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Sample records for samarium silicates

  1. Optical analysis of samarium doped sodium bismuth silicate glass.

    Science.gov (United States)

    Thomas, V; Sofin, R G S; Allen, M; Thomas, H; Biju, P R; Jose, G; Unnikrishnan, N V

    2017-01-15

    Samarium doped sodium bismuth silicate glass was synthesized using the melt quenching method. Detailed optical spectroscopic studies of the glassy material were carried out in the UV-Vis-NIR spectral range. Using the optical absorption spectra Judd-Ofelt (JO) parameters are derived. The calculated values of the JO parameters are utilized in evaluating the various radiative parameters such as electric dipole line strengths (Sed), radiative transition probabilities (Arad), radiative lifetimes (τrad), fluorescence branching ratios (β) and the integrated absorption cross- sections (σa) for stimulated emission from various excited states of Sm3+‡ ion. The principal fluorescence transitions are identified by recording the fluorescence spectrum. Our analysis revealed that the novel glassy system has the optimum values for the key parameters viz. spectroscopic quality factor, optical gain, stimulated emission cross section and quantum efficiency, which are required for a high performance optical amplifier. Calculated chromaticity co-ordinates (0.61, 0.38) also confirm its application potential in display devices. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Synthesis of Samarium Cobalt Nanoblades

    Energy Technology Data Exchange (ETDEWEB)

    Darren M. Steele

    2010-08-25

    As new portable particle acceleration technologies become feasible the need for small high performance permanent magnets becomes critical. With particle accelerating cavities of a few microns, the photonic crystal fiber (PCF) candidate demands magnets of comparable size. To address this need, samarium cobalt (SmCo) nanoblades were attempted to be synthesized using the polyol process. Since it is preferable to have blades of 1-2 {micro}m in length, key parameters affecting size and morphology including method of stirring, reaction temperature, reaction time and addition of hydroxide were examined. Nanoparticles consisting of 70-200 nm spherical clusters with a 3-5 nm polyvinylpyrrolidone (PVP) coating were synthesized at 285 C and found to be ferromagnetic. Nanoblades of 25nm in length were observed at the surface of the nanoclusters and appeared to suggest agglomeration was occurring even with PVP employed. Morphology and size were characterized using a transmission electron microscope (TEM). Powder X-Ray Diffraction (XRD) analysis was conducted to determine composition but no supportive evidence for any particular SmCo phase has yet been observed.

  3. Behavior of Samarium III during the sorption process; Comportamiento del Samario-III durante el proceso de sorcion

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez R, E.; Garcia G, N.; Garcia R, G. [ININ, Carr. Mexico-Toluca Km 36.5, Salazar, Estado de Mexico (Mexico)]. e-mail: edo@nuclear.inin.mx

    2004-07-01

    In this work the results of the behavior of samarium in solution are presented, in front of a fine powder of zirconium silicate (zircon). For that which is necessary to characterize the zircon, studying the crystallinity, the morphology, the surface area and the isoelectric point. The behavior of samarium in solution is studied by means of the elaboration of isotherm of sorption, using the technique by lots. One observes that to pH values of nearer to the isoelectric point (pH = 7.23) the process of sorption of the samarium begins, reaching a maximum to near pH at 9. The technique of luminescence is used to determine the concentration of the sipped samarium (phosphorescence) and also to make the speciation of the species formed in the surface of the zircon (phosphorescence). The results can be extrapolated with the plutonium when making the modeling of the migration of alpha emitting coming from the repositories of radioactive waste since both they have similar chemical properties (they are homologous). (Author)

  4. Particle-Size-Induced Valence Changes in Samarium Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Mason, M. G.; Lee, S. -T.; Apai, G.; Davis, R. F.; Shirley, D. A.; Franciosi, A.; Weaver, J. H.

    1981-09-01

    Samarium clusters exhibit mixed-valence behavior which is sensitive to particle size. XPS and UPS data show samarium to be primarily divalent (4f{sup 6} ) at small particle size. The trivalent state (4f{sup 5} ) becomes progressively more abundant with increasing s1ze, becoming the dominant state for the bulk metal. These results are interpreted using a model in which band narrowing, due to reduced surface coordination, is more dominant than surface tension effects in establishing the valence of small samarium clusters.

  5. Yellow-green electroluminescence of samarium complexes of 8-hydroxyquinoline

    Energy Technology Data Exchange (ETDEWEB)

    Behzad, Sara Karimi; Najafi, Ezzatollah [Department of Chemistry Shahid Beheshti University G.C., Tehran 1983963113 (Iran, Islamic Republic of); Amini, Mostafa M., E-mail: m-pouramini@sbu.ac.ir [Department of Chemistry Shahid Beheshti University G.C., Tehran 1983963113 (Iran, Islamic Republic of); Janghouri, Mohammad; Mohajerani, Ezeddin [Laser Research Institute Shahid Beheshti University G.C., Tehran 1983963113 (Iran, Islamic Republic of); Ng, Seik Weng [Department of Chemistry, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-12-15

    Four novel samarium complexes were prepared by reacting samarium(III) nitrate with 8-hydroxyquinoline, 2-methyl-8-hydroxyquinoline, and 1,10-phenanthroline and utilized as emitting materials in the electroluminescence device. All complexes were characterized by elemental analysis, infrared, UV–vis and {sup 1}H NMR spectroscopes and the molecular structure of a representative complex, [Sm{sub 2}(Me-HQ){sub 4}(NO{sub 3}){sub 6}] (1), was determined by single-crystal X-ray diffraction. Utilization of a π-conjugated (phenanthroline) ligand as a second ligand in the structure of the samarium complexes resulted in red shifts in both absorption and fluorescence spectra of complexes and moderately enhanced the photoluminescence intensity and the fluorescence quantum yield. The maximum emission peaks showed that a good correlation exists between the nature of the substituent group on the 8-hydroxyquinoline and the addition of the π-conjugated ligand in the structure of samarium complexes and emission wavelength. Devices with samarium(III) complexes with structure of ITO/PEDOT:PSS (90 nm)/PVK:PBD:Sm(III) complexes (75 nm)/Al (180 nm) were fabricated. In the electroluminescence (EL) spectra of the devices, a strong ligand-centered emission and narrow bands arising from the {sup 4}G{sub 5/2}→{sup 6}H{sub J} transitions (J=7/2, 9/2, and 11/2) of the samarium ion were observed for the complexes. The electroluminescent spectra of the samarium complexes were red-shifted as compared with the PVK:PBD blend. We believe that the electroluminescence performance of OLED devices based on samarium complexes relies on overlaps between the absorption of the samarium compounds and the emission of PVK:PBD. This revealed that it is possible to evaluate the electroluminescence performance of the samarium compounds-doped OLED devices based on the emission of PVK:PBD and the absorption of the dopants. - Highlights: • Four novel photoluminescence samarium complexes have been synthesized.

  6. Biodistribution of samarium-153-EDTMP in rats treated with docetaxel

    Energy Technology Data Exchange (ETDEWEB)

    Villarim Neto, Arthur; Acucena, Maria Kadja Meneses Torres; Pereira, Kercia Regina Santos Gomes; Rego, Amalia Cinthia Meneses [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Postgraduate Program in Health Sciences; Azevedo, Italo Medeiros; Medeiros, Aldo Cunha [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Dept. of Surgery; Bernardo-Filho, Mario [State University of Rio de Janeiro, RJ (Brazil). Dept. of Biophysics and Biometry

    2009-01-15

    Purpose: Many patients with metastatic bone disease have to use radiopharmaceuticals associated with chemotherapy to relieve bone pain. The aim of this study was to assess the influence of docetaxel on the biodistribution of samarium-153-EDTMP in bones and other organs of rats. Methods: Wistar male rats were randomly allocated into 2 groups of 6 rats each. The DS (docetaxel/samarium) group received docetaxel (15 mg/kg) intraperitoneally in two cycles 11 days apart. The S (samarium/control) group rats were not treated with docetaxel. Nine days after chemotherapy, all the rats were injected with 0.1 ml of samarium-153-EDTMP via orbital plexus (25 {mu} Ci. After 2 hours, the animals were killed and samples of the brain, thyroid, lung, heart, stomach, colon, liver, kidney and both femurs were removed. The percentage radioactivity of each sample (% ATI / g) was determined in an automatic gamma-counter (Wizard-1470, Perkin-Elmer, Finland). Results: On the ninth day after the administration of the second chemotherapy cycle, the rats had a significant weight loss (314.50 +- 22.09 g) compared (p<0.5) to pre-treatment weight (353.66 {+-} 22.8). The % ATI/g in the samples of rats treated with samarium-153-EDTMP had a significant reduction in the right femur, left femur, kidney, liver and lungs of animals treated with docetaxel, compared to the control rats. Conclusion: The combination of docetaxel and samarium-153-EDTMP was associated with a lower response rate in the biodistribution of the radiopharmaceutical to targeted tissues. Further investigation into the impact of docetaxel on biodistribution of samarium-153-EDTMP would complement the findings of this study. (author)

  7. The Basis for Developing Samarium AMS for Fuel Cycle Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, B A; Biegalski, S R; Whitney, S M; Tumey, S J; Weaver, C J

    2008-10-13

    Modeling of nuclear reactor fuel burnup indicates that the production of samarium isotopes can vary significantly with reactor type and fuel cycle. The isotopic concentrations of {sup 146}Sm, {sup 149}Sm, and {sup 151}Sm are potential signatures of fuel reprocessing, if analytical techniques can overcome the inherent challenges of lanthanide chemistry, isobaric interferences, and mass/charge interferences. We review the current limitations in measurement of the target samarium isotopes and describe potential approaches for developing Sm-AMS. AMS sample form and preparation chemistry will be discussed as well as possible spectrometer operating conditions.

  8. Optical characteristics of transparent samarium oxide thin films ...

    Indian Academy of Sciences (India)

    Optical characteristics of transparent samarium oxide thin films deposited by the radio-frequency sputtering technique. A A ATTA M M EL-NAHASS KHALED M ELSABAWY M M ABD EL-RAHEEM A M HASSANIEN A ALHUTHALI ALI BADAWI AMAR MERAZGA. Regular Volume 87 Issue 5 November 2016 Article ID 72 ...

  9. Optical properties of zinc–vanadium glasses doped with samarium ...

    Indian Academy of Sciences (India)

    Zinc–vanadium glasses doped with samarium oxide having the chemical composition Sm2O3() ZnO(40-)V2O5(60) (where = 0.1–0.5 mol%) were prepared by melt quenching method. The density of these glasses was measured by Archimedes method; the corresponding molar volumes have also been calculated.

  10. Optical properties of samarium doped zinc–tellurite glasses

    Indian Academy of Sciences (India)

    Unknown

    Optical properties of samarium doped zinc–tellurite glasses. B ERAIAH. Department of Physics, Karnatak University, Dharwad 580 003, India. Present address: Department of Physics, Bangalore University, Bangalore 560 056, India. MS received 20 March 2006; revised 13 June 2006. Abstract. Glasses with the composition, ...

  11. Effect of second ligand on the luminescence of Samarium (III ...

    Indian Academy of Sciences (India)

    Effect of second ligand on the luminescence of Samarium (III) dibenzoylmethane complexes: Syntheses, crystal structures, thermal analysis and luminescence study. MUHAMMAD IDIRIS SALEH, MIN YEE CHOO, TAI WEI CHAN and MOHD R RAZALI. ∗. School of Chemical Sciences, Universiti Sains Malaysia, Penang, ...

  12. Effect of second ligand on the luminescence of Samarium (III ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 127; Issue 12. Effect of second ligand on the luminescence of Samarium (III) dibenzoylmethane complexes: ... Muhammad Idiris Saleh1 Min Yee Choo1 Tai Wei Chan1 Mohd R Razali1. School of Chemical Sciences, Universiti Sains Malaysia, Penang, Malaysia ...

  13. Dependence of samarium-soil interaction on samarium concentration: Implications for environmental risk assessment.

    Science.gov (United States)

    Ramírez-Guinart, Oriol; Salaberria, Aitor; Vidal, Miquel; Rigol, Anna

    2018-03-01

    The sorption and desorption behaviour of samarium (Sm), an emerging contaminant, was examined in soil samples at varying Sm concentrations. The obtained sorption and desorption parameters revealed that soil possessed a high Sm retention capacity (sorption was higher than 99% and desorption lower than 2%) at low Sm concentrations, whereas at high Sm concentrations, the sorption-desorption behaviour varied among the soil samples tested. The fractionation of the Sm sorbed in soils, obtained by sequential extractions, allowed to suggest the soil properties (pH and organic matter solubility) and phases (organic matter, carbonates and clay minerals) governing the Sm-soil interaction. The sorption models constructed in the present work along with the sorption behaviour of Sm explained in terms of soil main characteristics will allow properly assessing the Sm-soil interaction depending on the contamination scenario under study. Moreover, the sorption and desorption K d values of radiosamarium in soils were strongly correlated with those of stable Sm at low concentrations (r = 0.98); indicating that the mobility of Sm radioisotopes and, thus, the risk of radioactive Sm contamination can be predicted using data from low concentrations of stable Sm. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Mechanism of the electrochemical deposition of samarium-based coatings

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, Edgar J. [Electrochemistry Department, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Parque Tecnologico Queretaro Sanfandila, P.O. Box 064, Pedro Escobedo, 76700 Queretaro (Mexico); Ortega-Borges, Raul [Electrochemistry Department, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Parque Tecnologico Queretaro Sanfandila, P.O. Box 064, Pedro Escobedo, 76700 Queretaro (Mexico); Godinez, Luis A. [Electrochemistry Department, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Parque Tecnologico Queretaro Sanfandila, P.O. Box 064, Pedro Escobedo, 76700 Queretaro (Mexico); Chapman, Thomas W. [Electrochemistry Department, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Parque Tecnologico Queretaro Sanfandila, P.O. Box 064, Pedro Escobedo, 76700 Queretaro (Mexico); Meas-Vong, Yunny [Electrochemistry Department, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Parque Tecnologico Queretaro Sanfandila, P.O. Box 064, Pedro Escobedo, 76700 Queretaro (Mexico)]. E-mail: yunnymeas@cideteq.mx

    2006-11-12

    Samarium-based films have been shown to form from aqueous solutions on the surfaces of metallic substrates such as steel or aluminum, and their presence has been reported to decrease substantially the corresponding corrosion rate of the underlying metallic substrate. Based on previous reports on the deposition of oxides or hydroxides of the closely related element cerium, this work demonstrates that samarium films are formed following a similar mechanism, which involves as the fundamental step an increase in interfacial pH resulting from cathodic oxygen-reduction or hydrogen-evolution reactions. With cyclic voltammetry (CV), electrochemical quartz-crystal microbalance (EQCM) measurements, rotating-disk electrode (RDE) tests, and surface characterization techniques, namely, scanning electron microscopy (SEM) and X-ray surface microanalysis (EDX), the postulated mechanism was verified, and the surface morphology of the resulting films was correlated with the nature of the reduction reaction that triggers film formation.

  15. Samarium Monosulfide (SmS): Reviewing Properties and Applications

    OpenAIRE

    Sousanis, Andreas; Smet, Philippe; Poelman, Dirk

    2017-01-01

    In this review, we give an overview of the properties and applications of samarium monosulfide, SmS, which has gained considerable interest as a switchable material. It shows a pressure-induced phase transition from the semiconducting to the metallic state by polishing, and it switches back to the semiconducting state by heating. The material also shows a magnetic transition, from the paramagnetic state to an antiferromagnetically ordered state. The switching behavior between the semiconducti...

  16. Optical properties of zinc–vanadium glasses doped with samarium ...

    Indian Academy of Sciences (India)

    Abstract. Zinc–vanadium glasses doped with samarium oxide having the chemical composition Sm2O3(x). ZnO(40−x)V2O5(60)(where x = 0·1–0·5 mol%) were prepared by melt quenching method. The density of these glasses was measured by Archimedes method; the corresponding molar volumes have also been ...

  17. Synthesis of nano-pore samarium (III)-imprinted polymer for preconcentrative separation of samarium ions from other lanthanide ions via solid phase extraction

    Energy Technology Data Exchange (ETDEWEB)

    Shirvani-Arani, Simindokht [Center of Excellence in Electrochemistry, Department of Chemistry, University of Tehran, P.O.Box:14155-6455, Tehran (Iran, Islamic Republic of); Jaber Ibne Hayan Research Laboratories, Nuclear Science and Technology Research Institute, P.O. Box: 11365-8486, Tehran (Iran, Islamic Republic of); Ahmadi, Seyed Javad [Jaber Ibne Hayan Research Laboratories, Nuclear Science and Technology Research Institute, P.O. Box: 11365-8486, Tehran (Iran, Islamic Republic of)], E-mail: sjahmadi@aeoi.org.ir; Bahrami-Samani, Ali [Nuclear Engineering and Physics Department, Amir Kabir University, P.O.Box: 15875-4413, Tehran (Iran, Islamic Republic of); Jaber Ibne Hayan Research Laboratories, Nuclear Science and Technology Research Institute, P.O. Box: 11365-8486, Tehran (Iran, Islamic Republic of); Ghannadi-Maragheh, Mohammad [Jaber Ibne Hayan Research Laboratories, Nuclear Science and Technology Research Institute, P.O. Box: 11365-8486, Tehran (Iran, Islamic Republic of)

    2008-08-08

    A batch process was developed to separate samarium ions from some lanthanide ions by a novel solid phase which was prepared via the ion-imprinting technique. The samarium (III) ion-imprinted polymer (IIP) particles were synthesized by preparing the ternary complex of samarium ions with 5,7-dichloroquinoline-8-ol (DCQ) and 4-vinylpyridine (VP). Then, thermally copolymerization with styrene (functional monomer, STY) and divinylbenzene (cross-linking monomer, DVB) followed in the presence of 2-methoxy ethanol (porogen) and 2,2'-azobisisobutyronitrile (initiator, AIBN). The imprinted ion was removed by stirring the above particles with 50% (v/v) HCl to obtain the leached IIP particles. Moreover, control polymer (CP) particles were similarly prepared without the samarium ions. The unleached and leached IIP particles were characterized by X-ray diffraction (XRD), infra-red spectroscopy (IR), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). Finally, preconcentration and selectivity studies for samarium and the other lanthanide ions were carried out. The preconcentration of the samarium (III) traces was studied during rebinding with the leached IIP particles as a function of pH, the weight of the polymer material, the preconcentration and the elution times, the eluent volume and the aqueous phase volume. These studies indicated that the samarium (III) amount as low as 1 {mu}g, present in 200 mL, could be preconcentrated into 25 mL of 1.0 M HCl.

  18. Ionization of Samarium by Chemical Releases in the Upper Atmosphere

    Science.gov (United States)

    Siefring, C. L.; Bernhardt, P. A.; Holmes, J. M.; Pedersen, T. R.; Caton, R.; Miller, D.; Groves, K. M.

    2014-12-01

    The release of Samarium vapor into the upper atmosphere was studied using during the Air Force Research Laboratory sponsored Metal Oxide Space Cloud (MOSC) rocket launches in May 2009. The Naval Research Laboratory supported these experiments with 3-D photochemical modeling of the artificial plasma cloud including (1) reactions with atomic oxygen, (2) photo excitation, (3) photoionization, (4) dissociative recombination, and (5) ion and neutral diffusion. NRL provided the experimental diagnostic instrument on the rocket which was a dual frequency radio beacon on the rocket to measure changes in total electron content. The AFRL provided ground based diagnostics of incoherent scatter radar and optical spectroscopy and imagery. The NRL Chemical Release Model (CRM) has over 600 excited states of atomic Samarium neutrals, atomic ions, along with Samarium Oxide Ions and electrons. Diffusive transport of neutrals in cylindrical geometry and ions along magnetic field lines is computed along with the reactive flow to predict the concentrations of Sm, Sm-Ion, Sm0, and SmO Ion. Comparison of the CRM with observations demonstrates that Sm release into the upper atmosphere initially produces enhanced electron densities and SmO-Ions. The diatomic ions recombine with electrons to yield neutral Sm and O. Only the photo ionization of Sm yields a stable atomic ion that does not substantially recombine. The MOSC releases in sunlight yielded long duration ion clouds that can be replicated with the CRM. The CRM predicts that Sm releases in darkness would not produce long duration plasma clouds because of the lack of photo excitation and photoionization.

  19. Reactive Materials for Evaporating Samarium (Pre-Print)

    Science.gov (United States)

    2016-04-15

    SUBJECT TERMS energetic materials, heat sources, pyrotechnic charges, easily ionized metals 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...experiments.    Keywords:  energetic  materials, heat sources, pyrotechnic charges, easily ionized metals  1. Introduction Ejection of clouds of...results  were  negatively  affected  by  reduced  efficiency   of  release  and  ionization of samarium [8]. It is possible that not the entire charge of

  20. Implementation of an analytical technique for Samarium; Implementacion de una tecnica analitica para Samario

    Energy Technology Data Exchange (ETDEWEB)

    Garcia G, N. [ININ, Carretera Mexico-Toluca Km. 36.5, 52045 Estado de Mexico (Mexico)

    2004-07-01

    Since the Samarium presents the same chemical properties that the plutonium, it has been used as homologous in studies that allow us to know the behavior that the plutonium presents in solution, with the advantage of working with an inactive and not very dangerous element. At the moment studies of sorption of plutonium or samarium are made on some mineral matrices that present certain surface properties. Due to the low concentrations that are used in the studies of sorption of samarium on those reagent substrates, their detection becomes very difficult for the conventional analysis media. The luminescence is a technique that can detect lower concentrations, smaller at 1 X 10{sup -} {sup 2} M, but when fluorofors are used this limit of detection increases in several orders of magnitude. In this work it has been used the arsenazo-III as fluorofor agent since it reacts in a specific way with the samarium, forming a complex that presents a proportional luminescence to the concentration of the present samarium. The advantage of making the quantification of samarium by luminescence is that it can use the same instrumental equipment to determine the speciation of the samarium sipped in the zircon. (Author)

  1. Synthesis of samarium binding bleomycin - a possible NCT radiosensitizer

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, B.M., E-mail: bmm@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Mendes, T.M.; Campos, T.P.R., E-mail: campos@nuclear.ufmg.b [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)

    2011-07-01

    Bleomycin (BLM) is a drug that has attractive features for the development of a new radiopharmaceutical, particularly with regard to neutron capture therapy (NCT) sensitized by Sm-149. It has the ability to chelate many metal ions. In vitro studies have shown that up to 78% of BLM present in a cell is accumulated inside the nucleus or in the nuclear membrane. In addition, this drug has higher affinity for tumor tissues than for normal tissues. Radioactive isotopes carried by this antibiotic would be taken preferentially to one important cellular targets DNA. Besides, BLM displays intrinsic anti-tumor activity - it is a chemotherapic antibiotic clinically used against some cancers. This study aimed to obtain bleomycin molecules bound to samarium (BLM-Sm) for NCT studies in vitro and in vivo. The binding technique employed in this work has great simplicity and low cost. Thin layer chromatography, high performance liquid chromatography, fast protein liquid chromatography and analysis by ICP-AES were applied to verify the binding molecule. ICP-AES results showed the presence of samarium in the sample peaks related to BLM-Sm. However, efficiency and stability of this bond needs to be investigated. (author)

  2. Silicate volcanism on Io

    Science.gov (United States)

    Carr, M. H.

    1986-03-01

    This paper is mainly concerned with the nature of volcanic eruptions on Io, taking into account questions regarding the presence of silicates or sulfur as principal component. Attention is given to the generation of silicate magma, the viscous dissipation in the melt zone, thermal anomalies at eruption sites, and Ionian volcanism. According to the information available about Io, it appears that its volcanism and hence its surface materials are dominantly silicic. Several percent of volatile materials such as sulfur, but also including sodium- and potassium-rich materials, may also be present. The volatile materials at the surface are continually vaporized and melted as a result of the high rates of silicate volcanism.

  3. Luminescent solutions and powders of new samarium complexes with N,N',O,O'-chelating ligands

    Science.gov (United States)

    Kharcheva, Anastasia V.; Nikolskiy, Kirill S.; Borisova, Nataliya E.; Ivanov, Alexey V.; Reshetova, Marina D.; Yuzhakov, Viktor I.; Patsaeva, Svetlana V.

    2016-04-01

    Imaging techniques in biology and medicine are crucial tools to obtain information on structural and functional properties of living cells and organisms. To fulfill the requirements associated with application of these techniques it appears necessary to design markers with specific characteristics. Luminescent complexes of trivalent lanthanide ions with chelating ligands are of increasing importance in biomedical applications because of their millisecond luminescence lifetime, narrow emission band, high signal-to-noise ratio and minimal photodamage to biological samples. In order to extend the available emission wavelength range the luminescent samarium chelates are highly desirable. In this study the ligands with diamides of 2,2'-bipyridin-6,6'-dicarboxylic acid were used to improve photophysical characteristics of samarium complexes. We report the luminescence characteristics of samarium complexes with novel ligands. All complexes exhibited the characteristic emission of Sm (III) ion with the lines at 565, 597, 605, 645 and 654 nm, the intensity strongly depended on the ligand. Absorption and luminescence excitation spectra of Sm (III) complexes showed main peaks in the UV range demonstrating lanthanide coordination to the ligand. The absolute lumenescence quantum yield was measured for solutions in acetonitrile with excitation at 350 nm. The largest luminescence quantum yield was found for the samarium complex Bipy 6MePy Sm (3%) being much higher that for samarium complexes reported in the literature earlier. These results prove as well that samarium chelates are potential markers for multiparametric imaging techniques.

  4. Australian manufacture of Quadramet{sup TM} (Samarium-153 EDTMP)

    Energy Technology Data Exchange (ETDEWEB)

    Wood, N.R.; Whitwell, J. [Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW (Australia). Australian Radioisotopes

    1997-10-01

    Quadramet{sup T} (Samarium-153 EDTMP) has been shown overseas to be potentially useful in the palliation of painful osteoblastic skeletal metastases and has been approved this year for general marketing in the USA. Australian Radioisotopes (ARI) has licensed this product from the Australian patent holders, Dow Chemical. Within the facilities of ARI, a hot cell has been dedicated to this product and fitted out to manufacture it weekly on a cycle related to the operating cycle of the Australian reactor HIFAR. Due to neutron flux limitations of HIFAR, the local formulation has an elemental Samarium content up to 200{mu}g/mL whereas the overseas formulation has a level of 20-46{mu}g/mL. All other specifications of the two products are essentially the same. In 1995 and 1996 a small clinical trial with 19 patients was held which demonstrated that the pharmacokinetic behaviour was also essentially the same by measuring blood clearance rates and skeletal uptake dynamics. Soft tissue uptake was also qualitatively determined. The ARI version is now the subject of an application for general marketing within Australia. Some useful characteristics of this agent are: almost complete excretion or fixation in the skeleton within 6 hours, rapid onset of clinical effect, applicability in most cases where an abnormal diagnostic bone scan correlates with painful sites, dosage can be tailored to individual patient uptake due to easy dose measurement and retreatment is quite possible. The use of this class of agents in pain palliation continues to increase. Australian manufacture of Quadramet{sup TM} provides a further option in the management of these difficult cases

  5. Electrochemical extraction of samarium from molten chlorides in pyrochemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Castrillejo, Y., E-mail: ycastril@qa.uva.es [QUIANE/Dept Quimica Analitica, F. de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid (Spain); Fernandez, P. [QUIANE/Dept Quimica Analitica, F. de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid (Spain); Medina, J. [Dept Fisica Materia Condensada Cristalografia y Mineralogia, F. de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid (Spain); Hernandez, P. [Centro de Investigaciones Quimicas, Universidad Autonoma del Estado de Hidalgo, Carr. Pachuca-Tulancingo Km. 4.5, C.P. 42076 Pachuca, Hidalgo (Mexico); Barrado, E. [QUIANE/Dept Quimica Analitica, F. de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid (Spain)

    2011-10-01

    This work concerns the electrochemical extraction of samarium from molten chlorides. In this way, the electrochemical behaviour of samarium ions has been investigated in the eutectic LiCl-KCl at the surface of tungsten, aluminium and aluminium coated tungsten electrodes. On a W inert electrode the electro-reduction of Sm(III) takes place in only one soluble-soluble electrochemical step Sm(III)/Sm(II). The electrochemical system Sm(II)/Sm(0) has not been observed within the electrochemical window, because of the prior reduction of Li(I) ions from the solvent, which inhibits the electro-extraction of Sm species from the salt on such a substrate. Sm metal in contact with the melt react to give Li(0) according to the reaction: Sm(0) + 2Li(I) {r_reversible} Sm(II) + 2Li(0). On the contrary, on reactive Al electrodes the electrochemical system Sm(II)/Sm(0) was observed within the electroactive range. The potential shift of the redox couple is caused by the decrease of Sm activity in the metal phase due to the formation of Sm-Al alloys at the interface. The formation mechanism of the intermetallic compounds was studied in a melt containing: (i) both Sm(III) and Al(III) ions, using W and Al coated tungsten electrodes, and (ii) Sm(III) ions using an Al electrode. Analysis of the samples after potentiostatic electrolysis by X-ray diffraction and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), allowed the identification of Al{sub 3}Sm and Al{sub 2}Sm.

  6. Nanostructured silicate polymer concrete

    Directory of Open Access Journals (Sweden)

    Figovskiy Oleg L'vovich

    2014-03-01

    Full Text Available It has been known that acid-resistant concretes on the liquid glass basis have high porosity (up to 18~20 %, low strength and insufficient water resistance. Significant increasing of silicate matrix strength and density was carried out by incorporation of special liquid organic alkali-soluble silicate additives, which block superficial pores and reduce concrete shrinkage deformation. It was demonstrated that introduction of tetrafurfuryloxisilane additive sharply increases strength, durability and shock resistance of silicate polymer concrete in aggressive media. The experiments showed, that the strength and density of silicate polymer concrete increase in case of decreasing liquid glass content. The authors obtained optimal content of silicate polymer concrete, which possesses increased strength, durability, density and crack-resistance. Diffusive permeability of concrete and its chemical resistance has been investigated in various corroding media.

  7. Samarium Monosulfide (SmS): Reviewing Properties and Applications.

    Science.gov (United States)

    Sousanis, Andreas; Smet, Philippe F; Poelman, Dirk

    2017-08-16

    In this review, we give an overview of the properties and applications of samarium monosulfide, SmS, which has gained considerable interest as a switchable material. It shows a pressure-induced phase transition from the semiconducting to the metallic state by polishing, and it switches back to the semiconducting state by heating. The material also shows a magnetic transition, from the paramagnetic state to an antiferromagnetically ordered state. The switching behavior between the semiconducting and metallic states could be exploited in several applications, such as high density optical storage and memory materials, thermovoltaic devices, infrared sensors and more. We discuss the electronic, optical and magnetic properties of SmS, its switching behavior, as well as the thin film deposition techniques which have been used, such as e-beam evaporation and sputtering. Moreover, applications and possible ideas for future work on this material are presented. Our scope is to present the properties of SmS, which were mainly measured in bulk crystals, while at the same time we describe the possible deposition methods that will push the study of SmS to nanoscale dimensions, opening an intriguing range of applications for low-dimensional, pressure-induced semiconductor-metal transition compounds.

  8. Polymer-Layer Silicate Nanocomposites

    DEFF Research Database (Denmark)

    Potarniche, Catalina-Gabriela

    Nowadays, some of the material challenges arise from a performance point of view as well as from recycling and biodegradability. Concerning these aspects, the development of polymer layered silicate nanocomposites can provide possible solutions. This study investigates how to obtain polymer layered...... silicate nanocomposites and their structure-properties relationship. In the first part of the thesis, thermoplastic layered silicates were obtained by extrusion. Different modification methods were tested to observe the intercalation treatment effect on the silicate-modifier interactions. The silicate...

  9. Excitation induced spectroscopic study and quenching effect in cerium samarium codoped lithium aluminoborate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Parvinder; Kaur, Simranpreet [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Singh, Gurinder Pal [Department of Physics, Khalsa College, Amritsar 143002 (India); Arora, Deepawali; Kumar, Sunil [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Singh, D.P., E-mail: dpsinghdr@yahoo.com [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)

    2016-08-15

    Lithium aluminium borate host has been codoped with cerium and samarium to prepare glass by conventional melt quench technique. Their structural and spectroscopic investigation has been carried out using XRD, FTIR and density measurements. The UV‐Vis absorption spectra and fluorescence spectra (λ{sub exc}.=380 nm and 400 nm) have been studied for spectroscopic analysis. The amorphous nature of the prepared samples is shown by XRD. The density is increasing with addition of cerium at the expense of aluminium, keeping other components constant. FTIR study also shows the presence of compact and stable tetrahedral BO{sub 4} units thus supporting the density results. The UV‐ Vis absorption spectra show a shift of optical absorption edge towards longer wavelength along with an increase in intensity of peaks with rising samarium concentration. The fluorescence spectra show a blue shift and subsequent suppression of cerium peaks with addition of samarium.

  10. Effect of samarium doping on the dielectric behavior of barium zircomium titanate ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Badapanda, T., E-mail: badapanda.tanmaya@gmail.com [Department of Physics, C.V. Raman College of Engineering, Bhubaneswar, Odisha-752054 (India); Sarangi, S.; Behera, B. [School of Physics, Sambalpur University, Jyoti Vihar Sambalpur, Odisha-768019 (India); Anwar, S. [Colloids and Materials Chemistry, Institute of Minerals and Materials Technology, Bhubaneswar, Odisha-751013 (India); Sinha, T. P. [Department of Physics, Bose Institute, Kolkata-700009 (India)

    2014-04-24

    Samarium doped Barium Zirconium Titanate ceramic with general formula Ba{sub 1−x}Sm{sub 2x/3}Zr{sub 0.05}Ti{sub 0.95}O{sub 3} [x=0.0,0.01,0.02,0.03,0.04] has been prepared by high energy ball milling. The X-ray diffraction (XRD) patterns confirmed that these ceramics have a single phase with perovskite-type upto x≤0.03 and a small secondary phase exist at x=0.04. The temperature dependent dielectric study shows a ferroelectric phase transition and transition temperature decreases with an increase in the Samarium content.

  11. Lithium Bromide/Water as Additives in Dearomatizing Samarium-Ketyl (Hetero)Arene Cyclizations.

    Science.gov (United States)

    Rao, Chintada Nageswara; Bentz, Christoph; Reissig, Hans-Ulrich

    2015-11-02

    New conditions for dearomatizing samarium-ketyl (hetero)arene cyclizations are reported. In many examples of these samarium diiodide-mediated reactions, lithium bromide and water can be used as additives instead of the carcinogenic and mutagenic hexamethylphosphoramide (HMPA). The best results were obtained for the cyclizations of N-acylated indole derivatives delivering the expected indolines in good yields and excellent diastereoselectivities. A new type of cyclization delivering indolyl-substituted allene derivatives is also described. The scope and limitations of the lithium bromide/water system are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. One-step synthesis of samarium-doped ceria and its CO catalysis

    Indian Academy of Sciences (India)

    The samarium-doped ceria (SDC) nanospheres were prepared by the one-step hydrothermal method and characterized by transmission electron microscope, scanning electron microscope, powder X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive spectrometer and Raman spectra. According to the ...

  13. A spectroscopic comparison of samarium-doped LiYF4 and KY3F10

    NARCIS (Netherlands)

    Wells, J. P. R.; Sugiyama, A.; Han, T. P. J.; Gallagher, H. G.

    2000-01-01

    Laser selective excitation and fluorescence has been performed on LiYF4 and KY3F10 doped with samarium ions. In LiYF4, a single, tetragonal symmetry center associated with isovalent substitution of Sm3+ with lattice yttrium ions is present. By contrast, three Sm2+ centres and a single, tetragonal

  14. The Use of a Flexible Calix[4]arene Template to Stabilize a Cyclooctatetraindiyl Samarium-Potassium Complex

    Directory of Open Access Journals (Sweden)

    Geoffroy Guillemot

    2013-01-01

    Full Text Available A sandwich compound of cyclooctatetraendiyl (COT2− samarium-potassium was synthesized and analyzed using a flexible calix[4]arene dianion. This compound, [p-tBu-calix[4]-(OMe2(O2]arenediyl-samarium-(η8-cyclooctatetraendiyl-potassium (tetrahydrofurane3, is constructed as a linear sequence L-Sm--K-, where L, , and are specific ligands with L = O,O-dimethyl-calix[4]arene2−, = cyclo-octatetraendiyl, and = tetrahydrofurane templates.

  15. Silicates in Alien Asteroids

    Science.gov (United States)

    2009-01-01

    This plot of data from NASA's Spitzer Space Telescopes shows that asteroid dust around a dead 'white dwarf' star contains silicates a common mineral on Earth. The data were taken primarily by Spitzer's infrared spectrograph, an instrument that breaks light apart into its basic constituents. The yellow dots show averaged data from the spectrograph, while the orange triangles show older data from Spitzer's infrared array camera. The white dwarf is called GD 40.

  16. Thermochemistry of Silicates

    Science.gov (United States)

    Costa, Gustavo; Jacobson, Nathan

    2015-01-01

    The thermodynamic properties of vapor and condensed phases of silicates are crucial in many fields of science. These quantities address fundamental questions on the formation, stability, transformation, and physical properties of silicate minerals and silicate coating compositions. Here the thermodynamic activities of silica and other species in solid solution have been measured by the analysis of the corresponding high temperature vapors using Knudsen Effusion Mass Spectrometry (KEMS). In first set of experiments KEMS has been used to examine the volatility sequence of species (Fe, SiO, Mg, O2 and O) present in the vapor phase during heating of fosterite-rich olivine (Fo93Fa7) up to 2400 C and to measure the Fe, SiO and Mg activities in its solid solution. The data of fosterite-rich olivine are essential for thermochemical equilibrium models to predict the atmospheric and surface composition of hot, rocky exoplanets (Lava Planets). In the second set of experiments the measured thermodynamic activities of the silica in Y2O3-SiO2 and Yb2O3-SiO2 systems are used to assess their reactivity and degradation recession as environmental barrier coatings (EBCs) in combustion environments (e.g. non-moveable parts of gas turbine engine).

  17. Solar nebula heterogeneity in p-process samarium and neodymium isotopes.

    Science.gov (United States)

    Andreasen, Rasmus; Sharma, Mukul

    2006-11-03

    Bulk carbonaceous chondrites display a deficit of approximately 100 parts per million (ppm) in 144Sm with respect to other meteorites and terrestrial standards, leading to a decrease in their 142Nd/144Nd ratios by approximately 11 ppm. The data require that samarium and neodymium isotopes produced by the p process associated with photodisintegration reactions in supernovae were heterogeneously distributed in the solar nebula. Other samarium and neodymium isotopes produced by rapid neutron capture (r process) in supernovae and by slow neutron capture (s process) in red giants were homogeneously distributed. The supernovae sources supplying the p- and r-process nuclides to the solar nebula were thus disconnected or only weakly connected.

  18. Samarium(II) iodide-mediated reductive annulations of ketones bearing a distal vinyl epoxide moiety

    Energy Technology Data Exchange (ETDEWEB)

    Molander, G.A.; Shakya, S.R. [Univ. of Colorado, Boulder, CO (United States)

    1996-08-23

    It was found that samarium (II) iodide promotes the intramolecular coupling of ketones with distal epoxy olefins while in the presence of hexamethylphosphoramide (HPMA). A number of epoxide compounds (1 a-k) fragment to form carbocycles with allylic alcohol side chains with high diastereoselectivity (2 a-k). Substituting tetramethylguanidine for HPMA reduces the diastereoselectivity. Adding Pd(0) as a catalyst reverses the diastereoselective sense. 40 refs., 1 tab.

  19. A temporal three-dimensional simulation of samarium release in the ionosphere

    Science.gov (United States)

    Zhao, Hai-Sheng; Feng, Jie; Xu, Zheng-Wen; Wu, Jian; Wu, Zhen-Sen; Xu, Bin; Xue, Kun; Xu, Tong; Hu, Yan-Li

    2016-10-01

    For understanding plasma processes of the ionosphere and magnetosphere, the alkali and alkaline-earth metals are usually released in space for artificially increasing the electron density. However, it is a limitation that these releases must be in sunlight where the photoionization can take place. In recent years, the lanthanide metals, such as samarium, have been released to produce electrons in reaction with atomic oxygen in the upper space. The reaction could proceed without sunlight so that the restriction on experimental periods is broken. Unfortunately, any sophisticated models even preliminary ones are unavailable yet in the literature. A temporal three-dimensional model is presented for the samarium release in detail with respect to various altitudes and mass. Especially, the plasma diffusion equation is remarkably extended from 2-D to 3-D by importing the influence of geomagnetic declination, which could be also useful for other chemical releases. The field-aligned terms are brought so as to the presented model can describe the diffusion along the geomagnetic field subtly. On the basis of the presented model, behaviors of radio waves propagating through the release area are simulated by using ray tracing. This model could be as the theoretical support for samarium releases, and it also helpful for the research on the generation and evolution of the ionosphere irregularities.

  20. Liquid–liquid anion exchange extraction studies of samarium(III from salicylate media using high molecular weight amine

    Directory of Open Access Journals (Sweden)

    Aniruddha M. Mandhare

    2015-07-01

    Full Text Available Liquid–liquid extraction and separation of samarium(III were carried out by using 0.025 mol dm−3 2-octylaminopyridine(2-OAP in xylene at 298 K. The extraction behavior of samarium was studied as a function of pH, weak acid concentration, extractant concentration, diluent, and equilibration time. Samarium was quantitatively extracted at pH 7.5 to 10.0 from 0.01 mol dm−3 sodium salicylate solution with 0.025 mol dm−3 2-OAP. The possible composition of the extracted species in organic phase has been determined by using model of slope analysis method and extraction mechanism was found to proceed via an anion exchange mechanism. The stripping efficiency was found to be quantitative in HNO3, HCl and CH3COOH. The robustness of the procedure was demonstrated by the average recoveries obtained (>99.6% for samarium(III extraction in the presence of several cations and anions which are commonly associated with it. The proposed method facilitates the separation and determination of samarium(III from binary and synthetic mixtures. The various thermodynamic functions like free energy (ΔG, enthalpy (ΔH and entropy (ΔS of extraction mechanism were discussed.

  1. Samarium(II) iodide-mediated intramolecular conjugate additions of alpha,beta-unsaturated lactones.

    Science.gov (United States)

    Molander, Gary A; St Jean, David J

    2002-05-31

    Samarium(II) iodide, in the presence of catalytic amounts of nickel(II) iodide, has been used to promote intramolecular conjugate additions of alkyl halides onto alpha,beta-unsaturated lactones. This process has been shown to be applicable to a number of alpha,beta-unsaturated lactones, including tetrasubstituted olefins, and has been demonstrated to be quite general for the formation of saturated bicyclic and tricyclic lactones. The method presented herein provides a mild, efficient process to form structurally complex lactones from simple precursors.

  2. Environmental silicate nano-biocomposites

    CERN Document Server

    Pollet, Eric

    2012-01-01

    Environmental Silicate Nano-Biocomposites focuses on nano-biocomposites, which are obtained by the association of silicates such as bioclays with biopolymers. By highlighting recent developments and findings, green and biodegradable nano-composites from both renewable and biodegradable polymers are explored. This includes coverage of potential markets such as packaging, agricultures, leisure and the fast food industry. The knowledge and experience of more than twenty international experts in diverse fields, from chemical and biochemical engineering to applications, is brought together in four different sections covering: Biodegradable polymers and Silicates, Clay/Polyesters Nano-biocomposites, Clay/Agropolymers Nano-biocomposites, and Applications and biodegradation of Nano-biocomposites. By exploring the relationships between the biopolymer structures, the processes, and the final properties Environmental Silicate Nano-Biocomposites explains how to design nano-materials to develop new, valuable, environmenta...

  3. Understanding silicate hydration from quantitative analyses of hydrating tricalcium silicates

    Science.gov (United States)

    Pustovgar, Elizaveta; Sangodkar, Rahul P.; Andreev, Andrey S.; Palacios, Marta; Chmelka, Bradley F.; Flatt, Robert J.; d'Espinose de Lacaillerie, Jean-Baptiste

    2016-01-01

    Silicate hydration is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement hydration. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-hydrates (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measurements of 29Si-enriched triclinic Ca3SiO5 enable the quantitative monitoring of the hydration process in terms of transient local molecular composition, extent of silicate hydration and polymerization. This provides insights on the relative influence of surface hydroxylation and hydrate precipitation on the hydration rate. When the rate drops, the amount of hydroxylated Ca3SiO5 decreases, thus demonstrating the partial passivation of the surface during the deceleration stage. Moreover, the relative quantities of monomers, dimers, pentamers and octamers in the C-S-H structure are measured. PMID:27009966

  4. Ekstraksi Pemisahan Neodimium dari Samarium, Itrium dan Praseodimium Memakai Tri Butil Fosfat

    Directory of Open Access Journals (Sweden)

    Maria Veronica Purwani

    2017-05-01

    Full Text Available The extraction of Nd(OH3 (neodymium hydroxide concentrate containing Y (yttrium, Sm (samarium and Pr (praseodymium as product of monazite processed has been done. The purpose of this study is to determine the separation of Nd from Y, Pr and Nd Sm in Nd concentrate. The aqueous phase was concentrated Nd (OH3 in HNO3 and extractant while organic phase was Tri Butyl Phosphate (TBP in kerosene. Parameters studied were pH and concentration feed, concentration of TBP in kerosene, extraction time and stirring speed. The result showed that the optimization of separation extraction neodymium from samarium, yttrium and praseodymium in Nd(OH3 concentrated with TBP, obtained the optimum condition of pH = 0.2, concentration of feed 100 g /L, concentration of TBP in kerosene 5%, extraction time 15 minutes and stirring speed 150 rpm. With the conditions, Separation Factor (SF obtained for Nd-Y, Nd-Pr, Nd-Sm are 2.242, 4.811, 4.002 respectively, while D and extraction efficiency of Nd are 0.236 and 19.07%.

  5. X-Band Microwave Reflection Properties of Samarium/Bismuth-Substituted Barium Lanthanum Titanate Ceramics

    Science.gov (United States)

    Bahel, Shalini; Pubby, Kunal; Narang, Sukhleen Bindra

    2017-03-01

    Samarium/bismuth-substituted barium lanthanum titanate ceramics with chemical composition Ba4 (La_{1 - y - z} Smy Biz )_{9.33} Ti_{18} O_{54} ( y = 0.5, 0.7; z = 0.05, 0.10, 0.15), intended as microwave reflecting materials, have been investigated in microwave X-band (8.2 GHz to 12.4 GHz) and the effect of substitution on their dielectric properties, i.e., dielectric constant and dielectric loss tangent, has been studied by vector network analyzer. Dielectric analysis showed that the dielectric constant increased with increasing samarium as well as bismuth content. Dielectric relaxation was observed for all samples in the scanned frequency range. Microwave reflection and transmission analysis of ceramic pellets of thickness 4 mm was carried out using two methods, i.e., open- and short-circuit approach, both indicating very high values of reflected power and very low values of transmitted power for all the doped materials in comparison with the base composition. The doped compositions are therefore potential microwave shielding materials for use in anechoic chambers, microwave laboratories, and radar equipment. Double-layer reflectors are also proposed, having better reflection properties (˜99% reflection) compared with single-layer reflectors.

  6. Microstructure and hysteresis curves of samarium-holmium-iron garnet synthesized by coprecipitation

    Directory of Open Access Journals (Sweden)

    Caffarena Valeska da Rocha

    2003-01-01

    Full Text Available An investigation was made into the synthesis and magnetic properties of Sm(3-xHo xFe5O12 (samarium-holmium-iron garnet ferrite, as yet absent from the literature. The material in question was synthesized by co-precipitation, starting from hydrated chlorides of rare-earth elements and ferrous sulfate, and the mixed hydroxide co-precipitate was calcined at 1000 °C. Using PVA as a binder, rectangular cross section-shaped compacts were produced by means of steel-die pressing, drying and sintering from 1200 to 1450 °C. The main conclusions of this study were that the coercive force decreases as the sintering temperature increases, and that the effect of substituting holmium for samarium in SmIG is entirely different from that provided by replacing yttrium by gadolinium in YIG, which is the most important result of this work. An in-depth investigation will be necessary to determine the correlation between microstructure/magnetic properties and ceramic processing variables.

  7. Bone-seeking radiopharmaceuticals as targeted agents of osteosarcoma: samarium-153-EDTMP and radium-223.

    Science.gov (United States)

    Anderson, Peter M; Subbiah, Vivek; Rohren, Eric

    2014-01-01

    Osteosarcoma is a cancer characterized by formation of bone by malignant cells. Routine bone scan imaging with Tc-99m-MDP is done at diagnosis to evaluate primary tumor uptake and check for bone metastases. At time of relapse the Tc-99m-MDP bone scan also provides a specific means to assess formation of bone by malignant osteosarcoma cells and the potential for bone-seeking radiopharmaceuticals to deliver radioactivity directly into osteoblastic osteosarcoma lesions. This chapter will review and compare a bone-seeking radiopharmaceutical that emits beta-particles, samarium-153-EDTMP, with an alpha-particle emitter, radium-223. The charged alpha particles from radium-223 have far more mass and energy than beta particles (electrons) from Sm-153-EDTMP. Because radium-223 has less marrow toxicity and more radiobiological effectiveness, especially if inside the bone forming cancer cell than samarium-153-EDTMP, radium-223 may have greater potential to become widely used against osteosarcoma as a targeted therapy. Radium-223 also has more potential to be used with chemotherapy against osteosarcoma and bone metastases. Because osteosarcoma makes bone and radium-223 acts like calcium, this radiopharmaceutical could possibly become a new targeted means to achieve safe and effective reduction of tumor burden as well as facilitate better surgery and/or radiotherapy for difficult to resect large, or metastatic tumors.

  8. Polypyrrole-coated samarium oxide nanobelts: fabrication, characterization, and application in supercapacitors

    Science.gov (United States)

    Liu, Peng; Wang, Yunjiao; Wang, Xue; Yang, Chao; Yi, Yanfeng

    2012-11-01

    Polypyrrole-coated samarium oxide nanobelts were synthesized by the in situ chemical oxidative surface polymerization technique based on the self-assembly of pyrrole on the surface of the amine-functionalized Sm2O3 nanobelts. The morphologies of the polypyrrole/samarium oxide (PPy/Sm2O3) nanocomposites were characterized using transmission electron microscope. The UV-vis absorbance of these samples was also investigated, and the remarkable enhancement was clearly observed. The electrochemical behaviors of the PPy/Sm2O3 composites were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge. The results indicated that the PPy/Sm2O3 composite electrode was fully reversible and achieved a very fast Faradaic reaction. After being corrected into the weight percentage of the PPy/Sm2O3 composite at a current density of 20 mA cm-2 in a 1.0 M NaNO3 electrolyte solution, a maximum discharge capacity of 771 F g-1 was achieved in a half-cell setup configuration for the PPy/Sm2O3 composites electrode with the potential application to electrode materials for electrochemical capacitors.

  9. Polypyrrole-coated samarium oxide nanobelts: fabrication, characterization, and application in supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Liu Peng, E-mail: pliu@lzu.edu.cn; Wang Yunjiao; Wang Xue; Yang Chao; Yi Yanfeng [College of Chemistry and Chemical Engineering, Lanzhou University, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province and State Key Laboratory of Applied Organic Chemistry (China)

    2012-11-15

    Polypyrrole-coated samarium oxide nanobelts were synthesized by the in situ chemical oxidative surface polymerization technique based on the self-assembly of pyrrole on the surface of the amine-functionalized Sm{sub 2}O{sub 3} nanobelts. The morphologies of the polypyrrole/samarium oxide (PPy/Sm{sub 2}O{sub 3}) nanocomposites were characterized using transmission electron microscope. The UV-vis absorbance of these samples was also investigated, and the remarkable enhancement was clearly observed. The electrochemical behaviors of the PPy/Sm{sub 2}O{sub 3} composites were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge. The results indicated that the PPy/Sm{sub 2}O{sub 3} composite electrode was fully reversible and achieved a very fast Faradaic reaction. After being corrected into the weight percentage of the PPy/Sm{sub 2}O{sub 3} composite at a current density of 20 mA cm{sup -2} in a 1.0 M NaNO{sub 3} electrolyte solution, a maximum discharge capacity of 771 F g{sup -1} was achieved in a half-cell setup configuration for the PPy/Sm{sub 2}O{sub 3} composites electrode with the potential application to electrode materials for electrochemical capacitors.

  10. Neutron and Charged-Particle Induced Cross Sections for Radiochemistry in the Region of Samarium, Europium, and Gadolinium

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, R D; Kelley, K; Dietrich, F S; Bauer, R; Mustafa, M

    2004-11-30

    We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron and proton induced nuclear reaction cross sections in the mass region of samarium, europium and gadolinium (62 {le} Z {le} 64, 82 {le} N {le} 96).

  11. Pemisahan Unsur Samarium dan Yttrium dari Mineral Tanah Jarang dengan Teknik Membran Cair Berpendukung (Supported Liquid Membrane

    Directory of Open Access Journals (Sweden)

    Amri Amin

    2009-06-01

    Full Text Available he increasing use of rare earth elements in high technology industries needs to be supported by developmental work for the separation of elements. The research objective is fiercely attracting and challenging considering the similarity of bath physical and chemical properties among these elements. The rate separation of samarium and yttrium elements using supported liquid membrane has been studied. Polytetrafluoroethylene (PTFE with pore size of 0.45 µm has been used as the membrane and di(2-ethylhexyl phosphate (D2EHP in hexane has been used as a carrier and nitric acid solution has been used as receiving phase. Result of experiments showed that the best separation rate of samarium and yttrium elements could be obtained at feeding phase of pH 3.0, di(2-ethylhexyl phosphate (D2EHP concentration of 0.3 M, agitation rate of 700 rpm, agitation time of 2 hours, and nitric acid and its solution concentrations of 1.0 M and 0.1 M, respectively. At this condition, separation rates of samarium and yttrium were 64.4 and 67.6%, respectively.   Keywords: liquid membrane, rare earth elements, samarium, yttrium

  12. Final report on the safety assessment of aluminum silicate, calcium silicate, magnesium aluminum silicate, magnesium silicate, magnesium trisilicate, sodium magnesium silicate, zirconium silicate, attapulgite, bentonite, Fuller's earth, hectorite, kaolin, lithium magnesium silicate, lithium magnesium sodium silicate, montmorillonite, pyrophyllite, and zeolite.

    Science.gov (United States)

    Elmore, Amy R

    2003-01-01

    This report reviews the safety of Aluminum, Calcium, Lithium Magnesium, Lithium Magnesium Sodium, Magnesium Aluminum, Magnesium, Sodium Magnesium, and Zirconium Silicates, Magnesium Trisilicate, Attapulgite, Bentonite, Fuller's Earth, Hectorite, Kaolin, Montmorillonite, Pyrophyllite, and Zeolite as used in cosmetic formulations. The common aspect of all these claylike ingredients is that they contain silicon, oxygen, and one or more metals. Many silicates occur naturally and are mined; yet others are produced synthetically. Typical cosmetic uses of silicates include abrasive, opacifying agent, viscosity-increasing agent, anticaking agent, emulsion stabilizer, binder, and suspending agent. Clay silicates (silicates containing water in their structure) primarily function as adsorbents, opacifiers, and viscosity-increasing agents. Pyrophyllite is also used as a colorant. The International Agency for Research on Cancer has ruled Attapulgite fibers >5 microm as possibly carcinogenic to humans, but fibers Cosmetic Ingredient Review (CIR. The Cosmetic Ingredient Review (CIR) Expert Panel concluded that the extensive pulmonary damage in humans was the result of direct occupational inhalation of the dusts and noted that lesions seen in animals were affected by particle size, fiber length, and concentration. The Panel considers that most of the formulations are not respirable and of the preparations that are respirable, the concentration of the ingredient is very low. Even so, the Panel considered that any spray containing these solids should be formulated to minimize their inhalation. With this admonition to the cosmetics industry, the CIR Expert Panel concluded that these ingredients are safe as currently used in cosmetic formulations. The Panel did note that the cosmetic ingredient, Talc, is a hydrated magnesium silicate. Because it has a unique crystalline structure that differs from ingredients addressed in this safety assessment, Talc is not included in this report.

  13. NON-AUTOCLAVE SILICATE BRICK

    Directory of Open Access Journals (Sweden)

    V. N. Yaglov

    2015-01-01

    Full Text Available The paper proposes a technology for obtaining bricks on the basis of lime-silica mixtures where chemical interactions are practically completely realized in dispersive state at the stage of preparation of binding contact maturing and raw mixture as a whole. The role of forming operation (moulding is changed in principle because in this case conversion of dispersive system into a rock-like solid occurs and due to this the solid obtains complete water-resistance in contact with water immediately after forming operation. Theoretical basis for the developed technology is capability of silicate dispersive substances (hydrated calcium silicate to transit in non-stable state, to form a rock-like water-resistant solid in the moment of mechanical load application during forming process. Specific feature of the proposed method is an exclusion of additional operations for autoclaving of products from the process of obtaining a silicate brick.Synthetic hydrated calcium silicate in contrast to natural ones are more uniform in composition and structure, they contain less impurities and they are characterized by dispersive composition and due to the mentioned advantages they find wider practical application. Contact-condensation binders permit to manipulate product properties on their basis and ensure maximum correspondence to the requirements of the concrete application. Raw material sources for obtaining synthetic hydrated calcium silicates are practically un-limited because calcium-silicon containing substances are found as in various technogenic wastes so in natural compounds as well. So the problem for obtaining hydrated calcium silicates having contact-condensation ability for structure formation becomes more and more actual one. This transition is considered as dependent principally on arrangement rate of substance particles which determined the level of its instability.

  14. Effects of the atomic environment on the electron binding energies in samarium

    Energy Technology Data Exchange (ETDEWEB)

    Inoyatov, A.Kh., E-mail: inoyatov@jinr.ru [Laboratory of Nuclear Problems, JINR, Dubna, Moscow Region (Russian Federation); Institute of Applied Physics, National University, Tashkent, Republic of Uzbekistan (Uzbekistan); Kovalík, A. [Laboratory of Nuclear Problems, JINR, Dubna, Moscow Region (Russian Federation); Nuclear Physics Institute of the ASCR, CZ-25068 Řež near Prague (Czech Republic); Filosofov, D.V. [Laboratory of Nuclear Problems, JINR, Dubna, Moscow Region (Russian Federation); Ryšavý, M.; Vénos, D. [Nuclear Physics Institute of the ASCR, CZ-25068 Řež near Prague (Czech Republic); Yushkevich, Yu.V.; Perevoshchikov, L.L. [Laboratory of Nuclear Problems, JINR, Dubna, Moscow Region (Russian Federation); Zhdanov, V.S. [Nuclear Physics Institute, Almaty, Republic of Kazakhstan (Kazakhstan)

    2016-02-15

    Highlights: • Eight different matrices (evaporated and implanted at 30 keV) used. • The greatest average difference in the binding energies amounted to 3.1 ± 0.1 eV. • The presence of trivalent and divalent Sm ions found in some implanted samples. • No significant differences in Sm natural atomic level widths were observed. - Abstract: Effects of the atomic environment on the L{sub 1}, L{sub 2}, L{sub 3}, M{sub 1}, M{sub 2}, M{sub 3}, and N{sub 1} electron binding energies in samarium generated in the electron capture decay of radioactive {sup 149}Eu were investigated by means of the internal conversion electron spectroscopy using the conversion electron spectrum of the 22.5 keV M1 + E2 nuclear transition in the daughter {sup 149}Sm. In this investigation, four pairs of {sup 149}Eu sources prepared by vacuum evaporation deposition and by ion implantation at 30 keV with the use of four different source backing materials, namely polycrystalline carbon, aluminium, gadolinium and platinum foils, were employed. The greatest average difference of (3.1 ± 0.1) eV in the L{sub 1}, L{sub 2}, L{sub 3}, and M{sub 1} subshell electron binding energies was observed between the {sup 149}Eu sources prepared by ion implantation into the aluminium and platinum substrates. On the other hand, minimal differences in the electron binding energies were generally found between samarium generated in the evaporated layer and in the bulk for the individual investigated source backings with the exception of the gadolinium foil. A doublet structure of all investigated conversion electron lines with the average values of 8.1 ± 0.2 eV and 1.5 ± 0.1 for the separation energy and the intensity ratio of the low-energy to high-energy components, respectively, was observed for the {sup 149}Eu sources prepared by ion implantation into the aluminium and carbon foils. This structure was presumably caused by the presence of both the trivalent and divalent Sm ions in the sources. No

  15. Battery components employing a silicate binder

    Science.gov (United States)

    Delnick, Frank M [Albuquerque, NM; Reinhardt, Frederick W [Albuquerque, NM; Odinek, Judy G [Rio Rancho, NM

    2011-05-24

    A battery component structure employing inorganic-silicate binders. In some embodiments, casting or coating of components may be performed using aqueous slurries of silicates and electrode materials or separator materials.

  16. Submarine silicic volcanism: Processes and products

    Digital Repository Service at National Institute of Oceanography (India)

    Kalangutkar, N.G.; Iyer, S.D.

    The occurrence of submarine silicic volcanics is rare at the mid-oceanic ridges, abyssal depths, seamounts and fracture zones. Hydrothermal processes are active in submarine silicic environments and are associated with host ores of Cu, Au, Ag, Pb...

  17. Multiphoton laser wave-mixing absorption spectroscopy for samarium using a graphite furnace atomizer

    Energy Technology Data Exchange (ETDEWEB)

    Maniaci, Michael J.; Tong, William G. E-mail: william.tong@sdsu.edu

    2004-07-30

    Nonlinear laser wave-mixing optical technique is presented as a sensitive atomic spectroscopic method for the analysis of rare earth elements using an unmodified commercially available graphite furnace (GF) atomizer. A simple nonplanar backward-scattering degenerate four-wave mixing optical arrangement offers sub-picogram detection sensitivity with sub-Doppler Lorentzian-broadened resolution. Nonlinear wave mixing is an unusually sensitive absorption-based optical method that offers both excellent detection sensitivity and sub-Doppler spectral resolution. A mass detection limit of 0.7 pg and a concentration detection limit of 70 pg/ml are determined for a rare earth element, samarium, using the 429.7-nm excitation line.

  18. Samarium Doped Cerium Oxide Clusters: a Study on the Modulation of Electronic Structure

    Science.gov (United States)

    Topolski, Josey E.; Kafader, Jared O.; Marrero-Colon, Vicmarie; Chick Jarrold, Caroline

    2017-06-01

    Cerium oxide is known for its use in solid oxide fuel cells due to its high ionic conductivity. The doping of trivalent samarium atoms into cerium oxide is known to enhance the ionic conductivity through the generation of additional oxygen vacancies. This study probes the electronic structure of Sm_{x}Ce_{y}O_{z} (x+y=3, z=2-4) anion and neutral clusters. Anion photoelectron spectra of these mixed metal clusters exhibit additional spectral features not present in the previously studied cerium oxide clusters. Density functional theory calculations have been used to aid interpretation of collected spectra. The results of this work can be used to inform the design of materials used for solid oxide fuel cells.

  19. Chelating Ligand-Mediated Hydrothermal Synthesis of Samarium Orthovanadate with Decavanadate as Vanadium Source

    Directory of Open Access Journals (Sweden)

    Quanguo Li

    2013-01-01

    Full Text Available A new ethylenediaminetetraacetic acid- (EDTA- mediated hydrothermal route to prepare chrysanthemum-shaped samarium orthovanadate (SmVO4 nanocrystals with decavanadate (K6V10O28·9H2O as vanadium source has been developed. The present hydrothermal approach is simple and reproducible and employs a relatively mild reaction temperature. The EDTA, pH value, and temperature of the reaction systems play important roles in determining the morphologies and growth process of the SmVO4 products. The products have been characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FT-IR, photoluminescence spectra (PL, and UV-Vis spectroscopy.

  20. The Magnetocaloric Effect and Heat Capacity of Suspensions of High-Dispersity Samarium Ferrite

    Science.gov (United States)

    Korolev, V. V.; Aref'ev, I. M.; Ramazanova, A. G.

    2008-02-01

    The magnetocaloric effect and specific heat capacity of an aqueous suspension of samarium ferrite were determined calorimetrically over the temperature range 288-343 K in magnetic fields of 0-0.7 T. The data obtained were used to calculate changes in the magnetic component of the molar heat capacity and entropy of the magnetic phase and changes in the enthalpy of the process under an applied magnetic field. The magnetocaloric effect was found to increase nonlinearly as the magnetic field induction grew. The corresponding temperature dependences contained a maximum at 313 K related to the second-order magnetic phase transition at the Curie point. The field and temperature dependences of heat capacity contained a maximum in fields of 0.4 T and a minimum at the magnetic phase transition temperature.

  1. Amended Silicated for Mercury Control

    Energy Technology Data Exchange (ETDEWEB)

    James Butz; Thomas Broderick; Craig Turchi

    2006-12-31

    Amended Silicates{trademark}, a powdered, noncarbon mercury-control sorbent, was tested at Duke Energy's Miami Fort Station, Unit 6 during the first quarter of 2006. Unit 6 is a 175-MW boiler with a cold-side electrostatic precipitator (ESP). The plant burns run-of-the-river eastern bituminous coal with typical ash contents ranging from 8-15% and sulfur contents from 1.6-2.6% on an as-received basis. The performance of the Amended Silicates sorbent was compared with that for powdered activated carbon (PAC). The trial began with a period of baseline monitoring during which no sorbent was injected. Sampling during this and subsequent periods indicated mercury capture by the native fly ash was less than 10%. After the baseline period, Amended Silicates sorbent was injected at several different ratios, followed by a 30-day trial at a fixed injection ratio of 5-6 lb/MMACF. After this period, PAC was injected to provide a comparison. Approximately 40% mercury control was achieved for both the Amended Silicates sorbent and PAC at injection ratios of 5-6 lbs/MMACF. Higher injection ratios did not achieve significantly increased removal. Similar removal efficiencies have been reported for PAC injection trials at other plants with cold-side ESPs, most notably for plants using medium to high sulfur coal. Sorbent injection did not detrimentally impact plant operations and testing confirmed that the use of Amended Silicates sorbent does not degrade fly ash quality (unlike PAC). The cost for mercury control using either PAC or Amended Silicates sorbent was estimated to be equivalent if fly ash sales are not a consideration. However, if the plant did sell fly ash, the effective cost for mercury control could more than double if those sales were no longer possible, due to lost by-product sales and additional cost for waste disposal. Accordingly, the use of Amended Silicates sorbent could reduce the overall cost of mercury control by 50% or more versus PAC for locations where

  2. Preparation of hollow core/shell microspheres of hematite and its adsorption ability for samarium.

    Science.gov (United States)

    Yu, Sheng-Hui; Yao, Qi-Zhi; Zhou, Gen-Tao; Fu, Sheng-Quan

    2014-07-09

    Hollow core/shell hematite microspheres with diameter of ca. 1-2 μm have been successfully achieved by calcining the precursor composite microspheres of pyrite and polyvinylpyrrolidone (PVP) in air. The synthesized products were characterized by a wide range of techniques including powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and Brunauer-Emmett-Teller (BET) gas sorptometry. Temperature- and time-dependent experiments unveil that the precursor pyrite-PVP composite microspheres finally transform into hollow core/shell hematite microspheres in air through a multistep process including the oxidation and sulfation of pyrite, combustion of PVP occluded in the precursor, desulfation, aggregation, and fusion of nanosized hematite as well as mass transportation from the interior to the exterior of the microspheres. The formation of the hollow core/shell microspheres dominantly depends on the calcination temperature under current experimental conditions, and the aggregation of hematite nanocrystals and the core shrinking during the oxidation of pyrite are responsible for the formation of the hollow structures. Moreover, the adsorption ability of the hematite for Sm(III) was also tested. The results exhibit that the hematite microspheres have good adsorption activity for trivalent samarium, and that its adsorption capacity strongly depends on the pH of the solution, and the maximum adsorption capacity for Sm(III) is 14.48 mg/g at neutral pH. As samarium is a typical member of the lanthanide series, our results suggest that the hollow hematite microspheres have potential application in removal of rare earth elements (REEs) entering the water environment.

  3. The influence of the technological parameters on the ionic conductivity of samarium doped ceria thin films

    Directory of Open Access Journals (Sweden)

    Mantas Sriubas

    2015-03-01

    Full Text Available Sm0,20Ce0,80O2 powder was used for the formation of samarium doped cerium oxide (SDC thin films using e-beam. Surface area of powder was 34.9 m2/g and particle size – 0.3-0.5 μm. Thin films were deposited using physical vapor deposition system on SiO2 and Alloy 600 substrates. 2 Å/s – 16 Å/s growth rate and 20 °C – 600 °C substrate temperature were used during the deposition. Ionic conductivity investigation revealed that the maximum ionic conductivity (1.67 S/m has the thin film deposited on 300 °C temperature substrate using 4 Å/s growth rate. Minimum ionic conductivity (0.26 S/m has thin film which was deposited on 20 °C temperature substrate using 8 Å/s growth rate. Vacancy activation energies vary in 0.87 eV – 0.97 eV range. Furthermore the calculations of crystallite size revealed that crystallite size increases with increasing substrate temperature: from 7.50 nm to 46.23 nm on SiO2 substrate and from 9.30 nm to 44.62 nm on Alloy 600 substrate. Molar concentration of samarium in initial evaporated material is 19.38 mol% and varies from 11.37 mol% to 21 mol% in formed thin films depending on technological parameters.DOI: http://dx.doi.org/10.5755/j01.ms.21.1.5700

  4. Formation of Core-Shell Nanoparticles Composed of Magnetite and Samarium Oxide in Magnetospirillum magneticum Strain RSS-1.

    Science.gov (United States)

    Shimoshige, Hirokazu; Nakajima, Yoshikata; Kobayashi, Hideki; Yanagisawa, Keiichi; Nagaoka, Yutaka; Shimamura, Shigeru; Mizuki, Toru; Inoue, Akira; Maekawa, Toru

    2017-01-01

    Magnetotactic bacteria (MTB) synthesize magnetosomes composed of membrane-enveloped magnetite (Fe3O4) or greigite (Fe3S4) particles in the cells. Recently, several studies have shown some possibilities of controlling the biomineralization process and altering the magnetic properties of magnetosomes by adding some transition metals to the culture media under various environmental conditions. Here, we successfully grow Magnetospirillum magneticum strain RSS-1, which are isolated from a freshwater environment, and find that synthesis of magnetosomes are encouraged in RSS-1 in the presence of samarium and that each core magnetic crystal composed of magnetite is covered with a thin layer of samarium oxide (Sm2O3). The present results show some possibilities of magnetic recovery of transition metals and synthesis of some novel structures composed of magnetic particles and transition metals utilizing MTB.

