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Sample records for calcium sulfate

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

    Energy Technology Data Exchange (ETDEWEB)

    Bizzozero, Julien, E-mail: julien.bizzozero@gmail.com; Scrivener, Karen L.

    2015-10-15

    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 and monocarboaluminate. Increasing the ratio between sulfate and aluminate decreases the extent of limestone reaction.

  2. Calcium sulfate in periodontics: A time tested versatile alloplast

    Directory of Open Access Journals (Sweden)

    Arnav Mukherji

    2016-01-01

    Full Text Available Calcium sulfate has multifaceted properties and has versatile use in the field of periodontal practice. Calcium sulfate can function as a resorbable space filler, a resorbable barrier (compatible with guided tissue regeneration principles, as a combination with other bone grafts in intrabony defects and in socket preservation procedures for implant placement. This review is an attempt to shed light on various applications of this bone graft in periodontal regeneration.

  3. The kinetics of sulfation of calcium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Sarofim, A.F.; Longwell, J.P.

    1990-01-01

    The rate of sulfation of a CaO surface is rapid at first, limited by the intrinsic kinetics, but slows down with increasing conversion as a consequence of the increased resistance to diffusion through the product layer. The objectives of this study are to determine the intrinsic kinetics and the product layer diffusion pate by minimizing the resistances to gas-phase pore diffusion, and eliminating complications due to pore filling. This is achieved by the use of nonporous CaO. A wide range of particle sizes are used to change the relative importance of the regimes in which the intrinsic kinetics and product layer diffusion control. The assumption of constant product layer diffusivity can then be tested and the variables that determine this diffusivity independently studied. Information on product layer diffusion can also be obtained from studies of porous particles after the pore mouths are all plugged and a uniform surface coating is obtained. This information on diffusion rate and intrinsic reactivity can then be combined with a geometrical model to describe the rate of reaction over the entire range of conversions and is particularly useful in treating the effect of particle size on conversion history.

  4. 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.

  5. 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.

  6. Modeling calcium sulfate chemistries with applications to Mars

    Science.gov (United States)

    Marion, G. M.; Catling, D. C.; Kargel, J. S.; Crowley, J. K.

    2016-11-01

    On Mars, evidence indicates widespread calcium sulfate minerals. Gypsum (CaSO4ṡ2H2O) seems to be the dominant calcium sulfate mineral in the north polar region of Mars. On the other hand, anhydrite (CaSO4) and bassanite (CaSO4ṡ0.5H2O) appear to be more common in large sedimentary deposits in the lower latitudes. The tropics are generally warmer and drier, and at least locally show evidence of acidic environments in the past. FREZCHEM is a thermodynamic modeling tool used for assessment of equilibrium involving high salinity solutions and salts, designed especially for low temperatures below 298 K (with one version adapted for temperatures up to 373 K), and we have used it to investigate many Earth, Mars, and other planetary science problems. Gypsum and anhydrite were included in earlier versions of FREZCHEM and our model Mars applications, but bassanite (the CaSO4 hemihydrate) has not previously been included. The objectives of this work are to (1) add bassanite to the FREZCHEM model, (2) examine the environments in which thermodynamic equilibrium precipitation of calcium sulfate minerals would be favored on Mars, and (3) use FREZCHEM to model situations where metastable equilibrium might be favored and promote the formation or persistence of one of these phases over the others in violation of an idealized equilibrium state. We added a bassanite equation based on high temperatures (343-373 K). A Mars simulation was based on a previously published Nasbnd Casbnd Mgsbnd Clsbnd SO4 system over the temperature range of 273 to 373 K. With declining temperatures, the first solid phase under equilibrium precipitation is anhydrite at 373 K, then gypsum forms at 319 K (46 °C), and epsomite (MgSO4ṡ7H2O) at 277 K. This sequence could reflect, for example, the precipitation sequence in a saturated solution that is slowly cooled in a deep, warm aquifer. Because FREZCHEM is based on thermodynamic equilibrium, a crude approach to problems involving metastable equilibria is

  7. Reactive Crystallization of Calcium Sulfate Dihydrate from Acidic Wastewater and Lime

    Institute of Scientific and Technical Information of China (English)

    邓立聪; 张亦飞; 陈芳芳; 曹绍涛; 游韶玮; 刘艳; 张懿

    2013-01-01

    The present work focused on the recycle of the sulfate and the metal ions from acidic wastewater dis-charged by nonferrous metallurgical industry. The effects of the temperature, the reactant concentration, the stirring speed and the metal ions on the reactive crystallization process of calcium sulfate between sulfuric acid and lime were systematically investigated. The morphology of the precipitated crystals evolved from platelet-like and nee-dle-like shape to rod-like shape when the temperature was increased from 25 to 70 °C. An increase in the agglom-eration of calcium sulfate was found with increasing lime concentration. Metal ions markedly retard the rate of crystallization of calcium sulfate dihydrate. The crystallization of gypsum was slowed with the existence of Mg2+in the solution, and the morphology of gypsum was transformed from platelet-like shape to rod-like shape when Mg2+concentration reached 0.08 mol·L-1. The amorphous ferric hydroxide was coated on the calcium sulfate after the co-precipitation process while Zn2+and Al3+ions in the solution enhanced the agglomeration of the calcium sulfate by absorbing on the surface of the crystals. Comprehensive acidic wastewater containing heavy metals was effi-ciently purified by the two stage lime neutralization technology, and highly agglomerated gypsum precipitates with needle-like shape were obtained. The precipitates could be purified by sulfuric acid washing, and the metal ions were effectively separated from the calcium sulfate by-products.

  8. Shape control synthesis of low-dimensional calcium sulfate

    Indian Academy of Sciences (India)

    Li-Xia Yang; Yan-Feng Meng; Ping Yin; Ying-Xia Yang; Ying-Ying Tang; Lai-Fen Qin

    2011-04-01

    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 by adjusting the volume ratio of ethanol/, -dimethylformamide to deionized water and the reaction time. Samples prepared at 35°C in mixed solvents of 50 mL ethanol and 30 mL water for 1 min and 2 h showed nanowire and sheet morphology, respectively. While increasing the volume ratio of ethanol to deionized water to 78/2, only nanorods were obtained. When , -dimethylformamide was employed to substitute ethanol, the sample heating at 35°C for 2 h was composed of nanowires in 50 mL , -dimethylformamide and 30 mL water. Higher volume ratio of , -dimethylformamide to deionized water caused the formation of nanorods.

  9. Structure, properties and animal study of a calcium phosphate/calcium sulfate composite cement.

    Science.gov (United States)

    Chen, Wei-Luen; Chen, Chang-Keng; Lee, Jing-Wei; Lee, Yu-Ling; Ju, Chien-Ping; Lin, Jiin-Huey Chern

    2014-04-01

    In-vitro and in-vivo studies have been conducted on an in-house-developed tetracalcium phosphate (TTCP)/dicalcium phosphate anhydrous (DCPA)/calcium sulfate hemihydrate (CSH)-derived composite cement. Unlike most commercial calcium-based cement pastes, the investigated cement paste can be directly injected into water and harden without dispersion. The viability value of cells incubated with a conditioned medium of cement extraction is >90% that of Al2O3 control and >80% that of blank medium. Histological examination reveals excellent bonding between host bone and cement without interposition of fibrous tissues. At 12 weeks-post implantation, significant remodeling activities are found and a new bone network is developed within the femoral defect. The 26-week samples show that the newly formed bone becomes more mature, while the interface between residual cement and the new bone appears less identifiable. Image analysis indicates that the resorption rate of the present cement is much higher than that of TTCP or TTCP/DCPA-derived cement under similar implantation conditions.

  10. Experimental study and modelling of sulfate sorption on calcium silicate hydrates; Etude experimentale et modelisation de l'adsorption de sulfates sur des silicates de calcium hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Barbarulo, R.; Peycelon, H. [CEA Saclay, Dept. de Physico-Chimie DPC/SCCME/LECBA, 91 - Gif sur Yvette (France); Prene, St. [Electricite de France, Dept. MMC, 77 - Moret sur Loing (France)

    2003-07-01

    A detailed study of the interactions between Calcium Silicate Hydrates (C-S-H) and sulfate is reported in this paper. C-S-H of Ca/Si ratio w 0.7-1.6 were synthesized from CaO and SiO{sub 2} in suspension, and Na{sub 2}SO{sub 4} was added to the system, kept at 20 or 85 deg C. The results of sulfate sorption show that the capacity of C-S-H to bind sulfate increases with the Ca/Si ratio of the C-S-H, and that temperature seems to have little influence for a given Ca/Si ratio. From these results, a modeling of sulfate binding on C-S-H is proposed. (authors)

  11. Tailored sequential drug release from bilayered calcium sulfate composites

    Energy Technology Data Exchange (ETDEWEB)

    Orellana, Bryan R.; Puleo, David A., E-mail: puleo@uky.edu

    2014-10-01

    The current standard for treating infected bony defects, such as those caused by periodontal disease, requires multiple time-consuming steps and often multiple procedures to fight the infection and recover lost tissue. Releasing an antibiotic followed by an osteogenic agent from a synthetic bone graft substitute could allow for a streamlined treatment, reducing the need for multiple surgeries and thereby shortening recovery time. Tailorable bilayered calcium sulfate (CS) bone graft substitutes were developed with the ability to sequentially release multiple therapeutic agents. Bilayered composite samples having a shell and core geometry were fabricated with varying amounts (1 or 10 wt.%) of metronidazole-loaded poly(lactic-co-glycolic acid) (PLGA) particles embedded in the shell and simvastatin directly loaded into either the shell, core, or both. Microcomputed tomography showed the overall layered geometry as well as the uniform distribution of PLGA within the shells. Dissolution studies demonstrated that the amount of PLGA particles (i.e., 1 vs. 10 wt.%) had a small but significant effect on the erosion rate (3% vs. 3.4%/d). Mechanical testing determined that introducing a layered geometry had a significant effect on the compressive strength, with an average reduction of 35%, but properties were comparable to those of mandibular trabecular bone. Sustained release of simvastatin directly loaded into CS demonstrated that changing the shell to core volume ratio dictates the duration of drug release from each layer. When loaded together in the shell or in separate layers, sequential release of metronidazole and simvastatin was achieved. By introducing a tunable, layered geometry capable of releasing multiple drugs, CS-based bone graft substitutes could be tailored in order to help streamline the multiple steps needed to regenerate tissue in infected defects. - Highlights: • Bilayered CS composites were fabricated as potential bone graft substitutes. • The shell

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

    OpenAIRE

    Ustinova Yuliya Valer'evna; Sivkov Sergey Pavlovich; Aleksashin Valeriy Mikhaylovich

    2012-01-01

    Currently, functional additives represented by many classes of substances and compounds, including polymers of different origin, are widely used in the production of dry mixtures based on gypsum binders. However, the impact of these additives produced on the formation of calcium sulfate dihydrate (CaSO42H2O) crystals in the course of the hardening of gypsum binders, is not quite clear. Therefore, the research is aimed at the clarification of the processes of growth and formation of calcium su...

  13. Tissue reaction and material biodegradation of a calcium sulfate/apatite biphasic bone substitute in rat muscle

    Directory of Open Access Journals (Sweden)

    Jian-Sheng Wang

    2016-07-01

    Conclusion: Calcium sulfate hydroxyapatite bone substitute can be used as a carrier for antibiotics or other drugs, without adverse reaction due to the fast resorption of the calcium sulfate. No bone formation was seen despite treating the bone substitute with autologous bone marrow.

  14. Effect of repeated vertical loads on microleakage of IRM and calcium sulfate-based temporary fillings.

    Science.gov (United States)

    Liberman, R; Ben-Amar, A; Frayberg, E; Abramovitz, I; Metzger, Z

    2001-12-01

    Temporary fillings are commonly used to seal endodontic access cavities between visits. IRM and Cavidentin were selected to represent two widely used groups of temporary filling materials. The first is a reinforced zinc oxide-eugenol preparation that is mixed at chairside, whereas the second is a ready-to-use calcium sulfate-based material that gained popularity due to its convenience of application. The seal provided by the aforementioned materials was studied using a radioactive tracer quantitative assay. When compared as passive temporary filling, the two provided a similar quality of seal. However, when subjected to repetitive "occlusal" cyclic loading of 4 kg, IRM was clearly superior to the calcium sulfate-based material. Whereas IRM maintained a reasonable seal, the calcium sulfate-based fillings deteriorated and lost the ability to seal. These results suggest that even though calcium sulfate-based materials may be useful when not subjected to any occlusal forces, IRM should be preferred whenever occlusal loads may be applied. Furthermore it is demonstrated that testing such materials for microleakage with no reference to mastication forces may be of limited value.

  15. Exploration of As(III)/As(V) Uptake from Aqueous Solution by Synthesized Calcium Sulfate Whisker☆

    Institute of Scientific and Technical Information of China (English)

    Xiaojuan Chen; Liuchun Yang; Junfeng Zhang; Yan Huang

    2014-01-01

    Although common calcium-containing minerals such as calcite and gypsum may fix arsenic, the interaction be-tween modified calcic minerals and arsenic has seldom been reported. The uptake behavior of As(III)/As(V) from aqueous solutions by calcium sulfate whisker (CSW, dihydrate or anhydrite) synthesized through a cooling recrystal ization method was explored. A series of batch experiments were conducted to examine the effect of pH, reaction time, whisker dosage, and initial As concentration. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the samples prepared. The results showed that pH of the aqueous solution was an important parameter for As(III)/As(V) uptake, and an excellent removal efficiency could be achieved under strongly alkaline condition. The data from batch experiments for reaction of As(V) with calcium sulfate dihydrate whisker (CSDW) and calcium sulfate anhydrous whisker (CSAW) were well described with extended Langmuir EXT1 model, from which theoretic maximum adsorption capacity of 46.57 mg As(V)·(g CSDW)−1 and 39.18 mg As(V)·(g CSAW)−1 were obtained. Some calcium arsenate solids products, such as CaAsO3(OH) (weilite, syn), Ca3(AsO4)2 (calcium arsenate), CaO–As2O5, Ca–As–O, Ca5(AsO4)3OH·xH2O (calcium arsenate hydroxide hydrate), and CaH(AsO4)·2H2O (hydrogen calcium arsenic oxide hydrate), were detected at pH = 12.5 through XRD analysis. This indicates that the interaction mechanism between As(V) and CSW is a complex adsorption process combined with surface dissolution and chemical precipitation.

  16. Effects of altered crystalline structure and increased initial compressive strength of calcium sulfate bone graft substitute pellets on new bone formation.

    Science.gov (United States)

    Urban, Robert M; Turner, Thomas M; Hall, Deborah J; Infanger, Susan I; Cheema, Naveed; Lim, Tae-Hong; Moseley, Jon; Carroll, Michael; Roark, Michael

    2004-01-01

    A new, modified calcium sulfate has been developed with a different crystalline structure and a compressive strength similar to many calcium phosphate materials, but with a resorption profile only slightly slower than conventional surgical-grade calcium sulfate. A canine bilateral defect model was used to compare restoration of defects treated with the modified calcium sulfate compared to treatment using conventional calcium sulfate pellets after 6, 13, and 26 weeks. The modified calcium sulfate pellets were as effective as conventional calcium sulfate pellets with regard to the area fraction and compressive strength of newly formed bone in the treated bone defects. Mechanical testing demonstrated that the initial compressive strength of the modified material was increased nearly three-fold compared to that of conventional surgical-grade calcium sulfate. This increase potentially allows for its use in a broader range of clinical applications, such as vertebral and subchondral defects.

  17. Use of calcium sulfate to accelerate densification while reducing greenhouse gas (GHG) emissions from oil sands tailings ponds

    Energy Technology Data Exchange (ETDEWEB)

    Bordenave, S.; Ramos, E.; Lin, S.; Voordouw, G.; Gieg, L. [Calgary Univ., AB (Canada). Petroleum Microbiology Research Group; Guo, C.; Wells, S. [Suncor Energy, Calgary, AB (Canada)

    2009-07-01

    Oil sands tailings ponds contain high volumes of fine tailings. Accelerated densification of the tailings can be achieved by adding calcium sulfate, and microbial activity has also been known to increase the tailings densification process. The presence of calcium sulfate can divert microbial activity from the production of methane. This study characterized the microbial processes in a tailings pond in order to estimate their contribution to tailings densification and greenhouse gas (GHG) emissions reductions. Sulfate and sulfide concentrations were measured. Rates of microbial sulfate reduction and methanogenesis were measured as a function of depth in a pond treated with calcium sulfate. Samples were collected at various depths from a tailings pond in northern Alberta. The study showed that the highest rates of methanogenesis occurred in areas where sulfate reduction rates were low. Fluctuating rates of sulfate reduction demonstrated that different microbial activities occurred at discrete levels in the pond. The study suggested that sulfide formed by the reduction of sulfate at depth is carried upwards in gas bubbles and then oxidized back into sulfate in the upper oxygenated layers of the pond. It was concluded that when used as a consolidation agent, calcium sulfate reduces GHG emissions from tailings ponds. 13 refs., 3 figs.

  18. Nucleation kinetics of the formation of low dimensional calcium sulfate dihydrate crystals in isopropyl alcohol medium

    Energy Technology Data Exchange (ETDEWEB)

    Sandhya, S.; Sureshbabu, S.; Varma, H.K.; Komath, Manoj [Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695 012 (India)

    2012-07-15

    Calcium sulfate dihydrate, constituted as uniform crystals of low dimensions, is a potential biomaterial for clinical applications like bone graft substitution and drug delivery. In this work, isopropyl alcohol has been used as a solvent to obtain low dimensional calcium sulfate dihydrate crystals from calcium nitrate - sulfuric acid system. Reactants in 0.5 molar concentration at ambient conditions generated uniform rod-shaped crystals of length 3-5 {mu}m. Analysis using X-ray Diffractometry and Fourier Transform Infrared Spectrometry showed the material to be well crystallized, phase-pure calcium sulfate dihydrate. The nucleation kinetics has been studied by observing the induction time of phase formation in solutions of millimolar concentrations through turbidimetry at 300 K. The data have been analysed using classical nucleation theory to deduce parameters like interfacial tension (or surface free energy), nucleation rate and critical radius. The surface free energy obtained (5.6 mJ/m{sup 2}) is comparatively lower than that reported for aqueous precipitation, which could be attributed to the presence of isopropyl alcohol. On escalating the supersaturation ratio, the nucleation rate drastically increased and the critical radius decreased exponentially. Particles formed at supersaturation 1.39 showed a monomodal distribution centered at 8.2 nm in Dynamic Light Scattering analysis. Comparable particle sizes were obtained in Transmission Electron Microscopy. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. 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.

  20. Inhibition of the Crystal Growth and Aggregation of Calcium Oxalate by Algae Sulfated Polysaccharide In-vitro

    Institute of Scientific and Technical Information of China (English)

    Xiu Mei WU; Jian Ming OUYANG; Sui Ping DENG; Ying Zhou CEN

    2006-01-01

    The influence of sulfated polysaccharide (SPS) isolated from marine algae Sargassum fusiforme on the morphology and phase compositions of urinary crystal calcium oxalate was investigated in vitro by means of scanning electron microscopy and X-ray diffraction. SPS maybe is a potential inhibitor to CaOxa urinary stones by inhibiting the growth of calcium oxalate monohydrate (COM), preventing the aggregation of COM, and inducing the formation of calcium oxalate dihydrate (COD) crystals.

  1. Calcium sulfate combined with guided tissue regeneration: A novel technique in treatment of gingival recessions.

    Science.gov (United States)

    Mukherji, Arnav

    2016-01-01

    The presence of mucogingival problem around anterior teeth is a challenge to the clinician as not only biological and functional aspects has to be addressed but esthetic aspirations of the patient have to be met. The use of guided tissue regeneration (GTR) procedures for the treatment of gingival recession has shown encouraging results and is gaining clinical acceptance. However, maintenance of space under the membrane remains a problem for clinicians. Hence, this case study was an innovative attempt to evaluate the effect of adjunctive calcium sulfate placement along with collagen membrane GTR-based root coverage procedure.

  2. Calcium sulfate combined with guided tissue regeneration: A novel technique in treatment of gingival recessions

    Directory of Open Access Journals (Sweden)

    Arnav Mukherji

    2016-01-01

    Full Text Available The presence of mucogingival problem around anterior teeth is a challenge to the clinician as not only biological and functional aspects has to be addressed but esthetic aspirations of the patient have to be met. The use of guided tissue regeneration (GTR procedures for the treatment of gingival recession has shown encouraging results and is gaining clinical acceptance. However, maintenance of space under the membrane remains a problem for clinicians. Hence, this case study was an innovative attempt to evaluate the effect of adjunctive calcium sulfate placement along with collagen membrane GTR-based root coverage procedure.

  3. Calcium Sulfate Characterized by Chemcam/Curiousity at Gale Crater, Mars

    Science.gov (United States)

    Nachon, M.; Clegg, S. M.; Mangold, N.; Schroeder, S.; Kah, L. C.; Dromart, G.; Ollila, A.; Johnson, J. R; Oehler, D. Z.; Bridges, J. C.; LeMouelic, S.; Forni, O.; Wiens, R. C.; Anderson, R. B.; Blaney, D. L.; Bell, J. F., III; Clark, B.; Cousin, A.; Dyar, M. D.; Ehlmann, B.; Fabre, C.; Gasnault, O.; Grotzinger, J.; Lasue, J.; Stack, K.

    2014-01-01

    Onboard the Mars Science Laboratory (MSL) Curiosity rover, the ChemCam instrument consists of : (1) a Laser-Induced Breakdown Spectrometer (LIBS) for elemental analysis of the targets and (2) a Remote Micro Imager (RMI), for the imaging context of laser analysis. Within the Gale crater, Curiosity traveled from Bradbury Landing through the Rocknest region and into Yellowknife Bay (YB). In the latter, abundant light-toned fracture-fill material occur. ChemCam analysis demonstrates that those fracture fills consist of calcium sulfates.[

  4. Calcium Sulfate Characterized by ChemCam/Curiosity at Gale Crater, Mars

    Science.gov (United States)

    Nachon, M.; Clegg, S. N.; Mangold, N.; Schroeder, S.; Kah, L. C.; Dromart, G.; Ollila, A.; Johnson, J. R.; Oehler, D. Z.; Bridges, J. C.; LeMouelic, S.; Forni, O.; Wiens, R. C.; Rapin, W.; Anderson, R. B.; Blaney, D. L.; Bell, J. F. , III; Clark, B.; Cousin, A.; Dyar, M. D.; Ehlmann, B.; Fabre, C.; Gasnault, O.; Grotzinger, J.; Lasue, J.; Lewin, E.; Leveille, R.; McLennan, S.; Maurice, S.; Meslin, P.-Y.; Rice, M.; Squyres, S. W.; Stack, K.; Sumner, D. Y.; Vaniman, D.; Wellington, D.

    2014-01-01

    Onboard the Mars Science Laboratory (MSL) Curiosity rover, the ChemCam instrument consists of :(1) a Laser-Induced Breakdown Spectrometer (LIBS) for elemental analysis of the targets [1;2] and (2) a Remote Micro Imager (RMI), for the imaging context of laser analysis [3]. Within the Gale crater, Curiosity traveled from Bradbury Landing through the Rocknest region and into Yellowknife Bay (YB). In the latter, abundant light-toned fracture-fill material were seen [4;5]. ChemCam analysis demonstrate that those fracture fills consist of calcium sulfates [6].

  5. Bioactive calcium sulfate/magnesium phosphate cement for bone substitute applications

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Guangyong [Department of Orthopaedics, Taizhou Hospital of Zhejiang Province, Linhai Zhejiang, 317000 (China); Department of Orthopaedic Surgery, Second Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, 325000 (China); Liu, Jianli [Trauma Center, Affiliated Hospital of Hainan Medical University, Haikou, Hainan, 570206 (China); Division of Functional Materials and Nanodevices, Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo, Zhejiang, 315201 (China); Li, Fan; Pan, Zongyou; Ni, Xiao; Shen, Yue [Department of Orthopaedic Surgery, Second Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, 325000 (China); Xu, Huazi, E-mail: spinexu@163.com [Department of Orthopaedic Surgery, Second Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, 325000 (China); Huang, Qing, E-mail: huangqing@nimte.ac.cn [Division of Functional Materials and Nanodevices, Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo, Zhejiang, 315201 (China)

    2014-02-01

    A novel calcium sulfate/magnesium phosphate cement (CSMPC) composite was prepared and studied in the present work. The physical properties including the phases, the microstructures, the setting properties and the compressive strengths of the CSMPCs were studied. The bio-performances of the CSMPCs were comprehensively evaluated using in vitro simulated body fluid (SBF) method and in vitro cell culture. The dependence of the physical and chemical properties of the CSMPC on its composition and microstructure was studied in detail. It is found that the CSMPC composites exhibited mediate setting times (6–12 min) compared to the calcium sulfate (CS) and the magnesium phosphate cement (MPC). They showed an encapsulation structure in which the unconverted hexagonal prism CSH particles were embedded in the xerogel-like MPC matrix. The phase compositions and the mechanical properties of the CSMPCs were closely related to the content of MPC and the hardening process. The CSMPCs exhibited excellent bioactivity and good biocompatibility to support the cells to attach and proliferate on the surface. The CSMPC composite has the potential to serve as bone grafts for the bone regeneration. - Highlights: • The mechanical strength and degradation rate of CSMPC composites are discussed. • The CSMPC composites exhibited good bioactivity to form bone-like apatite. • The CSMPC composites also show good biocompatibility.

  6. Bioactive calcium sulfate/magnesium phosphate cement for bone substitute applications.

    Science.gov (United States)

    Yang, Guangyong; Liu, Jianli; Li, Fan; Pan, Zongyou; Ni, Xiao; Shen, Yue; Xu, Huazi; Huang, Qing

    2014-02-01

    A novel calcium sulfate/magnesium phosphate cement (CSMPC) composite was prepared and studied in the present work. The physical properties including the phases, the microstructures, the setting properties and the compressive strengths of the CSMPCs were studied. The bio-performances of the CSMPCs were comprehensively evaluated using in vitro simulated body fluid (SBF) method and in vitro cell culture. The dependence of the physical and chemical properties of the CSMPC on its composition and microstructure was studied in detail. It is found that the CSMPC composites exhibited mediate setting times (6-12 min) compared to the calcium sulfate (CS) and the magnesium phosphate cement (MPC). They showed an encapsulation structure in which the unconverted hexagonal prism CSH particles were embedded in the xerogel-like MPC matrix. The phase compositions and the mechanical properties of the CSMPCs were closely related to the content of MPC and the hardening process. The CSMPCs exhibited excellent bioactivity and good biocompatibility to support the cells to attach and proliferate on the surface. The CSMPC composite has the potential to serve as bone grafts for the bone regeneration.

  7. Synthesis and characterization of nanocrystalline calcium sulfate for use in osseous regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Park, Young Bum; Dziak, Rosemary [Yonsei University College of Dentistry, 250 Seongsanno, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Mohan, Kathiravan [Advanced and Comfort Dentistry, 3655 Municipal Dr., Whitehall-Hokendauqua, PA 18052 (United States); Al-Sanousi, Abdulazi [Health Science Center, PO Box 24923, Safat 13110 (Kuwait); Almaghrabi, Bandar; Genco, Robert J [Department of Oral Biology, University at Buffalo (SUNY), 320 Foster Hall, South Campus, Buffalo, NY 14214 (United States); Swihart, Mark T, E-mail: rdziak@buffalo.edu [Department of Chemical and Biological Engineering, University at Buffalo (SUNY), 303 Furnas Hall, Buffalo, NY 14260-4200 (United States)

    2011-10-15

    Nanoparticles of calcium sulfate (nCS) have potential advantages as a ceramic matrix, scaffold and/or vehicle for delivering growth factors for osseous regeneration in a variety of clinical situations. The objectives of this study were to synthesize and characterize nanoparticles of hemihydrate calcium sulfate (nCS) and to develop a nCS-based system for bone regeneration. A cryo-vacuum method was used to process dihydrate CS into dihydrate nCS, which was then subjected to oven drying to produce hemihydrate. The nCS was sterilized by glow discharge treatment for use as a synthetic graft material for the treatment of bone defects. Electron microscopy showed that the nCS powder consisted of aggregates of closely arranged acicular crystals, approximately 30-80 nm in width, 400-600 nm in length and approximately 80-100 nm in diameter, providing a surface area about ten times that of conventional CS. Thorough physico-chemical characterization confirmed the composition and phase of the material. Cell viability/metabolic activity assays and alkaline phosphate assays confirmed the safety and biocompatibility of nCS. Release kinetics for adsorbed platelet-derived growth factor and bone morphogenetic protein-2 (BMP-2) suggests that nCS may serve as an appropriate vehicle for slow release delivery of these agents. The studies presented here give evidence of the advantages of nCS as a scaffold to support osteoblastic cell activity.

  8. Calcium Sulfate and Platelet-Rich Plasma make a novel osteoinductive biomaterial for bone regeneration

    Directory of Open Access Journals (Sweden)

    Intini Francesco E

    2007-03-01

    Full Text Available Abstract Background With the present study we introduce a novel and simple biomaterial able to induce regeneration of bone. We theorized that nourishing a bone defect with calcium and with a large amount of activated platelets may initiate a series of biological processes that culminate in bone regeneration. Thus, we engineered CS-Platelet, a biomaterial based on the combination of Calcium Sulfate and Platelet-Rich Plasma in which Calcium Sulfate also acts as an activator of the platelets, therefore avoiding the need to activate the platelets with an agonist. Methods First, we tested CS-Platelet in heterotopic (muscle and orthotopic (bone bone regeneration bioassays. We then utilized CS-Platelet in a variety of dental and craniofacial clinical cases, where regeneration of bone was needed. Results The heterotopic bioassay showed formation of bone within the muscular tissue at the site of the implantation of CS-Platelet. Results of a quantitative orthotopic bioassay based on the rat calvaria critical size defect showed that only CS-Platelet and recombinant human BMP2 were able to induce a significant regeneration of bone. A non-human primate orthotopic bioassay also showed that CS-Platelet is completely resorbable. In all human clinical cases where CS-Platelet was used, a complete bone repair was achieved. Conclusion This study showed that CS-Platelet is a novel biomaterial able to induce formation of bone in heterotopic and orthotopic sites, in orthotopic critical size bone defects, and in various clinical situations. The discovery of CS-Platelet may represent a cost-effective breakthrough in bone regenerative therapy and an alternative or an adjuvant to the current treatments.

  9. Sulfato de calcio: propiedades y aplicaciones clínicas Calcium sulfate: properties and clinical applications

    Directory of Open Access Journals (Sweden)

    J López

    2011-12-01

    Full Text Available Durante más de cien años el sulfato de calcio se ha distinguido de otros biomateriales, por ser uno de los materiales aloplásticos más simples y que presenta la más larga historia clínica como material sintético. Entre sus principales propiedades destacan que es de fácil obtención, capacidad de osteoconducción, es totalmente absorbible, no provoca reacciones de inflamación o antigénicas, fácil modelado y fuerza de compresión semejante al tejido óseo. Todas éstas características son necesarias para ser usado como sustituto óseo. Sin embargo, diferencias en la morfología y estructura de sus cristales, la porosidad, propiedades mecánicas y en la constitución química del sulfato de calcio puede alterar significativamente sus propiedades biológicas. El objetivo de la presente revisión es conocer las propiedades del sulfato de calcio y sus diferentes aplicaciones clínicas como sustituto óseo en procedimientos regenerativos.For over 100 years, the calcium sulfate has stood out from other biomaterials, for being one of the simplest alloplastic materials and having the longest history as synthetic material. It is readily available, has osteoconductive properties, is completely absorbed, does not cause inflammation or antigenic reactions, can be modeled to defect, has compressive strength similar to bone tissue and can be used as a vehicle for in situ release of chemotherapeutic agents. All these features are required to be used as a bone substitute. However, differences in morphology, crystal structure, porosity, mechanical properties and chemical constitution of calcium sulfate can significantly alter its biological properties. The aim of this study was to determine through a review of the literature, the properties of calcium sulfate and its various clinical applications as bone substitute in regenerative procedures.

  10. 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.

  11. Hydration state of calcium sulfates in Gale crater, Mars: Identification of bassanite veins

    Science.gov (United States)

    Rapin, W.; Meslin, P.-Y.; Maurice, S.; Vaniman, D.; Nachon, M.; Mangold, N.; Schröder, S.; Gasnault, O.; Forni, O.; Wiens, R. C.; Martínez, G. M.; Cousin, A.; Sautter, V.; Lasue, J.; Rampe, E. B.; Archer, D.

    2016-10-01

    In-situ analyses reveal the presence of hydrogen within calcium sulfate veins crosscutting the sediments found in Gale crater. Laboratory experiments were performed to calibrate the hydrogen signal measured by laser induced breakdown spectroscopy (LIBS) in a range applicable to martian data. The analyses indicate that all veins targeted so far at Gale consist predominantly of bassanite which most likely formed by dehydration of gypsum. This scenario suggests that the percolating water produced gypsum, possibly by hydration of anhydrite in aqueous solution, and remained at temperatures below ∼60 °C at that time. Desiccating conditions followed, consistent with a hyperarid climate and favored by burial or impacts. Additionally, anhydrite with lesser bassanite has been found by XRD in samples of sediments hosting the veins. Our result suggests bassanite is likely found in the veins and anhydrite may be more common as a fine-grained component within the sediments.

  12. Tunable Degradation Rate and Favorable Bioactivity of Porous Calcium Sulfate Scaffolds by Introducing Nano-Hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Jianhua Zhou

    2016-12-01

    Full Text Available The bone scaffolds should possess suitable physicochemical properties and osteogenic activities. In this study, porous calcium sulfate (CaSO4 scaffolds were fabricated successfully via selected laser sintering (SLS. Nano-hydroxyapatite (nHAp, a bioactive material with a low degradation rate, was introduced into CaSO4 scaffolds to overcome the overquick absorption. The results demonstrated that nHAp could not only control the degradation rate of scaffolds by adjusting their content, but also improve the pH environment by alleviating the acidification progress during the degradation of CaSO4 scaffolds. Moreover, the improved scaffolds were covered completely with the apatite spherulites in simulated body fluid (SBF, showing their favorable bioactivity. In addition, the compression strength and fracture toughness were distinctly enhanced, which could be ascribed to large specific area of nHAp and the corresponding stress transfer.

  13. Augmentation of screw fixation with injectable calcium sulfate bone cement in ovariectomized rats.

    Science.gov (United States)

    Yu, Xiao-Wei; Xie, Xin-Hui; Yu, Zhi-Feng; Tang, Ting-Ting

    2009-04-01

    The objective of this study was to determine the effect of augmenting screw fixation with an injectable calcium sulfate cement (CSC) in the osteoporotic bone of ovariectomized rats. The influence of the calcium sulfate (CS) on bone remodeling and screw anchorage in osteoporotic cancellous bone was systematically investigated using histomorphometric and biomechanical analyses. The femoral condyles of 55 Sprague-Dawley ovariectomized rats were implanted with screw augmented with CS, while the contralateral limb received a nonaugmented screw. At time intervals of 2, 4, 8, 12, and 16 weeks, 11 rats were euthanized. Six pair-matched samples were used for histological analysis, while five pair-matched samples were preserved for biomechanical testing. Histomorphometric data showed that CS augmented screws activated cancellous bone formation, evidenced by a statistically higher (p < 0.05) percentage of osteoid surface at 2, 4, and 8 weeks and a higher rate of bone mineral apposition at 12 weeks compared with nonaugmented screws. The amount of the bone-screw contact at 2, 8, and 12 weeks and of bone ingrowth on the threads at 4 and 8 weeks was greater in the CS group than in the nonaugmented group (p < 0.05), although these parameters increased concomitantly with time for both groups. The CS was resorbed completely at 8 weeks without stimulating fibrous encapsulation on the screw surface. Also, the cement significantly increased the screw pull-out force and the energy to failure at 2, 4, 8, and 12 weeks after implantation, when compared with the control group (p < 0.05). These results imply that augmentation of screw fixation with CS may have the potential to decrease the risk of implant failure in osteoporotic bone.

  14. Synthesis, characterization and in vitro study of magnetic biphasic calcium sulfate-bioactive glass

    Energy Technology Data Exchange (ETDEWEB)

    Goh, Yi-Fan; Akram, Muhammad; Alshemary, Ammar Z. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Darul Ta' zim (Malaysia); Hussain, Rafaqat, E-mail: rafaqat@kimia.fs.utm.my [Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor Darul Ta' zim (Malaysia)

    2015-08-01

    Calcium sulfate-bioactive glass (CSBG) composites doped with 5, 10 and 20 mol% Fe were synthesized using quick alkali sol–gel method. X-ray diffraction (XRD) data of samples heated at 700 °C revealed the presence of anhydrite, while field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) characterization confirmed the formation of nano-sized CSBGs. The UV–vis studies confirmed that the main iron species in 5% Fe and 10% Fe doped CSBGs were tetrahedral Fe(III) whereas that in 20% Fe doped CSBG were extra-framework FeO{sub x} oligomers or iron oxide phases. Measurement of magnetic properties of the samples by vibrating sample magnetometer (VSM) showed very narrow hysteresis loop with zero coercivity and remanence for 10% Fe and 20% Fe doped CSBG, indicating that they are superparamagnetic in nature. All samples induced the formation of apatite layer with Ca/P ratio close to the stoichiometric HA in simulated body fluid (SBF) assessment. - Highlights: • Biphasic calcium sulphate-bioactive glass containing iron was prepared. • Composite bioglass was superparamagnetic in nature. • All samples promoted the growth of apatite layer with Ca/P close to 1.67.

  15. Structure, Properties, and In Vitro Behavior of Heat-Treated Calcium Sulfate Scaffolds Fabricated by 3D Printing.

    Directory of Open Access Journals (Sweden)

    Mitra Asadi-Eydivand

    Full Text Available The ability of inkjet-based 3D printing (3DP to fabricate biocompatible ceramics has made it one of the most favorable techniques to generate bone tissue engineering (BTE scaffolds. Calcium sulfates exhibit various beneficial characteristics, and they can be used as a promising biomaterial in BTE. However, low mechanical performance caused by the brittle character of ceramic materials is the main weakness of 3DP calcium sulfate scaffolds. Moreover, the presence of certain organic matters in the starting powder and binder solution causes products to have high toxicity levels. A post-processing treatment is usually employed to improve the physical, chemical, and biological behaviors of the printed scaffolds. In this study, the effects of heat treatment on the structural, mechanical, and physical characteristics of 3DP calcium sulfate prototypes were investigated. Different microscopy and spectroscopy methods were employed to characterize the printed prototypes. The in vitro cytotoxicity of the specimens was also evaluated before and after heat treatment. Results showed that the as-printed scaffolds and specimens heat treated at 300°C exhibited severe toxicity in vitro but had almost adequate strength. By contrast, the specimens heat treated in the 500°C-1000°C temperature range, although non-toxic, had insufficient mechanical strength, which was mainly attributed to the exit of the organic binder before 500°C and the absence of sufficient densification below 1000°C. The sintering process was accelerated at temperatures higher than 1000°C, resulting in higher compressive strength and less cytotoxicity. An anhydrous form of calcium sulfate was the only crystalline phase existing in the samples heated at 500°C-1150°C. The formation of calcium oxide caused by partial decomposition of calcium sulfate was observed in the specimens heat treated at temperatures higher than 1200°C. Although considerable improvements in cell viability of heat

  16. Structure, Properties, and In Vitro Behavior of Heat-Treated Calcium Sulfate Scaffolds Fabricated by 3D Printing.

    Science.gov (United States)

    Asadi-Eydivand, Mitra; Solati-Hashjin, Mehran; Shafiei, Seyedeh Sara; Mohammadi, Sepideh; Hafezi, Masoud; Abu Osman, Noor Azuan

    2016-01-01

    The ability of inkjet-based 3D printing (3DP) to fabricate biocompatible ceramics has made it one of the most favorable techniques to generate bone tissue engineering (BTE) scaffolds. Calcium sulfates exhibit various beneficial characteristics, and they can be used as a promising biomaterial in BTE. However, low mechanical performance caused by the brittle character of ceramic materials is the main weakness of 3DP calcium sulfate scaffolds. Moreover, the presence of certain organic matters in the starting powder and binder solution causes products to have high toxicity levels. A post-processing treatment is usually employed to improve the physical, chemical, and biological behaviors of the printed scaffolds. In this study, the effects of heat treatment on the structural, mechanical, and physical characteristics of 3DP calcium sulfate prototypes were investigated. Different microscopy and spectroscopy methods were employed to characterize the printed prototypes. The in vitro cytotoxicity of the specimens was also evaluated before and after heat treatment. Results showed that the as-printed scaffolds and specimens heat treated at 300°C exhibited severe toxicity in vitro but had almost adequate strength. By contrast, the specimens heat treated in the 500°C-1000°C temperature range, although non-toxic, had insufficient mechanical strength, which was mainly attributed to the exit of the organic binder before 500°C and the absence of sufficient densification below 1000°C. The sintering process was accelerated at temperatures higher than 1000°C, resulting in higher compressive strength and less cytotoxicity. An anhydrous form of calcium sulfate was the only crystalline phase existing in the samples heated at 500°C-1150°C. The formation of calcium oxide caused by partial decomposition of calcium sulfate was observed in the specimens heat treated at temperatures higher than 1200°C. Although considerable improvements in cell viability of heat-treated scaffolds were

  17. Effects of spermidine and calcium sulfate on quantitative and qualitative traits and vase life of rose (Rosa hybrida cv. Dolcvita grown in hydroponic system

    Directory of Open Access Journals (Sweden)

    M. Hosseini Farahi

    2013-07-01

    Full Text Available In order to improve quantitative and qualitative properties and vase life of rose cv. Dolcvita, an experiment was conducted in a randomized complete blocks design with ten treatments and three replications in a hydroponic greenhouse adjacent to Yasouj city, Iran. Treatments included control, spermidine (0.5, 1 and 1.5 mM, calcium sulfate (2.5 and 5 mM, spermidine 0.5 mM+ calcium sulfate 2.5 mM, spermidine 0.5 mM + calcium sulfate 5 mM, spermidine 1 mM + calcium sulfate 2.5 mM and spermidine 1 mM + calcium sulfate 5 mM. Traits such as length of flower stalk, stem diameter, flower bud diameter, fresh weight of stem, chlorophyll content and vase life were measured. Results showed that effect of spermidine and calcium sulfate on all traits, except chlorophyll content, was significant (P<0.05. The highest and lowest length of flower stalk, stem diameter and fresh weight of stem was obtained in the 1.5 mM spermidine and control treatments, respectively. The highest diameter of flower bud was observed in the 0.5 mM spermidine and 2.5 mM calcium sulfate treatments. Flower vase life in the 0.5 mM spermidine + 5 mM calcium sulfate treatment was higher than that in the other treatments. Therefore, application of 1.5 mM spermidine is recommended for improving quantitative properties and combination of 0.5 mM spermidine with 5 mM calcium sulfate for increasing vase life of rose, cultivar Dolcvita, in hydroponic system.

  18. Improvement of in vitro physicochemical properties and osteogenic activity of calcium sulfate cement for bone repair by dicalcium silicate

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chun-Cheng [School of Dentistry, Chung Shan Medical University, Taichung City 402, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung City 402, Taiwan (China); Wang, Chien-Wen [Department of Biomedical Engineering, National Cheng Kung University, Tainan City 701, Taiwan (China); Hsueh, Nai-Shuo [Institute of Oral Science, Chung Shan Medical University, Taichung City 402, Taiwan (China); Ding, Shinn-Jyh, E-mail: sjding@csmu.edu.tw [School of Dentistry, Chung Shan Medical University, Taichung City 402, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung City 402, Taiwan (China); Institute of Oral Science, Chung Shan Medical University, Taichung City 402, Taiwan (China)

    2014-02-05

    Highlights: • Dicalcium silicate can improve osteogenic activity of calcium sulfate cement. • The higher the calcium sulfate content, the shorter the setting time in the composite cement. • The results were useful for designing calcium-based cement with optimal properties. -- Abstract: An ideal bone graft substitute should have the same speed of degradation as formation of new bone tissue. To improve the properties of calcium sulfate hemihydrate (CSH) featured for its rapid resorption, a low degradation material of dicalcium silicate (DCS) was added to the CSH cement. This study examined the effect of DCS (20, 40, 60 and 80 wt%) on the in vitro physicochemical properties and osteogenic activities of the calcium-based composite cements. The diametral tensile strength, porosity and weight loss of the composite cements were evaluated before and after soaking in a simulated body fluid (SBF). The osteogenic activities, such as proliferation, differentiation and mineralization, of human mesenchymal stem cells (hMSCs) seeded on cement surfaces were also examined. As a result, the greater the DCS amount, the higher the setting time was in the cement. Before soaking in SBF, the diametral tensile strength of the composite cements was decreased due to the introduction of DCS. On 180-day soaking, the composite cements containing 20, 40, 60 and 80 wt% DCS lost 80%, 69%, 61% and 44% in strength, respectively. Regarding in vitro bioactivity, the DCS-rich cements were covered with clusters of apatite spherulites after soaking for 7 days, while there was no formation of apatite spherulites on the CSH-rich cement surfaces. The presence of DCS could reduce the degradation of the CSH cements, as evidenced in the results of weight loss and porosity. More importantly, DCS may promote effectively the cell proliferation, proliferation and mineralization. The combination of osteogenesis of DCS and degradation of CSH made the calcium-based composite cements an attractive choice for

  19. Influence of Calcium Sulfate State and Fineness of Cement on Hydration of Portland Cements Using Electrical Measurement

    Institute of Scientific and Technical Information of China (English)

    WEI Xiaosheng; LI Zongjin; XIAO Lianzhen; THONG Wangfai

    2006-01-01

    The influence of calcium sulfate state and fineness of cement on hydration of Portland cement was studied using electrical resistivity measurement. The bulk resistivity curve of the paste from the abnormal cement mainly with hemihydrate had a characteristic abnormal peak and rapid increase in early period. The resistivity measurement technique can be used to discriminate abnormal setting. For normal cement with gypsum, the increase in fineness of the Portland cement decreases the minimum resistivity due to a higher ionic concentration and increases the 24 hour resistivity due to a reduction in macroscopic pore size. Thesetting time, compressive strength, pore structure of pastes made from different cements were carried out to compare the influence of water to cement ratio, calcium sulfate state and fineness. It is found that the electrical and mechanical properties are strongly affected by the initial porosity, the presence of hemihydrate or gypsum, and the fineness of cement.

  20. Fabrication of biodegradable composite microneedles based on calcium sulfate and gelatin for transdermal delivery of insulin.

    Science.gov (United States)

    Yu, Weijiang; Jiang, Guohua; Liu, Depeng; Li, Lei; Chen, Hua; Liu, Yongkun; Huang, Qin; Tong, Zaizai; Yao, Juming; Kong, Xiangdong

    2017-02-01

    To reduce the inconvenience and pain of subcutaneous needle injection, the calcium sulfate and gelatin biodegradable composite microneedle patches with high aspect-ratio microneedles (MNs) and a flexible substrate have been developed. The microneedles with an aspect-ratio approximate 6:1 exhibit excellent mechanical property which can achieve 0.4N for each needle. The cross-section views show the inside of microneedles that have abundant pores and channels which offer potential for different drug-release profiles. The preparation procedures, degradable property for the biodegradable composite microneedle patches are described in the paper. Insulin, the drug to control blood glucose levels in diabetic patients, has been embedded into the biodegradable composite MNs. The hypoglycemic effect for transdermal delivery of insulin is studied using diabetic Sprague-Dawley (SD) rats as models in vivo. After transdermal administration to the diabetic rats, the released insulin from biodegradable composite MNs exhibit an obvious and effective hypoglycemic effect for longer time compared with that of subcutaneous injection route. This work suggests that biodegradable composite MNs containing of insulin have a potential application in diabetes treatment via transdermal ingestion.

  1. Properties and Osteogenicity of Two Calcium Sulfate Materials with Micro or Nano Morphology.

    Science.gov (United States)

    Zhang, Chunli; Li, Zhonghai; Li, Qihong; Han, Liwei; Zhu, Jialiang; Bai, Yulong; Ge, Cheng; Zhao, Yantao; Zhong, Hongbin

    2016-03-01

    Calcium sulfate dihydrate (CaSO4 x 2H2O, CSD) was widely used as the artificial bone graft. In this study, two kinds of CSD materials were characterized with XRD, TG/DTA, FT-IR, and SEM. They were both composed of CSD. Spherical shape particles were observed for nano-CSD with diameters of 52-300 nm. The micro-CSD were thin sheet particles with dimensions of 5-10 μm. At 56 days post-implantation in vivo, nano-CSD had good tissue compatibility. A frequently used bioactive material DBM, which was the combination of nano-CSD (nano-CSD-DBM) and micro-CSD (micro-CSD-DBM) in a 1:1 weight ratio separately. Composite materials were implanted in intramuscular pockets in nude mouse model. New bone mineralization could be both observed in the surgery site. Collagen I was also widely distributed by immunohistochemistry assay. And new bone area of nano-CSD-DBM was 28 ± 4.6% at 4 weeks post-operation. But new bone area of micro-CSD-DBM was 16 ± 3.7% (less than nano-CSD-DBM). Nano-CSD showed increased degradation rate with obvious anginogenicity. And nano-CSD-DBM showed more excellent bone induction property as bone substitute implant.

  2. Enhanced Stability of Calcium Sulfate Scaffolds with 45S5 Bioglass for Bone Repair

    Directory of Open Access Journals (Sweden)

    Cijun Shuai

    2015-11-01

    Full Text Available Calcium sulfate (CaSO4, as a promising tissue repair material, has been applied widely due to its outstanding bioabsorbability and osteoconduction. However, fast disintegration, insufficient mechanical strength and poor bioactivity have limited its further application. In the study, CaSO4 scaffolds fabricated by using selective laser sintering were improved by adding 45S5 bioglass. The 45S5 bioglass enhanced stability significantly due to the bond effect of glassy phase between the CaSO4 grains. After immersing for four days in simulated body fluid (SBF, the specimens with 45S5 bioglass could still retain its original shape compared as opposed to specimens without 45S5 bioglass who experienced disintegration. Meanwhile, its compressive strength and fracture toughness increased by 80% and 37%, respectively. Furthermore, the apatite layer was formed on the CaSO4 scaffolds with 45S5 bioglass in SBF, indicating good bioactivity of the scaffolds. In addition, the scaffolds showed good ability to support the osteoblast-like cell adhesion and proliferation.

  3. Thermal simulation experiments of saturated hydrocarbons with calcium sulfate and element sulfur: Implications on origin of H2S

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Temperature-programmed simulation experiments of saturated hydrocarbons with calcium sulfate and element sulfur were compared in this study. Based on the variation analysis of the yields and evolvement features of gaseous hydrocarbon (C1-C5) and inorganic gaseous CO2, H2 and H2S, the reaction mechanisms were analyzed and discussed. In the calcium sulfate-saturated hydrocarbon system, H2S was produced by a small quantity, which indicates this reaction belongs to the low-degreed thermal sulfate reduction (TSR) and is featured of self-pyrolysis. In the sulfur-saturated hydrocarbon system, the heated sulfur becomes sulfur radical, which has strong catalysis capability and can fasten the cracking of C―H bond in the alkyl group in the saturated hydrocarbons. As a result, the cracking of C―H bond leads to the yields enhancement of CO2 and H2, and at the same time, H2S was produced since the cracked hydrogen can be instantly combined with sulfur radical. Therefore, this reaction in the sulfur-hydrocarbon system belongs to the catalysis of sulfur radical. Furthermore, the promoted pyrolysis effects of C6+ hydrocarbons by sulfur radical in the low-temperature stage in the sul- fur-hydrocarbon system, together with the consumption effects of gaseous hydrocarbon in the high-temperature stage in the calcium-hydrocarbon system, result in the crossed phenomenon of the gaseous hydrocarbon yields curves.

  4. 硫酸钙结垢与防治措施研究进展%Calcium Sulfate Fouling and its Advances in Research of Control Measures

    Institute of Scientific and Technical Information of China (English)

    杨亿; 胡宏; 李天祥

    2014-01-01

    在众多生产行业常常遇到硫酸钙结垢的问题,因此对于硫酸钙垢的防治技术的研究变得十分重要。针对密度大、硬度高的硫酸钙难溶垢,本文论述了硫酸钙结垢机理与特点的研究,探讨了硫酸钙工艺防垢、物理防垢、化学防垢、物理化学防垢的最新研究进展,介绍了新型高效的硫酸钙除垢措施。并对未来硫酸钙防垢方法及硫酸钙阻垢剂的发展进行了展望。%Many production industries often encountered some problems of calcium sulfate fouling.Therefore, to study some control techniques of the calcium sulfate fouling became extremely important.For the hard -soluble calcium sulfate scale of large density and high hardness , the research of calcium sulfate fouling mechanism , the latest research progress of calcium sulfate process scale , physical anti -scaling , chemical anti -scaling , physical and chemical anti -scaling , the newly and high efficiency removal measures of calcium sulfate are introduced , and the future development of the methods of preventing calcium sulfate scale and calcium sulfate scale inhibitor were discussed.

  5. Calcium Sulfate Vein Observations at Yellowknife Bay using ChemCam on the Curiosity Rover

    Science.gov (United States)

    Clegg, S. M.; Mangold, N.; Nachon, M.; Le Mouelic, S.; Ollila, A.; Vaniman, D. T.; Kah, L. C.; Dromart, G.; Bridges, J.; Rice, M. S.; Wellington, D. F.; Bell, J. F.; Anderson, R. B.; Clark, B. C.; Cousin, A.; Forni, O.; Lasue, J.; Schröder, S.; Meslin, P.; Dyar, M. D.; Blaney, D. L.; Maurice, S.; Wiens, R. C.; Team, M.

    2013-12-01

    The Mars Science Laboratory Curiosity rover completed its traverse from the Bradbury landing site into Yellowknife Bay (YKB) on sol 125, where it spent ~175 sols. The YKB region is characterized as a fluvio-lacustrine depositional environment. The entire Curiosity payload was used to thoroughly investigate parts of YKB from which significant geochemical observations were made, including the identification of anhydrite and hydrated calcium sulfate. The Curiosity ChemCam package consists of a remote Laser-Induced Breakdown Spectrometer (LIBS) and a Remote Micro-Imager (RMI). LIBS is essentially an elemental analysis micro-probe capable of 300 - 550 μm spatial resolution from 1.5 - 7.0 m standoff distance from the Curiosity mast. The RMI records context images that have a resolution of 40 μrad, which corresponds to 120 μm at 3 meters. The ChemCam instrument recorded many calcium rich geochemical features as it descended ~18 m into YKB. Many light-toned veins became apparent with the ChemCam RMI and Mastcam once Curiosity entered YKB. The ChemCam LIBS instrument is uniquely capable of distinctly probing the elemental composition of these vein structures separately from the host rock. LIBS demonstrated that the white vein material was dominated by CaSO4, while the host rock had relatively low SO3 compositions. The ChemCam instrument can also qualitatively detect H, presumably due to H2O, in many samples. While some of these veins contained no H signature beyond the ubiquitous small amount of H on rock surfaces and in soils, some of the veins contained various amounts of H as a function of depth indicating that some of the samples were either bassanite or gypsum. Mastcam spectral hydration surveys detect evidence of hydration that is consistent with (but not a unique indicator of) the presence of gypsum in some, but not all, of the veins. The CheMin X-ray diffraction instrument identified both anhydrite and bassanite in the matrix of a mudstone unit but did not detect

  6. Elution of platinum from carboplatin-impregnated calcium sulfate hemihydrate beads in vitro.

    Science.gov (United States)

    Tulipan, Rachel J; Phillips, Heidi; Garrett, Laura D; Dirikolu, Levent; Mitchell, Mark A

    2016-11-01

    OBJECTIVE To characterize the elution of platinum from carboplatin-impregnated calcium sulfate hemihydrate (CSH) beads in vitro. SAMPLE 60 carboplatin-impregnated CSH beads and 9 CSH beads without added carboplatin (controls). PROCEDURES Carboplatin-impregnated CSH beads (each containing 4.6 mg of carboplatin [2.4 mg of platinum]) were placed into separate 10-mL plastic tubes containing 5 mL of PBSS in groups of 1, 3, 6, or 10; 3 control beads were placed into a single tube of PBSS at the same volume. Experiments were conducted in triplicate at 37°C and a pH of 7.4 with constant agitation. Eluent samples were collected at 1, 2, 3, 6, 12, 24, and 72 hours. Samples were analyzed for platinum content by inductively coupled plasma-mass spectrometry. RESULTS The mean concentration of platinum released per carboplatin-impregnated bead over 72 hours was 445.3 mg/L. Cumulative concentrations of platinum eluted increased as the number of beads per tube increased. There was a significant difference in platinum concentrations over time, with values increasing over the first 12 hours and then declining for all tubes. There was also a significant difference in percentage of total incorporated platinum released into tubes with different numbers of beads: the percentage of eluted platinum was higher in tubes containing 1 or 3 beads than in those containing 6 or 10 beads. CONCLUSIONS AND CLINICAL RELEVANCE Carboplatin-impregnated CSH beads eluted platinum over 72 hours. Further studies are needed to determine whether implantation of carboplatin-impregnated CSH beads results in detectable levels of platinum systemically and whether the platinum concentrations eluted locally are toxic to tumor cells.

  7. Biocompatibility of artificial bone based on vancomycin loaded mesoporous silica nanoparticles and calcium sulfate composites.

    Science.gov (United States)

    Gu, Jisheng; Wang, Teng; Fan, Guoxin; Ma, Junhua; Hu, Wei; Cai, Xiaobing

    2016-04-01

    The aim of this study was to evaluate the in vitro and in vivo biocompatibility of artificial bone based on vancomycin loaded mesoporous silica nanoparticles and calcium sulfate composites. In vitro cytotoxicity tests by cholecystokinin octapeptide (CCK-8) assay showed that the 5%Van-MSN-CaSO4 and Van-CaSO4 bone cements were cytocompatible for mouse osteoblastic cell line MC3T3-E1. The microscopic observation confirmed that MC3T3-E1cells incubated with Van-CaSO4 group and 5%Van-MSN-CaSO4 group exhibited clear spindle-shaped changes, volume increase and maturation, showing that these cements supported adhesion of osteoblastic cells on their surfaces. In addition, the measurement of alkaline phosphatase activity revealed the osteoconductive property of these biomaterials. In order to assess in vivo biocompatibility, synthesized cements were implanted into the distal femur of twelve adult male and female New Zealand rabbits. After implantation in artificial defects of the distal femur, 5%Van-MSN-CaSO4 and Van-CaSO4 bone cements did not damage the function of main organs of rabbits. In addition, the Van-MSN-CaSO4 composite allowed complete repair of bone defects with new bone formation 3 months after implantation. These results show potential application of Van-MSN-CaSO4 composites as bone graft materials for the treatment of open fracture in human due to its mechanical, osteoconductive and potential sustained drug release characteristics and the absence of adverse effects on the body.

  8. BLENDED CALCIUM ALUMINATE-CALCIUM SULFATE CEMENT-BASED GROUT FOR P-REACTOR VESSEL IN-SITU DECOMMISSIONING

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C.; Stefanko, D.

    2011-03-10

    The objective of this report is to document laboratory testing of blended calcium aluminate - calcium hemihydrate grouts for P-Reactor vessel in-situ decommissioning. Blended calcium aluminate - calcium hemihydrate cement-based grout was identified as candidate material for filling (physically stabilizing) the 105-P Reactor vessel (RV) because it is less alkaline than portland cement-based grout which has a pH greater than 12.4. In addition, blended calcium aluminate - calcium hemihydrate cement compositions can be formulated such that the primary cementitious phase is a stable crystalline material. A less alkaline material (pH {<=} 10.5) was desired to address a potential materials compatibility issue caused by corrosion of aluminum metal in highly alkaline environments such as that encountered in portland cement grouts [Wiersma, 2009a and b, Wiersma, 2010, and Serrato and Langton, 2010]. Information concerning access points into the P-Reactor vessel and amount of aluminum metal in the vessel is provided elsewhere [Griffin, 2010, Stefanko, 2009 and Wiersma, 2009 and 2010, Bobbitt, 2010, respectively]. Radiolysis calculations are also provided in a separate document [Reyes-Jimenez, 2010].

  9. Effects of calcium sulfate and magnesium sulfate whiskers on Vickers Hardness of dental composite resin%硫酸钙和硫酸镁晶须对复合树脂维氏硬度的影响

    Institute of Scientific and Technical Information of China (English)

    何峰; 张莘; 王晓菲; 章非敏; 谢海峰

    2011-01-01

    Objects The aim of this study was to evalue the effects of calcium sulphate and magnesium sulfate whiskers on the Vickers Hardness of dental composite resin. Methods Calcium suffate and magnesium sulfate whiskers were prepared and were surface modified by sodium stearate. Eight groups of composite resin specimens were prepared: one control group, and seven groups using either surface modified calcium sulfate whiskers or magnesium sulfate whiskers comprising 1%, 10% , 20%, 30% of the material by weight. The standard resin samples were prepared, and their Vickers Hardness values were measured. Results With 20% and 30% calcium sulphate or magnesium sulfate whiskers, surface hardness improved. The more magnesium sulfate whiskers was added, the higher surface hardness values presented. Conclusons Appropriate proportions of calcium sulphate and magnesium sulfate whisker would increase the surface hardness of dental composite resin.%目的 探讨硫酸钙和硫酸镁晶须对复合树脂的维氏硬度的影响.方法 制备硫酸钙和硫酸镁晶须,以硬脂酸钠改性剂表面改性,随后分别按1%、10%、20%、30%的比例混合入复合树脂中,固化后测量各组试件表面维氏硬度.结果 两种晶须的添加比例为20%和30%时,树脂的表面维氏硬度均增加,硫酸镁晶须添加量多时树脂表面硬度相应增加.结论 添加适当比例的硫酸钙和硫酸镁镁晶须可以提高复合树脂的表面硬度.

  10. Novel bone substitute composed of chitosan and strontium-doped α-calcium sulfate hemihydrate: Fabrication, characterisation and evaluation of biocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yirong; Zhou, Yilin [Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Yang, Shenyu [Department of Materials Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Li, Jiao Jiao [Biomaterials and Tissue Engineering Research Unit, School of AMME, University of Sydney, Sydney, NSW 2006 (Australia); Li, Xue; Ma, Yunfei; Hou, Yilong; Jiang, Nan; Xu, Changpeng; Zhang, Sheng [Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Zeng, Rong [Department of Materials Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Tu, Mei, E-mail: tumei@jnu.edu.cn [Department of Materials Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Yu, Bin, E-mail: yubinol@163.com [Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China)

    2016-09-01

    Calcium sulfate is in routine clinical use as a bone substitute, offering the benefits of biodegradability, biocompatibility and a long history of use in bone repair. The osteoconductive properties of calcium sulfate may be further improved by doping with strontium ions. Nevertheless, the high degradation rate of calcium sulfate may impede bone healing as substantial material degradation may occur before the healing process is complete. The purpose of this study is to develop a novel composite bone substitute composed of chitosan and strontium-doped α-calcium sulfate hemihydrate in the form of microcapsules, which can promote osteogenesis while matching the natural rate of bone healing. The developed microcapsules exhibited controlled degradation that facilitated the sustained release of strontium ions. In vitro testing showed that the microcapsules had minimal cytotoxicity and ability to inhibit bacterial growth. In vivo testing in a mouse model showed the absence of genetic toxicity and low inflammatory potential of the microcapsules. The novel microcapsules developed in this study demonstrated suitable degradation characteristics for bone repair as well as favourable in vitro and in vivo behaviour, and hold promise for use as an alternative bone substitute in orthopaedic surgery. - Highlights: • Chitosan + Sr-doped α-calcium sulfate hemihydrate microcapsules were synthesised. • The novel composite microcapsules had potential application as a bone substitute. • The microcapsules showed controlled degradation and release of strontium ions. • The microcapsules showed in vitro biocompatibility by cytotoxicity test. • The microcapsules showed in vivo biocompatibility in a mouse model.

  11. Printability of calcium phosphate: calcium sulfate powders for the application of tissue engineered bone scaffolds using the 3D printing technique.

    Science.gov (United States)

    Zhou, Zuoxin; Buchanan, Fraser; Mitchell, Christina; Dunne, Nicholas

    2014-05-01

    In this study, calcium phosphate (CaP) powders were blended with a three-dimensional printing (3DP) calcium sulfate (CaSO4)-based powder and the resulting composite powders were printed with a water-based binder using the 3DP technology. Application of a water-based binder ensured the manufacture of CaP:CaSO4 constructs on a reliable and repeatable basis, without long term damage of the printhead. Printability of CaP:CaSO4 powders was quantitatively assessed by investigating the key 3DP process parameters, i.e. in-process powder bed packing, drop penetration behavior and the quality of printed solid constructs. Effects of particle size, CaP:CaSO4 ratio and CaP powder type on the 3DP process were considered. The drop penetration technique was used to reliably identify powder formulations that could be potentially used for the application of tissue engineered bone scaffolds using the 3DP technique. Significant improvements (pprinted constructs were manufactured, which exhibited appropriate green compressive strength and a high level of printing accuracy.

  12. Reinforcement of calcium sulfate and magnesium sulfate whiskers to dental composite resin%CaSO4和MgSO4晶须填料对牙科复合树脂抗弯强度的影响

    Institute of Scientific and Technical Information of China (English)

    何峰; 徐玲玲; 谢海峰; 朱烨; 章非敏

    2010-01-01

    目的 观察CaSO4晶须和MgSO4晶须对复合树脂的抗弯强度的影响.方法 制备CaSO4晶须和MgSO4晶须,以硬脂酸钠改性剂表面改性,随后分别按质量分数为1%、10%、20%、30%混合添加到复合树脂中,固化后评价其三点抗弯强度,扫描电镜观察断面形态.结果 添加2种晶须的质量分数在10%及以下时,复合树脂的三点抗弯强度均下降,质量分数为20%和30%时,MgsO4晶须组的三点抗弯强度增加.结论 添加适当比例的MgSO4晶须可以提高复合树脂的三点抗弯强度.%Objective The aim of this study was to evaluate the effect of calcium sulphate and magnesium sulfate whiskers on the flexture strengths of dental composite resin.Methods Calcium sulfate whiskers and magnesium sulfate whiskers were prepared.Seven groups of composite resin specimens were prepared including one control group and six groups using either calcium sulfate whiskers or magnesium sulfate whiskers comprising 1%,10%,20%,30% of the material by weight.Before mixing with resin,both whiskers were surface modified by Sodium stearate.The standard resin samples with dimensions of 25 mm×2 mm×2 mm were prepared according to the ISO-10477 criterion(eight for each group),and their flexure strengths were measured by a universal testing machine.The fracture surfaces of selected specimens were examined by a scan electron microscope.Results Neither mixture improved the flexure strength of composite resin when the adding proportions of calcium sulfate and whiskers magnesium sulfate whiskers were under 10%.However,when the adding proportions were 20 wt % and 30 wt%,magnesium sulfate whiskers excerted positive effects.Concluson Appropriate proportions of magnesium sulfate crystal whisker would increase the flexure strength of dental composite resin.

  13. Promotion of in vivo degradability, vascularization and osteogenesis of calcium sulfate-based bone cements containing nanoporous lithium doping magnesium silicate

    Science.gov (United States)

    Cao, Liehu; Weng, Weizong; Chen, Xiao; Zhang, Jun; Zhou, Qirong; Cui, Jin; Zhao, Yuechao; Shin, Jung-Woog; Su, Jiacan

    2017-01-01

    Nanoporous lithium doping magnesium silicate (nl-MS) was introduced into calcium sulfate hemihydrate to prepare calcium sulfate composite (nl-MSC) bone cements. The introduction of nl-MS improved the in vitro degradability of nl-MSC cements, which could neutralize acidic degradable products of calcium sulfate and prevented the pH from dropping. The cements were implanted into the bone defects of femur bone of rabbits, and the results of histological and immunohistochemical analysis revealed that massive new bone tissue formed in the defects while the cements were degradable, indicating that the osteogenesis and degradability of the nl-MSC cements were much better than the control calcium sulfate dihydrate (CSD) cements. Furthermore, the positive expression of vascular endothelial growth factor and collagen type I for nl-MSC cements was higher than CSD, indicating that addition of nl-MS into the cements enhanced vascularization and osteogenic differentiation. The results suggested that the nl-MSC cements with good biocompatibility and degradability could promote vascularization and osteogenesis, and had great potential to treat bone defects. PMID:28260883

  14. Degradability of injectable calcium sulfate/mineralized collagen-based bone repair material and its effect on bone tissue regeneration

    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); Kang, Lingzhi [National Glycoengineering Research Center, Shandong University, Jinan 250100 (China); Meng, Qing-Yuan [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Liu, Huanye [Department of Prosthodontics, School of Stomatology, China Medical University, Shenyang 110001 (China); Wang, Zhaoliang [Jinan Military General Hospital of PLA, Jinan 250031 (China); Guo, Zhongwu, E-mail: zwguo@sdu.edu.cn [National Glycoengineering Research Center, Shandong University, Jinan 250100 (China); Cui, Fu-Zhai, E-mail: cuifz@mail.tsinghua.edu.cn [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2014-12-01

    The nHAC/CSH composite is an injectable bone repair material with controllable injectability and self-setting properties prepared by introducing calcium sulfate hemihydrate (CSH) into mineralized collagen (nHAC). When mixed with water, the nHAC/CSH composites can be transformed into mineralized collagen/calcium sulfate dihydrate (nHAC/CSD) composites. The nHAC/CSD composites have good biocompatibility and osteogenic capability. Considering that the degradation behavior of bone repair material is another important factor for its clinical applications, the degradability of nHAC/CSD composites was studied. The results showed that the degradation ratio of the nHAC/CSD composites with lower nHAC content increased with the L/S ratio increase of injectable materials, but the variety of L/S ratio had no significant effect on the degradation ratio of the nHAC/CSD composites with higher nHAC content. Increasing nHAC content in the composites could slow down the degradation of nHAC/CSD composite. Setting accelerator had no significant effect on the degradability of nHAC/CSD composites. In vivo histological analysis suggests that the degradation rate of materials can match the growth rate of new mandibular bone tissues in the implanted site of rabbit. The regulable degradability of materials resulting from the special prescriptions of injectable nHAC/CSH composites will further improve the workability of nHAC/CSD composites. - Highlights: • The nHAC/CSH composite can be as an injectable bone repair material. • The L/S ratio and nHAC content have a significant effect on material degradability. • The degradability of bone materials can be regulated to match tissue repair. • The regulable degradability will further improve the workability of bone materials.

