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Sample records for chemically-bonded phosphate ceramic

  1. Mercury stabilization in chemically bonded phosphate ceramics

    International Nuclear Information System (INIS)

    Wagh, A. S.; Singh, D.; Jeong, S. Y.

    2000-01-01

    Mercury stabilization and solidification is a significant challenge for conventional stabilization technologies. This is because of the stringent regulatory limits on leaching of its stabilized products. In a conventional cement stabilization process, Hg is converted at high pH to its hydroxide, which is not a very insoluble compound; hence the preferred route for Hg sulfidation to convert it into insoluble cinnabar (HgS). Unfortunately, efficient formation of this compound is pH-dependent. At a high pH, one obtains a more soluble Hg sulfate, in a very low pH range, insufficient immobilization occurs because of the escape of hydrogen sulfide, while efficient formation of HgS occurs only in a moderately acidic region. Thus, the pH range of 4 to 8 is where stabilization with Chemically Bonded Phosphate Ceramics (CBPC) is carried out. This paper discusses the authors experience on bench-scale stabilization of various US Department of Energy (DOE) waste streams containing Hg in the CBPC process. This process was developed to treat DOE's mixed waste streams. It is a room-temperature-setting process based on an acid-base reaction between magnesium oxide and monopotassium phosphate solution that forms a dense ceramic within hours. For Hg stabilization, addition of a small amount ( 2 S or K 2 S is sufficient in the binder composition. Here the Toxicity Characteristic Leaching Procedure (TCLP) results on CBPC waste forms of surrogate waste streams representing secondary Hg containing wastes such as combustion residues and Delphi DETOXtrademark residues are presented. The results show that although the current limit on leaching of Hg is 0.2 mg/L, the results from the CBPC waste forms are at least one order lower than this stringent limit. Encouraged by these results on surrogate wastes, they treated actual low-level Hg-containing mixed waste from their facility at Idaho. TCLP results on this waste are presented here. The efficient stabilization in all these cases is

  2. Vitrified chemically bonded phosphate ceramics for immobilization of radioisotopes

    Science.gov (United States)

    Wagh, Arun S.

    2016-04-05

    A method of immobilizing a radioisotope and vitrified chemically bonded phosphate ceramic (CBPC) articles formed by the method are described. The method comprises combining a radioisotope-containing material, MgO, a source of phosphate, and optionally, a reducing agent, in water at a temperature of less than 100.degree. C. to form a slurry; curing the slurry to form a solid intermediate CBPC article comprising the radioisotope therefrom; comminuting the intermediate CBPC article, mixing the comminuted material with glass frits, and heating the mixture at a temperature in the range of about 900 to about 1500.degree. C. to form a vitrified CBPC article comprising the radioisotope immobilized therein.

  3. Method of waste stabilization with dewatered chemically bonded phosphate ceramics

    Science.gov (United States)

    Wagh, Arun; Maloney, Martin D.

    2010-06-29

    A method of stabilizing a waste in a chemically bonded phosphate ceramic (CBPC). The method consists of preparing a slurry including the waste, water, an oxide binder, and a phosphate binder. The slurry is then allowed to cure to a solid, hydrated CBPC matrix. Next, bound water within the solid, hydrated CBPC matrix is removed. Typically, the bound water is removed by applying heat to the cured CBPC matrix. Preferably, the quantity of heat applied to the cured CBPC matrix is sufficient to drive off water bound within the hydrated CBPC matrix, but not to volatalize other non-water components of the matrix, such as metals and radioactive components. Typically, a temperature range of between 100.degree. C.-200.degree. C. will be sufficient. In another embodiment of the invention wherein the waste and water have been mixed prior to the preparation of the slurry, a select amount of water may be evaporated from the waste and water mixture prior to preparation of the slurry. Another aspect of the invention is a direct anyhydrous CBPC fabrication method wherein water is removed from the slurry by heating and mixing the slurry while allowing the slurry to cure. Additional aspects of the invention are ceramic matrix waste forms prepared by the methods disclosed above.

  4. EVALUATION OF CHEMICALLY BONDED PHOSPHATE CERAMICS FOR MERCURY STABILIZATION OF A MIXED SYNTHETIC WASTE

    Science.gov (United States)

    This experimental study was conducted to evaluate the stabilization and encapsulation technique developed by Argonne National Laboratory, called the Chemically Bonded Phosphate Ceramics technology for Hg- and HgCl2-contaminated synthetic waste materials. Leachability ...

  5. Method for Producing Chemically Bonded Phosphate Ceramics and for Stabilizing Contaminants Encapsulated therein Utilizing Reducing Agents

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Dileep; Wagh, Arun S.; Jeong, Seung-Young

    1999-05-05

    Known phosphate ceramic formulations are improved and the ability to produce iron-based phosphate ceramic systems is enabled by the addition of an oxidizing or reducing step during the acid-base reactions that form the phosphate ceramic products. The additives allow control of the rate of the acid-base reactions and concomitant heat generation. In an alternate embodiment, waste containing metal anions is stabilized in phosphate ceramic products by the addition of a reducing agent to the phosphate ceramic mixture. The reduced metal ions are more stable and/or reactive with the phosphate ions, resulting in the formation of insoluble metal species within the phosphate ceramic matrix, such that the resulting chemically bonded phosphate ceramic product has greater leach resistance.

  6. Stabilization of low-level mixed waste in chemically bonded phosphate ceramics

    International Nuclear Information System (INIS)

    Wagh, A.S.; Singh, D.; Sarkar, A.V.

    1994-06-01

    Mixed waste streams, which contain both chemical and radioactive wastes, are one of the important categories of DOE waste streams needing stabilization for final disposal. Recent studies have shown that chemically bonded phosphate ceramics may have the potential for stabilizing these waste streams, particularly those containing volatiles and pyrophorics. Such waste streams cannot be stabilized by conventional thermal treatment methods such as vitrification. Phosphate ceramics may be fabricated at room temperature into durable, hard and dense materials. For this reason room-temperature-setting phosphate ceramic waste forms are being developed to stabilize these to ''problem waste streams.''

  7. Effect of raw material ratios on the compressive strength of magnesium potassium phosphate chemically bonded ceramics.

    Science.gov (United States)

    Wang, Ai-juan; Yuan, Zhi-long; Zhang, Jiao; Liu, Lin-tao; Li, Jun-ming; Liu, Zheng

    2013-12-01

    The compressive strength of magnesium potassium phosphate chemically bonded ceramics is important in biomedical field. In this work, the compressive strength of magnesium potassium phosphate chemically bonded ceramics was investigated with different liquid-to-solid and MgO-to-KH2PO4 ratios. X-ray diffractometer was applied to characterize its phase composition. The microstructure was imaged using a scanning electron microscope. The results showed that the compressive strength of the chemically bonded ceramics increased with the decrease of liquid-to-solid ratio due to the change of the packing density and the crystallinity of hydrated product. However, with the increase of MgO-to-KH2PO4 weight ratio, its compressive strength increased firstly and then decreased. The low compressive strength in lower MgO-to-KH2PO4 ratio might be explained by the existence of the weak phase KH2PO4. However, the low value of compressive strength with the higher MgO-to-KH2PO4 ratio might be caused by lack of the joined phase in the hydrated product. Besides, it has been found that the microstructures were different in these two cases by the scanning electron microscope. Colloidal structure appeared for the samples with lower liquid-to-solid and higher MgO-to-KH2PO4 ratios possibly because of the existence of amorphous hydrated products. The optimization of both liquid-to-solid and MgO-to-KH2PO4 ratios was important to improve the compressive strength of magnesium potassium phosphate chemically bonded ceramics. © 2013.

  8. Chemically bonded phosphate ceramics : part III : reduction mechanism and its application to iron phosphate ceramics.

    Energy Technology Data Exchange (ETDEWEB)

    Wagh, A. S.; Jeong, S. Y.; Energy Technology

    2003-11-01

    In this, the last of a series of three papers, we discuss a method of forming iron phosphate ceramics by a reduction process. We report the formation of iron oxide ceramics by reducing hematite with iron in a phosphoric acid solution. The reaction results in a rapid-setting ceramic (at room temperature) with a compressive strength of 3700 psi and a density of 1.7 g/cm{sup 3}. Although the exact mineral form of the binder is difficult to determine because it is mostly amorphous and hence is not amenable to X-ray diffraction analyses, this material is expected to consist of iron hydrophosphates. The reduction process is very useful in recycling several industrial wastes that are rich in hematite, including iron mine tailings, red mud (a caustic waste from the alumina industry), and machining swarfs. Formation of ceramics with red mud and swarfs is also discussed.

  9. Chemically bonded phosphate ceramics for low-level mixed waste stabilization

    International Nuclear Information System (INIS)

    Singh, D.; Wagh, A.S.; Cunnane, J.C.; Mayberry, J.L.

    1994-01-01

    Novel chemically bonded phosphate ceramics (CBPCs) are being developed and fabricated for low-temperature stabilization and solidification of mixed waste streams which are amenable to conventional high-temperature stabilization processes due to presence of volatiles such as heavy metal chloride and fluorides and/or pyrophorics in the wastes. Phosphates of Mg, Mg-Na and Zr are being developed as candidate matrix materials. In this paper, we present the fabrication procedures of phosphate waste forms using surrogates compositions of three typical mixed wastes streams -- ash, cement sludges, and salts. The performance of the final waste forms such as compression strength, leachability of the contaminants, durability in aqueous environment were conducted. In addition, parameteric studies have been conducted to establish the optimal waste loading in a particular binder system. Based on the results, we present potential applications in the treatment of various mixed waste streams

  10. Stabilization of hazardous ash waste with newberyite-rich chemically bonded magnesium phosphate ceramic

    International Nuclear Information System (INIS)

    Wagh, A.S.; Singh, D.; Jeong, S.Y.

    1995-11-01

    A novel newberyite-rich magnesium-phosphate ceramic, intended for the stabilization of the US Department of Energy's low-level mixed-waste streams, has been developed by an acid-base reaction between magnesium oxide and a phosphoric acid solution. The reaction slurry, formed at room temperature, sets rapidly and forms a lightweight hard ceramic with low open porosity and a high compression strength of ∼ 6,200 psi. It is a composite of stable mineral phases of newberyite, luenebergite, and residual Mg oxide. Using this matrix, the authors developed superior waste forms for a surrogate ash waste stream. The final waste form is a low-permeability structural-quality ceramic, in which hazardous contaminants are chemically fixed and physically encapsulated. The compression strength of the waste form is an order of magnitude higher than the land disposal requirement, even at high waste loading. The high compression strength is attributed to stronger bonds in the waste form that result from participation of ash waste in the setting reactions. Long-term leaching studies show that the waste form is stable in an aqueous environment. The chemically bonded phosphate ceramic approach in this study may be a simple, inexpensive, and efficient method for fabricating high-performance waste forms either for stabilizing waste streams or for developing value-added construction materials from high-volume benign waste streams

  11. Preparation and photocatalytic activity of chemically-bonded phosphate ceramics containing TiO2

    Science.gov (United States)

    Martins, Monize Aparecida; de Lima, Bruna de Oliveira; Ferreira, Leticia Patrício; Colonetti, Emerson; Feltrin, Jucilene; De Noni, Agenor

    2017-05-01

    Titanium dioxide was incorporated into chemically-bonded phosphate ceramic for use as photocatalytic inorganic coating. The coatings obtained were applied to unglazed ceramic tiles and cured at 350 °C. The surfaces were characterized by photocatalytic activity, determined in aqueous medium, based on the degradation of methylene blue dye. The effects of the percentage of TiO2 and the thickness of the layer on the photocatalytic efficiency were evaluated. The influence of the incorporation of TiO2 on the consolidation of the phosphate matrix coating was investigated using the wear resistance test. The crystalline phases of the coatings obtained were determined by XRD. The microstructure of the surfaces was analyzed by SEM. The thermal curing treatment did not cause a phase transition from anatase to rutile. An increase in the photocatalytic activity of the coating was observed with an increase in the TiO2 content. The dye degradation indices ranged from 14.9 to 44.0%. The photocatalytic efficiency was not correlated with the thickness of the coating layer deposited. The resistance to wear decreased with an increase in the TiO2 content. Comparison with a commercial photocatalytic ceramic coating indicated that there is a range of values for the TiO2 contents which offer potential for photocatalytic applications.

  12. Stabilization of lead-rich low-level mixed waste in chemically bonded phosphate ceramic

    International Nuclear Information System (INIS)

    Jeong, S.-Y.

    1999-01-01

    A chemically bonded magnesium potassium phosphate ceramic has been developed by an acid-base reaction at room temperature, for use in stabilizing U.S. Department of Energy low-level mixed waste streams that include hazardous metals and low-level radioactive elements. Using this ceramic, we solidified, in monolithic waste forms, low-level mixed waste streams containing various levels of PbCl 2 and PbCO 3 . These final waste forms were evaluated for their land disposal suitability. The results showed low open porosity (1.48-4.61 vol.%); hence, low permeability, and higher compression strengths (4310-6734 psi) that were one order of magnitude above that required. The level of lead in the leachate following the Toxicity Characteristic Leaching Procedure test was reduced from 50,000 to <0.1 ppm. Leachability indexes from the long-term leaching test (ANS 16.1 test) were between 11.9 and 13.6. This excellent lead retention is due to its chemical fixation as insoluble lead phosphate and to physical encapsulation by the phosphate matrix

  13. Novel Chemically-Bonded Phosphate Ceramic Borehole Sealants (Ceramicretes) for Arctic Environments

    Energy Technology Data Exchange (ETDEWEB)

    Shirish Patil; Godwin A. Chukwu; Gang Chen; Santanu Khataniar

    2008-12-31

    Novel chemically bonded phosphate ceramic borehole sealant, i.e. Ceramicrete, has many advantages over conventionally used permafrost cement at Alaska North Slope (ANS). However, in normal field practices when Ceramicrete is mixed with water in blenders, it has a chance of being contaminated with leftover Portland cement. In order to identify the effect of Portland cement contamination, recent tests have been conducted at BJ services in Tomball, TX as well as at the University of Alaska Fairbanks with Ceramicrete formulations proposed by the Argonne National Laboratory. The tests conducted at BJ Services with proposed Ceramicrete formulations and Portland cement contamination have shown significant drawbacks which has caused these formulations to be rejected. However, the newly developed Ceramicrete formulation at the University of Alaska Fairbanks has shown positive results with Portland cement contamination as well as without Portland cement contamination for its effective use in oil well cementing operations at ANS.

  14. A Review on the Chemically Bonded Phosphate Ceramics as a Binder of Next Generation

    International Nuclear Information System (INIS)

    Yang, Jae Hwan; Kang, K. H.; Na, S. H.; Lee, J. W.

    2010-12-01

    Phosphate ceramics which is fabricated by means of acid-base reaction is a new material that may be used in many fields. This report introduces the technology of phosphate ceramics, especially the process of magnesium phosphate ceramics fabrication and properties in detail. We expect that researchers and engineers who are seeking to develop the technology of wasteform containing spent fuel waste are referred to this document

  15. Stabilization of contaminated soil and wastewater with chemically bonded phosphate ceramics

    International Nuclear Information System (INIS)

    Wagh, A.S.; Jeong, S.Y.; Singh, D.

    1997-01-01

    At Argonne National Laboratory, we have developed chemically Bonded phosphate ceramic (CBPC) technology to stabilize the U.S. Department of Energy's problem mixed waste streams, for which no other stabilization technology is suitable. In this technology, solid waste is mixed with MgO and reacted with aqueous solutions of phosphoric acid or acid phosphates at room temperature to form a slurry that sets in ∼2 h into a hard and dense ceramic waste form. Initial studies involved stabilizing the surrogate waste streams and then testing the waste forms for leaching of contaminants. After achieving satisfactory performance of the waste forms, we next incorporated actual waste streams at bench scale and produced waste forms that were then tested with the Toxicity Characteristic Leaching Procedure (TCLP). This presentation deals with stabilization of soil contaminated with Cd, Cr, Pb, Ag, Ba, and Hg, and of low-level radioactive wastewater. To enhance the contaminant levels in the soil, we further spiked the soil with additional amounts of Cd, Cr, Pb, and Hg. Both the soil and the wastewater were incorporated in the same waste form by stabilizing them with the CBPC process. The waste forms had a total waste loading of ∼77 wt.% and were dense with an open porosity of 2.7 vol.% and a density of 2.17 g/cm 3 . Compression strength was 4910 psi. The TCLP results showed excellent immobilization of all the RCRA metals, and radioactive contaminant levels were below the detection limit of 0.2 pCi/mL. Long-term leaching studies using the ANS 16.1 procedure showed that the retention of contaminants is excellent and comparable to or better than most of other stabilization processes. These results demonstrate that the CBPC process is a very superior process for treatment of low level mixed wastes; we therefore conclude that the CBPC process is well suited to the treatment of low-level mixed waste streams with high waste loading

  16. Immobilization of fission products in phosphate ceramic waste forms

    International Nuclear Information System (INIS)

    Singh, D.

    1996-01-01

    The goal of this project is to develop and demonstrate the feasibility of a novel low-temperature solidification/stabilization (S/S) technology for immobilizing waste streams containing fission products such as cesium, strontium, and technetium in a chemically bonded phosphate ceramic. This technology can immobilize partitioned tank wastes and decontaminate waste streams containing volatile fission products

  17. Immobilization of fission products in phosphate ceramic waste forms

    International Nuclear Information System (INIS)

    Singh, D.; Wagh, A.

    1997-01-01

    Argonne National Laboratory (ANL) is developing chemically bonded phosphate ceramics (CBPCs) to treat low-level mixed wastes, particularly those containing volatiles and pyrophorics that cannot be treated by conventional thermal processes. This work was begun under ANL''s Laboratory Directed Research and Development funds, followed by further development with support from EM-50''s Mixed Waste Focus Area

  18. Phosphate bonded ceramics as candidate final-waste-form materials

    International Nuclear Information System (INIS)

    Singh, D.; Wagh, A.S.; Cunnane, J.; Sutaria, M.; Kurokawa, S.; Mayberry, J.

    1994-04-01

    Room-temperature setting phosphate-bonded ceramics were studied as candidate materials for stabilization of DOE low-level problem mixed wastes which cannot be treated by other established stabilization techniques. Phosphates of Mg, Mg-Na, Al and Zr were studied to stabilize ash surrogate waste containing RCRA metals as nitrates and RCRA organics. We show that for a typical loading of 35 wt.% of the ash waste, the phosphate ceramics pass the TCLP test. The waste forms have high compression strength exceeding ASTM recommendations for final waste forms. Detailed X-ray diffraction studies and differential thermal analyses of the waste forms show evidence of chemical reaction of the waste with phosphoric acid and the host matrix. The SEM studies show evidence of physical bonding. The excellent performance in the leaching tests is attributed to a chemical solidification and physical as well as chemical bonding of ash wastes in these phosphate ceramics

  19. Erosion of magnesium potassium phosphate ceramic waste forms

    International Nuclear Information System (INIS)

    Goretta, K. C.

    1998-01-01

    Phosphate-based chemically bonded ceramics were formed from magnesium potassium phosphate (MKP) binder and either industrial fly ash or steel slag. The resulting ceramics were subjected to solid-particle erosion by a stream of either angular Al 2 O 3 particles or rounded SiO 2 sand. Particle impact angles were 30 or 90degree and the impact velocity was 50 m/s. Steady-state erosion rates, measured as mass lost from a specimen per mass of impacting particle, were dependent on impact angle and on erodent particle size and shape. Material was lost by a combination of fracture mechanisms. Evolution of H 2 O from the MKP phase appeared to contribute significantly to the material loss

  20. Erosion of magnesium potassium phosphate ceramic waste forms.

    Energy Technology Data Exchange (ETDEWEB)

    Goretta, K. C.

    1998-11-20

    Phosphate-based chemically bonded ceramics were formed from magnesium potassium phosphate (MKP) binder and either industrial fly ash or steel slag. The resulting ceramics were subjected to solid-particle erosion by a stream of either angular Al{sub 2}O{sub 3} particles or rounded SiO{sub 2} sand. Particle impact angles were 30 or 90{degree} and the impact velocity was 50 m/s. Steady-state erosion rates, measured as mass lost from a specimen per mass of impacting particle, were dependent on impact angle and on erodent particle size and shape. Material was lost by a combination of fracture mechanisms. Evolution of H{sub 2}O from the MKP phase appeared to contribute significantly to the material loss.

  1. Processing–structure–property relations of chemically bonded ...

    Indian Academy of Sciences (India)

    Mechanical properties and microstructures of a chemically bonded phosphate ceramic (CBPC) and its composite with 1.0 wt% graphite nanoplatelets (GNPs) reinforcement have been investigated. Microstructure was identified by using optical and scanning electron microscopes, X-ray tomography, and X-ray diffraction.

  2. Leaching behavior of phosphate-bonded ceramic waste forms

    International Nuclear Information System (INIS)

    Singh, D.; Wagh, A.S.; Jeong, S.Y.; Dorf, M.

    1996-04-01

    Over the last few years, Argonne National Laboratory has been developing room-temperature-setting chemically bonded phosphate ceramics for solidifying and stabilizing low-level mixed wastes. This technology is crucial for stabilizing waste streams that contain volatile species and off-gas secondary waste streams generated by high-temperature treatment of such wastes. We have developed a magnesium phosphate ceramic to treat mixed wastes such as ash, salts, and cement sludges. Waste forms of surrogate waste streams were fabricated by acid-base reactions between the mixtures of magnesium oxide powders and the wastes, and phosphoric acid or acid phosphate solutions. Dense and hard ceramic waste forms are produced in this process. The principal advantage of this technology is that the contaminants are immobilized by both chemical stabilization and subsequent microencapsulation of the reaction products. This paper reports the results of durability studies conducted on waste forms made with ash waste streams spiked with hazardous and radioactive surrogates. Standard leaching tests such as ANS 16.1 and TCLP were conducted on the final waste forms. Fates of the contaminants in the final waste forms were established by electron microscopy. In addition, stability of the waste forms in aqueous environments was evaluated with long-term water-immersion tests

  3. Iron Phosphate Glass-ceramics

    Directory of Open Access Journals (Sweden)

    Andrea Moguš-Milanković

    2015-12-01

    Full Text Available The crystallization of 40Fe2O3-60P2O5, 10ZnO-30Fe2O3-60P2O5 and (43.3−xPbO–(13.7+xFe2O3–43P2O5, (0 x < 30, glasses and glass-ceramic have been investigated. The structural evolution of glasses during heat treatment at various temperatures and the tendency for crystallization for series of glasses with modified composition are characterized by a dendrite-like phase separation in the early stage of crystallization. Such a behavior leads to the formation of randomly dispersed agglomerates which contain the anhedrally shaped crystallites embedded in glass matrix. Therefore, regardless of the type of crystallization, controlled or spontaneous, the formation of crystalline phases in these phosphate glasses and glass-ceramics is attributed to the disordered interfaces between crystalline grains and glassy matrix.

  4. Chemical bond fundamental aspects of chemical bonding

    CERN Document Server

    Frenking, Gernot

    2014-01-01

    This is the perfect complement to ""Chemical Bonding - Across the Periodic Table"" by the same editors, who are two of the top scientists working on this topic, each with extensive experience and important connections within the community. The resulting book is a unique overview of the different approaches used for describing a chemical bond, including molecular-orbital based, valence-bond based, ELF, AIM and density-functional based methods. It takes into account the many developments that have taken place in the field over the past few decades due to the rapid advances in quantum chemica

  5. Macroencapsulation of low-level debris waste with the phosphate ceramic process

    International Nuclear Information System (INIS)

    Singh, D.; Wagh, A.S.; Tlustochowicz, M.; Jeong, S.Y.

    1997-03-01

    Across the DOE complex, large quantities of contaminated debris and irradiated lead bricks require disposal. The preferred method for disposing of these wastes is macroencapsulation under U.S. Environmental Protection Agency Alternative Treatment Standards. Chemically bonded phosphate ceramics serve as a novel binder, developed at Argonne National Laboratory, for stabilizing and solidifying various low-level mixed wastes. Extremely strong, dense, and impervious to water intrusion, this material was developed with support from the U.S. Department of Energy's Office of Science and Technology (DOE OST). In this investigation, CBPCs have been used to demonstrate macroencapsulation of various contaminated debris wastes, including cryofractured debris, lead bricks, and lead-lined plastic gloves. This paper describes the processing steps for fabricating the waste forms and the results of various characterizations performed on the waste forms. The conclusion is that simple and low-cost CBPCs are excellent material systems for macroencapsulating debris wastes

  6. Mineralisation of two phosphate ceramics in HBSS: role of albumin.

    Science.gov (United States)

    Marques, P A A P; Serro, A P; Saramago, B J; Fernandes, A C; Magalhães, M C F; Correia, R N

    2003-02-01

    The role of albumin in the mineralisation process of commercial hydroxyapatite (HAp) and synthesised biphasic (HAp-tricalcium phosphate) ceramics in a bufferless simulated inorganic plasma (HBSS) was investigated by conventional in vitro tests and static and dynamic wettability measurements. Albumin was either pre-adsorbed or solubilised in HBSS. It was found that calcium complexation by albumin plays a key role in early mineralisation kinetics, so that mineralisation is favoured when albumin is pre-adsorbed and hindered when it is dissolved in HBSS. In the biphasic ceramic this picture is complicated by the fact that albumin, in solution, seems to promote the dissolution of tricalcium phosphate, and simultaneously compete for calcium with the ceramic. It also appears that albumin has a stabilising effect of octacalcium phosphate present in deposits on commercial HAp. The same effect may be present in the case of the biphasic ceramic, at earlier mineralisation times, when octacalcium phosphate appears as a precursor of HAp. Octacalcium phosphate formation on commercial apatite is accompanied by carbonate substitution in phosphate positions.

  7. Processing–structure–property relations of chemically bonded ...

    Indian Academy of Sciences (India)

    Administrator

    Bend- ing and compression strength of the CBPC was improved by reducing bubbles via preparation in vacuum. Keywords. Chemical bonded ceramics; ceramic-matrix composites; particle-reinforced composites; mechanical properties. 1. Introduction. High temperature manufacturing processes contribute to global warming ...

  8. Phosphate-bonded ceramic–wood composites : R&D project overview and invitation to participate

    Science.gov (United States)

    Theodore L. Laufenberg; Matt Aro

    2004-01-01

    We are developing chemically bonded ceramic phosphate binders for the production of biofiber-based composite materials. These binders promise to have better processing and properties than some current cement and polymer resin binder systems. The ceramic phosphate binders (termed Ceramicrete), if used in place of cement and polymers, will significantly reduce the...

  9. Microporous calcium phosphate ceramics driving osteogenesis through surface architecture.

    Science.gov (United States)

    Zhang, Jingwei; Barbieri, Davide; ten Hoopen, Hetty; de Bruijn, Joost D; van Blitterswijk, Clemens A; Yuan, Huipin

    2015-03-01

    The presence of micropores in calcium phosphate (CaP) ceramics has shown its important role in initiating inductive bone formation in ectopic sites. To investigate how microporous CaP ceramics trigger osteoinduction, we optimized two biphasic CaP ceramics (i.e., BCP-R and BCP-S) to have the same chemical composition, equivalent surface area per volume, comparable protein adsorption, similar ion (i.e., calcium and phosphate) exchange and the same surface mineralization potential, but different surface architecture. In particular, BCP-R had a surface roughness (Ra) of 325.4 ± 58.9 nm while for BCP-S it was 231.6 ± 35.7 nm. Ceramic blocks with crossing or noncrossing channels of 250, 500, 1000, and 2000 µm were implanted in paraspinal muscle of dogs for 12 weeks. The percentage of bone volume in the channels was not affected by the type of pores (i.e., crossing vs. closed) or their size, but it was greatly influenced by the ceramic type (i.e., BCP-R vs. BCP-S). Significantly, more bone was formed in the channels of BCP-R than in those of BCP-S. Since the two CaP ceramics differed only in their surface architecture, the results hereby demonstrate that microporous CaP ceramics may induce ectopic osteogenesis through surface architecture. © 2014 Wiley Periodicals, Inc.

  10. Bond strength of plasma sprayed ceramic coatings on phosphate steels

    Czech Academy of Sciences Publication Activity Database

    Pokorný, P.; Mastný, L.; Sýkora, V.; Pala, Zdeněk; Brožek, Vlastimil

    2015-01-01

    Roč. 54, č. 2 (2015), s. 411-414 ISSN 0543-5846 R&D Projects: GA ČR(CZ) GAP108/12/1872 Institutional support: RVO:61389021 Keywords : phosphating * plasma spraying * ceramic coatings * corrosion * bond strength Subject RIV: CA - Inorganic Chemistry Impact factor: 0.959, year: 2014

  11. Stabilization Using Phosphate Bonded Ceramics. Salt Containing Mixed Waste Treatment. Mixed Waste Focus Area. OST Reference No. 117

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    1999-09-01

    Throughout the Department of Energy (DOE) complex there are large inventories of homogeneous mixed waste solids, such as wastewater treatment residues, fly ashes, and sludges that contain relatively high concentrations (greater than 15% by weight) of salts. The inherent solubility of salts (e.g., nitrates, chlorides, and sulfates) makes traditional treatment of these waste streams difficult, expensive, and challenging. One alternative is low-temperature stabilization by chemically bonded phosphate ceramics (CBPCs). The process involves reacting magnesium oxide with monopotassium phosphate with the salt waste to produce a dense monolith. The ceramic makes a strong environmental barrier, and the metals are converted to insoluble, low-leaching phosphate salts. The process has been tested on a variety of surrogates and actual mixed waste streams, including soils, wastewater, flyashes, and crushed debris. It has also been demonstrated at scales ranging from 5 to 55 gallons. In some applications, the CBPC technology provides higher waste loadings and a more durable salt waste form than the baseline method of cementitious grouting. Waste form test specimens were subjected to a variety of performance tests. Results of waste form performance testing concluded that CBPC forms made with salt wastes meet or exceed both RCRA and recommended Nuclear Regulatory Commission (NRC) low-level waste (LLW) disposal criteria. Application of a polymer coating to the CBPC may decrease the leaching of salt anions, but continued waste form evaluations are needed to fully assess the deteriorating effects of this leaching, if any, over time.

  12. Stabilization Using Phosphate Bonded Ceramics. Salt Containing Mixed Waste Treatment. Mixed Waste Focus Area. OST Reference No. 117

    International Nuclear Information System (INIS)

    1999-01-01

    Throughout the Department of Energy (DOE) complex there are large inventories of homogeneous mixed waste solids, such as wastewater treatment residues, fly ashes, and sludges that contain relatively high concentrations (greater than 15% by weight) of salts. The inherent solubility of salts (e.g., nitrates, chlorides, and sulfates) makes traditional treatment of these waste streams difficult, expensive, and challenging. One alternative is low-temperature stabilization by chemically bonded phosphate ceramics (CBPCs). The process involves reacting magnesium oxide with monopotassium phosphate with the salt waste to produce a dense monolith. The ceramic makes a strong environmental barrier, and the metals are converted to insoluble, low-leaching phosphate salts. The process has been tested on a variety of surrogates and actual mixed waste streams, including soils, wastewater, flyashes, and crushed debris. It has also been demonstrated at scales ranging from 5 to 55 gallons. In some applications, the CBPC technology provides higher waste loadings and a more durable salt waste form than the baseline method of cementitious grouting. Waste form test specimens were subjected to a variety of performance tests. Results of waste form performance testing concluded that CBPC forms made with salt wastes meet or exceed both RCRA and recommended Nuclear Regulatory Commission (NRC) low-level waste (LLW) disposal criteria. Application of a polymer coating to the CBPC may decrease the leaching of salt anions, but continued waste form evaluations are needed to fully assess the deteriorating effects of this leaching, if any, over time.

  13. Formation of calcium phosphate layer on ceramics with different reactivities

    International Nuclear Information System (INIS)

    Ribeiro, C.; Rigo, E.C.S.; Sepulveda, P.; Bressiani, J.C.; Bressiani, A.H.A.

    2004-01-01

    Biphasic ceramic samples of different biological reactivity are prepared by using hydroxyapatite (HAp) and tricalcium phosphate (TCP) in various ratios. Different parameters for sintering in an air atmosphere furnace were defined after dilatometric studies. An increased densification with decreased TCP content was observed. The sintered bodies were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The dissolution kinetics and in vitro reactivity were investigated using simulated body fluid (SBF) at 37 deg. C for a maximum period of 3 weeks. The surfaces of the ceramics were analyzed by Fourier transform infrared spectroscopy (FTIR) and SEM in order to observe the formation of a calcium phosphate layer, which indicates the samples bioactivity. Dissolution in SBF demonstrated that layers with different kinetics on the samples surface were formed during the immersion period. The biphasic ceramics show bioactive behavior, even if the resorbable TCP is incorporated

  14. Calcium phosphate ceramics in drug delivery

    Science.gov (United States)

    Bose, Susmita; Tarafder, Solaiman; Edgington, Joe; Bandyopadhyay, Amit

    2011-04-01

    Calcium phosphate (CaP) particulates, cements and scaffolds have attracted significant interest as drug delivery vehicles. CaP systems, including both hydroxyapaptite and tricalcium phosphates, possess variable stoichiometry, functionality and dissolution properties which make them suitable for cellular delivery. Their chemical similarity to bone and thus biocompatibility, as well as variable surface charge density contribute to their controlled release properties. Among specific research areas, nanoparticle size, morphology, surface area due to porosity, and chemistry controlled release kinetics are the most active. This article discusses CaP systems in their particulate, cements, and scaffold forms for drug, protein, and growth factor delivery toward orthopedic and dental applications.

  15. Aluminum phosphate ceramics for waste storage

    Science.gov (United States)

    Wagh, Arun; Maloney, Martin D

    2014-06-03

    The present disclosure describes solid waste forms and methods of processing waste. In one particular implementation, the invention provides a method of processing waste that may be particularly suitable for processing hazardous waste. In this method, a waste component is combined with an aluminum oxide and an acidic phosphate component in a slurry. A molar ratio of aluminum to phosphorus in the slurry is greater than one. Water in the slurry may be evaporated while mixing the slurry at a temperature of about 140-200.degree. C. The mixed slurry may be allowed to cure into a solid waste form. This solid waste form includes an anhydrous aluminum phosphate with at least a residual portion of the waste component bound therein.

  16. EFFECTIVE CHEMICALLY BONDED BUILDING MATERIALS

    Directory of Open Access Journals (Sweden)

    Сергей Николаевич Золотухин

    2017-11-01

    Full Text Available Physical and physical-and-chemical preconditions for creation of the production technology of chemically bonded building materials and products based on phosphogypsum are presented. The methodology and production technology of chemically bonded lime-and-sandy phosphogypsum material (LSPM with the use of modern computerized differential scanning calorimetry are developed and offered. The structure of LSPM is examined. The conceptions of making building composites on the basis of dispersed materials are proved and updated. It was found out that at the definite thickness of water film on the surface of disperse materials, in the thermodynamically unstable state, in the presence of external fields, heightened temperatures and definite pH, cheap water-resistant chemically bonded building composites on the basis of dispersed materials can be made. The results of the LSPM studies showed that such material is effective for forming of low- and middle-quality wall small-piece blocks, partition slabs and bulkheads.

  17. Characterisation and development of fine porosity in magnesium potassium phosphate ceramics

    Czech Academy of Sciences Publication Activity Database

    Viani, Alberto; Radulescu, A.; Pérez-Estébanez, Marta

    2015-01-01

    Roč. 161, December (2015), s. 628-630 ISSN 0167-577X R&D Projects: GA MŠk(CZ) LO1219 Keywords : amorphous materials * chemically-bonded ceramics * microstructure * Rietveld-RIR method * small-angle neutron scattering * specific surface area Subject RIV: AL - Art, Architecture, Cultural Heritage Impact factor: 2.437, year: 2015 https://juser.fz-juelich.de/record/255737

  18. The material and biological characteristics of osteoinductive calcium phosphate ceramics

    Science.gov (United States)

    Tang, Zhurong; Li, Xiangfeng; Tan, Yanfei

    2018-01-01

    Abstract The discovery of osteoinductivity of calcium phosphate (Ca-P) ceramics has set an enduring paradigm of conferring biological regenerative activity to materials with carefully designed structural characteristics. The unique phase composition and porous structural features of osteoinductive Ca-P ceramics allow it to interact with signaling molecules and extracellular matrices in the host system, creating a local environment conducive to new bone formation. Mounting evidence now indicate that the osteoinductive activity of Ca-P ceramics is linked to their physicochemical and three-dimensional structural properties. Inspired by this conceptual breakthrough, many laboratories have shown that other materials can be also enticed to join the rank of tissue-inducing biomaterials, and besides the bones, other tissues such as cartilage, nerves and blood vessels were also regenerated with the assistance of biomaterials. Here, we give a brief historical recount about the discovery of the osteoinductivity of Ca-P ceramics, summarize the underlying material factors and biological characteristics, and discuss the mechanism of osteoinduction concerning protein adsorption, and the interaction with different types of cells, and the involvement of the vascular and immune systems. PMID:29423267

  19. Low-temperature setting phosphate ceramics for stabilization of DOE problem low level mixed-waste: I. Material and waste form development

    International Nuclear Information System (INIS)

    Singh, D.; Wagh, A.; Knox, L.; Mayberry, J.

    1994-03-01

    Chemically bonded phosphate ceramics are proposed as candidates for solidification and stabilization of some of the open-quotes problemclose quotes DOE low-level mixed wastes at low-temperatures. Development of these materials is crucial for stabilization of waste streams which have volatile species and any use of high-temperature technology leads to generation of off-gas secondary waste streams. Several phosphates of Mg, Al, and Zr have been investigated as candidate materials. Monoliths of these phosphates were synthesized using chemical routes at room or slightly elevated temperatures. Detailed physical and chemical characterizations have been conducted on some of these phosphates to establish their durability. Magnesium ammonium phosphate has shown to possess excellent mechanical and as well chemical properties. These phosphates were also used to stabilize a surrogate ash waste with a loading ranging from 25-35 wt.%. Characterization of the final waste forms show that waste immobilization is due to both chemical stabilization and physical encapsulation of the surrogate waste which is desirable for waste immobilization

  20. Dimension of surface microstructure as an osteogenic factor in calcium phosphate ceramics

    NARCIS (Netherlands)

    Zhang, Jingwei; Luo, Xiaoman; Barbieri, D.; Barradas, A.M.C.; de Bruijn, Joost Dick; van Blitterswijk, Clemens; Yuan, Huipin

    2014-01-01

    Microporosity of calcium phosphate (CaP) ceramics has shown its essential role in osteoinduction by CaP ceramics after ectopic implantation. Here we show that not the microporosity but the dimension of surface microstructural features is likely the osteogenic factor. Two tricalcium phosphate

  1. Chemical bonding in carbonitride nanolayers

    Science.gov (United States)

    Hoffmann, P.; Baake, O.; Beckhoff, B.; Ensinger, W.; Fainer, N.; Klein, A.; Kosinova, M.; Pollakowski, B.; Trunova, V.; Ulm, G.; Weser, J.

    2007-05-01

    First results are presented for the identification of chemical bonds and structures (speciation) in boron and silicon carbonitrides, produced as layers of some hundred nm. The boron carbonitride (BC xN y) films are synthesized by low-pressure chemical vapor deposition (LPCVD) using the precursor substance trimethylamine borane. The samples of silicon carbonitride (SiC xN y) films are synthesized by plasma-enhanced chemical vapor deposition (PECVD) using hexamethyl disilazane. The measurements were performed by total reflection X-ray fluorescence analysis combined with near-edge X-ray absorption fine structure investigations (TXRF-NEXAFS) and by X-ray photo-electron spectroscopy (XPS). The results are compared with those obtained for standard samples boron carbide (B 4C), boron nitride (e.g., h-BN, c-BN), silicon carbide (SiC), and silicon nitride (Si 3N 4).

  2. Effect of nanostructure on osteoinduction of porous biphasic calcium phosphate ceramics.

    Science.gov (United States)

    Li, Bo; Liao, Xiaoling; Zheng, Li; Zhu, Xiangdong; Wang, Zhe; Fan, Hongsong; Zhang, Xingdong

    2012-10-01

    In order to evaluate the effect of the nanostructure of calcium phosphate ceramics on osteoinductive potential, porous biphasic calcium phosphate (BCP) ceramics with a nano- or submicron structure were prepared via microwave sintering and compared to conventional BCP ceramics. The selective protein adsorption of bovine serum albumin and lysozyme (LSZ) and the osteogenic differentiation of human mesenchymal stem cells in vitro was investigated. Porous BCP nanoceramics showed higher ability to adsorb proteins, especially low molecular weight protein of LSZ, than conventional BCP ceramics, and the BCP nanoceramics promoted bone sialoprotein expression more than conventional BCP did. Further in vivo study to investigate ectopic bone formation and bone repair efficiency proved the highly osteoinductive potential of nanostructured BCP ceramics. The results suggest that nanostructured BCP ceramics have the potential to become a new generation of bioceramics for bone tissue engineering grafts. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  3. Investigation of amorphous and crystalline phosphates in magnesium phosphate ceramics with solid-state H-1 and P-31 NMR spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Viani, Alberto; Mali, G.; Mácová, Petra

    2017-01-01

    Roč. 43, č. 8 (2017), s. 6571-6579 ISSN 0272-8842 R&D Projects: GA MŠk(CZ) LO1219 Keywords : sol-gel processes * spectroscopy * MgO * chemically-bonded ceramics Subject RIV: JJ - Other Materials OBOR OECD: Materials engineering Impact factor: 2.986, year: 2016 http://www.sciencedirect.com/science/article/pii/S027288421730278X

  4. Investigation of the setting reaction in magnesium phosphate ceramics with quasielastic neutron scattering

    Czech Academy of Sciences Publication Activity Database

    Viani, Alberto; Zbiri, M.; Bordallo, H. N.; Gualtieri, A. F.; Mácová, Petra

    2017-01-01

    Roč. 121, č. 21 (2017), s. 11355-11367 ISSN 1932-7447 R&D Projects: GA MŠk(CZ) LO1219 Keywords : magnesium potassium phosphate ceramics * amorphous materials * NMR-spectroscopy Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass OBOR OECD: Ceramics Impact factor: 4.536, year: 2016 http://pubs.acs.org/doi/abs/10.1021/acs.jpcc.7b01396

  5. Enhanced Luminescent Properties in Tm3+/Dy3+ Co-doped Transparent Phosphate Glass Ceramic

    OpenAIRE

    Yao L. Q.; Chen G. H.; Zhong H. J.; Cui S. C.; Li F.; Gan J.Y.

    2016-01-01

    Novel Tm3+/Dy3+ co-doped phosphate glass and glass ceramic samples for white light emitting diodes were prepared by melt quenching method. Under 353 nm excitation, the colors of the luminescence of the glass and glass ceramic samples are white. The CIE chromaticity coordinates (0.338, 0.328) of the emission from the glass ceramic is close to the standard white-light illumination (0.333, 0.333). Compared to the glass, the fluorescence intensity in the glass ceramic is greatly enhanced.

  6. Evolution of microstructure and performance in magnesium potassium phosphate ceramics: role of sintering temperature of MgO powder

    Czech Academy of Sciences Publication Activity Database

    Viani, Alberto; Sotiriadis, Konstantinos; Šašek, Petr; Appavou, M.-S.

    2016-01-01

    Roč. 42, č. 14 (2016), s. 16310-16316 ISSN 0272-8842 R&D Projects: GA MŠk(CZ) LO1219 Keywords : chemically-bonded ceramics * X-ray diffraction (XRD) * small angle neutron scattering (SANS) * microstructure * amorphous materials Subject RIV: JN - Civil Engineering Impact factor: 2.986, year: 2016 http://www.sciencedirect.com/science/article/pii/S027288421631255X

  7. Effect of phase composition on protein adsorption and osteoinduction of porous calcium phosphate ceramics in mice.

    Science.gov (United States)

    Wang, Jing; Chen, Ying; Zhu, Xiangdong; Yuan, Tun; Tan, Yanfei; Fan, Yujiang; Zhang, Xingdong

    2014-12-01

    The purpose of this study was to investigate the effect of phase compositions of porous calcium phosphate (CaP) ceramics on their protein adsorption behaviors in vitro and osteoinductive potentials in vivo in mice. Under competitive conditions, a high adsorption of bone morphogenetic protein 2 (BMP-2) was observed at a high initial concentration of BMP-2 in the multi-protein solution on all the four types of ceramics, indicating their strong affinity for BMP-2. No significant difference in BMP-2 adsorption between the ceramics was noted, indicating that phase composition could have little influence on BMP-2 adsorption. After implantation into the thigh muscles of mice for 45 and 90 days, the histological and histomorphometric analyses showed that porous biphasic calcium phosphate (BCP) ceramic consisting of 30% hydroxyapatite HA and 70% tricalcium phosphate (β-TCP), i.e. BCP-2 had stronger osteoinductive ability than the other three groups of ceramics. The immunohistochemical staining showed the highest expression of BMP-2 and osteocalcin (OCN) in BCP-2 group. Osteoinduction of porous CaP ceramics might be influenced by the amount of BMP-2 present in the local microenvironment in the implant, which was regulated by the phase composition of the ceramics. BCP-2 promoted the highest expression of BMP-2 and then showed the strongest osteoinduction in mice. © 2014 Wiley Periodicals, Inc.

  8. Investigation of setting reaction in magnesium potassium phosphate ceramics with time resolved infrared spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Mácová, Petra; Viani, Alberto

    2017-01-01

    Roč. 205, October (2017), s. 62-66 ISSN 0167-577X R&D Projects: GA MŠk(CZ) LO1219 Keywords : amorphous materials * magnesium potassium phosphate cements * FTIR Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass OBOR OECD: Ceramics Impact factor: 2.572, year: 2016 http://www.sciencedirect.com/science/article/pii/S0167577X17309552

  9. Polymer-Ceramic Composite Scaffolds: The Effect of Hydroxyapatite and β-tri-Calcium Phosphate

    OpenAIRE

    Boyang Huang; Guilherme Caetano; Cian Vyas; Jonny James Blaker; Carl Diver; Paulo Bártolo

    2018-01-01

    The design of bioactive scaffolds with improved mechanical and biological properties is an important topic of research. This paper investigates the use of polymer-ceramic composite scaffolds for bone tissue engineering. Different ceramic materials (hydroxyapatite (HA) and β-tri-calcium phosphate (TCP)) were mixed with poly-ε-caprolactone (PCL). Scaffolds with different material compositions were produced using an extrusion-based additive manufacturing system. The produced scaffolds were physi...