  5. Co-reduction of aluminium and lanthanide ions in molten fluorides: Application to cerium and samarium extraction from nuclear wastes

    Energy Technology Data Exchange (ETDEWEB)

    Gibilaro, M. [Laboratoire de Genie Chimique UMR 5503, Departement Procedes Electrochimiques, Universite de Toulouse, 31062 Toulouse Cedex 9 (France); Massot, L. [Laboratoire de Genie Chimique UMR 5503, Departement Procedes Electrochimiques, Universite de Toulouse, 31062 Toulouse Cedex 9 (France)], E-mail: massot@chimie.ups-tlse.fr; Chamelot, P.; Taxil, P. [Laboratoire de Genie Chimique UMR 5503, Departement Procedes Electrochimiques, Universite de Toulouse, 31062 Toulouse Cedex 9 (France)

    2009-09-01

    This work concerns the method of co-reduction process with aluminium ions in LiF-CaF{sub 2} medium (79-21 mol.%) on tungsten electrode for cerium and samarium extraction. Electrochemical techniques such as cyclic and square wave voltammetries, and potentiostatic electrolyses were used to study the co-reduction of CeF{sub 3} and SmF{sub 3} with AlF{sub 3}. For each of these elements, specific peaks of Al-Ce and Al-Sm alloys formation were observed by voltammetry as well as peaks of pure cerium and aluminium, and pure samarium and aluminium respectively. The difference of potential measured between the solvent reduction and the alloy formation suggests expecting an extraction efficiency of 99.99% of each lanthanide by the process. Different intermetallic compounds were obtained for different potentiostatic electrolysis and were characterised by Scanning Electron Microscopy with EDS probe. The validity of the process was verified by carrying out cerium and samarium extractions in the form of Al-Ln alloy; the extraction efficiency was 99.5% for Ce(III) and 99.4% for Sm(III)

  6. Structural and luminescence properties of samarium doped lead alumino borate glasses

    Science.gov (United States)

    Mohan, Shaweta; Kaur, Simranpreet; Singh, D. P.; Kaur, Puneet

    2017-11-01

    The study reports the effect of samarium concentration on the physical, structural and spectroscopic characteristics of samarium doped lead alumino borate glasses having composition 20PbO-(10-x)Al2O3-70B2O3-xSm2O3; x = 0.1, 0.5, 1.0 and 2.0 mol %. The glasses were fabricated by conventional melt-quenching technique and then characterized by XRD, FTIR, optical absorption and fluorescence spectra. X-ray diffraction studies confirmed the amorphous nature of the prepared glasses. FTIR spectra indicate the presence of BO3, BO4, AlO6 and a few other structural groups. Various physical properties such as density, molar volume, refractive index, rare earth ion concentration, boron-boron distance and polarizability etc. were determined using conventional methods and standard formulae. The Judd-Ofelt theory was applied on the optical absorption spectra of the glasses to evaluate the three phenomenological intensity parameters Ω2, Ω4 and Ω6. The value of Ω2 was found to be highest for glass with 1 mol% Sm2O3 and attributed to the asymmetry of the ligand field at the rare earth ion site and the rare earth oxygen (Sm-O) covalency. The calculated intensity parameters and fluorescence spectra were further used to predict the radiative transition probability (A), radiative lifetime (τR), branching ratio (βR), peak wavelength (λp), effective line widths (Δλeff) and stimulated emission cross-section (σ) for the characteristic 4G5/2 → 6H5/2, 6H7/2 and 6H9/2 transitions of the Sm3+ ion. Concentration quenching was observed for 2 mol% concentration of Sm2O3 and ascribed to energy transfer through various cross-relaxation channels between Sm3+ ions. Reasonably high values of branching ratios and stimulated emission cross-section for the prepared glasses points towards their utility in the development of visible lasers emitting in the reddish-orange spectral region. However, the glass with 1 mol% Sm2O3 was found to show better radiative properties.

  7. Tailoring polymer properties with layered silicates

    Science.gov (United States)

    Xu, Liang

    Polymer layered silicate nanocomposites have found widespread applications in areas such as plastics, oil and gas production, biomedical, automotive and information storage, but their successful commercialization critically depends on consistent control over issues such as complete dispersion of layered silicate into the host polymer and optimal interaction between the layered silicates and the polymers. Polypropylene is a commercially important polymer but usually forms intercalated structures with organically modified layered silicate upon mixing, even it is pre-treated with compatibilizing agent such as maleic anhydride. In this work, layered silicate is well dispersed in ammonium modified polypropylene but does not provide sufficient reinforcement to the host polymer due to poor interactions. On the other hand, interactions between maleic anhydride modified polypropylene and layered silicate are fine tuned by using a small amount of maleic anhydride and mechanical strength of the resultant nanocomposites are significantly enhanced. In particular, the melt rheological properties of layered silicate nanocomposites with maleic anhydride functionalized polypropylene are contrasted to those based on ammonium-terminated polypropylene. While the maleic anhydride treated polypropylene based nanocomposites exhibit solid-like linear dynamic behavior, consistent with the formation of a long-lived percolated nanoparticle network, the single-end ammonium functionalized polypropylene based nanocomposites demonstrated liquid-like behavior at comparable montmorillonite concentrations. The differences in the linear viscoelasticity are attributed to the presence of bridging interaction in maleic anhydride functionalized nanocomposites, which facilitates formation of a long-lived silicate network mediated by physisorbed polymer chains. Further, the transient shear stress of the maleic anhydride functionalized nanocomposites in start-up of steady shear is a function of the shear

  8. X-ray Induced Luminescence Spectroscopy of Samarium Doped Barium Sulfate Prepared by Sintering Method

    Science.gov (United States)

    Kumeda, T.; Maeda, K.; Shirano, Y.; Fujiwara, K.; Sakai, K.; Ikari, T.

    2015-06-01

    X-ray induced luminescence (XL) properties of phosphor materials made of samarium doped barium sulfate have been investigated. The samples were prepared by sintering method heated at 900-1250 °C for 3 hours in air from the mixture of BaSO4 and Sm2O3. The concentration of Sm were prepared from 0.01-6 at.%. In as-prepared sample, the Sm3+ was detected by photoluminescence (PL). The PL intensity is maximum about 2 at.% with Sm, and then starts decreasing. The PL intensity showed concentration quenching. The XL observed Sm2+ and Sm3+ ions. The XL was shown from the sample sintered up to 1200 °C. The XL intensity increased with Sm concentration up to 1 at.%. The intensity was almost constant larger than 1 at.% Sm. These concentration dependences is different since the X-ray energy absorbed to the host material at once, and the energy transferred to both Sm3+ and Sm2+ ions. Sm doped BaSO4 is found a host for XL phosphor materials.

  9. High-κ Samarium-Based Metal-Organic Framework for Gate Dielectric Applications.

    Science.gov (United States)

    Pathak, Abhishek; Chiou, Guan Ru; Gade, Narsinga Rao; Usman, Muhammad; Mendiratta, Shruti; Luo, Tzuoo-Tsair; Tseng, Tien Wen; Chen, Jenq-Wei; Chen, Fu-Rong; Chen, Kuei-Hsien; Chen, Li-Chyong; Lu, Kuang-Lieh

    2017-07-05

    The self-assembly of a samarium-based metal-organic framework [Sm2(bhc)(H2O)6]n (1) in good yield was achieved by reacting Sm(NO3)3·6H2O with benzenehexacarboxylic acid (bhc) in a mixture of H2O-EtOH under hydrothermal conditions. A structural analysis showed that compound 1 crystallized in a space group of Pnmn and adopted a 3D structure with (4,8) connected nets. Temperature dependent dielectric measurements showed that compound 1 behaves as a high dielectric material with a high dielectric constant (κ = 45.1) at 5 kHz and 310 K, which is comparable to the values for some of the most commonly available dielectric inorganic metal oxides such as Sm2O3, Ta2O5, HfO2, and ZrO2. In addition, electrical measurements of 1 revealed an electrical conductivity of about 2.15 × 10-7 S/cm at a frequency of 5 kHz with a low leakage current (Ileakage = 8.13 × 10-12 Amm-2). Dielectric investigations of the Sm-based MOF provide an effective path for the development of high dielectric materials in the future.

  10. Pyroelectric properties and electrical conductivity in samarium doped BiFeO 3 ceramics

    KAUST Repository

    Yao, Yingbang

    2012-06-01

    Samarium (Sm 3+) doped BiFeO 3 (BFO) ceramics were prepared by a modified solid-state-reaction method which adopted a rapid heating as well as cooling during the sintering process. The pyroelectric coefficient increased from 93 to 137 μC/m 2 K as the Sm 3+ doping level increased from 1 mol% to 8 mol%. Temperature dependence of the pyroelectric coefficient showed an abrupt decrease above 80 °C in all samples, which was associated with the increase of electrical conductivity with temperature. This electrical conduction was attributed to oxygen vacancy existing in the samples. An activation energy of ∼0.7 eV for the conduction process was found to be irrespective of the Sm 3+ doping level. On the other hand, the magnetic Néel temperature (T N) decreased with increasing Sm 3+ doping level. On the basis of our results, the effects of Sm doping level on the pyroelectric and electrical properties of the BFO were revealed. © 2011 Elsevier Ltd. All rights reserved.

  11. Characterization of luminescent samarium doped HfO{sub 2} coatings synthesized by spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Chacon-Roa, C [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-IPN, Legaria 694, Col. Irrigacion, C.P. 11500, Mexico D.F. (Mexico); Guzman-Mendoza, J [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-IPN, Legaria 694, Col. Irrigacion, C.P. 11500, Mexico D.F. (Mexico); Aguilar-Frutis, M [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-IPN, Legaria 694, Col. Irrigacion, C.P. 11500, Mexico D.F. (Mexico); Garcia-Hipolito, M [Departamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, A.P. 70-360 Coyoacan 04510, Mexico, D.F. (Mexico); Alvarez-Fragoso, O [Departamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, A.P. 70-360 Coyoacan 04510, Mexico, D.F. (Mexico); Falcony, C [Departamento de Fisica, CINVESTAV-IPN, A. P. 14-740, 07000 Mexico D.F. (Mexico)

    2008-01-07

    Trivalent samarium (Sm{sup 3+}) doped hafnium oxide (HfO{sub 2}) films were deposited using the spray pyrolysis deposition technique. The films were deposited on Corning glass substrates at temperatures ranging from 300 to 550 deg. C using chlorides as raw materials. Films, mostly amorphous, were obtained when deposition temperatures were below 350 deg. C. However, for temperatures higher than 400 deg. C, the films became polycrystalline, presenting the HfO{sub 2} monoclinic phase. Scanning electron microscopy of the films revealed a rough surface morphology with spherical particles. Also, electron energy dispersive analysis was performed on these films. The photoluminescence and cathodoluminescence characteristics of the HfO{sub 2} : SmCl{sub 3} films, measured at room temperature, exhibited four main bands centred at 570, 610, 652 and 716 nm, which are due to the well-known intra-4f transitions of the Sm{sup 3+} ion. It was found that the overall emission intensity rose as the deposition temperature was increased. Furthermore, a concentration quenching of the luminescence intensity was also observed.

  12. Samarium-153 EDTMP for metastatic bone pain palliation: the impact of europium impurities.

    Science.gov (United States)

    Kalef-Ezra, J A; Valakis, S T; Pallada, S

    2015-02-01

    To evaluate the impact on the radiation protection policies of the radiocontaminants in Samarium-153 ethylenediamine tetramethylene phosphonate ((153)Sm-EDTMP). The internal contamination of patients treated with (153)Sm-EDMTP for palliation of painful disseminated multiple bone metastases due to long-lived impurities was assessed by direct measurements. These measurements were coupled with dose-rate measurements close to their bodies and spectroscopic analysis of the residual activity in post-treatment radiopharmaceutical vials. Whole-body counting carried out in six patients showed a 30-81-kBq europium -152 plus europium-154 contamination. The 0.85 mean (152)Eu- to -(154)Eu activity ratio obtained by direct counting was similar to that assessed by analysis of post-treatment residual activities in twelve radiopharmaceutical vials following radiopharmaceutical injection. The long-lived radiocontaminants in the patient's bodies and the treatment wastes require modifications of the applicable radiation protection policies. Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  13. Luminescence of trivalent samarium ions in silver and tin co-doped aluminophosphate glass

    Science.gov (United States)

    Jiménez, José A.; Lysenko, Sergiy; Liu, Huimin; Sendova, Mariana

    2011-06-01

    This work presents the spectroscopic properties of trivalent samarium ions in a melt-quenched aluminophosphate glass containing silver and tin. Addition of 4 mol% of each Ag 2O and SnO into the glass system with 2 mol% Sm 2O 3 results in Sm 3+ ions luminescence under non-resonant UV excitation owing to energy transfer from single silver ions and/or twofold-coordinated Sn centers. Assessment of luminescence spectra and decay dynamics suggest the energy transfer mechanism to be essentially of the resonant radiative type. Moreover, a connection between the luminescent and structural properties of the rare-earth doped glass system was demonstrated. Raman spectroscopy characterization revealed that no significant variation in the glass matrix is induced by Sm 3+ doping at the concentration employed. A comparison was made with a structural study performed on the Eu 3+ doped system (containing 2 mol% Eu 2O 3 along with 4 mol% of each Ag 2O and SnO) where the radiative energy transfer mechanism was previously established. The data appears consistent regarding the lack of variation in glass structure upon the Eu 3+ and Sm 3+ doping in connection with the dominance of the radiative transfer in the matrix. Thermal treatment of the material leads to precipitation of Ag nanoparticles of a broad size range inside the dielectric as observed by transmission electron microspcopy. Assessment of 4G 5/2 excited state decay in Sm 3+ ions shows no influence from the silver particles.

  14. Samarium (III) adsorption on bentonite modified with N-(2-hydroxyethyl) ethylenediamine.

    Science.gov (United States)

    Li, Dandan; Chang, Xijun; Hu, Zheng; Wang, Qihui; Li, Ruijun; Chai, Xiaoli

    2011-02-15

    A new material has been synthesized using dry process to activate bentonite followed by N-(2-hydroxyethyl) ethylenediamine connecting chlorosilane coupling agent. The synthesized new material was characterized by elemental analysis, FT-IR and thermogravimetry which proved that bentonite was successfully modified. The most interesting trait of the new material was its selective adsorption for rare earth elements. A variety of conditions of the new material were investigated for adsorption. The optimal conditions were determined with respect to pH and shaking time. Samarium (Sm) was quantitatively adsorbed at pH 4 and shaking time of 2 min onto the new material. Under these conditions the maximum static adsorption capacity of Sm(III) was found to be 17.7 mg g(-1). The adsorbed Sm(III) ion were quantitatively eluted by 2.0 mL 0.1 mol L(-1) HCl and 5% CS (NH(2))(2) solution. According to IUPAC definition, the detection limit (3σ) of this method was 0.60 ng mL(-1). The relative standard deviation (RSD) under optimum conditions was less than 3% (n=8). The new material also was applied for the preconcentration of trace Sm(III) in environmental samples with satisfactory results. Copyright © 2010 Elsevier B.V. All rights reserved.

  15. Nanoscale zinc silicate from phytoliths

    Science.gov (United States)

    Qadri, S. B.; Gorzkowski, E. P.; Rath, B. B.; Feng, C. R.; Amarasinghe, R.; Freitas, J. A.; Culbertson, J. C.; Wollmershauser, J. A.

    2017-10-01

    We report a faster, less expensive method of producing zinc silicate nanoparticles. Such particles are used in high volume to make phosphors and anti-corrosion coatings. The approach makes use of phytoliths (plant rocks), which are microscopic, amorphous, and largely silicate particles embedded in plants, that lend themselves to being easily broken down into nanoparticles. Nanoparticles of Zn2SiO4 were produced in a two stage process. In the refinement stage, plant residue, mixed with an appropriate amount of ZnO, was heated in an argon atmosphere to a temperature exceeding 1400 °C for four to six hours and then heated in air at 650 °C to remove excess carbon. TEM shows 50-100 nm nanoparticles. Raman scattering indicates that only the -Zn2SiO4 crystalline phase was present. X-ray analysis indicated pure rhombohedral R 3 bar phase results from using rice/wheat husks. Both samples luminesced predominantly at 523 nm when illuminated with X-rays or UV laser light.

  16. Silicates materials of high vacuum technology

    CERN Document Server

    Espe, Werner

    2013-01-01

    Materials of High Vacuum Technology, Volume 2: Silicates covers silicate insulators of special importance to vacuum technology. The book discusses the manufacture, composition, and physical and chemical properties of technical glasses, quartz glass, quartzware, vycor glass, ceramic materials, mica, and asbestos.

  17. Mesoporous Silicate Materials in Sensing

    Directory of Open Access Journals (Sweden)

    Paul T. Charles

    2008-08-01

    Full Text Available Mesoporous silicas, especially those exhibiting ordered pore systems and uniform pore diameters, have shown great potential for sensing applications in recent years. Morphological control grants them versatility in the method of deployment whether as bulk powders, monoliths, thin films, or embedded in coatings. High surface areas and pore sizes greater than 2 nm make them effective as adsorbent coatings for humidity sensors. The pore networks also provide the potential for immobilization of enzymes within the materials. Functionalization of materials by silane grafting or through cocondensation of silicate precursors can be used to provide mesoporous materials with a variety of fluorescent probes as well as surface properties that aid in selective detection of specific analytes. This review will illustrate how mesoporous silicas have been applied to sensing changes in relative humidity, changes in pH, metal cations, toxic industrial compounds, volatile organic compounds, small molecules and ions, nitroenergetic compounds, and biologically relevant molecules.

  18. Samarium oxide as a radiotracer to evaluate the in vivo biodistribution of PLGA nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mandiwana, Vusani, E-mail: VMandiwana@csir.co.za; Kalombo, Lonji, E-mail: LKalombo@csir.co.za [Centre of Polymers and Composites, CSIR (South Africa); Venter, Kobus, E-mail: Kobus.Venter@mrc.ac.za [South African Medical Research Council (South Africa); Sathekge, Mike, E-mail: Mike.Sathekge@up.ac.za [University of Pretoria and Steve Biko Academic Hospital, Department of Nuclear Medicine (South Africa); Grobler, Anne, E-mail: Anne.Grobler@nwu.ac.za; Zeevaart, Jan Rijn, E-mail: zeevaart@necsa.co.za [North-West University, DST/NWU Preclinical Drug Development Platform (South Africa)

    2015-09-15

    Developing nanoparticulate delivery systems that will allow easy movement and localization of a drug to the target tissue and provide more controlled release of the drug in vivo is a challenge in nanomedicine. The aim of this study was to evaluate the biodistribution of poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles containing samarium-153 oxide ([{sup 153}Sm]Sm{sub 2}O{sub 3}) in vivo to prove that orally administered nanoparticles alter the biodistribution of a drug. These were then activated in a nuclear reactor to produce radioactive {sup 153}Sm-loaded-PLGA nanoparticles. The nanoparticles were characterized for size, zeta potential, and morphology. The nanoparticles were orally and intravenously (IV) administered to rats in order to trace their uptake through imaging and biodistribution studies. The {sup 153}Sm-loaded-PLGA nanoparticles had an average size of 281 ± 6.3 nm and a PDI average of 0.22. The zeta potential ranged between 5 and 20 mV. The [{sup 153}Sm]Sm{sub 2}O{sub 3} loaded PLGA nanoparticles, orally administered were distributed to most organs at low levels, indicating that there was absorption of nanoparticles. While the IV injected [{sup 153}Sm]Sm{sub 2}O{sub 3}-loaded PLGA nanoparticles exhibited the highest localization of nanoparticles in the spleen (8.63 %ID/g) and liver (3.07 %ID/g), confirming that nanoparticles are rapidly removed from the blood by the RES, leading to rapid uptake in the liver and spleen. From the biodistribution data obtained, it is clear that polymeric nanoscale delivery systems would be suitable for improving permeability and thus the bioavailability of therapeutic compounds.

  19. Samarium oxide as a radiotracer to evaluate the in vivo biodistribution of PLGA nanoparticles

    Science.gov (United States)

    Mandiwana, Vusani; Kalombo, Lonji; Venter, Kobus; Sathekge, Mike; Grobler, Anne; Zeevaart, Jan Rijn

    2015-09-01

    Developing nanoparticulate delivery systems that will allow easy movement and localization of a drug to the target tissue and provide more controlled release of the drug in vivo is a challenge in nanomedicine. The aim of this study was to evaluate the biodistribution of poly( d, l-lactide- co-glycolide) (PLGA) nanoparticles containing samarium-153 oxide ([153Sm]Sm2O3) in vivo to prove that orally administered nanoparticles alter the biodistribution of a drug. These were then activated in a nuclear reactor to produce radioactive 153Sm-loaded-PLGA nanoparticles. The nanoparticles were characterized for size, zeta potential, and morphology. The nanoparticles were orally and intravenously (IV) administered to rats in order to trace their uptake through imaging and biodistribution studies. The 153Sm-loaded-PLGA nanoparticles had an average size of 281 ± 6.3 nm and a PDI average of 0.22. The zeta potential ranged between 5 and 20 mV. The [153Sm]Sm2O3 loaded PLGA nanoparticles, orally administered were distributed to most organs at low levels, indicating that there was absorption of nanoparticles. While the IV injected [153Sm]Sm2O3-loaded PLGA nanoparticles exhibited the highest localization of nanoparticles in the spleen (8.63 %ID/g) and liver (3.07 %ID/g), confirming that nanoparticles are rapidly removed from the blood by the RES, leading to rapid uptake in the liver and spleen. From the biodistribution data obtained, it is clear that polymeric nanoscale delivery systems would be suitable for improving permeability and thus the bioavailability of therapeutic compounds.

  20. Fabrication and properties of samarium doped calcium sulphate thin films using spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Reghima, Meriem [Université Tunis El Manar, Faculté des Sciences de Tunis, Département de Physique, LR99ES13 Laboratoire de Physique de la Matière Condensée (LPMC), 2092 Tunis, Tunisie (Tunisia); Institut d' Electronique et des systèmes, Unité Mixte de Recherche 5214 UM2-CNRS (ST2i) – Université Montpellier, 860 rue de Saint Priest, Bâtiment 5, 34097 Montpellier (France); Faculté des Sciences de Bizerte, Université de Carthage, Zarzouna 7021 (Tunisia); Guasch, Cathy [Institut d' Electronique et des systèmes, Unité Mixte de Recherche 5214 UM2-CNRS (ST2i) – Université Montpellier, 860 rue de Saint Priest, Bâtiment 5, 34097 Montpellier (France); Azzaza, Sonia; Alleg, Safia [Laboratoire de Magnétisme et Spectroscopie des Solides (LM2S), Département de Physique, Faculté des Sciences, Université Badji Mokhtar Annaba, B.P. 12, 23000 Annaba (Algeria); Kamoun-Turki, Najoua [Université Tunis El Manar, Faculté des Sciences de Tunis, Département de Physique, LR99ES13 Laboratoire de Physique de la Matière Condensée (LPMC), 2092 Tunis, Tunisie (Tunisia)

    2016-10-01

    Using low cost spray pyrolysis technique, polycrystalline CaSO{sub 4} thin films were successfully grown on a glass substrate with a thickness of about 1 μm. Samarium doping has been performed on CaSO{sub 4} thin films to explore luminescence properties. The characterizations of these films were carried out using X-ray diffraction, Scanning Electron Microscopy and optical measurements. The structural analyses reveal the existence of hexagonal CaSO{sub 4} phase with a (200) preferred orientation belonging to CaS compound for substrate temperatures below 350 °C. It is shown that the crystallinity of the sprayed thin films can be improved by increasing substrate temperature up to 250 °C. Warren-Averbach analysis has been applied on X-ray diffractogram to determine structural parameters involving the phase with its amount, the grain size and the lattice parameters using Maud software. The surface topography shows a rough surface covered by densely packed agglomerated clusters having faceted and hexagonal shapes. Energy dispersive microscopy measurements confirm the presence of calcium and sulfur in equal proportions as well as high percentage of oxygen. Photoluminescence at room temperature revealed that luminescence peaks are attributed to the intrinsic emission of pure CaSO{sub 4} phase. - Highlights: • Warren Averbach analysis reveal the presence of hcp structure of CaSO{sub 4} phase. • A mixture of CaSO{sub 4} and CaHO{sub 4.5}S phases has been detected for lower T{sub s}. • For increasing T{sub s}, the CaHO{sub 4.5}S phase has been disappeared. • The origin of PL peaks has been identified.

  1. Alkali Silicate Vehicle Forms Durable, Fireproof Paint

    Science.gov (United States)

    Schutt, John B.; Seindenberg, Benjamin

    1964-01-01

    The problem: To develop a paint for use on satellites or space vehicles that exhibits high resistance to cracking, peeling, or flaking when subjected to a wide range of temperatures. Organic coatings will partially meet the required specifications but have the inherent disadvantage of combustibility. Alkali-silicate binders, used in some industrial coatings and adhesives, show evidence of forming a fireproof paint, but the problem of high surface-tension, a characteristic of alkali silicates, has not been resolved. The solution: Use of a suitable non-ionic wetting agent combined with a paint incorporating alkali silicate as the binder.

  2. Model Dust Envelopes Around Silicate Carbon Stars

    Directory of Open Access Journals (Sweden)

    Kyung-Won Suh

    2006-03-01

    Full Text Available We have modeled dust envelopes around silicate carbon stars using optical properties for a mixture of amorphous carbon and silicate dust grains paying close attention to the infrared observations of the stars. The 4 stars show various properties in chemistry and location of the dust shell. We expect that the objects that fit a simple detached silicate dust shell model could be in the transition phase of the stellar chemistry. For binary system objects, we find that a mixed dust chemistry model would be necessary.

  3. Optical properties and electronic transitions of zinc oxide, ferric oxide, cerium oxide, and samarium oxide in the ultraviolet and extreme ultraviolet

    DEFF Research Database (Denmark)

    Pauly, N; Yubero, F; Espinós, J P

    2017-01-01

    Optical properties and electronic transitions of four oxides, namely zinc oxide, ferric oxide, cerium oxide, and samarium oxide, are determined in the ultraviolet and extreme ultraviolet by reflection electron energy loss spectroscopy using primary electron energies in the range 0.3-2.0 keV. This...

  4. Siliceous microfossil extraction from altered Monterey rocks

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, C.O.; Casey, R.E.

    1986-04-01

    Samples of altered Monterey rocks of differing lithologies were processed by various methods to develop new techniques for extracting siliceous microfossils. The preliminary use of thin sections made from the same rocks reduced the number of probable samples (samples worth further processing) by about one-third. Most of the siliceous microfossils contained in altered Monterey rocks appear to be highly recrystallized and are extremely fragile; however, some contained silicified and silica-infilled radiolarians and planktonic and benthonic foraminifera, which are very tough. In general the most useful techniques were gently hydrochloric acid, hydrogen peroxide, formic acid, monosodium glutamate, and regular siliceous microfossil extraction techniques. Unsuccessful techniques and a new siliceous microfossil flotation technique are also documented.

  5. Carbon Monoxide Silicate Reduction System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Carbon Monoxide Silicate Reduction System (COSRS) is a novel technology for producing large quantities of oxygen on the Moon. Oxygen yields of 15 kilograms per...

  6. Carbon Monoxide Silicate Reduction System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Carbon Monoxide Silicate Reduction System (COSRS) is an innovative method that for the first time uses the strong reductant carbon monoxide to both reduce iron...

  7. Peralkaline silicic volcanic rocks in northwestern nevada.

    Science.gov (United States)

    Noble, D C; Chipman, D W; Giles, D L

    1968-06-21

    Late Tertiary silicic ashflow tuffs and lavas peralkaline in chemical character (atomic Na + K greater than Al), mainly comendites, occur over wide areas in northwestern Nevada and appear to be widespread in southeastern Oregon. Such peralkaline rocks-which are not uncommon in the western United States-and other chemically unusual silicic rocks are found near the margins rather than toward the center of the Great Basin.

  8. Optical response and magnetic characteristic of samarium doped zinc phosphate glasses containing nickel nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Azmi, Siti Amlah M.; Sahar, M.R., E-mail: mrahim057@gmail.com

    2015-11-01

    A magnetic glass of composition 40ZnO–(58−x) P{sub 2}O{sub 5}–1Sm{sub 2}O{sub 3}–xNiO, with x=0.0, 1.0, 1.5 and 2.0 mol% is prepared by melt-quenching technique. The glass is characterized by X-ray diffraction, high-resolution transmission electron microscope (HRTEM), photoluminescence (PL) spectroscopy and vibrating sample magnetometer (VSM) analysis. The X-rays diffraction confirms the amorphous nature of the glass while the HRTEM analysis reveals the presence of nickel nanoparticles in the glass samples. High-resolution TEM reveals that the lattice spacing of nickel nanoparticles is 0.35 nm at (100) plane. Photoluminescence emission shows the existence of four peaks that correspond to the transition from the upper level of {sup 4}G{sub 5/2} to the lower level of {sup 6}H{sub 5/2}, {sup 6}H{sub 7/2}, {sup 6}H{sub 9/2,} and {sup 6}H{sub 11/2.} It is observed that all peaks experience significant quenching effect with the increasing concentration of nickel nanoparticles, suggesting a strong energy transfer from excited samarium ions to the nickel ions. The glass magnetization and susceptibility at 12 kOe at room temperature are found to be in the range of (3.87±0.17×10{sup −2}–7.19±0.39×10{sup −2}) emu/g and (3.24±0.16×10{sup −6}–5.99±0.29×10{sup −6}) emu/Oe g respectively. The obtained hysteresis curve indicates that the glass samples are paramagnetic materials. The studied glass can be further used towards the development of magneto-optical functional glass. - Highlights: • Sm{sup 3+} doped zinc phosphate glass embedded with Ni NPs has been prepared. • The Laue pattern and lattice spacing of Ni NPs are confirmed by HRTEM image. • The magnetic response of glasses has been studied through VSM analysis. • Enhancement factor and decay half-lifetime are investigated.

  9. Treatment of bone pain secondary to metastases using samarium-153-EDTMP

    Directory of Open Access Journals (Sweden)

    Elba Cristina Sá de Camargo Etchebehere

    Full Text Available CONTEXT: More than 50% of patients with prostate, breast or lung cancer will develop painful bone metastases. The purpose of treating bone metastases is to relieve pain, reduce the use of steroids and to maintain motion. OBJECTIVE: To evaluate the use of samarium-153-EDTMP (153Sm-EDTMP for the treatment of bone pain secondary to metastases that is refractory to clinical management. TYPE OF STUDY: Retrospective. SETTING: Division of Nuclear Medicine, Universidade Estadual de Campinas (Unicamp. METHODS: Fifty-eight patients were studied (34 males with mean age 62 years; 31 patients had prostate cancer, 20 had breast cancer, three had lung cancer, one had lung hemangioendothelioma, one had parathyroid adenocarcinoma, one had osteosarcoma and one had an unknown primary tumor. All patients had multiple bone metastases demonstrated by bone scintigraphy using 99mTc-MDP,and were treated with 153Sm-EDTMP. Response to treatment was graded as good (pain reduction of 50-100%, intermediate (25-49% and poor (0-24%. RESULTS: All patients showed good uptake of 153Sm-EDTMP by bone metastases. Among the patients with prostate cancer, intermediate or good response to therapy occurred in 80.6% (25 patients and poor response in 19.4% (6. Among the patients with breast cancer, 85% (17 showed intermediate or good response to therapy while 15% (3 showed poor response. All three patients with lung cancer showed poor response to treatment. The lung hemangioendothelioma and unknown primary lesion patients showed intermediate response to treatment; the osteosarcoma and parathyroid adenocarcinoma patients showed good response to treatment. No significant myelotoxicity occurred. DISCUSSION: Pain control is important for improving the quality of life of patients with advanced cancers. The mechanism by which pain is relieved with the use of radionuclides is still not yet completely understood, however, the treatment is simple and provides a low risk of mielotoxicity

  10. Anchoring samarium oxide nanoparticles on reduced graphene oxide for high-performance supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Dezfuli, Amin Shiralizadeh [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Ganjali, Mohammad Reza, E-mail: ganjali@khayam.ut.ac.ir [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Biosensor Research Center, Endocrinology & Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Naderi, Hamid Reza [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of)

    2017-04-30

    Highlights: • Samarium oxide nanoparticles have been anchored on the surface of reduced graphene oxide for the first time. • Sm{sub 2}O{sub 3}/RGO nanocomposite show high capacitance, good rate and cycling performance. • Sm{sub 2}O{sub 3}/RGO nanocomposite can serve as efficient electrode material for energy storage. • The best composite electrode exhibits specific capacitance of 321 F g{sup −1} in 2 mV s{sup −1}. - Abstract: We have synthesized Sm{sub 2}O{sub 3} nanoparticles (SmNs) and anchored them onto the surface of reduced graphene oxide (RGO) through a self-assembly thereof by utilizing a facile sonochemical procedure. The nanomaterials were characterized by means of powder X-ray diffraction (XRD), Field-emission scanning electron microscopy (FE-SEM), fourier transform infrared spectroscopy (FT-IR) spectra, and X-ray photoelectron spectroscopy (XPS). As the next step, the supercapacitive behavior of the resulting nanocomposites were investigated when used as electrode material, through with cyclic voltammetric (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) techniques. The SmNs decorated RGO (SmN-RGO) nanocomposites were found to possess a specific capacitance (SC) of 321 F g{sup −1} when used in a 0.5 M Na{sub 2}SO{sub 4} solution as an electrolyte, in a scan rate of 2 mV s{sup −1}. The SC of the SmN-RGO based electrodes were also found to be 268 F g{sup −1} at a current density of 2 A g{sup −1} through galvanostatic charge-discharge tests. The outstanding properties of the SmN-RGOs were attributed to synergy of the high charge mobility of SmNs and the flexibility of the sheets of RGOs. Additionally, the nano-composite revealed a unique cycling durability (maintaining 99% of its SC even after 4000 cycles).

  11. Thermodynamics and Kinetics of Silicate Vaporization

    Science.gov (United States)

    Jacobson, Nathan S.; Costa, Gustavo C. C.

    2015-01-01

    Silicates are a common class of materials that are often exposed to high temperatures. The behavior of these materials needs to be understood for applications as high temperature coatings in material science as well as the constituents of lava for geological considerations. The vaporization behavior of these materials is an important aspect of their high temperature behavior and it also provides fundamental thermodynamic data. The application of Knudsen effusion mass spectrometry (KEMS) to silicates is discussed. There are several special considerations for silicates. The first is selection of an appropriate cell material, which is either nearly inert or has well-understood interactions with the silicate. The second consideration is proper measurement of the low vapor pressures. This can be circumvented by using a reducing agent to boost the vapor pressure without changing the solid composition or by working at very high temperatures. The third consideration deals with kinetic barriers to vaporization. The measurement of these barriers, as encompassed in a vaporization coefficient, is discussed. Current measured data of rare earth silicates for high temperature coating applications are discussed. In addition, data on magnesium-iron-silicates (olivine) are presented and discussed.

  12. Effect of Current Density on Thermodynamic Properties of Nanocrystalline Palladium Capped Samarium Hydride Thin Film Switchable Mirrors

    Directory of Open Access Journals (Sweden)

    Pushpendra Kumar

    2007-01-01

    Full Text Available A 55 nm samarium film capped with a 10 nm palladium overlayer switched from a metallic reflecting to a semiconducting, transparent in visible state during ex-situ hydrogen loading via electrochemical means in 1 M KOH electrolytic aqueous solution at room temperature. The switching between metal to semiconductor was accompanied by measurement of transmittance during hydrogen loading/unloading. The effect of current density on switching and thermodynamic properties was studied between dihydride state (FCC phase and trihydride state (hexagonal phase. From the plateau of partial pressure of hydrogen at x=2.6, enthalpy of formation was calculated at different current densities. The diffusion coefficients and switching kinetics are shown to depend on applied current density.

  13. Targeted bone marrow radioablation with 153Samarium-lexidronam promotes allogeneic hematopoietic chimerism and donor-specific immunologic hyporesponsiveness.

    Science.gov (United States)

    Inverardi, Luca; Linetsky, Elina; Pileggi, Antonello; Molano, R Damaris; Serafini, Aldo; Paganelli, Giovanni; Ricordi, Camillo

    2004-03-15

    Transplantation tolerance, defined as acceptance of a graft by an otherwise fully immunocompetent host, has been an elusive goal. Although robust tolerance has been achieved by the induction of stable hematopoietic chimerism after bone marrow transplantation, lethal or sublethal radiation conditioning used to induce long-term chimerism precludes its clinical use. We studied whether targeted delivery of radiation to bone marrow could allow for bone marrow cell (BMC) engraftment, chimerism, and donor-specific tolerance in the absence of the side effects associated with external irradiation. We administered a radioactive bone-seeking compound (Samarium-Lexidronam, Quadramet, Berlex Laboratories, Wayne, NJ) together with transient T-cell costimulatory blockade to recipient mice. Allogeneic BMCs were given 7 or 14 days after preconditioning. Costimulatory blockade was obtained by the use of an anti-CD154 antibody for 4 weeks. Chimerism was assessed by flow cytometry. Mice then received donor-specific and third-party skin grafts. Graft survival was analyzed with mechanisms of donor-specific hyporesponsiveness. High levels of stable chimerism across an allogeneic barrier were achieved in mice by a single administration of Samarium-Lexidronam, transient T-cell costimulatory blockade, and BMC transplantation. A large percentage of chimeric animals retained donor-derived skin grafts for more than 120 days without requiring additional immunosuppression, suggesting that harsh cytotoxic preconditioning is not necessary to achieve stable chimerism and donor specific hyporesponsiveness. Analysis of the T-cell repertoire in chimeras indicates T-cell deletional mechanisms. These data broaden the potential use of BMC transplantation for tolerance induction and argue for its potential in treating autoimmune diseases.

  14. Sorption of samarium in soils: influence of soil properties and Sm concentration

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez-Guinart, Oriol; Salaberria, Aitor; Rigol, Anna; Vidal, Miquel [Analytical Chemistry department, Faculty of Chemistry, University of Barcelona, Marti i Franques 1-11, 08028, Barcelona (Spain)

    2014-07-01

    Due to the fact that barriers of Deep Geological Repositories (DGR) may lose efficiency before the radioisotopes present in the High Level Radioactive Waste (HLRW) completely decay, it is possible that, in the long-term, radioactive leachates may escape from the DGR and reach the soil and water compartments in the biosphere. Therefore, it is required to examine the interaction and mobility of radionuclides present in the HLRW, or their chemical analogues, to predict the impact of their eventual incorporation in the biosphere and to assess the derived risk. Although relevant data have been recently obtained for a few radionuclides in soils, there are still some important gaps for some radionuclides, such us for samarium (Sm). Sm is a lanthanide that, besides being considered as a natural analogue of actinides, may also be present in HLRW in the form of the radioactive isotope {sup 151}Sm. The main objective of this work was to obtain sorption data (K{sub d}) of {sup 151}Sm gathered from a set of soil samples physicochemical fully-characterized (pH, texture, cationic exchange capacity, soil solution cationic composition, organic matter, carbonate and metallic oxides content, etc.). Additionally, as an alternative for testing sorption capacity of radionuclides in soils is the use of the corresponding stable isotope or a chemical analogue, the influence of Sm concentration was also checked. To evaluate {sup 151}Sm sorption, batch assays were carried out for each soil sample, which consisted in a pre-equilibration step of 2 g of each soil with 50 ml of double deionised water, and a subsequent equilibration step with the same solution, but labelled with {sup 151}Sm. The activity of {sup 151}Sm in initial and final solutions was measured by liquid scintillation and K{sub d} ({sup 151}Sm) data were calculated. The reversibly sorbed fraction was estimated by the application of a single extraction test, with double deionised water, to soil residues coming from the previous

  15. Hydrothermal Synthesis of Dicalcium Silicate Based Cement

    Science.gov (United States)

    Dutta, N.; Chatterjee, A.

    2017-06-01

    It is imperative to develop low energy alternative binders considering the large amounts of energy consumed as well as carbon dioxide emissions involved in the manufacturing of ordinary Portland cement. This study is on the synthesis of a dicalcium silicate based binder using a low temperature hydrothermal route.The process consists of synthesizing an intermediate product consisting of a calcium silicate hydrate phase with a Ca:Si ratio of 2:1 and further thermal treatment to produce the β-Ca2SiO4 (C2S) phase.Effect of various synthesis parameters like water to solid ratio, dwell time and temperature on the formation of the desired calcium silicate hydrate phase is reported along with effect of heating conditions for formation of the β-C2S phase. Around 77.45% of β-C2S phase was synthesized by thermal treatment of the intermediate phase at 820°C.

  16. Silicate mineral dissolution during heap bioleaching.

    Science.gov (United States)

    Dopson, Mark; Halinen, Anna-Kaisa; Rahunen, Nelli; Boström, Dan; Sundkvist, Jan-Eric; Riekkola-Vanhanen, Marja; Kaksonen, Anna H; Puhakka, Jaakko A

    2008-03-01

    Silicate minerals are present in association with metal sulfides in ores and their dissolution occurs when the sulfide minerals are bioleached in heaps for metal recovery. It has previously been suggested that silicate mineral dissolution can affect mineral bioleaching by acid consumption, release of trace elements, and increasing the viscosity of the leach solution. In this study, the effect of silicates present in three separate samples in conjunction with chalcopyrite and a complex multi-metal sulfide ore on heap bioleaching was evaluated in column bioreactors. Fe(2+) oxidation was inhibited in columns containing chalcopyrite samples A and C that leached 1.79 and 1.11 mM fluoride, respectively but not in sample B that contained 0.14 mM fluoride. Microbial Fe(2+) oxidation inhibition experiments containing elevated fluoride concentrations and measurements of fluoride release from the chalcopyrite ores supported that inhibition of Fe(2+) oxidation during column leaching of two of the chalcopyrite ores was due to fluoride toxicity. Column bioleaching of the complex sulfide ore was carried out at various temperatures (7-50 degrees C) and pH values (1.5-3.0). Column leaching at pH 1.5 and 2.0 resulted in increased acid consumption rates and silicate dissolution such that it became difficult to filter the leach solutions and for the leach liquor to percolate through the column. However, column temperature (at pH 2.5) only had a minor effect on the acid consumption and silicate dissolution rates. This study demonstrates the potential negative impact of silicate mineral dissolution on heap bioleaching by microbial inhibition and liquid flow. Copyright 2007 Wiley Periodicals, Inc.

  17. Nanostructure of Calcium Silicate Hydrates in Cements

    KAUST Repository

    Skinner, L. B.

    2010-05-11

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

  18. Crystal growth of semiorganic complex- samarium chloride coordinated thiourea-L-tartaric acid and its studies on structure and optical characteristics

    Science.gov (United States)

    Slathia, Goldy; Singh, Harjinder; Ramya, E.; Rao, D. Narayana; Bamzai, K. K.

    2017-05-01

    The semi-organic complex of samarium chloride coordinated thiourea-L-tartaric acid (SCTLT) has been grown as a single crystal by slow evaporation technique at room temperature. For structural studies, the grown crystal was subjected to single crystal X-ray diffraction and Fourier transform infra-red (FTIR) spectroscopy. Low cut off wavelength and transparent characteristics were explored by UV-VIS optical characterization. Third-order nonlinear optical properties of grown crystal were investigated by Z-scan technique.

  19. Sorption of samarium in iron (II) and (III) phosphates in aqueous systems; Sorcion de samario en fosfatos de hierro (II) y (III) en sistemas acuosos

    Energy Technology Data Exchange (ETDEWEB)

    Diaz F, J.C

    2006-07-01

    The radioactive residues that are stored in the radioactive confinements its need to stay isolated of the environment while the radioactivity levels be noxious. An important mechanism by which the radioactive residues can to reach the environment, it is the migration of these through the underground water. That it makes necessary the investigation of reactive materials that interacting with those radionuclides and that its are able to remove them from the watery resources. The synthesis and characterization of materials that can be useful in Environmental Chemistry are very important because its characteristics are exposed and its behavior in chemical phenomena as the sorption watery medium is necessary to use it in the environmental protection. In this work it was carried out the sorption study of the samarium III ion in the iron (II) and (III) phosphate; obtaining the sorption isotherms in function of pH, of the phosphate mass and of the concentration of the samarium ion using UV-visible spectroscopy to determine the removal percentage. The developed experiments show that as much the ferrous phosphate as the ferric phosphate present a great affinity by the samarium III, for what it use like reactive material in contention walls can be very viable because it sorption capacity has overcome 90% to pH values similar to those of the underground and also mentioning that the form to obtain these materials is very economic and simple. (Author)

  20. Trace amounts of rare earth elements in high purity samarium oxide by sector field inductively coupled plasma mass spectrometry after separation by HPLC

    Energy Technology Data Exchange (ETDEWEB)

    Pedreira, W.R. [Instituto de Geociencias, Universidade de Brasilia (UnB), 70910-900 Brasilia, DF (Brazil) and Fundacao Jorge Duprat Figueiredo de Seguranca e Medicina do Trabalho (FUNDACENTRO), 05409-002 Sao Paulo, SP (Brazil)]. E-mail: walter.pedreira@fundacentro.gov.br; Queiroz, C.A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), 05508-900 Sao Paulo, SP (Brazil); Abrao, A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), 05508-900 Sao Paulo, SP (Brazil); Rocha, S.M. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), 05508-900 Sao Paulo, SP (Brazil); Vasconcellos, M.E. de [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), 05508-900 Sao Paulo, SP (Brazil); Boaventura, G.R. [Instituto de Geociencias, Universidade de Brasilia (UnB), 70910-900 Brasilia, DF (Brazil); Pimentel, M.M. [Instituto de Geociencias, Universidade de Brasilia (UnB), 70910-900 Brasilia, DF (Brazil)

    2006-07-20

    Today there is an increasing need for high purity rare earth compounds in various fields, the optical, the electronics, the ceramic, the nuclear and geochemistry. Samarium oxide has special uses in glass, phosphors, lasers and thermoelectric devices. Calcium chloride crystals treated with samarium have been employed in lasers, which produce light beams intense enough to burn metal. In general, the inductively coupled plasma mass spectrometry (ICP-MS) presents some advantages for trace element analysis, due to high sensitivity and resolution, when compared with other analytical techniques such as ICP optical emission spectrometry (ICP-OES). In this work, sector field inductively coupled plasma mass spectrometry was used. Sixteen elements (Sc, Y and 14 lanthanides) were determined selectively with the ICP-MS system using a concentration gradient method. The detection limits with the ICP-MS system were about 0.2 (La) pg mL{sup -1} to 8 (Gd) pg mL{sup -1}. The %R.S.D. of the methods varying between 0.9 and 1.5% for a set of five (n = 5) replicates was found for the IPEN's material and for the certificate reference sample. Determination of trace REEs in two high pure samarium oxides samples (IPEN and JMC) was performed. IPEN's material is highly pure (>99.99%) and was successfully analyzed without spectral interference (MO{sup +} and MOH{sup +})

  1. Stability constants for silicate adsorbed to ferrihydrite

    DEFF Research Database (Denmark)

    Hansen, Hans Christian Bruun; Wetche, T.P.; Raulund-Rasmussen, Karsten

    1994-01-01

    Intrinsic surface acidity constants (K(a1)intr, K(a2)intr) and surface complexation constant for adsorption of orthosilicate onto synthetic ferrihydrite (K(Si) for the complex = FeOSi(OH)3) have been determined from acid/base titrations in 0.001-0.1 m NaClO4 electrolytes and silicate adsorption e...

  2. Combustion synthesis and photoluminescence study of silicate ...

    Indian Academy of Sciences (India)

    Silicate based bioceramics are promising candidates as biomaterials for tissue engineering. The combustion synthesis method provides control on the morphology and particle size of the synthesized material. This paper discusses the combustion synthesis of akermanite (Ca2MgSi2O7 and Sr2MgSi2O7), which has been ...

  3. Suppressive effects of a polymer sodium silicate solution on ...

    African Journals Online (AJOL)

    The silicon contents in the roots of the miniature rose treated with polymer sodium silicate were significantly greater than that in plants treated with monomer sodium silicate. In conclusion, the suppressive effects of sodium silicate in the polymer form were confirmed against powdery mildew and root rot diseases of the ...

  4. The role of water in silicate oligomerization reaction

    NARCIS (Netherlands)

    Trinh, T.T.; Jansen, A.P.J.; Santen, R.A.; Meijer, E.J.

    2009-01-01

    The silicate oligomerization reaction is key to sol-gel chemistry and zeolite synthesis. Numerous experimental and theoretical studies have been devoted to investigating the physical chemistry of silicate oligomers in the prenucleation stage of siliceous zeolite formation. Most of the previous

  5. Suppressive effects of a polymer sodium silicate solution on ...

    African Journals Online (AJOL)

    Mohsen

    2015-10-21

    Oct 21, 2015 ... Sodium silicate was dissolved in water in either a monomer form or polymer form; the effects of both forms of sodium silicate aqueous solution on rose powdery mildew and root rot diseases of miniature rose were examined. Both forms of sodium silicate aqueous solution were applied to the roots of the.

  6. Silicate release from glass for pharmaceutical preparations.

    Science.gov (United States)

    Bohrer, Denise; Bortoluzzi, Fabiana; Nascimento, Paulo Cícero; Carvalho, Leandro Machado; Ramirez, Adrian Gustavo

    2008-05-01

    Glass is made of polymeric silica and other minor components, which are necessary for turning the silica into a material more easily moldable and resistant to temperature changes. Glass containers for pharmaceutical usage are classified according to their resistance to a chemical attack, a test carried out in the presence of water and heat. The test is designed to show the released alkalinity, a variable dependent on the amount of sodium oxide, one of the minor components added to the glass mass. In this work, the release of silica from glass by action of constituents from pharmaceutical formulations was investigated. The study included products used in large volumes and usually stored in glass containers. Solutions of amino acids, electrolytes, glucose, oligoelements and others such as heparin and sodium bicarbonate were individually stored in glass containers and heated at 121 degrees C for 30min, as in the water attack test. The test was also carried out only with water, where the pH varied from 2 to 12. The released silicate was measured either by photometry or atomic absorption spectrometry, depending on the nature of the sample. The results showed that silicate is released during the heating cycle even if the contact is with pure water only. The pH exerts a considerable influence on the release, being that the higher the pH, the higher the silica dissolved. An elevated pH, however, is not the only factor responsible for silica dissolution. While in the solutions of NaCl, KCl, Mg Cl2 and ZnSO4 and in most of the amino acids, the concentration of silicate was as high as in pure water (0.1-1.0mg Si/L). In the solutions of sodium acetate, bicarbonate and gluconate, its concentration was much higher, over 30mg Si/L. These results were confirmed by the analysis of commercial products, where in solutions of amino acids the level of silicate ranged from 0.14 to 0.19mg Si/L. On the other hand, calcium gluconate, sodium bicarbonate and potassium phosphate presented

  7. Effectiveness of radiation synovectomy with samarium-{sup 153} particulate hydroxyapatite in rheumatoid arthritis patients with knee synovitis: a controlled randomized double-blind trial

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Marla Francisca dos; Furtado, Rita Nely Vilar; Konai, Monique Sayuri; Natour, Jamil, E-mail: jnatour@unifesp.b [Universidade Federal de Sao Paulo (UNIFESP-EPM), Sao Paulo, SP (Brazil). Divisao de Reumatologia; Castiglioni, Mario Luiz Vieira; Marchetti, Renata Rosa [Universidade Federal de Sao Paulo (UNIFESP-EPM), Sao Paulo, SP (Brazil). Divisao de Medicina Nuclear

    2009-07-01

    Objectives: the aim of the present study was to investigate the effectiveness of Samarium{sup 153}-particulate hydroxyapatite radiation synovectomy in rheumatoid arthritis patients with chronic knee synovitis. Methods: fifty-eight rheumatoid arthritis patients (60 knees) with chronic knee synovitis participated in a controlled double-blinded trial. Patients were randomized to receive either an intra-articular injection with 40 mg triamcinolone hexacetonide alone (TH group) or 40 mg triamcinolone hexacetonide combined with 15 mCi Samarium{sup 153}-particulate hydroxyapatite (Sm/TH group). Blinded examination at baseline (T0) and at 1 (T1), 4 (T4), 12 (T12), 32 (T32), and 48 (T48) weeks post-intervention were performed on all patients and included a visual analog scale for joint pain and swelling as well as data on morning stiffness, flexion, extension, knee circumference, Likert scale of improvement, percentage of improvement, SF-36 generic quality of life questionnaire, Stanford Health Assessment Questionnaire (HAQ), Lequesne index, use of non-steroidal anti-inflammatory drugs or oral corticosteroids, events and adverse effects, calls to the physician, and hospital visits. Results: the sample was homogeneous at baseline, and there were no withdrawals. Improvement was observed in both groups in relation to T0, but no statistically significant differences between groups were observed regarding all variables at the time points studied. The Sm/TH group exhibited more adverse effects at T1 (p<0.05), but these were mild and transitory. No severe adverse effects were reported during follow-up. Conclusion: intra-articular injection of Samarium{sup 153}-particulate hydroxyapatite (15 mCi) with 40 mg of triamcinolone hexacetonide is not superior to triamcinolone hexacetonide alone for the treatment of knee synovitis in patients with rheumatoid arthritis at 1 y of follow-up. (author)

  8. The properties of samarium-doped zinc oxide/phthalocyanine structure for optoelectronics prepared by pulsed laser deposition and organic molecular evaporation

    Czech Academy of Sciences Publication Activity Database

    Novotný, Michal; Marešová, Eva; Fitl, Přemysl; Vlček, Jan; Bergmann, M.; Vondráček, Martin; Yatskiv, Roman; Bulíř, Jiří; Hubík, Pavel; Hruška, Petr; Drahokoupil, Jan; Abdellaoui, N.; Vrňata, M.; Lančok, Ján

    2016-01-01

    Roč. 122, č. 3 (2016), 1-8, č. článku 225. ISSN 0947-8396 R&D Projects: GA MŠk(CZ) LG15050; GA ČR(CZ) GAP108/11/0958; GA MŠk(CZ) LM2011029; GA ČR(CZ) GA14-10279S; GA MŠk(CZ) 7AMB14FR010 Institutional support: RVO:68378271 ; RVO:67985882 Keywords : samarium-doped zinc oxide zinc/phthalocyanine deposition * evaporation * pulsed laser deposition * thin films Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.455, year: 2016

  9. LABORATORY INVESTIGATIONS OF SILICATE MUD CONTAMINATION WITH CALCIUM

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    2004-12-01

    Full Text Available The silicate-based drilling fluid is a low solids KCl/polymer system with the addition of soluble sodium or potassium silicate to enhance inhibition and wellbore stability. Silicate-based drilling fluids exhibit remarkable shale and chalk stabilizing properties, resulting in gauge hole and the formation of firm cuttings when drilling reactive shales and soft chalks. Silicates protect shales by in-situ gellation when exposed to the neutral pore fluid and precipitation, which occurs on contact with divalent ions present at the surface of the shale. Also, silicates prevent the dispersion and washouts when drilling soft chalk by reacting with the Ca2+ ions present on chalk surfaces of cutting and wellbore to form a protective film. The silicate-based drilling fluid can be used during drilling hole section through shale interbeded anhydrite formations because of its superior shale stabilizing characteristics. However, drilling through the anhydrite can decrease the silicate concentration and change rheological and filtration fluid properties. So, the critical concentration of calcium ions should be investigated by lab tests. This paper details the mechanism of shale inhibition using silicate-based drilling fluid, and presents results of lab tests conducted to ascertain the effect of Ca2+ ions on silicate level in the fluid and the fluid properties.

  10. Activity composition relationships in silicate melts

    Energy Technology Data Exchange (ETDEWEB)

    Glazner, A.F.

    1990-01-01

    Equipment progress include furnace construction and electron microprobe installation. The following studies are underway: phase equilibria along basalt-rhyolite mixing line (olivine crystallization from natural silicic andensites, distribution of Fe and Mg between olivine and liquid, dist. of Ca and Na between plagioclase and liquid), enthalpy-composition relations in magmas (bulk heat capacity of alkali basalt), density model for magma ascent and contamination, thermobarometry in igneous systems (olivine/plagioclase phenocryst growth in Quat. basalt), high-pressure phase equilibria of alkali basalt, basalt-quartz mixing experiments, phase equilibria of East African basalts, and granitic minerals in mafic magma. (DLC)

  11. Determination of chlorine in silicate rocks

    Science.gov (United States)

    Peck, L.C.

    1959-01-01

    In a rapid accurate method for the determination of chlorine in silicate rocks, the rock powder is sintered with a sodium carbonate flux containing zinc oxide and magnesium carbonate. The sinter cake is leached with water, the resulting solution is filtered, and the filtrate is acidified with nitric acid. Chlorine is determined by titrating this solution with mercuric nitrate solution using sodium nitroprusside as the indicator. The titration is made in the dark with a beam of light shining through the solution. The end point of the titration is found by visually comparing the intensity of this beam of light with that of a similar beam of light in a reference solution.

  12. Microbial dissolution of silicate materials. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Schwartzman, D. [Howard Univ., Washington, DC (United States). Dept. of Biology

    1996-03-26

    The objective of this research was to better understand the role of selected thermophilic bacteria in the colonization and dissolution of silicate minerals, with potential applications to the HDR Project. The demonstration of enhanced dissolution from microbial effects is critically dependent on providing a mineral bait within a media deficient in the critical nutrient found in the mineral (e.g., Fe). Reproducible experimental conditions in batch experiments require agitation to expose mineral powders, as well as nearly similar initial conditions for both inoculated cultures and controls. It is difficult, but not impossible to ensure reproducible conditions with microbes favoring filamentous growth habits.

  13. Neutron Activated Samarium-153 Microparticles for Transarterial Radioembolization of Liver Tumour with Post-Procedure Imaging Capabilities

    Science.gov (United States)

    Hashikin, Nurul Ab. Aziz; Yeong, Chai-Hong; Abdullah, Basri Johan Jeet; Ng, Kwan-Hoong; Chung, Lip-Yong; Dahalan, Rehir; Perkins, Alan Christopher

    2015-01-01

    Introduction Samarium-153 (153Sm) styrene divinylbenzene microparticles were developed as a surrogate for Yttrium-90 (90Y) microspheres in liver radioembolization therapy. Unlike the pure beta emitter 90Y, 153Sm possess both therapeutic beta and diagnostic gamma radiations, making it possible for post-procedure imaging following therapy. Methods The microparticles were prepared using commercially available cation exchange resin, Amberlite IR-120 H+ (620–830 μm), which were reduced to 20–40 μm via ball mill grinding and sieve separation. The microparticles were labelled with 152Sm via ion exchange process with 152SmCl3, prior to neutron activation to produce radioactive 153Sm through 152Sm(n,γ)153Sm reaction. Therapeutic activity of 3 GBq was referred based on the recommended activity used in 90Y-microspheres therapy. The samples were irradiated in 1.494 x 1012 n.cm-2.s-1 neutron flux for 6 h to achieve the nominal activity of 3.1 GBq.g-1. Physicochemical characterisation of the microparticles, gamma spectrometry, and in vitro radiolabelling studies were carried out to study the performance and stability of the microparticles. Results Fourier Transform Infrared (FTIR) spectroscopy of the Amberlite IR-120 resins showed unaffected functional groups, following size reduction of the beads. However, as shown by the electron microscope, the microparticles were irregular in shape. The radioactivity achieved after 6 h neutron activation was 3.104 ± 0.029 GBq. The specific activity per microparticle was 53.855 ± 0.503 Bq. Gamma spectrometry and elemental analysis showed no radioactive impurities in the samples. Radiolabelling efficiencies of 153Sm-Amberlite in distilled water and blood plasma over 48 h were excellent and higher than 95%. Conclusion The laboratory work revealed that the 153Sm-Amberlite microparticles demonstrated superior characteristics for potential use in hepatic radioembolization. PMID:26382059

  14. Thermochemistry of dense hydrous magnesium silicates

    Science.gov (United States)

    Bose, Kunal; Burnley, Pamela; Navrotsky, Alexandra

    1994-01-01

    Recent experimental investigations under mantle conditions have identified a suite of dense hydrous magnesium silicate (DHMS) phases that could be conduits to transport water to at least the 660 km discontinuity via mature, relatively cold, subducting slabs. Water released from successive dehydration of these phases during subduction could be responsible for deep focus earthquakes, mantle metasomatism and a host of other physico-chemical processes central to our understanding of the earth's deep interior. In order to construct a thermodynamic data base that can delineate and predict the stability ranges for DHMS phases, reliable thermochemical and thermophysical data are required. One of the major obstacles in calorimetric studies of phases synthesized under high pressure conditions has been limitation due to the small (less than 5 mg) sample mass. Our refinement of calorimeter techniques now allow precise determination of enthalpies of solution of less than 5 mg samples of hydrous magnesium silicates. For example, high temperature solution calorimetry of natural talc (Mg(0.99) Fe(0.01)Si4O10(OH)2), periclase (MgO) and quartz (SiO2) yield enthalpies of drop solution at 1044 K to be 592.2 (2.2), 52.01 (0.12) and 45.76 (0.4) kJ/mol respectively. The corresponding enthalpy of formation from oxides at 298 K for talc is minus 5908.2 kJ/mol agreeing within 0.1 percent to literature values.

  15. Carbon Mineralization Using Phosphate and Silicate Ions

    Science.gov (United States)

    Gokturk, H.

    2013-12-01

    Carbon dioxide (CO2) reduction from combustion of fossil fuels has become an urgent concern for the society due to marked increase in weather related natural disasters and other negative consequences of global warming. CO2 is a highly stable molecule which does not readily interact with other neutral molecules. However it is more responsive to ions due to charge versus quadrupole interaction [1-2]. Ions can be created by dissolving a salt in water and then aerosolizing the solution. This approach gives CO2 molecules a chance to interact with the hydrated salt ions over the large surface area of the aerosol. Ion containing aerosols exist in nature, an example being sea spray particles generated by breaking waves. Such particles contain singly and doubly charged salt ions including Na+, Cl-, Mg++ and SO4--. Depending on the proximity of CO2 to the ion, interaction energy can be significantly higher than the thermal energy of the aerosol. For example, an interaction energy of 0.6 eV is obtained with the sulfate (SO4--) ion when CO2 is the nearest neighbor [2]. In this research interaction between CO2 and ions which carry higher charges are investigated. The molecules selected for the study are triply charged phosphate (PO4---) ions and quadruply charged silicate (SiO4----) ions. Examples of salts which contain such molecules are potassium phosphate (K3PO4) and sodium orthosilicate (Na4SiO4). The research has been carried out with first principle quantum mechanical calculations using the Density Functional Theory method with B3LYP functional and Pople type basis sets augmented with polarization and diffuse functions. Atomic models consist of the selected ions surrounded by water and CO2 molecules. Similar to the results obtained with singly and doubly charged ions [1-2], phosphate and silicate ions attract CO2 molecules. Energy of interaction between the ion and CO2 is 1.6 eV for the phosphate ion and 3.3 eV for the silicate ion. Hence one can expect that the selected

  16. Preparation and examination of properties of samarium-153-EDTMP complex; Otrzymywanie chelatu kwasu etylenodiaminotetrametylenofosfonowego (EDTMP) z samarem-153 i badanie jego wlasciwosci

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, M. [Institute of Atomic Energy, Otwock-Swierk (Poland); Garnuszek, P.; Lukasiewicz, A.; Wozniak, I.; Zulczyk, W. [Osrodek Badawczo-Rozwojowy Izotopow, Otwock-Swierk (Poland); Licinska, I. [Instytut Lekow, Warsaw (Poland)

    1995-12-31

    Preparation and properties of ethylenediaminetetramethylenephosphonic acid (EDTMP) as well as some properties of {sup 153}Sm-EDTMP chelate have been examined. The chelate formed by samarium-153 (46.3 h, {beta}{sup -}-decay) with EDTMP exhibits high bone uptake and can be used for treatment of disseminated, painful skeletal metastases. The purity and stability of solutions of {sup 153}Sm-EDTMP chelate were examined in a broad range of samarium concentration and {sup 153}Sm specific activity. The complex under study was examined by radio-TLC, -electrophoresis and radio-HPLC. The results obtained suggest the small size of molecules of {sup 153}Sm-EDTMP chelate as compared with molecules of ``free``EDTMP. The results of biodistribution of {sup 153}Sm-EDTMP determined in rats indicate the quick blood clearance, high deposition of radioactivity in bone and quick excretion of radioactivity into urine. No specific uptake of {sup 153}Sm-EDTMP in extra-skeletal organs was found. (author). 42 refs, 13 figs, 22 tabs.

  17. Petrology and Geochemistry of Calc-Silicate Schists and Calc ...

    African Journals Online (AJOL)

    Chemically the calc-silicate schists are characterized by relatively high CaO, MgO, Cr, Ni, Sr, La, Ce and Nd contents compared with the mica schist regionally associated with the marble as well as the Post-Archean Australian Shale (PAAS). Relative to the ultramafic schist the calc-silicate schists are characterized by higher ...

  18. 40 CFR 721.9513 - Modified magnesium silicate polymer (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified magnesium silicate polymer (generic). 721.9513 Section 721.9513 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.9513 Modified magnesium silicate polymer (generic). (a) Chemical...

  19. [Adsorption characteristic and form distribution of silicate in lakes sediments].

    Science.gov (United States)

    Lü, Chang-Wei; Cui, Meng; Gao, Ji-Mei; Zhang, Xi-Yan; Wan, Li-Li; He, Jiang; Meng, Ting-Ting; Bai, Fan; Yang, Xu

    2012-01-01

    Taking surface sediments from the Wuliangsuhai Lake and Daihai Lake as adsorbent, the isothermal adsorption experiments of silicate on sediments were carried out and the adsorption behavior was explained by Langmuir, Freundlich and Temkin crossover-type equations, then the form distribution characters of silicate were studied after adsorption in this work. The results showed that the adsorption behavior of silicate on the two lakes sediments can be linear fitting in the lower concentration dose (Temkin crossover-type equations can be used to explain the adsorption behavior of silicate on the two lakes sediments, and the native adsorption silicate (NAS) and equilibrium silicate concentration (ESC(0)) calculated by the three equations could be used to explain the sink and source effects of the sediments from the two lakes; the silicate form distribution in the sediments after adsorption indicated that silicate adsorbed on particles were mainly added on the form of IEF-Si, CF-Si, IMOF-Si and OSF-Si, and the IMOF-Si and OSF-Si had important potential bioavailability.

  20. Fire Resistance of Wood Impregnated with Soluble Alkaline Silicates

    OpenAIRE

    Andrea Marisa Pereyra; Carlos Alberto Giudice

    2007-01-01

    The aim of this paper is to determine the fire performance of wood panels (Araucaria angustifolia) impregnated with soluble alkaline silicates. Commercial silicates based on sodium and potassium with 2.5/1.0 and 3.0/1.0 silica/alkali molar ratios were selected; solutions and glasses ...

  1. Natural Weathering Rates of Silicate Minerals

    Science.gov (United States)

    White, A. F.

    2003-12-01

    Silicates constitute more than 90% of the rocks exposed at Earth's land surface (Garrels and Mackenzie, 1971). Most primary minerals comprising these rocks are thermodynamically unstable at surface pressure/temperature conditions and are therefore susceptible to chemical weathering. Such weathering has long been of interest in the natural sciences. Hartt (1853) correctly attributed chemical weathering to "the efficacy of water containing carbonic acid in promoting the decomposition of igneous rocks." Antecedent to the recent interest in the role of vegetation on chemical weathering, Belt (1874) observed that the most intense weathering of rocks in tropical Nicaragua was confined to forested regions. He attributed this effect to "the percolation through rocks of rain water charged with a little acid from decomposing vegetation." Chamberlin (1899) proposed that the enhanced rates of chemical weathering associated with major mountain building episodes in Earth's history resulted in a drawdown of atmospheric CO2 that led to periods of global cooling. Many of the major characteristics of chemical weathering had been described when Merrill (1906) published the groundbreaking volume Rocks, Rock Weathering, and Soils.The major advances since that time, particularly during the last several decades, have centered on understanding the fundamental chemical, hydrologic, and biologic processes that control weathering and in establishing quantitative weathering rates. This research has been driven by the importance of chemical weathering to a number environmentally and economically important issues. Undoubtedly, the most significant aspect of chemical weathering is the breakdown of rocks to form soils, a process that makes life possible on the surface of the Earth. The availability of many soil macronutrients such as magnesium, calcium, potassium, and PO4 is directly related to the rate at which primary minerals weather. Often such nutrient balances are upset by anthropogenic

  2. Kinetics of iron oxidation in silicate melts

    Energy Technology Data Exchange (ETDEWEB)

    Magnien, V.; Neuville, D.R.; Cormier, L.; Mysen, B.O.; Pinet, O.; Richet, P

    2004-07-01

    High-temperature XANES experiments at the Fe K-edge have been used to study the kinetics of iron oxidation in a supercooled melt of Fe-bearing pyroxene composition. These experiments, made just above the glass transition between 600 and 700 deg C, show that variations in relative abundances of ferric and ferrous iron can be determined in situ at such temperatures. The kinetics of iron oxidation do not vary much with temperature down to the glass transition. This suggests that rate-limiting factor in this process is not oxygen diffusion, which is coupled to relaxation of the silicate network, but diffusion of network modifying cations along with a counter flux of electrons. To give a firmer basis to redox determinations made from XANES spectroscopy, the redox state of a series of a samples was first determined from wet chemical, Moessbauer spectroscopy and electron microprobe analyses. (authors)

  3. Selective silicate-directed motility in diatoms

    DEFF Research Database (Denmark)

    Bondoc, Karen Grace V.; Heuschele, Jan; Gillard, Jeroen

    2016-01-01

    Diatoms are highly abundant unicellular algae that often dominate pelagic as well as benthic primary production in the oceans and inland waters. Being strictly dependent on silica to build their biomineralized cell walls, marine diatoms precipitate 240 × 10(12) mol Si per year, which makes them...... the major sink in the global Si cycle. Dissolved silicic acid (dSi) availability frequently limits diatom productivity and influences species composition of communities. We show that benthic diatoms selectively perceive and behaviourally react to gradients of dSi. Cell speed increases under d......Si-limited conditions in a chemokinetic response and, if gradients of this resource are present, increased directionality of cell movement promotes chemotaxis. The ability to exploit local and short-lived dSi hotspots using a specific search behaviour likely contributes to micro-scale patch dynamics in biofilm...

  4. Thermal Ablation Modeling for Silicate Materials

    Science.gov (United States)

    Chen, Yih-Kanq

    2016-01-01

    A general thermal ablation model for silicates is proposed. The model includes the mass losses through the balance between evaporation and condensation, and through the moving molten layer driven by surface shear force and pressure gradient. This model can be applied in the ablation simulation of the meteoroid and the glassy ablator for spacecraft Thermal Protection Systems. Time-dependent axisymmetric computations are performed by coupling the fluid dynamics code, Data-Parallel Line Relaxation program, with the material response code, Two-dimensional Implicit Thermal Ablation simulation program, to predict the mass lost rates and shape change. The predicted mass loss rates will be compared with available data for model validation, and parametric studies will also be performed for meteoroid earth entry conditions.

  5. Lithium alumino-silicate ion source development

    Science.gov (United States)

    Roy, Prabir Kumar; Seidl, Peter A.; Kwan, Joe W.; Greenway, Wayne G.; Waldron, William L.; Wu, James K.; Mazaheri, Kavous

    2009-11-01

    We report experimental progress on Li+ source development in preparation for warm dense matter heating experiments. To uniformly heat targets to electron-volt temperatures for the study of warm dense matter, we are pursuing the use of a low (E spodumene and β-eucryptite, each of area 0.31 cm2, have been fabricated for ion emission measurements. These surface ionization sources are heated to 1200 to 1300 C where they preferentially emit singly ionized alkali ions. Tight process controls were necessary in preparing and sintering the alumino-silicate to the porous tungsten substrate to produce an emitter that gives uniform ion emission, sufficient current density and low beam emittance. Current density limit of the two kinds have been measured, and ion species identification of possible contaminants has been verified with a Wien (E x B) filter.