  15. Effects of neutral sulfate berberine on LPS-induced cardiomyocyte TNF-αsecretion, abnormal calcium cycling, and cardiac dysfunction in rats

    Institute of Scientific and Technical Information of China (English)

    Jing YANG; Hua-dong WANG; Da-xiang LU; Yan-ping WANG; Ren-bin QI; Jing LI; Fei LI; Chu-jie LI

    2006-01-01

    Aim: To evaluate the effect of neutral sulfate berberine on cardiac function, tumornecrosis factor α (TNF-α) release, and intracellular calcium concentration ([Ca2+]i)in cardiomyocytes exposed to lipopolysaccharide (LPS). Methods: Primary cultured rat cardiomyocytes were prepared from ventricles of 3-4-day old SpragueDawley rats. TNF-α concentrations in cell-conditioned media were measured by using a Quantikine enzyme-linked immunosorbent assay kit, and cardiomyocyte [Ca2+]i was measured by using Fura-2/AM. The isolated rat hearts were perfused in the Langendorff mode. Results: LPS at doses of 1, 5, 10, and 20 μg/mL markedly stimulated TNF-α secretion from cardiomyocytes, and neutral sulfate berberine inhibited LPS-induced TNF-α production. Intracellular calcium concentration was significantly decreased after LPS stimulation for 1 h, and increased 2 h after LPS treatment. Pretreatment with neutral sulfate berberine reversed the LPS-induced [Ca2+]i alterations, although neutral sulfate berberine did not inhibit a rapid increase in cardiomyocyte [Ca2+]i induced by LPS. Perfusion of isolated hearts with LPS (100 μg/mL) for 20 min resulted in significantly impaired cardiac performance at 120 min after LPS challenge: the maximal rate of left ventricular pressure rise and fall (±dp/dtmax) decreased compared with the control. In contrast, ±dp/dtmax at 120min in hearts perfused with neutral sulfate berberine (1 μmol/L) for 10 min followed by 20 min LPS (100 μg/mL) was greater than the corresponding value in the LPS group. Conclusion: Neutral sulfate berberine inhibits LPS-stimulated myocardial TNF-α production, impairs calcium cycling, and improves LPS-induced contractile dysfunction in intact heart.

  16. Effect of Compounding of Sodium Tripolyphosphate and Super Plasticizers on the Hydration of α-calcium Sulfate Hemihydrate

    Institute of Scientific and Technical Information of China (English)

    PAN Wei; WANG Peiming

    2011-01-01

    The inhibition and its mechanism of sodium tripolyphosphate(STP)composited with super plasticizers(SPs)on hydration of α-calcium sulfate hemihydrate were studied by setting time,strength,hydration heat,X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),electronic probe micro analysis (EPMA),scanning electron microscopy(SEM)and differential scanning calorimeter(DSC)measurements.The experimental results show that compared with STP addition,compositing STP with polycarboxylate(PC)plasticizer,the final setting time is prolonged from 0.5h to 2hs.While formulating STP with naphthalene-based plasticizer(NAP)or sulfonate melamine formaldehyde plasticizer(SMF),the final setting time is reduced to quarter of an hour Similar changes can also be found in the rate of exothermic hydration and hydration degree.Formulating STP with suitable addition of PC can enhance the strength,while compositing STP and NAP or SMF weakens the strength.Besides,adding STP or STP and SMF,obvious movement(more than lev)of binding energy of Ca2p1/2 and Ca2p3/2 is detected.Compared with STP addition,content of the characteristic element(P)of STP is cut down form 1.1% to 0.49% by compositing STP with SMF.Furthermore,as hydration age increases,hydration inhibition in the presence of admixtures weakens and even disappears within 56 h.

  17. Calcium Sulfate in Atacama Desert Basalt: A Possible Analog for Bright Material in Adirondack Basalt, Gusev Crater

    Science.gov (United States)

    Sutter, B.; Golden, D. C.; Amundson, R.; Chong-Diaz, G.; Ming, D. W.

    2007-01-01

    The Atacama Desert in northern Chile is one of the driest deserts on Earth (basalt parent material observed white material in the interior vesicles of surface basalt. This is strikingly similar to the bright-white material present in veins and vesicles of the Adirondack basalt rocks at Gusev Crater which are presumed to consist of S, Cl, and/or Br. The abundance of soil gypsum/anhydrite in the area of the Atacama basalt suggested that the white material consisted of calcium sulfate (Ca-SO4) which was later confirmed by SEM/EDS analysis. This work examines the Ca-SO4 of Atacama basalt in an effort to provide insight into the possible nature of the bright material in the Adirondack basalt of Gusev Crater. The objectives of this work are to (i) discuss variations in Ca-SO4 crystal morphology in the vesicles and (ii) examine the Ca-SO4 interaction(s) with the basalt interior.

  18. Characterization and precipitation mechanism of α-calcium sulfate hemihydrate growing out of FGD gypsum in salt solution

    Institute of Scientific and Technical Information of China (English)

    YANG LiuChun; GUAN BaoHong; WU ZhongBiao

    2009-01-01

    Alpha-calcium sulfate hemihydrate (α-HH) has been prepared from flue gas desulfurization (FGD)gypsum with salt solution method under atmospheric pressure. X-ray diffraction (XRD), thermogra-vimetry and differential scanning calorimetry (TG-DSC), optical micrograph, X-ray photoelectron spec-troscopy (XPS), energy dispersive spectrometry (EDS), and scanning electron microscopy (SEM) have been employed to characterize the α-HH crystals, based on which the formation and growth mecha-nisms of the a-HH crystals have been discussed. The results show that FGD gypsum can be success-fully transformed into high purity α-HH in salt solution under mild conditions, and that a dissolu-tion-recrystallization route is most probably adopted by this transition. The growth of a-HH crystals in salt solution demonstrates a preferred direction along [001] and results in a bundle-of-sheets or bun-dle-of-raphide texture. The characteristics revealed in this study can help to understand and control the growth of the α-HH crystal from solution.

  19. Characterization and precipitation mechanism of α-calcium sulfate hemihydrate growing out of FGD gypsum in salt solution

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Alpha-calcium sulfate hemihydrate (α-HH) has been prepared from flue gas desulfurization (FGD) gypsum with salt solution method under atmospheric pressure. X-ray diffraction (XRD),thermogra-vimetry and differential scanning calorimetry (TG-DSC),optical micrograph,X-ray photoelectron spec-troscopy (XPS),energy dispersive spectrometry (EDS),and scanning electron microscopy (SEM) have been employed to characterize the α-HH crystals,based on which the formation and growth mecha-nisms of the α-HH crystals have been discussed. The results show that FGD gypsum can be success-fully transformed into high purity α-HH in salt solution under mild conditions,and that a dissolu-tion-recrystallization route is most probably adopted by this transition. The growth of α-HH crystals in salt solution demonstrates a preferred direction along [001] and results in a bundle-of-sheets or bun-dle-of-raphide texture. The characteristics revealed in this study can help to understand and control the growth of the α-HH crystal from solution.

  20. Biphasic calcium sulfate dihydrate/iron-modified alpha-tricalcium phosphate bone cement for spinal applications: in vitro study

    Energy Technology Data Exchange (ETDEWEB)

    Vlad, M D; Lopez, J; Torres, R; Barraco, M; Fernandez, E [Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Division of Biomaterials and Bioengineering, Technical University of Catalonia (UPC), Avda Diagonal 647, E-08028-Barcelona (Spain); Valle, L J [Centre of Molecular Biotechnology (CEBIM), Department of Agri-Food Engineering and Biotechnology, ESAB, UPC, Avda Canal Olimpico 15, E-08860-Castelldefels (Spain); Poeata, I, E-mail: enrique.fernandez@upc.ed [Faculty of Medical Bioengineering, ' Gr T Popa' University of Medicine and Pharmacy, Str. Kogalniceanu 9-13, 700454 Iasi (Romania)

    2010-04-15

    In this study, the cytocompatibility of new 'iron-modified/alpha-tricalcium phosphate (IM/alpha-TCP) and calcium sulfate dihydrate (CSD)' bone cement (IM/alpha-TCP/CSD-BC) intended for spinal applications has been approached. The objective was to investigate by direct-contact osteoblast-like cell cultures (from 1 to 14 days) the in vitro cell adhesion, proliferation, morphology and cytoskeleton organization of MG-63 cells seeded onto the new cements. The results were as follows: (a) quantitative MTT-assay and scanning electron microscopy (SEM) showed that cell adhesion, proliferation and viability were not affected with time by the presence of iron in the cements; (b) double immunofluorescent labeling of F-actin and alpha-tubulin showed a dynamic interaction between the cell and its porous substrates sustaining the locomotion phenomenon on the cements' surface, which favored the colonization, and confirming the biocompatibility of the experimental cements; (c) SEM-cell morphology and cytoskeleton observations also evidenced that MG-63 cells were able to adhere, to spread and to attain normal morphology on the new IM/alpha-TCP/CSD-BC which offered favorable substratum properties for osteoblast-like cells proliferation and differentiation in vitro. The results showed that these new iron-modified cement-like biomaterials have cytocompatible features of interest not only as possible spinal cancellous bone replacement biomaterial but also as bone tissue engineering scaffolds.

  1. The influence of calcium, magnesium, phosphorus and silica on vanadium precipitation in acidic sulfate solutions

    Directory of Open Access Journals (Sweden)

    A. H. Martins

    2000-06-01

    Full Text Available The experimental research work was carried out in accordance with the Factorial Design Statistical Method to evaluate and analyze the influence of calcium, magnesium, silica and phosphorus on the precipitation of vanadates. Precipitation was performed by neutralization with H2SO4 of alkaline aqueous solutions containing vanadium pentoxide (V2O5 at 60± 2ºC. The experimental responses measured were percent of vanadium recovery and vanadium pentoxide content in the precipitate. These impurities are considered representative of those present in a leach liquor from the ore obtained at Campo Alegre de Lourdes (Brazil. The operational variables in this work were used under optimum conditions as determined by the statistical approach. Among the impurities under study, phosphorus exhibited the highest negative influence on the experimental responses. Phosphorus diminished the percent of vanadium recovered from 98.9 to 34.5 and the vanadium oxide content in the precipitate from 91.2 % to 39.3 %.

  2. The influence of calcium, magnesium, phosphorus and silica in vanadium precipitation in acidic sulfate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Martins, A.H. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Engenharia Metalurgica e de Materiais. E-mail: ahmartin@demet.ufmg.br

    2000-06-01

    The experimental research work was carried out in accordance with the Factorial Design Statistical Method to evaluate and analyze the influence of calcium, magnesium, silica and phosphorus on the precipitation of vanadates. precipitation was performed by neutralization with H{sub 2} SO{sub 4} of alkaline aqueous solutions containing vanadium pentoxide (V{sub 2} O{sub 5}) at 60 {+-} 2 deg C. The experimental responses measured were percent of vanadium recovery and vanadium pentoxide content in the precipitate. These impurities are considered representative of those present in a leach liquor from the ore obtained at Campo Alegre de Lourdes (Brazil). The operational variables in this work were used optimum conditions as determined by the statistical approach. Among the impurities under study, phosphorus exhibited the highest negative influence on the experimental responses. Phosphorus diminished the percent of vanadium recovered from 98.9 to 34.5 and the vanadium oxide content in the precipitate from 91.2% to 39.3%. (author)

  3. Thermal simulation experiments of saturated hydro-carbons with calcium sulfate and element sulfur: Implications on origin of H_2S

    Institute of Scientific and Technical Information of China (English)

    CHEN TengShui; HE Qin; LU Hong; PENG PingAn; LIU JinZhong

    2009-01-01

    Temperature-programmed simulation experiments of saturated hydrocarbons with calcium sulfate and element sulfur were compared in this study. Based on the variation analysis of the yields and evolve-ment features of gaseous hydrocarbon (C_1-C_5) and inorganic gaseous CO_2, H_2 and H_2S, the reaction mechanisms were analyzed and discussed. In the calcium sulfate-saturated hydrocarbon system, H2S was produced by a small quantity, which indicates this reaction belongs to the low-degreed thermal sulfate reduction (TSR) and is featured of self-pyrolysis. In the sulfur-saturated hydrocarbon system, the heated sulfur becomes sulfur radical, which has strong catalysis capability and can fasten the cracking of C-H bond in the alkyl group in the saturated hydrocarbons. As a result, the cracking of C-H bond leads to the yields enhancement of CO_2 and H_2, and at the same time, H2S was produced since the cracked hydrogen can be instantly combined with sulfur radical. Therefore, this reaction in the sulfur-hydrocarbon system belongs to the catalysis of sulfur radical. Furthermore, the promoted pyro-lysis effects of C_(6+). hydrocarbons by sulfur radical in the low-temperature stage in the sul-fur-hydrocarbon system, together with the consumption effects of gaseous hydrocarbon in the high-temperature stage in the calcium-hydrocarbon system, result in the crossed phenomenon of the gaseous hydrocarbon yields curves.

  4. Evaluation of sulfated polysaccharides from the brown seaweed Dictyopteris justii as antioxidant agents and as inhibitors of the formation of calcium oxalate crystals.

    Science.gov (United States)

    Melo, Karoline Rachel Teodosio; Camara, Rafael Barros Gomes; Queiroz, Moacir Fernandes; Vidal, Arthur Anthunes Jacome; Lima, Camila Renata Machado; Melo-Silveira, Raniere Fagundes; Almeida-Lima, Jailma; Rocha, Hugo Alexandre Oliveira

    2013-11-25

    Oxalate crystals and other types of crystals are the cause of urolithiasis, and these are related to oxidative stress. The search for new compounds with antioxidant qualities and inhibitors of these crystal formations is therefore necessary. In this study, we extracted four sulfated polysaccharides, a fucoglucoxyloglucuronan (DJ-0.3v), a heterofucan (DJ-0.4v), and two glucans (DJ-0.5v and DJ-1.2v), from the marine alga Dictyopteris justii. The presence of sulfated polysaccharides was confirmed by chemical analysis and FT-IR. All the sulfated polysaccharides presented antioxidant activity under different conditions in some of the in vitro tests and inhibited the formation of calcium oxalate crystals. Fucan DJ-0.4v was the polysaccharide that showed the best antioxidant activity and was one of the best inhibitors of the crystallization of calcium oxalate. Glucan DJ-0.5v was the second most potent inhibitor of the formation of oxalate crystals, as it stabilized dehydrated oxalate crystals (less aggressive form), preventing them from transforming into monohydrate crystals (more aggressive form). The obtained data lead us to propose that these sulfated polysaccharides are promising agents for use in the treatment of urolithiasis.

  5. Evaluation of Sulfated Polysaccharides from the Brown Seaweed Dictyopteris Justii as Antioxidant Agents and as Inhibitors of the Formation of Calcium Oxalate Crystals

    Directory of Open Access Journals (Sweden)

    Karoline Rachel Teodosio Melo

    2013-11-01

    Full Text Available Oxalate crystals and other types of crystals are the cause of urolithiasis, and these are related to oxidative stress. The search for new compounds with antioxidant qualities and inhibitors of these crystal formations is therefore necessary. In this study, we extracted four sulfated polysaccharides, a fucoglucoxyloglucuronan (DJ-0.3v, a heterofucan (DJ-0.4v, and two glucans (DJ-0.5v and DJ-1.2v, from the marine alga Dictyopteris justii. The presence of sulfated polysaccharides was confirmed by chemical analysis and FT-IR. All the sulfated polysaccharides presented antioxidant activity under different conditions in some of the in vitro tests and inhibited the formation of calcium oxalate crystals. Fucan DJ-0.4v was the polysaccharide that showed the best antioxidant activity and was one of the best inhibitors of the crystallization of calcium oxalate. Glucan DJ-0.5v was the second most potent inhibitor of the formation of oxalate crystals, as it stabilized dehydrated oxalate crystals (less aggressive form, preventing them from transforming into monohydrate crystals (more aggressive form. The obtained data lead us to propose that these sulfated polysaccharides are promising agents for use in the treatment of urolithiasis.

  6. The effect of intraosseous injection of calcium sulfate on microstructure and biomechanics of osteoporotic lumbar vertebrae in sheep

    Directory of Open Access Journals (Sweden)

    Da LIU

    2014-10-01

    Full Text Available Objective To investigate the effect of calcium sulfate (CS on improvement of microstructure and biomechanical performance of osteoporotic lumbar vertebrae in sheep. Methods Osteoporosis model was reproduced in 8 female sheep by bilateral ovariectomy and methylprednisolone administration. Then the lumbar vertebrae (L1-L4 in each sheep were randomly divided into CS group and blank group (2 vertebrae in each sheep. CS was injected into the vertebral bodies through the pedicle in CS group, and no treatment was given in blank group. All of the animals were sacrificed 3 months later, and vertebrae L1-L4 were harvested. The microstructure and biomechanical performance of vertebral bodies were assessed by micro-CT scanning, histological observation and biomechanical test. Results After ovariectomy and methylprednisolone administration, the mean bone mineral density of the lumbar vertebrae in the sheep was significantly decreased (>25% compared with that before induction (P<0.05, demonstrating a successful reproduction of osteoporosis model. Three months after injection, it was shown that CS was completely degraded without any remnant in the bone tissue. The quality of the bone tissue (trabecular number and tissue mineral density in CS group was significantly better than that in blank group (P<0.05, and the biomechanical performance in CS group was significantly superior to that in blank group (P<0.05. Conclusions  Local injection of CS could significantly improve the microstructure and biomechanical performance of osteoporotic vertebrae, and it may decrease the risk of fracture of patients with osteoporosis. DOI: 10.11855/j.issn.0577-7402.2014.09.02

  7. Effects of Calcium Sulfate Combined with Platelet-rich Plasma on Restoration of Long Bone Defect in Rabbits

    Institute of Scientific and Technical Information of China (English)

    Hua Chen; Xin-Ran Ji; Qun Zhang; Xue-Zhong Tian; Bo-Xun Zhang; Pei-Fu Tang

    2016-01-01

    Background:The treatment for long bone defects has been a hot topic in the field of regenerative medicine.This study aimed to evaluate the therapeutic effects of calcium sulfate (CS) combined with platelet-rich plasma (PRP) on long bone defect restoration.Methods:A radial bone defect model was constructed through an osteotomy using New Zealand rabbits.The rabbits were randomly divided into four groups (n =10 in each group):a CS combined with PRP (CS-PRP) group,a CS group,a PRP group,and a positive (recombinant human bone morphogenetic protein-2) control group.PRP was prepared from autologous blood using a two-step centrifugation process.CS-PRP was obtained by mixing hemihydrate CS with PRP.Radiographs and histologic micrographs were generated.The percentage of bone regenerated bone area in each rabbit was calculated at 10 weeks.One-way analysis of variance was performed in this study.Results:The radiographs and histologic micrographs showed bone restoration in the CS-PRP and positive control groups,while nonunion was observed in the CS and PRP groups.The percentages of bone regenerated bone area in the CS-PRP (84.60 ± 2.87%) and positive control (52.21 ± 4.53%) groups were significantly greater than those in the CS group (12.34 ± 2.17%) and PRP group (16.52 ± 4.22%) (P < 0.001).In addition,the bone strength of CS-PRP group (43.l 0 ± 4.10%) was significantly greater than that of the CS group (20.10 ± 3.70%) or PRP group (25.10 ± 2.10%) (P < 0.001).Conclusion:CS-PRP functions as an effective treatment for long bone defects through stimulating bone regeneration and enhancing new bone strength.

  8. Reinforcing effect of calcium sulfate cement bovine bone morphogenetic protein on vertebral in the rabbit model of osteoporosis

    Institute of Scientific and Technical Information of China (English)

    Jie Zhang; Yu-Ming Chen; Chen Sheng-Guo; Kaken Habaerxi; Shawuti Alimujiang; Yu Chen; Ming-Zhen Peng; Rong Yue; Yu-Lian Wu; De-Quan Wang

    2014-01-01

    Objective:To observe reinforcing effect of calcium sulfate cement(CSC) bovine bone morphogenetic protein(bBMP) on vertebral in the rabbit model of osteoporosis.Methods:A total of48NewZealand white rabbits were randomly divided into groupⅠ(blank control group), group Ⅱ(CSC injection group), group Ⅲ(CSC/bBMP injection group) and control group.White rabbit osteoporosis model was established rapidly by using castration method+methylprednisolone candidate.After modeling, groups Ⅱ, Ⅲ were given corresponding vertebral body injection material, and4 animals were sacrificed respectively at24 h,6 weeks,12 weeks after vertebral plasty.Tissue pathological status, vertebral mineral density and vertebral body bone mechanical strength were observed.Results:Vertebral body structure form was normal in the groups Ⅱand Ⅲ.Trabecular bone coarsens, connection and repair were observed in micro fracture and bone defects, bone trabecular connectivity was superior to group Ⅰ significantly; vertebral body compression strength in the groupⅠ was on the decline, vertebral compression strength in the groups Ⅱand Ⅲ was on the rise, the largest vertebra.PostoperativeBMC andBMD in groups Ⅱand Ⅲ were incresed, andsignificantly higher than group Ⅰ after6 weeks(P<0.05),BMC and BMD in group Ⅲ after12 weeks were higher than the other three groups.Conclusion:Compound bBMPCSC has good bone induction.It can improve the three-dimensional construction effect for osteoporosis vertebral trabecula, and can significantly improve the vertebral strength, as a vertebral packing material with good application prospect.

  9. Hydroxyapatite-calcium sulfate-hyaluronic acid composite encapsulated with collagenase as bone substitute for alveolar bone regeneration.

    Science.gov (United States)

    Subramaniam, Sadhasivam; Fang, Yen-Hsin; Sivasubramanian, Savitha; Lin, Feng-Huei; Lin, Chun-pin

    2016-01-01

    Periodontitis is a very severe inflammatory condition of the periodontium that progressively damages the soft tissue and destroys the alveolar bone that supports the teeth. The bone loss is naturally irreversible because of limited reparability of the teeth. Advancement in tissue engineering provides an effective regeneration of osseous defects with suitable dental implants or tissue-engineered constructs. This study reports a hydroxyapatite, calcium sulfate hemihydrate and hyaluronic acid laden collagenase (HAP/CS/HA-Col) as a bone substitute for the alveolar bone regeneration. The composite material was mechanically tested and the biocompatibility was evaluated by WST-1 assay. The in vivo bone formation was assessed in rat with alveolar bone defects and the bone augmentation by the HAP/CS/HA-Col composite was confirmed by micro-CT images and histological examination. The mechanical strength of 6.69 MPa with excellent biocompatibility was obtained for the HAP/CS/HA-Col composite. The collagenase release profile had facilitated the acceleration of bone remodeling process and it was confirmed by the findings of micro-CT and H&E staining. The bone defects implanted with HAP/CS/HA composite containing 2 mg/mL type I collagenase have shown improved new bone formation with matured bone morphology in comparison with the HAP/CS/HA composite that lacks the collagenase and the porous hydroxyapatite (p-HAP) granules. The said findings demonstrated that the collagenase inclusion in HAP/CS/HA composite is a feasible approach for the alveolar bone regeneration and the same design can also be applied to other defective tissues.

  10. The crystal growth kinetics of alpha calcium sulfate hemihydrate in concentrated CaCl2-HCl solutions

    Science.gov (United States)

    Feldmann, Thomas; Demopoulos, George P.

    2012-07-01

    The crystal growth kinetics of calcium sulfate α-hemihydrate (α-HH) in nearly constant supersaturated HCl-CaCl2 solutions were investigated. Two types of solutions were used, the first had a low HCl (1.4 mol/L) and high CaCl2 (2.8 mol/L) concentration and the second had a high HCl (5.6 mol/L) and low CaCl2 (0.7 mol/L) concentration. These conditions were chosen to represent the first and last stage of a newly developed stage-wise HCl regeneration process. The seeded growth experiments were carried out in a stirred, temperature controlled semi-batch reactor in which supersaturation was kept constant by simultaneous addition of CaCl2 and Na2SO4 solutions. The influence of the following parameters on α-HH crystal growth was studied: temperature (70-95 °C), specific power input of stirring (0.02-1.29 W/kg) and equimolar inflow rate of CaCl2 and Na2SO4 (0-0.6 mol/h). The crystal growth rate was derived from particle size distribution measurements made with the laser light diffraction technique. It was found that the surface area normalized crystal growth rate increased linearly with the molar inflow rate up to 0.3 mol/h, at higher inflow rates no further increase of the growth rate was observed. Temperature and specific power input, within the investigated ranges, did not show a marked effect on the growth rate, attributable to a diffusion/adsorption controlled growth process. An interesting finding of the present research is the establishment of a positive relationship between the narrowing of the width of the particle size distribution with increasing crystal growth rate. The results show that the resulting particle size distribution is positively related to the reagent inflow rate, a finding that can be applied to the industrial design and scale-up of the α-HH crystallization/HCl regeneration process.

  11. 硫酸钙晶须的制备及其在塑料中的应用%Preparation of Calcium Sulfate Whisker and It's Application in Plastics

    Institute of Scientific and Technical Information of China (English)

    田浩; 薛涛; 聂登攀; 王振杰

    2012-01-01

    评述硫酸钙晶须的基本性能、制备及其在塑料中应用.提出利用磷石膏制备硫酸钙晶须有望成为解决磷石膏污染的新途径,同时可对天然石膏资源的滥采现象起到防治作用.%The basic properties, preparation and application in plastics of calcium sulfate whiskers are reviewed. Preparation of calcium phosphate whisker using Phosphogypsum is expected to become a new way to solve Phosphogypsum pollution , and prevent and cure an abuse phenomenon of the natural gypsum resources.

  12. The Effect of Ethyl Acetate on Crystallization of Calcium Sulfate Whisker%乙酸乙酯对硫酸钙晶须结晶的影响

    Institute of Scientific and Technical Information of China (English)

    李胜利

    2012-01-01

    The half water calcium sulphate whisker was prepared by hydrothermal synthesis process with calcium sulfate as raw material. When ethyl acetate was used as addition agent, the effects of the temperature, the reaction time, ethyl acetate and the mass ratio of dihydrate calcium sulphate to water on crystallization of half calcium sulfate whisker were studied by using the method of orthogonal design. The results sho.red that the increase of the reaction temperature induced the decrease of the ratio of length to width of whisker, the ratio of length to width of whisker increased at first and then decreased with the reaction time, the ratio of length to width of whisker increased with increasing the mass ratio of dihydrate calcium sulphate to water, namely the decrease of concentration of solution, ethyl acetate led to crystal form of half water calcium sulphate whisker from slender corrugated to massive prismatic%以硫酸钙为原料,采用水热法合成了半水硫酸钙晶须;并采用正交设计的方法来分析乙酸乙酯作为添加剂时,各因素对半水硫酸钙晶须结晶的影响:温度、时间、乙酸乙酯及二水硫酸钙与水的质量比。结果表明:反应温度的升高使得晶须的长宽比降低,反应时间的延长使得晶须的长宽比先升高后降低,二水硫酸钙与水的质量比增大即料浆浓度的降低使得晶须的长宽比增大,乙酸乙酯使半水硫酸钙晶须的的晶形由细长的瓦楞状变为粗大的棱柱状。

  13. Inhibition of tumor invasion and metastasis by calcium spirulan (Ca-SP), a novel sulfated polysaccharide derived from a blue-green alga, Spirulina platensis.

    Science.gov (United States)

    Mishima, T; Murata, J; Toyoshima, M; Fujii, H; Nakajima, M; Hayashi, T; Kato, T; Saiki, I

    1998-08-01

    We have investigated the effect of calcium spirulan (Ca-SP) isolated from a blue-green alga, Spirulina platensis, which is a sulfated polysaccharide chelating calcium and mainly composed of rhamnose, on invasion of B16-BL6 melanoma, Colon 26 M3.1 carcinoma and HT-1080 fibrosarcoma cells through reconstituted basement membrane (Matrigel). Ca-SP significantly inhibited the invasion of these tumor cells through Matrigel/fibronectin-coated filters. Ca-SP also inhibited the haptotactic migration of tumor cells to laminin, but it had no effect on that to fibronectin. Ca-SP prevented the adhesion of B16-BL6 cells to Matrigel and laminin substrates but did not affect the adhesion to fibronectin. The pretreatment of tumor cells with Ca-SP inhibited the adhesion to laminin, while the pretreatment of laminin substrates did not. Ca-SP had no effect on the production and activation of type IV collagenase in gelatin zymography. In contrast, Ca-SP significantly inhibited degradation of heparan sulfate by purified heparanase. The experimental lung metastasis was significantly reduced by co-injection of B16-BL6 cells with Ca-SP. Seven intermittent i.v. injections of 100 microg of Ca-SP caused a marked decrease of lung tumor colonization of B16-BL6 cells in a spontaneous lung metastasis model. These results suggest that Ca-SP, a novel sulfated polysaccharide, could reduce the lung metastasis of B16-BL6 melanoma cells, by inhibiting the tumor invasion of basement membrane probably through the prevention of the adhesion and migration of tumor cells to laminin substrate and of the heparanase activity.

  14. Hydrothermal Synthesis of a-calcium Sulfate Hemihydrate Particles Modified with Hydroxyapatite%水热合成羟基磷灰石表面修饰α-半水石膏复合颗粒

    Institute of Scientific and Technical Information of China (English)

    程逵; 章华勇; 翁文剑; 李坚; 黄海生

    2013-01-01

    The a-calcium sulfate hemihydrate particles modified with hydroxyapatite (HA) were prepared with calcium sulfate di-hydrate and HA in a mixed electrolyte solution of citric acid and magnesium sulfate by a co-hydrothermal method. The crystalline phase, morphology and microstructure of the HA modified a-calcium sulfate hemihydrate particles were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, differential scanning calorimetry and thermogravimetry, respectively. The results indicate that the composite particles after surface modification can be prepared by the co-hydrothermal synthesis method. The more HA could be deposited on the surface of a-calcium sulfate hemihydrate particles when the content of HA in the electrolyte was increased.%在柠檬酸和硫酸镁溶液中同时直接引入二水石膏与羟基磷灰石(hydroxyapatite,HA)共水热合成,获得了一种具有HA表面修饰的α-半水石膏的复合颗粒,并分析了该复合颗粒的成分、形貌、微观结构.结果表明:水热合成的颗粒是以α-半水石膏为主体,有HA在其表面修饰;随着HA的添加量的增加,HA表面修饰层的覆盖范围明显增加.

  15. Reactions Involving Calcium and Magnesium Sulfates as Potential Sources of Sulfur Dioxide During MSL SAM Evolved Gas Analyses

    Science.gov (United States)

    McAdam, A. C.; Knudson, C. A.; Sutter, B.; Franz, H. B.; Archer, P. D., Jr.; Eigenbrode, J. L.; Ming, D. W.; Morris, R. V.; Hurowitz, J. A.; Mahaffy, P. R.; Navarro-Gonzalez, R.

    2016-01-01

    The Sample Analysis at Mars (SAM) and Chemistry and Mineralogy (CheMin) instruments on the Mars Science Laboratory (MSL) have analyzed several subsamples of 860 C). Sulfides or Fe sulfates were detected by CheMin (e.g., CB, MJ, BK) and could contribute to the high temperature SO2 evolution, but in most cases they are not present in enough abundance to account for all of the SO2. This additional SO2 could be largely associated with x-ray amorphous material, which comprises a significant portion of all samples. It can also be attributed to trace S phases present below the CheMin detection limit, or to reactions which lower the temperatures of SO2 evolution from sulfates that are typically expected to thermally decompose at temperatures outside the SAM temperature range (e.g., Ca and Mg sulfates). Here we discuss the results of SAM-like laboratory analyses targeted at understanding this last possibility, focused on understanding if reactions of HCl or an HCl evolving phase (oxychlorine phases, chlorides, etc.) and Ca and Mg sulfates can result in SO2 evolution in the SAM temperature range.

  16. 硫酸钙在高分子材料中的应用综述%Application of Calcium Sulfate in Polymer Materials

    Institute of Scientific and Technical Information of China (English)

    黄明杰; 张晓莹

    2014-01-01

    塑料、合成纤维和合成橡胶被称为现代高分子三大合成材料,已经成为国民经济建设与人民日常生活所必不可少的重要材料。硫酸钙有着安全无毒、价廉易得、白度好、耐热性、介电特性、分散性和流动性均优异等诸多优势,在高分子材料中添加不仅可以补强、降低成本,并且还能赋予高分子材料各种新的功能,本文主要介绍了硫酸钙(石膏)在橡胶、塑料和涂料中的应用。%Plastics, synthetic fibers and synthetic rubber known as modern polymer three synthetic materials, have become important materials necessary for national economy construction and people’s daily life. Calcium sul-fate is safe and non-toxic,cheap,good whiteness,heat resistance,dielectric properties,excellent dispersion and mob-ility and many other advantages,it can reduce the cost of reinforcement by adding to polymer materials,and can give polymer materials all kinds of new functions. The author mainly introduced the applications of calcium sulfate ( gyp-sum) in rubber,plastic and paint.

  17. Preparation of α-calcium sulfate hemihydrate from phosphogypsum in Ca-Na-Cl solutions under atmospheric pressure%常压水热Ca-Na-Cl溶液中用磷石膏制备α-半水石膏

    Institute of Scientific and Technical Information of China (English)

    马保国; 茹晓红; 邹开波; 卢斯文; 付浩兵

    2013-01-01

    Preparation of a-calcium sulfate hemihydrate from phosphogypsum in hydrothermal electrolyte solutions under atmospheric pressure has been a promising way of effective utilization of phosphogypsum.In this paper preparation of α-calcium sulfate hemihydrate from phosphogypsum in Ca-Na-Cl solutions at 95℃was studied.Reaction time and solid products identification in 18.8% NaCl solution,24% CaCl2 and CaCl2 +NaCl solutions were investigated through morphologic observation,water of crystalization determination and phase analysis methods.The results showed that NaCl solution was not favorable as the dehydration reaction medium of phosphogypsum though reaction time was only 20 min,because the dehydration product was α-calcium sulfate hemihydrate containing omangwaite (Na2Ca5 (SO4)6 · 3H2O) which had no hydration property of gypsum.In 24% CaCl2 solution α-calcium sulfate hemihydrate phase could be obtained at reaction time of 240 min,reaction time was reduced obviously with increasing NaCl content in Ca-Na-Cl solution,but it was accompanied by increase of Na2O content and irregular uncompleted crystal shapes in the reaction product.Therefore,Ca-Na-Cl solution could be a suitable medium for dehydration reaction of phosphogypsum to form α-calcium sulfate hemihydrate in hydrothermal electrolyte solution under atmospheric pressure.Meanwhile NaCl content should be limited to 2%.

  18. 离子色谱法测定硫酸钙样品中的硫酸根%Determination of Sulfate Ion of Calcium Sulphate by Ion Chromatography

    Institute of Scientific and Technical Information of China (English)

    周巧丽; 卢丽君; 王国华; 廖海星; 薛改凤; 朱丽华

    2014-01-01

    用碳酸钠将硫酸钙样品中的钙沉淀为碳酸钙,释放出硫酸根,用阴离子型离子色谱仪,在40℃柱温下,以6.3 mmol/L NaHCO3–1.7 mmol/L Na2CO3缓冲盐为淋洗液,采用电导检测器测定其中硫酸根的浓度,以间接得到硫酸钙含量。实验结果表明,该法与经典的沉淀重量法测定结果相吻合,两者之间的相对误差为0.29%。样品加标回收率在96.0%~105.3%之间,测定结果的相对标准偏差为0.26%(n=6)。该方法精密度与准确度高,可快速、稳定、可靠地分析脱硫灰渣及石膏样品中的硫酸根含量。%Calcium sulphate in the sample was converted into calcium carbonate by using sodium carbonate,which released sulfate ions into solutions. The released sulfate ions were determined by an conductivity detector with anionic ion chromatography at 40℃,with the buffer of 6.3 mmol/L NaHCO3–1.7 mmol/L Na2CO3 solution. It was found that the result obtained by the anionic ion chromatography was very close to that obtained with the classic precipitation method, and the relative error between the two methods was only 0.29%. The new method yielded recoveries between 96.0% and 105.3% with RSD of 0.26% (n=6). The method can determine thecontent of sulfate in the sample of the desulfurization ash and gypsum,with high precision and accuracy,as well as being fast,stable and reliable.

  19. Chloride, gluconate, sulfate, and short-chain fatty acids affect calcium flux rates across the sheep forestomach epithelium.

    Science.gov (United States)

    Leonhard-Marek, S; Becker, G; Breves, G; Schröder, B

    2007-03-01

    In ruminants, more than 50% of overall gastrointestinal Ca absorption can occur preintestinally, and the anions of orally applied Ca salts are thought to play an important role in stimulating ruminal Ca absorption. This assumption is based mainly on ion-exchange studies that have used gluconate as the control anion, which may bind Ca2+ ions and interfere with treatment effects. In the present study, we investigated the distinct effects of different anions on Ca absorption across the sheep rumen and on the concentration of free Ca2+ ions ([Ca2+]ion). We showed that gluconate, sulfate, and short-chain fatty acids (SCFA) remarkably reduced [Ca2+]ion in buffer solutions. Nevertheless, increasing the Cl or SCFA concentration by 60 mM stimulated net ruminal Ca absorption 5- to 7-fold, but these effects could be antagonized by gluconate. Therefore, ion-exchange experiments must be (re)evaluated very carefully, because changes in [Ca2+]ion in the presence of gluconate, sulfate, or SCFA not only might entail an underestimation of Ca flux rates, but also might have effects on other cellular pathways that are Ca2+ dependent. Concerning the optimal Ca supply for dairy cows, the present study suggests that CaCl2 formulations and Ca salts of the SCFA stimulate Ca absorption across the rumen wall and are beneficial in preventing or correcting a Ca deficiency.

  20. Combination of calcium sulfate and simvastatin-controlled release microspheres enhances bone repair in critical-sized rat calvarial bone defects

    Directory of Open Access Journals (Sweden)

    Fu YC

    2015-12-01

    Full Text Available Yin-Chih Fu,1–4 Yan-Hsiung Wang,1,5 Chung-Hwan Chen,1,3,4 Chih-Kuang Wang,1,6 Gwo-Jaw Wang,1,3,4 Mei-Ling Ho1,3,7,8 1Orthopaedic Research Center, 2Graduate Institute of Medicine, 3Department of Orthopaedics, 4Department of Orthopaedics, College of Medicine, 5School of Dentistry, College of Dental Medicine, 6Department of Medicinal and Applied Chemistry, 7Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; 8Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, TaiwanAbstract: Most allogenic bone graft substitutes have only osteoconductive properties. Developing new strategies to improve the osteoinductive activity of bone graft substitutes is both critical and practical for clinical application. Previously, we developed novel simvastatin-encapsulating poly(lactic-co-glycolic acid microspheres (SIM/PLGA that slowly release simvastatin and enhance fracture healing. In this study, we combined SIM/PLGA with a rapidly absorbable calcium sulfate (CS bone substitute and studied the effect on bone healing in critical-sized calvarial bone defects in a rat model. The cytotoxicity and cytocompatibility of this combination was tested in vitro using lactate dehydrogenase leakage and a cell attachment assay, respectively. Combination treatment with SIM/PLGA and the CS bone substitute had no cytotoxic effect on bone marrow stem cells. Compared with the control, cell adhesion was substantially enhanced following combination treatment with SIM/PLGA and the CS bone substitute. In vivo, implantation of the combination bone substitute promoted healing of critical-sized calvarial bone defects in rats; furthermore, production of bone morphogenetic protein-2 and neovascularization were enhanced in the area of the defect. In summary, the combination of SIM/PLGA and a CS bone substitute has osteoconductive and osteoinductive properties, indicating that it could be used for regeneration

  1. Synthesis and evaluation of calcium sulfate scale inhibitor%硫酸钙阻垢剂(MAM)的合成与评价

    Institute of Scientific and Technical Information of China (English)

    李建波; 李永会; 钟小芳

    2013-01-01

    以马来酸为主要单体合成了一种四元共聚物阻垢剂(MAM),用正交实验进行了合成条件的优化研究,确定了最优的合成条件:m(马来酸):m (AA):m (AMPS):m(AM)=5∶5∶4∶0.5,引发剂与单体的质量比为8%,4种单体的总质量分数为15%,反应温度为90℃,反应时间为4h.研究了阻垢剂用量、溶液pH、钙离子浓度、硫酸根离子浓度、温度、恒温时间对该共聚物阻垢剂阻硫酸钙垢性能的影响,结果表明,在温度为70℃、溶液pH=7、ρ (Ca2+)=4 000 mg/L、ρ(SO42-)=7 000 mg/L、ρ(NaCl)=7.5 g/L的条件下,当MAM投加量为3 mg/L、恒温时间为25 h时,阻垢率为98.58%.%The quadripolymer scale inhibitor (MAM) has been synthesized with maleic acid as main monomer. The synthetic conditions are optimized by orthogonal tests. The result proves that the optimum synthetic conditions of the quadripolymer are as follows:m(MA):m(AA):m(AMPS):m(AM)=5:5:4:0.5,m[(NH4)2S2O8]:m(MA+AA+AMPS+ AM)=8%,m(MA+AA+AMPS+AM):m(MA+AA+AMPS+AM+H2O)=15%,reaction temperature at 90 ℃,and reaction time 4 h. The effects of scale inhibitor dosage, Ph of the solution, calcium ion concentration, sulfate ion concentration , solution temperature and constant temperature time on the inhibition efficiency of calcium sulfate scale are evaluated. The result proves that the scale-inhibiting rate will be 98.58%,when the temperature is 70 ℃ ,ρ(Ca2+) = 4 000 mg/L,ρ(SO42-) = 7 000 mg/L,ρ(NaCl)=7.5 g/L,and solution Ph=7 ,and when the dosage of MAM is 3 mg/L, and constant temperature time is 25 h.

  2. The kinetics of sulfation of calcium oxide. [Quarterly] project status report, March 1, 1990--May 31, 1990

    Energy Technology Data Exchange (ETDEWEB)

    Sarofim, A.F.; Longwell, J.P.

    1990-12-31

    The rate of sulfation of a CaO surface is rapid at first, limited by the intrinsic kinetics, but slows down with increasing conversion as a consequence of the increased resistance to diffusion through the product layer. The objectives of this study are to determine the intrinsic kinetics and the product layer diffusion pate by minimizing the resistances to gas-phase pore diffusion, and eliminating complications due to pore filling. This is achieved by the use of nonporous CaO. A wide range of particle sizes are used to change the relative importance of the regimes in which the intrinsic kinetics and product layer diffusion control. The assumption of constant product layer diffusivity can then be tested and the variables that determine this diffusivity independently studied. Information on product layer diffusion can also be obtained from studies of porous particles after the pore mouths are all plugged and a uniform surface coating is obtained. This information on diffusion rate and intrinsic reactivity can then be combined with a geometrical model to describe the rate of reaction over the entire range of conversions and is particularly useful in treating the effect of particle size on conversion history.

  3. Effectof Material Ratio on Phase Transfer Rate of Calcium Ions During Reaction between Calcium Sulfate Dihydrate and Ammonium Carbonate%二水硫酸钙与碳酸铵反应过程中物料比对钙离子相转移速率的影响

    Institute of Scientific and Technical Information of China (English)

    陈昌国; 周加贝; 夏素兰; 王子宁; 宫源; 刘仕忠

    2015-01-01

    选择二水硫酸钙晶须为研究对象,在温度、搅拌速度、料浆浓度不变的条件下,探究了二水硫酸钙与碳酸铵反应过程中物料比 n(NH 4)2 CO 3:nCaSO 4∙2 H 2 O 对钙离子相转移速率的影响。结果表明,物料比在1.05∶1~1.4∶1之间时,生成的碳酸钙沉淀于溶液中,钙离子相转移是溶解-结晶过程,二水硫酸钙转化率和碳酸钙颗粒粒径均随物料比增大而增大,即相转移速率与物料比成正比。%Calcium sulfate dihydrate whiskers were applied under constant temperature,stirring speed and slurry concentration.The material ratio of n(NH 4 )2 CO 3 ∶nCaSO 4 ∙2 H 2 O was changed to study its effect on phase transfer of calcium ions during the reaction between calcium sulfate dihydrate and ammonium car-bonate.The result showed that calcium carbonate crystals were precipitate in solution as the material ratio between 1.05∶1 and 1.4∶1,so corresponding mechanism of calcium ions phase transfer was dissolution-precipitation.It could found that both the conversion rate of calcium sulfate dihydrate and the calcium car-bonate particles size were increased with the increasing value of materials ratio.It indicated that the phase transfer rate of calcium ions was proportional to the material ratio.

  4. Repair of wounded monolayers of cultured bovine aortic endothelial cells is inhibited by calcium spirulan, a novel sulfated polysaccharide isolated from Spirulina platensis.

    Science.gov (United States)

    Kaji, Toshiyuki; Fujiwara, Yasuyuki; Inomata, Yuki; Hamada, Chieko; Yamamoto, Chika; Shimada, Satomi; Lee, Jung-Bum; Hayashi, Toshimitsu

    2002-03-08

    Calcium spirulan (Ca-SP) is a novel sulfated polysaccharide isolated from a blue-green alga Spirulina platensis. Ca-SP inhibits thrombin by activation of heparin cofactor II. Therefore, it could serve as an origin of anti-atherogenic medicines. Since maintenance of vascular endothelial cell monolayers is important for prevention of vascular lesions such as atherosclerosis, the effect of Ca-SP at 20 microg/ml or less on the repair of wounded bovine aortic endothelial cell monolayers in culture was investigated in the present study. When the monolayers were wounded and cultured in the presence of Ca-SP, the polysaccharide inhibited the appearance of the cells in the wounded area. The inhibition was also observed even when the repair was promoted by excess basic fibroblast growth factor, which is one of the autocrine growth factors that are involved in the endothelial cell monolayer maintenance. On the other hand, Ca-SP inhibited the cell growth and the incorporation of [3H]thymidine into the acid-insoluble fraction of proliferating endothelial cells, suggesting that Ca-SP inhibits endothelial cell proliferation. From these results, it is concluded that Ca-SP may retard the repair process of damaged vascular endothelium through inhibition of vascular endothelial cell proliferation by induction of a lower ability to respond to stimulation by endogenous basic fibroblast growth factor.

  5. Biocompatibility evaluation of dicalcium phosphate/calcium sulfate/poly (amino acid) composite for orthopedic tissue engineering in vitro and in vivo.

    Science.gov (United States)

    Wang, Peng; Liu, Pengzheng; Peng, Haitao; Luo, Xiaoman; Yuan, Huipin; Zhang, Juncai; Yan, Yonggang

    2016-08-01

    In vitro cytocompatibility of ternary biocomposite of dicalcium phosphate (DCP) and calcium sulfate (CS) containing 40 wt% poly (amino acid) (PAA) was evaluated using L929 fibroblasts and MG-63 osteoblast-like cells. Thereafter, the biocompatibility of biocomposite in vivo was investigated using an implantation in muscle and bone model. In vitro L929 and MG-63 cell culture experiments showed that the composite and PAA polymer were noncytotoxic and allowed cells to adhere and proliferate. The scanning electron microscope (SEM) confirmed that two kinds of cells maintained their phenotype on all of samples surfaces. Moreover, the DCP/CS/PAA composite showed higher cellular viability than that of PAA; meanwhile, the cell proliferation and ALP activity were much higher when DCP/CS had added into PAA. After implanted in muscle of rabbits for 12 weeks, the histological evaluation indicated that the composite exhibited excellent biocompatibility and no inflammatory responses were found. When implanted into bone defects of femoral condyle of rabbits, the composite was combined directly with the host bone tissue without fibrous capsule tissue, which shown good biocompatibility and osteoconductivity. Thus, this novel composite may have potential application in the clinical setting.

  6. Decontamination Using a Desiccant with Air Powder Abrasion Followed by Biphasic Calcium Sulfate Grafting: A New Treatment for Peri-Implantitis

    Directory of Open Access Journals (Sweden)

    Giorgio Lombardo

    2015-01-01

    Full Text Available Peri-implantitis is characterized by inflammation and crestal bone loss in the tissues surrounding implants. Contamination by deleterious bacteria in the peri-implant microenvironment is believed to be a major factor in the etiology of peri-implantitis. Prior to any therapeutic regenerative treatment, adequate decontamination of the peri-implant microenvironment must occur. Herein we present a novel approach to the treatment of peri-implantitis that incorporates the use of a topical desiccant (HYBENX, along with air powder abrasives as a means of decontamination, followed by the application of biphasic calcium sulfate combined with inorganic bovine bone material to augment the intrabony defect. We highlight the case of a 62-year-old man presenting peri-implantitis at two neighboring implants in positions 12 and 13, who underwent access flap surgery, followed by our procedure. After an uneventful 2-year healing period, both implants showed an absence of bleeding on probing, near complete regeneration of the missing bone, probing pocket depth reduction, and clinical attachment gain. While we observed a slight mucosal recession, there was no reduction in keratinized tissue. Based on the results described within, we conclude that the use of HYBENX and air powder abrasives, followed by bone defect grafting, represents a viable option in the treatment of peri-implantitis.

  7. The development and prospect for calcium sulfate whisker in Guizhou%贵州硫酸钙晶须的发展前景及展望

    Institute of Scientific and Technical Information of China (English)

    李聪聪; 虞江; 丁禹

    2012-01-01

    贵州省作为磷矿资源大省,长期生产磷肥而产生大量磷石膏,以对企业发展构成影响。硫酸钙晶须本身是一种性能优良,价格低廉的绿色环保材料。充分利用磷石膏生产磷石膏晶须,是典型的绿色化学工艺,不仅可以解决湿法磷酸的磷石膏堆积如山的难题,而且可以变废为宝,实现综合利用。%Calcium sulfate whisker (CSW) was an excellent,low price and green materials. As phosphate resource province, Guizhou's long - term production of phosphate fertilizer and produce large amounts of phosphogypsum made full use of phosphogypsum production of phosphogypsum whiskers, this typical green chemical processes not only can solve the problem of WPA mountains of phosphogypsum, but also turn waste into treasure.

  8. Crystallization of calcium sulfate dihydrate under simulated conditions of phosphoric acid production in the presence of aluminum and magnesium ions

    Science.gov (United States)

    Rashad, M. M.; Mahmoud, M. H. H.; Ibrahim, I. A.; Abdel-Aal, E. A.

    2004-06-01

    The effect of Al 3+ and Mg 2+ ions, as additives, on the crystallization of gypsum was studied under simulated conditions of the phosphoric acid production. Calcium hydrogen phosphate and sulfuric acid were mixed with dilute phosphoric acid at 80°C, and the turbidity of the reaction mixture was measured at different time periods to calculate the induction time of gypsum crystals formation. Addition of Al 3+ ions up to 2% decreased the induction time and increased the growth efficiency while addition of Mg 2+ increased the induction time and decreased the growth efficiency compared with in absence of additives. Interestingly, the crystals mean and median diameters were found to increase in the presence of Al 3+ and decrease in the presence of Mg 2+. The surface energy increased with Al 3+ and decreased with Mg 2+ compared to the baseline (without additives). Gypsum morphology changed from needle-like type in absence of additives to thick-rhombic in the presence of Al 3+ ions.

  9. Study on Isothermal Crystallization Kinetics of the Calcium Sulfate Whisker/PBS Blends%硫酸钙晶须/PBS共混物等温结晶动力学研究

    Institute of Scientific and Technical Information of China (English)

    杨海; 张宁; 卢翔; 瞿金平

    2013-01-01

    用差示扫描量热仪(DSC)测试了硫酸钙晶须/聚丁二酸丁二醇酯(PBS)共混物的等温结量过程.采用Hoffm-weeks方程拟合的方法得到了4种配比的硫酸钙晶须/PBS共混物的平衡熔点,并根据实验数据拟合出描述硫酸钙晶须/PBS共混物等温结晶过程的Avrami方程.结果表明:共混物的平衡熔点随着硫酸钙晶须含量的提高而降低;硫酸钙晶须的加入,对PBS的成核机理和生长方式没有明显的影响;等温结晶温度不影响共混物的结晶机理,但会影响结晶速率,等温结晶温度越高,结晶速率越慢.%The isothermal crystallization process of calcium sulfate whisker/poly(butylene succinate) (PBS) blends was observed by differential scanning calorimetry (DSC). The equilibrium melting points of the calcium sulfate whisker/PBS blends was obtained by using Hoffm-weeks equation fitting method, and the equilibrium melting point of blends decreased with the increase of calcium sulfate whisker content. The isothermal crystallization process was described by the classic Avrami equation. The Avrami equation was fitted by experimental data. The results show that: the calcium sulfate whisker has no significant effect on the mechanism of nucleation of the PBS, the isothermal crystallization temperature (Tc) can't affect the mechanism of crystallization of the blend, but it can affect the rate of crystallization; the higher Tc is, the slower the rate of crystallization is.

  10. 骨损伤修复用硫酸钙及其无机复合材料的研究进展%Progress of Calcium Sulfate and Inorganic Composites for Bone Defect Repair

    Institute of Scientific and Technical Information of China (English)

    杨国敬; 林勉; 张雷; 苟中入

    2013-01-01

    Treatments of bone defects caused by trauma,tumor and arthroplasty are challenging research area which has aroused great interests among biomaterial researchers to design and fabricate ideal artificial implants.Calcium sulfate has been used as biomedical bone cement for over a century,but its too fast bioresorption limits the applications in some clinical conditions.In this paper,its physicochemical properties,crystal polymorph and synthetic techniques are summarized.Furthermore,the recent research progress on calcium sulfate-based inorganic composite with hydroxyapatite,bioactive glasses,calcium phosphate cements and calcium silicate cements are reviewed.In addition,the development perspective on overcoming the shortcomings of calcium sulfate-base biomaterials is also discussed.%创伤、骨肿瘤、关节置换术等引起骨缺损的修复是目前临床治疗的难点和研究热点领域,寻找理想的骨修复材料已经成为该领域的重点研究方向.硫酸钙骨水泥作为骨修复材料已有百余年历史,有着显著的优势.但其降解过快的缺点影响了治疗效果,限制了应用范围.本文对硫酸钙的理化特性、晶粒形貌与晶型控制、合成方法等进行了系统介绍,总结了硫酸钙与羟基磷灰石、生物玻璃、磷酸钙和硅酸钙复合材料及其性能研究的新成果,并提出了克服硫酸钙作为骨修复材料的缺点的若干方法.

  11. Sulfate Resistance of Alite-barium Calcium Sulphoaluminate Cement%阿利特-硫铝酸钡钙水泥抗硫酸盐侵蚀性能的研究

    Institute of Scientific and Technical Information of China (English)

    李贵强; 芦令超; 王守德; 陈诚; 尹超男

    2009-01-01

    本文研究了石膏掺量对阿利特-硫铝酸钡钙水泥抗硫酸盐侵蚀性能的影响,并与硅酸盐水泥进行了比较;利用XRD,SEM-EDS等测试方法对侵蚀后水泥水化产物的物相组成和形貌进行了分析.研究结果表明:阿利特-硫铝酸钡钙水泥具有良好的抗硫酸盐侵蚀性能.当石膏掺量为5%时,阿利特-硫铝酸钡钙水泥的抗蚀系数达1.31,而硅酸盐水泥的抗蚀系数仅为0.94.石膏对阿利特-硫铝酸钡钙水泥硬化浆体的致密性有较大影响,进而影响水泥的抗硫酸盐侵蚀性能.同时,对阿利特-硫铝酸钡钙水泥的抗侵蚀机理进行了初步分析.%Effect of gypsum content on the sulfate resistance of alite-barium calcium sulphoaluminate cement was investigated. Portland cement was taken for comparison. The composition and microstructure of hardened cement pastes were analyzed by X-ray diffraction and scanning electron microscope. The results show that alite-barium calcium sulphoaluminate cement has better ability of sulfate resistance. The coefficient of resistance to sulfate attack with 5% gypsum addition in alite-barium calcium sulphoaluminate is 1.31, while that in Portland cement is only 0.94. Gypsum can affect the tightness of alite-barium calcium sulphoaluminate cement hardened pastes and further influence the ability of resistance to sulfate attack. At the same time, the mechanism of sulfate resistance of alite-barium calcium sulphoaluminate cement was discussed in this paper.

  12. Calcium sulfate as pigment for improved functional properties of coated paper%硫酸钙作为颜料改进涂布纸的功能性质

    Institute of Scientific and Technical Information of China (English)

    张金朝

    2015-01-01

    In the last few years, interest and demand of high bright paper have forced paper manufacturers to think new ways to improve brightness and whiteness of coated paper. Pigment coating is widely used to enhance the optical properties such as brightness, whiteness, and gloss of paper and paperboard. These optical properties are the most important for end user and also determine the final cost of coated paper. Calcium sulfate has inherent better optical properties compared to other conventional pigments for example ground calcium carbonate, precipitated calcium carbonate and kaolin clay. The present study was carried out with an aim to synthesize calcium sulfate using waste procured from phosphoric acid industry and to study its impact on the rheology of coating color as well as optical properties of coated paper. Addition of calcium sulfate improved the water retention property of coating color which can be helpful for improving the machine runnability. The results also revealed that calcium sulfate can be used as a pigment to produce coated paper of high brightness and whiteness. The brightness and whiteness of the coated paper were improved 4 and 15 points, respectively by using 50 parts of calcium sulfate as a pigment replacing clay from the coating formulation. The surface strength in terms of IGT pick value of coated sheets was found signiifcantly comparable using calcium sulfate as pigment. The print gloss results were observed analogous with matt grade coated paper.%在过去的几年间,人们对于高亮度纸的关注和需求已经驱使造纸厂家探寻新的方法来提高涂布纸的亮度和白度。用以提高纸和纸板光学性能(如亮度、白度和光泽度)的颜料涂布得到广泛应用。这些光学性质对于最终使用者非常重要,同时也决定了涂布纸的最终成本。相比于其它的常规颜料,如重质碳酸钙、沉淀碳酸钙和高岭土,硫酸钙具有固有的更好的光

  13. Mechanics, degradability, bioactivity, in vitro, and in vivo biocompatibility evaluation of poly(amino acid)/hydroxyapatite/calcium sulfate composite for potential load-bearing bone repair.

    Science.gov (United States)

    Fan, Xiaoxia; Ren, Haohao; Luo, Xiaoman; Wang, Peng; Lv, Guoyu; Yuan, Huipin; Li, Hong; Yan, Yonggang

    2016-03-01

    A ternary composite of poly(amino acid), hydroxyapatite, and calcium sulfate (PAA/HA/CS) was prepared using in situ melting polycondensation method and evaluated in terms of mechanical strengths, in vitro degradability, bioactivity, as well as in vitro and in vivo biocompatibility. The results showed that the ternary composite exhibited a compressive strength of 147 MPa, a bending strength of 121 MPa, a tensile strength of 122 MPa, and a tensile modulus of 4.6 GPa. After immersion in simulated body fluid, the compressive strength of the composite decreased from 147 to 98 MPa for six weeks and the bending strength decreased from 121 to 75 MPa for eight weeks, and both of them kept stable in the following soaking period. The composite could be slowly degraded with 7.27 wt% loss of initial weight after soaking in phosphate buffered solution for three weeks when started to keep stable weight in the following days. The composite was soaked in simulated body fluid solution and the hydroxyapatite layer, as flower-like granules, formed on the surface of the composite samples, showing good bioactivity. Moreover, it was found that the composite could promote proliferation of MG-63 cells, and the cells with normal phenotype extended and spread well on the composite surface. The implantation of the composite into the ulna of sheep confirmed that the composite was biocompatible and osteoconductive in vivo, and offered the PAA/HA/CS composite promising material for load-bearing bone substitutes for clinical application.

  14. Application of Anhydrous Calcium Sulfate as a Partial Replacement for Titanium Dioxide%无水硫酸钙部分替代钛白粉的应用

    Institute of Scientific and Technical Information of China (English)

    黄明杰; 邵聂

    2013-01-01

    The present price of titanium dioxide is high, but research of titanium composite pigment in domestic is still in the initial stage. Titanium dioxide has many advantages, but people have to consider other products replacing titanium dioxide due to its expensive price. In order to save the expensive titanium dioxide and reduce costs, people have been actively researched and developed and used efficient and inexpensive extender pigments instead of titanium dioxide for a long time. It is imperative to research new product replacing titanium dioxide partly. Because calcium sulfate has good whiteness and gelling property, it can partly replace titanium dioxide in the coating, maximum substitution is 20%of titanium dioxide.%  目前钛白粉的价格居高不下,而且在国内钛复合颜料的研究尚处于起步阶段。钛白粉具有很多优势,但是其昂贵的价格让人们不得不考虑采用其他的产品来替代钛白粉。为了节省昂贵的钛白粉,降低成本,长期以来人们都积极地研究和开发利用高效价廉的体质颜料取代钛白粉,研究新的产品部分替代钛白粉势在必行。由于硫酸钙具有良好的白度以及胶凝性,故可部分替代钛白粉添加到涂料中,最大替代量为钛白粉用量的20%。

  15. A glass-reinforced hydroxyapatite and surgical-grade calcium sulfate for bone regeneration: In vivo biological behavior in a sheep model.

    Science.gov (United States)

    Cortez, Paulo Pegado; Silva, Marta Alves; Santos, Marta; Armada-da-Silva, Paulo; Afonso, Amrico; Lopes, Maria A; Santos, Jose Domingos; Maurício, Ana Colette

    2012-08-01

    A glass-reinforced hydroxyapatite (HA) composite (Bonelike®) was developed for bone grafting. This biomaterial is composed of a modified HA matrix with α- and β-tricalcium phosphate secondary phases, resulting in higher solubility than single HA type of materials. Several in vitro and in vivo studies demonstrated that Bonelike® has a highly bioactive behavior, which was also confirmed by employing granular forms of this biomaterial in orthopedics and dental applications. However, a fast consolidation vehicle was needed to promote the fixation of Bonelike® granules if applied in larger defects or in unstable sites. Surgical-grade calcium sulfate (CS), which is widely recognized as a well-tolerated and inexpensive bone graft material, was the chosen vehicle to improve the handling characteristics of Bonelike® as it can be used in the form of a powder that is mixed with a liquid to form a paste that sets in situ. After application in non-critical monocortical defects in sheep, histological, and scanning electron microscopy evaluations demonstrated that Bonelike® associated to CS functioned as a very satisfactory scaffold for bone regeneration as it achieved synchronization of the ingrowing bone with biomaterial resorption and subsequent preservation of the bone graft initial volume. Therefore, our results indicate that CS is an effective vehicle for Bonelike® granules as it facilitates their application and does not interfere with their proven highly osteoconductive properties. In the opposite way, the incorporation of Bonelike® improves the bone regeneration capabilities of CS.

  16. 晶形助长剂对磷石膏制硫酸钙晶须性能的影响%Influence of crystal growing agent on properties of calcium sulfate whisker with phosphogypsum

    Institute of Scientific and Technical Information of China (English)

    杨林; 周杰; 李贺军; 曹建新

    2012-01-01

    借助X射线衍射、扫描电子显微镜等分析方法,研究了晶形助长剂对以磷石膏为原料水热法制备硫酸钙晶须生长行为的影响.结果表明,以磷石膏为原料制备硫酸钙晶须适宜的晶形助长剂为氯化镁(掺量为磷石膏质量的1.0%),其次为十二烷基磺酸钠,效果最差的是硫酸铝.%Influence of crystal growing agent on growth behavior of calcium sulfate whisker,which was prepared by hydrothermal method with phosphogypsum as raw material, was studied and analyzed by means of XRD and SEM etcResults showed that when the calcium sulfate whisker was prepared from phosphogypsum, the proper crystal growing agent was magnesium chloride (doping amount was 1.0% of phosphogypsum) .The next-proper crystal growing agent was sodium dodecyl sulfonate and the worst was aluminum sulfate.

  17. 磷石膏-碳铵-氨水球磨制备硫酸铵和碳酸钙%Ammonium Sulfate and Calcium Carbonate Prepared by Ball-milling from Phosphogypsum-Ammonium Bicarbonate-Ammonia Water

    Institute of Scientific and Technical Information of China (English)

    李娜; 邓跃全; 董发勤; 罗绍东; 李珊珊; 彭宝瑶

    2013-01-01

    Ammonium sulfate and calcium carbonate were prepared using phosphogypsum, ammonium bicarbonate and ammonia water as raw materials by ball-milling technique. The optimum conditions were explored through orthogonal test, the major elements and phase composition of two kinds of products were analyzed by XRF and XRD, and the grain size distribution and poisonous elements of calcium carbonate were determined using laser particle size analyzer and ICP. The analysis results showed that the optimum technological conditions were as follows: the liquid-solid ratio was 0.5, the response time was 45 min, the ball-material ratio was 3:1, rotational speed was 600 r/min, and the average conversion reaction was up to 97.95%; the product quality of ammonium sulfate reached the standard of byproduct ammonium sulfate, poisonous and harmful elements contents of calcium carbonate were far lower than quality criteria of soil environment allows. Preparation of ammonium sulfate and calcium carbonate from phosphogypsum by ball-milling achieved the purpose of effectively using phosphogypsum.%  以磷石膏、碳酸氢铵和氨水为原料,采用球磨工艺制备硫酸铵和碳酸钙.通过正交试验设计,探索磷石膏球磨制备硫酸铵和碳酸钙的最佳工艺条件,采用 XRF 和 XRD 分析了2种产物的化学组成及物相组成,采用激光粒度仪和 ICP 分别测定了碳酸钙的粒度分布及有毒有害元素含量.结果表明,球磨制备硫酸铵和碳酸钙适宜的工艺条件为:液固比0.5,反应时间45 min,球料比3∶1,转速600 r/min,反应的平均转化率达97.95%;硫酸铵产品质量达到了副产硫酸铵标准,碳酸钙中有毒有害元素的含量远低于土壤环境质量标准要求.磷石膏球磨制备硫酸铵和碳酸钙,实现了磷石膏的高效利用.

  18. Research on purification of phosphogypsum and preparation of calcium sulfate whisker%磷石膏的净化处理及制备硫酸钙晶须的研究

    Institute of Scientific and Technical Information of China (English)

    杨荣华; 宋锡高

    2012-01-01

    New methods of purification and comprehensive utilization of phosphogypsum were experimentally studied.On the basis of physical testing of phosphogypsum samples,including particle size distribution,XRD mineral analysis,chemical analysis,and SEM morphology analysis,phosphogypsum was treated with low-cost ammonium bicarbonate,ammonia,and industrial by-product hydrochloric acid,and calcium sulfate(CaSO4) was obtained by removing impurities.Meanwhile,by-product ammonium chloride was also got and carbon dioxide could be recovered.Then CaSO4was applied as raw material to prepare calcium sulfate whisker by hydrothermal method, so as to enhance the application value of phosphogypsum.Optimal conditions of phosphogypsum purification and hydrothermal method of calcium sulfate whisker were obtained by experiments, the morphologies of calcium sulfate and calcium sulfate whisker were analyzed by POM and SEM.Results showed that the experimental process route was technically feasible, the process equipment and operating conditions were simple, the mother liquor could be recycled, no ' three waste' pollution, so it not only reduced environmental pollution, but also cut down the production costs.Therefore, it had good economic and social benefits.%实验研究磷石膏净化处理方法及化工综合利用新路.在对磷石膏样品进行粒度分布、XRD矿物分析、化学成分分析和SEM形貌分析等物性检测的基础上,利用廉价的碳酸氢铵和氨水及工业副产盐酸,对磷石膏进行净化处理,去除杂质提纯得到硫酸钙,副产氯化铵并回收二氧化碳.以磷石膏提纯得到的硫酸钙为原料,采用水热法制备硫酸钙晶须,提升磷石膏的利用价值.实验得到磷石膏净化处理和水热法制备硫酸钙晶须的最优化工艺条件,并通过POM与SEM对所得硫酸钙样品和硫酸钙晶须进行形貌分析.结果表明,工艺路线在技术上是可行的,工艺设备和操作条件简单、母液

  19. Study on the Calcium Sulfate Crystallization Law in the Isothermal Evaporation of Desalination Brine%海水淡化浓盐水等温蒸发过程硫酸钙析出规律研究

    Institute of Scientific and Technical Information of China (English)

    陈丽芳; 刘同慧; 詹志斌; 陈侠

    2011-01-01

    海水淡化在获得淡水的同时副产大量浓盐水,浓盐水的盐度、温度等均高于自然海水,如在渤海湾内直接大量排放浓盐水势必会对周围海洋环境造成污染,为此实现浓海水资源的综合利用势在必行.研究浓海水不同温度下等温蒸发过程硫酸钙的析出规律可以为浓海水综合利用提供理论依据.室内试验研究表明:不同温度下等温蒸发时硫酸钙析出点稍有变化,30℃等温蒸发硫酸钙析出点为密度1.108 8 g/cm3,此时水分蒸发率为58.4%,溶液硫酸钙质量分数5.4g/kg;50℃等温蒸发硫酸钙析出点为密度1.1094g/cm3,此时水分蒸发率为60.1%,溶液硫酸钙质量分数5.6 g/kg;75℃等温蒸发硫酸钙析出点为密度1.1000g/cm3,此时水分蒸发率为60.3%,溶液硫酸钙质量分数5.8 g/1000 g;100℃等温蒸发硫酸钙析出点为密度1.0680g/cm3,此时水分蒸发率为53.4%,溶液硫酸钙质量分数4.4g/1000g.%While gaining the fresh water in desalination, a large amount of brine appears as byproduct. Both the salinity and temperature of the brine are higher than nature seawater. If great quantities of brine are discharged directly into the Bohai bay, it will inevitably pollute the surrounding marine environment. Therefore, it is imperative to enforce the comprehensive utilization of concentrated seawater. The research which studies the law of calcium sulfate precipitation in the process of isothermal evaporation at different temperatures lays a fundamental theoretical basis for the comprehensive utilization of seawater. The results of laboratory experiment show that; in the process of isothermal evaporation the point of calcium sulfate crystallization changes slightly at different temperatures. In the process of 30℃ isothermal evaporation, when the calcium sulfate crystallizes, the density is 1.1088 grams per liter, water evaporation rate is 58.4% , and the concentration of calcium sulfate is 5.4 g/kg. While in the condition of

  20. 分光光度法测定磷石膏钙渣中硫酸根含量%Spectrophotometric determination of sulfate radicals in calcium slag of phosphogypsum

    Institute of Scientific and Technical Information of China (English)

    贾洪秀; 朱云勤; 朱必学; 刘健; 张頔

    2011-01-01

    钙渣中含有杂质硫酸根,其含量给磷石膏钙渣制备轻质碳酸钙工艺中除杂过程带来负担,同时是影响轻质碳酸钙产品质量的一个重要指标.用铬酸钡分光光度法测定磷石膏钙渣中的硫酸根,建立了一个简单、快速、选择性较好的钙渣中硫酸根的测定方法.在410 nm波长处,硫酸根为0.00~6.00mg/mL时与铬酸根吸光度呈线性关系,线性回归方程为y=0.168 4x+0.003 2,r=0.999 9,相对标准偏差优于10%,加标回收率在96%~102%.该法可用于测定钙渣中硫酸根含量,操作简单,可行性强,可以满足测定要求并应用于实时监控.%Sulfate radical is contained in calcium slag, which is an important index influencing the quality of precipitated calcium carbonate (PCC ) and it will increase the load to the impurity removing process during manufacturing PCC.Barium chromate spectrophotometry was adopted to determine sulfate radicals in calcium slag of phosphagypsum and a simple and rapid determination method with good selectivity has been established. At wavelenth of 410 nm,when the mass concentration of suffate radicals is at 0.00 ~ 6.00 mg/mL and it has a linear relation with chromate radicals. Linear recession equation and the correlation coefficient are y = 0.168 4x +0.003 2 and r = 0. 999 9 respectively. Relative standard deviation is less than 10% ,and the standard sample recovery rates are at 96% ~ 102%. This method is applied to the determination of sulfate radicals in calcium slag and has advantages of simplicity and strong feasibility, which can satisfy the determination requirements and can be used for real time monitor.