  10. ATR-FTIR measurements of albumin and fibrinogen adsorption: Inert versus calcium phosphate ceramics.

    Science.gov (United States)

    Boix, Marcel; Eslava, Salvador; Costa Machado, Gil; Gosselin, Emmanuel; Ni, Na; Saiz, Eduardo; De Coninck, Joël

    2015-11-01

    Arthritis, bone fracture, bone tumors and other musculoskeletal diseases affect millions of people across the world. Nowadays, inert and bioactive ceramics are used as bone substitutes or for bone regeneration. Their bioactivity is very much dictated by the way proteins adsorb on their surface. In this work, we compared the adsorption of albumin and fibrinogen on inert and calcium phosphates ceramics (CaPs) using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to follow in situ protein adsorption on these materials. To this effect, we developed a sol-gel technique to control the surface chemistry of an ATR-FTIR detector. Hydroxyapatite adsorbed more albumin and β-tricalcium phosphate adsorbed more fibrinogen. Biphasic calcium phosphate presented the lowest adsorption among CaP for both proteins, illustrating the effect of surface heterogeneities. Inert ceramics adsorbed a lower amount of both proteins compared with bioactive ceramics. A significant change was observed in the conformation of the adsorbed protein versus the surface chemistry. Hydroxyapatite produced a larger loss of α-helix structure on albumin and biphasic calcium phosphate reduced β-sheet percentage on fibrinogen. Inert ceramics produced large α-helix loss on albumin and presented weak interaction with fibrinogen. Zirconia did not adsorb albumin and titanium dioxide promoted huge denaturalization of fibrinogen. © 2015 Wiley Periodicals, Inc.

  11. Magnesium-phosphate-glass cements with ceramic-type properties

    Science.gov (United States)

    Sugama, T.; Kukacka, L.E.

    1982-09-23

    Rapid setting magnesium phosphate (Mg glass) cementitious materials consisting of magnesium phosphate cement paste, polyborax and water-saturated aggregate, exhibits rapid setting and high early strength characteristics. The magnesium glass cement is prepared from a cation-leachable powder and a bivalent metallic ion-accepting liquid such as an aqueous solution of diammonium phosphate and ammonium polyphosphate. The cation-leachable powder includes a mixture of two different magnesium oxide powders processed and sized differently which when mixed with the bivalent metallic ion-accepting liquid provides the magnesium glass cement consisting primarily of magnesium ortho phosphate tetrahydrate, with magnesium hydroxide and magnesium ammonium phosphate hexahydrate also present. The polyborax serves as a set-retarder. The resulting magnesium mono- and polyphosphate cements are particularly suitable for use as a cementing matrix in rapid repair systems for deteriorated concrete structures as well as construction materials and surface coatings for fireproof structures.

  12. Magnesium phosphate glass cements with ceramic-type properties

    Science.gov (United States)

    Sugama, Toshifumi; Kukacka, Lawrence E.

    1984-03-13

    Rapid setting magnesium phosphate (Mg glass) cementitious materials consisting of magnesium phosphate cement paste, polyborax and water-saturated aggregate exhibiting rapid setting and high early strength characteristics. The magnesium glass cement is prepared from a cation-leachable powder and a bivalent metallic ion-accepting liquid such as an aqueous solution of diammonium phosphate and ammonium polyphosphate. The cation-leachable powder includes a mixture of two different magnesium oxide powders processed and sized differently which when mixed with the bivalent metallic ion-accepting liquid provides the magnesium glass cement consisting primarily of magnesium ortho phosphate tetrahydrate, with magnesium hydroxide and magnesium ammonium phosphate hexahydrate also present. The polyborax serves as a set-retarder. The resulting magnesium mono- and polyphosphate cements are particularly suitable for use as a cementing matrix in rapid repair systems for deteriorated concrete structures as well as construction materials and surface coatings for fireproof structures.

  13. Bond strength of plasma sprayed ceramic coatings on the phosphated steels

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2015-04-01

    Full Text Available In the presented work, results of adhesion measurements for different systems of steel sheet-phosphate interlayer-ceramiccoating are described. The interlayers were produced by zinc phosphating; alumina, olivine and zirconiasilica-alumina (e.g. eucor coatings were deposited by water stabilized plasma torch WSP®. However, successful application of the WSP technique depends on the choice of correct deposition parameters preserving the hydrated phosphates from thermal destruction by the molten ceramic particles. For the adhesion measurement ISO 4624standardized test was used. Corrosion resistivity was measured by polarisation resistance and free corrosion potential in 3 % NaCl solution.

  14. Mg-phosphate ceramics produced from the product of thermal transformation of cement-asbestos

    Czech Academy of Sciences Publication Activity Database

    Pérez-Estébanez, Marta; Mácová, Petra; Šašek, Petr; Viani, Alberto; Gualtieri, A.

    2014-01-01

    Roč. 34, č. 2 (2014), s. 187-192 ISSN 1640-4920. [Conference on Environment and Mineral Processing /18./. Ostrava, 29.05.2014-31.05.2014] R&D Projects: GA MŠk(CZ) LO1219 Keywords : cement-asbestos * magnesium phosphate ceramics * amorphous Subject RIV: AL - Art, Architecture, Cultural Heritage http://www.potopk.com.pl/archiwum.html

  15. Controlling surface microstructure of calcium phosphate ceramic from random to custom-design

    NARCIS (Netherlands)

    Wang, Liao; Luo, Xiaoman; Barbieri, D.; Bao, Chongyun; Yuan, Huipin

    2014-01-01

    Calcium phosphate ceramics have long been studied as bone graft substitutes due to their similarity with the mineral constitute of bone and teeth, excellent biocompatibility and bioactivity. Chemical composition, macrostructure and surface microstructure are believed to be important for the bone

  16. Formation and growth of manganese phosphate passivation layers for NTC ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Hsiang, H.-I, E-mail: hsingi@mail.ncku.edu.t [Particulate Materials Research Center, Department of Resources Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Mei, L.-T.; Lin, Y.-H. [Particulate Materials Research Center, Department of Resources Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

    2009-09-18

    This study examines the effect of additives in manganese phosphating (MPO) solution on the formation of phosphate coating and the formation and growth mechanism of phosphates on NTC ceramics using X-ray diffractometry (XRD), scanning electron microscopy (SEM), and electron probe microanalyzer (EPMA). The results showed that addition of Zn{sup 2+} in MPO solutions can make the coating coverage more complete compared to Fe{sup 3+}. In addition, manganese phosphate precipitation initiated near the grain boundary of Ni-rich region, is generated due to the preferential etching of Mn compared to Ni and Co. The passivation layer formed with manganese phosphate coating has good acid resistance and can act as a passivation layer for NTC during electroplating.

  17. Production of porous Calcium Phosphate (CaP) ceramics with aligned pores using ceramic/camphene-based co-extrusion.

    Science.gov (United States)

    Choi, Won-Young; Kim, Hyoun-Ee; Moon, Young-Wook; Shin, Kwan-Ha; Koh, Young-Hag

    2015-01-01

    Calcium phosphate (CaP) ceramics are one of the most valuable biomaterials for uses as the bone scaffold owing to their outstanding biocompatability, bioactivity, and biodegradation nature. In particular, these materials with an open porous structure can stimulate bone ingrowth into their 3-dimensionally interconnected pores. However, the creation of pores in bulk materials would inevitably cause a severe reduction in mechanical properties. Thus, it is a challenge to explore new ways of improving the mechanical properties of porous CaP scaffolds without scarifying their high porosity. Porous CaP ceramic scaffolds with aligned pores were successfully produced using ceramic/camphene-based co-extrusion. This aligned porous structure allowed for the achievement of high compressive strength when tested parallel to the direction of aligned pores. In addition, the overall porosity and mechanical properties of the aligned porous CaP ceramic scaffolds could be tailored simply by adjusting the initial CaP content in the CaP/camphene slurry. The porous CaP scaffolds showed excellent in vitro biocompatibility, suggesting their potential as the bone scaffold. Aligned porous CaP ceramic scaffolds with considerably enhanced mechanical properties and tailorable porosity would find very useful applications as the bone scaffold.

  18. The chemical bond of stibium. Technological aspects

    Directory of Open Access Journals (Sweden)

    Ashcheulov A. A.

    2011-08-01

    Full Text Available Thin structure of the chemical bond of the hexagonal and rhombohedral modifications of stibium was investigated. The boundaries of their polymorphism were identified, which opens new technological possibilities of creating optical, photoelectric, thermoelectric, and other materials for electronic equipment components.

  19. Graphene composites containing chemically bonded metal oxides

    Indian Academy of Sciences (India)

    (figure 7). We have also been able to bond Al2O3 to graphene by using AlCl3 as the reactant. The oxide film was amor- phous after calcination at 600. ◦. C. We have prepared chemically bonded magnetic Fe3O4 nanoparticles to graphene by functionalizing Fe3O4 by amine, then reacting it with graphene functionalized with.

  20. Graphene composites containing chemically bonded metal oxides

    Indian Academy of Sciences (India)

    Abstract. Composites of graphene involving chemically bonded nano films of metal oxides have been prepared by reacting graphene containing surface oxygen functionalities with metal halide vapours followed by exposure to water vapour. The composites have been characterized by electron microscopy, atomic force ...

  1. Teaching Chemical Bonding through Jigsaw Cooperative Learning

    Science.gov (United States)

    Doymus, Kemal

    2008-01-01

    This study examined the effectiveness of jigsaw cooperative learning in teaching chemical bonding at tertiary level. This study was carried out in two different classes in the Department of Primary Science Education of Ataturk University during the 2005-2006 academic year. One of the classes was the non-jigsaw group (control) and the other was the…

  2. Graphene composites containing chemically bonded metal oxides

    Indian Academy of Sciences (India)

    Composites of graphene involving chemically bonded nano films of metal oxides have been prepared by reacting graphene containing surface oxygen functionalities with metal halide vapours followed by exposure to water vapour. The composites have been characterized by electron microscopy, atomic force microscopy ...

  3. Optimization of calcium phosphate fine ceramic powders preparation

    Science.gov (United States)

    Sezanova, K.; Tepavitcharova, S.; Rabadjieva, D.; Gergulova, R.; Ilieva, R.

    2013-12-01

    The effect of biomimetic synthesis method, reaction medium and further precursor treatments on the chemical and phase composition, crystal size and morphology of calcium phosphates was examined. Nanosized calcium phosphate precursors were biomimetically precipitated by the method of continuous precipitation in three types of reaction media at pH 8: (i) SBF as an inorganic electrolyte system; (ii) organic (glycerine) modified SBF (volume ratio of 1:1); (iii) polymer (10 g/l xanthan gum or 10 g/l guar gum) modified SBF (volume ratio of 1:1). After maturation (24 h) the samples were lyophilized, calcinated at 300°C for 3 hours, and washed with water, followed by new gelation, lyophilization and step-wise (200, 400, 600, 800, and 1000°C, each for 3 hours) sintering. The reaction medium influenced the chemical composition and particle size but not the morphology of the calcium phosphate powders. In all studied cases bi-phase calcium phosphate fine powders with well-shaped spherical grains, consisting of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) with a Ca/P ratio of 1.3 - 1.6 were obtained. The SBF modifiers decreased the particle size of the product in the sequence guar gum ˜ xanthan gum < glycerin < SBF medium.

  4. Grafting cyclodextrins to calcium phosphate ceramics for biomedical applications

    DEFF Research Database (Denmark)

    Jacobsen, P.A.L.; Nielsen, J.L.; Juhl, M.V.

    2012-01-01

    The grafting of hydroxyapatite/beta-tricalcium phosphate with β-cyclodextrin was achieved using a two step reaction with (3-glycidyloxypropyl)trimethoxysilane as a linker. Firstly, the silane group was brought to react with the hydroxyl groups at the surface of the hydroxyapatite/beta-tricalcium ...

  5. Bone morphogenetic protein Smads signaling in mesenchymal stem cells affected by osteoinductive calcium phosphate ceramics.

    Science.gov (United States)

    Tang, Zhurong; Wang, Zhe; Qing, Fangzhu; Ni, Yilu; Fan, Yujiang; Tan, Yanfei; Zhang, Xingdong

    2015-03-01

    Porous calcium phosphate ceramics (CaP ceramics) could induce ectopic bone formation which was regulated by various signal molecules. In this work, bone marrow mesenchymal stem cells (MSCs) were cultured on the surface of osteoinductive hydroxyapatite (HA) and biphasic calcium phosphate (BCP) ceramics in comparison with control (culture plate) for up to 14 days to detect the signal molecules which might be affected by the CaP ceramics. Without adding osteogenic factors, MSCs cultured on HA and BCP both expressed higher Runx2, Osterix, collagen type I, osteopontin, bone sialoprotein, and osteocalcin at various stages compared with control, thus confirmed the osteoblastic differentiation of MSCs. Later study demonstrated the messenger RNA level of bone morphogenetic protein 2 (BMP2) and BMP4 were also significantly enhanced by HA and BCP. Furthermore, Smad1, 4, 5, and Dlx5, the main molecules in the BMP/Smads signaling pathway, were upregulated by HA and BCP. Moreover, the higher expression of Smads and BMP2, 4 in BCP over HA, corresponded to the better performance of BCP in stimulating in vitro osteoblastic differentiation of MSCs. This was in accordance with the better osteoinductivity of BCP over HA in vivo. Altogether, these results implied that the CaP ceramics may initiate the osteoblastic differentiation of MSCs by influencing the expression of molecules in BMP/Smads pathway. © 2014 Wiley Periodicals, Inc.

  6. Visualizing Chemical Bonds in Synthetic Molecules

    Science.gov (United States)

    Collins, Laura C.; Ruth, Anthony; Green, David B.; Janko, Boldizsar; Gomes, Kenjiro K.

    The use of synthetic quantum systems makes it possible to study phenomena that cannot be probed by conventional experiments. We created synthetic molecules using atomic manipulation and directly imaged the chemical bonds using tunneling spectroscopy. These synthetic systems allow us to probe the structure and electronic properties of chemical bonds in molecules, including those that would be unstable in nature, with unprecedented detail. The experimental images of electronic states in our synthetic molecules show a remarkable match to the charge distribution predicted by density functional theory calculations. The statistical analysis of the spectroscopy of these molecules can be adapted in the future to quantify aromaticity, which has been difficult to quantify universally thus far due to vague definitions. We can also study anti-aromatic molecules which are unstable naturally, to illuminate the electronic consequences of antiaromaticity.

  7. Comparative study on in vivo response of porous calcium carbonate composite ceramic and biphasic calcium phosphate ceramic

    Energy Technology Data Exchange (ETDEWEB)

    He, Fupo, E-mail: fphebm@126.com [School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Ren, Weiwei [School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Tian, Xiumei [Department of Biomedical Engineering, School of Basic Sciences, Guangzhou Medical University, Guangzhou 510182 (China); Liu, Wei; Wu, Shanghua [School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Chen, Xiaoming, E-mail: xmchenw@126.com [Department of Biomedical Engineering, School of Basic Sciences, Guangzhou Medical University, Guangzhou 510182 (China)

    2016-07-01

    In a previous study, robust calcium carbonate composite ceramics (CC/PG) were prepared by using phosphate-based glass (PG) as an additive, which showed good cell response. In the present study the in vivo response of porous CC/PG was compared to that of porous biphasic calcium phosphate ceramics (BCP), using a rabbit femoral critical-size grafting model. The materials degradation and bone formation processes were evaluated by general observation, X-ray radiography, micro-computed tomography, and histological examination. The results demonstrated excellent biocompatibility and osteoconductivity, and progressive degradation of CC/PG and BCP. Although the in vitro degradation rate of CC/PG was distinctly faster than that of BCP, at 4 week post-implantation, the bone generation and material degradation of CC/PG were less than those of BCP. Nevertheless, at postoperative week 8, the increment of bone formation and material degradation of CC/PG was pronouncedly larger than that of BCP. These results show that CC/PG is a potential resorbable bone graft aside from the traditional synthetic ones. - Highlights: • A calcium carbonate composite ceramic (CC/PG) was acquired. • The in vivo response of CC/PG and biphasic calcium phosphate (BCP) was compared. • CC/PG showed faster in vitro degradation rate compared to BCP. • CC/PG showed less in vivo degradation and bone formation than BCP at week 4. • CC/PG had larger increment of degradation and bone formation than BCP at week 8.

  8. [Clinical study of nanometer calcium phosphate ceramic artificial bone].

    Science.gov (United States)

    Sun, Yong; Xiao, Jian-De; Xiong, Jian-Yi; Liu, Jian-Quan

    2009-11-01

    To study the clinical effects and security of nanometer ceramics artificial bone transplantation to treat the bone defect. From March 2005 to November 2007, 32 patients (artificial bone group) with extremity bone defects applied nanometer ceramics artificial bone transplantations, included 19 males and 13 females, aged from 17 to 63 years old (averaged 31.4 years). The other 36 patients (internal fixation group) with extremity bone defects were treated by the internal fixation in the same period, included 21 males and 15 females, aged from 16 to 65 years old (averaged 32.6 years). Ca, P, B-ALP, IgG, IgA, IgM, CIC, C3, SL-2R and CD4+/CD8+ in the peripheral venous blood were measured in the 1st and 2th week and 1st, 3rd, 6th month after operation. All patients were followed up and the limb function was evaluated according to Enneking standard. The wounds of all patients smoothly healed after operation. Every immunological indicators had no significant difference between two groups. Serum calcium and phosphorus content did not significantly increased. Serum B-ALP of all patients were increased after operation, fell to normal levels in the internal fixation group, but remained at a relatively high level in the artificial bone group. All patients were followed-up for from 9 to 24 months (averaged 15 months). All patients get the excellent physical function. The artificial bone has no immunogenicity, no rejection,does not affect the blood calcium and phosphorus content, and has higher osteogenic activity. It is affirmed that nanometer ceramics artificial bone is used to treat the smaller bone defect on clinical.

  9. Thai students' mental model of chemical bonding

    Science.gov (United States)

    Sarawan, Supawadee; Yuenyong, Chokchai

    2018-01-01

    This Research was finding the viewing about concept of chemical bonding is fundamental to subsequent learning of various other topics related to this concept in chemistry. Any conceptions about atomic structures that students have will be shown their further learning. The purpose of this study is to interviews conceptions held by high school chemistry students about metallic bonding and to reveal mental model of atomic structures show according to the educational level. With this aim, the questionnaire prepared making use of the literature and administered for analysis about mental model of chemical bonding. It was determined from the analysis of answers of questionnaire the 10th grade, 11th grade and 12th grade students. Finally, each was shown prompts in the form of focus cards derived from curriculum material that showed ways in which the bonding in specific metallic substances had been depicted. Students' responses revealed that learners across all three levels prefer simple, realistic mental models for metallic bonding and reveal to chemical bonding.

  10. Polymer-Ceramic Composite Scaffolds: The Effect of Hydroxyapatite and β-tri-Calcium Phosphate.

    Science.gov (United States)

    Huang, Boyang; Caetano, Guilherme; Vyas, Cian; Blaker, Jonny James; Diver, Carl; Bártolo, Paulo

    2018-01-14

    The design of bioactive scaffolds with improved mechanical and biological properties is an important topic of research. This paper investigates the use of polymer-ceramic composite scaffolds for bone tissue engineering. Different ceramic materials (hydroxyapatite (HA) and β-tri-calcium phosphate (TCP)) were mixed with poly-ε-caprolactone (PCL). Scaffolds with different material compositions were produced using an extrusion-based additive manufacturing system. The produced scaffolds were physically and chemically assessed, considering mechanical, wettability, scanning electron microscopy and thermal gravimetric tests. Cell viability, attachment and proliferation tests were performed using human adipose derived stem cells (hADSCs). Results show that scaffolds containing HA present better biological properties and TCP scaffolds present improved mechanical properties. It was also possible to observe that the addition of ceramic particles had no effect on the wettability of the scaffolds.

  11. Polymer-Ceramic Composite Scaffolds: The Effect of Hydroxyapatite and β-tri-Calcium Phosphate

    Directory of Open Access Journals (Sweden)

    Boyang Huang

    2018-01-01

    Full Text Available The design of bioactive scaffolds with improved mechanical and biological properties is an important topic of research. This paper investigates the use of polymer-ceramic composite scaffolds for bone tissue engineering. Different ceramic materials (hydroxyapatite (HA and β-tri-calcium phosphate (TCP were mixed with poly-ε-caprolactone (PCL. Scaffolds with different material compositions were produced using an extrusion-based additive manufacturing system. The produced scaffolds were physically and chemically assessed, considering mechanical, wettability, scanning electron microscopy and thermal gravimetric tests. Cell viability, attachment and proliferation tests were performed using human adipose derived stem cells (hADSCs. Results show that scaffolds containing HA present better biological properties and TCP scaffolds present improved mechanical properties. It was also possible to observe that the addition of ceramic particles had no effect on the wettability of the scaffolds.

  12. Effect of particle size on osteoinductive potential of microstructured biphasic calcium phosphate ceramic.

    Science.gov (United States)

    Wang, Liao; Barbieri, Davide; Zhou, Hongyu; de Bruijn, Joost D; Bao, Chongyun; Yuan, Huipin

    2015-06-01

    Material factors such as chemistry, surface microstructure and geometry have shown their influence on osteoinduction of calcium phosphate ceramics. Hereby we report that osteoinduction of a micro-structured biphasic calcium phosphate ceramic (BCP) has a relation with the particle sizes. BCP particles with the size of 212-300 µm, 106-212 µm, 45-106 µm, and smaller than 45 µm were prepared and implanted in paraspinal muscle of dogs for 12 weeks. Histological evaluation of the explants showed abundant bone in all samples with particle size of 212-300 µm, 106-212 µm, and 45-106 µm, while no bone was seen in any sample having particle size smaller than 45 µm. Bone was formed as early as 3 weeks after implantation in implants having BCP particles bigger than 45 µm and the volume of the formed bone was similar among the implants with particles larger than 45 µm after 12 weeks implantation. The results herein show that a size limitation of microstructured calcium phosphate ceramic particles for osteoinduction. It is most likely that the particle size affect inductive bone formation via macroporous structures for body fluid infiltration, cell/tissue ingrowth and angiogenesis. © 2014 Wiley Periodicals, Inc.

  13. X-ray diffraction and chemical bonding

    International Nuclear Information System (INIS)

    Bats, J.W.

    1976-01-01

    Chemical bonds are investigated in sulfamic acid (H 3 N-SO 3 ), sodium sulfonlate dihydrate (H 2 NC 6 H 4 SO 3 Na.2H 2 O), 2,5-dimercaptothiadiazole (HS-C 2 N 2 S-SH), sodium cyanide dihydrate (NaCN.2H 2 O), sodium thiocyanate (NaSCN) and ammonium thiocyanate (NH 4 SCN) by X-ray diffraction, and if necessary completed with neutron diffraction. Crystal structures and electron densities are determined together with bond length and angles. Also the effects of thermal motion are discussed

  14. Quantum mechanical facets of chemical bonds

    International Nuclear Information System (INIS)

    Daudel, R.

    1976-01-01

    To define the concept of bond is both a central problem of quantum chemistry and a difficult one. The concept of bond appeared little by little in the mind of chemists from empirical observations. From the wave-mechanical viewpoint it is not an observable. Therefore there is no precise operator associated with that concept. As a consequence there is not a unique approach to the idea of chemical bond. This is why it is preferred to present various quantum mechanical facets, e.g. the energetic facet, the density facet, the partitioning facet and the functional facet, of that important concept. (Auth.)

  15. In Vitro Investigation of Bioactive Glass-Ceramic Composites Based on Biogenic Hydroxyapatite or Synthetic Calcium Phosphates

    OpenAIRE

    Pinchuk, Nataliia; Parkhomey, Oleksandr; Sych, Olena

    2017-01-01

    This in vitro investigation of the behavior of two types of calcium phosphate glass ceramics on the basis of phosphates of biogenic or synthetic origin prepared from initial mixtures with different particle size has revealed that some different factors affect the behavior, namely the phase composition of composite, fraction of open porosity, and average diameter of pore channels. It was established that the solubility of the composites on the basis of synthetic calcium phosphates and glass af...

  16. Synthesis and characterization of tricalcium phosphate ceramics doped with zinc

    International Nuclear Information System (INIS)

    Kai, K.C.; Marchi, J.; Ussui, V.; Bressiani, A.H.A.

    2011-01-01

    Due to its biocompatibility, the tricalcium phosphate (TCP) is used as a biomaterial for bone replacement and reconstruction. Zinc (Zn) can replace calcium in the crystal structure of TCP to be added in small quantities, can result in stimulatory effects on bone formation in vitro and in vivo. In this work, pure TCP and Zn-TCP, with general formula (Ca 1-x Zn x ) 3 (PO 4 ) 2 and 0 ≤ x ≤ 0.0225, were prepared by wet synthesis, from precursors Ca(OH) 2 , H 3 PO 4 and ZnO, after calcinated at 800 deg C and characterized by X-ray diffraction, specific surface area, agglomerate size distribution, differential thermal analysis and scanning electron microscopy. The results showed that the addition of small amounts of Zn resulted in TCP with suitable densification and higher specific surface area, may be promising as biomaterial due to the stimulatory effects of zinc associated with suitable mechanical properties of the final material. (author)

  17. Cell response of calcium phosphate based ceramics, a bone substitute material

    Directory of Open Access Journals (Sweden)

    Juliana Marchi

    2013-01-01

    Full Text Available The aim of this study was to characterize calcium phosphate ceramics with different Ca/P ratios and evaluate cell response of these materials for use as a bone substitute. Bioceramics consisting of mixtures of hydroxyapatite (HAp and β-tricalcium phosphate (β-TCP powders in different proportions were pressed and sintered. The physical and chemical properties of these bioceramics were then characterized. Characterization of the biological properties of these materials was based on analysis of cell response using cultured fibroblasts. The number of cells attached to the samples was counted from SEM images of samples exposed to cell culture solution for different periods. These data were compared by analysis of variance (ANOVA complemented by the Tukey's test. The TCP sample had higher surface roughness and lower density. The adherence and growth of FMM1 cells on samples from all groups was studied. Even though the different calcium based ceramics exhibited properties which made them suitable as bone substitutes, those with higher levels of β-TCP revealed improved cell growth on their surfaces. These observations indicated two-phase calcium phosphate based materials with a β-TCP surface layer to be a promising bone substitute.

  18. Surface degradation of glass ceramics after exposure to acidulated phosphate fluoride

    Science.gov (United States)

    CCAHUANA, Vanessa Zulema S.; ÖZCAN, Mutlu; MESQUITA, Alfredo Mikail Melo; NISHIOKA, Renato Sussumo; KIMPARA, Estevão Tomomitsu; BOTTINO, Marco Antonio

    2010-01-01

    Objective This study evaluated the surface degradation effect of acidulated phosphate fluoride (APF) gel exposure on the glassy matrix ceramics as a function of time. Material and methods Disc-shaped ceramic specimens (N = 120, 10/per ceramic material) were prepared in stainless steel molds (inner diameter: 5 mm, height: 2 mm) using 6 dental ceramics: 3 indicated for ceramic-fused-to-metal (Vita Omega 900, Carmen and Vita Titankeramik), 2 for all-ceramic (Vitadur Alpha and Finesse® Low Fusing) and 1 for both types of restorations (IPS d.SIGN). The specimens were wet ground finished, ultrasonically cleaned and auto-glazed. All specimens were subjected to calculation of percentage of mass loss, surface roughness analysis and topographical description by scanning electron microscopy (SEM) before (0 min) and after exposure to 1.23 % APF gel for 4 min and 60 min representing short- and long-term etching effect, respectively. The data were analyzed using two-way ANOVA with repeated measures and Tukey`s test (α=0.05). Results Significant effect of the type of the ceramics (p=0.0000, p=0.0031) and exposure time (p=0.0000) was observed in both surface roughness and percentage of mass loss values, respectively. The interaction factor between both parameters was also significant for both parameters (p=0.0904, p=0.0258). Both 4 min (0.44±0.1 - 0.81±0.2 µm) and 60 min (0.66±0.1 - 1.04±0.3 µm) APF gel exposure created significantly more surface roughness for all groups when compared to the control groups (0.33±0.2 - 0.68±0.2 µm) (p0.05) but at 60 min exposure, IPS d.SIGN showed the highest percentage of mass loss (0.1151±0.11). The mean surface roughness for Vita Titankeramik (0.84±0.2 µm) and Finesse® Low Fusing (0.74.±0.2 µm) was significantly higher than those of the other ceramics (0.59±0.1 µm - 0.49±0.1 µm) and Vita Titankeramik (p<0.05) regardless of the exposure time. A positive correlation was found between surface roughness and percentage of mass

  19. Topography of calcium phosphate ceramics regulates primary cilia length and TGF receptor recruitment associated with osteogenesis.

    Science.gov (United States)

    Zhang, Jingwei; Dalbay, Melis T; Luo, Xiaoman; Vrij, Erik; Barbieri, Davide; Moroni, Lorenzo; de Bruijn, Joost D; van Blitterswijk, Clemens A; Chapple, J Paul; Knight, Martin M; Yuan, Huipin

    2017-07-15

    The surface topography of synthetic biomaterials is known to play a role in material-driven osteogenesis. Recent studies show that TGFβ signalling also initiates osteogenic differentiation. TGFβ signalling requires the recruitment of TGFβ receptors (TGFβR) to the primary cilia. In this study, we hypothesize that the surface topography of calcium phosphate ceramics regulates stem cell morphology, primary cilia structure and TGFβR recruitment to the cilium associated with osteogenic differentiation. We developed a 2D system using two types of tricalcium phosphate (TCP) ceramic discs with identical chemistry. One sample had a surface topography at micron-scale (TCP-B, with a bigger surface structure dimension) whilst the other had a surface topography at submicron scale (TCP-S, with a smaller surface structure dimension). In the absence of osteogenic differentiation factors, human bone marrow stromal cells (hBMSCs) were more spread on TCP-S than on TCP-B with alterations in actin organization and increased primary cilia prevalence and length. The cilia elongation on TCP-S was similar to that observed on glass in the presence of osteogenic media and was followed by recruitment of transforming growth factor-β RII (p-TGFβ RII) to the cilia axoneme. This was associated with enhanced osteogenic differentiation of hBMSCs on TCP-S, as shown by alkaline phosphatase activity and gene expression for key osteogenic markers in the absence of additional osteogenic growth factors. Similarly, in vivo after a 12-week intramuscular implantation in dogs, TCP-S induced bone formation while TCP-B did not. It is most likely that the surface topography of calcium phosphate ceramics regulates primary cilia length and ciliary recruitment of p-TGFβ RII associated with osteogenesis and bone formation. This bioengineering control of osteogenesis via primary cilia modulation may represent a new type of biomaterial-based ciliotherapy for orthopedic, dental and maxillofacial surgery

  20. Calcium phosphate/microgel composites for 3D powderbed printing of ceramic materials.

    Science.gov (United States)

    Birkholz, Mandy-Nicole; Agrawal, Garima; Bergmann, Christian; Schröder, Ricarda; Lechner, Sebastian J; Pich, Andrij; Fischer, Horst

    2016-06-01

    Composites of microgels and calcium phosphates are promising as drug delivery systems and basic components for bone substitute implants. In this study, we synthesized novel composite materials consisting of pure β-tricalcium phosphate and stimuli-responsive poly(N-vinylcaprolactam-co-acetoacetoxyethyl methacrylate-co-vinylimidazole) microgels. The chemical composition, thermal properties and morphology for obtained composites were extensively characterized by Fourier transform infrared, X-ray photoelectron spectroscopy, IGAsorp moisture sorption analyzer, thermogravimetric analysis, granulometric analysis, ESEM, energy dispersive X-ray spectroscopy and TEM. Mechanical properties of the composites were evaluated by ball-on-three-balls test to determine the biaxial strength. Furthermore, initial 3D powderbed-based printing tests were conducted with spray-dried composites and diluted 2-propanol as a binder to evaluate a new binding concept for β-tricalcium phosphate-based granulates. The printed ceramic bodies were characterized before and after a sintering step by ESEM. The hypothesis that the microgels act as polymer adhesive agents by efficient chemical interactions with the β-tricalcium phosphate particles was confirmed. The obtained composites can be used for the development of new scaffolds.

  1. Scaffolds with a standardized macro-architecture fabricated from several calcium phosphate ceramics using an indirect rapid prototyping technique

    Science.gov (United States)

    Wilson, C. E.; van Blitterswijk, C. A.; Verbout, A. J.; de Bruijn, J. D.

    2010-01-01

    Calcium phosphate ceramics, commonly applied as bone graft substitutes, are a natural choice of scaffolding material for bone tissue engineering. Evidence shows that the chemical composition, macroporosity and microporosity of these ceramics influences their behavior as bone graft substitutes and bone tissue engineering scaffolds but little has been done to optimize these parameters. One method of optimization is to place focus on a particular parameter by normalizing the influence, as much as possible, of confounding parameters. This is difficult to accomplish with traditional fabrication techniques. In this study we describe a design based rapid prototyping method of manufacturing scaffolds with virtually identical macroporous architectures from different calcium phosphate ceramic compositions. Beta-tricalcium phosphate, hydroxyapatite (at two sintering temperatures) and biphasic calcium phosphate scaffolds were manufactured. The macro- and micro-architectures of the scaffolds were characterized as well as the influence of the manufacturing method on the chemistries of the calcium phosphate compositions. The structural characteristics of the resulting scaffolds were remarkably similar. The manufacturing process had little influence on the composition of the materials except for the consistent but small addition of, or increase in, a beta-tricalcium phosphate phase. Among other applications, scaffolds produced by the method described provide a means of examining the influence of different calcium phosphate compositions while confidently excluding the influence of the macroporous structure of the scaffolds. PMID:21069558

  2. Chemically-bonded brick production based on burned clay by means of semidry pressing

    Science.gov (United States)

    Voroshilov, Ivan; Endzhievskaya, Irina; Vasilovskaya, Nina

    2016-01-01

    We presented a study on the possibility of using the burnt rocks of the Krasnoyarsk Territory for production of chemically-bonded materials in the form of bricks which are so widely used in multistory housing and private house construction. The radiographic analysis of the composition of burnt rock was conducted and a modifier to adjust the composition uniformity was identified. The mixing moisture content was identified and optimal amount at 13-15% was determined. The method of semidry pressing has been chosen. The process of obtaining moldings has been theoretically proved; the advantages of chemically-bonded wall materials compared to ceramic brick were shown. The production of efficient artificial stone based on material burnt rocks, which is comparable with conventionally effective ceramic materials or effective with cell tile was proved, the density of the burned clay-based cell tile makes up to 1630-1785 kg m3, with compressive strength of 13.6-20.0 MPa depending on the compression ratio and cement consumption, frost resistance index is F50, and the thermal conductivity in the masonry is λ = 0,459-0,546 W m * °C. The clear geometric dimensions of pressed products allow the use of the chemically-bonded brick based on burnt clay as a facing brick.

  3. Cells responding to surface structure of calcium phosphate ceramics for bone regeneration.

    Science.gov (United States)

    Zhang, Jingwei; Sun, Lanying; Luo, Xiaoman; Barbieri, Davide; de Bruijn, Joost D; van Blitterswijk, Clemens A; Moroni, Lorenzo; Yuan, Huipin

    2017-11-01

    Surface structure largely affects the inductive bone-forming potential of calcium phosphate (CaP) ceramics in ectopic sites and bone regeneration in critical-sized bone defects. Surface-dependent osteogenic differentiation of bone marrow stromal cells (BMSCs) partially explained the improved bone-forming ability of submicron surface structured CaP ceramics. In this study, we investigated the possible influence of surface structure on different bone-related cells, which may potentially participate in the process of improved bone formation in CaP ceramics. Besides BMSCs, the response of human brain vascular pericytes (HBVP), C2C12 (osteogenic inducible cells), MC3T3-E1 (osteogenic precursors), SV-HFO (pre-osteoblasts), MG63 (osteoblasts) and SAOS-2 (mature osteoblasts) to the surface structure was evaluated in terms of cell proliferation, osteogenic differentiation and gene expression. The cells were cultured on tricalcium phosphate (TCP) ceramics with either micron-scaled surface structure (TCP-B) or submicron-scaled surface structure (TCP-S) for up to 14 days, followed by DNA, alkaline phosphatase (ALP) and quantitative polymerase chain reaction gene assays. HBVP were not sensitive to surface structure with respect to cell proliferation and osteogenic differentiation, but had downregulated angiogenesis-related gene expression (i.e. vascular endothelial growth factor) on TCP-S. Without additional osteogenic inducing factors, submicron-scaled surface structure enhanced ALP activity and osteocalcin gene expression of human (h)BMSCs and C2C12 cells, favoured the proliferation of MC3T3-E1, MG63 and SAOS-2, and increased ALP activity of MC3T3-E1 and SV-HFO. The results herein indicate that cells with osteogenic potency (either osteogenic inducible cells or osteogenic cells) could be sensitive to surface structure and responded to osteoinductive submicron-structured CaP ceramics in cell proliferation, ALP production or osteogenic gene expression, which favour bone

  4. Calcium phosphate ceramics as bone graft substitutes in filling bone tumor defects

    Directory of Open Access Journals (Sweden)

    Saikia K

    2008-01-01

    Full Text Available Background: Synthetic bio-inert materials are currently used as an alternative to autogenous bone graft. Calcium hydroxyapatite (HA and Beta tri-calcium phosphate (β-TCP, which belong to the calcium phosphate ceramics group, are biocompatible and osteo-conductive. The purpose of this study is to analyse the use of HA and β-TCP in their ceramic forms as a bone graft substitute in filling bone voids after curettage of benign bone tumors. Materials and Methods: Twenty-four patients in the age range of 3.5-55 years (mean 14.3 years having benign bone tumors with bone defects were filled with bone graft substitute following curettage. In 20 patients bone defects were filled with block/granules of HA ceramic and in four with β-TCP. Fibular strut graft was packed with HA in four patients. The patients were followed up for an average of 18 months (range 12-36 months. Results: The functional status of the patients at follow-up was evaluated and compared with preoperative functional status. Early incorporation of graft substitutes became evident radiologically between 6 and 10 weeks (Stage I. Complete incorporation (Stage III was observed in an average of nine months (6-18 months. Clinical healing was observed before radiological healing. The average time taken to return to preoperative function was 14 weeks. There was no recurrence of lesion or growth retardation. Conclusion: Calcium hydroxyapatite and β-TCP are excellent bone graft substitutes for autogenous bone graft in filling voids after curettage of benign bone tumors.

  5. [Histologic and biomechanic evaluation of posterolateral arthrodesis using a biphasic ceramic of calcium phosphate as bone substitute. Experimental study with sheep].

    Science.gov (United States)

    Guigui, P; Hardouin, P

    2000-01-01

    The effectiveness of a macroporous biphasic calcium phosphate ceramic was studied after laterovertebral arthrodesis in sheep. A ceramic with a TCP/HAP ratio of 35/65 was compared with autologous bone graft in an histomorphometric and biomechanical point of view. Quantitative analysis of the results indicated that the biphasic ceramic allows an arthrodesis after 12 months, although control graft is effective after six months. A large decrease of flexibility in all directions was obtained with the ceramic, similarly to autologous graft. No nonfusion case was observed. In conditions very close to the human surgery, a posterolateral fusion can be obtained using biphasic phosphate ceramic as bone substitute.

  6. Direct tomography with chemical-bond contrast.

    Science.gov (United States)

    Huotari, Simo; Pylkkänen, Tuomas; Verbeni, Roberto; Monaco, Giulio; Hämäläinen, Keijo

    2011-05-29

    Three-dimensional (3D) X-ray imaging methods have advanced tremendously during recent years. Traditional tomography uses absorption as the contrast mechanism, but for many purposes its sensitivity is limited. The introduction of diffraction, small-angle scattering, refraction, and phase contrasts has increased the sensitivity, especially in materials composed of light elements (for example, carbon and oxygen). X-ray spectroscopy, in principle, offers information on element composition and chemical environment. However, its application in 3D imaging over macroscopic length scales has not been possible for light elements. Here we introduce a new hard-X-ray spectroscopic tomography with a unique sensitivity to light elements. In this method, dark-field section images are obtained directly without any reconstruction algorithms. We apply the method to acquire the 3D structure and map the chemical bonding in selected samples relevant to materials science. The novel aspects make this technique a powerful new imaging tool, with an inherent access to the molecular-level chemical environment. © 2011 Macmillan Publishers Limited. All rights reserved

  7. Upper Secondary Teachers' Knowledge for Teaching Chemical Bonding Models

    Science.gov (United States)

    Bergqvist, Anna; Drechsler, Michal; Chang Rundgren, Shu-Nu

    2016-01-01

    Researchers have shown a growing interest in science teachers' professional knowledge in recent decades. The article focuses on how chemistry teachers impart chemical bonding, one of the most important topics covered in upper secondary school chemistry courses. Chemical bonding is primarily taught using models, which are key for understanding…

  8. Emphasizing the Significance of Electrostatic Interactions in Chemical Bonding

    Science.gov (United States)

    Venkataraman, Bhawani

    2017-01-01

    This paper describes a pedagogical approach to help students understand chemical bonding by emphasizing the importance of electrostatic interactions between atoms. The approach draws on prior studies that have indicated many misconceptions among students in understanding the nature of the chemical bond and energetics associated with bond formation…

  9. Teaching and Learning the Concept of Chemical Bonding

    Science.gov (United States)

    Levy Nahum, Tami; Mamlok-Naaman, Rachel; Hofstein, Avi; Taber, Keith S.

    2010-01-01

    Chemical bonding is one of the key and basic concepts in chemistry. The learning of many of the concepts taught in chemistry, in both secondary schools as well as in the colleges, is dependent upon understanding fundamental ideas related to chemical bonding. Nevertheless, the concept is perceived by teachers, as well as by learners, as difficult,…

  10. Effect of nano-hydroxyapatite coating on the osteoinductivity of porous biphasic calcium phosphate ceramics

    Science.gov (United States)

    2014-01-01

    Background Porous biphasic calcium phosphate (BCP) ceramics exhibit good biocompatibility and bone conduction but are not inherently osteoinductive. To overcome this disadvantage, we coated conventional porous BCP ceramics with nano-hydroxyapatite (nHA). nHA was chosen as a coating material due to its high osteoinductive potential. Methods We used a hydrothermal deposition method to coat conventional porous BCP ceramics with nHA and assessed the effects of the coating on the physical and mechanical properties of the underlying BCP. Next, its effects on mesenchymal stem cell (MSC) attachment, proliferation, viability, and osteogenic differentiation were investigated. Results nHA formed a deposited layer on the BCP surface, and synthesized nHA had a rod-like shape with lengths ranging from ~50–200 nm and diameters from ~15–30 mm. The nHA coating did not significantly affect the density, porosity, flexural strength, or compressive strength of the underlying BCP (P > 0.1). Scanning electron microscopy showed MSC attachment to the scaffolds, with a healthy morphology and anchorage to nHA crystals via cytoplasmic processes. The densities of MSCs attached on BCP and nHA-coated BCP scaffolds were 62 ± 26 cells/mm2 and 63 ± 27 cells/mm2 (P > 0.1), respectively, after 1 day and 415 ± 62 cells/mm2 and 541 ± 35 cells/mm2 (P ceramics, making this material more suitable for applications in bone tissue engineering. PMID:24690170

  11. Enhanced effect of β-tricalcium phosphate phase on neovascularization of porous calcium phosphate ceramics: in vitro and in vivo evidence.

    Science.gov (United States)

    Chen, Y; Wang, J; Zhu, X D; Tang, Z R; Yang, X; Tan, Y F; Fan, Y J; Zhang, X D

    2015-01-01

    Neovascularization plays a key role in bone repair and regeneration. In the present study, four types of porous calcium phosphate (CaP) ceramics, namely hydroxyapatite (HA), biphasic calcium phosphates (BCP-1 and BCP-2) and β-tricalcium phosphate (β-TCP), with HA to β-TCP ratios of 100/0, 70/30, 30/70 and 2/98, respectively, were investigated in terms of their angiogenic induction. The in vitro cell culture revealed that the ceramics could promote proliferation and angiogenesis of human umbilical vein endothelial cells (HUVECs). This result could be achieved by stimulating CCD-18Co human fibroblasts to secrete angiogenic factors (vascular endothelial growth factor, basic fibroblast growth factor and transforming growth factor-β) as a paracrine effect, as well as by up-regulating HUVECs to express these angiogenic factors and their receptors (KDR, FGFR1 and ACVRL1) and the downstream eNOS as an autocrine effect. These effects were more significant in β-TCP and BCP-2, which had a higher content of β-TCP phase. In the in vivo implantation into the thigh muscles of mice, the process of neovascularization of the ceramics was initiated at 2 weeks and the mature vascular networks were formed at 4 weeks as visualized by hematoxylin and eosin staining and scanning electron microscopy. Microvessel density count confirmed that β-TCP and BCP-2 induced more microvessels to form than HA or BCP-1. This phenomenon was further confirmed by the significantly up-regulated expressions of angiogenesis-related genes in the ingrowth of cells into the inner pores of the two ceramics. All the results confirmed the angiogenic induction of porous CaP ceramics, and a higher content of β-TCP phase had an enhanced effect on the neovascularization of the ceramics. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  12. Osteoinduction of Calcium Phosphate Ceramics in Four Kinds of Animals for 1 Year: Dog, Rabbit, Rat, and Mouse.