  6. The Level of Europium-154 Contaminating Samarium-153-EDTMP Activates the Radiation Alarm System at the US Homeland Security Checkpoints

    Directory of Open Access Journals (Sweden)

    Mohammed Najeeb Al Hallak

    2009-08-01

    Full Text Available 153Sm-EDTMP is a radiopharmaceutical composed of EDTMP (ethylenediamine-tetramethylenephosphonate and Samarium-153 [1]. 153Sm-EDTMP has an affinity for skeletal tissue and concentrates in areas with increased bone turnover; thus, it is successfully used in relieving pain related to diffuse bone metastases [1]. The manufacturing process of 153Sm-EDTMP leads to contamination with 154Eu (Europium-154 [2]. A previous study only alluded to the retention of 154Eu in the bones after receiving treatment with 153Sm-EDTMP [2]. Activation of the alarm at security checkpoints after 153Sm-EDTMP therapy has not been previously reported. Two out of 15 patients who received 153Sm-EDTMP at Roger Maris Cancer Center (Fargo, N. Dak., USA activated the radiation activity sensors while passing through checkpoints; one at a US airport and the other while crossing theAmerican-Canadian border. We assume that the 154Eu which remained in the patients’ bones activated the sensors. Methods: In order to investigate this hypothesis, we obtained the consent from 3 of our 15 patients who received 153Sm-EDTMP within the previous 4 months to 2 years, including the patient who had activated the radiation alarm at the airport. The patients were scanned with a handheld detector and a gamma camera for energies from 511 keV to 1.3 MeV. Results: All three patients exhibited identical spectral images, and further analysis showed that the observed spectra are the result of 154Eu emissions. Conclusion: Depending on the detection thresholds and windows used by local and federal authorities, the remaining activity of 154Eu retained in patients who received 153Sm-EDTMP could be sufficient enough to increase the count rates above background levels and activate the sensors. At Roger Maris Cancer Center, patients are now informed of the potential consequences of 153Sm-EDTMP therapy prior to initiating treatment. In addition, patients treated with 153Sm-EDTMP at Roger Maris Cancer Center

  7. The Level of Europium-154 Contaminating Samarium-153-EDTMP Activates the Radiation Alarm System at the US Homeland Security Checkpoints.

    Science.gov (United States)

    Najeeb Al Hallak, Mohammed; McCurdy, Matt; Zouain, Nicolas; Hayes, Justin

    2009-08-28

    (153)Sm-EDTMP is a radiopharmaceutical composed of EDTMP (ethylenediamine-tetramethylenephosphonate) and Samarium-153 [1]. (153)Sm-EDTMP has an affinity for skeletal tissue and concentrates in areas with increased bone turnover; thus, it is successfully used in relieving pain related to diffuse bone metastases [1]. The manufacturing process of (153)Sm-EDTMP leads to contamination with (154)Eu (Europium-154) [2]. A previous study only alluded to the retention of (154)Eu in the bones after receiving treatment with (153)Sm-EDTMP [2]. Activation of the alarm at security checkpoints after (153)Sm-EDTMP therapy has not been previously reported. Two out of 15 patients who received (153)Sm-EDTMP at Roger Maris Cancer Center (Fargo, N. Dak., USA) activated the radiation activity sensors while passing through checkpoints; one at a US airport and the other while crossing the American-Canadian border. We assume that the (154)Eu which remained in the patients' bones activated the sensors. METHODS: In order to investigate this hypothesis, we obtained the consent from 3 of our 15 patients who received (153)Sm-EDTMP within the previous 4 months to 2 years, including the patient who had activated the radiation alarm at the airport. The patients were scanned with a handheld detector and a gamma camera for energies from 511 keV to 1.3 MeV. RESULTS: All three patients exhibited identical spectral images, and further analysis showed that the observed spectra are the result of (154)Eu emissions. CONCLUSION: Depending on the detection thresholds and windows used by local and federal authorities, the remaining activity of (154)Eu retained in patients who received (153)Sm-EDTMP could be sufficient enough to increase the count rates above background levels and activate the sensors. At Roger Maris Cancer Center, patients are now informed of the potential consequences of (153)Sm-EDTMP therapy prior to initiating treatment. In addition, patients treated with (153)Sm-EDTMP at Roger Maris Cancer

  8. Lattice thermal conductivity of silicate glasses at high pressures

    Science.gov (United States)

    Chang, Y. Y.; Hsieh, W. P.

    2016-12-01

    Knowledge of the thermodynamic and transport properties of magma holds the key to understanding the thermal evolution and chemical differentiation of Earth. The discovery of the remnant of a deep magma ocean above the core mantle boundary (CMB) from seismic observations suggest that the CMB heat flux would strongly depend on the thermal conductivity, including lattice (klat) and radiative (krad) components, of dense silicate melts and major constituent minerals around the region. Recent measurements on the krad of dense silicate glasses and lower-mantle minerals show that krad of dense silicate glasses could be significantly smaller than krad of the surrounding solid mantle phases, and therefore the dense silicate melts would act as a thermal insulator in deep lower mantle. This conclusion, however, remains uncertain due to the lack of direct measurements on the lattice thermal conductivity of silicate melts under relevant pressure-temperature conditions. Besides the CMB, magmas exist in different circumstances beneath the surface of the Earth. Chemical compositions of silicate melts vary with geological and geodynamic settings of the melts and have strong influences on their thermal properties. In order to have a better view of heat transport within the Earth, it is important to study compositional and pressure dependences of thermal properties of silicate melts. Here we report experimental results on lattice thermal conductivities of silicate glasses with basaltic and rhyolitic compositions up to Earth's lower mantle pressures using time-domain thermoreflectance coupled with diamond-anvil cell techniques. This study not only provides new data for the thermal conductivity of silicate melts in the Earth's deep interior, but is crucial for further understanding of the evolution of Earth's complex internal structure.

  9. Viscosity of Heterogeneous Silicate Melts: A Non-Newtonian Model

    Science.gov (United States)

    Liu, Zhuangzhuang; Blanpain, Bart; Guo, Muxing

    2017-12-01

    The recently published viscosity data of heterogeneous silicate melts with well-documented structure and experimental conditions are critically re-analyzed and tabulated. By using these data, a non-Newtonian viscosity model incorporating solid fraction, solid shape, and shear rate is proposed on the basis of the power-law equation. This model allows calculating the viscosity of the heterogeneous silicate melts with solid fraction up to 34 vol pct. The error between the calculated and measured data is evaluated to be 32 pct, which is acceptable considering the large error in viscosity measurement of the completely liquid silicate melt.

  10. Fire Resistance of Wood Impregnated with Soluble Alkaline Silicates

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Giudice

    2007-01-01

    Full Text Available The aim of this paper is to determine the fire performance of wood panels (Araucaria angustifolia impregnated with soluble alkaline silicates. Commercial silicates based on sodium and potassium with 2.5/1.0 and 3.0/1.0 silica/alkali molar ratios were selected; solutions and glasses were previously characterized. Experimental panels were tested in a limiting oxygen chamber and in a two-foot tunnel. Results displayed a high fire-retardant efficiency using some soluble silicates.

  11. Formation of a new adduct based on fullerene tris-malonate samarium salt C60-[C60(=C(COO)2)3]Sm2

    Science.gov (United States)

    Petrov, A. A.; Keskinov, V. A.; Semenov, K. N.; Charykov, N. A.; Letenko, D. G.; Nikitin, V. A.

    2017-03-01

    Gram quantities of a new adduct based on light fullerene tris-malonate samarium salt C60 [C60(=C(COO)2)3]Sm2 are obtained via the reaction of ion exchange. The obtained adduct is studied by means of electron and infrared spectroscopy, X-ray and elemental analysis, electron microscopy, and thermogravimetry. The polythermal solubility of [C60(=C(COO)2)3]Sm2 in water is determined in ampoules via saturation within 20-70°C. The composition of crystalline hydrate [C60(=C(COO)2)3]Sm2 · 36H2O, which exists in equilibrium with the saturated solution, is estimated.

  12. Biodistribution of samarium-153-EDTMP in rats treated with docetaxel Biodistribuição de EDTMP-153-samário em ratos tratados com docetaxel

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    Arthur Villarim Neto

    2009-02-01

    Full Text Available PURPOSE: Many patients with metastatic bone disease have to use radiopharmaceuticals associated with chemotherapy to relieve bone pain. The aim of this study was to assess the influence of docetaxel on the biodistribution of samarium-153-EDTMP in bones and other organs of rats. METHODS: Wistar male rats were randomly allocated into 2 groups of 6 rats each. The DS (docetaxel/samarium group received docetaxel (15 mg/kg intraperitoneally in two cycles 11 days apart. The S (samarium/control group rats were not treated with docetaxel. Nine days after chemotherapy, all the rats were injected with 0.1ml of samarium-153-EDTMP via orbital plexus (25µCi. After 2 hours, the animals were killed and samples of the brain, thyroid, lung, heart, stomach, colon, liver, kidney and both femurs were removed. The percentage radioactivity of each sample (% ATI/g was determined in an automatic gamma-counter (Wizard-1470, Perkin-Elmer, Finland. RESULTS: On the 9th day after the administration of the 2nd chemotherapy cycle, the rats had a significant weight loss (314.50±22.09g compared (pOBJETIVO: Muitos pacientes com metástases ósseas são tratados com radiofármacos associados com quimioterapia para alívio da dor óssea. O objetivo do trabalho foi estudar a influência do docetaxel na biodistribuição do EDTMP-153-samário nos ossos e outros órgãos de ratos. MÉTODOS: Ratos Wistar foram aleatoriamente alocados em 2 grupos de 6 animais cada. O grupo DS (docetaxel/samário recebeu docetaxel (15 mg/kg intraperitoneal em dois ciclos com 11 dias de intervalo. Os ratos do grupo S (samário/controle não foram tratados com docetaxel. Nove dias após a quimioterapia, todos os animais receberam 0,1ml de EDTMP-153-samário via plexo orbital (25µCi. Após 2 horas, os animais foram mortos e feitas biópsias de cérebro, tireóide, pulmão, coração, estômago, cólon, fígado, rim e fêmures. O percentual de radioatividade por grama (%ATI/g de tecido de cada bi

  13. Conversion of rice hull ash into soluble sodium silicate

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    Edson Luiz Foletto

    2006-09-01

    Full Text Available Sodium silicate is used as raw material for several purposes: silica gel production, preparation of catalysts, inks, load for medicines, concrete hardening accelerator, component of detergents and soaps, refractory constituent and deflocculant in clay slurries. In this work sodium silicate was produced by reacting rice hull ash (RHA and aqueous sodium hydroxide, in open and closed reaction systems. The studied process variables were time, temperature of reaction and composition of the reaction mixture (expressed in terms of molar ratios NaOH/SiO2 and H2O/SiO2. About 90% silica conversion contained in the RHA into sodium silicate was achieved in closed system at 200 °C. The results showed that sodium silicate production from RHA can generate aggregate value to this residue.

  14. Study of thermal effects of silicate-containing hydroxyapatites

    Science.gov (United States)

    Golovanova, O. A.; Zaits, A. V.; Berdinskaya, N. V.; Mylnikova, T. S.

    2016-02-01

    The possibility of modifications of hydroxyapatite silicate ions, from the extracellular fluid prototype solution under near-physiological conditions has been studied. Formation of silicon-structured hydroxyapatite with different extent of substitution of phosphate groups in the silicate group has been established through chemical and X-ray diffraction analyses, FTIR spectroscopy and optical microscopy. The results obtained are in agreement and suggest the possibility of substitution of phosphate groups for silicate groups in the hydroxyapatite structure when introducing different sources of silica, tetraethoxysilane and sodium silicate, in the reaction mixture. Growth in the amount of silicon in Si-HA results in the increase in the thermal stability of the samples. The greatest mass loss occurs at temperatures in the range of 25-400 0C that is caused by the removal of the crystallization and adsorption water and volatile impurities. It is shown that the modified apatites are of imperfect structure and crystallize in a nanocrystalline state.

  15. Silicate Urolithiasis during Long-Term Treatment with Zonisamide

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    Satoru Taguchi

    2013-01-01

    Full Text Available Silicate urinary calculi are rare in humans, with an incidence of 0.2% of all urinary calculi. Most cases were related to excess ingestion of silicate, typically by taking magnesium trisilicate as an antacid for peptic ulcers over a long period of time; however, there also existed unrelated cases, whose mechanism of development remains unclear. On the other hand, zonisamide, a newer antiepileptic drug, is one of the important causing agents of iatrogenic urinary stones in patients with epilepsy. The supposed mechanism is that zonisamide induces urine alkalinization and then promotes crystallization of urine components such as calcium phosphate by inhibition of carbonate dehydratase in renal tubular epithelial cells. Here, we report a case of silicate urolithiasis during long-term treatment with zonisamide without magnesium trisilicate intake and discuss the etiology of the disease by examining the silicate concentration in his urine.

  16. Tris (catecholato) silicates of nickel: Synthesis, characterization and ...

    Indian Academy of Sciences (India)

    catecholato)silicates of nickel: Synthesis, characterization and first observation of inter-ion ligand transfer. J Vijeyakumar Kingston G S M Sundaram M N Sudheendra Rao. Volume 112 Issue 3 June 2000 pp 402-402 ...

  17. Marrow irradiation with high-dose 153Samarium-EDTMP followed by chemotherapy and hematopoietic stem cell infusion for acute myelogenous leukemia.

    Science.gov (United States)

    Rodriguez, Vilmarie; Anderson, Peter M; Litzow, Mark R; Erlandson, Linda; Trotz, Barbara A; Arndt, Carola A S; Khan, Shakila P; Wiseman, Gregory A

    2006-08-01

    In four patients, aged 15 - 20 years, with high-risk acute myeloid leukemia (AML), high-dose samarium 153-labelled ethylenediaminetetramethylenephosphonate (153Sm-EDTMP) was used for targeted marrow irradiation before preparative chemotherapy conditioning regimens and allogeneic (three patients) or autologous (one patient) hematopoietic stem cell transplantation. The dose of 153Sm-EDTMP was 703 MBq/kg (n = 1) or 1110 MBq/kg (n = 3). No side-effects occurred during the 30-min infusion of 153Sm-EDTMP. Samarium - melphalan regimens were given to three patients; one had 153Sm-EDTMP - busulfan + cyclophosphamide. Total body radioactivity was below the 133 MBq safe limit before infusion of stem cells (day 14 after 153Sm-EDTMP). No hemorrhagic cystitis, nephrotoxicity or serious infections occurred. Leukocyte engraftment (white blood cell count >0.5 x 10(9)/l) occurred between 12 and 23 days after stem cell infusion (mean of 17 days). Complete cytogenetic and morphologic remission of AML was evident on follow-up marrow aspirate and biopsy specimens from all patients. In two of the four study patients, the disease remains in complete remission and the patients have an excellent quality of life (Eastern Cooperative Oncology Group performance status 0; no medications) and no organ toxicity more than 2 years and more than 4 years, respectively, after their blood and bone marrow transplantations. Thus, in adolescents and adults, 153Sm-EDTMP may provide a relatively simple and effective means for using irradiation to eliminate AML within the marrow.

  18. Conversion of rice hull ash into soluble sodium silicate

    OpenAIRE

    Edson Luiz Foletto; Ederson Gratieri; Leonardo Hadlich de Oliveira; Sérgio Luiz Jahn

    2006-01-01

    Sodium silicate is used as raw material for several purposes: silica gel production, preparation of catalysts, inks, load for medicines, concrete hardening accelerator, component of detergents and soaps, refractory constituent and deflocculant in clay slurries. In this work sodium silicate was produced by reacting rice hull ash (RHA) and aqueous sodium hydroxide, in open and closed reaction systems. The studied process variables were time, temperature of reaction and composition of the reacti...

  19. Comparison of silicon nanoparticles and silicate treatments in fenugreek.

    Science.gov (United States)

    Nazaralian, Sanam; Majd, Ahmad; Irian, Saeed; Najafi, Farzaneh; Ghahremaninejad, Farrokh; Landberg, Tommy; Greger, Maria

    2017-06-01

    Silicon (Si) fertilization improves crop cultivation and is commonly added in the form of soluble silicates. However, most natural plant-available Si originates from plant formed amorphous SiO2 particles, phytoliths, similar to SiO2-nanoparticles (SiNP). In this work we, therefore, compared the effect by sodium silicate and that of SiNP on Si accumulation, activity of antioxidative stress enzymes catalase, peroxidase, superoxide dismutase, lignification of xylem cell walls and activity of phenylalanine ammonia-lyase (PAL) as well as expression of genes for the putative silicon transporter (PST), defensive (Tfgd 1) and phosphoenolpyruvate carboxykinase (PEPCK) and protein in fenugreek (Trigonella foenum-graecum L.) grown in hydroponics. The results showed that Si was taken up from both silicate and SiNP treatments and increasing sodium silicate addition increased the translocation of Si to the shoot, while this was not shown with increasing SiNP addition. The silicon transporter PST was upregulated at a greater level when sodium silicate was added compared with SiNP addition. There were no differences in effects between sodium silicate and SiNP treatments on the other parameters measured. Both treatments increased the uptake and accumulation of Si, xylem cell wall lignification, cell wall thickness, PAL activity and protein concentration in seedlings, while there was no effect on antioxidative enzyme activity. Tfgd 1 expression was strongly downregulated in leaves at Si addition. The similarity in effects by silicate and SiNP would be due to that SiNP releases silicate, which may be taken up, shown by a decrease in SiNP particle size with time in the medium. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  20. Effects of silicate application on soil fertility and wheat yield

    Directory of Open Access Journals (Sweden)

    Marcos Vinícius Mansano Sarto

    2015-12-01

    Full Text Available An improvement in soil chemical properties and crop development with silicate application has been confirmed in several plant species. The effects of silicate application on soil chemical properties and wheat growth were investigated in the present study. The experiment was carried out in 8-L plastic pots in a greenhouse. Treatments were arranged in a randomized block design in a 3 × 5 factorial: three soils [Rhodic Acrudox (Ox1, Rhodic Hapludox (Ox2 and Arenic Hapludult (Ult] and five silicate rates (0, 1, 2, 4 and 6 Mg ha–1 of calcium/magnesium silicate, with four replications. The plant length, number of spikes per pot, shoot dry matter and grain yield, were measured after 115 days of wheat (Triticum aestivum L. growth. Changes in the soil chemical properties (pH, H+ + Al3+, Al3+, P, K, Ca, Mg, Si, Cu, Zn, Fe and Mn were analyzed after wheat harvest. Application of calcium/magnesium silicate reduces the potential acidity (H+ + Al3+ and Al3+ phytotoxic; and increases the soil pH, available Ca, Mg and Si, cation exchange capacity (CEC and soil base saturation. Silicate application did not affect the available P, exchangeable K and availability of micronutrients (Cu, Zn, Fe and Mn in the three soils. The application of calcium/magnesium silicate in an acid clayey Rhodic Hapludox improves the development and yield of wheat; however, the silicate application in soil with pH higher to 5.3 and high Si availability does not affect the agronomic characteristics and grain yield of wheat. 

  1. History of Nebular Processing Traced by Silicate Stardust in IDPS

    Science.gov (United States)

    Messenger, Scott R.; Keller, L. P.; Nakamura-Messenger, K.

    2010-01-01

    Chondritic porous interplanetary dust particles (CP-IDPs) may be the best preserved remnants of primordial solar system materials, in part because they were not affected by parent body hydrothermal alteration. Their primitive characteristics include fine grained, unequilibrated, anhydrous mineralogy, enrichment in volatile elements, and abundant molecular cloud material and silicate stardust. However, while the majority of CP-IDP materials likely derived from the Solar System, their formation processes and provenance are poorly constrained. Stardust abundances provide a relative measure of the extent of processing that the Solar System starting materials has undergone in primitive materials. For example, among primitive meteorites silicate stardust abundances vary by over two orders of magnitude (less than 10-200 ppm). This range of abundances is ascribed to varying extents of aqueous processing in the meteorite parent bodies. The higher average silicate stardust abundances among CP-IDPs (greater than 375 ppm) are thus attributable to the lack of aqueous processing of these materials. Yet, silicate stardust abundances in IDPs also vary considerably. While the silicate stardust abundance in IDPs having anomalous N isotopic compositions was reported to be 375 ppm, the abundance in IDPs lacking N anomalies is less than 10 ppm. Furthermore, these values are significantly eclipsed among some IDPs with abundances ranging from 2,000 ppm to 10,000 ppm. Given that CP-IDPs have not been significantly affected by parent body processes, the difference in silicate stardust abundances among these IDPs must reflect varying extents of nebular processing. Here we present recent results of a systematic coordinated mineralogical/isotopic study of large cluster IDPs aimed at (1) characterizing the mineralogy of presolar silicates and (2) delineating the mineralogical and petrographic characteristics of IDPs with differing silicate stardust abundances. One of the goals of this study is

  2. Silicates in orthopedics and bone tissue engineering materials.

    Science.gov (United States)

    Zhou, Xianfeng; Zhang, Nianli; Mankoci, Steven; Sahai, Nita

    2017-07-01

    Following the success of silicate-based glasses as bioactive materials, silicates are believed to play important roles in promoting bone formation and have therefore been considered to provide a hydroxyapatite (HAP) surface layer capable of binding to bone as well as potentially being a pro-osteoinductive factor. Natural silicate minerals and silicate-substituted HAPs are also being actively investigated as orthopaedic bone and dental biomaterials for application in tissue engineering. However, the mechanisms for the proposed roles of silicate in these materials have not been fully understood and are controversial. Here, we review the potential roles of silicate for bone tissue engineering applications and recent breakthroughs in identifying the cellular-level molecular mechanisms for the osteoinductivity of silica. The goal of this article is to inspire new ideas for the rational design of third-generation cell-and gene-affecting biomaterials. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2090-2102, 2017. © 2017 Wiley Periodicals, Inc.

  3. On the Mg/Fe Ratio in Silicate Minerals in the Circumstellar Environments I. The Mg/Fe Ratio in Silicate Mineral Constituents of the Kaba Meteorite

    Science.gov (United States)

    Futó, P.

    2017-11-01

    The moderately high ratio of Mg in the silicates of the solar environment indicates that Mg-rich silicates are likely to be frequent in the interstellar medium and the circumstellar environments in case of chondritic-like composition.

  4. Potassium silicate and calcium silicate on the resistance of soybean to Phakopsora pachyrhizi infection

    Directory of Open Access Journals (Sweden)

    Maria Fernanda Cruz

    2013-01-01

    Full Text Available The control of Asian Soybean Rust (ASR, caused by Phakopsora pachyrhizi, has been difficult due to the aggressiveness of the pathogen and the lack of resistant cultivars. The objective of this study was to evaluate the effects of spray of potassium silicate (PS and soil amendment with calcium silicate (CS on soybean resistance to ASR. The PS solution was sprayed to leaves 24 hours prior to fungal inoculation while CS was amended to the soil at thirty-five days before sowing. The infection process of P. pachyrhizi was investigated by scanning electron microscopy. The uredia on leaves of plants sprayed with PS were smaller and more compact than those observed on the leaves of plants grown in soil amended with CS or in soil non-amended with CS (control treatment. On leaves of plants from the control treatment, uredia produced many urediniospores at 9 days after inoculation, and the ASR severity was 15, 8 and 9%, respectively, for plants from control, PS and CS treatments. In conclusion, the spray of PS contributed to reduce the number of uredia per cm² of leaf area and both PS spray and CS resulted in lower ASR symptoms.

  5. Viscoelastic properties of polymer based layered-silicate nanocomposites

    Science.gov (United States)

    Ren, Jiaxiang

    Polymer based layered-silicate nanocomposites offer the potential for dramatically improved mechanical, thermal, and barrier properties while keeping the material density low. Understanding the linear and non-linear viscoelastic response for such materials is crucial because of the ability of such measurements to elucidate the mesoscale dispersion of layered-silicates and changes in such dispersion to applied flows as would be encountered in processing of these materials. A series of intercalated polystyrene (and derivatives of polystyrene) layered-silicate nanocomposites are studied to demonstrate the influence of mesoscale dispersion and organic---inorganic interactions on the linear and non-linear viscoelastic properties. A layered-silicate network structure is exhibited for the nanocomposites with strong polymer-silicate interaction such as montmorillonite (2C18M) and fluorohectorite (C18F) and the percolation threshold is ˜ 6 wt % for the 2C18M based hybrids. However, the nanocomposites based on hectorite (2C18H) with weak polymer-silicate interaction exhibit liquid-like terminal zone behavior. Furthermore, the enhanced terminal zone elastic modulus and viscosity of high brominated polystyrene and high molecular weight polystyrene based 2C18M nanocomposites suggest an improved delamination and dispersion of layered-silicates in the polymer matrix. The non-linear viscoelastic properties, specifically, the non-linear stress relaxation behavior and the applicability of time---strain separability, the effect of increasing strain amplitude on the oscillatory shear flow properties, and the shear rate dependence of the steady shear flow properties are examined. The silicate sheets (or collections of sheets) exhibit the ability to be oriented by the applied flow. Experimentally, the empirical Cox - Merz rule is demonstrated to be inapplicable for the hybrids. Furthermore, the K-BKZ constitutive model is used to model the steady shear properties. While being able to

  6. COMPARISON OF SOL-GEL SILICATE COATINGS ON Ti SUBSTRATE

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    DIANA HORKAVCOVÁ

    2012-12-01

    Full Text Available The objective of the submitted work was to prepare and to characterize two types of silicate coatings prepared by the sol-gel method using the dip-coating technique on a titanium substrate. Efforts have been made to use mechanical properties of bio-inert titanium and bioactive properties of a silicate layer enriched with an admixture of compounds identified below. The first group consisted of silicate coatings containing silver, brushite and monetite. The other group of silicate coatings contained calcium nitrate and triethyl phosphate. Mechanically and chemically treated titanium substrates were dipped into sols and dried and fired. Silicate coatings from the first group were also chemically treated in 10 mol.l-1 solution of sodium hydroxide. All coatings were measured to determine their adhesive and bioactive properties and furthermore the antibacterial properties were tested in the case of first group. Surfaces of the coated substrates were investigated after the firing and after the individual tests with optical and electron microscopy and X-ray microdiffraction. A tape test demonstrated excellent adhesive property of all coatings to the substrate, classified with degree 5. A static in vitro test demonstrated bioactivity of nearly all the coatings. The basic silicate coating from the first group and one type of coating from the second group were identified as inert. Antibacterial properties of silicate coatings containing silver showed to be different when tested against Escherichia coli bacteria. A complete inhibition of the growth of bacteria under our experimental conditions was observed for the coating containing silver and monetite and a partial inhibition of the growth of bacteria for coatings containing silver and silver in combination with brushite.

  7. Synthesis of samarium complexes with the derivative binder of Schiff Quinolinic base. Characterization and photophysical study; Sintesis de complejos de samario con el ligante derivado de base de Schiff Quinolinica. Caracterizacion y estudio fotofisico

    Energy Technology Data Exchange (ETDEWEB)

    Lucas H, J.

    2016-07-01

    In this work we determined the metal: binder stoichiometry of the species formed during the UV/Vis spectrophotometric titration of the derivative binder of Schiff quinolinic base, L1 with the samarium nitrate pentahydrate in methanol. Statistical analysis of the data allowed proposing the metal: binder stoichiometry for the synthesis of the complexes which was one mole of samarium salt by 2.5 moles of binder and thus favor the formation of complexes with 1M: 1L and 1M: 2L stoichiometries. They were synthesized in aqueous-organic medium (water-ethanol), isolated and purified two complexes with stoichiometry 1 Sm: 1 L1, complex 1 and 1 Sm: 2 L1, complex 2. The overall yield of the reaction was 76%. The characterization of the formed complexes was performed by visible ultraviolet spectrometry (UV/Vis), nuclear magnetic resonance, X-ray photoelectron spectroscopy (XP S), thermal gravimetric analysis with differential scanning calorimetry (TGA/DSC), and radial distribution function. These complexes were studied by fluorescence and emission phosphorescence at variable temperature. Spectroscopic techniques used in both solution and solid demonstrated the formation and stability of these complexes. In addition XP S indicated that in both complexes the samarium retains its oxidation state 3+. Luminescence studies indicated that there is intra-binding charge transfer which decreases the transfer of light energy from the binder to the samarium. Based on the experimental results, L1 binder molecules and complexes 1 and 2 were modeled that demonstrated the proposed Nc for each complex, as well as allowed to visualize the structural arrangement of the molecules, complexes and binder. (Author)

  8. SON68 glass dissolution driven by magnesium silicate precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Fleury, Benjamin, E-mail: benjamin.fleury@cea.fr [CEA Marcoule, DEN/DTCD/SECM/LCLT, BP17171, 30207 Bagnols-sur-cèze (France); Godon, Nicole [CEA Marcoule, DEN/DTCD/SECM/LCLT, BP17171, 30207 Bagnols-sur-cèze (France); Ayral, André [IEM, University Montpellier 2, CC 047, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France); Gin, Stéphane [CEA Marcoule, DEN/DTCD/SECM/LCLT, BP17171, 30207 Bagnols-sur-cèze (France)

    2013-11-15

    Experimental results are reported on the effect of magnesium silicate precipitation on the mechanisms and rate of borosilicate glass dissolution. Leaching experiments with SON68 glass, a borosilicate containing no Mg, were carried out in initially deionized water at 50 °C with a glass-surface-area-to-solution-volume ratio of 20,000 m{sup −1}. After 29 days of alteration the experimental conditions were modified by the addition of Mg to trigger the precipitation of Mg-silicate. Additional experiments were conducted to investigate the importance of other parameters such as pH or dissolved silica on the mechanisms of precipitation of Mg-silicates and their consequences on the glass dissolution rate. Mg-silicates precipitate immediately after Mg is added. The amount of altered glass increases with the quantity of added Mg, and is smaller when silicon is added in solution. A time lag is observed between the addition of magnesium and the resumption of glass alteration because silicon is first provided by partial dissolution of the previously formed alteration gel. It is shown that nucleation does not limit Mg-silicate precipitation. A pH above 8 is necessary for the phase to precipitate under the investigated experimental conditions. On the other hand the glass alteration kinetics limits the precipitation if the magnesium is supplied in solution at a non-limiting rate.

  9. Heterogeneous nucleation of protein crystals on fluorinated layered silicate.

    Directory of Open Access Journals (Sweden)

    Keita Ino

    Full Text Available Here, we describe an improved system for protein crystallization based on heterogeneous nucleation using fluorinated layered silicate. In addition, we also investigated the mechanism of nucleation on the silicate surface. Crystallization of lysozyme using silicates with different chemical compositions indicated that fluorosilicates promoted nucleation whereas the silicates without fluorine did not. The use of synthesized saponites for lysozyme crystallization confirmed that the substitution of hydroxyl groups contained in the lamellae structure for fluorine atoms is responsible for the nucleation-inducing property of the nucleant. Crystallization of twelve proteins with a wide range of pI values revealed that the nucleation promoting effect of the saponites tended to increase with increased substitution rate. Furthermore, the saponite with the highest fluorine content promoted nucleation in all the test proteins regardless of their overall net charge. Adsorption experiments of proteins on the saponites confirmed that the density of adsorbed molecules increased according to the substitution rate, thereby explaining the heterogeneous nucleation on the silicate surface.

  10. Silicate fertilizer and irrigation depth in corn production

    Directory of Open Access Journals (Sweden)

    Edvaldo Eloy Dantas Júnior

    2013-08-01

    Full Text Available Calcium-magnesium silicates improve the soil physicochemical properties and provide benefits to plant nutrition, since they are sources of silica, calcium and magnesium. The objective of this study was to evaluate the grain yield of irrigated corn fertilized with calcium-magnesium silicate. The experiment was carried out in a greenhouse in Campina Grande - PB, Brazil, using plastic pots containing 80 kg of soil. The treatments consisted of the combination of four irrigation depths, related to water replacement of 50, 75, 100 and 125% of the crop evapotranspiration, with fertilizer levels of 0, 82, 164 and 246 g of calcium-magnesium silicate, with three replications. The experimental design was in randomized blocks, with the irrigation depths distributed in bands while the silicon levels constituted the subplots. Corn yield was influenced by calcium-magnesium silicate and by irrigation depth, obtaining the greatest grain yield with the dose of 164 g pot-1 irrigated at the highest water level. The water-use efficiency of in corn production tended to decrease when the irrigation depth was increased. The best water-use efficiency was observed when the irrigation level was between 87 and 174 mm, and the dose of silicate was 164 g pot-1.

  11. Steam based conversion coating on AA6060 alloy: Effect of sodium silicate chemistry and corrosion performance

    Science.gov (United States)

    Din, Rameez Ud; Bordo, Kirill; Tabrizian, Naja; Jellesen, Morten Stendahl; Ambat, Rajan

    2017-11-01

    Surface treatment of aluminium alloy AA6060 using an industrially applicable pilot steam jet system with and without silicate chemistry has been investigated. Treatment using steam alone and steam with silicate, resulted in an oxide layer formation with thickness ∼425 nm and ∼160 nm, respectively. Moreover, the use of sodium silicate resulted in the formation of distinct microstructure and incorporation of silicate into the oxide film. These oxide films reduced the anodic activity 4 times, while the corrosion protection by silicate containing oxide was the function of its concentration. Further, in acid salt spray and filiform corrosion tests, oxide layer containing silicate exhibited two times higher corrosion resistance.

  12. Copper Containing Silicates as Catalysts for Liquid Phase Cyclohexane Oxidation

    Directory of Open Access Journals (Sweden)

    Cruz Rosenira S. da

    2002-01-01

    Full Text Available Copper containing silicates have been prepared by an acid-catalyzed sol-gel process. The materials were characterized by X-ray diffraction and fluorescence, EPR spectroscopy, elemental analysis, N2-physisorption, thermogravimetry, differential scanning calorimetry, temperature-programmed reduction, FTIR and UV/VIS spectroscopy. The silicates were shown to be efficient catalysts for the oxidation of cyclohexane with tert-butyl hydroperoxide as oxidant. Cyclohexanol and cyclohexanone were obtained as the main products. The metal was shown to be weakly bound to the silicate matrix and metal leaching was observed. Leaching was quantified by X-ray fluorescence and leaching tests showed that the catalytic activity is due to supported copper species. Leached copper showed no activity in the homogeneous phase.

  13. Rubber curing chemistry governing the orientation of layered silicate

    Directory of Open Access Journals (Sweden)

    2007-11-01

    Full Text Available The effect of curing systems on the orientation and the dispersion of the layered silicates in acrylonitrile butadiene rubber nanocomposite is reported. Significant differences in X-ray diffraction pattern between peroxide curing and sulfur curing was observed. Intense X-ray scattering values in the XRD experiments from peroxide cured vulcanizates indicate an orientation of the layers in a preferred direction as evinced by transmission electron micrographs. However, sulfur cured vulcanizates show no preferential orientation of the silicate particles. Nevertheless, a closer inspection of transmission electron microscopy (TEM images of peroxide and sulfur cured samples shows exfoliated silicate layers in the acrylonitrile butadiene rubber (NBR matrix. It was revealed in the prevailing study that the use of an excess amount of stearic acid in the formulation of the sulfur curing package leads to almost exfoliated type X-ray scattering pattern.

  14. Petrophysical Analysis of Siliceous Ooze Sediments, Ormen Lange Field, Norway

    DEFF Research Database (Denmark)

    Awedalkarim, Ahmed; Fabricius, Ida Lykke

    structure is complex and the solids are mechanically fragile and hydrous. Normal petrophysical methods used in formation evaluation might not be suitable for interpreting siliceous ooze. For example, density and neutron logging tools are calibrated to give correct porosity readings in a limestone formation...... to analyse and interpret logging data acquired through siliceous ooze sediments. Our main objectives were to characterize and evaluate the petrophysics of siliceous ooze and to find the true porosity and water saturation to test its hydrocarbon reservoir potential. We used and integrated core analysis data...... with logging data from four Ormen Lange wells, and included X-ray diffraction analysis (XRD) data. Additionally, other available information such as petrographic thin-section analysis, core computed tomography scans (CT-scans), scanning electron microscope (SEM), and other published data were used here...

  15. Potential of calcium silicate to mitigate water deficiency in maize

    Directory of Open Access Journals (Sweden)

    Douglas José Marques

    2016-01-01

    Full Text Available ABSTRACT The aim of this study was to evaluate the potential of calcium silicate to mitigate the effects of water deficiency in maize plants yield. A completely randomized factorial design, consisting of five combinations of calcium silicate (0, 25, 50, 75, and 100% and five different soil moisture levels (30, 70, 100, 130, and 160%, was adopted. The following parameters were evaluated: soil matric potential, xylem water potential, silicon concentration, leaf dry weight, and dry mass production. Matric potential monitoring confirmed that the irrigation depths employed resulted in different environments for maize plant development during the experiment. Confirming the hypothesis of the study, at the lower irrigation depths, the maize production has accompanied the increase in calcium silicate used as corrective up to the proportion of 50%. These results indicate that silicon mitigated the impact of water deficiency in maize plants and increased the xylem water potential.

  16. Energetic Processing of Interstellar Silicate Grains by Cosmic Rays

    Energy Technology Data Exchange (ETDEWEB)

    Bringa, E M; Kucheyev, S O; Loeffler, M J; Baragiola, R A; Tielens, A G Q M; Dai, Z R; Graham, G; Bajt, S; Bradley, J; Dukes, C A; Felter, T E; Torres, D F; van Breugel, W

    2007-03-28

    While a significant fraction of silicate dust in stellar winds has a crystalline structure, in the interstellar medium nearly all of it is amorphous. One possible explanation for this observation is the amorphization of crystalline silicates by relatively 'low' energy, heavy ion cosmic rays. Here we present the results of multiple laboratory experiments showing that single-crystal synthetic forsterite (Mg{sub 2}SiO{sub 4}) amorphizes when irradiated by 10 MeV Xe{sup ++} ions at large enough fluences. Using modeling, we extrapolate these results to show that 0.1-5.0 GeV heavy ion cosmic rays can rapidly ({approx}70 Million yrs) amorphize crystalline silicate grains ejected by stars into the interstellar medium.

  17. Potassium Silicate Foliar Fertilizer Grade from Geothermal Sludge and Pyrophyllite

    Directory of Open Access Journals (Sweden)

    Muljani Srie

    2016-01-01

    Full Text Available Potassium silicate fertilizer grade were successfully produced by direct fusion of silica (SiO2 and potasium (KOH and K2CO3 in furnaces at temperatures up to melting point of mixture. The geothermal sludge (98% SiO2 and the pyrophyllite (95% SiO2 were used as silica sources. The purposes of the study was to synthesise potassium silicate fertilizer grade having solids concentrations in the range of 31-37% K2O, and silica in the range of 48-54% SiO2. The weight ratio of silicon dioxide/potasium solid being 1:1 to 5:1. Silica from geothermal sludge is amorphous, whereas pyrophylite is crystalline phase. The results showed that the amount of raw materials needed to get the appropriate molar ratio of potassium silicate fertilizer grade are different, as well as the fusion temperature of the furnace. Potassium silicate prepared from potassium hydroxide and geothermal sludge produced a low molar ratio (2.5: 1 to 3: 1. The potassium required quite small (4:1 in weight ratio, and on a fusion temperature of about 900 °C. Meanwhile, the potassium silicate prepared from pyrophyllite produced a high molar ratio (1.4 - 9.4 and on a fusion temperature of about 1350 °C, so that potassium needed large enough to meet the required molar ratio for the fertilizer grade. The product potassium silicate solid is amorphous with a little trace of crystalline.

  18. Polymer layered silicate nanocomposites: Structure, morphology, and properties

    Science.gov (United States)

    Nawani, Pranav

    Layered silicates are important fillers for improving various mechanical, flame retardant, and barrier properties of polymers, which can be attributed to their sheet-like morphology. Layered silicates can be modified with organic surfactants to render them compatible with polymer matrices. Organically modified silicates (organoclays) having large surface areas are very cost-efficient non-toxic nanofillers effective at very low loads and are readily available. Upon amalgamation of organoclays with polymer matrix nanocomposites, polymer chains can penetrate in between the silicate layers and result in an intercalated structure where the clay stack remains intact but the interlayer spacing is increased. When penetration becomes more severe, disintegration of clay stacks can occur, resulting in an exfoliated structure. It has often been observed that exfoliation is not complete down to the level of isolated silicate layers; rather, the large clay stacks are broken up into shorter stacks termed 'tactoids' together with a few individual silicate layers, resulting in a kind of mixed intercalated-exfoliated structure. Organoclay particles are mostly intercalated, having a preferred orientation with the clay gallery planes being preferentially parallel to the plane of the pressed film. Preferential orientation of organoclays affects the barrier properties of polymer membranes. Additional fillers like carbon black can induce a change in the orientation of organoclays. The effect of carbon black on the orientation of organoclays was elucidated and a relationship between orientation and permeability of air through such membranes was established. We have also investigated the flammability properties of a series of polymer nanocomposites, containing various Transition Metal Ion (TMI) modified organoclays. The improved fire retardation in nanocomposites with TMI-modified organoclays can be attributed to enhanced carbonaceous char formation during combustion, i.e., charring

  19. Leaf application of silicic acid to upland rice and corn

    Directory of Open Access Journals (Sweden)

    Carlos Alexandre Costa Crusciol

    2013-12-01

    Full Text Available This study aimed to evaluate the effect of Si (stabilized silicic acid, Silamol® leaf application on mineral nutrition and yield in upland rice and corn crops. The treatments were the control (without Si and Si foliar split spraying using 2 L ha-1 of the Silamol® commercial product, with 0.8% soluble Si as concentrated stabilized silicic acid. Silicon leaf application increased the concentrations of K, Ca and Si in rice and corn leaves, the number of panicles per m2 of rice and the number of grains per ear of corn; accordingly, the Si leaf application provided a higher grain yield in both crops.

  20. Non-conservative controls on distribution of dissolved silicate in Cochin Backwaters

    Digital Repository Service at National Institute of Oceanography (India)

    Balachandran, K.K.; Sankaranarayanan, V.N.; Joseph, T.; Nair, M.

    Cochin backwater system was studied with regard to dissolved silicate (DSi) to understand its seasonal distribution and behaviour during estuarine mixing. Silicate had a linear relationship with salinity during the high river discharge period...

  1. Quantitative Estimation of the Reinforcing Effect of Layered Silicates in PP Nanocomposites

    NARCIS (Netherlands)

    Szazdi, Laszlo; Pukansky Jr, Bela; Vancso, Gyula J.; Pukanszky, B.; Pukanszky, Bela

    2006-01-01

    Various polypropylene/layered silicate composites were prepared with different silicate contents. Montmorillonites with and without organophilization as well as three maleinated polypropylenes were used to change the extent of exfoliation and hence the properties of the composites. Structure was

  2. Pyrolysis result of polyethylene waste as fuel for solid oxide fuel cell with samarium doped-ceria (SDC)-carbonate as electrolyte

    Science.gov (United States)

    Syahputra, R. J. E.; Rahmawati, F.; Prameswari, A. P.; Saktian, R.

    2017-02-01

    In this research, the result of pyrolysis on polyethylene was used as fuel for a solid oxide fuel cell (SOFC). The pyrolysis result is a liquid which consists of hydrocarbon chains. According to GC-MS analysis, the hydrocarbons mainly consist of C7 to C20 hydrocarbon chain. Then, the liquid was applied to a single cell of NSDC-L | NSDC | NSDC-L. NSDC is a composite SDC (samarium doped-ceria) with sodium carbonate. Meanwhile, NSDC-L is a composite of NSDC with LiNiCuO (LNC). NSDC and LNC were analyzed by X-ray diffraction to understand their crystal structure. The result shows that presence of carbonate did not change the crystal structure of SDC. SEM EDX analysis for fuel cell before and after being loaded with polyethylene oil to get information of element diffusion to the electrolyte. Meanwhile, the conductivity properties were investigated through impedance measurement. The presence of carbonate even increases the electrical conductivity. The single cell test with the pyrolysis result of polyethylene at 300 - 600 °C, found that the highest power density is at 600 °C with the maximum power density of 0.14 mW/cm2 and open circuit voltage of 0.4 Volt. Elemental analysis at three point spots of single cell NDSC-L |NSDC|NSDC-L found that a migration of ions was occurred during fuel operation at 300 - 600 °C.

  3. Effects of some rare earth and carbonate-based co-dopants on structural and electrical properties of samarium doped ceria (SDC) electrolytes for solid oxide fuel cells

    Science.gov (United States)

    Anwar, Mustafa; Khan, Zuhair S.; Mustafa, Kamal; Rana, Akmal

    2015-09-01

    In the present study, samarium doped ceria (SDC) and SDC-based composite with the addition of K2CO3 were prepared by co-precipitation route and effects of pH of the solution and calcination temperature on microstructure of SDC and SDC-K2CO3, respectively, were investigated. Furthermore, experimentation was performed to investigate into the ionic conductivity of pure SDC by co-doping with yttrium i.e., YSDC, XRD and SEM studies show that the crystallite size and particle size of SDC increases with the increase in pH. The SEM images of all the samples of SDC synthesized at different pH values showed the irregular shaped and dispersed particles. SDC-K2CO3 was calcined at 600∘C, 700∘C and 800∘C for 4 h and XRD results showed that crystallite size increases while lattice strain, decreases with the increase in calcination temperature and no peaks were detected for K2CO3 as it is present in an amorphous form. The ionic conductivity of the electrolytes increases with the increase in temperature and SDC-K2CO3 shows the highest value of ionic conductivity as compared to SDC and YSDC. Chemical compatibility tests were performed between the co-doped electrolyte and lithiated NiO cathode at high temperature. It revealed that the couple could be used up to the temperature of 700∘C.

  4. Calculation of the Dose of Samarium-153-Ethylene Diamine Tetramethylene Phosphonate (153Sm-EDTMP as a Radiopharmaceutical for Pain Relief of bone Metastasis

    Directory of Open Access Journals (Sweden)

    Fatemeh Razghandi

    2016-04-01

    Full Text Available Introduction One of the important applications of nuclear physics in medicine is the use of radioactive elements as radiopharmaceuticals. Metastatic bone disease is the most common form of malignant bone tumors. Samarium-153-ethylene diamine tetramethylene phosphonate (153Sm-EDTMP as a radiopharmaceutical is used for pain palliation. This radiopharmaceutical usually emits beta particles, which have a high uptake in bone tissues. The purpose of this study was to calculate the radiation dose distribution of 153Sm-EDTMP in bone and other tissues, using MCNPX Monte Carlo code in the particle transport model. Materials and Methods Dose delivery to the bone was simulated by seeking radiopharmaceuticals on the bone surface. The phantom model had a simple cylindrical geometry and included bone, bone marrow, and soft tissue. Results The simulation results showed that a significant amount of radiation dose was delivered to the bone by the use of this radiopharmaceutical. Conclusion Thebone acted as a fine protective shield against rays for the bone marrow. Therefore, the trivial absorbed dose by the bone marrow caused less damage to bone-making cells. Also, the high absorbed dose of the bone could destroy cancer cells and relieve the pain in the bone.

  5. Synthesis, quality control and biological evaluation of tris[(1,10-phenanthroline)[{sup 153}Sm]samarium(III)]trithiocyanate complex as a therapeutic agent

    Energy Technology Data Exchange (ETDEWEB)

    Naseri, Z.; Kharat, A. Nemati [Tehran Univ. (Iran, Islamic Republic of). Inorganic Chemistry Dept.; Hakimi, A. [Islamic Azad Univ., Tehran (Iran, Islamic Republic of). Dept. of Nuclear Engineering, Science and Research Branch; Jalilian, A.R.; Shirvani-Arani, S.; Bahrami-Samani, A.; Ghannadi-Maragheh, M. [Nuclear Science and Technology Research Institute (NSTRI), Tehran (IR). Radiopharmaceutical Research and Development Lab (RRDL)

    2012-07-01

    Therapeutic radiopharmaceuticals are designed to deliver high doses of radiation to selected target organs or tissues with an aim of minimizing unwanted radiation to surrounding healthy tissue. In this work, [tris(1,10-phenanthroline)[{sup 153}Sm]samarium(III)]trithiocyanate ({sup 153}Sm-TPTTC) was developed for possible therapeutic properties. The cold compound, i.e. {sup nat}Sm-TPTTC was prepared and characterized by IR, UV, mass and {sup 1}H-NMR spectroscopy. {sup 153}Sm-TPTTC was prepared in two steps using [{sup 153}Sm]SmCl{sub 3}, obtained by neutron activation of an enriched {sup 152}Sm sample. Stability tests, partition coefficient determination, toxicity tests and biodistribution studies of the complex in wild-type and fibrosarcoma-bearing mice were determined. The radiolabeled complex was prepared in high radiochemical purity (> 99% precipitation method) and specific activity of 278 GBq/mmol and demonstrated significant stability at 4, 25 and 37 C (in presence of human serum). Initial complex biodistribution data showed significant liver accumulation in wild-type mice and significant tumor accumulation in fibrosarcoma-bearing mice with tumor:blood and tumor:muscle ratios of 3.55 (2 h) and 38.26 (96 h) respectively. {sup 153}Sm-TPTTC properties suggest an efficient tumor targeting agent with high tumor-avidity. Further investigation on the therapeutic properties must be conducted. (orig.)

  6. PETROLOGY AND GEOCHEMISTRY OF CALC-SILICATE SCHISTS ...

    African Journals Online (AJOL)

    DR OKONKOWO

    2012-02-29

    Feb 29, 2012 ... Calc-silicate diffusion zones between marble and pelitic schist. Journal of. Petrology, 16, 314-346. Turner, D. C., 1983. Upper Proterozoic Schist Belts in the Nigerian sector of the Pan-African province of West Africa. Precambrian Research, 21, 55-. 79. Van de Kamp, P. C., 1968. Geochemistry and origin of.

  7. Dry phosphorus silicate glass etching for multicrystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Nositschka, W.A.; Voigt, O.; Kurz, H. [Aachen Univ. (Germany). Inst. of Semiconductor Electronics; Kenanoglu, A.; Borchert, D. [Fraunhofer Inst. for Solar Energy Systems, Gelsenkirchen (Germany)

    2003-07-01

    A dry plasma etching process for phosphorus silicate glass (PSG) in a SiN-PECVD batch reactor is developed. In the same reactor PSG etching and anti-reflective coating (ARC) can be performed successively. To demonstrate industrial feasibility, screen-printed solar cells are manufactured and compared with cells prepared by a standard wet chemical process. (Author)

  8. Effects of Mixed Alkaline Earth Oxides in Potash Silicate Glass ...

    African Journals Online (AJOL)

    The aim of this work is to investigate the effects of mixed alkaline earth oxide in potash silicate glasses with regards to their physical properties. More recently; there has been an increase in the demand for light weight glasses which retains their physical and chemical properties for both domestic and industrial applications.

  9. High-pressure physical properties of magnesium silicate post ...

    Indian Academy of Sciences (India)

    dLaboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Academy of Engineering. Physics, PO Box 919-102, Mianyang 621900, China. MS received 1 May 2011. Abstract. The structure, thermodynamic and elastic properties of magnesium silicate (MgSiO3) post-perovskite at high pressure ...

  10. Vesuvianite–wollastonite–grossular-bearing calc-silicate rock near ...

    Indian Academy of Sciences (India)

    This paper reports the occurrence of vesuvianite + wollastonite + grossular + diopside + microcline + quartz assemblage in an enclave of calc-silicate rocks occurring within quartzofeldspathic gneiss near Tatapani in the western part of Chhotanagpur Gneissic Complex. The enclave contains phlogopite-absent and ...

  11. Effects of Aluminium–Magnesium Silicate on Newcastle Disease ...

    African Journals Online (AJOL)

    Effect of a synthetic Aluminium – Magnesium Silicate (AMS) on Newcastle Disease Virus (NDV) was tested. Equal amounts, of the AMS and of NDV, on a volume to weight (v/w) basis, were incubated for one hour at room temperature, and then centrifuged. The supernatant was tested for NDV titre. Portions of a virulent NDV ...

  12. Preparation and characterization of magnesium–aluminium–silicate ...

    Indian Academy of Sciences (India)

    A three-stage heating schedule involving calcination, nucleation and crystallization, has been evolved for the preparation of magnesium aluminium silicate (MAS) glass ceramic with MgF2 as a nucleating agent. The effect of sintering temperature on the density of compacted material was studied. Microstructure and ...

  13. Determination of reactivity rates of silicate particle-size fractions

    Directory of Open Access Journals (Sweden)

    Angélica Cristina Fernandes Deus

    2014-04-01

    Full Text Available The efficiency of sources used for soil acidity correction depends on reactivity rate (RR and neutralization power (NP, indicated by effective calcium carbonate (ECC. Few studies establish relative efficiency of reactivity (RER for silicate particle-size fractions, therefore, the RER applied for lime are used. This study aimed to evaluate the reactivity of silicate materials affected by particle size throughout incubation periods in comparison to lime, and to calculate the RER for silicate particle-size fractions. Six correction sources were evaluated: three slags from distinct origins, dolomitic and calcitic lime separated into four particle-size fractions (2, 0.84, 0.30 and <0.30-mm sieves, and wollastonite, as an additional treatment. The treatments were applied to three soils with different texture classes. The dose of neutralizing material (calcium and magnesium oxides was applied at equal quantities, and the only variation was the particle-size material. After a 90-day incubation period, the RER was calculated for each particle-size fraction, as well as the RR and ECC of each source. The neutralization of soil acidity of the same particle-size fraction for different sources showed distinct solubility and a distinct reaction between silicates and lime. The RER for slag were higher than the limits established by Brazilian legislation, indicating that the method used for limes should not be used for the slags studied here.

  14. Estimation of high temperature metal-silicate partition coefficients

    Science.gov (United States)

    Jones, John H.; Capobianco, Christopher J.; Drake, Michael J.

    1992-12-01

    It has been known for some time that abundances of siderophile elements in the upper mantle of the Earth are far in excess of those expected from equilibrium between metal and silicate at low pressures and temperatures. Murthy (1991) has re-examined this excess of siderophile element problem by estimating liquid metal/liquid silicate partition coefficients reduces from their measured values at a lower temperature, implying that siderophile elements become much less siderophilic at high temperatures. Murthy then draws the important conclusion that metal/silicate equilibrium at high temperatures can account for the abundances of siderophile elements in the Earth's mantle. Of course, his conclusion is critically dependent on the small values of the partition coefficients he calculates. Because the numerical values of most experimentally-determined partition coefficients increase with increasing temperature at both constant oxygen fugacity and at constant redox buffer, we think it is important to try an alternative extrapolation for comparison. We have computed high temperature metal/silicate partition coefficients under a different set of assumptions and show that such long temperature extrapolations yield values which are critically dependent upon the presumed chemical behavior of the siderophile elements in the system.

  15. In vitro bioactivity and cytocompatibility of tricalcium silicate

    Indian Academy of Sciences (India)

    In vitro cytocompatible evaluation reveals that osteoblasts adhere and spread well on the Ca3SiO5 ceramics, indicating good bioactivity and cytocompatibility. Keywords. Tricalcium silicate; bioactivity; cytocompatibility; hydroxyapatite; osteoblasts. 1. Introduction. Up to now, many bioactive biomaterials, such as A/W glass.

  16. Mineralogy and trace element chemistry of the Siliceous Earth of ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    We report the presence of a 3–5 cm thick loose fragmental layer in the Siliceous Earth at Matti ka. Gol in the Barmer basin of Rajasthan. Petrographic, chemical and mineralogical study reveals the presence of abundant volcanic debris such as glass shards, agglutinates, hollow spheroids, kinked biotites, feldspars showing ...

  17. Potassium silicate-zinc oxide solution for metal finishes

    Science.gov (United States)

    Schutt, J. B.

    1970-01-01

    Examples of zinc dust formulations, which are not subject to cracking or crazing, are fire retardant, and have high adhesive qualities, are listed. The potassium silicate in these formulations has mol ratios of dissolved silica potassium oxide in the range 4.8 to 1 - 5.3 to 1.

  18. Fluoroalkylsilane versus Alkylsilane as Hydrophobic Agents for Silica and Silicates

    Directory of Open Access Journals (Sweden)

    Damian Ambrożewicz

    2013-01-01

    Full Text Available Hydrophobic powders were obtained via surface modification of silica or magnesium silicate with selected silanes. A modified precipitation method, carried out in an emulsion system, was used for monodisperse silica synthesis, while magnesium silicate was precipitated in a traditional water system. Functionalization of the obtained inorganic supports was performed with selected alkylsilanes: one newly synthesized, 3-(2,2,3,3,4,4,5,5-octafluoropentyloxypropyltriethoxysilane (OPF, and two commercial, octadecylsilane (ODS and octyltriethoxysilane C14H32O3Si (OCS, in amounts of 3, 5, or 10 weight parts by mass of SiO2. It was determined how the chemical modification of the silica or magnesium silicate surface affected its physicochemical properties. The dispersive characteristics of both unmodified and functionalized silica-based systems were evaluated. The morphology and microstructure of the samples obtained were analyzed using scanning electron microscopy. The parameters of porous structure of the prepared systems were evaluated on the basis of BET equation as well as nitrogen adsorption/desorption isotherms. Wettability tests as well as elemental analysis of the obtained inorganic oxide hybrids were also performed. In order to verify the effectiveness of silica and magnesium silicate surface functionalization with selected silanes, FTIR spectra were investigated. The resulting experimental data allowed calculation of the degree of coverage of the silica-based systems with modifying agents.

  19. Evaluation of Calcium Silicate Cement Bond Strength after Using ...

    African Journals Online (AJOL)

    2018-01-24

    Jan 24, 2018 ... Objectives: To determine the effect of different gutta‑percha solvents. (chloroform, Endosolv E, orange oil, and eucalyptol) on the push‑out bond strength of calcium silicate cements (CSCs; white mineral trioxide aggregate. [WMTA]; capsule‑form mineral trioxide aggregate [CMTA], and Biodentine). Materials ...

  20. Energetics of silicate melts from thermal diffusion studies

    Energy Technology Data Exchange (ETDEWEB)

    Walker, D.

    1992-07-01

    Efforts are reported in the following areas: laboratory equipment (multianvils for high P/T work, pressure media, SERC/DL sychrotron), liquid-state thermal diffusion (silicate liquids, O isotopic fractionation, volatiles, tektites, polymetallic sulfide liquids, carbonate liquids, aqueous sulfate solutions), and liquid-state isothermal diffusion (self-diffusion, basalt-rhyolite interdiffusion, selective contamination, chemical diffusion).

  1. 77 FR 21676 - Silicic Acid, Sodium Salt etc.; Tolerance Exemption

    Science.gov (United States)

    2012-04-11

    ... chlorotrimethylsilane and iso-propyl alcohol, reaction with poly(oxypropylene)-poly(oxyethylene) glycol; when used as an... residues of Silicic acid, sodium salt, reaction products with chlorotrimethylsilane and iso-propyl alcohol...-OPP-2011-0934, by one of the following methods. Federal eRulemaking Portal: http://www.regulations.gov...

  2. Ubiquitous high-FeO silicates in enstatite chondrites

    Science.gov (United States)

    Lusby, David; Scott, Edward R. D.; Keil, Klaus

    1987-01-01

    SEM and EMPA were used to determine the mineral contents of four EH3 chondrites. All four showed the dominant enstatite peak, Fs 0-5, with 4-8 percent of FeO-rich pyroxene with Fs 5-20. Among the 542 objects found to contain high-FeO silicates, 18 were chondrules, 381 were rimmed or unrimmed grains, and 143 were aggregates. The high-FeO silicates in these objects are very largely pyroxene with Fs 5-23. Large grains of both FeO-rich and FeO-poor silicates were found to be present in the FeO-rich chondrules. This fact, together with the absence of clasts of FeO-rich chondritic material in the EH3 chondrites, suggests that FeO-rich grains were introduced before or during chondrule formation. It is concluded that FeO-rich and FeO-poor silicates were both present in the nebular region where E chondrites originated.

  3. Mineralogy and trace element chemistry of the Siliceous Earth of ...

    Indian Academy of Sciences (India)

    We report the presence of a 3-5 cm thick loose fragmental layer in the Siliceous Earth at Matti ka Gol in the Barmer basin of Rajasthan. Petrographic, chemical and mineralogical study reveals the presence of abundant volcanic debris such as glass shards, agglutinates, hollow spheroids, kinked biotites, feldspars showing ...

  4. Oxygen from the lunar soil by molten silicate electrolysis

    Science.gov (United States)

    Colson, Russell O.; Haskin, Larry A.

    1992-01-01

    Accepting that oxygen, rather than gigantic gems or gold, is likely to make the Moon's Klondike, the extraction of oxygen from the lunar soil by molten silicate electrolysis has chosen to be investigated. Process theory and proposed lunar factory are addressed.

  5. A Siliceous Microfossil View of Middle Eocene Arctic Paleoenvironments

    Science.gov (United States)

    Stickley, C. E.; Koc, N.; Brumsack, H.; Jordan, R. W.; Suto, I.

    2007-12-01

    Integrated Ocean Drilling Program Expedition 302, "The Arctic Coring Expedition" (ACEX) made arguably the most significant discovery of Paleogene siliceous microfossils in nearly 2 decades. 100 m of mm to sub-mm laminated biosiliceous sediments of Middle Eocene age are rich in marine and freshwater siliceous microfossils allowing intriguing insights into central Arctic paleoenvironments during the start of Cenozoic cooling to icehouse conditions. Largely endemic assemblages of marine diatoms and ebridians are preserved along with very high abundances of chrysophyte cysts, the endogenously formed resting stage of freshwater algae. These siliceous microfossil groups imply an overall brackish environment, but variations in group dominance suggest episodic variations in salinity, stratification and trophic status. We synthesize the overall characteristics of the biosiliceous sediments by reporting on broad scale variations in siliceous microfossils and give some exciting insights into the composition of the laminae which may help explain the formation of these sediments. Our results indicate basin-wide paleo-environmental fluctuations on long- and possibly seasonal timescales.

  6. Mesoporous silicates: Materials science and biological applications

    Science.gov (United States)

    Roggers, Robert Anthony

    This thesis dissertation presents the collective research into the advancement of mesoporous silicate particles as biointerface devices, the development of new materials and the application of these particles as solid supports for heterogeneous catalysis. Mesoporous silica has been utilized in the aforementioned applications due to several reasons; the first being the ability to achieve high surface areas (500 - 1000 m2 g-1) with controlled pore sizes and particle morphology. Another reason for their popularity is their robustness in applications of heterogeneous catalysis and the ability to functionalize the surface with a wide variety of organic functional groups. In the field of biointerface devices, mesoporous silica nanoparticles represent a class of materials that exhibit high biocompatibility. In addition, the ability to functionalize the surfaces (outer surface and pore interiors) allows the particles to be targeted to specific cell types as well as the ability to release many different therapeutic molecules under specific stimuli. A unique particle coating consisting of a chemically cleavable lipid bilayer that allows for the encapsulation of a fluorescent molecule and increases the biocompatibility of the particle has been developed. The lipid bilayer coated mesoporous silica nanoparticle (LB-MSN) was characterized using X-ray diffraction, transmission electron microscopy and nitrogen `sorption isotherms. The finished LB-MSN was then incubated with mammalian cells in order to prove their biocompatibility. Confocal micrographs demonstrate the endocytosis of the particles into the cells. In addition the micrographs also show that the LB-MSNs are separate from the endosomal compartments, however due to the lipophilic nature of the dye used to label the endosome there is some debate regarding this conclusion. The lipid bilayer coating was then applied to a large pore MSN (l-MSN) which had been previously shown to cause lysis of red blood cells (RBCs) at low

  7. Silicate Dispersion and Mechanical Reinforcement in Polysiloxane/Layered Silicate Nanocomposites

    KAUST Repository

    Schmidt, Daniel F.

    2010-01-12

    We report the first in-depth comparison of the mechanical properties and equilibrium solvent uptake of a range of polysiloxane nanocomposites based on treated and untreated montmorillonite and fumed silica nanofillers. We demonstrate the ability of equilibrium solvent uptake data (and, thus, overall physical and chemical cross-link density) to serve as a proxy for modulus (combining rubber elasticity and Flory-Rehner theory), hardness (via the theory of Boussinesq), and elongation at break, despite the nonideal nature of these networks. In contrast, we find that tensile and tear strength are not well-correlated with solvent uptake. Interfacial strength seems to dominate equilibrium solvent uptake and the mechanical properties it predicts. In the montmorillonite systems in particular, this results in the surprising consequence that equilibrium solvent uptake and mechanical properties are independent of dispersion state. We conclude that edge interactions play a more significant role than degree of exfoliation, a result unique in the field of polymer nanocomposites. This demonstrates that even a combination of polymer/nanofiller compatibility and thermodynamically stable nanofiller dispersion levels may not give rise to reinforcement. These findings provide an important caveat when attempting to connect structure and properties in polymer nanocomposites, and useful guidance in the design of optimized polymer/layered silicate nanocomposites in particular. © 2009 American Chemical Society.

  8. Production test IP-728 half-plant sodium silicate test. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Geier, R.G.

    1966-07-28

    The sodium silicate addition to the coolant reduced the effluent concentrations of certain radionuclides. Nothing was observed during the course of the test to indicate that sodium silicate could not be used at all plants. However, the reductions obtained in effluent activity are not believed commensurate with the cost of silicate usage.

  9. Silicate Phases on the Surfaces of Trojan Asteroids

    Science.gov (United States)

    Martin, Audrey; Emery, Joshua P.; Lindsay, Sean S.

    2017-10-01

    Determining the origin of asteroids provides an effective means of constraining the solar system’s dynamic past. Jupiter Trojan asteroids (hereafter Trojans) may help in determining the amount of radial mixing that occurred during giant planet migration. Previous studies aimed at characterizing surface composition show that Trojans have low albedo surfaces and are spectrally featureless in the near infrared. The thermal infrared (TIR) wavelength range has advantages for detecting silicates on low albedo asteroids such as Trojans. The 10 μm region exhibits strong features due to the Si-O fundamental molecular vibrations. Silicates that formed in the inner solar system likely underwent thermal annealing, and thus are crystalline, whereas silicates that accreted in the outer solar system experienced less thermal processing, and therefore are more likely to have remained in an amorphous phase. We hypothesize that the Trojans formed in the outer solar system (i.e., the Kuiper Belt), and therefore will have a more dominant amorphous spectral silicate component. With TIR spectra from the Spitzer Space Telescope, we identify mineralogical features from the surface of 11 Trojan asteroids. Fine-grain mixtures of crystalline pyroxene and olivine exhibit a 10 μm feature with sharp cutoffs between about 9 μm and 12 μm, which create a broad flat plateau. Amorphous phases, when present, smooth the sharp emission features, resulting in a dome-like shape. Preliminary results indicate that the surfaces of analyzed Trojans contain primarily amorphous silicates. Emissivity spectra of asteroids 1986 WD and 4709 Ennomos include small peaks in the 10 μm region, diagnostic of small amounts of crystalline olivine. One explanation is that Trojans formed in the same region as Kuiper Belt objects, and when giant planet migration ensued, they were swept into Jupiter’s stable Lagrange points where they are found today. As such, it is possible that an ancestral group of Kuiper Belt

  10. Wastewater reuse in liquid sodium silicate manufacturing in alexandria, egypt.

    Science.gov (United States)

    Ismail, Gaber A; Abd El-Salam, Magda M; Arafa, Anwar K

    2009-01-01

    Soluble sodium silicates (waterglass) are liquids containing dissolved glass which have some water like properties. They are widely used in industry as sealants, binders, deflocculants, emulsifiers and buffers. Their most common applications in Egypt are in the pulp and paper industry (where they improve the brightness and efficiency of peroxide bleaching) and the detergent industry, in which they improve the action of the detergent and lower the viscosity of liquid soaps. The survey results showed that the production was carried out batch-wise, in an autoclave (dissolver). Sodium silicate in the state of crushed glass was charged in an autoclave (dissolver) with sodium hydroxide and water. The product is filtered through a press. The left over sludge (mud and silicates impurities) is emptied into the local sewer system. Also, sludge (silica gel) was discharged from the neutralization process of the generated alkaline wastewater and consequently clogging the sewerage system. So this study was carried out to modify the current wastewater management system which eliminates sludge formation, the discharge of higher pH wastewater to the sewer system, and to assess its environmental and economic benefits. To assess the characteristics of wastewater to be reused, physico-chemical parameters of 12 samples were tested using standard methods. The survey results showed that a total capacity of the selected enterprise was 540 tons of liquid sodium silicates monthly. The total amount of wastewater being discharged was 335 m3/month. Reusing of wastewater as feed autoclave water reduced water consumption of 32.1% and reduced wastewater discharge/month that constitutes 89.6% as well as saving in final product of 6 ton/month. It was concluded that reusing of wastewater generated from liquid sodium silicate manufacturing process resulted in cheaper and environmental-friendly product.

  11. Effect of silicate module of water glass on rheological parameters of poly(sodium acrylate)/sodium silicate hydrogels

    Science.gov (United States)

    Mastalska-Popiawska, J.; Izak, P.

    2017-01-01

    The poly(sodium acrylate)/sodium silicate hydrogels were synthesized in the presence of sodium thiosulphate and potassium persulphate as the redox initiators and N,N’-methylene-bisacrylamide as the cross-linking monomer. 20 wt% aqueous solution of sodium acrylate was polymerized together with water glass with different silicate modules (M) from 1.74 to 2.29, in three mass ratio of the monomer solution to the water glass 2:1, 1:1 and 1:2. Such obtained hybrid composites were rheologically tested using the oscillation method. It allowed to designate the crossover point during polymerization, as well as to define the viscoelastic properties of the casted hydrogel samples one week after the reaction. The obtained results of the oscillation measurements showed that cross-linking reaction proceeds very quickly and the lower the silicate module is, the process starts faster. After the completion of the reaction the silicate-polymer hydrogels are strongly elastic materials and the highest elasticity characterizes systems with the mass ratio 1:2, i.e. with the highest water glass content.

  12. Biological and therapeutic effects of ortho-silicic acid and some ortho-silicic acid-releasing compounds: New perspectives for therapy

    Directory of Open Access Journals (Sweden)

    Jurkić Lela Munjas

    2013-01-01

    Full Text Available Abstract Silicon (Si is the most abundant element present in the Earth's crust besides oxygen. However, the exact biological roles of silicon remain unknown. Moreover, the ortho-silicic acid (H4SiO4, as a major form of bioavailable silicon for both humans and animals, has not been given adequate attention so far. Silicon has already been associated with bone mineralization, collagen synthesis, skin, hair and nails health atherosclerosis, Alzheimer disease, immune system enhancement, and with some other disorders or pharmacological effects. Beside the ortho-silicic acid and its stabilized formulations such as choline chloride-stabilized ortho-silicic acid and sodium or potassium silicates (e.g. M2SiO3; M= Na,K, the most important sources that release ortho-silicic acid as a bioavailable form of silicon are: colloidal silicic acid (hydrated silica gel, silica gel (amorphous silicon dioxide, and zeolites. Although all these compounds are characterized by substantial water insolubility, they release small, but significant, equilibrium concentration of ortho-silicic acid (H4SiO4 in contact with water and physiological fluids. Even though certain pharmacological effects of these compounds might be attributed to specific structural characteristics that result in profound adsorption and absorption properties, they all exhibit similar pharmacological profiles readily comparable to ortho-silicic acid effects. The most unusual ortho-silicic acid-releasing agents are certain types of zeolites, a class of aluminosilicates with well described ion(cation-exchange properties. Numerous biological activities of some types of zeolites documented so far might probably be attributable to the ortho-silicic acid-releasing property. In this review, we therefore discuss biological and potential therapeutic effects of ortho-silicic acid and ortho-silicic acid -releasing silicon compounds as its major natural sources.