  1. 硫酸钙防垢剂的合成与性能评价%Synthesis and Performance Evaluation of Inhibitor for Calcium Sulfate Scale

    Institute of Scientific and Technical Information of China (English)

    李建波; 钟小芳; 李永会; 税敏; 任卉

    2012-01-01

    A scale inhibitor, poly(maleic anhydride-acrylic acid-sodium allylsulfonate) terpolymer(BSI), was synthesized by the copolymerization of maleic anhydride, acrylic acid and sodium allylsulfonate with ammonium persulfate as the initiator. The effects of BSI concentration, temperature, time, pH, NaCl concentration and the concentrations of scale-forming ions(Ca2+and SO2-4) on the scale inhibition rate of BSI for calcium sulfate scale were studied. The effect of the BSI concentration on the scale inhibition rate with high Ca2+and SO2-4 concentrations was investigated. The results show that the scale inhibition rate would be 99.0% under the conditions of 70 ℃, 25 h, p(BSI) 3 mg/L, c(Ca2+) 0.1 mol/L, c(SO2-4) 0.1 mol/L, system pH 8 and p(NaCl) 7.5 g/L. The scale-forming ion concentration has a great influence on the scale inhibition rate. With increasing the BSI concentration, its scale inhibition effect for the solution with high scale-forming ion concentration is better and under the conditions of c(Ca2+) 0.6 mol/L, c(SO2-4) 0.6 mol/L and p(BSI) 220 mg/L the scale inhibition rate can reach 99.0%. According to the characteristics of the molecular structure of BSI, its inhibition mechanism was analyzed, in which BSI and Ca formed a complex. The dispersion flocculation and lattice distortion of BSI were discussed also.%以顺丁烯二酸酐、丙烯酸和烯丙基磺酸钠为原料,以过硫酸铵为引发剂,经共聚反应制得硫酸钙防垢剂聚顺丁烯二酸酐-丙烯酸-烯丙基磺酸钠三元共聚物(BSl);考察了BSI含量、温度、时间、体系pH、NaCl含量、成垢离子(Ca2+和SO42-)浓度对防垢率的影响,同时考察了BSI含量对高浓度成垢离子溶液防垢率的影响.实验结果表明,在70℃、25 h、ρ(BSI) =3mg/L、c (Ca2+)=c(SO42-) =0.1 mol/L、体系pH=8、ρ(NaCl) =7.5 g/L的条件下,防垢率为99.0%.成垢离子浓度对BSI的防垢率影响很大,对于高浓度成垢离子溶液,增加BSI用量仍可使其具有较

  2. 添加剂辅助水热法制备硫酸钙晶须及生长机理研究%Additives-Assisted Hydrothermal Synthesis of Calcium Sulfate Whisker and Its Growth Mechanism

    Institute of Scientific and Technical Information of China (English)

    杨娜; 肖汉宁; 郭文明

    2014-01-01

    The influence of additives (i.e.,magnesium chloride,citric acid,sodium dodecyl benzene sulfonate (SDBS)and so-dium oleate)on the growth behavior of calcium sulfate whisker synthesized with desulfurization gypsum by a hydrothermal process was investigated.The hydrothermal products obtained with or without additives are a half-water calcium sulfate whisk-er.However,the whisker obtained without additive appears short and thick.Magnesium chloride does not affect the growth of whisker,and citric acid inhibits the growth of whisker.SDBS plays a certain role on the promotion of whisker growth.The morphology of the product is inhomogeneous,and granular calcium sulfate appears.However,sodium oleate has a promoting effect on the growth of calcium sulfate whisker.Needle-like whiskers with 50-200μm in length and about 1μm in diameter are obtained.For the stabilization of the whiskers,calcining process was used to obtain insoluble anhydrous calcium sulphate whiskers.In addition,the promoting mechanism of the sodium oleate on the hydrothermal process of the whisker was also dis-cussed.%以脱硫石膏为原料,采用水热法再结晶工艺,研究了氯化镁、柠檬酸、十二烷基苯磺酸钠(SDBS)和油酸钠对硫酸钙晶须生长行为的影响。结果表明:在一定温度下,水热再结晶产物晶相均为半水硫酸钙;未加添加剂的脱硫石膏经水热转化可以形成硫酸钙晶须,但产物长径比小,晶须短而粗。氯化镁对晶须的生长无明显促进作用;柠檬酸会抑制晶须的生长;SDBS对晶须的生长有一定的促进作用,但产物形貌不均匀,出现颗粒状硫酸钙;油酸钠对晶须生长有较好的促进作用,可获得形貌均匀、长50~200μm、直径约1μm的高长径比的针状晶须,经煅烧可得到稳定化的无水死烧硫酸钙晶须。在此基础上探讨了油酸钠在水热转化过程中对晶须生长的作用机理。

  3. The use of nanocrystalline and two other forms of calcium sulfate in the treatment of infrabony defects: A clinical and radiographic study

    Science.gov (United States)

    Pandit, Nymphea; Sharma, Aditi; Jain, Ashish; Bali, Deepika; Malik, Rajvir; Gugnani, Shalini

    2015-01-01

    Background: Calcium sulphate(CS) is one of the oldest alloplastic graft materials used because of its biocompatibility, handling characteristics, porosity, different rates of dissolution, chemico-physical resemblance to bone mineral, ability to induce release of growth factors and potentially unlimited supply at a modest cost. Aim of the study was to evaluate the efficacy of 3 forms of calcium sulphate i.e. Nanogen (nCS)(+), BoneGen(+) and Dentogen(+) in treatment of infrabony defects and to compare their efficacy as bone grafting substitutes. Materials and Methods: A prospective randomized, double blind controlled study was conducted on 45 sites from 16 subjects having Moderate to Advanced Periodontitis who were divided into 3 groups i.e. Group I (Nanogen), Group II (Dentogen) and Group III (BoneGen) clinical along with radiographic measurements were taken at baseline, 6 and 12 months postoperatively. Results: There was no significant inter-group difference in mean clinical attachment level (CAL) values at different time intervals whereas Intra-group changes in CAL at 6 and 12 months as compared to baseline were significant statistically. In Group I, changes in CAL between 6 and 12 months were found to be statistically significant in comparison with Group II and III. Conclusion: Both Nanogen and BoneGen TR can be considered valuable options in the treatment of infra-bony periodontal defects. The faster degradation of Dentogen may negatively affect its bone regeneration potential. PMID:26644722

  4. Experimental research of injectable calcium sulfate-based bone graft in the sheep femur bone defects%可注射硫酸钙基人工骨在羊股骨缺损植骨中的实验研究

    Institute of Scientific and Technical Information of China (English)

    王逢贤; 尹本敬; 俞兴; 曹旭; 徐林

    2012-01-01

    [目的]通过可注射性植骨材料在羊股骨缺损的骨内植入,评价可注射硫酸钙基植骨材料的骨修复能力.[方法]建立绵羊单侧股骨缺损模型,将可注射硫酸钙基人工骨植入骨缺损内,于术后4、8、12周行大体观察及X线片检查缺损区骨痂生长情况.[结果]术后4周时材料大部分降解吸收,可见新生骨小梁结构,缺损区有部分骨痂形成;8周时可见大量新生骨小梁结构,部分形成成熟骨单位,可见骨母细胞,新生骨与宿主骨界面模糊,完成断端间的骨性桥接;12周时材料完全降解,形成的新生骨小梁部分出现重塑形成正常骨结构,缺损区被新骨完全替代,骨痂开始塑形,髓腔再通.[结论]可注射硫酸钙基人工骨作为骨移植替代材料,具有良好的骨传导性和骨诱导性,用于修复骨缺损可以取得良好的效果.%[Objective]To evaluate the osteogenetic ability of injectable calcium sulfate-based bone graft substitute by applying injectable bone graft material in the sheep femur bone defects. [ Method] The sheep unilateral femoral defect model was established, and the injectable calcium sulfate-based bone graft substitute was implanted into the bone defect. The callus growth was investigated at 4,8 and 12 weeks after surgery by gross observation and X-ray examination. [ Result] At 4 weeks after operation the majority of material was degraded and absorbed. New trabecular bone structure and some defect of callus formation were noted. At 8 weeks after operation a large number of new trabecular bone structure could be seen. Part of mature bone unit were formed, osteoblasts were noted, new bone was blurred at the host bone interface, and bone bridging was completed between the ends. At 12 weeks after operation material was degraded completely, the new bone grew into normal structure,and the defect was completely replaced by new bone. [ Conclusion ] Injectable calcium sulfate-based bone as a bone graft substitute

  5. 半水硫酸钙人工骨治疗颌骨囊肿术后骨缺损的临床效果%Clinical application of calcium sulfate hemihydrate for bone defect caused by jaw cyst

    Institute of Scientific and Technical Information of China (English)

    邓天政; 吕晶; 汪正文; 杨捷绯; 柯杰

    2013-01-01

    目的 研究使用半水硫酸钙人工骨治疗颌骨缺损的效果,探讨该方法的应用前景.方法 16例颌骨囊肿术后患者,植骨组6例采用Osteoset半水硫酸钙人工骨填充颌骨囊肿术后遗留的骨腔,对照组10例不植入人工骨.并于术后1d、1个月、3个月拍曲面断层片,观察愈合情况和修复效果.结果 所有患者未出现感染和排异反应.植骨组2例患者术后3d出现眶下区肿胀,及时引流后伤口完全愈合.术后3个月内曲面断层片提示新骨逐渐形成,人工骨逐渐吸收,成骨效果满意.对照组患者均出现不同程度肿胀,新骨形成时间晚于植骨组.结论 医用半水硫酸钙人工骨是一种成骨性能优良的骨移植替代材料,具有较好的临床应用前景.%Objective To treat bone defect caused by jaw cyst using calcium sulfate hemihydrate, to observe the results of postoperation, and to discuss the method and application prospect. Methods Osteoset bone was used to fill the bone space of patients caused by jaw cyst. After 1 day, 1 month, 3 months, 6months of operation, the results was observed through X-ray examination. Results All patients had no infection or immunological rejection. The infraorbital region of 2 patients swelled at the third days, but the wounds healed fully after drainage. Six months after postoperation, the new bone were built up, osteoset bone was absorbed graduelly. The clinical results was satisfactory. Conclusion Calcium sulfate hemihydrate is a good choice of osteoblast bone graft substitute materials, and the excellent capacities of osteogenesis allows it to be used broadly in clinical practice.

  6. Congenital fibrosarcoma in complete remission with Somatostatin, Bromocriptine, Retinoids, Vitamin D3, Vitamin E, Vitamin C, Melatonin, Calcium, Chondroitin sulfate associated with low doses of Cyclophosphamide in a 14-year Follow up.

    Science.gov (United States)

    Di Bella, Giuseppe; Toscano, Rosilde; Ricchi, Alessandro; Colori, Biagio

    2015-01-01

    At birth, a male child presented a 6 cm tumour in the right leg. The tumour was partially removed after just 12 days. Histology showed a congenital fibrosarcoma associated with reactive lymphadenitis. A first cycle of adjuvant chemotherapy did not prevent the rapid progression of the disease. Subsequent evaluation for surgical removal raised serious concerns due to the need for a major operation involving total amputation of the right leg and hemipelvectomy. Since surgery could not exclude the possibility of disease recurrence and since the traditional cycles of chemotherapy did not offer any possibility of a cure, the parents opted for the Di Bella Method. The combined use of Somatostatin, Melatonin, Retinoids solubilized in Vit. E, Vit. C, Vit. D3, Calcium, and Chondroitin sulfate associated with low doses of Cyclophosphamide resulted in a complete objective response, still present 14 years later, with no toxicity and without the need for hospitalization, allowing a normal quality of life and perfectly normal adolescent psycho-physical development.

  7. Physicochemical properties of chitosan microspheres/silk fibroin/calcium sulfate bone cement%壳聚糖微球复合丝素基硫酸钙骨水泥的理化特性

    Institute of Scientific and Technical Information of China (English)

    王鹏; 皮斌; 王金宁; 朱雪松; 杨惠林

    2014-01-01

    背景:脊柱成形和脊柱后凸成形治疗中采用的硫酸钙骨水泥理化性质好,对人体无毒性作用,同时具有降解性能,但单独使用降解较快。  目的:研制具有载药缓释功能的壳聚糖微球丝素基硫酸钙骨水泥。  方法:采用三聚磷酸钠乳化交联法制备壳聚糖微球。采用浓度分别为3%,6%,9%的丝素溶液与CaSO4•0.5H 2 O混合,通过万能力学试验机确定骨水泥力学性能最佳时的丝素浓度,在此浓度下,按壳聚糖微球占CaSO 4•0.5H 2 O的质量比分别为0.5%,1%,5%的比例制备壳聚糖微球丝素基硫酸钙骨水泥,测定其抗压强度,并通过X射线多晶衍射仪及傅里叶红外光谱明确达到最佳抗压强度组的骨水泥成分,电镜观察复合骨水泥中壳聚糖微球的形态。  结果与结论:当丝素溶液浓度为6%,壳聚糖微球含量为0.5%时,复合骨水泥的抗压强度最大,为(39.17±1.96) MPa,此时复合骨水泥的初凝时间为(12.99±1.63) min,终凝时间为(21.55±0.54) min;骨水泥中主要晶相组成为硫酸钙,傅里叶红外光谱结果证实复合骨水泥中含有丝素及壳聚糖;复合骨水泥中的微球表面稍有皱缩,但球形仍然完整,未见明显破坏,可见在制备复合骨水泥的过程中微球能保持稳定而不被破坏。%BACKGROUND:Calcium sulfate used in kyphoplasty and vertebrolplasty has good physical and chemical properties, exerts no toxic effects on human body and has the degradation performance. But its main drawback is rapid degradation. OBJECTIVE:To develop a chitosan microsphere with silk fibroin/calcium sulfate cement to prepare drug carrier system. METHODS:Chitosan microspheres were prepared by the emulsion method. Scanning electron microscopy, particle size analysis and swel ing rate were used to study the properties of the microspheres. Different silk concentrations (3%, 6%and 9%) and weight rates (0

  8. 硫酸钙骨水泥强化骨质疏松绵羊腰椎的生物力学研究%Biomechanical study on augmentation of osteoporotic sheep vertebrae with calcium sulfate cement:in vivo study

    Institute of Scientific and Technical Information of China (English)

    张军华; 张炼

    2012-01-01

    目的 评价硫酸钙骨水泥(CSC)强化骨质疏松绵羊腰椎力学强度的效果.方法 成年雌性绵羊4只,行去势手术后饲养1年,测量去势前后腰椎骨密度.取L2~5共16个椎体,分为CSC组和对照组,每组8个椎体.CSC组经椎弓根向椎体内注射CSC(2.0 ml),对照组不给于任何处理.CSC组于术后12周测量L2~5单个椎体的骨密度,然后处死绵羊.取出椎体行压缩实验,测量各组中椎体的最大压缩应力(σult)和能量吸收值(EAV).结果 去势1年后绵羊腰椎骨密度显著下降,与去势前比较差异有统计学意义(P<0.05),骨质疏松绵羊模型建立成功.注射CSC 12周后椎体骨密度(BMD)、σult、EAV均高于对照组(P<0.05),且椎体的σult和EAV均与BMD成正相关关系(P<0.05).结论 CSC可以提高骨质疏松椎体的BMD,强化骨质疏松椎体的力学强度,有利于避免或减少骨质疏松椎体骨折的风险.%Objective To evaluate biomechanical performance of osteoporotic lumbar vertebral body augmented with calcium sulfate cement ( CSC ) in ovariectomized sheep. Methods Four female adult sheep were treated with bilateral ovariectomy. Bone mineral density ( BMD ) of lumbar vertebrae of all sheep was measured before the treatment and one year after of the treatment. L2 ~ L5 of each sheep and total 16 vertebrae were grouped into CSC and blank group with 8 vertebrae in each group. In CSC group, vertebrae were augmented with CSC( 2. 0 ml ) through transpedicular approach. There was no augmentation in blank group. Each vertebra BMD of L2 ~ L5 in CSC group was measured 12 weeks later. Then all sheep were killed and L2 ~ L5 were prepared for compression test. The ultimate compared stres-ses( (σult )and energy absorption value( EAV )of each group were recorded. Results There was a significant decrease in average BMD of lumbar one year after ovariectomy( P < 0. 05 ). The osteoporotic lumbar vertebral experiment was successful. 12 weeks after augmentation with CSC

  9. 氨基酸聚合物/硫酸钙生物工程骨的生物相容性研究%Study on biocompatibility of poly (amino acid)/calcium sulfate composite as bioengineering bone

    Institute of Scientific and Technical Information of China (English)

    苏保; 蒋电明; 严永刚; 赵增辉; 李军

    2011-01-01

    Objective To evaluate the biocompatibility of poly ( amino acid)/calcium sulfate ( PAA/CaSO4 ) composite as bioengineering bone. Methods The PAA in the composite consists of 6-aminohexanoic acid, glycine, alanine, phenylalanine, proline, lysine, and hydroxyproline. Physiological saline lixivium of the composite was used in acute toxicity test, hemolysis test, micronucleus test, intradermal irritation test, pyrogen test, and cytotoxicity test to evaluate the biocompatibility of the material. Results The activity of mice was normal in the acute toxicity test. No animal died and no toxicity symptom or adverse effect was shown within 7 d. The average daily weight increases showed no statistically significant difference ( P > 0.05 ) between the experimental and control groups after 7 d. The hemolysis rate of the lixivium was 2.01%, which was lower than the national standard ( < 5% ). The micronucleus rates showed no statistically significant difference (P >0. 05 ) between three experimental groups and the negative control group ( each group' s micronucleus rate was between 0.4 and 0.6), and potential mutagenicity was not observed in the micronucleus test. The maximum increase of body temperature in the experimental group was 0.4 ℃, and the total body temperature increase of the three experimental animals was 1.1 ℃, which met the national standard ( < 1.4 C ). Intradermal irritation test results showed no obvious erythema, edema, or skin necrosis in the experimental and negative control groups, with a primary irritation index of 0.01 -0.02, indicating very slight irritation. In the cytotoxicity test,the relative growth rates of two experimental groups and the negative control group were all above 90%, and the toxicity of PAA/CaS04 composite lixivium was graded 0 or 1, indicating no cytotoxicity. Conclusion PAA/CaSO4 composite has good biocompatibility.%目的 评价氨基酸聚合物[poly(amino acid),PAA]/硫酸钙(calcium sulfate,CaSO4)生物工

  10. Preparation and biocompatibility of a novel strontium-containing calcium sulfate%新型含锶硫酸钙的制备及其生物相容性试验

    Institute of Scientific and Technical Information of China (English)

    侯毅龙; 李雪; 许长鹏; 宋锦旗; 黄磊; 余斌

    2016-01-01

    Objective To prepare a novel strontium-containing calcium sulfate and assess its and biocompatibility. Methods A novel strontium-containing α-calcium sulfate hemihydrate (Sr-caS) bone substitute as prepared with hydrothermal reaction and examined for X-ray diffraction (XRD), Fourier transform infrared (FTIR) and thermogravimetric differential scanning calorimetric (TG-DSC) patterns. The biocompatibility of the material was evaluated by in vitro cytotoxicity test in L-929 cells, hemolysis test of blood, and in vivo implantation test in SD rats. Results The XRD spectra of the prepared Sr-CaS powder highlighted 3 strong characteristic peaks ofα-CaSO4 at 14.63° , 25.72° and 29.80° with a strontium-specific peak at 24.78° . The FTIR patterns of Sr-CaS resembled those of CaS. TG-DSC results showed that the material contained a non-evaporable water content of 6.03%. In vitro cytotoxicity test in L-929 cells suggested that the material had a class 1 cytotoxicity, and the hemolysis rate of its aqueous extract was 4.3%. The material implanted in the muscular tissues of SD rats maintained a steady state in the surrounding tissues. Conclusion This strontium-containing calcium sulfate material we prepared shows an excellent biocompatibility for potential use as a novel artificial bone material.%目的:制备一种新型含锶硫酸钙材料并对其进行生物相容性评价。方法探讨采用水热法制备一种新型的含锶硫酸钙并对制备的材料进行:(1)X线衍射、傅里叶变换红外光谱及差式量热扫描表征检测,以验证材料为目标产物;(2)细胞毒性试验评估材料浸提液对L-929小鼠成纤维细胞形态学及相对增殖率的影响;(3)溶血试验评估材料浸提液的血液相容性;(4)体内植入试验评估其对活体组织局部毒性反应。结果(1)X线衍射结果示:14.63°,25.72°和29.80°处可见α-半水硫酸钙的特征峰,在24.78°处可见锶元素的特征峰;傅

  11. Controlling Sulfate Attack in Mississippi Department of Transportation Structures

    Science.gov (United States)

    2010-08-01

    one of the materials that normally forms during the early setting of portland cement from a reaction between calcium aluminate and gypsum in the...such as calcium aluminates and calcium hydroxide, can influence the degree of damage observed. In all cases, the deterioration observed appears to be...counterions, such as calcium, magnesium , or sodium. Additionally, there are well-documented cases of concrete deterioration due to acid sulfate attack

  12. Sulfate inhibition effect on sulfate reducing bacteria

    Directory of Open Access Journals (Sweden)

    Sulaiman Al Zuhair

    2008-12-01

    Full Text Available There is an increasing interest in the potential of bacterial sulfate reduction as an alternative method for sulfate removal from wastewater. Under anaerobic conditions, sulfate-reducing bacteria (SRB utilize sulfate to oxidize organic compounds and generate sulfide (S2-. SRB were successfully isolated from sludge samples obtained from a local petroleum refinery, and used for sulfate removal. The effects of initial sulfate concentration, temperature and pH on the rate of bacterial growth and anaerobic sulfate removal were investigated and the optimum conditions were identified. The experimental data were used to determine the parameters of two proposed kinetic model, which take into consideration substrate inhibition effect. Keywords: Sulfate Reducing Bacteria, Sulfate, Kinetic Model, Biotreatement, Inhibition Received: 31 August 2008 / Received in revised form: 18 September 2008, Accepted: 18 September 2008 Published online: 28 September 2008

  13. 载万古霉素硫酸钙人工骨结合负压吸引技术治疗金黄色葡萄球菌骨髓炎%Staphylococcus aureus osteomyelitis treated with vancomycin-calcium sulfat and vacuum assisted closure

    Institute of Scientific and Technical Information of China (English)

    付士平; 于晓雯; 高田田; 孙平; 沈姣; 戚晓冬; 蔡韵律

    2011-01-01

    目的 探讨采用载万古霉素硫酸钙结合负压吸引治疗金黄色葡萄球菌骨髓炎的疗效.方法 回顾性分析上海市第八人民医院骨科采用载万古霉素硫酸钙人工骨结合清创负压吸引技术治疗金黄色葡萄球菌骨髓炎的78例患者,血源性骨髓炎患者10例,人工内植物感染患者68例,年龄11~83岁,平均年龄46.9岁.采用一期清创负压吸引想二期含万古霉素硫酸钙人工骨局部植入治疗.结果 随访时间15~40个月,平均25个月,炎症平均愈合时间32.3 d.人工骨平均吸收时间63 d,共6例复发.结论 载万古霉素硫酸钙结合负压吸引治疗金黄色葡萄球菌骨髓炎,可明显提高手术治愈率,改善局部成骨条件,提高患者满意度.%Objective To evaluate the clinical outcomes of osteomyelitis treated with vancomycin-calcium sulfat and vacuuln assisted closllre.Methods Seventy-eight cases of chronic osteomyelitis were treated with vancomycin-calcium sulfate and vacuum assisted closure.Ten Were haematogenous osteomyrelitis and other sixty-eight had infection after interenal fixation of fracture.Results The average age was 46.9 years(range from 11 to 83 years).fracture was unstable.Mcan follow-up Was 25 months(range from 15 to 40 months).The average control of the infection time Was 32.3 days.the mean absorption time of Vancomycin-calcium sulfate granules were 63 days.Conclusion Treatment of chronic osteomyelitis with vancomycin-calcium and vacuum assisted closure is a relatirely simple method.It has a high rate of infection control and ossification improvement.

  14. 碳酸盐沉淀法分离硫酸盐溶液中的锰与钙和镁%Separation of manganese from calcium and magnesium in sulfate solutions via carbonate precipitation

    Institute of Scientific and Technical Information of China (English)

    林清泉; 顾帼华; 王晖; 王重庆; 刘有才; 朱仁锋; 符剑刚

    2016-01-01

    The separation of manganese from sulfate solutions containing 14.59 g/L Mn2+, 1.89 g/L Mg2+ and 1.54 g/L Ca2+ was preformed successfully by carbonate precipitation. The results of thermodynamic analysis and tests indicate that carbonate precipitation holds better selectivity for manganese over magnesium than hydroxide precipitation and the feeding method is the most critical factor for minimizing the co-precipitation of calcium and magnesium. Furthermore, with adding MnSO4 solution to NH4HCO3 solution, the effects of the initial NH4HCO3 concentration, NH4HCO3 amount, solution pH value, reaction temperature and time on carbonate precipitation were evaluated and the optimum precipitation conditions were obtained. Under the optimum conditions, the precipitation rates of Mn2+, Ca2+ and Mg2+ are 99.75%, 5.62% and 1.43%, respectively. Moreover, the prepared manganese carbonate was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX). The results demonstrate that the product can be indexed to the rhombohedral structure of MnCO3.%以含14.59 g/L Mn2+、1.89 g/L Mg2+和1.54 g/L Ca2+的硫酸盐溶液为原料,利用碳酸盐沉淀法实现了锰与钙和镁的有效分离。热力学分析与实验结果表明,碳酸盐沉淀体系中锰对镁的选择性明显优于水解沉淀体系,而且加料方式是减少钙、镁共沉淀的主要因素。因而以硫酸锰加入碳酸氢铵的方式,研究碳酸氢铵初始浓度和用量、溶液 pH 值、反应温度及时间对沉淀过程的影响,并得到最优沉淀条件。结果表明:最优条件下锰、钙和镁离子的沉淀率分别为99.75%、5.62%和1.43%。另外,制得的产品经 X 射线衍射和能谱扫描电镜分析,结果表明该产品为菱形碳酸锰。

  15. Preparation of Zeolite From High Calcium and Solid Sulfate Fly Ash and Its Adsorption of Cu2+%高钙固硫粉煤灰制备分子筛及对Cu2+的吸附

    Institute of Scientific and Technical Information of China (English)

    陈龙; 曹旺均; 宋明光; 王群英

    2016-01-01

    An unnamed zeolite product was successfully prepared by an alkali-fusion & hydrothermal-crystallization method from high calcium and solid sulfate fly ash. The effect of NaOH/fly ash mass ratio on the product was studied,and the products were analyzed by means of XRD, SEM and SEM-EDX. The results show that NaOH/fly ash mass ratio of 1.5 is more appropriate. Adsorption process of Cu2+ from aqueous solution by the prepared product CAZ-1.5 attributes to Lagergren second-order kinetics model under the condition of room temperature, initial Cu2+ mass concentration 200 mg·L-1 and the ratio of zeolite to solution 0.005g·ml-1. The corresponding adsorption constant is 62.50g/ (mg·min). The equilibrium isotherm for Cu2+ uptake corresponds closely to the Langmuir model under the condition of room temperature and the ratio of zeolite to solution 0.005g·ml-1. The maximum adsorption capacity of CAZ-1.5 is up to 107.5mg·g-1.%以高钙固硫粉煤灰为原料,采用碱熔-水热晶化法制备了一种未命名分子筛产品,考察了不同碱灰比对合成产物的影响,并采用了XRD、SEM、SEM-EDX等手段对产物进行了表征分析,实验结果表明1.5为较为合适的碱灰比。在室温条件下、Cu2+离子浓度为200mg·L-1、分子筛样品用量比为0.005g·ml-1时,制备得到的分子筛产品CAZ-1.5对溶液中Cu2+离子的吸附过程符合Lagergren二级速率方程,相应的二级吸附速率常数为62.50g/(mg·min)。在室温条件下、分子筛样品用量比为0.005g·ml-1时,制备得到的分子筛产品对不同浓度Cu2+的等温吸附曲线均符合Langmuir方程,理论饱和吸附容量(Qm)可达107.5 mg·g-1。

  16. [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.

  17. Preliminary Study on a Novel Process for Manufacturing Soda Ash from Sodium Sulfate

    Institute of Scientific and Technical Information of China (English)

    王天贵; 李佐虎

    2004-01-01

    The purpose of this work is to find a new way for utilizing the rich sodium sulfate resource to produce soda ash. A novel process is proposed which uses aqueous dichromate solution as working medium through decomposition of calcium carbonate in aqueous sodium dichromate, complex decomposition of aqueous sodium sulfate and calcium chromate, regeneration of sodium dichromate and production of sodium bicarbonate from carbonation of aqueous sodium chromate solution, processing and utilization of byproduct calcium sulfate, and production of sodium carbonate from sodium bicarbonate. The process has the features of less corrosion and pollution and low energy consumption.

  18. Calcium supplements

    Science.gov (United States)

    ... do not help. Always tell your provider and pharmacist if you are taking extra calcium. Calcium supplements ... 2012:chap 251. The National Osteoporosis Foundation (NOF). Clinician's Guide to prevention and treatment of osteoporosis . National ...

  19. Initial kinetics of the direct sulfation of limestone

    DEFF Research Database (Denmark)

    Hu, Guilin; Shang, Lei; Dam-Johansen, Kim;

    2008-01-01

    The initial kinetics of direct sulfation of Faxe Bryozo, a porous bryozoan limestone was studied in the temperature interval from 873 to 973 K in a pilot entrained flow reactor with very short reaction times (between 0.1 and 0.6 s). The initial conversion rate of the limestone - for conversions...... ions in calcite grains is established. The validity of the model is limited to the initial sulfation period, in which nucleation of the solid product calcium sulphate is not started. This theoretical reaction-diffusion model gives a good simulation of the initial kinetics of the direct sulfation...

  20. Sulfation and Cation Effects on the Conformational Properties of the Glycan Backbone of Chondroitin Sulfate Disaccharides

    Science.gov (United States)

    Faller, Christina E.; Guvench, Olgun

    2015-01-01

    Chondroitin sulfate (CS) is one of several glycosaminoglycans that are major components of proteoglycans. A linear polymer consisting of repeats of the disaccharide -4GlcAβ1-3GalNAcβ1-, CS undergoes differential sulfation resulting in five unique sulfation patterns. Because of the dimer repeat, the CS glycosidic “backbone” has two distinct sets of conformational degrees of freedom defined by pairs of dihedral angles: (ϕ1, ψ1) about the β1-3 glycosidic linkage and (ϕ2, ψ2) about the β1-4 glycosidic linkage. Differential sulfation and the possibility of cation binding, combined with the conformational flexibility and biological diversity of CS, complicate experimental efforts to understand CS three-dimensional structures at atomic resolution. Therefore, all-atom explicit-solvent molecular dynamics simulations with Adaptive Biasing Force sampling of the CS backbone were applied to obtain high resolution, high precision free energies of CS disaccharides as a function of all possible backbone geometries. All ten disaccharides (β1-3 vs. β1-4 linkage x five different sulfation patterns) were studied; additionally, ion effects were investigated by considering each disaccharide in the presence of either neutralizing sodium or calcium cations. GlcAβ1-3GalNAc disaccharides have a single, broad, thermodynamically important free-energy minimum whereas GalNAcβ1-4GlcA disaccharides have two such minima. Calcium cations but not sodium cations bind to the disaccharides, and binding is primarily to the GlcA –COO− moiety as opposed to sulfate groups. This binding alters the glycan backbone thermodynamics in instances where a calcium cation bound to –COO− can act to bridge and stabilize an interaction with an adjacent sulfate group, whereas, in the absence of this cation, the proximity of a sulfate group to –COO− results in two like charges being both desolvated and placed adjacent to each other and is found to be destabilizing. In addition to providing

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

    Directory of Open Access Journals (Sweden)

    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.

  2. Tyrosine Sulfation of Statherin

    Directory of Open Access Journals (Sweden)

    C. Kasinathan, N. Gandhi, P. Ramaprasad, P. Sundaram, N. Ramasubbu

    2007-01-01

    Full Text Available Tyrosylprotein sulfotransferase (TPST, responsible for the sulfation of a variety of secretory and membrane proteins, has been identified and characterized in submandibular salivary glands (William et al. Arch Biochem Biophys 1997; 338: 90-96. In the present study we demonstrate the sulfation of a salivary secretory protein, statherin, by the tyrosylprotein sulfotransferase present in human saliva. Optimum statherin sulfation was observed at pH 6.5 and at 20 mm MnCl2. Increase in the level of total sulfation was observed with increasing statherin concentration. The Km value of tyrosylprotein sulfotransferase for statherin was 40 μM. Analysis of the sulfated statherin product on SDS-polyacrylamide gel electrophoresis followed by autoradiography revealed 35S-labelling of a 5 kDa statherin. Further analysis of the sulfated statherin revealed the sulfation on tyrosyl residue. This study is the first report demonstrating tyrosine sulfation of a salivary secretory protein. The implications of this sulfation of statherin in hydroxyapatite binding and Actinomyces viscosus interactions are discussed.

  3. INVESTIGATION ON PROPERTIES OF CONCRETE CONTAINING NATURAL POZZOLAN VOLCANIC ORIGIN DUE TO SULFATE ATTACK

    OpenAIRE

    MERIDA AHCENE; KHARCHI FATTOUM

    2013-01-01

    Sulfate attack and its effects are important from both scientific and industrial viewpoints. It is perceived that concretes containing pozzolan have better performance in sulfate solutions, since the pozzolanic reactions reduce the quantity of calcium hydroxide and increase calcium silicate hydrate. This paper investigates thecontribution of natural pozzolan volcanic origin on the physico - mechanical and physico-chemical characteristics of the concretes. When it is coupled to a water reducin...

  4. Roles of heparan sulfate sulfation in dentinogenesis.

    Science.gov (United States)

    Hayano, Satoru; Kurosaka, Hiroshi; Yanagita, Takeshi; Kalus, Ina; Milz, Fabian; Ishihara, Yoshihito; Islam, Md Nurul; Kawanabe, Noriaki; Saito, Masahiro; Kamioka, Hiroshi; Adachi, Taiji; Dierks, Thomas; Yamashiro, Takashi

    2012-04-06

    Cell surface heparan sulfate (HS) is an essential regulator of cell signaling and development. HS traps signaling molecules, like Wnt in the glycosaminoglycan side chains of HS proteoglycans (HSPGs), and regulates their functions. Endosulfatases Sulf1 and Sulf2 are secreted at the cell surface to selectively remove 6-O-sulfate groups from HSPGs, thereby modifying the affinity of cell surface HSPGs for its ligands. This study provides molecular evidence for the functional roles of HSPG sulfation and desulfation in dentinogenesis. We show that odontogenic cells are highly sulfated on the cell surface and become desulfated during their differentiation to odontoblasts, which produce tooth dentin. Sulf1/Sulf2 double null mutant mice exhibit a thin dentin matrix and short roots combined with reduced expression of dentin sialophosphoprotein (Dspp) mRNA, encoding a dentin-specific extracellular matrix precursor protein, whereas single Sulf mutants do not show such defective phenotypes. In odontoblast cell lines, Dspp mRNA expression is potentiated by the activation of the Wnt canonical signaling pathway. In addition, pharmacological interference with HS sulfation promotes Dspp mRNA expression through activation of Wnt signaling. On the contrary, the silencing of Sulf suppresses the Wnt signaling pathway and subsequently Dspp mRNA expression. We also show that Wnt10a protein binds to cell surface HSPGs in odontoblasts, and interference with HS sulfation decreases the binding affinity of Wnt10a for HSPGs, which facilitates the binding of Wnt10a to its receptor and potentiates the Wnt signaling pathway, thereby up-regulating Dspp mRNA expression. These results demonstrate that Sulf-mediated desulfation of cellular HSPGs is an important modification that is critical for the activation of the Wnt signaling in odontoblasts and for production of the dentin matrix.

  5. 低分子肝素钙联合硫酸镁与酚妥拉明治疗肺源性心脏病急性加重期的效果%Clinical effect of low molecular heparin calcium combined with magnesium sulfate and phentolamine on acute exacerbation of pulmonary heart disease

    Institute of Scientific and Technical Information of China (English)

    李良玉

    2015-01-01

    Objective To observe the clinical effect of low molecular heparin calcium combined with magnesium sulfate and phentolamine on acute exacerbation of pulmonary heart disease.Methods One hundred and eight pulmonary heart disease patients in acute aggravating period were randomly divided into two groups:the treatment group with 54 cases and the control with 54 cases.The two groups were routinely given anti-infection,oxygen,cough expectorant,spasmolysis and asthma,strong heart,diuresis,correct electrolyte disturbances and so on.In addition,the patients in the treatment group were given low molecular heparin calcium,magnesium sulfate and phentolamine injection,taken 10 d as a course of treatment.The therapeutic effect,the difference of hemorrheology and blood gas analysis indexes before and after treatment between the two groups were observed.Results The total effectiveness of the treatment group was 88.9%,and the total effectiveness of the control group was 70.4%,the curative effect of the treatment group was better than that of the control group (P < 0.05) ; the improvement of blood gas analysis indexes in the treatment group were much better than those in the control group (all P < 0.05).Conclusions There is a good synergistic effect when low molecular heparin calcium combined with magnesium sulfate and phentolamine in the treatment of patients with acute exacerbation of pulmonary heart disease.It can improve the cardiopulmonary function and the prognosis of patients with pulmonary heart disease,and can be popularized in clinical application.%目的 观察低分子肝素钙联合硫酸镁、酚妥拉明治疗肺源性心脏病急性加重期的临床效果.方法 选择商丘市第四人民医院收治的符合入选标准的肺源性心脏病急性加重期患者108例,随机分为治疗组54例和对照组54例,两组患者均常规给予抗感染、吸氧、止咳祛痰、解痉平喘、强心利尿、纠正电解质紊乱等治疗,治疗组在常规治疗

  6. The clinical study on the application of calcium sulfate/Demineralized bone matrix (DBM) granule in the cervical interbody fusion%硫酸钙/脱钙骨基质颗粒在颈椎椎体间融合中的应用

    Institute of Scientific and Technical Information of China (English)

    谢幼专; 张蒲; 富灵杰; 李华; 赵杰

    2011-01-01

    Objective To investigate the clinical outcome of interbody fusion with calcium sulfate/demineralized bone matrix ( DBM ) granule in the cervical spine. Methods 35 patients had undergone anterior cervical discectomy and interbody fusion ( 59 segments )with the polyetheretherketone (PEEK )cages filled with calcium sulfate/DBM granule. There were 19 male and 16 female. The mean age was 53.2 years old (range, 32-65 1 The fusion was agumented with anterior cervical plate. There were 12 cases of cervical spondylotic radiculopathy, 15 cases of cervical spondylotic myelopathy and 8 cases of combined cervical spondylosis. The JOA score, cervical curvature and the fusion status were evaluated after the operation. Results All the patients were followed up consecutively for 24 months. The preoperative JOA score was 7.7± 2.1. At final follow-up, the score was 14.2±2.9 (P < 0.01 I The recovery rate was 69.9%. There was no breakage, looseness or migration of the implants. The fusion rate was 100%. Conclusion It is feasible to achieve the cervical interbody fusion with the PEEK cage filled with calcium sulfate/DBM granule.%目的 观察应用硫酸钙/脱钙骨基质颗粒作为植骨替代材料促进颈椎椎体间融合的效果.方法 对35例患者(59个节段)行颈椎前路间隙减压植骨融合钛板固定术,椎体间植骨采用填充硫酸钙/脱钙骨基质颗粒的聚醚醚酮(PEEK)融合器.其中男19例,女16例,年龄32~65岁,平均53.2±12.5岁.其中神经根型颈椎病12例,脊髓型颈椎病15例,混合型颈椎病8例.术后观察JOA评分、颈椎曲度、椎体间融合情况.结果 35例均获随访,随访时间24个月.JOA评分术前为7.7±2.1,随访终止时为14.2±2.9(P<0.01),恢复率为69.9%.术后无钛板、螺钉断裂或松动,无融合器移位现象发生.所有融合节段均融合.结论 颈椎前路减压融合术中使用填充硫酸钙/脱钙骨基质颗粒的PEEK椎体间融合器能够获得满意的椎体间融合.

  7. Theoretical study on the reactivity of sulfate species with hydrocarbons

    Science.gov (United States)

    Ma, Q.; Ellis, G.S.; Amrani, A.; Zhang, T.; Tang, Y.

    2008-01-01

    used in the laboratory, with most of the dissolved sulfate occurring as SO42 -, aqueous calcium sulfate ([CaSO4](aq)), and aqueous magnesium sulfate ([MgSO4](aq)). Our calculations indicate that TSR reactions that occur in natural environments are most likely to involve bisulfate ions (HSO4-) and/or magnesium sulfate contact ion-pairs ([MgSO4]CIP) rather than 'free' sulfate ions (SO42 -) or solvated sulfate ion-pairs, and that water chemistry likely plays a significant role in controlling the rate of TSR. ?? 2008 Elsevier Ltd. All rights reserved.

  8. Calcium in diet

    Science.gov (United States)

    ... D is needed to help your body use calcium. Milk is fortified with vitamin D for this reason. ... of calcium dietary supplements include calcium citrate and calcium carbonate. Calcium citrate is the more expensive form of ...

  9. Biological sulfate removal from construction and demolition debris leachate: Effect of bioreactor configuration

    Energy Technology Data Exchange (ETDEWEB)

    Kijjanapanich, Pimluck, E-mail: som_cheng00@hotmail.com [Pollution Prevention and Resource Recovery Chair Group, UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX Delft (Netherlands); Do, Anh Tien [Civil and Environmental Engineering, University of South Florida, Tampa, FL 33620 (United States); Annachhatre, Ajit P. [Environmental Engineering and Management, Asian Institute of Technology, PO Box 4, Klongluang, Pathumthani 12120 (Thailand); Esposito, Giovanni [Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via Di Biasio 43, 03043 Cassino (Italy); Yeh, Daniel H. [Civil and Environmental Engineering, University of South Florida, Tampa, FL 33620 (United States); Lens, Piet N.L. [Pollution Prevention and Resource Recovery Chair Group, UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX Delft (Netherlands)

    2014-03-01

    Highlights: • Novel biological technique for gypsum removal from CDD. • CDDS leachate treatment performed using different sulfate reducing bioreactors. • Gypsum in CDD can be used as a source of sulfate for sulfate reducing bacteria. • High calcium concentration (1000 mg L{sup −1}) did not affect the bioreactor performance. - Abstract: Due to the contamination of construction and demolition debris (CDD) by gypsum drywall, especially, its sand fraction (CDD sand, CDDS), the sulfate content in CDDS exceeds the posed limit of the maximum amount of sulfate present in building sand (1.73 g sulfate per kg of sand for the Netherlands). Therefore, the CDDS cannot be reused for construction. The CDDS has to be washed in order to remove most of the impurities and to obtain the right sulfate content, thus generating a leachate, containing high sulfate and calcium concentrations. This study aimed at developing a biological sulfate reduction system for CDDS leachate treatment and compared three different reactor configurations for the sulfate reduction step: the upflow anaerobic sludge blanket (UASB) reactor, inverse fluidized bed (IFB) reactor and gas lift anaerobic membrane bioreactor (GL-AnMBR). This investigation demonstrated that all three systems can be applied for the treatment of CDDS leachate. The highest sulfate removal efficiency of 75–85% was achieved at a hydraulic retention time (HRT) of 15.5 h. A high calcium concentration up to 1000 mg L{sup −1} did not give any adverse effect on the sulfate removal efficiency of the IFB and GL-AnMBR systems.

  10. 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

  11. Formation of ettringite, Ca 6Al 2(SO 4) 3(OH) 12·26H 2O, AFt, and monosulfate, Ca 4Al 2O 6(SO 4)·14H 2O, AFm-14, in hydrothermal hydration of Portland cement and of calcium aluminum oxide—calcium sulfate dihydrate mixtures studied by in situ synchrotron X-ray powder diffraction

    Science.gov (United States)

    Christensen, Axel Nørlund; Jensen, Torben R.; Hanson, Jonathan C.

    2004-06-01

    In the hydration of calcium aluminum oxide-gypsum mixtures, i.e., Ca 3Al 2O 6, Ca 12Al 14O 33 and CaSO 4·2H 2O, the reaction products can be ettringite, Ca 6Al 2(SO 4) 3(OH) 12·26H 2O, monosulfate, Ca 4Al 2O 6(SO 4)·14H 2O, or the calcium aluminum oxide hydrate, Ca 4Al 2O 7·19H 2O. Ettringite is formed if sufficient CaSO 4·2H 2O is present in the mixture. Ettringite is converted to monosulfate when all CaSO 4·2H 2O is consumed in the synthesis of ettringite. The reactions were investigated in the temperature range 25-170°C using in situ synchrotron X-ray powder diffraction. This technique allows the study of very fast chemical reactions that are observed here under hydrothermal conditions. A new experimental approach was developed to perform in situ mixing of the reactants during X-ray data collection.

  12. Calcium and bones

    Science.gov (United States)

    Bone strength and calcium ... calcium (as well as phosphorus) to make healthy bones. Bones are the main storage site of calcium in ... your body does not absorb enough calcium, your bones can get weak or will not grow properly. ...

  13. Direct Sulfation of Limestone

    DEFF Research Database (Denmark)

    Hu, Guilin; Dam-Johansen, Kim; Wedel, Stig

    2007-01-01

    -state diffusion. The nucleation and crystal grain growth of the solid product, and this mixed control mechanism provide satisfactory explanations of the various phenomena related to the direct sulfation of limestone, such as porosity in the product layer, the variation of the apparent reaction orders of SO2, O-2...

  14. Calcium Test

    Science.gov (United States)

    ... if a person has symptoms of a parathyroid disorder , malabsorption , or an overactive thyroid. A total calcium level is often measured as part of a routine health screening. It is included in the comprehensive metabolic panel (CMP) and the basic metabolic panel (BMP) , ...

  15. Calcium Carbonate

    Science.gov (United States)

    ... doctor if you have or have ever had kidney disease or stomach conditions.tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking calcium carbonate, call your doctor.

  16. Production development and utilization of Zimmer Station wet FGD by-products. Final report. Volume 4, A laboratory study conducted in fulfillment of Phase 2, Objective 1 titled. Inhibition of acid production in coal refuse amended with calcium sulfite and calcium sulfate - containing FGD solids

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Y. L. [Ohio State Univ., Wooster, OH (United States); Dick, W. A. [Ohio State Univ., Wooster, OH (United States); Stehouwer, R. C. [Ohio State Univ., Wooster, OH (United States); Bigham, J. M. [Ohio State Univ., Wooster, OH (United States)

    1998-06-30

    Control of S02 emission from coal combustion requires desulfurization of coal before its combustion to produce coal refuse. Alternatively, gaseous emissions from coal combustion may be scrubbed to yield flue gas desulfurization (FGD) by-products that include calcium sulfite (CaSO3∙0.5H2O or simply CaS03). Acid production in coal refuse due to pyrite oxidation and disposal of large amounts of FGD can cause environmental degradation. Addition of CaS03 and CaS03-containing FGD to coal refuse may reduce the amounts of oxygen and ferric ion available to oxidize pyrite because the sulfite moiety in CaS03 is a strong reductant and thus may mitigate acid production in coal refuse. In Chapter 1, it was shown that CaS03 efficiently scavenged dissolved oxygen and ferric ion in water under the conditions commonly encountered in a coal refuse disposal environment. In the presence ofCaS03, the concentration of dissolved oxygen in water exposed to the atmosphere declined to below 0.01 mg L"1 at pH <8.0. In Chapter 2, it was demonstrated that CaS03 prevented a pH drop in coal refuse slurry when 0.2 gCaS03 was added to a 2% fresh coal refuse slurry every three days. Calcium sulfite also inhibited acid leaching from fresh coal refuse in bench-scale columns under controlled conditions. During the initial 13 weeks of leaching, the total amounts of titratable acidity, soluble H\\ Fe, and Al from CaS03-treated refuse (6.4 gin 50 g fresh coal refuse) were only 26%,10%, 32%, and 39% of those of the control columns, respectively. A combination of CaS03 with CaC03 or fly ash enhanced the inhibitory effect of CaS03 on acid leaching. Calcium sulfite-containing FGD which combined CaS03, CaC03, fly ash, and gypsum showed a much stronger inhibitory effect on acid leaching than CaS03 alone. This

  17. Preliminary Study on a Novel Process for Manufacturing Soda Ash from Sodium Sulfate%一种新的芒硝制碱法实验室研究

    Institute of Scientific and Technical Information of China (English)

    王天贵; 李佐虎

    2004-01-01

    The purpose of this work is to find a new way for utilizing the rich sodium sulfate resource to produce soda ash.A novel process is proposed which uses aqueous dichromate solution as working medium through decomposition of calcium carbonate in aqueous sodium dichromate,complex decomposition of aqueous sodium sulfate and calcium chromate,regeneration of sodium dichromate and production of sodium bicarbonate from carbonation of aqueous sodium chromate solution,processing and utilization of byproduct calcium sulfate,and production of sodium carbonate from sodium bicarbonate.The process has the features of less corrosion and pollution and low energy consumption.

  18. Heparan sulfate biosynthesis

    DEFF Research Database (Denmark)

    Multhaupt, Hinke A B; Couchman, John R

    2012-01-01

    that the synthesis of heparan sulfate is tightly controlled. Although genomics has identified the enzymes involved in glycosaminoglycan synthesis in a number of vertebrates and invertebrates, the regulation of the process is not understood. Moreover, the localization of the various enzymes in the Golgi apparatus has...... not been carried out in a detailed way using high-resolution microscopy. We have begun this process, using well-known markers for the various Golgi compartments, coupled with the use of characterized antibodies and cDNA expression. Laser scanning confocal microscopy coupled with line scanning provides high......-quality resolution of the distribution of enzymes. The EXT2 protein, which when combined as heterodimers with EXT1 comprises the major polymerase in heparan sulfate synthesis, has been studied in depth. All the data are consistent with a cis-Golgi distribution and provide a starting point to establish whether all...

  19. Controlling barium sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Greenley, R.

    Even though for several years success has been realized in controlling barium sulfate scale deposition in relatively shallow, low pressure oil wells--by squeezing an organic phosphonate scale inhibitor into the producing zone--barium sulfate scale depositon in deep, high pressure/high temperature wells usually meant an expensive workover operation. A case history of a deep (16,000 ft) well in St. Mary Parish, Louisiana, and the scale inhibitor squeeze operation are described. Based on the successful results obtained in treating this well, a generalized treating procedure for combating downhole scale deposition in high pressure/high temperature gas wells is presented. Formation squeezing with such an inhibitor represents a significant breakthrough for the oil and gas industry.

  20. The effect of divalent salt in chondroitin sulfate solutions

    Science.gov (United States)

    Aranghel, D.; Badita, C. R.; Radulescu, A.; Moldovan, L.; Craciunescu, O.; Balasoiu, M.

    2016-03-01

    Chondroitin-4 sulfate (CS4) is the main glycosaminoglycan extracted from bovine trachea. CS4 play an important role in osteoarthritis treatment, anticoagulant activity, reduces the degradation of cartilage matrix components, reduces necrosis and apoptosis of chondrocytes and reduces the activity of collagenase. Chondroitin sulfate is also responsible for proteoglycans degradation. Chondroitin sulfate can bind calcium ions with different affinities, depending on their sulfation position. The purpose of this study was to determine the structural properties and the influence of Ca2+ cations. We carried out measurements on CS4 solutions and mixtures of liquid CS4 with Ca2+ by Small-Angle Neutron Scattering (SANS). CS4 have a mass fractal behavior and the addition of a salt (CaCl2) in CS4 solutions generates the appearance of a correlation peak due to local ordering between adjacent chains with inter-chain distances between 483 Å and 233 Å for a calcium concentration of 0.01% w/w.

  1. Sulfation of chondroitin. Specificity, degree of sulfation, and detergent effects with 4-sulfating and 6-sulfating microsomal systems

    Energy Technology Data Exchange (ETDEWEB)

    Sugumaran, G.; Silbert, J.E.

    1988-04-05

    Microsomal preparations from chondroitin 6-sulfate-producing chick embryo epiphyseal cartilage, and from chondroitin 4-sulfate-producing mouse mastocytoma cells, were incubated with UDP-(14C)glucuronic acid and UDP-N-acetylgalactosamine to form non-sulfated proteo(14C)chondroitin. Aliquots of the incubations were then incubated with 3'-phosphoadenylylphosphosulfate (PAPS) in the presence or absence of various detergents. In the absence of detergents, there was good sulfation of this endogenous proteo(14C)chondroitin by the original microsomes from both sources. Detergents, with the exception of Triton X-100, markedly inhibited sulfation in the mast cell system but not in the chick cartilage system. These results indicate that sulfation and polymerization are closely linked on cell membranes and that in some cases this organization can be disrupted by detergents. When aliquots of the original incubation were heat inactivated, and then reincubated with new microsomes from chick cartilage and/or mouse mastocytoma cells plus PAPS, there was no significant sulfation of this exogenous proteo(14C) chondroitin with either system unless Triton X-100 was added. Sulfation of exogenous chondroitin and chondroitin hexasaccharide was compared with sulfation of endogenous and exogenous proteo(14C)chondroitin. Sulfate incorporation into hexasaccharide and chondroitin decreased as their concentrations (based on uronic acid) approached that of the proteo(14C)chondroitin. At the same time, the degree of sulfation in percent of substituted hexosamine increased. However, the degree of sulfation did not reach that of the endogenous proteo(14C)chondroitin. Hexasaccharide and chondroitin sulfation were stimulated by the presence of Triton X-100. However, in contrast to the exogenous proteo(14C)chondroitin, there was some sulfation of hexasaccharide and chondroitin in the absence of this detergent.

  2. Off limits: sulfate below the sulfate-methane transition

    Science.gov (United States)

    Brunner, Benjamin; Arnold, Gail; Røy, Hans; Müller, Inigo; Jørgensen, Bo

    2016-07-01

    One of the most intriguing recent discoveries in biogeochemistry is the ubiquity of cryptic sulfur cycling. From subglacial lakes to marine oxygen minimum zones, and in marine sediments, cryptic sulfur cycling - the simultaneous sulfate consumption and production - has been observed. Though this process does not leave an imprint in the sulfur budget of the ambient environment - thus the term cryptic - it may have a massive impact on other element cycles and fundamentally change our understanding of biogeochemical processes in the subsurface. Classically, the sulfate-methane transition (SMT) in marine sediments is considered to be the boundary that delimits sulfate reduction from methanogenesis as the predominant terminal pathway of organic matter mineralization. Two sediment cores from Aarhus Bay, Denmark reveal the constant presence of sulfate (generally 0.1 to 0.2 mM) below the SMT. The sulfur and oxygen isotope signature of this deep sulfate (34S = 18.9‰, 18O = 7.7‰) was close to the isotope signature of bottom-seawater collected from the sampling site (34S = 19.8‰, 18O = 7.3‰). In one of the cores, oxygen isotope values of sulfate at the transition from the base of the SMT to the deep sulfate pool (18O = 4.5‰ to 6.8‰) were distinctly lighter than the deep sulfate pool. Our findings are consistent with a scenario where sulfate enriched in 34S and 18O is removed at the base of the SMT and replaced with isotopically light sulfate below. Here, we explore scenarios that explain this observation, ranging from sampling artifacts, such as contamination with seawater or auto-oxidation of sulfide - to the potential of sulfate generation in a section of the sediment column where sulfate is expected to be absent which enables reductive sulfur cycling, creating the conditions under which sulfate respiration can persist in the methanic zone.

  3. 注射型可吸收聚氨基酸/硫酸钙复合材料动物体内降解吸收及促成骨作用%In vivo degradation, absorption and osteogenesis of injectable and absorbable polyamine acid/calcium sulfate composites

    Institute of Scientific and Technical Information of China (English)

    姜勇; 张帅; 周勇; 闵理; 易敏; 段宏; 屠重棋; 严永刚

    2012-01-01

    背景:注射型人工骨可经皮穿刺注射植入体内,对机体创伤较小,同时该型材料可以任意塑形,能较好地充填骨缺损,但目前临床上尚无在体内能完全降解吸收且具有较好促成骨作用的注射型人工骨产品.目的:评估注射型可吸收聚氨基酸/硫酸钙复合材料(硫酸钙含量70%)动物体内的降解吸收及促成骨作用,观察其修复骨缺损的能力.方法:取48只新西兰大白兔,在股骨外髁处制备直径为5 mm、深10 mm的骨缺损模型,以随机数字表法分为实验组和对照组,实验组将注射型可吸收聚氨基酸/硫酸钙复合材料植入骨缺损处,对照组未予干预.结果与结论:X射线平片示:实验组骨缺损逐渐被骨痂填充,术后16周,骨缺损处恢复正常松质骨密度,塑形完成;对照组骨缺损处修复不明显.组织学检查(苏木精-伊红、MASSON染色)示:术后4周,材料开始降解,新生原始骨小梁长入材料内;术后12周,编织骨开始转化为板层骨;术后16周,材料完全被降解吸收,新生骨组织完全修复骨缺损.结果显示注射型聚氨基酸/硫酸钙复合材料在动物内能够完全降解、吸收,具备一定的成骨活性,可望用作骨修复材料.%BACKGROUND: With fewer traumas to the body, injectable artificial bone can be implanted into the body through the percutaneous injection. Meanwhile, the material can be any shape to fill bone defects. But now in clinic, there is no injectable artificial bone substitute product with the better ability of bone formation, which can be completely degraded and absorbed in vivo. OBJECTIVE: To evaluate the degradation, absorption and osteogenesis in vivo ability of injectable and absorbable polyamine acid/calcium sulfate (PAA/CS) composites (containing 70% calcium sulfate), and to observe the ability to repair bone defects. METHODS: A 5 mm×10 mm size bone defect model was made on the femoral condyle of 48 New Zealand white rabbits, which were

  4. Effect of magnesium sulfate combined with calcium channel blockers on cystatin C,uric acid, alpha fetal protein and urinary transferrin levels in patients with hypertension pregnancy%硫酸镁联合钙离子通道拮抗剂对妊娠期高血压患者血清胱抑素C、尿酸、甲胎蛋白及尿转铁蛋白水平的影响

    Institute of Scientific and Technical Information of China (English)

    蔡安利; 宋飞銮; 秦洁; 戴洁; 潘倩若; 吕杰强

    2015-01-01

    目的:探讨硫酸镁联合钙离子通道拮抗剂对妊娠期高血压患者血清胱抑素C( cystatin C)、尿酸、甲胎蛋白( alpha fetal protein,AFP)及尿转铁蛋白( transferrin,TRF)水平的影响及意义。方法选取温州医科大学附属第三医院2013年1月~2014年10月产科收治的75例妊娠期高血压患者,随机分为2组,对照组37例行临床常规治疗;实验组38例,在对照组基础上加用硫酸镁和钙离子通道拮抗剂治疗。检测2组患者血清胱抑素C、尿酸、甲胎蛋白及尿转铁蛋白水平变化,比较2组临床疗效。结果与对照组比较,实验组Cys C、尿酸水平较低(P<0.05),血清AFP水平、尿TRF水平较低(P<0.05),血清血细胞比容、血液粘度及红细胞聚集指数较低(P<0.05),总有效率明显高于对照组(P<0.05)。结论硫酸镁联合钙离子通道拮抗剂对妊娠期高血压疾病患者治疗有较好的临床疗效,能有效改善血液粘度,降低血清Cys C、尿酸、AFP和尿TRF水平。%Objective To explore the effect of magnesium sulfate combined with calcium channel blockers on cystatin C, uric acid, alpha fetal protein and urinary transferrin in patients with hypertension pregnancy.Methods 75 cases with hypertension of pregnancy were selected and divided into two groups, control group(n=37) were treated with conventional therapy, experiment group(n=38) were treated with magnesium sulfate combined with calcium channel blockers on the basis of control group.Cystatin C, uric acid, alpha fetal protein and urinary transferrin were compared after treatment between two groups.Results Compared with control group, Cys C, uric acid, serum AFP l, urinary TRF levels were all lower in experiment group( P<0.05), serum hematocrit, whole blood viscosity and erythrocyte aggregation index were all lower in experiment group(P<0.05).The total efficiency of experiment group was significantly higher than

  5. Effect of fly ash on the optimum sulfate of Portland Cement

    Science.gov (United States)

    Niemuth, Mark D.

    Calcium sulfate is typically added to ordinary portland cement (OPC) clinker during grinding to prevent flash set and to improve early-age strength development without causing volume instabilities. Recent changes to ASTM C150, Standard Specification for Portland Cement, have enabled greater flexibility in determining optimum sulfate levels in portland cement by not requiring ASTM C563, Approximation of Optimum SO3 in Hydraulic Cement Using Compressive Strength, to be used in setting sulfate target levels. ASTM C563 requires strength testing using only the hydraulic cement, which is not always indicative of the optimum sulfate for field use, since supplementary materials (e.g., fly ash) may be used by the concrete producer. Adding additional sulfate to account for the sulfate demand of fly ashes can enable an improvement in the early age strength for cement-fly ash systems and decrease in problems that may be attributed to OPC-admixture-fly ash incompatibility such as abnormal setting and slow strength gain. This thesis provides experimental data on the strength development and heat release during early hydration for cement-fly ash systems with different sulfate levels. The thesis focused on high calcium fly ashes, but low calcium fly ash was also tested. It is demonstrated that some fly ashes have their own sulfate demand and when these ashes are used in cement-fly ash blends there is effectively an increase in the optimal sulfate level that could be used for the OPC. It is also shown that optimum sulfate determined by heat of hydration measured with isothermal calorimetry is similar to the optimum sulfate determined by compressive strength at 1 day. Using isothermal calorimetry can result in substantial time and cost savings at plants for determining the optimal sulfate content. Theories for the mechanisms that drive the differences in sulfate demand in OPC are reviewed. These theories are adapted for OPC-fly ash blends and are outlined, tested and discussed. The

  6. Interaction of PACls with sulfate

    Institute of Scientific and Technical Information of China (English)

    XU Yi; WANG Dong-Sheng; TANG Hong-Xiao

    2004-01-01

    This article discusses the influential factors on Al13 separation considering the interaction of sulfate with various polyaluminum chloride(PACl). The experimental results showed that the basicity(B=[OH]/[Al]), the concentration of PACl and Al/SO4 ratio exhibited significant roles in the PACl-sulfate reaction. It indicated that different species in various PACl underwent different reaction pathway with sulfate. The Alc, colloidal species, formed precipitation quickly with sulfate, while Alb, oligomers and polymers, undergoes slow crystallization. And Ala, monomers, reacts with sulfate to form soluble complexes. The kinetic difference of reaction made it possible to realize the separation of Alb and further purification. The decrease of Ala resulted in the limit of ferron method was also mentioned.

  7. SULFATE RESISTANCE MECHANISM OF HIGH-PERFORMANCE CONCRETE CONTAINING NCI

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    It is found that the incorporation of Nitrite Corrosion Inhibitor (NCI) greatly weakens the resistance of mixtures to sulfate attack.To study the mechanism of this phenomenon,in this paper,the influence of NCI additionon on the cement paste and microstructure change of high performance concrete specimens is studied by means of quantitative XRD,SEM tests.The results demonstrate that the incorporation of NCI accelerates the formation of calcium hydroxide and ettringite crystals,and weakens the pore refinement effect caused by the secondary hydration reaction of fly ash and microsilica.At the age up to one year,the relative crystal quantity in mixture containing NCI is always higher than that in control mixture.The reasons for the degradation in sulfate resisitance of mixtures may be attributed to the increase and stability of the calcium hydroxide and ettringite crystals formed and the weakening of secondary hydration reaction.Based on the results,conclusion can be drawn that NCI should be used cautiously in practical engineering where high resistance to sulfate attack is required.

  8. BILE SECRETION OF SULFATED GLYCOLITHOCHOLIC ACID IS REQUIRED FOR ITS CHOLESTATIC ACTION IN RATS

    NARCIS (Netherlands)

    KUIPERS, F; HARDONK, MJ; VONK, RJ; VANDERMEER, R

    1992-01-01

    To test our hypothesis that the cholestatic action of sulfated glycolithocholic acid (SGLC) in the rat is related to its interaction with calcium in the biliary tree [R. van der Meer, R. J. Vonk, and F. Kuipers. Am. J. Physiol. 254 (Gastrointest. Liver Physiol. 17): G644-G649, 1988], we have now com

  9. Calcium and Vitamin D

    Science.gov (United States)

    ... Cart Home › Patients › Treatment › Calcium/Vitamin D Calcium/Vitamin D Getting enough calcium and vitamin D is ... the-counter medications and calcium supplements. What is Vitamin D and What Does it Do? Vitamin D ...

  10. Imaging calcium in neurons.

    Science.gov (United States)

    Grienberger, Christine; Konnerth, Arthur

    2012-03-08

    Calcium ions generate versatile intracellular signals that control key functions in all types of neurons. Imaging calcium in neurons is particularly important because calcium signals exert their highly specific functions in well-defined cellular subcompartments. In this Primer, we briefly review the general mechanisms of neuronal calcium signaling. We then introduce the calcium imaging devices, including confocal and two-photon microscopy as well as miniaturized devices that are used in freely moving animals. We provide an overview of the classical chemical fluorescent calcium indicators and of the protein-based genetically encoded calcium indicators. Using application examples, we introduce new developments in the field, such as calcium imaging in awake, behaving animals and the use of calcium imaging for mapping single spine sensory inputs in cortical neurons in vivo. We conclude by providing an outlook on the prospects of calcium imaging for the analysis of neuronal signaling and plasticity in various animal models.

  11. Sulfated polysaccharides from marine sponges (Porifera): an ancestor cell-cell adhesion event based on the carbohydrate-carbohydrate interaction.

    Science.gov (United States)

    Vilanova, Eduardo; Coutinho, Cristiano C; Mourão, Paulo A S

    2009-08-01

    Marine sponges (Porifera) are ancient and simple eumetazoans. They constitute key organisms in the evolution from unicellular to multicellular animals. We now demonstrated that pure sulfated polysaccharides from marine sponges are responsible for the species-specific cell-cell interaction in these invertebrates. This conclusion was based on the following observations: (1) each species of marine sponge has a single population of sulfated polysaccharide, which differ among the species in their sugar composition and sulfate content; (2) sulfated polysaccharides from sponge interact with each other in a species-specific way, as indicated by an affinity chromatography assay, and this interaction requires calcium; (3) homologous, but not heterologous, sulfated polysaccharide inhibits aggregation of dissociated sponge cells; (4) we also observed a parallel between synthesis of the sulfated polysaccharide and formation of large aggregates of sponge cells, known as primmorphs. Once aggregation reached a plateau, the demand for the de novo synthesis of sulfated polysaccharides ceased. Heparin can mimic the homologous sulfated polysaccharide on the in vitro interaction and also as an inhibitor of aggregation of the dissociated sponge cells. However, this observation is not relevant for the biology of the sponge since heparin is not found in the invertebrate. In conclusion, marine sponges display an ancestor event of cell-cell adhesion, based on the calcium-dependent carbohydrate-carbohydrate interaction.