    Science.gov (United States)

    Cheng, L; Wang, T; Zhu, J; Cai, P

    2016-05-01

    Bone grafts are in great demand. Synthetic materials have been extensively studied as substitutes for autografts. Calcium phosphate ceramics are promising synthetic bone replacement materials. Because they share chemical similarities with human bone mineral, they show excellent biocompatibility and osteoinductivity. Calcium phosphate ceramics have been used to fill bone defects in preclinical study in a variety of animals. This study aimed to investigate the osteogenesis ability of calcium phosphate ceramics in 4 kinds of animals. Φ3 × 5 mm hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) cylinders were implanted into the dorsal muscle of rats and mice, whereas Φ5 × 10 mm cylinders were implanted into the dorsal muscle of dogs and rabbits. One year after implantation, the ceramics were harvested to perform hematoxylin and eosin (HE) staining and Masson-trichrome staining. The new bone tissues were observed and the area percentage of new bone was compared in the 4 kinds of animals. A large number of new bone and bone marrow tissues were observed in dogs, rabbits, and mice, but not in rats; and the area percentage of new bone in mice was significantly higher than that in dogs and rabbits (P  dog > rabbit > rat. To achieve better effects for bone transplantation, mouse should be chosen as the preferred experimental model based on these advantages: economic, convenience, and osteogenesis ability. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Inflammatory response and bone healing capacity of two porous calcium phosphate ceramics in critical size cortical bone defects.

    Science.gov (United States)

    Chatterjea, Anindita; van der Stok, Johan; Danoux, Charlène B; Yuan, Huipin; Habibovic, Pamela; van Blitterswijk, Clemens A; Weinans, Harrie; de Boer, Jan

    2014-05-01

    In the present study, two open porous calcium phosphate ceramics, β-tricalcium phosphate (β-TCP), and hydroxyapatite (HA) were compared in a critical-sized femoral defect in rats. Previous comparisons of these two ceramics showed significantly greater osteoinductive potential of β-TCP upon intramuscular implantation and a better performance in a spinal fusion model in dogs. Results of the current study also showed significantly more bone formation in defects grafted with β-TCP compared to HA; however, both the ceramics were not capable of increasing bone formation to such extend that it bridges the defect. Furthermore, a more pronounced degradation of β-TCP was observed as compared to HA. Progression of inflammation and initiation of new bone formation were assessed for both materials at multiple time points by histological and fluorochrome-based analyses. Until 12 days postimplantation, a strong inflammatory response in absence of new bone formation was observed in both ceramics, without obvious differences between the two materials. Four weeks postimplantation, signs of new bone formation were found in both β-TCP and HA. At 6 weeks, inflammation had subsided in both ceramics while bone deposition continued. In conclusion, the two ceramics differed in the amount of bone formed after 8 weeks of implantation, whereas no differences were found in the duration of the inflammatory phase after implantation or initiation of new bone formation. Copyright © 2013 Wiley Periodicals, Inc.

  14. BIOCOMPATIBILITY OF IN HOUSE β-TRICALCIUM PHOSPHATE CERAMICS WITH NORMAL HUMAN OSTEOBLAST CELL

    Directory of Open Access Journals (Sweden)

    NURSHUHADA MOHD NAZIR

    2012-04-01

    Full Text Available β-Tricalcium Phosphate (β–TCP have been widely used as an implant materials. It has been successfully produced locally using two different method which is hydrothermal and precipitation. The aim of the study was to determine the biocompatibility of β-TCP prepared by hydrothermal and precipitation method with normal human osteoblast (NHOst cells. For this purpose cytotoxicity of the material was assessed using an Alamar Blue method to determine the viability of NHOst cells grown with extracts of β-TCP in various concentrations. In addition NHOst grown on β-TCP ceramics were examined under an inverted microscope after 4, 24, 48 and 72 hours to verify cell attachment. Staining was done using Calcein AM and Ethidium homodimers to assess viability using a Confocal Laser Scanning Microscope (CLSM. The results showed that neither hydrothermal β-TCP nor precipitation β-TCP were cytotoxic with either of the method applied.

  15. Understanding of dopant-induced osteogenesis and angiogenesis in calcium phosphate ceramics.

    Science.gov (United States)

    Bose, Susmita; Fielding, Gary; Tarafder, Solaiman; Bandyopadhyay, Amit

    2013-10-01

    General trends in synthetic bone grafting materials are shifting towards approaches that can illicit osteoinductive properties. Pharmacologics and biologics have been used in combination with calcium phosphate (CaP) ceramics, however, they have recently become the target of scrutiny over safety. The importance of trace elements in natural bone health is well documented. Ions, for example, lithium, zinc, magnesium, manganese, silicon, strontium, etc., have been shown to increase osteogenesis and neovascularization. Incorporation of dopants (trace metal ions) into CaPs can provide a platform for safe and efficient delivery in clinical applications where increased bone healing is favorable. This review highlights the use of trace elements in CaP biomaterials, and offers an insight into the mechanisms of how metal ions can enhance both osteogenesis and angiogenesis. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Trace element doping in calcium phosphate ceramics to Understand osteogenesis and angiogenesis

    Science.gov (United States)

    Bose, Susmita; Fielding, Gary; Tarafder, Solaiman; Bandyopadhyay, Amit

    2013-01-01

    The general trends in synthetic bone grafting materials are shifting towards approaches that can illicit osteoinductive properties. Pharmacologics and biologics have been used in combination with calcium phosphate (CaP) ceramics, however, recently have become the target of scrutiny over the safety. The importance of trace elements in natural bone health is well documented. Ions, e.g. lithium, zinc, magnesium, manganese, silicon, strontium etc. have shown to increase osteogenesis and neovascularization. Incorporation of dopants into CaPs can provide a platform for safe and efficient delivery in clinical applications where increased bone healing is favorable. This review highlights use of trace elements in CaP biomaterials, and offers an insight into the mechanisms of how metal ions can enhance both osteogenesis and angiogenesis. PMID:24012308

  17. Closing in on chemical bonds by opening up relativity theory.

    Science.gov (United States)

    Whitney, Cynthia K

    2008-03-01

    This paper develops a connection between the phenomenology of chemical bonding and the theory of relativity. Empirical correlations between electron numbers in atoms and chemical bond stabilities in molecules are first reviewed and extended. Quantitative chemical bond strengths are then related to ionization potentials in elements. Striking patterns in ionization potentials are revealed when the data are viewed in an element-independent way, where element-specific details are removed via an appropriate scaling law. The scale factor involved is not explained by quantum mechanics; it is revealed only when one goes back further, to the development of Einstein's special relativity theory.

  18. Closing in on Chemical Bonds by Opening up Relativity Theory

    Science.gov (United States)

    Whitney, Cynthia Kolb

    2008-01-01

    This paper develops a connection between the phenomenology of chemical bonding and the theory of relativity. Empirical correlations between electron numbers in atoms and chemical bond stabilities in molecules are first reviewed and extended. Quantitative chemical bond strengths are then related to ionization potentials in elements. Striking patterns in ionization potentials are revealed when the data are viewed in an element-independent way, where element-specific details are removed via an appropriate scaling law. The scale factor involved is not explained by quantum mechanics; it is revealed only when one goes back further, to the development of Einstein’s special relativity theory. PMID:19325749

  19. Electrical properties of phosphate glasses

    International Nuclear Information System (INIS)

    Mogus-Milankovic, A; Santic, A; Reis, S T; Day, D E

    2009-01-01

    Investigation of the electrical properties of phosphate glasses where transition metal oxide such as iron oxide is the network former and network modifier is presented. Phosphate glasses containing iron are electronically conducting glasses where the polaronic conduction is due to the electron hopping from low to high iron valence state. The identification of structural defects caused by ion/polaron migration, the analysis of dipolar states and electrical conductivity in iron phosphate glasses containing various alkali and mixed alkali ions was performed on the basis of the impedance spectroscopy (IS). The changes in electrical conductivity from as-quenched phosphate glass to fully crystallized glass (glass-ceramics) by IS are analyzed. A change in the characteristic features of IS follows the changes in glass and crystallized glass network. Using IS, the contribution of glass matrix, crystallized grains and grain boundary to the total electrical conductivity for iron phosphate glasses was analyzed. It was shown that decrease in conductivity is caused by discontinuities in the conduction pathways as a result of the disruption of crystalline network where two or more crystalline phases are formed. Also, phosphate-based glasses offer a unique range of biomaterials, as they form direct chemical bonding with hard/soft tissue. The surface charges of bioactive glasses are recognized to be the most important factors in determining biological responses. The improved bioactivity of the bioactive glasses as a result of the effects of the surface charges generated by electrical polarization is discussed.

  20. Synthesis, characterization, and in-vitro cytocompatibility of amorphous β-tri-calcium magnesium phosphate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Satish S., E-mail: sss42@pitt.edu [Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Roy, Abhijit, E-mail: abr20@pitt.edu [Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Lee, Boeun, E-mail: bol11@pitt.edu [Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Banerjee, Ipsita [Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Kumta, Prashant N., E-mail: pkumta@pitt.edu [Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Center for Craniofacial Regeneration, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Department of Mechanical Engineering and Materials Science, University of Pittsburgh, PA 15261 (United States)

    2016-10-01

    Biphasic mixtures of crystalline β-tricalcium magnesium phosphate (β-TCMP) and an amorphous calcium magnesium phosphate have been synthesized and reported to support enhanced hMSC differentiation in comparison to β-tricalcium phosphate (β-TCP) due to the release of increased amounts of bioactive ions. In the current study, completely amorphous β-TCMP has been synthesized which is capable of releasing increased amounts of Mg{sup 2+} and PO{sub 4}{sup 3−} ions, rather than a biphasic mixture as earlier reported. The amorphous phase formed was observed to crystallize between temperatures of 400–600 °C. The scaffolds prepared with amorphous β-TCMP were capable of supporting enhanced hMSC proliferation and differentiation in comparison to commercially available β-TCP. However, a similar gene expression of mature osteoblast markers, OCN and COL-1, in comparison to biphasic β-TCMP was observed. To further study the role of Mg{sup 2+} and PO{sub 4}{sup 3−} ions in regulating hMSC osteogenic differentiation, the capability of hMSCs to mineralize in growth media supplemented with Mg{sup 2+} and PO{sub 4}{sup 3−} ions was studied. Interestingly, 5 mM PO{sub 4}{sup 3−} supported mineralization while the addition of 5 mM Mg{sup 2+} to 5 mM PO{sub 4}{sup 3−} inhibited mineralization. It was therefore concluded that the release of Ca{sup 2+} ions from β-TCMP scaffolds also plays a role in regulating osteogenic differentiation on these scaffolds and it is noted that further work is required to more accurately determine the exact role of Mg{sup 2+} in regulating hMSC osteogenic differentiation. - Highlights: • Synthesis of amorphous Mg containing beta tricalcium phosphate ceramics • Amorphous beta TCMP supports enhanced hMSC proliferation and differentiation. • Amorphous beta TCMP shows comparable OCN and COL-1 expression to biphasic TCMP. • Presence of 5 mM Mg{sup 2+} and PO{sub 4}{sup 3−} ions in growth media inhibits hMSC mineralization.

  1. 3D Printing of Calcium Phosphate Ceramics for Bone Tissue Engineering and Drug Delivery

    Science.gov (United States)

    Trombetta, Ryan; Inzana, Jason A.; Schwarz, Edward M.; Kates, Stephen L.; Awad, Hani A.

    2016-01-01

    Additive manufacturing, also known as 3D printing, has emerged over the past 3 decades as a disruptive technology for rapid prototyping and manufacturing. Vat polymerization, powder bed fusion, material extrusion, and binder jetting are distinct technologies of additive manufacturing, which have been used in a wide variety of fields, including biomedical research and tissue engineering. The ability to print biocompatible, patient-specific geometries with controlled macro- and micropores, and to incorporate cells, drugs and proteins has made 3D-printing ideal for orthopaedic applications, such as bone grafting. Herein, we performed a systematic review examining the fabrication of calcium phosphate (CaP) ceramics by 3D printing, their biocompatibility in vitro, and their bone regenerative potential in vivo, as well as their use in localized delivery of bioactive molecules or cells. Understanding the advantages and limitations of the different 3D printing approaches, CaP materials, and bioactive additives through critical evaluation of in vitro and in vivo evidence of efficacy is essential for developing new classes of bone graft substitutes that can perform as well as autografts and allografts or even surpass the performance of these clinical standards. PMID:27324800

  2. 3D Printing of Calcium Phosphate Ceramics for Bone Tissue Engineering and Drug Delivery.

    Science.gov (United States)

    Trombetta, Ryan; Inzana, Jason A; Schwarz, Edward M; Kates, Stephen L; Awad, Hani A

    2017-01-01

    Additive manufacturing, also known as 3D printing, has emerged over the past 3 decades as a disruptive technology for rapid prototyping and manufacturing. Vat polymerization, powder bed fusion, material extrusion, and binder jetting are distinct technologies of additive manufacturing, which have been used in a wide variety of fields, including biomedical research and tissue engineering. The ability to print biocompatible, patient-specific geometries with controlled macro- and micro-pores, and to incorporate cells, drugs and proteins has made 3D-printing ideal for orthopaedic applications, such as bone grafting. Herein, we performed a systematic review examining the fabrication of calcium phosphate (CaP) ceramics by 3D printing, their biocompatibility in vitro, and their bone regenerative potential in vivo, as well as their use in localized delivery of bioactive molecules or cells. Understanding the advantages and limitations of the different 3D printing approaches, CaP materials, and bioactive additives through critical evaluation of in vitro and in vivo evidence of efficacy is essential for developing new classes of bone graft substitutes that can perform as well as autografts and allografts or even surpass the performance of these clinical standards.

  3. Planning a Teaching Sequence for the Teaching of Chemical Bonding

    Science.gov (United States)

    Sibanda, Doras; Hobden, Paul

    2015-01-01

    The current study seeks to examine how teachers plan teaching sequences to teach chemical bonding in the senior secondary phase of schooling. The study employs a learning demand tool as interpretive framework. A mixed method was used to guide the collection of data. Data were collected through a survey instrument with 227 practising physical…

  4. Study of structural, electrical, and dielectric properties of phosphate-borate glasses and glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Melo, B. M. G.; Graça, M. P. F., E-mail: mpfg@ua.pt; Prezas, P. R.; Valente, M. A. [Physics Department (I3N), Aveiro University, Campus Universitário de Santiago, Aveiro (Portugal); Almeida, A. F.; Freire, F. N. A. [Mechanics Engineering Department, Ceará Federal University, Fortaleza (Brazil); Bih, L. [Equipe Physico-Chimie la Matière Condensée, Faculté des Sciences de Meknès, Meknès (Morocco)

    2016-08-07

    In this work, phosphate-borate based glasses with molar composition 20.7P{sub 2}O{sub 5}–17.2Nb{sub 2}O{sub 5}–13.8WO{sub 3}–34.5A{sub 2}O–13.8B{sub 2}O{sub 3}, where A = Li, Na, and K, were prepared by the melt quenching technique. The as-prepared glasses were heat-treated in air at 800 °C for 4 h, which led to the formation of glass-ceramics. These high chemical and thermal stability glasses are good candidates for several applications such as fast ionic conductors, semiconductors, photonic materials, electrolytes, hermetic seals, rare-earth ion host solid lasers, and biomedical materials. The present work endorses the analysis of the electrical conductivity of the as-grown samples, and also the electrical, dielectric, and structural changes established by the heat-treatment process. The structure of the samples was analyzed using X-Ray powder Diffraction (XRD), Raman spectroscopy, and density measurements. Both XRD and Raman analysis confirmed crystals formation through the heat-treatment process. The electrical ac and dc conductivities, σ{sub ac} and σ{sub dc}, respectively, and impedance spectroscopy measurements as function of the temperature, varying from 200 to 380 K, were investigated for the as-grown and heat-treated samples. The impedance spectroscopy was measured in the frequency range of 100 Hz–1 MHz.

  5. Study of hMSC proliferation and differentiation on Mg and Mg–Sr containing biphasic β-tricalcium phosphate and amorphous calcium phosphate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Satish S., E-mail: sss42@pitt.edu [Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Roy, Abhijit, E-mail: abr20@pitt.edu [Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Lee, Boeun [Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Kumta, Prashant N., E-mail: pkumta@pitt.edu [Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Center for Craniofacial Regeneration, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Department of Mechanical Engineering and Materials Science, University of Pittsburgh, PA 15261 (United States)

    2016-07-01

    Biphasic mixtures of either Mg{sup 2+} or combined Mg{sup 2+} and Sr{sup 2+} cation substituted β-tricalcium phosphate (β-TCP) and amorphous calcium phosphate (ACP) were prepared using a low temperature chemical phosphatizing and hydrolysis reaction approach. Scaffolds prepared using the cation substituted calcium phosphates were capable of supporting similar levels of human mesenchymal stem cell proliferation in comparison to commercially available β-TCP. The concentrations of Mg{sup 2+}, Sr{sup 2+}, and PO{sub 4}{sup 3−} released from these scaffolds were also within the ranges desired from previous reports to support both hMSC proliferation and osteogenic differentiation. Interestingly, hMSCs cultured directly on scaffolds prepared with only Mg{sup 2+} substituted β-TCP were capable of supporting statistically significantly increased alkaline phosphatase activity, osteopontin, and osteoprotegerin expression in comparison to all compositions containing both Mg{sup 2+} and Sr{sup 2+}, and commercially available β-TCP. hMSCs cultured in the presence of scaffold extracts also exhibited similar trends in the expression of osteogenic markers as was observed during direct culture. Therefore, it was concluded that the enhanced differentiation observed was due to the release of bioactive ions rather than the surface microstructure. The role of these ions on transforming growth factor-β and bone morphogenic protein signaling was also evaluated using a PCR array. It was concluded that the release of these ions may support enhanced differentiation through SMAD dependent TGF-β and BMP signaling. - Highlights: • Synthesis of Mg and Mg-Sr containing biphasic beta tricalcium phosphate ceramics • Magnesium substitution influences ALP activity compared to strontium content. • Solution extract plays a more dominant role on hMSC differentiation. • Direct and indirect Mg and Mg-Sr TCP culture show similar OPG and OPN expression.

  6. Porous biphasic calcium phosphate ceramics coated with nano-hydroxyapatite and seeded with mesenchymal stem cells for reconstruction of radius segmental defects in rabbits.

    Science.gov (United States)

    Hu, Jianzhong; Yang, Zhiming; Zhou, Yongchun; Liu, Yong; Li, Kaiyang; Lu, Hongbin

    2015-11-01

    The osteoconduction of porous biphasic calcium phosphate (BCP) ceramics has been widely reported. In a previous study, we demonstrated that applying a nano-hydroxyapatite (nHA) coating enhances the osteoinductive potential of BCP ceramics, making these scaffolds more suitable for bone tissue engineering applications. The aim of the present study was to determine the effects of reconstructing radius defects in rabbits using nHA-coated BCP ceramics seeded with mesenchymal stem cells (MSCs) and to compare the bone regeneration induced by different scaffolds. Radius defects were created in 20 New Zealand rabbits, which were divided into four groups by treatment: porous BCP ceramics (Group A), nHA-coated porous BCP ceramics (Group B), porous BCP ceramics seeded with rabbit MSCs (Group C), and nHA-coated porous BCP ceramics seeded with rabbit MSCs (Group D). After in vitro incubation, the cell/scaffold complexes were implanted into the defects. Twelve weeks after implantation, the specimens were examined macroscopically and histologically. Both the nHA coating and seeding with MSCs enhanced the formation of new bone tissue in the BCP ceramics, though the osteoinductive potential of the scaffolds with MSCs was greater than that of the nHA-coated scaffolds. Notably, the combination of nHA coating and MSCs significantly improved the bone regeneration capability of the BCP ceramics. Thus, MSCs seeded into porous BCP ceramics coated with nHA may be an effective bone substitute to reconstruct bone defects in the clinic.

  7. The nature of chemical bonds from PNOF5 calculations.

    Science.gov (United States)

    Matxain, Jon M; Piris, Mario; Uranga, Jon; Lopez, Xabier; Merino, Gabriel; Ugalde, Jesus M

    2012-06-18

    Natural orbital functional theory (NOFT) is used for the first time in the analysis of different types of chemical bonds. Concretely, the Piris natural orbital functional PNOF5 is used. It provides a localization scheme that yields an orbital picture which agrees very well with the empirical valence shell electron pair repulsion theory (VSEPR) and Bent's rule, as well as with other theoretical pictures provided by valence bond (VB) or linear combination of atomic orbitals-molecular orbital (LCAO-MO) methods. In this context, PNOF5 provides a novel tool for chemical bond analysis. In this work, PNOF5 is applied to selected molecules that have ionic, polar covalent, covalent, multiple (σ and π), 3c-2e, and 3c-4e bonds. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Researching on thermal characters in Yb3+/Er3+ codoped phosphate glass ceramic for fluorescence temperature sensor

    Directory of Open Access Journals (Sweden)

    Yuanxue Cai

    Full Text Available To explore fluorescence temperature sensor, Yb3+/Er3+ co-doped phosphate glass ceramic was prepared by high-temperature melting method and thermal annealing technology. The luminescent spectra of the sample were measured under 975 nm excitation at the temperature ranges of 25–300 °C. The strong green up-conversion emissions, coming from the transitions of Er3+ ion: 2H11/2-4I15/2 and 4S3/2-4I15/2, were observed. The fluorescence intensity ratio of the two green up-conversion emissions can change with the increasing of temperature. The sensitivity of Er3+/Yb3+ co-doped phosphate glass ceramic reached the maximal value of ∼0.0077 K−1. The sensitivity is relatively flat at the high temperature region. Our research is valuable to developing fluorescence temperature sensor. Keywords: Luminescence, Optical materials and properties, Sensor

  9. Experimental and in silico investigations of organic phosphates and phosphonates sorption on polymer-ceramic monolithic materials and hydroxyapatite.

    Science.gov (United States)

    Pietrzyńska, Monika; Zembrzuska, Joanna; Tomczak, Rafał; Mikołajczyk, Jakub; Rusińska-Roszak, Danuta; Voelkel, Adam; Buchwald, Tomasz; Jampílek, Josef; Lukáč, Miloš; Devínsky, Ferdinand

    2016-10-10

    A method based on experimental and in silico evaluations for investigating interactions of organic phosphates and phosphonates with hydroxyapatite was developed. This quick and easy method is used for determination of differences among organophosphorus compounds of various structures in their mineral binding affinities. Empirical sorption evaluation was carried out using liquid chromatography with tandem mass spectrometry or UV-VIS spectroscopy. Raman spectroscopy was used to confirm sorption of organic phosphates and phosphonates on hydroxyapatite. Polymer-ceramic monolithic material and bulk hydroxyapatite were applied as sorbent materials. Furthermore, a Polymer-ceramic Monolithic In-Needle Extraction device was used to investigate both sorption and desorption steps. Binding energies were computed from the fully optimised structures utilising Density Functional Theory (DFT) at B3LYP/6-31+G(d,p) level. Potential pharmacologic and toxic effects of the tested compounds were estimated by the Prediction of the Activity Spectra of Substances using GeneXplain software. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Rapid biomimetic deposition of octacalcium phosphate coatings on zirconia ceramics (Y-TZP) for dental implant applications

    Science.gov (United States)

    Stefanic, Martin; Krnel, Kristoffer; Pribosic, Irena; Kosmac, Tomaz

    2012-03-01

    Octacalcium phosphate (OCP) coatings on zirconia oral implants have a great potential to improve the osseointegration of already existing ceramic implants, owing to high osteoconductive characteristics of OCP and its possibility of use as a drug delivery system. Such OCP coatings can be prepared with a simple two-step biomimetic procedure investigated in our study. In the first step, zirconia discs were immersed into the solution with a pH 7.4 and after 1 h of soaking a thin nanostructured calcium phosphate (Ca-P) layer was precipitated on the ceramic substrate via three stages: (i) precipitation of an amorphous Ca-P; (ii) precipitation of the OCP; and (iii) the transformation of the OCP to apatite. This Ca-P layer later served as a template for the rapid deposition of a thicker OCP coating in the second step of the synthesis where the substrate was immersed into the solution with pH 7.0. The main benefits of the method are a relatively quick synthesis, simplicity and a good reproducibility. Moreover, the coatings show good tensile adhesion strength according to the tape tests (ASTM D-3359). In addition, mild physiological conditions of the synthesis may allow incorporation of biologically active molecules in the coating.

  11. Structure and short time degradation studies of sodium zirconium phosphate ceramics loaded with simulated fast breeder (FBR) waste

    Science.gov (United States)

    Ananthanarayanan, A.; Ambashta, R. D.; Sudarsan, V.; Ajithkumar, T.; Sen, D.; Mazumder, S.; Wattal, P. K.

    2017-04-01

    Sodium zirconium phosphate (NZP) ceramics have been prepared using conventional sintering and hot isostatic pressing (HIP) routes. The structure of NZP ceramics, prepared using the HIP route, has been compared with conventionally sintered NZP using a combination of X-ray diffraction (XRD) and (31P and 23Na) nuclear magnetic resonance (NMR) spectroscopy techniques. It is observed that NZP with no waste loading is aggressive toward the steel HIP-can during hot isostatic compaction and significant fraction of cations from the steel enter the ceramic material. Waste loaded NZP samples (10 wt% simulated FBR waste) show significantly low can-interaction and primary NZP phase is evident in this material. Upon exposure of can-interacted and waste loaded NZP to boiling water and steam, 31P NMR does not detect any major modifications in the network structure. However, the 23Na NMR spectra indicate migration of Na+ ions from the surface and possible re-crystallization. This is corroborated by Small-Angle Neutron Scattering (SANS) data and Scanning Electron Microscopy (SEM) measurements carried out on these samples.

  12. Microstructure and spectroscopic investigations of calcium zinc bismuth phosphate glass ceramics doped with manganese ions

    Science.gov (United States)

    Suneel Kumar, A.; Sambasiva Rao, M. V.; Chinna Ram, G.; Krishna Rao, D.

    2018-01-01

    Multi-component 10CaF2-20ZnO-(15 - x)Bi2O3-55P2O5:xMnO (0 ≤ x ≤ 2.5) glass ceramics were synthesised by melt quenching technique and heat treatment. The prepared glass ceramics were characterised by XRD, DTA, EDS and SEM. Spectroscopic studies such as optical absorption, EPR, FTIR and Raman were also carried out on these glass ceramics. The XRD and SEM studies have indicated that ceramic samples contain well defined and randomly distributed grains of different crystalline phases. The observed increase of enthalpy from DTA patterns up to 1 mol% of MnO indicates that the crystallisation starts initially from the surface of the material then gradually it is extended to the volume of the material and this influence is meagre at higher concentrations of MnO. The absorption spectra of manganese doped glass ceramics have exhibited two types of conventional bands; one due to Mn2+ ions and other due to Mn3+ ions. The EPR spectra of MnO doped glass ceramics showed a resonance signal around g2 = 2.023 with a six line hyperfine structure and another signal at about g1 = 4.314. The relative intensity and half-width of these two signals are observed to increase with the increase in the concentration of manganese ions up to 1 mol% beyond this concentration it is found to decrease. Such observation indicates the conversion of part of Mn2+ ions into Mn3+ ions in the glass ceramic matrix. The observed increase in the intensity of symmetrical structural units at the expense of asymmetrical structural units from the FTIR and Raman spectra at higher concentration of MnO indicating that Mn2+ ions occupy the network forming positions in the glass ceramic structure.

  13. Development of zirconium/magnesium phosphate composites for immobilization of fission products

    International Nuclear Information System (INIS)

    Singh, D.; Tlustochowicz, M.; Wagh, A.S.

    1999-01-01

    Novel chemically bonded phosphate ceramics have been investigated for the capture and stabilization of volatile fission-product radionuclides. The authors have used low-temperature processing to fabricate zirconium phosphate and zirconium/magnesium phosphate composites. A zirconium/magnesium phosphate composite has been developed and shown to stabilize ash waste that has been contaminated with a radioactive surrogate of the 137 Cs and 90 Sr species. Excellent retention of cesium in the phosphate matrix system was observed in both short- and long-term leaching tests. The retention factor determined by the USEPA Toxicity Characteristic Leaching Procedure was one order of magnitude better for cesium that for strontium. The effective diffusivity, at room temperature, for cesium and strontium in the waste forms was estimated to be as low as 2.4 x 10 -13 and 1.2 x 10 -11 m 2 /s, respectively. This behavior was attributed to the capture of cesium in the layered zirconium phosphate structure via an intercalation ion-exchange reaction, followed by microencapsulation. However, strontium is believed to be precipitated out in its phosphate form and subsequently microencapsulated in the phosphate ceramic. The performance of these final waste forms, as indicated by the compression strength and the durability in aqueous environments, satisfies the regulatory criteria

  14. Benchmarking Density Functionals for Chemical Bonds of Gold

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta

    2017-01-01

    Gold plays a major role in nanochemistry, catalysis, and electrochemistry. Accordingly, hundreds of studies apply density functionals to study chemical bonding with gold, yet there is no systematic attempt to assess the accuracy of these methods applied to gold. This paper reports a benchmark...... considering the diverse bonds to gold and the complication of relativistic effects. Thus, studies that use DFT with effective core potentials for gold chemistry, with no alternative due to computational cost, are on solid ground using TPSS-D3 or PBE-D3....

  15. Unicorns in the world of chemical bonding models.

    Science.gov (United States)

    Frenking, Gernot; Krapp, Andreas

    2007-01-15

    The appearance and the significance of heuristically developed bonding models are compared with the phenomenon of unicorns in mythical saga. It is argued that classical bonding models played an essential role for the development of the chemical science providing the language which is spoken in the territory of chemistry. The advent and the further development of quantum chemistry demands some restrictions and boundary conditions for classical chemical bonding models, which will continue to be integral parts of chemistry. Copyright (c) 2006 Wiley Periodicals, Inc.

  16. Fluorescence spectral studies of chromium and titanium ions in phosphate glass ceramics

    International Nuclear Information System (INIS)

    Veeraiah, N.

    2008-01-01

    The luminescence characteristics of glass ceramic depend on the kind and quantity of the crystal phase formed as well as on the residual glass composition. Hence, the selection of a suitable nucleating agent in the correct concentration and determination on the temperature and the time of nucleation and growth are important factors, in deciding the luminescence efficiency of glass-ceramic. The nucleating agents that are generally used for controlled crystallization processes, giving rise to enormous numbers of nucleation centres in the original glass are, gold, silver, platinum or the oxides of Ti, Cr, Mn, Ce, V, Ni, and Zr or certain sulfides or fluorides. The objective of this talk is to throw some light on the photoluminescence characteristics of Ti, Cr, and Mn ions in Li 2 O-CaF 2 -P 2 O 5 glass ceramic system

  17. A New Biocompatible and Antibacterial Phosphate Free Glass-Ceramic for Medical Applications

    Science.gov (United States)

    Cabal, Belén; Alou, Luís; Cafini, Fabio; Couceiro, Ramiro; Sevillano, David; Esteban-Tejeda, Leticia; Guitián, Francisco; Torrecillas, Ramón; Moya, José S.

    2014-06-01

    In the attempt to find valid alternatives to classic antibiotics and in view of current limitations in the efficacy of antimicrobial-coated or loaded biomaterials, this work is focused on the development of a new glass-ceramic with antibacterial performance together with safe biocompatibility. This bactericidal glass-ceramic composed of combeite and nepheline crystals in a residual glassy matrix has been obtained using an antimicrobial soda-lime glass as a precursor. Its inhibitory effects on bacterial growth and biofilm formation were proved against five biofilm-producing reference strains. The biocompatibility tests by using mesenchymal stem cells derived from human bone indicate an excellent biocompatibility.

  18. A New Biocompatible and Antibacterial Phosphate Free Glass-Ceramic for Medical Applications

    Science.gov (United States)

    Cabal, Belén; Alou, Luís; Cafini, Fabio; Couceiro, Ramiro; Sevillano, David; Esteban-Tejeda, Leticia; Guitián, Francisco; Torrecillas, Ramón; Moya, José S.

    2014-01-01

    In the attempt to find valid alternatives to classic antibiotics and in view of current limitations in the efficacy of antimicrobial-coated or loaded biomaterials, this work is focused on the development of a new glass-ceramic with antibacterial performance together with safe biocompatibility. This bactericidal glass-ceramic composed of combeite and nepheline crystals in a residual glassy matrix has been obtained using an antimicrobial soda-lime glass as a precursor. Its inhibitory effects on bacterial growth and biofilm formation were proved against five biofilm-producing reference strains. The biocompatibility tests by using mesenchymal stem cells derived from human bone indicate an excellent biocompatibility. PMID:24961911

  19. Neutron-scattering studies of nitride, oxide, and phosphate ceramics and their relationship with molecular-dynamics simulations of high-temperature properties

    International Nuclear Information System (INIS)

    Loong, C.K.

    1997-01-01

    Currently, the strength and reliability of nitride and carbide ceramics are not sufficient to meet the demands of high-tech applications such as heat engines. A large R and D effort is needed to advance the field of ceramic science and engineering. The strength of ceramics depends on both the nature of atomic bonding such as covalency versus ionicity and the microstructure such as flaws and stress within the materials. The length scale of these influential factors ranges from 0.1 to 5,000 nm, thus presenting a challenge to experimentalists for a complete, quantitative characterization. The method of neutron scattering provides distinct advantages. In this paper, the authors present the neutron-scattering results of several important nitride oxide, and phosphate ceramics and point out the connections between the neutron data and computer simulations towards the goal of designing high-temperature materials

  20. Long-term conversion of 45S5 bioactive glass-ceramic microspheres in aqueous phosphate solution.

    Science.gov (United States)

    Fu, Hailuo; Rahaman, Mohamed N; Day, Delbert E; Huang, Wenhai

    2012-05-01

    The conversion of 45S5 glass and glass-ceramics to a hydroxyapatite (HA)-like material in vitro has been studied extensively, but only for short reaction times (typically glass-ceramic microspheres (designated 45S5c) in an aqueous phosphate solution. Microspheres of 45S5c (75-150 μm) were immersed for 10 years at room temperature (~25 °C) in K(2)HPO(4) solution with a concentration of 0.01 M or 1.0 M, and with a starting pH of 7.0 or 9.5. The reacted 45S5c microspheres and solutions were analyzed using structural and analytical techniques. Only 25-45 vol% of the 45S5c microspheres were converted to an HA-like material after the 10 year reaction. In solutions with a starting pH of 9.5, an increase in the K(2)HPO(4) concentration from 0.01 to 1.0 M resulted in a doubling of the volume of the microspheres converted to an HA-like material but had little effect on the composition of the HA-like product. In comparison, reaction of the 45S5c microspheres in the solution with a starting pH of 7.0 resulted in an HA-like product in the 0.01 M K(2)HPO(4) solution but a calcium pyrophosphate product, Ca(10)K(4)(P(2)O(7))(6).9H(2)O, in the 1.0 M solution. The consequences of these results for the long-term use of 45S5 glass-ceramics in biomedical applications are discussed.

  1. Calcium phosphate holmium-166 ceramic to addition in bone cement: synthesis and characterization

    International Nuclear Information System (INIS)

    Donanzam, Blanda A.; Campos, Tarcisio P.R.

    2011-01-01

    Spine metastases are a common and painful complication of cancer. The treatment often consists of bone cement injection (vertebroplasty or kyphoplasty) within vertebral body for vertebrae stabilization, followed by external beam radiation therapy. Recently, researchers introduced the concept of radioactive bone cement for spine tumors therapy. Then, investigations about bioactive and radioactive materials became interesting. In this study, we present the synthesis of calcium phosphate incorporated holmium (CaP-Ho) via sol-gel technique, and its characterization by XRD, FT-IR, NA and SEM. Results showed a multiphasic bioceramic composed mainly of hydroxyapatite, β-tricalcium phosphate, holmium phosphate and traces of calcium pyrophosphate. Furthermore, the nuclide Ho-166 was the major radioisotope produced. Despite that, the radioactive bioceramic CaP- 166 Ho must be investigated in clinical trials to assure its efficacy and safety on spine tumors treatment (author)

  2. Calcium phosphate holmium-166 ceramic to addition in bone cement: synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Donanzam, Blanda A.; Campos, Tarcisio P.R., E-mail: campos@nuclear.ufmg.b [Universidade do Federal de Minas Gerais (DEN/UFMG), Belo Horizonte, MG (Brazil). Escola de Engenharia. Dept. de Engenharia Nuclear; Dalmazio, Ilza; Valente, Eduardo S., E-mail: id@cdtn.b, E-mail: valente@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2011-07-01

    Spine metastases are a common and painful complication of cancer. The treatment often consists of bone cement injection (vertebroplasty or kyphoplasty) within vertebral body for vertebrae stabilization, followed by external beam radiation therapy. Recently, researchers introduced the concept of radioactive bone cement for spine tumors therapy. Then, investigations about bioactive and radioactive materials became interesting. In this study, we present the synthesis of calcium phosphate incorporated holmium (CaP-Ho) via sol-gel technique, and its characterization by XRD, FT-IR, NA and SEM. Results showed a multiphasic bioceramic composed mainly of hydroxyapatite, {beta}-tricalcium phosphate, holmium phosphate and traces of calcium pyrophosphate. Furthermore, the nuclide Ho-166 was the major radioisotope produced. Despite that, the radioactive bioceramic CaP-{sup 166}Ho must be investigated in clinical trials to assure its efficacy and safety on spine tumors treatment (author)

  3. Processing highly porous calcium phosphate ceramics for use in bioreactor cores for culturing human liver cells in-vitro

    Science.gov (United States)

    Finoli, Anthony

    Chronic liver disease is the 11th highest cause of death in the United States claiming over 30,000 lives in 2009. The current treatment for chronic liver failure is liver transplantation but the availability of tissue is far less than the number of patients in need. To develop human liver tissue in the lab a 3D culturing environment must be created to support the growth of a complex tissue. Hydroxyapatite (HAp) has been chosen as a scaffold material because of its biocompatibility in the body and the ability to create a bioresorbable scaffold. By using a ceramic material, it is possible to create a three dimensional, protective environment in which tissue can grow. The first part of this study is to examine the behavior of adult human liver cells grown on composites of HAp and different biocompatible hydrogels. Porous HAp has been created using an emulsion foaming technique and cells are injected into the structure after being suspended in a hydrogel and are kept in culture for up to 28 days. Functional assays, gene expression and fluorescent microscopy will be used to examine these cultures. The second part of this study will be to develop a processing technique to create a resorbable scaffold that incorporates a vascular system template. Previous experiments have shown the high temperature decomposition of HAp into resorbable calcium phosphates will be used to create a multiphase material. By controlling the amount of transformation product formed, it is proposed that the resorption of the scaffold can be tailored. To introduce a pore network to guide the growth of a vascular system, a positive-negative casting technique has also been developed. A positive polymer copy can be made of a natural vascular system and ceramic is foamed around the copy. During sintering, the polymer is pyrolyzed leaving a multiscale pore network in the ceramic. By combining these techniques, it is proposed that a calcium phosphate bioreactor core can be processed that is suitable for

  4. Synthesis and characterization of cerium containing iron phosphate based glass-ceramics

    Science.gov (United States)

    Deng, Yi; Liao, Qilong; Wang, Fu; Zhu, Hanzhen

    2018-02-01

    The structure and properties of xCeO2-(100-x)(40Fe2O3-60P2O5), where x = 0, 2, 4, 6 and 8 mol%, glass-ceramics prepared by melting and slow cooling method have been investigated by using X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), differential thermal analysis (DTA) and the Product Consistency Test (PCT). The results show that the 40Fe2O3-60P2O5 sample is homogeneously amorphous and the sample containing 2 mol% CeO2 has a small amount of FePO4 phase embedded. For the sample containing up to 4 mol% CeO2, monazite CePO4 and a small amount of FePO4 appear. Spectra analysis show that the structure networks of the glass-ceramics mainly consist of orthophosphate, along with pyrophosphate and a small amount of metaphosphate units. Moreover, the leaching rates of Fe and Ce are about 3.5 × 10-5 g m-2 d-1 and 5.0 × 10-5 g m-2 d-1 respectively after immersion in deionized water at 90 °C for 56 days, indicating their good chemical durability. The conclusions imply that the prepared method may be a promising process to immobilize nuclear waste into glass-ceramic matrix.

  5. "Vibrational bonding": a new type of chemical bond is discovered.

    Science.gov (United States)

    Rhodes, Christopher J; Macrae, Roderick M

    2015-01-01

    A long-sought but elusive new type of chemical bond, occurring on a minimum-free, purely repulsive potential energy surface, has recently been convincingly shown to be possible on the basis of high-level quantum-chemical calculations. This type of bond, termed a vibrational bond, forms because the total energy, including the dynamical energy of the nuclei, is lower than the total energy of the dissociated products, including their vibrational zero-point energy. For this to be the case, the ZPE of the product molecule must be very high, which is ensured by replacing a conventional hydrogen atom with its light isotope muonium (Mu, mass = 1/9 u) in the system Br-H-Br, a natural transition state in the reaction between Br and HBr. A paramagnetic species observed in the reaction Mu +Br2 has been proposed as a first experimental sighting of this species, but definitive identification remains challenging.

  6. The chemical bond in inorganic chemistry the bond valence model

    CERN Document Server

    Brown, I David

    2016-01-01

    The bond valence model is a version of the ionic model in which the chemical constraints are expressed in terms of localized chemical bonds formed by the valence charge of the atoms. Theorems derived from the properties of the electrostatic flux predict the rules obeyed by both ionic and covalent bonds. They make quantitative predictions of coordination number, crystal structure, bond lengths and bond angles. Bond stability depends on the matching of the bonding strengths of the atoms, while the conflicting requirements of chemistry and space lead to the structural instabilities responsible for the unusual physical properties displayed by some materials. The model has applications in many fields ranging from mineralogy to molecular biology.

  7. Heat treatment of pre-hydrolyzed silane increases adhesion of phosphate monomer-based resin cement to glass ceramic.

    Science.gov (United States)

    de Carvalho, Rodrigo Furtado; Cotes, Caroline; Kimpara, Estevão Tomomitsu; Leite, Fabíola Pessoa Pereira; Özcan, Mutlu

    2015-01-01

    This study evaluated the influence of different forms of heat treatment on a pre-hydrolyzed silane to improve the adhesion of phosphate monomer-based (MDP) resin cement to glass ceramic. Resin and feldspathic ceramic blocks (n=48, n=6 for bond test, n=2 for microscopy) were randomly divided into 6 groups and subject to surface treatments: G1: Hydrofluoric acid (HF) 9.6% for 20 s + Silane + MDP resin cement (Panavia F); G2: HF 9.6% for 20 s + Silane + Heat Treatment (oven) + Panavia F; G3: Silane + Heat Treatment (oven) + Panavia F; G4: HF 9.6% for 20 s + Silane + Heat Treatment (hot air) + Panavia F; G5: Silane + Heat Treatment (hot air) + Panavia F; G6: Silane + Panavia F. Microtensile bond strength (MTBS) test was performed using a universal testing machine (1 mm/min). After debonding, the substrate and adherent surfaces were analyzed using stereomicroscope and scanning electron microscope (SEM) to categorize the failure types. Data were analyzed statistically using two-way test ANOVA and Tukey's test (=0.05). Heat treatment of the silane containing MDP, with prior etching with HF (G2: 13.15 ± 0.89a; G4: 12.58 ± 1.03a) presented significantly higher bond strength values than the control group (G1: 9.16 ± 0.64b). The groups without prior etching (G3: 10.47 ± 0.70b; G5: 9.47 ± 0.32b) showed statistically similar bond strength values between them and the control group (G1). The silane application without prior etching and heat treatment resulted in the lowest mean bond strength (G6: 8.05 ± 0.37c). SEM analysis showed predominantly adhesive failures and EDS analysis showed common elements of spectra (Si, Na, Al, K, O, C) characterizing the microstructure of the glass-ceramic studied. Heat treatment of the pre-hydrolyzed silane containing MDP in an oven at 100 °C for 2 min or with hot air application at 50 ± 5 ºC for 1 min, was effective in increasing the bond strength values between the ceramic and resin cement containing MDP.

  8. A silver ion-doped calcium phosphate-based ceramic nanopowder-coated prosthesis increased infection resistance.

    Science.gov (United States)

    Kose, Nusret; Otuzbir, Ali; Pekşen, Ceren; Kiremitçi, Abdurrahman; Doğan, Aydin

    2013-08-01

    Despite progress in surgical techniques, 1% to 2% of joint arthroplasties become complicated by infection. Coating implant surfaces with antimicrobial agents have been attempted to prevent initial bacterial adhesion to implants with varying success rates. We developed a silver ion-containing calcium phosphate-based ceramic nanopowder coating to provide antibacterial activity for orthopaedic implants. We asked whether titanium prostheses coated with this nanopowder would show resistance to bacterial colonization as compared with uncoated prostheses. We inserted titanium implants (uncoated [n = 9], hydroxyapatite-coated [n = 9], silver-coated [n = 9]) simulating knee prostheses into 27 rabbits' knees. Before implantation, 5 × 10(2) colony-forming units of Staphylococcus aureus were inoculated into the femoral canal. Radiology, microbiology, and histology findings were quantified at Week 6 to define the infection, microbiologically by increased rate of implant colonization/positive cultures, histologically by leukocyte infiltration, necrosis, foreign-body granuloma, and devitalized bone, and radiographically by periosteal reaction, osteolysis, or sequestrum formation. Swab samples taken from medullary canals and implants revealed a lower proportion of positive culture in silver-coated implants (one of nine) than in uncoated (eight of nine) or hydroxyapatite-coated (five of nine) implants. Silver-coated implants also had a lower rate of colonization. No cellular inflammation or foreign-body granuloma was observed around the silver-coated prostheses. Silver ion-doped ceramic nanopowder coating of titanium implants led to an increase in resistance to bacterial colonization compared to uncoated implants. Silver-coated orthopaedic implants may be useful for resistance to local infection but will require in vivo confirmation.