  13. Retention capacity of samarium (III) in zircon for it possible use in retaining walls for confinement of nuclear residues; Capacidad de retencion de samario (III) en circon para su posible uso en barreras de contencion para confinamiento de residuos nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Garcia G, N

    2006-07-01

    Mexico, as country that produces part of its electric power by nuclear means, should put special emphasis in the development of technologies guided to the sure and long term confinement of the high level nuclear residuals. This work studies the capacity that has the natural zircon to retain to the samarium (III) in solution, by what due, firstly, to characterize the zircon for technical instrumental to determine the purity and characteristic of the mineral in study. The instrumental techniques that were used to carry out the physicochemical characterization were the neutron activation analysis (NAA), the infrared spectroscopy (IS), the thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), semiquantitative analysis, dispersive energy spectroscopy (EDS), X-ray diffraction (XRD) and luminescence technique. The characterization of the surface properties carries out by means of the determination of the surface area using the BET multipoint technique, acidity constants, hydration time, the determination of the point of null charge (pH{sub PCN}) and density of surface sites (D{sub s}). The luminescence techniques were useful to determine the optimal point hydration of the zircon and for the quantification of the samarium, for that here intends the development of both analysis techniques. With the adjustment of the titration curves in the FITEQL 4 package the constants of surface acidity in the solid/liquid interface were determined. To the finish of this study it was corroborated that the zircon is a mineral that presents appropriate characteristics to be proposed as a contention barrier for the deep geologic confinement. With regard to the study of adsorption that one carries out the samarium retention it is superior to 90% under the described conditions. This investigation could also be applicable in the confinement of dangerous industrial residuals. (Author)

  14. Modeling the viscosity of silicate melts containing manganese oxide

    Directory of Open Access Journals (Sweden)

    Kim Wan-Yi

    2013-01-01

    Full Text Available Our recently developed model for the viscosity of silicate melts is applied to describe and predict the viscosities of oxide melts containing manganese oxide. The model requires three pairs of adjustable parameters that describe the viscosities in three systems: pure MnO, MnO-SiO2 and MnO-Al2O3-SiO2. The viscosity of other ternary and multicomponent silicate melts containing MnO is then predicted by the model without any additional adjustable model parameters. Experimental viscosity data are reviewed for melts formed by MnO with SiO2, Al2O3, CaO, MgO, PbO, Na2O and K2O. The deviation of the available experimental data from the viscosities predicted by the model is shown to be within experimental error limits.

  15. Thermochemistry of Rare Earth Silicates for Environmental Barrier Coatings

    Science.gov (United States)

    Costa, Gustavo; Jacobson, Nathan

    2015-01-01

    Rare earth silicates are promising candidates as environmental protective coatings (EBCs) for silica-forming ceramics and composites in combustion environments since they are predicted to have lower reactivity with the water vapor combustion products. The reactivity of rare earth silicates is assessed by the thermodynamic activity of the silica component which is best measured by Knudsen effusion mass spectrometry (KEMS). Here, we discuss a novel method based on a reducing agent to increase the partial pressure of SiO(g) which is then used to calculate thermodynamic activity of silica in Y2O3-SiO2 and Yb2O3-SiO2 systems. After the KEMS measurements, samples were probed by X-ray diffraction and their phase content was calculated from Rietveld refinement.

  16. The viscosity window of the silicate glass foam production

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng

    2017-01-01

    The production of silicate glass foam allows diverse resources and waste materials to be used in the production. Testing of such large palette of materials complicates and prolongs the optimisation process. Therefore, it is crucial to find a universal criterion for foaming silicate glass melts...... which can offer a practical starting point for the optimisation procedure. The melt viscosity might be the most important parameter for controlling the foaming process and the glass foam density. In this work, we attempt to define a viscosity range in which foaming of different glasses results...... in a maximum of foam expansion. The expansion maximum is obtained for different glasses (labware, E-glass, CRT panel, soda-lime-silica) by foaming with CaCO3 at isokom temperature and from literature data. In general, the viscosity window was found to be within 104–106 Pa s when foaming with MnO2 or metal...

  17. Participation of bacteria in weathering processes of silicates

    Directory of Open Access Journals (Sweden)

    Peter Javorský

    2005-11-01

    Full Text Available Biological processes presented by the metabolic activity of different species of bacteria adhered at the mineral surfaces are a part of the geochemical processes. These bacteria accelerate, by the production of organic acids into the minerals structural bonds, the leaching of elements and their subsequent and gradual transformation to the secondary minerals. Microbial destructions of silicates are studied in order to processing low-quality mineral raw-materials and the remediation of soils, sediments and waters contaminated by industrial pollutants. The samples of material, used in our research, were obtained at 9 deposits of non-metallic raw-materials in Slovakia. The sediment sample was taken from the area of Baikal Lake. The presence of microorganisms in the matrix most frequently was determined by a subsequent isolation of microorganisms and identification of bacterial species presented in the silicate matrix. The species of Bacillus and Pseudomonas genus were the common representative of the microorganisms.

  18. Enzyme-Mimicking properties of silicates and other minerals

    Science.gov (United States)

    Siegel, B. Z.; Siegel, S. M.

    The adsorptive and/or catalytic properties of clays, silicates in general, and other minerals are well known. More recently, their probable role in prebiotic syntheses of bio-organic compounds has become a matter of record. We demonstrate that, in addition to their role in de novo formation of important biomolecules, clays, micas, fibrous silicates and other minerals mimick the activities of contemporary enzymes including oxidases, esterases, phosphatases and glucosidases. The existence of such capabilities in substances likely to be represented on the surfaces of Earth-like planets may offer a challenge to the technology and design of remote life detection systems which must then distinguish between bona fide biological chemistry and mineral-base pseudometabolism. It also raises questions about the importance of mineral surfaces in post-mortem transformations of organic metabolites in our own biosphere.

  19. The solubility of gold in silicate melts: First results

    Science.gov (United States)

    Borisov, A.; Palme, H.; Spettel, B.

    1993-01-01

    The effects of oxygen fugacity and temperature on the solubility of Au in silicate melts were determined. Pd-Au alloys were equilibrated with silicate of anorthite-diopside eutectic composition at different T-fO2 conditions. The behavior of Au was found to be similar to that of Pd reported recently. Au solubilities for alloys with 30 to 40 at. percent Au decrease at 1400 C from 12 ppm in air to 160 ppb at a log fO2 = -8.7. The slope of the log(Me-solubility) vs. log(fO2) curve is close to 1/4 for Au and the simultaneously determined Pd suggesting a formal valence of Au and Pd of 1+. Near the IW buffer Pd and Au solubilities become even less dependent on fO2 perhaps reflecting the presence of some metallic Au and Pd.

  20. Conductivity studies of lithium zinc silicate glasses with varying ...

    Indian Academy of Sciences (India)

    WINTEC

    biomedical applications (McMillan 1979). The lithium– zinc–silicate (LZS) glass containing Li2O–ZnO–SiO2–. Na2O–B2O3–P2O5 has been used as the base glass for producing glass ceramics that are suitable for applications in hermetic glass–ceramic–to–metal seals with a variety of metals and alloys (Sharma et al 2004) ...

  1. Cracking phenomena in lithium-di-silicate glass ceramics

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Lithium-di-silicate glass ceramic (Li2O, SiO2) with uniformly oriented crystals was placed on a. Vickers indentation with extrusion axis horizontally parallel to the base axis. The material was rotated through. 0°– 90° and at each angle a 20 N load was applied to ascertain the crack path. It was observed that the crack.

  2. Cracking phenomena in lithium-di-silicate glass ceramics

    Indian Academy of Sciences (India)

    Lithium-di-silicate glass ceramic (Li2O, SiO2) with uniformly oriented crystals was placed on a Vickers indentation with extrusion axis horizontally parallel to the base axis. The material was rotated through 0°– 90° and at each angle a 20 N load was applied to ascertain the crack path. It was observed that the crack length ...

  3. Apatite: a new redox proxy for silicic magmas?

    OpenAIRE

    Miles, A.J.; Graham, C M; Hawkesworth, C.J.; Gillespie, M.R.; Hinton, R.W.; Bromiley, G.D.

    2014-01-01

    The oxidation states of magmas provide valuable information about the release and speciation of volatile elements during volcanic eruptions, metallogenesis, source rock compositions, open system magmatic processes, tectonic settings and potentially titanium (Ti) activity in chemical systems used for Ti-dependent geothermometers and geobarometers. In this paper we explore the use of Mn in apatite as an oxybarometer in intermediate and silicic igneous rocks. Increased Mn concentrations in apati...

  4. INORGANIC PHOSPHORS IN GLASS BASED ON LEAD SILICATE GLASSES

    Directory of Open Access Journals (Sweden)

    V. A. Aseev

    2014-09-01

    Full Text Available We created and synthesized luminescent composite of the "phosphor in glass" type, based on the lead-silicate matrix and fine-dispersed powder of cerium-activated yttrium-aluminum garnet crystal. Lead-silicate system (40SiO2- 20PbO-(40-x PbF2-xAlF3, x = 0-25 was chosen as the glassy matrix. Initial glass was reduced to powder (frit for "phosphor in glass" composite with a particle size about 50 µm. Glass frit and powder of commercial YAG:Ce3+ phosphor were mixed in a ratio of 30 to 70 (wt %. Then this composite was pressed in a tablet and sintered on a quartz substrate at 823 К for 30 minutes. Thus, the plane parallel sheet for composite of the "phosphor in glass" was obtained with a diameter equal to 10 mm. For the purpose to reduce the loss of light in the presence of dispersion at a glass-phosphor boundary, optimization of glass mixture was done by adjusting the refractive index. X-ray phase and spectral-luminescent analysis of the derived composite were done. The results of these studies showed that there was no degradation of YAG: Ce powder during sintering. Dependence of luminescence intensity from temperature in the range from room temperature to 473 К was studied. It was shown, that with the phosphor in glass usage thermal quenching of luminescence was reduced in comparison with the silicone. The model of white LED was created with the "phosphor in glass" composite based on lead-silicate glasses with low temperature of vitrifying. The derived LED emits white light with a color temperature of 4370 K, and the luminous efficiency is equal to 58 lm/W. The developed luminescent composite based on the lead-silicate matrix can be used for the production of high-power white light LED.

  5. Soda-Lime-Silicate Float Glass: A Property Comparison

    Science.gov (United States)

    2017-10-01

    Laboratory Soda-Lime-Silicate Float Glass: A Property Comparison by Andrew Cachiaras Science and Mathematics Academy at Aberdeen High School...Aberdeen, MD Luke Gilde Oak Ridge Institute for Science and Education, Oak Ridge, TN George D Quinn National Institute of Standards and...transparent armor systems. Thus, it is necessary to measure and compare the chemical composition as well as the physical and mechanical properties of

  6. SU-C-201-06: Utility of Quantitative 3D SPECT/CT Imaging in Patient Specific Internal Dosimetry of 153-Samarium with GATE Monte Carlo Package

    Energy Technology Data Exchange (ETDEWEB)

    Fallahpoor, M; Abbasi, M [Tehran University of Medical Sciences, Vali-Asr Hospital, Tehran, Tehran (Iran, Islamic Republic of); Sen, A [University of Houston, Houston, TX (United States); Parach, A [Shahid Sadoughi University of Medical Sciences, Yazd, Yazd (Iran, Islamic Republic of); Kalantari, F [UT Southwestern Medical Center, Dallas, TX (United States)

    2015-06-15

    Purpose: Patient-specific 3-dimensional (3D) internal dosimetry in targeted radionuclide therapy is essential for efficient treatment. Two major steps to achieve reliable results are: 1) generating quantitative 3D images of radionuclide distribution and attenuation coefficients and 2) using a reliable method for dose calculation based on activity and attenuation map. In this research, internal dosimetry for 153-Samarium (153-Sm) was done by SPECT-CT images coupled GATE Monte Carlo package for internal dosimetry. Methods: A 50 years old woman with bone metastases from breast cancer was prescribed 153-Sm treatment (Gamma: 103keV and beta: 0.81MeV). A SPECT/CT scan was performed with the Siemens Simbia-T scanner. SPECT and CT images were registered using default registration software. SPECT quantification was achieved by compensating for all image degrading factors including body attenuation, Compton scattering and collimator-detector response (CDR). Triple energy window method was used to estimate and eliminate the scattered photons. Iterative ordered-subsets expectation maximization (OSEM) with correction for attenuation and distance-dependent CDR was used for image reconstruction. Bilinear energy mapping is used to convert Hounsfield units in CT image to attenuation map. Organ borders were defined by the itk-SNAP toolkit segmentation on CT image. GATE was then used for internal dose calculation. The Specific Absorbed Fractions (SAFs) and S-values were reported as MIRD schema. Results: The results showed that the largest SAFs and S-values are in osseous organs as expected. S-value for lung is the highest after spine that can be important in 153-Sm therapy. Conclusion: We presented the utility of SPECT-CT images and Monte Carlo for patient-specific dosimetry as a reliable and accurate method. It has several advantages over template-based methods or simplified dose estimation methods. With advent of high speed computers, Monte Carlo can be used for treatment planning

  7. Fabrication of catalytically active nanocrystalline samarium (Sm)-doped cerium oxide (CeO2) thin films using electron beam evaporation

    Science.gov (United States)

    Kundu, Subrata; Sutradhar, Narottam; Thangamuthu, R.; Subramanian, B.; Panda, Asit Baran; Jayachandran, M.

    2012-08-01

    Samarium (Sm)-doped cerium oxide (CeO2) thin films were fabricated using electron beam evaporation technique. The synthesized films were deposited either on glass or ITO substrates and studied their nature by annealing at different temperatures. The optical properties and other morphological studies were done by UV-Vis, XRD, XPS, SEM, EDS, and FT-IR analysis. XRD and XPS analysis clearly confirm the presence of Sm in the ceria site. From the SEM study, it was found that after annealing at high temperature ( 300 or 500 °C), the particles size was reduced due to breakdown of large aggregates of particles which is also confirmed from UV-Vis, XPS, and XRD analyses. The FT-IR study proves the presence of -COO-, -OH, or ammonium group on the particles surface. The deposition of Sm-doped CeO2 nanomaterials was found more feasible on ITO substrate compared to that of glass substrate in terms of stability and depth of film thickness. The Sm-doped CeO2 nanomaterial acts as a re-usable catalyst for the reduction of organic dye molecules in the presence of NaBH4. The catalysis rate was compared by considering the electron transfer process during the reduction. The synthesized Sm-doped CeO2 thin films might find wide variety of applications in various emerging fields like solid oxide fuel cells (SOFCs), oxygen sensor or as catalyst in different types of organic and inorganic catalytic reactions. The fabrication process is very simple, straightforward, less time consuming, and cost effective.

  8. Fabrication of catalytically active nanocrystalline samarium (Sm)-doped cerium oxide (CeO{sub 2}) thin films using electron beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Subrata, E-mail: skundu@cecri.res.in [Council of Scientific and Industrial Research (CSIR), Electrochemical Materials Science (ECMS) Division, Central Electrochemical Research Institute - CECRI (India); Sutradhar, Narottam [G. B. Marg, Central Salt and Marine Chemical Research Institute - CSIR (India); Thangamuthu, R.; Subramanian, B. [Council of Scientific and Industrial Research (CSIR), Electrochemical Materials Science (ECMS) Division, Central Electrochemical Research Institute - CECRI (India); Panda, Asit Baran [G. B. Marg, Central Salt and Marine Chemical Research Institute (CSIR) (India); Jayachandran, M., E-mail: mjayam54@yahoo.com [Council of Scientific and Industrial Research (CSIR), Electrochemical Materials Science (ECMS) Division, Central Electrochemical Research Institute - CECRI (India)

    2012-08-15

    Samarium (Sm)-doped cerium oxide (CeO{sub 2}) thin films were fabricated using electron beam evaporation technique. The synthesized films were deposited either on glass or ITO substrates and studied their nature by annealing at different temperatures. The optical properties and other morphological studies were done by UV-Vis, XRD, XPS, SEM, EDS, and FT-IR analysis. XRD and XPS analysis clearly confirm the presence of Sm in the ceria site. From the SEM study, it was found that after annealing at high temperature ({approx}300 or 500 Degree-Sign C), the particles size was reduced due to breakdown of large aggregates of particles which is also confirmed from UV-Vis, XPS, and XRD analyses. The FT-IR study proves the presence of -COO-, -OH, or ammonium group on the particles surface. The deposition of Sm-doped CeO{sub 2} nanomaterials was found more feasible on ITO substrate compared to that of glass substrate in terms of stability and depth of film thickness. The Sm-doped CeO{sub 2} nanomaterial acts as a re-usable catalyst for the reduction of organic dye molecules in the presence of NaBH{sub 4}. The catalysis rate was compared by considering the electron transfer process during the reduction. The synthesized Sm-doped CeO{sub 2} thin films might find wide variety of applications in various emerging fields like solid oxide fuel cells (SOFCs), oxygen sensor or as catalyst in different types of organic and inorganic catalytic reactions. The fabrication process is very simple, straightforward, less time consuming, and cost effective.Graphical Abstract.

  9. Cleavage Energies of Modified Layered Silicates by Molecular Dynamics Simulation

    Science.gov (United States)

    Fu, Yao-Tsung; Heinz, Hendrik

    2009-03-01

    The cleavage energy of organically modified layered silicates indicates the thermodynamic propensity of exfoliation in polymer matrices. We find substantial cleavage energy differences upon variation in cation exchange capacity (CEC) (90 and 145 meq/100g), head groups (-NH3 and --NMe3), and chain length of the surfactants (C2 to C14) due to layering effects of the surfactants in the galleries using molecular dynamics simulation. Model systems of full atomistic detail are periodic in the xy plane, open in the z direction, are subjected to sheet separation starting at equilibrium distance. Overall, the cleavage energy, consistent with experimentally measured surface tensions and previous calculations for selected organoclays, shows complex fluctuations as a function of chain length and head group structure. Computed cleavage energies are in the range 25-50 mJ/m^2 for C2˜C14 (-NH3 headgroup) and 40-200 mJ/m^2 for C2˜C14 (--NMe3 headgroup) at two CEC layered silicates. The progression is not linear and related to the packing density of the interlayer of self-assembled surfactant chains and surface reconstruction of the modified layered silicates upon cleavage.

  10. Silicate dissolution boosts the CO2 concentrations in subduction fluids.

    Science.gov (United States)

    Tumiati, S; Tiraboschi, C; Sverjensky, D A; Pettke, T; Recchia, S; Ulmer, P; Miozzi, F; Poli, S

    2017-09-20

    Estimates of dissolved CO2 in subduction-zone fluids are based on thermodynamic models, relying on a very sparse experimental data base. Here, we present experimental data at 1-3 GPa, 800 °C, and ∆FMQ ≈ -0.5 for the volatiles and solute contents of graphite-saturated fluids in the systems COH, SiO2-COH ( + quartz/coesite) and MgO-SiO2-COH ( + forsterite and enstatite). The CO2 content of fluids interacting with silicates exceeds the amounts measured in the pure COH system by up to 30 mol%, as a consequence of a decrease in water activity probably associated with the formation of organic complexes containing Si-O-C and Si-O-Mg bonds. The interaction of deep aqueous fluids with silicates is a novel mechanism for controlling the composition of subduction COH fluids, promoting the deep CO2 transfer from the slab-mantle interface to the overlying mantle wedge, in particular where fluids are stable over melts.Current estimates of dissolved CO2 in subduction-zone fluids based on thermodynamic models rely on a very sparse experimental data base. Here, the authors show that experimental graphite-saturated COH fluids interacting with silicates at 1-3 GPa and 800 °C display unpredictably high CO2 contents.

  11. A Review: Fundamental Aspects of Silicate Mesoporous Materials

    Directory of Open Access Journals (Sweden)

    Zeid A. ALOthman

    2012-12-01

    Full Text Available Silicate mesoporous materials have received widespread interest because of their potential applications as supports for catalysis, separation, selective adsorption, novel functional materials, and use as hosts to confine guest molecules, due to their extremely high surface areas combined with large and uniform pore sizes. Over time a constant demand has developed for larger pores with well-defined pore structures. Silicate materials, with well-defined pore sizes of about 2.0–10.0 nm, surpass the pore-size constraint (<2.0 nm of microporous zeolites. They also possess extremely high surface areas (>700 m2 g−1 and narrow pore size distributions. Instead of using small organic molecules as templating compounds, as in the case of zeolites, long chain surfactant molecules were employed as the structure-directing agent during the synthesis of these highly ordered materials. The structure, composition, and pore size of these materials can be tailored during synthesis by variation of the reactant stoichiometry, the nature of the surfactant molecule, the auxiliary chemicals, the reaction conditions, or by post-synthesis functionalization techniques. This review focuses mainly on a concise overview of silicate mesoporous materials together with their applications. Perusal of the review will enable researchers to obtain succinct information about microporous and mesoporous materials.

  12. Development of Li+ alumino-silicate ion source

    Energy Technology Data Exchange (ETDEWEB)

    Roy, P.K.; Seidl, P.A.; Waldron, W.; Greenway, W.; Lidia, S.; Anders, A.; Kwan, J.

    2009-04-21

    To uniformly heat targets to electron-volt temperatures for the study of warm dense matter, one strategy is to deposit most of the ion energy at the peak of energy loss (dE/dx) with a low (E< 5 MeV) kinetic energy beam and a thin target[1]. Lower mass ions have a peak dE/dx at a lower kinetic energy. To this end, a small lithium (Li+) alumino-silicate source has been fabricated, and its emission limit has been measured. These surface ionization sources are heated to 1000-1150 C where they preferentially emit singly ionized alkali ions. Alumino-silicates sources of K+ and Cs+ have been used extensively in beam experiments, but there are additional challenges for the preparation of high-quality Li+ sources: There are tighter tolerances in preparing and sintering the alumino-silicate to the substrate to produce an emitter that gives uniform ion emission, sufficient current density and low beam emittance. We report on recent measurements ofhigh ( up to 35 mA/cm2) current density from a Li+ source. Ion species identification of possible contaminants is being verified with a Wien (E x B) filter, and via time-of-flight.

  13. Investigation of synthesized Be-bearing silicate glass as laboratory reference sample at X-ray electron probe microanalysis of silicates

    Science.gov (United States)

    Belozerova, Olga Yu.; Mikhailov, Mikhail A.; Demina, Tamara V.

    2017-01-01

    The article discusses estimates of the stability and homogeneity in Be-Mg-Al-silicate glass produced by the authors and its applicability as a laboratory reference sample for X-ray electron probe microanalysis (EPMA) of Be-bearing silicate matters: crystals and quenching melt (glasses), silicates and oxides. The results were obtained using Superprobe-733 and Superprobe JXA-8200 (JEOL Ltd, Japan) devices. The sample homogeneity was studied on macro (10-100 μm) and micro (1-10 μm) levels and was evaluated by the scheme of dispersion analysis. The applicability of Be-bearing silicate glass as a reference sample for Mg, Al, Si determinations was tested on the international certified reference glasses and laboratory reference samples of minerals with a known composition. The obtained experimental metrological characteristics correspond to the "applied geochemistry" type of analysis (second category) and suggest that Be-bearing silicate glass is appropriate as a laboratory reference sample for EPMA of Be-bearing silicate matters, silicates and oxides. Using Be-Mg-Al-silicate glass as a reference sample we obtained satisfactory data on the composition of both some minerals including cordierite and beryllium cordierite, beryllium indialite, beryl and metastable phases (chrysoberyl, compounds with structure of β-quartz and petalite).

  14. Confined Water in Layered Silicates: The Origin of Anomalous Thermal Expansion Behavior in Calcium-Silicate-Hydrates.

    Science.gov (United States)

    Krishnan, N M Anoop; Wang, Bu; Falzone, Gabriel; Le Pape, Yann; Neithalath, Narayanan; Pilon, Laurent; Bauchy, Mathieu; Sant, Gaurav

    2016-12-28

    Water, under conditions of nanoscale confinement, exhibits anomalous dynamics, and enhanced thermal deformations, which may be further enhanced when such water is in contact with hydrophilic surfaces. Such heightened thermal deformations of water could control the volume stability of hydrated materials containing nanoconfined structural water. Understanding and predicting the thermal deformation coefficient (TDC, often referred to as the CTE, coefficient of thermal expansion), which represents volume changes induced in materials under conditions of changing temperature, is of critical importance for hydrated solids including: hydrogels, biological tissues, and calcium silicate hydrates, as changes in their volume can result in stress development, and cracking. By pioneering atomistic simulations, we examine the physical origin of thermal expansion in calcium-silicate-hydrates (C-S-H), the binding agent in concrete that is formed by the reaction of cement with water. We report that the TDC of C-S-H shows a sudden increase when the CaO/SiO2 (molar ratio; abbreviated as Ca/Si) exceeds 1.5. This anomalous behavior arises from a notable increase in the confinement of water contained in the C-S-H's nanostructure. We identify that confinement is dictated by the topology of the C-S-H's atomic network. Taken together, the results suggest that thermal deformations of hydrated silicates can be altered by inducing compositional changes, which in turn alter the atomic topology and the resultant volume stability of the solids.

  15. Microstructure engineering of Portland cement pastes and mortars through addition of ultrafine layer silicates

    DEFF Research Database (Denmark)

    Lindgreen, Holger; Geiker, Mette Rica; Krøyer, Hanne

    2008-01-01

    Pozzolanic submicron-sized silica fume and the non-pozzolanic micron- and nano-sized layer silicates (clay minerals) kaolinite, smectite and palygorskite have been used as additives in Portland cement pastes and mortars. These layer silicates have different particle shape (needles and plates...... is that the cement paste structure and porosity can be engineered by addition of selected layer silicates having specific particle shapes and surface properties (e.g., charge and specific surface area). This seems to be due to the growth of calcium-silicate hydrates (C-S-H) on the clay particle surfaces......, and the nano-structure of the C-S-H depends on type of layer silicate. The effect of layer silicate addition is most pronounced for palygorskite and smectite having the largest surface area and negative charges on the particle surfaces. The cement pastes containing palygorskite and bentonite have...

  16. Pyrolytic Synthesis of Carbon Nanotubes from Sucrose on a Mesoporous Silicate

    Science.gov (United States)

    Abdel-Fattah, Tarek; Siochi, Mia; Crooks, Roy

    2005-01-01

    Multiwall carbon nanotubes were synthesized from sucrose by a pyrolytic technique using mesoporous MCM-41 silicate templates without transition metal catalysts. The Nanotubes were examined in the carbon/silicate composite and after dissolution of the silicate. High resolution transmission electron microscopy study of the multiwall nanotubes showed them to be 15 nm in diameter, 200 nm in length and close-ended. There was variation in crystallinity with some nanotubes showing disordered wall structures.

  17. Proton tunneling in low dimensional cesium silicate LDS-1

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, Hiroshi, E-mail: matsui-ldp@m.tohoku.ac.jp; Iwamoto, Kei [Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan); Mochizuki, Dai [Interdisciplinary Cluster for Cutting Edge Research, Center for Energy and Environmental Science, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567 (Japan); Osada, Shimon; Asakura, Yusuke [Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Kuroda, Kazuyuki [Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Kagami Memorial Research Institute for Material Science and Technology, Waseda University, Tokyo 169-0051 (Japan)

    2015-07-14

    In low dimensional cesium silicate LDS-1 (monoclinic phase of CsHSi{sub 2}O{sub 5}), anomalous infrared absorption bands observed at 93, 155, 1210, and 1220 cm{sup −1} are assigned to the vibrational mode of protons, which contribute to the strong hydrogen bonding between terminal oxygen atoms of silicate chain (O–O distance = 2.45 Å). The integrated absorbance (oscillator strength) for those modes is drastically enhanced at low temperatures. The analysis of integrated absorbance employing two different anharmonic double-minimum potentials makes clear that proton tunneling through the potential barrier yields an energy splitting of the ground state. The absorption bands at 93 and 155 cm{sup −1}, which correspond to the different vibrational modes of protons, are attributed to the optical transition between the splitting levels (excitation from the ground state (n = 0) to the first excited state (n = 1)). Moreover, the absorption bands at 1210 and 1220 cm{sup −1} are identified as the optical transition from the ground state (n = 0) to the third excited state (n = 3). Weak Coulomb interactions in between the adjacent protons generate two types of vibrational modes: symmetric mode (93 and 1210 cm{sup −1}) and asymmetric mode (155 and 1220 cm{sup −1}). The broad absorption at 100–600 cm{sup −1} reveals an emergence of collective mode due to the vibration of silicate chain coupled not only with the local oscillation of Cs{sup +} but also with the proton oscillation relevant to the second excited state (n = 2)

  18. SILICATES ON IAPETUS FROM CASSINI’S COMPOSITE INFRARED SPECTROMETER

    Energy Technology Data Exchange (ETDEWEB)

    Young, Cindy L.; Wray, James J. [School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA (United States); Clark, Roger N. [Planetary Science Institute, Tucson, AZ (United States); Spencer, John R. [Southwest Research Institute, Boulder, CO (United States); Jennings, Donald E. [NASA Goddard Space Flight Center, Greenbelt, MD (United States); Hand, Kevin P.; Carlson, Robert W. [Jet Propulsion Laboratory, Pasadena, CA (United States); Poston, Michael J. [Caltech, Pasadena, CA (United States)

    2015-10-01

    We present the first spectral features obtained from Cassini’s Composite Infrared Spectrometer (CIRS) for any icy moon. The spectral region covered by CIRS focal planes (FP) 3 and 4 is rich in emissivity features, but previous studies at these wavelengths have been limited by low signal-to-noise ratios (S/Ns) for individual spectra. Our approach is to average CIRS FP3 spectra to increase the S/N and use emissivity spectra to constrain the composition of the dark material on Iapetus. We find an emissivity feature at ∼855 cm{sup −1} and a possible doublet at 660 and 690 cm{sup −1} that do not correspond to any known instrument artifacts. We attribute the 855 cm{sup −1} feature to fine-grained silicates, similar to those found in dust on Mars and in meteorites, which are nearly featureless at shorter wavelengths. Silicates on the dark terrains of Saturn’s icy moons have been suspected for decades, but there have been no definitive detections until now. Serpentines reported in the literature at ambient temperature and pressure have features near 855 and 660 cm{sup −1}. However, peaks can shift depending on temperature and pressure, so measurements at Iapetus-like conditions are necessary for more positive feature identifications. As a first investigation, we measured muscovite at 125 K in a vacuum and found that this spectrum does match the emissivity feature near 855 cm{sup −1} and the location of the doublet. Further measurements are needed to robustly identify a specific silicate, which would provide clues regarding the origin and implications of the dark material.

  19. Light-cured Tricalcium Silicate Toxicity to the Dental Pulp.

    Science.gov (United States)

    Jeanneau, Charlotte; Laurent, Patrick; Rombouts, Charlotte; Giraud, Thomas; About, Imad

    2017-12-01

    Numerous studies reported dentin bridge formation after pulp capping with tricalcium silicates. By contrast, pulp capping with resins leads to pulp toxicity and inflammation. Hybrid materials made up of tricalcium silicates and resins have also been developed to be used in direct pulp capping. This work was designed to study the consequences of adding resins to tricalcium silicates by investigating TheraCal (BISCO, Lançon De Provence, France) and Biodentine (Septodont, Saint Maur des Fosses, France) interactions with the dental pulp. Media conditioned with the biomaterials were used to analyze pulp fibroblast proliferation using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) test and proinflammatory cytokine interleukin 8 (IL-8) secretion using the enzyme-linked immunosorbent assay. The effects of conditioned media on dentin sialoprotein (DSP) and nestin expression by dental pulp stem cells (DPSCs) were investigated by immunofluorescence. The materials' interactions with the vital pulp were investigated using the entire tooth culture model. TheraCal-conditioned media significantly decreased pulp fibroblast proliferation, whereas no effect was observed with Biodentine. When DPSCs were cultured with Biodentine-conditioned media, immunofluorescence showed an increased expression of DSP and nestin. This expression was lower with TheraCal, which significantly induced proinflammatory IL-8 release both in cultured fibroblasts and entire tooth cultures. This IL-8 secretion increase was not observed with Biodentine. Entire tooth culture histology showed a higher mineralization with Biodentine, whereas significant tissue disorganization was observed with TheraCal. Within the limits of these preclinical results, resin-containing TheraCal cannot be recommended for direct pulp capping. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  20. Low- 18O silicic magmas: why are they so rare?

    Science.gov (United States)

    Balsley, Steven D.; Gregory, Robert T.

    1998-10-01

    Low- 18O silicic magmas are reported from only a small number of localities (e.g., Yellowstone and Iceland), yet petrologic evidence points to upper crustal assimilation coupled with fractional crystallization (AFC) during magma genesis for nearly all silicic magmas. The rarity of low- 18O magmas in intracontinental caldera settings is remarkable given the evidence of intense low- 18O meteoric hydrothermal alteration in the subvolcanic remnants of larger caldera systems. In the Platoro caldera complex, regional ignimbrites (150-1000 km 3) have plagioclase δ 18O values of 6.8±0.1‰, whereas the Middle Tuff, a small-volume (est. 50-100 km 3) post-caldera collapse pyroclastic sequence, has plagioclase δ 18O values between 5.5 and 6.8‰. On average, the plagioclase phenocrysts from the Middle Tuff are depleted by only 0.3‰ relative to those in the regional tuffs. At Yellowstone, small-volume post-caldera collapse intracaldera rhyolites are up to 5.5‰ depleted relative to the regional ignimbrites. Two important differences between the Middle Tuff and the Yellowstone low- 18O rhyolites elucidate the problem. Middle Tuff magmas reached water saturation and erupted explosively, whereas most of the low- 18O Yellowstone rhyolites erupted effusively as domes or flows, and are nearly devoid of hydrous phenocrysts. Comparing the two eruptive types indicates that assimilation of low- 18O material, combined with fractional crystallization, drives silicic melts to water oversaturation. Water saturated magmas either erupt explosively or quench as subsurface porphyries before the magmatic 18O can be dramatically lowered. Partial melting of low- 18O subvolcanic rocks by near-anhydrous magmas at Yellowstone produced small-volume, low- 18O magmas directly, thereby circumventing the water saturation barrier encountered through normal AFC processes.

  1. Low-(18)O Silicic Magmas: Why Are They So Rare?

    Energy Technology Data Exchange (ETDEWEB)

    Balsley, S.D.; Gregory, R.T.

    1998-10-15

    LOW-180 silicic magmas are reported from only a small number of localities (e.g., Yellowstone and Iceland), yet petrologic evidence points to upper crustal assimilation coupled with fractional crystallization (AFC) during magma genesis for nearly all silicic magmas. The rarity of 10W-l `O magmas in intracontinental caldera settings is remarkable given the evidence of intense 10W-l*O meteoric hydrothermal alteration in the subvolcanic remnants of larger caldera systems. In the Platoro caldera complex, regional ignimbrites (150-1000 km3) have plagioclase 6180 values of 6.8 + 0.1%., whereas the Middle Tuff, a small-volume (est. 50-100 km3) post-caldera collapse pyroclastic sequence, has plagioclase 8]80 values between 5.5 and 6.8%o. On average, the plagioclase phenocrysts from the Middle Tuff are depleted by only 0.3%0 relative to those in the regional tuffs. At Yellowstone, small-volume post-caldera collapse intracaldera rhyolites are up to 5.5%o depleted relative to the regional ignimbrites. Two important differences between the Middle Tuff and the Yellowstone 10W-180 rhyolites elucidate the problem. Middle Tuff magmas reached water saturation and erupted explosively, whereas most of the 10W-l 80 Yellowstone rhyolites erupted effusively as domes or flows, and are nearly devoid of hydrous phenocrysts. Comparing the two eruptive types indicates that assimilation of 10W-180 material, combined with fractional crystallization, drives silicic melts to water oversaturation. Water saturated magmas either erupt explosively or quench as subsurface porphyrins bejiire the magmatic 180 can be dramatically lowered. Partial melting of low- 180 subvolcanic rocks by near-anhydrous magmas at Yellowstone produced small- volume, 10W-180 magmas directly, thereby circumventing the water saturation barrier encountered through normal AFC processes.

  2. Synthesis of magnesium silicate from wheat husk ash: Effects of parameters on structural and surface properties

    OpenAIRE

    Pinar Terzioglu; Sevil Yucel

    2012-01-01

    In the present study, magnesium silicate was produced by using wheat husk ash. Wheat husk was burned at 600 °C to obtain an amorphous ash structure, and the ash was processed with sodium hydroxide solution with heat to extract silica. Sodium silicate solution and magnesium salts were used to synthesize magnesium silicate. The present study investigates effects of the feeding rate on magnesium silicate production (0.6 mL/min, 35 mL/min, 70 mL/min), the type of magnesium salt (MgSO4 • 7H2O or M...

  3. Studies on Thermal Degradation Behavior of Siliceous Agriculture Waste (Rice Husk, Wheat Husk and Bagasse)

    National Research Council Canada - National Science Library

    Syed H. Javed; Umair Aslam; Mohsin Kazmi; Masooma Rustam; Sheema Riaz; Zahid Munir

    2015-01-01

    Various siliceous agriculture waste (SAW) such as rice husk, wheat husk and bagasse have been investigated to study their thermal degradation behavior using Thermogravimetric Analyzer (TGA) technique...

  4. High-temperature silicate volcanism on Jupiter's moon Io

    Science.gov (United States)

    McEwen, A.S.; Keszthelyi, L.; Spencer, J.R.; Schubert, G.; Matson, D.L.; Lopes-Gautier, R.; Klaasen, K.P.; Johnson, T.V.; Head, J.W.; Geissler, P.; Fagents, S.; Davies, A.G.; Carr, M.H.; Breneman, H.H.; Belton, M.J.S.

    1998-01-01

    Infrared wavelength observations of Io by the Galileo spacecraft show that at last 12 different vents are erupting lavas that are probably hotter than the highest temperature basaltic eruptions on Earth today. In at least one case, the eruption near Pillan Patea, two independent instruments on Galileo show that the lava temperature must have exceeded 1700 kelvin and may have reached 2000 kelvin. The most likely explanation is that these lavas are ultramafic (magnesium-rich) silicates, and this idea is supported by the tentative identification of magnesium-rich orthopyroxene in lava flows associated with thse high-temperature hot spots.

  5. Alkali-metal silicate binders and methods of manufacture

    Science.gov (United States)

    Schutt, J. B. (Inventor)

    1979-01-01

    A paint binder is described which uses a potassium or sodium silicate dispersion having a silicon dioxide to alkali-metal oxide mol ratio of from 4.8:1 to 6.0:1. The binder exhibits stability during both manufacture and storage. The process of making the binder is predictable and repeatable and the binder may be made with inexpensive components. The high mol ratio is achieved with the inclusion of a silicon dioxide hydrogel. The binder, which also employs a silicone, is in the final form of a hydrogel sol.

  6. Activity composition relationships in silicate melts. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Glazner, A.F.

    1990-12-31

    Equipment progress include furnace construction and electron microprobe installation. The following studies are underway: phase equilibria along basalt-rhyolite mixing line (olivine crystallization from natural silicic andensites, distribution of Fe and Mg between olivine and liquid, dist. of Ca and Na between plagioclase and liquid), enthalpy-composition relations in magmas (bulk heat capacity of alkali basalt), density model for magma ascent and contamination, thermobarometry in igneous systems (olivine/plagioclase phenocryst growth in Quat. basalt), high-pressure phase equilibria of alkali basalt, basalt-quartz mixing experiments, phase equilibria of East African basalts, and granitic minerals in mafic magma. (DLC)

  7. Calcium silicate hydrates: Solid and liquid phase composition

    OpenAIRE

    Lothenbach Barbara; Nonat André

    2015-01-01

    © 2015 Elsevier Ltd. This paper presents a review on the relationship between the composition the structure and the solution in which calcium silicate hydrate (C S H) is equilibrated. The silica chain length in C S H increases with the silicon concentration and the calcium content in the interlayer space with the calcium concentrations. Sodium and potassium are taken up in the interlayer space preferentially at low calcium concentrations and thus by low Ca/Si C S H. Aluminium uptake in C S H ...

  8. Space Weathering of Silicate Asteroids: An Observational Investigation

    Science.gov (United States)

    MacLennan, Eric M.; Emery, Joshua; Lindsay, Sean S.

    2017-10-01

    Solar wind exposure and micrometeoroid bombardment are known to cause mineralogical changes in the upper few microns of silicate grains (by forming amorphous “composition” rims with embedded nano-phase Fe0). These processes, jointly called space weathering (SW), affect the light-scattering properties and subsequently the geometric albedo and spectral parameters (spectral slope and band depth). Earth’s Moon exhibits the well known “lunar-style” of SW: albedo decrease, spectral slope increase, and absorption band suppression. However, space mission images of (243) Ida and (433) Eros suggest that different SW “styles” exist among the silicate-bearing (olivine and pyroxene) S-complex asteroids, which exhibit diagnostic absorption features near 1 & 2 μm. While Eros generally shows only albedo differences between younger and older locations, Ida’s surface only shows changes in spectral slope and band depth. It is not clear if these SW styles are unique to Ida and Eros or if they can be observed throughout the entire asteroid population.We hypothesize that the SW styles seen on Eros and Ida also exist on other asteroid surfaces. Additionally, we hypothesize that increased solar wind exposure, smaller regolith particles, higher olivine abundance, and older asteroid surfaces will increase the observed degree of SW. Our dataset includes publicly available Visible (0.4-0.8 μm) and Near Infrared (~0.7-2.5 μm) reflectance spectra of silicate-bearing asteroids (those with 1 & 2 μm bands) from the PDS and the SMASS, S3OS2 and MIT-UH-IRTF spectral surveys. We have also conducted a spectral survey with the IRTF/SpeX targeting 52 silicate asteroids for which we have constraints for regolith grain sizes from interpretation of thermal-IR data. The relevant band parameters to SW and to interpreting mineralogical properties are calculated using the band analysis code, SARA. Geometric albedos are calculated using thermal-IR data from WISE/NEOWISE. Using these derived

  9. Infrared spectroscopy and hydrogen isotope geochemistry of hydrous silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Epstein, S.; Stolper, E.

    1992-01-01

    The focus of this project is the combined appication of infrared spectroscopy and stable isotope geochemistry to the study of hydrogen-bearing species dissolved in silicate melts and glasses. We are conducting laboratory experiments aimed at determining the fractionation of D and H between melt species (OH and H{sub 2}O) and hydrous vapor and the diffusivities of these species in glasses and melts. Knowledge of these parameters is critical to understanding the behavior of hydrogen isotopes during igneous processes and hydrothermal processes. These results also could be valuable in application of glass technology to development of nuclear waste disposal strategies.

  10. Tin in silicate glasses: structure, thermodynamics and kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Verena; Ksenofontov, Vadim [Johannes Gutenberg-Universitaet Mainz, Institut fuer Anorganische Chemie und Analytische Chemie (Germany); Aigner, Maria-Louisa; Pfeiffer, Thomas; Sprenger, Dirk [Schott AG Mainz (Germany); Felser, Claudia, E-mail: felser@uni-mainz.de [Johannes Gutenberg-Universitaet Mainz, Institut fuer Anorganische Chemie und Analytische Chemie (Germany)

    2008-04-15

    In this work Moessbauer spectroscopy is used to investigate the oxidation states and structures of tin in silicate glasses. Thermal treatment of the glasses in atmospheres with varying oxygen partial pressure leads to the simultaneous appearance of reduction and diffusion. Experiments with varying treatment time give the opportunity to study diffusion and reduction processes in detail. Comparison of the hyperfine parameters of reference materials with measured parameter provides information about the local surroundings of the tin atoms. An octahedral surrounding for Sn{sup 4+} is presumed, while Sn{sup 2+} and three oxygen atoms form a tetrahedral coordination.

  11. Infrared Spectroscopy and Stable Isotope Geochemistry of Hydrous Silicate Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Stolper, Edward

    2007-03-05

    The focus of this DOE-funded project has been the study of volatile components in magmas and the atmosphere. Over the twenty-one year period of this project, we have used experimental petrology and stable isotope geochemistry to study the behavior and properties of volatile components dissolved in silicate minerals and melts and glasses. More recently, we have also studied the concentration and isotopic composition of CO2 in the atmosphere, especially in relation to air quality issues in the Los Angeles basin.

  12. Calorimetric signature of structural heterogeneity in a ternary silicate glass

    DEFF Research Database (Denmark)

    Zhang, Yanfei; Yang, G.; Yue, Yuanzheng

    2013-01-01

    We investigate the structural heterogeneity in a silicate glass by hyperquenching–annealing–calorimetry approach. The results show a striking phenomenon: two separated sub-Tg relaxation peaks appear on the calorimetric curve of the hyperquenched CaO–MgO–SiO2 glass, implying the existence of two...... distinct structural domains of higher and lower potential energies, respectively. The higher energy domains in nanoscale are so unstable that they become ordered during hyperquenching. This is verified by the high-resolution transmission electron microscopy image exhibiting nanoordered domains in the glass...

  13. Competitive Adsorption of Arsenite and Silicic Acid on Goethite

    OpenAIRE

    Luxton, Todd Peter

    2002-01-01

    The adsorption behavior of silicic acid and arsenite alone and competitively on goethite over a broad pH range (3-11) at environmentally relevant concentrations was investigated utilizing pH adsorption data and zeta potential measurements. Both addition scenarios (Si before As(III) and As(III) before Si) were examined. The results of the adsorption experiments and zeta potential measurements were then used to model the single ion and competitive ion adsorption on goethite with the CD-MUSIC ...

  14. Crystal structure of monoclinic samarium and cubic europium sesquioxides and bound coherent neutron scattering lengths of the isotopes {sup 154}Sm and {sup 153}Eu

    Energy Technology Data Exchange (ETDEWEB)

    Kohlmann, Holger [Leipzig Univ. (Germany). Inst. of Inorganic Chemistry; Hein, Christina; Kautenburger, Ralf [Saarland Univ., Saarbruecken (Germany). Inorganic Solid State Chemistry; Hansen, Thomas C.; Ritter, Clemens [Institut Laue-Langevin, Grenoble (France); Doyle, Stephen [Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen (Germany). Inst. for Synchrotron Radiation (ISS)

    2016-11-01

    The crystal structures of monoclinic samarium and cubic europium sesquioxide, Sm{sub 2}O{sub 3} and Eu{sub 2}O{sub 3}, were reinvestigated by powder diffraction methods (laboratory X-ray, synchrotron, neutron). Rietveld analysis yields more precise structural parameters than previously known, especially for oxygen atoms. Interatomic distances d(Sm-O) in Sm{sub 2}O{sub 3} range from 226.3(4) to 275.9(2) pm [average 241.6(3) pm] for the monoclinic B type Sm{sub 2}O{sub 3} [space group C2/m, a = 1418.04(3) pm, b = 362.660(7) pm, c = 885.48(2) pm, β = 100.028(1) ], d(Eu-O) in Eu{sub 2}O{sub 3} from 229.9(2) to 238.8(2) pm for the cubic bixbyite (C) type [space group Ia anti 3, a = 1086.87(1) pm]. Neutron diffraction at 50 K and 2 K did not show any sign for magnetic ordering in Sm{sub 2}O{sub 3}. Isotopically enriched {sup 154}Sm{sub 2}O{sub 3} and {sup 153}Eu{sub 2}O{sub 3} were used for the neutron diffraction work because of the enormous absorption cross section of the natural isotopic mixtures for thermal neutrons. The isotopic purity was determined by inductively coupled plasma - mass spectrometry to be 98.9% for {sup 154}Sm and 99.8% for {sup 153}Eu. Advanced analysis of the neutron diffraction data suggest that the bound coherent scattering lengths of {sup 154}Sm and {sup 153}Eu need to be revised. We tentatively propose b{sub c}({sup 154}Sm) = 8.97(6) fm and b{sub c}({sup 153}Eu) = 8.85(3) fm for a neutron wavelength of 186.6 pm to be better values for these isotopes, showing up to 8% deviation from accepted literature values. It is shown that inaccurate scattering lengths may result in severe problems in crystal structure refinements causing erroneous structural details such as occupation parameters, which might be critically linked to physical properties like superconductivity in multinary oxides.

  15. NMR study of hydrated calcium silicates; Etude par RMN de la structure des silicates de calcium hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Klur, I

    1996-02-26

    Radioactive wastes storage methods are developed by the CEA. As cements are important materials as well for hours living radioisotopes than for years living radioisotopes, a better knowledge of this material will allow to anticipate its behaviour and to obtain safer storage methods. The structure of calcium silicates (C-S-H) (main constituent of cements) have then been determined in this thesis by nuclear magnetic resonance. This method has allow to explain in structural terms, the different calcium rates that can be measured in the C-S-H too. (O.M.) 101 refs.

  16. Enhanced bioactivity of glass ionomer cement by incorporating calcium silicates.

    Science.gov (United States)

    Chen, Song; Cai, Yixiao; Engqvist, Håkan; Xia, Wei

    2016-01-01

    Glass ionomer cements (GIC) are known as a non-bioactive dental cement. During setting the GIC have an acidic pH, driven by the acrylic acid component. It is a challenge to make GIC alkaline without disturbing its mechanical properties. One strategy was to add slowly reacting systems with an alkaline pH. The aim of the present study is to investigate the possibility of forming a bioactive dental material based on the combination of glass ionomer cement and calcium silicates. Two types of GIC were used as control. Wollastonite (CS also denoted β-CaSiO3) or Mineral Trioxide Aggregate (MTA) was incorporated into the 2 types of GIC. The material formulations' setting time, compressive strength, pH and bioactivity were compared between modified GIC and GIC control. Apatite crystals were found on the surfaces of the modified cements but not on the control GIC. The compressive strength of the cement remained with the addition of 20% calcium silicate or 20% MTA after one day immersion. In addition, the compressive strength of GIC modified with 20% MTA had been increased during the 14 d immersion (p < 0 .05).

  17. Anionic silicate organic frameworks constructed from hexacoordinate silicon centres

    Science.gov (United States)

    Roeser, Jérôme; Prill, Dragica; Bojdys, Michael J.; Fayon, Pierre; Trewin, Abbie; Fitch, Andrew N.; Schmidt, Martin U.; Thomas, Arne

    2017-10-01

    Crystalline frameworks composed of hexacoordinate silicon species have thus far only been observed in a few high pressure silicate phases. By implementing reversible Si-O chemistry for the crystallization of covalent organic frameworks, we demonstrate the simple one-pot synthesis of silicate organic frameworks based on octahedral dianionic SiO6 building units. Clear evidence of the hexacoordinate environment around the silicon atoms is given by 29Si nuclear magnetic resonance analysis. Characterization by high-resolution powder X-ray diffraction, density functional theory calculation and analysis of the pair-distribution function showed that those anionic frameworks—M2[Si(C16H10O4)1.5], where M = Li, Na, K and C16H10O4 is 9,10-dimethylanthracene-2,3,6,7-tetraolate—crystallize as two-dimensional hexagonal layers stabilized in a fully eclipsed stacking arrangement with pronounced disorder in the stacking direction. Permanent microporosity with high surface area (up to 1,276 m2 g-1) was evidenced by gas-sorption measurements. The negatively charged backbone balanced with extra-framework cations and the permanent microporosity are characteristics that are shared with zeolites.

  18. Enhanced bioactivity of glass ionomer cement by incorporating calcium silicates

    Science.gov (United States)

    Chen, Song; Cai, Yixiao; Engqvist, Håkan; Xia, Wei

    2016-01-01

    Abstract Glass ionomer cements (GIC) are known as a non-bioactive dental cement. During setting the GIC have an acidic pH, driven by the acrylic acid component. It is a challenge to make GIC alkaline without disturbing its mechanical properties. One strategy was to add slowly reacting systems with an alkaline pH. The aim of the present study is to investigate the possibility of forming a bioactive dental material based on the combination of glass ionomer cement and calcium silicates. Two types of GIC were used as control. Wollastonite (CS also denoted β-CaSiO3) or Mineral Trioxide Aggregate (MTA) was incorporated into the 2 types of GIC. The material formulations’ setting time, compressive strength, pH and bioactivity were compared between modified GIC and GIC control. Apatite crystals were found on the surfaces of the modified cements but not on the control GIC. The compressive strength of the cement remained with the addition of 20% calcium silicate or 20% MTA after one day immersion. In addition, the compressive strength of GIC modified with 20% MTA had been increased during the 14 d immersion (p < 0 .05). PMID:26787304

  19. Novel understanding of calcium silicate hydrate from dilute hydration

    KAUST Repository

    Zhang, Lina

    2017-05-13

    The perspective of calcium silicate hydrate (C-S-H) is still confronting various debates due to its intrinsic complicated structure and properties after decades of studies. In this study, hydration at dilute suspension of w/s equaling to 10 was conducted for tricalcium silicate (C3S) to interpret long-term hydration process and investigate the formation, structure and properties of C-S-H. Based on results from XRD, IR, SEM, NMR and so forth, loose and dense clusters of C-S-H with analogous C/S ratio were obtained along with the corresponding chemical formulae proposed as Ca5Si4O13∙6.2H2O. Crystalline structure inside C-S-H was observed by TEM, which was allocated at the foil-like proportion as well as the edge of wrinkles of the product. The long-term hydration process of C3S in dilute suspension could be sketchily described as migration of calcium hydroxide and in-situ growth of C-S-H with equilibrium silicon in aqueous solution relatively constant and calcium varied.

  20. Anionic silicate organic frameworks constructed from hexacoordinate silicon centres.

    Science.gov (United States)

    Roeser, Jérôme; Prill, Dragica; Bojdys, Michael J; Fayon, Pierre; Trewin, Abbie; Fitch, Andrew N; Schmidt, Martin U; Thomas, Arne

    2017-10-01

    Crystalline frameworks composed of hexacoordinate silicon species have thus far only been observed in a few high pressure silicate phases. By implementing reversible Si-O chemistry for the crystallization of covalent organic frameworks, we demonstrate the simple one-pot synthesis of silicate organic frameworks based on octahedral dianionic SiO6 building units. Clear evidence of the hexacoordinate environment around the silicon atoms is given by (29)Si nuclear magnetic resonance analysis. Characterization by high-resolution powder X-ray diffraction, density functional theory calculation and analysis of the pair-distribution function showed that those anionic frameworks-M2[Si(C16H10O4)1.5], where M = Li, Na, K and C16H10O4 is 9,10-dimethylanthracene-2,3,6,7-tetraolate-crystallize as two-dimensional hexagonal layers stabilized in a fully eclipsed stacking arrangement with pronounced disorder in the stacking direction. Permanent microporosity with high surface area (up to 1,276 m(2) g(-1)) was evidenced by gas-sorption measurements. The negatively charged backbone balanced with extra-framework cations and the permanent microporosity are characteristics that are shared with zeolites.

  1. The structure of alkali silicate gel by total scattering methods

    KAUST Repository

    Benmore, C.J.

    2010-06-01

    The structure of the alkali silicate gel (ASR) collected from the galleries of Furnas Dam in Brazil was determined by a pair distribution function (PDF) analysis of high energy X-ray diffraction data. Since this method is relatively new to concrete structure analysis a detailed introduction on the PDF method is given for glassy SiO2. The bulk amorphous structure of the dam material is confirmed as no Bragg peaks are observed in the scattered intensity. The real space results show that the local structure of the amorphous material is similar to kanemite (KHSi2O5:3H2O) however the long range layer structure of the crystal is broken up in the amorphous state, so that ordering only persists of the length scale of a few polyhedra. The silicate layer structure is a much more disordered than predicted by molecular dynamics models. The X-ray results are consistent with the molecular dynamics model of Kirkpatrick et al. (2005) [1] which predicts that most of the water resides in pores within the amorphous network rather than in layers. The total scattering data provide a rigorous basis against which other models may also be tested. © 2010.

  2. Evidence of yttrium silicate inclusions in YSZ-porcelain veneers.

    Science.gov (United States)

    Stoner, Brian R; Griggs, Jason A; Neidigh, John; Piascik, Jeffrey R

    2014-04-01

    This report introduces the discovery of crystalline defects that can form in the porcelain veneering layer when in contact with yttria-stabilized zirconia (YSZ). The focus was on dental prostheses and understanding the defects that form in the YSZ/porcelain system; however the data reported herein may have broader implications toward the use and stability of YSZ-based ceramics in general. Specimens were cut from fully sintered YSZ plates and veneering porcelain was applied (veneer. Local EDAX (SEM) was performed in the regions of visible inclusions and showed significant increases in yttrium concentration. TEM specimens also showed apparent inclusions in the porcelain and selected area electron diffraction was performed on these regions and found the inclusions to be crystalline and identified as either yttrium-silicate (Y2 SiO5 ) or yttrium-disilicate (Y2 Si2 O7 ). Micro-CT data showed that yttrium-silicate precipitates were distributed throughout the thickness of the porcelain veneer. Future studies are needed to determine whether many of the premature failures associated with this materials system may be the result of crystalline flaws that form as a result of high temperature yttrium diffusion near the surfaces of YSZ. © 2013 Wiley Periodicals, Inc.

  3. In vitro bioactivity of a tricalcium silicate cement

    Energy Technology Data Exchange (ETDEWEB)

    Morejon-Alonso, L.; Bareiro, O.; Santos, L.A. dos, E-mail: loreley.morejon@ufrgs.b [Universidade Federal do Rio Grande do Sul (UFRG), Porto Alegre, RS (Brazil). Escola de Engenharia. Dep. de Materiais; Carrodeguas R, Garcia [Consejo Superior de Investigaciones Cientificas (CSIC), Madrid (Spain). Inst. de Ceramica y Vidrio. Dept. de Ceramica

    2009-07-01

    Tricalcium silicate is the major constituent of Portland cement and the responsible for their mechanical strength at early stages. In order to be used as and additive of conventional calcium phosphate cement (CPC), in vitro bioactivity of a calcium silicate cement (CSC) after soaking in simulated body fluid (SBF) for 14 days was study. The cement was obtained by mixing Ca{sub 3}SiO{sub 5}, obtained by sol-gel process, and a Na{sub 2}HPO{sub 4} solution. The morphological and structural changes of the material before and after soaking were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed the formation of a layer of a Hydroxyapatite (HA) onto the CSC cement after soaking for 1h in SBF that became denser with the increase of soaking time. The study suggests that Ca{sub 3}SiO{sub 5} would be an effective additive to improve the bioactivity and long term strength of conventional CPC. (author)

  4. Interaction of dispersed polyvynil acetate with silicate in finishing materials

    Directory of Open Access Journals (Sweden)

    Runova, R. F.

    1996-12-01

    Full Text Available This article focuses on the processes of interaction between calcium silicate hydrates and dispersed polyvinyl acetate in tight films with the aim of developing compounds meant for restoration and finishing works. The basis of this development relies on the concept concerning the determining role of the crystal-chemical factor of the silicate phase in the formation of organic-mineral compounds of increased durability. The characteristics of dispersed calcium silicate hydrates are portrayed. The preparation conditions, accounting for the synthesis of the product of submicrocrystalline structure, conforming with the stoichiometry CaO∙SiO2 =0.8-2.0 have been determined. The interaction has been studied for compounds achieved by mixing ingredients in a rapid whirling mixer, and subjected to hardening at T=20+2 T. With the aid of XRD, DTA and Infra-Red Spectrometry methods the formation process of the sophisticated polymer silicate phase in the material was observed for a period of 90 days. The properties of the film were investigated and its high resistance against the influence of external factors was established. On this basis a conclusion concerning the quite high effectiveness of substituting portland cement with dispersed calcium silicate hydrate in polymer cement compounds has been made. White colour and other various special properties determine the suitability for repair and finishing works on facades of buildings.

    Este artículo está orientado a estudiar los procesos de interacción entre los silicatos cálcicos hidratados y el acetato de polivinilo disperso en capas impermeables, con el objeto de desarrollar compuestos destinados para la restauración. El fundamento de estos estudios es determinar el papel que los factores cristaloquímicos de las fases silicato tienen en la formación de compuestos órganominerales de elevada durabilidad. Se han descrito las características de los silicatos cálcicos hidratados

  5. Influence of silicate on the transport of bacteria in quartz sand and iron mineral-coated sand.

    Science.gov (United States)

    Dong, Zhe; Yang, Haiyan; Wu, Dan; Ni, Jinren; Kim, Hyunjung; Tong, Meiping

    2014-11-01

    The influence of silicate on the transport and deposition of bacteria (Escherichia coli) in packed porous media were examined at a constant 20 mM ionic strength with different silicate concentrations (from 0 to 1 mM) at pH 7. Transport experiments were performed in two types of representative porous media, both bare quartz sand and iron mineral-coated quartz sand. In bare quartz sand, the breakthrough plateaus in the presence of silicate in suspensions were lower and the corresponding retained profiles were higher than those without silicate ions, indicating that the presence of silicate in suspensions decreased cell transport in bare quartz sand. Moreover, the decrease of bacteria transport in quartz sand induced by silicate was more pronounced with increasing silicate concentrations from 0 to 1 mM. However, when EPS was removed from cell surfaces, the presence of silicate in cell suspensions (with different concentrations) did not affect the transport behavior of bacteria in quartz sand. The interaction of silicate with EPS on cell surfaces negatively decreased the zeta potentials of bacteria, resulting in the decreased cell transport in bare quartz sand when silicate was copresent in bacteria suspensions. In contrast, the presence of silicate in suspensions increased cell transport in iron mineral-coated sand. Silicate ions competed with bacteria for the adsorption sites on mineral-coated sand, contributing to the increased cell transport in mineral-coated sand with silicate present in cell suspensions. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. A study of redox kinetic in silicate melt; Etude cinetique des reactions d'oxydoreduction dans les silicates

    Energy Technology Data Exchange (ETDEWEB)

    Magnien, V

    2005-12-15

    The aim of this thesis is to understand better iron redox reactions and mechanisms in silicate glasses and melts. Particular interest has been paid to the influence of temperature and chemical composition. For this purpose, the influence of alkali element content, iron content and network formers on the kinetics of redox reactions has been determined through XANES and Raman spectroscopy experiments performed either near the glass transition or above the liquidus temperature. As a complement, electrical conductivity and RBS spectroscopy experiments have been made to characterize the diffusivity of the species that transport electrical charges and the reaction morphology, respectively. Temperature and composition variations can induce changes in the dominating redox mechanism. At a given temperature, the parameters that exert the strongest influence on redox mechanisms are the presence or lack of divalent cations and the existing decoupling between the mobility of network former and modifier elements. Near Tg, the diffusion of divalent cations, when present in the melt, controls the kinetics of iron redox reactions along with a flux of electron holes. Composition, through the degree of polymerization and the silicate network structure, influences the kinetics and the nature of the involved cations, but not the mechanisms of the reaction. Without alkaline earth elements, the kinetics of redox reactions are controlled by the diffusion of oxygen species. With increasing temperatures, the diffusivities of all ionic species tend to become similar. The decoupling between ionic fluxes then is reduced so that several mechanisms become kinetically equivalent and can thus coexist. (author)

  7. Steam based conversion coating on AA6060 alloy: Effect of sodium silicate chemistry and corrosion performance

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Bordo, Kirill; Tabrizian, Naja

    2017-01-01

    Surface treatment of aluminium alloy AA6060 using an industrially applicable pilot steam jet system with and without silicate chemistry has been investigated. Treatment using steam alone and steam with silicate, resulted in an oxide layer formation with thickness ∼425 nm and ∼160 nm, respectively...

  8. Sodium Silicate Behavior in Porous Media Applied for In-Depth Profile Modifications

    Directory of Open Access Journals (Sweden)

    Hossein A. Akhlaghi Amiri

    2014-03-01

    Full Text Available This paper addresses alkaline sodium silicate (Na-silicate behavior in porous media. One of the advantages of the Na-silicate system is its water-like injectivity during the placement stage. Mixing Na-silicate with saline water results in metal silicate precipitation as well as immediate gelation. This work demonstrated that low salinity water (LSW, sea water diluted 25 times could be used as a pre-flush in flooding operations. A water override phenomenon was observed during gel formation which is caused by gravity segregation. Dynamic adsorption tests in the sand-packed tubes showed inconsiderable adsorbed silicon density (about 8.5 × 10−10 kg/cm3 for a solution with 33 mg/L silicon content, which is less than the estimated mono-layer adsorption density of 1.4 × 10−8 kg/cm3. Na-silicate enhanced water sweep efficiency after application in a dual-permeability sand-pack system, without leak off into the oil-bearing low permeability (LP zone. Field-scale numerical sensitivity studies in a layered reservoir demonstrated that higher permeability and viscosity contrasts and lower vertical/horizontal permeability ratio result in lower Na-silicate leakoff into the matrix. The length of the mixing zone between reservoir water and the injected Na-silicate solution, which is formed by low salinity pre-flush, acts as a buffer zone.

  9. Crystal Structure and Chemical Composition of a Presolar Silicate from the Queen Elizabeth Range 99177 Meteorite

    Science.gov (United States)

    Nguyen, A. N.; Keller, L. P.; Rahman, Z.; Messenger, S.

    2013-01-01

    Mineral characterization of presolar silicate grains, the most abundant stardust phase, has provided valuable information about the formation conditions in circumstellar environments and in super-nova (SN) outflows. Spectroscopic observations of dust around evolved stars suggest a majority of amor-phous, Mg-rich olivine grains, but crystalline silicates, most of which are pyroxene, have also been observed [1]. The chemical compositions of hundreds of presolar silicates have been determined by Auger spectroscopy and reveal high Fe contents and nonstoichiometric compositions intermediate to olivine and pyroxene [2-6]. The unexpectedly high Fe contents can partly be attributed to secondary alteration on the meteorite parent bodies, as some grains have Fe isotopic anomalies from their parent stellar source [7]. Only about 35 presolar silicates have been studied for their mineral structures and chemical compositions by transmission electron microscopy (TEM). These grains display a wide range of compositions and structures, including crystalline forsterite, crystalline pyroxene, nanocrystalline grains, and a majority of amorphous nonstoichiometric grains. Most of these grains were identified in the primitive Acfer 094 meteorite. Presolar silicates from this meteorite show a wide range of Fe-contents, suggestive of secondary processing on the meteorite parent body. The CR chondrite QUE 99177 has not suffered as much alteration [8] and displays the highest presolar silicate abundance to date among carbonaceous chondrites [3, 6]. However, no mineralogical studies of presolar silicates from this meteorite have been performed. Here we examine the mineralogy of a presolar silicate from QUE 99177.

  10. Facile synthesis of magnetic hierarchical copper silicate hollow nanotubes for efficient adsorption and removal of hemoglobin.

    Science.gov (United States)

    Zhang, Min; Wang, Baoyu; Zhang, Yanwei; Li, Weizhen; Gan, Wenjun; Xu, Jingli

    2016-01-21

    This study reports the fabrication of magnetic copper silicate hierarchical hollow nanotubes, which are featured by a tailored complex wall structure and high surface area. Moreover, they exhibit excellent performance as an easily recycled adsorbent for protein separation. Particularly, this strategy can be extended as a general method to prepare other magnetic metal silicate hollow nanotubes.

  11. FT-IR and 29 Si-NMR for evaluating aluminium silicate precursors for geopolymers

    NARCIS (Netherlands)

    Valcke, S.L.A.; Pipilikaki, P.; Fischer, H.R.; Verkuijlen, M.H.W.; Eck, E.R.H.

    2014-01-01

    Geopolymers are systems of inorganic binders that can be used for sustainable, cementless concrete and are formed by alkali activation of an aluminium–silicate precursor (often secondary resources like fly ash or slag). The type of aluminium– silicate precursor and its potential variations within

  12. New estimates of silicate weathering rates and their uncertainties in global rivers

    Science.gov (United States)

    Moon, Seulgi; Chamberlain, C. P.; Hilley, G. E.

    2014-06-01

    This study estimated the catchment- and global-scale weathering rates of silicate rocks from global rivers using global compilation datasets from the GEMS/Water and HYBAM. These datasets include both time-series of chemical concentrations of major elements and synchronous discharge. Using these datasets, we first examined the sources of uncertainties in catchment and global silicate weathering rates. Then, we proposed future sampling strategies and geochemical analyses to estimate accurate silicate weathering rates in global rivers and to reduce uncertainties in their estimates. For catchment silicate weathering rates, we considered uncertainties due to sampling frequency and variability in river discharge, concentration, and attribution of weathering to different chemical sources. Our results showed that uncertainties in catchment-scale silicate weathering rates were due mostly to the variations in discharge and cation fractions from silicate substrates. To calculate unbiased silicate weathering rates accounting for the variations from discharge and concentrations, we suggest that at least 10 and preferably ∼40 temporal chemical data points with synchronous discharge from each river are necessary. For the global silicate weathering rate, we examined uncertainties from infrequent sampling within an individual river, the extrapolation from limited rivers to a global flux, and the inverse model selections for source differentiation. For this weathering rate, we found that the main uncertainty came from the extrapolation to the global flux and the model configurations of source differentiation methods. This suggests that to reduce the uncertainties in the global silicate weathering rates, coverage of synchronous datasets of river chemistry and discharge to rivers from tectonically active regions and volcanic provinces must be extended, and catchment-specific silicate end-members for those rivers must be characterized. With current available synchronous datasets, we

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

    DEFF Research Database (Denmark)

    Haastrup, Sonja; Yu, Donghong; Yue, Yuanzheng

    2017-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Rajan Choudhary

    2015-06-01

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

  15. Pilot study on binding of bovine salivary proteins to grit silicates and plant phytoliths.

    Science.gov (United States)

    Mau, Marcus; M Kaiser, Thomas; Südekum, Karl-Heinz

    2013-06-01

    Mostly fed with grass in fresh or conserved form, cattle and other livestock have to cope with silicate defence bodies from plants (phytoliths) and environmental silicates (grit), which abrade tooth enamel and could additionally interact with various salivary proteins. To detect potential candidates for silicate-binding proteins, bovine whole saliva was incubated with grass-derived phytoliths and silicates. Interactions of salivary proteins with pulverized bovine dental enamel and dentine were additionally analysed. After intense washing, the powder fractions were loaded onto 1D-polyacrylamide gels, most prominent adhesive protein bands were cut out and proteins were identified by mass spectrometry within three independent replicates. All materials were mainly bound by bovine odorant-binding protein, bovine salivary protein 30×10(3) and carbonic anhydrase VI. The phytolith/silicate fraction showed additional stronger interaction with haemoglobin β and lactoperoxidase. Conceivably, the binding of these proteins to the surfaces may contribute to biological processes occurring on them.

  16. Apatite: a new redox proxy for silicic magmas?

    Science.gov (United States)

    Miles, Andrew; Graham, Colin; Hawkesworth, Chris; Gillespie, Martin; Bromiley, Geoff; Hinton, Richard

    2015-04-01

    The oxidation states of magmas provide valuable information about the release and speciation of volatile elements during volcanic eruptions, metallogenesis, source rock compositions, open system magmatic processes, tectonic settings and potentially titanium (Ti) activity in chemical systems used for Ti-dependent geothermometers and geobarometers. In this presentation we explore the use of Mn in apatite as an oxybarometer in intermediate and silicic igneous rocks. Increased Mn concentrations in apatite in granitic rocks from the zoned Criffell granitic pluton (southern Scotland) correlate with decreasing Fe2O3 (Fe3+) and Mn in the whole-rock and likely reflect increased Mn2+/Mn3+and greater compatibility of Mn2+ relative to Mn3+ in apatite under reduced conditions. Fe3+/Fe2+ ratios in biotites have previously been used to calculate oxygen fugacities (fO2) in the outer zone granodiorites and inner zone granites where redox conditions have been shown to change from close to the magnetite-hematite buffer to close to the nickel-nickel oxide buffer respectively[1]. This trend is apparent in apatite Mn concentrations from a range of intermediate to silicic volcanic rocks that exhibit varying redox states and are shown to vary linearly and negatively with log fO2, such that logfO2=-0.0022(±0.0003)Mn(ppm)-9.75(±0.46) Variations in the Mn concentration of apatites appear to be largely independent of differences in the Mn concentration of the melt. Apatite Mn concentrations may therefore provide an independent oxybarometer that is amenable to experimental calibration, with major relevance to studies on detrital mineral suites, particularly those containing a record of early Earth redox conditions, and on the climatic impact of historic volcanic eruptions[2]. [1] Stephens, W. E., Whitley, J. E., Thirlwall, M. F. and Halliday, A. N. (1985) The Criffell zoned pluton: correlated behaviour of rare earth element abundances with isotopic systems. Contributions to Mineralogy and

  17. Role of organically modified layered silicate both as an active interfacial modifier and nanofiller for immiscible polymer blends.