  12. Sulfate transport in toad skin

    DEFF Research Database (Denmark)

    Larsen, Erik Hviid; Simonsen, K

    1988-01-01

    1. In short-circuited toad skin preparations exposed bilaterally to NaCl-Ringer's containing 1 mM SO2(-4), influx of sulfate was larger than efflux showing that the skin is capable of transporting sulfate actively in an inward direction. 2. This active transport was not abolished by substituting...... apical Na+ for K+. 3. Following voltage activation of the passive Cl- permeability of the mitochondria-rich (m.r.) cells sulfate flux-ratio increased to a value predicted from the Ussing flux-ratio equation for a monovalent anion. 4. In such skins, which were shown to exhibit vanishingly small leakage...

  13. p-Cresyl Sulfate

    Directory of Open Access Journals (Sweden)

    Tessa Gryp

    2017-01-01

    Full Text Available If chronic kidney disease (CKD is associated with an impairment of kidney function, several uremic solutes are retained. Some of these exert toxic effects, which are called uremic toxins. p-Cresyl sulfate (pCS is a prototype protein-bound uremic toxin to which many biological and biochemical (toxic effects have been attributed. In addition, increased levels of pCS have been associated with worsening outcomes in CKD patients. pCS finds its origin in the intestine where gut bacteria metabolize aromatic amino acids, such as tyrosine and phenylalanine, leading to phenolic end products, of which pCS is one of the components. In this review we summarize the biological effects of pCS and its metabolic origin in the intestine. It appears that, according to in vitro studies, the intestinal bacteria generating phenolic compounds mainly belong to the families Bacteroidaceae, Bifidobacteriaceae, Clostridiaceae, Enterobacteriaceae, Enterococcaceae, Eubacteriaceae, Fusobacteriaceae, Lachnospiraceae, Lactobacillaceae, Porphyromonadaceae, Staphylococcaceae, Ruminococcaceae, and Veillonellaceae. Since pCS remains difficult to remove by dialysis, the gut microbiota could be a future target to decrease pCS levels and its toxicity, even at earlier stages of CKD, aiming at slowing down the progression of the disease and decreasing the cardiovascular burden.

  14. p-Cresyl Sulfate

    Science.gov (United States)

    Gryp, Tessa; Vanholder, Raymond; Vaneechoutte, Mario; Glorieux, Griet

    2017-01-01

    If chronic kidney disease (CKD) is associated with an impairment of kidney function, several uremic solutes are retained. Some of these exert toxic effects, which are called uremic toxins. p-Cresyl sulfate (pCS) is a prototype protein-bound uremic toxin to which many biological and biochemical (toxic) effects have been attributed. In addition, increased levels of pCS have been associated with worsening outcomes in CKD patients. pCS finds its origin in the intestine where gut bacteria metabolize aromatic amino acids, such as tyrosine and phenylalanine, leading to phenolic end products, of which pCS is one of the components. In this review we summarize the biological effects of pCS and its metabolic origin in the intestine. It appears that, according to in vitro studies, the intestinal bacteria generating phenolic compounds mainly belong to the families Bacteroidaceae, Bifidobacteriaceae, Clostridiaceae, Enterobacteriaceae, Enterococcaceae, Eubacteriaceae, Fusobacteriaceae, Lachnospiraceae, Lactobacillaceae, Porphyromonadaceae, Staphylococcaceae, Ruminococcaceae, and Veillonellaceae. Since pCS remains difficult to remove by dialysis, the gut microbiota could be a future target to decrease pCS levels and its toxicity, even at earlier stages of CKD, aiming at slowing down the progression of the disease and decreasing the cardiovascular burden. PMID:28146081

  15. Development and Demonstration of a Sulfate Precipitation Process for Hanford Waste Tank 241-AN-107

    Energy Technology Data Exchange (ETDEWEB)

    SK Fiskum; DE Kurath; BM Rapko

    2000-08-16

    A series of precipitation experiments were conducted on Hanford waste tank 241-AN-107 samples in an effort to remove sulfate from the matrix. Calcium nitrate was added directly to AN-107 sub-samples to yield several combinations of Ca:CO{sub 3} mole ratios spanning a range of 0:1 to 3:1 to remove carbonate as insoluble CaCO{sub 3}. Similarly barium nitrate was added directly to the AN-107 aliquots, or to the calcium pretreated AN-107 aliquots, giving of Ba:SO{sub 4} mole ratios spanning a range of 1:1 to 5:1 to precipitate sulfate as BaSO{sub 4}. Initial bulk carbonate removal was required for successful follow-on barium sulfate precipitation. A {ge} 1:1 mole ratio of Ca:CO{sub 3} was found to lower the carbonate concentration such that Ba would react preferentially with the sulfate. A follow-on 1:1 mole ratio of Ba:SO{sub 4} resulted in 70% sulfate removal. The experiment was scaled up with a 735-mL aliquot of AN-107 for more complete testing. Calcium carbonate and barium sulfate settling rates were determined and fates of selected cations, anions, and radionuclides were followed through the various process steps. Seventy percent of the sulfate was removed in the scale-up test while recovering 63% of the filtrate volume. Surprisingly, during the scale-up test a sub-sample of the CaCO{sub 3}/241-AN-107 slurry was found to lose fluidity upon standing for {le} 2 days. Metathesis with BaCO{sub 3} at ambient temperature was also evaluated using batch contacts at various BaCO{sub 3}:SO{sub 4} mole ratios with no measurable success.

  16. Microstructural Origins of Cement Paste Degradation by External Sulfate Attack

    Science.gov (United States)

    Feng, Pan; Garboczi, Edward J.; Miao, Changwen; Bullard, Jeffrey W.

    2015-01-01

    A microstructure model has been applied to simulate near-surface degradation of portland cement paste in contact with a sodium sulfate solution. This new model uses thermodynamic equilibrium calculations to guide both compositional and microstructure changes. It predicts localized deformation and the onset of damage by coupling the confined growth of new solids with linear thermoelastic finite element calculations of stress and strain fields. Constrained ettringite growth happens primarily at the expense of calcium monosulfoaluminate, carboaluminate and aluminum-rich hydrotalcite, if any, respectively. Expansion and damage can be mitigated chemically by increasing carbonate and magnesium concentrations or microstructurally by inducing a finer dispersion of monosulfate. PMID:26722191

  17. 21 CFR 558.364 - Neomycin sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Neomycin sulfate. 558.364 Section 558.364 Food and... in Animal Feeds § 558.364 Neomycin sulfate. (a) Approvals. Type A medicated article: 325 grams per.... (c) (d) Conditions of use. Neomycin sulfate is used as follows: Neomycin Sulfate...

  18. 21 CFR 184.1307 - Ferric sulfate.

    Science.gov (United States)

    2010-04-01

    ... Substances Affirmed as GRAS § 184.1307 Ferric sulfate. (a) Ferric sulfate (iron (III) sulfate, Fe2(SO4)3 CAS Reg. No. 10028-22-5) is a yellow substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide or ferric hydroxide with sulfuric acid. (b) The ingredient must be of a...

  19. 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.

  20. Clinical significance of application of calcium sulfate prevention of oral anticoagulation in patients with alveolar hemorrhage after tooth extraction%应用硫酸钙预防口服抗凝药患者拔牙后牙槽内出血的临床研究

    Institute of Scientific and Technical Information of China (English)

    马小红

    2015-01-01

    目的:评估采用口服抗凝药物治疗的患者拔牙后使用半水合硫酸钙作为止血剂的止血疗效。方法选取2013年6月至2014年8月收治的拔牙同时行抗凝治疗的患者75例(95颗牙),根据随机抽样方法将患者分成实验组38例和对照组37例。对照组采用牙槽闭塞性缝合止血处理,实验组采用半水合硫酸钙填塞牙槽窝止血处理。在整个治疗过程中,两组患者均维持口服抗凝药。观察两组术前患者患牙情况,统计拔牙原因及数量;观察两组拔牙后创口愈合情况,术中及术后出血情况,术后并发症等。结果两组患者拔牙数量及手术所需时间之间比较差异无统计学意义( P >0.05);拔牙术后在连续的时间点观察,两组患者牙槽出血情况均得到控制,但实验组止血能力和创口愈合情况明显高于对照组,两组比较差异有统计学意义( P <0.05)。实验组术后并发症发生率低于对照组,两组比较差异有统计学意义( P <0.05)。结论应用半水合硫酸钙填塞控制拔牙后牙槽出血,止血效果高效、充分,患者术后愈合情况好,并发症少。%Objective To evaluate the use of calcium sulfate as a hemostatic agent after tooth extraction in patients with anticoagulant drug therapy. Methods 75 patients undergoing anticoagulant therapy,needing dental extractions,were selected in our department of stomatology dur-ing June 2013 to August 2014 for this study. The patients were divided into control group(n = 37)and experimental group(n = 38)in a random-ized way. The postextraction socket of the control group were managed with obliterative suture,while the postextraction sockets were packed with CaS. During the whole treatment process,all of the patients received maintained treatment of oral anticoagulants. The teeth surgery patient,the number of reasons for tooth extraction,wound healing after tooth extraction were observed. The

  1. Clinical analysis of the treatment of thoracolumbar fracture by calcium sulfate liquid artificial bone strengthening the fractured vertebral%经伤椎硫酸钙液态人工骨强化治疗胸腰椎骨折的临床分析

    Institute of Scientific and Technical Information of China (English)

    黄勇; 徐峰; 蔡贤华; 胡昊; 魏坦军; 王威

    2013-01-01

    目的 比较短节段跨伤椎固定联合经伤椎注入液态人工骨强化和单纯短节段跨伤椎固定治疗胸腰椎骨折的临床疗效.方法 回顾性分析2009年1月至2011年6月我院收治的95例胸腰椎骨折的临床资料,其中A组(40例)采用短节段跨伤椎固定结合可注射液态人工骨(硫酸钙骨水泥)伤椎椎体成形,B组(55例)采用短节段跨伤椎固定治疗胸腰椎爆裂性骨折.所有患者术后随访至少12个月.对两组患者的术前、术后及末次随访的Cobb角,伤椎前缘高度比值,椎管侵占率和VAS疼痛评分进行分析比较.结果 两组术后伤椎后凸Cobb角、椎管侵占率、伤椎前缘压缩率及VAS评分较术前均明显改善,A组与B组相比较无统计学差异(P>0.05),两组术后长期随访伤椎后凸Cobb角、伤椎前缘压缩率、VAS评分,B组较A组疗效好,结果有显著性差异(P<0.05).结论 经伤椎液态人工骨强化治疗胸腰椎骨折具有更加牢固的固定效果,前中柱重建稳定,后柱固定牢固,矫正度丢失少,疗效满意,是治疗单一节段胸腰椎爆裂性骨折的有效方法.%Objective Investigate the clinical effect by comparing the short segments across the injured vertebra fixation with the fractured vertebral liquid artificial bone injection strengthening with the simple short segments across the injured vertebra fixed ofthoracolumbar fractures.Methods A retrospective analysis of the clinical data of 95 patients with thoracolumbar fractures our hospital from January 2009 to June 2011,including group B (55 patients) with short segment cross-fractured vertebral fixation and group A (40 patients) using short-segment cross hurt vertebral fixation combined injectable liquid cement (calcium sulfate bone cement) vertebral body shaping treatment ofthoracolumbar burst fractures.All patients were followed up for at least 12 months.The injured vertebra leading edge height ratio,spinal the encroachment rate and VAS pain scores

  2. 新型α-半水硫酸钙/双相生物陶瓷人工骨修复兔桡骨骨缺损的X射线评估%X-ray evaluation of alpha-calcium sulfate hemiydrate/biphasic bioceramics bone for repairing bone defects of rabbit radius

    Institute of Scientific and Technical Information of China (English)

    姚彪; 钱卫庆; 尹宏

    2014-01-01

    背景:α-半水硫酸钙和双相生物陶瓷作为骨修复材料已在临床广泛应用,但都存在一定的缺点。目的:观察α-半水硫酸钙/双相生物陶瓷人工骨用于修复兔桡骨缺损的效果。方法:建立18只成年新西兰大白兔任一单侧桡骨缺损模型,随机分为3组,分别于骨缺损处植入α-半水硫酸钙材料、α-半水硫酸钙/双相生物陶瓷材料与双相生物陶瓷材料,植入后第4,8,12周时取材,对3组进行大体观察及X射线观察。结果与结论:①大体观察:植入第12周,α-半水硫酸钙/双相生物陶瓷组骨缺损空腔完全修复,桡骨形状基本恢复到术前形态;α-半水硫酸钙组明显缺损凹陷,双相生物陶瓷组仍可见少量材料填充覆盖。②X 射线观察:α-半水硫酸钙组材料吸收过快,材料降解快于新骨生成,可见骨缺损;α-半水硫酸钙/双相生物陶瓷组骨缺损已愈合,皮质骨塑形良好,骨髓腔完全再通;双相生物陶瓷组仍可见材料影,受未降解材料影响骨缺损未能修复。表明新型α-半水硫酸钙/双相生物陶瓷骨修复材料能明显促进兔桡骨骨缺损的修复,修复效果优于与单独α-半水硫酸钙材料及双相生物陶瓷材料。%BACKGROUND:Alpha-calcium sulfate hemiydrate/biphasic bioceramics (α-CSH/BCP) as a bone repair material has been widely used in the clinic, but there are stil some deficiencies. OBJECTIVE:To observe the effect of α-CSH/BCP on the repair of bone defects of the radius in rabbits. METHODS:The unilateral radius of 18 adult New Zealand white rabbits was selected to establish bone defect models, and then these rabbit models were randomized into three groups that were treated with α-CSH,α-CSH/BCP, BCP materials, respectively. At 4, 8, 12 weeks after implantation, bone samples were taken for gross and X-ray observations. RESULTS AND CONCLUSION: (1) Gross observation: At 12 weeks of implantation

  3. Calcium - Function and effects

    NARCIS (Netherlands)

    Liang, Jianfen; He, Yifan; Gao, Qian; Wang, Xuan; Nout, M.J.R.

    2016-01-01

    Rice is the primary food source for more than half of the world population. Levels of calcium contents and inhibitor - phytic acid are summarized in this chapter. Phytic acid has a very strong chelating ability and it is the main inhibit factor for calcium in rice products. Calcium contents in br

  4. Calcium spirulan, an inhibitor of enveloped virus replication, from a blue-green alga Spirulina platensis.

    Science.gov (United States)

    Hayashi, T; Hayashi, K; Maeda, M; Kojima, I

    1996-01-01

    Bioactivity-directed fractionation of a hot H2O extract from a blue-green alga Spirulina platensis led to the isolation of a novel sulfated polysaccharide named calcium spirulan (Ca-SP) as an antiviral principle. This polysaccharide was composed of rhamnose, ribose, mannose, fructose, galactose, xylose, glucose, glucuronic acid, galacturonic acid, sulfate, and calcium. Ca-SP was found to inhibit the replication of several enveloped viruses, including Herpes simplex virus type 1, human cytomegalovirus, measles virus, mumps virus, influenza A virus, and HIV-1. It was revealed that Ca-SP selectively inhibited the penetration of virus into host cells. Retention of molecular conformation by chelation of calcium ion with sulfate groups was suggested to be indispensable to its antiviral effect.

  5. Mineral carbonation of phosphogypsum waste for production of useful carbonate and sulfate salts

    Directory of Open Access Journals (Sweden)

    Hannu-Petteri eMattila

    2015-11-01

    Full Text Available Phosphogypsum (CaSO4·2H2O waste is produced in large amounts during phosphoric acid (H3PO4 production. Minor quantities are utilized in construction or agriculture, while most of the material is stockpiled, creating an environmental challenge to prevent pollution of natural waters. In principle, the gypsum waste could be used to capture several hundred Mt of carbon dioxide (CO2. For example, when gypsum is converted to ammonium sulfate ((NH42SO4 with ammonia (NH3 and CO2, also solid calcium carbonate (CaCO3 is generated. The ammonium sulfate can be utilized as a fertilizer or in other mineral carbonation processes that use magnesium silicate-based rock as feedstock, while calcium carbonate has various uses as e.g. filler material. The reaction extent of the described process was studied by thermodynamic modeling and experimentally as a function of reactant concentrations and temperature. Other essential properties such as purity and quality of the solid products are also followed. Conversion efficiencies of >95% calcium from phosphogypsum to calcium carbonate are obtained. Scalenohedral, rhombohedral and prismatic calcite particles can be produced, though the precipitates contain certain contaminants such as rare earth metals and sulfur from the gypsum. A reverse osmosis membrane cartridge is also tested as an alternative and energy-efficient method of concentrating the ammonium sulfate salt solution instead of the traditional evaporation of the process solution.

  6. Heparan sulfate structure: methods to study N-sulfation and NDST action.

    Science.gov (United States)

    Dagälv, Anders; Lundequist, Anders; Filipek-Górniok, Beata; Dierker, Tabea; Eriksson, Inger; Kjellén, Lena

    2015-01-01

    Heparan sulfate proteoglycans are important modulators of cellular processes where the negatively charged polysaccharide chains interact with target proteins. The sulfation pattern of the heparan sulfate chains will determine the proteins that will bind and the affinity of the interactions. The N-deacetylase/N-sulfotransferase (NDST) enzymes are of key importance during heparan sulfate biosynthesis when the sulfation pattern is determined. In this chapter, metabolic labeling of heparan sulfate with [(35)S]sulfate or [(3)H]glucosamine in cell cultures is described, in addition to characterization of polysaccharide chain length and degree of N-sulfation. Methods to measure NDST enzyme activity are also presented.

  7. Effect of fly ash composition on the sulfate resistance of concrete[Includes the CSCE forum on professional practice and career development : 1. international engineering mechanics and materials specialty conference : 1. international/3. coastal, estuarine and offshore engineering specialty conference : 2. international/8. construction specialty conference

    Energy Technology Data Exchange (ETDEWEB)

    Dhole, R.D.; Thomas, M.D.A. [New Brunswick Univ., Fredericton, NB (Canada); Folliard, K.J.; Drimalas, T. [Texas Univ., Austin, TX (United States)

    2009-07-01

    Studies have shown that low-calcium Class F fly ashes obtained from burning coal in power stations can increase the sulfate resistance of Portland cement concrete. In many cases the sulfate resistance of concrete containing high-calcium Class C fly ash can be reduced compared to concrete without fly ash, due to the presence of crystalline C3A in the fly ash and calcium aluminate in the glass. This study investigated the differences in the glass composition and sulfate resistance of fly ashes with a range of calcium contents. The objective was to determine whether the behaviour of high-calcium fly ashes could be improved by blending with low-calcium fly ash. The sulfate resistance of cementitious systems consisting of a Type I Portland cement blended with Class F and Class C fly ashes of varying composition was evaluated by monitoring the length change of mortar bars stored in 5 per cent sodium sulfate solution. Scanning electron microscopy and electron dispersive X-ray analysis were used to characterize the glass phases of the fly ashes. The position occupied by the glass when plotted on a CaO-SiO{sub 2}-Al{sub 2}O{sub 3} ternary was identified as belonging to one of the fields occupied by the mineral phases mullite, anorthosite or gehlenite. The glass showed a transition from alumino-silicate in Class F fly ash to a calcium alumino-silicate or mixed calcium-aluminate/alumino-silicate in Class C fly ashes with higher calcium contents. Fly ashes with high amounts of calcium-aluminate glass had reduced sulfate resistance when tested in mortars. Blends of Class C and Class F fly ashes had better sulfate resistance than mixes made with only Class C fly ash. A relationship was established between the calcium oxide content of the blended fly ash and sulfate resistance of mortar. 8 refs., 5 tabs., 10 figs.

  8. Sulfate reduction in freshwater peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Oequist, M.

    1996-12-31

    This text consist of two parts: Part A is a literature review on microbial sulfate reduction with emphasis on freshwater peatlands, and part B presents the results from a study of the relative importance of sulfate reduction and methane formation for the anaerobic decomposition in a boreal peatland. The relative importance of sulfate reduction and methane production for the anaerobic decomposition was studied in a small raised bog situated in the boreal zone of southern Sweden. Depth distribution of sulfate reduction- and methane production rates were measured in peat sampled from three sites (A, B, and C) forming an minerotrophic-ombrotrophic gradient. SO{sub 4}{sup 2-} concentrations in the three profiles were of equal magnitude and ranged from 50 to 150 {mu}M. In contrast, rates of sulfate reduction were vastly different: Maximum rates in the three profiles were obtained at a depth of ca. 20 cm below the water table. In A it was 8 {mu}M h{sup -1} while in B and C they were 1 and 0.05 {mu}M h{sup -1}, respectively. Methane production rates, however, were more uniform across the three nutrient regimes. Maximum rates in A (ca. 1.5 {mu}g d{sup -1} g{sup -1}) were found 10 cm below the water table, in B (ca. 1.0 {mu}g d{sup -1} g{sup -1}) in the vicinity of the water table, and in C (0.75 {mu}g d{sup -1} g{sup -1}) 20 cm below the water table. In all profiles both sulfate reduction and methane production rates were negligible above the water table. The areal estimates of methane production for the profiles were 22.4, 9.0 and 6.4 mmol m{sup -2} d{sup -1}, while the estimates for sulfate reduction were 26.4, 2.5, and 0.1 mmol m{sup -2} d{sup -1}, respectively. The calculated turnover times at the sites were 1.2, 14.2, and 198.7 days, respectively. The study shows that sulfate reducing bacteria are important for the anaerobic degradation in the studied peatland, especially in the minerotrophic sites, while methanogenic bacteria dominate in ombrotrophic sites Examination

  9. Calcium signaling and epilepsy.

    Science.gov (United States)

    Steinlein, Ortrud K

    2014-08-01

    Calcium signaling is involved in a multitude of physiological and pathophysiological mechanisms. Over the last decade, it has been increasingly recognized as an important factor in epileptogenesis, and it is becoming obvious that the excess synchronization of neurons that is characteristic for seizures can be linked to various calcium signaling pathways. These include immediate effects on membrane excitability by calcium influx through ion channels as well as delayed mechanisms that act through G-protein coupled pathways. Calcium signaling is able to cause hyperexcitability either by direct modulation of neuronal activity or indirectly through calcium-dependent gliotransmission. Furthermore, feedback mechanisms between mitochondrial calcium signaling and reactive oxygen species are able to cause neuronal cell death and seizures. Unravelling the complexity of calcium signaling in epileptogenesis is a daunting task, but it includes the promise to uncover formerly unknown targets for the development of new antiepileptic drugs.

  10. Studies on Sulfation of Lycium barbarum Polysaccharides

    Institute of Scientific and Technical Information of China (English)

    YI,Jian-Ping; YAN,Hong; ZHONG,Ru-Gang

    2004-01-01

    @@ Polysaccharides can anti-virus, such as human immunodeficiency virus (HIV-1),[1] herpes simplex virus (HSV-1,HSV-2) and cytomegalovirus. Some of them are sulfates, e.g. dextran sulfate, heparin, sulfonation of chitosan and sulfated derivatives of Lentinan. Our results showed that sulfated derivatives of Lycium barbarum polysaccharides (LBP)have anti-HIV activity. Because the anti-HIV activity of LBP was deeply dependent on the molecular weight, the sulfation pattern and glycosidic branches besides degree of sulfation (DS), so we emphasized our work on the factors of DS.

  11. Durability of Alite-calcium Barium Sulphoaluminate Cement

    Institute of Scientific and Technical Information of China (English)

    LU Lingchao; LU Zeye; LIU Shiquan; WANG Shoude; CHENG Xin

    2009-01-01

    The durability of the cement was mainly studied.Under 1.0 MPa of hydraulic pressure for 8 hours,water could penetrate completely through the sample made by portland cement,but could not penetrate through that by alite-barium sulphoaluminate cement.Under the condition of freezing and thawing cycle,the loss ratio of compressive strength of the cement was only about 17.3%at curing 28 d ages,but the loss of portland cement was as high as 29.5%.Alite-calcium bar-ium sulphoaluminate cement also has an excellent resistance to sulfate attack.The coefficients of resistance to sulfate attack of the cement exceeded 1.0.Meanwhile,the composition and microstructure of the hardened paste of alite-calcium barium sulphoaluminate cement were analyzed by XRD and SEM.

  12. A sulfate conundrum: Dissolved sulfates of deep-saline brines and carbonate-associated sulfates

    Science.gov (United States)

    Labotka, Dana M.; Panno, Samuel V.; Locke, Randall A.

    2016-10-01

    Sulfates in deeply circulating brines and carbonate-associated sulfates (CAS) within sedimentary units of the Cambrian strata in the Illinois Basin record a complex history. Dissolved sulfate within the Mt. Simon Sandstone brines exhibits average δ34SSO4 values of 35.4‰ and δ18OSO4 values of 14.6‰ and appears to be related to Cambrian seawater sulfate, either original seawater or sourced from evaporite deposits such as those in the Michigan Basin. Theoretical and empirical relationships based on stable oxygen isotope fractionation suggest that sulfate within the lower depths of the Mt. Simon brines has experienced a long period of isolation, possibly several tens of millions of years. Comparison with brines from other stratigraphic units shows the Mt. Simon brines are geochemically unique. Dissolved sulfate from brines within the Ironton-Galesville Sandstone averages 22.7‰ for δ34SSO4 values and 13.0‰ for δ18OSO4 values. The Ironton-Galesville brine has mixed with younger groundwater, possibly of Ordovician to Devonian age and younger. The Eau Claire Formation lies between the Mt. Simon and Ironton-Galesville Sandstones. The carbonate units of the Eau Claire and stratigraphically equivalent Bonneterre Formation contain CAS that appears isotopically related to the Late Pennsylvanian-Early Permian Mississippi Valley-type ore pulses that deposited large sulfide minerals in the Viburnum Trend/Old Lead Belt ore districts. The δ34SCAS values range from 21.3‰ to 9.3‰, and δ18OCAS values range from +1.4‰ to -2.6‰ and show a strong covariance (R2 = 0.94). The largely wholesale replacement of Cambrian seawater sulfate signatures in these dolomites does not appear to have affected the sulfate signatures in the Mt. Simon brines even though these sulfide deposits are found in the stratigraphically equivalent Lamotte Sandstone to the southwest. On the basis of this and previous studies, greater fluid densities of the Mt. Simon brines may have prevented the

  13. Thermochemical sulfate reduction in deep petroleum reservoirs: a molecular approach; Thermoreduction des sulfates dans les reservoirs petroliers: approche moleculaire

    Energy Technology Data Exchange (ETDEWEB)

    Hanin, S.

    2002-11-01

    The thermochemical sulfate reduction (TSR) is a set of chemical reactions leading to hydrocarbon oxidation and production of carbon dioxide and sour gas (H{sub 2}S) which is observed in deep petroleum reservoirs enriched in anhydrites (calcium sulfate). Molecular and isotopic studies have been conducted on several crude oil samples to determine which types of compounds could have been produced during TSR. Actually, we have shown that the main molecules formed by TSR were organo-sulfur compounds. Indeed, sulfur isotopic measurements. of alkyl-di-benzothiophenes, di-aryl-disulfides and thia-diamondoids (identified by NMR or synthesis of standards) shows that they are formed during TSR as their value approach that of the sulfur of the anhydrite. Moreover, thia-diamondoids are apparently exclusively formed during this phenomenon and can thus be considered as true molecular markers of TSR. In a second part, we have investigated with laboratory experiments the formation mechanism of the molecules produced during TSR. A first model has shown that sulfur incorporation into the organic matter occurred with mineral sulfur species of low oxidation degree. The use of {sup 34}S allowed to show that the sulfates reduction occurred during these simulations. At least, some experiments on polycyclic hydrocarbons, sulfurized or not, allowed to establish that thia-diamondoids could be formed by acid-catalysed rearrangements at high temperatures in a similar way as the diamondoids. (author)

  14. Sulfation of thyroid hormone by estrogen sulfotransferase

    NARCIS (Netherlands)

    M.H.A. Kester (Monique); T.J. Visser (Theo); C.H. van Dijk (Caren); D. Tibboel (Dick); A.M. Hood (Margaret); N.J. Rose; W. Meinl; U. Pabel; H. Glatt; C.N. Falany; M.W. Coughtrie

    1999-01-01

    textabstractSulfation is one of the pathways by which thyroid hormone is inactivated. Iodothyronine sulfate concentrations are very high in human fetal blood and amniotic fluid, suggesting important production of these conjugates in utero. Human estrogen sulfotransferas

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

    OpenAIRE

    Ustinova Yulia Valer’evna

    2013-01-01

    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 select...

  16. 21 CFR 524.1484e - Neomycin sulfate and polymyxin B sulfate ophthalmic solution.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Neomycin sulfate and polymyxin B sulfate ophthalmic solution. 524.1484e Section 524.1484e Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... DOSAGE FORM NEW ANIMAL DRUGS § 524.1484e Neomycin sulfate and polymyxin B sulfate ophthalmic solution....

  17. 21 CFR 582.1643 - Potassium sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium sulfate. 582.1643 Section 582.1643 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1643 Potassium sulfate. (a) Product. Potassium sulfate. (b) Conditions of use....

  18. 21 CFR 184.1643 - Potassium sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium sulfate. 184.1643 Section 184.1643 Food... Specific Substances Affirmed as GRAS § 184.1643 Potassium sulfate. (a) Potassium sulfate (K2SO4, CAS Reg... having a bitter, saline taste. It is prepared by the neutralization of sulfuric acid with...

  19. 21 CFR 582.5443 - Magnesium sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium sulfate. 582.5443 Section 582.5443 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5443 Magnesium sulfate. (a) Product. Magnesium sulfate. (b) Conditions of use....

  20. 21 CFR 184.1443 - Magnesium sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium sulfate. 184.1443 Section 184.1443 Food... Specific Substances Affirmed as GRAS § 184.1443 Magnesium sulfate. (a) Magnesium sulfate (MgSO4·7H2O, CAS... magnesium oxide, hydroxide, or carbonate with sulfuric acid and evaporating the solution to...

  1. Sulfate transport in Penicillium chrysogenum plasma membranes.

    OpenAIRE

    Hillenga, Dirk J.; Versantvoort, Hanneke J.M.; Driessen, Arnold J. M.; Konings, Wil N.

    1996-01-01

    Transport studies with Penicillium chrysogenum plasma membranes fused with cytochrome c oxidase liposomes demonstrate that sulfate uptake is driven by the transmembrane pH gradient and not by the transmembrane electrical potential. Ca2+ and other divalent cations are not required. It is concluded that the sulfate transport system catalyzes the symport of two protons with one sulfate anion.

  2. INVESTIGATION ON PROPERTIES OF CONCRETE CONTAINING NATURAL POZZOLAN VOLCANIC ORIGIN DUE TO SULFATE ATTACK

    Directory of Open Access Journals (Sweden)

    MERIDA AHCENE

    2013-05-01

    Full Text Available Sulfate attack and its effects are important from both scientific and industrial viewpoints. It is perceived that concretes containing pozzolan have better performance in sulfate solutions, since the pozzolanic reactions reduce the quantity of calcium hydroxide and increase calcium silicate hydrate. This paper investigates thecontribution of natural pozzolan volcanic origin on the physico - mechanical and physico-chemical characteristics of the concretes. When it is coupled to a water reducing superplasticizer by a correct adjustment of the composition, it greatly improves the concrete properties. The analysis of the experimental results on pozzolan concrete at 5% content and sharpness of 9600cm2/g, in a sulphated environment, showed that it contributes positively to the improvement of its mechanical characteristics and its durability with respect towater absorption, and to the permeability to the chlorine ions as well as to the resistance to the sulphates.

  3. Calcium is important forus.

    Institute of Scientific and Technical Information of China (English)

    高利平

    2005-01-01

    Calcium is important for our health.We must have it in our diet to stay well.A good place to get it is from dairy products like milk, cheese and ice cream.One pound of cheese has fifty times the calcium we should have every day.Other foods have less.For example,a pound of beans also has calcium.But it has only three times the amount we ought to have daily.

  4. Tris(ethylenediaminecobalt(II sulfate

    Directory of Open Access Journals (Sweden)

    Bunlawee Yotnoi

    2010-06-01

    Full Text Available The structure of the title compound, [CoII(C2H8N23]SO4, the cobalt example of [M(C2H8N23]SO4, is reported. The Co and S atoms are located at the 2d and 2c Wyckoff sites (point symmetry 32, respectively. The Co atom is coordinated by six N atoms of three chelating ethylenediamine molecules generated from half of the ethylenediamine molecule in the asymmetric unit. The O atoms of the sulfate anion are disordered mostly over two crystallographic sites. The third disorder site of O (site symmetry 3 has a site occupancy approaching zero. The H atoms of the ethylenediamine molecules interact with the sulfate anions via intermolecular N—H...O hydrogen-bonding interactions.

  5. Sulfates on Mars: Indicators of Aqueous Processes

    Science.gov (United States)

    Bishop, Janice L.; Lane, Melissa D.; Dyar, M. Darby; Brown, Adrian J.

    2006-01-01

    Recent analyses by MER instruments at Meridiani Planum and Gusev crater and the OMEGA instrument on Mars Express have provided detailed information about the presence of sulfates on Mars [1,2,3]. We are evaluating these recent data in an integrated multi-disciplinary study of visible-near-infrared, mid-IR and Mossbauer spectra of several sulfate minerals and sulfate-rich analog sites. Our analyses suggest that hydrated iron sulfates may account for features observed in Mossbauer and mid-IR spectra of Martian soils [4]. The sulfate minerals kieserite, gypsum and other hydrated sulfates have been identified in OMEGA spectra in the layered terrains in Valles Marineris and Terra Meridiani [2]. These recent discoveries emphasize the importance of studying sulfate minerals as tracers of aqueous processes. The sulfate-rich rock outcrops observed in Meridiani Planum may have formed in an acidic environment similar to acid rock drainage environments on Earth [5]. Because microorganisms typically are involved in the oxidation of sulfides to sulfates in terrestrial sites, sulfate-rich rock outcrops on Mars may be a good location to search for evidence of past life on that planet. Whether or not life evolved on Mars, following the trail of sulfate minerals will lead to a better understanding of aqueous processes and chemical weathering.

  6. Chondroitin Sulfate Perlecan Enhances Collagen Fibril Formation

    DEFF Research Database (Denmark)

    Kvist, A. J.; Johnson, A. E.; Mörgelin, M.

    2006-01-01

    produced in the presence of perlecan. Interestingly, the enhancement of collagen fibril formation is independent on the core protein and is mimicked by chondroitin sulfate E but neither by chondroitin sulfate D nor dextran sulfate. Furthermore, perlecan chondroitin sulfate contains the 4,6-disulfated......Inactivation of the perlecan gene leads to perinatal lethal chondrodysplasia. The similarity to the phenotypes of the Col2A1 knock-out and the disproportionate micromelia mutation suggests perlecan involvement in cartilage collagen matrix assembly. We now present a mechanism for the defect...... in collagen type II fibril assembly by perlecan-null chondrocytes. Cartilage perlecan is a heparin sulfate or a mixed heparan sulfate/chondroitin sulfate proteoglycan. The latter form binds collagen and accelerates fibril formation in vitro, with more defined fibril morphology and increased fibril diameters...

  7. 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...

  8. Sulfation and biological activities of konjac glucomannan.

    Science.gov (United States)

    Bo, Surina; Muschin, Tegshi; Kanamoto, Taisei; Nakashima, Hideki; Yoshida, Takashi

    2013-05-15

    The sulfation of konjac glucomannan and its anti-HIV and blood anticoagulant activities were investigated. Konjac glucomannan is a polysaccharide occurring naturally in konjac plant tubers and has high molecular weights. Solubility in water is very low, and the aqueous solutions at low concentrations have high viscosity. Before sulfation, hydrolysis by diluted sulfuric acid was carried out to decrease the molecular weights of M¯n=19.2 × 10(4)-0.2 × 10(4). Sulfation with piperidine-N-sulfonic acid or SO3-pyridine complex gave sulfated konjac glucomannans with molecular weights of M¯n=1.0 × 10(4)-0.4 × 10(4) and degrees of sulfation (DS) of 1.3-1.4. It was found that the sulfated konjac glucomannans had potent anti-HIV activity at a 50% effective concentration, (EC50) of 1.2-1.3 μg/ml, which was almost as high as that of an AIDS drug, ddC, whose EC50=3.2 μg/ml, and moderate blood anticoagulant activity, AA=0.8-22.7 units/mg, compared to those of standard sulfated polysaccharides, curdlan (10 units/mg) and dextran (22.7 units/mg) sulfates. Structural analysis of sulfated konjac glucomannans with negatively charged sulfated groups was performed by high resolution NMR, and the interaction between poly-l-lysine with positively charged amino groups as a model compound of proteins and peptides was measured by surface plasmon resonance measurement, suggesting that the sulfated konjac glucomannans had a high binding stability on immobilized poly-l-lysine. The binding of sulfated konjac glucomannan was concentration-dependent, and the biological activity of the sulfated konjac glucomannans may be due to electrostatic interaction between the sulfate and amino groups.

  9. Calcium signaling in neurodegeneration

    Directory of Open Access Journals (Sweden)

    Dreses-Werringloer Ute

    2009-05-01

    Full Text Available Abstract Calcium is a key signaling ion involved in many different intracellular and extracellular processes ranging from synaptic activity to cell-cell communication and adhesion. The exact definition at the molecular level of the versatility of this ion has made overwhelming progress in the past several years and has been extensively reviewed. In the brain, calcium is fundamental in the control of synaptic activity and memory formation, a process that leads to the activation of specific calcium-dependent signal transduction pathways and implicates key protein effectors, such as CaMKs, MAPK/ERKs, and CREB. Properly controlled homeostasis of calcium signaling not only supports normal brain physiology but also maintains neuronal integrity and long-term cell survival. Emerging knowledge indicates that calcium homeostasis is not only critical for cell physiology and health, but also, when deregulated, can lead to neurodegeneration via complex and diverse mechanisms involved in selective neuronal impairments and death. The identification of several modulators of calcium homeostasis, such as presenilins and CALHM1, as potential factors involved in the pathogenesis of Alzheimer's disease, provides strong support for a role of calcium in neurodegeneration. These observations represent an important step towards understanding the molecular mechanisms of calcium signaling disturbances observed in different brain diseases such as Alzheimer's, Parkinson's, and Huntington's diseases.

  10. Calcium does not inhibit the absorption of 5 milligrams of nonheme or heme iron at doses less than 800 milligrams in nonpregnant women.

    Science.gov (United States)

    Gaitán, Diego; Flores, Sebastián; Saavedra, Pía; Miranda, Constanza; Olivares, Manuel; Arredondo, Miguel; López de Romaña, Daniel; Lönnerdal, Bo; Pizarro, Fernando

    2011-09-01

    Calcium is the only known component in the diet that may affect absorption of both nonheme and heme iron. However, the evidence for a calcium effect on iron absorption mainly comes from studies that did not isolate the effect of calcium from that of other dietary components, because it was detected in single-meal studies. Our objective was to establish potential effects of calcium on absorption of nonheme and heme iron and the dose response for this effect in the absence of a meal. Fifty-four healthy, nonpregnant women were selected to participate in 4 iron absorption studies using iron radioactive tracers. We evaluated the effects of calcium doses between 200 and 1500 mg on absorption of 5 mg nonheme iron (as ferrous sulfate). We also evaluated the effects of calcium doses between 200 and 800 mg on absorption of 5 mg heme iron [as concentrated RBC (CRBC)]. Calcium was administered as calcium chloride in all studies and minerals were ingested on an empty stomach. Calcium doses ≥1000 mg diminished nonheme iron absorption by an average of 49.6%. A calcium dose of 800 mg diminished absorption of 5 mg heme iron by 37.7%. In conclusion, we demonstrated an isolated effect of calcium (as chloride) on absorption of 5 mg of iron provided as nonheme (as sulfate) and heme (as CRBC) iron. This effect was observed at doses higher than previously reported from single-meal studies, starting at ~800 mg of calcium.

  11. Manufacture of ammonium sulfate fertilizer from gypsum-rich byproduct of flue gas desulfurization - A prefeasibility cost estimate

    Science.gov (United States)

    Chou, I.-Ming; Rostam-Abadi, M.; Lytle, J.M.; Achorn, F.P.

    1996-01-01

    Costs for constructing and operating a conceptual plant based on a proposed process that converts flue gas desulfurization (FGD)-gypsum to ammonium sulfate fertilizer has been calculated and used to estimate a market price for the product. The average market price of granular ammonium sulfate ($138/ton) exceeds the rough estimated cost of ammonium sulfate from the proposed process ($111/ ton), by 25 percent, if granular size ammonium sulfate crystals of 1.2 to 3.3 millimeters in diameters can be produced by the proposed process. However, there was at least ??30% margin in the cost estimate calculations. The additional costs for compaction, if needed to create granules of the required size, would make the process uneconomical unless considerable efficiency gains are achieved to balance the additional costs. This study suggests the need both to refine the crystallization process and to find potential markets for the calcium carbonate produced by the process.

  12. Releasing effects in flame photometry: Determination of calcium

    Science.gov (United States)

    Dinnin, J.I.

    1960-01-01

    Strontium, lanthanum, neodymium, samarium, and yttrium completely release the flame emission of calcium from the depressive effects of sulfate, phosphate, and aluminate. Magnesium, beryllium, barium, and scandium release most of the calcium emission. These cations, when present in high concentration, preferentially form compounds with the depressing anions when the solution is evaporated rapidly in the flame. The mechanism of the interference and releasing effects is explained on the basis of the chemical equilibria in the evaporating droplets of solution and is shown to depend upon the nature of the compounds present in the aqueous phase of the solution. The need for background correction techniques is stressed. The releasing effect is used in the determination of calcium in silicate rocks without the need for separations.

  13. Hydration of Portland cement with additions of calcium sulfoaluminates

    Energy Technology Data Exchange (ETDEWEB)

    Le Saout, Gwenn, E-mail: gwenn.le-saout@mines-ales.fr [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Lothenbach, Barbara [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Hori, Akihiro [DENKA Chemicals GmbH, Wehrhahn-Center, Cantadorstr. 3, D-40211 Duesseldorf (Germany); Higuchi, Takayuki [Denki Kagaku Kogyo Kabushiki Kaisha (DENKA), Omi, Itoigawa, Niigata, 949-0393 (Japan); Winnefeld, Frank [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)

    2013-01-15

    The effect of mineral additions based on calcium aluminates on the hydration mechanism of ordinary Portland cement (OPC) was investigated using isothermal calorimetry, thermal analysis, X-ray diffraction, scanning electron microscopy, solid state nuclear magnetic resonance and pore solution analysis. Results show that the addition of a calcium sulfoaluminate cement (CSA) to the OPC does not affect the hydration mechanism of alite but controls the aluminate dissolution. In the second blend investigated, a rapid setting cement, the amorphous calcium aluminate reacts very fast to ettringite. The release of aluminum ions strongly retards the hydration of alite but the C-S-H has a similar composition as in OPC with no additional Al to Si substitution. As in CSA-OPC, the aluminate hydration is controlled by the availability of sulfates. The coupling of thermodynamic modeling with the kinetic equations predicts the amount of hydrates and pore solution compositions as a function of time and validates the model in these systems.

  14. ROLE OF POROSITY LOSS IN LIMITING SO2 CAPTURE BY CALCIUM BASED SORBENTS

    Science.gov (United States)

    The extent of high temperature (900-1,300°C), short time (capture was found to be limited by temperature-dependent losses in the porosity of calcium based sorbents. At 970°C these porosity losses were caused by CO2-activated sintering. Sulfation of the sorbents either p...

  15. Inhibition of synthesis of heparan sulfate by selenate: Possible dependence on sulfation for chain polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, C.P.; Nader, H.B. (Paulist School of Medicine, Sao Paulo (Brazil)); Buonassisi, V.; Colburn, P. (W. Alton Jones Cell Science Center, Lake Placid, NY (USA))

    1988-01-01

    Selenate, a sulfation inhibitor, blocks the synthesis of heparan sulfate and chondroitin sulfate by cultured endothelial cells. In contrast, selenate does not affect the production of hyaluronic acid, a nonsulfated glycosaminoglycan. No differences in molecular weight, ({sup 3}H)glucosamine/({sup 35}S)sulfuric acid ratios, or disaccharide composition were observed when the heparan sulfate synthesized by selenate-treated cells was compared with that of control cells. The absence of undersulfated chains in preparations from cultures exposed to selenate supports the concept that, in the intact cell, the polymerization of heparan sulfate might be dependent on the sulfation of the saccharide units added to the growing glycosaminoglycan chain.

  16. The influence of temperature on limestone sulfation and attrition under fluidized bed combustion conditions

    Energy Technology Data Exchange (ETDEWEB)

    Montagnaro, Fabio [Dipartimento di Chimica - Universita degli Studi di Napoli Federico II, Complesso Universitario del Monte di Sant' Angelo, 80126 Napoli (Italy); Salatino, Piero [Istituto di Ricerche sulla Combustione - CNR, Piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy); Dipartimento di Ingegneria Chimica - Universita degli Studi di Napoli Federico II, Piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy); Scala, Fabrizio [Istituto di Ricerche sulla Combustione - CNR, Piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy)

    2010-04-15

    The influence of temperature on attrition of two limestones during desulfurization in a fluidized bed reactor was investigated. Differences in the microstructure of the two limestones were reflected by a different thickness of the sulfate shell formed upon sulfation and by a different value of the ultimate calcium conversion degree. Particle attrition and fragmentation were fairly small under moderately bubbling fluidization conditions for both limestones. An increase of temperature from 850 C to 900 C led to an increase of the attrition rate, most likely because of a particle weakening effect caused by a faster CO{sub 2} evolution during calcination. This weakening effect, however, was not sufficiently strong to enhance particle fragmentation in the bed. The progress of sulfation, associated to the build-up of a hard sulfate shell around the particles, led in any case to a decrease of the extent of attrition. Sulfation at 900 C was less effective than at 850 C, and this was shown to be related to the porosimetric features of the different samples. (author)

  17. Evaluating Deterioration of Concrete by Sulfate Attack

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Effects of factors such as water to cement ratio, fly ash and silica fume on the resistance of concrete to sulfate attack were investigated by dry-wet cycles and immersion method. The index of the resistance to sulfate attack was used to evaluate the deterioration degree of concrete damaged by sulfate. The relationship between the resistance of concrete to sulfate attack and its permeability/porosity were analyzed as well as its responding mechanism. Results show that the depth of sulfate crystal attack from surface to inner of concrete can be reduced by decreasing w/c and addition of combining fly ash with silica fume. The variation of relative elastic modulus ratio and relative flexural strength ratio of various specimens before and after being subjected to sulfate attack was compared.

  18. Depolymerization of sulfated polysaccharides under hydrothermal conditions.

    Science.gov (United States)

    Morimoto, Minoru; Takatori, Masaki; Hayashi, Tetsuya; Mori, Daiki; Takashima, Osamu; Yoshida, Shinichi; Sato, Kimihiko; Kawamoto, Hitoshi; Tamura, Jun-ichi; Izawa, Hironori; Ifuku, Shinsuke; Saimoto, Hiroyuki

    2014-01-30

    Fucoidan and chondroitin sulfate, which are well known sulfated polysaccharides, were depolymerized under hydrothermal conditions (120-180°C, 5-60min) as a method for the preparation of sulfated polysaccharides with controlled molecular weights. Fucoidan was easily depolymerized, and the change of the molecular weight values depended on the reaction temperature and time. The degree of sulfation and IR spectra of the depolymerized fucoidan did not change compared with those of untreated fucoidan at reaction temperatures below 140°C. However, fucoidan was partially degraded during depolymerization above 160°C. Nearly the same depolymerization was observed for chondroitin sulfate. These results indicate that hydrothermal treatment is applicable for the depolymerization of sulfated polysaccharides, and that low molecular weight products without desulfation and deformation of the initial glycan structures can be obtained under mild hydrothermal conditions.

  19. Adsorption of Potassium and Calcium Ions by Variable Charge Soils

    Institute of Scientific and Technical Information of China (English)

    LIHONG-YAN; JIGUO-LIANG

    1992-01-01

    Interactions of potassium and calcium ions with four typical variable charge soils in South China were examined by measuring pK-0.5pCa value with a potassium ion-selective electrode and a calcium ion-selective electrode,and pK value with a potassium ion-selective electrode.The results showed that adsorption of potassium and calcium ions increased with soil suspension pH,and the tendency of the pK-0.5pCa value changing with pH differed with respect to pH range and potassium to calcium ratio.Adsorption of equal amount of calcium and potassium ions led to release of an identical number of protons,suggesting similar adsorption characteristics of these two ions when adsorbed by variable charge soils.Compared with red soil,latosol and lateritic red soil had higher adsorption selectivities for calcium ion.The red soil had a greater affinity for potassium ion than that for calcium ion at low concentration,which seems to result from its possession of 2:1 type minerals,such as vermiculite and mica with a high affinity for potassium ion.The results indicated that adsorption of potassium and calcium ions by the variable charge soils was chiefly caused by the electrostatic attraction between the cations and the soil surfaces.Moreover,it was found that sulfate could affect the adsorption by changing soil surface properties and by forming ion-pair.

  20. Calcium and Your Child

    Science.gov (United States)

    ... for dinner. Create mini-pizzas by topping whole-wheat English muffins or bagels with pizza sauce, low- ... Minerals Do I Need to Drink Milk? Lactose Intolerance Becoming a Vegetarian Soy Foods and Health Calcium ...

  1. 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.

  2. Sulfate resistance of ordinary Portland cement with fly ash

    Directory of Open Access Journals (Sweden)

    Irassar, Edgardo F.

    1989-03-01

    Full Text Available Low calcium fly ash has demonstrated to be an effective pozzolan to improve sulfate resistance of ordinary portland cement (type I. In this paper physico-chemical effects that produce this pozzolan in the mortar exposed to sulfate attack are studied. Dilution and dispersion affects are analyzed using mixes of cement with an inert mineral admixture. Mineralogical changes of mortar are studied using X-ray diffraction and the help of scanning electron microscope. The results show that fly ash delays mortar cracking phenomenon due to less content of unstable compounds in sulfate environment, greater available space to be occupied by expansive compounds and less CH present in the mortars.

    La ceniza volante de bajo contenido de óxido de calcio ha demostrado ser una efectiva puzolana para mejorar la resistencia a los sulfatos del cemento portland normal (CRN. En el presente trabajo se estudian los efectos físico-químicos que produce esta puzolana en el mortero expuesto al ataque de sulfatos. Se analizan los efectos de dilución y dispersión utilizando mezclas de cemento con una adición mineral inactiva. Los cambios mineralógicos del mortero se estudian con difracción de rayos X (DRX y la ayuda del microscopio electrónico. Los resultados indican que la ceniza volante retarda el fenómeno de fisuración del mortero debido a la menor cantidad de compuestos inestables en ambiente con sulfatos, el mayor espacio disponible para albergar a los compuestos expansivos y la disminución del CH presente en la mezcla.

  3. Calcium and Calcium-Base Alloys

    Science.gov (United States)

    1949-01-01

    should be satisfactory, because the electrolytic process for •(!>: A. H. Everts and G. D. Baglev’, " Physical «nrt m<„.+„4 i «_ of Calcium«, Electrochem...Rev. Metalurgie , 3j2, (1), 129 (1935). 10 ^sm^mssss^ma^^ extension between two known loads, is preferable to the value of 3,700,000 p.B.i. obtained

  4. Modeling of ferric sulfate decomposition and sulfation of potassium chloride during grate‐firing of biomass

    DEFF Research Database (Denmark)

    Wu, Hao; Jespersen, Jacob Boll; Jappe Frandsen, Flemming

    2013-01-01

    Ferric sulfate is used as an additive in biomass combustion to convert the released potassium chloride to the less harmful potassium sulfate. The decomposition of ferric sulfate is studied in a fast heating rate thermogravimetric analyzer and a volumetric reaction model is proposed to describe th...

  5. Involvement of highly sulfated chondroitin sulfate in the metastasis of the Lewis lung carcinoma cells.

    NARCIS (Netherlands)

    Li, F.; Dam, G.B. ten; Murugan, S.; Yamada, S.; Hashiguchi, T.; Mizumoto, S.; Oguri, K.; Okayama, M.; Kuppevelt, A.H.M.S.M. van; Sugahara, K.

    2008-01-01

    The altered expression of cell surface chondroitin sulfate (CS) and dermatan sulfate (DS) in cancer cells has been demonstrated to play a key role in malignant transformation and tumor metastasis. However, the functional highly sulfated structures in CS/DS chains and their involvement in the process

  6. Discovery of a Heparan sulfate 3- o -sulfation specific peeling reaction

    NARCIS (Netherlands)

    Huang, Yu; Mao, Yang; Zong, Chengli; Lin, Cheng; Boons, Geert Jan; Zaia, Joseph

    2015-01-01

    Heparan sulfate (HS) 3-O-sulfation determines the binding specificity of HS/heparin for antithrombin III and plays a key role in herpes simplex virus (HSV) infection. However, the low natural abundance of HS 3-O-sulfation poses a serious challenge for functional studies other than the two cases ment

  7. [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 ab

  8. Scientific Opinion on the safety assessment of the active substances, sodium erythorbate, sodium carbonate, sodium bicarbonate, iron sulphate, activated carbon, cellulose, calcium hydroxide, calcium chloride and water, for use as active system in food contact materials

    OpenAIRE

    2014-01-01

    This scientific opinion of EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids deals with the safety assessment of the active substances sodium erythorbate, sodium carbonate, sodium bicarbonate, iron sulfate, activated carbon, cellulose, calcium hydroxide, calcium chloride and water, used in mixture which is packed into sachets for absorbing oxygen/carbon dioxide emitting from/into the headspace surrounding packed food. All substances of this formulation have been e...

  9. The potential for calcium depletion in forest ecosystems of southeastern United States: Review and analysis

    Science.gov (United States)

    Huntington, Thomas G.

    2000-06-01

    Biogeochemical mass balance assessments of calcium status in southeastern forests indicate that losses through harvesting and soil leaching often exceed inputs from atmospheric deposition and weathering. Many forest soils of the southeastern United States are particularly sensitive because these soils and the underlying saprolite from which these soils are derived are largely depleted of weatherable calcium. At most of the intensively studied sites in the southeastern United States, it is estimated that calcium depletion has already reduced or will likely reduce exchangeable soil calcium reserves to less than the estimated requirement for a merchantable forest stand in 150 years or less. At most sites, calcium uptake into merchantable wood equals or exceeds soil leaching losses. Chronic atmospheric deposition of sulfate and nitrate and declining atmospheric deposition of calcium are likely to accelerate calcium depletion. The southeastern U.S. regional distribution of soil calcium pools and calcium fluxes (deposition and uptake in merchantable wood) indicates that the depletion status of the intensively studied sites is representative of a substantially larger area. Where weathering inputs are insufficient to replace leaching and uptake losses, there is a potential for a regional problem in forest nutrition over the long term.

  10. Physico-chemical properties and toxic effect of fruit-ripening agent calcium carbide

    Directory of Open Access Journals (Sweden)

    Mohammad Asif

    2012-01-01

    Full Text Available Ripening is the final stage of the maturation process, when the fruit changes color, softens and develops the flavor, texture and aroma that constitute optimum eating quality. This study was conducted to discuss the use of unsatisfactory calcium carbide to ripen fruits for domestic markets as well as their toxic effects on human health. The commonly used ripening agents are calcium carbide, acetylene, ethylene, propylene, ethrel (2-chloroethyl phosphonic acid, glycol, ethanol and some other agents. The calcium carbide is one of the most commonly used ripening agent for fruits, while other calcium salts like calcium ammonium nitrate, calcium chloride and calcium sulfate are used to delay fruit ripening agents for local fruit industries. The use of calcium carbide is being discouraged worldwide, due to associated health hazards. Calcium carbide treatment of food is extremely hazardous because it contains traces of arsenic and phosphorous, and once dissolved in water, it produces acetylene gas. Arsenic, phosphorous and acetylene gas may affect the different body organs and causes various health problems like headache, dizziness, mood disturbances, sleepiness, mental confusion, memory loss, cerebral edema, seizures and prolonged hypoxia.

  11. Sulfated tyrosines 27 and 29 in the N-terminus of human CXCR3 participate in binding native IP-10

    Institute of Scientific and Technical Information of China (English)

    Jinming GAO; Ruolan XIANG; Lei JIANG; Wenhui LI; Qiping FENG; Zijiang GUO; Qi SUN; Zhengpei ZENG; Fude FANG

    2009-01-01

    Aim:Human CXCR3,a seven-transmembrane segment (7TMS),is predominantly expressed in Th1-mediated responses.Interferon-γ-inducible protein 10 (IP-10) is an important ligand for CXCR3.Their interaction is pivotal for leukocyte migra-tion and activation.Tyrosine sulfation in 7TMS is a posttranslational modification that contributes substantially to ligand binding.We aimed to study the role of tyrosine sulfation of CXCR3 in the protein's binding to IP-10.Methods: Plasmids encoding CXCR3 and its mutants were prepared by PCR and site-directed mutagenesis.HEK 293T cells were transfected with plasmids encoding CXCR3 or its variants using calcium phosphate.Transfected cells were labeled with [35S]-cysteine and methionine or [35S]-Na2SO3 and then analyzed by immunoprecipitation to measure sulfation.Experi-ments with 125I-labeled IP-10 were carried out to evaluate the affinity of CXCR3 for its ligand.Calcium influx assays were used to measure intercellular signal transduction.Results: Our data show that sulfate moieties are added to tyrosines 27 and 29 of CXCR3.Mutation of these two tyrosines to phenylalanines substantially decreases binding of CXCR3 to IP-10 and appears to eliminate the associated signal transduc-tion.Tyrosine sulfation of CXCR3 is enhanced by tyrosyl protein sulfotransferases (TPSTs),and it is weakened by shRNA constructs.The binding ability of CXCR3 to IP-10 is increased by TPSTs and decreased by shRNAs.Conclusion: This study identifies two sulfated tyrosines in the N-terminus of CXCR3 as part of the binding site for IP-10,and it underscores the fact that tyrosine sulfation in the N-termini of 7TMS receptors is functionally important for ligand interactions.Our study suggests a molecular target for inhibiting this ligand-receptor interaction.

  12. 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

  13. Effects of Foliar Spraying of Magnesium-potassium Sulfate Fertilizer on Absorption of Magnesium, Potassium and Calcium in Different-position Tobacco Leaves%叶面喷施硫酸钾镁肥对不同部位烟叶镁、钾、钙吸收的影响

    Institute of Scientific and Technical Information of China (English)

    周敏; 周绍松; 郑波; 鲁耀; 段宗颜; 王建新; 张忠武; 杨景华

    2014-01-01

    design were adopted in this research. The group without Mg fertilization was treated as control. There were 3 treatment groups for foliar spraying of magnesium-potassium sulfate fertilizer and 2 treatment groups for soil application + foliar spraying of magnesium-potassium sulfate fertilizer. The tobac-co roots, stems, lower leaves, middle leaves and upper leaves were dried and weighed. They were grinded for the determination of K, Ca and Mg content. The total K, Ca and Mg content in upper (B2F), middle (C3F) and lower (X2F) flue-cured tobacco leaves in each plot was measured. [Result] The foliar spraying and soil application + foliar spraying al increased the absorption of Mg and K in middle and lower tobacco leaves and the absorption of Ca in lower tobacco leaves, but de-creased the absorption of Mg, K and Ca in upper leaves and the absorption of Ca in middle leaves. Among the positions, the accumulated distribution of Mg, K and Ca ranked as middle leaves > lower leaves > upper leaves. With the application of Mg fertilizer, the Ca/Mg ratio and K/Mg ratio al decreased in middle and upper to-bacco leaves; while the Ca/Mg ratio increased in the lower tobacco leaves, and the K/Mg ratio showed no significant difference among treatment groups. [Conclusion] The foliar spraying and soil application + foliar spraying of magnesium-potassium sulfate fertilizer affected the Ca/Mg ratio and K/Mg ratio in tobacco leaves mainly through affecting the absorption of Mg.

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

    OpenAIRE

    Wilson, Rosamund J; Copley, J Brian

    2017-01-01

    Background Calcium-based and non-calcium-based phosphate binders have similar efficacy in the treatment of hyperphosphatemia; however, calcium-based binders may be associated with hypercalcemia, vascular calcification, and adynamic bone disease. Scope A post hoc analysis was carried out of data from a 16-week, Phase IV study of patients with end-stage renal disease (ESRD) who switched to lanthanum carbonate monotherapy from baseline calcium acetate/calcium carbonate monotherapy. Of the intent...

  15. Fucoidans - sulfated polysaccharides of brown algae

    Energy Technology Data Exchange (ETDEWEB)

    Usov, Anatolii I; Bilan, M I [N.D.Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation)

    2009-08-31

    The methods of isolation of fucoidans and determination of their chemical structures are reviewed. The fucoidans represent sulfated polysaccharides of brown algae, the composition of which varies from simple fucan sulfates to complex heteropolysaccharides. The currently known structures of such biopolymers are presented. A variety of the biological activities of fucoidans is briefly summarised.

  16. Fucoidans — sulfated polysaccharides of brown algae

    Science.gov (United States)

    Usov, Anatolii I.; Bilan, M. I.

    2009-08-01

    The methods of isolation of fucoidans and determination of their chemical structures are reviewed. The fucoidans represent sulfated polysaccharides of brown algae, the composition of which varies from simple fucan sulfates to complex heteropolysaccharides. The currently known structures of such biopolymers are presented. A variety of the biological activities of fucoidans is briefly summarised.

  17. Primary mesenchyme cell migration requires a chondroitin sulfate/dermatan sulfate proteoglycan.

    Science.gov (United States)

    Lane, M C; Solursh, M

    1991-02-01

    Primary mesenchyme cell migration in the sea urchin embryo is inhibited by sulfate deprivation and exposure to exogenous beta-D-xylosides, two treatments known to disrupt proteoglycan synthesis. We show that in the developing sea urchin, exogenous xyloside affects the synthesis by the primary mesenchyme cells of a very large, cell surface chondroitin sulfate/dermatan sulfate proteoglycan. This proteoglycan is present in a partially purified fraction that restores migratory ability to defective cells in vitro. The integrity of this chondroitin sulfate/dermatan sulfate proteoglycan appears essential for primary mesenchyme cell migration since treatment of actively migrating cells with chondroitinase ABC reversibly inhibited their migration in vitro.

  18. Metabolic Flexibility of Sulfate Reducing Bacteria

    Directory of Open Access Journals (Sweden)

    Caroline M. Plugge

    2011-05-01

    Full Text Available Dissimilatory sulfate-reducing prokaryotes (SRB are a very diverse group of anaerobic bacteria that are omnipresent in nature and play an imperative role in the global cycling of carbon and sulfur. In anoxic marine sediments sulfate reduction accounts for up to 50% of the entire organic mineralization in coastal and shelf ecosystems where sulfate diffuses several meters deep into the sediment. As a consequence, SRB would be expected in the sulfate-containing upper sediment layers, whereas methanogenic Archaea would be expected to succeed in the deeper sulfate-depleted layers of the sediment. Where sediments are high in organic matter, sulfate is depleted at shallow sediment depths, and biogenic methane production will occur. In the absence of sulfate, many SRB ferment organic acids and alcohols, producing hydrogen, acetate, and carbon dioxide, and may even rely on hydrogen- and acetate-scavenging methanogens to convert organic compounds to methane. SRB can establish two different life styles, and these can be termed as sulfidogenic and acetogenic, hydrogenogenic metabolism. The advantage of having different metabolic capabilities is that it raises the chance of survival in environments when electron acceptors become depleted. In marine sediments, SRB and methanogens do not compete but rather complement each other in the degradation of organic matter.Also in freshwater ecosystems with sulfate concentrations of only 10-200 μM, sulfate is consumed efficiently within the top several cm of the sediments. Here, many of the δ-Proteobacteria present have the genetic machinery to perform dissimilatory sulfate reduction, yet they have an acetogenic, hydrogenogenic way of life.In this review we evaluate the physiology and metabolic mode of SRB in relation with their environment.

  19. Inositol trisphosphate and calcium signalling

    Science.gov (United States)

    Berridge, Michael J.

    1993-01-01

    Inositol trisphosphate is a second messenger that controls many cellular processes by generating internal calcium signals. It operates through receptors whose molecular and physiological properties closely resemble the calcium-mobilizing ryanodine receptors of muscle. This family of intracellular calcium channels displays the regenerative process of calcium-induced calcium release responsible for the complex spatiotemporal patterns of calcium waves and oscillations. Such a dynamic signalling pathway controls many cellular processes, including fertilization, cell growth, transformation, secretion, smooth muscle contraction, sensory perception and neuronal signalling.

  20. Geochemical and isotopic composition of ground water with emphasis on sources of sulfate in the upper Floridan Aquifer in parts of Marion, Sumter, and Citrus counties, Florida

    Science.gov (United States)

    Sacks, Laura A.

    1996-01-01

    In inland areas of northwest central Florida, sulfate concentrations in the Upper Floridan aquifer are extremely variable and sometimes exceed drinking water standards (250 milligrams per liter). This is unusual because the aquifer is unconfined and near the surface, allowing for active recharge. The sources of sulfate and geochemical processes controlling ground-water composition were evaluated in this area. Water was sampled from thirty-three wells in parts of Marion, Sumter, and Citrus Counties, within the Southwest Florida Water Management District; these included at least a shallow and a deep well at fifteen separate locations. Ground water was analyzed for major ions, selected trace constituents, dissolved organic carbon, and stable isotopes (sulfur-34 of sulfate and sulfide, carbon-13 of inorganic carbon, deuterium, and oxygen-18). Sulfate concentrations ranged from less than 0.2 to 1,400 milligrams per liter, with higher sulfate concentrations usually in water from deeper wells. The samples can be categorized into a low sulfate group (less than 30 milligrams per liter) and a high sulfate group (greater than 30 milligrams per liter). For the high sulfate water, concentrations of calcium and magnesium increased concurrently with sulfate. Chemical and isotopic data and mass-balance modeling indicate that the composition of high sulfate waters is controlled by dedolomitization reactions (dolomite dissolution and calcite precipitation, driven by dissolution of gypsum). Gypsum occurs deeper in the aquifer than open intervals of sampled wells. Upward flow has been documented in deeper parts of the aquifer in the study area, which may be driven by localized discharge areas or rapid flow in shallow parts of the aquifer. Mixing between shallow ground water and sulfate-rich water that dissolved gypsum at the base of the aquifer is probably responsible for the range of concentrations observed in the study area. Other solutes that increased with sulfate apparently

  1. 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)

  2. Calcium and Calcium Supplements: Achieving the Right Balance

    Science.gov (United States)

    ... bone mass, which is a risk factor for osteoporosis. Many Americans don't get enough calcium in their diets. Children and adolescent girls are at particular risk, but so are adults age 50 and older. How much calcium you ...

  3. Mitigation of chloride and sulfate based corrosion in reinforced concrete via electrokinetic nanoparticle treatment

    Science.gov (United States)

    Kupwade-Patil, Kunal

    Concrete is a porous material which is susceptible to the migration of highly deleterious species such as chlorides and sulfates. Various external sources, including sea salt spray, direct seawater wetting, deicing salts and chlorides can contaminate reinforced concrete. Chlorides diffuse into the capillary pores of concrete and come into contact with the reinforcement. When chloride concentration at the reinforcement exceeds a threshold level it breaks down the passive oxide layer, leading to chloride induced corrosion. The application of electrokinetics using positively charged nanoparticles for corrosion protection in reinforced concrete structures is an emerging technology. This technique involves the principle of electrophoretic migration of nanoparticles to hinder chloride diffusion in the concrete. The return of chlorides is inhibited by the electrodeposited assembly of the nanoparticles at the reinforcement interface. This work examined the nanoparticle treatment impact on chloride and sulfate induced corrosion in concrete. Electrokinetic Nanoparticle (EN) treatments were conducted on reinforced cylindrical concrete, rectangular ASTM G109 specimens that simulate a bridge deck and full scale beam specimens. EN treatment to mitigate external sulfate attack in concrete was performed on cylindrical concrete specimens. Corrosion results indicated lower corrosion potentials and rates as compared to the untreated specimens. Scanning electron microscopy (SEM) showed a dense microstructure within the EN treated specimens. Chemical analysis (Raman spectroscopy, X ray-diffraction, and Fourier transform infrared spectroscopy FTIR) showed the presence of strength enhancing phases such as calcium aluminate hydrate (C-A-H) and increased amounts of calcium silicate hydrate (C-S-H) within the EN treated specimens. Strength and porosity results showed an increase in strength and a reduction in porosity among the EN treated specimens. EN treatment acted as a protective

  4. Optimization of a biological sulfate reduction process

    Energy Technology Data Exchange (ETDEWEB)

    Lebel, A.

    1985-01-01

    A biological sulfate reduction process is presented. It is intended to treat sulfate wastes by converting them to hydrogen sulfide which can be further oxidized to elemental sulfur. An optimization study of a completely-mixed reactor system was performed. Major operating parameters were determined at the bench-scale level. The study was conducted in batch-culture experiments, using a mixed Desulfovibrio culture from sewage. Kinetic values were extrapolated using the Michaelis-Menten model, which best fitted the experimental data. The iron loading and the sulfate loading significantly affected the growth and metabolism of sulfate reducing bacteria (SRB). A model to determine V/sub m/ from the iron and sulfate loading values was explored. The model is limited by sulfate loading greater than 4.3 g/l, where bacterial growth is inhibited. Iron loading is not anticipated to suppress the bacterial metabolism efficiency since it remained in the linear pattern even at inhibition levels. Studies of the metabolic behavior of SRB, using lactic acid as the carbon source, showed a requirement of 2.7 moles of lactate for each mole of sulfate. This technique and its application to the sulfur recovery process are discussed.