  9. The thorium phosphate diphosphate as a ceramic for the actinides immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Dacheux, N.; Thomas, A.C.; Chassigneux, B.; Brandel, V.; Genet, M. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire

    1999-07-01

    Considering that phosphate matrices like apatites or monazites could be potential candidates for the immobilization of actinides, the thorium phosphates chemistry has been completely reexamined. Among the solids synthesized, the Thorium Phosphate Diphosphate (namely TPD) was obtained after heating at 1250 degrees Celsius for 10 hours whatever the chemical way of synthesis using dry or wet chemistry methods, whatever the thorium salt and the phosphating reagent used in the condition to respect the initial mole ratio Th/PO{sub 4}=2/3. The ab initio structure determination was achieved on powder and single crystal and led to an orthorhombic unit cell. In this structure, the thorium atoms are eightfold coordinated. The substitution of thorium atoms by tetravalent actinides leading to the formation of Th{sub 4-x}M{sub x}(PO{sub 4}){sub 4}P{sub 2}O{sub 7} (M=U, Np, Pu) solid solutions (respectively TUPD, TNPD, TPPD) was also investigated. For each actinide, several solid solutions were synthesized. The linear decrease of the unit cell parameters and volume refined as a function of the x value has been observed. It confirms that solid solutions are well formed. The equations obtained by linear regression are in very good agreement with the ionic radii reported in the literature for U{sup 4+}, Np{sup 4+} and Pu{sup 4+} in the eightfold coordination. The maximum substitution of Th{sup 4+} by each tetravalent actinide has been determined as well as the corresponding Maximum Mole Loading (MML) and Maximum Weight Loading (MWL). It appeared that the TPD structure allows the replacement of thorium by large amounts of tetravalent uranium, neptunium and plutonium. Pellets of TPD and TUPD solid solutions were prepared and the corresponding densities determined. They correspond to 95-99 % of the values calculated from crystallographic data. In order to study the resistance of these materials (TPD, TUPD, TPPD) to aqueous alteration, leaching tests were achieved in distilled water and

  10. Biphasic Calcium Phosphate Ceramics for Bone Regeneration and Tissue Engineering Applications

    Directory of Open Access Journals (Sweden)

    Sonja Ellen Lobo

    2010-01-01

    Full Text Available Biphasic calcium phosphates (BCP have been sought after as biomaterials for the reconstruction of bone defects in maxillofacial, dental and orthopaedic applications. They have demonstrated proven biocompatibility, osteoconductivity, safety and predictability in in vitro, in vivo and clinical models. More recently, in vitro and in vivo studies have shown that BCP can be osteoinductive. In the field of tissue engineering, they represent promising scaffolds capable of carrying and modulating the behavior of stem cells. This review article will highlight the latest advancements in the use of BCP and the characteristics that create a unique microenvironment that favors bone regeneration.

  11. Sodium aluminum-iron phosphate glass-ceramics for immobilization of lanthanide oxide wastes from pyrochemical reprocessing of spent nuclear fuel

    Science.gov (United States)

    Stefanovsky, S. V.; Stefanovsky, O. I.; Kadyko, M. I.; Nikonov, B. S.

    2018-03-01

    Sodium aluminum (iron) phosphate glass ceramics containing of up to 20 wt.% rare earth (RE) oxides simulating pyroprocessing waste were produced by melting at 1250 °C followed by either quenching or slow cooling to room temperature. The iron-free glass-ceramics were composed of major glass and minor phosphotridymite and monazite. The iron-bearing glass-ceramics were composed of major glass and minor monazite and Na-Al-Fe orthophosphate at low waste loadings (5-10 wt.%) and major orthophosphate and minor monazite as well as interstitial glass at high waste loadings (15-20 wt.%). Slowly cooled samples contained higher amount of crystalline phases than quenched ones. Monazite is major phase for REs. Leach rates from the materials of major elements (Na, Al, Fe, P) are 10-5-10-7 g cm-2 d-1, RE elements - lower than 10-5 g cm-2 d-1.

  12. Obtain ceramic porous alumina-zirconia by replica method calcium phosphate coated

    International Nuclear Information System (INIS)

    Silva, A.D.R.; Rigoli, W.R.; Osiro, Denise; Pallone, E.M.J.A.

    2016-01-01

    Biomaterials used in bone replacement, including porous bioceramics, are often used as support structure for bone formation and repair. The porous bioceramics are used because present features as biocompatibility, high porosity and pore morphology that confer adequate mechanical strength and induce bone growth. In this work were obtained porous specimens of alumina containing 5% by inclusion of volume of zirconia produced by the replica method. The porous specimens had its surface chemically treated with phosphoric acid and were coated with calcium phosphate. The coating was performed using the biomimetic method during 14 days and an initial pH of 6.1. The porous specimens were characterized using the follow techniques: porosity, axial compression tests, microtomography, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and pH measurements SBF solution. The results showed specimens with suitable pore morphology for application as biomaterial, and even a reduced time of incubation favored the calcium phosphate phases formation on the material surfaces. (author)

  13. Combined numerical and experimental mechanical characterization of a calcium phosphate ceramic using modified Brazilian disc and SCB specimen

    Energy Technology Data Exchange (ETDEWEB)

    Elghazel, A., E-mail: elgazelachwak@live.fr [Laboratory of Industrial Chemistry, National School of Engineering, Box 1173, 3038 Sfax (Tunisia); Taktak, R. [Materials Engineering and Environment Laboratory (LGME), National School of Engineering, 3038 Sfax (Tunisia); Bouaziz, J. [Laboratory of Industrial Chemistry, National School of Engineering, Box 1173, 3038 Sfax (Tunisia)

    2016-07-18

    Ceramics and bioceramic composites are materials characterized with strong but quite low crack-resistance properties. Indeed, their application is hindered by their brittleness and low ability to deform. This paper presents an examination of the mechanical behavior of a commercial tricalcium phosphate (TCP) mixed with synthesized fluorapatite (Fap) powder. A new method called the semi-circular bending “SCB” method is developed for mode I fracture toughness determination. The samples were characterized by scanning electronic microscopy measurements and examined for mechanical properties, such as compressive strength, flexural strength, tensile strength, elastic modulus, Vickers hardness and fracture toughness under tensile and shear mode. The evolution of these mechanical properties and microstructure of TCP-Fap was studied. The performances of the composites increase with the addition of the Fap. The highest values of the composites of compressive strength (95 MPa), flexural strength (15 MPa), tensile strength (7 MPa) and fracture toughness (2.9 MPa m{sup 1/2}) were obtained after the sintering process with 33.16 wt% Fap at 1300° C. The increase of these performances is due to the formation of the liquid phase, which helps to fill the pores in the microstructure. Above 33.16 wt% Fap, the mechanical properties of the composites are hindered by the exaggerated grain growth formation.

  14. Systematic investigation of the strontium zirconium phosphate ceramic form for nuclear waste immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Pet' kov, Vladimir; Asabina, Elena, E-mail: e.a.asabina@gmail.com; Loshkarev, Vladimir; Sukhanov, Maksim

    2016-04-01

    We have summarized our data and literature ones on the thermophysical properties and hydrolytic stability of Sr{sub 0.5}Zr{sub 2}(PO{sub 4}){sub 3} compound as a host NaZr{sub 2}(PO{sub 4}){sub 3}-type (NZP) structure for immobilization of {sup 90}Sr-containing radioactive waste. Absence of any polymorphic transformations on the temperature dependence of its heat capacity between 7 and 665 K is caused by the stability of crystalline Sr{sub 0.5}Zr{sub 2}(PO{sub 4}){sub 3}. Calculated values of thermal conductivity coefficients at zero porosity in the range 298–673 K were 1.86–2.40 W·m{sup −1} K{sup −1}. The compound may be classified as low thermal expanding material due to its average linear thermal expansion coefficient. Study of the hydrolytic stability in acid and alkaline media has shown that the relative mass fraction of Sr{sup 2+} ions, released into aggressive leaching media, didn't exceed 1% of the mass of sample. Soxhlet leaching studies have shown substantial resistance towards the release of Sr{sup 2+} ions into distilled water. Feeble sinterability constrains practical applications of NZP substances, that is why known in literature methods of Sr{sub 0.5}Zr{sub 2}(PO{sub 4}){sub 3} dense ceramics obtaining have been reviewed. - Graphical abstract: The ability of Sr{sub 0.5}Zr{sub 2}(PO{sub 4}){sub 3} using as a perspective nuclear waste form, resistant to radiation damage, has been investigated. The obtained results highlight several concerns with application of Sr{sub 0.5}Zr{sub 2}(PO{sub 4}){sub 3} material as a host matrix, which is stable to extreme environmental condition action and able to include 90Sr radioisotope into insoluble framework structure. - Highlights: • The ability of Sr{sub 0.5}Zr{sub 2}(PO{sub 4}){sub 3} using as a nuclear waste form was investigated. • Its heat capacity, thermal expansion and thermal conductivity were studied. • Its stability in distilled water, aggressive (acid and alkaline) media was

  15. Chemical bonding and charge density distribution analysis of ...

    Indian Academy of Sciences (India)

    Ceramics; charge density; X-ray diffraction; bonding; microstructure. 1. Introduction. Ferroelectric perovskite materials are .... on Powder Diffraction Standards (JCPDS) database. (PDF# 05-0626). Existence of well-defined and ..... Li W, Xu Z, Chu R, Fu P and Hao J 2010 J. Alloy. Compd. 499 255. 9. Glinchuk M D, Bykov I P, ...

  16. Inclusion of piroxicam in mesoporous phosphate glass-ceramic and evaluation of the physiochemical characteristics.

    Science.gov (United States)

    Javadzadeh, Yousef; Bairami Atashgah, Rahimeh; Barzegar-Jalali, Mohammad; Soleimani, Farshad; Mohammadi, Ghobad; Sabzevari, Araz; Adibkia, Khosro

    2014-04-01

    The mesoporous glass-ceramic (GC) was employed as a carrier to investigate its capability for pharmaceutical applications. Piroxicam (PX) as a model drug was loaded in the GC by using of solvent evaporation technique. The physicochemical properties and morphology of the powders were evaluated employing X-ray powder diffractometry (XRPD), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The drug adsorption isotherms were assessed as well. Drug release profiles were examined by fitting the data to the 10 common kinetic models. The specific surface area, Vm (the volume of the N2 adsorbed on the 1g of the GC when the monolayer is complete) and the average pore diameter of the GC powder before and after loading process were measured by the Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analysis benefiting N2 adsorption/desorption isotherms. The ideal loading of PX in the GC was 41.8%. The average pore diameter for the GC was determined to be about 10nm. The Freundlich model was found to be the best adsorption isotherm. Decrease of the GC specific surface area and Vm values were observed after loading process. Drug release data were best fitted to the Weibull model with the shape factor of 0.4-0.7 signifying the Fickian diffusion of PX from the GC. Accordingly, the GC could be considered as a suitable adsorbent to develop an oral drug delivery system. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Zirconium phosphate waste forms for low-temperature stabilization of cesium-137-containing waste streams

    International Nuclear Information System (INIS)

    Singh, D.; Wagh, A.S.; Tlustochowicz.

    1996-04-01

    Novel chemically bonded phosphate ceramics are being developed and fabricated for low-temperature stabilization and solidification of waste streams that are not amenable to conventional high-temperature stabilization processes because volatiles are present in the wastes. A composite of zirconium-magnesium phosphate has been developed and shown to stabilize ash waste contaminated with a radioactive surrogate of 137 Cs. Excellent retainment of cesium in the phosphate matrix system was observed in Toxicity Characteristic Leaching Procedure tests. This was attributed to the capture of cesium in the layered zirconium phosphate structure by intercalation ion-exchange reaction. But because zirconium phosphate has low strength, a novel zirconium/magnesium phosphate composite waste form system was developed. The performance of these final waste forms, as indicated by compression strength and durability in aqueous environments, satisfy the regulatory criteria. Test results indicate that zirconium-magnesium-phosphate-based final waste forms present a viable technology for treatment and solidification of cesium-contaminated wastes

  18. Tailoring the surface chemical bond states of the NbN films by doping Ag: Achieving hard hydrophobic surface

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Ping; Zhang, Kan; Du, Suxuan [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, 130012 (China); Meng, Qingnan [College of Construction Engineering, Jilin University, Changchun, 130026 (China); He, Xin [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, 130012 (China); Wang, Shuo [Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Wen, Mao, E-mail: wenmao225@jlu.edu.cn [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, 130012 (China); Zheng, Weitao, E-mail: WTZheng@jlu.edu.cn [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, 130012 (China)

    2017-06-15

    Highlights: • Intrinsically hydrophilic NbN films can transfer to hydrophobic Nb-Ag-N films by doping Ag atoms into NbN sublattice. • Solute Ag can promote that the hydrophobic Ag{sub 2}O groups formed on the Nb-Ag-N film surface through self-oxidation. • The present work may provide a straightforward approach for the production of robust hydrophobic ceramic surfaces. - Abstract: Robust hydrophobic surfaces based on ceramics capable of withstanding harsh conditions such as abrasion, erosion and high temperature, are required in a broad range of applications. The metal cations with coordinative saturation or low electronegativity are commonly chosen to achieve the intrinsically hydrophobic ceramic by reducing Lewis acidity, and thus the ceramic systems are limited. In this work, we present a different picture that robust hydrophobic surface with high hardness (≥20 GPa) can be fabricated through doping Ag atoms into intrinsically hydrophilic ceramic film NbN by reactive co-sputtering. The transition of wettability from hydrophilic to hydrophobic of Nb-Ag-N films induced by Ag doping results from the appearance of Ag{sub 2}O groups on the films surfaces through self-oxidation, because Ag cations (Ag{sup +}) in Ag{sub 2}O are the filled-shell (4d{sup 10}5S{sup 0}) electronic structure with coordinative saturation that have no tendency to interact with water. The results show that surface Ag{sub 2}O benefited for hydrophobicity comes from the solute Ag atoms rather than precipitate metal Ag, in which the more Ag atoms incorporated into Nb-sublattice are able to further improve the hydrophobicity, whereas the precipitation of Ag nanoclusters would worsen it. The present work opens a window for fabricating robust hydrophobic surface through tailoring surface chemical bond states by doping Ag into transition metal nitrides.

  19. Low temperature setting iron phosphate ceramics as a stabilization and solidification agent for incinerator ash contaminated with transuranic and RCRA metals

    International Nuclear Information System (INIS)

    Medvedev, P.G.; Hansen, M.; Wood, E.L.; Frank, S.M.; Sidwell, R.W.; Giglio, J.J.; Johnson, S.G.; Macheret, J.

    1997-01-01

    Incineration of combustible Mixed Transuranic Waste yields an ash residue that contains oxides of Resource Conservation and Recovery Act (RCRA) and transuranic metals. In order to dispose of this ash safely, it has to be solidified and stabilized to satisfy appropriate requirements for repository disposal. This paper describes a new method for solidification of incinerator ash, using room temperature setting iron phosphate ceramics, and includes fabrication procedures for these waste forms as well as results of the MCC-1 static leach test, XRD analysis, scanning electron microscopy studies and density measurements of the solidified waste form produced

  20. Shear Bond Strength of MDP-Containing Self-Adhesive Resin Cement and Y-TZP Ceramics: Effect of Phosphate Monomer-Containing Primers

    Science.gov (United States)

    Ahn, Jin-Soo; Yi, Young-Ah; Lee, Yoon; Seo, Deog-Gyu

    2015-01-01

    Purpose. This study was conducted to evaluate the effects of different phosphate monomer-containing primers on the shear bond strength between yttria-tetragonal zirconia polycrystal (Y-TZP) ceramics and MDP-containing self-adhesive resin cement. Materials and Methods. Y-TZP ceramic surfaces were ground flat with #600-grit SiC paper and divided into six groups (n = 10). They were treated as follows: untreated (control), Metal/Zirconia Primer, Z-PRIME Plus, air abrasion, Metal/Zirconia Primer with air abrasion, and Z-PRIME Plus with air abrasion. MDP-containing self-adhesive resin cement was applied to the surface-treated Y-TZP specimens. After thermocycling, a shear bond strength test was performed. The surfaces of the Y-TZP specimens were analyzed under a scanning electron microscope. The bond strength values were statistically analyzed using one-way analysis of variance and the Student–Newman–Keuls multiple comparison test (P Zirconia Primer combined with air abrasion, air abrasion alone, and, lastly, Metal/Zirconia Primer application. The control group yielded the lowest results (P < 0.05). Conclusion. The application of MDP-containing primer resulted in increased bond strength between Y-TZP ceramics and MDP-containing self-adhesive resin cements. PMID:26539485

  1. Shear Bond Strength of MDP-Containing Self-Adhesive Resin Cement and Y-TZP Ceramics: Effect of Phosphate Monomer-Containing Primers.

    Science.gov (United States)

    Ahn, Jin-Soo; Yi, Young-Ah; Lee, Yoon; Seo, Deog-Gyu

    2015-01-01

    This study was conducted to evaluate the effects of different phosphate monomer-containing primers on the shear bond strength between yttria-tetragonal zirconia polycrystal (Y-TZP) ceramics and MDP-containing self-adhesive resin cement. Y-TZP ceramic surfaces were ground flat with #600-grit SiC paper and divided into six groups (n = 10). They were treated as follows: untreated (control), Metal/Zirconia Primer, Z-PRIME Plus, air abrasion, Metal/Zirconia Primer with air abrasion, and Z-PRIME Plus with air abrasion. MDP-containing self-adhesive resin cement was applied to the surface-treated Y-TZP specimens. After thermocycling, a shear bond strength test was performed. The surfaces of the Y-TZP specimens were analyzed under a scanning electron microscope. The bond strength values were statistically analyzed using one-way analysis of variance and the Student-Newman-Keuls multiple comparison test (P MDP-containing primer resulted in increased bond strength between Y-TZP ceramics and MDP-containing self-adhesive resin cements.

  2. A qualitative study of high school students' pre- and post instructional conceptions in chemical bonding

    Science.gov (United States)

    Wang, Renhong

    This study investigated high school students' understanding of chemical bonding prior to and after formal chemistry instruction. Two sets of clinical interviews were conducted prior to and after formal instructions on the topic of chemical bonding using a teacher-as-researcher protocol. Twenty-two students enrolled in a New York Regents Chemistry course were interviewed. Six students participated in the pilot study and the other sixteen were involved in the full study. Oral and pictorial data from the interviews were collected and analyzed in two parts; first, the students' conceptual understanding of chemical bonding including common themes, ideas and misconceptions were identified; second, profiles of each student were made to determine conceptual changes due to formal instruction. The findings showed that students were not familiar with the basic components and structure of atoms, especially the electrostatic properties of the sub-atomic particles. Inter-particle distance, rather than the electrostatic forces between particles, was believed to be the determining cause of the state of matter of a substance. The role of repulsive and attractive electrostatic forces in chemical bonding was not recognized. Students were unable to accurately describe the underlying scientific concepts for all types of chemical bonding and revealed a number of misconceptions, which were resistant to change by instruction. Specific areas of difficulty included the accurate descriptions of ionic bonding, covalent bonding and hydrogen bonding. Further, almost all the students could not use electrostatic forces to explain three states of water and phase changes and most students were unable to describe the energy that was released or absorbed due to bond formation or breaking. Student difficulties stemmed from a lack of understanding of some of the underlying, fundamental chemistry, such as the basic atomic structure, the particulate nature of mater and the role of electrostatic forces in

  3. Influence of cement type and ceramic primer on retention of polymer-infiltrated ceramic crowns to a one-piece zirconia implant.

    Science.gov (United States)

    Rohr, Nadja; Brunner, Stefan; Märtin, Sabrina; Fischer, Jens

    2018-01-01

    The best procedure for cementing a restoration to zirconia implants has not yet been established. The purpose of this in vitro study was to measure the retention of polymer-infiltrated ceramic crowns to zirconia 1-piece implants using a wide range of cements. The effect of ceramic primer treatment on the retention force was also recorded. The retention results were correlated with the shear bond strength of the cement to zirconia and the indirect tensile strength of the cements to better understand the retention mechanism. The retention test was performed using 100 polymer-infiltrated ceramic crowns (Vita Enamic) and zirconia implants (ceramic.implant CI) The crowns were cemented with either interim cement (Harvard Implant semipermanent, Temp Bond), glass-ionomer cement (Ketac Cem), self-adhesive cement (Perma Cem 2.0, RelyX Unicem Automix 2, Panavia SA), or adhesive cement (Multilink Implant, Multilink Automix, Vita Adiva F-Cem, RelyX Ultimate, Panavia F 2.0, Panavia V5 or Panavia 21) (n=5). Additionally ceramic primer was applied on the intaglio crown surface and implant abutment before cementation for all adhesive cements (Multilink Implant, Multilink Automix: Monobond plus; RelyX Ultimate Scotchbond Universal; Vita Adiva F-Cem: Vita Adiva Zr-Prime; Panavia F2.0, Panavia V5: Clearfil Ceramic Primer) and 1 self-adhesive cement containing 10-methacryloyloxydecyl dihydrogen phosphate (MDP) (Panavia SA: Clearfil Ceramic Primer). Crown debond fracture patterns were recorded. Shear bond strength was determined for the respective cement groups to polished zirconia (n=6). The diametral tensile strength of the cements was measured (n=10). Statistical analysis was performed using 1-way or 2-way analysis of variance followed by the Fisher LSD test (α=.05) within each test parameter. Adhesive and self-adhesive resin cements had shear bond strength values of 0.0 to 5.3 MPa and revealed similar retention forces. Cements containing MDP demonstrated shear bond strength values

  4. Representational Classroom Practices that Contribute to Students' Conceptual and Representational Understanding of Chemical Bonding

    Science.gov (United States)

    Hilton, Annette; Nichols, Kim

    2011-11-01

    Understanding bonding is fundamental to success in chemistry. A number of alternative conceptions related to chemical bonding have been reported in the literature. Research suggests that many alternative conceptions held by chemistry students result from previous teaching; if teachers are explicit in the use of representations and explain their content-specific forms and functions, this might be avoided. The development of an understanding of and ability to use multiple representations is crucial to students' understanding of chemical bonding. This paper draws on data from a larger study involving two Year 11 chemistry classes (n = 27, n = 22). It explores the contribution of explicit instruction about multiple representations to students' understanding and representation of chemical bonding. The instructional strategies were documented using audio-recordings and the teacher-researcher's reflection journal. Pre-test-post-test comparisons showed an improvement in conceptual understanding and representational competence. Analysis of the students' texts provided further evidence of the students' ability to use multiple representations to explain macroscopic phenomena on the molecular level. The findings suggest that explicit instruction about representational form and function contributes to the enhancement of representational competence and conceptual understanding of bonding in chemistry. However, the scaffolding strategies employed by the teacher play an important role in the learning process. This research has implications for professional development enhancing teachers' approaches to these aspects of instruction around chemical bonding.

  5. Microstructure and chemical bonding of DLC films deposited on ACM rubber by PACVD

    NARCIS (Netherlands)

    Martinez-Martinez, D.; Schenkel, M.; Pei, Y.T.; Sánchez-López, J.C.; Hosson, J.Th.M. De

    2011-01-01

    The microstructure and chemical bonding of DLC films prepared by plasma assisted chemical vapor deposition on acrylic rubber (ACM) are studied in this paper. The temperature variation produced by the ion impingement during plasma cleaning and subsequent film deposition was used to modify the film

  6. X-ray scattering and the chemical bond in N2 and CN

    NARCIS (Netherlands)

    Groenewegen, P.P.M.; Zeevalkink, J.; Feil, D.

    1971-01-01

    X-ray scattering from the chemical bond within N2 and CN- has been studied in detail. Differences in scattering from these systems, derived from bonding and non-bonding models, are characterized by R values of ~ 0.04. Partitioning of the scattering into core and valence electron parts clearly

  7. The Collaboration of Cooperative Learning and Conceptual Change: Enhancing the Students' Understanding of Chemical Bonding Concepts

    Science.gov (United States)

    Eymur, Gülüzar; Geban, Ömer

    2017-01-01

    The main purpose of this study was to investigate the effects of cooperative learning based on conceptual change approach instruction on ninth-grade students' understanding in chemical bonding concepts compared to traditional instruction. Seventy-two ninth-grade students from two intact chemistry classes taught by the same teacher in a public high…

  8. Anatomy of Bond Formation. Bond Length Dependence of the Extent of Electron Sharing in Chemical Bonds

    Czech Academy of Sciences Publication Activity Database

    Ponec, Robert; Cooper, D.

    2005-01-01

    Roč. 727, 1-3 (2005), s. 133-138 ISSN 0166-1280 R&D Projects: GA AV ČR(CZ) IAA4072403 Institutional research plan: CEZ:AV0Z40720504 Keywords : electron sharing * chemical bonds Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.045, year: 2005

  9. Advanced zinc phosphate conversion and pre-ceramic polymetallosiloxane coatings for corrosion protection of steel and aluminum, and characteristics of polyphenyletheretherketone-based materials. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, T.; Carciello, N.R.

    1992-07-01

    Anhydrous zinc phosphate (Zn{center_dot}Ph) coatings deposited by immersing the steel in transition Co, Ni, and Mn cation-incorporated phosphating solutions were investigated. Two features for the anhydrous 340C-heated (Zn{center_dot}Ph) were addressed; one was to determine if electron trapping of adsorbed CO{sup 2+} and Ni{sup 2+} ions acts to inhibit the cathodic reaction on the (Zn{center_dot}Ph), and the second was to determine the less susceptibility of the {alpha}-Zn{sub 3}(PO{sub 4}){sub 2} phase to alkali-induced dissolution. The factors governing film-forming of pre-ceramic polymetallosiloxane (PMS) coatings for Al substrates were investigated. Four factors were important in obtaining a good film: (1) formation of organopolymetallosiloxane at sintering temperatures of 150C; (2) pyrolytic conversion at 350C into an amorphous PMS network structure in which the Si-O-M linkage were moderately enhanced; (3) noncrystalline phases; and (4) formation of interfacial oxane bond between PMS and Al oxide. Formation of well-crystallized polyphenyletheretherketone (PEEK) in vicinity of silica aggregates was found in the molted body made in N{sub 2}. Crystalline PEEK contributed to thermal and hydrothermal stabilities of mortar specimens at temperatures up to 200C, and resistance in 5 wt % H{sub 2}SO{sub 4} solution at 80C.

  10. Laser Machining and In Vitro Assessment of Wollastonite-Tricalcium Phosphate Eutectic Glasses and Glass-Ceramics.

    Science.gov (United States)

    Sola, Daniel; Grima, Lorena

    2018-01-13

    Bioactivity and ingrowth of ceramic implants is commonly enhanced by a suitable interconnected porous network. In this work, the laser machining of CaSiO₃‒Ca₃(PO₄)₂ biocompatible eutectic glass-ceramics and glasses was studied. For this purpose, 300 µm diameter craters were machined by using pulsed laser radiation at 532 nm with a pulsewidth in the nanosecond range. Machined samples were soaked in simulated body fluid for 2 months to assess the formation of a hydroxyapatite layer on the surface of the laser machined areas. The samples were manufactured by the laser floating zone technique using a CO₂ laser. Morphology, composition and microstructure of the machined samples were described by Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy and micro-Raman Spectroscopy.

  11. Developing a New Teaching Approach for the Chemical Bonding Concept Aligned with Current Scientific and Pedagogical Knowledge

    Science.gov (United States)

    Nahum, Tami Levy; Mamlok-Naaman, Rachel; Hofstein, Avi; Krajcik, Joseph

    2007-01-01

    The traditional pedagogical approach for teaching chemical bonding is often overly simplistic and not aligned with the most up-to-date scientific models. As a result, high-school students around the world lack fundamental understanding of chemical bonding. In order to improve students' understanding of this concept, it was essential to propose a…

  12. Initial deposition of calcium phosphate ceramic on polyethylene and polydimethylsiloxane by rf magnetron sputtering deposition: the interface chemistry.

    Science.gov (United States)

    Feddes, B; Wolke, J G C; Vredenberg, A M; Jansen, J A

    2004-02-01

    Calcium phosphate (CaP) coatings are well known for their bioactive nature. CaP coated polymeric materials can be used as implant material. For this, a strong adhesion between the coating and substrate is necessary. Because the chemical structure of the interface plays an important role in the coating adhesion, we studied the interface between CaP and the polymers polyethylene (PE) and polydimethylsiloxane (PDMS/silicone rubber). Both untreated and plasma pretreated polymers were used. On PE, a low Ca/P ratio nearby the interface and a high amount of C-O bonds were found on both untreated and plasma pretreated PE. This is the result of phosphate-like groups that are able to bind to the carbon of the PE. PDMS reacts towards the plasma pretreatment by losing CH(3) side groups. Compared to PE, a low amount of C-O bonds is found nearby the interface. Besides, a low Ca/P ratio is found nearby the interface. This is the result of phosphate groups that connect to Si atoms of the PDMS, thereby replacing the CH(3) side groups. The bombardment by negatively charged oxygen ions that are accelerated from the target during the deposition process makes the chemical interaction between the coating and the substrates possible.

  13. Direct determination of the chemical bonding of individual impurities in graphene.

    Science.gov (United States)

    Zhou, Wu; Kapetanakis, Myron D; Prange, Micah P; Pantelides, Sokrates T; Pennycook, Stephen J; Idrobo, Juan-Carlos

    2012-11-16

    Using a combination of Z-contrast imaging and atomically resolved electron energy-loss spectroscopy on a scanning transmission electron microscope, we show that the chemical bonding of individual impurity atoms can be deduced experimentally. We find that when a Si atom is bonded with four atoms at a double-vacancy site in graphene, Si 3d orbitals contribute significantly to the bonding, resulting in a planar sp(2) d-like hybridization, whereas threefold coordinated Si in graphene adopts the preferred sp(3) hybridization. The conclusions are confirmed by first-principles calculations and demonstrate that chemical bonding of two-dimensional materials can now be explored at the single impurity level.

  14. Biosynthesis and characterization of layered iron phosphate

    International Nuclear Information System (INIS)

    Zhou Weijia; He Wen; Wang Meiting; Zhang Xudong; Yan Shunpu; Tian Xiuying; Sun Xianan; Han Xiuxiu; Li Peng

    2008-01-01

    Layered iron phosphate with uniform morphology has been synthesized by a precipitation method with yeast cells as a biosurfactant. The yeast cells are used to regulate the nucleation and growth of layered iron phosphate. The uniform layered structure is characterized by small-angle x-ray diffraction (SAXD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses. Fourier transform infrared spectroscopy (FT-IR) is used to analyze the chemical bond linkages in organic–inorganic hybrid iron phosphate. The likely synthetic mechanism of nucleation and oriented growth is discussed. The electrical conductivity of hybrid iron phosphate heat-treated at different temperatures is presented

  15. Comparison of Hypersensitivity in Metal Ceramic Crowns cemented with Zinc Phosphate and Self-adhesive Resin: A Prospective Study.

    Science.gov (United States)

    Shankar, Thatapudi; Garhnayak, Mirna; Garhnayak, Lokanath; Dhal, Angurbala; Kar, Aswini K

    2017-10-01

    Luting agents used to fix artificial prostheses, such as fixed partial denture (FPD) to tooth are basically viscous in nature and show chemical reaction for fixation. Postcementation hypersensitivity is a frequent complaint of patients. The present study was conducted to compare postcementation hypersensitivity with zinc phosphate and self-adhesive resin in complete coverage crown. This study included 30 patients in which 60 porcelein fused to metal crowns was placed. Two metal crowns were placed in each patient in nonantagonis-tic contralateral quadrants. First crown was cemented with zinc phosphate cement, while the other was cemented with self-adhesive resin. Hypersensitivity was evaluated by visual analog scale (VAS) score and by clinical test. For clinical evaluation of sensitivity, hot and cold water was applied to the cervical margin of restoration for 5 seconds and response was recorded. This study consisted of 30 patients in which 60 crowns were given. There was no statistical difference in VAS score of mastication in zinc phosphate cement recorded at baseline, 1 week, 4 weeks, 6 months, 1 year, and 2 years (p > 0.05). Cold response also did not show a significant difference at six time points. Warm response showed slight decrease in subsequent time points but was nonsignificant (p > 0.05). Similarly, with self-adhesive resin cement, VAS score during mastication, hot and cold response was statistically nonsignificant (p > 0.05). Postcementation hypersensitivity is a frequent complaint that patient may experience. However, we found no statistically significant difference in both cements tested. Postcementation hypersensitivity is an unpleasant sensation experienced by patients. This may affect the success of any prosthesis. Thus, selection of luting agent for cementation plays an important role to eliminate this symptom.

  16. Fiber-reinforced ceramics for thermostructural applications, produced by polymer impregnation pyrolysis

    OpenAIRE

    Mingazzini, Claudio

    2014-01-01

    Several CFCC (Continuous Fiber Composite Ceramics) production processes were tested, concluding that PIP (Polymer Impregnation, or Infiltration, Pyrolysis) and CBC (Chemically Bonded Ceramics) based procedures have interesting potential applications in the construction and transportation fields, thanks to low costs to get potentially useful thermomechanical performances. Among the different processes considered during the Doctorate (from the synthesis of new preceramic polymers, to the PIP...

  17. Effects of Hot Chemical Etching and 10-Metacryloxydecyl Dihydrogen Phosphate (MDP) Monomer on the Bond Strength of Zirconia Ceramics to Resin-Based Cements.

    Science.gov (United States)

    Akay, Canan; Çakırbay Tanış, Merve; Şen, Murat

    2017-07-01

    The purpose of this in vitro study was to evaluate the hot chemical etching method on the shear bond strength between zirconia and two resin cements. Sixty zirconia specimens (13 × 7.5 × 2.5 mm 3 ) were prepared and treated as follows: (1) airborne-particle abrasion with 50 μm Al 2 O 3 particles; (2) hot chemical etching for 10 minutes; (3) hot chemical etching for 30 minutes. Sixty composite cylinders of 3 mm diameter and height were prepared and bonded to zirconia specimens, which were divided into subgroups A and B. Group A: cemented with conventional resin cement (Variolink II); group B: cemented with 10-metacryloxydecyl dihydrogen phosphate (MDP) monomer containing resin cement (Panavia SA) after the application of surface treatments. Next, the specimens were stored in 37ºC distilled water for 24 hours. Following water storage, shear bond strength test was performed at a 1 mm/min crosshead speed in a universal testing machine. The statistical analyses were performed with one-way ANOVA and post hoc Tukey tests. p MDP monomer-containing resin cement, Panavia SA, improved the resin bonding of zirconia ceramics when combined with airborne-particle abrasion. © 2016 by the American College of Prosthodontists.

  18. Effect of apatite formation of biphasic calcium phosphate ceramic (BCP) on osteoblastogenesis using simulated body fluid (SBF) with or without bovine serum albumin (BSA).

    Science.gov (United States)

    Huang, Li; Zhou, Bo; Wu, Huayu; Zheng, Li; Zhao, Jinmin

    2017-01-01

    Although biphasic calcium phosphate ceramic (BCP) holds promise in therapy of bone defect, surface mineralization prior to implantation may improve the bioactivity to better integrate with the host. Immersion in simulated body fluid (SBF) and bovine serum albumin-simulated body fluid (BSA-SBF) are common methods to form apatite interface layer. This study was intended to investigate the effect of SBF and BSA-SBF treatment on the bioactivity of BCP in vitro. In this study, osteoblasts were grown on BCP with or without treatment of SBF or BSA-SBF, and detected with general observation, scanning electron microscope (SEM), cell proliferation assay, morphology observation, viability assay, alkaline phosphatase (ALP) activity assay, and osteogenic specific gene expression of alkaline phosphatase (ALPL), bone gamma-carboxyglutamate (gla) protein (BGLAP), bone morphogenetic protein 2 (BMP2), bone sialoprotein (BSP), type I collagen (COLI) and runt-related transcription factor 2 (RUNX2) after culture of 2, 5 and 8days. As the results shown, BCP pre-incubated in SBF and BSA-SBF up-regulated ALP activity and osteogenic related genes and proteins, which testified the positive effect of SBF and BSA-SBF. Especially, BSA-SBF enhanced the cell growth significantly. This study indicated that treatment by BSA-SBF is of importance for BCP before clinical application. Copyright © 2016. Published by Elsevier B.V.

  19. Study of chemical bond strength of methyl methacrylate (MMA based bonding agent on type I dentin collagen at various humidity

    Directory of Open Access Journals (Sweden)

    Adioro Soetojo

    2007-06-01

    Full Text Available One of the basic agents used in dentin bonding solution is methyl methacrylate (MMA. This bonding agent is widely used in dentistry. It have been proved that the adhesion between dentin bonding agent and collagen fibril is chemically bond; though the chemical bonding contribution is smaller than physical mechanical bond. The purpose of the research was to examined the chemical bonding strength of MMA based dentin bonding on type I dentin collagen at various humidity. Samples of treatment group were put into desiccator with 60%, 70%, 80%, and 90% humidity, while for control groups at room humidity (65%. Chemical bond of pure MMA and MMA mixed with collagen were measured by FTIR. The lower the value of MMA carbonyl, the higher absorbance band speak of chemical bond strength between MMA and collagen. Data was statistically analyzed with One-Way ANOVA at 95% confidence level continued with Tukey-HSD test. The result showed that the highest chemical bond strength was at 65% humidity (p ≤ 0.05. In conclusion, many esther carbonyl MMA molecules reacted with amino collagen at 65% humidity. This can be shown by the lowest peak's value of the MMA carbonyl absorbance at FTIR.

  20. The use of dialogic electronic journal writing to develop students' understanding of chemical bonding

    Science.gov (United States)

    English, Sarah Collard

    The intent of this study is to examine how the implementation of a dialogic electronic journal writing environment continues the development of students' understanding of chemistry, specifically chemical bonding, through written communication between the individual students and their chemistry teacher. This study is framed within a constructivist theoretical context where students' understanding is constructed through written discussions with the educator, the students' interaction with the classroom environment, and his/her interaction with the computer environment. The research design of collective case study was employed to allow multiple perspectives and processes conveyed by the participants to be examined in the context in which they occurred while considering multiple sources of information. Data sources included electronic journal entries, classroom artifacts, and semi-structured interviews. Data were analyzed using the constant comparative method, which involved coding, categorizing, and interpreting for patterns and relationships. Four cases were reported in detail. This study found that the dialogic electronic journal-writing environment was an effective venue in revealing previously undiscovered students' alternative conceptions of chemical bonding. Opportunities to actively confront and reconcile such conceptions were afforded through educator/student dialogic written interaction. The dialogic electronic journal-writing environment was also critical in the identification of gaps in students' conceptual understanding linked to improper sequencing of chemistry content. This study also found that the on-line environment provided the educator the opportunity to scaffold chemical bonding concepts to meet the needs of the students involved in the study. This study concluded that the dialogic electronic journal-writing environment positively contributed to the development of student understanding. These findings may have practical implications for teachers in

  1. Effect of conditioning methods on the microtensile bond strength of phosphate monomer-based cement on zirconia ceramic in dry and aged conditions

    NARCIS (Netherlands)

    Amaral, Regina; Ozcan, Mutlu; Valandro, Luiz Felipe; Balducci, Ivan; Bottino, Marco Antonio

    The objective of this study was to evaluate the durability of bond strength between a resin cement and aluminous ceramic submitted to various surface conditioning methods. Twenty-four blocks (5 X 5 X 4 mm 3) of a glass-in filtrated zirconia-alumina ceramic (inCeram Zirconia Classic) were randomly

  2. The role of the 5f valence orbitals of early actinides in chemical bonding

    Science.gov (United States)

    Vitova, T.; Pidchenko, I.; Fellhauer, D.; Bagus, P. S.; Joly, Y.; Pruessmann, T.; Bahl, S.; Gonzalez-Robles, E.; Rothe, J.; Altmaier, M.; Denecke, M. A.; Geckeis, H.

    2017-01-01

    One of the long standing debates in actinide chemistry is the level of localization and participation of the actinide 5f valence orbitals in covalent bonds across the actinide series. Here we illuminate the role of the 5f valence orbitals of uranium, neptunium and plutonium in chemical bonding using advanced spectroscopies: actinide M4,5 HR-XANES and 3d4f RIXS. Results reveal that the 5f orbitals are active in the chemical bonding for uranium and neptunium, shown by significant variations in the level of their localization evidenced in the spectra. In contrast, the 5f orbitals of plutonium appear localized and surprisingly insensitive to different bonding environments. We envisage that this report of using relative energy differences between the 5fδ/ϕ and 5fπ*/5fσ* orbitals as a qualitative measure of overlap-driven actinyl bond covalency will spark activity, and extend to numerous applications of RIXS and HR-XANES to gain new insights into the electronic structures of the actinide elements. PMID:28681848

  3. Chemical Bonding, Interfaces and Defects in Hafnium Oxide/Germanium Oxynitride Gate Stacks on Ge (100)

    Energy Technology Data Exchange (ETDEWEB)

    Oshima, Yasuhiro; /Stanford U., Materials Sci. Dept.; Sun, Yun; /SLAC, SSRL; Kuzum, Duygu; /Stanford U.; Sugawara, Takuya; Saraswat, Krishna C.; Pianetta, Piero; /SLAC, SSRL; McIntyre, Paul C.; /Stanford U., Materials Sci. Dept.

    2008-10-31

    Correlations among interface properties and chemical bonding characteristics in HfO{sub 2}/GeO{sub x}N{sub y}/Ge MIS stacks were investigated using in-situ remote nitridation of the Ge (100) surface prior to HfO{sub 2} atomic layer deposition (ALD). Ultra thin ({approx}1.1 nm), thermally stable and aqueous etch-resistant GeO{sub x}N{sub y} interfaces layers that exhibited Ge core level photoelectron spectra (PES) similar to stoichiometric Ge{sub 3}N{sub 4} were synthesized. To evaluate GeO{sub x}N{sub y}/Ge interface defects, the density of interface states (D{sub it}) was extracted by the conductance method across the band gap. Forming gas annealed (FGA) samples exhibited substantially lower D{sub it} ({approx} 1 x 10{sup 12} cm{sup -2} eV{sup -1}) than did high vacuum annealed (HVA) and inert gas anneal (IGA) samples ({approx} 1x 10{sup 13} cm{sup -2} eV{sup -1}). Germanium core level photoelectron spectra from similar FGA-treated samples detected out-diffusion of germanium oxide to the HfO{sub 2} film surface and apparent modification of chemical bonding at the GeO{sub x}N{sub y}/Ge interface, which is related to the reduced D{sub it}.

  4. Electronic structure and chemical bonding in LaIrSi-type intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Matar, Samir F. [Bordeaux Univ., Pessac (France). CNRS; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Nakhl, Michel [Univ. Libanaise, Fanar (Lebanon). Ecole Doctorale Sciences et Technologies

    2017-05-01

    The cubic LaIrSi type has 23 representatives in aluminides, gallides, silicides, germanides, phosphides, and arsenides, all with a valence electron count of 16 or 17. The striking structural motif is a three-dimensional network of the transition metal (T) and p element (X) atoms with TX{sub 3/3} respectively XT{sub 3/3} coordination. Alkaline earth or rare earth atoms fill cavities within the polyanionic [TX]{sup δ-} networks. The present work presents a detailed theoretical study of chemical bonding in LaIrSi-type representatives, exemplarily for CaPtSi, BaIrP, BaAuGa, LaIrSi, CeRhSi, and CeIrSi. DFT-GGA-based electronic structure calculations show weakly metallic compounds with itinerant small magnitude DOSs at E{sub F} except for CeRhSi whose large Ce DOS at E{sub F} leads to a finite magnetization on Ce (0.73 μ{sub B}) and induced small moments of opposite sign on Rh and Si in a ferromagnetic ground state. The chemical bonding analyses show dominant bonding within the [TX]{sup δ-} polyanionic networks. Charge transfer magnitudes were found in accordance with the course of the electronegativites of the chemical constituents.

  5. Repair of Cranial Bone Defects Using rhBMP2 and Submicron Particle of Biphasic Calcium Phosphate Ceramics with Through-Hole

    Directory of Open Access Journals (Sweden)

    Byung-Chul Jeong

    2015-01-01

    Full Text Available Recently a submicron particle of biphasic calcium phosphate ceramic (BCP with through-hole (donut-shaped BCP (d-BCP was developed for improving the osteoconductivity. This study was performed to examine the usefulness of d-BCP for the delivery of osteoinductive rhBMP2 and the effectiveness on cranial bone regeneration. The d-BCP was soaked in rhBMP2 solution and then freeze-dried. Scanning electron microscope (SEM, energy dispersive spectroscopy (EDS, and Raman spectroscopy analyses confirmed that rhBMP2 was well delivered onto the d-BCP surface and the through-hole. The bioactivity of the rhBMP2/d-BCP composite was validated in MC3T3-E1 cells as an in vitro model and in critical-sized cranial defects in C57BL/6 mice. When freeze-dried d-BCPs with rhBMP2 were placed in transwell inserts and suspended above MC3T3-E1, alkaline phosphatase activity and osteoblast-specific gene expression were increased compared to non-rhBMP2-containing d-BCPs. For evaluating in vivo effectiveness, freeze-dried d-BCPs with or without rhBMP2 were implanted into critical-sized cranial defects. Microcomputed tomography and histologic analysis showed that rhBMP2-containing d-BCPs significantly enhanced cranial bone regeneration compared to non-rhBMP2-containing control. These results suggest that a combination of d-BCP and rhBMP2 can accelerate bone regeneration, and this could be used to develop therapeutic strategies in hard tissue healing.