    CSIR Research Space (South Africa)

    Ray, SS

    2007-05-01

    Full Text Available ) revealed efficient mixing of the polymers in the presence of organically modified layered silicate. X-ray diffraction (XRD) patterns and transmission electron microscopic (TEM) observations showed that silicate layers were either intercalated or exfoliated...

  18. Highly CO2-Tolerant Cathode for Intermediate-Temperature Solid Oxide Fuel Cells: Samarium-Doped Ceria-Protected SrCo0.85Ta0.15O3-δ Hybrid.

    Science.gov (United States)

    Li, Mengran; Zhou, Wei; Zhu, Zhonghua

    2017-01-25

    Susceptibility to CO2 is one of the major challenges for the long-term stability of the alkaline-earth-containing cathodes for intermediate-temperature solid oxide fuel cells. To alleviate the adverse effects from CO2, we incorporated samarium-stabilized ceria (SDC) into a SrCo0.85Ta0.15O3-δ (SCT15) cathode by either mechanical mixing or a wet impregnation method and evaluated their cathode performance stability in the presence of a gas mixture of 10% CO2, 21% O2, and 69% N2. We observed that the CO2 tolerance of the hybrid cathode outperforms the pure SCT15 cathode by over 5 times at 550 °C. This significant enhancement is likely attributable to the low CO2 adsorption and reactivity of the SDC protective layer, which are demonstrated through thermogravimetric analysis, energy-dispersive spectroscopy, and electrical conductivity study.

  19. Effects of Silicate, Phosphate, and Calcium on the Stability of Aldopentoses

    Science.gov (United States)

    Nitta, Sakiko; Furukawa, Yoshihiro; Kakegawa, Takeshi

    2016-06-01

    Ribose is an important constituent of RNA: ribose connects RNA bases and forms a strand of sugar phosphates. Accumulation of ribose on prebiotic Earth was difficult because of its low stability. Improvement in the yield of ribose by the introduction of borate or silicate in a formose-like reaction has been proposed. The effects of borates have been further analyzed and confirmed in subsequent studies. Nonetheless, the effects of silicates and phosphates remain unclear. In the present study, we incubated aldopentoses in a highly alkaline aqueous solution at a moderate temperature to determine the effects of silicate or phosphate on the degradation rates of ribose and its isomeric aldopentoses. The formation of a complex of silicate (or phosphate) with ribose was also analyzed in experiments with 29Si and 31P nuclear magnetic resonance (NMR). We found that silicate or phosphate complexes of ribose were not detectable under our experimental conditions. The stability of ribose and lyxose improved after addition of 40-fold molar excess (relative to a pentose) of sodium silicate or sodium phosphate to the alkaline solution. The stability was not improved further when an 80-fold molar excess of sodium silicate or sodium phosphate was added. Calcium was removed from these solutions by precipitation of calcium salts. The drop in Ca2+ concentration might have improved the stability of ribose and lyxose, which are susceptible to aldol addition. The improvement of ribose stability by the removal of Ca2+ and by addition of silicate or phosphate was far smaller than the improvement by borate. Furthermore, all aldopentoses showed similar stability in silicate- and phosphate-containing solutions. These results clearly show that selective stabilization of ribose by borate cannot be replaced by the effects of silicate or phosphate; this finding points to the importance of borate in prebiotic RNA formation.

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

    Science.gov (United States)

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

    2014-06-01

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

  1. Soil microbial response to waste potassium silicate drilling fluid.

    Science.gov (United States)

    Yao, Linjun; Naeth, M Anne; Jobson, Allen

    2015-03-01

    Potassium silicate drilling fluids (PSDF) are a waste product of the oil and gas industry with potential for use in land reclamation. Few studies have examined the influence of PSDF on abundance and composition of soil bacteria and fungi. Soils from three representative locations for PSDF application in Alberta, Canada, with clay loam, loam and sand textures were studied with applications of unused, used once and used twice PSDF. For all three soils, applying ≥40 m3/ha of used PSDF significantly affected the existing soil microbial flora. No microbiota was detected in unused PSDF without soil. Adding used PSDF to soil significantly increased total fungal and aerobic bacterial colony forming units in dilution plate counts, and anaerobic denitrifying bacteria numbers in serial growth experiments. Used PSDF altered bacterial and fungal colony forming unit ratios of all three soils. Copyright © 2015. Published by Elsevier B.V.

  2. Laboratory Evidence for Microbially Mediated Silicate Mineral Dissolution in Nature

    Energy Technology Data Exchange (ETDEWEB)

    Ullman, W. J.; Kirchman, D. L.; Welch, S. A.; Vandevivere, P.

    1996-01-01

    Bacteria may potentially enhance or inhibit silicate mineral dissolution in nature by a variety of mechanisms. In the laboratory, some microbial metabolites enhanced dissolution rates by a factor of ten above the expected proton-promoted rate by an additional ligand-promoted mechanism focused principally at Al sites at the mineral surface. In investigations with bacteria, it was found that organic acids are produced in organic-rich/nutrient-poor cultures, resulting in increased mineral dissolution rates compared to abiotic controls. Alginate and poly-aspartate inhibited dissolution rates either by a reduction in surface reactivity or reactive surface area (or both). Bacteria may also influence dissolution rates by creating and maintaining microenvironments where metabolite concentrations are higher than in the bulk solution.

  3. About Fundamental Problems of Hydrosphere and Silicate Karst

    Directory of Open Access Journals (Sweden)

    A. Ya. Gayev

    2017-09-01

    Full Text Available Rationale of hydrosphere model with two regions of supply and discharge reveals regularities of ground water formation reflecting the special features of system water – rock – gas – living material and character of interaction of hydrosphere with the other spheres of the Earth. It is necessary to concentrate the development of endogenous hy-drogeology fundamentals with the study of silicate karst on investigation of “white and black smokers”, the structure and isotope composition of water in different phase condi-tions, and on modeling of situation in hydrometagenese zone. It will support the development of geotechnology and providing the humanity with mineral and energetic resources in future.

  4. Is plant ecology more siliceous than we realise?

    Science.gov (United States)

    Cooke, Julia; Leishman, Michelle R

    2011-02-01

    Although silicon occurs in all plants, it is an element that is largely overlooked by many plant ecologists and most plant-related research on silicon comes from agronomy, archaeology, palaeontology and biogeochemistry. Plant silicon has many functions, acting biochemically as silicic acid and physically as amorphous silica. It contributes to cell and plant strength and enables plants to respond adaptively to environmental stresses. Consequently, plant silicon can increase plant fitness in many fundamental aspects of ecology, including plant-herbivore interactions, light interception, pathogen resistance and alleviation of abiotic stresses. Here, we provide an ecological perspective to research outcomes from diverse disciplines, showing that silicon is an important element in plant ecology that is worthy of greater attention. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. Intergranular area microalloyed aluminium-silicate ceramics fractal analysis

    Directory of Open Access Journals (Sweden)

    Purenović J.

    2013-01-01

    Full Text Available Porous aluminium-silicate ceramics, modified by alloying with magnesium and microalloying with alluminium belongs to a group of advanced multifunctional ceramics materials. This multiphase solid-solid system has predominantly amorphous microstructure and micro morphology. Intergranular and interphase areas are very complex, because they represent areas, where numbered processes and interactions take place, making new boundaries and regions with fractal nature. Fractal analysis of intergranular microstructure has included determination of ceramic grain fractal dimension by using Richardson method. Considering the fractal nature of intergranular contacts, it is possible to establish correlation between material electrical properties and fractal analysis, as a tool for future correlation with microstructure characterization. [Projekat Ministarstva nauke Republike Srbije, br. ON 172057 i br. III 45012

  6. Stylolites, porosity, depositional texture, and silicates in chalk facies sediments

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Borre, Mai K.

    2007-01-01

    Comparison of chalk on the Ontong Java Plateau and chalk in the Central North Sea indicates that, whereas pressure dissolution is controlled by effective burial stress, pore-filling cementation is controlled by temperature. Effective burial stress is caused by the weight of all overlying water...... and sediments as counteracted by the pressure in the pore fluid, so the regional overpressure in the Central North Sea is one reason why the two localities have different relationships between temperature and effective burial stress. In the chalk of the Ontong Java Plateau the onset of calcite-silicate pressure...... equilibrated to quartz before the onset of pressure dissolution and thus, in this case, dissolution and precipitation of calcite have no lag. This temperature versus effective burial stress induced difference in diagenetic history is of particular relevance when exploring for hydrocarbons in normally pressured...

  7. Tribological properties of silicate materials on nano and microscale

    Energy Technology Data Exchange (ETDEWEB)

    Tordjeman, Ph., E-mail: philippe.tordjeman@imft.fr [Universite de Toulouse-CNRS, Institut de Mecanique des Fluides de Toulouse UMR 5502, Allee Camille Soula, F-31400 Toulouse (France); Morel, N. [Laboratoire IES, Groupe Micro et RheoAcoustique, UMR CNRS 5214, Universite Montpellier 2, CC 082, Pl. E. Bataillon, 34095 Montpellier Cedex 05 (France); Ramonda, M. [Laboratoire de Microscopie a Champ Proche, LMCP, Universite Montpellier 2, CC 082, Pl. E. Bataillon, 34095 Montpellier Cedex 05 (France)

    2009-05-15

    We studied the friction properties of four model silicate materials at the nanoscale and microscale. From nanotribology, we characterized the tribological properties at single asperity contact scale and from microtribology, we characterized the tribological properties at multi asperity contact scale. First, for each material we measured chemical composition by XPS, Young's modulus by acoustical microscopy and roughness {sigma} by atomic force microscopy (AFM). Second, we measured the nanofriction coefficients with an AFM and the microfriction coefficients with a ball probe tribometer, for three hardnesses of the ball probe. We identified one friction mechanism at the nanoscale (sliding friction) and two friction mechanisms at the microscale (sliding friction and yielding friction). Comparison of the nano and microfriction coefficients at the same sliding friction regime shown, that the tribological properties of these materials didn't depend on roughness.

  8. High-dose dosimetry using natural silicate minerals

    Energy Technology Data Exchange (ETDEWEB)

    Carmo, Lucas S. do; Mendes, Leticia, E-mail: isatiro@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Watanabe, Shigueo; Rao, Gundu; Lucas, Natasha; Sato, Karina, E-mail: lacifid@if.usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Fisica. Departamento de Fisica Nuclear; Barbosa, Renata F., E-mail: profcelta@hotmail.com [Universidade Federal de Sao Paulo (UNIFESP), Santos, SP (Brazil). Departamento de Ciencias do Mar

    2015-07-01

    In the present study, certain natural silicate minerals such as aquamarine (AB), morganite (PB), goshenite (WB), white jadeite (JW), green jadeite (JG), pink tourmaline (PT) and two varieties of jadeite-like quartz, denoted here by JQ1 and JQ2, were investigated using the thermoluminescence technique to evaluate their potential for use as very-high- and high-dose dosimeters. These minerals respond to high doses of γ-rays of up to 1000 kGy and often to very high doses of up to 3000 kGy. The TL response of these minerals may be considered to be satisfactory for applications in high-dose dosimetry. Investigations of electron paramagnetic resonance and optically stimulated luminescence dosimetry are in progress. (author)

  9. Luminescent solar concentrators using uranyl-doped silicate glasses

    Science.gov (United States)

    Folcher, G.; Keller, N.; Paris, J.

    1984-09-01

    The effect of the uranium concentration on the performance of uranyl-doped glass used in solar concentrators was examined experimentally. Na-Ca silicate glass and UO3 additive were prepared at 1250 C, cooled to 600 C, annealed at 700 C, and cooled to ambient for the tests. Light absorption was proportional to uranium content up to a 2 percent concentration. A doped-glass test cell filled with a fluoresceine solution and irradiated at 337 nm and 420 nm with laser light was monitored to measure the luminescent lifetimes of the uranyl ions. A 380 microsec half-lifetime was determined, along with a quantum yield that varied from 0.5 at 1 percent uranyl concentration to 0.3 at a 5 percent concentration. The quantum efficiencies could be attained with 1 cm thick glass with existing manufacturing technologies, and thinner glass with further developments.

  10. A-thermal elastic behavior of silicate glasses

    Science.gov (United States)

    Rabia, Mohammed Kamel; Degioanni, Simon; Martinet, Christine; Le Brusq, Jacques; Champagnon, Bernard; Vouagner, Dominique

    2016-02-01

    Depending on the composition of silicate glasses, their elastic moduli can increase or decrease as function of the temperature. Studying the Brillouin frequency shift of these glasses versus temperature allows the a-thermal composition corresponding to an intermediate glass to be determined. In an intermediate glass, the elastic moduli are independent of the temperature over a large temperature range. For sodium alumino-silicate glasses, the a-thermal composition is close to the albite glass (NaAlSi3O8). The structural origin of this property is studied by in situ high temperature Raman scattering. The structure of the intermediate albite glass and of silica are compared at different temperatures between room temperature and 600 °C. When the temperature increases, it is shown that the high frequency shift of the main band at 440 cm-1 in silica is a consequence of the cristobalite-like alpha-beta transformation of 6-membered rings. This effect is stronger in silica than bond elongation (anharmonic effects). As a consequence, the elastic moduli of silica increase as the temperature increases. In the albite glass, the substitution of 25% of Si4+ ions by Al3+ and Na+ ions decreases the proportion of SiO2 6-membered rings responsible for the silica anomaly. The effects of the silica anomaly balance the anharmonicity in albite glass and give rise to an intermediate a-thermal glass. Different networks, formers or modifiers, can be added to produce different a-thermal glasses with useful mechanical or chemical properties.

  11. Evaluation of apatite silicates as solid oxide fuel cell electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Marrero-Lopez, D. [Dpto. de Fisica Aplicada I, Laboratorio de Materiales y Superficies (Unidad Asociada al C.S.I.C.), Universidad de Malaga, 29071 Malaga (Spain); Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Martin-Sedeno, M.C.; Aranda, M.A.G. [Dpto. de Quimica Inorganica, Universidad Malaga, 29071 Malaga (Spain); Pena-Martinez, J. [Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Instituto de Energias Renovables, Parque Tecnologico, Universidad de Castilla La Mancha, 02006 Albacete (Spain); Ruiz-Morales, J.C.; Nunez, P. [Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Ramos-Barrado, J.R. [Dpto. de Fisica Aplicada I, Laboratorio de Materiales y Superficies (Unidad Asociada al C.S.I.C.), Universidad de Malaga, 29071 Malaga (Spain)

    2010-05-01

    Apatite-type silicates have been considered as promising electrolytes for Solid Oxide Fuel Cells (SOFC); however studies on the potential use of these materials in SOFC devices have received relatively little attention. The lanthanum silicate with composition La{sub 10}Si{sub 5.5}Al{sub 0.5}O{sub 26.75} has been evaluated as electrolyte with the electrode materials commonly used in SOFC, i.e. manganite, ferrite and cobaltite as cathode materials and NiO-CGO composite, chromium-manganite and Sr{sub 2}MgMoO{sub 6} as anode materials. Chemical compatibility, area-specific resistance and fuel cell studies have been performed. X-ray powder diffraction (XRPD) analysis did not reveal any trace of reaction products between the apatite electrolyte and most of the aforementioned electrode materials. However, the area-specific polarisation resistance (ASR) of these electrodes in contact with apatite electrolyte increased significantly with the sintering temperature, indicating reactivity at the electrolyte/electrode interface. On the other hand, the ASR values are significantly improved using a ceria buffer layer between the electrolyte and electrode materials to prevent reactivity. Maximum power densities of 195 and 65 mWcm{sup -2} were obtained at 850 and 700 C, respectively in H{sub 2} fuel, using an 1 mm-thick electrolyte, a NiO-Ce{sub 0.8}Gd{sub 0.2}O{sub 1.9} composite as anode and La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} as cathode materials. This fuel cell was tested for 100 h in 5%H{sub 2}-Ar atmosphere showing stable performance. (author)

  12. Low Velocity Sphere Impact of a Soda Lime Silicate Glass

    Energy Technology Data Exchange (ETDEWEB)

    Wereszczak, Andrew A [ORNL; Fox, Ethan E [ORNL; Morrissey, Timothy G [ORNL; Vuono, Daniel J [ORNL

    2011-10-01

    This report summarizes TARDEC-sponsored work at Oak Ridge National Laboratory (ORNL) during the FY11 involving low velocity (< 30 m/s or < 65 mph) ball impact testing of Starphire soda lime silicate glass. The intent was to better understand low velocity impact response in the Starphire for sphere densities that bracketed that of rock. Five sphere materials were used: borosilicate glass, soda-lime silicate glass, steel, silicon nitride, and alumina. A gas gun was fabricated to produce controlled velocity delivery of the spheres against Starphire tile targets. Minimum impact velocities to initiate fracture in the Starphire were measured and interpreted in context to the kinetic energy of impact and the elastic property mismatch between the any of the five sphere-Starphire-target combinations. The primary observations from this low velocity (< 30 m/s or < 65 mph) testing were: (1) Frictional effects contribute to fracture initiation. (2) Spheres with a lower elastic modulus require less force to initiate fracture in the Starphire than spheres with a higher elastic modulus. (3) Contact-induced fracture did not initiate in the Starphire SLS for impact kinetic energies < 150 mJ. Fracture sometimes initiated or kinetic energies between {approx} 150-1100 mJ; however, it tended to occur when lower elastic modulus spheres were impacting it. Contact-induced fracture would always occur for impact energies > 1100 mJ. (4) The force necessary to initiate contact-induced fracture is higher under dynamic or impact conditions than it is under quasi-static indentation conditions. (5) Among the five used sphere materials, silicon nitride was the closest match to 'rock' in terms of both density and (probably) elastic modulus.

  13. In vitro cytotoxicity of calcium silicate-containing endodontic sealers.

    Science.gov (United States)

    Zhou, Hui-min; Du, Tian-feng; Shen, Ya; Wang, Zhe-jun; Zheng, Yu-feng; Haapasalo, Markus

    2015-01-01

    The cytotoxicity of 2 novel calcium silicate-containing endodontic sealers to human gingival fibroblasts was studied. EndoSequence BC (Brasseler, Savannah, GA), MTA Fillapex (Angelus Indústria de Produtos Odontológicos S/A, Londrina, PR, Brazil) and a control sealer (AH Plus; Dentsply DeTrey GmbH, Konstanz, Germany) were evaluated. Human gingival fibroblasts were incubated for 3 days both with the extracts from fresh and set materials in culture medium and cultured on the surface of the set materials in Dulbecco-modified Eagle medium. Fibroblasts cultured in Dulbecco-modified Eagle medium were used as a control group. Cytotoxicity was evaluated by flow cytometry, and the adhesion of the fibroblasts to the surface of the set materials was assessed using scanning electron microscopy. The data of cell cytotoxicity were analyzed statistically using a 1-way analysis of variance test at a significance level of P extracts from BC Sealer showed higher viabilities at all extract concentrations than cells incubated with extracts from freshly mixed AH Plus and fresh and set MTA Fillapex, esspecially for the high extract concentrations (1:2 and 1:8 dilutions). Extracts from set MTA Fillapex of 2 weeks and older were more cytotoxic than extracts from freshly mixed and 1-week-old cement. With extract concentrations of 1:32 and lower, MTA Fillapex was no longer cytotoxic. After setting, AH Plus was no longer cytotoxic, and the fibroblast cells grew on set AH Plus equally as well as on BC Sealer. BC Sealer and MTA Fillapex, the 2 calcium silicate-containing endodontic sealers, exhibited different cytotoxicity to human gingival fibroblasts. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  14. Modified tricalcium silicate cement formulations with added zirconium oxide.

    Science.gov (United States)

    Li, Xin; Yoshihara, Kumiko; De Munck, Jan; Cokic, Stevan; Pongprueksa, Pong; Putzeys, Eveline; Pedano, Mariano; Chen, Zhi; Van Landuyt, Kirsten; Van Meerbeek, Bart

    2017-04-01

    This study aims to investigate the effect of modifying tricalcium silicate (TCS) cements on three key properties by adding ZrO 2 . TCS powders were prepared by adding ZrO 2 at six different concentrations. The powders were mixed with 1 M CaCl 2 solution at a 3:1 weight ratio. Biodentine (contains 5 wt.% ZrO 2 ) served as control. To evaluate the potential effect on mechanical properties, the mini-fracture toughness (mini-FT) was measured. Regarding bioactivity, Ca release was assessed using ICP-AES. The component distribution within the cement matrix was evaluated by Feg-SEM/EPMA. Cytotoxicity was assessed using an XTT assay. Adding ZrO 2 to TCS did not alter the mini-FT (p = 0.52), which remained in range of that of Biodentine (p = 0.31). Ca release from TSC cements was slightly lower than that from Biodentine at 1 day (p > 0.05). After 1 week, Ca release from TCS 30 and TCS 50 increased to a level that was significantly higher than that from Biodentine (p  0.05). EPMA revealed a more even distribution of ZrO 2 within the TCS cements. Particles with an un-reacted core were surrounded by a hydration zone. The 24-, 48-, and 72-h extracts of TCS 50 were the least cytotoxic. ZrO 2 can be added to TCS without affecting the mini-FT; Ca release was reduced initially, to reach a prolonged release thereafter; adding ZrO 2 made TCS cements more biocompatible. TCS 50 is a promising cement formulation to serve as a biocompatible hydraulic calcium silicate cement.

  15. A carbonate-silicate aqueous geochemical cycle model for Mars

    Science.gov (United States)

    Schaefer, M. W.; Leidecker, H.

    1992-01-01

    A model for the carbonate-silicate geochemical cycle of an early, wet Mars is under development. The results of this study will be used to constrain models of the geochemical history of Mars and the likely mineralogy of its present surface. Although Mars today is a cold, dry planet, it may once have been much warmer and wetter. Values of total outgassed CO2 from several to about 10 bars are consistent with present knowledge (Pollack et al. 1987), and this amount of CO2 implies an amount of water outgassed at least equal to an equivalent depth of 500-1000 meters (Carr 1986). Pollack et al. (1987), in addition, estimate that a thick CO2 atmosphere may have existed for an extended period of time, perhaps as long as a billion years. The greenhouse effect of such an atmosphere would permit the presence of liquid water on the surface, most likely in the form of a shallow sea in the lowest regions of the planet, such as the northern plains (Schaefer 1990). The treatment of geochemical cycles as complex kinetic chemical reactions has been undertaken for terrestrial systems in recent years with much success (Lasaga 1980, 1981; Berner et al. 1983; Lasaga et al. 1985). Although the Martian system is vastly less well understood, and hence less well-constrained, it is also a much simpler system, due to the lack of biogenic reactions that make the terrestrial system so complex. It should be possible, therefore, to use the same techniques to model the Martian system as have been used for terrestrial systems, and to produce useful results. A diagram of the carbonate-silicate cycle for Mars (simplified from the terrestrial system) is given.

  16. Fluorine in silicate glasses: A multinuclear nuclear magnetic resonance study

    Energy Technology Data Exchange (ETDEWEB)

    Schaller, T.; Dingwell, D.B.; Keppler, H.; Merwin, L.; Sebald, A. (Univ. Bayreuth (West Germany)); Knoeller, W. (Bruker Analytische Messtechnik, Rheinstetten (West Germany))

    1992-02-01

    Anhydrous nepheline, jadeite, and albite glasses doped with F as well as hydrous F-containing haplogranitic glasses were investigated using {sup 19}F combined rotation and multiple-pulse spectroscopy; {sup 19}F {yields} {sup 29}Si cross-polarization/magic angle spinning (MAS); and high-power {sup 19}F decoupled {sup 29}Si, {sup 23}Na, and {sup 27}Al MAS nuclear magnetic resonance methods. Fluorine preferentially coordinates with Al to form octahedral AlF{sub 6}{sup 3{minus}} complexes in all glasses studied. In addition, F anions bridging two Al cations, units containing octahedral Al coordinated by both O and F, or tetrahedral Al-F complexes might be present. The presence of Si-F bonds cannot be entirely ruled out but appears unlikely on the basis of the {sup 19}F {yields} {sup 29}Si CP/MAS spectra. There is no evidence for any significant coordination of F with alkalis in the glasses studied. Over the range of F contents studied (up to 5 wt.%), there seems to be hardly any dependence of F speciation on the concentration of F in the samples. The spectroscopic results explain the decrease of the viscosity of silicate melts with increasing F content by removal of Al from bridging AlO{sub 4}-units due to complexing with F, which causes depolymerization of the melt. The same mechanism can account for the shift of the eutectic point in the haplogranite system to more feldspar-rich compositions with increasing F content, and for the peraluminous composition of most F-rich granites. Liquid immiscibility in F-rich granitic melts might be caused by formation of (Na,K){sub 3}AlF{sub 6} units in the melt with little or no interaction with the silicate component. The presence of F in granitic melts might increase the solubility of high field strength cations by making nonbridging O atoms available which form complexes with these cations.

  17. Relationships between CO2, thermodynamic limits on silicate weathering, and the strength of the silicate weathering feedback

    Science.gov (United States)

    Winnick, Matthew J.; Maher, Kate

    2018-03-01

    Recent studies have suggested that thermodynamic limitations on chemical weathering rates exert a first-order control on riverine solute fluxes and by extension, global chemical weathering rates. As such, these limitations may play a prominent role in the regulation of carbon dioxide levels (pCO2) over geologic timescales by constraining the maximum global weathering flux. In this study, we develop a theoretical scaling relationship between equilibrium solute concentrations and pCO2 based on equilibrium constants and reaction stoichiometry relating primary mineral dissolution and secondary mineral precipitation. We test this theoretical scaling relationship against reactive transport simulations of chemical weathering profiles under open- and closed-system conditions, representing partially and fully water-saturated regolith, respectively. Under open-system conditions, equilibrium bicarbonate concentrations vary as a power-law function of pCO2 (y = kxn) where n is dependent on reaction stoichiometry and k is dependent on both reaction stoichiometry and the equilibrium constant. Under closed-system conditions, bicarbonate concentrations vary linearly with pCO2 at low values and approach open-system scaling at high pCO2. To describe the potential role of thermodynamic limitations in the global silicate weathering feedback, we develop a new mathematical framework to assess weathering feedback strength in terms of both (1) steady-state atmospheric pCO2 concentrations, and (2) susceptibility to secular changes in degassing rates and transient carbon cycle perturbations, which we term 1st and 2nd order feedback strength, respectively. Finally, we discuss the implications of these results for the effects of vascular land plant evolution on feedback strength, the potential role of vegetation in controlling modern solute fluxes, and the application of these frameworks to a more complete functional description of the silicate weathering feedback. Most notably, the dependence

  18. A design of spectrophotometric microfluidic chip sensor for analyzing silicate in seawater

    Science.gov (United States)

    Cao, X.; Zhang, S. W.; Chu, D. Z.; Wu, N.; Ma, H. K.; Liu, Y.

    2017-08-01

    High quality and continuous in situ silicate data are required to investigate the mechanism of the biogeochemical cycles and the formation of red tide. There is an urgently growing need for autonomous in situ silicate instruments that perform determination on various platforms. However, due to the high reagents and power consumption, as well as high system complexity leading to low reliability and robustness, the performance of the commercially available silicate sensors is not satisfactory. With these problems, here we present a new generation of microfluidic continuous flow analysis silicate sensor with sufficient analytical performance and robustness, for in situ determination of soluble silicate in seawater. The reaction mechanism of this sensor is based on the reaction of silicate with ammonium molybdate to form a yellow silicomolybdate complex and further reduction to silicomoIybdenum blue by ascorbic acid. The minimum limit of detection was 45.1 nmol L-1, and the linear determination range of the sensor is 0-400 μmol L-1. The recovery rate of the actual water is between 98.1%-104.0%, and the analyzing cycle of the sensor is about 5 minutes. This sensor has the advantages of high accuracy, high integration, low water consumption, and strong anti-interference ability. It has been successfully applied to measuring the silicate in seawater in Jiaozhou Bay.

  19. Petrophysical Analysis of Siliceous-Ooze Sediments, More Basin, Norwegian Sea

    DEFF Research Database (Denmark)

    Awedalkarim, Ahmed; Sørensen, Morten Kanne; Fabricius, Ida Lykke

    2014-01-01

    Pelagic siliceous-ooze sediments occur above the hydrocarbon reservoir of the Ormen Lange gas field in More Basin, Norwegian Sea. A possible hydrocarbon prospect of siliceous ooze was proposed, but siliceous ooze is significantly different in texture from most commonly known reservoir rocks. Logg....... Amplitude-versus-offset analysis indicated that an oil-saturated sandstone layer can be distinguished from water-saturated siliceous ooze.......Pelagic siliceous-ooze sediments occur above the hydrocarbon reservoir of the Ormen Lange gas field in More Basin, Norwegian Sea. A possible hydrocarbon prospect of siliceous ooze was proposed, but siliceous ooze is significantly different in texture from most commonly known reservoir rocks...... was calculated from the gamma-ray log and empirical grain-density data were calibrated with X-ray diffraction analysis data. The grain-density log was used with the calculated true porosity log and the brine density of 1.025 g/cm(3) to convert the bulk-density log from conventional limestone and water scaling...

  20. Evaluation of the effect of sodium silicate addition to mine backfill, Gelfill − Part 1

    Directory of Open Access Journals (Sweden)

    M. Kermani

    2015-06-01

    Full Text Available In this paper, the mechanical properties of sodium silicate-fortified backfill, called Gelfill, were investigated by conducting a series of laboratory experiments. Two configurations were tested, i.e. Gelfill and cemented hydraulic fill (CHF. The Gelfill has an alkali activator such as sodium silicate in its materials in addition to primary materials of mine backfill which are tailings, water and binders. Large numbers of samples of Gelfill and CHF with various mixture designs were cast and cured for over 28 d. The mechanical properties of samples were investigated using uniaxial compression test, and the results were compared with those of reference samples made without sodium silicate. The test results indicated that the addition of an appropriate amount of an alkali activator such as sodium silicate can enhance the mechanical (uniaxial compressive strength and physical (water retention properties of backfill. The microstructure analysis conducted by mercury intrusion porosimetry (MIP revealed that the addition of sodium silicate can modify the pore size distribution and total porosity of Gelfill, which can contribute to the better mechanical properties of Gelfill. It was also shown that the time and rate of drainage in the Gelfill specimens are less than those in CHF specimens made without sodium silicate. Finally, the study showed that the addition of sodium silicate can reduce the required setting time of mine backfill, which can contribute to increase mine production in accordance with the mine safety.

  1. Bilateral urinary calculi after treatment with a silicate-containing milk thickener.

    Science.gov (United States)

    Ulinski, Tim; Sabot, Jean-François; Bourlon, Isabelle; Cochat, Pierre

    2004-04-01

    Nephrocalcinosis and/or urinary calculi are rare in infants. Furosemide treatment during the neonatal period, vitamin D intoxication, hereditary diseases such as hyperoxaluria or distal tubular acidosis are among the most common aetiologies. We report the case of a 6-month-old boy with an extra-hepatic biliary duct atresia treated by the Kasai procedure and a gastro-oesophageal reflux treated with a silicate containing milk thickener (Gelopectose, 5.5% colloidal silicate) since the neonatal period. He did not present any other endogenous risk factor for urinary stone formation (normal urinary calcium/creatinine ratio; normal urinary magnesium excretion). The nephrolithiasis was discovered as the boy presented painful episodes of macroscopic haematuria. Ultrasound examination revealed bilateral nephrocalcinosis and multiple bilateral calculi without infection or urinary obstruction. Infrared spectroscopy revealed silicate as the major component suggesting silicate absorption to be responsible for the described symptoms. After replacement of the silicate-containing agent by a silicate-free milk thickener, the lesions were completely reversible as confirmed by repeated renal ultrasound examinations over a 2-month period. Silicate-containing milk thickeners can be responsible for urinary calculi and/or nephrocalcinosis.

  2. Preparation and Characterization of Lithium Zirconium Silicate for CO2 Capture

    Directory of Open Access Journals (Sweden)

    T.S. Bhosale

    2014-10-01

    Full Text Available The samples of lithium zirconium silicate were prepared by precipitation, template and sol-gel meth-ods. The samples were prepared with several mol ratios of Li:Zr:Si. The preparation of lithium zirco-nium silicate samples by precipitation method were carried out by using the lithium nitrate, zirconyl nitrate, zirconium(IV oxypropoxide and tetramethylorthosilicate (TEOS as precursors. The samples of lithium zirconium silicate were prepared by using cetyltrimethyl-ammonium bromide (C-TAB and tetramethyl ammonium hydroxide (TMAOH by template method. The samples of lithium zirconium silicate were characterized by XRD, TEM, SEM, 29Si-MAS NMR and FTIR. The surface area, alkalinity / acidity of the samples of lithium zirconium silicate were measured. The TGA analysis of lithium zirco-nium silicate samples was done. The CO2 captured by the samples of lithium zirconium silicate was es-timated. The captured CO2 by the samples of lithium zirconium silicate was found to be in the range 3.3 to 8.6 wt%. © 2014 BCREC UNDIP. All rights reservedReceived: 27th March 2014; Revised: 31st July 2014; Accepted: 2nd August 2014How to Cite: Bhosale, T.S. , Gaikwad, A.G. (2014. Preparation and Characterization of Lithium Zirconium Silicate for CO2 Capture. Bulletin of Chemical Reaction Engineering & Catalysis, 9(3: 249-262. (doi:10.9767/bcrec.9.3.6646.249-262Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.3.6646.249-262

  3. Sulfur Saturation Limits in Silicate Melts and their Implications for Core Formation Scenarios for Terrestrial Planets

    Science.gov (United States)

    Holzheid, Astrid; Grove, Timothy L.

    2002-01-01

    This study explores the controls of temperature, pressure, and silicate melt composition on S solubility in silicate liquids. The solubility of S in FeO-containing silicate melts in equilibrium with metal sulfide increases significantly with increasing temperature but decreases with increasing pressure. The silicate melt structure also exercises a control on S solubility. Increasing the degree of polymerization of the silicate melt structure lowers the S solubility in the silicate liquid. The new set of experimental data is used to expand the model of Mavrogenes and O'Neill(1999) for S solubility in silicate liquids by incorporating the influence of the silicate melt structure. The expected S solubility in the ascending magma is calculated using the expanded model. Because the negative pressure dependence of S solubility is more influential than the positive temperature dependence, decompression and adiabatic ascent of a formerly S-saturated silicate magma will lead to S undersaturation. A primitive magma that is S-saturated in its source region will, therefore, become S-undersaturated as it ascends to shallower depth. In order to precipitate magmatic sulfides, the magma must first cool and undergo fractional crystallization to reach S saturation. The S content in a metallic liquid that is in equilibrium with a magma ocean that contains approx. 200 ppm S (i.e., Earth's bulk mantle S content) ranges from 5.5 to 12 wt% S. This range of S values encompasses the amount of S (9 to 12 wt%) that would be present in the outer core if S is the light element. Thus, the Earth's proto-mantle could be in equilibrium (in terms of the preserved S abundance) with a core-forming metallic phase.

  4. Ferrites Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} doped with samarium: structural analysis, morphological and electromagnetic; Ferritas Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} dopada com samario: analise estrutural, morfologica e eletromagnetica

    Energy Technology Data Exchange (ETDEWEB)

    Costa, A.C.F.M.; Diniz, A.P., E-mail: anacristina@dema.ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academinca de Engenharia de Materiais; Viana, K.M.S. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, PE (Brazil). Escola de Ciencias e Tecnologia; Cornejo, D.R. [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Fisica; Kiminami, R.H.G.A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

    2010-07-01

    This paper proposes to investigate the sintering at 1200 deg C/2h of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2-x}Sm{sub x}O{sub 4} ferrite doped with 0.05; 0.075 e 0.1 mol of Sm synthesized by combustion reaction to evaluate the performance materials as absorbers of electromagnetic radiation. The influence of the concentration of samarium on the structure, morphology and electromagnetic properties of ferrites was studied. The resulting samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), magnetic measurements and reflectivity measurements in the frequency range between 8-12 GHz. The results showed that increasing the concentration of samarium caused a decrease in particle size of the samples, encouraging, therefore, to obtain materials with better values of magnetization and reflectivity, allowing for use as absorbers in narrow-band frequency between 9-10 GHz. (author)

  5. Pockels effect of silicate glass-ceramics: Observation of optical modulation in Mach-Zehnder system.

    Science.gov (United States)

    Yamaoka, Kazuki; Takahashi, Yoshihiro; Yamazaki, Yoshiki; Terakado, Nobuaki; Miyazaki, Takamichi; Fujiwara, Takumi

    2015-07-17

    Silicate glass has been used for long time because of its advantages from material's viewpoint. In this paper, we report the observation of Pockels effect by Mach-Zehnder interferometer in polycrystalline ceramics made from a ternary silicate glass via crystallization due to heat-treatment, i.e., glass-ceramics. Since the silicate system is employed as the precursor, merits of glass material are fully utilized to fabricate the optical device component, in addition to that of functional crystalline material, leading us to provide an electro-optic device, which is introducible into glass-fiber network.

  6. USE OF LOCAL NATURAL SILICEOUS RAW MATERIAL AND WASTES FOR PRODUCTION OF HEAT-INSULATING FOAMCONCRETE

    Directory of Open Access Journals (Sweden)

    V. U. Matsapulin

    2015-01-01

    Full Text Available The article analyzes the resource base, reserves and the use of siliceous rocks, their economic feasibility of the use for production of building materials of new generation with low-energy and other costs. Presented are the results of laboratory research and testing technology of production of insulating foam from a composition based on an aqueous solution of sodium silicate obtained from the local siliceous rocks (diatomite and the liquid alkali component - soapstock, hardener from ferrochrome slag and waste carbonate rock able to harden at a low temperature processing ( 100-110 ° C.

  7. Production of reactive oxygen species from abraded silicates. Implications for the reactivity of the Martian soil

    DEFF Research Database (Denmark)

    Bak, Ebbe Norskov; Zafirov, Kaloyan; Merrison, Jonathan P.

    2017-01-01

    to oxidants in the form of hydrogen peroxide (H2O2) and hydroxyl radicals (⋅OH). We found that silicate samples abraded in simulated Martian atmospheres gave rise to a significant production of H2O2 and ⋅OH upon contact with water. Our experiments demonstrated that abraded silicates could lead to a production...... of H2O2 facilitated by atmospheric O2 and inhibited by carbon dioxide. Furthermore, during simulated saltation the silicate particles became triboelectrically charged and at pressures similar to the Martian surface pressure we observed glow discharges. Electrical discharges can cause dissociation of CO...

  8. Carbonate formation in non-aqueous environments by solid-gas carbonation of silicates

    Science.gov (United States)

    Day, S. J.; Thompson, S. P.; Evans, A.; Parker, J. E.

    2012-02-01

    We have produced synthetic analogues of cosmic silicates using the Sol Gel method, producing amorphous silicates of composition Mg(x)Ca(1-x)SiO3. Using synchrotron X-ray powder diffraction on Beamline I11 at the Diamond Light Source, together with a newly-commissioned gas cell, real-time powder diffraction scans have been taken of a range of silicates exposed to CO2 under non-ambient conditions. The SXPD is complemented by other techniques including Raman and Infrared Spectroscopy and SEM imaging.

  9. The distribution of chromium among orthopyroxene, spinel and silicate liquid at atmospheric pressure

    Science.gov (United States)

    Barnes, S. J.

    1986-01-01

    The Cr distributions for a synthetic silicate melt equilibrated with bronzitic orthopyroxene and chromite spinel between 1334 and 1151 C over a range of oxygen fugacities between the nickel-nickel oxide and iron-wuestite buffers are studied. The occurrence, chemical composition, and structure of the orthopyroxene-silicate melt and the spinel-silicate melt are described. It is observed that the Cr content between bronzite and the melt increases with falling temperature along a given oxygen buffer and decreases with falling oxygen fugacity at a given temperature; however, the Cr content of the melt in equilibrium with spinel decreases with falling temperature and increases with lower oxygen fugacity.

  10. Metal - Silicate Separation in a Deformation Regime: Implications for Early Differentiation Processes

    Science.gov (United States)

    Rushmer, T.; Jones, J. H.; Gaetani, G.; Zanda, B.

    2001-12-01

    The segregation of metallic cores from silicate mantles is one of the earliest, and most important, differentiation process involved in the evolution of the Earth and other terrestrial planetary bodies. The physical segregation of Fe-rich metal from silicate imparted a strong geochemical signature on early silicate mantles due to the preferential incorporation of siderophile elements into the core. Reconciling our estimates of primary bulk silicate mantle with candidate planetary bulk compositions requires an understanding of the geochemical consequences of the different regimes in which core forming material may have been mobile. This includes not only the possible differentiation processes that occurred in the terrestrial planets, but also understanding the differentiation processes in the meteorite parent bodies. Although a magma ocean model is possible for efficient core formation, some scenarios call for segregation of the core from solid silicate and the geochemical consequences can be significantly different. Experimental studies are one way in which insight can be gained into the possible geochemical signatures of metal-silicate segregation. Deformation experiments in addition provide a dynamic component, which allows liquid metal to segregate from solid silicate. Starting materials are cored from a slab of the Kernouve fall which is composed of olivine, pyroxene, plagioclase, chromite and chlorapatite; Fe-Ni metal and sulfide form 20-25% of the sample. Experimental conditions are 1.0-1.4 GPa confining pressure with strain rates of 10-4/s to 10-6/s. Temperatures ranging from 900° C to 1050° C produce variable amounts of silicate melt and different mechanisms of metal segregation are observed. In experiments which are below the silicate solidus, mobility of FeS is extensive and deformation textures are cataclastic. Geochemical analyses shows that migration of Fe-S-Ni-O metal through fractures and along grain boundaries produces extensive modification to

  11. Lifetime Predictions of a Titanium Silicate Glass with Machined Flaws

    Science.gov (United States)

    Tucker, Dennis S.; Nettles, Alan T.; Cagle, Holly

    2003-01-01

    A dynamic fatigue study was performed on a Titanium Silicate glass to assess its susceptibility to delayed failure and to compare the results with those of a previous study. Fracture mechanics techniques were used to analyze the results for the purpose of making lifetime predictions. The material strength and lifetime was seen to increase due to the removal of residual stress through grinding and polishing. Influence on time-to-failure is addressed for the case with and without residual stress present. Titanium silicate glass otherwise known as ultra-low expansion (ULE)* glass is a candidate for use in applications requiring low thermal expansion characteristics such as telescope mirrors. The Hubble Space Telescope s primary mirror was manufactured from ULE glass. ULE contains 7.5% titanium dioxide which in combination with silica results in a homogenous glass with a linear expansion coefficient near zero. delayed failure . This previous study was based on a 230/270 grit surface. The grinding and polishing process reduces the surface flaw size and subsurface damage, and relieves residual stress by removing the material with successively smaller grinding media. This results in an increase in strength of the optic during the grinding and polishing sequence. Thus, a second study was undertaken using samples with a surface finish typically achieved for mirror elements, to observe the effects of surface finishing on the time-to-failure predictions. An allowable stress can be calculated for this material based upon modulus of rupture data; however, this does not take into account the problem of delayed failure, most likely due to stress corrosion, which can significantly shorten lifetime. Fortunately, a theory based on fracture mechanics has been developed enabling lifetime predictions to be made for brittle materials susceptible to delayed failure. Knowledge of the factors governing the rate of subcritical flaw growth in a given environment enables the development of

  12. Crystallisation mechanism of a multicomponent lithium alumino-silicate glass

    Energy Technology Data Exchange (ETDEWEB)

    Wurth, R. [Otto-Schott-Institut, Jena University, Fraunhoferstr. 6, 07743 Jena (Germany); Pascual, M.J., E-mail: mpascual@icv.csic.es [Instituto de Ceramica y Vidrio, CSIC, Kelsen 5, 28049 Madrid (Spain); Mather, G.C.; Pablos-Martin, A.; Munoz, F.; Duran, A. [Instituto de Ceramica y Vidrio, CSIC, Kelsen 5, 28049 Madrid (Spain); Cuello, G.J. [Institut Laue-Langevin, Boite Postale 156, 38042 Grenoble Cedex 9 (France); Ruessel, C. [Otto-Schott-Institut, Jena University, Fraunhoferstr. 6, 07743 Jena (Germany)

    2012-06-15

    A base glass of composition 3.5 Li{sub 2}O Bullet-Operator 0.15 Na{sub 2}O Bullet-Operator 0.2 K{sub 2}O Bullet-Operator 1.15 MgO Bullet-Operator 0.8 BaO Bullet-Operator 1.5 ZnO Bullet-Operator 20 Al{sub 2}O{sub 3} Bullet-Operator 67.2 SiO{sub 2} Bullet-Operator 2.6 TiO{sub 2} Bullet-Operator 1.7 ZrO{sub 2} Bullet-Operator 1.2 As{sub 2}O{sub 3} (in wt.%), melted and provided by SCHOTT AG (Mainz), was used to study the crystallisation mechanism of lithium alumino-silicate glass employing X-ray diffraction combined with neutron diffraction and non-isothermal differential scanning calorimetry (DSC). A high-quartz solid solution of LiAlSi{sub 2}O{sub 6} with nanoscaled crystals forms at 750 Degree-Sign C. Quantitative Rietveld refinement of samples annealed at 750 Degree-Sign C for 8 h determined a crystallised fraction of around 59 wt.%. The room temperature crystallised phase adopts an ordered, {beta}-eucryptite-like structure (2 Multiplication-Sign 2 Multiplication-Sign 2 cell) with Li ordered in the structural channels. The Avrami parameter (n {approx} 4), calculated from DSC data using different theoretical approaches, indicates that bulk crystallisation occurs and that the number of nuclei increases during annealing. The activation energy of the crystallisation is 531 {+-} 20 kJ mol{sup -1}. - Highlights: Black-Right-Pointing-Pointer Nanoscaled high-quartz crystals from a multicomponent lithium alumino-silicate glass. Black-Right-Pointing-Pointer Combined X-ray and neutron diffraction structural refinement. Black-Right-Pointing-Pointer {beta}-Eucryptite-like structure (2 Multiplication-Sign 2 Multiplication-Sign 2 cell) with Li ordered in the structural channels. Black-Right-Pointing-Pointer 3-Dimensional bulk crystallisation mechanism with an increasing number of nuclei. Black-Right-Pointing-Pointer Usage and validation of an alternative approach to calculate the Avrami parameter.

  13. Microstructure engineering of Portland cement pastes and mortars through addition of ultrafine layer silicates

    DEFF Research Database (Denmark)

    Lindgreen, Holger; Geiker, Mette; Krøyer, Hanne

    2008-01-01

    Pozzolanic submicron-sized silica fume and the non-pozzolanic micron- and nano-sized layer silicates (clay minerals) kaolinite, smectite and palygorskite have been used as additives in Portland cement pastes and mortars. These layer silicates have different particle shape (needles and plates...... is that the cement paste structure and porosity can be engineered by addition of selected layer silicates having specific particle shapes and surface properties (e.g., charge and specific surface area). This seems to be due to the growth of calcium-silicate hydrates (C-S-H) on the clay particle surfaces......), surface charge, and size (micron and nano). The structure of the resulting cement pastes and mortars has been investigated by atomic force microscopy (AFM), helium porosimetry, nitrogen adsorption (specific surface area and porosity), low-temperature calorimetry (LTC) and thermal analysis. The main result...

  14. Some observations on use of siliceous mineral waters in reduction of corrosion in RCC structures

    Digital Repository Service at National Institute of Oceanography (India)

    Venugopal, C.

    The corrosion-resisting characteristics of reinforcement in cement blended with siliceous mineral wastes viz. gold tailing and flyash have been evaluated by using an accelerated corrosion technique. The additions of these mineral admixtures...

  15. Geotechnical properties of two siliceous cores from the central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Khadge, N.H.

    Physical properties of the siliceous sediments from the Central Indian Basin are measured on two short cores. The properties such as water content, Atterberg limits, porosity specific gravity, wet density show the medium to high plastic sediment...

  16. Black silicate paints: Formulation and performance data on OSO-H

    Science.gov (United States)

    Schutt, J. B.; Shai, C. M.

    1973-01-01

    Formulations and general procedures are given for making and applying space environmentally, as well as atmospherically stable black silicate paints. Compositions are given which meet spacecraft self-contamination requirements, have excellent heat resistance, and are strongly semiconductive.

  17. Polymer Derived Rare Earth Silicate Nanocomposite Protective Coatings for Nuclear Thermal Propulsion Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this Phase I SBIR program is to develop polymer derived rare earth silicate nanocomposite environmental barrier coatings (EBC) for providing...

  18. Carbonation of metal silicates for long-term CO.sub.2 sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Blencoe, James G.; Palmer, Donald A.; Anovitz, Lawrence M.; Beard, James S.

    2017-08-01

    In a preferred embodiment, the invention relates to a process of sequestering carbon dioxide. The process comprises the steps of: (a) reacting a metal silicate with a caustic alkali-metal hydroxide to produce a hydroxide of the metal formerly contained in the silicate; (b) reacting carbon dioxide with at least one of a caustic alkali-metal hydroxide and an alkali-metal silicate to produce at least one of an alkali-metal carbonate and an alkali-metal bicarbonate; and (c) reacting the metal hydroxide product of step (a) with at least one of the alkali-metal carbonate and the alkali-metal bicarbonate produced in step (b) to produce a carbonate of the metal formerly contained in the metal silicate of step (a).

  19. Polymer Derived Yttrium Silicate Ablative TPS Materials for Next-Generation Exploration Missions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Through the proposed NASA SBIR program, NanoSonic will optimize its HybridSil® derived yttrium silicates to serve as next-generation reinforcement for carbon...

  20. USE OF LOCAL NATURAL SILICEOUS RAW MATERIAL AND WASTES FOR PRODUCTION OF HEAT-INSULATING FOAMCONCRETE

    National Research Council Canada - National Science Library

    V. U. Matsapulin; A. B. Toturbiev; V. I. Toturbiev; B. D. Toturbieva; V. I. Cherkashin

    2015-01-01

    The article analyzes the resource base, reserves and the use of siliceous rocks, their economic feasibility of the use for production of building materials of new generation with low-energy and other costs...

  1. Polymer Derived Rare Earth Silicate Nanocomposite Protective Coatings for Nuclear Thermal Propulsion Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Leveraging a rapidly evolving state-of-the-art technical base empowered by Phase I NASA SBIR funding, NanoSonic's polymer derived rare earth silicate EBCs will...

  2. THE ALUMINA-SILICATES IN STABILIZATION PROCESSES IN FLUIDIZED-BED ASH

    Directory of Open Access Journals (Sweden)

    IVANA PERNA

    2011-03-01

    Full Text Available Presented study of coal fluidized-bed ash solidification was accompanied with specific studies of alumino-silicates residues in ashes. The specific technology of fluid coal burning and its relatively low temperature combustion combines coal burning and decomposition of calcium carbonate added to the fluid layer in the main endeavor to capture all sulfur oxides. The burning temperature seems be decisive to the behavior of clayed residues and calcium carbonate decomposition in connection for the future solidification of fluidized bed ash. The calcareous substances in combination with alumino-silicate residues form solid bodies where silicates play decisive role of long-term stability and insolubility of obtained solids. The position of aluminum ions in clayed residues of burned coal were studied by MAS-NMR with attention on aluminum ion coordination to oxygen and formation of roentgen amorphous phase of poly-condensed calcium alumina-silicate.

  3. Effects of soil drenching of water-soluble potassium silicate on ...

    African Journals Online (AJOL)

    Effects of soil drenching of water-soluble potassium silicate on commercial avocado ( Persea americana Mill.) orchard trees infected with Phytophthora cinnamomi Rands on root density, canopy health, induction and concentration of phenolic com.

  4. [Colonization of silicate bacterium strain NBT in wheat roots].

    Science.gov (United States)

    Sheng, Xiafang

    2003-11-01

    The strain NBT of silicate bacterium was labelled with streptomycin, and a stable streptomycin resistance strain NBT was obtained. Its colonization dynamics and affecting factors in wheat rhizosphere were studied in agar plates and greenhouse pots were studied by counting the method with selective medium. The results of pot culture experiment showed that strain NBT could successfully colonize in the rhizosphere of wheat. In pot cultures of sterile soil, the highest colonization level (3.4 x 10(7) cfu.g-1 root soil) was reached on 9th day after seeds sown; at 54th day, the population of strain NBT tended to stable, and decreased to 1.4 x 10(4) cfu.g-1 root soil. In pot cultures of unsterile soil, the highest colonization level (3.8 x 10(7) cfu.g-1 root soil) was reached at 9th day, and the population of strain NBT tended to a stationary state at 60th day, with the numbers being 1.4 x 10(4) cfu.g-1 root soil. Some biological and abiotic factors could greatly influence the colonization of the beneficial microorganism.

  5. A New Biphasic Dicalcium Silicate Bone Cement Implant

    Directory of Open Access Journals (Sweden)

    Fausto Zuleta

    2017-07-01

    Full Text Available This study aimed to investigate the processing parameters and biocompatibility of a novel biphasic dicalcium silicate (C2S cement. Biphasic α´L + β-C2Sss was synthesized by solid-state processing, and was used as a raw material to prepare the cement. In vitro bioactivity and biocompatibility studies were assessed by soaking the cement samples in simulated body fluid (SBF and human adipose stem cell cultures. Two critical-sized defects of 6 mm Ø were created in 15 NZ tibias. A porous cement made of the high temperature forms of C2S, with a low phosphorous substitution level, was produced. An apatite-like layer covered the cement’s surface after soaking in SBF. The cell attachment test showed that α´L + β-C2Sss supported cells sticking and spreading after 24 h of culture. The cement paste (55.86 ± 0.23 obtained higher bone-to-implant contact (BIC percentage values (better quality, closer contact in the histomorphometric analysis, and defect closure was significant compared to the control group (plastic. The residual material volume of the porous cement was 35.42 ± 2.08% of the initial value. The highest BIC and bone formation percentages were obtained on day 60. These results suggest that the cement paste is advantageous for initial bone regeneration.

  6. Mesoporous Calcium Silicate Nanoparticles with Drug Delivery and Odontogenesis Properties.

    Science.gov (United States)

    Huang, Ching-Yuang; Huang, Tsui-Hsien; Kao, Chia-Tze; Wu, Yuan-Haw; Chen, Wan-Chen; Shie, Ming-You

    2017-01-01

    Calcium silicate (CS) -based materials play an important role in the development of endodontic materials that induce bone/cementum tissue regeneration and inhibit bacterial viability. The aim of this study was to prepare novel mesoporous CS (MesoCS) nanoparticles that have osteogenic, drug delivery, and antibacterial characteristics for endodontic materials and also have an excellent ability to develop apatite mineralization. The MesoCS nanoparticles were prepared using sol-gel methods. In addition, the mesoporous structure, specific surface area, pore volume, and morphology of the MesoCS nanoparticles were analyzed. The apatite mineralization ability, in vitro odontogenic differentiation, drug delivery, and antibacterial properties of the MesoCS nanoparticles were further investigated. The results indicate that the 200-nm-sized MesoCS nanoparticles synthesized using a facile template method exhibited a high specific surface area and pore volume with internal mesopores (average pore size = 3.05 nm). Furthermore, the MesoCS nanoparticles can be used as drug carriers to maintain sustained release of gentamicin and fibroblast growth factor-2 (FGF-2). The MesoCS-loaded FGF-2 might stimulate more odontogenic-related protein than CS because of the FGF-2 release. Based on this work, it can be inferred that MesoCS nanoparticles are potentially useful endodontic materials for biocompatible and osteogenic dental pulp tissue regenerative materials. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  7. A New Biphasic Dicalcium Silicate Bone Cement Implant

    Science.gov (United States)

    Murciano, Angel; Maté-Sánchez de Val, José E.

    2017-01-01

    This study aimed to investigate the processing parameters and biocompatibility of a novel biphasic dicalcium silicate (C2S) cement. Biphasic α´L + β-C2Sss was synthesized by solid-state processing, and was used as a raw material to prepare the cement. In vitro bioactivity and biocompatibility studies were assessed by soaking the cement samples in simulated body fluid (SBF) and human adipose stem cell cultures. Two critical-sized defects of 6 mm Ø were created in 15 NZ tibias. A porous cement made of the high temperature forms of C2S, with a low phosphorous substitution level, was produced. An apatite-like layer covered the cement’s surface after soaking in SBF. The cell attachment test showed that α´L + β-C2Sss supported cells sticking and spreading after 24 h of culture. The cement paste (55.86 ± 0.23) obtained higher bone-to-implant contact (BIC) percentage values (better quality, closer contact) in the histomorphometric analysis, and defect closure was significant compared to the control group (plastic). The residual material volume of the porous cement was 35.42 ± 2.08% of the initial value. The highest BIC and bone formation percentages were obtained on day 60. These results suggest that the cement paste is advantageous for initial bone regeneration. PMID:28773119

  8. Quaternary ammonium borohydride adsorption in mesoporous silicate MCM-48

    Energy Technology Data Exchange (ETDEWEB)

    Wolverton, Michael J [Los Alamos National Laboratory; Daemen, Luke L [Los Alamos National Laboratory; Hartl, Monika A [Los Alamos National Laboratory

    2010-01-01

    Inorganic borohydrides have a high gravimetric hydrogen density but release H2 only under energetically unfavorable conditions. Surface chemistry may help in lowering thermodynamic barriers, but inclusion of inorganic borohydrides in porous silica materials has proved hitherto difficult or impossible. We show that borohydrides with a large organic cation are readily adsorbed inside mesoporous silicates, particularly after surface treatment. Thermal analysis reveals that the decomposition thermodynamics of tetraalkylammonium borohydrides are substantially affected by inclusion in MCM-48. Inelastic neutron scattering (INS) data show that the compounds adsorb on the silica surface. Evidence of pore loading is supplemented by DSC/TGA, XRD, FTIR, and BET isotherm measurements. Mass spectrometry shows significant hydrogen release at lower temperature from adsorbed borohydrides in comparison with the bulk borohydrides. INS data measured for partially decomposed samples indicates that the decomposition of the cation and anion is likely simultaneous. Additionally, these data confirm the formation of Si-H bonds on the silica surface upon decomposition of adsorbed tetramethylammonium borohydride.

  9. Intraplate mantle oxidation by volatile-rich silicic magmas

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Audrey M.; Médard, Etienne; Righter, Kevin; Lanzirotti, Antonio

    2017-11-01

    The upper subcontinental lithospheric mantle below the French Massif Central is more oxidized than the average continental lithosphere, although the origin of this anomaly remains unknown. Using iron oxidation analysis in clinopyroxene, oxybarometry, and melt inclusions in mantle xenoliths, we show that widespread infiltration of volatile (HCSO)-rich silicic melts played a major role in this oxidation. We propose the first comprehensive model of magmatism and mantle oxidation at an intraplate setting. Two oxidizing events occurred: (1) a 365–286 Ma old magmatic episode that produced alkaline vaugnerites, potassic lamprophyres, and K-rich calc-alkaline granitoids, related to the N–S Rhenohercynian subduction, and (2) < 30 Ma old magmatism related to W–E extension, producing carbonatites and hydrous potassic trachytes. These melts were capable of locally increasing the subcontinental lithospheric mantle fO2 to FMQ + 2.4. Both events originate from the melting of a metasomatized lithosphere containing carbonate + phlogopite ± amphibole. The persistence of this volatile-rich lithospheric source implies the potential for new episodes of volatile-rich magmatism. Similarities with worldwide magmatism also show that the importance of volatiles and the oxidation of the mantle in intraplate regions is underestimated.

  10. Nanoporous Calcium Silicate and PLGA Biocomposite for Bone Repair

    Directory of Open Access Journals (Sweden)

    Jiacan Su

    2010-01-01

    Full Text Available Nanoporous calcium silicate (n-CS with high surface area was synthesized using the mixed surfactants of EO20PO70EO20 (polyethylene oxide20(polypropylene oxide70(polyethylene oxide20, P123 and hexadecyltrimethyl ammonium bromide (CTAB as templates, and its composite with poly(lactic acid-co-glycolic acid (PLGA were fabricated. The results showed that the n-CS/PLGA composite (n-CPC with 20 wt% n-CS could induce a dense and continuous layer of apatite on its surface after soaking in simulated body fluid (SBF for 1 week, suggesting the excellent in vitro bioactivity. The n-CPC could promote cell attachment on its surfaces. In addition, the proliferation ratio of MG63 cells on n-CPC was significantly higher than PLGA; the results demonstrated that n-CPC had excellent cytocompatibility. We prepared n-CPC scaffolds that contained open and interconnected macropores ranging in size from 200 to 500 μm. The n-CPC scaffolds were implanted in femur bone defect of rabbits, and the in vivo biocompatibility and osteogenicity of the scaffolds were investigated. The results indicated that n-CPC scaffolds exhibited good biocompatibility, degradability, and osteogenesis in vivo. Collectively, these results suggested that the incorporation of n-CS in PLGA produced biocomposites with improved bioactivity and biocompatibility.

  11. Calcium silicate hydrates: Solid and liquid phase composition

    Energy Technology Data Exchange (ETDEWEB)

    Lothenbach, Barbara, E-mail: Barbara.lothenbach@empa.ch [Laboratory Concrete & Construction Chemistry, Empa (Switzerland); Nonat, André [ICB, UMR CNRS 6303 CNRS-Université de Bourgogne, Faculté des Sciences et Techniques, BP47870, 21078 Dijon Cedex (France)

    2015-12-15

    This paper presents a review on the relationship between the composition, the structure and the solution in which calcium silicate hydrate (C–S–H) is equilibrated. The silica chain length in C–S–H increases with the silicon concentration and the calcium content in the interlayer space with the calcium concentrations. Sodium and potassium are taken up in the interlayer space, preferentially at low calcium concentrations and thus by low Ca/Si C–S–H. Aluminium uptake in C–S–H increases strongly at higher aluminium concentrations in the solution. At low Ca/Si, aluminium substitutes silica in the bridging position, at Ca/Si > 1 aluminium is bound in TAH. Recently developed thermodynamic models are closely related to the structure of C–S–H and tobermorite, and able to model not only the solubility and the chemical composition of the C–S–H, but also to predict the mean silica chain length and the uptake of aluminium.

  12. Mechanical behavior of a composite interface: Calcium-silicate-hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Palkovic, Steven D.; Moeini, Sina; Büyüköztürk, Oral, E-mail: obuyuk@mit.edu [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Yip, Sidney [Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-07-21

    The generalized stacking fault (GSF) is a conceptual procedure historically used to assess shear behavior of defect-free crystalline structures through molecular dynamics or density functional theory simulations. We apply the GSF technique to the spatially and chemically complex quasi-layered structure of calcium-silicate-hydrates (C-S-H), the fundamental nanoscale binder within cementitious materials. A failure plane is enforced to calculate the shear traction-displacement response along a composite interface containing highly confined water molecules, hydroxyl groups, and calcium ions. GSF simulations are compared with affine (homogeneous) shear simulations, which allow strain to localize naturally in response to the local atomic environment. Comparison of strength and deformation behavior for the two loading methods shows the composite interface controls bulk shear deformation. Both models indicate the maximum shear strength of C-S-H exhibits a normal-stress dependency typical of cohesive-frictional materials. These findings suggest the applicability of GSF techniques to inhomogeneous structures and bonding environments, including other layered systems such as biological materials containing organic and inorganic interfaces.

  13. Efficacy of dispersion of magnesium silicate (talc in papermaking

    Directory of Open Access Journals (Sweden)

    Vipul Singh Chauhan

    2017-02-01

    Full Text Available The understanding of the dispersion chemistry of papermaking grade fillers is as important as their effect on paper. Magnesium silicate (talc is one of the major fillers used for papermaking. It is hydrophobic and chemically inert. The dispersion chemistry of talc of different particle sizes was studied with wetting agent (non-ionic triblock copolymer and anionic dispersant (sodium salt of polyacrylic acid. Both wetting agent and dispersant were added in talc slurry separately and in combination. The dispersion behavior was studied through measuring the Brookfield viscosity. The wetted and dispersed talc was also added to paper to understand its effect on papermaking process and paper properties. Wetting and dispersion changed the colloidal charge chemistry of talc making it more anionic which reduced the talc retention in paper. Lowering the particle size of talc significantly improved the light scattering coefficient (LSC of paper and decreased its retention. Controlling colloidal charge of papermaking suspension with cationic polyacrylamide polymer helped in protecting the retention of talc without affecting the LSC of both filler and paper.

  14. Silicate grout curtains behaviour for the protection of coastal aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Elektorowicz, M.; Chifrina, R.; Hesnawi, R. [Concordia Univ., Montreal, Quebec (Canada)

    1997-12-31

    Tests were performed to evaluate the behaviour of silicate grout with different reagents (ethylacetate - formamide SA and calcium chloride SC) in pure silica sand and natural soils from coastal areas containing organic matter, clayey soil and silica sand. The grouted specimens were tested with simulated fresh and salt water. The setting process during chemical grouting in the soil and sand was studied. The grouting of soil and sand with SA caused a transfer to the environment of some compounds: sodium formate, sodium acetate, ammonia and part of the initial ethylacetate and formamide. This process had a tendency to decrease for approximately 4 months. The stability of specimens was low. The grouting of soil and sand with SC caused no significant contamination of the environment. The increase of pH of environmental water was even less than with SA grouting. Also, the stability of specimens is higher in comparison with SA grouting. Salt water protected the specimens grouted with SA and SC from destruction and prevented contamination.

  15. Understanding controlled drug release from mesoporous silicates: theory and experiment.

    Science.gov (United States)

    Ukmar, T; Maver, U; Planinšek, O; Kaučič, V; Gaberšček, M; Godec, A

    2011-11-07

    Based on the results of carefully designed experiments upgraded with appropriate theoretical modeling, we present clear evidence that the release curves from mesoporous materials are significantly affected by drug-matrix interactions. In experimental curves, these interactions are manifested as a non-convergence at long times and an inverse dependence of release kinetics on pore size. Neither of these phenomena is expected in non-interacting systems. Although both phenomena have, rather sporadically, been observed in previous research, they have not been explained in terms of a general and consistent theoretical model. The concept is demonstrated on a model drug indomethacin embedded into SBA-15 and MCM-41 porous silicates. The experimental release curves agree exceptionally well with theoretical predictions in the case of significant drug-wall attractions. The latter are described using a 2D Fokker-Planck equation. One could say that the interactions affect the relative cross-section of pores where the local flux has a non-vanishing axial component and in turn control the effective transfer of drug into bulk solution. Finally, we identify the critical parameters determining the pore size dependence of release kinetics and construct a dynamic phase diagram of the various resulting transport regimes. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Distribution of rubidium between sodic sanidine and natural silicic liquid

    Science.gov (United States)

    Noble, D.C.; Hedge, C.E.

    1970-01-01

    Phenocrysts of sodic sanidine from twelve upper Cenozoic units of silicic ash-flow tuff and lava from the Western United States contain from 0.25 to 0.45 the Rb present in the associated groundmass materials. The ratios of potassium to rubidium in the sanidines are, on the average, about four times greater than those of the groundmass. Separation of phenocrystic sanidine from salic melts provides an efficient method for raising the Rb content and lowering the K/Rb ratio of the melts, although the amount of differentiation probably is limited by continuous reequilibration of the alkalis between crystal and liquid phases through ion exchange. Syenites of cumulate origin will have appreciably lower Rb contents and higher K/Rb ratios than the melts from which they precipitated. Available data on the distribution of Rb between synthetic biotite and K-sanidine demonstrate that the separation of biotite probably will not deplete salic melts in Rb relative to K. ?? 1970 Springer-Verlag.

  17. Pt, Au, Pd and Ru Partitioning Between Mineral and Silicate Melts: The Role of Metal Nanonuggets

    Science.gov (United States)

    Malavergne, V.; Charon, E.; Jones, J.; Agranier, A.; Campbell, A.

    2012-01-01

    The partition coefficients of Pt and other Pt Group Elements (PGE) between metal and silicate D(sub Metal-Silicate) and also between silicate minerals and silicate melts D(sub Metal-Silicate) are among the most challenging coefficients to obtain precisely. The PGE are highly siderophile elements (HSE) with D(sub Metal-Silicate) >10(exp 3) due to the fact that their concentrations in silicates are very low (ppb to ppt range). Therefore, the analytical difficulty is increased by the possible presence of HSE-rich-nuggets in reduced silicate melts during experiments). These tiny HSE nuggets complicate the interpretation of measured HSE concentrations. If the HSE micro-nuggets are just sample artifacts, then their contributions should be removed before calculations of the final concentration. On the other hand, if they are produced during the quench, then they should be included in the analysis. We still don't understand the mechanism of nugget formation well. Are they formed during the quench by precipitation from precursor species dissolved homogeneously in the melts, or are they precipitated in situ at high temperature due to oversaturation? As these elements are important tracers of early planetary processes such as core formation, it is important to take up this analytical and experimental challenge. In the case of the Earth for example, chondritic relative abundances of the HSE in some mantle xenoliths have led to the concept of the "late veneer" as a source of volatiles (such as water) and siderophiles in the silicate Earth. Silicate crystal/liquid fractionation is responsible for most, if not all, the HSE variation in the martian meteorite suites (SNC) and Pt is the element least affected by these fractionations. Therefore, in terms of reconstructing mantle HSE abundances for Mars, Pt becomes a very important player. In the present study, we have performed high temperature experiments under various redox conditions in order to determine the abundances of Pt, Au

  18. Metal-silicate partitioning experiments in the diamond anvil cell: A comment on potential analytical errors

    Science.gov (United States)

    Wade, Jon; Wood, Bernard J.

    2012-02-01

    We have performed simulations of the electron microbeam analysis of metal-silicate partitioning experiments in which a small (˜50 μm) ball of metal is embedded in a silicate matrix. This geometry approximates that found in many high pressure diamond-cell experiments aimed at determining the partition coefficients (Di) of elements between metal and silicate. The simulations involved using the (publicly available) Monte Carlo simulation package PENEPMA which is based on the general-purpose electron-photon transport code PENELOPE. The code allows complex geometrical structures to be defined by quadric surfaces, which enclose homogeneous materials specified by the user. The package simulates both electron and photon transport, keeps track of the X-ray production mechanism and includes the continuum contribution. Our principal results came from simulating the effects of secondary fluorescence on the apparent metal-silicate partition coefficient of Ni for the case of an Ni-rich metal (26.8% Ni, 73.2% Fe) embedded in a silicate matrix. If, as is frequently the case, analysis of the silicate is performed 5-10 μm from the silicate-metal interface then secondary fluorescence of Ni in the metal will increase the apparent NiO concentration in the silicate by ˜1000 ppm. In the case considered, this is 25% of the Ni content of the silicate and the fluorescence effect decreases the apparent DNi from 110 to 84. For this type of experiment, therefore, the fluorescence effect reduces the apparent partition coefficient. We performed similar simulations of the analysis of the centre of a 10 μm diameter metal ball embedded in the silicate matrix to determine apparent Si and O concentrations in the metal. In this case, because the electrons do not penetrate so far into the metal, the fluorescence effect is very small and can be neglected. Finally, we show that focused ion beam (FIB) sections, while providing the potential physically to separate metal from silicate present

  19. Emission and extinction of ground and vapor-condensed silicates from 4 to 14 microns and the 10 micron silicate feature

    Science.gov (United States)

    Stephens, J. R.; Rusell, R. W.

    1979-01-01

    Emission and absorption spectra from 4 to 14 microns of ground and laser-vaporized olivine and enstatite silicates are compared with the 10-micron emission feature of the Orion Trapezium. The agreement in band center and shape between the amorphous laser-vaporized olivine sample and the Trapezium feature suggests that amorphous silicate grains of approximately olivine composition may be a major constituent of interstellar dust. Differences between the emission and absorption spectral profiles (absorption plus scattering) show characteristics that could be used as a sensitive probe of the morphology of interstellar grain systems when high signal-to-noise ratio (30-100) observational spectra become available.