  5. Di-sulfated Keratan Sulfate as a Novel Biomarker for Mucopolysaccharidosis II, IVA, and IVB.

    Science.gov (United States)

    Shimada, Tsutomu; Tomatsu, Shunji; Mason, Robert W; Yasuda, Eriko; Mackenzie, William G; Hossain, Jobayer; Shibata, Yuniko; Montaño, Adriana M; Kubaski, Francyne; Giugliani, Roberto; Yamaguchi, Seiji; Suzuki, Yasuyuki; Orii, Kenji E; Fukao, Toshiyuki; Orii, Tadao

    2015-01-01

    Keratan sulfate (KS) is a storage material in mucopolysaccharidosis IV (MPS IV). However, no detailed analysis has been reported on subclasses of KS: mono-sulfated KS and di-sulfated KS. We established a novel method to distinguish and quantify mono- and di-sulfated KS using liquid chromatography-tandem mass spectrometry and measured both KS levels in various specimens.Di-sulfated KS was dominant in shark cartilage and rat serum, while mono-sulfated KS was dominant in bovine cornea and human serum. Levels of both mono- and di-sulfated KS varied with age in the blood and urine from control subjects and patients with MPS II and IVA. The mean levels of both forms of KS in the plasma/serum from patients with MPS II, IVA, and IVB were elevated compared with that in age-matched controls. Di-sulfated KS provided more significant difference between MPS IVA and the age-matched controls than mono-sulfated KS. The ratio of di-sulfated KS to total KS in plasma/serum increased with age in control subjects and patients with MPS II but was age independent in MPS IVA patients. Consequently, this ratio can discriminate younger MPS IVA patients from controls. Levels of mono- and di-sulfated KS in urine of MPS IVA and IVB patients were all higher than age-matched controls for all ages studied.In conclusion, the level of di-sulfated KS and its ratio to total KS can distinguish control subjects from patients with MPS II, IVA, and IVB, indicating that di-sulfated KS may be a novel biomarker for these disorders.

  6. Using Terrestrial Sulfate Efflorescences as an Analogue of Hydrated Sulfate Formation in Valles Marineris on Mars

    Science.gov (United States)

    Smith, P. C.; Szynkiewicz, A.

    2015-12-01

    Hydrated sulfate minerals provide conclusive evidence that a hydrologic cycle was once active on the surface of Mars. Two classes of hydrated sulfate minerals have been detected by robotic instruments on Mars: monohydrated sulfate minerals comprised of kieserite and gypsum, and various polyhydrated sulfates with Fe-Ca-Na-Mg-rich compositions. These minerals are found in various locations on Mars, including large surface exposures in valley settings of Valles Marineris. However, the sulfate sources and formation mechanisms of these minerals are not yet well understood.Recently, it has been suggested that the sulfate minerals in Valles Marineris might have formed in a manner similar to sulfate efflorescences found in dry environments on Earth. In this study, we use sulfate effloresences from the Rio Puerco Watershed, New Mexico as a terrestrial analogue to assess major factors that might have led to deposition of sulfate minerals in Valles Marineris. In different seasons indicative of dry and wet conditions, we collected field photographs and sediment samples for chemical and stable isotopic analyses (sulfur content, δ34S) to determine major sources of sulfate ions for efflorescences and to assess how the seasonal changes in surface/groundwater activity affect their formation. Preliminary sulfur isotope results suggest that oxidation of bedrock sulfides (0.01-0.05 wt. S %) is a major source of sulfate ion for efflorescences formation because their δ34S varied in negative range (-28 to -20‰) similar to sulfides (average -32‰). Using field photographs collected in Oct 2006, Feb and Nov 2012, May 2013, Mar and Oct 2014, we infer that the highest surface accumulation of sulfate efflorescences in the studied analog site was observed after summer monsoon seasons when more water was available for surface and subsurface transport of solutes from chemical weathering. Conversely, spring snow melt led to enhanced dissolution of sulfate efflorescences.

  7. Calcium, vitamin D and bone

    OpenAIRE

    Borg, Andrew A.

    2012-01-01

    Calcium, protein and vitamin D are the main nutrients relevant to bone health. This short article discusses the importance of vitamin D and its relation to calcium homeostasis. The various causes, clinical manifestations and treatment are outlined.

  8. Effect of purification pretreatment on the recovery of magnetite from waste ferrous sulfate

    Institute of Scientific and Technical Information of China (English)

    Wang Yu; Ying-lin Peng; Ya-jie Zheng

    2016-01-01

    The present study was conducted to elucidate the influence of impurities in waste ferrous sulfate on its recovery of magnetite. Ferrous sulfate solution was purified by the addition of NaOH solution to precipitate impurities, and magnetite was recovered from fer-rous sulfate solution without and with purification pretreatment. Calcium hydroxide was added to the solution of ferrous sulfate as a pre-cipitator. A mixed product of magnetite and gypsum was subsequently obtained by air oxidation and heating. Wet-milling was performed prior to magnetic separation to recover magnetite from the mixed products. The results show that with the purification pretreatment, the grade of iron in magnetite concentrate increased from 62.05%to 65.58%and the recovery rate of iron decreased from 85.35%to 80.35%. The pu-rification pretreatment reduced the conglutination between magnetite and gypsum, which favors their subsequent magnetic separation. In summary, a higher-grade magnetite with a better crystallinity and a larger particle size of 2.35 μm was obtained with the purification pretreatment.

  9. Attack of Limestone Cement-based Material Exposed to Magnesium Sulfate Solution at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    ZHANG Fengchen; WU Shengxing; FANG Yonghao; ZHOU Jikai; LI Zhonghua

    2014-01-01

    Limestone in cement could be a source of CO32-needed for thaumasite formation which will result in thaumasite form of sulfate attack (TSA) probably. TSA has more deterioration than ettringite or gypsum form of sulfate attack because it targets the calcium silicate hydrates (C-S-H) which is the main binder phase in all Portland cement-based materials. By means of physical and mechanical property testing as well as erosion phases analysis, magnesium sulfate attack of cement-based material containing 35% limestone powder by mass at 5 ± 2℃is investigated. The compressive strength and flexural strength of mortar specimen immersed in MgSO4 solution increase firstly, then decrease rapidly with the immersing age. Relative dynamic elastic modulus of mortar specimen changes in a phased process. After immersing in MgSO4 solution for 15 weeks, the main erosion phases in paste specimen change from four phases compounds, three phases compounds to two phases compounds from surface to inside. Deterioration course of limestone cement-based material exposed to magnesium sulfate aggressive environment appears progressive damage layer by layer, and every layer probably suffers four stages, which are property strengthening stage, initial degradation stage, thaumasite formation stage and cementation loss stage, respectively.

  10. Effect of purification pretreatment on the recovery of magnetite from waste ferrous sulfate

    Science.gov (United States)

    Yu, Wang; Peng, Ying-lin; Zheng, Ya-jie

    2016-08-01

    The present study was conducted to elucidate the influence of impurities in waste ferrous sulfate on its recovery of magnetite. Ferrous sulfate solution was purified by the addition of NaOH solution to precipitate impurities, and magnetite was recovered from ferrous sulfate solution without and with purification pretreatment. Calcium hydroxide was added to the solution of ferrous sulfate as a precipitator. A mixed product of magnetite and gypsum was subsequently obtained by air oxidation and heating. Wet-milling was performed prior to magnetic separation to recover magnetite from the mixed products. The results show that with the purification pretreatment, the grade of iron in magnetite concentrate increased from 62.05% to 65.58% and the recovery rate of iron decreased from 85.35% to 80.35%. The purification pretreatment reduced the conglutination between magnetite and gypsum, which favors their subsequent magnetic separation. In summary, a higher-grade magnetite with a better crystallinity and a larger particle size of 2.35 μm was obtained with the purification pretreatment.

  11. Sulfated binary and trinary oxide solid superacids

    Institute of Scientific and Technical Information of China (English)

    缪长喜; 华伟明; 陈建民; 高滋

    1996-01-01

    A series of sulfated binary and trinary oxide solid superacids were prepared, and their catalytic activities for n-butane isomerization at low temperature were measured. The incorporation of different metal oxides into ZrO2 may produce a positive or negative effect on the acid strength and catalytic activity of the solid superacids. Sulfated oxides of Cr-Zr, Fe-Cr-Zr and Fe-V-Zr are 2 - 3 times more active than the reported sulfated Fe-Mn-Zr oxide. The enhancement in the superacidity and catalytic activity of these new solid superacids has been discussed on account of the results of various characteriation techniques.

  12. Analysis of tyrosine-O-sulfation

    DEFF Research Database (Denmark)

    Bundgaard, J.R.; Sen, J.W.; Johnsen, A.H.

    2008-01-01

    Tyrosine O-sulfation was first described about 50 years ago as a post-translational modification of fibrinogen. In the following 30 years it was considered to be a rare modification affecting only a few proteins and peptides. However, in the beginning of the 1980s tyrosine (Tyr) sulfation was shown...... the presence of radioactively labeled tyrosine. These techniques have been described in detail previously. The aim of this chapter is to present alternative analytical methods of Tyr sulfation than radioisotope incorporation before analysis Udgivelsesdato: 2008...

  13. Chlorate: a reversible inhibitor of proteoglycan sulfation

    Energy Technology Data Exchange (ETDEWEB)

    Humphries, D.E.; Silbert, J.E.

    1988-07-15

    Bovine aorta endothelial cells were cultured in medium containing (/sup 3/H)glucosamine, (/sup 35/S)sulfate, and various concentrations of chlorate. Cell growth was not affected by 10 mM chlorate, while 30 mM chlorate had a slight inhibitory effect. Chlorate concentrations greater than 10 mM resulted in significant undersulfation of chondroitin. With 30 mM chlorate, sulfation of chondroitin was reduced to 10% and heparan to 35% of controls, but (/sup 3/H)glucosamine incorporation on a per cell basis did not appear to be inhibited. Removal of chlorate from the culture medium of cells resulted in the rapid resumption of sulfation.

  14. Interactions in Calcium Oxalate Hydrate/Surfactant Systems.

    Science.gov (United States)

    Sikiric; Filipovic-Vincekovic; Babic-Ivancić Vdović Füredi-Milhofer

    1999-04-15

    Phase transformation of calcium oxalate dihydrate (COD) into the thermodynamically stable monohydrate (COM) in anionic (sodium dodecyl sulfate (SDS)) and cationic (dodecylammonium chloride) surfactant solutions has been studied. Both surfactants inhibit, but do not stop transformation from COD to COM due to their preferential adsorption at different crystal faces. SDS acts as a stronger transformation inhibitor. The general shape of adsorption isotherms of both surfactants at the solid/liquid interface is of two-plateau-type, but differences in the adsorption behavior exist. They originate from different ionic and molecular structures of crystal surfaces and interactions between surfactant headgroups and solid surface. Copyright 1999 Academic Press.

  15. Calcium ion channel and epilepsy

    Institute of Scientific and Technical Information of China (English)

    Yudan Lü; Weihong Lin; Dihui Ma

    2006-01-01

    OBJECTIVE: To review the relationship between calcium ion channel and epilepsy for well investigating the pathogenesis of epilepsy and probing into the new therapeutic pathway of epilepsy.DATA SOURCES: A computer-based online research Calcium ion channel and epilepsy related articles published between January 1994 and December 2006 in the CKNI and Wanfang database with the key words of "calcium influxion, epilepsy, calcium-channel blocker". The language was limited to Chinese. At the same time,related articles published between January 1993 and December 2006 in Pubmed were searched for on online with the key words of "calcium influxion, epilepsy" in English.STUDY SELECTION: The materials were selected firstly. Inclusive criteria: ① Studies related to calcium ion channel and the pat1hogenesis of epilepsy. ② Studies on the application of calcium ion channel blocker in the treatment of epilepsy. Exclusive criteria: repetitive or irrelated studies.DATA EXTRACTION: According to the criteria, 123 articles were retrieved and 93 were excluded due to repetitive or irrelated studies. Altogether 30 articles met the inclusive criteria, 11 of them were about the structure and characters of calcium ion channel, 10 about calcium ion channel and the pathogenesis of epilepsy and 9 about calcium blocker and the treatment of epilepsy.DATA SYNTHESIS: Calcium ion channels mainly consist of voltage dependent calcium channel and receptor operated calcium channel. Depolarization caused by voltage gating channel-induced influxion is the pathological basis of epileptic attack, and it is found in many studies that many anti-epileptic drugs have potential and direct effect to rivalizing voltage-dependent calcium ion channel.CONCLUSION: Calcium influxion plays an important role in the seizure of epilepsy. Some calcium antagonists seen commonly are being tried in the clinical therapy of epilepsy that is being explored, not applied in clinical practice. If there are enough evidences to

  16. Molecular Dynamics Study of the Foam Stability of a Mixed Surfactant System with and without Calcium Ions

    Science.gov (United States)

    Yang, Xiaozhen; Yang, Wenhong; Institute of Chemistry, CAS Team

    2011-03-01

    Foam stability performance of a mixture surfactant system with and without calcium ions, including linear alkylbenzene sulfonate (LAS) and sodium dodecyl sulfate (SDS), has been studied by molecular dynamics. Microscopic interaction analysis reveals that the fraction of free calcium ions, Xf , in film system indicates the extent of the foam stabilities when Xf is in different calcium ion zones. In the system without ions, we found the variable of the surfactant tail mass out of water film, W , is indicator of foam stability. Performance of the mixture system predicted here was supported by experiments.

  17. Calcium carbonate overdose

    Science.gov (United States)

    Calcium carbonate is not very poisonous. Recovery is quite likely. But, long-term overuse is more serious than a single overdose, because it can cause kidney damage. Few people die from an antacid overdose. Keep all medicines in child-proof bottles and out ...

  18. High Blood Calcium (Hypercalcemia)

    Science.gov (United States)

    ... as well as kidney function and levels of calcium in your urine. Your provider may do other tests to further assess your condition, such as checking your blood levels of phosphorus (a mineral). Imaging studies also may be helpful, such as bone ...

  19. 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...

  20. Calcium aluminate in alumina

    Science.gov (United States)

    Altay, Arzu

    The properties of ceramic materials are determined not only by the composition and structure of the phases present, but also by the distribution of impurities, intergranular films and second phases. The phase distribution and microstructure both depend on the fabrication techniques, the raw materials used, the phase-equilibrium relations, grain growth and sintering processes. In this dissertation research, various approaches have been employed to understand fundamental phenomena such as grain growth, impurity segregation, second-phase formation and crystallization. The materials system chosen was alumina intentionally doped with calcium. Atomic-scale structural analyses of grain boundaries in alumina were carried on the processed samples. It was found that above certain calcium concentrations, CA6 precipitated as a second phase at all sintering temperatures. The results also showed that abnormal grain growth can occur after precipitation and it is not only related to the calcium level, but it is also temperature dependent. In order to understand the formation mechanism of CA6 precipitates in calcium doped alumina samples, several studies have been carried out using either bulk materials or thin films The crystallization of CA2 and CA6 powders has been studied. Chemical processing techniques were used to synthesize the powders. It was observed that CA2 powders crystallized directly, however CA6 powders crystallized through gamma-Al 2O3 solid solution. The results of energy-loss near-edge spectrometry confirmed that gamma-Al2O3 can dissolve calcium. Calcium aluminate/alumina reaction couples have also been investigated. All reaction couples were heat treated following deposition. It was found that gamma-Al2O3 was formed at the interface as a result of the interfacial reaction between the film and the substrate. gamma-Al 2O3 at the interface was stable at much higher temperatures compared to the bulk gamma-Al2O3 formed prior to the CA6 crystallization. In order to

  1. Recycling of ferrous sulfate by the synthesis of a new super oxidant material 'Referox'

    Energy Technology Data Exchange (ETDEWEB)

    Evrard, O. [Universite Henri Poincare, Vandoeuvre (France); Dupre, B.; Jeannot, C.; Kanari, N.; Gaballah, I.; Ninane, L.; Verstraete, W.; Denomme, S.; Belsue, M.

    2001-07-01

    This European Union-sponsored project was initiated to develop a process to recycle industrial ferrous sulfate by the synthesis of a superoxidant containing hexavalent (FeVI) iron. Hexavalent iron, also called ferrates, can be used in decontamination of industrial effluents, decolorisation and purification of effluents from the textile and tanning industries, oxidation of cyanide to cyanates, soil remediation, water treatment and in a variety of other processes. Dry synthesis of potassium ferrate, using calcium hypochlorite as the oxidizing agent, was successful. By using chlorine instead of calcium hypochlorite and by partially substituting sodium hydroxide for potassium hydroxide the cost of the synthesis was significantly reduced. Recycling of ferrous sulfate at room temperature by the synthesis of potassium ferrate (FeVI) using gaseous chlorine instead of solid calcium hypochlorite was also successful. The yield of the synthesis was about 65 per cent for the used industrial ferrous sulfate samples. Large scale experimentation of the potassium ferrate synthesis was also carried out, obtaining potassium ferrate that remained stable for several months. The ferrates were used in the treatment of drinking water, wastewater, soil remediation, and effluent decontamination. Encouraging results were obtained. An additional benefit found was that use of the ferrates as bactericide for water treatment instead of chlorine gas eliminates the generation of halo-organic compounds which are suspected to be carcinogenic. 2 figs.

  2. 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...

  3. Bioceramics of calcium orthophosphates.

    Science.gov (United States)

    Dorozhkin, Sergey V

    2010-03-01

    A strong interest in use of ceramics for biomedical applications appeared in the late 1960's. Used initially as alternatives to metals in order to increase a biocompatibility of implants, bioceramics have become a diverse class of biomaterials, presently including three basic types: relatively bioinert ceramics, bioactive (or surface reactive) and bioresorbable ones. Furthermore, any type of bioceramics could be porous to provide tissue ingrowth. This review is devoted to bioceramics prepared from calcium orthophosphates, which belong to the categories of bioresorbable and bioactive compounds. During the past 30-40 years, there have been a number of major advances in this field. Namely, after the initial work on development of bioceramics that was tolerated in the physiological environment, emphasis was shifted towards the use of bioceramics that interacted with bones by forming a direct chemical bond. By the structural and compositional control, it became possible to choose whether the bioceramics of calcium orthophosphates was biologically stable once incorporated within the skeletal structure or whether it was resorbed over time. At the turn of the millennium, a new concept of calcium orthophosphate bioceramics, which is able to regenerate bone tissues, has been developed. Current biomedical applications of calcium orthophosphate bioceramics include 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. Potential future applications of calcium orthophosphate bioceramics will include drug-delivery systems, as well as they will become effective carriers of growth factors, bioactive peptides and/or various types of cells for tissue engineering purposes.

  4. Biological properties of biphasic tricalcium phosphate bioceramics/calcium sulfate bone cement porous three-dimensional scaffolds%双相钙磷生物陶瓷/硫酸钙骨水泥多孔三维支架的生物性能

    Institute of Scientific and Technical Information of China (English)

    谭迎赟; 白石; 廖运茂

    2014-01-01

    背景:随着组织工程技术的发展,多孔生物陶瓷被越来越多的运用到骨缺损的修复中,当前的研究主要集中在这种生物陶瓷的合成及其各项性能的评价。  目的:研究一种新型骨水泥的制备方法并测定其理化性能及与成骨细胞的生物相容性。  方法:共沉淀法制备双相钙磷生物陶瓷粉体,利用胶体团聚成颗粒,烧结后得到颗粒状、多孔羟基磷灰石/磷酸三钙生物陶瓷,并按不同比例与高纯度医用半水硫酸钙混合制备钙磷陶瓷/硫酸钙骨水泥。  结果与结论:X 射线衍射证实合成物质为双相钙磷陶瓷,颗粒状双相钙磷陶瓷具有多孔网状结构,骨水泥在3 min内保持可塑状态,固化时间为15 min,固化温度为36.5℃,压缩强度最高为5.82 MPa,MTT毒性级为0级,成骨细胞在材料表面生长良好。%BACKGROUND:With the development of tissue engineering, porous bioceramics are more and more used to repair bone defects. Current research focuses on the biological synthesis of this bioceramics and its performance evaluation. OBJECTIVE:To discuss the preparation of a new kind of bone cement and to determine its physicochemical properties and biocompatibility with osteoblasts. METHODS:Biphasic tricalcium phosphate powders were prepared using co-precipitation method. The powder was turned into granular stuff by arabic gum. After sintering, porous hydroxyapatite/tricalcium phosphate bioceramics were harvested, and then mixed with alpha-hemihydrate to prepare the bone cement. RESULTS AND CONCLUSION:X-ray diffraction confirmed that the synthetic substance was a kind of biphasic calcium phosphate ceramic having a porous structure. The bone cement could be in the plastic state within 3 minutes. The curing time was 15 minutes, and the curing temperature was 36.5℃. The maximum compression strength was 5.82 MPa, and the MTT toxicity was level 0. Osteoblasts could grew wel on the

  5. Sulfated cellulose thin films with antithrombin affinity

    Directory of Open Access Journals (Sweden)

    2009-11-01

    Full Text Available Cellulose thin films were chemically modified by in situ sulfation to produce surfaces with anticoagulant characteristics. Two celluloses differing in their degree of polymerization (DP: CEL I (DP 215–240 and CEL II (DP 1300–1400 were tethered to maleic anhydride copolymer (MA layers and subsequently exposed to SO3•NMe3 solutions at elevated temperature. The impact of the resulting sulfation on the physicochemical properties of the cellulose films was investigated with respect to film thickness, atomic composition, wettability and roughness. The sulfation was optimized to gain a maximal surface concentration of sulfate groups. The scavenging of antithrombin (AT by the surfaces was determined to conclude on their potential anticoagulant properties.

  6. ROE Wet Sulfate Deposition 2009-2011

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet sulfate deposition in kilograms per hectare from 2009 to 2011. Summary data in this indicator were provided by EPA’s...

  7. Sulfate reduction and methanogenesis at a freshwater

    DEFF Research Database (Denmark)

    Iversen, Vibeke Margrethe Nyvang; Andersen, Martin Søgaard; Jakobsen, Rasmus

    The freshwater-seawater interface was studied in a ~9-m thick anaerobic aquifer located in marine sand and gravel with thin peat lenses. Very limited amounts of iron-oxides are present. Consequently, the dominating redox processes are sulfate reduction and methanogenesis, and the groundwater...... is enriched in dissolved sulfide, methane and bicarbonate. Under normal conditions the seawater-freshwater interface is found at a depth of 4 m at the coastline and reaches the bottom of the aquifer 40 m inland. However, occasional flooding of the area occurs, introducing sulfate to the aquifer. Groundwater...... chemistry was studied in a 120 m transect perpendicular to the coast. Cores were taken for radiotracer rate measurements of sulfate reduction and methanogenesis. In the saline part of the aquifer 35 m inland, sulfate reduction was the dominant process with rates of 0.1-10 mM/year. In the freshwater part 100...

  8. A Comparative Study on Several Models of Experimental Renal Calcium Oxalate Stones Formation in Rats

    Institute of Scientific and Technical Information of China (English)

    LIU Jihong; CAO Zhenggno; ZHANG Zhaohui; ZHOU Siwei; YE Zhangqun

    2007-01-01

    In order to compare the effects of several experimental renal calcium oxalate stones formation models in rats and to find a simple and convenient model with significant effect of calcium oxalate crystals deposition in the kidney, several rat models of renal calcium oxalate stones formation were induced by some crystal-inducing drugs (CID) including ethylene glycol (EG), ammonium chloride (AC), vitamin D3 [1α(OH)VitD3, alfacalcidol], calcium gluconate, ammonium oxalate, gentamicin sulfate, L-hydroxyproline. The rats were fed with drugs given singly or unitedly. At the end of experiment, 24-h urines were collected and the serum creatinine (Cr), blood urea nitrogen (BUN), the extents of calcium oxalate crystal deposition in the renal tissue, urinary calcium and oxalate excretion were measured. The serum Cr levels in the stone-forming groups were significantly higher than those in the control group except for the group EG+L-hydroxyproline, group calcium gluconate and group oxalate. Blood BUN concentration was significantly higher in rats fed with CID than that in control group except for group EG+L-hydroxyproline and group ammonium oxalate plus calcium gluconate. In the group of rats administered with EG plus Vitamin D3, the deposition of calcium oxalate crystal in the renal tissue and urinary calcium excretion were significantly greater than other model groups. The effect of the model induced by EG plus AC was similar to that in the group induced by EG plus Vitamin D3. EG plus Vitamin D3 or EG plus AC could stably and significantly induced the rat model of renal calcium oxalate stones formation.

  9. Sulfate Resistance of Alkali Activated Pozzolans

    OpenAIRE

    Bondar, Dali

    2015-01-01

    The consequence of sulfate attack on geopolymer concrete, made from an alkali activated natural pozzolan (AANP) has been studied in this paper. Changes in the compressive strength, expansion and capillary water absorption of specimens have been investigated combined with phases determination by means of X-ray diffraction. At the end of present investigation which was to evaluate the performance of natural alumina silica based geopolymer concrete in sodium and magnesium sulfate solution, the l...

  10. Is there a correlation between structure and anticoagulant action of sulfated galactans and sulfated fucans?

    Science.gov (United States)

    Pereira, Mariana S; Melo, Fábio R; Mourão, Paulo A S

    2002-10-01

    We attempted to identify the specific structural features in sulfated galactans and sulfated fucans that confer anticoagulant activity. For this study we employed a variety of invertebrate polysaccharides with simple structures composed of well-defined units of oligosaccharides. Our results indicate that a 2-O-sulfated, 3-linked alpha-L-galactan, but not a alpha-L-fucan with a similar molecular size, is a potent thrombin inhibitor mediated by antithrombin or heparin cofactor II. The difference between the activities of these two polysaccharides is not very pronounced when factor Xa replaced thrombin. The occurrence of 2,4-di-O-sulfated units is an amplifying motif for 3-linked alpha-fucan-enhanced thrombin inhibition by antithrombin. If we replace antithrombin by heparin cofactor II, then the major structural requirement for the activity becomes single 4-O-sulfated fucose units. The presence of 2-O-sulfated fucose residues always had a deleterious effect on anticoagulant activity. Overall, our results indicate that the structural requirements for interaction of sulfated galactans and sulfated fucans with coagulation cofactors and their target proteases are stereospecific and not merely a consequence of their charge density and sulfate content.

  11. EGFR Activation Mediates Inhibition of Axon Regeneration by Myelin and Chondroitin Sulfate Proteoglycans

    Science.gov (United States)

    Koprivica, Vuk; Cho, Kin-Sang; Park, Jong Bae; Yiu, Glenn; Atwal, Jasvinder; Gore, Bryan; Kim, Jieun A.; Lin, Estelle; Tessier-Lavigne, Marc; Chen, Dong Feng; He, Zhigang

    2005-10-01

    Inhibitory molecules associated with myelin and the glial scar limit axon regeneration in the adult central nervous system (CNS), but the underlying signaling mechanisms of regeneration inhibition are not fully understood. Here, we show that suppressing the kinase function of the epidermal growth factor receptor (EGFR) blocks the activities of both myelin inhibitors and chondroitin sulfate proteoglycans in inhibiting neurite outgrowth. In addition, regeneration inhibitors trigger the phosphorylation of EGFR in a calcium-dependent manner. Local administration of EGFR inhibitors promotes significant regeneration of injured optic nerve fibers, pointing to a promising therapeutic avenue for enhancing axon regeneration after CNS injury.

  12. Hormonal control of sulfate uptake and assimilation.

    Science.gov (United States)

    Koprivova, Anna; Kopriva, Stanislav

    2016-08-01

    Plant hormones have a plethora of functions in control of plant development, stress response, and primary metabolism, including nutrient homeostasis. In the plant nutrition, the interplay of hormones with responses to nitrate and phosphate deficiency is well described, but relatively little is known about the interaction between phytohormones and regulation of sulfur metabolism. As for other nutrients, sulfate deficiency results in modulation of root architecture, where hormones are expected to play an important role. Accordingly, sulfate deficiency induces genes involved in metabolism of tryptophane and auxin. Also jasmonate biosynthesis is induced, pointing to the need of increase the defense capabilities of the plants when sulfur is limiting. However, hormones affect also sulfate uptake and assimilation. The pathway is coordinately induced by jasmonate and the key enzyme, adenosine 5'-phosphosulfate reductase, is additionally regulated by ethylene, abscisic acid, nitric oxid, and other phytohormones. Perhaps the most intriguing link between hormones and sulfate assimilation is the fact that the main regulator of the response to sulfate starvation, SULFATE LIMITATION1 (SLIM1) belongs to the family of ethylene related transcription factors. We will review the current knowledge of interplay between phytohormones and control of sulfur metabolism and discuss the main open questions.

  13. Preparation of Agarose Sulfate and Its Antithrombogenicity

    Institute of Scientific and Technical Information of China (English)

    JIE Youping; ZHANG Lingmin; CHEN Peng; MAO Xuan; TANG Shunqing

    2012-01-01

    As one of the seaweed polysaccharide,agarose has received much attention because of its biocompatibility.However,its application in biomedical field was limited with its biological inertia.Modification with some functional groups is needed to obtain agarose derivatives with biological activity and expand its applications.Consequently,agarose was sulfated with chlorosulfonic acid-pyridine with formamide as dispersing agent.The orthogonal test result showed that the optimal reaction condition was the reaction time being 4 h,the reaction temperature 65 ℃,and the ratio of chlorosulfonic acid to agarose 1-4(mL/g).Two kinds of the insoluble agarose sulfate (below 37 ℃) were synthesized with degree of substitution (DS) being 0.17 and 0.43 respectively.Infrared spectroscopy (IR) and 13C nuclear magnetic resonance (13C-NMR) spectroscopy results proved that C3-6 in agarose was sulfated.Their hydrophobic property and BSA adsorption capacity rose with increasing DS,while the adsorption of Hb was reduced.The anti-clotting properties of agarose sulfate were significantly improved,and agarose sulfate could protect red blood cells from deformation after adsorption of BSA.These findings demonstrate that the cold-water insoluble agarose sulfate has a promise for applications as heparin-like material in anticoagulation or endothelial regeneration scaffold.

  14. Structure of a rat hepatoma heparan sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Fedarko, N.S.; Ishihara, M.; Conrad, H.E.

    1986-05-01

    Previous studies showed that as monolayer cultures of a rat hepatocyte cell line passed from log growth to confluency there was an increase in sulfation of heparan sulfate (HS) and the accumulation of a unique species of HS with a high content of sulfated GlcA residues in the nucleus. The present study compares the HS metabolism of a rat (Morris) hepatoma line. Cells were labeled with /sup 35/SO/sub 4//sup 2 -/ and the structure and distribution of (/sup 35/SO/sub 4/)HS from the culture medium (CM), the pericellular matrix (Ma), the nucleus (NUC), the outer nuclear membrane (NM), and the remaining cytoplasmic (CP) pool was measured as nitrous acid-susceptible material. The amount of label incorporated into each pool was 1/10 that observed in the hepatocyte line. The HS proteglycan and the free HS chains from the hepatoma showed size distributions similar to those found for the hepatocytes, but a lower average charge density. In the HS from the CM, Ma, and CP pools 56% of glucosamine residues were sulfated; in that from the NM and NUC pools 46% were sulfated. HONO treatment gave mono- and disulfated disaccharides in a ratio of 1.5:1 for all five cellular pools, but showed that the HS from the NUC pool did not contain high levels of sulfated GlcA residues.

  15. Ammonium sulfate preparation from phosphogypsum waste

    Directory of Open Access Journals (Sweden)

    Abdel-Hakim T. Kandil

    2017-01-01

    Full Text Available The Egyptian phosphogypsum waste is treated using sulfuric acid prior the ammonium sulfate production. The relevant factors that would affect the removal efficiencies of some impurities are studied. The optimum conditions of the treatment are 8 M sulfuric acid solution and 1/4 solid/liquid ratio for 30 min contact time at 80 °C. Moreover, the optimum conditions of the ammonium sulfate preparation are 10 g of the suspended impure or purified phosphogypsum in 40 ml of 3% ammonium sulfate solution (as initiator, 1/4 solid/liquid ratio at pH7 at an addition of an excess ammonium carbonate, and 150 rpm stirring speed for 4.0 h contact time at 55 °C as well as the 5 mg of barium chloride is added to remove the radium in the ammonium sulfate product. Finally, the ammonium sulfate is crystallized and the chemical analysis of the product shows 20% nitrogen and 23.6% sulfur. Therefore, the purity of the obtained ammonium sulfate is 95% from the purified phosphogypsum.

  16. 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.

  17. Sulfated polysaccharides and cell differentiation in the sea urchin embryo.

    Science.gov (United States)

    Løvtrup-Rein, H; Løvtrup, S

    1984-01-01

    The synthesis of sulfated polysaccharides during the embryonic development of Paracentrotus lividus has been investigated by incorporation of radioactive sulfate, glucose, glucosamine and fucose. The following substances become labelled: fucan sulfate (approximately 60%), heparan sulfate (approximately 20%) and dermatan sulfate (approximately 20%), and possibly a very slight amount of chondroitin sulfate. In animalized and vegetalized embryos, the rate of incorporation is significantly reduced, and furthermore dermatan sulfate is almost absent in animalized embryos. It is concluded that this substance is associated with the differentiation of vegetative cells, possibly the mesenchyme cells.

  18. Fruit Calcium: Transport and Physiology

    Directory of Open Access Journals (Sweden)

    Bradleigh eHocking

    2016-04-01

    Full Text Available Calcium has well-documented roles in plant signaling, water relations and cell wall interactions. Significant research into how calcium impacts these individual processes in various tissues has been carried out; however, the influence of calcium on fruit ripening has not been thoroughly explored. Here, we review the current state of knowledge on how calcium may impact fruit development, physical traits and disease susceptibility through facilitating developmental and stress response signaling, stabilizing membranes, influencing water relations and modifying cell wall properties through cross-linking of de-esterified pectins. We explore the involvement of calcium in hormone signaling integral to ripening and the physiological mechanisms behind common disorders that have been associated with fruit calcium deficiency (e.g. blossom end rot in tomatoes or bitter pit in apples. This review works towards an improved understanding of how the many roles of calcium interact to influence fruit ripening, and proposes future research directions to fill knowledge gaps. Specifically, we focus mostly on grapes and present a model that integrates existing knowledge around these various functions of calcium in fruit, which provides a basis for understanding the physiological impacts of sub-optimal calcium nutrition in grapes. Calcium accumulation and distribution in fruit is shown to be highly dependent on water delivery and cell wall interactions in the apoplasm. Localized calcium deficiencies observed in particular species or varieties can result from differences in xylem morphology, fruit water relations and pectin composition, and can cause leaky membranes, irregular cell wall softening, impaired hormonal signaling and aberrant fruit development. We propose that the role of apoplasmic calcium-pectin crosslinking, particularly in the xylem, is an understudied area that may have a key influence on fruit water relations. Furthermore, we believe that improved

  19. 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.

  20. Synthesis of calcium superoxide

    Science.gov (United States)

    Rewick, R. T.; Blucher, W. G.; Estacio, P. L.

    1972-01-01

    Efforts to prepare Ca(O2) sub 2 from reactions of calcium compounds with 100% O3 and with O(D-1) atoms generated by photolysis of O3 at 2537 A are described. Samples of Ca(OH) sub 2, CaO, CaO2, Ca metal, and mixtures containing suspected impurities to promote reaction have been treated with excess O3 under static and flow conditions in the presence and absence of UV irradiation. Studies with KO2 suggest that the superoxide anion is stable to radiation at 2537 A but reacts with oxygen atoms generated by the photolysis of O3 to form KO3. Calcium superoxide is expected to behave in an analogous.

  1. Diversity of sulfur isotope fractionations by sulfate-reducing prokaryotes

    DEFF Research Database (Denmark)

    Detmers, Jan; Brüchert, Volker; Habicht, K S;

    2001-01-01

    Batch culture experiments were performed with 32 different sulfate-reducing prokaryotes to explore the diversity in sulfur isotope fractionation during dissimilatory sulfate reduction by pure cultures. The selected strains reflect the phylogenetic and physiologic diversity of presently known....... Sulfate reducers that oxidized the carbon source completely to CO2 showed greater fractionations than sulfate reducers that released acetate as the final product of carbon oxidation. Different metabolic pathways and variable regulation of sulfate transport across the cell membrane all potentially affect...

  2. 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...

  3. Sulfated polysaccharides and immune response: promoter or inhibitor?

    Science.gov (United States)

    Chen, D; Wu, X Z; Wen, Z Y

    2008-06-01

    Sulfated polysaccharides, which frequently connect to core protein, are expressed not only on cell surface but also throughout the extracellular matrix. Besides providing structural integrity of cells, sulfated polysaccharides interact with a variety of sulfated polysaccharides-binding proteins, such as growth factors, cytokines, chemokines and proteases. Sulfated polysaccharides play two-edged roles, inhibitor and promoter, in immune response. Some sulfated polysaccharides act as the immunosuppressor by blocking inflammatory signal transduction induced by proinflammatory cytokines, suppressing the activation of complement and inhibiting the process that leukocytes adhere to and pass through endothelium. On the contrary, the interaction between immune cells and sulfated polysaccharides produced by bacteria, endothelial cells and immune cells initiate the occurrence of immune response. It promotes the processes of recognizing and arresting antigen, migrating transendothelium, moving into and out of immune organ and enhancing the proliferation of lymphocyte. The structure of sulfated polysaccharides, such as molecular weight and sulfated sites heterogeneity, especially the degree of disaccharide sulfation, position of the sulfate moiety and organization of sulfated domains, may play critical role in their controversial effects. As a consequence, the interaction between sulfated polysaccharides and sulfated polysaccharide-binding proteins may be changed by modifying the structure of sulfated polysaccharides chains. The administration of drug targeting sulfated polysaccharide-protein interaction may be useful in treating inflammatory related diseases.

  4. Sulfate transport by chick renal tubule brush-border and basolateral membranes

    Energy Technology Data Exchange (ETDEWEB)

    Renfro, J.L.; Clark, N.B.; Metts, R.E.; Lynch, M.A.

    1987-01-01

    Brush-border and basolateral membrane vesicles (BBMV and BLMV, respectively) were prepared from chick kidney by a calcium precipitation method and by centrifugation on an 8% Percoll self-generating gradient, respectively. In BBMV a 100-mM Na gluconate gradient, out>in, caused concentrative (/sup 35/S) sulfate uptake approximately fivefold greater at 1 min than at 60 min (equilibrium) whether or not the membranes were short-circuited with 100 mM K gluconate, in=out, plus 20 ..mu..g valinomycin/mg protein. A 48-mM HCO/sub 3//sup -/ gradient, in>out, stimulated a 2.5-fold higher uptake at 1 min than at 60 min, and short circuiting as above had no effect on the magnitude of this response. Imposition of a H/sup +/ gradient caused concentrative uptake fourfold higher at 1 min than at equilibrium. Short circuiting as above or addition of 0.1 mM carbonyl cyanide m-chlorophenylhydrazone (CCCP) significantly inhibited the pH gradient effect. Creation of an inside positive electrical potential with 100 mM K gluconate, out>in, plus valinomycin, also caused concentrative sulfate uptake. Based on inhibitor/competitor effects, these are distinct sulfate transport processes. In chick BLMV, imposition of an HCO/sub 3//sup -/ gradient, in>out, produced concentrative sulfate uptake. 4-Acetamido-4'-isothiocyanostilbene 2,2'-disulfonic acid disodium at 0.1 mM was an effective inhibitor of BLMV bicarbonate-sulfate exchange.

  5. On the roles and regulation of chondroitin sulfate and heparan sulfate in zebrafish pharyngeal cartilage morphogenesis

    DEFF Research Database (Denmark)

    Holmborn, Katarina; Habicher, Judith; Kasza, Zsolt;

    2012-01-01

    The present study addresses the roles of heparan sulfate (HS) proteoglycans and chondroitin sulfate (CS) proteoglycans in the development of zebrafish pharyngeal cartilage structures. uxs1 and b3gat3 mutants, predicted to have impaired biosynthesis of both HS and CS because of defective formation...

  6. NMR-based conformation and dynamics of a tetrasaccharide-repeating sulfated fucan substituted by different counterions.

    Science.gov (United States)

    Soares, Paulo A G; Queiroz, Ismael N L; Santos, Gustavo R C; Mourão, Paulo A S; Pomin, Vitor H

    2016-11-01

    The sulfated fucan from the sea urchin Lytechinus variegatus is composed of the repetitive sequence [-3)-α-l-Fucp-4( OSO3-)-(1-3)-α-l-Fucp-2,4-di( OSO3-)-(1-3)-α-l-Fucp-2( OSO3-)-(1-3)-α-l-Fucp-2( OSO3-)-(1-]n . Conformation (of rings and chains) and dynamics of this tetrasaccharide-repeating sulfated fucan substituted by Na(+) , Ca(2+) , and Li(+) as counterions have been examined through experiments of liquid-state nuclear magnetic resonance spectroscopy. Scalar coupling and nuclear Overhauser effect (NOE)-based data have confirmed that all composing units occur as (1) C4 chair conformer regardless of the cation type, unit position within the repeating sequence, and sulfation type. Chain conformation determined by NOE signal pattern assisted by molecular modeling for a theoretical octasaccharide has shown a similar linear 3D structure for the three differently substituted forms. Data derived from spin-relaxation measurements have indicated a contribution of counterion type to dynamics. The calcium-based preparation has shown the highest mobility while the sodiated one showed the lowest mobility. The set of results from this work suggests that counterion type can affect the physicochemical properties of the structurally well-defined sulfated fucan. The counterion effect seems to impact more on the structural mobility than on average conformation of the studied sulfated glycan in solution.

  7. Calcium signalling and calcium channels: evolution and general principles.

    Science.gov (United States)

    Verkhratsky, Alexei; Parpura, Vladimir

    2014-09-15

    Calcium as a divalent cation was selected early in evolution as a signaling molecule to be used by both prokaryotes and eukaryotes. Its low cytosolic concentration likely reflects the initial concentration of this ion in the primordial soup/ocean as unicellular organisms were formed. As the concentration of calcium in the ocean subsequently increased, so did the diversity of homeostatic molecules handling calcium. This includes the plasma membrane channels that allowed the calcium entry, as well as extrusion mechanisms, i.e., exchangers and pumps. Further diversification occurred with the evolution of intracellular organelles, in particular the endoplasmic reticulum and mitochondria, which also contain channels, exchanger(s) and pumps to handle the homeostasis of calcium ions. Calcium signalling system, based around coordinated interactions of the above molecular entities, can be activated by the opening of voltage-gated channels, neurotransmitters, second messengers and/or mechanical stimulation, and as such is all-pervading pathway in physiology and pathophysiology of organisms.

  8. 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

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

  9. EDTA-insoluble, calcium-binding proteoglycan in bovine bone

    Science.gov (United States)

    Hashimoto, Y.; Lester, G. E.; Caterson, B.; Yamauchi, M.

    1995-01-01

    A calcium ion precipitable, trypsin-generated proteoglycan fragment has been isolated from the demineralized, EDTA-insoluble matrices of bone. The demineralized matrix was completely digested with trypsin, increasing concentrations of CaCl2 were added to the supernatant, and the resulting precipitates were analyzed. The amount of precipitate gradually increased with higher concentrations of calcium and was reversibly solubilized by EDTA. After molecular sieve and anion exchange chromatography, a proteoglycan-containing peak was obtained. Immunochemical analysis showed that this peak contained chondroitin 4-sulfate and possibly keratan sulfate. Amino acid analysis showed that this proteoglycan contained high amounts of aspartic acid/asparagine (Asx), serine (Ser), glutamic acid/glutamine (Glx), proline (Pro), and glycine (Gly); however, it contained little leucine (Leu) which suggests that it is not a member of the leucine-rich small proteoglycan family. In addition, significant amounts of phosphoserine (P-Ser) and hydroxyproline (Hyp) were identified in hydrolysates of this fraction. A single band (M(r) 59 kDa) was obtained on SDS-PAGE that stained with Stains-all but not with Coomassie Brilliant Blue R-250. If bone powder was trypsinized prior to demineralization, this proteoglycan-containing fraction was not liberated. Collectively, these results indicate that a proteoglycan occurs in the demineralized matrix that is precipitated with CaCl2 and is closely associated with both mineral and collagen matrices. Such a molecule might facilitate the structural network for the induction of mineralization in bone.

  10. Heparin-like properties of sulfated alginates with defined sequences and sulfation degrees.

    Science.gov (United States)

    Arlov, Øystein; Aachmann, Finn Lillelund; Sundan, Anders; Espevik, Terje; Skjåk-Bræk, Gudmund

    2014-07-14

    Sulfated glycosaminoglycans have a vast range of protein interactions relevant to the development of new biomaterials and pharmaceuticals, but their characterization and application is complicated mainly due to a high structural variability and the relative difficulty to isolate large quantities of structurally homogeneous samples. Functional and versatile analogues of heparin/heparan sulfate can potentially be created from sulfated alginates, which offer structure customizability through targeted enzymatic epimerization and precise tuning of the sulfation degree. Alginates are linear polysaccharides consisting of β-D-mannuronic acid (M) and α-L-guluronic acid (G), derived from brown algae and certain bacteria. The M/G ratio and distribution of blocks are critical parameters for the physical properties of alginates and can be modified in vitro using mannuronic-C5-epimerases to introduce sequence patterns not found in nature. Alginates with homogeneous sequences (poly-M, poly-MG, and poly-G) and similar molecular weights were chemically sulfated and structurally characterized by the use of NMR and elemental analysis. These sulfated alginates were shown to bind and displace HGF from the surface of myeloma cells in a manner similar to heparin. We observed dependence on the sulfation degree (DS) as well as variation in efficacy based on the alginate monosaccharide sequence, relating to relative flexibility and charge density in the polysaccharide chains. Co-incubation with human plasma showed complement compatibility of the alginates and lowering of soluble terminal complement complex levels by sulfated alginates. The sulfated polyalternating (poly-MG) alginate proved to be the most reproducible in terms of precise sulfation degrees and showed the greatest relative degree of complement inhibition and HGF interaction, maintaining high activity at low DS values.

  11. A biological process for the reclamation of flue gas desulfurization gypsum using mixed sulfate-reducing bacteria with inexpensive carbon sources.

    Science.gov (United States)

    Kaufman, E N; Little, M H; Selvaraj, P

    1997-01-01

    A combined chemical and biological process for the recycling of flue gas desulfurization (FGD) gypsum into calcium carbonate and elemental sulfur is demonstrated. In this process, a mixed culture of sulfate-reducing bacteria (SRB) utilizes inexpensive carbon sources, such as sewage digest or synthesis gas, to reduce FGD gypsum to hydrogen sulfide. The sulfide is then oxidized to elemental sulfur via reaction with ferric sulfate, and accumulating calcium ions are precipitated as calcium carbonate using carbon dioxide. Employing anaerobically digested municipal sewage sludge (AD-MSS) medium as a carbon source, SRBs in serum bottles demonstrated an FGD gypsum reduction rate of 8 mg/L/h (10(9) cells)(-1). A chemostat with continuous addition of both AD-MSS media and gypsum exhibited sulfate reduction rates as high as 1.3 kg FGD gypsum/m(3)d. The increased biocatalyst density afforded by cell immobilization in a columnar reactor allowed a productivity of 152 mg SO(4) (-2)/Lh or 6.6 kg FGD gypsum/m(3)d. Both reactors demonstrated 100% conversion of sulfate, with 75-100% recovery of elemental sulfur and chemical oxygen demand utilization as high as 70%. Calcium carbonate was recovered from the reactor effluent on precipitation using carbon dioxide. It was demonstrated that SRBs may also use synthesis gas (CO, H(2), and CO(2) in the reduction of gypsum, further decreasing process costs. The formation of two marketable products-elemental sulfur and calcium carbonate-from FGD gypsum sludge, combined with the use of a low-cost carbon source and further improvements in reactor design, promises to offer an attractive alternative to the landfilling of FGD gypsum.

  12. p-Cresyl sulfate and indoxyl sulfate in pediatric patients on chronic dialysis

    Directory of Open Access Journals (Sweden)

    Hye Sun Hyun

    2013-04-01

    Full Text Available &lt;b&gt;Purpose:&lt;/b&gt; Indoxyl sulfate and p- cresyl sulfate are important protein-bound uremic retention solutes whose levels can be partially reduced by renal replacement therapy. These solutes originate from intestinal bacterial protein fermentation and are associated with cardiovascular outcomes and chronic kidney disease progression. The aims of this study were to investigate the levels of indoxyl sulfate and p- cresyl sulfate as well as the effect of probiotics on reducing the levels of uremic toxins in pediatric patients on dialysis. &lt;b&gt;Methods:&lt;/b&gt; We enrolled 20 pediatric patients undergoing chronic dialysis; 16 patients completed the study. The patients underwent a 12-week regimen of VSL#3, a high-concentration probiotic preparation, and the serum levels of indoxyl sulfate and p- cresyl sulfate were measured before treatment and at 4, 8, and 12 weeks after the regimen by using fluorescence liquid chromatography. To assess the normal range of indoxyl sulfate and p- cresyl sulfate we enrolled the 16 children with normal glomerular filtration rate who had visited an outpatient clinic for asymptomatic microscopic hematuria that had been detected by a school screening in August 2011. &lt;b&gt;Results:&lt;/b&gt; The baseline serum levels of indoxyl sulfate and p- cresyl sulfate in the patients on chronic dialysis were significantly higher than those in the children with microscopic hematuria. The baseline serum levels of p- cresyl sulfate in the peritoneal dialysis group were significantly higher than those in the hemodialysis group. There were no significant changes in the levels of these uremic solutes after 12-week VSL#3 treatment in the patients on chronic dialysis. &lt;b&gt;Conclusion:&lt;/b&gt; The levels of the uremic toxins p- cresyl sulfate and indoxyl sulfate are highly elevated in pediatric patients on dialysis, but there was no significant effect by

  13. Formation of the natural sulfate aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Kerminen, V.M.; Hillamo, R.; Maekinen, M.; Virkkula, A.; Maekelae, T.; Pakkanen, T. [Helsinki Univ. (Finland). Dept. of Physics

    1996-12-31

    Anthropogenic sulfate aerosol, together with particles from biomass burning, may significantly reduce the climatic warming due to man-made greenhouse gases. The radiative forcing of aerosol particles is based on their ability to scatter and absorb solar radiation (direct effect), and on their influences on cloud albedos and lifetimes (indirect effect). The direct aerosol effect depends strongly on the size, number and chemical composition of particles, being greatest for particles of 0.1-1 {mu}m in diameter. The indirect aerosol effect is dictated by the number of particles being able to act as cloud condensation nuclei (CCN). For sulfate particles, the minimum CCN size in tropospheric clouds is of the order of 0.05-0.2 {mu}m. To improve aerosol parameterizations in future climate models, it is required that (1) both primary and secondary sources of various particle types will be characterized at a greater accuracy, and (2) the influences of various atmospheric processes on the spatial and temporal distribution of these particles and their physico-chemical properties are known much better than at the present. In estimating the climatic forcing due to the sulfate particles, one of the major problems is to distinguish between sulfur from anthropogenic sources and that of natural origin. Global emissions of biogenic and anthropogenic sulfate pre-cursors are comparable in magnitude, but over regional scales either of these two source types may dominate. The current presentation is devoted to discussing the natural sulfate aerosol, including the formation of sulfur-derived particles in the marine environment, and the use of particulate methanesulfonic acid (MSA) as a tracer for the natural sulfate

  14. Calcium – how and why?

    Indian Academy of Sciences (India)

    J K Jaiswal

    2001-09-01

    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 that during the origin and early evolution of life the Ca2+ ion was given a unique opportunity to be used in several biological processes because of its unusual physical and chemical properties.

  15. Calcium Phosphate Biomaterials: An Update

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Current calcium phosphate (CaP) biomaterials for bone repair, substitution, augmentation and regeneration include hydroxyapatite ( HA ) from synthetic or biologic origin, beta-tricalcium phosphate ( β-TCP ) , biphasic calcium phosphate (BCP), and are available as granules, porous blocks, components of composites (CaP/polymer) cements, and as coatings on orthopedic and dental implants. Experimental calcium phosphate biomaterials include CO3- and F-substituted apatites, Mg-and Zn-substituted β-TCP, calcium phosphate glasses. This paper is a brief review of the different types of CaP biomaterials and their properties such as bioactivity, osteoconductivity, osteoinductivity.

  16. Studying inhibition of calcium oxalate stone formation: an in vitro approach for screening hydrogen sulfide and its metabolites

    Directory of Open Access Journals (Sweden)

    S. Vaitheeswari

    2015-06-01

    Full Text Available ABSTRACTPurpose:Calcium oxalate urolithiasis is one of the most common urinary tract diseases and is of high prevalence. The present study proposes to evaluate the antilithiatic property of hydrogen sulfide and its metabolites like thiosulfate & sulfate in an in vitro model.Materials and Methods:The antilithiatic activity of sodium hydrogen sulfide (NaSH, sodium thiosulfate (Na2S2O3 and sodium sulfate (Na2SO4 on the kinetics of calcium oxalate crystal formation was investigated both in physiological buffer and in urine from normal and recurrent stone forming volunteers. The stones were characterized by optical and spectroscopic techniques.Results:The stones were characterized to be monoclinic, prismatic and bipyramidal habit which is of calcium monohydrate and dihydrate nature. The FTIR displayed fingerprint corresponding to calcium oxalate in the control while in NaSH treated, S=O vibrations were visible in the spectrum. The order of percentage inhibition was NaSH>Na2S2O3>Na2SO4.Conclusion:Our study indicates that sodium hydrogen sulfide and its metabolite thiosulfate are inhibitors of calcium oxalate stone agglomeration which makes them unstable both in physiological buffer and in urine. This effect is attributed to pH changes and complexing of calcium by S2O32-and SO42- moiety produced by the test compounds.

  17. Calcium measurement methods

    Directory of Open Access Journals (Sweden)

    CarloAlberto Redi

    2010-09-01

    Full Text Available Rightly stressed by prof. Wolfgang Walz in the Preface to the series Neuromethods series, the “careful application of methods is probably the most important step in the process of scientific inquiry”. Thus, I strongly suggest to all those interested in calcium signaling and especially to the new-comers in the hot topic of neuroscience (which has so much space even in science-society debate for its implications in legal issues and in the judge-decision process to take profit from this so well edited book. I am saying this since prof. Verkhratsky and prof. Petersen......

  18. On the evaporation of ammonium sulfate solution

    Energy Technology Data Exchange (ETDEWEB)

    Drisdell, Walter S.; Saykally, Richard J.; Cohen, Ronald C.

    2009-07-16

    Aqueous evaporation and condensation kinetics are poorly understood, and uncertainties in their rates affect predictions of cloud behavior and therefore climate. We measured the cooling rate of 3 M ammonium sulfate droplets undergoing free evaporation via Raman thermometry. Analysis of the measurements yields a value of 0.58 {+-} 0.05 for the evaporation coefficient, identical to that previously determined for pure water. These results imply that subsaturated aqueous ammonium sulfate, which is the most abundant inorganic component of atmospheric aerosol, does not affect the vapor-liquid exchange mechanism for cloud droplets, despite reducing the saturation vapor pressure of water significantly.

  19. Molybdate transport through the plant sulfate transporter SHST1.

    Science.gov (United States)

    Fitzpatrick, Kate L; Tyerman, Stephen D; Kaiser, Brent N

    2008-04-30

    Molybdenum is an essential micronutrient required by plants. The mechanism of molybdenum uptake in plants is poorly understood, however, evidence has suggested that sulfate transporters may be involved. The sulfate transporter from Stylosanthes hamata, SHST1, restored growth of the sulfate transport yeast mutant, YSD1, on media containing low amounts of molybdate. Kinetic analysis using 99MoO4(2-) demonstrated that SHST1 enhanced the uptake of molybdate into yeast cells at nM concentrations. Uptake was not inhibited by sulfate, but sulfate transport via SHST1 was reduced with molybdate. These results are the first measurement of molybdate transport by a characterised plant sulfate transport protein.

  20. Selective sulfation of carrageenans and the influence of sulfate regiochemistry on anticoagulant properties.

    Science.gov (United States)

    de Araújo, Cristiano A; Noseda, Miguel D; Cipriani, Thales R; Gonçalves, Alan G; Duarte, Maria Eugênia R; Ducatti, Diogo R B

    2013-01-16

    Sulfated polysaccharides are recognized for their broad range of biological activities, including anticoagulant properties. The positions occupied by the sulfate groups are often related to the level of the inherent biological activity. Herein the naturally sulfated galactans, kappa-, iota- and theta-carrageenan, were additionally sulfated by regioselective means. The anticoagulant activity of the resulting samples was then studied using the aPTT in vitro assay. The influence of sulfate regiochemistry on the anticoagulant activity was evaluated. From kappa-carrageenan three rare polysaccharides were synthesized, one of them involved a synthetic route with an amphiphilic polysaccharide intermediate containing pivaloyl groups. Iota- and theta-carrageenan were utilized in a selective C6 sulfation at β-D-Galp units to produce different structures comprising trisulfated diads. All the samples were characterized by NMR (1D and 2D). The resulting aPPT measurements suggested that sulfation at C2 of 3,6-anhydro-α-D-Galp and C6 of β-D-Galp increased the anticoagulant activity.

  1. Extracellular calcium sensing and extracellular calcium signaling

    Science.gov (United States)

    Brown, E. M.; MacLeod, R. J.; O'Malley, B. W. (Principal Investigator)

    2001-01-01

    , localized changes in Ca(o)(2+) within the ECF can originate from several mechanisms, including fluxes of calcium ions into or out of cellular or extracellular stores or across epithelium that absorb or secrete Ca(2+). In any event, the CaR and other receptors/sensors for Ca(o)(2+) and probably for other extracellular ions represent versatile regulators of numerous cellular functions and may serve as important therapeutic targets.

  2. Activation and transfer of sulfate in biological systems (1960); Activation biologique du sulfate et son transfert (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Chapeville, F. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    It examines in this review the successive stages of active sulfate formation and its role in biological synthesis of sulfuric esters. The possible role of active sulfate as intermediary in sulfate reduction is also discussed. (author) [French] On examine dans cette etude les stades successifs de la mise en evidence du sulfate actif, son role dans la formation des esters sulfuriques de natures diverses, ainsi que sa participation eventuelle comme intermediaire au cours de la reduction du sulfate. On decrit aussi un procede de preparation du systeme biologique, generateur du sulfate actif et une methode de synthese chimique. (auteur)

  3. Vitamin D, Calcium, and Bone Health

    Science.gov (United States)

    ... in Balance › Vitamin D, Calcium, and Bone Health 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 ...

  4. 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 ...

  5. Calcium Deposits in the Crayfish, Cherax quadricarinatus: Microstructure Versus Elemental Distribution.

    Science.gov (United States)

    Luquet, Gilles; Dauphin, Yannicke; Percot, Aline; Salomé, Murielle; Ziegler, Andreas; Fernández, Maria S; Arias, José L

    2016-02-01

    The crayfish Cherax quadricarinatus stores calcium ions, easily mobilizable after molting, for calcifying parts of the new exoskeleton. They are chiefly stored as amorphous calcium carbonate (ACC) during each premolt in a pair of gastroliths synthesized in the stomach wall. How calcium carbonate is stabilized in the amorphous state in such a biocomposite remains speculative. The knowledge of the microstructure at the nanometer level obtained by field emission scanning electron microscopy and atomic force microscopy combined with scanning electron microscopy energy-dispersive X-ray spectroscopy, micro-Raman and X-ray absorption near edge structure spectroscopy gave relevant information on the elaboration of such an ACC-stabilized biomineral. We observed nanogranules distributed along chitin-protein fibers and the aggregation of granules in thin layers. AFM confirmed the nanolevel structure, showing granules probably surrounded by an organic layer and also revealing a second level of aggregation as described for other crystalline biominerals. Raman analyses showed the presence of ACC, amorphous calcium phosphate, and calcite. Elemental analyses confirmed the presence of elements like Fe, Na, Mg, P, and S. P and S are heterogeneously distributed. P is present in both the mineral and organic phases of gastroliths. S seems present as sulfate (probably as sulfated sugars), sulfonate, sulfite, and sulfoxide groups and, in a lesser extent, as sulfur-containing amino acids.

  6. Influence of calcium and silicon supplementation into Pleurotus ostreatus substrates on quality of fresh and canned mushrooms.

    Science.gov (United States)

    Thongsook, T; Kongbangkerd, T

    2011-08-01

    Supplements of gypsum (calcium source), pumice (silicon source) and pumice sulfate (silicon and calcium source) into substrates for oyster mushrooms (Pleurotus ostreatus) were searched for their effects on production as well as qualities of fresh and canned mushrooms. The addition of pumice up to 30% had no effect on total yield, size distribution and cap diameters. The supplementation of gypsum at 10% decreased the total yield; and although gypsum at 5% did not affect total yield, the treatment increased the proportion of large-sized caps. High content (>10%) of pumice sulfate resulted in the lower yield. Calcium and silicon contents in the fruit bodies were not influenced by supplementations. The centrifugal drip loss values and solid content of fresh mushrooms, and the percentage of weight gained and firmness of canned mushrooms, cultivated in substrates supplemented with gypsum, pumice and pumice sulfate were significantly (p≤0.05) higher than those of the control. Scanning electron micrographs revealed the more compacted hyphae of mushroom stalks supplemented with silicon and/or calcium after heat treatment, compared to the control. Supplementation of P. ostreatus substrates with 20% pumice was the most practical treatment because it showed no effect on yield and the most cost-effective.

  7. Sulfate-reducing bacteria in anaerobic bioreactors.

    NARCIS (Netherlands)

    Oude Elferink, S.J.W.H.

    1998-01-01

    The treatment of industrial wastewaters containing high amounts of easily degradable organic compounds in anaerobic bioreactors is a well-established process. Similarly, wastewaters which in addition to organic compounds also contain sulfate can be treated in this way. For a long time, the occurrenc

  8. Plasmin Regulation through Allosteric, Sulfated, Small Molecules

    Directory of Open Access Journals (Sweden)

    Rami A. Al-Horani

    2015-01-01

    Full Text Available Plasmin, a key serine protease, plays a major role in clot lysis and extracellular matrix remodeling. Heparin, a natural polydisperse sulfated glycosaminoglycan, is known to allosterically modulate plasmin activity. No small allosteric inhibitor of plasmin has been discovered to date. We screened an in-house library of 55 sulfated, small glycosaminoglycan mimetics based on nine distinct scaffolds and varying number and positions of sulfate groups to discover several promising hits. Of these, a pentasulfated flavonoid-quinazolinone dimer 32 was found to be the most potent sulfated small inhibitor of plasmin (IC50 = 45 μM, efficacy = 100%. Michaelis-Menten kinetic studies revealed an allosteric inhibition of plasmin by these inhibitors. Studies also indicated that the most potent inhibitors are selective for plasmin over thrombin and factor Xa, two serine proteases in coagulation cascade. Interestingly, different inhibitors exhibited different levels of efficacy (40%–100%, an observation alluding to the unique advantage offered by an allosteric process. Overall, our work presents the first small, synthetic allosteric plasmin inhibitors for further rational design.

  9. Intravenous magnesium sulfate therapy in severe asthma

    Directory of Open Access Journals (Sweden)

    Mohd. Al-Ajmi

    2007-01-01

    Full Text Available A 22-year-old female, known asthmatic since seven years, developed severe bronchospasm in the preop-erative period. Bronchospasm remained unresponsive to the inhaled beta-agonist plus anticholinergic, IV ami-nophylline and hydrocortisone but responded quickly with magnesium sulfate® ( PSI, KSA infusion 1.25gm in 100ml normal saline over 20 minutes and another 1.25 gm over next 30 minutes as the initial infusion showed improvement in her clinical symptoms. Within half an hour of administering the 1st infusion of magnesium sulfate (1.25 gm the respiratory rate started reducing, rhonchi became less, SpO 2 came upto 92% and re-mained always above 90%. Encouraged by this result IV magnesium sulfate 2.5 gm in 500 ml normal saline was infused over next 24 hours along with alternate salbutamol and ipratropium nebulization every 6 hourly. With this treatment regimen the patient became asymptomatic within next 24 hours with normal clinical parameters and FEV 1 value. Hence it may be concluded that IV magnesium sulfate can be considered for patients with acute severe asthma who do not respond to standard therapeutic medications.

  10. METABOLISM OF SULFATE-REDUCING PROKARYOTES

    NARCIS (Netherlands)

    HANSEN, TA

    1994-01-01

    Dissimilatory sulfate reduction is carried out by a heterogeneous group of bacteria and archaea that occur in environments with temperatures up to 105 degrees C. As a group together they have the capacity to metabolize a wide variety of compounds ranging from hydrogen via typical organic fermentatio

  11. Sulfate transport in Penicillium chrysogenum plasma membranes

    NARCIS (Netherlands)

    Hillenga, Dirk J.; Versantvoort, Hanneke J.M.; Driessen, Arnold J.M.; Konings, Wil N.

    1996-01-01

    Transport studies with Penicillium chrysogenum plasma membranes fused with cytochrome c oxidase liposomes demonstrate that sulfate uptake is driven by the transmembrane pH gradient and not by the transmembrane electrical potential. Ca2+ and other divalent cations are not required. It is concluded th

  12. Sulfato de calcio: propiedades y aplicaciones clínicas Calcium sulfate: properties and clinical applications

    OpenAIRE

    J. López(); Alarcón, M

    2011-01-01

    Durante más de cien años el sulfato de calcio se ha distinguido de otros biomateriales, por ser uno de los materiales aloplásticos más simples y que presenta la más larga historia clínica como material sintético. Entre sus principales propiedades destacan que es de fácil obtención, capacidad de osteoconducción, es totalmente absorbible, no provoca reacciones de inflamación o antigénicas, fácil modelado y fuerza de compresión semejante al tejido óseo. Todas éstas características son necesarias...

  13. Radiation damage in calcium sulfate; Danos de radiacao em sulfato de calcio

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, Antonio Roberto Pereira Leite

    1977-12-15

    We used the techniques of Electron Paramagnetic Resonance (EPR) to study the free radicals produced by X-radiation in natural crystals of Gypsum (CaSO{sub 4}2H{sub 2}0). We observed the formation of four free radicals. The spectra of these radicals are overlapped, being separated by power and temperature variation measurements. Two radicals were univocal identified, as being of OH{sup +} and 0{sub 2}H{sup +}. We suggest the assignment of SO{sub 4}{sup -} and O{sub 2}{sup -} to two other radicals. From angular variation measurements, we determined the components of tensors {r_reversible}g and {r_reversible}A of the radicals OH{sup -} and O{sub 2}H{sup -}. (author)

  14. 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.

  15. Calcium sulfate combined with guided tissue regeneration: A novel technique in treatment of gingival recessions

    OpenAIRE

    Arnav Mukherji

    2016-01-01

    The presence of mucogingival problem around anterior teeth is a challenge to the clinician as not only biological and functional aspects has to be addressed but esthetic aspirations of the patient have to be met. The use of guided tissue regeneration (GTR) procedures for the treatment of gingival recession has shown encouraging results and is gaining clinical acceptance. However, maintenance of space under the membrane remains a problem for clinicians. Hence, this case study was an innovative...

  16. 21 CFR 524.1204 - Kanamycin sulfate, calcium amphomycin, and hydrocortisone acetate.

    Science.gov (United States)

    2010-04-01

    ... antibiotics: Acute otitis externa, furunculosis, folliculitis, pruritus, anal gland infections, erythema, decubital ulcer, superficial wounds, and superficial abscesses. (2) The ointment should be applied to the... of the anal gland, the drug should be introduced into the orifice of the gland and not through...

  17. Conversion of phosphogypsum to potassium sulfate and calcium carbonate in aqueous solution

    Directory of Open Access Journals (Sweden)

    Ennaciri Y.

    2013-09-01

    Full Text Available The dissociation of the phosphogysum by the liquid route which is the object of our work, is most appropriate and little expensive. Indeed, it leads to materials of direct application. The present work has for objective to study the decomposition of the phosphogypsum by the soft chemistry into valuable products such as K2SO4 and CaCO3. K2SO4 is a fertilizer which is highly recommended in the field of the agriculture, while CaCO3 can be used in the fields of the industry (cement and the environment. According to the obtained results, we notice that the decomposition of the phosphogypsum in aqueous solution is very workable, reproducible, inexpensive and it is an ecologically interesting reaction. This reaction is made at room temperature and in aqueous environment, by giving two valuable products K2SO4 and CaCO3. The reaction is total after one hour and a half.

  18. Bacterial transport of sulfate, molybdate, and related oxyanions.

    Science.gov (United States)

    Aguilar-Barajas, Esther; Díaz-Pérez, César; Ramírez-Díaz, Martha I; Riveros-Rosas, Héctor; Cervantes, Carlos

    2011-08-01

    Sulfur is an essential element for microorganisms and it can be obtained from varied compounds, sulfate being the preferred source. The first step for sulfate assimilation, sulfate uptake, has been studied in several bacterial species. This article reviews the properties of different bacterial (and archaeal) transporters for sulfate, molybdate, and related oxyanions. Sulfate uptake is carried out by sulfate permeases that belong to the SulT (CysPTWA), SulP, CysP/(PiT), and CysZ families. The oxyanions molybdate, tungstate, selenate and chromate are structurally related to sulfate. Molybdate is transported mainly by the high-affinity ModABC system and tungstate by the TupABC and WtpABC systems. CysPTWA, ModABC, TupABC, and WtpABC are homologous ATP-binding cassette (ABC)-type transporters with similar organization and properties. Uptake of selenate and chromate oxyanions occurs mainly through sulfate permeases.

  19. Pregnenolone Sulfate: From Steroid Metabolite to TRP Channel Ligand

    Directory of Open Access Journals (Sweden)

    Christian Harteneck

    2013-09-01

    Full Text Available Pregnenolone sulfate is a steroid metabolite with a plethora of actions and functions. As a neurosteroid, pregnenolone sulfate modulates a variety of ion channels, transporters, and enzymes. Interestingly, as a sulfated steroid, pregnenolone sulfate is not the final- or waste-product of pregnenolone being sulfated via a phase II metabolism reaction and renally excreted, as one would presume from the pharmacology textbook knowledge. Pregnenolone sulfate is also the source and thereby the starting point for subsequent steroid synthesis pathways. Most recently, pregnenolone sulfate has been functionally “upgraded” from modulator of ion channels to an activating ion channel ligand. This review will focus on molecular aspects of the neurosteroid, pregnenolone sulfate, its metabolism, concentrations in serum and tissues and last not least will summarize the functional data.