  6. Influence of saline solution on hydration behavior of β-dicalcium silicate in comparison with biphasic calcium phosphate/hydroxyapatite bio-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Radwan, M.M., E-mail: mmahmoudradwan@yahoo.com [Ceramics Dept, National Research Centre, Cairo (Egypt); Abd El-Hamid, H.K. [Ceramics Dept, National Research Centre, Cairo (Egypt); Mohamed, A.F. [The Holding Company for Production of Vaccines, Sera and Drugs (EGYVAC) (Egypt)

    2015-12-01

    The influence of using saline solution as mixing and curing liquid on some characteristics of β-dicalcium silicate (β-C{sub 2}S) and biphasic compound tri-calcium phosphate/hydroxyapatite (TCP/HAp) bio-ceramics was investigated. β-C{sub 2}S (27–30 nm) was prepared by solid state reaction at 1450 °C, while biphasic compound TCP/HAp (7–15 nm) was synthesized from an aqueous solution of Ca(NO{sub 3}){sub 2}·4H{sub 2}O and (NH{sub 4}){sub 2}HPO{sub 4}·12H{sub 2}O by chemical precipitation method. Setting times, compressive strength, pH values, X-ray diffraction analysis, infrared spectroscopy, scanning electron microscopy (SEM) were investigated. The evaluation of cytotoxicity of both calcium silicate and biphasic compounds to human gingival fibroblasts was carried out. The use of saline solution as mixing and immersing liquid shortened the setting time for the two bio-cements. TCP/HAp did not show any mechanical strength but β-C{sub 2}S showed good strength values. Both synthesized compounds showed a moderate cytotoxicity and both materials were effective in a no significant way. - Highlights: • The dissolution and hydration of β-C{sub 2}S and TCP/HAp in distilled water and saline solution were studied. • TCP/HAp did not show mechanical strength, while β-C{sub 2}S showed good mechanical strength. • The use of saline solution did enhances the dissolution & hydration rate. • An increase in pH values was detected when using saline solution. • Both materials showed a moderate cytotoxicity in no significant way.

  7. Novel resorbable glass-ceramic scaffolds for hard tissue engineering: from the parent phosphate glass to its bone-like macroporous derivatives.

    Science.gov (United States)

    Bretcanu, Oana; Baino, Francesco; Verné, Enrica; Vitale-Brovarone, Chiara

    2014-05-01

    One of the major challenges of hard tissue engineering research focuses on the development of scaffolds that can match the mechanical properties of the host bone and resorb at the same rate as the bone is repaired. The aim of this work was the synthesis and characterization of a resorbable phosphate glass, as well as its application for the fabrication of three dimensional (3-D) scaffolds for bone regeneration. The glass microstructure and behaviour upon heating were analysed by X-ray diffraction, differential scanning calorimetry and hot stage microscopy. The glass solubility was investigated according to relevant ISO standards using distilled water, simulated body fluid (SBF) and Tris-HCl as testing media. The glass underwent progressive dissolution over time in all three media but the formation of a hydroxyapatite-like layer was also observed on the samples soaked in SBF and Tris-HCl, which demonstrated the bioactivity of the material. The glass powder was used to fabricate 3-D macroporous bone-like glass-ceramic scaffolds by adopting polyethylene particles as pore formers: during thermal treatment, the polymer additive was removed and the sintering of glass particles was allowed. The obtained scaffolds exhibited high porosity (87 vol.%) and compressive strength around 1.5 MPa. After soaking for 4 months in SBF, the scaffolds mass loss was 76 wt.% and the pH of the solution did not exceed the 7.55 value, thereby remaining in a physiological range. The produced scaffolds, being resorbable, bioactive, architecturally similar to trabecular bone and exhibiting interesting mechanical properties, can be proposed as promising candidates for bone repair applications.

  8. Theoretical study of relativistic effects in the electronic structure and chemical bonding of UF6

    International Nuclear Information System (INIS)

    Onoe, Jun; Takeuchi, Kazuo; Sekine, Rika; Nakamatsu, Hirohide; Mukoyama, Takeshi; Adachi, Hirohiko.

    1992-01-01

    We have performed the relativistic molecular orbital calculation for the ground state of UF 6 , using the discrete-variational Dirac-Slater method (DV-DS), in order to elucidate the relativistic effects in the electronic structure and chemical bonding. Compared with the electronic structure calculated by the non-relativistic Hartree-Fock-Slater (DV-X α )MO method, not only the direct relativistic effects (spin-orbit splitting etc), but also the indirect effect due to the change in screening core potential charge are shown to be important in the MO level structure. From the U-F bond overlap population analysis, we found that the U-F bond formation can be explained only by the DV-DS, not by the DV-X α . The calculated electronic structure in valence energy region (-20-OeV) and excitation energies in UV region are in agreement with experiments. (author)

  9. The role of radial nodes of atomic orbitals for chemical bonding and the periodic table.

    Science.gov (United States)

    Kaupp, Martin

    2007-01-15

    The role of radial nodes, or of their absence, in valence orbitals for chemical bonding and periodic trends is discussed from a unified viewpoint. In particular, we emphasize the special role of the absence of a radial node whenever a shell with angular quantum number l is occupied for the first time (lack of "primogenic repulsion"), as with the 1s, 2p, 3d, and 4f shells. Although the consequences of the very compact 2p shell (e.g. good isovalent hybridization, multiple bonding, high electronegativity, lone-pair repulsion, octet rule) are relatively well known, it seems that some of the aspects of the very compact 3d shell in transition-metal chemistry are less well appreciated, e.g., the often weakened and stretched bonds at equilibrium structure, the frequently colored complexes, and the importance of nondynamical electron-correlation effects in bonding. Copyright (c) 2006 Wiley Periodicals, Inc.

  10. Formation of aromatics in thermally induced reactions of chemically bonded RP-C18 stationary phase.

    Science.gov (United States)

    Prus, Wojciech

    2014-10-01

    In continuation of the research on the thermally induced chemical transformation of the silica-based chemically bonded stationary phases (C18), the oxidative cleavage of the silicon-carbon bonds with hydrogen peroxide and potassium fluoride was utilized, followed by the gas chromatography coupled with mass spectrometry (GC-MS) study of the resulting products. These investigations allowed determination of the probable structures of certain thermal modification products as the various different alkyl derivatives of the phenylsilane ligands. Apart from aromatic compounds, the products with unsaturated bonds and carbonyl functionalities were found in the analyzed extracts. The analysis of the GC-MS chromatograms reveals that under the applied working conditions, the investigated process runs with relatively low yields. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. YNi and its hydrides: Phase stabilities, electronic structures and chemical bonding properties from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Matar, S.F., E-mail: matar@icmcb-bordeaux.cnrs.fr [CNRS, Universite de Bordeaux, ICMCB, 87 avenue du Docteur Albert Schweitzer, F-33608 Pessac (France); Nakhl, M. [Universite Libanaise, Laboratoire de Chimie-Physique des Materiaux LCPM, Fanar (Lebanon); Al Alam, A.F.; Ouaini, N. [Universite Saint-Esprit de Kaslik, Faculte des Sciences et de Genie Informatique, Jounieh (Lebanon); Chevalier, B. [CNRS, Universite de Bordeaux, ICMCB, 87 avenue du Docteur Albert Schweitzer, F-33608 Pessac (France)

    2010-11-25

    Graphical abstract: Base centered orthorhombic YNiH{sub X} structure. For x = 3, only H1 and H2 are present. Highest hydrogen content YNiH{sub 4} is obtained when H3 are added. - Abstract: Within density functional theory, establishing the equations of states of YNi in two different controversial structures in the literature, leads to determine the orthorhombic FeB-type as the ground state one with small energy difference. For YNiH{sub 3} and YNiH{sub 4} hydrides crystallizing in the orthorhombic CrB-type structure the geometry optimization and the ab initio determination of the H atomic positions show that the stability of hydrogen decreases from the tri- to the tetra- hydride. New states brought by hydrogen within the valence band lead to its broadening and to enhanced localization of metal density of states. The chemical bonding analysis shows a preferential Ni-H bonding versus Y-H.

  12. Core level photoemission spectroscopy and chemical bonding in Sr2Ta2O7

    DEFF Research Database (Denmark)

    Atuchin, V. V.; Grivel, Jean-Claude; Zhang, Z. M.

    2009-01-01

    Electronic parameters of constituent element core levels of strontium pyrotantalate (Sr2Ta2O7) were measured with X-ray photoelectron spectroscopy (XPS). The Sr2Ta2O7 powder sample was synthesized using standard solid state method. The valence electron transfer on the formation of the Sr-O and Ta......-O bonds was characterized by the binding energy differences between the O 1s and cation core levels, Delta(O-Sr) = BE(O 1s) - BE(Sr 3d(5/2)) and Delta(O-Ta) = BE(O 1s) - BE(Ta 4f(7/2)). The chemical bonding effects were considered on the basis of our XPS results for Sr2Ta2O7 and earlier published...

  13. Atom-specific look at the surface chemical bond using x-ray emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, A.; Wassdahl, N.; Weinelt, M. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    CO and N{sub 2} adsorbed on the late transition metals have become prototype systems regarding the general understanding of molecular adsorption. It is in general assumed that the bonding of molecules to transition metals can be explained in terms of the interaction of the frontier HOMO and LUMO molecular orbitals with the d-orbitals. In such a picture the other molecular orbitals should remain essentially the same as in the free molecule. For the adsorption of the isoelectronic molecules CO and N{sub 2} this has led to the so called Blyholder model i.e., a synergetic {sigma} (HOMO) donor and {pi} (LUMO) backdonation bond. The authors results at the ALS show that such a picture is oversimplified. The direct observation and identification of the states related to the surface chemical bond is an experimental challenge. For noble and transition metal surfaces, the adsorption induced states overlap with the metal d valence band. Their signature is therefore often obscured by bulk substrate states. This complication has made it difficult for techniques such as photoemission and inverse photoemission to provide reliable information on the energy of chemisorption induced states and has left questions unanswered regarding the validity of the frontier orbitals concept. Here the authors show how x-ray emission spectroscopy (XES), in spite of its inherent bulk sensitivity, can be used to investigate adsorbed molecules. Due to the localization of the core-excited intermediate state, XE spectroscopy allows an atomic specific separation of the valence electronic states. Thus the molecular contributions to the surface measurements make it possible to determine the symmetry of the molecular states, i.e., the separation of {pi} and {sigma} type states. In all the authors can obtain an atomic view of the electronic states involved in the formation of the chemical bond to the surface.

  14. Electronic structure and chemical bonding anisotropy investigation of wurtzite AlN

    Science.gov (United States)

    Magnuson, M.; Mattesini, M.; Höglund, C.; Birch, J.; Hultman, L.

    2009-10-01

    The electronic structure and the anisotropy of the AlN π and σ chemical bonding of wurtzite AlN has been investigated by bulk-sensitive total fluorescence yield absorption and soft x-ray emission spectroscopies. The measured NK , AlL1 , and AlL2,3 x-ray emission and N1s x-ray absorption spectra are compared with calculated spectra using first-principles density-functional theory including dipole transition matrix elements. The main N2p-Al3p-Al 3d and N2p-Al3s hyridization regions are identified at -1.0 to -1.8eV and -5.0 to -5.5eV below the top of the valence band, respectively. In addition, N2s-Al3p and N2s-Al3s hybridization regions are found at the bottom of the valence band around -13.5 and -15eV , respectively. A strongly modified spectral shape of Al3s states in the AlL2,3 emission from AlN in comparison to Al metal is found, which is also reflected in the N2p-Al3p hybridization observed in the AlL1 emission. The differences between the electronic structure and chemical bonding of AlN and Al metal are discussed in relation to the position of the hybridization regions and the valence-band edge influencing the magnitude of the large band gap.

  15. Autologous platelet-rich plasma induces bone formation of tissue-engineered bone with bone marrow mesenchymal stem cells on beta-tricalcium phosphate ceramics.

    Science.gov (United States)

    Yu, Tengbo; Pan, Huazheng; Hu, Yanling; Tao, Hao; Wang, Kai; Zhang, Chengdong

    2017-11-21

    The purpose of the study is to investigate whether autologous platelet-rich plasma (PRP) can serve as bone-inducing factors to provide osteoinduction and improve bone regeneration for tissue-engineered bones fabricated with bone marrow mesenchymal stem cells (MSCs) and beta-tricalcium phosphate (β-TCP) ceramics. The current study will give more insight into the contradictory osteogenic capacity of PRP. The concentration of platelets, platelet-derived growth factor-AB (PDGF-AB), and transforming growth factor-β1 (TGF-β1) were measured in PRP and whole blood. Tissue-engineered bones using MSCs on β-TCP scaffolds in combination with autologous PRP were fabricated (PRP group). Controls were established without the use of autologous PRP (non-PRP group). In vitro, the proliferation and osteogenic differentiation of MSCs on fabricated constructs from six rabbits were evaluated with MTT assay, alkaline phosphatase (ALP) activity, and osteocalcin (OC) content measurement after 1, 7, and 14 days of culture. For in vivo study, the segmental defects of radial diaphyses of 12 rabbits from each group were repaired by fabricated constructs. Bone-forming capacity of the implanted constructs was determined by radiographic and histological analysis at 4 and 8 weeks postoperatively. PRP produced significantly higher concentration of platelets, PDGF-AB, and TGF-β1 than whole blood. In vitro study, MTT assay demonstrated that the MSCs in the presence of autologous PRP exhibited excellent proliferation at each time point. The results of osteogenic capacity detection showed significantly higher levels of synthesis of ALP and OC by the MSCs in combination with autologous PRP after 7 and 14 days of culture. In vivo study, radiographic observation showed that the PRP group produced significantly higher score than the non-PRP group at each time point. For histological evaluation, significantly higher volume of regenerated bone was found in the PRP group when compared with the non

  16. Valence XPS structure and chemical bond in Cs2UO2Cl4

    Directory of Open Access Journals (Sweden)

    Teterin Yury A.

    2016-01-01

    Full Text Available Quantitative analysis was done of the valence electrons X-ray photoelectron spectra structure in the binding energy (BE range of 0 eV to ~35 eV for crystalline dicaesium tetrachloro-dioxouranium (VI (Cs2UO2Cl4. This compound contains the uranyl group UO2. The BE and structure of the core electronic shells (~35 eV-1250 eV, as well as the relativistic discrete variation calculation results for the UO2Cl4(D4h cluster reflecting U close environment in Cs2UO2Cl4 were taken into account. The experimental data show that many-body effects due to the presence of cesium and chlorine contribute to the outer valence (0-~15 eV BE spectral structure much less than to the inner valence (~15 eV-~35 eV BE one. The filled U5f electronic states were theoretically calculated and experimentally confirmed to be present in the valence band of Cs2UO2Cl4. It corroborates the suggestion on the direct participation of the U5f electrons in the chemical bond. Electrons of the U6p atomic orbitals participate in formation of both the inner (IVMO and the outer (OVMO valence molecular orbitals (bands. The filled U6p and the O2s, Cl3s electronic shells were found to make the largest contributions to the IVMO formation. The molecular orbitals composition and the sequence order in the binding energy range 0 eV-~35 eV in the UO2Cl4 cluster were established. The experimental and theoretical data allowed a quantitative molecular orbitals scheme for the UO2Cl4 cluster in the BE range 0-~35 eV, which is fundamental for both understanding the chemical bond nature in Cs2UO2Cl4 and the interpretation of other X-ray spectra of Cs2UO2Cl4. The contributions to the chemical binding for the UO2Cl4 cluster were evaluated to be: the OVMO contribution - 76%, and the IVMO contribution - 24 %.

  17. The active site of hen egg-white lysozyme: flexibility and chemical bonding

    International Nuclear Information System (INIS)

    Held, Jeanette; Smaalen, Sander van

    2014-01-01

    Chemical bonding at the active site of lysozyme is analyzed on the basis of a multipole model employing transferable multipole parameters from a database. Large B factors at low temperatures reflect frozen-in disorder, but therefore prevent a meaningful free refinement of multipole parameters. Chemical bonding at the active site of hen egg-white lysozyme (HEWL) is analyzed on the basis of Bader’s quantum theory of atoms in molecules [QTAIM; Bader (1994 ▶), Atoms in Molecules: A Quantum Theory. Oxford University Press] applied to electron-density maps derived from a multipole model. The observation is made that the atomic displacement parameters (ADPs) of HEWL at a temperature of 100 K are larger than ADPs in crystals of small biological molecules at 298 K. This feature shows that the ADPs in the cold crystals of HEWL reflect frozen-in disorder rather than thermal vibrations of the atoms. Directly generalizing the results of multipole studies on small-molecule crystals, the important consequence for electron-density analysis of protein crystals is that multipole parameters cannot be independently varied in a meaningful way in structure refinements. Instead, a multipole model for HEWL has been developed by refinement of atomic coordinates and ADPs against the X-ray diffraction data of Wang and coworkers [Wang et al. (2007), Acta Cryst. D63, 1254–1268], while multipole parameters were fixed to the values for transferable multipole parameters from the ELMAM2 database [Domagala et al. (2012), Acta Cryst. A68, 337–351] . Static and dynamic electron densities based on this multipole model are presented. Analysis of their topological properties according to the QTAIM shows that the covalent bonds possess similar properties to the covalent bonds of small molecules. Hydrogen bonds of intermediate strength are identified for the Glu35 and Asp52 residues, which are considered to be essential parts of the active site of HEWL. Furthermore, a series of weak C

  18. The active site of hen egg-white lysozyme: flexibility and chemical bonding

    Energy Technology Data Exchange (ETDEWEB)

    Held, Jeanette, E-mail: jeanette.netzel@uni-bayreuth.de; Smaalen, Sander van [University of Bayreuth, D-95440 Bayreuth (Germany)

    2014-04-01

    Chemical bonding at the active site of lysozyme is analyzed on the basis of a multipole model employing transferable multipole parameters from a database. Large B factors at low temperatures reflect frozen-in disorder, but therefore prevent a meaningful free refinement of multipole parameters. Chemical bonding at the active site of hen egg-white lysozyme (HEWL) is analyzed on the basis of Bader’s quantum theory of atoms in molecules [QTAIM; Bader (1994 ▶), Atoms in Molecules: A Quantum Theory. Oxford University Press] applied to electron-density maps derived from a multipole model. The observation is made that the atomic displacement parameters (ADPs) of HEWL at a temperature of 100 K are larger than ADPs in crystals of small biological molecules at 298 K. This feature shows that the ADPs in the cold crystals of HEWL reflect frozen-in disorder rather than thermal vibrations of the atoms. Directly generalizing the results of multipole studies on small-molecule crystals, the important consequence for electron-density analysis of protein crystals is that multipole parameters cannot be independently varied in a meaningful way in structure refinements. Instead, a multipole model for HEWL has been developed by refinement of atomic coordinates and ADPs against the X-ray diffraction data of Wang and coworkers [Wang et al. (2007), Acta Cryst. D63, 1254–1268], while multipole parameters were fixed to the values for transferable multipole parameters from the ELMAM2 database [Domagala et al. (2012), Acta Cryst. A68, 337–351] . Static and dynamic electron densities based on this multipole model are presented. Analysis of their topological properties according to the QTAIM shows that the covalent bonds possess similar properties to the covalent bonds of small molecules. Hydrogen bonds of intermediate strength are identified for the Glu35 and Asp52 residues, which are considered to be essential parts of the active site of HEWL. Furthermore, a series of weak C

  19. Trigermanides AEGe{sub 3} (AE = Ca, Sr, Ba). Chemical bonding and superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, Rodrigo; Schnelle, Walter; Baranov, Alexey I.; Burkhardt, Ulrich; Bobnar, Matej; Cardoso-Gil, Raul; Schwarz, Ulrich; Grin, Yuri [Max-Planck-Institut fuer Chemische Physik Fester Stoffe, Dresden (Germany)

    2016-08-01

    The crystal structures of the trigermanides AEGe{sub 3}(tI32) (AE = Ca, Sr, Ba; space group I4/mmm, for SrGe{sub 3}: a = 7.7873(1), c = 12.0622(3) Aa) comprise Ge{sub 2} dumbbells forming layered Ge substructures which enclose embedded AE atoms. The chemical bonding analysis by application of the electron localizability approach reveals a substantial charge transfer from the AE atoms to the germanium substructure. The bonding within the dumbbells is of the covalent two-center type. A detailed analysis of SrGe{sub 3} reveals that the interaction on the bond-opposite side of the Ge{sub 2} groups is not lone pair-like - as it would be expected from the Zintl-like interpretation of the crystal structure with anionic Ge layers separated by alkaline-earth cations - but multi-center strongly polar between the Ge{sub 2} dumbbells and the adjacent metal atoms. Similar atomic interactions are present in CaGe{sub 3} and BaGe{sub 3}. The variation of the alkaline-earth metal has a merely insignificant influence on the superconducting transition temperatures in the s,p-electron compounds AEGe{sub 3}.

  20. DFT modeling of the electronic and magnetic structures and chemical bonding properties of intermetallic hydrides

    International Nuclear Information System (INIS)

    Al Alam, A.F.

    2009-06-01

    This thesis presents an ab initio study of several classes of intermetallics and their hydrides. These compounds are interesting from both a fundamental and an applied points of view. To achieve this aim two complementary methods, constructed within the DFT, were chosen: (i) pseudo potential based VASP for geometry optimization, structural investigations and electron localization mapping (ELF), and (ii) all-electrons ASW method for a detailed description of the electronic structure, chemical bonding properties following different schemes as well as quantities depending on core electrons such as the hyperfine field. A special interest is given with respect to the interplay between magneto-volume and chemical interactions (metal-H) effects within the following hydrided systems: binary Laves (e.g. ScFe 2 ) and Haucke (e.g. LaNi 5 ) phases on one hand, and ternary cerium based (e.g. CeRhSn) and uranium based (e.g. U 2 Ni 2 Sn) alloys on the other hand. (author)

  1. Are The Chemical Bonding Interactions in Halide Perovskite Solar Cells Cooperative?

    Science.gov (United States)

    Varadwaj, Pradeep; Varadwaj, Arpita; Yamashita, Koichi

    Designing novel photo-sensitive and -responsive light harvesting solar cell materials is an important area of nanoscience and technologies mainly because these can transform the light energy directly or indirectly into electricity. Examples of a few of them, inter alia, include dye-sensitized solar cells, organic solar cells and halide perovskite solar cells. Methylammonium lead iodide (CH3NH3PbI3) organic-inorganic hybrid perovskite is one of the highly valued photocatalysts reported till date, which is comparable in its strength with the inorganic cesium lead iodide (CsPbI3) perovskite solar cell especially for energy conversion. The study thus has focused on the fundamental understanding of the geometrical, electronic and energetic properties of the CH3NH3PbI3 and CsPbI3 nanoclusters, obtained using density functional theory calculations. The main aim towards this end was to uncover the consequences of additivity, or non-additive cooperative binding, in the intermolecular chemical bonding interactions examined for these nanoclusters. The results obtained are compared with the current state-of-the-art, and will be discussed in detail.

  2. Chemical bonding and the equilibrium composition of Grignard reagents in ethereal solutions.

    Science.gov (United States)

    Henriques, André M; Barbosa, André G H

    2011-11-10

    A thorough analysis of the electronic structure and thermodynamic aspects of Grignard reagents and its associated equilibrium composition in ethereal solutions is performed. Considering methylmagnesium halides containing fluorine, chlorine, and bromine, we studied the neutral, charged, and radical species associated with their chemical equilibrium in solution. The ethereal solvents considered, tetrahydrofuran (THF) and ethyl ether (Et(2)O), were modeled using the polarizable continuum model (PCM) and also by explicit coordination to the Mg atoms in a cluster. The chemical bonding of the species that constitute the Grignard reagent is analyzed in detail with generalized valence bond (GVB) wave functions. Equilibrium constants were calculated with the DFT/M06 functional and GVB wave functions, yielding similar results. According to our calculations and existing kinetic and electrochemical evidence, the species R(•), R(-), (•)MgX, and RMgX(2)(-) must be present in low concentration in the equilibrium. We conclude that depending on the halogen, a different route must be followed to produce the relevant equilibrium species in each case. Chloride and bromide must preferably follow a "radical-based" pathway, and fluoride must follow a "carbanionic-based" pathway. These different mechanisms are contrasted against the available experimental results and are proven to be consistent with the existing thermodynamic data on the Grignard reagent equilibria.

  3. Relaxation of the chemical bond skin chemisorption size matter ZTP mechanics H2O myths

    CERN Document Server

    Sun, Chang Q

    2014-01-01

    The aim of this book is to explore the detectable properties of a material to the parameters of bond and non-bond involved and to clarify the interdependence of various properties. This book is composed of four parts; Part I deals with the formation and relaxation dynamics of bond and non-bond during chemisorptions with uncovering of the correlation among the chemical bond, energy band, and surface potential barrier (3B) during reactions; Part II is focused on the relaxation of bonds between atoms with fewer neighbors than the ideal in bulk with unraveling of the bond order-length-strength (BOLS) correlation mechanism, which clarifies the nature difference between nanostructures and bulk of the same substance; Part III deals with the relaxation dynamics of bond under heating and compressing with revealing of rules on the temperature-resolved elastic and plastic properties of low-dimensional materials; Part IV is focused on the asymmetric relaxation dynamics of the hydrogen bond (O:H-O) and the anomalous behav...

  4. Adjusting the Chemical Bonding of SnO2@CNT Composite for Enhanced Conversion Reaction Kinetics.

    Science.gov (United States)

    Cheng, Yayi; Huang, Jianfeng; Qi, Hui; Cao, Liyun; Yang, Jun; Xi, Qiao; Luo, Xiaomin; Yanagisawa, Kazumichi; Li, Jiayin

    2017-08-01

    Carbon nanotubes (CNTs) with excellent electron conductivity are widely used to improve the electrochemical performance of the SnO 2 anode. However, the chemical bonding between SnO 2 and CNTs is not clearly elucidated despite it may affect the lithiation/delithiation behavior greatly. In this work, an SnO 2 @CNT composite with SnC and SnOC bonds as a linkage bridge is reported and the influence of the SnC and SnOC bonds on the lithium storage properties is revealed. It is found that the SnC bond can act as an ultrafast electron transfer path, facilitating the reversible conversion reaction between Sn and Li 2 O to form SnO 2 . Therefore, the SnO 2 @CNT composite with more SnC bond shows high reversible capacity and nearly half capacity contributes from conversion reaction. It is opposite for the SnO 2 @CNT composite with more SnOC bond that the electrons cannot be transferred directly to CNTs, resulting in depressed conversion reaction kinetics. Consequently, this work can provide new insight for exploration and design of metal oxide/carbon composite anode materials in lithium-ion battery. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Synthesis, Crystal Structure, and Chemical-Bonding Analysis of BaZn(NCN2

    Directory of Open Access Journals (Sweden)

    Alex J. Corkett

    2017-12-01

    Full Text Available The ternary carbodiimide BaZn(NCN2 was prepared by a solid-state metathesis reaction between BaF2, ZnF2, and Li2NCN in a 1:1:2 molar ratio, and its crystal structure was determined from Rietveld refinement of X-ray data. BaZn(NCN2 represents the aristotype of the LiBa2Al(NCN4 structure which is unique to carbodiimide/cyanamide chemistry and is well regarded as being constructed from ZnN4 tetrahedra, sharing edges and vertices through NCN2− units to form corrugated layers with Ba2+ in the interlayer voids. Structural anomalies in the shape of the cyanamide units are addressed via IR spectrometry and DFT calculations, which suggest the presence of slightly bent N=C=N2− carbodiimide units with C2v symmetry. Moreover, chemical-bonding analysis within the framework of crystal orbital Hamilton population (COHP reveals striking similarities between the bonding interactions in BaZn(NCN2 and SrZn(NCN2 despite their contrasting crystal structures. BaZn(NCN2 is only the second example of a ternary post-transition metal carbodiimide, and its realization paves the way for the preparation of analogues featuring divalent transition metals at the tetrahedral Zn2+ site.

  6. Crystal structure and chemical bonding of the intermetallic Zintl phase Yb11AlSb9.

    Science.gov (United States)

    Kastbjerg, Sofie; Uvarov, Catherine A; Kauzlarich, Susan M; Chen, Yu-Sheng; Nishibori, Eiji; Spackman, Mark A; Iversen, Bo Brummerstedt

    2012-09-14

    High resolution single crystal synchrotron X-ray diffraction data measured at 15(2) K were used to solve the structure of the complex intermetallic Zintl phase, Yb(11)AlSb(9) (space group Iba2), made up of Yb cations and polyanions along with isolated Sb anions. The 15(2) K cell parameters are a = 11.7383(4) Å, b = 12.3600(4) Å, c = 16.6796(6) Å. The temperature dependence of the structure was investigated through high resolution synchrotron powder X-ray diffraction (PXRD) data measured from 90 K to 1000 K. Rietveld refinements of the crystal structure revealed near linear thermal expansion of Yb(11)AlSb(9) with expansion coefficients of 1.49(2) × 10(-5) K(-1), 1.71(3) × 10(-5) K(-1), 1.13(1) × 10(-5) K(-1) for a, b and c, respectively. The chemical bonding in Yb(11)AlSb(9) was analyzed using atomic Hirshfeld surfaces, and the analysis supports the presence of the structural elements of Yb cations, [AlSb(4)](9-) tetrahedra, [Sb(2)](4-) dimers and isolated Sb(3-) anions. However, indications of interatomic interactions between the Zintl anions and the Yb cations were also observed.

  7. Nature of the chemical bond and prediction of radiation tolerance in pyrochlore and defect fluorite compounds

    International Nuclear Information System (INIS)

    Lumpkin, Gregory R.; Pruneda, Miguel; Rios, Susana; Smith, Katherine L.; Trachenko, Kostya; Whittle, Karl R.; Zaluzec, Nestor J.

    2007-01-01

    The radiation tolerance of synthetic pyrochlore and defect fluorite compounds has been studied using ion irradiation. We show that the results can be quantified in terms of the critical temperature for amorphization, structural parameters, classical Pauling electronegativity difference, and disorder energies. Our results demonstrate that radiation tolerance is correlated with a change in the structure from pyrochlore to defect fluorite, a smaller unit cell dimension, and lower cation-anion disorder energy. Radiation tolerance is promoted by an increase in the Pauling cation-anion electronegativity difference or, in other words, an increase in the ionicity of the chemical bonds. A further analysis of the data indicates that, of the two possible cation sites in ideal pyrochlore, the smaller B-site cation appears to play the major role in bonding. This result is supported by ab initio calculations of the structure and bonding, showing a correlation between the Mulliken overlap populations of the B-site cation and the critical temperature. - Graphical abstract: Three-dimensional representation of the predicted critical amorphization temperature in pyrochlores

  8. Understanding Boron through Size-Selected Clusters: Structure, Chemical Bonding, and Fluxionality

    Energy Technology Data Exchange (ETDEWEB)

    Sergeeva, Alina P.; Popov, Ivan A.; Piazza, Zachary A.; Li, Wei-Li; Romanescu, Constantin; Wang, Lai S.; Boldyrev, Alexander I.

    2014-04-15

    Conspectus Boron is an interesting element with unusual polymorphism. While three-dimensional (3D) structural motifs are prevalent in bulk boron, atomic boron clusters are found to have planar or quasi-planar structures, stabilized by localized two-center–two-electron (2c–2e) σ bonds on the periphery and delocalized multicenter–two-electron (nc–2e) bonds in both σ and π frameworks. Electron delocalization is a result of boron’s electron deficiency and leads to fluxional behavior, which has been observed in B13+ and B19–. A unique capability of the in-plane rotation of the inner atoms against the periphery of the cluster in a chosen direction by employing circularly polarized infrared radiation has been suggested. Such fluxional behaviors in boron clusters are interesting and have been proposed as molecular Wankel motors. The concepts of aromaticity and antiaromaticity have been extended beyond organic chemistry to planar boron clusters. The validity of these concepts in understanding the electronic structures of boron clusters is evident in the striking similarities of the π-systems of planar boron clusters to those of polycyclic aromatic hydrocarbons, such as benzene, naphthalene, coronene, anthracene, or phenanthrene. Chemical bonding models developed for boron clusters not only allowed the rationalization of the stability of boron clusters but also lead to the design of novel metal-centered boron wheels with a record-setting planar coordination number of 10. The unprecedented highly coordinated borometallic molecular wheels provide insights into the interactions between transition metals and boron and expand the frontier of boron chemistry. Another interesting feature discovered through cluster studies is boron transmutation. Even though it is well-known that B–, formed by adding one electron to boron, is isoelectronic to carbon, cluster studies have considerably expanded the possibilities of new structures and new materials using the B

  9. Topological Properties of Chemical Bonds from Static and Dynamic Electron Densities

    Science.gov (United States)

    Jagannatha Prathapa, Siriyara; Held, Jeanette; van Smaalen, Sander

    2013-01-01

    Dynamic and static electron densities (EDs) based on the independent spherical atom model (IAM) and multipole (MP) models of crambin were successfully computed, holding no series-termination effects. The densities are compared to EDs of small biological molecules at diverse temperatures. It is outlined that proteins exhibit an intrinsic flexibility, present as frozen disorder at 100 K, in contrast to small molecules. The flexibility of the proteins is reflected by atomic displacement parameters (B-factors), which are considerably larger than for small molecules at 298 K. Thus, an optimal deconvolution of deformation density and thermal motion is not guaranteed, which prevents a free refinement of MP parameters but allows an application of transferable, fixed MP parameters. The analysis of the topological properties, such as the density at bond critical points (BCPs) and the Laplacian, reveals systematic differences between static and dynamic EDs. Zero-point-vibrations, yet present in dynamic EDs at low temperature, affect but marginally the EDs of small molecules. The zero-point-vibrations cause a smearing of the ED, which becomes more pronounced with increasing temperature. Topological properties, primarily the Laplacian, of covalent bonds appear to be more sensitive to effects by temperature and the polarity of the bonds. However, dynamic EDs at ca. 20 K based on MP models provide a good characterization of chemical bonding. Both the density at BCPs and the Laplacian of hydrogen bonds constitute similar values from static and dynamic EDs for all studied temperatures. Deformation densities demonstrate the necessity of the employment of MP parameters in order to comprise the nature of covalent bonds. The character of hydrogen bonds can be roughly pictured by IAM, whereas MP parameters are recommended for a classification of hydrogen bonds beyond a solely interpretation of topological properties. PMID:25995522

  10. Investigation of thermal expansion and compressibility of rare-earth orthovanadates using a dielectric chemical bond method.

    Science.gov (United States)

    Zhang, Siyuan; Zhou, Shihong; Li, Huaiyong; Li, Ling

    2008-09-01

    The chemical bond properties, lattice energies, linear expansion coefficients, and mechanical properties of ReVO 4 (Re = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Y) are investigated systematically by the dielectric chemical bond theory. The calculated results show that the covalencies of Re-O bonds are increasing slightly from La to Lu and that the covalencies of V-O bonds in crystals are decreasing slightly from La to Lu. The linear expansion coefficients decrease progressively from LaVO 4 to LuVO 4; on the contrary, the bulk moduli increase progressively. Our calculated results are in good agreement with some experimental values for linear expansion coefficients and bulk moduli.

  11. Electronic parameters of Sr2M2O7 (M = V, Nb, Ta) and Sr-O chemical bonding

    DEFF Research Database (Denmark)

    Atuchin, Victor V.; Grivel, Jean-Claude; Zhang, Zhaoming

    2010-01-01

    on the formation of the Sr-O bonds. The chemical bonding effects were considered on the basis of our XPS results for Sr2Nb2O7 and Sr2Ta2O7 and the previously published structural and XPS data for other Sr-oxide compounds. A new empirical relationship between Δ(O-Sr) and L(Sr-O) was obtained. Possible applications...

  12. Characteristics of chemical bond and vacancy formation in chalcopyrite-type CuInSe2 and related compounds

    International Nuclear Information System (INIS)

    Maeda, Tsuyoshi; Wada, Takahiro

    2009-01-01

    We studied characteristics of chemical bond and vacancy formation in chalcopyrite-type CuInSe 2 (CIS) by first principles calculations. The chalcopyrite-type CIS has two kinds of chemical bonds, Cu-Se and In-Se. The Cu-Se bond is a weak covalent bonding because electrons occupy both bonding and antibonding orbitals of Cu 3d and Se 4p and occupy only the bonding orbital (a 1 ) of Cu 4s and Se 4p and do not occupy the antibonding orbital (a 1 * ) of Cu 4s and Se 4p. On the other hand, the In-Se bond has a partially covalent and partially ionic character because the In 5s orbital covalently interacts with Se 4p; the In 5p orbital is higher than Se 4p and so the electron in the In 5p orbital moves to the Se 4p orbital. The average bond order of the Cu-Se and In-Se bonds can be calculated to be 1/4 and 1, respectively. The bond order of Cu-Se is smaller than that of In-Se. The characteristics of these two chemical bonds are related to the formation of Cu and In vacancies in CIS. The formation energy of the Cu vacancy is smaller than that of the In vacancy under both Cu-poor and In-poor conditions. The displacement (Δl) of the surrounding Se atoms after the formation of the Cu vacancy is smaller than the Δl after the formation of the In vacancy. The interesting and unique characteristics of CIS are discussed on the basis of the characteristics of the chemical bond. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Toward a consistent interpretation of the QTAIM: tortuous link between chemical bonds, interactions, and bond/line paths.

    Science.gov (United States)

    Foroutan-Nejad, Cina; Shahbazian, Shant; Marek, Radek

    2014-08-04

    Currently, bonding analysis of molecules based on the Quantum Theory of Atoms in Molecules (QTAIM) is popular; however, "misinterpretations" of the QTAIM analysis are also very frequent. In this contribution the chemical relevance of the bond path as one of the key topological entities emerging from the QTAIM's topological analysis of the one-electron density is reconsidered. The role of nuclear vibrations on the topological analysis is investigated demonstrating that the bond paths are not indicators of chemical bonds. Also, it is argued that the detection of the bond paths is not necessary for the "interaction" to be present between two atoms in a molecule. The conceptual disentanglement of chemical bonds/interactions from the bonds paths, which are alternatively termed "line paths" in this contribution, dismisses many superficial inconsistencies. Such inconsistencies emerge from the presence/absence of the line paths in places of a molecule in which chemical intuition or alternative bonding analysis does not support the presence/absence of a chemical bond. Moreover, computational QTAIM studies have been performed on some "problematic" molecules, which were considered previously by other authors, and the role of nuclear vibrations on presence/absence of the line paths is studied demonstrating that a bonding pattern consistent with other theoretical schemes appears after a careful QTAIM analysis and a new "interpretation" of data is performed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Calcium phosphate coating on titanium induced by phosphating

    Energy Technology Data Exchange (ETDEWEB)

    Feng, B. [Sichuan Univ., Chengdu (China). Engineering Research Center in Biomaterials; Sichuan Inst. of Tech., Chengdu (China). Dept. of Material Science and Engineering; Chen, J.Y.; Zhang, X.D. [Sichuan Univ., Chengdu (China). Engineering Research Center in Biomaterials

    2001-07-01

    The phosphatization has been used in anti-corrosion treatment for metals for many years. In this work, the calcium phosphate ceramic coatings (Ca-P coatings) based on titanium were prepared by phosphating titanium and then soaking in a supersaturated calcium phosphate solution. The effect of phosphatization of titanium on the formation of Ca-P coating was investigated. The analysis with a scanning electron microscopy showed microporous surfaces of titanium after phosphatization. The spectra of X-ray photoelectron spectroscopy indicated that the surfaces contained PO{sub 4}{sup 3-}, HPO{sub 4}{sup 2-} and H{sub 2}PO{sup -}. The induced couple plasma atomic emission spectroscopy suggested that precipitation of P be prior to Ca during immersion in the supersaturated calcium phosphate solution. (orig.)

  15. Chemical bonding in epitaxial ZrB 2 studied by X-ray spectroscopy

    Science.gov (United States)

    Magnuson, Martin; Tengdelius, Lina; Greczynski, Grzegorz; Hultman, Lars; Högberg, Hans

    2018-03-01

    The chemical bonding in an epitaxial ZrB2 film is investigated by Zr K-edge (1s) X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopies and compared to the ZrB2 compound target from which the film was synthesized as well as a bulk {\\alpha}-Zr reference. Quantitative analysis of X-ray Photoelectron Spectroscopy spectra reveals at the surface: ~5% O in the epitaxial ZrB2 film, ~19% O in the ZrB2 compound target and ~22% O in the bulk {\\alpha}-Zr reference after completed sputter cleaning. For the ZrB2 compound target, X-ray diffraction (XRD) shows weak but visible -111, 111, and 220 peaks from monoclinic ZrO2 together with peaks from ZrB2 and where the intensity distribution for the ZrB2 peaks show a randomly oriented target material. For the bulk {\\alpha}-Zr reference no peaks from any crystalline oxide were visible in the diffractogram recorded from the 0001-oriented metal. The Zr K-edge absorption from the two ZrB2 samples demonstrate more pronounced oscillations for the epitaxial ZrB2 film than in the bulk ZrB2 attributed to the high atomic ordering within the columns of the film. The XANES exhibits no pre-peak due to lack of p-d hybridization in ZrB2, but with a chemical shift towards higher energy of 4 eV in the film and 6 eV for the bulk compared to {\\alpha}-Zr (17.993 keV) from the charge-transfer from Zr to B. The 2 eV larger shift in bulk ZrB2 material suggests higher oxygen content than in the epitaxial film, which is supported by XPS. In EXAFS, the modelled cell-edge in ZrB2 is slightly smaller in the thin film (a=3.165 {\\AA}, c=3.520 {\\AA}) in comparison to the bulk target material (a=3.175 {\\AA}, c=3.540 {\\AA}) while in hexagonal closest-packed metal ({\\alpha}-phase, a=3.254 {\\AA}, c=5.147 {\\AA}).

  16. [Influence of primers ' chemical composition on shear bond strength of resin cement to zirconia ceramic].

    Science.gov (United States)

    Łagodzińska, Paulina; Bociong, Kinga; Dejak, Beata

    2014-01-01

    Resin cements establish a strong durable bond between zirconia ceramic and hard tissues of teeth. It is essential to use primers with proper chemical composition before cementation. The aim of this study was to assess the influence of primer's chemical composition on the shear bond strength of zirconia ceramic to resin cements. 132 zirconia specimens were randomly assigned to four groups. There were four resin systems used. They included resin cement and respective primer, dedicated to zirconia: Clearfil Ceramic Primer/Panavia F2.0, Monobond Plus/Multilink Automix, AZ - Primer/ResiCem, Z - Prime Plus/Duo-Link. In each group the protocol of cementation was as follows: application of primer to the zirconia surface and application of the respective resin cement in cylindric mold (dimensions: 3.0 mm height and 3.0 mm diameter). Then, the shear bond strength was evaluated and the failure type was assessed in lupes (×2.5 magnification), also random specimens under SEM. The Wilcoxon test was used to analyze the data, the level of significance was α = 0.05. Finally, the known chemical composition of each primer was analysed in reference to probable chemical bonds, which may occure between primers and zirconia. The mean shear bond strength between resin cements and zirconia was the highest for Z-Prime Plus/Duo-Link (8.24 ± 3,21 MPa) and lowest for Clearfil Ceramic Primer/Panavia F 2.0 (4.60 ± 2.21 MPa). The analysis revealed significant difference between all groups, except pair Clearfil Ceramic Primer/Panavia F 2.0 and AZ-Primer/ResiCem. The failure type in groups of Clearfil Ceramic Primer/Panavia F 2.0 and AZ-Primer/ResiCem was mainly adhesive, in groups Monobond Plus/ /Multilink Automix and Z-Prime Plus/Duo-Link mainly mixed. The chemical composition of primers affects different bond mechanisms between resin cements and zirconia. The highest shear bond strength of resin cement to zirconia can be obtained for the primer composed of 10-Methacryloyloxydecyl dihydrogen

  17. Problems and possibilities of development of boron nitride ceramics

    International Nuclear Information System (INIS)

    Rusanova, L.N.; Romashin, A.G.; Kulikova, G.I.; Golubeva, O.P.

    1988-01-01

    The modern state of developments in the field of technology of ceramics produced from boron nitride is analyzed. Substantial difficulties in production of pure ceramics from hexagonal and wurtzite-like boron nitride are stated as related to the structure peculiarities and inhomogeneity of chemical bonds in elementary crystal cells of various modifications. Advantages and disadvantages of familiar technological procedures in production of boron nitride ceramics are compared. A new technology is suggested, which is based on the use of electroorganic compounds for hardening and protection of porous high-purity boron-nitride die from oxidation, and as high-efficient sintered elements for treatment of powders of various structures and further pyrolisis. The method is called thermal molecular lacing (TML). Properties of ceramics produced by the TML method are compared with characteristics of well-known brands of boron nitride ceramics

  18. Portfolio: Ceramics.

    Science.gov (United States)

    Hardy, Jane; And Others

    1982-01-01

    Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

  19. In situ synchrotron powder diffraction study of the setting reaction kinetics of magnesium-potassium phosphate cements

    Czech Academy of Sciences Publication Activity Database

    Viani, Alberto; Pérez-Estébanez, Marta; Pollastri, S.; Gualtieri, A. F.

    2016-01-01

    Roč. 79, January (2016), s. 344-352 ISSN 0008-8846 R&D Projects: GA MŠk(CZ) LO1219 Keywords : kinetics * reaction * X-ray diffraction * MgO * chemically bonded ceramics Subject RIV: JN - Civil Engineering Impact factor: 4.762, year: 2016 http://www.sciencedirect.com/science/article/pii/S0008884615002690

  20. Exploration of earth-abundant transition metals (Fe, Co, and Ni) as catalysts in unreactive chemical bond activations.