  20. Experimental calibration of a new oxybarometer for silicic magmas based on vanadium partitioning between magnetite and silicate melt

    Science.gov (United States)

    Arató, Róbert; Audétat, Andreas

    2017-07-01

    Partition coefficients of vanadium between magnetite and rhyolitic silicate melt, DVmgt/melt, were experimentally determined as a function of oxygen fugacity (0.7-4.0 log units above the fayalite-magnetite-quartz buffer), temperature (800-1000 °C), melt alumina saturation index (ASI = 0.74-1.14), magnetite composition (0.2-14 wt% TiO2) and pressure (1-5 kbar; at H2O saturation). Experiments were performed by equilibrating small (≤20 μm), V-free magnetite grains in V-doped silicate melts (∼100 ppm V) and then analyzing both phases by LA-ICP-MS. Attainment of equilibrium was demonstrated by several reversal experiments. The results suggest that DVmgt/melt depends strongly on fO2, increasing by 1.5-1.7 log units from the MnO-Mn3O4 buffer to the Ni-NiO buffer, and to lesser (but still considerable) extents on melt alumina saturation index (ASI; increasing by 0.3-0.7 log units over 0.4 ASI units) and temperature (increasing by 0.3-0.7 log units over a 200 °C interval at a fixed fO2 buffer). Magnetite composition and melt water content seem to have negligible effects. The data were fitted by the following linear regression equation: in which temperature is given in K, ASI refers to molar Al2O3/(CaO + Na2O + K2O) and ΔFMQ refers to the deviation of fO2 (in log units) from the fayalite-magnetite-quartz buffer. This equation reproduces all of our data within 0.3 log units, and 89% of them within 0.15 log units. The main advantages of this new oxybarometer over classical magnetite-ilmenite oxybarometry are (1) that it can be applied to rocks that do not contain ilmenite, and (2) that it is easier to apply to slowly-cooled rocks such as granites.

  1. Adsorption of Free Fatty Acid from Crude Palm Oil on Magnesium Silicate Derived from Rice Husk

    Directory of Open Access Journals (Sweden)

    Pornsawan Assawasaengrat

    2011-07-01

    Full Text Available Magnesium silicate with various silica and magnesium oxide ratios (SiO2/MgO ratios was used as the adsorbent for a study of adsorption of free fatty acid (FFA in crude palm oil (CPO. Magnesium silicate was prepared from magnesium nitrate or magnesium sulfate solution precipitated with a solution of sodium silicate derived from rice husk. SiO2/MgO ratios of the magnesium silicate synthesized from magnesium nitrate and magnesium sulfate were 3.93, 3.75, 2.74, 2.40, 1.99 and 3.96, 3.61, 3.51, 2.91, 2.69, respectively. FFA adsorption on the magnesium silicate was carried out by adding 1 gram of the adsorbent to 50 grams of CPO and shaking for 1 hour at 50oC. It was found that SiO2/MgO ratio of 1.99 had the highest adsorption capacities of 185 mg of FFA per gram of adsorbent. In addition, increasing of SiO2/MgO ratios of magnesium silicate was found to reduce the adsorption capacities due to decreasing of FFA chemisorption. The effect of dosage amount to equilibrium adsorption capacities were carried out by adding different amount of magnesium silicate (SiO2/MgO ratio of 1.99 to 50 grams of CPO. The result showed that efficiency decreased when dosage increased. The Fruendlich and Langmuir isotherm were applied to describe this absorption system. The values of maximum sorption capacity (Q0 and Langmuir's sorption affinity (b in the Langmuir equation obtained by linear-regression were minus values which were physically meanigless. Thus, FFA adsorption on magnesium silicate was both physisorption and chemisorption and well represented by the Fruenlich isotherm.

  2. Synthesis and optical features of an europium organic-inorganic silicate hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Franville, A.C.; Zambon, D.; Mahiou, R.; Chou, S.; Cousseins, J.C. [Universite Blaise Pascal, Aubiere (France). Lab. des Materiaux Inorganiques; Troin, Y. [Laboratoire de Chimie des Heterocycles et des Glucides, EA 987, Universite Blaise-Pascal and ENSCCF, F-63177 Aubiere Cedex (France)

    1998-07-24

    A europium organic-inorganic silicate hybrid was synthesized by grafting a coordinative group (dipicolinic acid) to a silicate network precursor (3-aminopropyltriethoxysilane) via a covalent bonding. Sol-gel process and complexation were performed using different experimental conditions. The hybrid materials, in particular the Eu{sup 3+} coordination mode, were characterized by infrared and luminescence spectroscopies. Morphology of the materials and TG analysis showed that grafted silica enhanced thermal and mechanical resistances of the organic part. (orig.) 7 refs.

  3. Assessment of Fe(III) and Eu(III) complexation by silicate in aqueous solutions

    Science.gov (United States)

    Patten, James T.; Byrne, Robert H.

    2017-04-01

    Prior investigations of Eu3+ complexation by silicate have led to predictions that rare earth silicate complexes (REESiO(OH)32+) are the dominant species of REEs in deep waters of the Atlantic and Pacific Oceans. The proposed importance of REE-silicate complexes has been used as a foundation to explain oceanic REE profiles. In the present work, we examine the significance of rare earth element complexation by silicate ions. As one fundamental means of assessing prior depictions of REE-silicate formation constant behavior, our work examines the comparative stability constant behavior of Eu(III) and Fe(III). Plots of Eu(III) complexation constants against Fe(III) formation constants, in conjunction with experimental determinations of FeSiO(OH)32+ formation constants, indicate that previously published EuSiO(OH)32+ formation constants are substantially overestimated. Assessment of prior EuSiO(OH)32+ formation constant determinations reveals that results obtained in the presence and absence of silicic acid polymerization are inconsistent. Much larger EuSiO(OH)32+ formation constants are obtained in the presence of polymeric silica. Reanalysis of complexation results obtained under conditions of minimal silicate polymerization leads to a EuSiO(OH)32+ formation constant that is smaller than previously published estimates by as much as a factor of ∼25. The dramatically reduced magnitude of Siβ1(Eu) relative to previously published results indicates that the role of silicate complexation in oceanic REE cycling is much less significant than previously proposed. The spectrophotometric investigations of FeSiO(OH)32+ formation in the present study yield the first characterization of FeSiO(OH)32+ formation constant behavior as a function of ionic strength:

  4. (Isotope tracer studies of diffusion in silicates and of geological transport processes using actinide elements)

    Energy Technology Data Exchange (ETDEWEB)

    Wasserburg, G.J.

    1991-01-01

    This report consists of sections entitled resonance ionization mass spectrometry of Os, Mg self-diffusion in spinel and silicate melts, neotectonics: U-Th ages of solitary corals from the California coast, uranium-series evidence on diagenesis and hydrology of carbonates of Barbados, diffusion of H{sub 2}O molecules in silicate glasses, and development of an extremely high abundance sensitivity mass spectrometer.

  5. A MODEL FOR THE DUST ENVELOPE OF THE SILICATE CARBON STAR IRAS 09425-6040

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Kyung-Won, E-mail: kwsuh@chungbuk.ac.kr [Department of Astronomy and Space Science, Chungbuk National University, Cheongju-City, 28644 (Korea, Republic of)

    2016-03-01

    IRAS 09425-6040 (I09425) is a silicate carbon star with conspicuous crystalline silicate and water-ice features and emission excesses in the far-infrared and millimeter (mm) wavelength ranges. To understand properties of the dust envelope of I09425, we propose a physical model based on the observations and known properties of asymptotic giant branch stars and dust. We perform radiative transfer model calculations using multiple dust shells and disks with various dust species. We compare the model results with the observed spectral energy distribution (SED) acquired with different telescopes. We find that the physical model for I09425 using multiple shells of carbon and silicate dust and multiple disks of amorphous and crystalline silicates reproduces the observed SED fairly well. This object looks to have detached cold O-rich (silicate and water-ice) dust shells, which could be remnants of the recent chemical transition from O to C and an inner C-rich dust shell. A long-lived thin disk of very large silicate grains can reproduce the emission excess in the mm wavelength band and a recently formed thick disk of crystalline silicates can reproduce the prominent emission features in the spectral range 8–45 μm. The highly crystallized silicates could be recently formed by high temperature annealing due to the last O-rich superwind just before the chemical transition of the central star. I09425 could be a rare object that has the remnants of past O-rich stellar winds in the outer shells as well as in the circumbinary disks.

  6. Fungicides and silicate clay on the control of antracnosis in yellow passionfruit

    OpenAIRE

    Medeiros, André Martins; Autônomo; Peruch, Luiz Augusto Martins; Estação Experimental de Urussanga

    2012-01-01

    The anthracnose, caused by Glomerella cingulata (anamorf Colletotrichum gloeosporioides), is the most important fungal disease for aerial parts of yellow passionfruit. However, few studies about anthracnose control in field conditions have been published. The objective of this research was to evaluate silicate clay and fungicides for anthracnose control. Treatments evaluated were: tebuconazole (20g i.a./100L), copper oxychloride (180g i.a./100L), silicate clay (15g /L) and control (untreated ...

  7. Molecular Dynamics Modeling of Hydrated Calcium-Silicate-Hydrate (CSH) Cement Molecular Structure

    Science.gov (United States)

    2014-08-30

    paste consisting of starting configuration of dry cement powder and water mixture by itself is a complex, multi-scale material system. Though...high pressure molecular structural behavior of the hydrated CSH. Portland cement in the powder form consists of four different major constituents...Tricalcium silicate (C3S), Di-Calcium silicate (C2S), Tri-Calcium aluminate (C3A), and Tetra calcium aluminoferrite (C4AF) [1]. Different mixture

  8. AC electrical breakdown phenomena of epoxy/layered silicate nanocomposite in needle-plate electrodes.

    Science.gov (United States)

    Park, Jae-Jun; Lee, Jae-Young

    2013-05-01

    Epoxy/layered silicate nanocomposite for the insulation of heavy electric equipments were prepared by dispersing 1 wt% of a layered silicate into an epoxy matrix with a homogenizing mixer and then AC electrical treeing and breakdown tests were carried out. Wide-angle X-ray diffraction (WAXD) analysis and transmission electron microscopy (TEM) observation showed that nano-sized monolayers were exfoliated from a multilayered silicate in the epoxy matrix. When the nano-sized silicate layers were incorporated into the epoxy matrix, the breakdown rate in needle-plate electrode geometry was 10.6 times lowered than that of the neat epoxy resin under the applied electrical field of 520.9 kV/mm at 30 degrees C, and electrical tree propagated with much more branches in the epoxy/layered silicate nanocomposite. These results showed that well-dispersed nano-sized silicate layers retarded the electrical tree growth rate. The effects of applied voltage and ambient temperature on the tree initiation, growth, and breakdown rate were also studied, and it was found that the breakdown rate was largely increased, as the applied voltage and ambient temperature increased.

  9. Silicate Earth’s missing niobium may have been sequestered into asteroidal cores

    Science.gov (United States)

    Münker, Carsten; Fonseca, Raúl O. C.; Schulz, Toni

    2017-11-01

    Geochemical models describing the behaviour of niobium during Earth’s growth rely on the general paradigm that niobium was delivered by Earth’s asteroidal building blocks at chondritic abundances. This paradigm is based on the observation that niobium is traditionally regarded as a refractory and strongly lithophile element, and thus stored in the silicate portions of Earth and differentiated asteroids. However, Earth’s silicate mantle is instead selectively depleted in niobium, in marked contrast to the silicate mantles of many asteroids and smaller planets that apparently lack any significant depletion in niobium. Here we present results of high-precision measurements for niobium and other lithophile elements in representative meteorites from various small differentiated asteroids. Our data, along with the results of low-pressure experiments, show that in more reduced asteroids--such as Earth’s first building blocks--niobium is moderately chalcophile and more so than its geochemical twin tantalum by an order of magnitude. Accordingly, niobium can be sequestered into the cores of more reduced asteroids during differentiation via the segregation of sulfide melts in a carbon-saturated environment. We suggest that the niobium deficit in Earth’s silicate mantle may be explained by the Earth’s silicate mantle preferentially accreting the silicate portions of reduced asteroidal building blocks.

  10. The Preparation of Flaky Layered Carbon by Using Layered Silicate Template

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Oh Yun [Yosu National University, Yeosu (Korea, Republic of); Park, Kyeong Won [Gyeongsang National University, Jinju (Korea, Republic of)

    2003-11-15

    Porous layered carbons with well-developed flake structure were successfully prepared by using layered silicate template. The gallery of layered silicate is composed of two-dimensional spaces with nano scale, which can have a role as nano reactor for chemicals introduced into the gallery. It confirmed that PFO, in this nano reactor, could be transformed easily to layered carbon or graphite structure by the heat treatment, allowing layered carbon-layered silicate nanocomposite (LC-LSN) piled carbon film or graphite sheet in layers of layered silicate. The removal of template from LC-LSN resulted in separated and well-developed flaky layered carbon or graphite with large surface area of 160-240 m{sup 2}/g, which was quite different from carbon black and activated carbon. In recent years, the preparation and application of nanostructure carbon materials such as carbon nanotube and nanoporous carbon has attracted increasing interests. We now report on the preparation of flaky layered carbon by using layered silicates as template. These layered carbons should be applicable potentially in technical field such as the electronics, catalytic and hydrogen-storage system. Layered silicates have exchangeable cations such as Na{sup +}, K{sup +}, Ca{sup 2+} and Mg{sup 2+} in the interlayer space.

  11. Trends in the adsorption and reactivity of hydrogen on magnesium silicate nanoclusters.

    Science.gov (United States)

    Oueslati, Ichraf; Kerkeni, Boutheïna; Bromley, Stefan T

    2015-04-14

    We study nanoclusters of Mg-rich olivine and pyroxene (having (MgO)6(SiO2)3 and (MgO)4(SiO2)4 compositions) with respect to their reactivity towards hydrogen atoms, using density functional calculations. Ultrasmall silicate particles are fundamental intermediates in cosmic dust grain formation and processing, and are thought to make up a significant mass fraction of the grain population. Due to their nanoscale dimensions and high surface area to bulk ratios, they are likely to also have a disproportionately large influence on surface chemistry in the interstellar medium. This work investigates the potential role of silicate nanoclusters in vital interstellar hydrogen-based chemistry by studying atomic H adsorption and H2 formation. Our extensive set of calculations confirm the generality of a Brønsted-Evans-Polanyi (BEP) relation between the H2 reaction barrier and the 2Hchem binding energy, suggesting it to be independent of silicate dust grain shape, size, crystallinity and composition. Our results also suggest that amorphous/porous grains with forsteritic composition would tend to dissociate H2, but relatively Mg-poor silicate grains (e.g. enstatite composition) and/or more crystalline/compact silicate grains would tend to catalyse H2 formation. The high structural thermostability of silicate nanoclusters with respect to the heat released during exothermic H2 formation reactions is also verified.

  12. [Effects of silicate on the community structure of phytoplankton in enclosures].

    Science.gov (United States)

    Sun, Ling; Jin, Xiang-can; Yang, Wei; Xu, Min; Zhong, Yuan; Zhu, Lin; Zhuang, Yuan-yi

    2007-10-01

    Controlling the concentrations of silicate, enclosure experiments were conducted in Xinkai Lake to investigate the influence of Si concentration on the growth and succession of phytoplankton communities in a eutrophic freshwater. The results show that with the addition of silicate, the biomass of diatoms increased and the ratio of diatom species to the total significantly increased from 10.2% to 22.1% . While the species percent of Cyanobacteria and Chlorophyta decreased to 61.5%, as compared with 76.8% in control. Several diatom species, such as Synedra ulna, Nitzschia denticula, Nitzschia acicularis, Gomphonema constrictum var. capitata, Gomphonema olivaceum, which were not found in control, were observed in the silicate-enriched treatments. The Shannon indices of 2.17 +/- 0.40 and 2.12 +/- 0.21 were obtained from the medium-Si (atomic ratio N:Si:P = 16:8:1) and high-Si ( N:Si:P = 16:16:1) treatments, which were higher than that of the control enclosure (1.89 +/- 0.55, without silicate addition). At the late phase of the experiments, algal blooms mainly composed of Microcystis aeruginosa appeared in control but not in the silicate-enriched enclosures. The enrichment of silicate can promote the growth of diatoms and the other algal species and change the dominance of few Cyanobacteria and Chlorophyte species. Therefore, it can elevate the algal biodiversity of an aquatic ecosystem and weaken the cyanobacterial blooms to a certain degree.

  13. SON68 glass dissolution driven by magnesium silicate precipitation

    Science.gov (United States)

    Fleury, Benjamin; Godon, Nicole; Ayral, André; Gin, Stéphane

    2013-11-01

    Experimental results are reported on the effect of magnesium silicate precipitation on the mechanisms and rate of borosilicate glass dissolution. Leaching experiments with SON68 glass, a borosilicate containing no Mg, were carried out in initially deionized water at 50 °C with a glass-surface-area-to-solution-volume ratio of 20,000 m-1. After 29 days of alteration the experimental conditions were modified by the addition of Mg to trigger the precipitation of Mg-silicate. Additional experiments were conducted to investigate the importance of other parameters such as pH or dissolved silica on the mechanisms of precipitation of Mg-silicates and their consequences on the glass dissolution rate. Mg-silicates precipitate immediately after Mg is added. The amount of altered glass increases with the quantity of added Mg, and is smaller when silicon is added in solution. A time lag is observed between the addition of magnesium and the resumption of glass alteration because silicon is first provided by partial dissolution of the previously formed alteration gel. It is shown that nucleation does not limit Mg-silicate precipitation. A pH above 8 is necessary for the phase to precipitate under the investigated experimental conditions. On the other hand the glass alteration kinetics limits the precipitation if the magnesium is supplied in solution at a non-limiting rate. The concentration of i in solution was analyzed as well as that of boron. The quantity of i released from the glass is estimated with the assumption that i and B are released congruently at the glass dissolution front. The remained quantity of the element i is then supposed to be in the gel or in the secondary phase. In this paper, we do not make a difference between gel and hydrated glass using the same word 'gel' whereas Gin et al. [40] makes this difference. Recent papers [40,41] discussed about different key issues related to the passivation properties of the alteration layer including the hydrated glass

  14. Water-bearing, high-pressure Ca-silicates

    Science.gov (United States)

    Németh, Péter; Leinenweber, Kurt; Ohfuji, Hiroaki; Groy, Thomas; Domanik, Kenneth J.; Kovács, István J.; Kovács, Judit S.; Buseck, Peter R.

    2017-07-01

    Water-bearing minerals provide fundamental knowledge regarding the water budget of the mantle and are geophysically significant through their influence on the rheological and seismic properties of Earth's interior. Here we investigate the CaO-SiO2-H2O system at 17 GPa and 1773 K, corresponding to mantle transition-zone condition, report new high-pressure (HP) water-bearing Ca-silicates and reveal the structural complexity of these phases. We document the HP polymorph of hartrurite (Ca3SiO5), post-hartrurite, which is tetragonal with space group P4/ncc, a = 6.820 (5), c = 10.243 (8) Å, V = 476.4 (8) Å3, and Z = 4, and is isostructural with Sr3SiO5. Post-hartrurite occurs in hydrous and anhydrous forms and coexists with larnite (Ca2SiO4), which we find also has a hydrous counterpart. Si is 4-coordinated in both post-hartrurite and larnite. In their hydrous forms, H substitutes for Si (4H for each Si; hydrogrossular substitution). Fourier transform infrared (FTIR) spectroscopy shows broad hydroxyl absorption bands at ∼3550 cm-1 and at 3500-3550 cm-1 for hydrous post-hartrurite and hydrous larnite, respectively. Hydrous post-hartrurite has a defect composition of Ca2.663Si0.826O5H1.370 (5.84 weight % H2O) according to electron-probe microanalysis (EPMA), and the Si deficiency relative to Ca is also observed in the single-crystal data. Hydrous larnite has average composition of Ca1.924Si0.851O4H0.748 (4.06 weight % H2O) according to EPMA, and it is in agreement with the Si occupancy obtained using X-ray data collected on a single crystal. Superlattice reflections occur in electron-diffraction patterns of the hydrous larnite and could indicate crystallographic ordering of the hydroxyl groups and their associated cation defects. Although textural and EPMA-based compositional evidence suggests that hydrous perovskite may occur in high-Ca-containing (or low silica-activity) systems, the FTIR measurement does not show a well-defined hydroxyl absorption band for this

  15. Combined effect of carbonate and biotite dissolution in landslides biases silicate weathering proxies

    Science.gov (United States)

    Emberson, R.; Galy, A.; Hovius, N.

    2017-09-01

    Long-term estimates of the dissolution of silicate rock are generally derived from a range of isotopic proxies, such as the radiogenic strontium isotope ratio (87Sr/86Sr), which are preserved in sediment archives. For these systems to fairly represent silicate weathering, the changes in isotopic ratios in terrestrial surface waters should correspond to changes in the overall silicate dissolution. This assumes that the silicate mineral phases that act as sources of a given isotope dissolve at a rate that is proportional to the overall silicate weathering. Bedrock landsliding exhumes large quantities of fresh rock for weathering in transient storage, and rapid weathering in these deposits is controlled primarily by dissolution of the most reactive phases. In this study, we test the hypothesis that preferential weathering of these labile minerals can decouple the dissolution of strontium sources from the actual silicate weathering rates in the rapidly eroding Western Southern Alps (WSA) of New Zealand. We find that rapid dissolution of relatively radiogenic calcite and biotite in landslides leads to high local fluxes in strontium with isotopic ratios that offer no clear discrimination between sources. These higher fluxes of radiogenic strontium are in contrast to silicate weathering rates in landslides that are not systematically elevated. On a mountain belt scale, radiogenic strontium fluxes are not coupled to volumes of recent landslides in large (>100 km2) catchments, but silicate weathering fluxes are. Such decoupling is likely due first to the broad variability in the strontium content of carbonate minerals, and second to the combination of radiogenic strontium released from both biotite and carbonate in recent landslides. This study supports previous work suggesting the limited utility of strontium isotopes as a system to study silicate weathering in the WSA. Crucially however, in settings where bedrock landsliding is a dominant erosive process there is

  16. Sodium silicate solutions from dissolution of glasswastes. Statistical analysis

    Directory of Open Access Journals (Sweden)

    Torres-Carrasco, M.

    2014-05-01

    Full Text Available It has studied the solubility process of four different waste glasses (with different particle sizes, 125 µm in alkaline solutions (NaOH and NaOH/Na₂CO₃ and water as a reference and under different conditions of solubility (at room temperature, at 80°C and a mechano-chemical process. Have established the optimal conditions of solubility and generation of sodium silicates solutions, and these were: the smaller particle size (Se ha estudiado el proceso de solubilidad de cuatro diferentes residuos vítreos (con distintas granulometrías, 125 µm en disoluciones alcalinas de NaOH y NaOH/Na₂CO₃ y agua como medio de referencia y bajo distintas condiciones de solubilidad (a temperatura ambiente, a 80°C y con un proceso mecano-químico. Se han establecido las condiciones óptimas de solubilidad y generación de disoluciones de silicato sódico, y estas son: menor tamaño de partícula del residuo vítreo (inferior a 45 µm, con la disolución de NaOH/Na₂CO₃ y tratamiento térmico a 80°C durante 6 horas de agitación. El análisis estadístico realizado a los resultados obtenidos da importancia a las variables estudiadas y a las interacciones de las mismas. A través de ²⁹Si RMN MAS se ha confirmado la formación, tras los procesos de disolución, de un silicato monomérico, apto para su utilización como activador en la preparación de cementos y hormigones alcalinos.

  17. Fluorinated silicate glass for conventional and holographic optical elements

    Science.gov (United States)

    Glebov, Leonid

    2007-04-01

    This presentation is a survey of results of a long-term research at the laboratory of photoinduced processes at CREOL/UCF. A highly homogeneous and transparent sodium-zinc-aluminum-silicate glass doped with fluorine and bromine was developed. Glass is transparent from 220 to 2700 nm. It is a crown-type optical glass having refractive index at 587.5 nm nd=1.4959 and Abbe number νd=59.2. This glass shows low dependence of refractive index on temperature dn/dtGlass can withstand multi-kilowatt laser beams. Nonlinear refractive index is the same as for fused silica. Laser damage threshold for 8 ns is about 40 /cm2. This glass becomes a photosensitive one by doping with silver and cerium. It demonstrates refractive index decrement after exposure to UV radiation followed by thermal development and therefore is used for phase volume hologram recording. Spatial modulation of refractive index resulted from precipitation of nano-crystalline phase of sodium fluoride. The main mechanism of refractive index decrement is a photoelastic effect resulted from strong tensions generated in both crystalline and vitreous phases because of difference in their coefficients of thermal expansion. Volume Bragg gratings recorded in this glass, show extremely narrow spectral and angular selectivity and have low losses combined with high tolerance to laser radiation. These gratings possess a unique ability to produce laser beam transformations directly in angular space. This feature paves a way to creation of high power lasers with stable narrow emission spectra and diffraction limited divergence.

  18. On the origin of silicate-bearing diamondites

    Science.gov (United States)

    Dobosi, Gabor; Kurat, Gero

    2010-05-01

    Garnets and clinopyroxenes, intergrown with diamonds in 37 diamondites (“bort”, “polycrystalline diamond aggregates”, “polycrystalline diamond”, “framesite”), presumably from southern Africa, were analyzed for trace element contents by LA-ICP-MS. The intimate diamond-silicate intergrowths suggest that both precipitated from the same fluids during the same crystallization events. In this study we distinguish 5 chemical garnet groups: “peridotitic” (P), intermediate (I) and 3 “eclogitic” groups (E1, E2 and E3). Chondrite-normalized trace element patterns for the garnet groups roughly correlate with major element abundances. Most of P garnets show complex, mildly sinusoidal REEN patterns with relatively flat HREEN-MREEN, a small hump at Sm-Nd and depleted LREEN, and have relatively high contents of Nb, Ta, U, and Th. The REEN abundance patterns of E garnets differ by showing a continuous increase from LREE to HREE and depletion in LREE and highly incompatible elements relative to the P garnets. Of all garnet groups, E3 garnets are the poorest in highly incompatible trace elements and in Mg. Model equilibrium fluids for P garnets suggest crystallization from magnesian carbonate-bearing fluids/melts, which were very rich in incompatible trace elements — similar to kimberlites. Hypothetical equilibrium melts for E1 and E2 garnets are also magnesian and poorer in LREE and highly incompatible elements relative to typical kimberlitic or carbonatitic melts. Fluids that crystallized the P and most of the E garnets have similar mg numbers indicating a peridotitic source for both. The differences in Cr and highly incompatible element contents can be the result of differences in fluid formation and/or evolution rather than different source rock. The positive correlation of Cr2O3 and mg with the abundances of highly incompatible elements in garnets indicate fluid-rock fractionation processes rather than igneous fractional crystallization processes being

  19. Modeling Silicate Weathering for Elevated CO2 and Temperature

    Science.gov (United States)

    Bolton, E. W.

    2016-12-01

    A reactive transport model (RTM) is used to assess CO2 drawdown by silicate weathering over a wide range of temperature, pCO2, and infiltration rates for basalts and granites. Although RTM's have been used extensively to model weathering of basalts and granites for present-day conditions, we extend such modeling to higher CO2 that could have existed during the Archean and Proterozoic. We also consider a wide range of surface temperatures and infiltration rates. We consider several model basalt and granite compositions. We normally impose CO2 in equilibrium with the various atmospheric ranges modeled and CO2 is delivered to the weathering zone by aqueous transport. We also consider models with fixed CO2 (aq) throughout the weathering zone as could occur in soils with partial water saturation or with plant respiration, which can strongly influence pH and mineral dissolution rates. For the modeling, we use Kinflow: a model developed at Yale that includes mineral dissolution and precipitation under kinetic control, aqueous speciation, surface erosion, dynamic porosity, permeability, and mineral surface areas via sub-grid-scale grain models, and exchange of volatiles at the surface. Most of the modeling is done in 1D, but some comparisons to 2D domains with heterogeneous permeability are made. We find that when CO2 is fixed only at the surface, the pH tends toward higher values for basalts than granites, in large part due to the presence of more divalent than monovalent cations in the primary minerals, tending to decrease rates of mineral dissolution. Weathering rates increase (as expected) with increasing CO2 and temperature. This modeling is done with the support of the Virtual Planetary Laboratory.

  20. Removal of lead from cathode ray tube funnel glass by generating the sodium silicate.

    Science.gov (United States)

    Hu, Biao; Zhao, Shuangshuang; Zhang, Shuhao

    2015-01-01

    In the disposal of electronic waste, cathode ray tube (CRT) funnel glass is an environmental problem of old television sets. Removal of the lead from CRT funnel glass can prevent its release into the environment and allow its reuse. In this research, we reference the dry progress productive technology of sodium silicate, the waste CRT glass was dealt with sodium silicate frit melted and sodium silicate frit dissolved. Adding a certain amount of Na ₂CO₃to the waste CRT glass bases on the material composition and content of it, then the specific modulus of sodium silicate frit is obtained by melting progress. The silicon, potassium and sodium compounds of the sodium silicate frit are dissolved under the conditions of high temperature and pressure by using water as solvent, which shows the tendency that different temperature, pressure, liquid-solid ratio and dissolving time have effect on the result of dissolving. At 175°C(0.75MPa), liquid-solid ratio is 1.5:1, the dissolving time is 1h, the dissolution rate of sodium silicate frit is 44.725%. By using sodium sulfide to separate hydrolysis solution and to collect lead compounds in the solution, the recovery rate of lead in dissolving reached 100% and we can get clean sodium silicate and high purity of lead compounds. The method presented in this research can recycle not only the lead but also the sodium, potassium and other inorganic minerals in CRT glass and can obtain the comprehensive utilization of leaded glass.

  1. Polymer/Silicate Nanocomposites Used to Manufacture Gas Storage Tanks With Reduced Permeability

    Science.gov (United States)

    Campbell, Sandi G.; Johnston, Chris

    2004-01-01

    Over the past decade, there has been considerable research in the area of polymer-layered silicate nanocomposites. This research has shown that the dispersion of small amounts of an organically modified layered silicate improves the polymer strength, modulus, thermal stability, and barrier properties. There have been several reports on the dispersion of layered silicates in an epoxy matrix. Potential enhancements to the barrier properties of epoxy/silicate nanocomposites make this material attractive for low permeability tankage. Polymer matrix composites (PMCs) have several advantages for cryogenic storage tanks. They are lightweight, strong, and stiff; therefore, a smaller fraction of a vehicle's potential payload capacity is used for propellant storage. Unfortunately, the resins typically used to make PMC tanks have higher gas permeability than metals. This can lead to hydrogen loss through the body of the tank instead of just at welds and fittings. One approach to eliminate this problem is to build composite tanks with thin metal liners. However, although these tanks provide good permeability performance, they suffer from a substantial mismatch in the coefficient of thermal expansion, which can lead to failure of the bond between the liner and the body of the tank. Both problems could be addressed with polymersilicate nanocomposites, which exhibit reduced hydrogen permeability, making them potential candidates for linerless PMC tanks. Through collaboration with Northrop Grumman and Michigan State University, nanocomposite test tanks were manufactured for the NASA Glenn Research Center, and the helium permeability was measured. An organically modified silicate was prepared at Michigan State University and dispersed in an epoxy matrix (EPON 826/JeffamineD230). The epoxy/silicate nanocomposites contained either 0 or 5 wt% of the organically modified silicate. The tanks were made by filament winding carbon fibers with the nanocomposite resin. Helium permeability

  2. Experimental Investigation of Irradiation-driven Hydrogen Isotope Fractionation in Analogs of Protoplanetary Hydrous Silicate Dust

    Science.gov (United States)

    Roskosz, Mathieu; Laurent, Boris; Leroux, Hugues; Remusat, Laurent

    2016-11-01

    The origin of hydrogen in chondritic components is poorly understood. Their isotopic composition is heavier than the solar nebula gas. In addition, in most meteorites, hydrous silicates are found to be lighter than the coexisting organic matter. Ionizing irradiation recently emerged as an efficient hydrogen fractionating process in organics, but its effect on H-bearing silicates remains essentially unknown. We report the evolution of the D/H of hydrous silicates experimentally irradiated by electrons. Thin films of amorphous silica, amorphous “serpentine,” and pellets of crystalline muscovite were irradiated at 4 and 30 keV. For all samples, irradiation leads to a large hydrogen loss correlated with a moderate deuterium enrichment of the solid residue. The entire data set can be described by a Rayleigh distillation. The calculated fractionation factor is consistent with a kinetically controlled fractionation during the loss of hydrogen. Furthermore, for a given ionizing condition, the deuteration of the silicate residues is much lower than the deuteration measured on irradiated organic macromolecules. These results provide firm evidence of the limitations of ionizing irradiation as a driving mechanism for D-enrichment of silicate materials. The isotopic composition of the silicate dust cannot rise from a protosolar to a chondritic signature during solar irradiations. More importantly, these results imply that irradiation of the disk naturally induces a strong decoupling of the isotopic signatures of coexisting organics and silicates. This decoupling is consistent with the systematic difference observed between the heavy organic matter and the lighter water typically associated with minerals in the matrix of most carbonaceous chondrites.

  3. Physical processes affecting availability of dissolved silicate for diatom production in the Arabian Sea

    Science.gov (United States)

    Young, David K.; Kindle, John C.

    1994-11-01

    A passive tracer to represent dissolved silicate concentrations, with biologically realistic uptake kinetics, is successfully incorporated into a three-dimensional, eddy-resolving, ocean circulation model of the Indian Ocean. Hypotheses are tested to evaluate physical processes which potentially affect the availability of silicate for diatom production in the Arabian Sea. An alternative mechanism is offered to the idea that open ocean upwelling is primarily responsible for the high, vertical nutrient flux and consequent large-scale phytoplankton bloom in the northwestern Arabian Sea during the southwest monsoon. Model results show that dissolved silicate in surface waters available for uptake by diatoms is primarily influenced by the intensity of nearshore upwelling from southwest monsoonal wind forcing and by the offshore advective transport of surface waters. The upwelling, which in the model occurs within 200±50 km of the coast, appears to be a result of a combination of coastal upwelling, Ekman pumping, and divergence of the coastal flow as it turns offshore. Localized intensifications of silicate concentrations appear to be hydrodynamically driven and geographically correlated to coastal topographic features. The absence of diatoms in sediments of the eastern Arabian Basin is consistent with modeled distributional patterns of dissolved silicate resulting from limited westward advection of upwelled coastal waters from the western continental margin of India and rapid uptake of available silicate by diatoms. Concentrations of modeled silicate become sufficiently low to become unavailable for diatom production in the eastern Arabian Sea, a region between 61°E and 70°E at 8°N on the south, with the east and west boundaries converging on the north at ˜67°E, 20°N.

  4. Experimental calibration of a new oxybarometer for silicic magmas based on the partitioning of vanadium between magnetite and silicate melt

    Science.gov (United States)

    Arató, Róbert; Audétat, Andreas

    2016-04-01

    Oxygen fugacity is an important parameter in magmatic systems that affects the stability of mineral phases and fluid species. However, there is no well-established method to reconstruct the oxygen fugacity of slowly cooled magmas such as granite, for example, because existing oxybarometers (e.g., magnetite-ilmenite method) are susceptible to re-equilibration processes during slow cooling and thus lead to erroneous results when applied for granitic rocks. In this study, we aim at developing an oxybarometer that is based on the partitioning of vanadium (a redox-sensitive element) between magnetite inclusions and silicate melt inclusions preserved in quartz phenocrysts, where they were protected from subsolidus alteration and can be measured as entities by LA-ICP-MS. In the first - experimental - part of this study we investigated the effects of temperature (800-950 ° C), pressure (1-2 kbar), oxygen fugacity (from ΔFMQ+0.7 to ΔFMQ+4.0), magnetite composition, and melt composition on the partition coefficient of vanadium between magnetite and melt (DVmgt-melt). The experiments were carried out in cold-seal pressure vessels and the starting material was a mixture of V-doped haplogranite glasses or natural obsidian powder with variable aluminum saturation index (ASI), and synthetic, V-free magnetite of 10-20 μm grain size. The vanadium partition coefficient was found to depend strongly on oxygen fugacity, and to lesser (but still considerable) degrees on melt composition and temperature. A more than 1.5 log unit decrease in DVmgt-melt values with increasing oxygen fugacity can be explained by a change of the dominant valence state of V in the silicate melt. For a given oxygen fugacity buffer DVmgt-melt decreases with increasing temperature, but this reflects mostly the change in absolute fO2 values while the net temperature effect is in fact positive. DVmgt-melt depends significantly on melt composition, resulting in higher D-values with increasing aluminum

  5. Retrospective evaluation of bone pain palliation after samarium-153-EDTMP therapy Avaliação retrospectiva do tratamento da dor óssea metastática com Samário-153-EDTMP

    Directory of Open Access Journals (Sweden)

    Marcelo Tatit Sapienza

    2004-01-01

    Full Text Available PURPOSE: The aim of this study was to evaluate the degree of metastatic bone pain palliation and medullar toxicity associated with samarium-153-EDTMP treatment. METHODS: Seventy-three patients with metastatic bone pain having previously undergone therapy with samarium-153-EDTMP (1 mCi/kg were retrospectively evaluated. Routine follow-up included pain evaluation and blood counts for 2 months after treatment. Pain was evaluated using a subjective scale (from 0 to 10 before and for 8 weeks after the treatment. Blood counts were obtained before treatment and once a week for 2 months during follow-up. Dosimetry, based upon the urinary excretion of the isotope, was estimated in 41 individuals, and the resulting radiation absorbed doses were correlated with hematological data. RESULTS: Reduction in pain scores of 75% to 100% was obtained in 36 patients (49%, with a decrease of 50% to 75%, 25% to 50%, and 0% to 25% in, respectively, 20 (27%, 10 (14%, and 7 (10% patients. There was no significant relationship between the pain response and location of the primary tumor (breast or prostate cancer. Mild to moderate myelosuppression was noted in 75.3% of patients, usually with hematological recovery at 8 weeks. The mean bone marrow dose was 347 ± 65 cGy, and only a weak correlation was found between absorbed dose and myelosuppression (Pearson coefficient = .4. CONCLUSIONS: Samarium-153-EDTMP is a valuable method for metastatic bone pain palliation. A mild to moderate and transitory myelosuppression is the main toxicity observed after samarium therapy, showing a weak correlation with dosimetric measures.OBJETIVO: O presente trabalho teve por objetivo avaliar o efeito paliativo da dor e a toxicidade medular associados ao tratamento com Samário-153-EDTMP em pacientes com metástases ósseas. MÉTODOS: O estudo foi realizado de forma retrospectiva, a partir do levantamento de prontuário de 178 pacientes submetidos a tratamento com 1mCi/kg de 153Sm

  6. The dynamics of the laser-induced metal-semiconductor phase transition of samarium sulfide (SmS); Die Dynamik des laserinduzierten Metall-Halbleiter-Phasenuebergangs von Samariumsulfid (SmS)

    Energy Technology Data Exchange (ETDEWEB)

    Kaempfer, Tino

    2009-12-15

    The present thesis is dedicated to the experimental study of the metal-semiconductor phase transition of samarium sulfide (SmS): Temperature- and time-resolved experiments on the characterization of the phase transition of mixed-valence SmS samples (M-SmS) are presented. The measurement of the dynamics of the laser-induced phase transition pursues via time-resolved ultrashort-time microscopy and by X-ray diffraction with sub-picosecond time resolution. The electronic and structural processes, which follow an excitation of M-SmS with infrared femtosecond laser pulses, are physically interpreted on the base of the results obtained in this thesis and model imaginations. [German] Die vorliegende Arbeit ist der experimentellen Untersuchung des Metall-Halbleiter-Phasenuebergangs von Samariumsulfid (SmS) gewidmet. Es werden temperatur- und zeitaufgeloeste Experimente zur Charakterisierung des Phasenuebergangs gemischt-valenter SmS Proben (M-SmS) vorgestellt. Die Messung der Dynamik des laserinduzierten Phasenuebergangs erfolgt ueber zeitaufgeloeste Ultrakurzzeit-Mikroskopie und durch Roentgenbeugung mit subpikosekunden Zeitaufloesung. Die elektronischen und strukturellen Prozesse, welche einer Anregung von M-SmS mit infraroten Femtosekunden-Laserpulsen folgen, werden auf der Basis der in dieser Arbeit gewonnenen Ergebnisse und Modellvorstellungen physikalisch interpretiert. (orig.)

  7. Asbestos and silicate pollution: Public health. July 1976-March 1989 (Citations from Pollution Abstracts). Report for July 1976-March 1989

    Energy Technology Data Exchange (ETDEWEB)

    1989-06-01

    This bibliography contains citations concerning the occurence and effects of asbestos and silicate pollution as a public health risk. This bibliography covers research on the epidemiological and medical studies involving exposure to asbestos and silicates, ingestion of asbestos, and methods to measure asbestos and silicate pollution. Topics include cancer risks, asbestos in drinking water, hazards of silica dust inahalation, and hazard management and abatement. Asbestos and silicate pollution in the workplace, and asbestos removal technology are found in separate published bibliographies. (Contains 104 citations fully indexed and including a title list.)

  8. The utilization of waste by-products for removing silicate from mineral processing wastewater via chemical precipitation.

    Science.gov (United States)

    Kang, Jianhua; Sun, Wei; Hu, Yuehua; Gao, Zhiyong; Liu, Runqing; Zhang, Qingpeng; Liu, Hang; Meng, Xiangsong

    2017-11-15

    This study investigates an environmentally friendly technology that utilizes waste by-products (waste acid and waste alkali liquids) to treat mineral processing wastewater. Chemical precipitation is used to remove silicate from scheelite (CaWO4) cleaning flotation wastewater and the waste by-products are used as a substitute for calcium chloride (CaCl2). A series of laboratory experiments is conducted to explain the removal of silicate and the characterization and formation mechanism of calcium silicate. The results show that silicate removal reaches 90% when the Ca:Si molar ratio exceeds 1.0. The X-ray diffraction (XRD) results confirm the characterization and formation of calcium silicate. The pH is the key factor for silicate removal, and the formation of polysilicic acid with a reduction of pH can effectively improve the silicate removal and reduce the usage of calcium. The economic analysis shows that the treatment costs with waste acid (0.63 $/m(3)) and waste alkali (1.54 $/m(3)) are lower than that of calcium chloride (2.38 $/m(3)). The efficient removal of silicate is confirmed by industrial testing at a plant. The results show that silicate removal reaches 85% in the recycled water from tailings dam. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. The microstructure and surface morphology of radiopaque tricalcium silicate cement exposed to different curing conditions.

    Science.gov (United States)

    Formosa, L M; Mallia, B; Bull, T; Camilleri, J

    2012-05-01

    Tricalcium silicate is the major constituent phase in mineral trioxide aggregate (MTA). It is thus postulated that pure tricalcium silicate can replace the Portland cement component of MTA. The aim of this research was to evaluate the microstructure and surface characteristics of radiopaque tricalcium silicate cement exposed to different curing conditions namely at 100% humidity or immersed in either water or a simulated body fluid at 37°C. The materials under study included tricalcium silicate and Portland cements with and without the addition of bismuth oxide radiopacifier. Material characterization was performed on hydrated cements using a combination of scanning electron microscopy (SEM) with X-ray energy dispersive (EDX) analyses and X-ray diffraction (XRD) analyses. Surface morphology was further investigated using optical profilometry. Testing was performed on cements cured at 100% humidity or immersed in either water or Hank's balanced salt solution (HBSS) for 1 and 28 days at 37°C. In addition leachate analysis was performed by X-ray fluorescence of the storage solution. The pH of the storage solution was assessed. All the cements produced calcium silicate hydrate and calcium hydroxide on hydration. Tricalcium silicate showed a higher reaction rate than Portland cement and addition of bismuth oxide seemed to also increase the rate of reaction with more calcium silicate hydrate and calcium hydroxide being produced as demonstrated by SEM and XRD analysis and also by surface deposits viewed by the optical profilometer. Cement immersion in HBSS resulted in the deposition of calcium phosphate during the early stages following immersion and extensive calcification after 28 days. The pH of all storage solutions was alkaline. The immersion in distilled water resulted in a higher pH of the solution than when the cements were immersed in HBSS. Leachate analysis demonstrated high calcium levels in all cements tested with higher levels in tricalcium silicate and

  10. Electrical conduction and glass relaxation in alkali- silicate glasses

    Science.gov (United States)

    Angel, Paul William

    Electrical response measurements from 1 Hz to 1 MHz between 50o and 540oC were made on potassium, sodium and lithium-silicate glasses with low alkali oxide contents. Conductivity and electrical relaxation responses for both annealed and air quenched glasses of the same composition were compared. Quenching was found to lower the dc conductivity, σdc, and activation energy as well as increase the pre-exponential term when compared to the corresponding annealed glass of the same composition. All of the glasses exhibited Arrhenius behavior in the log σdc against 1/T plots. A sharp decrease in σdc was observed for glasses containing alkali concentrations of 7 mol% or less. The σdc activation energy exhibited similar behavior when plotted as a function of alkali composition and was explained in terms of a mixture of the weak and strong electrolyte models. The depression angle for fits to the complex impedance data were also measured as a function of thermal history, alkali concentration and alkali species. These results were interpreted in terms of changes in the distribution of relaxation times. Annealed samples from a single melt of a 10 mol% K2O-90SiO2 glass were reheated to temperatures ranging from 450o to 800oC, held isothermally for 20 min, and then quenched in either air or silicon oil. The complex impedance of both an annealed and the quenched samples were then measured as a function of temperature from 120o to 250oC. The σdc was found to be remain unaffected by heat treatments below 450oC, to increase rapidly over an approximate 200oC range of temperatures that was dependent on cooling rate and to be constant for heat treatments above this range. This behavior is interpreted in terms of the mean structural relaxation time as a function of temperature and cooling rate near the glass transition temperature and glass transformation ranges. A more detailed definition for the transition and transformation temperatures and ranges was also provided.

  11. Spin transition in Fe3+ in Mg-silicate perovskite

    Science.gov (United States)

    Catalli, K.; Shim, S.; Prakapenka, V. B.; Zhao, J.; Sturhahn, W.; Liu, H.

    2008-12-01

    In recent years, spin transitions have been reported in both perovskite (Pv) (Badro et al., 2004) and magnesiowüstite (Mw) (Lin et al., 2005). Although no density change has been detected in ferrous iron bearing Pv (Lundin et al., 2008), large changes in density have been found to occur with the spin transition in Mw (Fei et al., 2007). This difference has been attributed to the diverse coordination and oxidation states of Fe in Pv and has made analysis of previous experimental data difficult. We have measured synchrotron Mössbauer spectroscopy (SMS) and X-ray diffraction (XRD) on Mg-silicate Pv with all Fe in Fe3+ (0.9MgSiO3- 0.1Fe2O3) up to 136 GPa in the laser heated diamond anvil cell with an argon pressure medium. Our SMS shows that Fe3+ enters both the dodecahedral and octahedral sites at the entire pressure range we studied (47-136 GPa). We found that both high and low spin Fe3+ exist in the octahedral site between 47 and 63 GPa and then all Fe3+ in the octahedral site becomes low spin at higher pressures, while Fe3+ in the dodecahedral site remains high spin to 136 GPa. Pressure-volume data, measured up to 106 GPa using the gold pressure scale (Tsuchiya, 2003), shows that the spin transition does not effect density but does result in a 10% increase in the bulk modulus near 60 GPa. Below 60 GPa, ferric Pv is 9% more compressible than ferrous Pv, but above 60 GPa, ferric Pv is 17% less compressible than ferrous perovskite. This change in compressibility is likely due to a change in compression mechanism: at low pressure compression is accomplished by a combination of the gradual spin collapse and lattice compression. However, after the spin transition is complete, only lattice compression is at work at higher pressures. If the lower mantle has as much Fe3+ as suggested by McCammon et al. (1997) and Frost et al. (2004), this may result in a global discontinuity at the mid-mantle. If not, local enrichment of Fe3+ can result in a discontinuity, which can be

  12. Through The Looking Glass: New Laboratory Spectra Of Glassy Silicates For The Comparison To Astrophysical Environments

    Science.gov (United States)

    Speck, Angela; Whittington, A.; Hofmeister, A.

    2011-05-01

    Many astrophysical environments exhibit a spectral feature at around 10 microns, which has long been attributed to amorphous silicates, but whose precise nature remains a mystery. Furthermore, the astronomically observed feature varies from location to location, and even within a given object both spatially and temporally. There have been many laboratory studies of potential cosmic dust analogs attempting to determine the exact nature of this dust, but most of those studies have failed to produce laboratory spectra that precisely match the observed astronomical spectra. We present new high-resolution spectra of a selection of silicate glasses whose compositions cover those expected to form in cosmic environments. These include synthetic endmember glasses of major mineral groups such as melilites (akermanite, gehlenite), pyroxenes (enstatite), olivines (forsterite) and silica; glasses produced by remelting natural mineral samples that contain iron and other elements; and a synthetic "cosmic” silicate glass with solar relative abundances of Mg, Si, Ca, Na and Al. Across the compositional range of 12 samples the 10 micron feature changes in peak position by more than a micron, as well as in shape. We discuss the effects of both compositional and structural factors on spectral features in these glassy silicates and we compare our new laboratory glass spectra with synthetic amorphous silicate spectra currently used in most models of dusty astrophysical environments. The synthetic spectra do not match either peak position or shape of any of our glass samples.

  13. Heavily Tm3+-Doped Silicate Fiber for High-Gain Fiber Amplifiers

    Directory of Open Access Journals (Sweden)

    Yin-Wen Lee

    2013-12-01

    Full Text Available We report on investigation the potential of a 7 wt% (8.35 × 1020 Tm3+/cm3 doped silicate fibers for high-gain fiber amplifiers. Such a high ion concentration significantly reduces the required fiber length of high-power 2 μm fiber laser systems and allows the high-repetition rate operation in 2 μm mode-locked fiber lasers. To evaluate the feasibility of extracting high gain-per-unit-length from this gain medium, we measure several key material properties of the silicate fiber, including the absorption/emission cross-sections, upper-state lifetime, fiber background loss, and photodarkening resistance. We show through numerical simulations that a signal gain-per-unit-length of 3.78 dB/cm at 1950 nm can be achieved in a watt-level core-pumped Tm3+-doped silicate fiber amplifier. In addition, an 18-dB 2013-nm amplifier is demonstrated in a 50-cm 7 wt% Tm3+-doped double-clad silicate fiber. Finally, we experimentally confirm that the reported silicate host exhibits no observable photodarkening.

  14. Partitioning of siderophile elements between metallic liquids and silicate liquids under high-pressure and temperature

    Science.gov (United States)

    Nakatsuka, A.; Urakawa, S.

    2010-12-01

    High-pressure metal-silicate element partitioning studies have shown the possibility that the mantle abundance of siderophile elements is consistent with core-mantle equilibration at high pressures and high temperatures. Equilibrium conditions are, however, still under debates partly due to the uncertainty of partition coefficients, which vary not only with pressure, temperature and oxygen fugacity but also with composition. We have carried out partitioning experiments of siderophile elements between liquid metal and ultramafic silicate liquid at high pressure to evaluate the effects of composition on the partition coefficients. Partitioning experiments were conducted by KAWAI-type high pressure apparatus. We used natural peridotite and Fe alloy as starting materials and they were contained in graphite capsule. The quenched samples were examined by electron microprobe. Quenched textures indicate that metallic melts coexisted with silicate melts during experiment. The metallic melt contained 7-9 wt% of C. Oxygen fugacity varied from IW-3 to IW-1 in associated with the composition of the starting material. At the reduced condition, silicate melt was enriched in SiO2 compared to peridotite because of the oxidation of Si in metallic melts. When oxygen fugacity is close to IW buffur, silicate melt was enriched in FeO due to the oxidation of metallic Fe and it had high NBO/T = 3.5-4. The partition coefficients D for Co, Ni and Fe were dependent on oxygen fugacity as well as the chemical compositions.

  15. Evaluation of the mechanical properties of acetic-cure silicone with the addition of magnesium silicate

    Directory of Open Access Journals (Sweden)

    Ronald Vargas Orellana

    2015-06-01

    Full Text Available Current study evaluates the mechanical properties (tensile and tear strength of an acetic-cure silicone with the addition of 10 or 20% vol. magnesium silicate. Magnesium silicate was added to the silicone at concentrations of 10 (MS-10 and 20% (MS-20 volume, followed by the analysis of tensile strength, maximal elongation during tensile and tear strength. Results were compared to control group of silicone without additives (CG. Mean rates were determined and compared by analysis of variance and Tukey’s test (p < 0.05. Control group had the greatest elongation when subjected to tensile strength (650%, whereas the MS-10 group statistically showed a better tensile strength (8.8 MPa when compared to CG (7.5 MPa and MS-20 (7.5 MPa groups. Both magnesium silicate groups exhibited statistically similar tear strength, whereas MS-20 group demonstrated statistically greater tear strength. The addition of 10% magnesium silicate increased tensile strength, but tear strength and elongation were similar to control. The addition of 20% magnesium silicate did not affect tensile but increased tear strength.

  16. Trace fossils of Ordovician radiolarian chert and siliceous mudstone in Newfoundland, Canada

    Science.gov (United States)

    Kakuwa, Yoshitaka

    2017-08-01

    Ordovician radiolarian chert and siliceous mudstone in Newfoundland are examined to elucidate the development of trace fossils in and on the Early Paleozoic ocean bottom. Chert sedimentation in the Shoal Arm Formation (SAF) is limited to a short interval, but its sedimentation rate is high with few siliciclastic materials. Trace fossils are common in chert in the SAF, but their development is interrupted by frequent anoxic events. The trace fossils are larger than trace fossils in the contemporary chert of other areas. In contrast, trace fossils in the Strong Island Chert (SIC) are moderately-sized to small, with a few sandstone beds interbedded with chert. Those characteristics reflect differences in the sedimentary environments. Rocks of the SIC were deposited in a basinal part of a back-arc basin; whereas, those in the SAF were deposited on a small isolated basin. Red chert or siliceous rocks that underlie grey cherts and siliceous rocks of the SIC and the SAF bear small and simple trace fossils. This is a common feature of ;oceanic red rocks.; Radiolarian chert and siliceous rocks in Newfoundland also showed that trace fossils are widespread by the Middle Ordovician in the deep-sea environment. The Great Ordovician Biodiversification Event is confirmed in the radiolarian siliceous rocks there.

  17. Antimicrobial activities and cellular responses to natural silicate clays and derivatives modified by cationic alkylamine salts.

    Science.gov (United States)

    Hsu, Shan-Hui; Tseng, Hsiang-Jung; Hung, Huey-Shan; Wang, Ming-Chien; Hung, Chiung-Hui; Li, Pei-Ru; Lin, Jiang-Jen

    2009-11-01

    Nanometer-scale silicate platelet (NSP) materials were previously developed by increasing the interlayer space and exfoliation of layered silicate clays such as montmorillonite and synthetic fluorinated mica by the process of polyamine exfoliation. In this study, the antibacterial activity and cytotoxicity of these nanometer-scale silicate clays were evaluated. The derivatives of NSP (NSP-S) which were modified by C18-fatty amine salts via ionic exchange association exhibited the highest antibacterial activity in the aqueous state among all clays. The high antibacterial activity, however, was accompanied by elevated cytotoxicity. The variations of cell surface markers (CD29 and CD44) and type I collagen expression of fibroblasts treated with the clays were measured to clarify the mechanism of the silicate-induced cytotoxicity. The signal transduction pathway involved the downregulation of extracellular-signal-regulated kinase (ERK), which appeared to participate in silicate-induced cytotoxicity. This study helped to understand the antibacterial potential of NSP and the interaction of natural and modified clays with cellular activities.

  18. Investigation of the physical properties of tricalcium silicate cement-based root-end filling materials.

    Science.gov (United States)

    Grech, L; Mallia, B; Camilleri, J

    2013-02-01

    Tricalcium silicate-based cements have been displayed as suitable root-end filling materials. The physical properties of prototype radiopacified tricalcium silicate cement, Bioaggregate and Biodentine were investigated. Intermediate restorative material was used as a control. The physical properties of a prototype zirconium oxide replaced tricalcium silicate cement and two proprietary cements composed of tricalcium silicate namely Bioaggregate and Biodentine were investigated. Intermediate restorative material (IRM) was used as a control. Radiopacity assessment was undertaken and expressed in thickness of aluminum. In addition the anti-washout resistance was investigated using a novel basket-drop method and the fluid uptake, sorption and solubility were investigated using a gravimetric method. The setting time was assessed using an indentation technique and compressive strength and micro-hardness of the test materials were investigated. All the testing was performed with the test materials immersed in Hank's balanced salt solution. All the materials tested had a radiopacity value higher than 3mm thickness of aluminum. IRM exhibited the highest radiopacity. Biodentine demonstrated a high washout, low fluid uptake and sorption values, low setting time and superior mechanical properties. The fluid uptake and setting time was the highest for Bioaggregate. The addition of admixtures to tricalcium silicate-based cements affects the physical properties of the materials. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  19. Nano porous alkaline earth metal silicates as free fatty acid adsorbents from Crude Palm Oil (CPO)

    Science.gov (United States)

    Masmur, Indra; Sembiring, Seri Bima; Bangun, Nimpan; Kaban, Jamaran; Putri, Nabila Karina

    2017-01-01

    Free fatty acids(FFA) from Crude Palm Oil (CPO) have been adsorbed by alkaline earth metal silicate (M-silicate : M = Mg, Ca, Sr and Ba) adsorbents in ethanol using batch method. The adsorbents were prepared from the chloride salts of alkaline metals and Na2SiO3. The resulting white solid of the alkaline earth metal silicates were then heated at 800°C for 3 hours to enlarge their porosities. All adsorbents were characterized by SEM-EDX, XRD and BET. The EDX spectrum of SEM-EDX showed the appearance of all elements in the adsorbents, and the XRD spectrum of all adsorbents showed that they have crystobalite structure. The porosity of the adsorbents calculated by BET method showed that the porosities of the adsorbents range from 2.0884 - 2.0969 nm. All the adsorbents were used to adsorb the FFA from CPO containing 4.79%, 7.3%, 10.37% and 13.34% of FFA. The ratio of adsorbent to CPO to be used in adsorption of FFA from CPO were made 1:1, 1:2 and 1:3, with adsorption time of 1 hour. We found that the maximum adsorption of FFA from CPO was given by Ca-Silicate adsorbent which was between 69.86 - 94.78%, while the lowest adsorption was shown by Mg-silicate adsorbent which was 49.32 -74.53%.

  20. Dielectric Property of Silicate-Doped CaBi4Ti4O15 Thin Films

    Science.gov (United States)

    Ogawa, Shota; Kondoh, Yohta; Kimura, Junichi; Funakubo, Hiroshi; Uchida, Hiroshi

    2012-09-01

    Thin films of silicate-doped CaBi4Ti4O15 were fabricated to enhance the insulating property of one-axis-oriented CaBi4Ti4O15 films under an applied electric field. The crystalline phase of CaBi4Ti4O15, a type of bismuth layer-structured dielectric (BLSD) compound, was successfully grown on (100)LaNiO3/(111)Pt/TiO2/(100)Si with the preferential orientation of the (001) plane by the addition of bismuth silicate with a nominal composition of Bi12SiO20 up to 1.00%. The crystallographic orientation of the (001)BLSD plane normal to the substrate surface was degraded by excessive bismuth silicate addition above 1.50%. The breakdown electric field was increased by bismuth silicate addition up to 2.00% without the degraded relative dielectric permittivity (ɛr) of approximately 230. The bismuth silicate could precipitate between the grain boundaries in the CaBi4Ti4O15 films without an interface reaction or a solid solution that enhances the insulating behavior of the BLSD films.

  1. Production of biodiesel and lactic acid from rapeseed oil using sodium silicate as catalyst.

    Science.gov (United States)

    Long, Yun-Duo; Guo, Feng; Fang, Zhen; Tian, Xiao-Fei; Jiang, Li-Qun; Zhang, Fan

    2011-07-01

    Biodiesel and lactic acid from rapeseed oil was produced using sodium silicate as catalyst. The transesterification in the presence of the catalyst proceeded with a maximum yield of 99.6% under optimized conditions [3% (w/w) sodium silicate, methanol/oil molar ratio 9/1, reaction time 60 min, reaction temperature 60°C, and stirring rate 250 rpm]. After six consecutive transesterification reactions, the catalyst was collected and used for catalysis of the conversion of glycerol to lactic acid. A maximum yield of 80.5% was achieved when the reaction was carried out at a temperature of 300°C for 90 min. Thus, sodium silicate is an effective catalyst for transesterification and lactic acid production from the biodiesel by-product, glycerol. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Eu-, Tb-, and Dy-Doped Oxyfluoride Silicate Glasses for LED Applications

    DEFF Research Database (Denmark)

    Zhu, C.F.; Wang, J.; Zhang, M.M.

    2014-01-01

    Luminescence glass is a potential candidate for the light-emitting diodes (LEDs) applications. Here, we study the structural and optical properties of the Eu-, Tb-, and Dy-doped oxyfluoride silicate glasses for LEDs by means of X-ray diffraction, photoluminescence spectra, Commission Internationale...... de L’Eclairage (CIE) chromaticity coordinates, and correlated color temperatures (CCTs). The results show that the white light emission can be achieved in Eu/Tb/Dy codoped oxyfluoride silicate glasses under excitation by near-ultraviolet light due to the simultaneous generation of blue, green, yellow......, and red-light wavelengths from Tb, Dy, and Eu ions. The optical performances can be tuned by varying the glass composition and excitation wavelength. Furthermore, we observed a remarkable emission spectral change for the Tb3+ single-doped oxyfluoride silicate glasses. The 5D3 emission of Tb3+ can...

  3. Development of Biomedical Polymer-Silicate Nanocomposites: A Materials Science Perspective

    Science.gov (United States)

    Wu, Chia-Jung; Gaharwar, Akhilesh K.; Schexnailder, Patrick J.; Schmidt, Gudrun

    2010-01-01

    Biomedical polymer-silicate nanocomposites have potential to become critically important to the development of biomedical applications, ranging from diagnostic and therapeutic devices, tissue regeneration and drug delivery matrixes to various bio-technologies that are inspired by biology but have only indirect biomedical relation. The fundamental understanding of polymer-nanoparticle interactions is absolutely necessary to control structure-property relationships of materials that need to work within the chemical, physical and biological constraints required by an application. This review summarizes the most recent published strategies to design and develop polymer-silicate nanocomposites (including clay based silicate nanoparticles and bioactive glass nanoparticles) for a variety of biomedical applications. Emerging trends in bio-technological and biomedical nanocomposites are highlighted and potential new fields of applications are examined.

  4. Electrophoretic deposition of magnesium silicates on titanium implants: Ion migration and silicide interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Afshar-Mohajer, M. [Center for Advanced Manufacturing and Material Processing, Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Yaghoubi, A., E-mail: yaghoubi@siswa.um.edu.my [Center for High Impact Research, University of Malaya, Kuala Lumpur 50603 (Malaysia); Ramesh, S., E-mail: ramesh79@um.edu.my [Center for Advanced Manufacturing and Material Processing, Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Bushroa, A.R.; Chin, K.M.C.; Tin, C.C. [Center for Advanced Manufacturing and Material Processing, Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Chiu, W.S. [Low Dimensional Materials Research Center, Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia)

    2014-07-01

    Magnesium silicates (Mg{sub x}SiO{sub y}) and in particular forsterite (Mg{sub 2}SiO{sub 4}) owing to their low thermal expansion mismatch with metals are promising materials for bioactive coating of implants. Here, we report the electrophoretic deposition (EPD) of forsterite onto titanium substrates using different precursors. Unlike bulk samples which achieve full stoichiometry only beyond 1400 °C, non-stoichiometric magnesium silicate rapidly decomposes into magnesium oxide nanowires during sintering. Elemental mapping and X-ray diffraction suggest that oxygen diffusion followed by ion exchange near the substrate leads to formation of an interfacial Ti{sub 5}Si{sub 3} layer. Pre-annealed forsterite powder on the other hand shows a comparatively lower diffusion rate. Overall, magnesium silicate coatings do not exhibit thermally induced microcracks upon sintering as opposed to calcium phosphate bioceramics which are currently in use.

  5. Determine the compressive strength of calcium silicate bricks by combined nondestructive method.

    Science.gov (United States)

    Brozovsky, Jiri

    2014-01-01

    The paper deals with the application of combined nondestructive method for assessment of compressive strength of calcium silicate bricks. In this case, it is a combination of the rebound hammer method and ultrasonic pulse method. Calibration relationships for determining compressive strength of calcium silicate bricks obtained from nondestructive parameter testing for the combined method as well as for the L-type Schmidt rebound hammer and ultrasonic pulse method are quoted here. Calibration relationships are known for their close correlation and are applicable in practice. The highest correlation between parameters from nondestructive measurement and predicted compressive strength is obtained using the SonReb combined nondestructive method. Combined nondestructive SonReb method was proved applicable for determination of compressive strength of calcium silicate bricks at checking tests in a production plant and for evaluation of bricks built in existing masonry structures.

  6. Investigation of the hydration and bioactivity of radiopacified tricalcium silicate cement, Biodentine and MTA Angelus.

    Science.gov (United States)

    Camilleri, Josette; Sorrentino, François; Damidot, Denis

    2013-05-01

    Novel root-end filling materials are composed of tricalcium silicate (TCS) and radiopacifier as opposed to the traditional mineral trioxide aggregate (MTA) which is made up of clinker derived from Portland cement and bismuth oxide. The aim of this research was to characterize and investigate the hydration of a tricalcium silicate-based proprietary brand cement (Biodentine™) and a laboratory manufactured cement made with a mixture of tricalcium silicate and zirconium oxide (TCS-20-Z) and compare their properties to MTA Angelus™. The materials investigated included a cement containing 80% of TCS and 20% zirconium oxide (TCS-20-Z), Biodentine™ and MTA Angelus™. The specific surface area and the particle size distribution of the un-hydrated cements and zirconium oxide were investigated using a gas adsorption method and scanning electron microscopy. Un-hydrated cements and set materials were tested for mineralogy and microstructure, assessment of bioactivity and hydration. Scanning electron microscopy, X-ray energy dispersive analysis, X-ray fluorescence spectroscopy, X-ray diffraction, Rietveld refined X-ray diffraction and calorimetry were employed. The radiopacity of the materials was investigated using ISO 6876 methods. The un-hydrated cements were composed of tricalcium silicate and a radiopacifier phase; zirconium oxide for both Biodentine™ and TCS-20-Z whereas bismuth oxide for MTA Angelus™. In addition Biodentine™ contained calcium carbonate particles and MTA Angelus™ exhibited the presence of dicalcium silicate, tricalcium aluminate, calcium, aluminum and silicon oxides. TCS and MTA Angelus™ exhibited similar specific surface area while Biodentine™ had a greater specific surface area. The cements hydrated and produced some hydrates located either as reaction rim around the tricalcium silicate grain or in between the grains at the expense of volume containing the water initially present in the mixture. The rate of reaction of tricalcium

  7. Metal-Silicate Partitioning of Tungsten from 10 to 50 GPa

    Science.gov (United States)

    Shofner, G. A.; Campbell, A. J.; Danielson, L.; Rahman, Z.; Righter, K.

    2014-01-01

    Geochemical models of core formation are commonly based on core and mantle abundances of siderophile elements that partitioned between silicate and metal in a magma ocean in the early Earth. Tungsten is a moderately siderophile element that may provide constraints on the pressure, temperature, composition, and oxygen fugacity conditions, and on the timing of core formation in the Earth. Previous experimental studies suggest that pressure exerts little to no influence over W metal-silicate partitioning up to 24 GPa, and indicate that the stronger influences are temperature, composition, and oxygen fugacity. However, core formation models based in part on W, predict metal-silicate equilibration pressures outside the available experimental pressure range, requiring extrapolation of parameterized models. Therefore, higher pressure experimental data on W were needed to constrain this important parameter.

  8. The opportunity of silicate product manufacturing with simultaneous pig iron reduction from slag technogenic formations

    Science.gov (United States)

    Sheshukov, O. Yu.; Lobanov, D. A.; Mikheenkov, M. A.; Nekrasov, I. V.; Egiazaryan, D. K.

    2017-09-01

    There are two main kinds of slag in modern steelmaking industry: the electric arc furnace slag (EAF slag) and ladle furnace slag (LF slag). The all known slag processing schemes provide the iron-containing component reduction while silicate component stays unprocessed. On the contrary, the silicate processing schemes doesn't provide the utilization of the iron-containing component. The present-day situation doesn't solve the problem of total slag utilization. The aim of this work is to investigate the opportunity of silicate product obtaining with simultaneous pig iron reduction from EAF and LF slags. The tests are conducted by the method of simplex-lattice design. The test samples are heated and melted under reductive conditions, slowly cooled and then analyzed by XRD methods. The experiment results prove the opportunity: the Portland clinker and pig iron can be simultaneously produced on the basis of these slags with a limestone addition.

  9. Low availability of aluminum in formulations for parenteral nutrition containing silicate.

    Science.gov (United States)

    Bohrer, Denise; Bortoluzzi, Fabiana; do Nascimento, Paulo Cícero; de Carvalho, Leandro Machado; de Oliveira, Sandra Ribeiro

    2009-01-01

    Silicate (Si) and aluminum (Al) may be concomitant impurities in solutions for parenteral nutrition (PN). Silicate can bind to Al to form stable hydroxyaluminosilicates (HAS), thus reducing Al availability. This possibility is investigated by heating solutions containing constituents of PN in glass containers to promote the release of Si and Al. The total amount of Si and Al in solution is measured by atomic absorption spectrometry, and the Al not bound to Si is evaluated by reaction with morin. When the Si:Al molar ratio is >5, no free Al is found in solution. For ratios 5, there is a "residual" fraction of free Al in amino acid formulations. The concomitant presence of Al and Si in solutions for PN reduces the amount of Al available attributable to the formation of HAS. In amino acid formulations this effect may be slightly reduced given the affinity of certain amino acids for Al. Therefore, amino acids may behave in the same fashion as silicate.

  10. Development of Biomedical Polymer-Silicate Nanocomposites: A Materials Science Perspective

    Directory of Open Access Journals (Sweden)

    Chia-Jung Wu

    2010-04-01

    Full Text Available Biomedical polymer-silicate nanocomposites have potential to become critically important to the development of biomedical applications, ranging from diagnostic and therapeutic devices, tissue regeneration and drug delivery matrixes to various bio-technologies that are inspired by biology but have only indirect biomedical relation. The fundamental understanding of polymer-nanoparticle interactions is absolutely necessary to control structure-property relationships of materials that need to work within the chemical, physical and biological constraints required by an application. This review summarizes the most recent published strategies to design and develop polymer-silicate nanocomposites (including clay based silicate nanoparticles and bioactive glass nanoparticles for a variety of biomedical applications. Emerging trends in bio-technological and biomedical nanocomposites are highlighted and potential new fields of applications are examined.

  11. Li+ alumino-silicate ion source development for the Neutralized Drift Compression Experiment (NDCX)

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.; Seidl, Peter A.; Waldron, William L.; Wu, James K.

    2010-10-01

    We report results on lithium alumino-silicate ion source development in preparation for warmdense-matter heating experiments on the new Neutralized Drift Compression Experiment (NDCXII). The practical limit to the current density for a lithium alumino-silicate source is determined by the maximum operating temperature that the ion source can withstand before running into problems of heat transfer, melting of the alumino-silicate material, and emission lifetime. Using small prototype emitters, at a temperature of ~;;1275 oC, a space-charge-limited Li+ beam current density of J ~;;1 mA/cm2 was obtained. The lifetime of the ion source was ~;;50 hours while pulsing at a rate of 0.033 Hz with a pulse duration of 5-6 mu s.