  20. Vitamin D and Intestinal Calcium Absorption

    OpenAIRE

    Christakos, Sylvia; Dhawan, Puneet; Porta, Angela; Mady, Leila J.; Seth, Tanya

    2011-01-01

    The principal function of vitamin D in calcium homeostasis is to increase calcium absorption from the intestine. Calcium is absorbed by both an active transcellular pathway, which is energy dependent, and by a passive paracellular pathway through tight junctions. 1,25Dihydroxyvitamin D3 (1,25(OH)2D3) the hormonally active form of vitamin D, through its genomic actions, is the major stimulator of active intestinal calcium absorption which involves calcium influx, translocation of calcium throu...

  1. Mammary-Specific Ablation of the Calcium-Sensing Receptor During Lactation Alters Maternal Calcium Metabolism, Milk Calcium Transport, and Neonatal Calcium Accrual

    OpenAIRE

    Mamillapalli, Ramanaiah; VanHouten, Joshua; Dann, Pamela; Bikle, Daniel; Chang, Wenhan; Brown, Edward; Wysolmerski, John

    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 ...

  2. 21 CFR 524.960 - Flumethasone, neomycin sulfate, and polymyxin B sulfate ophthalmic solutions.

    Science.gov (United States)

    2010-04-01

    ... sulfate, with or without hydroxypropyl methylcellulose. (b) Sponsor. See No. 000856 in § 510.600(c) of this chapter. (c) Conditions of use—(1) Amount—(i) Preparation containing hydroxypropyl...

  3. Do Ca2+-adsorbing ceramics reduce the release of calcium ions from gypsum-based biomaterials?

    Science.gov (United States)

    Belcarz, Anna; Zalewska, Justyna; Pałka, Krzysztof; Hajnos, Mieczysław; Ginalska, Grazyna

    2015-02-01

    Bone implantable materials based on calcium sulfate dihydrate dissolve quickly in tissue liquids and release calcium ions at very high levels. This phenomenon induces temporary toxicity for osteoblasts, may cause local inflammation and delay the healing process. Reduction in the calcium ion release rate by gypsum could be therefore beneficial for the healing of gypsum-filled bone defects. The aim of this study concerned the potential use of calcium phosphate ceramics of various porosities for the reduction of high Ca(2+) ion release from gypsum-based materials. Highly porous ceramics failed to reduce the level of Ca(2+) ions released to the medium in a continuous flow system. However, it succeeded to shorten the period of high calcium level. It was not the phase composition but the high porosity of ceramics that was found crucial for both the shortening of the Ca(2+) release-related toxicity period and intensification of apatite deposition on the composite. Nonporous ceramics was completely ineffective for this purpose and did not show any ability to absorb calcium ions at a significant level. Moreover, according to our observations, complex studies imitating in vivo systems, rather than standard tests, are essential for the proper evaluation of implantable biomaterials.

  4. Sources of sulfate supporting anaerobic metabolism in a contaminated aquifer

    Science.gov (United States)

    Ulrich, G.A.; Breit, G.N.; Cozzarelli, I.M.; Suflita, J.M.

    2003-01-01

    Field and laboratory techniques were used to identify the biogeochemical factors affecting sulfate reduction in a shallow, unconsolidated alluvial aquifer contaminated with landfill leachate. Depth profiles of 35S-sulfate reduction rates in aquifer sediments were positively correlated with the concentration of dissolved sulfate. Manipulation of the sulfate concentration in samples revealed a Michaelis-Menten-like relationship with an apparent Km and Vmax of approximately 80 and 0.83 ??M SO4-2??day-1, respectively. The concentration of sulfate in the core of the leachate plume was well below 20 ??M and coincided with very low reduction rates. Thus, the concentration and availability of this anion could limit in situ sulfate-reducing activity. Three sulfate sources were identified, including iron sulfide oxidation, barite dissolution, and advective flux of sulfate. The relative importance of these sources varied with depth in the alluvium. The relatively high concentration of dissolved sulfate at the water table is attributed to the microbial oxidation of iron sulfides in response to fluctuations of the water table. At intermediate depths, barite dissolves in undersaturated pore water containing relatively high concentrations of dissolved barium (???100 ??M) and low concentrations of sulfate. Dissolution is consistent with the surface texture of detrital barite grains in contact with leachate. Laboratory incubations of unamended and barite-amended aquifer slurries supported the field observation of increasing concentrations of barium in solution when sulfate reached low levels. At a deeper highly permeable interval just above the confining bottom layer of the aquifer, sulfate reduction rates were markedly higher than rates at intermediate depths. Sulfate is supplied to this deeper zone by advection of uncontaminated groundwater beneath the landfill. The measured rates of sulfate reduction in the aquifer also correlated with the abundance of accumulated iron sulfide

  5. Influence of the Ca/Si ratio of the C–S–H phase on the interaction with sulfate ions and its impact on the ettringite crystallization pressure

    Energy Technology Data Exchange (ETDEWEB)

    Kunther, Wolfgang [Instrument Centre for Solid-State NMR Spectroscopy, Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus C (Denmark); Lothenbach, Barbara [Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Concrete/Construction Chemistry, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Skibsted, Jørgen, E-mail: jskib@chem.au.dk [Instrument Centre for Solid-State NMR Spectroscopy, Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus C (Denmark)

    2015-03-15

    The effect of the Ca/Si ratio of the calcium–silicate–hydrate (C–S–H) phase on the interaction with sulfate ions is investigated for C–S–H phases (Ca/Si = 0.83, 1.25, 1.50) and mortar samples of blended Portland cements. It is shown that leaching of calcium from C–S–H and portlandite affects the composition of the pore solution and contributes to the developing crystallization pressure of ettringite. Sulfate profiles show that sulfate binding before cracking is similar for different Ca/Si ratios whereas the highest expansion rates are observed for the mortars with the highest Ca/Si ratios. After leaching in sulfate solutions, the C–S–H samples have been characterized by {sup 29}Si MAS NMR, thermogravimetric analysis, and elemental solution analysis. Generally, the exposure to sulfate solutions results in decalcification of the C–S–H, which increases with decreasing Ca/Si ratio. The data are in good agreement with thermodynamic modeling, indicating that equilibrium is almost achieved in the leached systems. Finally, the expansion of mortar samples exposed to sulfate solutions was much less at lower Ca/Si ratios of the cement blends. This reduced expansion can be related to the decrease of the supersaturation of the pore solution with respect to ettringite at lower Ca/Si ratios of the C–S–H and in the absence of portlandite.

  6. 21 CFR 184.1191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of... soda process”; (2) By precipitation of calcium carbonate from calcium hydroxide in the...

  7. Comprehensive sulfation model verified for T-T sorbent clusters during flue gas desulfurization at moderate temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Yuran Li; Haiying Qi; Changfu You; Lizhai Yang [Tsinghua University, Beijing (China). Key Laboratory for Thermal Science and Power Engineering of Ministry of Education

    2010-08-15

    An empirical sulfation model for T-T sorbent clusters was developed based on amassed experimental results under moderate temperatures (300-800{sup o}C). In the model, the reaction rate is a function of clusters mass, SO{sub 2} concentration, CO{sub 2} concentration, calcium conversion and temperature. The smaller pore volume partly results in a lower reaction rate at lower temperatures. The exponent on SO{sub 2} concentration is 0.88 in the rapid reaction stage and then decreases gradually as reaction progresses. The exponent on the fraction of the unreacted calcium is 1/3 in the first stage and then increases significantly in the second stage. The CO{sub 2} concentration has a negative influence on SO{sub 2} removal, especially for the temperature range of 400-650{sup o}C, which should be avoided to achieve a high effective calcium conversion. The sulfation model has been verified for the T-T sorbent clusters and has also been applied to CaO particles. Over extensive reaction conditions, the predictions agree well with experimental data. 17 refs., 10 figs., 2 tabs.

  8. Nanocrystalline cellulose with various contents of sulfate groups.

    Science.gov (United States)

    Voronova, M I; Surov, O V; Zakharov, A G

    2013-10-15

    Properties of films derived from aqueous nanocrystalline cellulose dispersions by water evaporation depend on concentration of sulfate groups. Namely type of thermodestruction and surface morphology change as a function of contents of sulfate groups. Surface roughness increases and water adsorption enhances with increasing sulfate groups content particularly at high relative pressure.

  9. 21 CFR 522.1484 - Neomycin sulfate sterile solution.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Neomycin sulfate sterile solution. 522.1484... § 522.1484 Neomycin sulfate sterile solution. (a) Specifications. Each milliliter of sterile aqueous solution contains 50 milligrams of neomycin sulfate (equivalent to 35 milligrams of neomycin base).1...

  10. 21 CFR 524.1484a - Neomycin sulfate ophthalmic ointment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Neomycin sulfate ophthalmic ointment. 524.1484a... § 524.1484a Neomycin sulfate ophthalmic ointment. (a) Specifications. Each gram of the ointment contains 5 milligrams of neomycin sulfate equivalent in activity to 3.5 milligrams of neomycin base....

  11. Thermophilic Sulfate-Reducing Bacteria in Cold Marine Sediment

    DEFF Research Database (Denmark)

    ISAKSEN, MF; BAK, F.; JØRGENSEN, BB

    1994-01-01

    C to search for presence of psychrophilic, mesophilic and thermophilic sulfate-reducing bacteria. Detectable activity was initially only in the mesophilic range, but after a lag phase sulfate reduction by thermophilic sulfate-reducing bacteria were observed. No distinct activity of psychrophilic...

  12. De Novo Sequencing of Complex Mixtures of Heparan Sulfate Oligosaccharides

    NARCIS (Netherlands)

    Huang, Rongrong; Zong, Chengli; Venot, Andre; Chiu, Yulun; Zhou, Dandan; Boons, Geert-Jan; Sharp, Joshua S

    2016-01-01

    Here, we describe the first sequencing method of a complex mixture of heparan sulfate tetrasaccharides by LC-MS/MS. Heparin and heparan sulfate (HS) are linear polysaccharides that are modified in a complex manner by N- and O-sulfation, N-acetylation, and epimerization of the uronic acid. Heparin an

  13. Evolution of the Calcium Paradigm: The Relation between Vitamin D, Serum Calcium and Calcium Absorption

    Directory of Open Access Journals (Sweden)

    Borje E. Christopher Nordin

    2010-09-01

    Full Text Available Osteoporosis is the index disease for calcium deficiency, just as rickets/osteomalacia is the index disease for vitamin D deficiency, but there is considerable overlap between them. The common explanation for this overlap is that hypovitaminosis D causes malabsorption of calcium which then causes secondary hyperparathyroidism and is effectively the same thing as calcium deficiency. This paradigm is incorrect. Hypovitaminosis D causes secondary hyperparathyroidism at serum calcidiol levels lower than 60 nmol/L long before it causes malabsorption of calcium because serum calcitriol (which controls calcium absorption is maintained until serum calcidiol falls below 20 nmol/L. This secondary hyperparathyroidism, probably due to loss of a “calcaemic” action of vitamin D on bone first described in 1957, destroys bone and explains why vitamin D insufficiency is a risk factor for osteoporosis. Vitamin D thus plays a central role in the maintenance of the serum (ionised calcium, which is more important to the organism than the preservation of the skeleton. Bone is sacrificed when absorbed dietary calcium does not match excretion through the skin, kidneys and bowel which is why calcium deficiency causes osteoporosis in experimental animals and, by implication, in humans.

  14. Acid Sulfate Alteration in Gusev Crater, Mars

    Science.gov (United States)

    Morris, R. V.; Ming, D. W.; Catalano, J. G.

    2016-01-01

    The Mars Exploration Rover (MER) Spirit landed on the Gusev Crater plains west of the Columbia Hills in January, 2004, during the Martian summer (sol 0; sol = 1 Martian day = 24 hr 40 min). Spirit explored the Columbia Hills of Gusev Crater in the vicinity of Home Plate at the onset on its second winter (sol approximately 900) until the onset of its fourth winter (sol approximately 2170). At that time, Spirit became mired in a deposit of fined-grained and sulfate-rich soil with dust-covered solar panels and unfavorable pointing of the solar arrays toward the sun. Spirit has not communicated with the Earth since sol 2210 (January, 2011). Like its twin rover Opportunity, which landed on the opposite side of Mars at Meridiani Planum, Spirit has an Alpha Particle X-Ray Spectrometer (APXS) instrument for chemical analyses and a Moessbauer spectrometer (MB) for measurement of iron redox state, mineralogical speciation, and quantitative distribution among oxidation (Fe(3+)/sigma Fe) and coordination (octahedral versus tetrahedral) states and mineralogical speciation (e.g., olivine, pyroxene, ilmenite, carbonate, and sulfate). The concentration of SO3 in Gusev rocks and soils varies from approximately 1 to approximately 34 wt%. Because the APXS instrument does not detect low atomic number elements (e.g., H and C), major-element oxide concentrations are normalized to sum to 100 wt%, i.e., contributions of H2O, CO2, NO2, etc. to the bulk composition care not considered. The majority of Gusev samples have approximately 6 plus or minus 5 wt% SO3, but there is a group of samples with high SO3 concentrations (approximately 30 wt%) and high total iron concentrations (approximately 20 wt%). There is also a group with low total Fe and SO3 concentrations that is also characterized by high SiO2 concentrations (greater than 70 wt%). The trend labeled "Basaltic Soil" is interpreted as mixtures in variable proportions between unaltered igneous material and oxidized and SO3-rich basaltic

  15. Calcium binding protein-mediated regulation of voltage-gated calcium channels linked to human diseases

    Institute of Scientific and Technical Information of China (English)

    Nasrin NFJATBAKHSH; Zhong-ping FENG

    2011-01-01

    Calcium ion entry through voltage-gated calcium channels is essential for cellular signalling in a wide variety of cells and multiple physiological processes. Perturbations of voltage-gated calcium channel function can lead to pathophysiological consequences. Calcium binding proteins serve as calcium sensors and regulate the calcium channel properties via feedback mechanisms. This review highlights the current evidences of calcium binding protein-mediated channel regulation in human diseases.

  16. ELECTRON DETACHMENT DISSOCIATION OF SYNTHETIC HEPARAN SULFATE GLYCOSAMINOGLYCAN TETRASACCHARIDES VARYING IN DEGREE OF SULFATION AND HEXURONIC ACID STEREOCHEMISTRY.

    Science.gov (United States)

    Leach, Franklin E; Arungundram, Sailaja; Al-Mafraji, Kanar; Venot, Andre; Boons, Geert-Jan; Amster, I Jonathan

    2012-12-15

    Glycosaminoglycan (GAG) carbohydrates provide a challenging analytical target for structural determination due to their polydisperse nature, non-template biosynthesis, and labile sulfate modifications. The resultant structures, although heterogeneous, contain domains which indicate a sulfation pattern or code that correlates to specific function. Mass spectrometry, in particular electron detachment dissociation Fourier transform ion cyclotron resonance (EDD FT-ICR MS), provides a highly sensitive platform for GAG structural analysis by providing cross-ring cleavages for sulfation location and product ions specific to hexuronic acid stereochemistry. To investigate the effect of sulfation pattern and variations in stereochemistry on EDD spectra, a series of synthetic heparan sulfate (HS) tetrasaccharides are examined. Whereas previous studies have focused on lowly sulfated compounds (0.5-1 sulfate groups per disaccharide), the current work extends the application of EDD to more highly sulfated tetrasaccharides (1-2 sulfate groups per disaccharide) and presents the first EDD of a tetrasaccharide containing a sulfated hexuronic acid. For these more highly sulfated HS oligomers, alternative strategies are shown to be effective for extracting full structural details. These strategies inlcude sodium cation replacement of protons, for determining the sites of sulfation, and desulfation of the oligosaccharides for the generation of product ions for assigning uronic acid stereochemistry.

  17. Introduction of sulfate groups on poly(ethylene) surfaces by argon plasma immobilization of sodium alkyl sulfates

    NARCIS (Netherlands)

    Lens, J.P.; Terlingen, J.G.A.; Engbers, G.H.M.; Feijen, J.

    1998-01-01

    Sulfate groups were introduced at the surface of poly(ethylene) (PE) samples. This was accomplished by immobilizing a precoated layer of either sodium 10-undecene sulfate (S11(:)) or sodium dodecane sulfate (SDS) on the polymeric surface by means of an argon plasma treatment. For this purpose, S11(:

  18. Scientific Opinion on the safety assessment of the active substances, sodium erythorbate, sodium carbonate, sodium bicarbonate, iron sulphate, activated carbon, cellulose, calcium hydroxide, calcium chloride and water, for use as active system in food contact materials

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF

    2014-02-01

    Full Text Available This scientific opinion of EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids deals with the safety assessment of the active substances sodium erythorbate, sodium carbonate, sodium bicarbonate, iron sulfate, activated carbon, cellulose, calcium hydroxide, calcium chloride and water, used in mixture which is packed into sachets for absorbing oxygen/carbon dioxide emitting from/into the headspace surrounding packed food. All substances of this formulation have been evaluated and approved for use as additives in plastic food contact materials or as food additives. No migration of calcium, iron and sodium ions was detected. No volatile organic compounds other than carbon dioxide were detected at the limit of detection of 0.5 μg/l. The CEF Panel concluded that the use of the substances sodium erythorbate, sodium carbonate, sodium bicarbonate, iron sulfate, activated carbon, cellulose, calcium hydroxide, calcium chloride and water does not raise a safety concern when used in oxygen absorber/carbon dioxide emitter systems, in sachets that prevent the physical release of their contents into the food. The sachets are to be placed in the headspace of the packaging and as such may come into occasional contact with the food, e.g. during handling. The sachet should not come into direct contact with liquid foods or foods that have and external aqueous liquid phase on the surface (liquid or exudates.

  19. Calcium signals in olfactory neurons.

    Science.gov (United States)

    Tareilus, E; Noé, J; Breer, H

    1995-11-09

    Laser scanning confocal microscopy in combination with the fluorescent calcium indicators Fluo-3 and Fura-Red was employed to estimate the intracellular concentration of free calcium ions in individual olfactory receptor neurons and to monitor temporal and spatial changes in the Ca(2+)-level upon stimulation. The chemosensory cells responded to odorants with a significant increase in the calcium concentration, preferentially in the dendritic knob. Applying various stimulation paradigma, it was found that in a population of isolated cells, subsets of receptor neurons display distinct patterns of responsiveness.

  20. Sulfate and acid resistant concrete and mortar

    Science.gov (United States)

    Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.

    1998-01-01

    The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction and other applications, which hardenable mixtures demonstrate significant levels of acid and sulfate resistance while maintaining acceptable compressive strength properties. The acid and sulfate hardenable mixtures of the invention containing fly ash comprise cementitious materials and a fine aggregate. The cementitous materials may comprise fly ash as well as cement. The fine aggregate may comprise fly ash as well as sand. The total amount of fly ash in the hardenable mixture ranges from about 60% to about 120% of the total amount of cement, by weight, whether the fly ash is included as a cementious material, fine aggregate, or an additive, or any combination of the foregoing. In specific examples, mortar containing 50% fly ash and 50% cement in cementitious materials demonstrated superior properties of corrosion resistance.

  1. Cholesterol sulfate in human physiology: what's it all about?

    Science.gov (United States)

    Strott, Charles A; Higashi, Yuko

    2003-07-01

    Cholesterol sulfate is quantitatively the most important known sterol sulfate in human plasma, where it is present in a concentration that overlaps that of the other abundant circulating steroid sulfate, dehydroepiandrosterone (DHEA) sulfate. Although these sulfolipids have similar production and metabolic clearance rates, they arise from distinct sources and are metabolized by different pathways. While the function of DHEA sulfate remains an enigma, cholesterol sulfate has emerged as an important regulatory molecule. Cholesterol sulfate is a component of cell membranes where it has a stabilizing role, e.g., protecting erythrocytes from osmotic lysis and regulating sperm capacitation. It is present in platelet membranes where it supports platelet adhesion. Cholesterol sulfate can regulate the activity of serine proteases, e.g., those involved in blood clotting, fibrinolysis, and epidermal cell adhesion. As a result of its ability to regulate the activity of selective protein kinase C isoforms and modulate the specificity of phosphatidylinositol 3-kinase, cholesterol sulfate is involved in signal transduction. Cholesterol sulfate functions in keratinocyte differentiation, inducing genes that encode for key components involved in development of the barrier. The accumulating evidence demonstrating a regulatory function for cholesterol sulfate appears solid; the challenge now is to work out the molecular mechanisms whereby this interesting molecule carries out its various roles.

  2. Effects of sulfate chitosan derivatives on nonalcoholic fatty liver disease

    Science.gov (United States)

    Yu, Mingming; Wang, Yuanhong; Jiang, Tingfu; Lv, Zhihua

    2014-06-01

    Sulfate chitosan derivatives have good solubility and therapeutic effect on the cell model of NAFLD. The aim of this study was to examine the therapeutic effect of sulfate chitosan derivatives on NAFLD. The male Wistar rats were orally fed high fat emulsion and received sulfate chitosan derivatives for 5 weeks to determine the pre-treatment effect of sulfate chitosan derivatives on NAFLD. To evaluate the therapeutic effect of sulfate chitosan derivatives on NAFLD, the rats were orally fed with high concentration emulsion for 5 weeks, followed by sulfate chitosan derivatives for 3 weeks. Histological analysis and biomedical assays showed that sulfate chitosan derivatives can dramatically prevent the development of hepatic steatosis in hepatocyte cells. In animal studies, pre-treatment and treatment with sulfate chitosan derivatives significantly protected against hepatic steatohepatitis induced by high fat diet according to histological analysis. Furthermore, increased TC, ALT, MDA, and LEP in NAFLD were significantly ameliorated by pre-treatment and treatment with sulfate chitosan derivatives. Furthermore, increased TG, AST, and TNF-α in NAFLD were significantly ameliorated by treatment with sulfate chitosan derivatives. Sulfate chitosan derivatives have good pre-treatment and therapeutic effect on NAFLD.

  3. The Importance of Heparan Sulfate in Herpesvirus Infection

    Institute of Scientific and Technical Information of China (English)

    Christopher D.O'Donnell; Deepak Shukla

    2008-01-01

    Herpes simplex virus type-1 (HSV-1) is one of many pathogens that use the cell surface glycosaminoglycan heparan sulfate as a receptor.Heparan sulfate is highly expressed on the surface and extracellular matrix of virtually all cell types making it an ideal receptor.Heparan sulfate interacts with HSV-1 envelope glycoproteins gB and gC during the initial attachment step during HSV-1 entry.In addition,a modified form of heparan sulfate,known as 3-O-sulfated heparan sulfate,interacts with HSV-1 gD to induce fusion between the viral envelope and host cell membrane.The 3-O-sulfation of heparan sulfate is a rare modification which occurs during the biosynthesis of heparan sulfate that is carded out by a family of enzymes known as 3-O-sulfotransferases.Due to its involvement in multiple steps of the infection process,heparan sulfate has been a prime target for the development of agents to inhibit HSV entry.Understanding how heparan sulfate functions during HSV-1 infection may not only be critical for inhibiting infection by this virus,but it may also be crucial in the fight against many other pathogens as well.

  4. Effects of Sulfate Chitosan Derivatives on Nonalcoholic Fatty Liver Disease

    Institute of Scientific and Technical Information of China (English)

    YU Mingming; WANG Yuanhong; JIANG Tingfu; LV Zhihua

    2014-01-01

    Sulfate chitosan derivatives have good solubility and therapeutic effect on the cell model of NAFLD. The aim of this study was to examine the therapeutic effect of sulfate chitosan derivatives on NAFLD. The male Wistar rats were orally fed high fat emulsion and received sulfate chitosan derivatives for 5 weeks to determine the pre-treatment effect of sulfate chitosan derivatives on NAFLD. To evaluate the therapeutic effect of sulfate chitosan derivatives on NAFLD, the rats were orally fed with high concentra-tion emulsion for 5 weeks, followed by sulfate chitosan derivatives for 3 weeks. Histological analysis and biomedical assays showed that sulfate chitosan derivatives can dramatically prevent the development of hepatic steatosis in hepatocyte cells. In animal studies, pre-treatment and treatment with sulfate chitosan derivatives significantly protected against hepatic steatohepatitis induced by high fat diet according to histological analysis. Furthermore, increased TC, ALT, MDA, and LEP in NAFLD were significantly amelio-rated by pre-treatment and treatment with sulfate chitosan derivatives. Furthermore, increased TG, AST, and TNF-α in NAFLD were significantly ameliorated by treatment with sulfate chitosan derivatives. Sulfate chitosan derivatives have good pre-treatment and therapeutic effect on NAFLD.

  5. Engineering sulfotransferases to modify heparan sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ding; Moon, Andrea F.; Song, Danyin; Pedersen, Lars C.; Liu, Jian (NIH); (UNC)

    2008-03-19

    The biosynthesis of heparan sulfate (HS) involves an array of specialized sulfotransferases. Here, we present a study aimed at engineering the substrate specificity of different HS 3-O-sulfotransferase isoforms. Based on the crystal structures, we identified a pair of amino acid residues responsible for selecting the substrates. Mutations of these residues altered the substrate specificities. Our results demonstrate the feasibility of tailoring the specificity of sulfotransferases to modify HS with desired functions.

  6. Fermentative hydrogen production at high sulfate concentration

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chin-Chao [Environmental Resources Laboratory, Department of Landscape Architecture, Chungchou Institute of Technology, Changhwa 51022 (China); Chen, Hong-Pin; Wu, Jou-Hsien; Lin, Chiu-Yue [BioHydrogen Laboratory, Department of Water Resource Engineering, Feng Chia University, P.O. Box 25-123, Taichung 40724 (China)

    2008-03-15

    The hydraulic retention time (HRT) effects on fermentative hydrogen production from sucrose at high sulfate concentration of 3 g-SO{sub 4}{sup 2-}/l were studied using enriched mixed-microflora in a continuously fed reactor. The tested HRTs and organic loading rate ranged from 10 to 2 h and 48 to 240 g-COD/l-day, respectively, and the operating pH was 5.5. The experimental results indicate that hydrogen production could not be inhibited under high sulfate concentration and the efficiency was HRT-dependent with a short HRT of 4 h efficiently enhanced hydrogen production. At this HRT the biogas production rate and hydrogen gas content peaked with the hydrogen yield, hydrogen production rate and specific hydrogen production rate of 4.70 mol-H{sub 2}/mol-sucrose, 874 mmol-H{sub 2}/l-day and 432 mmol-H{sub 2}/g-VSS-day, respectively. These values were 50%, 80% and 300%, respectively, higher than those reported for 12 h HRT at the same sulfate concentration. The metabolite concentration fractions were butyrate 77.3%, acetate 15.6%, ethanol 4.4% and propionate 2.0% and changed to 55%, 27.3%, 11.2% and 6.5%, respectively, at HRT 2 h. Therefore, intimate HRT control is important to obtain efficient hydrogen production. Based on a biological growth comparison, pH 5.5 was considered to be the optimal value for operating a hydrogen-producing fermenter fed on sulfate-rich substrate. (author)

  7. Nickel hydroxide precipitation from aqueous sulfate media

    Science.gov (United States)

    Sist, Cinziana; Demopoulos, George P.

    2003-08-01

    Hydrometallurgical processing of laterite ores constitutes a major industrial and R&D activity in extractive metallurgy. In some of the process flowsheets, nickel hydroxide precipitation is incorporated. For these operations, the optimization of nickel hydroxide precipitation is important to assure efficiency and product quality. The main objective of this investigation was to study and improve the precipitation characteristics of Ni(OH)2 in a sulfate system using supersaturation controlled precipitation.

  8. Studies on the binding of amylopectin sulfate with gastric mucin.

    Science.gov (United States)

    Kim, Y S; Bella, A; Whitehead, J S; Isaacs, R; Remer, L

    1975-07-01

    Amylopectin sulfate, a sulfated polysaccharide that has an antipeptic property, was examined for its ability to bind gastric mucins. After chemically cross-linking the amylopectin sulfate into an insoluble gel, its binding with mucins isolated from antral and fundic mucosa of canine stomachs was studied with chromatography. A component present in both mucin fractions bound to the amylopectin sulfate gel below pH 4.5. This binding was reversible, and the complex dissociated above pH 5. Similar binding properties were found with soluble amylopectin sulfate. The component of the mucine which bound to amylopectin sulfate differed from the one which did not bind in its electrophoretic mobility and in its higher proportion of basic amino acids and a lower hexosamine, serine, and threonine content. This study suggests that amylopectin sulfate may bind to gastric mucins only under conditions of low pH.

  9. 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...

  10. Conformation of sulfated galactan and sulfated fucan in aqueous solutions: implications to their anticoagulant activities.

    Science.gov (United States)

    Becker, Camila F; Guimarães, Jorge A; Mourão, Paulo A S; Verli, Hugo

    2007-07-01

    The discovery of sulfated galactans and sulfated fucans in marine invertebrates with simple and ordered structures opened new perspectives to investigate the biological activity of these molecules and to determine whether different structures confer high affinity for a particular protein. We undertook a conformational analysis of a 2-sulfated, 3-linked alpha-L-galactan and of a alpha-L-fucan with similar structure. Through comparison between theoretical and NMR derived coupling constants, we observed that the pyranose rings are predominantly in the (1)C(4) conformation in these polysaccharides. Additionally, the geometry of the glycosidic linkages was determined based on force field calculations, indicating that the two polysaccharides have similar conformations in solution. Since the sulfated alpha-L-galactan, but not the alpha-L-fucan potentiates antithrombin (AT) inhibition of thrombin, the solution conformations of the compounds were docked into AT and the complexes obtained were refined through molecular dynamics calculations. The obtained results indicates extremely different orientations for the two polysaccharides, which well correlates and explain their distinct anticoagulant activities. Finally, the molecular mechanism of a selective 2-desulfation reaction, observed among sulfated fucans, was explained as a consequence of an intramolecular hydrogen bond capable of assisting in the removal of the charged group.

  11. Calcium Orthophosphate Cements and Concretes

    Directory of Open Access Journals (Sweden)

    Sergey V. Dorozhkin

    2009-03-01

    Full Text Available In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are a bioactive and biodegradable grafting material in the form of a powder and a liquid. Both phases form after mixing a viscous paste that after being implanted, sets and hardens within the body as either a non-stoichiometric calcium deficient hydroxyapatite (CDHA or brushite, sometimes blended with unreacted particles and other phases. As both CDHA and brushite are remarkably biocompartible and bioresorbable (therefore, in vivo they can be replaced with newly forming bone, calcium orthophosphate cements represent a good correction technique for non-weight-bearing bone fractures or defects and appear to be very promising materials for bone grafting applications. Besides, these cements possess an excellent osteoconductivity, molding capabilities and easy manipulation. Furthermore, reinforced cement formulations are available, which in a certain sense might be described as calcium orthophosphate concretes. The concepts established by calcium orthophosphate cement pioneers in the early 1980s were used as a platform to initiate a new generation of bone substitute materials for commercialization. Since then, advances have been made in the composition, performance and manufacturing; several beneficial formulations have already been introduced as a result. Many other compositions are in experimental stages. In this review, an insight into calcium orthophosphate cements and concretes, as excellent biomaterials suitable for both dental and bone grafting application, has been provided.

  12. Factors affecting calcium balance in Chinese adolescents.

    Science.gov (United States)

    Yin, Jing; Zhang, Qian; Liu, Ailing; Du, Weijing; Wang, Xiaoyan; Hu, Xiaoqi; Ma, Guansheng

    2010-01-01

    Chinese dietary reference intakes (DRIs) for calcium were developed mainly from studies conducted amongst Caucasians, yet a recent review showed that reference calcium intakes for Asians are likely to be different from those of Caucasians (Lee and Jiang, 2008). In order to develop calcium DRIs for Chinese adolescents, it is necessary to explore the characteristics and potential influencing factors of calcium metabolic balance in Chinese adolescents. A total of 80 students (15.1+/-0.8 years) were recruited stratified by gender from a 1-year calcium supplementation study. Subjects were randomly designed to four groups and supplemented with calcium carbonate tablets providing elemental calcium at 63, 354, 660, and 966 mg/day, respectively. Subjects consumed food from a 3-day cycle menu prepared by staff for 10 days. Elemental calcium in samples of foods, feces, and urine was determined in duplicates by inductively coupled plasma atomic emission spectrometry. The total calcium intake ranged from 352 to 1323 mg/day. The calcium apparent absorption efficiency and retention in boys were significantly higher than that in girls (68.7% vs. 46.4%, 480 mg/day vs. 204 mg/day, PCalcium retention increased with calcium intakes, but did not reach a plateau. Calcium absorption efficiency in boys increased with calcium intake up to 665 mg/day, and decreased after that. In girls, calcium absorption efficiency decreased with calcium intake. Calcium absorption efficiency increased within 1 year after first spermatorrhea in boys, but decreased with pubertal development in girls. Sex, calcium intake, age, and pubertal development were the most important determinants of calcium absorption (R(2)=0.508, Pcalcium intake, age, and pubertal development are important factors for calcium retention and absorption during growth, which should be considered for the development of calcium DRIs for Chinese adolescents.

  13. Heritability and clinical determinants of serum indoxyl sulfate and p-cresyl sulfate, candidate biomarkers of the human microbiome enterotype.

    Directory of Open Access Journals (Sweden)

    Liesbeth Viaene

    Full Text Available BACKGROUND: Indoxyl sulfate and p-cresyl sulfate are unique microbial co-metabolites. Both co-metabolites have been involved in the pathogenesis of accelerated cardiovascular disease and renal disease progression. Available evidence suggests that indoxyl sulfate and p-cresyl sulfate may be considered candidate biomarkers of the human enterotype and may help to explain the link between diet and cardiovascular disease burden. OBJECTIVE AND DESIGN: Information on clinical determinants and heritability of indoxyl sulfate and p-cresyl sulfate serum is non-existing. To clarify this issue, the authors determined serum levels of indoxyl sulfate and p-cresyl sulfate in 773 individuals, recruited in the frame of the Flemish Study on Environment, Genes and Health Outcomes (FLEMENGHO study. RESULTS: Serum levels of indoxyl sulfate and p-cresyl sulfate amounted to 3.1 (2.4-4.3 and 13.0 (7.4-21.5 μM, respectively. Regression analysis identified renal function, age and sex as independent determinants of both co-metabolites. Both serum indoxyl sulfate (h2 = 0.17 and p-cresyl sulfate (h2 = 0.18 concentrations showed moderate but significant heritability after adjustment for covariables, with significant genetic and environmental correlations for both co-metabolites. LIMITATIONS: Family studies cannot provide conclusive evidence for a genetic contribution, as confounding by shared environmental effects can never be excluded. CONCLUSIONS: The heritability of indoxyl sulfate and p-cresyl sulfate is moderate. Besides genetic host factors and environmental factors, also renal function, sex and age influence the serum levels of these co-metabolites.

  14. Analysis of serum Calcium, Magnesium, and Parathyroid Hormone in neonates delivered following preeclampsia treatment.

    Science.gov (United States)

    Vahabi, S; Zaman, M; Farzan, B

    2016-12-30

    Due to the approximate clinical and biochemical manifestations of calcium and magnesium disturbances, with regard to the regulatory effects of parathyroid hormone (PTH), this present study is designed to analyze serum calcium (Ca), magnesium (Mg), and (PTH) at the time of birth, 24 hours afterwards in newborns after the mother has been treated with Mg-sulfate. We registered 86 term and preterm neonates (43 in each group) using simple census method delivered through vagina to preeclampsia pregnant women treated with Mg-sulfate immediately before birth in Khoramabad Asali Hospital, Iran. The first specimen was obtained from umbilical cord blood at birth, followed by the second sample of 2cc peripherally obtained from blood 24 hours after birth. The mean serum Mg level was higher than normal for both specimens in both term and preterm groups with no significant difference. The mean serum Ca level was higher in term group at both occasions, which turned out to be statistically significant (Pmagnesium level showed a significant decline at 24 hours (P = 0.005) while PTH increased significantly (p<0.000) and (p=0.005) for term and preterm groups respectively. In contrast, Ca changes were not significantly different between the two specimens. Treatment with Mg-sulfate immediately before vaginal delivery increases Mg in both term and preterm neonates with no effect on Ca and PTH levels.

  15. Reactions of calcium-based sorbents with sulfur in coal during gasification

    Energy Technology Data Exchange (ETDEWEB)

    Rehmat, A.; Abbasian, M.J.; Leppin, D.; Banerjee, D.D.

    1987-01-01

    This status report outlines the results obtained to date of the current research program supported jointly by the Gas Research Institute and the State of Illinois Center for Research on Sulfur in Coal. The overall objective is to obtain data related to the efficient utilization of high-sulfur Illinois coal in a One-Step Desulfurization Process by employing in-situ removal of sulfur using calcium-based sorbents. The project includes a study of fluidization behavior of coal char/sorbent mixtures and the reactions of calcium-based sorbents with sulfur present in the coal during gasification. The tests are conducted in bench-scale units; an 8-inch fluidization column is utilized for fluidization tests, and a thermobalance reactor is used for gas-solid reactions. The test parameters include the choice of sorbent, sorbent size, the effect of temperature on sulfation and sulfidation reactions, the effect of the steam-to-hydrogen sulfide ratio on the sulfidation reaction, the effect of the steam on the sulfation reaction, and the influence of exposure time on sulfation of the presulfided sorbent. The reaction conditions for these reactions have been chosen to be directly applicable to scale-up of the One-Step Desulfurization Process. 7 refs., 9 figs., 11 tabs.

  16. Sulfation pattern of fucose branches affects the anti-hyperlipidemic activities of fucosylated chondroitin sulfate.

    Science.gov (United States)

    Wu, Nian; Zhang, Yu; Ye, Xingqian; Hu, Yaqin; Ding, Tian; Chen, Shiguo

    2016-08-20

    Fucosylated chondroitin sulfates (fCSs) are glycosaminoglycans extracted from sea cucumbers, consisting of chondroitin sulfate E (CSE) backbones and sulfated fucose branches. The biological properties of fCSs could be affected by the sulfation pattern of their fucose branches. In the present study, two fCSs were isolated from sea cucumbers Isostichopus badionotus (fCS-Ib) and Pearsonothuria graeffei (fCS-Pg). Their monosaccharide compositions of glucuronic acid (GlcA), N-acetylgalactosamine (GalNAc), fucose (Fuc) and sulfate were at similar molar ratio with 1.0/0.7/0.9/3.1 for fCS-Ib and 1.0/0.8/1.5/2.6 for fCS-Pg. The two fCSs have different sulfation patterns on their fucose branches, fCS-Pg with 3,4-O-disulfation while fCS-Ib with 2,4-O-disulfation. Their antihyperlipidemic effects were compared using a high-fat high-fructose diet (HFFD)-fed C57BL/6J mice model. Both fCS-Ib and fCS-Pg had significant effects on lipid profile improvement, liver protection, blood glucose diminution and hepatic glycogen synthesis. Specifically, fCS-Pg with 3,4-O-disulfation fucose branches was more effective in reduction of blood cholesterol (TC), low density lipoprotein (LDL) and atherogenic index (AI). Our results indicate that both fCSs, especially fCS-Pg, could be used as a potential anti-hyperlipidemic drug.

  17. Purity determination of amphotericin B, colistin sulfate and tobramycin sulfate in a hydrophilic suspension by HPLC.

    Science.gov (United States)

    Pfeifer, Corina; Fassauer, Georg; Gerecke, Hagen; Jira, Thomas; Remane, Yvonne; Frontini, Roberto; Byrne, Jonathan; Reinhardt, Robert

    2015-05-15

    A suspension comprising of the three antibiotic substances amphotericin B, colistin sulfate and tobramycin sulfate is often used in clinical practice for the selective decontamination of the digestive tract of patients in intensive care. Since no detailed procedures, specifications or stability data are available for manufacturing this suspension, there may be discrepancies regarding formulation and stability of suspensions prepared in different pharmacies. The aim of this work is to develop a standardized formulation and to determine its stability under defined storage conditions. This would help guarantee that all patients receive the same preparation, therefore ensuring similar efficacy and improved safety. The first step in this process is to develop the required analytical tools to measure the content and purity of the drug substances in this complex mixture. In this paper, the development and validation of these tools as well as the development of the drug suspension formulation is described. The formulation comprises of Ampho-Moronal(®)-Suspension (Dermapharm) and a buffered, preservated aqueous solution of colistin sulfate and tobramycin sulfate. Two simple, well established high-performance liquid chromatography (HPLC) methods in the European Pharmacopoeia (EP) for impurity profiling of the two active ingredients amphotericin B and colistin sulfate were combined with a newly developed sample extraction procedure for the suspension. Sufficient selectivity and stability-indicating power have been demonstrated. Additionally, a new robust routine method was developed to determine possible degradation products of tobramycin sulfate in the investigated suspension. The specificity, precision, accuracy and linearity of the analytical procedures were demonstrated. The recovery rate was in the range of 90-110%. The precision results for the calculated impurities showed variation coefficients of <10%. The calibration curves were found to be linear with correlation

  18. The preparation and antioxidant activity of glucosamine sulfate

    Science.gov (United States)

    Xing, Ronge; Liu, Song; Wang, Lin; Cai, Shengbao; Yu, Huahua; Feng, Jinhua; Li, Pengcheng

    2009-05-01

    Glucosamine sulfate was prepared from glucosamine hydrochloride that was produced by acidic hydrolysis of chitin by ion-exchange method. Optical rotation and elemental analysis characterized the degree of its purity. In addition, the antioxidant potency of chitosan derivative-glucosamine sulfate was investigated in various established in vitro systems, such as superoxide (O{2/-})/hydroxyl (·OH) radicals scavenging, reducing power, iron ion chelating. The following results are obtained: first, glucosamine sulfate had pronounced scavenging effect on superoxide radical. For example the O{2/-} scavenging activity of glucosamine sulfate was 92.11% at 0.8 mg/mL. Second, the ·OH scavenging activity of glucosamine sulfate was also strong, and was about 50% at 3.2 mg/mL. Third, the reducing power of glucosamine sulfate was more pronounced. The reducing power of glucosamine sulfate was 0.643 at 0.75 mg/mL. However, its potency for ferrous ion chelating was weak. Furthermore, except for ferrous ion chelating potency, the scavenging rate of radical and reducing power of glucosamine sulfate were concentration-dependent and increased with their increasing concentrations, but its ferrous ion chelating potency decreased with the increasing concentration. The multiple antioxidant activities of glucosamine sulfate were evidents of reducing power and superoxide/hydroxyl radicals scavenging ability. These in vitro results suggest the possibility that glucosamine sulfate could be used effectively as an ingredient in health or functional food, to alleviate oxidative stress.

  19. The preparation and antioxidant activity of glucosamine sulfate

    Institute of Scientific and Technical Information of China (English)

    XING Ronge; LIU Song; WANG Lin; CAI Shengbao; YU Huahua; FENG Jinhua; LI Pengcheng

    2009-01-01

    Glucosamine sulfate was prepared from glucosamine hydrochloride that was produced by acidic hydrolysis of chitin by ion-exchange method. Optical rotation and elemental analysis characterized the degree of its purity. In addition, the antioxidant potency of chitosan derivative-glucosamine sulfate was investigated in various established in vitro systems, such as superoxide (O(2))/hydroxyl (·OH) radicals scavenging, reducing power, iron ion chelating. The following results are obtained: first, glucosamine sulfate had pronounced scavenging effect on superoxide radical. For example the O(2) scavenging activity of glucosamine sulfate was 92.11% at 0.8 mg/mL. Second, the ·OH scavenging activity of glucosamine sulfate was also strong, and was about 50% at 3.2 mg/mL Third, the reducing power of glucosamine sulfate was more pronounced. The reducing power of glucosamine sulfate was 0.643 at 0.75 mg/mL.However, its potency for ferrous ion chelating was weak. Furthermore, except for ferrous ion chelating potency, the scavenging rate of radical and reducing power of glucosamine sulfate were concentration-dependent and increased with their increasing concentrations, but its ferrous ion chelating potency decreased with the increasing concentration. The multiple antioxidant activities of glucosamine sulfate were evidents of reducing power and superoxide/hydroxyl radicals scavenging ability. These in vitro results suggest the possibility that glucosamine sulfate could be used effectively as an ingredient in health or functional food, to alleviate oxidative stress.

  20. Inactivation of thrombin by a fucosylated chondroitin sulfate from echinoderm.

    Science.gov (United States)

    Mourão, P A; Boisson-Vidal, C; Tapon-Bretaudière, J; Drouet, B; Bros, A; Fischer, A

    2001-04-15

    A polysaccharide extracted from the sea cucumber body wall has the same backbone structure as the mammalian chondroitin sulfate, but some of the glucuronic acid residues display sulfated fucose branches. These branches confer high anticoagulant activity to the polysaccharide. Since the sea cucumber chondroitin sulfate has analogy in structure with mammalian glycosaminoglycans and sulfated fucans from brown algae, we compared its anticoagulant action with that of heparin and of a homopolymeric sulfated fucan with approximately the same level of sulfation as the sulfated fucose branches found in the sea cucumber polysaccharide. These various compounds differ not only in their anticoagulant potencies but also in the mechanisms of thrombin inhibition. Fucosylated chondroitin sulfate, like heparin, requires antithrombin or heparin cofactor II for thrombin inhibition. Sulfated fucans from brown algae have an antithrombin effect mediated by antithrombin and heparin cofactor II, plus a direct antithrombin effect more pronounced for some fractions. But even in the case of these two polysaccharides, we observed some differences. In contrast with heparin, total inhibition of thrombin in the presence of antithrombin is not achieved with fucosylated chondroitin sulfate, possibly reflecting a less specific interaction. Fucosylated chondroitin sulfate is able to inhibit thrombin generation after stimulation by both contact-activated and thromboplastin-activated systems. It delayed only the contact-induced thrombin generation, as expected for an anticoagulant without direct thrombin inhibition. Overall, the specific spatial array of the sulfated fucose branches in the fucosylated chondroitin sulfate not only confer high anticoagulant activity to the polysaccharide but also determine differences in the way it inhibits thrombin.

  1. Mitochondrial calcium uptake.

    Science.gov (United States)

    Williams, George S B; Boyman, Liron; Chikando, Aristide C; Khairallah, Ramzi J; Lederer, W J

    2013-06-25

    Calcium (Ca(2+)) uptake into the mitochondrial matrix is critically important to cellular function. As a regulator of matrix Ca(2+) levels, this flux influences energy production and can initiate cell death. If large, this flux could potentially alter intracellular Ca(2+) ([Ca(2+)]i) signals. Despite years of study, fundamental disagreements on the extent and speed of mitochondrial Ca(2+) uptake still exist. Here, we review and quantitatively analyze mitochondrial Ca(2+) uptake fluxes from different tissues and interpret the results with respect to the recently proposed mitochondrial Ca(2+) uniporter (MCU) candidate. This quantitative analysis yields four clear results: (i) under physiological conditions, Ca(2+) influx into the mitochondria via the MCU is small relative to other cytosolic Ca(2+) extrusion pathways; (ii) single MCU conductance is ∼6-7 pS (105 mM [Ca(2+)]), and MCU flux appears to be modulated by [Ca(2+)]i, suggesting Ca(2+) regulation of MCU open probability (P(O)); (iii) in the heart, two features are clear: the number of MCU channels per mitochondrion can be calculated, and MCU probability is low under normal conditions; and (iv) in skeletal muscle and liver cells, uptake per mitochondrion varies in magnitude but total uptake per cell still appears to be modest. Based on our analysis of available quantitative data, we conclude that although Ca(2+) critically regulates mitochondrial function, the mitochondria do not act as a significant dynamic buffer of cytosolic Ca(2+) under physiological conditions. Nevertheless, with prolonged (superphysiological) elevations of [Ca(2+)]i, mitochondrial Ca(2+) uptake can increase 10- to 1,000-fold and begin to shape [Ca(2+)]i dynamics.

  2. Lacrimal gland development and Fgf10-Fgfr2b signaling are controlled by 2-O- and 6-O-sulfated heparan sulfate

    NARCIS (Netherlands)

    Qu, X.; Carbe, C.; Tao, C.; Powers, A.; Lawrence, R.; Kuppevelt, A.H.M.S.M. van; Cardoso, W.V.; Grobe, K.; Esko, J.D.; Zhang, X.

    2011-01-01

    Heparan sulfate, an extensively sulfated glycosaminoglycan abundant on cell surface proteoglycans, regulates intercellular signaling through its binding to various growth factors and receptors. In the lacrimal gland, branching morphogenesis depends on the interaction of heparan sulfate with Fgf10-Fg

  3. Reversible block of the calcium release channel/ryanodine receptor by protamine, a heparin antidote.

    Science.gov (United States)

    Koulen, P; Ehrlich, B E

    2000-07-01

    Channel activity of the calcium release channel from skeletal muscle, ryanodine receptor type 1, was measured in the presence and absence of protamine sulfate on the cytoplasmic side of the channel. Single-channel activity was measured after incorporating channels into planar lipid bilayers. Optimally and suboptimally calcium-activated calcium release channels were inactivated by the application of protamine to the cytoplasmic side of the channel. Recovery of channel activity was not observed while protamine was present. The addition of protamine bound to agarose beads did not change channel activity, implying that the mechanism of action involves an interaction with the ryanodine receptor rather than changes in the bulk calcium concentration of the medium. The block of channel activity by protamine could be reversed either by removal by perfusion with buffer or by the addition of heparin to the cytoplasmic side of the channel. Microinjection of protamine into differentiated C(2)C(12) mouse muscle cells prevented caffeine-induced intracellular calcium release. The results suggest that protamine acts on the ryanodine receptor in a similar but opposite manner from heparin and that protamine can be used as a potent, reversible inhibitor of ryanodine receptor activity.

  4. Dopaminergic regulation of dendritic calcium: fast multisite calcium imaging.

    Science.gov (United States)

    Zhou, Wen-Liang; Oikonomou, Katerina D; Short, Shaina M; Antic, Srdjan D

    2013-01-01

    Optimal dopamine tone is required for the normal cortical function; however it is still unclear how cortical-dopamine-release affects information processing in individual cortical neurons. Thousands of glutamatergic inputs impinge onto elaborate dendritic trees of neocortical pyramidal neurons. In the process of ensuing synaptic integration (information processing), a variety of calcium transients are generated in remote dendritic compartments. In order to understand the cellular mechanisms of dopaminergic modulation it is important to know whether and how dopaminergic signals affect dendritic calcium transients. In this chapter, we describe a relatively inexpensive method for monitoring dendritic calcium fluctuations at multiple loci across the pyramidal dendritic tree, at the same moment of time (simultaneously). The experiments have been designed to measure the amplitude, time course and spatial extent of action potential-associated dendritic calcium transients before and after application of dopaminergic drugs. In the examples provided here the dendritic calcium transients were evoked by triggering the somatic action potentials (backpropagation-evoked), and puffs of exogenous dopamine were applied locally onto selected dendritic branches.

  5. Formation of calcium complexes by borogluconate in vitro and during calcium borogluconate infusion in sheep.

    Science.gov (United States)

    Farningham, D A

    1985-07-01

    The effect of borogluconate on plasma calcium fractions was studied in vitro and in vivo in sheep. In vitro calcium chloride was more effective in raising ionised plasma calcium than calcium borogluconate. Sodium borate or gluconate added to blood caused only small decreases in blood ionised calcium. However, together, a synergistic reduction in ionised calcium was observed. Following calcium borogluconate infusions into sheep, total plasma calcium rose primarily because of an increase in the unionised ultrafiltrable fraction. Other changes observed following the infusion were hypercalciuria, decreased glomerular filtration rate and acidosis. Sodium borogluconate administered subcutaneously lowered total plasma calcium. This probably resulted from enhanced calcium excretion. It is suggested that since the anionic component of calcium solutions alters the availability and retention of calcium, it is likely to affect clinical efficacy significantly.

  6. Utilization of sulfate additives in biomass combustion: fundamental and modeling aspects

    DEFF Research Database (Denmark)

    Wu, Hao; Jespersen, Jacob Boll; Grell, Morten Nedergaard;

    2013-01-01

    Sulfates, such as ammonium sulfate, aluminum sulfate and ferric sulfate, are effective additives for converting the alkali chlorides released from biomass combustion to the less harmful alkali sulfates. Optimization of the use of these additives requires knowledge on their decomposition rate...... and product distribution under high temperature conditions. In the present work, the decomposition of ammonium sulfate, aluminum sulfate and ferric sulfate was studied respectively in a fast-heating rate thermogravimetric analyzer for deriving a kinetic model to describe the process. The yields of SO2 and SO3...... of different sulfates indicated that ammonium sulfate has clearly strongest sulfation power towards KCl at temperatures below 800oC, whereas the sulfation power of ferric and aluminum sulfates exceeds clearly that of ammonium sulfate between 900 and 1000oC. However, feeding gaseous SO3 was found to be most...

  7. [Calcium metabolism characteristics in microgravity].

    Science.gov (United States)

    Grigor'ev, A I; Larina, I M; Morukov, B V

    1999-06-01

    The results of research of calcium exchange parameters at cosmonauts taken part in long space flights (SF) onboard of orbital stations "SALUT" and "MIR" within 1978-1998 were generalized. The analysis of data received during observation of 44 cosmonauts (18 of them have taken part in long SF twice) was done. The observation was carried out before and after SF by duration 30-438 days. The content of a total calcium in blood serum was increased basically by the increase of its ionized fraction after flights of moderate (3-6 months) and large duration (6-14 months) along with the significant increase of PTH and decrease of calcitonin levels. The content of osteocalcin after SF was increased. Three cosmonauts participated in research of calcium kinetics using stable isotopes before, in time and after a 115-day SF. Reduction of intestinal absorption, excretion through a gastrointestinal tract, and increase of calcium excretion with urine were marked in time of SF. In early postflight period a level of intestinal absorption, on the average, was much lower than in SF, and the calcium removal through intestine was increased. Both renal and intestinal excretion of calcium were not normalized in 3.5-4.5 months after end of SF. Increase of resorbtive processes in bone tissues which induced negative bone balance during flight was observed in all test subjects, proceeding from estimations of speed of the basic calcium flows made on the basis of mathematical modeling. The conclusion about decrease in speed of bone tissue remodeling and strengthening of its resorption proves to be true by data of research of biochemical and endocrine markers.

  8. Calcium wave of tubuloglomerular feedback.

    Science.gov (United States)

    Peti-Peterdi, János

    2006-08-01

    ATP release from macula densa (MD) cells into the interstitium of the juxtaglomerular (JG) apparatus (JGA) is an integral component of the tubuloglomerular feedback (TGF) mechanism that controls the glomerular filtration rate. Because the cells of the JGA express a number of calcium-coupled purinergic receptors, these studies tested the hypothesis that TGF activation triggers a calcium wave that spreads from the MD toward distant cells of the JGA and glomerulus. Ratiometric calcium imaging of in vitro microperfused isolated JGA-glomerulus complex dissected from rabbits was performed with fluo-4/fura red and confocal fluorescence microscopy. Activation of TGF by increasing tubular flow rate at the MD rapidly produced a significant elevation in intracellular Ca(2+) concentration ([Ca(2+)](i)) in extraglomerular mesangial cells (by 187.6 +/- 45.1 nM) and JG renin granular cells (by 281.4 +/- 66.6 nM). Subsequently, cell-to-cell propagation of the calcium signal at a rate of 12.6 +/- 1.1 microm/s was observed upstream toward proximal segments of the afferent arteriole and adjacent glomeruli, as well as toward intraglomerular elements including the most distant podocytes (5.9 +/- 0.4 microm/s). The same calcium wave was observed in nonperfusing glomeruli, causing vasoconstriction and contractions of the glomerular tuft. Gap junction uncoupling, an ATP scavenger enzyme cocktail, and pharmacological inhibition of P(2) purinergic receptors, but not adenosine A(1) receptor blockade, abolished the changes in [Ca(2+)](i) and propagation of the calcium wave. These studies provided evidence that both gap junctional communication and extracellular ATP are integral components of the TGF calcium wave.

  9. Structural characterization of anion-calcium-humate complexes in phosphate-based fertilizers.

    Science.gov (United States)

    Baigorri, Roberto; Urrutia, Oscar; Erro, Javier; Mandado, Marcos; Pérez-Juste, Ignacio; Garcia-Mina, José María

    2013-07-01

    Fertilizers based on phosphate-metal-humate complexes are a new family of compounds that represents a more sustainable and bioavailable phosphorus source. The characterization of this type of complex by using solid (31)P NMR in several fertilizers, based on single superphosphate (SSP) and triple superphosphate (TSP) matrices, yielded surprising and unexpected trends in the intensity and fine structure of the (31)P NMR peaks. Computational chemistry methods allowed the characterization of phosphate-calcium-humate complexes in both SSP and TSP matrices, but also predicted the formation of a stable sulfate-calcium-humate complex in the SSP fertilizers, which has not been described previously. The stability of this complex has been confirmed by using ultrafiltration techniques. Preference towards the humic substance for the sulfate-metal phase in SSP allowed the explanation of the opposing trends that were observed in the experimental (31)P NMR spectra of SSP and TSP samples. Additionally, computational chemistry has provided an assignment of the (31)P NMR signals to different phosphate ligands as well as valuable information about the relative strength of the phosphate-calcium interactions within the crystals.

  10. Effects of sulfate deprivation on the production of chondroitin/dermatan sulfate by cultures of skin fibroblasts from normal and diabetic individuals

    Energy Technology Data Exchange (ETDEWEB)

    Silbert, C.K.; Humphries, D.E.; Palmer, M.E.; Silbert, J.E. (Veterans Administration Outpatient Clinic, Boston, MA (USA))

    1991-02-15

    Human skin fibroblast monolayer cultures from two normal men, three Type I diabetic men, and one Type I diabetic woman were incubated with (3H)glucosamine in the presence of diminished concentrations of sulfate. Although total synthesis of (3H)chondroitin/dermatan glycosaminoglycans varied somewhat between cell lines, glycosaminoglycan production was not affected within any line when sulfate levels were decreased from 0.3 mM to 0.06 mM to 0.01 mM to 0 added sulfate. Lowering of sulfate concentrations resulted in diminished sulfation of chondroitin/dermatan in a progressive manner, so that overall sulfation dropped to as low as 19% for one of the lines. Sulfation of chondroitin to form chondroitin 4-sulfate and chondroitin 6-sulfate was progressively and equally affected by decreasing the sulfate concentration in the culture medium. However, sulfation to form dermatan sulfate was preserved to a greater degree, so that the relative proportion of dermatan sulfate to chondroitin sulfate increased. Essentially all the nonsulfated residues were susceptible to chondroitin AC lyase, indicating that little epimerization of glucuronic acid residues to iduronic acid had occurred in the absence of sulfation. These results confirm the previously described dependency of glucuronic/iduronic epimerization on sulfation, and indicate that sulfation of the iduronic acid-containing disaccharide residues of dermatan can take place with sulfate concentrations lower than those needed for 6-sulfation and 4-sulfation of the glucuronic acid-containing disaccharide residues of chondroitin. There were considerable differences among the six fibroblast lines in susceptibility to low sulfate medium and in the proportion of chondroitin 6-sulfate, chondroitin 4-sulfate, and dermatan sulfate. However, there was no pattern of differences between normals and diabetics.

  11. Reaction of calcium-based sorbents with sulfur componds during gasification. Annual report, October 1, 1986-September 30, 1987

    Energy Technology Data Exchange (ETDEWEB)

    Rehmat, A.; Abbasian, M.J.

    1988-01-01

    This report outlines the objectives and the data obtained under the project related to the efficient utilization of high-sulfur Illinois coal in a One-Step Coal Gasification/Desulfurization Process by employing in-situ removal of sulfur using calcium-based sorbents. The scope of the research included a study of fluidization behavior of coal char/sorbent mixtures and the reactions of calcium-based sorbents with sulfur present in the coal during gasification. Tests were conducted in bench-scale units; an 8-inch (0.2 meter) fluidization column was utilized for fluidization tests, and a thermobalance reactor was used for gas/solid sulfidation and sulfation reactions. The test parameters included the choice of sorbent, sorbent size, the effect of temperature on the sulfidation and sulfation reactions, the effect of the steam-to-hydrogen sulfide ratio on the sulfidation reaction, the effect of the steam on the sulfation reaction, and the influence of exposure time on sulfation of the presulfided sorbent. The reaction conditions for these reactions were chosen to be applicable to scale-up of an in-situ desulfurization-type coal gasification process such as the one proposed by the Institute of Gas Technology (IGT) and KRW Energy Systems, Inc., of the USA.

  12. Testing Silica Fume-Based Concrete Composites under Chemical and Microbiological Sulfate Attacks

    Directory of Open Access Journals (Sweden)

    Adriana Estokova

    2016-04-01

    Full Text Available Current design practices based on descriptive approaches to concrete specification may not be appropriate for the management of aggressive environments. In this study, the durability of cement-based materials with and without the addition of silica fume, subjected to conditions that leach calcium and silicon, were investigated. Chemical corrosion was simulated by employing various H2SO4 and MgSO4 solutions, and biological corrosion was simulated using Acidithiobacillus sp. bacterial inoculation, leading to disrupted and damaged surfaces; the samples’ mass changes were studied following both chemical and biological attacks. Different leaching trends were observed via X-ray fluorescence when comparing chemical with biological leaching. Lower leaching rates were found for concrete samples fortified with silica fume than those without silica fume. X-ray diffraction and scanning electron microscopy confirmed a massive sulfate precipitate formation on the concrete surface due to bacterial exposure.

  13. Sulfated fucan as support for antibiotic immobilization.

    Science.gov (United States)

    Araújo, P M; Oliveira, G B; Córdula, C R; Leite, E L; Carvalho Jr, L B; Silva, M P C

    2004-03-01

    Xylofucoglucuronan from Spatoglossum schröederi algae was tested as a support for antibiotic immobilization. The polysaccharide (20 mg in 6 ml) was first activated using carbodiimide, 1-ethyl-3-(3-dimethylamino-propyl)carbodiimide methiodide (20 mg in 2 ml), under stirring for 1 h at 25 masculine C and pH from 4.5 to 5.0. After adjusting the pH to 8.0, either gentamicin or amikacin (62.5 mg in 1.25 ml) was then immobilized on this chemically modified polysaccharide with shaking for 24 h in a cold room. Infrared spectra of the activated carbodiimide xylofucoglucuronan showed two bands to carbonyl (C=O at 1647.9 and 1700.7 cm(-1)) and to amide (C-NH2) groups (1662.8 and 1714.0 cm(-1)). Microbial characterization of the derivatives was carried out by the disk diffusion method using Staphylococcus aureus or Klebsiella pneumoniae incorporated in Müller Hinton medium. Inhibition halos of bacterial growth were observed for the antibiotics immobilized on this sulfated heteropolysaccharide before and after dialysis. However, the halos resulting from the samples after dialysis were much smaller, suggesting that dialysis removed either non-covalently bound antibiotic or other small molecules. In contrast, bacterial growth was not inhibited by either xylofucoglucuronan or its activated form or by gentamicin or amikacin after dialysis. An additional experiment was carried out which demonstrated that the sulfated heteropolysaccharide was hydrolyzed by the microorganism. Therefore, the antibiotic immobilized on xylofucoglucuronan can be proposed as a controlled drug delivery system. Furthermore, this sulfated heteropolysaccharide can be extracted easily from sea algae Spatoglossum schröederi.

  14. Sulfated fucan as support for antibiotic immobilization

    Directory of Open Access Journals (Sweden)

    Araújo P.M.

    2004-01-01

    Full Text Available Xylofucoglucuronan from Spatoglossum schröederi algae was tested as a support for antibiotic immobilization. The polysaccharide (20 mg in 6 ml was first activated using carbodiimide, 1-ethyl-3-(3-dimethylamino-propylcarbodiimide methiodide (20 mg in 2 ml, under stirring for 1 h at 25ºC and pH from 4.5 to 5.0. After adjusting the pH to 8.0, either gentamicin or amikacin (62.5 mg in 1.25 ml was then immobilized on this chemically modified polysaccharide with shaking for 24 h in a cold room. Infrared spectra of the activated carbodiimide xylofucoglucuronan showed two bands to carbonyl (C = O at 1647.9 and 1700.7 cm-1 and to amide (CÝ-NH2 groups (1662.8 and 1714.0 cm-1. Microbial characterization of the derivatives was carried out by the disk diffusion method using Staphylococcus aureus or Klebsiella pneumoniae incorporated in Müller Hinton medium. Inhibition halos of bacterial growth were observed for the antibiotics immobilized on this sulfated heteropolysaccharide before and after dialysis. However, the halos resulting from the samples after dialysis were much smaller, suggesting that dialysis removed either non-covalently bound antibiotic or other small molecules. In contrast, bacterial growth was not inhibited by either xylofucoglucuronan or its activated form or by gentamicin or amikacin after dialysis. An additional experiment was carried out which demonstrated that the sulfated heteropolysaccharide was hydrolyzed by the microorganism. Therefore, the antibiotic immobilized on xylofucoglucuronan can be proposed as a controlled drug delivery system. Furthermore, this sulfated heteropolysaccharide can be extracted easily from sea algae Spatoglossum schröederi.

  15. Calcium supplement: humanity's double-edged sword.

    Science.gov (United States)

    Bunyaratavej, Narong; Buranasinsup, Shutipen

    2011-10-01

    The principle aim of the present study is to investigate the dark side of calcium, pollutions in calcium preparation especially lead (Pb), mercury (Hg) and cadmium (Cd). The collected samples were the different calcium salts in the market and 18 preparations which were classified into 3 groups: Calcium carbonate salts, Chelated calcium and natural-raw calcium. All samples were analyzed for lead, cadmium and mercury by inductively Coupled Plasma Mass Spectrometry (ICP-MS) technique, in house method based on AOAC (2005) 999.10 by ICP-MS. The calcium carbonate and the natural-raw calcium in every sample contained lead at 0.023-0.407 mg/kg of calcium powder. Meanwhile, the natural-raw calcium such as oyster, coral and animal bone showed amount of lead at 0.106-0.384 mg/kg with small amounts of mercury and cadmium. The chelated calcium such as calcium gluconate, calcium lactate and calcium citrate are free of lead.

  16. Synthesis and characterization of novel cellulose ether sulfates.

    Science.gov (United States)

    Rohowsky, Juta; Heise, Katja; Fischer, Steffen; Hettrich, Kay

    2016-05-20

    The synthesis and characterization of novel cellulose sulfate derivatives was reported. Various cellulose ethers were prepared in a homogeneous reaction with common sulfating agents. The received product possess different properties in dependence on the reaction conditions like sulfating agent, solvent, reaction time and reaction temperature. The cellulose ether sulfates are all soluble in water, they rheological behavior could be determined by viscosity measurements and the determination of the sulfur content by elemental analysis lead to a resulting degree of substitution ascribed to sulfate groups (DSSul) of the product. A wide range of products from DSSul 0.1 to DSSul 2.7 will be obtained. Furthermore the cellulose sulfate ethers could be characterized by Raman spectroscopy.

  17. Chemical leukoderma induced by dimethyl sulfate*

    Science.gov (United States)

    Gozali, Maya Valeska; Zhang, Jia-an; Yi, Fei; Zhou, Bing-rong; Luo, Dan

    2016-01-01

    Chemical leukoderma occurs due to the toxic effect of a variety of chemical agents. Mechanisms include either destruction or inhibition of melanocytes. We report two male patients (36 and 51 years old) who presented with multiple hypopigmented macules and patches on the neck, wrist, and legs after exposure to dimethyl sulfate in a chemical industry. Physical examination revealed irregular depigmentation macules with sharp edges and clear hyperpigmentation around the lesions. History of repeated exposure to a chemical agent can help the clinical diagnosis of chemical leukoderma. This diagnosis is very important for prognosis and therapeutic management of the disease.

  18. New Bioactive Alkyl Sulfates from Mediterranean Tunicates

    Directory of Open Access Journals (Sweden)

    Marialuisa Menna

    2012-10-01

    Full Text Available Chemical investigation of two species of marine ascidians, Aplidium elegans and Ciona edwardsii, collected in Mediterranean area, led to isolation of a series of alkyl sulfates (compounds 1–5 including three new molecules 1–3. Structures of the new metabolites have been elucidated by spectroscopic analysis. Based on previously reported cytotoxic activity of these type of molecules, compounds 1–3 have been tested for their effects on the growth of two cell lines, J774A.1 (BALB/c murine macrophages and C6 (rat glioma in vitro. Compounds 1 and 2 induced selective concentration-dependent mortality on J774A.1 cells.

  19. Effect of chondroitin sulfate on osteogenetic differentiation of human mesenchymal stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Schneiders, Wolfgang, E-mail: schneidersw@gmx.de; Rentsch, Claudia; Rehberg, Sebastian; Rein, Susanne; Zwipp, Hans; Rammelt, Stefan

    2012-10-01

    Chondroitin sulfate (CS) has anti-inflammatory properties and increases the regeneration ability of injured bone. In different in vivo investigations on bone defects the addition of CS to calcium phosphate bone cement has lead to an enhanced bone remodeling and increased new bone formation. The goal of this study was to evaluate the cellular effects of CS on human mesenchymal stem cells (hMSCs). In cell culture experiments hMSCs were incubated on calcium phosphate bone cements with and without CS and cultivated in a proliferation and an osteogenetic differentiation media. Alkaline phosphatase and the proliferation rate were determined on days 1, 7 and 14. Concerning the proliferation rates, no significant differences were detected. On days 1, 7 and 14 a significantly higher activity of alkaline phosphatase, an early marker of osteogenesis, was detected around CS modified cements in both types of media. The addition of CS leads to a significant increase of osteogenetic differentiation of hMSCs. To evaluate the influence of the osteoconductive potency of CS in twelve adult male Wistar rats, the interface reaction of cancellous bone to a nanocrystalline hydroxyapatite cement containing type I collagen (CDHA/Coll) without and with CS (CDHA/Coll/CS) was evaluated. Cylindrical implants were inserted press-fit into a defect of the tibial head. 28 days after the operation the direct bone contact and the percentage of newly formed bone were significantly higher on CDHA/Coll/CS-implants (p < 0.05). The addition of CS appears to enhance new bone formation on CDHA/Coll-composites in the early stages of bone healing. Possible mechanisms are discussed. - Highlights: Black-Right-Pointing-Pointer The influence of chondroitin sulfate (CS) on bone metabolism was evaluated. Black-Right-Pointing-Pointer CS leads to a significant increase of osteogenetic differentiation of hMSCs. Black-Right-Pointing-Pointer In small animal investigation CS seems to enhance osteogenesis in bone healing.