    Science.gov (United States)

    Su, Bo; Cao, Zhi-Chao; Shi, Zhang-Jie

    2015-03-17

    Activation of inert chemical bonds, such as C-H, C-O, C-C, and so on, is a very important area, to which has been drawn much attention by chemists for a long time and which is viewed as one of the most ideal ways to produce valuable chemicals. Under modern chemical bond activation logic, many conventionally viewed "inert" chemical bonds that were intact under traditional conditions can be reconsidered as novel functionalities, which not only avoids the tedious synthetic procedures for prefunctionalizations and the emission of undesirable wastes but also inspires chemists to create novel synthetic strategies in completely different manners. Although activation of "inert" chemical bonds using stoichiometric amounts of transition metals has been reported in the past, much more attractive and challenging catalytic transformations began to blossom decades ago. Compared with the broad application of late and noble transition metals in this field, the earth-abundant first-row transition-metals, such as Fe, Co, and Ni, have become much more attractive, due to their obvious advantages, including high abundance on earth, low price, low or no toxicity, and unique catalytic characteristics. In this Account, we summarize our recent efforts toward Fe, Co, and Ni catalyzed "inert" chemical bond activation. Our research first unveiled the unique catalytic ability of iron catalysts in C-O bond activation of both carboxylates and benzyl alcohols in the presence of Grignard reagents. The benzylic C-H functionalization was also developed via Fe catalysis with different nucleophiles, including both electron-rich arenes and 1-aryl-vinyl acetates. Cobalt catalysts also showed their uniqueness in both aromatic C-H activation and C-O activation in the presence of Grignard reagents. We reported the first cobalt-catalyzed sp(2) C-H activation/arylation and alkylation of benzo[h]quinoline and phenylpyridine, in which a new catalytic pathway via an oxidative addition process was demonstrated

  1. High pressure stability analysis and chemical bonding of Ti1-xZrxN alloy: A first principle study

    International Nuclear Information System (INIS)

    Chauhan, Mamta; Gupta, Dinesh C.

    2016-01-01

    First-principles pseudo-potential calculations have been performed to analyze the stability of Ti 1-x Zr x N alloy under high pressures. The first order phase transition from B1 to B2 phase has been observed in this alloy at high pressure. The variation of lattice parameter with the change in concentration of Zr atom in Ti 1-x Zr x N is also reported in both the phases. The calculations for density of states have been performed to understand the alloying effects on chemical bonding of Ti-Zr-N alloy.

  2. Role of the chemical bonding for the time-dependent electron transport through an interacting quantum dot

    KAUST Repository

    Goker, Ali

    2011-06-01

    A combination of ab initio and many-body calculations is utilized to determine the effects of the bonding in Au electrodes on the time dependent current through a quantum dot suddenly shifted into the Kondo regime by a gate voltage. For an asymmetrically coupled system the instantaneous conductance exhibits fluctuations. The frequencies of the fluctuations turn out to be proportional to the energetic separation between the dominating peaks in the density of states and the Fermi level. The chemical bonding in the electrodes, thus, drastically alters the transient current, which can be accessed by ultrafast pump-probe techniques. © 2011 Elsevier B.V. All rights reserved.

  3. Mechanical properties of chemically bonded sand core materials dipped in sol-gel coating impregnated with filter

    DEFF Research Database (Denmark)

    Nwaogu, Ugochukwu Chibuzoh; Tiedje, Niels Skat

    2012-01-01

    -displacement curve from which the mechanical properties of the materials are deduced. The fracture surfaces were examined using a stereomicroscope and a scanning electron microscope. From the results, the strengths of the core materials were slightly reduced by the coating in tensile and flexural modes, while......A novel sol-gel coating impregnated with filter dust was applied on chemically bonded sand core materials by dipping. After curing, the strengths of the core materials were measured under uniaxial loading using a new strength testing machine (STM). The STM presents the loading history as a force...

  4. Phosphate Salts

    Science.gov (United States)

    ... many different combinations of the chemical phosphate with salts and minerals. Foods high in phosphate include dairy products, whole grain cereals, nuts, and certain meats. Phosphates found in dairy products ... People use phosphate salts for medicine. Be careful not to confuse phosphate ...

  5. Investigation of chemical bond characteristics, thermal expansion coefficients and bulk moduli of alpha-R2MoO6 and R2Mo2O7 (R = rare earths) by using a dielectric chemical bond method.

    Science.gov (United States)

    Li, Huaiyong; Zhang, Siyuan; Zhou, Shihong; Cao, Xueqiang

    2009-09-01

    Theoretical researches are performed on the alpha-R2MoO6 (R = Y, Gd, Tb Dy, Ho, Er, Tm and Yb) and pyrochlore-type R2Mo2O7 (R = Y, Nd, Sm, Gd, Tb and Dy) rare earth molybdates by using chemical bond theory of dielectric description. The chemical bonding characteristics and their relationship with thermal expansion property and compressibility are explored. The calculated values of linear thermal expansion coefficient (LTEC) and bulk modulus agree well with the available experimental values. The calculations reveal that the LTECs and the bulk moduli do have linear relationship with the ionic radii of the lanthanides: the LTEC decreases from 6.80 to 6.62 10(-6)/K and the bulk modulus increases from 141 to 154 GPa when R goes in the order Gd, Tb Dy, Ho, Er, Tm, and Yb in the alpha-R2MoO6 series; while in the R2Mo2O7 series, the LTEC ranges from 6.80 to 6.61 10(-6)/K and the bulk modulus ranges from 147 to 163 GPa when R varies in the order Nd, Sm, Gd, Tb and Dy. Copyright 2008 Wiley Periodicals, Inc.

  6. Advanced Sodium Ion Battery Anode Constructed via Chemical Bonding between Phosphorus, Carbon Nanotube, and Cross-Linked Polymer Binder.

    Science.gov (United States)

    Song, Jiangxuan; Yu, Zhaoxin; Gordin, Mikhail L; Li, Xiaolin; Peng, Huisheng; Wang, Donghai

    2015-12-22

    Maintaining structural stability is a great challenge for high-capacity conversion electrodes with large volume change but is necessary for the development of high-energy-density, long-cycling batteries. Here, we report a stable phosphorus anode for sodium ion batteries by the synergistic use of chemically bonded phosphorus-carbon nanotube (P-CNT) hybrid and cross-linked polymer binder. The P-CNT hybrid was synthesized through ball-milling of red phosphorus and carboxylic group functionalized carbon nanotubes. The P-O-C bonds formed in this process help maintain contact between phosphorus and CNTs, leading to a durable hybrid. In addition, cross-linked carboxymethyl cellulose-citric acid binder was used to form a robust electrode. As a result, this anode delivers a stable cycling capacity of 1586.2 mAh/g after 100 cycles, along with high initial Coulombic efficiency of 84.7% and subsequent cycling efficiency of ∼99%. The unique electrode framework through chemical bonding strategy reported here is potentially inspirable for other electrode materials with large volume change in use.

  7. Thermal stability of phosphate coatings on steel

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2015-07-01

    Full Text Available The work was validated thermal stability of zinc, manganese and tri-cations phosphate coatings on steel, made from commercial phosphating bath type Pragofos. Thermogravimetric data dehydration of scholzite, phosphophylite and hureaulite coatings in the temperature range 160 °C – 400 °C define the conditions for applying paints with higher firing temperature or thermal spraying ceramic coatings.

  8. Effects of Jigsaw Cooperative Learning and Animation Techniques on Students' Understanding of Chemical Bonding and Their Conceptions of the Particulate Nature of Matter

    Science.gov (United States)

    Karacop, Ataman; Doymus, Kemal

    2013-04-01

    The aim of this study was to determine the effect of jigsaw cooperative learning and computer animation techniques on academic achievements of first year university students attending classes in which the unit of chemical bonding is taught within the general chemistry course and these students' learning of the particulate nature of matter of this unit. The sample of this study consisted of 115 first-year science education students who attended the classes in which the unit of chemical bonding was taught in a university faculty of education during the 2009-2010 academic year. The data collection instruments used were the Test of Scientific Reasoning, the Purdue Spatial Visualization Test: Rotations, the Chemical Bonding Academic Achievement Test, and the Particulate Nature of Matter Test in Chemical Bonding (CbPNMT). The study was carried out in three different groups. One of the groups was randomly assigned to the jigsaw group, the second was assigned to the animation group (AG), and the third was assigned to the control group, in which the traditional teaching method was applied. The data obtained with the instruments were evaluated using descriptive statistics, one-way ANOVA, and MANCOVA. The results indicate that the teaching of chemical bonding via the animation and jigsaw techniques was more effective than the traditional teaching method in increasing academic achievement. In addition, according to findings from the CbPNMT, the students from the AG were more successful in terms of correct understanding of the particulate nature of matter.

  9. Scandium phosphates

    International Nuclear Information System (INIS)

    Mel'nikov, P.P.; Komissarova, L.N.

    1988-01-01

    The review deals with scandium phosphates known by now, including mono- and condensed phosphates (di-, tri-, tetra phosphates and more condensed forms). Phosphates with complex cation and anion parts are also considered. The methods of preparation, structural types, structure peculiarities, physicochemical characteristics are generalized and application fields of the compounds mentioned are indicated

  10. Flyweight, Superelastic, Electrically Conductive, and Flame-Retardant 3D Multi-Nanolayer Graphene/Ceramic Metamaterial.

    Science.gov (United States)

    Zhang, Qiangqiang; Lin, Dong; Deng, Biwei; Xu, Xiang; Nian, Qiong; Jin, Shengyu; Leedy, Kevin D; Li, Hui; Cheng, Gary J

    2017-07-01

    A ceramic/graphene metamaterial (GCM) with microstructure-derived superelasticity and structural robustness is achieved by designing hierarchical honeycomb microstructures, which are composited with two brittle constituents (graphene and ceramic) assembled in multi-nanolayer cellular walls. Attributed to the designed microstructure, well-interconnected scaffolds, chemically bonded interface, and coupled strengthening effect between the graphene framework and the nanolayers of the Al 2 O 3 ceramic (NAC), the GCM demonstrates a sequence of multifunctional properties simultaneously that have not been reported for ceramics and ceramics-matrix-composite structures, such as flyweight density, 80% reversible compressibility, high fatigue resistance, high electrical conductivity, and excellent thermal-insulation/flame-retardant performance simultaneously. The 3D well-ordered graphene aerogel templates are strongly coupled with the NAC by the chemically bonded interface, exhibiting mutual strengthening, compatible deformability, and a linearly dependent relationship between the density and Young's modulus. Considerable size effects of the ceramic nanolayers on the mechanical properties are revealed in these ceramic-based metamaterials. The designed hierarchical honeycomb graphene with a fourth dimensional control of the ceramic nanolayers on new ways to scalable fabrication of advanced multifunctional ceramic composites with controllable design suggest a great potential in applications of flexible conductors, shock/vibration absorbers, thermal shock barriers, thermal insulation/flame-retardant skins, and porous microwave-absorbing coatings. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Sandwiched Thin-Film Anode of Chemically Bonded Black Phosphorus/Graphene Hybrid for Lithium-Ion Battery.

    Science.gov (United States)

    Liu, Hanwen; Zou, Yuqin; Tao, Li; Ma, Zhaoling; Liu, Dongdong; Zhou, Peng; Liu, Hongbo; Wang, Shuangyin

    2017-09-01

    A facile vacuum filtration method is applied for the first time to construct sandwich-structure anode. Two layers of graphene stacks sandwich a composite of black phosphorus (BP), which not only protect BP from quickly degenerating but also serve as current collector instead of copper foil. The BP composite, reduced graphene oxide coated on BP via chemical bonding, is simply synthesized by solvothermal reaction at 140 °C. The sandwiched film anode used for lithium-ion battery exhibits reversible capacities of 1401 mAh g -1 during the 200th cycle at current density of 100 mA g -1 indicating superior cycle performance. Besides, this facile vacuum filtration method may also be available for other anode material with well dispersion in N-methyl pyrrolidone (NMP). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Lattice dynamics and chemical bonding in Sb{sub 2}Te{sub 3} from first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bao-Tian, E-mail: wbt11129@sxu.edu.cn [Institute of Theoretical Physics and Department of Physics, Shanxi University, Taiyuan 030006 (China); Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, P.O. Box 516, SE-75120 Uppsala (Sweden); Souvatzis, Petros; Eriksson, Olle, E-mail: olle.eriksson@physics.uu.se [Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, P.O. Box 516, SE-75120 Uppsala (Sweden); Zhang, Ping [LCP, Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

    2015-05-07

    Pressure effects on the lattice dynamics and the chemical bonding of the three-dimensional topological insulator, Sb{sub 2}Te{sub 3}, have been studied from a first-principles perspective in its rhombohedral phase. Where it is possible to compare, theory agrees with most of the measured phonon dispersions. We find that the inclusion of relativistic effects, in terms of the spin-orbit interaction, affects the vibrational features to some extend and creates large fluctuations on phonon density of state in high frequency zone. By investigations of structure and electronic structure, we analyze in detail the semiconductor to metal transition at ∼2 GPa followed by an electronic topological transition at a pressure of ∼4.25 GPa.

  13. Interfacial chemical bonding state and band alignment of CaF2/hydrogen-terminated diamond heterojunction

    International Nuclear Information System (INIS)

    Liu, J. W.; Liao, M. Y.; Cheng, S. H.; Imura, M.; Koide, Y.

    2013-01-01

    CaF 2 films are deposited on hydrogen-terminated diamond (H-diamond) by a radio-frequency sputter-deposition technique at room temperature. Interfacial chemical bonding state and band alignment of CaF 2 /H-diamond heterojunction are investigated by X-ray photoelectron spectroscopy. It is confirmed that there are only C-Ca bonds at the CaF 2 /H-diamond heterointerface. Valence and conductance band offsets of the CaF 2 /H-diamond heterojunciton are determined to be 3.7 ± 0.2 and 0.3 ± 0.2 eV, respectively. It shows a type I straddling band configuration. The large valence band offset suggests advantage of the CaF 2 /H-diamond heterojunciton for the development of high power and high frequency field effect transistors.

  14. Characterization of electron-deficient chemical bonding of diborane with attosecond electron wavepacket dynamics and laser response

    Science.gov (United States)

    Yonehara, Takehiro; Takatsuka, Kazuo

    2009-12-01

    We report a theoretical study of non-adiabatic electrons-nuclei coupled dynamics of diborane H 2BH 2BH 2 under several types of short pulse lasers. This molecule is known to have particularly interesting geometrical and electronic structures, which originate from the electron-deficient chemical bondings. We revisit the chemical bonding of diborane from the view point of electron wavepacket dynamics coupled with nuclear motions, and attempt to probe the characteristics of it by examining its response to intense laser fields. We study in the following three aspects, (i) bond formation of diborane by collision between two monoboranes, (ii) attosecond electron wavepacket dynamics in the ground state and first excited state by circularly polarized laser pulse, and (iii) induced fragmentation back to monoborane molecules by linearly polarized laser. The wave lengths of two types of laser field employed are 200 nm (in UV range) and 800 nm (in IR range), and we track the dynamics from hundreds of attoseconds up to few tens of femtoseconds. To this end, we apply the ab initio semiclassical Ehrenfest theory, into which the classical vector potential of a laser field is introduced. Basic features of the non-adiabatic response of electrons to the laser fields is elucidated in this scheme. To analyze the electronic wavepackets thus obtained, we figure out bond order density that is a spatial distribution of the bond order and bond order flux density arising only from the bonding regions, and so on. Main findings in this work are: (i) dimerization of monoboranes to diborane is so efficient that even intense laser is hard to prevent it; (ii) collective motions of electron flux emerge in the central BHHB bonding area in response to the circularly polarized laser fields; (iii) laser polarization with the direction of central two BH bonding vector is efficient for the cleavage of BH 3-BH 3; and (iv) nuclear derivative coupling plays a critical role in the field induced fragmentation

  15. Characterization of chemical bonding in low-k dielectric materialsfor interconnect isolation: a xas and eels study

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, P.; Schmeisser, D.; Engelmann, H.-J.; Zschech, E.; Stegmann, H.; Himpsel, F.; Denlinger, J.

    2006-04-10

    The use of low dielectric constant materials in the on-chipinterconnect process reduces interconnect delay, power dissipation andcrosstalk noise. To achieve the requirements of the ITRS for 2007-2009minimal sidewall damage from etch, ash or cleans is required. In chemicalvapor deposited (CVD) organo-silicate glass (OSG) which are used asintermetal dielectric (IMD) materials the substitution of oxygen in SiO2by methyl groups (-CH3) reduces the permittivity significantly (from 4.0in SiO2 to 2.6-3.3 in the OSG), since the electronic polarizability islower for Si-C bonds than for Si-O bonds. However, plasma processing forresist stripping, trench etching and post-etch cleaning removes C and Hcontaining molecular groups from the near-surface layer of OSG.Therefore, compositional analysis and chemical bonding characterizationof structured IMD films with nanometer resolution is necessary forprocess optimization. OSG thin films as-deposited and after plasmatreatment are studied using X-ray absorption spectroscopy (XAS) andelectron energy loss spectroscopy (EELS). In both techniques, the finestructure near the C1s absorption or energy loss edge, respectively,allows to identify C-H, C-C, and C-O bonds. This gives the opportunity todifferentiate between individual low-k materials and their modifications.The O1s signal is less selective to individual bonds. XAS spectra havebeen recorded for non-patterned films and EELS spectra for patternedstructures. The chemical bonding is compared for as-deposited andplasma-treated low-k materials. The Fluorescence Yield (FY) and the TotalElectron Yield (TEY) recorded while XAS measurement are compared.Examination of the C 1s near-edge structures reveal a modified bonding ofthe remaining C atoms in the plasma-treated sample regions.

  16. Characterization of electron-deficient chemical bonding of diborane with attosecond electron wavepacket dynamics and laser response

    International Nuclear Information System (INIS)

    Yonehara, Takehiro; Takatsuka, Kazuo

    2009-01-01

    We report a theoretical study of non-adiabatic electrons-nuclei coupled dynamics of diborane H 2 BH 2 BH 2 under several types of short pulse lasers. This molecule is known to have particularly interesting geometrical and electronic structures, which originate from the electron-deficient chemical bondings. We revisit the chemical bonding of diborane from the view point of electron wavepacket dynamics coupled with nuclear motions, and attempt to probe the characteristics of it by examining its response to intense laser fields. We study in the following three aspects, (i) bond formation of diborane by collision between two monoboranes, (ii) attosecond electron wavepacket dynamics in the ground state and first excited state by circularly polarized laser pulse, and (iii) induced fragmentation back to monoborane molecules by linearly polarized laser. The wave lengths of two types of laser field employed are 200 nm (in UV range) and 800 nm (in IR range), and we track the dynamics from hundreds of attoseconds up to few tens of femtoseconds. To this end, we apply the ab initio semiclassical Ehrenfest theory, into which the classical vector potential of a laser field is introduced. Basic features of the non-adiabatic response of electrons to the laser fields is elucidated in this scheme. To analyze the electronic wavepackets thus obtained, we figure out bond order density that is a spatial distribution of the bond order and bond order flux density arising only from the bonding regions, and so on. Main findings in this work are: (i) dimerization of monoboranes to diborane is so efficient that even intense laser is hard to prevent it; (ii) collective motions of electron flux emerge in the central BHHB bonding area in response to the circularly polarized laser fields; (iii) laser polarization with the direction of central two BH bonding vector is efficient for the cleavage of BH 3 -BH 3 ; and (iv) nuclear derivative coupling plays a critical role in the field induced

  17. Dispersibility and chemical bonds between multi-walled carbon nanotubes and poly(ether ether ketone) in nanocomposite fibers

    International Nuclear Information System (INIS)

    Yanmei, Jin; Haihui, Liu; Ning, Wang; Lichen, Hou; Xing-Xiang, Zhang

    2012-01-01

    A series of multi-walled carbon nanotubes (MWNTs)/poly(ether ether ketone)(PEEK) nanocomposite fibers were fabricated by mixing, melt extruding PEEK with different loadings and species of MWNTs, and melt-spun the blended chips. Nanocomposite fibers were heat-stretched and heat-treated. The morphology and dispersibility of MWNTs in nanocomposite fibers were observed using a field emission environmental scanning electron microscope (FESEM) and a transmission electron microscope (TEM). The thermal and crystallization behavior of nanocomposite fibers were characterized using differential scanning calorimetry (DSC) and an X-ray diffractometer (XRD). Mechanical properties were tested using a tensile strength tester. MWNTs tend to aggregate when the loading exceeds 0.8 wt%. Functional groups on MWNTs improve the hydrophobicity and the dispersibility of MWNTs in PEEK matrix. The enhancement of mechanical properties depends on the loading and species of functional groups. The most effectively reinforced effect is in the sequence, carboxylic MWNTs (MWNT–COOH) > hydroxyl MWNTs (MWNT–OH) > MWNTs, which can be explained by the strong hydrogen bonding and the affinity between MWNT–COOH and PEEK, MWNT–OH and PEEK, and possible formation of a chemical bond between MWNT–COOH and PEEK. A nanocomposite fiber with excellent mechanical property was fabricated using 0.8 wt% MWNT–COOH as filler. The Young's modulus is 1.7 GPa; and the stress is 648 MPa. -- Highlights: ► Functional groups on MWNTs improve their hydrophobility and dispersability. ► Mechanical properties depend on the content and species of the functional groups. ► The reinforced effect is in the sequence, carboxylic MWNTs > hydroxyl MWNTs > MWNTs. ► The strength behavior was result of hydrogen bond, affinity and chemical bond. ► Dispersability of MWNTs in matrix was analyzed by calculating solubility parameter.

  18. The adsorption of acrolein on a Pt (1 1 1): A study of chemical bonding and electronic structure

    International Nuclear Information System (INIS)

    Pirillo, S.; López-Corral, I.; Germán, E.; Juan, A.

    2012-01-01

    Highlights: ► Study of acrolein/Pt (1 1 1) adsorption using ab-initio and semiempirical methods. ► Geometry optimization and DOS curves were carried out using VASP code. ► Study of chemical bonding evolution using COOP and OP analysis. ► After adsorption Pt-Pt, C=O and C=C bonds are weakened. ► η 3 -cis and η 4 -trans most stable adsorption modes, η 1 -trans less favored one. - Abstract: The adsorption of acrolein on a Pt (1 1 1) surface was studied using ab-initio and semiempirical calculations. Geometry optimization and densities of states (DOS) curves were carried out using the Vienna Ab-initio Simulation Package (VASP) code. We started our study with the preferential geometries corresponding to the different acrolein/Pt (1 1 1) adsorption modes previously reported. Then, we examined the evolution of the chemical bonding in these geometries, using the crystal orbital overlap population (COOP) and overlap population (OP) analysis of selected pairs of atoms. We analyzed the acrolein intramolecular bonds, Pt (1 1 1) superficial bonds and new molecule-surface formed bonds after adsorption. We found that Pt-Pt bonds interacting with the molecule and acrolein C=O and C=C bonds are weakened after adsorption; this last bond is significantly linked to the surface. The obtained C-Pt and O-Pt OP values suggest that the most stable adsorption modes are η 3 -cis and η 4 -trans, while the η 1 -trans is the less favored configuration. We also found that C p z orbital and Pt p z and d z 2 orbitals participate strongly in the adsorption process.

  19. Dispersibility and chemical bonds between multi-walled carbon nanotubes and poly(ether ether ketone) in nanocomposite fibers

    Energy Technology Data Exchange (ETDEWEB)

    Yanmei, Jin, E-mail: jinyanmei818@163.com [Tianjin Municipal Key Lab of Fiber Modification and Functional Fiber, Institute of Functional Fibers, Tianjin Polytechnic University, Tianjin 300387 (China); Haihui, Liu; Ning, Wang; Lichen, Hou [Tianjin Municipal Key Lab of Fiber Modification and Functional Fiber, Institute of Functional Fibers, Tianjin Polytechnic University, Tianjin 300387 (China); Xing-Xiang, Zhang, E-mail: zhangpolyu@gmail.com [Tianjin Municipal Key Lab of Fiber Modification and Functional Fiber, Institute of Functional Fibers, Tianjin Polytechnic University, Tianjin 300387 (China)

    2012-08-15

    A series of multi-walled carbon nanotubes (MWNTs)/poly(ether ether ketone)(PEEK) nanocomposite fibers were fabricated by mixing, melt extruding PEEK with different loadings and species of MWNTs, and melt-spun the blended chips. Nanocomposite fibers were heat-stretched and heat-treated. The morphology and dispersibility of MWNTs in nanocomposite fibers were observed using a field emission environmental scanning electron microscope (FESEM) and a transmission electron microscope (TEM). The thermal and crystallization behavior of nanocomposite fibers were characterized using differential scanning calorimetry (DSC) and an X-ray diffractometer (XRD). Mechanical properties were tested using a tensile strength tester. MWNTs tend to aggregate when the loading exceeds 0.8 wt%. Functional groups on MWNTs improve the hydrophobicity and the dispersibility of MWNTs in PEEK matrix. The enhancement of mechanical properties depends on the loading and species of functional groups. The most effectively reinforced effect is in the sequence, carboxylic MWNTs (MWNT-COOH) > hydroxyl MWNTs (MWNT-OH) > MWNTs, which can be explained by the strong hydrogen bonding and the affinity between MWNT-COOH and PEEK, MWNT-OH and PEEK, and possible formation of a chemical bond between MWNT-COOH and PEEK. A nanocomposite fiber with excellent mechanical property was fabricated using 0.8 wt% MWNT-COOH as filler. The Young's modulus is 1.7 GPa; and the stress is 648 MPa. -- Highlights: Black-Right-Pointing-Pointer Functional groups on MWNTs improve their hydrophobility and dispersability. Black-Right-Pointing-Pointer Mechanical properties depend on the content and species of the functional groups. Black-Right-Pointing-Pointer The reinforced effect is in the sequence, carboxylic MWNTs > hydroxyl MWNTs > MWNTs. Black-Right-Pointing-Pointer The strength behavior was result of hydrogen bond, affinity and chemical bond. Black-Right-Pointing-Pointer Dispersability of MWNTs in matrix was analyzed by

  20. Piezoelectric Ceramics

    International Nuclear Information System (INIS)

    Park, Chang Yeop

    1987-03-01

    This book tells of piezoelectric ceramics on BaTiO 3 Pb(Zr, Ti)O 3 , properties of piezoelectric ceramics, measurement method of piezoelectric ceramics, manufacturing method of piezoelectric ceramics, property of PbZrO 3 -PbTiO 3 , transparent ceramics like electro-optics effect, electro-optics ceramics, application of a producer of high voltage, application of ultrasonic generator, ZnO piezoelectric film and its application such as property of ZnO, piezoelectric of ZnO film, manufacturing method of ZnO.

  1. Preparation of magnesium phosphate cement by recycling the product of thermal transformation of asbestos containing wastes

    Czech Academy of Sciences Publication Activity Database

    Viani, Alberto; Gualtieri, A.F.

    2014-01-01

    Roč. 58, April (2014), s. 56-66 ISSN 0008-8846 R&D Projects: GA MŠk(CZ) LO1219 Institutional support: RVO:68378297 Keywords : cement-asbestos * chemically bonded ceramics * waste management * X-ray diffraction * amorphous material Subject RIV: JN - Civil Engineering Impact factor: 2.864, year: 2014 http://www.sciencedirect.com/science/article/pii/S000888461400012X

  2. On Ceramics.

    Science.gov (United States)

    School Arts, 1982

    1982-01-01

    Presents four ceramics activities for secondary-level art classes. Included are directions for primitive kiln construction and glaze making. Two ceramics design activities are described in which students make bizarrely-shaped lidded jars, feet, and footwear. (AM)

  3. Phosphate sensing

    Science.gov (United States)

    Bergwitz, Clemens; Jüppner, Harald

    2011-01-01

    Human phosphate homeostasis is regulated at the level of intestinal absorption of phosphate from the diet, release of phosphate through bone resorption, and renal phosphate excretion and involves the actions of parathyroid hormone (PTH), 1,25-dihydroxy-vitamin D (1,25-(OH)2-D), and fibroblast growth factor 23 (FGF23) to maintain circulating phosphate levels within a narrow normal range, which is essential for numerous cellular functions, for the growth of tissues and for bone mineralization. Prokaryotic and single cellular eukaryotic organisms such as bacteria and yeast “sense” ambient phosphate with a multi-protein complex located in their plasma membrane, which modulates the expression of genes important for phosphate uptake and metabolism (pho pathway). Database searches based on amino acid sequence conservation alone have been unable to identify metazoan orthologs of the bacterial and yeast phosphate sensors. Thus little is known about how human and other metazoan cells sense inorganic phosphate to regulate the effects of phosphate on cell metabolism (“metabolic” sensing) or to regulate the levels of extracellular phosphate via feedback system(s) (“endocrine” sensing). Whether the “metabolic” and the “endocrine” sensor use the same or different signal transduction cascades is unknown. This chapter will review the bacterial and yeast phosphate sensors, and then discuss what is currently known about the metabolic and endocrine effects of phosphate in multicellular organisms and humans. PMID:21406298

  4. The role of silicon on the bioactivity of Skelite(TM) bioceramic: A material and biological characterization of silicon alpha-tricalcium phosphate based ceramics

    Science.gov (United States)

    Pietak, Alexis Mari

    Skelite(TM) bioceramics are novel synthetic skeletal replacement materials that participate in the full remodeling process of bone. Skelite contains a high fraction of Silicon Stabilized alpha-Tricalcium Phosphate (Si-TCP), a novel phase to which the unique bioactive properties of Skelite have been attributed. The role of Si in the development of the microporous, interconnected microstructure and mixed phase composition of Skelite was investigated using crystallization kinetics and defect characterization studies. The kinetics of the phase transformation to Si-TCP were studied using rapid thermal processing of thin films on quartz substrates. The results, interpreted using a novel Avrami model, show that Si acts as a nucleation agent for Si-TCP, and also that Si pins the microstructure of the films at higher concentrations. Characterization of defects induced by Si substitution into the phases of Skelite material utilized electron spin resonance (ESR) and thermoluminescence (TL) techniques. These results identify two unique paramagnetic defect centers associated with Si substitution in the hydroxyapatite lattice. Quantification of the relative level of these centers supports a novel chemical model that describes the development of the mixed phase system of Skelite as a function of silica addition. The significance of the Si-TCP phase, sample morphology, and surface chemistry on the activity of osteoclast and osteoblast cells was investigated using cell culture and protein functionalized atomic force microscopy techniques. The biological characterization identifies three interaction mechanisms between Skelite and the biological system. Skelite releases a soluble molecular complex containing Si to the extracellular media, which has a significant bioactive effect on osteoclast and osteoblast growth and activity. Using protein functionalized atomic force microscopy the surface chemistry and reactivity of samples is shown to influence osteopontin affinity for Skelite

  5. Advanced Ceramics

    International Nuclear Information System (INIS)

    1989-01-01

    The First Florida-Brazil Seminar on Materials and the Second State Meeting about new materials in Rio de Janeiro State show the specific technical contribution in advanced ceramic sector. The others main topics discussed for the development of the country are the advanced ceramic programs the market, the national technic-scientific capacitation, the advanced ceramic patents, etc. (C.G.C.) [pt

  6. Sodium Phosphate

    Science.gov (United States)

    Sodium phosphate is used in adults 18 years of age or older to empty the colon (large intestine, bowel) ... view of the walls of the colon. Sodium phosphate is in a class of medications called saline ...

  7. Effects of Jigsaw Cooperative Learning and Animation Techniques on Students' Understanding of Chemical Bonding and Their Conceptions of the Particulate Nature of Matter

    Science.gov (United States)

    Karacop, Ataman; Doymus, Kemal

    2013-01-01

    The aim of this study was to determine the effect of jigsaw cooperative learning and computer animation techniques on academic achievements of first year university students attending classes in which the unit of chemical bonding is taught within the general chemistry course and these students' learning of the particulate nature of matter of this…

  8. Anatomy of Bond Formation. Bond Length Dependence on the Extent of Electron Sharing in Chemical Bonds from the Analysis of Domain-Averaged Fermi holes.

    Czech Academy of Sciences Publication Activity Database

    Ponec, Robert; Cooper, D.L.

    2007-01-01

    Roč. 135, č. 7, (2007) , s. 31-41 ISSN 0301-7249 R&D Projects: GA AV ČR(CZ) IAA4072006 Institutional research plan: CEZ:AV0Z40720504 Keywords : electron sharing * chemical bonds * domain averaged fermi holes Subject RIV: CF - Physical ; Theoretical Chemistry

  9. Evolution of the chemical bonding nature and electrode activity of indium selenide upon the composite formation with graphene nanosheets

    International Nuclear Information System (INIS)

    Oh, Seung Mi; Lee, Eunsil; Adpakpang, Kanyaporn; Patil, Sharad B.; Park, Mi Jin; Lim, Young Soo; Lee, Kyu Hyoung; Kim, Jong-Young; Hwang, Seong-Ju

    2015-01-01

    Graphical abstract: Display Omitted -- Highlights: • In 4 Se 2.85 @graphene nanocomposite is easily prepared by high energy mechanical milling process. • The bond covalency of In 4 Se 2.85 is notably changed upon the composite formation with graphene. • In 4 Se 2.85 @graphene nanocomposite shows promising anode performance for lithium ion battery. -- Abstract: Evolution of the chemical bonding nature and electrochemical activity of indium selenide upon the composite formation with carbon species is systematically investigated. Nanocomposites of In 4 Se 2.85 @graphene and In 4 Se 2.85 @carbon-black are synthesized via a solid state reaction between In and Se elements, and the following high energy mechanical milling of In 4 Se 2.85 with graphene and carbon-black, respectively. The high energy mechanical milling (HEMM) of In 4 Se 2.85 with carbon species gives rise to a decrease of particle size with a significant depression of the crystallinity of In 4 Se 2.85 phase. In contrast to the composite formation with carbon-black, that with graphene induces a notable decrease of (In−Se) bond covalency, underscoring significant chemical interaction between graphene and In 4 Se 2.85 . Both the nanocomposites of In 4 Se 2.85 @graphene and In 4 Se 2.85 @carbon-black show much better anode performance for lithium ion batteries with larger discharge capacity and better cyclability than does the pristine In 4 Se 2.85 material, indicating the beneficial effect of composite formation on the electrochemical activity of indium selenide. Between the present nanocomposites, the electrode performance of the In 4 Se 2.85 @graphene nanocomposite is superior to that of the In 4 Se 2.85 @carbon-black nanocomposite, which is attributable to the weakening of (In−Se) bonds upon the composite formation with graphene as well as to the better mixing between In 4 Se 2.85 and graphene. The present study clearly demonstrates that the composite formation with graphene has strong influence

  10. Probing Chemical Bonding and Electronic Structures in ThO-by Anion Photoelectron Imaging and Theoretical Calculations.

    Science.gov (United States)

    Li, Yanli; Zou, Jinghan; Xiong, Xiao-Gen; Su, Jing; Xie, Hua; Fei, Zejie; Tang, Zichao; Liu, Hongtao

    2017-03-16

    Because of renewed research on thorium-based molten salt reactors, there is growing demand and interest in enhancing the knowledge of thorium chemistry both experimentally and theoretically. Compared with uranium, thorium has few chemical studies reported up to the present. Here we report the vibrationally resolved photoelectron imaging of the thorium monoxide anion. The electron affinity of ThO is first reported to be 0.707 ± 0.020 eV. Vibrational frequencies of the ThO molecule and its anion are determined from Franck-Condon simulation. Spectroscopic evidence is obtained for the two-electron transition in ThO - , indicating the strong electron correlation among the (7s σ ) 2 (6d δ ) 1 electrons in ThO - and the (7s σ ) 2 electrons in ThO. These findings are explained by using quantum-chemical calculations including spin-orbit coupling, and the chemical bonding of gaseous ThO molecules is analyzed. The present work will enrich our understanding of bonding capacities with the 6d valence shell.

  11. Chemical bonding modifications of tetrahedral amorphous carbon and nitrogenated tetrahedral amorphous carbon films induced by rapid thermal annealing

    International Nuclear Information System (INIS)

    McCann, R.; Roy, S.S.; Papakonstantinou, P.; Bain, M.F.; Gamble, H.S.; McLaughlin, J.A.

    2005-01-01

    Tetrahedral amorphous carbon (ta-C) and nitrogenated tetrahedral amorphous carbon films (ta-CN x ), deposited by double bend off plane Filtered Vacuum Cathodic Arc were annealed up to 1000 deg. C in flowing argon for 2 min. Modifications on the chemical bonding structure of the rapidly annealed films, as a function of temperature, were investigated by NEXAFS, X-ray photoelectron and Raman spectroscopies. The interpretation of these spectra is discussed. The results demonstrate that the structure of undoped ta-C films prepared at floating potential with an arc current of 80 A remains stable up to 900 deg. C, whereas that of ta-CN x containing 12 at.% nitrogen is stable up to 700 deg. C. At higher temperatures, all the spectra indicated the predominant formation of graphitic carbon. Through NEXAFS studies, we clearly observed three π* resonance peaks at the ' N K edge structure. The origin of these three peaks is not well established in the literature. However our temperature-dependant study ascertained that the first peak originates from C=N bonds and the third peak originates from the incorporation of nitrogen into the graphite like domains

  12. Effects of lithium doping on microstructure, electrical properties, and chemical bonds of sol-gel derived NKN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chun-Cheng [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Department of Mathematic and Physical Sciences, R.O.C. Air Force Academy, Kaohsiung 820, Taiwan (China); Chen, Chan-Ching; Weng, Chung-Ming [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Chu, Sheng-Yuan, E-mail: chusy@mail.ncku.edu.tw [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China); Hong, Cheng-Shong [Department of Electronic Engineering, National Kaohsiung Normal University, Kaohsiung 802, Taiwan (China); Tsai, Cheng-Che [Department of Digital Game and Animation Design, Tung-Fang Design University, Kaohsiung 829, Taiwan (China)

    2015-02-28

    Highly (100/110) oriented lead-free Li{sub x}(Na{sub 0.5}K{sub 0.5}){sub 1−x}NbO{sub 3} (LNKN, x = 0, 0.02, 0.04, and 0.06) thin films are fabricated on Pt/Ti/SiO{sub 2}/Si substrates via a sol-gel processing method. The lithium (Li) dopants modify the microstructure and chemical bonds of the LNKN films, and therefore improve their electrical properties. The optimal values of the remnant polarization (P{sub r} = 14.3 μC/cm{sup 2}), piezoelectric coefficient (d{sub 33} = 48.1 pm/V), and leakage current (<10{sup −5} A/cm{sup 2}) are obtained for a lithium addition of x = 0.04 (i.e., 4 at. %). The observation results suggest that the superior electrical properties are the result of an improved crystallization, a larger grain size, and a smoother surface morphology. It is shown that the ion transport mechanism is dominated by an Ohmic behavior under low electric fields and the Poole-Frenkel emission effect under high electric fields.

  13. Thermal stability and chemical bonding states of AlOxNy/Si gate stacks revealed by synchrotron radiation photoemission spectroscopy

    International Nuclear Information System (INIS)

    He, G.; Toyoda, S.; Shimogaki, Y.; Oshima, M.

    2010-01-01

    Annealing-temperature dependence of the thermal stability and chemical bonding states of AlO x N y /SiO 2 /Si gate stacks grown by metalorganic chemical vapor deposition (MOCVD) using new chemistry was investigated by synchrotron radiation photoemission spectroscopy (SRPES). Results have confirmed the formation of the AlN and AlNO compounds in the as-deposited samples. Annealing the AlO x N y samples in N 2 ambient in 600-800 deg. C promotes the formation of SiO 2 component. Meanwhile, there is no formation of Al-O-Si and Al-Si binding states, suggesting no interdiffusion of Al with the Si substrate. A thermally induced reaction between Si and AlO x N y to form volatile SiO and Al 2 O is suggested to be responsible for the full disappearance of the Al component that accompanies annealing at annealing temperature of 1000 deg. C. The released N due to the breakage of the Al-N bonding will react with the SiO 2 interfacial layer and lead to the formation of the Si 3 -N-O/Si 2 -N-O components at the top of Si substrate. These results indicate high temperature processing induced evolution of the interfacial chemistry and application range of AlO x N y /Si gate stacks in future CMOS devices.

  14. The adsorption of acrolein on a Pt (1 1 1): A study of chemical bonding and electronic structure

    Science.gov (United States)

    Pirillo, S.; López-Corral, I.; Germán, E.; Juan, A.

    2012-12-01

    The adsorption of acrolein on a Pt (1 1 1) surface was studied using ab-initio and semiempirical calculations. Geometry optimization and densities of states (DOS) curves were carried out using the Vienna Ab-initio Simulation Package (VASP) code. We started our study with the preferential geometries corresponding to the different acrolein/Pt (1 1 1) adsorption modes previously reported. Then, we examined the evolution of the chemical bonding in these geometries, using the crystal orbital overlap population (COOP) and overlap population (OP) analysis of selected pairs of atoms. We analyzed the acrolein intramolecular bonds, Pt (1 1 1) superficial bonds and new moleculesbnd surface formed bonds after adsorption. We found that Ptsbnd Pt bonds interacting with the molecule and acrolein Cdbnd O and Cdbnd C bonds are weakened after adsorption; this last bond is significantly linked to the surface. The obtained Csbnd Pt and Osbnd Pt OP values suggest that the most stable adsorption modes are η3-cis and η4-trans, while the η1-trans is the less favored configuration. We also found that C pz orbital and Pt pz and d orbitals participate strongly in the adsorption process.

  15. Crystal structure and chemical bonding of the intermetallic Zintl phase Yb[subscript 11]AlSb[subscript 9

    Energy Technology Data Exchange (ETDEWEB)

    Kastbjerg, Sofie; Uvarov, Catherine A.; Kauzlarich, Susan M.; Chen, Yu-Sheng; Nishibori, Eiji; Spackman, Mark A.; Iversen, Bo Brummerstedt (Aarhus); (UWA); (UCD); (UC); (Nagoya)

    2012-10-09

    High resolution single crystal synchrotron X-ray diffraction data measured at 15(2) K were used to solve the structure of the complex intermetallic Zintl phase, Yb{sub 11}AlSb{sub 9} (space group Iba2), made up of Yb cations and polyanions along with isolated Sb anions. The 15(2) K cell parameters are a = 11.7383(4) {angstrom}, b = 12.3600(4) {angstrom}, c = 16.6796(6) {angstrom}. The temperature dependence of the structure was investigated through high resolution synchrotron powder X-ray diffraction (PXRD) data measured from 90 K to 1000 K. Rietveld refinements of the crystal structure revealed near linear thermal expansion of Yb{sub 11}AlSb{sub 9} with expansion coefficients of 1.49(2) x 10{sup -5} K{sup -1}, 1.71(3) x 10{sup -5} K{sup -1}, 1.13(1) x 10{sup -5} K{sup -1} for a, b and c, respectively. The chemical bonding in Yb{sub 11}AlSb{sub 9} was analyzed using atomic Hirshfeld surfaces, and the analysis supports the presence of the structural elements of Yb cations, [AlSb{sub 4}]{sup 9-} tetrahedra, [Sb{sub 2}]{sup 4-} dimers and isolated Sb{sup 3-} anions. However, indications of interatomic interactions between the Zintl anions and the Yb cations were also observed.

  16. Effects of carbon vacancies on the structures, mechanical properties, and chemical bonding of zirconium carbides: a first-principles study.

    Science.gov (United States)

    Xie, Congwei; Oganov, Artem R; Li, Duan; Debela, Tekalign Terfa; Liu, Ning; Dong, Dong; Zeng, Qingfeng

    2016-04-28

    Interstitial carbides are able to maintain structural stability even with a high concentration of carbon vacancies. This feature provides them with tunable properties through the design of carbon vacancies, and thus making it important to reveal how carbon vacancies affect their properties. In the present study, using first-principles, we have calculated the properties of a number of stable and metastable zirconium carbides ZrC1-x (x = 0 and 1/n, n = 2-8) which were predicted by the evolutionary algorithm USPEX. Effects of carbon vacancies on the structures, mechanical properties, and chemical bonding of these zirconium carbides were systematically investigated. The distribution of carbon vacancies has significant influence on mechanical properties, especially Pugh's ratio. Nonadjacent carbon vacancies enhance Pugh's ratio, while grouped carbon vacancies decrease Pugh's ratio. This is explained by the changes in strength of Zr-C and Zr-Zr bonding around differently distributed carbon vacancies. We further explored the mechanical properties of zirconium carbides with impurities (N and O) by inserting N and O atoms into the sites of carbon vacancies. The enhanced mechanical properties of zirconium carbides were found.

  17. Biomimetic calcium phosphate coatings on recombinant spider silk fibres

    NARCIS (Netherlands)

    Yang, Liang; Hedhammar, My; Blom, Tobias; Leifer, Klaus; Johansson, Jan; Habibovic, Pamela; van Blitterswijk, Clemens

    2010-01-01

    Calcium phosphate ceramic coatings, applied on surfaces of metallic and polymeric biomaterials, can improve their performance in bone repair and regeneration. Spider silk is biocompatible, strong and elastic, and hence an attractive biomaterial for applications in connective tissue repair. Recently,

  18. Ceramic joining

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E. [Sandia National Lab., Albuquerque, NM (United States)

    1996-04-01

    This paper describes the relation between reactions at ceramic-metal interfaces and the development of strong interfacial bonds in ceramic joining. Studies on a number of systems are described, including silicon nitrides, aluminium nitrides, mullite, and aluminium oxides. Joints can be weakened by stresses such as thermal expansion mismatch. Ceramic joining is used in a variety of applications such as solid oxide fuel cells.

  19. Isotopic studies of trans- and cis-HOCO using rotational spectroscopy: Formation, chemical bonding, and molecular structures

    International Nuclear Information System (INIS)

    McCarthy, Michael C.; Martinez, Oscar; Crabtree, Kyle N.; Martin-Drumel, Marie-Aline; McGuire, Brett A.; Stanton, John F.