  12. Synergistic effect of silicate clay and phosphazene-oxyalkyleneamines on thermal stability of cured epoxies.

    Science.gov (United States)

    Chen, Yu-Min; Liao, Yi-Lin; Lin, Jiang-Jen

    2010-03-01

    Amine substitution of hexachlorocyclophosphazene (HCP) with poly(oxypropylene)diamines (POP) afforded HCP-POP adducts which were subsequently intercalated into a layered silicate clay. The relative thermal stabilities of the epoxies cured with the phosphazene-amines and the intercalated clays were studied. The organoclays, with the confined HCP-POP from 400 and 2000 g/mol M(w) amines, are nongelled products when using 1/6 M ratio of HCP/POP starting materials in tetrahydrofuran solvent. The intercalation of HCP-POP polyamine salts into sodium montmorillonite afforded the HCP-POP-embedded organoclays with an expanded interlayer silicate spacing (2.4-5.1 nm) from the original 1.2 nm spacing (X-ray diffraction). The effect of silicate clays was evaluated by blending the HCP-POP/clay hybrids into a two-component epoxy system (diglycidyl ether of 4,4'-isopropylidenediphenol (BPA) and a diamine) and fully cured to form solid materials. The distribution of the exfoliated silicate platelets in the matrix was analyzed by transmission electronic microscopy (TEM). Thermal gravimetric analysis (TGA) indicated an enhanced thermal stability for the HCP/clay epoxy nanocomposites, with a delayed weight-loss pattern (temperature of weight loss at 10% (T(10 wt.%)) from 360 to 385 degrees C and temperature of weight loss at 85% (T(85 wt.%)) from 598 to 696 degrees C), compared to the pristine epoxies. By comparing these epoxies with different amounts of phosphazene and/or silicates, the TGA revealed a synergistic effect for the presence of both phosphorous and silicate components. Furthermore, the epoxies had improved physical properties such as hardness (from 3H to 5H) and surface adhesion (observed by scanning electron microscope (SEM) on fracture surface). 2009. Published by Elsevier Inc. All rights reserved.

  13. Through The Looking Glass: The Causes Of Variations In "Amorphous” Silicate Spectral Features.

    Science.gov (United States)

    Speck, Angela; Hofmeister, A. M.; Whittington, A. G.

    2009-05-01

    Silicate dust plays an essential role in many astrophysical environments. The "amorphous” silicate spectral features have been observed in our solar system, young stellar objects, star formation regions, novae, and the diffuse and dense interstellar medium as well as in extragalactic environments such as quasars and AGN. This dust contributes to the physical processes inherent in star formation processes, as well as to several aspects of interstellar processes such as gas heating and the formation of molecules. The discovery of this almost ubiquitous 10um silicate feature, led to many laboratory studies of potential cosmic dust analogs attempting to determine the exact nature of this dust. However, these various lab studies have produced inconsistent and often conflicting results. Studies of ostensibly the same material produce different spectra, which can be attributed to small differences in samples and techniques, but which leave astronomers at a loss as to interpretation of astrophysical data. We survey the compositional and structural factors that affect spectral features in "amorphous” silicates, illustrated with examples of new high-resolution spectra and previously published spectra of amorphous silicates nominally corresponding in composition to the mineral end-members forsterite (Mg2SiO4), enstatite (MgSiO3) and gehlenite (Ca2Al2SiO7). These examples highlight the sensitivity of such characteristics as peak shape, peak position, and the ratio of the 10µm and 18µm features, to subtle compositional / structural variations. By careful laboratory study, we can harness these effects on the spectral features of amorphous silicates to understand dust composition more precisely and provide a rich source of information on dust formation and processing.

  14. Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria-A Challenge for Life on Mars.

    Science.gov (United States)

    Bak, Ebbe N; Larsen, Michael G; Moeller, Ralf; Nissen, Silas B; Jensen, Lasse R; Nørnberg, Per; Jensen, Svend J K; Finster, Kai

    2017-01-01

    The habitability of Mars is determined by the physical and chemical environment. The effect of low water availability, temperature, low atmospheric pressure and strong UV radiation has been extensively studied in relation to the survival of microorganisms. In addition to these stress factors, it was recently found that silicates exposed to simulated saltation in a Mars-like atmosphere can lead to a production of reactive oxygen species. Here, we have investigated the stress effect induced by quartz and basalt abraded in Mars-like atmospheres by examining the survivability of the three microbial model organisms Pseudomonas putida, Bacillus subtilis, and Deinococcus radiodurans upon exposure to the abraded silicates. We found that abraded basalt that had not been in contact with oxygen after abrasion killed more than 99% of the vegetative cells while endospores were largely unaffected. Exposure of the basalt samples to oxygen after abrasion led to a significant reduction in the stress effect. Abraded quartz was generally less toxic than abraded basalt. We suggest that the stress effect of abraded silicates may be caused by a production of reactive oxygen species and enhanced by transition metal ions in the basalt leading to hydroxyl radicals through Fenton-like reactions. The low survivability of the usually highly resistant D. radiodurans indicates that the effect of abraded silicates, as is ubiquitous on the Martian surface, would limit the habitability of Mars as well as the risk of forward contamination. Furthermore, the reactivity of abraded silicates could have implications for future manned missions, although the lower effect of abraded silicates exposed to oxygen suggests that the effects would be reduced in human habitats.

  15. Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria—A Challenge for Life on Mars

    Science.gov (United States)

    Bak, Ebbe N.; Larsen, Michael G.; Moeller, Ralf; Nissen, Silas B.; Jensen, Lasse R.; Nørnberg, Per; Jensen, Svend J. K.; Finster, Kai

    2017-01-01

    The habitability of Mars is determined by the physical and chemical environment. The effect of low water availability, temperature, low atmospheric pressure and strong UV radiation has been extensively studied in relation to the survival of microorganisms. In addition to these stress factors, it was recently found that silicates exposed to simulated saltation in a Mars-like atmosphere can lead to a production of reactive oxygen species. Here, we have investigated the stress effect induced by quartz and basalt abraded in Mars-like atmospheres by examining the survivability of the three microbial model organisms Pseudomonas putida, Bacillus subtilis, and Deinococcus radiodurans upon exposure to the abraded silicates. We found that abraded basalt that had not been in contact with oxygen after abrasion killed more than 99% of the vegetative cells while endospores were largely unaffected. Exposure of the basalt samples to oxygen after abrasion led to a significant reduction in the stress effect. Abraded quartz was generally less toxic than abraded basalt. We suggest that the stress effect of abraded silicates may be caused by a production of reactive oxygen species and enhanced by transition metal ions in the basalt leading to hydroxyl radicals through Fenton-like reactions. The low survivability of the usually highly resistant D. radiodurans indicates that the effect of abraded silicates, as is ubiquitous on the Martian surface, would limit the habitability of Mars as well as the risk of forward contamination. Furthermore, the reactivity of abraded silicates could have implications for future manned missions, although the lower effect of abraded silicates exposed to oxygen suggests that the effects would be reduced in human habitats. PMID:28955310

  16. Hydration characteristics of calcium silicate cements with alternative radiopacifiers used as root-end filling materials.

    Science.gov (United States)

    Camilleri, Josette

    2010-03-01

    Mineral trioxide aggregate (MTA) is composed of calcium silicate cement and bismuth oxide added for radiopacity. The bismuth oxide in MTA has been reported to have a deleterious effect on the physical and chemical properties of the hydrated material. This study aimed to investigate the hydration mechanism of calcium silicate cement loaded with different radiopacifiers for use as a root-end filling material. Calcium silicate cement loaded with barium sulfate, gold, or silver/tin alloy was hydrated, and paste microstructure was assessed after 30 days. In addition, atomic ratio plots of Al/Ca versus Si/Ca and S/Ca and Al/Ca were drawn, and X-ray energy dispersive analysis of the hydration products was performed to assess for inclusion of heavy metals. The leachate produced from the cements after storage of the cements in water for 28 days and the leaching of the radiopacifiers in an alkaline solution was assessed by using inductively coupled plasma. The hydrated calcium silicate cement was composed of calcium silicate hydrate, calcium hydroxide, ettringite, and monosulfate. Unhydrated cement particles were few. No heavy metals were detected in the calcium silicate hydrate except for the bismuth in MTA. Calcium was leached out early in large quantities that reduced with time. The barium and bismuth were leached in increasing amounts. Copper was the most soluble in alkaline solution followed by bismuth and barium in smaller amounts. The bismuth oxide can be replaced by other radiopacifiers that do not affect the hydration mechanism of the resultant material. Copyright (c) 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  17. Effect of phase composition of calcium silicate phosphate component on properties of brushite based composite cements

    Energy Technology Data Exchange (ETDEWEB)

    Sopcak, T., E-mail: tsopcak@imr.saske.sk [Institute of Materials Research of SAS, Watsonova 47, 04001 Kosice (Slovakia); Medvecky, L.; Giretova, M.; Stulajterova, R.; Durisin, J. [Institute of Materials Research of SAS, Watsonova 47, 04001 Kosice (Slovakia); Girman, V. [Institute of Physics, Faculty of Science, P. J. Šafárik University, Park Angelinum 9, 04001 Kosice (Slovakia); Faberova, M. [Institute of Materials Research of SAS, Watsonova 47, 04001 Kosice (Slovakia)

    2016-07-15

    The composite cement mixtures were prepared by mixing brushite (B) with, the amorphous hydrated calcium silicate phosphate (CSPH) or annealed calcium silicate phosphate (CSP composed of Si-saturated hydroxyapatite, wollastonite and silica) phases and water as liquid component. The contents of the silicate-phosphate phase in composites were 10.30 and 50 wt%. The significant effect of both the Ca/P ratio and different solubility of calcium silicate phosphate component in starting cement systems on setting time and phase composition of the final composite cements was demonstrated. The compressive strength of the set cements increased with the filler addition and the highest value (~ 48 MPa) exhibited the 50CSP/B cement composite. The final setting times of the composite cements decreased with the CSPH addition from about 25 to 17 min in 50CSHP/B and setting time of CSP/B composites was around 30 min. The higher content of silica in cements caused the precipitation of fine hydroxyapatite particles in the form of nanoneedles or thin plates perpendicularly oriented to sample surface. The analysis of in vitro cement cytotoxicity demonstrated the strong reduction in cytotoxicity of 10CSPH/B composite with time of cultivation (a low cytotoxicity after 9 days of culture) contrary to cements with higher calcium silicate-phosphate content. These results were attributed to the different surface topography of composite substrates and possible stimulation of cell proliferation by the slow continuously release of ions from 10CSPH/B cement. - Highlights: • Ca/P ratio and solubility of calcium silicate-phosphate components affect the self-setting properties of cements. • Strong relationship between the composite in vitro cytotoxicity and surface microtopography was demonstrated. • Plate-like morphology of coarser particles allowed cells to better adhere and proliferate as compared with nanoneedles.

  18. Preparation and properties of isotropic Nd-Fe-B bonded magnets with sodium silicate binder

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W.Q.; Hu, R.J.; Yue, M., E-mail: yueming@bjut.edu.cn; Yin, Y.X.; Zhang, D.T.

    2017-08-01

    Graphical abstract: To improve the working temperature of bonded Nd-Fe-B magnets, the heat-resistant binder, sodium silicate, was used to prepare new type bonded Nd-Fe-B magnets. The three-dimensional Si-O-Si structure formed in the curing process has excellent strength; it can ensure that the bonded magnets have a certain shape and usable magnetic properties when working at 200 °C. - Highlights: • Sodium silicate enables bonded Nd-Fe-B magnets to be used for higher operation temperatures. • The sodium silicate bonded magnets exhibit usable maximum energy product of 4.057 MGOe at 200 °C. • The compressive strength of sodium silicate bonded magnets is twice bigger than that of epoxy resin bonded magnets. - Abstract: In present study, sodium silicate, a kind of heat-resistant binder, was used to prepare bonded Nd-Fe-B magnets with improved thermal stability and mechanical strength. Effect of curing temperature and curing time of the new binder to the magnetic properties, microstructure, and mechanical strength of the magnets was systematically investigated. Fracture surface morphology observation show that sodium silicate in bonded magnets could completely be cured at 175 °C for 40 min, and the magnets prepared under this condition exhibit optimal properties. They exhibit usable magnetic properties of B{sub r} of 4.66 kGs, H{sub cj} of 4.84 kOe, and (BH){sub max} of 4.06 MGOe at 200 °C. Moreover, the magnets possess high compressive strength of 63 MPa.

  19. The inhibitory effects of potassium chloride versus potassium silicate application on (137)Cs uptake by rice.

    Science.gov (United States)

    Fujimura, Shigeto; Yoshioka, Kunio; Ota, Takeshi; Ishikawa, Tetsuya; Sato, Makoto; Satou, Mutsuto

    2016-03-01

    After the accident at the Fukushima Dai-ichi Nuclear Power Plant owned by the Tokyo Electric Power Company on 11 March 2011, potassium fertilizer was applied to agricultural fields in the southern Tohoku and northern Kanto regions of Japan to reduce the uptake of radiocesium by crops. In this study, we examined the effects of two types of potassium fertilizers, potassium chloride (a readily available potassium fertilizer) and potassium silicate (a slow-release potassium fertilizer), as well as a split application of potassium, on the accumulation of (137)Cs by rice plants in two pot experiments. The (137)Cs concentrations in the brown rice and in the above-ground plants were significantly lower after potassium chloride application than after potassium silicate application. The potassium ion (K(+)) concentrations in soil solutions sampled 9 and 21 d after transplanting were significantly higher for the potassium chloride application than for the potassium silicate application. The K(+) concentrations in soil solutions observed in the application of potassium silicate were similar to those in the treatment when no potassium was applied. This finding indicates that the application of potassium silicate did not sufficiently increase the available K(+) for rice plants in the soil, which led to a greater uptake of (137)Cs after the potassium silicate application than after the application of potassium chloride. The (137)Cs concentration in brown rice was higher in the split application of potassium fertilizer with the second application at the full heading stage than that without split application and the split application with the second application before heading. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria—A Challenge for Life on Mars

    Directory of Open Access Journals (Sweden)

    Ebbe N. Bak

    2017-09-01

    Full Text Available The habitability of Mars is determined by the physical and chemical environment. The effect of low water availability, temperature, low atmospheric pressure and strong UV radiation has been extensively studied in relation to the survival of microorganisms. In addition to these stress factors, it was recently found that silicates exposed to simulated saltation in a Mars-like atmosphere can lead to a production of reactive oxygen species. Here, we have investigated the stress effect induced by quartz and basalt abraded in Mars-like atmospheres by examining the survivability of the three microbial model organisms Pseudomonas putida, Bacillus subtilis, and Deinococcus radiodurans upon exposure to the abraded silicates. We found that abraded basalt that had not been in contact with oxygen after abrasion killed more than 99% of the vegetative cells while endospores were largely unaffected. Exposure of the basalt samples to oxygen after abrasion led to a significant reduction in the stress effect. Abraded quartz was generally less toxic than abraded basalt. We suggest that the stress effect of abraded silicates may be caused by a production of reactive oxygen species and enhanced by transition metal ions in the basalt leading to hydroxyl radicals through Fenton-like reactions. The low survivability of the usually highly resistant D. radiodurans indicates that the effect of abraded silicates, as is ubiquitous on the Martian surface, would limit the habitability of Mars as well as the risk of forward contamination. Furthermore, the reactivity of abraded silicates could have implications for future manned missions, although the lower effect of abraded silicates exposed to oxygen suggests that the effects would be reduced in human habitats.

  1. Silicate fertilization of tropical soils: silicon availability and recovery index of sugarcane

    Directory of Open Access Journals (Sweden)

    Mônica Sartori de Camargo

    2013-10-01

    Full Text Available Sugarcane is considered a Si-accumulating plant, but in Brazil, where several soil types are used for cultivation, there is little information about silicon (Si fertilization. The objectives of this study were to evaluate the silicon availability, uptake and recovery index of Si from the applied silicate on tropical soils with and without silicate fertilization, in three crops. The experiments in pots (100 L were performed with specific Si rates (0, 185, 370 and 555 kg ha-1 Si, three soils (Quartzipsamment-Q, 6 % clay; Rhodic Hapludox-RH, 22 % clay; and Rhodic Acrudox-RA, 68 % clay, with four replications. The silicon source was Ca-Mg silicate. The same Ca and Mg quantities were applied to all pots, with lime and/or MgCl2, when necessary. Sugarcane was harvested in the plant cane and first- and second-ratoon crops. The silicon rates increased soil Si availability and Si uptake by sugarcane and had a strong residual effect. The contents of soluble Si were reduced by harvesting and increased with silicate application in the following decreasing order: Q>RH>RA. The silicate rates promoted an increase in soluble Si-acetic acid at harvest for all crops and in all soils, except RA. The amounts of Si-CaCl2 were not influenced by silicate in the ratoon crops. The plant Si uptake increased according to the Si rates and was highest in RA at all harvests. The recovery index of applied Si (RI of sugarcane increased over time, and was highest in RA.

  2. Corrosion of low Si-alloyed steels in aqueous solution at 90 deg. C. Inhibitive action of silicates; Corrosion d'aciers faiblement allies au silicium en solution aqueuse a 90 deg. C. Action inhibitrice des silicates

    Energy Technology Data Exchange (ETDEWEB)

    Giordana, S

    2002-02-01

    Low-Si alloyed steels, with Si content ranging from 0.25 to 3.2 wt%, as potential candidate materials for high-level nuclear waste disposal containers, have been studied four the point of view of their corrosion behaviour at 90 deg C in an aqueous solution simulating groundwater (0.1 M NaCl borate-buffered solution with a pH of 8.5) both in reducing and in aerated conditions. The influence of silicate addition to the solution is examined so as to represent the silicon of groundwater, coming from the clay dissolution. When no silicate was added to the solution, silicon as an alloying element was proved to degrade in the first moments the steel ability to passivate. For longer immersion times, protective effects developed most efficiently on the steel containing 3.2 wt% silicon both in reducing an in aerating conditions, Infrared spectroscopy, EDSX, XRD and Raman microprobe were applied to characterise the oxide layer composition, which was found to be a mixture of magnetite and maghemite. In the presence of silicate in the solution, clay-like iron silicates appeared in the corrosion layer. Electrochemical tests results show that adding silicate into solution resulted in increasing the steel ability to passivate. In the short term, the inhibiting effect of silicate was confirmed by mass loss tests, but the tendency was inverse in the long term. Silicate iron layers were eventually less protective than the magnetite layers formed in the absence of silicate. (author)

  3. Influence of Chemical Conditions on the Nanoporous Structure of Silicate Aerogels

    Directory of Open Access Journals (Sweden)

    Katalin Sinkó

    2010-01-01

    Full Text Available Silica or various silicate aerogels can be characterized by highly porous, open cell, low density structures. The synthesis parameters influence the three-dimensional porous structures by modifying the kinetics and mechanism of hydrolysis and condensation processes. Numerous investigations have shown that the structure of porous materials can be tailored by variations in synthesis conditions (e.g., the type of precursors, catalyst, and surfactants; the ratio of water/precursor; the concentrations; the medium pH; and the solvent. The objectives of this review are to summarize and elucidate the effects of chemical conditions on the nanoporous structure of sol-gel derived silicate aerogels.

  4. Inorganic polymer cement from Fe-Silicate glasses: Varying the activating solution to glass ratio

    OpenAIRE

    Machiels, Lieven; Arnout, Lukas; Jones , Peter Tom; Blanpain, Bart; Pontikes, Yiannis

    2014-01-01

    Large volumes of Fe-silicate glasses - slags - are produced as residues of metal production and waste treatment processes. It would be interesting if these materials could become an alternative group of precursors for the synthesis of inorganic polymer (IP) cements. This paper investigates the polymerisation of Fe-silicate glasses of composition (in wt%) SiO2: 40; FeO: 30; CaO: 15; Al2O3: 8 and an activating solution of composition (in wt%) Na2O: 15; SiO2: 13; H2O: 72. The mass ratio of the a...

  5. The LithicUB project: A virtual lithotheque of siliceous rocks at the University of Barcelona

    Directory of Open Access Journals (Sweden)

    Marta Sánchez

    2014-03-01

    Full Text Available The LithicUB project began in 2009 with two main objectives. The first objective was to make available to the scientific community the description and classification of a set of siliceous rocks that had been recovered from different surveys. The second to make public the lithotheque as a useful tool for archaeological research, related to the procurement and management of lithic raw materials in Prehistory. Thanks to several research projects that have been carried out, the number of samples is steadily increasing and diversifying, including siliceous rocks collected in Spain, Portugal, France, Jordan and Israel.

  6. Nicotine-magnesium aluminum silicate microparticle surface modified with chitosan for mucosal delivery

    DEFF Research Database (Denmark)

    Kanjanakawinkul, Watchara; Rades, Thomas; Puttipipatkhachorn, Satit

    2013-01-01

    Magnesium aluminum silicate (MAS), a negatively charged clay, and nicotine (NCT), a basic drug, can interact electrostatically to form microparticles. Chitosan (CS) was used for the surface modification of the microparticles, and a lyophilization method was used to preserve the original particle...... an irregular shape and that their NCT content increased with increasing NCT ratios in the microparticle preparation solution. High molecular weight CS (800 kDa) adsorbed to the microparticle surface and induced a positive surface charge. CS molecules intercalated into the MAS silicate layers and decreased...

  7. Heavily Tm3+-Doped Silicate Fiber for High-Gain Fiber Amplifiers

    OpenAIRE

    Yin-Wen Lee; Han-Wei Chien; Che-Hung Cho; Ju-Zhe Chen; Juin-Shin Chang; Shibin Jiang

    2013-01-01

    We report on investigation the potential of a 7 wt% (8.35 × 1020 Tm3+/cm3) doped silicate fibers for high-gain fiber amplifiers. Such a high ion concentration significantly reduces the required fiber length of high-power 2 μm fiber laser systems and allows the high-repetition rate operation in 2 μm mode-locked fiber lasers. To evaluate the feasibility of extracting high gain-per-unit-length from this gain medium, we measure several key material properties of the silicate fiber, including the ...

  8. Universality of the high-temperature viscosity limit of silicate liquids

    DEFF Research Database (Denmark)

    Zheng, Qiuju; Mauro, John C.; Ellison, Adam J.

    2011-01-01

    We investigate the high-temperature limit of liquid viscosity by analyzing measured viscosity curves for 946 silicate liquids and 31 other liquids including metallic, molecular, and ionic systems. Our results show no systematic dependence of the high-temperature viscosity limit on chemical...... composition for the studied liquids. Based on theMauro-Yue-Ellison-Gupta-Allan (MYEGA) model of liquid viscosity, the high-temperature viscosity limit of silicate liquids is 10−2.93 Pa·s. Having established this value, there are only two independent parameters governing the viscosity-temperature relation...

  9. Three-dimensional culture of dental pulp stem cells in direct contact to tricalcium silicate cements.

    Science.gov (United States)

    Widbiller, M; Lindner, S R; Buchalla, W; Eidt, A; Hiller, K-A; Schmalz, G; Galler, K M

    2016-03-01

    Calcium silicate cements are biocompatible dental materials applicable in contact with vital tissue. The novel tricalcium silicate cement Biodentine™ offers properties superior to commonly used mineral trioxide aggregate (MTA). Objective of this study was to evaluate its cytocompatibility and ability to induce differentiation and mineralization in three-dimensional cultures of dental pulp stem cells after direct contact with the material. Test materials included a new tricalcium silicate (Biodentine™, Septodont, Saint-Maur-des-Fossés, France), MTA (ProRoot® MTA, DENSPLY Tulsa Dental Specialities, Johnson City, TN, USA), glass ionomer (Ketac™ Molar Aplicap™, 3M ESPE, Seefeld, Germany), human dentin disks and polystyrene. Magnetic activated cell sorting for to the surface antigen STRO-1 was performed to gain a fraction enriched with mesenchymal stem cells. Samples were allowed to set and dental pulp stem cells in collagen carriers were placed on top. Scanning electron microscopy of tricalcium silicate cement surfaces with and without cells was conducted. Cell viability was measured for 14 days by MTT assay. Alkaline phosphatase activity was evaluated (days 3, 7, and 14) and expression of mineralization-associated genes (COL1A1, ALP, DSPP, and RUNX2) was quantified by real-time quantitative PCR. Nonparametric statistical analysis for cell viability and alkaline phosphatase data was performed to compare different materials as well as time points (Mann-Whitney U test, α = 0.05). Cell viability was highest on tricalcium silicate cement, followed by MTA. Viability on glass ionomer cement and dentin disks was significantly lower. Alkaline phosphatase activity was lower in cells on new tricalcium silicate cement compared to MTA, whereas expression patterns of marker genes were alike. Increased cell viability and similar levels of mineralization-associated gene expression in three-dimensional cell cultures on the novel tricalcium silicate cement and mineral

  10. Mechanical Properties and Durability of Advanced Environmental Barrier Coatings in Calcium-Magnesium-Alumino-Silicate Environments

    Science.gov (United States)

    Miladinovich, Daniel S.; Zhu, Dongming

    2011-01-01

    Environmental barrier coatings are being developed and tested for use with SiC/SiC ceramic matrix composite (CMC) gas turbine engine components. Several oxide and silicate based compositons are being studied for use as top-coat and intermediate layers in a three or more layer environmental barrier coating system. Specifically, the room temperature Vickers-indentation-fracture-toughness testing and high-temperature stability reaction studies with Calcium Magnesium Alumino-Silicate (CMAS or "sand") are being conducted using advanced testing techniques such as high pressure burner rig tests as well as high heat flux laser tests.

  11. Sol-Gel Synthesis, X-Ray Diffraction Studies, and Electric Conductivity of Sodium Europium Silicate

    Directory of Open Access Journals (Sweden)

    Ekaterina V. Borisova

    2013-01-01

    Full Text Available Sodium europium silicate, NaEu9(SiO46O2, with apatite structure has been obtained and studied using X-ray diffraction and SEM. It has been shown that sodium sublimation does not take place upon synthesis by the sol-gel method. Rietveld refinement has revealed that sodium atoms are ordered and occupy the 4f position. O(4 atoms not related to silicate ions are placed at the centers of Eu(2 triangles. DC and AC electric conductivity and activation energy have been determined for the compound studied.

  12. Rice field test applied by the granular fertilizer made of silicate and oyster sell powder

    OpenAIRE

    森本, 正則; 守本, 信一; 宮本, 信彦; 立木, 陽子; 大黒, 撤平; 樋口, 喜三; 駒井, 功一郎

    2009-01-01

    [Synopsis] The granular fertilizer made of silicate and oyster sell powder was evaluated the efficacy by application for rice production in the paddy field experiment. The fertilizer was formulated oyster sell powder and silicate using granulator during spray a lignin solution as binder to ingredient powder. Finally, the granular fertilizer contents 1~2% water, 40% CaO, 3% SiO_2 and the particle size is 1~2 mm. The experimental setting was along with conventional rice production in Nara Pref....

  13. Low-temperature fabrication of macroporous scaffolds through foaming and hydration of tricalcium silicate paste and their bioactivity

    NARCIS (Netherlands)

    Huan, Z.; Chang, J.; Zhou, J.

    2009-01-01

    A low-temperature fabrication method for highly porous bioactive scaffolds was developed. The two-step method involved the foaming of tricalcium silicate cement paste and hydration to form calcium silicate hydrate and calcium hydroxide. Scaffolds with a combination of interconnected macro- and

  14. Tracing metal–silicate segregation and late veneer in the Earth and the ureilite parent body with palladium stable isotopes

    DEFF Research Database (Denmark)

    Creech, J. B.; Moynier, F.; Bizzarro, Martin

    2017-01-01

    Stable isotope studies of highly siderophile elements (HSE) have the potential to yield valuable insights into a range of geological processes. In particular, the strong partitioning of these elements into metal over silicates may lead to stable isotope fractionation during metal–silicate segrega...... with a late-veneer of chondritic material after core formation....

  15. Pre-hydrolysed ethyl silicate as an alternative precursor for SiO{sub 2}-coated carbon nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Barrena, M.I., E-mail: ibarrena@quim.ucm.es [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Av. Complutense s/n, 28040 Madrid (Spain); Gomez de Salazar, J.M.; Soria, A.; Matesanz, L. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Av. Complutense s/n, 28040 Madrid (Spain)

    2011-11-15

    This work reported basically aims at understanding the extent of SiO{sub 2}-coated carbon nanofibers using two different sol-gel precursors for the silicate glass. The silicate precursors employed were tetraethoxysilane (TEOS) and pre-hydrolysed ethyl silicate. The first route consisted in an acid hydrolysis and polycondensation of the TEOS and the second one in a polycondensation of the pre-hydrolysed ethyl silicate. The techniques of Fourier Infra Red spectroscopy, thermogravimetric analysis, scanning electron microscopy and X-ray diffraction were used to characterize the materials obtained. Both kinds of SiO{sub 2} precursor can coat the CNF effectively. However, the use of pre-hydrolysed ethyl silicate (faster gelation times and higher surface areas) can be considered a low-cost and facile alternative with respect to the use of TEOS, to obtain industrially silica-coated carbon nanofibers.

  16. Effects of polymer intercalation in calcium silicate hydrates on drug loading capacities and drug release kinetics: an X-ray absorption near edge structure study

    National Research Council Canada - National Science Library

    Guo, Xiaoxuan; Zhu, Ying-Jie; Hu, Yongfeng; Wu, Jin; Yiu, Yun-Mui; Sham, Tsun-Kong

    2017-01-01

    Different calcium silicate hydrate (CSH)/polymer composites are synthesized by using a controlled precipitation reaction between calcium salt and silicate salt, followed by the addition of various polymer solutions at room temperature...

  17. A general route to hollow mesoporous rare-earth silicate nanospheres as a catalyst support.

    Science.gov (United States)

    Jin, Renxi; Yang, Yang; Zou, Yongcun; Liu, Xianchun; Xing, Yan

    2014-02-17

    Hollow mesoporous structures have recently aroused intense research interest owing to their unique structural features. Herein, an effective and precisely controlled synthesis of hollow rare-earth silicate spheres with mesoporous shells is reported for the first time, produced by a simple hydrothermal method, using silica spheres as the silica precursors. The as-prepared hollow rare-earth silicate spheres have large specific surface area, high pore volume, and controllable structure parameters. The results demonstrate that the selection of the chelating reagent plays critical roles in forming the hollow mesoporous structures. In addition, a simple and low-energy-consuming approach to synthesize highly stable and dispersive gold nanoparticle-yttrium silicate (AuNPs/YSiO) hollow nanocomposites has also been developed. The reduction of 4-nitrophenol with AuNPs/YSiO hollow nanocomposites as the catalyst has clearly demonstrated that the hollow rare-earth silicate spheres are good carriers for Au nanoparticles. This strategy can be extended as a general approach to prepare multifunctional yolk-shell structures with diverse compositions and morphologies simply by replacing silica spheres with silica-coated nanocomposites. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Solid-phase extraction of plant thionins employing aluminum silicate based extraction columns.

    Science.gov (United States)

    Hussain, Shah; Güzel, Yüksel; Pezzei, Cornelia; Rainer, Matthias; Huck, Christian W; Bonn, Günther K

    2014-08-01

    Thionins belong to a family of cysteine-rich, low-molecular-weight (∼5 KDa) biologically active proteins in the plant kingdom. They display a broad cellular toxicity against a wide range of organisms and eukaryotic cell lines. Thionins protect plants against different pathogens, including bacteria and fungi. A highly selective solid-phase extraction method for plant thionins is reported deploying aluminum silicate (3:2 mullite) powder as a sorbent in extraction columns. Mullite was shown to considerably improve selectivity compared to a previously described zirconium silicate embedded poly(styrene-co-divinylbenzene) monolithic polymer. Due to the presence of aluminum(III), mullite offers electrostatic interactions for the selective isolation of cysteine-rich proteins. In comparison to zirconium(IV) silicate, aluminum(III) silicate showed reduced interactions towards proteins which resulted into superior washings of unspecific compounds while still retaining cysteine-rich thionins. In the presented study, European mistletoe, wheat and barley samples were subjected to solid-phase extraction analysis for isolation of viscotoxins, purothionins and hordothionins, respectively. Matrix-assisted laser desorption/ionization time of flight mass spectroscopy was used for determining the selectivity of the sorbent toward thionins. The selectively retained thionins were quantified by colorimetric detection using the bicinchoninic acid assay. For peptide mass-fingerprint analysis tryptic digests of eluates were examined. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Multiple ways of producing intermediate and silicic rocks within Thingmúli and other Icelandic volcanoes

    DEFF Research Database (Denmark)

    Charreteur, Gilles; Tegner, Christian; Haase, Karsten

    2013-01-01

    Major and trace element compositions of rocks and coexisting phenocrysts of the ThingmA(0)li volcano suggest a revision of the existing models for the formation of intermediate and silicic melts in Iceland. The new data define two compositional tholeiitic trends with a significant gap between them...

  20. Investigation on the effects of combining lime and sodium silicate for ...

    African Journals Online (AJOL)

    Expansive clay is unsuitable subgrade material covering about 40% of the area of Ethiopia. Engineering properties of such problematic soils can be improved by chemical stabilization. This study investigated the effects of combining slightly alkaline liquid sodium silicate with hydrated lime for stabilization of expansive clay.

  1. Analysis of the color alteration and radiopacity promoted by bismuth oxide in calcium silicate cement.

    Science.gov (United States)

    Marciano, Marina Angélica; Estrela, Carlos; Mondelli, Rafael Francisco Lia; Ordinola-Zapata, Ronald; Duarte, Marco Antonio Hungaro

    2013-01-01

    The aim of the study was to determine if the increase in radiopacity provided by bismuth oxide is related to the color alteration of calcium silicate-based cement. Calcium silicate cement (CSC) was mixed with 0%, 15%, 20%, 30% and 50% of bismuth oxide (BO), determined by weight. Mineral trioxide aggregate (MTA) was the control group. The radiopacity test was performed according to ISO 6876/2001. The color was evaluated using the CIE system. The assessments were performed after 24 hours, 7 and 30 days of setting time, using a spectrophotometer to obtain the ΔE, Δa, Δb and ΔL values. The statistical analyses were performed using the Kruskal-Wallis/Dunn and ANOVA/Tukey tests (pbismuth oxide was added showed radiopacity corresponding to the ISO recommendations (>3 mm equivalent of Al). The MTA group was statistically similar to the CSC/30% BO group (p>0.05). In regard to color, the increase of bismuth oxide resulted in a decrease in the ΔE value of the calcium silicate cement. The CSC group presented statistically higher ΔE values than the CSC/50% BO group (pbismuth oxide has no relation to the color alteration of calcium silicate-based cements.

  2. Powder synthesis, processing and characterization of lanthanum silicates for SOFC application

    Energy Technology Data Exchange (ETDEWEB)

    Jothinathan, E.; Vanmeensel, K. [Department of Metallurgy and Materials Engineering, Kasteelpark Arenberg 44, B-3001 Heverlee, Leuven (Belgium); Vleugels, J., E-mail: jozef.vleugels@mtm.kuleuven.b [Department of Metallurgy and Materials Engineering, Kasteelpark Arenberg 44, B-3001 Heverlee, Leuven (Belgium); Van der Biest, O. [Department of Metallurgy and Materials Engineering, Kasteelpark Arenberg 44, B-3001 Heverlee, Leuven (Belgium)

    2010-04-16

    Recent studies have shown that rare earth silicates exhibit higher oxygen conductivity at lower temperatures (500-800 {sup o}C) compared to traditional yttria-stabilized cubic zirconia. Among the rare earth silicates, doped lanthanum silicates are known to exhibit higher ionic conductivity. The difficulty in sinterability of these powders combined with the fact that the electrolyte material should be sintered onto a porous anode material in a single sintering step to produce SOFC half cells requires very fine starting powders with high sinterability at lower temperatures (1000-1200 {sup o}C). In this paper, we report on the synthesis of lanthanum silicates doped with aluminium or iron using the sol-gel process. Using this fairly simple and quick process, nanometer sized powders with an average grain size below 100 nm have been synthesised, while the intrinsic nanostructure could be maintained in the fully densified electrolyte material after pulsed electric current sintering (PECS) at 1100-1200 {sup o}C.

  3. Anthropogenic Origin of Siliceous Scoria Droplets from Pleistocene and Holocene Archeaological Sites in Northern Syria

    DEFF Research Database (Denmark)

    Thy, Peter; Willcox, George; Barfod, Gry

    2015-01-01

    to archaeological sites. We therefore conclude that melting of building earth in ancient settlements can occur during !res reaching modest temperatures. There is no evidence to suggest that siliceous scoria droplets result from very high temperature melting of soil and are the result of a cosmic event....

  4. Influence of silicate on enrichment of highly productive microalgae from a mixed culture

    NARCIS (Netherlands)

    Mooij, P.R.; De Jongh, L.D.; Van Loosdrecht, M.C.M.; Kleerebezem, R.

    2015-01-01

    Microalgae have the potential to supply a biobased society with essential feedstocks like sugar and lipids. Besides being productive, strains used for this purpose should grow fast, be resistant to predators, and have good harvestability properties. Diatoms, a class of siliceous algae, have these

  5. Effect of soaking of seeds in potassium silicate and uniconazole on ...

    African Journals Online (AJOL)

    Jane

    2011-07-13

    Jul 13, 2011 ... uniconazole on seed germination and seedling growth of two tomato cultivars. Tomato ( ... containing either 50 or 100 mg L-1 potassium silicate or uniconazole and were placed in an environment controlled chamber (25°C, .... determined with a leaf area meter (LI-3100 area meter, LI-COR. Inc., Lincoln ...

  6. Core Formation on Asteroid 4 Vesta: Iron Rain in a Silicate Magma Ocean

    Science.gov (United States)

    Kiefer, Walter S.; Mittlefehldt, David W.

    2017-01-01

    Geochemical observations of the eucrite and diogenite meteorites, together with observations made by NASA's Dawn spacecraft, suggest that Vesta resembles H chondrites in bulk chemical composition, possibly with about 25% of a CM-chondrite like composition added in. For this model, the core is 15% by mass (or 8 volume %) of the asteroid. The abundances of moderately siderophile elements (Ni, Co, Mo, W, and P) in eucrites require that essentially all of the metallic phase in Vesta segregated to form a core prior to eucrite solidification. Melting in the Fe-Ni-S system begins at a cotectic temperature of 940 deg. C. Only about 40% of the total metal phase, or 3-4 volume % of Vesta, melts prior to the onset of silicate melting. Liquid iron in solid silicate initially forms isolated pockets of melt; connected melt channels, which are necessary if the metal is to segregate from the silicate, are only possible when the metal phase exceeds about 5 volume %. Thus, metal segregation to form a core does not occur prior to the onset of silicate melting.

  7. Synthesis of a novel polyester building block from pentoses by tin-containing silicates

    DEFF Research Database (Denmark)

    Elliot, Samuel Gilbert; Andersen, Christian; Tolborg, Søren

    2017-01-01

    We report here the direct formation of the new chemical product, trans-2,5-dihydroxy-3-pentenoic acid methyl ester, from pentoses using tin-containing silicates as catalysts. The product is formed under alkali-free conditions in methanol at temperatures in the range 140–180 °C. The highest yields...

  8. The effect of inversion of matrix and inclusions composition in liquation phospho-silicate glasses.

    Science.gov (United States)

    Sitarz, M

    2011-08-15

    Silico-phosphate glasses of XCaPO(4)-SiO(2) and XCaPO(4)-AlPO(4)-SiO(2) (X=Na(+) and/or K(+)) system have been the subject of the presented investigations. Glasses belonging to those systems are characterized by a liquation phenomenon-spherical amorphous inclusions dispersed in an amorphous matrix. Thorough EDX investigations have shown that introduction of aluminum ions into the structure of phospho-silicate glasses results in inversion of matrix and inclusions composition, when XCaPO(4) exceeds 25-35% mol. Such a substantial influence of aluminum ions on phospho-silicate glasses texture as well as matrix and inclusions composition (inversion) must be a result of structural changes. (27)Al MAS NMR research stated that aluminum ions in structures of XCaPO(4)-AlPO(4)-SiO(2) phospho-silicate glasses always acts as a glass-forming ion-i.e. aluminum always occupies fourfold coordinated sites. (23)Na and (31)P MAS NMR research has shown that the inversion of matrix and inclusions composition, brought about by introduction of aluminum ions into the structure of phospho-silicate glasses, is an outcome of a change in phosphorous and alkaline ions coordination. Copyright © 2010 Elsevier B.V. All rights reserved.

  9. THE EFFECT OF VARIOUS SILICATE-GLASS MATRIXES ON GOLD-NANOPARTICLE FORMATION

    National Research Council Canada - National Science Library

    Svecova, Blanka

    2016-01-01

    Ion implantation of Au+ with energy of 1.7 MeV and a fluence of 1 x 1016 ions.cm-2 along with post-implantation annealing were used to synthesize metal nanoparticles in various types of silicate glasses...

  10. Core–shell Au/Ag nanoparticles embedded in silicate sol–gel ...

    Indian Academy of Sciences (India)

    Administrator

    physical rigidity, biodegradation, electrochemical, photochemical, thermal stabilities and optical trans- parency. 14–17 .... charge transfer resistance (Rct) for GC/MTMOS modified electrode due to the silicate matrix film on .... ficient of n = 0⋅99 at a signal to noise ratio of 3. The detection limit was experimentally estimated as.

  11. Characterization of chitosan-magnesium aluminum silicate nanocomposite films for buccal delivery of nicotine

    DEFF Research Database (Denmark)

    Pongjanyakul, Thaned; Khunawattanakul, Wanwisa; Strachan, Clare J

    2013-01-01

    The objective of this study was to prepare and characterize chitosan-magnesium aluminum silicate (CS-MAS) nanocomposite films as a buccal delivery system for nicotine (NCT). The effects of the CS-MAS ratio on the physicochemical properties, release and permeation, as well as on the mucoadhesive...

  12. Lysozyme-magnesium aluminum silicate microparticles: Molecular interaction, bioactivity and release studies

    DEFF Research Database (Denmark)

    Kanjanakawinkul, Watchara; Medlicott, Natalie J.; Rades, Thomas

    2015-01-01

    The objectives of this study were to investigate the adsorption behavior of lysozyme (LSZ) onto magnesium aluminum silicate (MAS) at various pHs and to characterize the LSZ–MAS microparticles obtained from the molecular interaction between LSZ and MAS. The results showed that LSZ could be bound...

  13. Effect of magnesium aluminum silicate glass on the thermal shock resistance of BN matrix composite ceramics

    NARCIS (Netherlands)

    Cai, Delong; Jia, Dechang; Yang, Zhihua; Zhu, Qishuai; Ocelik, Vaclav; Vainchtein, Ilia D.; De Hosson, Jeff Th M.; Zhou, Yu

    The effects of magnesium aluminum silicate (MAS) glass on the thermal shock resistance and the oxidation behavior of h-BN matrix composites were systematically investigated at temperature differences from 600 degrees C up to 1400 degrees C. The retained strength rate of the composites rose with the

  14. Distribution of nickel between copper-nickel and alumina saturated iron silicate slags

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, R.G.; Acholonu, C.C.

    1984-03-01

    The solubility of nickel in slag is determined in this article by equilibrating copper-nickel alloys with alumina-saturated iron silicate slags in an alumina crucible at 1573 K. The results showed that nickel dissolves in slag both as nickel oxide and as nickel metal. The presence of alumina is shown to increase the solubility of nickel in slags.

  15. Water transport in the nano-pore of the calcium silicate phase: reactivity, structure and dynamics.

    Science.gov (United States)

    Hou, Dongshuai; Li, Zongjin; Zhao, Tiejun; Zhang, Peng

    2015-01-14

    Reactive force field molecular dynamics was utilized to simulate the reactivity, structure and dynamics of water molecules confined in calcium-silicate-hydrate (C-S-H) nano-pores of 4.5 nm width. Due to the highly reactive C-S-H surface, hydrolytic reactions occur in the solid-liquid interfacial zone, and partially surface adsorbed water molecules transforming into the Si-OH and Ca-OH groups are strongly embedded in the C-S-H structure. Due to the electronic charge difference, the silicate and calcium hydroxyl groups have binomial distributions of the dipolar moment and water orientation. While Ca-OH contributes to the Ow-downward orientation, the ONB atoms in the silicate chains prefer to accept H-bonds from the surface water molecules. Furthermore, the defective silicate chains and solvated Caw atoms near the surface contribute to the glassy nature of the surface water molecules, with large packing density, pronounced orientation preference, and distorted organization. The stable H-bonds connected with the Ca-OH and Si-OH groups also restrict the mobility of the surface water molecules. The significant reduction of the diffusion coefficient matches well with the experimental results obtained by NMR, QENS and PCFR techniques. Upon increasing the distance from the channel, the structural and dynamic behavior of the water molecules varies and gradually translates into bulk water properties at distances of 10-15 Å from the liquid-solid interface.

  16. In Situ Soft X-ray Spectromicroscopy of Early Tricalcium Silicate Hydration

    Science.gov (United States)

    Bae, Sungchul; Kanematsu, Manabu; Hernández-Cruz, Daniel; Moon, Juhyuk; Kilcoyne, David; Monteiro, Paulo J. M.

    2016-01-01

    The understanding and control of early hydration of tricalcium silicate (C3S) is of great importance to cement science and concrete technology. However, traditional characterization methods are incapable of providing morphological and spectroscopic information about in situ hydration at the nanoscale. Using soft X-ray spectromicroscopy, we report the changes in morphology and molecular structure of C3S at an early stage of hydration. In situ C3S hydration in a wet cell, beginning with induction (~1 h) and acceleration (~4 h) periods of up to ~8 h, was studied and compared with ex situ measurements in the deceleration period after 15 h of curing. Analysis of the near-edge X-ray absorption fine structure showed that the Ca binding energy and energy splitting of C3S changed rapidly in the early age of hydration and exhibited values similar to calcium silicate hydrate (C–S–H). The formation of C–S–H nanoseeds in the C3S solution and the development of a fibrillar C–S–H morphology on the C3S surface were visualized. Following this, silicate polymerization accompanied by C–S–H precipitation produced chemical shifts in the peaks of the main Si K edge and in multiple scattering. However, the silicate polymerization process did not significantly affect the Ca binding energy of C–S–H. PMID:28774096

  17. 40 CFR 721.9514 - Ethyl silicate, reaction products with modified alkoxysilane salt (generic).

    Science.gov (United States)

    2010-07-01

    .... (1) The chemical substance identified generically as Ethyl silicate, reaction products with modified... modified alkoxysilane salt (generic). 721.9514 Section 721.9514 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES...

  18. 78 FR 14540 - Cyromazine, Silica Silicates (Silica Dioxide and Silica Gel), Glufosinate Ammonium, Dioctyl...

    Science.gov (United States)

    2013-03-06

    ... herbicide that acts by inhibiting glutamine synthetase, which leads to poisoning in plants via the...). Silica silicates, silicon dioxide and silica gel, are insecticides and acaracides used in controlling insects at indoor and outdoor sites including a variety of crops. Silicon dioxide is diatomaceous earth, a...

  19. Porosity distribution in root canals filled with gutta percha and calcium silicate cement

    NARCIS (Netherlands)

    Moinzadeh, A.T.; Zerbst, W.; Boutsioukis, C.; Shemesh, H.; Zaslansky, P.

    2015-01-01

    Objective Gutta percha is commonly used in conjunction with a sealer to produce a fluid-tight seal within the root canal fillings. One of the most commonly used filling methods is lateral compaction of gutta percha coupled with a sealer such as calcium silicate cement. However, this technique may

  20. In Situ Soft X-ray Spectromicroscopy of Early Tricalcium Silicate Hydration

    Directory of Open Access Journals (Sweden)

    Sungchul Bae

    2016-12-01

    Full Text Available The understanding and control of early hydration of tricalcium silicate (C3S is of great importance to cement science and concrete technology. However, traditional characterization methods are incapable of providing morphological and spectroscopic information about in situ hydration at the nanoscale. Using soft X-ray spectromicroscopy, we report the changes in morphology and molecular structure of C3S at an early stage of hydration. In situ C3S hydration in a wet cell, beginning with induction (~1 h and acceleration (~4 h periods of up to ~8 h, was studied and compared with ex situ measurements in the deceleration period after 15 h of curing. Analysis of the near-edge X-ray absorption fine structure showed that the Ca binding energy and energy splitting of C3S changed rapidly in the early age of hydration and exhibited values similar to calcium silicate hydrate (C–S–H. The formation of C–S–H nanoseeds in the C3S solution and the development of a fibrillar C–S–H morphology on the C3S surface were visualized. Following this, silicate polymerization accompanied by C–S–H precipitation produced chemical shifts in the peaks of the main Si K edge and in multiple scattering. However, the silicate polymerization process did not significantly affect the Ca binding energy of C–S–H.

  1. Attributes of the soil fertilized with sewage sludge and calcium and magnesium silicate

    Directory of Open Access Journals (Sweden)

    Geraldo R. Zuba Junio

    2015-11-01

    Full Text Available ABSTRACTThis study aimed to evaluate the chemical attributes of an Inceptisol cultivated with castor bean (Ricinus communis L., variety ‘BRS Energia’, fertilized with sewage sludge compost and calcium (Ca and magnesium (Mg silicate. The experiment was conducted at the ICA/UFMG, in a randomized block design, using a 2 x 4 factorial scheme with three replicates, and the treatments consisted of two doses of Ca-Mg silicate (0 and 1 t ha-1 and four doses of sewage sludge compost (0, 23.81, 47.62 and 71.43 t ha-1, on dry basis. Soil organic matter (OM, pH, sum of bases (SB, effective cation exchange capacity (CEC(t, total cation exchange capacity (CEC(T, base saturation (V% and potential acidity (H + Al were evaluated. There were no significant interactions between doses of sewage sludge compost and doses of Ca-Mg silicate on soil attributes, and no effect of silicate fertilization on these attributes. However, fertilization with sewage sludge compost promoted reduction in pH and increase in H + Al, OM and CEC. The dose of 71.43 t ha-1 of sewage sludge compost promoted the best soil chemical conditions.

  2. Productivity and nutritive value of bluestem grass fertilized with calcium and magnesium silicate

    Directory of Open Access Journals (Sweden)

    Cinthya Souza Santana

    2016-01-01

    Full Text Available This study evaluated the effect of application of calcium and magnesium silicate on the productivity, chemical composition and in situ ruminal degradation of bluestem grass (Andropogon gayanus Kunth, cv. Baeti; Embrapa 23 during the rainy and dry seasons. The design consisted of completely randomized blocks in a 6x2 factorial scheme (six silicate doses and two cutting seasons, arranged in plots subdivided over time. The plots were the calcium and magnesium silicate doses (0, 200, 400, 600, 800 and 1,000 kg/ha and the subplots were the two cutting seasons (rainy and dry period, with five repetitions (blocks. The calcium and magnesium silicate doses exerted no significant effect on green or dry matter production, chemical forage composition or degradability parameters. On the other hand, there was an effect of cutting period on forage production and chemical composition. The highest production of green and dry matter was observed during the rainy period, while acid detergent fiber content was higher during the dry season. The treatments did not exert any significant effect on the parameters of degradability that would alter the nutritive value of bluestem grass.

  3. Core-shell Au/Ag nanoparticles embedded in silicate sol-gel ...

    Indian Academy of Sciences (India)

    The electrocatalytic activity of core-shell Au100-Ag ( = 15, 27, 46, and 60) bimetallic nanoparticles embedded in methyl functionalized silicate MTMOS network towards the reduction of hydrogen peroxide was investigated by using cyclic voltammetry and chronoamperometric techniques. Core-shell Au/Ag bimetallic ...

  4. Composition dependence of luminescence of Eu and Eu/Tb doped silicate glasses for LED applications

    DEFF Research Database (Denmark)

    Zhu, C.F.; Chaussedent, S.; Liu, S.

    2013-01-01

    The Eu and Eu/Tb doped silicate glasses are good candidates for light emitting diode (LED) applications. But the optical performance of these glasses is sensitive to variations in chemical composition. In this paper we report our recent findings about the effect of addition of minor components su...... curves....

  5. Electronic structure of iron in magnesium silicate glasses at high pressure

    Science.gov (United States)

    Gu, Chen; Catalli, Krystle; Grocholski, Brent; Gao, Lili; Alp, Ercan; Chow, Paul; Xiao, Yuming; Cynn, Hyunchae; Evans, William J.; Shim, Sang-Heon

    2012-12-01

    A recent study attributed the source of an iron partitioning change between silicate melt and minerals at deep mantle conditions to a high-spin to low-spin change in iron, which was found in a Fe-diluted Mg-silicate glass at a similar pressure. We conducted X-ray emission spectroscopy and nuclear forward scattering on iron-rich Mg-silicate glasses at high pressure and 300 K in the diamond-anvil cell: Al-free glass up to 135 GPa and Al-bearing glass up to 93 GPa. In both glasses, the spin moment decreases gradually from 1 bar and does not reach a complete low-spin state even at the peak pressures of this study. The gradual change may be due to the existence of diverse coordination environments for iron in the glasses and continuous structural adjustment of the disordered system with pressure. If the result can be extrapolated to iron in mantle melts, the small, gradual changes in the spin state of iron may not be the dominant factor explaining the reported sudden change in the partitioning behavior of iron between silicate melt and minerals at lower-mantle pressures.

  6. Electrophoretic deposition of calcium silicate-reduced graphene oxide composites on titanium substrate

    DEFF Research Database (Denmark)

    Mehrali, Mehdi; Akhiani, Amir Reza; Talebian, Sepehr

    2016-01-01

    silicate-reduced graphene oxide (CS-rGO) composites were synthesized, using an in situ hydrothermal method. CS nanowires were uniformly decorated on the rGO, with an appropriate interfacial bonding. The CS-rGO composites behaved like hybrid composites when deposited on a titanium substrate by cathodic...

  7. Preparation and in vivo evaluation of a silicate-based composite bone cement.

    Science.gov (United States)

    Ma, Bing; Huan, Zhiguang; Xu, Chen; Ma, Nan; Zhu, Haibo; Zhong, Jipin; Chang, Jiang

    2017-08-01

    Silicate-based cements have been developed as a class of bioactive and biodegradable bone cements owing to their good in vitro bioactivity and ability to dissolve in a simulated body fluid. Until recently, however, the in vivo evidence of their ability to support bone regeneration is still scarce. In the present study, a pilot in vivo evaluation of a silicate-based composite bone cement (CSC) was carried out in a rabbit femur defect model. The cement was composed of tricalcium silicate, 45S5 bioglass and calcium sulfate, and the self-setting properties of the material were established. The in vivo bone integration and biodegradability of CSC were investigated and compared with those of bioactive glass particulates, and a calcium phosphate cement. The results showed that CSC underwent a relatively slower in vivo degradation as compared with bioactive glass and calcium phosphate cement. Histological observation demonstrated that bone contact area at the interface between the surrounding bone and CSC gradually increased with time proceeding. CSC kept its structural integrity during implantation in vivo because of its acceptable mechanical strength. These results provide evidence of effectiveness in vivo and suggest potential clinical applications of the silicate-based composite bone cements.

  8. Detection of solar wind-produced water in irradiated rims on silicate minerals.

    Science.gov (United States)

    Bradley, John P; Ishii, Hope A; Gillis-Davis, Jeffrey J; Ciston, James; Nielsen, Michael H; Bechtel, Hans A; Martin, Michael C

    2014-02-04

    The solar wind (SW), composed of predominantly ∼1-keV H(+) ions, produces amorphous rims up to ∼150 nm thick on the surfaces of minerals exposed in space. Silicates with amorphous rims are observed on interplanetary dust particles and on lunar and asteroid soil regolith grains. Implanted H(+) may react with oxygen in the minerals to form trace amounts of hydroxyl (-OH) and/or water (H2O). Previous studies have detected hydroxyl in lunar soils, but its chemical state, physical location in the soils, and source(s) are debated. If -OH or H2O is generated in rims on silicate grains, there are important implications for the origins of water in the solar system and other astrophysical environments. By exploiting the high spatial resolution of transmission electron microscopy and valence electron energy-loss spectroscopy, we detect water sealed in vesicles within amorphous rims produced by SW irradiation of silicate mineral grains on the exterior surfaces of interplanetary dust particles. Our findings establish that water is a byproduct of SW space weathering. We conclude, on the basis of the pervasiveness of the SW and silicate materials, that the production of radiolytic SW water on airless bodies is a ubiquitous process throughout the solar system.

  9. Formation and Detection of Clay Network Structure in Poly(propylene) /Layered Silicate Nanocomposites

    NARCIS (Netherlands)

    Abranyi, Agnes; Szazdi, Laszlo; Pukanszky Jr., Bela; Vancso, Gyula J.; Pukanszky, B.; Pukanszky, Bela

    2006-01-01

    The study of the structure and the rheological properties of poly(propylene) (PP)/montmorillonite (MMT)/maleinated PP (MAPP) composites strongly suggests that a silicate network may form under certain conditions. Network formation could not be proven unambiguously with the usual techniques, i.e.,

  10. Energetics of silicate melts from thermal diffusion studies. Annual progress report

    Energy Technology Data Exchange (ETDEWEB)

    Walker, D.

    1992-07-01

    Efforts are reported in the following areas: laboratory equipment (multianvils for high P/T work, pressure media, SERC/DL sychrotron), liquid-state thermal diffusion (silicate liquids, O isotopic fractionation, volatiles, tektites, polymetallic sulfide liquids, carbonate liquids, aqueous sulfate solutions), and liquid-state isothermal diffusion (self-diffusion, basalt-rhyolite interdiffusion, selective contamination, chemical diffusion).

  11. Flow perfusion culture of human mesenchymal stem cells on silicate-substituted tricalcium phosphate scaffolds

    DEFF Research Database (Denmark)

    Jensen, Lea Bjerre; Bünger, Cody; Kassem, Moustapha

    2008-01-01

    Autologous bone grafts are currently the gold standard for treatment of large bone defects, but their availability is limited due to donor site morbidity. Different substitutes have been suggested to replace these grafts, and this study presents a bone tissue engineered alternative using silicate...

  12. Effect of ethyl silicate on salt crystallization resistance of Maastricht limestone

    NARCIS (Netherlands)

    Lubelli, B.A.; Hees, R.P.J.; Nijland, T.G.; Bolhuis, J.

    2014-01-01

    consolidant treatments aim to re-establish the cohesion in declayed materials showing decqay patterns as sanding or powdering. Ethyl silicate (TEOS) is the most used type of consolidant for inorganic porous materials in the last 30 years. This product which works through precipitation of silica gel

  13. Determination of Thermal Conductivity of Silicate Matrix for Applications in Effective Media Theory

    Science.gov (United States)

    Fiala, Lukáš; Jerman, Miloš; Reiterman, Pavel; Černý, Robert

    2018-02-01

    Silicate materials have an irreplaceable role in the construction industry. They are mainly represented by cement-based- or lime-based materials, such as concrete, cement mortar, or lime plaster, and consist of three phases: the solid matrix and air and water present in the pores. Therefore, their effective thermal conductivity depends on thermal conductivities of the involved phases. Due to the time-consuming experimental determination of the effective thermal conductivity, its calculation by means of homogenization techniques presents a reasonable alternative. In the homogenization theory, both volumetric content and particular property of each phase need to be identified. For porous materials the most problematic part is to accurately identify thermal conductivity of the solid matrix. Due to the complex composition of silicate materials, the thermal conductivity of the matrix can be determined only approximately, based on the knowledge of thermal conductivities of its major compounds. In this paper, the thermal conductivity of silicate matrix is determined using the measurement of a sufficiently large set of experimental data. Cement pastes with different open porosities are prepared, dried, and their effective thermal conductivity is determined using a transient heat-pulse method. The thermal conductivity of the matrix is calculated by means of extrapolation of the effective thermal conductivity versus porosity functions to zero porosity. Its practical applicability is demonstrated by calculating the effective thermal conductivity of a three-phase silicate material and comparing it with experimental data.

  14. Composite nanoparticles: A new way to siliceous materials and a model of biosilica synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Annenkov, Vadim V., E-mail: annenkov@lin.irk.ru [Limnological Institute, Siberian Branch of the Russian Academy of Sciences, Irkutsk 664033 (Russian Federation); Pal' shin, Viktor A.; Verkhozina, Olga N. [Limnological Institute, Siberian Branch of the Russian Academy of Sciences, Irkutsk 664033 (Russian Federation); Larina, Lyudmila I. [A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk 664033 (Russian Federation); Danilovtseva, Elena N. [Limnological Institute, Siberian Branch of the Russian Academy of Sciences, Irkutsk 664033 (Russian Federation)

    2015-09-01

    A new polyampholyte based on poly (acrylic acid) which bears pendant polyamine oligomeric chains (average number of the nitrogen atoms is 11.2) is obtained. This polymer is a model of silaffins – proteins playing important role in formation of siliceous structures in diatom algae and sponges. The polymer catalyses condensation of silicic acid. The obtained solutions contain oligosilicates coordinated with the polymer chains. The action of 50,000 g gravity on this solution results in concentrating-induced condensation of the pre-condensed siliceous oligomers. The obtained solid silica contains 4% admixture of the organic polymer which is close to the silica from diatom frustules. These results confirm the hypothesis about formation of biosilica under the action of desiccation agent, e.g. aquaporins. The formation of solid substances during centrifugation of solutions containing soluble oligomers is a new promising approach to inorganic and composite materials which allows to work in aqueous medium and to reuse the organic polymer. - Highlights: • A polyampholyte with pendant polyamine chains is obtained. • The polymer catalyses condensation of silicic acid giving stable solutions. • Gravity-induced (50,000 g) formation of solid silica was observed in these solutions. • The obtained silica is close to biosilica from diatom frustules. • A new approach to inorganic and composite materials is proposed.

  15. Potential of secondary resources as aluminium-silicate precursors for geopolymer synthesis

    NARCIS (Netherlands)

    Valcke, S.L.A.; Pipilikaki, P.; Fischer, H.R.

    2015-01-01

    Secondary resources containing (catcium) atuminium-silicate phases, e.g., fly ash, slag or bottom ash are used as precursor for binders such as geopolymers. Because secondary resources can be highly variable in terms of their potential to dissolve and form reaction products, analytical methods are

  16. Silicate-SiO reaction in a protoplanetary disk recorded by oxygen isotopes in chondrules

    Science.gov (United States)

    Tanaka, Ryoji; Nakamura, Eizo

    2017-07-01

    The formation of planetesimals and planetary embryos during the earliest stages of the solar protoplanetary disk largely determined the composition and structure of the terrestrial planets. Within a few million years of the birth of the Solar System, chondrule formation and the accretion of the parent bodies of differentiated achondrites and the terrestrial planets took place in the inner protoplanetary disk 1,2 . Here we show that, for chondrules in unequilibrated enstatite chondrites, high-precision Δ17O values (where Δ17O is the deviation of the δ17O value from a terrestrial silicate fractionation line) vary significantly (ranging from -0.49 to +0.84‰) and fall on an array with a steep slope of 1.27 on a three-oxygen-isotope plot. This array can be explained by the reaction between an olivine-rich chondrule melt and an SiO-rich gas derived from vaporized dust and nebular gas. Our study suggests that a large proportion of the building blocks of planetary embryos formed by successive silicate-gas interaction processes: silicate-H2O followed by silicate-SiO interactions under more oxidized and reduced conditions, respectively, within a few million years of the formation of the Solar System.

  17. Silicate availability, vertical mixing and grazing control of phytoplankton blooms in mesocosms

    NARCIS (Netherlands)

    Escaravage, V.L.; Prins, T.C.

    2002-01-01

    The present paper explores (i) the way silicate concentrations may control the switch from diatom to non-diatom dominated phytoplankton, (ii) the consequence of mixing intensity and nutrient loading on phytoplankton composition (and potentially harmful species), (iii) to what extent trophic

  18. Calcium-silicate mesoporous nanoparticles loaded with chlorhexidine for both anti- Enterococcus faecalis and mineralization properties.

    Science.gov (United States)

    Fan, Wei; Li, Yanyun; Sun, Qing; Ma, Tengjiao; Fan, Bing

    2016-10-21

    In infected periapical tissues, Enterococcus faecalis is one of the most common dominant bacteria. Chlorhexidine has been proved to show strong antibacterial ability against E. faecalis but is ineffective in promoting mineralization for tissues around root apex. Mesoporous calcium-silicate nanoparticles are newly synthesized biomaterials with excellent ability to promote mineralization and carry-release bioactive molecules in a controlled manner. In this study, mesoporous calcium-silicate nanoparticles were functionalized with chlorhexidine and their releasing profile, antibacterial ability, effect on cell proliferation and in vitro mineralization property were evaluated. The chlorhexidine was successfully incorporated into mesoporous calcium-silicate nanoparticles by a mixing-coupling method. The new material could release chlorhexidine as well as Ca(2+) and SiO3(2-) in a sustained manner with an alkaline pH value under different conditions. The antimicrobial ability against planktonic E. faecalis was dramatically improved after chlorhexidine incorporation. The nanoparticles with chlorhexidine showed no negative effect on cell proliferation with low concentrations. On dentin slices, the new synthesized material demonstrated a similar inhibitory effect on E. faecalis as the chlorhexidine. After being immersed in SBF for 9 days, numerous apatite crystals could be observed on surfaces of the material tablets. Mesoporous calcium-silicate nanoparticles loaded with chlorhexidine exhibited release of ions and chlorhexidine, low cytotoxicity, excellent antibacterial ability and in vitro mineralization. This material could be developed into a new effective intra-canal medication in dentistry or a new bone defect filling material for infected bone defects.

  19. Effect of soaking of seeds in potassium silicate and uniconazole on ...

    African Journals Online (AJOL)

    Experiments were conducted to investigate the effects of soaking seeds in potassium silicate and uniconazole on seed germination and seedling growth of two tomato cultivars. Tomato (Lycopersicum esculentum Mill. 'Seogeon and Seokwang') seeds were put in a Petri dish filled with 15 ml of a solutions containing either ...

  20. Termochemical Models For Slags and Silicate Melts, Review and Perspectives

    Science.gov (United States)

    Ottonello, G.

    Thermochemical models devoted to the comprehension of reactive and mixing properties of silicate melts and slags may be roughly grouped into four main classes: 1) fictive chemical; 2) quasi chemical; 3) fictive structural; 4) polymeric. In the first class we may group the fictive regular mixture approach of Ghiorso and Carmichael [1,2]and its extensions [3-5]and the subregular model of Berman and Brown [6]. To the second class belong the modified quasi chemical approach of Pelton and coworkers [7,8] , and the Kapoor - Froberg cellular model and its extensions [9-11]. The third class has much to share with the second one (and indeed the cellular model could be ascribed to this class as well). To this class belong the "central surround model" of Sastri and Lahiri [12] , the associated solution models of Bjorkman [13], Hastie and coworkers [14]and Goel and coworkers [15], the two sublattice model of Hillert and coworkers [16]and the polynomial expansions of Hoch and Arpshofen [17] . The fourth class encompasses the models of Masson[18-20] , Toop-Samis [21,22]and its extensions [23-25] . The phylosophy beyond each one of the four classes is basically different. Benefits and drawbacks are present in any of them, and applications are often limited to simple systems (or to sufficiently complex systems, in the case of arbitrary deconvolutions of type 1) and to limited P-T ranges. The crucial aspects of the various models will be outlined to some extent. It will be shown that, often, model conflictuality is only appartent and that, in some cases, model failure is unperceived by acritical utilizers. New perspectives in the future research devoted to the comprehension of melt reactivity in compositionally complex systems, with special enphasis on the solubility of gaseous components and unmixing, will be finally discussed. References: [1] Ghiorso M.S. and Carmichael I.S.E. (1980) Contrib. Mineral. Petrol., 71, 323-342. [2] Ghiorso M.S., Carmichael I.S.E., Rivers M.L. and Sack

  1. Deglacial pulses of deep-ocean silicate into the subtropical North Atlantic Ocean.

    Science.gov (United States)

    Meckler, A N; Sigman, D M; Gibson, K A; François, R; Martínez-García, A; Jaccard, S L; Röhl, U; Peterson, L C; Tiedemann, R; Haug, G H

    2013-03-28

    Growing evidence suggests that the low atmospheric CO2 concentration of the ice ages resulted from enhanced storage of CO2 in the ocean interior, largely as a result of changes in the Southern Ocean. Early in the most recent deglaciation, a reduction in North Atlantic overturning circulation seems to have driven CO2 release from the Southern Ocean, but the mechanism connecting the North Atlantic and the Southern Ocean remains unclear. Biogenic opal export in the low-latitude ocean relies on silicate from the underlying thermocline, the concentration of which is affected by the circulation of the ocean interior. Here we report a record of biogenic opal export from a coastal upwelling system off the coast of northwest Africa that shows pronounced opal maxima during each glacial termination over the past 550,000 years. These opal peaks are consistent with a strong deglacial reduction in the formation of silicate-poor glacial North Atlantic intermediate water (GNAIW). The loss of GNAIW allowed mixing with underlying silicate-rich deep water to increase the silicate supply to the surface ocean. An increase in westerly-wind-driven upwelling in the Southern Ocean in response to the North Atlantic change has been proposed to drive the deglacial rise in atmospheric CO2 (refs 3, 4). However, such a circulation change would have accelerated the formation of Antarctic intermediate water and sub-Antarctic mode water, which today have as little silicate as North Atlantic Deep Water and would have thus maintained low silicate concentrations in the Atlantic thermocline. The deglacial opal maxima reported here suggest an alternative mechanism for the deglacial CO2 release. Just as the reduction in GNAIW led to upward silicate transport, it should also have allowed the downward mixing of warm, low-density surface water to reach into the deep ocean. The resulting decrease in the density of the deep Atlantic relative to the Southern Ocean surface promoted Antarctic overturning

  2. Role of the oxidation state of cerium on the ceria surfaces for silicate adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Jihoon [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Moon, Jinok [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Clean/CMP Technology Team, Memory, Samsung Electronics, Hwaseong (Korea, Republic of); Kim, Joo Hyun; Lee, Kangchun [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Hwang, Junha [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Materials R& D Center, K.C.Tech, Anseong (Korea, Republic of); Yoon, Heesung [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Yi, Dong Kee, E-mail: vitalis@mju.ac.kr [Department of Chemistry, Myongji University, Yongin (Korea, Republic of); Paik, Ungyu, E-mail: upaik@hanyang.ac.kr [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of)

    2016-12-15

    Highlights: • We investigated the role of Ce oxidation state (Ce{sup 3+}/Ce{sup 4+}) on the CeO{sub 2} surfaces for the silicate adsorption. • As the Ce{sup 3+} concentration increased from 19.3 to 27.6%, the surface density of −OH group increased from 0.34 to 0.72 OH/nm{sup 2}. • The Freundlich constant for the relative adsorption capacity (K{sub F}) and adsorption intensity (1/n) indicated that CeO{sub 2} NPs with high Ce{sup 3+} concentration show higher adsorption affinity with silicate ions. - Abstract: In this study, we have investigated the role of the Ce oxidation state (Ce{sup 3+}/Ce{sup 4+}) on the CeO{sub 2} surfaces for silicate adsorption. In aqueous medium, the Ce{sup 3+} sites lead to the formation of −OH groups at the CeO{sub 2} surface through H{sub 2}O dissociation. Silicate ions can adsorb onto the CeO{sub 2} surface through interaction with the −OH groups (−Ce−OH− + −Si−O{sup −} ↔ −Ce−O−Si− + OH{sup −}). As the Ce{sup 3+} concentration increased from 19.3 to 27.6%, the surface density of −OH group increased from 0.34 to 0.72 OH/nm{sup 2}. To evaluate the adsorption behaviors of silicate ions onto CeO{sub 2} NPs, we carried out an adsorption isothermal analysis, and the adsorption isotherm data followed the Freundlich model. The Freundlich constant for the relative adsorption capacity (K{sub F}) and adsorption intensity (1/n) indicated that CeO{sub 2} NPs with high Ce{sup 3+} concentration show higher adsorption affinity with silicate ions. As a result, we have demonstrated that the Ce oxidation state (Ce{sup 3+}/Ce{sup 4+}) on the CeO{sub 2} surface can have a significant influence on the silicate adsorption.