  20. Sulfation patterns determine cellular internalization of heparin-like polysaccharides

    OpenAIRE

    Raman, Karthik; Mencio, Caitlin; Desai, Umesh R.; Kuberan, Balagurunathan

    2013-01-01

    Heparin is a highly sulfated polysaccharide which serves biologically relevant roles as an anticoagulant and anti-cancer agent. While it is well known that modification of heparin’s sulfation pattern can drastically influence its ability to bind growth factors and other extracellular molecules, very little is known about the cellular uptake of heparin and the role sulfation patterns serve in affecting its internalization. In this study, we chemically synthesized several fluorescently-labeled ...

  1. Glycosaminoglycan modifications in Duchenne muscular dystrophy: specific remodeling of chondroitin sulfate/dermatan sulfate.

    Science.gov (United States)

    Negroni, Elisa; Henault, Emilie; Chevalier, Fabien; Gilbert-Sirieix, Marie; Van Kuppevelt, Toin H; Papy-Garcia, Dulce; Uzan, Georges; Albanese, Patricia

    2014-08-01

    Widespread skeletal muscle degeneration and impaired regeneration lead to progressive muscle weakness and premature death in patients with Duchenne muscular dystrophy (DMD). Dystrophic muscles are progressively replaced by nonfunctional tissue because of exhaustion of muscle precursor cells and excessive accumulation of extracellular matrix (ECM). Sulfated glycosaminoglycans (GAGs) are components of the ECM and are increasingly implicated in the regulation of biologic processes, but their possible role in the progression of DMD pathology is not understood. In the present study, we performed immunohistochemical and biochemical analyses of endogenous GAGs in skeletal muscle biopsies of 10 DMD patients and 11 healthy individuals (controls). Immunostaining targeted to specific GAG species showed greater deposition of chondroitin sulfate (CS)/dermatan (DS) sulfate in DMD patient biopsies versus control biopsies. The selective accumulation of CS/DS in DMD biopsies was confirmed by biochemical quantification assay. In addition, high-performance liquid chromatography analysis demonstrated a modification of the sulfation pattern of CS/DS disaccharide units in DMD muscles. In conclusion, our data open up a new path of investigation and suggest that GAGs could represent a new and original therapeutic target for improving the success of gene or cell therapy for the treatment of muscular dystrophies.

  2. Modeling of sulfation of potassium chloride by ferric sulfate addition during grate-firing of biomass

    DEFF Research Database (Denmark)

    Wu, Hao; Jespersen, Jacob Boll; Aho, Martti;

    2013-01-01

    Potassium chloride, KCl, formed from critical ash-forming elements released during combustion may lead to severe ash deposition and corrosion problems in biomass-fired boilers. Ferric sulfate, Fe2(SO4)3 is an effective additive, which produces sulfur oxides (SO2 and SO3) to convert KCl to the les...

  3. Inter vs. intraglycosidic acetal linkages control sulfation pattern in semi-synthetic chondroitin sulfate.

    Science.gov (United States)

    Laezza, Antonio; De Castro, Cristina; Parrilli, Michelangelo; Bedini, Emiliano

    2014-11-04

    Microbial-sourced unsulfated chondroitin could be converted into chondroitin sulfate (CS) polysaccharide by a multi-step strategy relying upon benzylidenation and acetylation reactions as key-steps for its regioselective protection. By conducting the two reactions one- or two-pots, CSs with different sulfation patterns could be obtained at the end of the semi-synthesis. In particular, a CS polysaccharide possessing sulfate groups randomly distributed between positions 4 and 6 of N-acetyl-galactosamine (GalNAc) units could be obtained through the two-pots route, whereas the one-pot pathway allowed an additional sulfation at position 3 of some glucuronic acid (GlcA) units. This difference was ascribed to the stabilization of a labile interglycosidic benzylidene acetal involving positions O-3 and O-6 of some GlcA and GalNAc, respectively, when the benzylidene-acetylation reactions were conducted in a one-pot fashion. Isolation and characterization of a polysaccharide intermediate showing interglycosidic acetal moieties was accomplished.

  4. Cloud water chemistry and the production of sulfates in clouds

    Science.gov (United States)

    Hegg, D. A.; Hobbs, P. V.

    1981-01-01

    Measurements are presented of the pH and ionic content of water collected in clouds over western Washington and the Los Angeles Basin. Evidence for sulfate production in some of the clouds is presented. Not all of the sulfur in the cloud water was in the form of sulfate. However, the measurements indicate that the production of sulfate in clouds is of considerable significance in the atmosphere. Comparison of field measurements with model results show reasonable agreement and suggest that the production of sulfate in cloud water is a consequence of more than one conversion mechanism.

  5. An Instrument to Measure Aircraft Sulfate Particle Emissions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aerodyne is developing a sulfate detection instrument, based on the Tunable Infrared Laser Differential Absorption Spectrophotometer (TILDAS) technology and...

  6. REFINEMENT OF THE CRYSTAL STRUCTURE OF GUANIDINIUM ALUMINUM SULFATE HEXAHYDRATE.

    Science.gov (United States)

    FERROELECTRIC CRYSTALS, * CRYSTAL STRUCTURE ), (*GUANIDINES, CRYSTAL STRUCTURE ), (*ALUMINUM COMPOUNDS, CRYSTAL STRUCTURE ), SULFATES, HYDRATES, X RAY DIFFRACTION, CHROMIUM COMPOUNDS, CRYSTAL LATTICES, CHEMICAL BONDS

  7. Basement membrane chondroitin sulfate proteoglycans: localization in adult rat tissues

    DEFF Research Database (Denmark)

    McCarthy, K J; Couchman, J R

    1990-01-01

    Heparan sulfate proteoglycans have been described as the major proteoglycan component of basement membranes. However, previous investigators have also provided evidence for the presence of chondroitin sulfate glycosaminoglycan in these structures. Recently we described the production...... and characterization of core protein-specific monoclonal antibodies (MAb) against a chondroitin sulfate proteoglycan (CSPG) present in Reichert's membrane, a transient extra-embryonic structure of rodents. This CSPG was also demonstrated to be present in adult rat kidney. We report here the tissue distribution...... sulfate proteoglycans previously described....

  8. Sulfate Reduction in Groundwater: Characterization and Applications for Remediation

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Z.; Brusseau, M. L.; Carroll, Kenneth C.; Carreon-Diazconti, C.; Johnson, B.

    2012-06-01

    Sulfate is ubiquitous in groundwater, with both natural and anthropogenic sources. Sulfate reduction reactions play a significant role in mediating redox conditions and biogeochemical processes for subsurface systems. They also serve as the basis for innovative in-situ methods for groundwater remediation. An overview of sulfate reduction in subsurface environments is provided, with a specific focus on implications for groundwater remediation. A case study presenting the results of a pilot-scale ethanol injection test illustrates the advantages and difficulties associated with the use of electron-donor amendments for sulfate remediation.

  9. The "in and out" of glucosamine 6-O-sulfation: the 6th sense of heparan sulfate.

    Science.gov (United States)

    El Masri, Rana; Seffouh, Amal; Lortat-Jacob, Hugues; Vivès, Romain R

    2016-11-03

    The biological properties of Heparan sulfate (HS) polysaccharides essentially rely on their ability to bind and modulate a multitude of protein ligands. These interactions involve internal oligosaccharide sequences defined by their sulfation patterns. Amongst these, the 6-O-sulfation of HS contributes significantly to the polysaccharide structural diversity and is critically involved in the binding of many proteins. HS 6-O-sulfation is catalyzed by 6-O-sulfotransferases (6OSTs) during biosynthesis, and it is further modified by the post-synthetic action of 6-O-endosulfatases (Sulfs), two enzyme families that remain poorly characterized. The aim of the present review is to summarize the contribution of 6-O-sulfates in HS structure/function relationships and to discuss the present knowledge on the complex mechanisms regulating HS 6-O-sulfation.

  10. Papillomavirus microbicidal activities of high-molecular-weight cellulose sulfate, dextran sulfate, and polystyrene sulfonate.

    Science.gov (United States)

    Christensen, N D; Reed, C A; Culp, T D; Hermonat, P L; Howett, M K; Anderson, R A; Zaneveld, L J

    2001-12-01

    The high-molecular-weight sulfated or sulfonated polysaccharides or polymers cellulose sulfate, dextran sulfate, and polystyrene sulfonate were tested for microbicidal activity against bovine papillomavirus type 1 (BPV-1) and human papillomavirus type 11 (HPV-11) and type 40 (HPV-40). In vitro assays included the BPV-1-induced focus-forming assay and transient infection of human A431 cells with HPVs. The compounds were tested for microbicidal activity directly by preincubation with virus prior to addition to cell cultures and indirectly by addition of virus to compound-treated cells and to virus-coated cells to test inactivation of the virus after virus-cell binding. The data indicated that all three compounds showed direct microbicidal activity with 50% effective concentrations between 10 to 100 microg/ml. These concentrations were nontoxic to cell cultures for both assays. When a clone of C127 cells was tested for microbicidal activity, approximately 10-fold-less compound was required to achieve a 50% reduction in BPV-1-induced foci than for the uncloned parental C127 cells. Pretreatment of cells with compound prior to addition of virus also demonstrated strong microbicidal activity with dextran sulfate and polystyrene sulfonate, but cellulose sulfate required several orders of magnitude more compound for virus inactivation. Polystyrene sulfonate prevented subsequent infection of HPV-11 after virus-cell binding, and this inactivation was observed up to 4 h after addition of virus. These data indicate that the polysulfated and polysulfonated compounds may be useful nontoxic microbicidal compounds that are active against a variety of sexually transmitted disease agents including papillomaviruses.

  11. Controls of Soluble Al in Experimental Acid Sulfate Conditions and Acid Sulfate Soils

    Institute of Scientific and Technical Information of China (English)

    LINCHUXIA; M.D.MELVILLE

    1997-01-01

    The controls of soluble Al concentration were examined in three situations of acid sulfate conditions:1) experimental acid sulfate conditions by addition of varying amounts of Al(OH)3(gibbsite) into a sequence of H2SO4 solutions;2)experimental acid sulfate conditions by addition of the same sequence of H2SO4 solutions into two non-cid sulfacte soil samples with known amounts of acid oxalate extractable Al; and 3) actual acid sulfate soil conditions.The experiment using gibbsite as an Al-bearing mineral showed that increase in the concentration of H2SO4 solution increased the soluble Al concentration,accompanied by a decrease i the solution pH, Increasing amount of gibbsite added to the H2SO4 solutions also increased soluble Al concentration,but resulted in an increase in solution pH.Within the H2SO4 concentration range of 0.0005-0.5mol L-1 and the Al(OH)3 range of 0.01-0.5g(in 25 mL of H2SO4 solutions),the input of H2SO4 had the major control on soluble Al Concentration and pH .The availability of Al(OH)3,however,was responsible for the spread fo the various sample points,with a tendency that the samples containing more gibbsite had a higher soluble Al concentration than those containing less gibbsite at equivalent pH levels.The experimental results from treatment of soil samples with H2SO4 solutions and the analytical results of acid sulfate soils also showed the similar trend.

  12. Diammonium tricadmium tris(sulfate dihydroxide dihydrate

    Directory of Open Access Journals (Sweden)

    Xin Yin

    2011-05-01

    Full Text Available The title compound, (NH42Cd3(SO43(OH2(H2O2, has been obtained serendipitously. It is isotypic with the heavier alkali analogues M2Cd3(SO43(OH2(H2O2 (M = K, Rb, Cs. The structure contains two Cd2+ ions, one in a general position and one with site symmetry m. The former Cd2+ ion is coordinated by three O atoms of three SO4 groups, two hydroxide O atoms and one water O atom, the latter Cd2+ ion by four O atoms of four SO4 groups and two hydroxide O atoms, both in a distorted octahedral coordination geometry. This arrangement leads to the formation of a layered framework extending parallel to (100, with the ammonium cations situated in the voids. O—H...O hydrogen bonds involving the water molecules, hydroxide groups and sulfate O atoms, as well as N—H...O hydrogen bonds between ammonium cations and sulfate O atoms consolidate the crystal packing.

  13. Synergistic Extraction of Gallium for Sulfate Solution

    Institute of Scientific and Technical Information of China (English)

    DENGTong; HUANGLijuan; 等

    2002-01-01

    A novel extractant mixture, di-2-ethylhexyl phosphate (DEHPA) plus HX, was propose and tested for recovering gallium from sulfate solution.It was found that the extraction capacity of DEPHA for gallium from sulfate solution could be enhanced significantly due to the synergistic effect of acidix extractant HX. Gallium extraction is negligible below pH 0 and highly sensitive to pH of aqueous phase in the range from 0 to 1, and satisfactory extraction can be gained at pH>1. More than 96% Ga extraction was obtained using 15% DEHPA plus 2% HX. Although Fe(Ⅲ) was found to be extracted preferentially to Ga (Ⅲ), effective extraction of Ga (Ⅲ) was possible by reducing ferric to the ferrous state prior to extraction. A loaded organic phase containing 0.48g·L-1 Ga could be produced from solution of 0.12g·L-1 Ga at A/O ratio of 4:1 via three mixer-settler operation stages. Gallium was stripped quantitatively from the loaded organic phase with 1.5mol·L-1 of sulfuric acid.

  14. Molecular Structure of Aminoguanidine Sulfate Monohydrate

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong-yan; ZHANG Tong-lai; QIAO Xiao-jing; YANG Li; SHAO Feng-lei

    2006-01-01

    The single crystal of aminoguanidine sulfate monohydrate [(AG)2SO4·H2O] is obtained and its structure is determined by X-ray diffraction analysis. The compound crystallizes in orthorhombic system with space group Pnma and the empirical formula C2H16N8O5S. The unit cell parameters are as follows: a=0.6759(2)nm, b=1.4131(5)nm, c=1.1650(4)nm, V=1.1128(6)n m3, Z=4, Dc=1.578g/cm3, F(000)=560, s=1.069, μ(MoKα)=0.318mm-1. The final R and Wr are 0.0312 and 0.0833, respectively. The title compound is an ionic compound and its structure unit consists of two aminoguanidium cations, one sulfate anion and one crystal water molecule, which are interconnected by electrostatic forces and hydrogen bond s into net structure, making the title compound very stable. Under a linear heat ingrate, the thermal decomposition processes of (AG)2SO4·H2O have one en dothermal dehydration stage, one melting process and one exothermic decomposition stage at 50-400℃, and can evolve abundant gas products.

  15. The effect of variable calcium and very low calcium diets on human calcium metabolism. Ph.D. Thesis. Final Report

    Science.gov (United States)

    Chu, J.

    1971-01-01

    The effects of a very low calcium diet, with variable high and low protein intake, on the dynamics of calcium metabolism and the mechanism of calciuretics, are examined. The experiment, using male subjects, was designed to study the role of intestinal calcium absorption on urinary calcium excretion, and the rate of production of endogeneously secreted calcium in the gastrointestinal tract. The study showed an average of 70% fractional absorption rate during very low calcium intake, and that a decrease in renal tubular reabsorption of calcium is responsible for calciuretic effects of high protein intake. The study also indicates that there is a tendency to develop osteoporosis after long periods of low calcium intake, especially with a concurrent high protein intake.

  16. Vitamin D and intestinal calcium absorption.

    Science.gov (United States)

    Christakos, Sylvia; Dhawan, Puneet; Porta, Angela; Mady, Leila J; Seth, Tanya

    2011-12-05

    The principal function of vitamin D in calcium homeostasis is to increase calcium absorption from the intestine. Calcium is absorbed by both an active transcellular pathway, which is energy dependent, and by a passive paracellular pathway through tight junctions. 1,25Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) the hormonally active form of vitamin D, through its genomic actions, is the major stimulator of active intestinal calcium absorption which involves calcium influx, translocation of calcium through the interior of the enterocyte and basolateral extrusion of calcium by the intestinal plasma membrane pump. This article reviews recent studies that have challenged the traditional model of vitamin D mediated transcellular calcium absorption and the crucial role of specific calcium transport proteins in intestinal calcium absorption. There is also increasing evidence that 1,25(OH)(2)D(3) can enhance paracellular calcium diffusion. The influence of estrogen, prolactin, glucocorticoids and aging on intestinal calcium absorption and the role of the distal intestine in vitamin D mediated intestinal calcium absorption are also discussed.

  17. Effects of brief and intermediate exposures to sulfate submicron aerosols and sulfate injections on cardiopulmonary function of dogs and tracheal mucous velocity of sheep

    Energy Technology Data Exchange (ETDEWEB)

    Sackner, M.A. (Mount Sinai Medical Center, Miami Beach, FL); Dougherty, R.L.; Chapman, G.A.; Cipley, J.; Perez, D.; Kwoka, M.; Reinhart, M.; Brito, M.; Schreck, R.

    1981-06-01

    Pulmonary mechanics of anesthetized dogs were not changed or were minimally altered by breathing the following compounds as submicron aerosols in concentrations up to 17.3 mg/m/sup 3/ for 7.5 min: (1) sodium chloride (as a control), (2) sodium sulfate, (3) ammonium sulfate, (4) zinc sulfate, (5) zinc ammonium sulfate, (6) ammonium bisulfate, (7) aluminum sulfate, (8) manganese sulfate, (9) nickel sulfate, (10) copper sulfate, (11) ferrous fulfate, and (12) ferric sulfate. Submicron aerosols of these compounds in concentrations of 4.1 to 8.8 mg/m/sup 3/, administered for 4 h to anesthetized dogs, did not affect mechanics of breathing, hemodynamics, and arterial blood gases. In conscious sheep, tracheal mucous velocity was not altered by exposure to the submicron aerosols of the sulfate compounds. None of these compounds, injected iv in a dose of 1 mg, had adverse effects on mechanics of breathing, pulmonary and systemic hemodynamics, or arterial blood gases. In 100-mg injections, zinc sulfate and zinc ammonium sulfate produced a fall in cardiac output, systemic hypotension, hypoxemia, and metabolic acidosis. Copper sulfate at this dose produced pulmonary hypertension, a fall in cardiac output, hypoxemia, respiratory acidosis, and a decrease of specific total respiratory conductance. It is concluded that submicron aerosols of sulfate salts do not have adverse cardiopulmonary effects when administered in high concentrations for up to 4 h. However, prolonged exposure to high concentrations of zinc sulfate, zinc ammonium sulfate, and copper sulfate aerosols might have adverse cardiopulmonary effects.

  18. 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

    electroporation and electrochemotherapy. METHODS: The effects of calcium electroporation and bleomycin electroporation (alone or in combination) were compared in three different cell lines (DC-3F, transformed Chinese hamster lung fibroblast; K-562, human leukemia; and murine Lewis Lung Carcinoma). Furthermore...... survival at similar applied voltage parameters. The effect of calcium electroporation is independent of calcium compound. GENERAL SIGNIFICANCE: This study strongly supports the use of calcium electroporation as a potential cancer therapy and the results may aid in future clinical trials....

  19. Chondroitin sulfate N-acetylgalactosaminyltransferase-1 (CSGalNAcT-1) involved in chondroitin sulfate initiation: Impact of sulfation on activity and specificity.

    Science.gov (United States)

    Gulberti, Sandrine; Jacquinet, Jean-Claude; Chabel, Matthieu; Ramalanjaona, Nick; Magdalou, Jacques; Netter, Patrick; Coughtrie, Michael W H; Ouzzine, Mohamed; Fournel-Gigleux, Sylvie

    2012-04-01

    Glycosaminoglycan (GAG) assembly initiates through the formation of a linkage tetrasaccharide region serving as a primer for both chondroitin sulfate (CS) and heparan sulfate (HS) chain polymerization. A possible role for sulfation of the linkage structure and of the constitutive disaccharide unit of CS chains in the regulation of CS-GAG chain synthesis has been suggested. To investigate this, we determined whether sulfate substitution of galactose (Gal) residues of the linkage region or of N-acetylgalactosamine (GalNAc) of the disaccharide unit influences activity and specificity of chondroitin sulfate N-acetylgalactosaminyltransferase-1 (CSGalNAcT-1), a key glycosyltransferase of CS biosynthesis. We synthesized a series of sulfated and unsulfated analogs of the linkage oligosaccharide and of the constitutive unit of CS and tested these molecules as potential acceptor substrates for the recombinant human CSGalNAcT-1. We show here that sulfation at C4 or C6 of the Gal residues markedly influences CSGalNAcT-1 initiation activity and catalytic efficiency. Kinetic analysis indicates that CSGalNAcT-1 exhibited 3.6-, 1.6-, and 2.2-fold higher enzymatic efficiency due to lower K(m) values toward monosulfated trisaccharides substituted at C4 or C6 position of Gal1, and at C6 of Gal2, respectively, compared with the unsulfated oligosaccharide. This highlights the critical influence of Gal substitution on both CSGalNAcT-1 activity and specifity. No GalNAcT activity was detected toward sulfated and unsulfated analogs of the CS constitutive disaccharide (GlcA-β1,3-GalNAc), indicating that CSGalNAcT-1 was involved in initiation but not in elongation of CS chains. Our results strongly suggest that sulfation of the linkage region acts as a regulatory signal in CS chain initiation.

  20. Growth performance and root transcriptome remodeling of Arabidopsis in response to Mars-like levels of magnesium sulfate.

    Directory of Open Access Journals (Sweden)

    Anne M Visscher

    Full Text Available BACKGROUND: Martian regolith (unconsolidated surface material is a potential medium for plant growth in bioregenerative life support systems during manned missions on Mars. However, hydrated magnesium sulfate mineral levels in the regolith of Mars can reach as high as 10 wt%, and would be expected to be highly inhibitory to plant growth. METHODOLOGY AND PRINCIPAL FINDINGS: Disabling ion transporters AtMRS2-10 and AtSULTR1;2, which are plasma membrane localized in peripheral root cells, is not an effective way to confer tolerance to magnesium sulfate soils. Arabidopsis mrs2-10 and sel1-10 knockout lines do not mitigate the growth inhibiting impacts of high MgSO(4.7H(2O concentrations observed with wildtype plants. A global approach was used to identify novel genes with potential to enhance tolerance to high MgSO(4.7H(2O (magnesium sulfate stress. The early Arabidopsis root transcriptome response to elevated concentrations of magnesium sulfate was characterized in Col-0, and also between Col-0 and the mutant line cax1-1, which was confirmed to be relatively tolerant of high levels of MgSO(4.7H(2O in soil solution. Differentially expressed genes in Col-0 treated for 45 min. encode enzymes primarily involved in hormone metabolism, transcription factors, calcium-binding proteins, kinases, cell wall related proteins and membrane-based transporters. Over 200 genes encoding transporters were differentially expressed in Col-0 up to 180 min. of exposure, and one of the first down-regulated genes was CAX1. The importance of this early response in wildtype Arabidopsis is exemplified in the fact that only four transcripts were differentially expressed between Col-0 and cax1-1 at 180 min. after initiation of treatment. CONCLUSIONS/SIGNIFICANCE: The results provide a solid basis for the understanding of the metabolic response of plants to elevated magnesium sulfate soils; it is the first transcriptome analysis of plants in this environment. The results foster

  1. The effect of calcium gluconate and other calcium supplements as a dietary calcium source on magnesium absorption in rats.

    Science.gov (United States)

    Chonan, O; Takahashi, R; Yasui, H; Watanuki, M

    1997-01-01

    The effects of commercially available calcium supplements (calcium carbonate, calcium gluconate, oyster shell preparation and bovine bone preparation) and gluconic acid on the absorption of calcium and magnesium were evaluated for 30 days in male Wistar rats. There were no differences in the apparent absorption ratio of calcium among rats fed each calcium supplement; however, the rats fed the calcium gluconate diet had a higher apparent absorption ratio of magnesium than the rats fed the other calcium supplements. Dietary gluconic acid also more markedly stimulated magnesium absorption than the calcium carbonate diet, and the bone (femur and tibia) magnesium contents of rats fed the gluconic acid diet were significantly higher than those of the rats fed the calcium carbonate diet. Furthermore, the weight of cecal tissue and the concentrations of acetic acid and butyric acid in cecal digesta of rats fed the calcium gluconate diet or the gluconic acid diet were significantly increased. We speculate that the stimulation of magnesium absorption in rats fed the calcium gluconate diet is a result of the gluconic acid component and the effect of gluconic acid on magnesium absorption probably results from cecal hypertrophy, magnesium solubility in the large intestine and the effects of volatile fatty acids on magnesium absorption.

  2. 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.

  3. Mechanism of store-operated calcium entry

    Indian Academy of Sciences (India)

    Devkanya Dutta

    2000-12-01

    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 store-operated calcium entry or capacitative calcium entry. Capacitative calcium current plays a key role in replenishing calcium stores and activating various physiological processes. Despite considerable efforts, very little is known about the molecular nature of the capacitative channel and the signalling pathway that activates it. This review summarizes our current knowledge about store operated calcium entry and suggests possible hypotheses for its mode of activation.

  4. The ins and outs of mitochondrial calcium.

    Science.gov (United States)

    Finkel, Toren; Menazza, Sara; Holmström, Kira M; Parks, Randi J; Liu, Julia; Sun, Junhui; Liu, Jie; Pan, Xin; Murphy, Elizabeth

    2015-05-22

    Calcium is thought to play an important role in regulating mitochondrial function. Evidence suggests that an increase in mitochondrial calcium can augment ATP production by altering the activity of calcium-sensitive mitochondrial matrix enzymes. In contrast, the entry of large amounts of mitochondrial calcium in the setting of ischemia-reperfusion injury is thought to be a critical event in triggering cellular necrosis. For many decades, the details of how calcium entered the mitochondria remained a biological mystery. In the past few years, significant progress has been made in identifying the molecular components of the mitochondrial calcium uniporter complex. Here, we review how calcium enters and leaves the mitochondria, the growing insight into the topology, stoichiometry and function of the uniporter complex, and the early lessons learned from some initial mouse models that genetically perturb mitochondrial calcium homeostasis.

  5. 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...

  6. Decalcification of calcium polycarbophil in rats.

    Science.gov (United States)

    Yamada, T; Saito, T; Takahara, E; Nagata, O; Tamai, I; Tsuji, A

    1997-03-01

    The in vivo decalcification of calcium polycarbophil was examined. The decalcification ratio of [45Ca]calcium polycarbophil in the stomach after oral dosing to rats was more than 70% at each designated time and quite closely followed in the in vitro decalcification curve, indicating that the greater part of the calcium ion is released from calcium polycarbophil under normal gastric acidic conditions. The residual radioactivity in rat gastrointestine was nearly equal to that after oral administration of either [45Ca]calcium chloride + polycarbophil. The serum level of radioactivity was nearly equal to that after oral dosing of [45Ca]calcium lactate. These results indicate that the greater part of orally administered calcium polycarbophil released calcium ions to produce polycarbophil in vivo.

  7. Transmembrane proteoglycans control stretch-activated channels to set cytosolic calcium levels

    DEFF Research Database (Denmark)

    Gopal, Sandeep; Søgaard, Pernille; Multhaupt, Hinke A B;

    2015-01-01

    show that syndecans regulate transient receptor potential canonical (TRPCs) channels to control cytosolic calcium equilibria and consequent cell behavior. In fibroblasts, ligand interactions with heparan sulfate of syndecan-4 recruit cytoplasmic protein kinase C to target serine714 of TRPC7...... with subsequent control of the cytoskeleton and the myofibroblast phenotype. In epidermal keratinocytes a syndecan-TRPC4 complex controls adhesion, adherens junction composition, and early differentiation in vivo and in vitro. In Caenorhabditis elegans, the TRPC orthologues TRP-1 and -2 genetically complement...

  8. A radioimmunoassay for measurement of thyroxine sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, I.J.; Santini, F.; Hurd, R.E.; Chua Teco, G.N. (Univ. of California Center for the Health Sciences, Los Angeles (United States))

    1993-01-01

    A highly sensitive, specific, and reproducible RIA has been developed to measure T[sub 4] sulfate (T[sub 4]S) in ethanol extracts of serum. rT[sub 3] sulfate (rT[sub 3]S) cross-reacted 7.1%, and T[sub 3]S cross-reacted 0.59% in the RIA; T[sub 4], T[sub 3], rT[sub 3] and 3,3[prime]-diiodothyronine cross-reacted 0.004% or less. The recovery of nonradioactive T[sub 4]S added to serum averaged 95%. The detection threshold of the RIA was 18 pmol/L. The coefficient of variation averaged 6.9% within an assay and 12% between assays. T[sub 4]S was bound by T[sub 4]-binding globulin and albumin in serum. The free fraction of T[sub 4]S in four normal sera averaged 0.06% compared to a value of 0.03% for T[sub 4] (P < 0.001). The serum concentration of T[sub 4]S was (mean [+-] SE) 19 [+-] 1.2 pmol/L in normal subjects, 33 [+-] 10 in hyperthyroid patients with Graves disease, 42 [+-] 15 in hypothyroid patients, 34 [+-] 6.9 in patients with systematic nonthyroidal illnesses, 21 [+-] 4.3 in pregnant women at 15-40 weeks gestation, and 245 [+-] 26 in cord blood sera of newborns; the value in the newborn was significantly different from normal (P < 0.001). Administration of sodium ipodate (Oragrafin; 3 g, orally) to hyperthyroid patients was associated with a transient increase in serum T[sub 4]S. The T[sub 4]S content of the thyroid gland was less than 1/4000th that of T[sub 4]. We conclude that (1) T[sub 4]S is a normal component of human serum, and its levels are markedly increased in newborn serum and amniotic fluid; and (2) the sulfation pathway plays an important role in the metabolism of T[sub 4] in man. 28 refs., 4 figs., 2 tabs.

  9. Calcium channel blockers and Alzheimer's disease

    Institute of Scientific and Technical Information of China (English)

    Yi Tan; Yulin Deng; Hong Qing

    2012-01-01

    Alzheimer's disease is characterized by two pathological hallmarks: amyloid plaques and neurofi-brillary tangles. In addition, calcium homeostasis is disrupted in the course of human aging. Recent research shows that dense plaques can cause functional alteration of calcium signals in mice with Alzheimer's disease. Calcium channel blockers are effective therapeutics for treating Alzheimer's disease. This review provides an overview of the current research of calcium channel blockers in-volved in Alzheimer's disease therapy.

  10. Variable efficacy of calcium carbonate tablets.

    Science.gov (United States)

    Kobrin, S M; Goldstein, S J; Shangraw, R F; Raja, R M

    1989-12-01

    Orally administered calcium carbonate tablets are commonly prescribed as a calcium supplement and for their phosphate-binding effects in renal failure patients. Two cases are reported in which a commercially available brand of calcium carbonate tablets appeared to be ineffective. Formal investigation of the bioavailability of this product revealed it to have impaired disintegration and dissolution and a lack of clinical efficacy. Recommendations that will enable physicians to avoid prescribing and pharmacists to avoid dispensing ineffective calcium carbonate tablets are proposed.

  11. Calcium regulation in endosymbiotic organelles of plants

    OpenAIRE

    Bussemer, Johanna; Vothknecht, Ute C.; Chigri, Fatima

    2009-01-01

    In plant cells calcium-dependent signaling pathways are involved in a large array of biological processes in response to hormones, biotic/abiotic stress signals and a variety of developmental cues. This is generally achieved through binding of calcium to diverse calcium-sensing proteins, which subsequently control downstream events by activating or inhibiting biochemical reactions. Regulation by calcium is considered as a eukaryotic trait and has not been described for prokaryotes. Neverthele...

  12. Teaching Calcium-Induced Calcium Release in Cardiomyocytes Using a Classic Paper by Fabiato

    Science.gov (United States)

    Liang, Willmann

    2008-01-01

    This teaching paper utilizes the materials presented by Dr. Fabiato in his review article entitled "Calcium-induced release of calcium from the cardiac sarcoplasmic reticulum." In the review, supporting evidence of calcium-induced calcium release (CICR) is presented. Data concerning potential objections to the CICR theory are discussed as well. In…

  13. Influence of alkali, silicate, and sulfate content of carbonated concrete pore solution on mild steel corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    L' Hostis, V. [CEA Saclay, DEN, DPC, SCCME, Lab Etud Comportement Betons and Argiles, F-91191 Gif Sur Yvette (France); Huet, B. [Schlumberger Riboud Prod Ctr, Schlumberger Carbon Serv, F-92142 Clamart (France); Tricheux, L. [CEBTP SOLEN, F-78990 Elancourt (France); Idrissi, H. [CNRS, Lab MATEIS UMR 5510, Equipe RI2S, Dept Sci and Genie Mat, F-69621 Villeurbanne (France)

    2010-07-01

    The increase in the rebar corrosion rate due to the concrete carbonation is the major cause of reinforced concrete degradation. The aim of this study was to investigate the corrosion behavior of mild steel rebars in simulated carbonated concrete solution. For this purpose, thermodynamic calculations, electrochemical techniques, gravimetric measurements, and surface analyses were used. Thermodynamic investigations of the nature of the interstitial solution provides an estimation of the influence of sulfate (SO{sub 4}{sup 2-}) and alkali (Na{sup +}, K{sup +}) content on carbonate alkalinity of the CO{sub 2}/H{sub 2}O open system (pCO{sub 2}=0. 3 mbar). in this system, calcium-silicate hydrates (C-S-H) remain thermodynamically unstable and amorphous silica controls silicate aqueous content at 100 ppm. Electrochemical results highlight a decrease in the corrosion rate with increasing carbonate alkalinity and the introduction of silicate. The introduction of sulfate at fixed carbonate alkalinity shows a dual effect: at high carbonate alkalinity, the corrosion rate is increased whereas at low carbonate alkalinity, corrosion rate is decreased. Those results are supported by surface analysis. Authors conclude that silicate and sulfate release from cement hydrates and fixation of alkali on carbonated hydrates are key parameters to estimate mild steel corrosion in carbonated concrete. (authors)

  14. Influence of alkali, silicate, and sulfate content of carbonated concrete pore solution on mild steel corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Huet, B. [Schlumberger Carbon Services, Schlumberger Riboud Product Center, Clamart (France); L' Hostis, V. [CEA, DEN, DPC, SCCME, Laboratoire d' Etude du Comportement des Betons et des Argiles, Gif-sur-Yvette, (France); Tricheux, L. [CEBTP-SOLEN, Elancourt, (France); Idrissi, H. [Laboratoire MATEIS UMR CNRS, Equipe RI2S, Department Science et Genie des Materiaux, Villeurbanne, (France)

    2010-02-15

    The increase in the rebar corrosion rate due to the concrete carbonation is the major cause of reinforced concrete degradation. The aim of this study was to investigate the corrosion behavior of mild steel rebars in simulated carbonated concrete solution. For this purpose, thermodynamic calculations, electrochemical techniques, gravimetric measurements, and surface analyses were used. Thermodynamic investigations of the nature of the interstitial solution provides an estimation of the influence of sulfate (SO{sub 4}{sup 2} {sup -}) and alkali (Na{sup +}, K{sup +}) content on carbonate alkalinity of the CO{sub 2}/H{sub 2}O open system (pCO{sub 2} = 0.3 mbar). In this system, calcium-silicate hydrates (C-S-H) remain thermodynamically unstable and amorphous silica controls silicate aqueous content at 100 ppm. Electrochemical results highlight a decrease in the corrosion rate with increasing carbonate alkalinity and the introduction of silicate. The introduction of sulfate at fixed carbonate alkalinity shows a dual effect: at high carbonate alkalinity, the corrosion rate is increased whereas at low carbonate alkalinity, corrosion rate is decreased. Those results are supported by surface analysis. Authors conclude that silicate and sulfate release from cement hydrates and fixation of alkali on carbonated hydrates are key parameters to estimate mild steel corrosion in carbonated concrete. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  15. The platelet glycoprotein thrombospondin binds specifically to sulfated glycolipids.

    Science.gov (United States)

    Roberts, D D; Haverstick, D M; Dixit, V M; Frazier, W A; Santoro, S A; Ginsburg, V

    1985-08-05

    The human platelet glycoprotein thrombospondin (TSP) binds specifically and with high affinity to sulfatides (galactosylceramide-I3-sulfate). Binding of 125I-TSP to lipids from sheep and human erythrocytes and human platelets resolved on thin layer chromatograms indicates that sulfatides are the only lipids in the membrane which bind TSP. Binding to less than 2 ng of sulfatide could be detected. TSP failed to bind to other purified lipids including cholesterol 3-sulfate, phospholipids, neutral glycolipids, and gangliosides. Binding of 125I-TSP was inhibited by unlabeled TSP, by low pH, and by reduction of intersubunit disulfide bonds with dithiothreitol. A monoclonal antibody against TSP (A2.5), which inhibits hemagglutination and agglutination of fixed activated platelets by TSP, strongly inhibited TSP binding to sulfatides. A second monoclonal antibody (C6.7), which inhibits hemagglutination and aggregation of thrombin-activated live platelets, weakly inhibited sulfatide binding. Binding was inhibited by high ionic strength and by some monosaccharide sulfates including methyl-alpha-D-GlcNAc-3-sulfate. Neutral sugars did not inhibit. Fucoidan, a sulfated fucan, strongly inhibited binding with 50% inhibition at 0.3 micrograms/ml fucoidan. Other sulfated polysaccharides including heparin and dextran sulfates were good inhibitors, whereas hyaluronic acid and keratan sulfate were very weak.

  16. Transmission spectra study of sulfate substituted potassium dihydrogen phosphate

    KAUST Repository

    LI, LIANG

    2013-04-18

    Potassium dihydrogen phosphate (KDP) crystals with different amounts of sulfate concentration were grown and the transmittance spectrum was studied. A crystal with high sulfate replacement density exhibits heavy absorption property in the ultraviolet region which confirms and agrees well with former results. © 2013 Astro Ltd.

  17. Biological processes for the production of aryl sulfates

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention generally relates to the field of biotechnology as it applies to the production of aryl sulfates using polypeptides or recombinant cells comprising said polypeptides. More particularly, the present invention pertains to polypeptides having aryl sulfotransferase activity......, recombinant host cells expressing same and processes for the production of aryl sulfates employing these polypeptides or recombinant host cells....

  18. Serum Indoxyl Sulfate Associates with Postangioplasty Thrombosis of Dialysis Grafts.

    Science.gov (United States)

    Wu, Chih-Cheng; Hsieh, Mu-Yang; Hung, Szu-Chun; Kuo, Ko-Lin; Tsai, Tung-Hu; Lai, Chao-Lun; Chen, Jaw-Wen; Lin, Shing-Jong; Huang, Po-Hsun; Tarng, Der-Cherng

    2016-04-01

    Hemodialysis vascular accesses are prone to recurrent stenosis and thrombosis after endovascular interventions.In vitro data suggest that indoxyl sulfate, a protein-bound uremic toxin, may induce vascular dysfunction and thrombosis. However, there is no clinical evidence regarding the role of indoxyl sulfate in hemodialysis vascular access. From January 2010 to June 2013, we prospectively enrolled patients undergoing angioplasty for dialysis access dysfunction. Patients were stratified into tertiles by baseline serum indoxyl sulfate levels. Study participants received clinical follow-up at 6-month intervals until June 2014. Primary end points were restenosis, thrombosis, and failure of vascular access. Median follow-up duration was 32 months. Of the 306 patients enrolled, 262 (86%) had symptomatic restenosis, 153 (50%) had access thrombosis, and 25 (8%) had access failure. In patients with graft access, free indoxyl sulfate tertiles showed a negative association with thrombosis-free patency (thrombosis-free patency rates of 54%, 38%, and 26% for low, middle, and high tertiles, respectively;P=0.001). Patients with graft thrombosis had higher free and total indoxyl sulfate levels. Using multivariate Cox regression analysis, graft thrombosis was independently predicted by absolute levels of free indoxyl sulfate (hazard ratio=1.14;P=0.01) and free indoxyl sulfate tertiles (high versus low, hazard ratio=2.41;P=0.001). Results of this study provide translational evidence that serum indoxyl sulfate is a novel risk factor for dialysis graft thrombosis after endovascular interventions.

  19. Sulfate reduction at low pH in organic wastewaters

    NARCIS (Netherlands)

    Lopes, S.I.C.

    2007-01-01

    The objective of the research described in this thesis was to investigate the operational window of dissimilatory sulfate reduction at low pH (6, 5 and 4) during the acidification of organic wastewaters. High sulfate reduction efficiencies at low pH are desirable for a more sustainable operation of

  20. Sulfation of ractopamine and salbutamol by the human cytosolic sulfotransferases.

    Science.gov (United States)

    Ko, Kyounga; Kurogi, Katsuhisa; Davidson, Garrett; Liu, Ming-Yih; Sakakibara, Yoichi; Suiko, Masahito; Liu, Ming-Cheh

    2012-09-01

    Feed additives such as ractopamine and salbutamol are pharmacologically active compounds, acting primarily as β-adrenergic agonists. This study was designed to investigate whether the sulfation of ractopamine and salbutamol may occur under the metabolic conditions and to identify the human cytosolic sulfotransferases (SULTs) that are capable of sulfating two major feed additive compounds, ractopamine and salbutamol. A metabolic labelling study showed the generation and release of [(35)S]sulfated ractopamine and salbutamol by HepG2 human hepatoma cells labelled with [(35)S]sulfate in the presence of these two compounds. A systematic analysis using 11 purified human SULTs revealed SULT1A3 as the major SULT responsible for the sulfation of ractopamine and salbutamol. The pH dependence and kinetic parameters were analyzed. Moreover, the inhibitory effects of ractopamine and salbutamol on SULT1A3-mediated dopamine sulfation were investigated. Cytosol or S9 fractions of human lung, liver, kidney and small intestine were examined to verify the presence of ractopamine-/salbutamol-sulfating activity in vivo. Of the four human organs, the small intestine displayed the highest activity towards both compounds. Collectively, these results imply that the sulfation mediated by SULT1A3 may play an important role in the metabolism and detoxification of ractopamine and salbutamol.

  1. 21 CFR 173.385 - Sodium methyl sulfate.

    Science.gov (United States)

    2010-04-01

    ... Specific Usage Additives § 173.385 Sodium methyl sulfate. Sodium methyl sulfate may be present in pectin in accordance with the following conditions. (a) It is present as the result of methylation of pectin by....1 percent by weight of the pectin....

  2. Reductive and sorptive properties of sulfate green rust (GRSO4)

    DEFF Research Database (Denmark)

    Nedel, Sorin

    The Fe(II), Fe(III) hydroxide containing sulfate in its structure, called sulfate green rust (GRSO4), can effectively reduce and convert contaminants to less mobile and less toxic forms. However, the ability of GRSO4 to remove positively charged species from solution, via sorption, is very limited...

  3. 21 CFR 520.110 - Apramycin sulfate soluble powder.

    Science.gov (United States)

    2010-04-01

    ...) caused by strains of E. coli sensitive to apramycin. (2) It is administered for 7 days in drinking water... sulfate soluble powder. (a) Specifications. A water soluble powder used to make a medicated drinking water containing apramycin sulfate equivalent to 0.375 gram of apramycin activity per gallon of drinking water....

  4. Novel Thermally Stable Poly (vinyl chloride) Composites for Sulfate Removal

    Science.gov (United States)

    BaCO3 dispersed PVC composites were prepared through a polymer re-precipitation method. The composites were tested for sulfate removal using rapid small scale column test (RSSCT) and found to significantly reduce sulfate concentration. The method was extended to synthe...

  5. Sulfate was a trace constituent of Archean seawater

    DEFF Research Database (Denmark)

    Crowe, Sean Andrew; Paris, Guillaume; Katsev, Sergei;

    2014-01-01

    In the low-oxygen Archean world (>2400 million years ago), seawater sulfate concentrations were much lower than today, yet open questions frustrate the translation of modern measurements of sulfur isotope fractionations into estimates of Archean seawater sulfate concentrations. In the water colum...

  6. Quantitative Analysis of Sulfate in Water by Indirect EDTA Titration

    Science.gov (United States)

    Belle-Oudry, Deirdre

    2008-01-01

    The determination of sulfate concentration in water by indirect EDTA titration is an instructive experiment that is easily implemented in an analytical chemistry laboratory course. A water sample is treated with excess barium chloride to precipitate sulfate ions as BaSO[subscript 4](s). The unprecipitated barium ions are then titrated with EDTA.…

  7. Catalytic synthesis of sulfated polysaccharides I: Characterization of chemical structure.

    Science.gov (United States)

    Wang, Junlong; Yang, Wen; Yang, Ting; Zhang, Xiaonuo; Zuo, Yuan; Tian, Jia; Yao, Jian; Zhang, Ji; Lei, Ziqiang

    2015-03-01

    In the present study, sulfated derivatives of Artemisia sphaerocephala polysaccharide (SASP) with high degree of substitution (DS) were synthesized by using 4-dimethylaminopyridine (DMAP)/dimethylcyclohexylcarbodiimide (DCC) as catalyst in homogeneous conditions. It was found that DMAP/DCC showed marked improvement in DS of sulfated samples. Compared to sulfated derivatives without catalyst, the DS of SASP increased from 0.91 to 1.28 with an increment in dosage of DMAP from 0 to 10 mg. The influence of DMAP/DCC on the DS of sulfated derivatives was depended on the content of DMAP. The effect of DMAP might be due to its strong coordination to the hydroxy group. The results of FT-IR and X-ray photoelectron spectroscopy (XPS) indicated that SO3- group (S6+, binding energy of 172.3 eV) was widely present in sulfated polysaccharide molecules. 13C NMR results indicated that C-6 substitution was predominant for sulfated polysaccharide when compared with other positions. In the sulfation reaction, a sharp decrease in MW was observed. DMAP/DCC was an effective catalyst system in sulfated modification of polysaccharide.

  8. Structural characterization and bioactivities of sulfated polysaccharide from Monostroma oxyspermum.

    Science.gov (United States)

    Seedevi, Palaniappan; Moovendhan, Meivelu; Sudharsan, Sadhasivam; Vasanthkumar, Shanmugam; Srinivasan, Alagiri; Vairamani, Shanmugam; Shanmugam, Annaian

    2015-01-01

    Sulfated polysaccharide was isolated from Monostroma oxyspermum through hot water extraction, anion-exchange and gel permeation column chromatography. The sulfated polysaccharide contained 92% of carbohydrate, 0% of protein, 7.8% of uronic acid, 22% of ash and 33% of moisture respectively. The elemental composition was analyzed using CHNS/O analyzer. The molecular weight of sulfated polysaccharide determined through PAGE was found to be as 55 kDa. Monosaccharides analysis revealed that sulfated polysaccharide was composed of rhamnose, fructose, galactose, xylose, and glucose. The structural features of sulfated polysaccharide were analyzed by NMR spectroscopy. Further the sulfated polysaccharide showed total antioxidant and DPPH free radical scavenging activity were as 66.29% at 250 μg/ml and 66.83% at 160 μg/ml respectively. The sulfated polysaccharide also showed ABTS scavenging ability and reducing power were as 83.88% at 125 μg/ml and 15.81% at 400 μg/ml respectively. The anticoagulant activity was determined for human plasma with respect to Activated Partial Thromboplastin Time (APTT) and Prothrombin Time (PT) was 20.09 IU and 1.79 IU at 25 μg/ml respectively. These results indicated that the sulfated polysaccharide from M. oxyspermum had potent antioxidant and anticoagulant activities.

  9. Genesis and solution chemistry of acid sulfate soils in Thailand

    NARCIS (Netherlands)

    Breemen, van N.

    1976-01-01

    To study short-term and long-term chemical processes in periodically flooded acid sulfate soils in the Bangkok Plain and in various smaller coastal plains along the Gulf of Thailand, 16 acid sulfate soils and one non-acid marine soil were examined for distribution of iron-sulfur compounds, elemental

  10. 21 CFR 582.5217 - Calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium phosphate. 582.5217 Section 582.5217 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic)....

  11. 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)....

  12. 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)....

  13. 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...

  14. Acute calcium homeostasis in MHS swine.

    Science.gov (United States)

    Harrison, G G; Morrell, D F; Brain, V; Jaros, G G

    1987-07-01

    To elucidate a pathogenesis for the reduction in bone calcium content observed in MHS individuals, we studied the acute calcium homeostasis of MHS swine. This was achieved by the serial measurement, with a calcium selective electrode, of calcium transients in Landrace MHS (five) and control Landrace/large white cross MH negative (five) swine following IV bolus injection of calcium gluconate 0.1 mmol X kg-1--a dose which induced an acute 45 per cent increase in plasma ionised calcium. Experimental animals were anaesthetised with ketamine 10 mg X kg-1 IM, thiopentone (intermittent divided doses) 15-25 mg X kg-1 (total) IV and N2O/O2 (FIO2 0.3) by IPPV to maintain a normal blood gas, acid/base state. The plasma ionised calcium decay curve observed in MHS swine did not differ from that of control normal swine. Further it was noted that the induced acute rise in plasma ionised calcium failed to trigger the MH syndrome in any MHS swine. It is concluded that the mechanisms of acute calcium homeostasis in MHS swine are normal. An explanation for the reduction in bone calcium content observed in MHS individuals must be sought, therefore, through study of the slow long-term component of the calcium regulatory process. In addition, the conventional strictures placed on the use, in MHS patients, of calcium gluconate are called in question.

  15. Multifaceted Role of Calcium in Cancer.

    Science.gov (United States)

    Sarode, Gargi S; Sarode, Sachin C; Patil, Shankargouda

    2017-01-01

    Role of calcium in bone remodeling and tooth remineral-ization is well known. However, calcium also plays a very imperative role in many biochemical reactions, which are essential for normal functioning of cells. The calcium associated tissue homeostasis encompasses activities like proliferation, cell death, cell motility, oxygen, and nutrient supply.

  16. 21 CFR 582.6219 - Calcium phytate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium phytate. 582.6219 Section 582.6219 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium phytate. (a) Product. Calcium phytate. (b) Conditions of use. This substance is...

  17. 21 CFR 582.3189 - Calcium ascorbate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium ascorbate. 582.3189 Section 582.3189 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL....3189 Calcium ascorbate. (a) Product. Calcium ascorbate. (b) Conditions of use. This substance...

  18. 21 CFR 182.3189 - Calcium ascorbate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium ascorbate. 182.3189 Section 182.3189 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Calcium ascorbate. (a) Product. Calcium ascorbate. (b) Conditions of use. This substance is...

  19. 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...

  20. Effects of chlorate on the sulfation process of Trypanosoma cruzi glycoconjugates. Implication of parasite sulfates in cellular invasion.

    Science.gov (United States)

    Ferrero, Maximiliano R; Soprano, Luciana L; Acosta, Diana M; García, Gabriela A; Esteva, Mónica I; Couto, Alicia S; Duschak, Vilma G

    2014-09-01

    Sulfation, a post-translational modification which plays a key role in various biological processes, is inhibited by competition with chlorate. In Trypanosoma cruzi, the agent of Chagas' disease, sulfated structures have been described as part of glycolipids and we have reported sulfated high-mannose type oligosaccharides in the C-T domain of the cruzipain (Cz) glycoprotein. However, sulfation pathways have not been described yet in this parasite. Herein, we studied the effect of chlorate treatment on T. cruzi with the aim to gain some knowledge about sulfation metabolism and the role of sulfated molecules in this parasite. In chlorate-treated epimastigotes, immunoblotting with anti-sulfates enriched Cz IgGs (AS-enriched IgGs) showed Cz undersulfation. Accordingly, a Cz mobility shift toward higher isoelectric points was observed in 2D-PAGE probed with anti-Cz antibodies. Ultrastructural membrane abnormalities and a significant decrease of dark lipid reservosomes were shown by electron microscopy and a significant decrease in sulfatide levels was confirmed by TLC/UV-MALDI-TOF-MS analysis. Altogether, these results suggest T. cruzi sulfation occurs via PAPS. Sulfated epitopes in trypomastigote and amastigote forms were evidenced using AS-enriched IgGs by immunoblotting. Their presence on trypomastigotes surface was demonstrated by flow cytometry and IF with Cz/dCz specific antibodies. Interestingly, the percentage of infected cardiac HL-1 cells decreased 40% when using chlorate-treated trypomastigotes, suggesting sulfates are involved in the invasion process. The same effect was observed when cells were pre-incubated with dCz, dC-T or an anti-high mannose receptor (HMR) antibody, suggesting Cz sulfates and HMR are also involved in the infection process by T. cruzi.

  1. Ovarian carcinoma cells synthesize both chondroitin sulfate and heparan sulfate cell surface proteoglycans that mediate cell adhesion to interstitial matrix.

    Science.gov (United States)

    Kokenyesi, R

    Metastatic ovarian carcinoma metastasizes by intra-peritoneal, non-hematogenous dissemination. The adhesion of the ovarian carcinoma cells to extracellular matrix components, such as types I and III collagen and cellular fibronectin, is essential for intra-peritoneal dissemination. The purpose of this study was to determine whether cell surface proteoglycans (a class of matrix receptors) are produced by ovarian carcinoma cells, and whether these proteoglycans have a role in the adhesion of ovarian carcinoma cells to types I and III collagen and fibronectin. Proteoglycans were metabolically labeled for biochemical studies. Both phosphatidylinositol-anchored and integral membrane-type cell surface proteoglycans were found to be present on the SK-OV-3 and NIH:OVCAR-3 cell lines. Three proteoglycan populations of differing hydrodynamic size were detected in both SK-OV-3 and NIH:OVCAR-3 cells. Digestions with heparitinase and chondroitinase ABC showed that cell surface proteoglycans of SK-OV-3 cells had higher proportion of chondroitin sulfate proteoglycans (75:25 of chondroitin sulfate:heparan sulfate ratio), while NIH:OVCAR-3 cells had higher proportion of heparan sulfate proteoglycans (10:90 of chondroitin sulfate:heparan sulfate ratio). RT-PCR indicated the synthesis of a unique assortment of syndecans, glypicans, and CD44 by the two cell lines. In adhesion assays performed on matrix-coated titer plates both cell lines adhered to types I and III collagen and cellular fibronectin, and cell adhesion was inhibited by preincubation of the matrix with heparin, heparan sulfate, chondroitin sulfate, dermatan sulfate, or chondroitin glycosaminoglycans. Treatment of the cells with heparitinase, chondroitinase ABC, or methylumbelliferyl xyloside also interfered with adhesion confirming the role of both heparan sulfate and chondroitin sulfate cell surface proteoglycans as matrix receptors on ovarian carcinoma cells.

  2. Dehydroepiandrosterone, Its Sulfate and Cognitive Functions

    Science.gov (United States)

    de Menezes, Karina Junqueira; Peixoto, Clayton; Nardi, Antonio Egidio; Carta, Mauro Giovanni; Machado, Sérgio; Veras, André Barciela

    2016-01-01

    To present a review of cross-sectional and longitudinal studies that investigate the relationship between the hormones Dehydroepiandrosterone (DHEA) and Dehydroepiandrosterone sulfate (DHEA-S) and cognition. Methods: The cognition items included in this review were global cognitive function, memory, attention, executive function, intelligence, perception and visuospatial ability. A systematic review was proceeded using three databases: PubMed, ISI Web of Science, and PsycINFO. Results: Two thousand fifty five references about cognition and hormones were found; 772 duplicated references were excluded, resulting in 1.283 references to be evaluated. According to exclusion and inclusion criteria, 25 references were selected. A positive correlation between DHEA-S blood levels and global cognition was found in women and men. Other positive correlations between DHEA-S and working memory, attention and verbal fluency were found only in women. The DHEA effect on cognition is limited to one study conducted among young men with high-doses. PMID:27346998

  3. Calcium Orthophosphate-Based Bioceramics

    Directory of Open Access Journals (Sweden)

    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. Pressure effect on dissimilatory sulfate reduction

    Science.gov (United States)

    Williamson, A. J.; Carlson, H. K.; Coates, J. D.

    2015-12-01

    Biosouring is the production of H2S by sulfate reducing microorganisms (SRM) in-situ or in the produced fluids of oil reservoirs. Sulfide is explosive, toxic and corrosive which can trigger equipment and transportation failure, leading to environmental catastrophe. As oil exploration and reservoir development continue, subsequent enhanced recovery is occurring in progressively deeper formations and typical oil reservoir pressures range from 10-50 MPa. Therefore, an understanding of souring control effects will require an accurate understanding of the influence of pressure on SRM metabolism and the efficacy of souring control treatments at high pressure. Considerable work to date has focussed on souring control at ambient pressure; however, the influence of pressure on biogeochemical processes and souring treatments in oil reservoirs is poorly understood. To explore the impact of pressure on SRM, wild type Desulfovibrio alaskensis G20 (isolated from a producing oil well in Ventura County, California) was grown under a range of pressures (0.1-14 MPa) at 30 °C. Complete sulfate reduction occurred in all pressures tested within 3 days, but microbial growth was inhibited with increasing pressure. Bar-seq identified several genes associated with flagella biosynthesis (including FlhB) and assembly as important for survival at elevated pressure and fitness was confirmed using individual transposon mutants. Flagellar genes have previously been implicated with biofilm formation and confocal microscopy on glass slides incubated with wild type D. alaskensis G20 showed more biomass associated with surfaces under pressure, highlighting the link between pressure, flagellar and biofilm formation. To determine the effect of pressure on the efficacy of SRM inhibitors, IC50 experiments were conducted and D. alaskensis G20 showed a greater resistance to nitrate and the antibiotic chloramphenicol, but a lower resistance to perchlorate. These results will be discussed in the context of

  5. Preparation and characterization of a chemically sulfated cashew gum polysaccharide

    Energy Technology Data Exchange (ETDEWEB)

    Moura Neto, Erico de; Maciel, Jeanny da S.; Cunha, Pablyana L. R.; Paula, Regina Celia M. de; Feitosa, Judith P.A., E-mail: judith@dqoi.ufc.br [Departamento de Quimica Organica e Inorganica, Universidade Federal do Ceara, Fortaleza (Brazil)

    2011-09-15

    Cashew gum (CG) was sulfated in pyridine:formamide using chlorosulfonic acid as the reagent. Confirmation of sulfation was obtained by Fourier transform infrared (FTIR) spectroscopy through the presence of an asymmetrical S=O stretching vibration at 1259 cm{sup -1}. The degrees of substitution were 0.02, 0.24 and 0.88 determined from the sulfur percentage. 1D and 2D nuclear magnetic resonance (NMR) data showed that the sulfation occurred at primary carbons. An increase of at least 4% of the solution viscosity was observed due to sulfation. The thermal gravimetric curves (TGA) indicate that the derivatives are stable up to ca. 200 deg C. The sulfated CG is compared to carboxymethylated CG in order to verify the possibility of the use of the former in the preparation of polyelectrolyte complexes; the latter is already being used for this application. (author)

  6. Sulfation of tea polysaccharides: synthesis, characterization and hypoglycemic activity.

    Science.gov (United States)

    Wang, Yuanfeng; Peng, Yonghua; Wei, Xinlin; Yang, Zhiwei; Xiao, Jianbo; Jin, Zhengyu

    2010-03-01

    Neutral polysaccharides (NTPS) and acid polysaccharides (ATPS) from tea leaves were obtained on a D315 macroporous anion-exchange resin column chromatography. NTPS and ATPS were sulfated by the pyridine-sulfonic acid method to obtain NTPS-S and ATPS-S. It was found that NTPS was easier sulfated than ATPS. There are strong characteristic absorption peaks located in 1258 cm(-1), 1146 cm(-1), 832 cm(-1) and 617 cm(-1) in the FTIR spectra of sulfated polysaccharides. Sulfation of polysaccharides also affected the endothermic and exothermic peaks via the DSC scan analysis. The appearance of exothermic peaks in both NTPS-S and ATPS-S indicated that the redox reaction might happen. The comparative study of hypoglycemic effect on mice showed that the sulfation of polysaccharides significantly improved hypoglycemic activity.

  7. Chondroitin / dermatan sulfate modification enzymes in zebrafish development.

    Directory of Open Access Journals (Sweden)

    Judith Habicher

    Full Text Available Chondroitin/dermatan sulfate (CS/DS proteoglycans consist of unbranched sulfated polysaccharide chains of repeating GalNAc-GlcA/IdoA disaccharide units, attached to serine residues on specific proteins. The CS/DS proteoglycans are abundant in the extracellular matrix where they have essential functions in tissue development and homeostasis. In this report a phylogenetic analysis of vertebrate genes coding for the enzymes that modify CS/DS is presented. We identify single orthologous genes in the zebrafish genome for the sulfotransferases chst7, chst11, chst13, chst14, chst15 and ust and the epimerase dse. In contrast, two copies were found for mammalian sulfotransferases CHST3 and CHST12 and the epimerase DSEL, named chst3a and chst3b, chst12a and chst12b, dsela and dselb, respectively. Expression of CS/DS modification enzymes is spatially and temporally regulated with a large variation between different genes. We found that CS/DS 4-O-sulfotransferases and 6-O-sulfotransferases as well as CS/DS epimerases show a strong and partly overlapping expression, whereas the expression is restricted for enzymes with ability to synthesize di-sulfated disaccharides. A structural analysis further showed that CS/DS sulfation increases during embryonic development mainly due to synthesis of 4-O-sulfated GalNAc while the proportion of 6-O-sulfated GalNAc increases in later developmental stages. Di-sulfated GalNAc synthesized by Chst15 and 2-O-sulfated GlcA/IdoA synthesized by Ust are rare, in accordance with the restricted expression of these enzymes. We also compared CS/DS composition with that of heparan sulfate (HS. Notably, CS/DS biosynthesis in early zebrafish development is more dynamic than HS biosynthesis. Furthermore, HS contains disaccharides with more than one sulfate group, which are virtually absent in CS/DS.

  8. 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.

  9. 21 CFR 524.154 - Bacitracin or bacitracin zinc-neomycin sulfate-polymyxin B sulfate ophthalmic ointment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Bacitracin or bacitracin zinc-neomycin sulfate... TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.154 Bacitracin or bacitracin zinc-neomycin sulfate-polymyxin B...: (1) To 000009; each gram contains 500 units of bacitracin, 3.5 milligrams of neomycin, and...

  10. Low levels of H2S may replace sulfate as sulfur source in sulfate-deprived onion

    NARCIS (Netherlands)

    Durenkamp, Mark; De Kok, LJ

    2005-01-01

    Onion (Allium cepa L.) was exposed to low levels of H2S in order to investigate to what extent H2S could be used as a sulfur source for growth under sulfate-deprived conditions. Sulfate deprivation for a two-week period resulted in a decreased biomass production of the shoot, a subsequently decrease

  11. Impact of sulfation pattern on the conformation and dynamics of sulfated fucan oligosaccharides as revealed by NMR and MD.

    Science.gov (United States)

    Queiroz, Ismael N L; Wang, Xiaocong; Glushka, John N; Santos, Gustavo R C; Valente, Ana P; Prestegard, James H; Woods, Robert J; Mourão, Paulo A S; Pomin, Vitor H

    2015-05-01

    Sulfated fucans from sea urchin egg jelly express well-defined chemical structures that vary with species. This species specificity regulates the sperm acrosome reaction, a critical step to assure intra-specific fertilization. In addition, these polysaccharides are involved in other biological activities such as anticoagulation. Although sulfation patterns are relevant to the levels of response in both activities, conformation and dynamics of these glycans are also contributing factors. However, data about these features of sulfated fucans are very rare. To address this, we have employed nuclear magnetic resonance experiments combined with molecular dynamics on structurally defined oligosaccharides derived from two sulfated fucans. The results have indicated that the oligosaccharides are flexible in solution. Ring conformation of their composing units displays just the (1)C4 chair configuration. In a particular octasaccharide, composed of two tetrasaccharide sequences, inter-residual hydrogen bonds play a role to decrease dynamics in these repeating units. Conversely, the linking disaccharide [-3)-α-L-Fucp-2(OSO3(-))-(1-3)-α-L-Fucp-4(OCO3(-))-(1-] located right between the two tetrasaccharide units has amplified motions suggested to be promoted by electrostatic repulsion of sulfates on opposite sides of the central glycosidic bond. This conjunction of information about conformation and dynamics of sulfated fucan oligosaccharides provides new insights to explain how these glycans behave free in solution and influenced by sulfation patterns. It may also serve for future studies concerning structure-function relationship of sulfated fucans, especially those involving sea urchin fertilization and anticoagulation.

  12. The chemical transformation of calcium in Shenhua coal during combustion in a muffle furnace

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Sida [North China Electric Power Univ., Beijing (China). School of Energy, Power and Mechanical Engineering; Ministry of Education, Beijing (China). Key Lab. of Condition Monitoring and Control for Power Plant Equipment; Zhuo, Yuqun; Chen, Changhe [Tsinghua Univ., Beijing (China). Dept. of Thermal Engineering; Ministry of Education, Beijing (China). Key Lab. for Thermal Science and Power Engineering; Shu, Xinqian [China Univ. of Mining and Technology, Beijing (China). School of Chemical and Environmental Engineering

    2013-07-01

    The chemical reaction characteristics of calcium in three samples of Shenhua coal, i.e. raw sample, hydrochloric acid washed sample and hydrochloric acid washed light fraction, during combustion in a muffle furnace have been investigated in this paper. Ca is bound by calcite and organic matter in Shenhua coal. X ray diffraction (XRD) phase analysis has been conducted to these samples' combustion products obtained by heating at different temperatures. It has been found that the organically-bound calcium could easily react with clays and transform into gehlenite and anorthite partially if combusted under 815 C, whilst the excluded minerals promoted the conversion of gehlenite to anorthite. Calcite in Shenhua coal decomposed into calcium oxide and partially transformed into calcium sulfate under 815 C, and formed gehlenite and anorthite under 1,050 C. Calcite and other HCl-dissolved minerals in Shenhua coal were responsible mainly for the characteristic that the clay minerals in Shenhua coal hardly became mullite during combustion.

  13. 物料还原性对硫铝酸钙形成过程的影响%Effect of Material Reduction on the Formation of Calcium Sulphoaluminate

    Institute of Scientific and Technical Information of China (English)

    许亚文; 谢峻林; 郭惠玲

    2011-01-01

    The influence of material reduction on the formation and high temperature stability of calcium sulphoaluminate、 the decomposition of calcium sulfate was investigated by means of flue gas analyzer, X-ray diffraction and chemical analysis.The results show that material reduction can significantly promote the decomposition of calcium sulfate above 1 200 ℃ ,and narrow the high temperature stable region of calcium sulphoaluminate; besides, the optimal formation temperature of calcium sulphoaluminate is 1 100 ℃ in the high reductive material.%采用烟气分析仪、X射线衍射分析等测试手段研究了物料还原性对高温固硫物相形成的影响.探讨了物料还原性对硫酸钙分解以及对硫铝酸钙的形成和高温稳定性的影响.结果表明:在1200℃以上,物料还原性对硫酸钙的分解有明显的促进作用;物料还原性缩小了硫铝酸钙的高温稳定区域;高还原性煤渣中硫铝酸钙的最佳形成温度为1100℃.

  14. 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......)-sensitive fast Na(+) spike faithfully followed repetitive depolarizing pulses with little change in spike duration or amplitude, while a strong outward rectification dominated responses to long-lasting depolarizations. High-threshold calcium spikes were uncovered following addition of potassium channel blockers...

  15. Calcium regulation in endosymbiotic organelles of plants.

    Science.gov (United States)

    Bussemer, Johanna; Vothknecht, Ute C; Chigri, Fatima

    2009-09-01

    In plant cells calcium-dependent signaling pathways are involved in a large array of biological processes in response to hormones, biotic/abiotic stress signals and a variety of developmental cues. This is generally achieved through binding of calcium to diverse calcium-sensing proteins, which subsequently control downstream events by activating or inhibiting biochemical reactions. Regulation by calcium is considered as a eukaryotic trait and has not been described for prokaryotes. Nevertheless, there is increasing evidence indicating that organelles of prokaryotic origin, such as chloroplasts and mitochondria, are integrated into the calcium-signaling network of the cell. An important transducer of calcium in these organelles appears to be calmodulin. In this review we want to give an overview over present data showing that endosymbiotic organelles harbour calcium-dependent biological processes with a focus on calmodulin-regulation.

  16. Store-operated calcium signaling in neutrophils.

    Science.gov (United States)

    Clemens, Regina A; Lowell, Clifford A

    2015-10-01

    Calcium signals in neutrophils are initiated by a variety of cell-surface receptors, including formyl peptide and other GPCRs, FcRs, and integrins. The predominant pathway by which calcium enters immune cells is termed SOCE, whereby plasma membrane CRAC channels allow influx of extracellular calcium into the cytoplasm when intracellular ER stores are depleted. The identification of 2 key families of SOCE regulators, STIM calcium "sensors" and ORAI calcium channels, has allowed for genetic manipulation of SOCE pathways and provided valuable insight into the molecular mechanism of calcium signaling in immune cells, including neutrophils. This review focuses on our current knowledge of the molecules involved in neutrophil SOCE and how study of these molecules has further informed our understanding of the role of calcium signaling in neutrophil activation.

  17. Drosophila mushroom body Kenyon cells generate spontaneous calcium transients mediated by PLTX-sensitive calcium channels.