    2016-01-01

    HOCO is an important intermediate in combustion and atmospheric processes because the OH + CO → H + CO_2 reaction represents the final step for the production of CO_2 in hydrocarbon oxidation, and theoretical studies predict that this reaction proceeds via various intermediates, the most important being this radical. Isotopic investigations of trans- and cis-HOCO have been undertaken using Fourier transform microwave spectroscopy and millimeter-wave double resonance techniques in combination with a supersonic molecular beam discharge source to better understand the formation, chemical bonding, and molecular structures of this radical pair. We find that trans-HOCO can be produced almost equally well from either OH + CO or H + CO_2 in our discharge source, but cis-HOCO appears to be roughly two times more abundant when starting from H + CO_2. Using isotopically labelled precursors, the OH + C"1"8O reaction predominately yields HOC"1"8O for both isomers, but H"1"8OCO is observed as well, typically at the level of 10%-20% that of HOC"1"8O; the opposite propensity is found for the "1"8OH + CO reaction. DO + C"1"8O yields similar ratios between DOC"1"8O and D"1"8OCO as those found for OH + C"1"8O, suggesting that some fraction of HOCO (or DOCO) may be formed from the back-reaction H + CO_2, which, at the high pressure of our gas expansion, can readily occur. The large "1"3C Fermi-contact term (a_F) for trans- and cis-HO"1"3CO implicates significant unpaired electronic density in a σ-type orbital at the carbon atom, in good agreement with theoretical predictions. By correcting the experimental rotational constants for zero-point vibration motion calculated theoretically using second-order vibrational perturbation theory, precise geometrical structures have been derived for both isomers.

  20. BiOBr@SiO2 flower-like nanospheres chemically-bonded on cement-based materials for photocatalysis

    Science.gov (United States)

    Wang, Dan; Hou, Pengkun; Yang, Ping; Cheng, Xin

    2018-02-01

    Endowment of photocatalytic property on the surface of concrete structure can contribute to the self-cleaning of the structure and purification of the polluted environment. We developed a nano-structured BiOBr@SiO2 photocatalyst and innovatively used for surface-treatment of cement-based materials with the hope of attaining the photocatalytic property in visible-light region and surface modification/densification performances. The SiO2 layer on the flower-like BiOBr@SiO2 helps to maintain a stable distribution of the photocatalyst, as well as achieving a chemical bonding between the coating and the cement matrix. Results showed that the color fading rate of during the degradation of Rhodamine B dye of the BiOBr-cem sample is 2 times higher compared with the commonly studied C, N-TiO2-cem sample. The photo-degradation rates of samples BiOBr-cem and BiOBr@SiO2-cem are 93 and 81% within 150 min, respectively, while sample BiOBr@SiO2-cem reveals a denser and smoother surface after curing for 28 days and pore-filling effect at size within 0.01-0.2 μm when compared with untreated samples. Moreover, additional C-S-H gel can be formed due to the pozzolanic reaction between BiOBr@SiO2 and the hardened cement matrix. Both advantages of the BiOBr@SiO2 favor its application for surface-treatment of hardened cement-based material to acquire an improved surface quality, as well as durable photocatalytic functionality.

  1. A DFT investigation on geometry and chemical bonding of isoelectronic Si8N6V-, Si8N6Cr, and Si8N6Mn+ clusters

    Science.gov (United States)

    Tam, Nguyen Minh; Pham, Hung Tan; Cuong, Ngo Tuan; Tung, Nguyen Thanh

    2017-10-01

    The geometric feature and chemical bonding of isoelectronic systems Si8N6Mq (M = V, Cr, Mn and q = -1, 0, 1, respectively) are investigated by means of density-functional-theory calculations. The encapsulated form is found for all ground-state structures, where the metal atom locates at the central site of the hollow Si8N6 cage. The Si8N6 cage is established by adding two Si atoms to a distorted Si6N6 prism, which is a combination of Si4N2 and Si2N4 strings. Chemical bonding of Si8N6Mq systems is explored by using the electron localization indicator and theory of atom in molecule, revealing the vital role of metal center in stabilizing the clusters.

  2. Interfacial characterization of ceramic core materials with veneering porcelain for all-ceramic bi-layered restorative systems.

    Science.gov (United States)

    Tagmatarchis, Alexander; Tripodakis, Aris-Petros; Filippatos, Gerasimos; Zinelis, Spiros; Eliades, George

    2014-01-01

    The aim of the study was to characterize the elemental distribution at the interface between all-ceramic core and veneering porcelain materials. Three groups of all-ceramic cores were selected: A) Glass-ceramics (Cergo, IPS Empress, IPS Empress 2, e-max Press, Finesse); B) Glass-infiltrated ceramics (Celay Alumina, Celay Zirconia) and C) Densely sintered ceramics (Cercon, Procera Alumina, ZirCAD, Noritake Zirconia). The cores were combined with compatible veneering porcelains and three flat square test specimens were produced for each system. The core-veneer interfaces were examined by scanning electron microscopy and energy dispersive x-ray microanalysis. The glass-ceramic systems showed interfacial zones reach in Si and O, with the presence of K, Ca, Al in core and Ca, Ce, Na, Mg or Al in veneer material, depending on the system tested. IPS Empress and IPS Empress 2 demonstrated distinct transitional phases at the core-veneer interface. In the glassinfiltrated systems, intermixing of core (Ce, La) with veneer (Na, Si) elements occurred, whereas an abrupt drop of the core-veneer elemental concentration was documented at the interfaces of all densely sintered ceramics. The results of the study provided no evidence of elemental interdiffusion at the core-veneer interfaces in densely sintered ceramics, which implies lack of primary chemical bonding. For the glass-containing systems (glassceramics and glass-infiltrated ceramics) interdiffusion of the glass-phase seems to play a critical role in establishing a primary bonding condition between ceramic core and veneering porcelain.

  3. [Ceramic posts].

    Science.gov (United States)

    Mainjot, Amélie; Legros, Caroline; Vanheusden, Alain

    2006-01-01

    As a result of ceramics and all-ceram technologies development esthetic inlay core and abutments flooded the market. Their tooth-colored appearance enhances restoration biomimetism principally on the marginal gingiva area. This article reviews indications and types of cores designed for natural teeth and implants.

  4. Relating mechanical properties and chemical bonding in an inorganic-organic framework material: a single-crystal nanoindentation study.

    Science.gov (United States)

    Tan, Jin Chong; Furman, Joshua D; Cheetham, Anthony K

    2009-10-14

    We report the application of nanoindentation and atomic force microscopy to establish the fundamental relationships between mechanical properties and chemical bonding in a dense inorganic-organic framework material: Ce(C(2)O(4))(HCO(2)), 1. Compound 1 is a mixed-ligand 3-D hybrid which crystallizes in an orthorhombic space group, in which its three basic building blocks, i.e. the inorganic metal-oxygen-metal (M-O-M) chains and the two organic bridging ligands, (oxalate and formate) are all oriented perpendicular to one another. This unique architecture enabled us to decouple the elastic and plastic mechanical responses along the three primary axes of a single crystal to understand the contribution associated with stiff vs compliant basic building blocks. The (001)-oriented facet that features rigid oxalate ligands down the c-axis exhibits the highest stiffness and hardness (E approximately 78 GPa and H approximately 4.6 GPa). In contrast, the (010)-oriented facet was found to be the most compliant and soft (E approximately 43 GPa and H approximately 3.9 GPa), since the formate ligand, which is the more compliant building block within this framework, constitutes the primary linkages down the b-axis. Notably, intermediate stiffness and hardness (E approximately 52 GPa and H approximately 4.1 GPa) were measured on the (100)-oriented planes. This can be attributed to the Ce-O-Ce chains that zigzag down the a-axis (Ce...Ce metal centers form an angle of approximately 132 degrees) and also the fact that the 9-coordinated CeO(9) polyhedra are expected to be geometrically more compliant. Our results present the first conclusive evidence that the crystal orientation dominated by inorganic chains is not necessarily more robust from the mechanical properties standpoint. Rigid organic bridging ligands (such as oxalate), on the other hand, can be used to produce greater stiffness and hardness properties in a chosen crystallographic orientation. This study demonstrates that

  5. [Ceramic brackets].

    Science.gov (United States)

    Mølsted, K

    1992-01-01

    Because of the many drawbacks of the hard and brittle material, ceramic brackets should not be used uncritically for orthodontic treatments. If ceramic brackets are used, the following guidelines should be observed: 1. If large and complicated tooth movements are involved, conventional bracket systems should be considered. 2. Occlusion on ceramic brackets is to be avoided. 3. Sharp instruments should be used with extreme care to avoid scratching the ceramic surface. Metal ligatures must not be used. 4. The length of the treatment is extended, probably because of the increased friction. 5. The problems connected with removing the brackets have not yet been solved. Be particularly careful of weakened teeth. 6. Esthetically, ceramic brackets function satisfactorily, but transparent elastic ligatures do not. They rapidly become discoloured and need frequent replacement. Nor are there as yet any "invisible arch wires", apart from some few, extremely flexible "white" arch wires. The ceramic bracket has no doubt come to stay, but there have been many difficulties in the "running-in" period, and the problems are far from solved yet. New ceramic brackets are coming onto the market all the time, and only future clinical studies can show whether they will become a genuine alternative to the conventional bracket.

  6. Oxide ceramics

    International Nuclear Information System (INIS)

    Ryshkewitch, E.; Richerson, D.W.

    1985-01-01

    The book explores single-phase ceramic oxide systems from the standpoint of physical chemistry and technology. This second edition also focuses on advances in technology since publication of the original edition. These include improvements in raw materials and forming and sintering techniques, and the major role that oxide ceramics have had in development of advanced products and processes. The text is divided into five major sections: general fundamentals of oxide ceramics, advances in aluminum oxide technology, advances in zirconia technology, and advances in beryllium oxide technology

  7. Tailored ceramics

    International Nuclear Information System (INIS)

    Harker, A.B.

    1988-01-01

    In polyphase tailored ceramic forms two distinct modes of radionuclide immobilization occur. At high waste loadings the radionuclides are distributed through most of the ceramic phases in dilute solid solution, as indicated schematically in this paper. However, in the case of low waste loadings, or a high loading of a waste with low radionuclide content, the ceramic can be designed with only selected phases containing the radionuclides. The remaining material forms nonradioactive phases which provide a degree of physical microstructural isolation. The research and development work with polyphase ceramic nuclear waste forms over the past ten years is discussed. It has demonstrated the critical attributes which suggest them as a waste form for future HLW disposal. From a safety standpoint, the crystalline phases in the ceramic waste forms offer the potential for demonstrable chemical durability in immobilizing the long-lived radionuclides in a geologic environment. With continued experimental research on pure phases, analysis of mineral analogue behavior in geochemical environments, and the study of radiation effects, realistic predictive models for waste form behavior over geologic time scales are feasible. The ceramic forms extend the degree of freedom for the economic optimization of the waste disposal system

  8. Light weight phosphate cements

    Science.gov (United States)

    Wagh, Arun S.; Natarajan, Ramkumar,; Kahn, David

    2010-03-09

    A sealant having a specific gravity in the range of from about 0.7 to about 1.6 for heavy oil and/or coal bed methane fields is disclosed. The sealant has a binder including an oxide or hydroxide of Al or of Fe and a phosphoric acid solution. The binder may have MgO or an oxide of Fe and/or an acid phosphate. The binder is present from about 20 to about 50% by weight of the sealant with a lightweight additive present in the range of from about 1 to about 10% by weight of said sealant, a filler, and water sufficient to provide chemically bound water present in the range of from about 9 to about 36% by weight of the sealant when set. A porous ceramic is also disclosed.

  9. [Effects of sandblasting on surface character and resin bond of zirconia ceramic].

    Science.gov (United States)

    Meng, Xiang-Feng; Xie, Zhi-Gang; Chen, Yuan-Hua; Gu, Ning

    2011-06-01

    To evaluate the effect of Al2O3 particles sandblasting on the surface roughness, element composition and resin bond durability of zirconia ceramic. Sixty 2.5 mm thick computer aided design and computer aided manufacture (CAD/CAM) zirconia ceramic (Vita Inceram YZ) plates were fired, polished and cleaned. Half of polished ceramic plates was sandblasted with 50 µm alumina particles at 0.3 MPa for 20 s. The surface roughness of polished and sandblasted ceramic surface were measured by 3D-laser scanning microscope, and the surface element weight and atom ratio of the ceramic surface were measured by energy disperse spectroscopy (EDS). Then polished and sandblasted ceramic plates were randomized into six groups. In Group 1 and 2 the polished and sandblasted ceramic plates were bonded irrespectively with conventional resin cement (DUOLINK). In Group 3 and 4 the ceramic plates were bonded with resin cement containing MDP (Panavia F), In Group 5 and 6 the specimens were pretreated with silane coupler acitivated by MDP (Clearfil Ceramic Primer), then bond with Panavia F. The specimens of each test group were then divided into two subgroups, and to received shear test after 0 and 10 000 time thermal cycle. The data was analyzed by one-way ANOVA and independent t test. Comparing with polishing, sandblasting reduced the oxygen atom and weight ratio of zirconia ceramic surface (P ceramic plates and resin cement in all test groups decreased after thermocycling (P ceramic and resin cement containing MDP, not only by increasing the roughness and area of ceramic surface, but also by changing its surface element composition to obtain more chemical bond.

  10. Structural Ceramics Database

    Science.gov (United States)

    SRD 30 NIST Structural Ceramics Database (Web, free access)   The NIST Structural Ceramics Database (WebSCD) provides evaluated materials property data for a wide range of advanced ceramics known variously as structural ceramics, engineering ceramics, and fine ceramics.

  11. High pressure stability analysis and chemical bonding of Ti{sub 1-x}Zr{sub x}N alloy: A first principle study

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Mamta; Gupta, Dinesh C., E-mail: sosfizix@gmail.com, E-mail: mamta-physics@yahoo.co.in [Condensed Matter Theory Group, School of Studies in Physics, Jiwaji University, Gwalior – 474 011 (India)

    2016-05-23

    First-principles pseudo-potential calculations have been performed to analyze the stability of Ti{sub 1-x}Zr{sub x}N alloy under high pressures. The first order phase transition from B1 to B2 phase has been observed in this alloy at high pressure. The variation of lattice parameter with the change in concentration of Zr atom in Ti{sub 1-x}Zr{sub x}N is also reported in both the phases. The calculations for density of states have been performed to understand the alloying effects on chemical bonding of Ti-Zr-N alloy.

  12. Mechanical properties investigation on single-wall ZrO2 nanotubes: A finite element method with equivalent Poisson's ratio for chemical bonds

    Science.gov (United States)

    Yang, Xiao; Li, Huijian; Hu, Minzheng; Liu, Zeliang; Wärnå, John; Cao, Yuying; Ahuja, Rajeev; Luo, Wei

    2018-04-01

    A method to obtain the equivalent Poisson's ratio in chemical bonds as classical beams with finite element method was proposed from experimental data. The UFF (Universal Force Field) method was employed to calculate the elastic force constants of Zrsbnd O bonds. By applying the equivalent Poisson's ratio, the mechanical properties of single-wall ZrNTs (ZrO2 nanotubes) were investigated by finite element analysis. The nanotubes' Young's modulus (Y), Poisson's ratio (ν) of ZrNTs as function of diameters, length and chirality have been discussed, respectively. We found that the Young's modulus of single-wall ZrNTs is calculated to be between 350 and 420 GPa.

  13. [Biomechanic and histomorphometric studies of HIP titanium glass ceramic, a new implant material, compared with glass ceramics, titanium and titanium alloy].

    Science.gov (United States)

    Schmitz, H J; Fritz, T R; Fuhrmann, G; Gross, U; Strunz, V

    1990-01-01

    Interfacial tensile strength and quantitative histomorphological properties of alloplastic implant materials for hard tissue application were studied in animal models. Physico-chemical bonding in the order of 1 N/mm2 of bone to glass-ceramic (Ceravital) was demonstrated independent of magnitude of surface roughness with mineralized bone in excess of 80% at the implant interface. No bone-bonding, but contact of mineralized bone at the metal surface was observed in pure titanium and titanium alloys (Ti6Al4V, Ti5Al2, 5Fe) with smooth surfaces. Rough or porous surfaced specimens, however, exhibited mechanical interlocking and interdigitation, thus yielding interfacial tensile strength of up to 4 N/mm2 in geometrically porous or madreporic surfaces. The new composite material HIP-Titanium-glass-ceramic (Ceravital) displayed physico-chemical bonding to bone as well as mechanical interdigitation within the secondary porous structure, thus giving support to expectations that HIP-Titanium-glass-ceramic coated implants should perform superior than bulk materials.

  14. (IV) phosphates

    Indian Academy of Sciences (India)

    M(IV) phosphates of the class of tetravalent metal acid (TMA) salts where M (IV) = Zr, Ti, Sn has been synthesized by the sol-gel method. These materials have been characterized for elemental analysis (ICP-AES), thermal analysis (TGA, DSC), X-ray analysis and FTIR spectroscopy. Chemical resistivity of these materials ...

  15. The precursors effects on biomimetic hydroxyapatite ceramic powders.

    Science.gov (United States)

    Yoruç, Afife Binnaz Hazar; Aydınoğlu, Aysu

    2017-06-01

    In this study, effects of the starting material on chemical, physical, and biological properties of biomimetic hydroxyapatite ceramic powders (BHA) were investigated. Characterization and chemical analysis of BHA powders were performed by using XRD, FT-IR, and ICP-AES. Microstructural features such as size and morphology of the resulting BHA powders were characterized by using BET, nano particle sizer, pycnometer, and SEM. Additionally, biological properties of the BHA ceramic powders were also investigated by using water-soluble tetrazolium salts test (WST-1). According to the chemical analysis of BHA ceramic powders, chemical structures of ceramics which are prepared under different conditions and by using different starting materials show differences. Ceramic powders which are produced at 80°C are mainly composed of hydroxyapatite, dental hydroxyapatite (contain Na and Mg elements in addition to Ca), and calcium phosphate sulfide. However, these structures are altered at high temperatures such as 900°C depending on the features of starting materials and form various calcium phosphate ceramics and/or their mixtures such as Na-Mg-hydroxyapatite, hydroxyapatite, Mg-Whitlockit, and chloroapatite. In vitro cytotoxicity studies showed that amorphous ceramics produced at 80°C and ceramics containing chloroapatite structure as main or secondary phases were found to be extremely cytotoxic. Furthermore, cell culture studies showed that highly crystalline pure hydroxyapatite structures were extremely cytotoxic due to their high crystallinity values. Consequently, the current study indicates that the selection of starting materials which can be used in the production of calcium phosphate ceramics is very important. It is possible to produce calcium phosphate ceramics which have sufficient biocompatibility at physiological pH values and by using appropriate starting materials. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Ceramic Seal.

    Energy Technology Data Exchange (ETDEWEB)

    Smartt, Heidi A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Romero, Juan A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Custer, Joyce Olsen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hymel, Ross W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Krementz, Dan [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Gobin, Derek [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Harpring, Larry [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Martinez-Rodriguez, Michael [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Varble, Don [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); DiMaio, Jeff [Tetramer Technologies, Pendleton, SC (United States); Hudson, Stephen [Tetramer Technologies, Pendleton, SC (United States)

    2016-11-01

    Containment/Surveillance (C/S) measures are critical to any verification regime in order to maintain Continuity of Knowledge (CoK). The Ceramic Seal project is research into the next generation technologies to advance C/S, in particular improving security and efficiency. The Ceramic Seal is a small form factor loop seal with improved tamper-indication including a frangible seal body, tamper planes, external coatings, and electronic monitoring of the seal body integrity. It improves efficiency through a self-securing wire and in-situ verification with a handheld reader. Sandia National Laboratories (SNL) and Savannah River National Laboratory (SRNL), under sponsorship from the U.S. National Nuclear Security Administration (NNSA) Office of Defense Nuclear Nonproliferation Research and Development (DNN R&D), have previously designed and have now fabricated and tested Ceramic Seals. Tests have occurred at both SNL and SRNL, with different types of tests occurring at each facility. This interim report will describe the Ceramic Seal prototype, the design and development of a handheld standalone reader and an interface to a data acquisition system, fabrication of the seals, and results of initial testing.

  17. Microcracking in ceramics and acoustic emission

    International Nuclear Information System (INIS)

    Subbarao, E.C.

    1991-01-01

    One of the limitations in the use of ceramics in critical applications is due to the presence of microcracks, which may arise from differential thermal expansion and phase changes, among others. Acoustic emission signals occur when there are abrupt microdeformations in a material and thus offer a convenient means of non-destructive detection of microcracking. Examples of a study of acoustic emission from microcracking due to anisotropic thermal expansion in low thermal expansion single phase ceramics such as niobia and sodium zirconium phosphate ceramics and due to phase changes in zirconia and superconducting YBa 2 Cu 3 Osub(7-x) ceramics are presented, together with the case of lead titanate ceramics, which exhibits both a phase change (paraelectric to ferroelectric) and an anisotropic thermal expansion. The role of grain size on the extent of microcracking is illustrated in the case of niobia ceramics. Some indirect evidence of healing of microcracks on heating niobia and lead titanate ceramics is presented from the acoustic emission results. (author). 69 refs., 9 figs

  18. Investigation of Phosphate Retention in some Allophanic and Non-Allophanic Nano-Clays from Karaj Formation

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Monajjem

    2017-02-01

    Full Text Available Introduction: Nanoclays, due to their high specific surface area (SSA chemical and mechanical stabilities, and a variety of surface and structural properties are widely applied. Some of their applications are using them as nano composite polymers, heavy metal ions absorbents, catalysts, photochemical reaction fields, ceramics, paper fillings and coatings, sensors and biosensors. Nano clays and Clays are the most important components constructing soil ecosystems. The physical and chemical properties of soils are mainly depending on the type and amount their clay fraction pertaining to considerable nanoclays. Nano clays have been frequently used to eliminate environmental contaminants from soil and water. Nano clays have also an effective role in the phosphate sorption and desorption from soil solution. Phosphate retention is highly affected by the chemical bonds of the materials, cristalographic properties and pH. In clay size particles there are different structures of nano particles such as alominosilicates with nano ball and nano tube construction. Soils with andic properties have amorphous clay minerals such as allophone. Allophane has a diameter of 3 to 5 nano meter under a transmission electron microscope (TEM and its atomic Si/Al ratio ranges between 0.5 and 1. Allophane shows variable charge characteristics and high selectivity for divalent cations, and is highly reactive with phosphate. Materials and Methods: The objective of this research was to inspect the effect of soil components particularly clay and nanoclay on the sorption of phosphate. To achieve this goal, we studied the amount of phosphate sorption by the natural nanoclays. Samples with andic and vitric properties which were previously formed on volcanic ash in Karaj were chosen in 5 pedons as two Andic ( > 5 percent volcanic glass, > 25 percent P retention, pH NaF > 8.6 and Alo +½ Feo > 0.4 and non Andic soils.. After removal of organic materials, soluble salts, carbonates

  19. First-principles investigation of the structure and synergistic chemical bonding of Ag and Mg at the Al | Ω interface in a Al-Cu-Mg-Ag alloy

    International Nuclear Information System (INIS)

    Sun Lipeng; Irving, Douglas L.; Zikry, Mohammed A.; Brenner, D.W.

    2009-01-01

    Density functional theory was used to characterize the atomic structure and bonding of the Al | Ω interface in a Al-Cu-Mg-Ag alloy. The most stable interfacial structure was found to be connected by Al-Al bonds with a hexagonal Al lattice on the surface of the Ω phase sitting on the vacant hollow sites of the Al {1 1 1} matrix plane. The calculations predict that when substituted separately for Al at this interface, Ag and Mg do not enhance the interface stability through chemical bonding. Combining Ag and Mg, however, was found to chemically stabilize this interface, with the lowest-energy structure examined being a bi-layer with Ag atoms adjacent to the Al matrix and Mg adjacent to the Ω phase. This study provides an atomic arrangement for the interfacial bi-layer observed experimentally in this alloy.

  20. Effect of the valence electron concentration on the bulk modulus and chemical bonding in Ta2AC and Zr2AC (A=Al, Si, and P)

    International Nuclear Information System (INIS)

    Schneider, Jochen M.; Music, Denis; Sun Zhimei

    2005-01-01

    We have studied the effect of the valence electron concentration, on the bulk modulus and the chemical bonding in Ta 2 AC and Zr 2 AC (A=Al, Si, and P) by means of ab initio calculations. Our equilibrium volume and the hexagonal ratio (c/a) agree well (within 2.7% and 1.2%, respectively) with previously published experimental data for Ta 2 AlC. The bulk moduli of both Ta 2 AC and Zr 2 AC increase as Al is substituted with Si and P by 13.1% and 20.1%, respectively. This can be understood since the substitution is associated with an increased valence electron concentration, resulting in band filling and an extensive increase in cohesion

  1. Evolution of chemical bonding and electron density rearrangements during D(3h) → D(3d) reaction in monolayered TiS2: a QTAIM and ELF study.

    Science.gov (United States)

    Ryzhikov, Maxim R; Slepkov, Vladimir A; Kozlova, Svetlana G; Gabuda, Svyatoslav P

    2014-08-15

    Monolayered titanium disulfide TiS2, a prospective nanoelectronic material, was previously shown to be subject to an exothermic solid-state D3h -D3d reaction that proceeds via a newly discovered transition state. Here, we study the reaction in detail using topological methods of quantum chemistry (quantum theory of atoms in molecules and electron localization function analysis) and show how electron density and chemical bonding between the atoms change in the course of the reaction. The reaction is shown to undergo a series of topological catastrophes, associated with elementary chemical events such as break and formation of bonds (including the unexpected formation of S-S bonding between sulfur layers), and rearrangement of electron density of outer valence and core shells. Copyright © 2014 Wiley Periodicals, Inc.

  2. On the nature of chemical bonding in phase change materials on the base of (GeTe)m-(Sb2Te3)n alloys

    Science.gov (United States)

    Orlov, V. G.; Sergeev, G. S.

    2017-05-01

    Despite widespread use of pseudobinary alloys (GeTe)m-(Sb2Te3)n for manufacture of optical data storage memory interpretation of very fast crystallization and amorphization processes in these phase change materials (PCM) is still under discussion. To clarify the role of electron subsystem in unusual properties of PCM and to reveal the nature of their chemical bonding electron band structure calculations using WIEN2k program code were performed for compounds GeTe, Sb2Te3, GeSb2Te4 and Ge2Sb2Te5. Parameters of bond critic points in the electron density distribution for studied compounds and some related substances were obtained and analyzed. Characteristics of bond critic points inherent to basic PCM are established. They can be used as guide parameters for searching new perspective materials.

  3. Electronic and Structural Evolution and Chemical Bonding in Ditungsten Oxide Clusters: W2On- and W2On (n = 1-6)

    International Nuclear Information System (INIS)

    Zhai, Hua Jin; Huang, Xin; Cui, Lifeng; Li, Xi; Li, Jun; Wang, Lai S.

    2005-01-01

    We report a systematic and comprehensive investigation of the electronic structures and chemical bonding in a series of ditungsten oxide clusters, W 2 O n - and W 2 O n (n = 1-6), using anion photoelectron spectroscopy and density functional theory (DFT) calculations. Well-resolved photoelectron spectra were obtained at several photon energies (2.331, 3.496, 4.661, 6.424, and 7.866 eV) and W 5d-based spectral features were clearly observed and distinguished from O 2p-based features. More complicated spectral features were observed for the oxygen-deficient clusters due to the W 5d electrons. With increasing oxygen content in W 2 O n - , the photoelectron spectra were observed to shift gradually to higher binding energies, accompanied by a decreasing number of W 5d-derived features. A behavior of sequential oxidation as a result of charge transfers from W to O was clearly observed. A large energy gap (2.8 eV) was observed in the spectrum of W 2 O 6 - , indicating the high electronic stability of the stoichiometric W 2 O 6 molecule. Extensive DFT calculations were carried out to search for the most stable structures of both the anion and neutral clusters. Time-dependent DFT method was used to compute the vertical detachment energies and compare to the experimental data. Molecular orbitals were used to analyze the chemical bonding in the ditungsten oxide clusters and elucidate their electronic and structural evolution

  4. The chemical bonds effect of anthocyanin and chlorophyll dyes on TiO2 for dye-sensitized solar cell (DSSC)

    Science.gov (United States)

    Ahliha, A. H.; Nurosyid, F.; Supriyanto, A.; Kusumaningsih, T.

    2017-11-01

    Anthocyanin and chlorophyll dyes have been blended as the photosensitizer of Dye-Sensitized Solar Cell (DSSC). The results study showed the effect of chemical bond dyes on TiO2 and the efficiency of DSSC. Ratio blend of the anthocyanin and chlorophyll dyes are 1:1. The absorbance of dyes and TiO2 were characterized using UV-Vis Spectrophotometer. The chemical bonds contained in TiO2-dyes were characterized using FT-IR spectrophotometer. The efficiency of DSSC was calculated using I-V meter. The absorption spectra of chlorophyll: anthocyanin blend dye solutions and TiO2 films can increase after the dye adsorption. Absorbance characterization of anthocyanin and chlorophyll dye blend solutions showed three peaks at the wavelength of 412 nm; 535.5 nm; and 656.5 nm. Absorbance characterization of spinach before being blend with anthocyanin dyes solutions showed two peaks at the wavelength of 431 nm and 665.5 nm. The absorption spectra of TiO2 films can increase after the dyes adsorption at the wavelength of 400 nm. FT-IR spectra of TiO2 founded the functional groups C-Br, C=C, and O-H. The functional groups founded in anthocyanin: chlorophyll dye blended on the surface of TiO2 are C-Br, C-O, O-H, C-H, C=C, C=O, and O-H. The result showed that the greatest efficiency of 0.0544% at dye red cabbage-spinach. Adsorption blends of anthocyanin and chlorophyll dyes on the surface of TiO2 can be used as the photosensitizer for DSSC.

  5. The chemical bonds effect of Amaranthus hybridus L. and Dracaena Angustifolia on TiO2 as photo-sensitizer for dye-sensitized solar Cells (DSSC)

    Science.gov (United States)

    Ahliha, A. H.; Nurosyid, F.; Supriyanto, A.

    2017-08-01

    Dye-Sensitized Solar Cells (DSSC) consists of a working electrode, dye, electrolyte, and a counter electrode. The paper showed the effect of chemical bonds Dracaena Angustifolia (suji leaves) and Amaranthus Hybridus L. (spinach leaves) on TiO2 for application in DSSC. Dracaena Angustifolia (suji leaves) and Amaranthus Hybridus L. (spinach leaves) were extracted using acetone solvent as a dye containing chlorophyll, the absorbance spectrum of the dye and TiO2 were characterized using Uv-visible spectrophotometer 1601 PC, the chemical bonds contained in TiO2-dye was characterized using FT-IR spectrophotometer Shimadzu Prestige 21. The efficiency of DSSC was calculated using I-V Keithley 2602A. Absorbance characterization of dye Dracaena Angustifolia showed two peaks at the wavelength of 665,5 nm and 412 nm. The absorbance peaks of dye Amaranthus Hybridus L. at the wavelength of 664 nm and 412,5 nm. FT-IR characterization of TiO2 founded the functional groups C=C-C, C=C-H, C-O, C-H, C=C, C-H aliphatic, and O-H. Dye Amaranthus Hybridus L. obtained functional groups C=C-C, C=C-H, C-O, C-H, C=C, C=O, C-H aliphatic, and O-H. Dye Dracaena Angustifolia obtained functional groups were identified as C=C-C, C=C-H, C-O, C-H, C=C, C-H aliphatic, and O-H. DSSC efficiency with Amaranthus Hybridus L. and Dracaena Angustifolia dyes of 0,063% and 0,058% respectively

  6. The effects of reasoning, use of models, sex type, and their interactions on posttest achievement in chemical bonding after constant instruction

    Science.gov (United States)

    Staver, John R.; Halsted, Douglas A.

    The purpose of the authors in this study was to determine the effects of reasoning, use of models during testing, and sex type on posttest achievement in chemical bonding under controlled instruction. Eighty-four high school students taking chemistry were randomly assigned within their classes to models and no models groups for the posttest. Reasoning capabilities were assessed by the Piagetian Logical Operations Test (PLOT) (Staver & Gabel, JRST, Vol. 16, No. 6, 1979), prior to instruction. All students then received the same instruction on chemical bonding which included teacher demonstrations of concepts with three-dimensional molecular models, interspersed teacher questions during the introduction and development of concepts, student manipulation of three-dimensional molecular models during laboratory experiments, and text reading assignments on concepts prior to their instruction in class. The posttest on molecular geometry and shape contained three sections requiring memory and application (Bloom, Taxonomy of educational objective, handbook I: Cognitive domain. New York: David McKay, 1956). Data were analyzed by regression (Nie et al., Statistical package for the social sciences, 2nd ed. New York: McGraw-Hill, 1975). Results indicate that reasoning accounted for a significant portion (p sex type did not account for a significant (p > 0.05) portion of the variance on total scores or any section of posttest. The three-way interaction of reasoning, model usage, and sex type accounted for a significant portion (p < 0.05) of the variance in total scores, and in the memory and application sections of the posttest. Discussion focused on the results, conclusions, and implications for science teaching.

  7. Effect of Lithium Disilicate Reinforced Liner Treatment on Bond and Fracture Strengths of Bilayered Zirconia All-Ceramic Crown

    Directory of Open Access Journals (Sweden)

    Yong-Seok Jang

    2018-01-01

    Full Text Available This study was performed to evaluate the effect of a lithium-disilicate spray-liner application on both the bond strength between zirconia cores and heat-pressed lithium-disilicate glass-ceramic veneers, and the fracture strength of all-ceramic zirconia crowns. A lithium-disilicate reinforced liner was applied on the surface of a zirconia core and lithium-disilicate glass-ceramic was veneered on zirconia through heat press forming. Microtensile and crown fracture tests were conducted in order to evaluate, respectively, the bonding strength between the zirconia cores and heat pressed lithium-disilicate glass-ceramic veneers, and the fracture strength of bilayered zirconia all-ceramic crowns. The role of lithium-disilicate spray-liner at the interface between zirconia and lithium-disilicate glass-ceramic veneers was investigated through surface and cross-sectional analyses. We confirmed that both the mean bonding strength between the zirconia ceramics and lithium-disilicate glass-ceramic veneers and the fracture strength of the liner-treated groups were significantly higher than those of the untreated groups, which resulted, on the one hand, from the chemical bonding at the interface of the zirconia and lithium-disilicate liner, and, on the other, from the existence of a microgap in the group not treated with liner.

  8. Effect of pH values on surface modification and solubility of phosphate bioglass-ceramics in the CaO-P 2O 5-Na 2O-SrO-ZnO system

    Science.gov (United States)

    Li, Xudong; Cai, Shu; Zhang, Wenjuang; Xu, Guohua; Zhou, Wei

    2009-08-01

    The bioactive glass-ceramics in the CaO-P 2O 5-Na 2O-SrO-ZnO system were synthesized by the sol-gel technique, and then chemically treated at different pH values to study the solubility and surface modification. Samples sintered at 650 °C for 4 h consisted of the crystalline phase β-Ca 2P 2O 7 and the glass matrix. After soaking in the solution at pH 1.0, the residual glass matrix on the surface appeared entirely dissolved and no new phase could be detected. Whereas at pH 3.0, web-like layer exhibiting peaks corresponding to CaP 2O 6 was formed and covered the entire surface of the sample. When conducted at pH 10.0, only part of the glass matrix was dissolved and a new phase Ca 4P 6O 19 was precipitated, forming the petaline layer. The chemical treatment can easily change the surface morphologies and phase composition of this bioactive glass-ceramics. The higher level of surface roughness resulting from the new-formed layer would improve the interface bonding and benefit for cell adhesion.

  9. Alkali corrosion resistant coatings and ceramic foams having superfine open cell structure and method of processing

    Science.gov (United States)

    Brown, Jr., Jesse J.; Hirschfeld, Deidre A.; Li, Tingkai

    1993-12-07

    Alkali corrosion resistant coatings and ceramic foams having superfine open cell structure are created using sol-gel processes. The processes have particular application in creating calcium magnesium zirconium phosphate, CMZP, coatings and foams.

  10. In vivo performance of microstructured calcium phosphate formulated in novel water-free carriers

    NARCIS (Netherlands)

    Davison, N.L.; Yuan, Huipin; de Bruijn, Joost Dick; Barrere-de Groot, F.YF.

    2012-01-01

    Osteoinductive calcium phosphate (CaP) ceramics can be combined with polymeric carriers to make shapeable bone substitutes as an alternative to autologous bone; however, carriers containing water may degrade the ceramic surface microstructure, which is crucial to bone formation. In this study five

  11. Effects of calcium phosphate composition in sputter coatings on in vitro and in vivo performance

    NARCIS (Netherlands)

    Urquia Edreira, E.R.; Wolke, J.G.C.; Aldosari, A.A.; Al-Johany, S.S.; Anil, S.; Jansen, J.A.; Beucken, J.J.J.P van den

    2015-01-01

    Calcium phosphate (CaP) ceramic coatings have been used to enhance the biocompatibility and osteoconductive properties of metallic implants. The chemical composition of these ceramic coatings is an important parameter, which can influence the final bone performance of the implant. In this study, the

  12. Effect of binder burnout on the sealing performance of glass ceramics for solid oxide fuel cells

    Science.gov (United States)

    Ertugrul, Tugrul Y.; Celik, Selahattin; Mat, Mahmut D.

    2013-11-01

    The glass ceramics composite sealants are among few materials suitable for the solid oxide fuel cells (SOFC) due to their high operating temperatures (600 °C-850 °C). The glass ceramics chemically bond to both the metallic interconnector and the ceramic electrolyte and provide a gas tight connection. A careful and several stages manufacturing procedure is required to obtain a gas tight sealing. In this study, effects of binder burnout process on the sealing performance are investigated employing commercially available glass ceramic powders. The glass ceramic laminates are produced by mixing glass ceramic powders with the organic binders and employing a tape casting method. The laminates are sandwiched between the metallic interconnectors of an SOFC cell. The burnout and subsequent sealing quality are analyzed by measuring leakage rate and final macrostructure of sealing region. The effects of heating rate, dead weight load, solid loading, carrier gas and their flow rates are investigated. It is found that sealing quality is affected from all investigated parameters. While a slower heating rate is required for a better burnout, the mass flow rate of sweep gas must be adequate for removal of the burned gas. The leakage rate is reduced to 0.1 ml min-1 with 2 °C min-1 + 1 °C min-1 heating rate, 86.25% solid loading, 200 N dead weight load and 500 ml min-1 sweep gas flow rate.

  13. Monolithic ceramics

    Science.gov (United States)

    Herbell, Thomas P.; Sanders, William A.

    1992-01-01

    A development history and current development status evaluation are presented for SiC and Si3N4 monolithic ceramics. In the absence of widely sought improvements in these materials' toughness, and associated reliability in structural applications, uses will remain restricted to components in noncritical, nonman-rated aerospace applications such as cruise missile and drone gas turbine engine components. In such high temperature engine-section components, projected costs lie below those associated with superalloy-based short-life/expendable engines. Advancements are required in processing technology for the sake of fewer and smaller microstructural flaws.

  14. Analyses of the modulatory effects of antibacterial silver doped calcium phosphate-based ceramic nano-powder on proliferation, survival, and angiogenic capacity of different mammalian cells in vitro.

    Science.gov (United States)

    Bostancıoğlu, R Beklem; Peksen, Ceren; Genc, Hatice; Gürbüz, Mevlüt; Karel, Filiz Bayrakçı; Koparal, A Savas; Dogan, Aydin; Kose, Nusret; Koparal, A Tansu

    2015-08-26

    In this study, the antibacterial, cytotoxic, and angiogenic activities of silver doped calcium phosphate-based inorganic powder (ABT or PAG) were systematically investigated. ABT powders containing varying silver content were fabricated using a wet chemical manufacturing method. Antibacterial efficiencies of the ABT powders were investigated using a standard test with indicator bacteria and yeast. The cytotoxic effects of ABT on three different fibroblast cells and human umbilical vein endothelial cells (HUVECs) were assessed using MTT assay. ABT powder exhibits concentration-related cytotoxicity characteristics. Apoptotic activity, attachment capability, and wound healing effects were examined on fibroblasts. The angiogenic activity of ABT was investigated by tube formation assay in HUVECs; 10 μg ml(-1) and 100 μg ml(-1) concentrations of the highest metal ion content of ABT did not disrupt the tube formation of HUVECs. All these tests showed that ABT does not compromise the survival of the cells and might impose regeneration ability to various cell types. These results indicate that silver doped calcium phosphate-based inorganic powder with an optimal silver content has good potential for developing new biomaterials for implant applications.

  15. Obtain ceramic porous alumina-zirconia by replica method calcium phosphate coated; Oobtencao de ceramicas porosas de alumina-zirconia pelo metodo da replica recobertas com fosfato de calcio

    Energy Technology Data Exchange (ETDEWEB)

    Silva, A.D.R.; Rigoli, W.R.; Osiro, Denise; Pallone, E.M.J.A., E-mail: adinizrs@yahoo.com.br [Universidade de Sao Paulo (FZEA/USP), Pirassununga, SP (Brazil). Faculdade de Zootecnia e Engenharia de Alimentos; Lobo, A.O. [Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, SP (Brazil)

    2016-07-01

    Biomaterials used in bone replacement, including porous bioceramics, are often used as support structure for bone formation and repair. The porous bioceramics are used because present features as biocompatibility, high porosity and pore morphology that confer adequate mechanical strength and induce bone growth. In this work were obtained porous specimens of alumina containing 5% by inclusion of volume of zirconia produced by the replica method. The porous specimens had its surface chemically treated with phosphoric acid and were coated with calcium phosphate. The coating was performed using the biomimetic method during 14 days and an initial pH of 6.1. The porous specimens were characterized using the follow techniques: porosity, axial compression tests, microtomography, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and pH measurements SBF solution. The results showed specimens with suitable pore morphology for application as biomaterial, and even a reduced time of incubation favored the calcium phosphate phases formation on the material surfaces. (author)

  16. Exploring Conceptual Frameworks of Models of Atomic Structures and Periodic Variations, Chemical Bonding, and Molecular Shape and Polarity: A Comparison of Undergraduate General Chemistry Students with High and Low Levels of Content Knowledge

    Science.gov (United States)

    Wang, Chia-Yu; Barrow, Lloyd H.

    2013-01-01

    The purpose of the study was to explore students' conceptual frameworks of models of atomic structure and periodic variations, chemical bonding, and molecular shape and polarity, and how these conceptual frameworks influence their quality of explanations and ability to shift among chemical representations. This study employed a purposeful sampling…

  17. Atomic Structure and Valence: Level II, Unit 10, Lesson 1; Chemical Bonding: Lesson 2; The Table of Elements: Lesson 3; Electrolysis: Lesson 4. Advanced General Education Program. A High School Self-Study Program.

    Science.gov (United States)

    Manpower Administration (DOL), Washington, DC. Job Corps.

    This self-study program for high-school level contains lessons on: Atomic Structure and Valence, Chemical Bonding, The Table of Elements, and Electrolysis. Each of the lessons concludes with a Mastery Test to be completed by the student. (DB)

  18. Anatomy of Bond Formation. Domain-Averaged Fermi holes as a Tool for the Study of the Nature of the Chemical Bonding in Li2, Li4 and F2

    Czech Academy of Sciences Publication Activity Database

    Ponec, Robert; Cooper, D.L.

    2007-01-01

    Roč. 111, č. 44 (2007), s. 11294-11301 ISSN 1089-5639 R&D Projects: GA AV ČR IAA4072403 Institutional research plan: CEZ:AV0Z40720504 Keywords : chemical bonding * domain averaged fermi hole * non-nuclear attractors Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.918, year: 2007

  19. Reduction-oxidation Enabled Glass-ceramics to Stainless Steel Bonding Part I: screening of doping oxidants

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Steve Xunhu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Lithium silicate-based glass-ceramics with high coefficients of thermal expansion, designed to form matched hermetic seals in 304L stainless steel housing, show little evidence of interfacial chemical bonding, despite extensive inter-diffusion at the glass-ceramic-stainless steel (GC-SS) interface. A series of glass-ceramic compositions modified with a variety of oxidants, AgO, FeO, NiO, PbO, SnO, CuO, CoO, MoO3 and WO3, are examined for the feasibility of forming bonding oxides through reduction-oxidation (redox) at the GC-SS interface. The oxidants were selected according to their Gibbs free energy to allow for oxidation of Cr/Mn/Si from stainless steel, and yet to prevent a reduction of P2O5 in the glass-ceramic where the P2O5 is to form Li3PO4 nuclei for growth of high expansion crystalline SiO2 phases. Other than the CuO and CoO modified glass-ceramics, bonding from interfacial redox reactions were not achieved in the modified glass-ceramics, either because of poor wetting on the stainless steel or a reduction of the oxidants at the surface of glass-ceramic specimens rather than the GC-SS interface.

  20. Perovskite BaBiO3 Transformed Layered BaBiO2.5 Crystals Featuring Unusual Chemical Bonding and Luminescence.

    Science.gov (United States)

    Li, Hong; Zhao, Qing; Liu, Bo-Mei; Zhang, Jun-Ying; Li, Zhi-Yong; Guo, Shao-Qiang; Ma, Ju-Ping; Kuroiwa, Yoshihiro; Moriyoshi, Chikako; Zheng, Li-Rong; Sun, Hong-Tao

    2018-04-14

    Engineering oxygen coordination environments of cations in oxides has received intense interest thanks to the opportunities for the discovery of novel oxides with unusual properties. Here we present the successful synthesis of stoichiometric layered BaBiO2.5 enabled by a non-topotactic phase transformation of perovskite BaBiO3. By analysing the synchrotron X-ray diffraction data using the maximum entropy method/Rietveld technique, we find that Bi forms unusual chemical bondings with four oxygen atoms, featuring one ionic bonding and three covalent bondings that results in an asymmetric coordination geometry. A broad range of photophysical characterizations reveal that this peculiar structure shows near-infrared luminescence differing from conventional Bi-bearing systems. Experimental and theoretical results lead us to propose the excitonic nature of luminescence. Our work highlights that synthesizing materials with uncommon Bi-O bonding and Bi coordination geometry provides a pathway to the discovery of systems with new functionalities. We envisage that this work could inspire interest for the exploration of a range of materials containing heavier p-block elements, offering prospects for the finding of systems with unusual properties. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Silica chemically bonded N-propyl kriptofix 21 and 22 with immobilized palladium nanoparticles for solid phase extraction and preconcentration of some metal ions.