  3. Hydration characteristics and environmental friendly performance of a cementitious material composed of calcium silicate slag

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Na; Li, Hongxu [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Key Laboratory of Rare and Precious Metals Green Recycling and Extraction, University of Science and Technology Beijing, Beijing 100083 (China); Zhao, Yazhao [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Liu, Xiaoming, E-mail: liuxm@ustb.edu.cn [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Key Laboratory of Rare and Precious Metals Green Recycling and Extraction, University of Science and Technology Beijing, Beijing 100083 (China)

    2016-04-05

    Highlights: • Cementitious material was designed according to [SiO{sub 4}] polymerization degree of raw materials. • The cementitious material composed of calcium silicate slag yields excellent physical and mechanical properties. • Amorphous C–A–S–H gel and rod-like ettringite are predominantly responsible for the strength development. • Leaching toxicity and radioactivity tests show the cementitious material is environmentally acceptable. - Abstract: Calcium silicate slag is an alkali leaching waste generated during the process of extracting Al{sub 2}O{sub 3} from high-alumina fly ash. In this research, a cementitious material composed of calcium silicate slag was developed, and its mechanical and physical properties, hydration characteristics and environmental friendly performance were investigated. The results show that an optimal design for the cementitious material composed of calcium silicate slag was determined by the specimen CFSC7 containing 30% calcium silicate slag, 5% high-alumina fly ash, 24% blast furnace slag, 35% clinker and 6% FGD gypsum. This blended system yields excellent physical and mechanical properties, confirming the usefulness of CFSC7. The hydration products of CFSC7 are mostly amorphous C–A–S–H gel, rod-like ettringite and hexagonal-sheet Ca(OH){sub 2} with small amount of zeolite-like minerals such as CaAl{sub 2}Si{sub 2}O{sub 8}·4H{sub 2}O and Na{sub 2}Al{sub 2}Si{sub 2}O{sub 8}·H{sub 2}O. As the predominant hydration products, rod-like ettringite and amorphous C–A–S–H gel play a positive role in promoting densification of the paste structure, resulting in strength development of CFSC7 in the early hydration process. The leaching toxicity and radioactivity tests results indicate that the developed cementitious material composed of calcium silicate slag is environmentally acceptable. This study points out a promising direction for the proper utilization of calcium silicate slag in large quantities.

  4. Energetically benign synthesis of lanthanum silicate through “silica garden” route and its characterization

    Energy Technology Data Exchange (ETDEWEB)

    Parmar, Kavita [Central University of Jharkhand, Ranchi (India); Bhattacharjee, Santanu, E-mail: santanu@nmlindia.org [CSIR-National Metallurgical Laboratory, Jamshedpur (India)

    2017-06-15

    Lanthanum silicate synthesis through “silica garden” route has been reported as an alternative to energy intensive milling procedure. Under optimum conditions lanthanum chloride crystals react with water glass (sodium silicate) to produce self generating hollow lanthanum silicate precipitation tube(s) (LaSPT). The micro tubes are irregular, thick, white coloured and amorphous but are hierarchically built from smaller tubules of 10–20 nm diameters. They retain their amorphous nature on being heated up to 600 °C beyond which crystallization starts. The major phase in the LaSPT heated at 900 °C is La{sub 2}Si{sub 2}O{sub 7}. “As synthesized” LaSPT is heterogeneous and comprises non stoichiometric phases. The exterior and interior surfaces of these tubes are remarkably different in their morphology and chemical composition. LaSPT sintered at 1200 and 1300 °C show fair amount of ionic conductivity. - Graphical abstract: Lanthanum silicate precipitation tube (LaSPT) produced through ‘silica garden’ route offers a green alternative to energy intensive milling procedure. - Highlights: • La-silicate precipitation tube (LaSPT) synthesized via silica garden route. • The microtubes are irregular, thick, white coloured and amorphous. • They are hierarchically built from smaller tubules of 10–20 nm diameters. • The major phase in the LaSPT heated at 900 °C is La{sub 2}Si{sub 2}O{sub 7}. • LaSPT sintered at 1200 °C is fairly conducting.

  5. Development of novel tricalcium silicate-based endodontic cements with sintered radiopacifier phase.

    Science.gov (United States)

    Xuereb, M; Sorrentino, F; Damidot, D; Camilleri, Josette

    2016-06-01

    All implants, bone and endodontic cements need to be sufficiently radiopaque to be able to be distinguished from neighbouring anatomical structures post-operatively. For this purpose, radiopacifying materials are added to the cements to render them sufficiently radiopaque. Bismuth oxide has been quite a popular choice of radiopacifier in endodontic materials. It has been shown to cause dental discoloration. The aim of this study was to develop, characterize and assess the properties of tricalcium silicate cement with alternative radiopacifiers, which are either inter-ground or sintered to the tricalcium silicate cement. Custom-made endodontic cements based on tricalcium silicate and 20 % barium, calcium or strontium zirconate, which were either inter-ground or sintered at high temperatures, were produced. The set materials stored for 28 days in Hank's balanced salt solution were characterized by scanning electron microscopy and X-ray diffraction analysis. Assessment of pH, leaching, interaction with physiological solution, radiopacity, setting time, compressive strength and material porosity were investigated. Mineral trioxide aggregate (MTA) Angelus was used as control. Addition of radiopacifying materials improved the radiopacity of the material. The sintered cements exhibited the formation of calcium zirconate together with the respective radiopacifier phase. All materials produced calcium hydroxide on hydration, which interacted with tissue fluids forming hydroxyapatite on the material surface. The physical properties of the tricalcium silicate-based cements were comparable to MTA Angelus. A novel method of producing radiopaque tricalcium silicate-based cements was demonstrated. The novel materials exhibited properties, which were either comparable or else improved over the control. The novel materials can be used to replace MTA for root-end filling, perforation repair and other clinical applications where MTA is indicated.

  6. Thermogravimetric analysis of phase transitions in cement compositions mixed by sodium silicate solution

    Directory of Open Access Journals (Sweden)

    Fedosov Sergey Viktorovich

    2014-01-01

    Full Text Available This paper presents a study of the capability to modify cement by mechanical activation of sodium silicate water solution. Admixtures or blends of binding agents were employed for modifying concrete properties. The liquid glass is applied to protect from chemically or physically unfavorable environmental impacts, such as acidic medium and high temperature. The sodium silicate is a high-capacity setting accelerator. The increasing of the liquid glass proportion in the mix leads to the degradation of the cement paste plasticity and for this reason it is necessary to reduce the amount of liquid glass in the cement paste. The activation of dilute water solution of sodium silicate into rotary pulsating apparatus directly before tempering of the cement paste is an effective way to decrease mass fraction of liquid glass in the cement paste. The results of the combined influence of liquid glass and mechanical activation on physicochemical processes taking place in cement stone are represented in this research. Thermogravimetric analysis was used in order to study cement blends. Thermogravimetric analysis of modified cement stone assays was performed by thermo analyzer SETARAM TGA 92-24. The results of the analysis of phase transition taking place under high-temperature heating of cement stone modified by the mechanical activation of the water solution of the sodium silicate were introduced. Thermograms of cement stone assays were obtained at different hardening age. The comparison of these thermograms allows us to come to a conclusion on the formation and the retention during long time of a more dense structure of the composite matrix mixed by the mechanical activation of sodium silicate water solution. The relation between the concrete composition and its strength properties was stated. Perhaps, the capability of modified concrete to keep calcium ions in sparingly soluble hydrosilicates leads to the increase in its durability and corrosion resistance.

  7. From illite/smectite clay to mesoporous silicate adsorbent for efficient removal of chlortetracycline from water.

    Science.gov (United States)

    Wang, Wenbo; Tian, Guangyan; Zong, Li; Zhou, Yanmin; Kang, Yuru; Wang, Qin; Wang, Aiqin

    2017-01-01

    A series of mesoporous silicate adsorbents with superior adsorption performance for hazardous chlortetracycline (CTC) were sucessfully prepared via a facile one-pot hydrothermal reaction using low-cost illite/smectite (IS) clay, sodium silicate and magnesium sulfate as the starting materials. In this process, IS clay was "teared up" and then "rebuilt" as new porous silicate adsorbent with high specific surface area of 363.52m(2)/g (about 8.7 folds higher than that of IS clay) and very negative Zeta potential (-34.5mV). The inert SiOSi (Mg, Al) bonds in crystal framework of IS were broken to form Si(Al) O(-) groups with good adsorption activity, which greatly increased the adsorption sites served for holding much CTC molecules. Systematic evaluation on adsorption properties reveals the optimal silicate adsorbent can adsorb 408.81mg/g of CTC (only 159.7mg/g for raw IS clay) and remove 99.3% (only 46.5% for raw IS clay) of CTC from 100mg/L initial solution (pH3.51; adsorption temperature 30°C; adsorbent dosage, 3g/L). The adsorption behaviors of CTC onto the adsorbent follows the Langmuir isotherm model, Temkin equation and pseudo second-order kinetic model. The mesopore adsorption, electrostatic attraction and chemical association mainly contribute to the enhanced adsorption properties. As a whole, the high-efficient silicate adsorbent could be candidates to remove CTC from the wastewater with high amounts of CTC. Copyright © 2016. Published by Elsevier B.V.

  8. Photo-induced changes in optical parameters of silicate glasses multiphoton laser radiation absorption

    Science.gov (United States)

    Efimov, Oleg M.; Glebov, Leonid B.; Matveev, Yurii A.; Mekryukov, Andrei M.

    1995-07-01

    In this paper are the results of investigations of the mechanisms of photo-induced changes of alkali-silicate (crown) and lead-silicate (flint) glasses optical parameters upon the exposure to intense laser radiation, and the basic regularities of these processes are reported. These investigations were performed in Research Center 'S.I. Vavilov State Optical Institute' during the last 15 years. The kinetics of stable and unstable CC formation and decay, the effect of widely spread impurity ions on these processes, the characteristics of fundamental and impure luminescence, the kinetics of refractive index change under conditions of multi-photon glass matrix excitation, and other properties are considered. On the basis of analysis of received regularities it was shown that the nonlinear coloration of alkali-silicate glasses (the fundamental absorption edge is nearly 6 eV) takes place only as a result of two-photon absorption. Important efforts were aimed at the detection of three or more photon matrix ionization of these glasses, but they failed. However it was established that in the lead silicate glasses, the long-wave carriers mobility boundary is placed considerably higher than the fundamental absorption edge of material matrix. This results in that the linear color centers formation in the lead silicate glasses is not observed. The coloration of these glasses arises only from the two- or three-photon matrix ionization, and the excitation occurs through virtual states that are placed in the fundamental absorption region. In the report the available mechanisms of photo-induced changes of glasses optical parameters, and some applied aspects of this problem are discussed.

  9. Characterization and nutrient release from silicate rocks and influence on chemical changes in soil

    Directory of Open Access Journals (Sweden)

    Douglas Ramos Guelfi Silva

    2012-06-01

    Full Text Available The expansion of Brazilian agriculture has led to a heavy dependence on imported fertilizers to ensure the supply of the growing food demand. This fact has contributed to a growing interest in alternative nutrient sources, such as ground silicate rocks. It is necessary, however, to know the potential of nutrient release and changes these materials can cause in soils. The purpose of this study was to characterize six silicate rocks and evaluate their effects on the chemical properties of treated soil, assessed by chemical extractants after greenhouse incubation. The experimental design consisted of completely randomized plots, in a 3 x 6 factorial scheme, with four replications. The factors were potassium levels (0-control: without silicate rock application; 200; 400; 600 kg ha-1 of K2O, supplied as six silicate rock types (breccia, biotite schist, ultramafic rock, phlogopite schist and two types of mining waste. The chemical, physical and mineralogical properties of the alternative rock fertilizers were characterized. Treatments were applied to a dystrophic Red-Yellow Oxisol (Ferralsol, which was incubated for 100 days, at 70 % (w/w moisture in 3.7 kg/pots. The soil was evaluated for pH; calcium and magnesium were extracted with KCl 1 mol L-1; potassium, phosphorus and sodium by Mehlich 1; nickel, copper and zinc with DTPA; and the saturation of the cation exchange capacity was calculated for aluminum, calcium, magnesium, potassium, and sodium, and overall base saturation. The alternative fertilizers affected soil chemical properties. Ultramafic rock and Chapada mining byproduct (CMB were the silicate rocks that most influenced soil pH, while the mining byproduct (MB led to high K levels. Zinc availability was highest in the treatments with mining byproduct and Cu in soil fertilized with Chapada and mining byproduct.

  10. Understanding Vesuvius magmatic processes: Evidence from primitive silicate-melt inclusions in medieval scoria clinopyroxenes (Terzigno formation)

    Science.gov (United States)

    Lima, A.; Belkin, H.E.; Torok, K.

    1999-01-01

    Microthermometric investigations of silicate-melt inclusions and electron microprobe analyses were conducted on experimentally homogenized silicate-melt inclusions and on the host clinopyroxenes from 4 scoria samples of different layers from the Mt. Somma-Vesuvius medieval eruption (Formazione di Terzigno, 893 A.D.). The temperature of homogenization, considered the minimum trapping temperature, ranges from 1190 to 1260??5 ??C for all clinopyroxene-hosted silicate melt inclusions. The major and minor-element compositional trends shown by Terzigno scoria and matrix glass chemical analysis are largely compatible with fractional crystallization of clinopyroxene and Fe-Ti oxides. Sulfur contents of the homogenized silicate-melt inclusions in clinopyroxene phenocrysts compared with that in the host scoria show that S has been significantly degassed in the erupted products; whereas, Cl has about the same abundance in the inclusions and in host scoria. Fluorine is low (infrequently up to 800 ppm) in the silicate-melt inclusions compared to 2400 ppm in the bulk scoria. Electron microprobe analyses of silicate-melt inclusions show that they have primitive magma compositions (Mg# = 75-91). The composition of the host clinopyroxene phenocrysts varies from typical plinian-related (Mg#???85) to non-plinian related (Mg#???85). The mixed source of the host clinopyroxenes and primitive nature of the silicate-melt inclusions implies that these phenocrysts, in part, may be residual and/or have a polygenetic origin. The similar variation trends of major and minor-elements between homogenized silicate-melt inclusions from the Terzigno scoria, and silicate-melt inclusions in olivine and diopside phenocrysts from plinian eruptions (Marianelli et al., 1995) suggest that the trapped inclusions represent melts similar to those that supplied the plinian and sub-plinian magma chambers. These geochemical characteristics suggest that the Vesuvius magmatic system retained a vestige of the most

  11. The evolution of immiscible silicate and fluoride melts: Implications for REE ore-genesis

    Science.gov (United States)

    Vasyukova, O.; Williams-Jones, A. E.

    2016-01-01

    The Mid-Proterozoic peralkaline Strange Lake pluton (Québec-Labrador, Canada) exhibits extreme enrichment in high field strength elements (HFSE), including the rare earth elements (REE), particularly in pegmatites. On the basis of a study of melt inclusions, we proposed recently that fluoride-silicate melt immiscibility played an important and perhaps dominant role in concentrating the REE within the pluton. Here we present further evidence for silicate-fluoride immiscibility at Strange Lake from a sample of the hypersolvus granite, which contains an inclusion composed largely of REE and HFSE minerals. The inclusion (∼5 cm in diameter) comprises a narrow rim containing chevkinite-(Ce) and zircon in a fluorite matrix, a core of fluorbritholite-(Ce) and bastnäsite-(Ce) and a transition zone between the rim and the core consisting of a fine-grained intergrowth of bastnäsite-(Ce), gagarinite-(Y) and fluorite. We propose that the inclusion formed as a result of silicate-fluoride immiscibility, which occurred early in the emplacement history of the Strange Lake pluton, and that it represents the fluoride melt. After separation of the two melts, the boundary between them acted as a locus of crystallisation, where crystals formed repeatedly due to heterogeneous (surface catalysed) nucleation. Zircon crystallised shortly after melt phase separation, and was followed by the growth of perthite together with arfvedsonite and quartz. As a result, the silicate melt surrounding the fluoride inclusion became enriched in volatiles that facilitated crystallisation of progressively larger crystals in the inclusion; large crystals of arfvedsonite and perthite were succeeded by even larger crystals of quartz. Massive crystallisation of chevkinite-(Ce) followed, forming the rim of the inclusion. The fluoride melt, which constituted the matrix to the silicate minerals and chevkinite-(Ce), crystallised after chevkinite-(Ce), forming fluorbritholite-(Ce) and fluorite. Aqueous fluid

  12. Making Earth's earliest continental crust - an analogue from voluminous Neogene silicic volcanism in NE-Iceland

    Science.gov (United States)

    Berg, Sylvia E.; Troll, Valentin R.; Burchardt, Steffi; Riishuus, Morten S.; Deegan, Frances M.; Harris, Chris; Whitehouse, Martin J.; Gústafsson, Ludvik E.

    2014-05-01

    Borgarfjörður Eystri in NE-Iceland represents the second-most voluminous exposure of silicic eruptive rocks in Iceland and is a superb example of bimodal volcanism (Bunsen-Daly gap), which represents a long-standing controversy that touches on the problem of crustal growth in early Earth. The silicic rocks in NE-Iceland approach 25 % of the exposed rock mass in the region (Gústafsson et al., 1989), thus they significantly exceed the usual ≤ 12 % in Iceland as a whole (e.g. Walker, 1966; Jonasson, 2007). The origin, significance, and duration of the voluminous (> 300 km3) and dominantly explosive silicic activity in Borgarfjörður Eystri is not yet constrained (c.f. Gústafsson, 1992), leaving us unclear as to what causes silicic volcanism in otherwise basaltic provinces. Here we report SIMS zircon U-Pb ages and δ18O values from the region, which record the commencement of silicic igneous activity with rhyolite lavas at 13.5 to 12.8 Ma, closely followed by large caldera-forming ignimbrite eruptions from the Breiðavik and Dyrfjöll central volcanoes (12.4 Ma). Silicic activity ended abruptly with dacite lava at 12.1 Ma, defining a ≤ 1 Myr long window of silicic volcanism. Magma δ18O values estimated from zircon range from 3.1 to 5.5 (± 0.3; n = 170) and indicate up to 45 % assimilation of a low-δ18O component (e.g. typically δ18O = 0 ‰, Bindeman et al., 2012). A Neogene rift relocation (Martin et al., 2011) or the birth of an off-rift zone to the east of the mature rift associated with a thermal/chemical pulse in the Iceland plume (Óskarsson & Riishuus, 2013), likely brought mantle-derived magma into contact with fertile hydrothermally-altered basaltic crust. The resulting interaction triggered large-scale crustal melting and generated mixed-origin silicic melts. Such rapid formation of silicic magmas from sustained basaltic volcanism may serve as an analogue for generating continental crust in a subduction-free early Earth (e.g. ≥ 3 Ga, Kamber et

  13. Silicate and Carbonatite Melts in the Mantle: Adding CO2 to the pMELTS Thermodynamic Model of Silicate Phase Equilibria

    Science.gov (United States)

    Antoshechkina, P. M.; Shorttle, O.

    2016-12-01

    The current rhyolite-MELTS algorithm includes a mixed H2O-CO2 vapor phase, and a self-consistent speciation model for CO2 and CaCO3 in the silicate liquid (Ghiorso & Gualda 2012; 2015). Although intended primarily to model crustal differentiation and degassing, GG15 captures much of the experimentally-observed melting behavior of CO2-rich mafic lithologies, including generation of small-degree carbonatite melts, a miscibility gap between carbonatite and silicate liquids at low P and a smooth transition to a single carbonated-silicate melt at high P (e.g. Dasgupta et al. 2007). However, solid and liquid carbonate phases were not used in calibration of GG15, and it is suitable only for P MySQL database, adapted from LEPR (Hirschmann et al. 2008). Here, we further extend our database, e.g. to include multiple carbonate phases, and combine the calibration scheme with the libalphaMELTS interface to the rhyolite-MELTS, pMELTS, and H2O-CO2 fluid thermodynamic models (see magmasource.caltech.edu/alphamelts). We use a Monte-Carlo type calibration approach to fit the observed phases and compositions, though stop short of a fully Bayesian formulation. The CO2-fluid experimental database has been updated to include more recent and higher P studies, adding approximately 40 pure fluid plus liquid constraints that conform to the selection criteria used in GG15. To further expand the database, we plan to use some or all of: solid carbonate-bearing experiments; coexisting silicate and carbonatite liquids; phase-present, and phase-absent constraints. As a first approximation, we include four carbonate phases: pure calcite and aragonite, and binary solutions for dolomite-ankerite and magnesite-siderite. Following GG15, we have adopted the CO2 fluid model of Duan & Zhang (2006) and added CO2 and CaCO3 species to the pMELTS liquid model. A key question that we hope to address during calibration is whether a Na2CO3 liquid species is justified instead of, or in addition to, CaCO3 for the

  14. Relations between structure and material properties in earth alkaline silicate basing phosphors; Struktureigenschaftsbeziehungen in Erdalkalisilikat basierenden Leuchtstoffen

    Energy Technology Data Exchange (ETDEWEB)

    Hempel, Wolfgang

    2008-03-19

    This work is basing on the relation between structure and luminescence of Eu{sup 2+} doped Earth-Alkaline-Silicates. After an overview of Earth-Alkaline-Silicates silicates with an additional cation (Li{sup +}, Al{sup 3+}) and an additional anion (Cl{sup -}, N{sup 3-}) are examined in chapter 4 and 5. Basing on this data an relation between structural influence - like ion-radii, anion and coordination polyeder - and phosphor luminescence is set up. The ability of using as an industrial phosphor is made in the final chapter. (orig.)

  15. Partitioning Behavior of Mn, Fe, Co, Ni and Zn between an Octahedral Site in Olivine and Silicate Melt

    OpenAIRE

    Hashizume, Hideo; Hariya, Yu

    1992-01-01

    Partition coefficients of Mn2+, Fe2+, Co2+, Ni2+ and Zn2+ between olivine and silicate melt have been determined in the system Mg2SiO4-SiO2-H2O at high pressure and temperature. A partition coefficient is defined by the ratio of the concentration of an element in olivine to that of the element in silicate melt. Olivine has two octahedral sites (M1 and M2 sites). Elements are partitioned among an M1, an M2 sites and silicate melt. We distributed the bulk concentration of the element in olivine...

  16. Hard X-ray irradiation of cosmic silicate analogs: structural evolution and astrophysical implications

    Science.gov (United States)

    Gavilan, L.; Jäger, C.; Simionovici, A.; Lemaire, J. L.; Sabri, T.; Foy, E.; Yagoubi, S.; Henning, T.; Salomon, D.; Martinez-Criado, G.

    2016-03-01

    Context. Protoplanetary disks, interstellar clouds, and active galactic nuclei contain X-ray-dominated regions. X-rays interact with the dust and gas present in such environments. While a few laboratory X-ray irradiation experiments have been performed on ices, X-ray irradiation experiments on bare cosmic dust analogs have been scarce up to now. Aims: Our goal is to study the effects of hard X-rays on cosmic dust analogs via in situ X-ray diffraction. By using a hard X-ray synchrotron nanobeam, we seek to simulate cumulative X-ray exposure on dust grains during their lifetime in these astrophysical environments and provide an upper limit on the effect of hard X-rays on dust grain structure. Methods: We prepared enstatite (MgSiO3) nanograins, which are analogs to cosmic silicates, via the melting-quenching technique. These amorphous grains were then annealed to obtain polycrystalline grains. These were characterized via scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) before irradiation. Powder samples were prepared in X-ray transparent substrates and were irradiated with hard X-rays nanobeams (29.4 keV) provided by beamline ID16B of the European Synchrotron Radiation Facility (Grenoble). X-ray diffraction images were recorded in transmission mode, and the ensuing diffractograms were analyzed as a function of the total X-ray exposure time. Results: We detected the amorphization of polycrystalline silicates embedded in an organic matrix after an accumulated X-ray exposure of 6.4 × 1027 eV cm-2. Pure crystalline silicate grains (without resin) do not exhibit amorphization. None of the amorphous silicate samples (pure and embedded in resin) underwent crystallization. We analyze the evolution of the polycrystalline sample embedded in an organic matrix as a function of X-ray exposure. Conclusions: Loss of diffraction peak intensity, peak broadening, and the disappearance of discrete spots and arcs reveal the amorphization

  17. Production of reactive oxygen species from abraded silicates. Implications for the reactivity of the Martian soil

    Science.gov (United States)

    Bak, Ebbe N.; Zafirov, Kaloyan; Merrison, Jonathan P.; Jensen, Svend J. Knak; Nørnberg, Per; Gunnlaugsson, Haraldur P.; Finster, Kai

    2017-09-01

    The results of the Labeled Release and the Gas Exchange experiments conducted on Mars by the Viking Landers show that compounds in the Martian soil can cause oxidation of organics and a release of oxygen in the presence of water. Several sources have been proposed for the oxidizing compounds, but none has been validated in situ and the cause of the observed oxidation has not been resolved. In this study, laboratory simulations of saltation were conducted to examine if and under which conditions wind abrasion of silicates, a process that is common on the Martian surface, can give rise to oxidants in the form of hydrogen peroxide (H2O2) and hydroxyl radicals (ṡOH). We found that silicate samples abraded in simulated Martian atmospheres gave rise to a significant production of H2O2 and ṡOH upon contact with water. Our experiments demonstrated that abraded silicates could lead to a production of H2O2 facilitated by atmospheric O2 and inhibited by carbon dioxide. Furthermore, during simulated saltation the silicate particles became triboelectrically charged and at pressures similar to the Martian surface pressure we observed glow discharges. Electrical discharges can cause dissociation of CO2 and through subsequent reactions lead to a production of H2O2. These results indicate that the reactions linked to electrical discharges are the dominant source of H2O2 during saltation of silicates in a simulated Martian atmosphere, given the low pressure and the relatively high concentration of CO2. Our experiments provide evidence that wind driven abrasion could enhance the reactivity of the Martian soil and thereby could have contributed to the oxidation of organic compounds and the O2 release observed in the Labeled Release and the Gas Exchange experiments. Furthermore, the release of H2O2 and ṡOH from abraded silicates could have a negative effect on the persistence of organic compounds in the Martian soil and the habitability of the Martian surface.

  18. Effect of moisture and chitosan layered silicate on morphology and properties of chitosan/layered silicates films; Efeito do teor de quitosana e do silicato em camadas na morfologia e propriedades dos filmes quitosana/silicatos em camadas

    Energy Technology Data Exchange (ETDEWEB)

    Silva, J.R.M.B. da; Santos, B.F.F. dos; Leite, I.F., E-mail: itamaraf@gmail.com [Universidade Federal da Paraiba (UFPB), PB (Brazil). Centro de Tecnologia. Departamento de Engenharia de Materiais

    2014-07-01

    Thin chitosan films have been for some time an object of practical assessments. However, to obtain biopolymers capable of competing with common polymers a significant improvement in their properties is required. Currently, the technology of obtaining polymer/layered silicates nanocomposites has proven to be a good alternative. This work aims to evaluate the effect of chitosan content (CS) and layered silicates (AN) on the morphology and properties of chitosan/ layered silicate films. CS/AN bionanocomposites were prepared by the intercalation by solution in the proportion 1:1 and 5:1. Then were characterized by infrared spectroscopy (FTIR), diffraction (XRD) and X-ray thermogravimetry (TG). It is expected from the acquisition of films, based on different levels of chitosan and layered silicates, choose the best composition to serve as a matrix for packaging drugs and thus be used for future research. (author)

  19. The solubility of carbon monoxide in silicate melts at high pressures and its effect on silicate phase relations. [in terrestrial and other planetary interiors

    Science.gov (United States)

    Eggler, D. H.; Mysen, B. O.; Hoering, T. C.; Holloway, J. R.

    1979-01-01

    Autoradiographic analysis and gas chromatography were used to measure the solubility in silicate melts of CO-CO2 vapors (30 to 40% CO by thermodynamic calculation) in equilibrium with graphite at temperatures up to 1700 deg C and pressures to 30 kbar. At near-liquidus temperatures CO-CO2 vapors were found to be slightly more soluble than CO2 alone. As a result of the apparently negative temperature dependence of CO solubility, the solubility of CO-CO2 at superliquidus temperatures is less than that of CO2. Melting points of two silicates were depressed more by CO than by CO2. Phase boundary orientations suggest that CO/CO + CO2 is greater in the liquid than in the vapor. The effect of the presence of CO on periodotite phase relations was investigated, and it was found that melts containing both CO and CO2 are nearly as polymerized as those containing only CO2. These results suggest that crystallization processes in planetary interiors can be expected to be about the same, whether the melts contain CO2 alone or CO2 and CO.

  20. Zircon from historic eruptions in Iceland: Reconstructing storage and evolution of silicic magmas

    Science.gov (United States)

    Carley, T.L.; Miller, C.F.; Wooden, J.L.; Bindeman, I.N.; Barth, A.P.

    2011-01-01

    Zoning patterns, U-Th disequilibria ages, and elemental compositions of zircon from eruptions of Askja (1875 AD), Hekla (1158 AD), ??r??faj??kull (1362 AD) and Torfaj??kull (1477 AD, 871 AD, 3100 BP, 7500 BP) provide insights into the complex, extended, histories of silicic magmatic systems in Iceland. Zircon compositions, which are correlated with proximity to the main axial rift, are distinct from those of mid-ocean ridge environments and fall at the low-Hf edge of the range of continental zircon. Morphology, zoning patterns, compositions, and U-Th ages all indicate growth and storage in subvolcanic silicic mushes or recently solidified rock at temperatures above the solidus but lower than that of the erupting magma. The eruptive products were likely ascending magmas that entrained a zircon "cargo" that formed thousands to tens of thousands of years prior to the eruptions. ?? 2011 Springer-Verlag.

  1. Nanoscale Charge Balancing Mechanism in Alkali Substituted Calcium-Silicate-Hydrate Gels

    CERN Document Server

    Özçelik, V Ongun

    2016-01-01

    Alkali-activated materials and related alternative cementitious systems are sustainable material technologies that have the potential to substantially lower CO$_2$ emissions associated with the construction industry. However, the impact of augmenting the chemical composition of the material on the main binder phase, calcium-silicate-hydrate gel, is far from understood, particularly since this binder phase is disordered at the nanoscale. Here, we reveal the presence of a charge balancing mechanism at the molecular level, which leads to stable structures when alkalis (i.e., Na or K) are incorporated into a calcium-silicate-hydrate gel, as modeled using crystalline 14{\\AA} tobermorite. These alkali containing charge balanced structures possess superior mechanical properties compared to their charge unbalanced counterparts. Our results, which are based on first-principles simulations using density functional theory, include the impact of charge balancing on the optimized geometries of the new model phases, format...

  2. Silicate species of water glass and insights for alkali-activated green cement

    Directory of Open Access Journals (Sweden)

    Helén Jansson

    2015-06-01

    Full Text Available Despite that sodium silicate solutions of high pH are commonly used in industrial applications, most investigations are focused on low to medium values of pH. Therefore we have investigated such solutions in a broad modulus range and up to high pH values (∼14 by use of infrared (IR spectroscopy and silicon nuclear magnetic resonance (29Si-NMR. The results show that the modulus dependent pH value leads to more or less charged species, which affects the configurations of the silicate units. This in turn, influences the alkali-activation process of low CO2 footprint cements, i.e. materials based on industrial waste or by-products.

  3. Sorption of Europium in zirconium silicate; Sorcion de Europio en silicato de circonio

    Energy Technology Data Exchange (ETDEWEB)

    Garcia R, G. [ININ, Carretera Mexico-Toluca Km. 36.5, 52045 Estado de Mexico (Mexico)

    2004-07-01

    Some minerals have the property of sipping radioactive metals in solution, that it takes advantage to manufacture contention barriers that are placed in the repositories of nuclear wastes. The more recent investigations are focused in the development of new technologies guided to the sorption of alpha emissors on minerals which avoid their dispersion in the environment. In an effort to contribute to the understanding of this type of properties, some studies of sorption of Europium III are presented like homologous of the americium, on the surface of zirconium silicate (ZrSiO{sub 4}). In this work the results of sorption experiences are presented as well as the interpretation of the phenomena of the formation of species in the surface of the zirconium silicate. (Author)

  4. Oxyhydroxy Silicate Colloids: A New Type of Waterborne Actinide(IV) Colloids

    Science.gov (United States)

    Weiss, Stephan; Hennig, Christoph; Brendler, Vinzenz; Ikeda‐Ohno, Atsushi

    2016-01-01

    Abstract At the near‐neutral and reducing aquatic conditions expected in undisturbed ore deposits or in closed nuclear waste repositories, the actinides Th, U, Np, and Pu are primarily tetravalent. These tetravalent actinides (AnIV) are sparingly soluble in aquatic systems and, hence, are often assumed to be immobile. However, AnIV could become mobile if they occur as colloids. This review focuses on a new type of AnIV colloids, oxyhydroxy silicate colloids. We herein discuss the chemical characteristics of these colloids and the potential implication for their environmental behavior. The binary oxyhydroxy silicate colloids of AnIV could be potentially more mobile as a waterborne species than the well‐known mono‐component oxyhydroxide colloids. PMID:27957406

  5. Production of reactive oxygen species from abraded silicates. Implications for the reactivity of the Martian soil

    DEFF Research Database (Denmark)

    Bak, Ebbe N.; Zafirov, Kaloyan; Merrison, Jonathan P.

    2017-01-01

    , but none has been validated in situ and the cause of the observed oxidation has not been resolved. In this study, laboratory simulations of saltation were conducted to examine if and under which conditions wind abrasion of silicates, a process that is common on the Martian surface, can give rise...... lead to a production of H(2)O(2)facilitated by atmospheric O-2 and inhibited by carbon dioxide. Furthermore, during simulated saltation the silicate particles became triboelectrically charged and at pressures similar to the Martian surface pressure we observed glow discharges. Electrical discharges can...... high concentration of CO2. Our experiments provide evidence that wind driven abrasion could enhance the reactivity of the Martian soil and thereby could have contributed to the oxidation of organic compounds and the O-2 release observed in the Labeled Release and the Gas Exchange experiments...

  6. Verification of Joule heat evolution model for silicate building materials with electrically conductive admixtures

    Science.gov (United States)

    Fiala, Lukáš; Maděra, Jiří; Černý, Robert

    2017-07-01

    Silicate building materials naturally exhibit electrically non-conductive behavior. However, a sufficient amount of electrically conductive admixtures leads to a significant increase of the electrical conductivity. This fact can be utilized in several practical ways, such as for development of self-sensing, electromagnetically-shielding or self-heating materials. In this paper, self-heating ability of chosen silicate material was tested and previously developed heating model was verified by means of comparison of calculated temperature evolution in time data with those experimentally determined by thermocouples placed on lateral sides. Sufficiently electrically conductive mixture with carbon black (CB) in amount of 8.89 % was used for DC experiment. Theoretical data were obtained by subsequent FEM calculations conducted on 3D model of the tested sample.

  7. Enhanced dissolution of silicate minerals by bacteria at near-neutral pH.

    Science.gov (United States)

    Vandevivere, P; Welch, S A; Ullman, W J; Kirchman, D L

    1994-05-01

    Previous studies have shown that various microorganisms can enhance the dissolution of silicate minerals at low (8) pH. However, it was not known if they can have an effect at near-neutral pH. Almost half of 17 isolates examined in this study stimulated bytownite dissolution at near-neutral pH while in a resting state in buffered glucose. Most of the isolates found to stimulate dissolution also oxidized glucose to gluconic acid. More detailed analysis with one of these isolates suggested that this partial oxidation was the predominant, if not sole, mechanism of enhanced dissolution. Enhanced dissolution did not require direct contact between the dissolving mineral and the bacteria. Gluconate-promoted dissolution was also observed with other silicate minerals such as albite, quartz, and kaolinite.

  8. Float processing of high-temperature complex silicate glasses and float baths used for same

    Science.gov (United States)

    Cooper, Reid Franklin (Inventor); Cook, Glen Bennett (Inventor)

    2000-01-01

    A float glass process for production of high melting temperature glasses utilizes a binary metal alloy bath having the combined properties of a low melting point, low reactivity with oxygen, low vapor pressure, and minimal reactivity with the silicate glasses being formed. The metal alloy of the float medium is exothermic with a solvent metal that does not readily form an oxide. The vapor pressure of both components in the alloy is low enough to prevent deleterious vapor deposition, and there is minimal chemical and interdiffusive interaction of either component with silicate glasses under the float processing conditions. Alloys having the desired combination of properties include compositions in which gold, silver or copper is the solvent metal and silicon, germanium or tin is the solute, preferably in eutectic or near-eutectic compositions.

  9. Adsorption of Basic Brown and Chrysophenine from Water Solution by Magnesium Silicate Gel

    Directory of Open Access Journals (Sweden)

    Zhun Zhao

    2015-01-01

    Full Text Available Noncrystalline, high surface area magnesium silicate gel was successfully prepared by hydrothermal method. Such product was characterized by BET and XRD to determine surface area 576.4 m2·g−1, average pore width 2.76 nm, and amorphous surface. The adsorption behaviors of Basic Brown and Chrysophenine on magnesium silicate gel were investigated through changing initial concentration, adsorbent dosage, solution pH, contact time, and temperature. The experimental data was analyzed by the adsorption isotherms and kinetics. The results showed the adsorption progress was fast for Basic Brown, and the adsorption equilibrium was finished in 2 h, while the adsorption equilibrium of Chrysophenine was finished in 7 h. Freundlich isotherm model and second-order kinetic models described the adsorption process very well.

  10. Formation of a low-crystalline Zn-silicate in a stream in SW Sardinia, Italy

    Science.gov (United States)

    Wanty, Richard B.; De Giudici, G.; Onnis, P.; Rutherford, D.; Kimball, B.A.; Podda, F.; Cidu, R.; Lattanzi, P.; Medas, D.

    2013-01-01

    n southwestern Sardinia, Italy, the Rio Naracauli drains a catchment that includes several abandoned mines. The drainage from the mines and associated waste rocks has led to extreme concentrations of dissolved Zn, but because of the near-neutral pH, concentrations of other metals remain low. In the reach from approximately 2300 to 3000 m downstream from the headwaters area, an amorphous Zn-silicate precipitates from the water. In this reach, concentrations of both Zn and silica remain nearly constant, but the loads (measured in mass/time) of both increase, suggesting that new Zn and silica are supplied to the stream, likely from emerging groundwater. Zinc isotope signatures of the solid are heavier than the dissolved Zn by about 0.5 permil in 66/64Zn, suggesting that an extracellular biologically mediated adsorption process may be involved in the formation of the Zn-silicate.

  11. Synthesis and characterization of functional copolymer/organo-silicate nanoarchitectures through interlamellar complex-radical (coterpolymerization

    Directory of Open Access Journals (Sweden)

    2008-09-01

    Full Text Available The functional copolymers, having a combination of rigid/flexible linkages and an ability of complex-formation with interlayered surface of organo-silicate, and their nanocomposites have been synthesized by interlamellar complex-radical (coterpolymerization of intercalated monomer complexes of maleic anhydride (MA and itaconic acid (IA with dimethyl dodecylamine surface modified montmorillonite (organo-MMT (MA…DMDA-MMT and IA…DMDA-MMT n-butyl methacrylate (BMA and/or BMA/styrene monomer mixtures. The results of nanocomposite structure–composition– property relationship studies indicate that interlamellar complex-formation between anhydride/acid units and surface alkyl amine and rigid/flexible linkage balance in polymer chains are important factors providing the effective intercalation/ exfoliation of the polymer chains into the silicate galleries, the formation of nanostructural hybrids with higher thermal stability, dynamic mechanical behaviour and well dispersed morphology.

  12. Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria—A Challenge for Life on Mars

    DEFF Research Database (Denmark)

    Bak, Ebbe Norskov; Larsen, Michael G.; Moeller, Ralf

    2017-01-01

    The habitability of Mars is determined by the physical and chemical environment. The effect of low water availability, temperature, low atmospheric pressure and strong UV radiation has been extensively studied in relation to the survival of microorganisms. In addition to these stress factors......, it was recently found that silicates exposed to simulated saltation in a Mars-like atmosphere can lead to a production of reactive oxygen species. Here, we have investigated the stress effect induced by quartz and basalt abraded in Mars-like atmospheres by examining the survivability of the three microbial model...... in the basalt leading to hydroxyl radicals through Fenton-like reactions. The low survivability of the usually highly resistant D. radiodurans indicates that the effect of abraded silicates, as is ubiquitous on the Martian surface, would limit the habitability of Mars as well as the risk of forward...

  13. Tin-Containing Silicates: Identification of a Glycolytic Pathway via 3-Deoxyglucosone

    DEFF Research Database (Denmark)

    Tolborg, Søren; Meier, Sebastian; Sádaba, I.

    2016-01-01

    Inorganic glycolytic systems, capable of transforming glucose through a cascade of catalytic steps, can lead to efficient chemical processes utilising carbohydrates as feedstock. Tin-containing silicates, such as Sn-Beta, are showing potential for the production of lactates from sugars through......-containing silicates. It is possible to influence the relative carbon flux through these pathways by controlling the amount of alkali metal salts present in the reaction mixture. In the absence of added potassium carbonate, at least 15–30% carbon flux via 3-deoxyglucosone is observed. Addition of just a few ppm...... of potassium carbonate makes retro-aldol pathways dominant and responsible for about 60-70% of the overall carbon flux. The 3-deoxyglucosone pathway results in new types of chemical products accessible directly from glucose. Furthermore, it is argued that 3-deoxyglucosone is a contributing source of some...

  14. Electrically conductive, black thermal control coatings for spacecraft application. I - Silicate matrix formulation

    Science.gov (United States)

    Bauer, J. L.; Odonnell, T. P.; Hribar, V. F.

    1986-01-01

    The formulation of the graphite silicate paints MH-11 and MH-11Z, which will serve as electrically conductive, heat-resistant thermal control coatings for the Galileo spacecraft's 400 Newton engine plume shield, 10 Newton thruster plume shields, and external shunt radiators, is described, and performance results for these paints are reported. The MH-11 is produced by combining a certain grade of graphite powder with a silicate base to produce a black, inorganic, electrically conductive, room temperature cure thermal control paint having high temperature capability. Zinc oxide is added to the MH-11 formulation to produce the blister resistant painta MH-11Z. The mechanical, chemical, thermal, optical, and radiation characteristics of the coatings are reported. The formulation, mixing, application, and surface preparation of the substrates are described, and a method of determining the electrical resistance of the coatings is demonstrated.

  15. Photoluminescent layered Y(III) and Tb(III) silicates doped with Ce(III).

    Science.gov (United States)

    Kostova, Mariya H; Sá Ferreira, Rute A; Ananias, Duarte; Carlos, Luís D; Rocha, João

    2006-08-10

    The synthesis and structural characterization of new layered rare-earth silicates K(3)[M(1-a)Ce(a)Si(3)O(8)(OH)(2)], M = Y(3+), Tb(3+), a silicates, such as intercalation chemistry, and photoluminescence and may find applications in new types of sensor devices. For mixed Tb/Ce-AV-22, evidence has been found for the energy transfer from the large Ce(3+) 4f( 1) --> 5d(1) broad band to the sharp Tb(3+) 4f (8) lines. This energy transfer allows the fine-tuning of the color emission in the blue-green region of the chromaticity diagram. Upon Ce(3+) excitation (342 nm), the radiance of Tb/Ce-AV-22 is approximately 2 times higher than that measured under direct Tb(3+) excitation, which reinforces the existence of effective room-temperature Ce(3+)-to-Tb(3+) energy transfer.

  16. Uranium in the silicate inclusions of stony-iron and iron meteorites

    Energy Technology Data Exchange (ETDEWEB)

    Crozaz, G.; Sibley, S.F.; Tasker, D.R. (Washington Univ., St. Louis, MO (USA). Dept. of Earth and Planetary Sciences; Washington Univ., St. Louis, MO (USA). McDonnell Center for the Space Sciences)

    1982-05-01

    The microdistribution of U has been studied, using fission track techniques, in eleven mesosiderites, seven pallasites and four iron meteorites with silicate inclusions. When concentrated, U is usually found in phosphates: merrillite and/or chlorapatite. As in stony meteorites, the U concentrations in a given phosphate phase are highly variable from meteorite to meteorite and sometimes also exhibit variations in the same meteorite. Uranium is found to be concentrated in merrillite in all the mesosiderites except Bondoc where none was observed. No U-rich phase was identified in six of the seven pallasites. In the seventh, Marjalahti, there are merrillite grains with concentrations ranging from 0.06 to 0.14 ppm. Where observed, the phosphates from silicate inclusions in the irons appear to have U concentrations similar to the mesosiderites.

  17. Correlations between silicic volcanic rocks of the St Mary's Islands (southwestern India) and eastern Madagascar

    DEFF Research Database (Denmark)

    Melluso, Leone; Sheth, Hetu C.; Mahoney, John J.

    2009-01-01

    The St Mary's, Islands (southwestern India) expose silicic volcanic and sub-volcanic rocks (rhyolites and granophyric dacites) emplaced contemporaneously with the Cretaceous igneous province of Madagascar, roughly 88-90 Ma ago. I he St Mary's Islands rocks have phenocrysts of plagioclase...... and isotopic Compositions very close to those of rhyolites exposed between Vatomandry Ilaka and Mananjary in eastern Madagascar, and are distinctly different from rhyolites front other sectors of the Madagascan province. We therefore postulate that the St Mary's and the Vatomandry-Ilaka Mananjary silicic rock...... outcrops were adjacent before the Late Cretaceous rifting that split Madagascar from India, If so, they provide a valuable tool to check and aid traditional Cretaceous India Madagascar reconstructions based on palaeomagnetism, matching Precambrian geological features, and geometric fitting of continental...

  18. Durability of metakaolin geopolymers with various sodium silicate/sodium hydroxide ratios against seawater exposure

    Science.gov (United States)

    Jaya, Nur Ain; Abdullah, Mohd Mustafa Al Bakri; Li, Long-Yuan; Sandu, Andrei Victor; Hussin, Kamarudin; Ming, Liew Yun

    2017-09-01

    This work presents an investigation of the performance of metakaolin geopolymers exposed to the continuous immersion of seawater. The geopolymers were prepared from metakaolin by activating with a mixture of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solutions and cured at 80°C. The ratios of sodium silicate to sodium hydroxide were varied from 0.20 to 0.32. The result showed that metakaolin geopolymers reduce in strength after immersion in seawater for 28 days. The unexposed samples with highest compressive strength attained greatest strength retention. White deposits were formed on the surface of the geopolymers after the exposure to seawater which was believed due to the depolymerisation process of the geopolymer network. Even so, the metakaolin geopolymers did not substantially change in dimension and remain structurally intact.

  19. Application of 29Si NMR spectroscopy to study of alkaline aqueous and alcoholic tetraoctylammonium (TOA) silicate solutions

    Science.gov (United States)

    Goudarzi, Nasser; Arab Chamjangali, M.; Bagherian, G.

    2010-10-01

    29Si NMR spectroscopy is a powerful tool for studying the silicate species existing in aqueous and non-aqueous solutions. In the present work, 29Si NMR spectroscopy is used to characterize the species present in alkaline alcoholic solutions of silicates. Tetraoctylammonium (TOA) hydroxide is used as a template. The effects of polymerization/depolymerization of silicate anions on alkaline alcoholic solutions are investigated using different alcohols (methanol, 1-propanol, 1,3-propane-diol, and glycerin) by 29Si NMR spectroscopy. The esterification of monomeric silicate, Si(OH) 4, in the presence of different alcohols is also studied. Esterification of Si(OH) 4 depends on the alkyl chain as well as the number of hydroxyl groups present in the alcohol.

  20. Application of mean-field model of polymer melt intercalation in organo-silicates for nanocomposites.

    Science.gov (United States)

    Meneghetti, Paulo; Qutubuddin, Syed

    2005-08-15

    The mean-field, lattice-based model of polymer melt intercalation in organically-modified layered silicates (OLS) originally developed by Vaia and Giannelis was applied for different polymers such as poly(methyl methacrylate) (PMMA), polypropylene (PP), and poly(ethylene oxide) (PEO). The nature of each polymer controls significantly the intercalation of the system. The internal energy change caused by the interaction of polymer, surfactant and clay is the strongest factor in determining the equilibrium structure of the nanocomposite system.

  1. Effects of Calcium Lignosulfonate and Silicic Acid on Ammonium Nitrate Degradation

    Directory of Open Access Journals (Sweden)

    Ahmet Ozan Gezerman

    2014-01-01

    Full Text Available Ammonium nitrate salts are the most commonly used nitrogenous fertilizers in industry. However, storage of ammonium nitrate is problematic, since its initial properties can decline because of environmental factors, leading to large economic losses. In this study, in order to prevent the caking and degradation of ammonium nitrate, an alternative composition with additional calcium lignosulfonate and silicic acid was studied. The resulting fertilizer was analyzed by screening analysis, ion chromatography, and electron microscopy methods.

  2. Enzyme stabilization by glass-derived silicates in glass-exposed aqueous solutions

    Science.gov (United States)

    Ives, J.A.; Moffett, J.R.; Arun, P.; Lam, D.; Todorov, T.I.; Brothers, A.B.; Anick, D.J.; Centeno, J.; Namboodiri, M.A.A.; Jonas, W.B.

    2010-01-01

    Objectives: To analyze the solutes leaching from glass containers into aqueous solutions, and to show that these solutes have enzyme activity stabilizing effects in very dilute solutions. Methods: Enzyme assays with acetylcholine esterase were used to analyze serially succussed and diluted (SSD) solutions prepared in glass and plastic containers. Aqueous SSD preparations starting with various solutes, or water alone, were prepared under several conditions, and tested for their solute content and their ability to affect enzyme stability in dilute solution. Results: We confirm that water acts to dissolve constituents from glass vials, and show that the solutes derived from the glass have effects on enzymes in the resultant solutions. Enzyme assays demonstrated that enzyme stability in purified and deionized water was enhanced in SSD solutions that were prepared in glass containers, but not those prepared in plastic. The increased enzyme stability could be mimicked in a dose-dependent manner by the addition of silicates to the purified, deionized water that enzymes were dissolved in. Elemental analyses of SSD water preparations made in glass vials showed that boron, silicon, and sodium were present at micromolar concentrations. Conclusions: These results show that silicates and other solutes are present at micromolar levels in all glass-exposed solutions, whether pharmaceutical or homeopathic in nature. Even though silicates are known to have biological activity at higher concentrations, the silicate concentrations we measured in homeopathic preparations were too low to account for any purported in vivo efficacy, but could potentially influence in vitro biological assays reporting homeopathic effects. ?? 2009 The Faculty of Homeopathy.

  3. Irradiation of potassium-silicate glass surfaces: XPS and REELS study

    Czech Academy of Sciences Publication Activity Database

    Romanyuk, Olexandr; Jiříček, Petr; Zemek, Josef; Houdková, Jana; Jurek, Karel; Gedeon, O.

    2016-01-01

    Roč. 48, č. 7 (2016), s. 543-546 ISSN 0142-2421. [16th European Conference on Applications of Surface and Interface Analysis (ECASIA). Granada, 28.09.2015-01.10.2015] R&D Projects: GA ČR(CZ) GA15-12580S Institutional support: RVO:68378271 Keywords : electron spectroscopy * potassium silicate glass * x-ray irradiation * electron irradiation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.132, year: 2016

  4. The formation of silver metal nanoparticles by ion implantation in silicate glasses

    Czech Academy of Sciences Publication Activity Database

    Vytykačová, S.; Švecová, B.; Nekvindová, P.; Špirková, J.; Macková, Anna; Mikšová, Romana; Bottger, R.

    2016-01-01

    Roč. 371, MAR (2016), s. 245-255 ISSN 0168-583X. [22nd International conference on Ion Beam Analysis (IBA). Opatija, 14.06.2015-19.06.2015] R&D Projects: GA MŠk(CZ) LM2011019; GA ČR GA15-01602S Institutional support: RVO:61389005 Keywords : silicate glasses * silver nanoparticles * ion implantation Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.109, year: 2016

  5. Chemically modified bitumens with enhanced rheology and adhesion properties to siliceous aggregates

    OpenAIRE

    Cuadri Vega, Antonio Abad; Partal López, Pedro; Ahmad, Naveed; Grenfell, James; Airey, Gordon

    2015-01-01

    Moisture damage is one of the major premature failures that worsens the performance and shortens service life of pavements. This research assesses the effect that two chemical modifiers (thiourea and an isocyanate-functionalized castor oil prepolymer) exerts on the bitumen rheology and on the resistance to potential moisture damage of asphalt mixtures based on siliceous aggregates. Both thiourea and the isocyanate-based prepolymer improve the viscous and viscoelastic behaviours of bitumen at ...

  6. Analysis of the color alteration and radiopacity promoted by bismuth oxide in calcium silicate cement

    Directory of Open Access Journals (Sweden)

    Marina Angelica Marciano

    2013-07-01

    Full Text Available The aim of the study was to determine if the increase in radiopacity provided by bismuth oxide is related to the color alteration of calcium silicate-based cement. Calcium silicate cement (CSC was mixed with 0%, 15%, 20%, 30% and 50% of bismuth oxide (BO, determined by weight. Mineral trioxide aggregate (MTA was the control group. The radiopacity test was performed according to ISO 6876/2001. The color was evaluated using the CIE system. The assessments were performed after 24 hours, 7 and 30 days of setting time, using a spectrophotometer to obtain the ΔE, Δa, Δb and ΔL values. The statistical analyses were performed using the Kruskal-Wallis/Dunn and ANOVA/Tukey tests (p 3 mm equivalent of Al. The MTA group was statistically similar to the CSC / 30% BO group (p > 0.05. In regard to color, the increase of bismuth oxide resulted in a decrease in the ΔE value of the calcium silicate cement. The CSC group presented statistically higher ΔE values than the CSC / 50% BO group (p < 0.05. The comparison between 24 hours and 7 days showed higher ΔE for the MTA group, with statistical differences for the CSC / 15% BO and CSC / 50% BO groups (p < 0.05. After 30 days, CSC showed statistically higher ΔE values than CSC / 30% BO and CSC / 50% BO (p < 0.05. In conclusion, the increase in radiopacity provided by bismuth oxide has no relation to the color alteration of calcium silicate-based cements.

  7. Cytotoxicity and genotoxicity of calcium silicate-based cements on an osteoblast lineage

    Directory of Open Access Journals (Sweden)

    Ana Lívia GOMES-CORNÉLIO

    2016-01-01

    Full Text Available Abstract Several calcium silicate-based biomaterials have been developed in recent years, in addition to Mineral Trioxide Aggregate (MTA. The aim of this study was to evaluate the cytotoxicity, genotoxicity and apoptosis/necrosis in human osteoblast cells (SAOS-2 of pure calcium silicate-based cements (CSC and modified formulations: modified calcium silicate-based cements (CSCM and three resin-based calcium silicate cements (CSCR1 (CSCR 2 (CSCR3. The following tests were performed after 24 hours of cement extract exposure: methyl-thiazolyl tetrazolium (MTT, apoptosis/necrosis assay and comet assay. The negative control (CT- was performed with untreated cells, and the positive control (CT+ used hydrogen peroxide. The data for MTT and apoptosis were submitted to analysis of variance and Bonferroni’s posttest (p < 0.05, and the data for the comet assay analysis, to the Kruskal-Wallis and Dunn tests (p < 0.05. The MTT test showed no significant difference among the materials in 2 mg/mL and 10 mg/mL concentrations. CSCR3 showed lower cell viability at 10 mg/mL. Only CSC showed lower cell viability at 50 mg/mL. CSCR1, CSCR2 and CSCR3 showed a higher percentage of initial apoptosis than the control in the apoptosis test, after 24 hours exposure. The same cements showed no genotoxicity in the concentration of 2 mg/mL, with the comet assay. CSC and CSCR2 were also not genotoxic at 10 mg/mL. All experimental materials showed viability with MTT. CSC and CSCR2 presented a better response to apoptosis and genotoxicity evaluation in the 10 mg/mL concentration, and demonstrated a considerable potential for use as reparative materials.

  8. Lithium isotopes in speleothems: Temperature-controlled variation in silicate weathering during glacial cycles

    Science.gov (United States)

    Pogge von Strandmann, Philip A. E.; Vaks, Anton; Bar-Matthews, Miryam; Ayalon, Avner; Jacob, Ezekiel; Henderson, Gideon M.

    2017-07-01

    Terrestrial chemical weathering of silicate minerals is a fundamental component of the global cycle of carbon and other elements. Past changes in temperature, rainfall, ice cover, sea-level and physical erosion are thought to affect weathering but the relative impact of these controls through time remains poorly constrained. This problem could be addressed if the nature of past weathering could be constrained at individual sites. In this study, we investigate the use of speleothems as local recorders of the silicate weathering proxy, Li isotopes. We analysed δ7 Li and [Li] in speleothems that formed during the past 200 ka in two well-studied Israeli caves (Soreq and Tzavoa), as well as in the overlying soils and rocks. Leaching and mass balance of these soils and rocks show that Li is dominantly sourced from weathering of the overlying aeolian silicate soils. Speleothem δ7 Li values are ubiquitously higher during glacials (∼23‰) than during interglacials (∼10‰), implying more congruent silicate weathering during interglacials (where ;congruent; means a high ratio of primary mineral dissolution to secondary mineral formation). These records provide information on the processes controlling weathering in Israel. Consideration of possible processes causing this change of weathering congruency indicates a primary role for temperature, with higher temperatures causing more congruent weathering (lower δ7Lispeleo). The strong relationship observed between speleothem δ7 Li and climate at these locations suggests that Li isotopes may be a powerful tool with which to understand the local controls on weathering at other sites, and could be used to assess the distribution of weathering changes accompanying climate change, such as that of Pleistocene glacial cycles.

  9. Atypical behaviour of dissolved silicate in the Cochin backwater and Periyar river

    Digital Repository Service at National Institute of Oceanography (India)

    Sankaranarayanan, V.N.; Joseph, T.; Jayalakshmy, K.V.; Balachandran, K.K.

    was fitted and it gave a good fit at 5% level (P 0.05). The expected removal of silicate at salinity range 0-5 and 5-35 x 10/3 given by linear relationship was 28.8 and 51.1% respectively. In 5-20 and 20-30 x 10/3 salinity the expected removal as given...

  10. Hydrothermal stability and catalytic performance of desilicated highly siliceous zeolites ZSM-5

    OpenAIRE

    Tarach, Karolina A.; Martínez-Triguero, Joaquín; Rey Garcia, Fernando; Góra-Marek, Kinga

    2016-01-01

    Highly siliceous zeolites, namely MFI type have attracted the great attention due to their higher hydrothermal stability, higher selectivity to organic compounds, and often better catalytic properties in comparison with Al-rich zeolites. The native zeolite (Si/Al = 164) and its desilicated analogues were deeply characterized with regard to their structural and textural properties by X-ray diffraction, low temperature adsorption of nitrogen and solid-state Al-27 MAS NMR. Their acidic propertie...

  11. Energetic feedback in galaxies: Processing of interstellar silicate grains by cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Bringa, E M; Kucheyev, S O; Loeffler, M J; Baragiola, R A; Tielens, A G W M; Dai, Z R; Graham, G; Bajt, S; Bradley, J P; Dukes, C A; Felter, T E; Torres, D F; van Breugel, W

    2006-05-10

    The formation and evolution of stars and galaxies is a complex process that involves the cooling and collapse of dense interstellar clouds as well as energetic feedback on these clouds. Interstellar dust grains are central to the radiative transfer, thermal balance, and molecular processes in these clouds and can provide an important diagnostic. Hence, the effects of energetic processing of interstellar dust may have significant consequences. r This may be studied in our own Galaxy, where observations have shown that an appreciable fraction of silicates formed in the outflows from red giants and supergiants have a crystalline structure. Yet, the fraction of crystalline silicates in the interstellar medium is very small, pointing towards an efficient crystalline crystalline-to to-amorphous conversion process. Here we report experimental and modeling results that show that relatively ''low'' energy (0.1 - 5.0 GeV) heavy ion cosmic rays can rapidly ({approx}70 Million yrs) amorphize crystalline silicate grains ejected by stars into the interstellar medium. The implications of this are briefly discussed. We also examine the effects of cosmic ray processing of silicates in the solar system and in stellar debris disks. In the latter systems, cosmic ray processing may play a role for grains trapped in resonance with planetary companions. We speculate that energetic processing of interstellar dust is likely to be even more important in s star forming galaxies, which have higher cosmic ray fluxes due to tar their much larger star formation rates and their emerging active black holes with associated jets.

  12. UTILIZATION OF RICE HUSK AS RAW MATERIAL IN SYNTHESIS OF MESOPOROUS SILICATES MCM-41

    Directory of Open Access Journals (Sweden)

    Suyanta Suyanta

    2011-12-01

    Full Text Available The research about synthesis and characterization of MCM-41 from rice husk has been done. Silica (SiO2 was extracted from rice husk by refluxing with 3M hydrochloric solution at 80 °C for 3 h. The acid-leached rice husk was filtered, washed, dried and calcined at 650 °C for 6 h lead the rough powder of rice husk silica with light brown in color. Characterization was carried out by X-ray diffraction (XRD and FTIR spectroscopy method. Rice husk silica was dissolved into the sodium hydroxide solution leading to the solution of sodium silicate, and used as silica source for the synthesis of MCM-41. MCM-41 was synthesized by hydrothermal process to the mixture prepared from 29 g of distilled water, 8.67 g of cetyltrimethyl ammonium bromide (CTMAB, 9.31 g of sodium silicate solution, and amount mL of 1 M H2SO4. Hydrothermal process was carried out at 100 °C in a teflon-lined stainless steel autoclave heated in the oven for 36 h. The solid phase was filtered, then washed with deionised water, and dried in the oven at 100 °C for 2 h. The surfactant CTMAB was removed by calcination at 550 °C for 10 h with heating rate 2 °C/min. The as-synthesized and calcined crystals were characterized by using FTIR spectroscopy, X-ray diffraction and N2 physisorption methods. In order to investigate the effect of silica source, the same procedure was carried out by using pure sodium silicate as silica source. It was concluded that silica extracted from rice husk can be used as raw materials in the synthesis of MCM-41, there is no significant difference in crystallinity and pore properties when was compared to material produced from commercial sodium silicate.

  13. PENGARUH PENAMBAHAN SURFAKTAN SODIUM LIGNOSULFONAT (SLS) DALAM PROSES PENGENDAPAN NANO CALCIUM SILICATE (NCS) DARI GEOTHERMAL BRINE

    OpenAIRE

    Ulya, M Ridho; Perdana, Indra; Mulyono, Panut

    2018-01-01

    Konsentrasi yang tinggi dari kelarutan silika dalam larutan geothermal menyebabkan masalah dalam pengoperasian produksi uap di PLTP Dieng. Mitigasi silika scaling diperlukan untuk mengurangi resiko kegagalan produksi uap. Dalam penelitian ini, asam silika dalam larutan geothermal direaksikan dengan kalsium hidroksida (Ca(OH)2) membentuk n ano calcium silicate (NCS). Tujuan penelitian ini adalah membentuk endapan NCS dari surfaktan SLS dan Ca(OH)2 ke dalam larutan geothermal. Mempelajari perub...

  14. Tomography of silicate dust around M-type AGB stars I. Diagnostics based on dynamical models

    Science.gov (United States)

    Bladh, S.; Paladini, C.; Höfner, S.; Aringer, B.

    2017-09-01

    The heavy mass loss observed in evolved asymptotic giant branch stars is usually attributed to a two-step process: atmospheric levitation by pulsation-induced shock waves, followed by radiative acceleration of newly formed dust grains. Detailed wind models suggest that the outflows of M-type AGB stars may be triggered by photon scattering on Fe-free silicates with grain sizes of about 0.1 - 1 $\\mu$m. Due to the low grain temperature, these Fe-free silicates can condense close to the star, but they do not produce the characteristic mid-IR features that are often observed in M-type AGB stars. However, it is probable that the silicate grains are gradually enriched with Fe as they move away from the star, to a degree where the grain temperature stays below the sublimation temperature, but is high enough to produce emission features. We investigate whether differences in grain temperature in the inner wind region, which are related to changes in the grain composition, can be detected with current interferometric techniques, in order to put constraints on the wind mechanism. To investigate this we use radial structures of the atmosphere and wind of an M-type AGB star, produced with the 1D radiation-hydrodynamical code DARWIN. The spectral energy distribution is found to be a poor indicator of different temperature profiles and therefore is not a good tool for distinguishing different scenarios of changing grain composition. However, spatially resolved interferometric observations have promising potential. They show signatures even for Fe-free silicates (found at 2-3 stellar radii), in contrast to the spectral energy distribution. Observations with baselines that probe spatial scales of about 4 stellar radii and beyond are suitable for tracing changes in grain composition, since this is where effects of Fe enrichment should be found.

  15. Electronic structures and physical properties of Na2O doped silicate glass

    Science.gov (United States)

    Baral, Khagendra; Ching, Wai-Yim

    2017-06-01

    Ab initio molecular dynamics has been applied to construct seven sodium silicate glass models with Na2O concentration ranging from 0 to 50 mol. %. The structures of the simulated (Na2O)x(SiO2)1-x glasses are critically analyzed and validated by comparing with available experimental data. Because the initial seed model is based on a near-perfect continuous random network model for amorphous SiO2 with periodic boundaries, the structures of these silicate glasses are highly reliable. The electronic structure, interatomic bonding, and the mechanical and optical properties of seven models are calculated using the first-principles density functional method. In particular, a single quantum mechanical metric, the total bond order density (TBOD), is used to characterize the internal cohesion of sodium silicate glass. This is a significant step beyond the traditional analysis of glasses based purely on the geometric parameters. The TBOD value is found to decrease with increasing Na content, indicating the destruction of silica network connectivity. The calculated mass density and refractive index increase with x are in good agreement with experiment. The elastic coefficients and bulk mechanical properties exhibit a nonlinear variation in the series and depend greatly on the internal bonding and cohesion of the glass. The calculated Poisson's ratio indicates that the glass becomes more ductile with the addition of Na2O. Our results indicate that sodium silicate glass tends to be unstable for x greater than 0.4 due to the total destruction of the SiO2 network.

  16. Velocity of a freely rising gas bubble in a soda-lime silicate glass melt

    Science.gov (United States)

    Hornyak, E. J.; Weinberg, M. C.

    1984-01-01

    A comparison is conducted between measured velocities for the buoyant rise of single bubbles of varying size and composition, in a soda-lime silicate glass melt, with the steady state velocities predicted by the Stokes and Hadamard-Rybczynski formulas. In all cases, the data are noted to fit the Hadamard-Rybczynski expression for steady state rise speed considerably better than the Stokes formula.

  17. A vaporization model for iron/silicate fractionation in the Mercury protoplanet

    Science.gov (United States)

    Fegley, Bruce, Jr.; Cameron, A. G. W.

    1987-01-01

    A study has been carried out on the vaporization of a totally molten silicate magma of chondritic composition heated into the range 2500-3500 K. The motivation for this was to determine the changes in the composition of the mantle that would occur in the Mercury protoplanet should that body have been subjected to the high-temperature phase in the evolution of the primitive solar nebula, but the results are of more general interest. An empirical model based on ideal mixing of complex components was used to describe the nonideal magma. It is found that vaporization of about 70-80 percent of the original amount of silicate from a chondritic planet is required to produce an iron-rich body with a mean uncompressed density equal to that deduced for Mercury. At this point the silicate is depleted in the alkalis, FeO, and SiO2, and enriched in CaO, MgO, Al2O3, and TiO2 relative to chondritic material.

  18. FORCAST Observations of Galactic Evolved Stars: Measurements of Carbonaceous Dust, Crystalline Silicates, and Fullerenes from SOFIA

    Science.gov (United States)

    Kraemer, Kathleen; Sloan, G. C.; Keller, L. D.; Groenewegen, M. A. T.

    2018-01-01

    We present preliminary results from two projects to observe the mid-infrared spectra of evolved stars in the Milky Way using the FORCAST instrument on SOFIA. In the first project, we observed a set of 31 carbon stars over the course of three cycles (government shutdowns contributed to the delays in the program execution), covering a wavelength range of 5-13.7 μm, which includes prominent dust and gas diagnostics. The sources were selected to sample portions of period and flux phase space which were not covered in existing samples from older telescopes such as the Infrared Space Observatory (ISO) or Infrared Astronomical Satellite (IRAS). In the second project, we searched for fullerene emission (C60) at 18.9 μm in Galactic sources with crystalline silicate emission. Although most evolved stars are either carbon-rich or oxygen- (silicate-) rich, fullerenes, a carbon-rich molecule, have been observed in several oxygen-rich evolved stars whose silicate emission features are crystalline rather than the more usual amorphous types. None of our targets show clear signatures of fullerene emission.Support for this work was provided by NASA through awards SOF 03-0079, SOF 03-0104, and SOF 04-0129 issued by USRA.

  19. Understanding the defect chemistry of alkali metal strontium silicate solid solutions: insights from experiment and theory

    KAUST Repository

    Bayliss, Ryan D.

    2014-09-24

    © the Partner Organisations 2014. Recent reports of remarkably high oxide ion conduction in a new family of strontium silicates have been challenged. It has recently been demonstrated that, in the nominally potassium substituted strontium germanium silicate material, the dominant charge carrier was not the oxygen ion, and furthermore that the material was not single phase (R. D. Bayliss et. al., Energy Environ. Sci., 2014, DOI: 10.1039/c4ee00734d). In this work we re-investigate the sodium-doped strontium silicate material that was reported to exhibit the highest oxide ion conductivity in the solid solution, nominally Sr0.55Na0.45SiO2.775. The results show lower levels of total conductivity than previously reported and sub-micron elemental mapping demonstrates, in a similar manner to that reported for the Sr0.8K0.2Si0.5Ge0.5O2.9 composition, an inhomogeneous chemical distribution correlating with a multiphase material. It is also shown that the conductivity is not related to protonic mobility. A density functional theory computational approach provides a theoretical justification for these new results, related to the high energetic costs associated with oxygen vacancy formation. This journal is

  20. The Effect of Aqueous Alteration and Metamorphism in the Survival of Presolar Silicate Grains in Chondrites

    Science.gov (United States)

    Trigo-Rodriguez, Josep M.; Blum, Jürgen

    2009-09-01

    Relatively small amounts (typically between 2 and 200 ppm) of presolar grains have been preserved in the matrices of chondritic meteorites. The measured abundances of the different types of grains are highly variable from one chondrite to another, but are higher in unequilibrated chondrites that have experienced little or no aqueous alteration and/or metamorphic heating than in processed meteorites. A general overview of the abundances measured in presolar grains (particularly the recently identified presolar silicates) contained in primitive chondrites is presented. Here we will focus on the most primitive chondrite groups, as typically the highest measured abundances of presolar grains occur in primitive chondrites that have experienced little thermal metamorphism. Looking at the most aqueously altered chondrite groups, we find a clear pattern of decreasing abundance of presolar silicate grains with increasing levels of aqueous alteration. We conclude that measured abundances of presolar grains in altered chondrites are strongly biased by their peculiar histories. Scales quantifying the intensity of aqueous alteration and shock metamorphism in chondrites could correlate with the content of presolar silicates. To do this it would be required to infer the degree of destruction or homogenization of presolar grains in the matrices of primitive meteorites. To get an unbiased picture of the relative abundance of presolar grains in the different regions of the protoplanetary disk where first meteorites consolidated, future dedicated studies of primitive meteorites, IDPs, and collected materials from sample-return missions (like e.g. the planned Marco Polo) are urgently required.