    Science.gov (United States)

    Jiang, Shaojuan Amy; Campusano, Jorge M; Su, Hailing; O'Dowd, Diane K

    2005-07-01

    Spontaneous calcium oscillations in mushroom bodies of late stage pupal and adult Drosophila brains have been implicated in memory consolidation during olfactory associative learning. This study explores the cellular mechanisms regulating calcium dynamics in Kenyon cells, principal neurons in mushroom bodies. Fura-2 imaging shows that Kenyon cells cultured from late stage Drosophila pupae generate spontaneous calcium transients in a cell autonomous fashion, at a frequency similar to calcium oscillations in vivo (10-20/h). The expression of calcium transients is up regulated during pupal development. Although the ability to generate transients is a property intrinsic to Kenyon cells, transients can be modulated by bath application of nicotine and GABA. Calcium transients are blocked, and baseline calcium levels reduced, by removal of external calcium, addition of cobalt, or addition of Plectreurys toxin (PLTX), an insect-specific calcium channel antagonist. Transients do not require calcium release from intracellular stores. Whole cell recordings reveal that the majority of voltage-gated calcium channels in Kenyon cells are PLTX-sensitive. Together these data show that influx of calcium through PLTX-sensitive voltage-gated calcium channels mediates spontaneous calcium transients and regulates basal calcium levels in cultured Kenyon cells. The data also suggest that these calcium transients represent cellular events underlying calcium oscillations in the intact mushroom bodies. However, spontaneous calcium transients are not unique to Kenyon cells as they are present in approximately 60% of all cultured central brain neurons. This suggests the calcium transients play a more general role in maturation or function of adult brain neurons.

  18. Ulvans induce resistance against plant pathogenic fungi independently of their sulfation degree.

    Science.gov (United States)

    de Freitas, Mateus B; Ferreira, Luciana G; Hawerroth, Caroline; Duarte, Maria Eugênia R; Noseda, Miguel D; Stadnik, Marciel J

    2015-11-20

    The present work aimed to evaluate the defense responses induced by chemically sulfated ulvans in Arabidopsis thaliana plants against the phytopathogenic fungi Alternaria brassicicola and Colletotrichum higginsianum. Derivatives with growing sulfate content (from 20.9 to 36.6%) were prepared with SO3-pyridine complex in formamide. NMR and FTIR spectroscopic analyses confirmed the increase of sulfate groups after the chemical sulfation process. The native sulfated polysaccharide (18.9% of sulfate) and its chemically sulfated derivatives similarly reduced the severity of both pathogenic fungi infections. Collectively, our results suggest that ulvans induce resistance against both fungal pathogens independently of its sulfation degree.

  19. An integrative review of the side effects related to the use of magnesium sulfate for pre-eclampsia and eclampsia management

    Directory of Open Access Journals (Sweden)

    Smith Jeffrey Michael

    2013-02-01

    Full Text Available Abstract Background Pre-eclampsia/eclampsia is one of the most common causes of maternal and perinatal morbidity and mortality in low and middle income countries. Magnesium sulfate is the drug of choice for prevention of seizures as part of comprehensive management of the disease. Despite the compelling evidence for the effectiveness of magnesium sulfate, concern has been expressed about its safety and potential for toxicity, particularly among providers in low- and middle-income countries. The purpose of this review was to determine whether the literature published in these global settings supports the concerns about the safety of use of magnesium sulfate. Methods An integrative review of the literature was conducted to document the known incidences of severe adverse reactions to magnesium sulphate, and specific outcomes of interest related to its use. All types of prospective clinical studies were included if magnesium sulfate was used to manage pre-eclampsia or eclampsia, the study was conducted in a low- or middle-income country, and the study included the recording of the incidence of any adverse side effect resulting from magnesium sulfate use. Results A total of 24 studies that compared a magnesium sulfate regimen against other drug regimens and examined side effects among 34 subject groups were included. The overall rate of absent patellar reflex among all 9556 aggregated women was 1.6%, with a range of 0-57%. The overall rate of respiratory depression in 25 subject groups in which this outcome was reported was 1.3%, with a range of 0–8.2%. Delay in repeat administration of magnesium sulfate occurred in 3.6% of cases, with a range of 0-65%. Calcium gluconate was administered at an overall rate of less than 0.2%. There was only one maternal death that was attributed by the study authors to the use of magnesium sulfate among the 9556 women in the 24 studies. Conclusion Concerns about safety and toxicity from the use of magnesium sulfate

  20. Biological functions of iduronic acid in chondroitin/dermatan sulfate.

    Science.gov (United States)

    Thelin, Martin A; Bartolini, Barbara; Axelsson, Jakob; Gustafsson, Renata; Tykesson, Emil; Pera, Edgar; Oldberg, Åke; Maccarana, Marco; Malmstrom, Anders

    2013-05-01

    The presence of iduronic acid in chondroitin/dermatan sulfate changes the properties of the polysaccharides because it generates a more flexible chain with increased binding potentials. Iduronic acid in chondroitin/dermatan sulfate influences multiple cellular properties, such as migration, proliferation, differentiation, angiogenesis and the regulation of cytokine/growth factor activities. Under pathological conditions such as wound healing, inflammation and cancer, iduronic acid has diverse regulatory functions. Iduronic acid is formed by two epimerases (i.e. dermatan sulfate epimerase 1 and 2) that have different tissue distribution and properties. The role of iduronic acid in chondroitin/dermatan sulfate is highlighted by the vast changes in connective tissue features in patients with a new type of Ehler-Danlos syndrome: adducted thumb-clubfoot syndrome. Future research aims to understand the roles of the two epimerases and their interplay with the sulfotransferases involved in chondroitin sulfate/dermatan sulfate biosynthesis. Furthermore, a better definition of chondroitin/dermatan sulfate functions using different knockout models is needed. In this review, we focus on the two enzymes responsible for iduronic acid formation, as well as the role of iduronic acid in health and disease.

  1. ALTERED ENZYMATIC ACTIVITY OF LYSOZYMES BOUND TO VARIOUSLY SULFATED CHITOSANS

    Institute of Scientific and Technical Information of China (English)

    Hong-wei Wang; Lin Yuan; Tie-liang Zhao; He Huang; Hong Chen; Di Wu

    2012-01-01

    The purpose of this research is to investigate the effects of the variously sulfated chitosans on lysozyme activity and structure.It was shown that the specific enzymatic activity of lysozyme remained almost similar to the native protein after being bound to 6-O-sulfated chitosan (6S-chitosan) and 3,6-O-sulfated chitosan (3,6S-chitosan),but decreased greatly after being bound to 2-N-6-O-sulfated chitosan (2,6S-chitosan).Meanwhile,among these sulfated chitosans,2,6S-chitosan induced the greatest conformational change in lysozyme as indicated by the fluorescence spectra.These findings demonstrated that when sulfated chitosans of different structures bind to lysozyme,lysozyme undergoes conformational change of different magnitudes,which results in corresponding levels of lysozyme activity.Further study on the interaction of sulfated chitosans with lysozyme by surface plasmon resonance (SPR) suggested that their affinities might be determined by their molecular structures.

  2. Reconstruction of secular variation in seawater sulfate concentrations

    Science.gov (United States)

    Algeo, T. J.; Luo, G. M.; Song, H. Y.; Lyons, T. W.; Canfield, D. E.

    2015-04-01

    Long-term secular variation in seawater sulfate concentrations ([SO42-]SW) is of interest owing to its relationship to the oxygenation history of Earth's surface environment. In this study, we develop two complementary approaches for quantification of sulfate concentrations in ancient seawater and test their application to late Neoproterozoic (635 Ma) to Recent marine units. The "rate method" is based on two measurable parameters of paleomarine systems: (1) the S-isotope fractionation associated with microbial sulfate reduction (MSR), as proxied by Δ34SCAS-PY, and (2) the maximum rate of change in seawater sulfate, as proxied by &partial; δ 34SCAS/∂ t(max). The "MSR-trend method" is based on the empirical relationship of Δ34SCAS-PY to aqueous sulfate concentrations in 81 modern depositional systems. For a given paleomarine system, the rate method yields an estimate of maximum possible [SO42-]SW (although results are dependent on assumptions regarding the pyrite burial flux, FPY), and the MSR-trend method yields an estimate of mean [SO42-]SW. An analysis of seawater sulfate concentrations since 635 Ma suggests that [SO42-]SW was low during the late Neoproterozoic (ocean anoxia, intense MSR, and pyrite burial. The procedures developed in this study offer potential for future high-resolution quantitative analyses of paleo-seawater sulfate concentrations.

  3. Regioselective sulfation of Artemisia sphaerocephala polysaccharide: Characterization of chemical structure.

    Science.gov (United States)

    Wang, Junlong; Yang, Wen; Wang, Jiancheng; Wang, Xia; Wu, Fang; Yao, Jian; Zhang, Ji; Lei, Ziqiang

    2015-11-20

    The biological activities of sulfated polysaccharides are related to the substitution positions of functional groups. In this study, regioselective sulfation of Artemisia sphaerocephala polysaccharides (SRSASP) was prepared by using triphenylchloromethane (TrCl) as protecting precursor. FT-IR spectra and X-ray photoelectron spectroscopy (XPS) showed that SO(3-) group (S(6+), high binding energy of 168.7eV) was widely present in sulfated polysaccharides. (13)C NMR spectroscopy showed that C-2 and C-3 substitution was occurred but not fully sulfation. Meanwhile, C-6 substituted signals near 65ppm were not observed. The degree of substitution varied from 0.44 to 0.63 in SRSASP which could be attributed to the low reactivity at secondary hydroxyl. Monosaccharide composition result showed a decrease in the ratio of mannose/glucose, indicating the change of chemical composition in sulfated polysaccharides. In size-exclusion chromatograph analysis, a decrease in molecular weight and broadening of molecular weight distribution of sulfated polysaccharides was also observed. It could be attributed to the hydrolysis of polysaccharide in the sulfated reaction.

  4. Sulfation patterns determine cellular internalization of heparin-like polysaccharides.

    Science.gov (United States)

    Raman, Karthik; Mencio, Caitlin; Desai, Umesh R; Kuberan, Balagurunathan

    2013-04-01

    Heparin is a highly sulfated polysaccharide that serves biologically relevant roles as an anticoagulant and anticancer agent. While it is well-known that modification of heparin's sulfation pattern can drastically influence its ability to bind growth factors and other extracellular molecules, very little is known about the cellular uptake of heparin and the role sulfation patterns serve in affecting its internalization. In this study, we chemically synthesized several fluorescently labeled heparins consisting of a variety of sulfation patterns. These polysaccharides were thoroughly characterized using anion exchange chromatography and size exclusion chromatography. Subsequently, we utilized flow cytometry and confocal imaging to show that sulfation patterns differentially affect the amount of heparin uptake in multiple cell types. This study provides the first comprehensive analysis of the effect of sulfation pattern on the cellular internalization of heparin or heparan sulfate like polysaccharides. The results of this study expand current knowledge regarding heparin internalization and provide insights into developing more effective heparin-based drug conjugates for applications in intracellular drug delivery.

  5. Structure versus anticoagulant and antithrombotic actions of marine sulfated polysaccharides

    Directory of Open Access Journals (Sweden)

    Vitor Hugo Pomin

    2012-08-01

    Full Text Available Marine sulfated polysaccharides (MSP, such as sulfated fucans (SF, sulfated galactans (SG and glycosaminoglycans (GAG isolated from either algae or invertebrate animals, are highly anionic polysaccharides capable of interacting with certain cationic proteins, such as (co-factors of the coagulation cascade during clotting-inhibition processes. These molecular complexes between MSP and coagulation-related proteins might, at first glance, be assumed to be driven mostly by electrostatic interactions. However, a systematic comparison using several novel sulfated polysaccharides composed of repetitive oligosaccharides with clear sulfation patterns has shown that these molecular interactions are regulated essentially by the stereochemistry of the glycans (which depends on a conjunction of anomericity, monosaccharide, conformational preference, and glycosylation and sulfation sites, rather than just a simple consequence of their negative charge density (mainly the number of sulfate groups. Here, we present an overview of the structure-function relationships of MSP, correlating their structures with their potential anticoagulant and antithrombotic actions, since pathologies related to the cardiovascular system are one of the major causes of illness and mortality in the world.

  6. Calcium channel antagonists in hypertension.

    Science.gov (United States)

    Ambrosioni, E; Borghi, C

    1989-02-01

    The clinical usefulness of calcium entry-blockers for the treatment of high blood pressure is related to their capacity to act upon the primary hemodynamic derangement in hypertension: the increased peripheral vascular resistance. They can be used alone or in combination with other antihypertensive agents for the treatment of various forms of hypertensive disease. The calcium entry-blockers appear to be the most useful agents for the treatment of hypertension in the elderly and for the treatment of hypertension associated with ischemic heart disease, pulmonary obstructive disease, peripheral vascular disease, and supraventricular arrhythmias. They are effective in reducing blood pressure in pregnancy-associated hypertension and must be considered as first-line therapy for the treatment of hypertensive crisis.

  7. The calcium-alkali syndrome

    OpenAIRE

    Arroyo, Mariangeli; Fenves, Andrew Z.; Emmett, Michael

    2013-01-01

    The milk-alkali syndrome was a common cause of hypercalcemia, metabolic alkalosis, and renal failure in the early 20th century. It was caused by the ingestion of large quantities of milk and absorbable alkali to treat peptic ulcer disease. The syndrome virtually vanished after introduction of histamine-2 blockers and proton pump inhibitors. More recently, a similar condition called the calcium-alkali syndrome has emerged as a common cause of hypercalcemia and alkalosis. It is usually caused b...

  8. Calcium phosphate polymer hybrid materials

    OpenAIRE

    2011-01-01

    Calcium phosphate (CaP) is of strong interest to the medical field because of its potential for bone repair, gene transfection, etc.1-3 Nowadays, the majority of the commercially available materials are fabricated via “classical” materials science approaches, i.e. via high temperature or high pressure approaches, from rather poorly defined slurries, or from organic solvents.3,4 Precipitation of inorganics with (polymeric) additives from aqueous solution on the other hand enables the synthesis...

  9. The influence of cloud droplet heterogeneity on sulfate production mechanisms constrained by isotopic measurements of sulfate aerosol

    Science.gov (United States)

    Alexander, B.; Allman, D. J.; Amos, H. M.; Fairlie, T. D.; Dachs, J.; Hegg, D.; Sletten, R. S.

    2011-12-01

    Observations and modeling studies have shown that heterogeneity in fog and cloud drop size and chemical composition can significantly impact in-cloud sulfate production rates due to the strong pH dependence of the ozone oxidation pathway. Averaging cloud water pH tends to underestimate the fraction of S(IV) that is SO32- leading to underestimates of in-cloud sulfate production rates. Large scale models typically do not account for this heterogeneity due to the large computational expense associated with this calculation, and instead employ bulk calculations or assumptions of cloud water pH. Modeling studies have consistently shown that calculated sulfate production rates using bulk cloud pH treatments tend to underestimate in-cloud sulfate production rates compared to more explicit treatment of cloud drop heterogeneity by underestimating the ozone oxidation pathway. Here, we utilize a global chemical transport model (GEOS-Chem) and observations of the oxygen isotopic composition of sulfate aerosol collected during a ship cruise in the subtropical northeast Atlantic Ocean to quantify sulfate formation pathways in the marine boundary layer. The oxygen isotopic composition of sulfate aerosol is particularly sensitive to the importance of the ozone oxidation pathway due to its large isotopic signature. We employ a model parameterization by Yuen et al. (1996) that accounts for the impact of alkaline, coarse-mode sea salt aerosols on in-cloud sulfate production rates. As sulfate formation in cloud droplets formed on alkaline coarse-mode sea salt aerosols is thought to be dominated by the ozone oxidation pathway, observations of the oxygen isotopic composition of sulfate aerosol provide a robust test of this parameterization. Including the Yuen et al. (1996) parameterization of cloud droplet heterogeneity improves the model's agreement with the observed sulfate oxygen isotopes. Accounting for the impact of cloud droplet heterogeneity on in-cloud sulfate production rates

  10. Localized sulfate-reducing zones in a coastal plain aquifer

    Science.gov (United States)

    Brown, C.J.; Coates, J.D.; Schoonen, M.A.A.

    1999-01-01

    High concentrations of dissolved iron in ground water of coastal plain or alluvial aquifers contribute to the biofouling of public supply wells for which treatment and remediation is costly. Many of these aquifers, however, contain zones in which microbial sulfate reduction and the associated precipitation of iron-sulfide minerals decreases iron mobility. The principal water-bearing aquifer (Magothy Aquifer of Cretaceous age) in Suffolk County, New York, contains localized sulfate-reducing zones in and near lignite deposits, which generally are associated with clay lenses. Microbial analyses of core samples amended with [14C]-acetate indicate that microbial sulfate reduction is the predominant terminal-electron-accepting process (TEAP) in poorly permeable, lignite-rich sediments at shallow depths and near the ground water divide. The sulfate-reducing zones are characterized by abundant lignite and iron-sulfide minerals, low concentrations of Fe(III) oxyhydroxides, and by proximity to clay lenses that contain pore water with relatively high concentrations of sulfate and dissolved organic carbon. The low permeability of these zones and, hence, the long residence time of ground water within them, permit the preservation and (or) allow the formation of iron-sulfide minerals, including pyrite and marcasite. Both sulfate-reducing bacteria (SRB) and iron-reducing bacteria (IRB) are present beneath and beyond the shallow sulfate-reducing zones. A unique Fe(III)-reducing organism, MD-612, was found in core sediments from a depth of 187 m near the southern shore of Long Island. The distribution of poorly permeable, lignite-rich, sulfate-reducing zones with decreased iron concentration is varied within the principal aquifer and accounts for the observed distribution of dissolved sulfate, iron, and iron sulfides in the aquifer. Locating such zones for the placement of production wells would be difficult, however, because these zones are of limited aerial extent.

  11. Evolutionary relationships and functional diversity of plant sulfate transporters

    Directory of Open Access Journals (Sweden)

    Hideki eTakahashi

    2012-01-01

    Full Text Available Sulfate is an essential nutrient cycled in nature. Ion transporters that specifically facilitate the transport of sulfate across the membranes are found ubiquitously in living organisms. The phylogenetic analysis of known sulfate transporters and their homologous proteins from eukaryotic organisms indicate two evolutionarily distinct groups of sulfate transport systems. One major group named Tribe 1 represents yeast and fungal SUL, plant SULTR and animal SLC26 families. The evolutionary origin of SULTR family members in land plants and green algae is suggested to be common with yeast and fungal sulfate transporters (SUL and animal anion exchangers (SLC26. The lineage of plant SULTR family is expanded into four subfamilies (SULTR1 to SULTR4 in land plant species. By contrast, the putative SULTR homologues from Chlorophyte green algae are in two separate lineages; one with the subfamily of plant tonoplast-localized sulfate transporters (SULTR4, and the other diverged before the appearance of lineages for SUL, SULTR and SLC26. There also was a group of yet undefined members of putative sulfate transporters in yeast and fungi divergent from these major lineages in Tribe 1. The other distinct group is Tribe 2, primarily composed of animal sodium-dependent sulfate/carboxylate transporters (SLC13 and plant tonoplast-localized dicarboxylate transporters (TDT. The putative sulfur-sensing protein (SAC1 and SAC1-like transporters (SLT of Chlorophyte green algae, bryophyte and lycophyte show low degrees of sequence similarities with SLC13 and TDT. However, the phylogenetic relationship between SAC1/SLT and the other two families, SLC13 and TDT in Tribe 2, is not clearly supported. In addition, the SAC1/SLT family is completely absent in the angiosperm species analyzed. The present study suggests distinct evolutionary trajectories of sulfate transport systems for land plants and green algae.

  12. 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.

  13. Store-Operated Calcium Channels.

    Science.gov (United States)

    Prakriya, Murali; Lewis, Richard S

    2015-10-01

    Store-operated calcium channels (SOCs) are a major pathway for calcium signaling in virtually all metozoan cells and serve a wide variety of functions ranging from gene expression, motility, and secretion to tissue and organ development and the immune response. SOCs are activated by the depletion of Ca(2+) from the endoplasmic reticulum (ER), triggered physiologically through stimulation of a diverse set of surface receptors. Over 15 years after the first characterization of SOCs through electrophysiology, the identification of the STIM proteins as ER Ca(2+) sensors and the Orai proteins as store-operated channels has enabled rapid progress in understanding the unique mechanism of store-operate calcium entry (SOCE). Depletion of Ca(2+) from the ER causes STIM to accumulate at ER-plasma membrane (PM) junctions where it traps and activates Orai channels diffusing in the closely apposed PM. Mutagenesis studies combined with recent structural insights about STIM and Orai proteins are now beginning to reveal the molecular underpinnings of these choreographic events. This review describes the major experimental advances underlying our current understanding of how ER Ca(2+) depletion is coupled to the activation of SOCs. Particular emphasis is placed on the molecular mechanisms of STIM and Orai activation, Orai channel properties, modulation of STIM and Orai function, pharmacological inhibitors of SOCE, and the functions of STIM and Orai in physiology and disease.

  14. Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfateβ-1→3GalNAc(4-Sulfateβ-1→] motifs in dermatan sulfate on heparin cofactor II activity

    Directory of Open Access Journals (Sweden)

    Sugahara Kazuyuki

    2011-05-01

    Full Text Available Abstract Background Previously, we have reported the presence of highly sulfated dermatans in solitary ascidians from the orders Phlebobranchia (Phallusia nigra and Stolidobranchia (Halocynthia pyriformis and Styela plicata. Despite the identical disaccharide backbone, consisting of [→4IdoA(2Sβ-1→3GalNAcβ-1→], those polymers differ in the position of sulfation on the N-Acetyl galactosamine, which can occur at carbon 4 or 6. We have shown that position rather than degree of sulfation is important for heparin cofactor II activity. As a consequence, 2,4- and 2,6-sulfated dermatans have high and low heparin cofactor II activities, respectively. In the present study we extended the disaccharide analysis of ascidian dermatan sulfates to additional species of the orders Stolidobranchia (Herdmania pallida, Halocynthia roretzi and Phlebobranchia (Ciona intestinalis, aiming to investigate how sulfation evolved within Tunicata. In addition, we analysed how heparin cofactor II activity responds to dermatan sulfates containing different proportions of 2,6- or 2,4-disulfated units. Results Disaccharide analyses indicated a high content of disulfated disaccharide units in the dermatan sulfates from both orders. However, the degree of sulfation decreased from Stolidobranchia to Phlebobranchia. While 76% of the disaccharide units in dermatan sulfates from stolidobranch ascidians are disulfated, 53% of disulfated disaccharides are found in dermatan sulfates from phlebobranch ascidians. Besides this notable difference in the sulfation degree, dermatan sulfates from phlebobranch ascidians contain mainly 2,6-sulfated disaccharides whereas dermatan sulfate from the stolidobranch ascidians contain mostly 2,4-sulfated disaccharides, suggesting that the biosynthesis of dermatan sulfates might be differently regulated during tunicates evolution. Changes in the position of sulfation on N-acetylgalactosamine in the disaccharide [→4IdoA(2-Sulfateβ-1→3GalNAcβ-1

  15. Isolation, purification, and characterization of fucose-containing sulfated polysaccharides from the brown seaweed Ecklonia kurome and their blood-anticoagulant activities.

    Science.gov (United States)

    Nishino, T; Yokoyama, G; Dobashi, K; Fujihara, M; Nagumo, T

    1989-02-15

    A sulfated polysaccharide fraction, obtained from the hot-water extract of the brown seaweed, Ecklonia kurome by removing laminaran and the major part of alginic acid, gave sulfated polysaccharides (B-I, B-II, C-I, and C-II) by both anion-exchange chromatography on a column of Ecteola-cellulose and by fractional precipitation with ethanol containing 0.3% calcium acetate, and then by gel-filtration chromatography on a Sepharose 4B column. B-I and B-II are composed of fucose, galactose, mannose, xylose, glucuronic acid, and ester sulfate in the approximate molar ratios of 1.00:0.36:0.48:1.08:1.85:2.35 and 1.00:0.81:0.18:0.45:0.61:2.00, respectively. C-I and C-II are composed of fucose, galactose, glucuronic acid, and ester sulfate in approximate molar ratios of 1.00:0.03:0.03:1.61 and 1.00:0.19:0.07:1.48, respectively. Blood-anticoagulant activities with respect to activated partial thromboplastin time (APTT) were approximately 24, 19, 81, and 85% of that of heparin for B-I, B-II, C-I, and C-II, respectively. All the polysaccharides showed slight antithrombin activity. No antifactor Xa activity was observed for any of the polysaccharides.

  16. Incorporation of Monovalent Cations in Sulfate Green Rust

    DEFF Research Database (Denmark)

    Christiansen, B. C.; Dideriksen, K.; Katz, A.;

    2014-01-01

    Green rust is a naturally occurring layered mixed-valent ferrous-ferric hydroxide, which can react with a range of redox-active compounds. Sulfate-bearing green rust is generally thought to have interlayers composed of sulfate and water. Here, we provide evidence that the interlayers also contain...... with water showed that Na+ and K+ were structurally fixed in the interlayer, whereas Rb+ and Cs+ could be removed, resulting in a decrease in the basal layer spacing. The incorporation of cations in the interlayer opens up new possibilities for the use of sulfate green rust for exchange reactions with both...

  17. Commercial Application of Technique for Removing Sulfates from Reforming Catalyst

    Institute of Scientific and Technical Information of China (English)

    JiChangqing

    2002-01-01

    In the course of reduction of reforming catalyst by not hydrogen a certain amount of chlorine containing compounds is added to the recycle hydrogen to facilitate the reduction of sulfates.The outcome of commercial application of this technique has revealed that the procedure of "regeneration by chlorination→reduction→sulfate removal→sulfiding and oil feed-in"aimed at sulate removal is very simple and can recover the reaction activity of reforming catalyst after having been poisoned by sulfates.This procedure can be disseminated for application in refineries.

  18. Sulfated oligosaccharide structures, as determined by NMR techniques

    Energy Technology Data Exchange (ETDEWEB)

    Noseda, M.D.; Duarte, M.E.R.; Tischer, C.A.; Gorin, P.A.J. [Parana Univ., Curitiba, PR (Brazil). Dept. De Bioquimica; Cerezo, A.S. [Buenos Aires Univ. Nacional (Argentina). Dept. de Quimica Organica

    1997-12-31

    Carrageenans are sulfated polysaccharides, produced by red seaweeds (Rhodophyta), that have important biological and physico-chemical properties. Using partial autohydrolysis, we obtained sulfated oligosaccharides from a {lambda}-carrageenan (Noseda and Cerezo, 1993). These oligosaccharides are valuable not only for the study of the structures of the parent carrageenans but also for their possible biological activities. In this work we determined the chemical structure of one of the sulfated oligosaccharides using 1D and 2D NMR techniques. (author) 4 refs., 8 figs., 1 tabs.

  19. Damage modelling in concrete subject to sulfate attack

    Directory of Open Access Journals (Sweden)

    N. Cefis

    2014-07-01

    Full Text Available In this paper, we consider the mechanical effect of the sulfate attack on concrete. The durability analysis of concrete structures in contact to external sulfate solutions requires the definition of a proper diffusion-reaction model, for the computation of the varying sulfate concentration and of the consequent ettringite formation, coupled to a mechanical model for the prediction of swelling and material degradation. In this work, we make use of a two-ions formulation of the reactive-diffusion problem and we propose a bi-phase chemo-elastic damage model aimed to simulate the mechanical response of concrete and apt to be used in structural analyses.

  20. Preparation and characterization of mesoporous tetragonal sulfated zirconia

    Institute of Scientific and Technical Information of China (English)

    Chun Xia He; Bin Yue; Ji Fang Cheng; Wei Ming Hua; Ying Hong Yue; He Yong He

    2009-01-01

    Mesoporous tetragonal sulfated zirconia with high surface area and narrow pore-size distribution was prepared using Zr(O-nPr)4 as zirconium precursor, sulfuric acid as sulfur source and triblock copolymer poly(ethylene glycol)-poly(propylene glycol)poly(ethylene glycol) (P123) as the template. The samples were characterized by X-ray diffraction, N2 sorption, TEM, and NH3TPD. A phase transformation from monoclinic sulfated zirconia to tetragonal sulfated zirconia is observed. The product shows strong acidity.

  1. Micro-SHINE Uranyl Sulfate Irradiations at the Linac

    Energy Technology Data Exchange (ETDEWEB)

    Youker, Amanda J. [Argonne National Lab. (ANL), Argonne, IL (United States); Kalensky, Michael [Argonne National Lab. (ANL), Argonne, IL (United States); Chemerisov, Sergey [Argonne National Lab. (ANL), Argonne, IL (United States); Schneider, John [Argonne National Lab. (ANL), Argonne, IL (United States); Byrnes, James [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-08-01

    Peroxide formation due to water radiolysis in a uranyl sulfate solution is a concern for the SHINE Medical Technologies process in which Mo-99 is generated from the fission of dissolved low enriched uranium. To investigate the effects of power density and fission on peroxide formation and uranyl-peroxide precipitation, uranyl sulfate solutions were irradiated using a 50-MeV electron linac as part of the micro-SHINE experimental setup. Results are given for uranyl sulfate solutions with both high and low enriched uranium irradiated at different linac powers.

  2. —Part I. Interaction of Calcium and Copper-Calcium Alloy with Electrolyte

    Science.gov (United States)

    Zaikov, Yurii P.; Batukhtin, Victor P.; Shurov, Nikolay I.; Ivanovskii, Leonid E.; Suzdaltsev, Andrey V.

    2014-06-01

    This paper describes the interaction between calcium and molten CaCl2 and the solubility of calcium in this melt, depending on the calcium content in the copper-calcium alloy that comes in contact with the molten CaCl2. The negative influence of the dissolved calcium on the current efficiency was verified. The negative effects of moisture and CaO impurities on the calcium current efficiency were demonstrated. The dependence of the current efficiency and the purity of the metal obtained by the electrolysis conditions were studied in a laboratory electrolyzer (20 to 80 A).

  3. Autogenous vein graft thrombosis following exposure to calcium-free solutions (calcium paradox).

    Science.gov (United States)

    Nozick, J H; Farnsworth, P; Montefusco, C M; Parsonnet, V; Ruigrok, T J; Zimmerman, A N

    1981-01-01

    The morphological and functional effects of calcium-free and calcium-containing solutions on canine jugular vein intima were examined under conditions which closely resemble those techniques currently employed in peripheral vascular and aortocoronary bypass surgery. Veins that had been exposed only to calcium-containing solutions remained patent for the duration of the experimental period. Vein perfusion with a calcium-free solution, however, resulted in disruption of the jugular vein intima once calcium ions were reintroduced. Autogenous as a femoral arterial graft became thrombosed within 60 minutes. It is therefore suggested that vein grafts of autogenous origin be irrigated with calcium-containing solutions to prevent intimal damage and thrombosis.

  4. Vitamin D-enhanced duodenal calcium transport.

    Science.gov (United States)

    Wongdee, Kannikar; Charoenphandhu, Narattaphol

    2015-01-01

    For humans and rodents, duodenum is a very important site of calcium absorption since it is exposed to ionized calcium released from dietary complexes by gastric acid. Calcium traverses the duodenal epithelium via both transcellular and paracellular pathways in a vitamin D-dependent manner. After binding to the nuclear vitamin D receptor, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] upregulates the expression of several calcium transporter genes, e.g., TRPV5/6, calbindin-D9k, plasma membrane Ca(2+)-ATPase1b, and NCX1, thereby enhancing the transcellular calcium transport. This action has been reported to be under the regulation of parathyroid-kidney-intestinal and bone-kidney-intestinal axes, in which the plasma calcium and fibroblast growth factor-23 act as negative feedback regulators, respectively. 1,25(OH)2D3 also modulates the expression of tight junction-related genes and convective water flow, presumably to increase the paracellular calcium permeability and solvent drag-induced calcium transport. However, vitamin D-independent calcium absorption does exist and plays an important role in calcium homeostasis under certain conditions, particularly in neonatal period, pregnancy, and lactation as well as in naturally vitamin D-impoverished subterranean mammals.

  5. 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.

  6. Calcium channel as a potential anticancer agent.

    Science.gov (United States)

    Kriazhev, L

    2009-11-01

    Anticancer treatment in modern clinical practices includes chemotherapy and radiation therapy with or without surgical interventions. Efficiency of both methods varies greatly depending on cancer types and stages. Besides, chemo- and radiotherapy are toxic and damaging that causes serious side effects. This fact prompts the search for alternative methods of antitumor therapy. It is well known that prolonged or high increase of intracellular calcium concentration inevitably leads to the cell death via apoptosis or necrosis. However, stimulation of cell calcium level by chemical agents is hardly achievable because cells have very sophisticated machinery for maintaining intracellular calcium in physiological ranges. This obstacle can be overridden, nevertheless. It was found that calcium channels in so called calcium cells in land snails are directly regulated by extracellular calcium concentration. The higher the concentration the higher the calcium intake is through the channels. Bearing in mind that extracellular/intracellular calcium concentration ratio in human beings is 10,000-12,000 fold the insertion of the channel into cancer cells would lead to fast and uncontrollable by the cells calcium intake and cell death. Proteins composing the channel may be extracted from plasma membrane of calcium cells and sequenced by mass-spectrometry or N-terminal sequencing. Either proteins or corresponding genes could be used for targeted delivery into cancer cells.

  7. Monitoring sulfide and sulfate-reducing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, R.S.

    1995-12-31

    Simple yet precise and accurate methods for monitoring sulfate-reducing bacteria (SRB) and sulfide remain useful for the study of bacterial souring and corrosion. Test kits are available to measure sulfide in field samples. A more precise methylene blue sulfide assay for both field and laboratory studies is described here. Improved media, compared to that in API RP-38, for enumeration of SRB have been formulated. One of these, API-RST, contained cysteine (1.1 mM) as a reducing agent, which may be a confounding source of sulfide. While cysteine was required for rapid enumeration of SRB from environmental samples, the concentration of cysteine in medium could be reduced to 0.4 mM. It was also determined that elevated levels of yeast extract (>1 g/liter) could interfere with enumeration of SRB from environmental samples. The API-RST medium was modified to a RST-11 medium. Other changes in medium composition, in addition to reduction of cysteine, included reduction of the concentration of phosphate from 3.4 mM to 2.2 mM, reduction of the concentration of ferrous iron from 0.8 mM to 0.5 mM and preparation of a stock mineral solution to ease medium preparation. SRB from environmental samples could be enumerated in a week in this medium.

  8. Application of Box-Behnken design to prepare gentamicin-loaded calcium carbonate nanoparticles.

    Science.gov (United States)

    Maleki Dizaj, Solmaz; Lotfipour, Farzaneh; Barzegar-Jalali, Mohammad; Zarrintan, Mohammad-Hossein; Adibkia, Khosro

    2016-09-01

    The aim of this research was to prepare and optimize calcium carbonate (CaCO3) nanoparticles as carriers for gentamicin sulfate. A chemical precipitation method was used to prepare the gentamicin sulfate-loaded CaCO3 nanoparticles. A 3-factor, 3-level Box-Behnken design was used for the optimization procedure, with the molar ratio of CaCl2: Na2CO3 (X1), the concentration of drug (X2), and the speed of homogenization (X3) as the independent variables. The particle size and entrapment efficiency were considered as response variables. Mathematical equations and response surface plots were used, along with the counter plots, to relate the dependent and independent variables. The results indicated that the speed of homogenization was the main variable contributing to particle size and entrapment efficiency. The combined effect of all three independent variables was also evaluated. Using the response optimization design, the optimized Xl-X3 levels were predicted. An optimized formulation was then prepared according to these levels, resulting in a particle size of 80.23 nm and an entrapment efficiency of 30.80%. It was concluded that the chemical precipitation technique, together with the Box-Behnken experimental design methodology, could be successfully used to optimize the formulation of drug-incorporated calcium carbonate nanoparticles.

  9. Extraction of beryllium sulfate by a long chain amine; Extraction du sulfate de beryllium par une amine a longue chaine

    Energy Technology Data Exchange (ETDEWEB)

    Etaix, E.S. [Commissariat a l' Energie Atomique, Fontenay-Aux-Roses (France). Centre d' Etudes Nucleaires

    1968-06-01

    The extraction of sulfuric acid in aqueous solution by a primary amine in benzene solution, 3-9 (diethyl) - 6-amino tri-decane (D.E.T. ) - i.e., with American nomenclature 1-3 (ethyl-pentyl) - 4-ethyl-octyl amine (E.P.O.) - has made it possible to calculate the formation constants of alkyl-ammonium sulfate and acid sulfate. The formula of the beryllium and alkyl-ammonium sulfate complex formed in benzene has next been determined, for various initial acidity of the aqueous solution. Lastly, evidence has been given of negatively charged complexes of beryllium and sulfate in aqueous solution, through the dependence of the aqueous sulfate ions concentration upon beryllium extraction. The formation constant of these anionic complexes has been evaluated. (author) [French] L'etude de l'extraction de l'acide sulfurique en solution aqueuse par une amine primaire en solution dans le benzene, le diethyl-3,9 amino-6 tridecane (D.E.T.) - autre nom americain 1-3 (ethylpentyl) - 4-ethyloctylamine (E.P.O.) a permis de calculer les constantes de formation du sulfate et de l'hydrogenosulfate d'alkyl-ammonium. La formule du complexe de sulfate de beryllium et d'alkyl-ammonium forme en solution benzenique a ete ensuite determinee pour diverses acidites initiales de la solution aqueuse. Enfin, l'influence de la concentration des ions sulfate de la phase aqueuse sur l'extraction du beryllium a mis en evidence la formation en solution aqueuse de complexes anioniques de sulfate et de beryllium dont la constante de formation a ete evaluee. (auteur)

  10. Characterisation of Ba(OH){sub 2}–Na{sub 2}SO{sub 4}–blast furnace slag cement-like composites for the immobilisation of sulfate bearing nuclear wastes

    Energy Technology Data Exchange (ETDEWEB)

    Mobasher, Neda; Bernal, Susan A.; Hussain, Oday H. [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom); Apperley, David C. [Solid-State NMR Group, Department of Chemistry, Durham University, Durham DH1 3LE (United Kingdom); Kinoshita, Hajime [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom); Provis, John L., E-mail: j.provis@sheffield.ac.uk [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2014-12-15

    Soluble sulfate ions in nuclear waste can have detrimental effects on cementitious wasteforms and disposal facilities based on Portland cement. As an alternative, Ba(OH){sub 2}–Na{sub 2}SO{sub 4}–blast furnace slag composites are studied for immobilisation of sulfate-bearing nuclear wastes. Calcium aluminosilicate hydrate (C–A–S–H) with some barium substitution is the main binder phase, with barium also present in the low solubility salts BaSO{sub 4} and BaCO{sub 3}, along with Ba-substituted calcium sulfoaluminate hydrates, and a hydrotalcite-type layered double hydroxide. This reaction product assemblage indicates that Ba(OH){sub 2} and Na{sub 2}SO{sub 4} act as alkaline activators and control the reaction of the slag in addition to forming insoluble BaSO{sub 4}, and this restricts sulfate availability for further reaction as long as sufficient Ba(OH){sub 2} is added. An increased content of Ba(OH){sub 2} promotes a higher degree of reaction, and the formation of a highly cross-linked C–A–S–H gel. These Ba(OH){sub 2}–Na{sub 2}SO{sub 4}–blast furnace slag composite binders could be effective in the immobilisation of sulfate-bearing nuclear wastes.

  11. Correction: Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfateβ-1→3GalNAc(4-Sulfateβ-1→] motifs in dermatan sulfate on heparin cofactor II activity

    Directory of Open Access Journals (Sweden)

    Sugahara Kazuyuki

    2011-07-01

    Full Text Available Abstract After the publication of the work entitled "Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfateβ-1→3GalNAc(4-Sulfateβ-1→] motifs in dermatan sulfate on heparin cofactor II activity", by Kozlowski et al., BMC Biochemistry 2011, 12:29, we found that the legends to Figures 2 to 5 contain serious mistakes that compromise the comprehension of the work. This correction article contains the correct text of the legends to Figures 2 to 5.

  12. Wound healing and antibacterial activities of chondroitin sulfate- and acharan sulfate-reduced silver nanoparticles

    Science.gov (United States)

    Im, A.-Rang; Kim, Jee Young; Kim, Hyun-Seok; Cho, Seonho; Park, Youmie; Kim, Yeong Shik

    2013-10-01

    For topical applications in wound healing, silver nanoparticles (AgNPs) have attracted much attention as antibacterial agents. Herein, we describe a green-synthetic route for the production of biocompatible and crystalline AgNPs using two glycosaminoglycans, chondroitin sulfate (CS) and acharan sulfate (AS), as reducing agents. The synthetic approach avoids the use of toxic chemicals, and the yield of AgNPs formation is found to be 98.1% and 91.1% for the chondroitin sulfate-reduced silver nanoparticles (CS-AgNPs) and the acharan sulfate-reduced silver nanoparticles (AS-AgNPs), respectively. Nanoparticles with mostly spherical and amorphous shapes were observed, with an average diameter of 6.16 ± 2.26 nm for CS-AgNPs and 5.79 ± 3.10 nm for AS-AgNPs. Images of the CS-AgNPs obtained from atomic force microscopy revealed the self-assembled structure of CS was similar to a densely packed woven mat with AgNPs sprinkled on the CS. These nanoparticles were stable under cell culture conditions without any noticeable aggregation. An approximately 128-fold enhancement of the antibacterial activities of the AgNPs was observed against Enterobacter cloacae and Escherichia coli when compared to CS and AS alone. In addition, an in vivo animal model of wound healing activity was tested using mice that were subjected to deep incision wounds. In comparison to the controls, the ointments containing CS-AgNPs and AS-AgNPs stimulated wound closure under histological examination and accelerated the deposition of granulation tissue and collagen in the wound area. The wound healing activity of the ointments containing CS-AgNPs and AS-AgNPs are comparable to that of a commercial formulation of silver sulfadiazine even though the newly prepared ointments contain a lower silver concentration. Therefore, the newly prepared AgNPs demonstrate potential for use as an attractive biocompatible nanocomposite for topical applications in the treatment of wounds.

  13. 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.

  14. Fortification of all-purpose wheat-flour tortillas with calcium lactate, calcium carbonate, or calcium citrate is acceptable.

    Science.gov (United States)

    Romanchik-Cerpovicz, Joelle E; McKemie, Rebecca J

    2007-03-01

    Fortification helps provide adequate nutrients for individuals not meeting daily needs. Foods may be fortified with calcium to assist individuals with lactose intolerance and others preferring not to consume traditional forms of dairy. This study examined the quality of all-purpose wheat-flour tortillas fortified with calcium lactate, calcium carbonate, or calcium citrate. These tortillas were compared to similarly prepared nonfortified flour tortillas (control) and commercial nonfortified flour tortillas. Calcium-fortified tortillas contained 114 mg elemental calcium per standard serving (48 g tortilla), an 8.6-fold increase compared to nonfortified tortillas. Moisture contents and rollabilities of all tortillas were similar. Consumers (N=87) evaluated each tortilla in duplicate using a hedonic scale and reported liking the appearance, texture, flavor, aftertaste, and overall acceptability of all tortillas. However, the appearance of control tortillas was preferred over commercial tortillas (P<0.01), whereas the aftertaste of commercial tortillas or those fortified with calcium carbonate was preferred over the control (P<0.05). Despite these differences, consumers were equally willing to purchase both fortified and nonfortified tortillas, suggesting that appearance and aftertaste may not influence willingness to purchase. Overall, this study shows that fortification of flour tortillas with various forms of calcium is a feasible alternative calcium source.

  15. Vincristine-sulphate-loaded liposome-templated calcium phosphate nanoshell as potential tumor-targeting delivery system.

    Science.gov (United States)

    Thakkar, Hetal Paresh; Baser, Amit Kumar; Parmar, Mayur Prakashbhai; Patel, Ketul Harshadbhai; Ramachandra Murthy, Rayasa

    2012-06-01

    Vincristine-sulfate-loaded liposomes were prepared with an aim to improve stability, reduce drug leakage during systemic circulation, and increase intracellular uptake. Liposomes were prepared by the thin-film hydration method, followed by coating with calcium phosphate, using the sequential addition approach. Prepared formulations were characterized for size, zeta potential, drug-entrapment efficiency, morphology by transmission electron microscopy (TEM), in vitro drug-release profile, and in vitro cell cytotoxicity study. Effect of formulation variables, such as drug:lipid ratio as well as nature and volume of hydration media, were found to affect drug entrapment, and the concentration of calcium chloride in coating was found to affect size and coating efficiency. Size, zeta potential, and TEM images confirmed that the liposomes were effectively coated with calcium phosphate. The calcium phosphate nanoshell exhibited pH-dependent drug release, showing significantly lower release at pH 7.4, compared to the release at pH 4.5, which is the pH of the tumor interstitium. The in vitro cytotoxicity study done on the lung cancer cell line indicated that coated liposomes are more cytotoxic than plain liposomes and drug solution, indicating their potential for intracellular drug delivery. The cell-uptake study done on the lung cancer cell line indicated that calcium-phosphate-coated liposomes show higher cell uptake than uncoated liposomes.

  16. Heparan sulfate proteoglycans in extravasation : assisting leukocyte guidance

    NARCIS (Netherlands)

    Celie, Johanna W. A. M.; Beelen, Robert H. J.; van den Born, Jacob

    2009-01-01

    Heparan sulfate proteoglycans (HSPGs) are glycoconjugates that are implicated in various biological processes including development, inflammation and repair, which is based on their capacity to bind and present several proteins via their carbohydrate side chains (glycosaminoglycans; GAGs). Well-know

  17. ROE Wet Sulfate Deposition Raster 2011-2013

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet sulfate deposition in kilograms per hectare from 2011 to 2013. Summary data in this indicator were provided by EPA’s...

  18. ROE Wet Sulfate Deposition Raster 1989-1991

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet sulfate deposition in kilograms per hectare from 1989 to 1991. Summary data in this indicator were provided by EPA’s...

  19. Specificities of Ricinus communis agglutinin 120 interaction with sulfated galactose.

    Science.gov (United States)

    Wang, Yufeng; Yu, Guangli; Han, Zhangrun; Yang, Bo; Hu, Yannan; Zhao, Xia; Wu, Jiandong; Lv, Youjing; Chai, Wengang

    2011-12-15

    Lectins are used extensively as research tools to detect and target specific oligosaccharide sequences. Ricinus communis agglutinin I (RCA(120)) recognizes non-reducing terminal β-D-galactose (Galβ) and its specificities of interactions with neutral and sialylated oligosaccharides have been well documented. Here we use carbohydrate arrays of sulfated Galβ-containing oligosaccharide probes, prepared from marine-derived galactans, to investigate their interactions with RCA(120). Our results showed that RCA(120) binding to Galβ1-4 was enhanced by 2-O- or 6-O-sulfation but abolished by 4-O-sulfation. The results were corroborated with competition experiments. Erythrina cristagalli lectin is also a Galβ-binding protein but it cannot accommodate any sulfation on Galβ.

  20. Calcium Impact on Milk Gels Formation

    DEFF Research Database (Denmark)

    Koutina, Glykeria

    and dense gel structure and with little seperation of whey due to participation of calcium to the final gel structure. On the other hand, the combination of heat treatment and calcium addition to milk with pH values lower than 5.6 will still produce gel structures which are dominated by the decrease of p......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...

  1. 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.

  2. Dextran sulfate inhibits acute Toxoplama gondii infection in pigs

    OpenAIRE

    2016-01-01

    Background Toxoplasma gondii is a highly prevalent protozoan that can infect all warm-blooded animals, including humans. Its definitive hosts are Felidae and its intermediate hosts include various other mammals and birds, including pigs. It is found in the meat of livestock which is a major source of human infection. Hence the control of toxoplasmosis in pigs is important for public health. We previously showed that dextran sulfate (DS), especially DS10 (dextran sulfate MW 10 kDa), is effecti...

  3. A New Ursane type Sulfated Saponin from Zygophyllum fabago Linn.

    Directory of Open Access Journals (Sweden)

    Saleha Suleman Khan

    2014-07-01

    Full Text Available One new sulfated saponin 3β,23,30-trihydroxyurs-20-en-28-al-23-sulfate 3-O-β- D -xylopyranoside (Zygofaboside C; 1 was purified from the water soluble fraction of ethanolic extract of the aerial parts of Zygophyllum fabago Linn. The structure of the compound was elucidated through spectral studies, especially 1D- and 2D-NMR, HR-FAB mass spectrometry, and comparison with literature data.

  4. Biotechnological aspects of sulfate reduction with methane as electron donor

    OpenAIRE

    Meulepas, R.J.W.; Stams, A.J.M.; Lens, P. N L

    2010-01-01

    Biological sulfate reduction can be used for the removal and recovery of oxidized sulfur compounds and metals from waste streams. However, the costs of conventional electron donors, like hydrogen and ethanol, limit the application possibilities. Methane from natural gas or biogas would be a more attractive electron donor. Sulfate reduction with methane as electron donor prevails in marine sediments. Recently, several authors succeeded in cultivating the responsible microorganisms in vitro. In...

  5. Immunohistochemical localization of chondroitin sulfate, chondroitin sulfate proteoglycan, heparan sulfate proteoglycan, entactin, and laminin in basement membranes of postnatal developing and adult rat lungs

    DEFF Research Database (Denmark)

    Sannes, P L; Burch, K K; Khosla, J

    1993-01-01

    alveolar, airway, and vascular BMs, in addition to smooth muscle external laminae (EL), in the adult and developing rat. Immunostaining for CSPG required hyaluronidase digestion, whereas CS staining was lost with the same treatment. A polyclonal antibody to the core protein of HSPG was found...... to be similarly distributed to CSPG by immunoperoxidase staining in adult and developing rat lungs, with the notable exception that little immunoreactivity for HSPG was found in smooth muscle EL. Commercially obtained polyclonal antibodies to entactin and laminin gave immunostaining comparable to that seen......Histologic preparations of lungs from 1-, 5-, 10-, 18-, and 25-day-old postnatal and adult rats were examined immunohistochemically with antibodies specific against chondroitin sulfate (CS), basement membrane chondroitin sulfate proteoglycan (BM-CSPG), heparan sulfate proteoglycan (HSPG), entactin...

  6. Reaction of calcium-based sorbents with sulfur compounds during gasification. Final report, 1 October 1986-30 June 1991

    Energy Technology Data Exchange (ETDEWEB)

    Abbasian, J.; Rehmat, A.

    1991-12-01

    The report outlines the objectives and the data obtained under the project related to the efficient utilization of high-sulfur Illinois coal in a One-Step Coal Gasification/Desulfurization Process by employing in-situ removal of sulfur using calcium-based sorbents. The research was supported jointly by the Gas Research Institute and the State of Illinois Center for Research on Sulfur in Coal. The scope of the research included a study of fluidization behavior of coal char/sorbent mixtures and the reactions of calcium-based sorbents with sulfur present in the coal during gasification as well as sulfation of the sulfided sorbents. The test parameters included the choice of sorbent, sorbent size, the effect of temperature and pressure, and the reactant gas composition on the sulfidation and sulfation reactions. The reaction conditions for these reactions were chosen to be applicable to scale-up of an in-situ desulfurization-type coal gasification process such as the one proposed by the Institute of Gas Technology (IGT) and KRW Energy Systems, Inc., of the U.S.A. A PC-based computer model was developed that is capable of describing a fluidized-bed gasifier with in-bed calcium-based sorbents.

  7. Sulfur-accumulating plants convert sulfate salts from soils into environmentally resilient biominerals

    Science.gov (United States)

    Robson, Thomas; Reid, Nathan; Stevens, Jason; Dixon, Kingsley

    2016-04-01

    Sulfur-accumulator plants (thiophores), which accumulate atypically high sulfur and calcium concentrations in their aerial biomass, may be suitable for revegetating and phytostabilising reactive sulfur-enriched substrates such as mine tailings, acid-sulfate soils and polluted soils. We present biogeochemical insights on thiophores from the Australian Great Sandy Desert, which accumulate up to 40 times as much sulfur (2-5 %S) versus comparator species. X-ray microanalyses revealed this accumulation relates to peculiar gypsum-like mineralisation throughout their foliage, illustrating a mechanism for sulfate removal from soils and sequestration as sparingly soluble biominerals. However, we did not know whether these species treat the excess Ca/S as a waste to be shed with senescent litter and, if so, how resilient these 'biominerals' are to photo-biodegradation once shed and so to what extent the accumulated elements are recycled back into the reactive/bioavailable sulfate reservoir. To address these questions, we sampled four foliage (phyllode) fractions from ten individuals of the thiophore, Acacia bivenosa: healthy mature phyllodes, senescent phyllodes on the branch, recently shed and older, more degraded ground litter. We selected two thiophores (A. bivenosa and A. robeorum) and a non-thiophore (A. ancistrocarpa) for detailed soil/regolith studies. Samples were collected from trenches bisected by each tree, taken from varying depth (20-500 mm) and distance from the stem (0.1-5 m). Dried foliage was cleaned, sectioned for SEM-EDXS examination and elemental compositions of foliage and soils were determined (microwave-assisted acid digestion + ICP-OES/MS). Each species generated a 'halo' of elevated S/Ca in the soil immediately beneath their crowns, although that of A. ancistrocarpa was of minor magnitude. These anomalies were confined to shallow soil (20-50 mm i.e. influenced by litter), suggesting limited S/Ca re-mobilisation from the litter. Foliar elemental

  8. Effects of potassium sulfate [K2SO4] on the element contents, polyphenol content, antioxidant and antimicrobial activities of milk thistle [Silybum marianum

    Directory of Open Access Journals (Sweden)

    Gulsum Yaldiz

    2017-01-01

    Abbreviations used: AlCl3: aluminum chloride, Ca+2: calcium, Cl-: chloride, Cr: chromium CE: catechol equivalents, DPPH: 2,2-diphenylpicrylhydrazyl, ABTS: 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid, DAP: diamonyum fosfat, F-: fluoride, Fe: iron, K2SO4: potassium sulfate, K+ : potassium, Li+: lithium, Mg+2 : magnesium, NH4+ : amonyum, Na+: sodium, NO2-: nitrite, NO3-: nitrate, Ni: nickel, NaNO2: sodium nitrite, NaOH: sodium hidroksit. ND: Not detectable, PO4-3: phosphorus, Zn: zinc

  9. CITRIC ACID AS A SET RETARDER FOR CALCIUM ALUMINATE PHOSPHATE CEMENTS.

    Energy Technology Data Exchange (ETDEWEB)

    SUGAMA,T.; BROTHERS, L.E.

    2005-01-01

    Citric acid added as set retarder significantly contributed to enhancing the setting temperature and to extending the thickening time of a calcium aluminate phosphate (CaP) geothermal cement slurry consisting of calcium aluminate cement (CAC) as the base reactant and sodium polyphosphate (NaP) solution as the acid reactant. The set-retarding activity of citric acid was due to the uptake of Ca{sup 2+} ions from the CAC by carboxylic acid groups within the citric acid. This uptake led to the precipitation of a Ca-complexed carboxylate compound as a set-retarding barrier layer on the CAC grains' surfaces. However, this barrier layer was vulnerable to disintegration by the attack of free Ca{sup 2+} ions from CAC, and also to degradation at elevated temperature, thereby promoting the generation of exothermic energy from acid-base reactions between the CAC and NaP after the barrier was broken. The exothermic reaction energy that was promoted in this way minimized the loss in strength of the citric acid-retarded cement. The phase composition assembled in both retarded and non-retarded cements after autoclaving at 180 C encompassed three reaction products, hydroxyapatite (HOAp), hydrogrossular and boehmite, which are responsible for strengthening the autoclaved cement. The first two reaction products were susceptible to reactions with sulfuric acid and sodium sulfate to form crystalline bassanite scale as the corrosion product. The boehmite phase possessed a great resistance to acid and sulfate. Although the bassanite scales clinging to the cement's surfaces were the major factor governing the loss in weight, they served in protecting the cement from further acid- and sulfate-corrosion until their spallation eventually occurred. Nevertheless, the repetitive processes of HOAp and hydrogrossular {yields} bassanite {yields} spallation played an important role in extending the useful lifetime of CaP cement in a low pH environment at 180 C.

  10. Overbased Calcium sulfonate Detergent Technology Overview

    Institute of Scientific and Technical Information of China (English)

    MA Qing-gao; MUIR Ronald J.

    2009-01-01

    Overbased calcium sulfonate is used widely as detergent in automotive and marine lubricants, as well as various industrial oil applications. In this paper, the process to produce overbased calcium sulfonate is overviewed. The sulfonate structure and molecular weight and its molecular weight distribution, the enclosed calcium carbonate nanoparticle size and crystalline structure, properties of the carrier oil, all influence its properties, such as stability, viscosity, and detergency of the system.

  11. [Calcium carbide of different crystal formation synthesized by calcium carbide residue].

    Science.gov (United States)

    Lu, Zhong-yuan; Kang, Ming; Jiang, Cai-rong; Tu, Ming-jing

    2006-04-01

    To recycle calcium carbide residue effectively, calcium carbide of different crystal form, including global aragonite, calcite and acicular calcium carbide was synthesized. Both the influence of pretreatment in the purity of calcium carbide, and the influence of temperatures of carbonization reaction, release velocity of carbon dioxide in the apparition of calcium carbide of different crystal form were studied with DTA-TG and SEM. The result shows that calcium carbide residue can take place chemistry reaction with ammonia chlorinate straight. Under the condition that pH was above 7, the purity of calcium carbide was above 97%, and the whiteness was above 98. Once provided the different temperatures of carbonization reaction and the proper release velocity of carbon dioxide, global aragonite, calcite and acicular calcium carbide were obtained.

  12. Persistent sulfate formation from London Fog to Chinese haze

    Science.gov (United States)

    Wang, Gehui; Zhang, Renyi; Gomez, Mario E.; Yang, Lingxiao; Levy Zamora, Misti; Hu, Min; Lin, Yun; Peng, Jianfei; Guo, Song; Meng, Jingjing; Li, Jianjun; Cheng, Chunlei; Hu, Tafeng; Ren, Yanqin; Wang, Yuesi; Gao, Jian; Cao, Junji; An, Zhisheng; Zhou, Weijian; Li, Guohui; Wang, Jiayuan; Tian, Pengfei; Marrero-Ortiz, Wilmarie; Secrest, Jeremiah; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Zeng, Limin; Shao, Min; Wang, Weigang; Huang, Yao; Wang, Yuan; Zhu, Yujiao; Li, Yixin; Hu, Jiaxi; Pan, Bowen; Cai, Li; Cheng, Yuting; Ji, Yuemeng; Zhang, Fang; Rosenfeld, Daniel; Liss, Peter S.; Duce, Robert A.; Kolb, Charles E.; Molina, Mario J.

    2016-11-01

    Sulfate aerosols exert profound impacts on human and ecosystem health, weather, and climate, but their formation mechanism remains uncertain. Atmospheric models consistently underpredict sulfate levels under diverse environmental conditions. From atmospheric measurements in two Chinese megacities and complementary laboratory experiments, we show that the aqueous oxidation of SO2 by NO2 is key to efficient sulfate formation but is only feasible under two atmospheric conditions: on fine aerosols with high relative humidity and NH3 neutralization or under cloud conditions. Under polluted environments, this SO2 oxidation process leads to large sulfate production rates and promotes formation of nitrate and organic matter on aqueous particles, exacerbating severe haze development. Effective haze mitigation is achievable by intervening in the sulfate formation process with enforced NH3 and NO2 control measures. In addition to explaining the polluted episodes currently occurring in China and during the 1952 London Fog, this sulfate production mechanism is widespread, and our results suggest a way to tackle this growing problem in China and much of the developing world.

  13. Stratospheric sulfate geoengineering impacts on global agriculture

    Science.gov (United States)

    Xia, L.; Robock, A.; Lawrence, P.; Lombardozzi, D.

    2015-12-01

    Stratospheric sulfate geoengineering has been proposed to reduce the impacts of anthropogenic climate change. If it is ever used, it would change agricultural production, and so is one of the future climate scenarios for the third phase of the Global Gridded Crop Model Intercomparison. As an example of those impacts, we use the Community Land Model (CLM-crop 4.5) to simulate how climate changes from the G4 geoengineering scenario from the Geoengineering Modeling Intercomparison Project. The G4 geoengineering scenario specifies, in combination with RCP4.5 forcing, starting in 2020 daily injections of a constant amount of SO2 at a rate of 5 Tg SO2 per year at one point on the Equator into the lower stratosphere. Eight climate modeling groups have completed G4 simulations. We use the crop model to simulate the impacts of climate change (temperature, precipitation, and solar radiation) on the global agriculture system for five crops - rice, maize, soybeans, cotton, and sugarcane. In general, without irrigation, compared with the reference run (RCP4.5), global production of cotton, rice and sugarcane would increase significantly due to the cooling effect. Maize and soybeans show different regional responses. In tropical regions, maize and soybean have a higher yield in G4 compared with RCP4.5, while in the temperate regions they have a lower yield under a geoengineered climate. Impacts on specific countries in terms of different crop production depend on their locations. For example, the United States and Argentina show soybean production reduction of about 15% under G4 compared to RCP4.5, while Brazil increases soybean production by about 10%.

  14. Osteoblasts detect pericellular calcium concentration increase via neomycin-sensitive voltage gated calcium channels.

    Science.gov (United States)

    Sun, Xuanhao; Kishore, Vipuil; Fites, Kateri; Akkus, Ozan

    2012-11-01

    The mechanisms underlying the detection of critically loaded or micro-damaged regions of bone by bone cells are still a matter of debate. Our previous studies showed that calcium efflux originates from pre-failure regions of bone matrix and MC3T3-E1 osteoblasts respond to such efflux by an increase in the intracellular calcium concentration. The mechanisms by which the intracellular calcium concentration increases in response to an increase in the pericellular calcium concentration are unknown. Elevation of the intracellular calcium may occur via release from the internal calcium stores of the cell and/or via the membrane bound channels. The current study applied a wide range of pharmaceutical inhibitors to identify the calcium entry pathways involved in the process: internal calcium release from endoplasmic reticulum (ER, inhibited by thapsigargin and TMB-8), calcium receptor (CaSR, inhibited by calhex), stretch-activated calcium channel (SACC, inhibited by gadolinium), voltage-gated calcium channels (VGCC, inhibited by nifedipine, verapamil, neomycin, and ω-conotoxin), and calcium-induced-calcium-release channel (CICRC, inhibited by ryanodine and dantrolene). These inhibitors were screened for their effectiveness to block intracellular calcium increase by using a concentration gradient induced calcium efflux model which mimics calcium diffusion from the basal aspect of cells. The inhibitor(s) which reduced the intracellular calcium response was further tested on osteoblasts seeded on mechanically loaded notched cortical bone wafers undergoing damage. The results showed that only neomycin reduced the intracellular calcium response in osteoblasts, by 27%, upon extracellular calcium stimulus induced by concentration gradient. The inhibitory effect of neomycin was more pronounced (75% reduction in maximum fluorescence) for osteoblasts seeded on notched cortical bone wafers loaded mechanically to damaging load levels. These results imply that the increase in

  15. Calcium binding proteins and calcium signaling in prokaryotes.

    Science.gov (United States)

    Domínguez, Delfina C; Guragain, Manita; Patrauchan, Marianna

    2015-03-01

    With the continued increase of genomic information and computational analyses during the recent years, the number of newly discovered calcium binding proteins (CaBPs) in prokaryotic organisms has increased dramatically. These proteins contain sequences that closely resemble a variety of eukaryotic calcium (Ca(2+)) binding motifs including the canonical and pseudo EF-hand motifs, Ca(2+)-binding β-roll, Greek key motif and a novel putative Ca(2+)-binding domain, called the Big domain. Prokaryotic CaBPs have been implicated in diverse cellular activities such as division, development, motility, homeostasis, stress response, secretion, transport, signaling and host-pathogen interactions. However, the majority of these proteins are hypothetical, and only few of them have been studied functionally. The finding of many diverse CaBPs in prokaryotic genomes opens an exciting area of research to explore and define the role of Ca(2+) in organisms other than eukaryotes. This review presents the most recent developments in the field of CaBPs and novel advancements in the role of Ca(2+) in prokaryotes.

  16. Disease causing mutations of calcium channels.

    Science.gov (United States)

    Lorenzon, Nancy M; Beam, Kurt G

    2008-01-01

    Calcium ions play an important role in the electrical excitability of nerve and muscle, as well as serving as a critical second messenger for diverse cellular functions. As a result, mutations of genes encoding calcium channels may have subtle affects on channel function yet strongly perturb cellular behavior. This review discusses the effects of calcium channel mutations on channel function, the pathological consequences for cellular physiology, and possible links between altered channel function and disease. Many cellular functions are directly or indirectly regulated by the free cytosolic calcium concentration. Thus, calcium levels must be very tightly regulated in time and space. Intracellular calcium ions are essential second messengers and play a role in many functions including, action potential generation, neurotransmitter and hormone release, muscle contraction, neurite outgrowth, synaptogenesis, calcium-dependent gene expression, synaptic plasticity and cell death. Calcium ions that control cell activity can be supplied to the cell cytosol from two major sources: the extracellular space or intracellular stores. Voltage-gated and ligand-gated channels are the primary way in which Ca(2+) ions enter from the extracellular space. The sarcoplasm reticulum (SR) in muscle and the endoplasmic reticulum in non-muscle cells are the main intracellular Ca(2+) stores: the ryanodine receptor (RyR) and inositol-triphosphate receptor channels are the major contributors of calcium release from internal stores.

  17. Regulation of cardiomyocyte autophagy by calcium.

    Science.gov (United States)

    Shaikh, Soni; Troncoso, Rodrigo; Criollo, Alfredo; Bravo-Sagua, Roberto; García, Lorena; Morselli, Eugenia; Cifuentes, Mariana; Quest, Andrew F G; Hill, Joseph A; Lavandero, Sergio

    2016-04-15

    Calcium signaling plays a crucial role in a multitude of events within the cardiomyocyte, including cell cycle control, growth, apoptosis, and autophagy. With respect to calcium-dependent regulation of autophagy, ion channels and exchangers, receptors, and intracellular mediators play fundamental roles. In this review, we discuss calcium-dependent regulation of cardiomyocyte autophagy, a lysosomal mechanism that is often cytoprotective, serving to defend against disease-related stress and nutrient insufficiency. We also highlight the importance of the subcellular distribution of calcium and related proteins, interorganelle communication, and other key signaling events that govern cardiomyocyte autophagy.

  18. Altered calcium signaling following traumatic brain injury

    Directory of Open Access Journals (Sweden)

    John Thomas Weber

    2012-04-01

    Full Text Available Cell death and dysfunction after traumatic brain injury (TBI is caused by a primary phase, related to direct mechanical disruption of the brain, and a secondary phase which consists of delayed events initiated at the time of the physical insult. Arguably, the calcium ion contributes greatly to the delayed cell damage and death after TBI. A large, sustained influx of calcium into cells can initiate cell death signaling cascades, through activation of several degradative enzymes, such as proteases and endonucleases. However, a sustained level of intracellular free calcium is not necessarily lethal, but the specific route of calcium entry may couple calcium directly to cell death pathways. Other sources of calcium, such as intracellular calcium stores, can also contribute to cell damage. In addition, calcium-mediated signal transduction pathways in neurons may be perturbed following injury. These latter types of alterations may contribute to abnormal physiology in neurons that do not necessarily die after a traumatic episode. This review provides an overview of experimental evidence that has led to our current understanding of the role of calcium signaling in death and dysfunction following TBI.

  19. Sintering of calcium phosphate bioceramics.

    Science.gov (United States)

    Champion, E

    2013-04-01

    Calcium phosphate ceramics have become of prime importance for biological applications in the field of bone tissue engineering. This paper reviews the sintering behaviour of these bioceramics. Conventional pressureless sintering of hydroxyapatite, Ca10(PO4)6(OH)2, a reference compound, has been extensively studied. Its physico-chemistry is detailed. It can be seen as a competition between two thermally activated phenomena that proceed by solid-state diffusion of matter: densification and grain growth. Usually, the objective is to promote the first and prevent the second. Literature data are analysed from sintering maps (i.e. grain growth vs. densification). Sintering trajectories of hydroxyapatite produced by conventional pressureless sintering and non-conventional techniques, including two-step sintering, liquid phase sintering, hot pressing, hot isostatic pressing, ultrahigh pressure, microwave and spark plasma sintering, are presented. Whatever the sintering technique may be, grain growth occurs mainly during the last step of sintering, when the relative bulk density reaches 95% of the maximum value. Though often considered very advantageous, most assisted sintering techniques do not appear very superior to conventional pressureless sintering. Sintering of tricalcium phosphate or biphasic calcium phosphates is also discussed. The chemical composition of calcium phosphate influences the behaviour. Similarly, ionic substitutions in hydroxyapatite or in tricalcium phosphate create lattice defects that modify the sintering rate. Depending on their nature, they can either accelerate or slow down the sintering rate. The thermal stability of compounds at the sintering temperature must also be taken into account. Controlled atmospheres may be required to prevent thermal decomposition, and flash sintering techniques, which allow consolidation at low temperature, can be helpful.

  20. Thermodestruction of complex sulfates of iridium and ruthenium in sulfate solutions at 100-180 deg C

    Energy Technology Data Exchange (ETDEWEB)

    Sinitsyn, N.M.; Godzhiev, S.E.; Blagodatin, Yu.V. (Moskovskij Inst. Tonkoj Khimicheskoj Tekhnologii (USSR))

    1983-12-01

    Thermodestruction of iridium- and ruthenium complex sulfates in sulfate solutions is studied at 100-180 deg C depending on the solution acidity, hold time, element initial chemical form in the solution, salt background. The complex ruthenium sulfates are shown to be destroyed during high-temperature solution holding with the solid phase formation, the rate of platinum metal transfer into a precipitate increasing with the temperature, hold time and pH of the source solution. Depending on the initial chemical form the thermodestruction proceeds in various ways and leads to the formation of either hydroxides or solid phase ''proper'' of the platinium metal salt. A reduced tendency to high-temperature hydrolysis of complex ruthenium sulfates at the +3 oxidation level is noted.