    Science.gov (United States)

    Ghaedi, Mehrorang; Niknam, Khodabakhsh; Zamani, Saeed; Larki, Habib Abasi; Roosta, Mostafa; Soylak, Mustafa

    2013-08-01

    Silica gel chemically bonded N-propyl kriptofix 21 (SBNPK 21) and N-propyl kriptofix 22 (SBNPK 22) and subsequently immobilized with palladium nanoparticles (PNP-SBNPK 21 and PNP-SBNPK 22) to produce two new complexing lipophilic materials. Then these novel sorbents were applied for the enrichment of some metal ions and their subsequent determination by flame atomic absorption spectroscopy (FAAS). The influences of the variables including pH, amount of solid phase, sample flow rate, eluent conditions and sample volume on the metal ion recoveries were investigated. The detection limit of proposed method was in the interval 2.1-2.3 and 1.7-2.8 ng mL(-1) for PNP-SBNPK 21 and PNP-SBNPK 22 respectively, while the preconcentration factor was 80 for two sorbents. The relative standard deviations of recoveries were between 1.23-1.31 and 1.28-1.49 for PNP-SBNPK 21 and PNP-SBNPK 22 respectively. The method has high sorption-preconcentration efficiency even in the presence of various interfering ions. Due to the reasonable selectivity of proposed method, the relative standard deviation of recoveries of all understudied metal ions in some complicated matrices was less than 3.0%. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Investigation of chemical bonding states at interface of Zn/organic materials for analysis of early stage of inorganic/organic hybrid multi-layer formation

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Ken, E-mail: k_cho@jwri.osaka-u.ac.jp [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Japan Science and Technology Agency, CREST (Japan); Takenaka, Kosuke; Setsuhara, Yuichi [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Japan Science and Technology Agency, CREST (Japan); Shiratani, Masaharu [Department of Electronics, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan); Japan Science and Technology Agency, CREST (Japan); Sekine, Makoto; Hori, Masaru [Plasma Nanotechnology Research Center, Nagoya University Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Japan Science and Technology Agency, CREST (Japan)

    2012-11-15

    Interactions between Ar-O{sub 2} mixture plasmas and Zn thin film on polyethylene terephthalate (PET) were investigated using the combinatorial plasma process analyzer, on the basis of nondestructive depth analyses of chemical bonding states at Zn thin film and Zn/PET interface via hard X-ray photoelectron spectroscopy (HXPES). After the Ar-O{sub 2} plasma exposure, peak-area ratio of O 1 s to Zn 2p{sub 3/2} evaluated from the HXPES spectra is found to increase with increasing the ion saturation current Multiplication-Sign time and saturated at the value obtained from ZnO. The HXPES C 1 s spectra measured at a take-off angle (TOA) of 80 Degree-Sign showed insignificant change in oxygen functionalities (O=C-O bond and C-O bond) after the deposition of Zn thin film and the plasma exposure. Whereas, the HXPES C 1 s spectra measurement at a TOA of 20 Degree-Sign suggested that the oxygen functionalities degraded in shallower regions up to about a few nanometer from the Zn/PET interface due to deposition of Zn thin film. However, after the plasma exposure, oxidation of PET substrate at the degraded layer of Zn/PET interface was caused by oxygen radicals and/or ions, which diffused through the Zn thin film.

  3. Effect of surface pretreatment on interfacial chemical bonding states of atomic layer deposited ZrO2 on AlGaN

    International Nuclear Information System (INIS)

    Ye, Gang; Arulkumaran, Subramaniam; Ng, Geok Ing; Li, Yang; Ang, Kian Siong; Wang, Hong; Ng, Serene Lay Geok; Ji, Rong; Liu, Zhi Hong

    2015-01-01

    Atomic layer deposition (ALD) of ZrO 2 on native oxide covered (untreated) and buffered oxide etchant (BOE) treated AlGaN surface was analyzed by utilizing x-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy. Evidenced by Ga–O and Al–O chemical bonds by XPS, parasitic oxidation during deposition is largely enhanced on BOE treated AlGaN surface. Due to the high reactivity of Al atoms, more prominent oxidation of Al atoms is observed, which leads to thicker interfacial layer formed on BOE treated surface. The results suggest that native oxide on AlGaN surface may serve as a protecting layer to inhibit the surface from further parasitic oxidation during ALD. The findings provide important process guidelines for the use of ALD ZrO 2 and its pre-ALD surface treatments for high-k AlGaN/GaN metal–insulator–semiconductor high electron mobility transistors and other related device applications

  4. On the problem of whether mass or chemical bonding is more important to bombardment-induced compositional changes in alloys and oxides

    International Nuclear Information System (INIS)

    Kelly, R.

    1980-01-01

    The bombardment of alloys, oxides, and halides often leads to marked compositional changes at the surface, and these changes have been attributed to an interplay of mass-dependent effects, chemical bonding, electronic processes, and diffusion. We attempt here to answer the limited question of whether, considering only alloys and oxides, mass or bonding is normally more important. The relevant theory is reviewed and extended, with mass effects being shown to be associated most explicitly with recoil sputtering and bonding effects being shown to be associated with all three of cascade sputtering, thermal sputtering, and surface segregation. As far as experimental examples are concerned, mass correlations are found to be quite unsuccessful, whereas most observations can be understood rather well in terms of bonding. Nevertheless, there is a basic problem in that the cascade component of sputtering, normally judged to be predominant, should give significantly less compositional change than is observed. Thermal sputtering would lead to more significant changes, but there is a new problem that, at least with alloys, the absolute yields are probably rather small. A combination of surface segregation with sputtering would also lead to more significant changes, but it is unclear whether segregation is rapid enough to be important in room-temperature bombardments. (orig.)

  5. Reaction dynamics. Extremely short-lived reaction resonances in Cl + HD (v = 1) → DCl + H due to chemical bond softening.

    Science.gov (United States)

    Yang, Tiangang; Chen, Jun; Huang, Long; Wang, Tao; Xiao, Chunlei; Sun, Zhigang; Dai, Dongxu; Yang, Xueming; Zhang, Dong H

    2015-01-02

    The Cl + H2 reaction is an important benchmark system in the study of chemical reaction dynamics that has always appeared to proceed via a direct abstraction mechanism, with no clear signature of reaction resonances. Here we report a high-resolution crossed-molecular beam study on the Cl + HD (v = 1, j = 0) → DCl + H reaction (where v is the vibrational quantum number and j is the rotational quantum number). Very few forward scattered products were observed. However, two distinctive peaks at collision energies of 2.4 and 4.3 kilocalories per mole for the DCl (v' = 1) product were detected in the backward scattering direction. Detailed quantum dynamics calculations on a highly accurate potential energy surface suggested that these features originate from two very short-lived dynamical resonances trapped in the peculiar H-DCl (v' = 2) vibrational adiabatic potential wells that result from chemical bond softening. We anticipate that dynamical resonances trapped in such wells exist in many reactions involving vibrationally excited molecules. Copyright © 2015, American Association for the Advancement of Science.

  6. Apatite glass-ceramics: a review

    Science.gov (United States)

    Duminis, Tomas; Shahid, Saroash; Hill, Robert Graham

    2016-12-01

    This article is a review of the published literature on apatite glass-ceramics (GCs). Topics covered include crystallization mechanisms of the various families of the apatite GCs and an update on research and development on apatite GCs for applications in orthopedics, dentistry, optoelectronics and nuclear waste management. Most apatite GCs crystallize through a homogenous nucleation and crystallization mechanism, which is aided by a prior liquid-liquid phase separation. Careful control of the base glass composition and heat-treatment conditions, which determine the nature and morphology of the crystal phases in the GC can produce GC materials with exceptional thermal, mechanical, optical and biological properties. The GCs reviewed for orthopedic applications exhibit suitable mechanical properties and can chemically bond to bone and stimulate its regeneration. The most commercially successful apatite GCs are those developed for dental veneering. These materials exhibit excellent translucency and clinical esthetics, and mimic the natural tooth mineral. Due to the ease of solid solution of the apatite lattice, rare earth doped apatite GCs are discussed for potential applications in optoelectronics and nuclear waste management. One of the drawbacks of the commercial apatite GCs used in orthopedics is the lack of resorbability, therefore the review provides a direction for future research in the field.

  7. Regulation of serum phosphate

    Science.gov (United States)

    Lederer, Eleanor

    2014-01-01

    The regulation of serum phosphate, an acknowledged risk factor for chronic kidney disease and cardiovascular mortality, is poorly understood. The discovery of fibroblast growth factor 23 (FGF23) as a key regulator of renal phosphate handling and activation of vitamin D has revolutionized our comprehension of phosphate homeostasis. Through as yet undetermined mechanisms, circulating and dietary phosphate appear to have a direct effect on FGF23 release by bone cells that, in turn, causes renal phosphate excretion and decreases intestinal phosphate absorption through a decrease in vitamin D production. Thus, the two major phosphaturic hormones, PTH and FGF23, have opposing effects on vitamin D production, placing vitamin D at the nexus of phosphate homeostasis. While our understanding of phosphate homeostasis has advanced, the factors determining regulation of serum phosphate level remain enigmatic. Diet, time of day, season, gender, age and genetics have all been identified as significant contributors to serum phosphate level. The effects of these factors on serum phosphate have major implications for what is understood as ‘normal’ and for studies of phosphate homeostasis and metabolism. Moreover, other hormonal mediators such as dopamine, insulin-like growth factor, and angiotensin II also affect renal handling of phosphate. How the major hormone effects on phosphate handling are regulated and how the effect of these other factors are integrated to yield the measurable serum phosphate are only now beginning to be studied. PMID:24973411

  8. Spectral Theory of Chemical Bonding

    National Research Council Canada - National Science Library

    Langhoff, P. W; Boatz, J. A; Hinde, R. J; Sheehy, J. A

    2004-01-01

    New theoretical methods are reported for obtaining the binding energies of molecules and other chemical aggregates employing the spectral eigenstates and related properties of their atomic constituents...

  9. Intercalation chemistry and chemical bonding

    Science.gov (United States)

    Hagenmuller, Paul

    In contrast to amphoteric graphite, the layer-type oxides or chalcogenides generally play the role of acceptors in chemical or electrochemical intercalation reactions. Due to the more ionic character of the MO bonds, the structural evolution of the oxides may usually be explained on hand of electrostatic considerations, or in terms of cation oxido-reduction. For the more covalent chalcogenides, the occupancy of higher energy levels in the band structure by the transferred electrons constitute mostly a prevailing factor, giving rise to structural changes but also to modifications of the physical properties. The ionic character of the MO bonds accounts for the strong tendency of the oxides to undergo 2D→3D transformations as a result of intercalation processes. Such features are determining for the choice of the electrode materials for lithium-ion batteries as far as users require high electrode capacity, stability, and cyclability.

  10. New concept bioceramics composed of octacalcium phosphate (OCP) and dicarboxylic acid-intercalated OCP via hydrothermal hot-pressing

    International Nuclear Information System (INIS)

    Ishihara, Shiho; Matsumoto, Takuya; Onoki, Takamasa; Sohmura, Taiji; Nakahira, Atsushi

    2009-01-01

    Octacalcium phosphate (OCP) and adipic acid-intercalated complexed OCP (Adi-OCP) were synthesized. Moreover, we made ceramic bodies out of them through a hydrothermal hot-pressing (HHP) method. Characteristic features of both the powder and ceramics were investigated by the X-ray diffraction method (XRD). Surface morphology of the ceramics was observed by scanning electron microscopy (SEM). Density, compressive strength and pore size distribution of the ceramics were measured. Crystalline structure of the newly developed OCP ceramics had no phase transformation from the starting materials. Moreover, the newly developed OCP ceramics had good mechanical properties only through the HHP treatment with a temperature as low as 110 deg. C. In order to evaluate bioactivity, the ceramics were immersed in simulating body fluid (SBF). It was predicted that OCP and Adi-OCP had better bioactivity than that of conventional HAp ceramics.

  11. Chemical Interaction Analysis of an Adhesive Containing 10-Methacryloyloxydecyl Dihydrogen Phosphate (10-MDP) With the Dentin in Noncarious Cervical Lesions.

    Science.gov (United States)

    Oliveira, Bmb; Ulbaldini, Alm; Sato, F; Baesso, M L; Bento, A C; Andrade, Lhc; Lima, S M; Pascotto, R C

    The purpose of this study was to evaluate the chemical bonds of a self-etch 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) adhesive to natural noncarious cervical lesions (NCCLs) and compare them with those occurring in sclerotic dentin in artificially prepared defects (APDs). Four human teeth with natural NCCLs on the buccal surface were selected. Artificial defects matching the natural lesions were prepared on the lingual surface of the same teeth serving as control. Micro-Raman (MR) spectroscopy was used to quantify mineral content in natural NCCLs and in APDs. Fourier transform infrared-photoacoustic spectroscopy (FTIR-PAS) readouts were taken before and after adhesive application to analyze the protein matrix/mineral (M:M) ratio and chemical interactions between 10-MDP adhesive and dentin. The MR and FTIR-PAS spectra collected from natural NCCLs demonstrated a larger area of the band (961 cm -1 , PO 4 ) and lower M:M ratio, respectively, characterizing a hypermineralized dentin, compared with APDs. FTIR-PAS demonstrated emergence of a peak (1179 cm -1 , P=O) in spectra after adhesive treatment, demonstrating a more intense chemical interaction in natural NCCLs. The results demonstrated that chemical bonding of 10-MDP adhesive to natural NCCLs is more intense, due to the hypermineralized surface, and suggest that it is unnecessary to remove the hypermineralized layer with burs, as this may decrease the chemical bonding potential of 10-MDP.

  12. Phosphate Uptake by Phosphate-Starved Euglena

    Science.gov (United States)

    BLUM, J. J.

    1966-01-01

    Phosphate-deprived Euglena acquire the ability to rapidly in-corporate added phosphate and, also, synthesize an induced acid phosphatase localized in the pellicle. The phosphate uptake system is saturated at low concentrations of phosphate and is inhibited by dinitrophenol, by low temperature, by K+, Li+, and Na+ ions, and competitively by arsenate. The orthophosphate incorporated into the cell is rapidly converted into organic forms but enough remains unesterified to suggest that the uptake is an active transport process. The data do not rule out the possibility that the induced phosphatase is involved in the transport process. PMID:5924104

  13. Verification of ceramic structures

    NARCIS (Netherlands)

    Behar-Lafenetre, S.; Cornillon, L.; Rancurel, M.; Graaf, D. de; Hartmann, P.; Coe, G.; Laine, B.

    2012-01-01

    In the framework of the "Mechanical Design and Verification Methodologies for Ceramic Structures" contract [1] awarded by ESA, Thales Alenia Space has investigated literature and practices in affiliated industries to propose a methodological guideline for verification of ceramic spacecraft and

  14. Ceramic Laser Materials

    Science.gov (United States)

    Sanghera, Jasbinder; Kim, Woohong; Villalobos, Guillermo; Shaw, Brandon; Baker, Colin; Frantz, Jesse; Sadowski, Bryan; Aggarwal, Ishwar

    2012-01-01

    Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements. PMID:28817044

  15. Electron densities and chemical bonding in TiC, TiN and TiO derived from energy band calculations

    International Nuclear Information System (INIS)

    Blaha, P.

    1983-10-01

    It was the aim of this paper to describe the chemical bonding of TiC, TiN and TiO by means of energy bands and electron densities. Using the respective potentials we have calculated the bandstructure of a finer k-grid with the linearized APW method to obtain accurate densities of states (DOS). These DOS wer partitioned into local partial contributions and the metal d DOS were further decomposed into tsub(2g) and esub(g) symmetry components in order to additionally characterize bonding. The electron densities corresponding to the occupied valence states are obtained from the LAPW calculations. They provide further insight into characteristic trends in the series from TiC to TiO: around the nonmetal site the density shows increasing localisation; around the metal site the deviation from spherical symmetry changes from esub(g) to tsub(2g). Electron density plots of characteristic band states allow to describe different types of bonding occurring in these systems. For TiC and TiN recent measurements of the electron densities exist for samples of TiCsub(0.94) and TiNsub(0.99), where defects cause static displacements of the Ti atoms. If this effect can be compensated by an atomic model one hopefully can extrapolate to stoichiometric composition. This procedure allows a comparison with structure factors derived from theoretical electron densities. The agreement for TiN is very good. For TiC the extrapolated data agree in terms of the deviations from spherical symmetry near the Ti site with the LAPW data, but the densities around both atoms are more localized than in theory. An explanation could be: a) the defects affect the electronic structure in TiCsub(0.94) with respect to TiCsub(1.0): b) the applied atomic model does not properly extrapolate to stoichiometry, because parameters of this model correlate or become unphysical. (Author)

  16. The antimony-group 11 chemical bond: dissociation energies of the diatomic molecules CuSb, AgSb, and AuSb.

    Science.gov (United States)

    Carta, V; Ciccioli, A; Gigli, G

    2014-02-14

    The intermetallic molecules CuSb, AgSb, and AuSb were identified in the effusive molecular beam produced at high temperature under equilibrium conditions in a double-cell-like Knudsen source. Several gaseous equilibria involving these species were studied by mass spectrometry as a function of temperature in the overall range 1349-1822 K, and the strength of the chemical bond formed between antimony and the group 11 metals was for the first time measured deriving the following thermochemical dissociation energies (D°(0), kJ/mol): 186.7 ± 5.1 (CuSb), 156.3 ± 4.9 (AgSb), 241.3 ± 5.8 (AuSb). The three species were also investigated computationally at the coupled cluster level with single, double, and noniterative quasiperturbative triple excitations (CCSD(T)). The spectroscopic parameters were calculated from the potential energy curves and the dissociation energies were evaluated at the Complete Basis Set limit, resulting in an overall good agreement with experimental values. An approximate evaluation of the spin-orbit effect was also performed. CCSD(T) calculations were further extended to the corresponding group 11 arsenide species which are here studied for the first time and the following dissociation energies (D°(0), kJ/mol): 190 ± 10 (CuAs), 151 ± 10 (AgAs), 240 ± 15 (AuAs) are proposed. Taking advantage of the new experimental and computational information here presented, the bond energy trends along group 11 and 4th and 5th periods of the periodic table were analyzed and the bond energies of the diatomic species CuBi and AuBi, yet experimentally unobserved, were predicted on an empirical basis.

  17. Effect of different chemical bonds in pegylation of zinc protoporphyrin that affects drug release, intracellular uptake, and therapeutic effect in the tumor.

    Science.gov (United States)

    Tsukigawa, Kenji; Nakamura, Hideaki; Fang, Jun; Otagiri, Masaki; Maeda, Hiroshi

    2015-01-01

    Pegylated zinc protoporphyrin (PEG-ZnPP) is a water-soluble inhibitor of heme oxygenase-1. In this study, we prepared two types of PEG-ZnPP conjugates with different chemical bonds between PEG and ZnPP, i.e., ester bonds and ether bonds, where both conjugates also contain amide bonds. Cleavability of these bonds in vitro and in vivo, especially cancer tissue, and upon intracellular uptake, was investigated in parallel with biological activities of the conjugates. Each conjugate showed different cleavability by plasma esterases and tumor proteases, as revealed by HPLC analyses. PEG-ZnPP with ester bond (esPEG-ZnPP) was more sensitive than PEG-ZnPP with ether bond (etPEG-ZnPP) for cleavage of PEG chains. etPEG-ZnPP showed no cleavage of PEG chains and had lower intracellular uptake and antitumor activity than did esPEG-ZnPP. The degradation of esPEG-ZnPP appeared to be facilitated by both serine and cysteine proteases in tumor tissues, whereas it was significantly slower in normal organs except the liver. Depegylated products such as free ZnPP had higher intracellular uptake than did intact PEG-ZnPP. We also studied hydrolytic cleavage by blood plasma of different animal species; mouse plasma showed the fastest cleavage whereas human plasma showed the slowest. These results suggest that ester-linked conjugates manifest more efficient cleavage of PEG, and greater yield of the active principle from the conjugates in tumor tissues than in normal tissues. More efficient intracellular uptake and thus an improved therapeutic effect with ester-linked conjugates are thus anticipated with fain stability, particularly in human blood. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Ceramic electrolyte coating methods

    Energy Technology Data Exchange (ETDEWEB)

    Seabaugh, Matthew M.; Swartz, Scott L.; Dawson, William J.; McCormick, Buddy E.

    2004-10-12

    Processes for preparing aqueous suspensions of a nanoscale ceramic electrolyte material such as yttrium-stabilized zirconia. The invention also includes a process for preparing an aqueous coating slurry of a nanoscale ceramic electrolyte material. The invention further includes a process for depositing an aqueous spray coating slurry including a ceramic electrolyte material on pre-sintered, partially sintered, and unsintered ceramic substrates and products made by this process.

  19. Simple additive manufacturing of an osteoconductive ceramic using suspension melt extrusion

    DEFF Research Database (Denmark)

    Slots, Casper; Bonde Jensen, Martin; Ditzel, Nicholas

    2017-01-01

    /calcium phosphate suspension melt for simple additive manufacturing of ceramic tricalcium phosphate implants. METHODS: A wide variety of non-aqueous liquids were tested to determine the formulation of a storable 3D printable tricalcium phosphate suspension ink, and only fatty acid-based inks were found to work...... clinically relevant mechanical strength and were chemically pure. They supported adhesion of mesenchymal stem cells, and these were able to deposit collagen onto the implants, secrete alkaline phosphatase and further mineralize the ceramic. SIGNIFICANCE: The tricalcium phosphate/fatty acid ink described here...... and its 3D printing may be sufficiently simple and effective to enable rapid, on-demand and in-hospital fabrication of individualized ceramic implants that allow clinicians to use them for treatment of bone trauma....

  20. Particle-induced amorphization of complex ceramics. Final report

    International Nuclear Information System (INIS)

    Ewing, R.C.; Wang, L.M.

    1998-01-01

    The crystalline-to-amorphous (c-a) phase transition is of fundamental importance. Particle irradiations provide an important, highly controlled means of investigating this phase transformation and the structure of the amorphous state. The interaction of heavy-particles with ceramics is complex because these materials have a wide range of structure types, complex compositions, and because chemical bonding is variable. Radiation damage and annealing can produce diverse results, but most commonly, single crystals become aperiodic or break down into a polycrystalline aggregate. The authors continued the studies of the transition from the periodic-to-aperiodic state in natural materials that have been damaged by α-recoil nuclei in the uranium and thorium decay series and in synthetic, analogous structures. The transition from the periodic to aperiodic state was followed by detailed x-ray diffraction analysis, in-situ irradiation/transmission electron microscopy, high resolution transmission electron microscopy, extended x-ray absorption fine structure spectroscopy/x-ray absorption near edge spectroscopy and other spectroscopic techniques. These studies were completed in conjunction with bulk irradiations that can be completed at Los Alamos National Laboratory or Sandia National Laboratories. Principal questions addressed in this research program included: (1) What is the process at the atomic level by which a ceramic material is transformed into a disordered or aperiodic state? (2) What are the controlling effects of structural topology, bond-type, dose rate, and irradiation temperature on the final state of the irradiated material? (3) What is the structure of the damaged material? (4) What are the mechanisms and kinetics for the annealing of interstitial and aggregate defects in these irradiated ceramic materials? (5) What general criteria may be applied to the prediction of amorphization in complex ceramics?

  1. Research on the preparation of highly functional ceramics aiming at fusing together with living cells. Pt. 2; Seitai saibo tono yugoka wo mezashita kokinosei ceramics sosei gijutsu ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Nishizawa, K.; Suzuki, T.; Nagae, H.; Kawamoto, Y.; Yokogawa, Y.; Nagata, F.; Tariyama, M.; Kameyama, T. [National Industrial Research Institute of Nagoya, Nagoya (Japan)

    2000-03-06

    The surface characteristics of surface-modified biocompatible ceramics made of {beta}-tricalcium phosphate (TCP) were found to change actively in tissue culture medium. Concentration changes of calcium and phosphate ions dissolved in distilled water or in culture medium showed that the solubility of the TCP ceramics was considerably high and depended on the pH value of the soaking medium. The most stable ceramics in the culture condition appeared to have the suitable surface for adhesion of L 929 cells. So, the solubility of the TCP ceramics as the cell carrier was considered to be the dominant factor in decreasing the adhesion of cells on TCP ceramics. Furthermore, it was found that the solubility and zeta potential of the surface-modified TCP ceramics, and cell adhesion and serum protein adsorption on the surface were varied with modification time. (author)

  2. Chemical Bonding and Molecular Geometry: from Lewis to Electron Densities. Ronald J. Gillespie, Paul L.A. Popelier (Eds.); Oxford University Press, Oxford, 2001, xiii+268 pages, ISBN 01951049-X, US$ 39.50

    Science.gov (United States)

    Silvi, B.

    2002-06-01

    This small book will certainly be one of the reference textbooks on the bonding theory of the next decade. The presentation of the different models used to describe and explain the chemical bond is made in both an epistemological and historical perspective in the first five chapters. The authors clearly show the importance of the Pauli principle as the explicative key of the chemical bonding. The respective merits and limitations of the Lewis model, of the orbital picture, of the valence shell electron pair (VSEPR) and ligand close-packing model are emphasised and illustrated by examples belonging to Inorganic Chemistry. The remaining three chapters contain an elegant presentation of the 'Atoms in Molecules' theory which provides a rigorous description of the bonding on the ground of the topological analysis of the electron density distribution. The introduction of the necessary mathematical definitions is made in a very simple and pedagogical fashion, which avoids unnecessary specialised jargon. The information extracted by the AIM analysis is then used to investigate the bonding in molecules belonging to periods 2-6. It is necessary to have read this book before teaching anything on the Chemical Bonding Theory. Its presence in the library is indispensable.

  3. Uranium from phosphate ores

    International Nuclear Information System (INIS)

    Hurst, F.J.

    1983-01-01

    The following topics are described briefly: the way phosphate fertilizers are made; how uranium is recovered in the phosphate industry; and how to detect covert uranium recovery operations in a phsophate plant

  4. Glucose-6-phosphate dehydrogenase

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003671.htm Glucose-6-phosphate dehydrogenase test To use the sharing features on this page, please enable JavaScript. Glucose-6-phosphate dehydrogenase (G6PD) is a protein that ...

  5. Ceramic gas turbine shroud

    Science.gov (United States)

    Shi, Jun; Green, Kevin E.

    2014-07-22

    An example gas turbine engine shroud includes a first annular ceramic wall having an inner side for resisting high temperature turbine engine gasses and an outer side with a plurality of radial slots. A second annular metallic wall is positioned radially outwardly of and enclosing the first annular ceramic wall and has a plurality of tabs in communication with the slot of the first annular ceramic wall. The tabs of the second annular metallic wall and slots of the first annular ceramic wall are in communication such that the first annular ceramic wall and second annular metallic wall are affixed.

  6. Creep in ceramics

    CERN Document Server

    Pelleg, Joshua

    2017-01-01

    This textbook is one of its kind, since there are no other books on Creep in Ceramics. The book consist of two parts: A and B. In part A general knowledge of creep in ceramics is considered, while part B specifies creep in technologically important ceramics. Part B covers creep in oxide ceramics, carnides and nitrides. While covering all relevant information regarding raw materials and characterization of creep in ceramics, the book also summarizes most recent innovations and developments in this field as a result of extensive literature search.

  7. Tailored ceramics. Chapter 5

    International Nuclear Information System (INIS)

    Haker, A.B.

    1988-01-01

    In the light of the broad variation in US high-level waste (HLW) types and the uncertainties in future waste production, research on the Rockwell International Science Center has focussed on developing a generic technology for the consolidation of high-level wastes into polyphase ceramics. The basic approach has been to 'tailor' wste compositions with chemical additives so that upon consolidation a dense ceramic assemblage is formed that chemically binds the waste species into known phases. This chapter deals with tailored ceramics for current and future high-level waste compositions. Section 2 gives a historical review of the development of tailored ceramics. Section 3 deals with tailored ceramics designed for specific HLW compositions and with microstructure and phase development. Section 4 discusses chemical and physical properties of tailored ceramic waste forms. In section 5 the various processing steps involved in converting HLW to polycrystalline ceramic forms are described. (author). 159 refs.; 20 figs.; 14 tabs

  8. CO2 and Nd:YAP laser interaction with lithium disilicate and Zirconia dental ceramics: A preliminary study

    Science.gov (United States)

    Rocca, Jean-Paul; Fornaini, Carlo; Brulat-Bouchard, Nathalie; Bassel Seif, Samy; Darque-Ceretti, Evelyne

    2014-04-01

    Lithium disilicate and Zirconia ceramics offer a high level of accuracy when used in prosthetic dentistry. Their bonding using different resins is highly dependent on micro-mechanical interlocking and adhesive chemical bonding. Investigation of the performances of high strength ceramics when their surface is modified for chemical and mechanical bonding is then required. The aim of this study is to investigate the possibility of using laser for surface treatment of different high strength CAD/CAM ceramics and thus to improve their mechanical and chemical properties. Thirty two CAD/CAM ceramic discs were divided into two different groups: lithium disilicate ceramics (IPS e.max CAD®, Ivoclar, Vivadent, Italy) and Zirconia ceramics (IPS e.max ZirCAD®, Ivoclar, Vivadent, Italy). The Laser surface treatment was performed by Carbon Dioxide laser (Dream Pulse Laser®, Daeshin Enterprise Corp., Korea) at 20 W, 25 W and 30 W CW and by Neodymium Yttrium Aluminum Perovskite laser (Nd:YAP Lokki®, Lobel Medical, France) at 10 W and 30 Hz. Physical modifications of the irradiated ceramic discs were observed by scanning electron microscopy (SEM) and chemically analyzed by Energy-Dispersive Spectroscopy (EDS). Surface wettability was tested using the water drop test and the crystalline structure was investigated using X-ray diffraction (XRD). The macroscopic observation showed a shinier structure in all the groups, while at the SEM observation only CO2 25 W and 30 W treated groups showed cracks and fissures. In the conditions of this study, CO2 laser and Nd:YAP laser with the parameters used create chemical and physical surface modifications of the ceramics, indicating the possibility of an improvement in adhesion of the tested ceramics.

  9. Effect of calcium carbonate on hardening, physicochemical properties, and in vitro degradation of injectable calcium phosphate cements.

    NARCIS (Netherlands)

    Sariibrahimoglu, K.; Leeuwenburgh, S.C.G.; Wolke, J.G.C.; Yubao, L.; Jansen, J.A.

    2012-01-01

    The main disadvantage of apatitic calcium phosphate cements (CPCs) is their slow degradation rate, which limits complete bone regeneration. Carbonate (CO(3)(2)(-)) is the common constituent of bone and it can be used to improve the degradability of the apatitic calcium phosphate ceramics. This study

  10. The relationship between bond ionicity, lattice energy, coefficient of thermal expansion and microwave dielectric properties of Nd(Nb(1-x)Sb(x))O4 ceramics.

    Science.gov (United States)

    Zhang, Ping; Zhao, Yonggui; Wang, Xiuyu

    2015-06-28

    The crystalline structure refinement, chemical bond ionicity, lattice energy and coefficient of thermal expansion were carried out for Nd(Nb(1-x)Sb(x))O4 ceramics with a monoclinic fergusonite structure to investigate the correlations between the crystalline structure, phase stability, bond ionicity, lattice energy, coefficient of thermal expansion, and microwave dielectric properties. The bond ionicity, lattice energy, and coefficient of thermal expansion of Nd(Nb(1-x)Sb(x))O4 ceramics were calculated using a semiempirical method based on the complex bond theory. The phase structure stability varied with the lattice energy which was resulted by the substitution constant of Sb(5+). With the increasing of the Sb(5+) contents, the decrease of Nb/Sb-O bond ionicity was observed, which could be contributed to the electric polarization. The ε(r) had a close relationship with the Nb/Sb-O bond ionicity. The increase of the Q×f and |τ(f)| values could be attributed to the lattice energy and the coefficient of thermal expansion. The microwave dielectric properties of Nd(Nb(1-x)Sb(x))O4 ceramics with the monoclinic fergusonite structure were strongly dependent on the chemical bond ionicity, lattice energy and coefficient of thermal expansion.

  11. Characterization of cement calcium phosphate for use dental

    International Nuclear Information System (INIS)

    Barros, C.M.B.; Oliveira, S.V.; Silva, M.C.; Marques, J.B.; Fook, M.V.L.

    2011-01-01

    Calcium phosphates are interesting biological and medical attention due to its occurrence in different animal species and humans. Ceramics based on calcium phosphate in the form of implants or porous particulate materials, have proven to be suitable replacements for bone tissue when they are only subjected to small mechanical stresses. Was obtained research laboratory DEMA/UFCG a calcium phosphate phase. The goal is to characterize the material by X-ray diffraction (XRD) in order to analyze what the phases and infrared spectroscopy (FTIR) to identify the absorption bands of the bonding characteristic. Was identified by XRD phase present in the sample is hydroxyapatite Ca/P 1.67. In infrared spectroscopy has absorption bands characteristic of the phosphate group at 1032 cm1 region. (author)

  12. Genotoxicity test of self-renovated ceramics in primary human peripheral lymphocytes.

    Science.gov (United States)

    Hua, Nan; Zhu, Huifang; Zhuang, Jing; Chen, Liping

    2014-12-01

    Zirconia-based ceramics is widely used in dentistry. Different compositions of ceramics have different features. Our self-renovated ceramics become more machinable without scarifying its dental restoration properties after adjusting ratio of lanthanum phosphate (LaPO4)/yttrium oxide (Y2O3). In order to evaluate its safety, here, we tested its genotoxicity in primary human peripheral lymphocytes. The human lymphocytes cultured on three groups of different ratios of LaPO4/Y2O3 diphase ceramics for 6 days showed little effect of growth inhibition and similar effect of growth trend to the negative control. Furthermore, single-cell gel electrophoresis (comet assay) indicated that there was no significant difference of the value of tail moment between the tested ceramics and negative control, the IPS Empress II (P > 0.05). Our findings implicate that our self-renovated ceramics do not induce DNA damages in human peripheral lymphocytes and support their future clinic application.

  13. Antibacterial ceramic for sandbox. Sunabayo kokin ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, K. (Ishizuka Glass Co. Ltd. Nagoya (Japan))

    1993-10-01

    Sands in sandboxes in parks have been called into question of being contaminated by colon bacilli and spawns from ascarides. This paper introduces an antibacterial ceramic for sandbox developed as a new material effective to help reduce the contamination. The ceramic uses natural sand as the main raw material, which is added with borax and silver to contain silver ions that have bacteria and fungus resistance and deodorizing effect. The ceramic has an average grain size ranging from 0.5 mm to 0.7 mm, and is so devised as to match specific gravity, grain size and shape of the sand, hence no separation and segregation can occur. The result of weatherability and antibacterial strength tests on sand for a sandbox mixed with the ceramic at 1% suggests that its efficacy lasts for about three years. Its actual use is under observation. Its efficacy has been verified in a test that measures a survival factor of spawns from dog ascardides contacted with aqueous solution containing the ceramic at 1%. Safety and sanitation tests have proved the ceramic a highly safe product that conforms to the food sanitation law. 5 refs., 3 figs., 3 tabs.

  14. Analyses of fine paste ceramics

    International Nuclear Information System (INIS)

    Sabloff, J.A.

    1980-01-01

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics

  15. Analyses of fine paste ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sabloff, J A [ed.

    1980-01-01

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics. (DLC)

  16. Science and Technology of Ceramics

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 2. Science and Technology of Ceramics - Advanced Ceramics: Structural Ceramics and Glasses. Sheela K Ramasesha. Series Article Volume 5 Issue 2 February 2000 pp 4-11 ...

  17. [Ceramic inlays and onlays].

    Science.gov (United States)

    van Pelt, A W; de Kloet, H J; van der Kuy, P

    1996-11-01

    Large direct composite restorations can induce shrinkage related postoperative sensitivity. Indirect resin-bonded (tooth colored) restorations may perhaps prevent these complaints. Indirect bonded ceramics are especially attractive because of their biocompatibility and esthetic performance. Several procedures and techniques are currently available for the fabrication of ceramic restorations: firing, casting, heat-pressing and milling. In this article the different systems are described. Advantages, disadvantages and clinical performance of ceramic inlays are compared and discussed.

  18. Continuous Fiber Ceramic Composites

    Energy Technology Data Exchange (ETDEWEB)

    Fareed, Ali [Honeywell Advanced Composites Inc. (HACI), Newark, DE (United States); Craig, Phillip A. [Honeywell Advanced Composites Inc. (HACI), Newark, DE (United States)

    2002-09-01

    Fiber-reinforced ceramic composites demonstrate the high-temperature stability of ceramics--with an increased fracture toughness resulting from the fiber reinforcement of the composite. The material optimization performed under the continuous fiber ceramic composites (CFCC) included a series of systematic optimizations. The overall goals were to define the processing window, to increase the robustinous of the process, to increase process yield while reducing costs, and to define the complexity of parts that could be fabricated.

  19. Synthesis of nano-bioactive glass-ceramic powders and its in vitro bioactivity study in bovine serum albumin protein

    Science.gov (United States)

    Nabian, Nima; Jahanshahi, Mohsen; Rabiee, Sayed Mahmood

    2011-07-01

    Bioactive glasses and ceramics have proved to be able to chemically bond to living bone due to the formation of an apatite-like layer on its surface. The aim of this work was preparation and characterization of bioactive glass-ceramic by sol-gel method. Nano-bioglass-ceramic material was crushed into powder and its bioactivity was examined in vitro with respect to the ability of hydroxyapatite layer to form on the surface as a result of contact with bovine serum albumin (BSA) protein. The obtained nano-bioactive glass-ceramic was analyzed before and after contact with BSA solution. This study used scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis to examine its morphology, crystallinity and composition. The TEM images showed that the NBG particles size were 10-40 nm. Bioactivity of nanopowder was confirmed by SEM and XRD due to the presence of a rich bone-like apatite layer. Therefore, this nano-BSA-bioglass-ceramic composite material is promising for medical applications such as bone substitutes and drug carriers.

  20. Method of sintering ceramic materials

    Science.gov (United States)

    Holcombe, Cressie E.; Dykes, Norman L.

    1992-01-01

    A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density.

  1. Ceramic piezoelectric materials

    International Nuclear Information System (INIS)

    Kaszuwara, W.

    2004-01-01

    Ceramic piezoelectric materials conert reversibility electric energy into mechanical energy. In the presence of electric field piezoelectric materials exhibit deformations up to 0.15% (for single crystals up to 1.7%). The deformation energy is in the range of 10 2 - 10 3 J/m 3 and working frequency can reach 10 5 Hz. Ceramic piezoelectric materials find applications in many modern disciplines such as: automatics, micromanipulation, measuring techniques, medical diagnostics and many others. Among the variety of ceramic piezoelectric materials the most important appear to be ferroelectric materials such as lead zirconate titanate so called PZT ceramics. Ceramic piezoelectric materials can be processed by methods widely applied for standard ceramics, i.e. starting from simple precursors e.g. oxides. Application of sol-gel method has also been reported. Substantial drawback for many applications of piezoelectric ceramics is their brittleness, thus much effort is currently being put in the development of piezoelectric composite materials. Other important research directions in the field of ceramic piezoelectric materials composite development of lead free materials, which can exhibit properties similar to the PZT ceramics. Among other directions one has to state processing of single crystals and materials having texture or gradient structure. (author)

  2. Corrosion of Ceramic Materials

    Science.gov (United States)

    Opila, Elizabeth J.; Jacobson, Nathan S.

    1999-01-01

    Non-oxide ceramics are promising materials for a range of high temperature applications. Selected current and future applications are listed. In all such applications, the ceramics are exposed to high temperature gases. Therefore it is critical to understand the response of these materials to their environment. The variables to be considered here include both the type of ceramic and the environment to which it is exposed. Non-oxide ceramics include borides, nitrides, and carbides. Most high temperature corrosion environments contain oxygen and hence the emphasis of this chapter will be on oxidation processes.

  3. Fabrication of Phosphate Cement with High Integrity

    International Nuclear Information System (INIS)

    Yang, Jae Hwan; Lee, Chang Hwa; Heo, Cheol Min; Jeon, Min Ku; Kang, Kweon Ho

    2011-01-01

    As the development of industrial society has accelerated, hazardous wastes are generated as well. According to the 1986 statistics of U.S.A, each person made 40 tons of waste in America that year. Treatment of radioactive waste is one of the most important and serious problems related to waste treatments, because its radioactivity and decaying heat have harmful effects to human and environment for a long time. Nuclear developed countries have used conventional method of treatment such as vitrification or cementation in order to stabilize and solidify radioactive waste. Although the former guarantees the formation of high leaching resistant and durable waste form, it requires several hundred (or even more than one thousand) temperature to melt glass frit. This process generates secondary waste volatilized, as well as being non-economical. Cement technology played a role of immobilizing low and middle class wastes. It has advantages of low temperature setting, low cost, easy process, etc. The alkalinity of ordinary cement, however, constrains the utility of cement to the solidification of alkaline waste. In addition, leachability and mechanical strength of cements are not quite appropriate for the stabilization of high level waste. In this regard, chemically bonded phosphate cement(CBPC), which sets by an acid-base reaction, is a potentially expectable material for immobilization of radioactive waste. CBPC not only sets at room temperature, but also encapsulates various isotopes chemically. The performance of CBPC can be enhanced by the addition of fly ash, sand, wollastonite, etc. This study aims at fabricating the CBPC containing fly ash with high integrity. Morphology, microstructure, and compressive strength are evaluated using SEM, and digital compressing machine

  4. A Ceramic Armor Material Database

    National Research Council Canada - National Science Library

    Holmquist, T

    1999-01-01

    .... The data include nine different ceramic materials. The ceramics are Silicon Carbide, Boron Carbide, Titanium Diboride, Aluminum Nitride, Silicon Nitride, Aluminum Oxide (85% pure), Aluminum Oxide (high purity...

  5. Bioactivity of calcium phosphate bioceramic coating fabricated by laser cladding

    Science.gov (United States)

    Zhu, Yizhi; Liu, Qibin; Xu, Peng; Li, Long; Jiang, Haibing; Bai, Yang

    2016-05-01

    There were always strong expectations for suitable biomaterials used for bone regeneration. In this study, to improve the biocompatiblity of titanium alloy, calcium phosphate bioceramic coating was obtained by laser cladding technology. The microstructure, phases, bioactivity, cell differentiation, morphology and resorption lacunae were investigated by optical microscope (OM), x-ray diffraction (XRD), methyl thiazolyl tetrazolium (MTT) assay, tartrate-resistant acid phosphatase (TRAP) staining and scanning electronic microscope (SEM), respectively. The results show that bioceramic coating consists of three layers, which are a substrate, an alloyed layer and a ceramic layer. Bioactive phases of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) were found in ceramic coating. Osteoclast precursors have excellent proliferation on the bioceramic surface. The bioceramics coating could be digested by osteoclasts, which led to the resorption lacunae formed on its surface. It revealed that the gradient bioceramic coating has an excellent bioactivity.

  6. Bioactivity of calcium phosphate bioceramic coating fabricated by laser cladding

    International Nuclear Information System (INIS)

    Zhu, Yizhi; Liu, Qibin; Xu, Peng; Li, Long; Jiang, Haibing; Bai, Yang

    2016-01-01

    There were always strong expectations for suitable biomaterials used for bone regeneration. In this study, to improve the biocompatiblity of titanium alloy, calcium phosphate bioceramic coating was obtained by laser cladding technology. The microstructure, phases, bioactivity, cell differentiation, morphology and resorption lacunae were investigated by optical microscope (OM), x-ray diffraction (XRD), methyl thiazolyl tetrazolium (MTT) assay, tartrate-resistant acid phosphatase (TRAP) staining and scanning electronic microscope (SEM), respectively. The results show that bioceramic coating consists of three layers, which are a substrate, an alloyed layer and a ceramic layer. Bioactive phases of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) were found in ceramic coating. Osteoclast precursors have excellent proliferation on the bioceramic surface. The bioceramics coating could be digested by osteoclasts, which led to the resorption lacunae formed on its surface. It revealed that the gradient bioceramic coating has an excellent bioactivity. (letter)

  7. Production of novel ceramic materials from coal fly ash and metal finishing wastes

    Energy Technology Data Exchange (ETDEWEB)

    Little, M.R.; Adell, V.; Cheeseman, C.R. [Centre for Environmental Control and Waste Management, Department of Civil and Environmental Engineering, Skempton Building, Imperial College London, London SW7 2AZ (United Kingdom); Boccaccini, A.R. [Department of Materials, Imperial College London, Prince Consort Road, London SW7 2BP (United Kingdom)

    2008-09-15

    Fly ash from coal fired power stations is a potential raw material for the production of ceramic tiles, bricks and blocks. Previous work has demonstrated that the addition of metals can significantly alter fly ash sintering. Metal finishing produces problematic waste filter cakes and sludges that are increasingly difficult to dispose of to landfill. The objective of this research was to investigate the effect of selected metal finishing wastes on the properties of sintered fly ash. A 10 wt.% addition of dried metal finishing sludge obtained from the phosphate bath at a tri-cationic phosphating operation significantly reduced the sintering temperature for maximum density by approximately 75 C. The addition of the phosphate bath sludge also reduced leaching of As, to the extent that fly ash ceramics containing this waste would be classified as inert. Potential industrial applications for these novel waste-derived ceramic materials are discussed. (author)

  8. Zinc phosphate conversion coatings

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, Toshifumi (Wading River, NY)

    1997-01-01

    Zinc phosphate conversion coatings for producing metals which exhibit enhanced corrosion prevention characteristics are prepared by the addition of a transition-metal-compound promoter comprising a manganese, iron, cobalt, nickel, or copper compound and an electrolyte such as polyacrylic acid, polymethacrylic acid, polyitaconic acid and poly-L-glutamic acid to a phosphating solution. These coatings are further improved by the incorporation of Fe ions. Thermal treatment of zinc phosphate coatings to generate .alpha.-phase anhydrous zinc phosphate improves the corrosion prevention qualities of the resulting coated metal.

  9. Zinc phosphate conversion coatings

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, T.

    1997-02-18

    Zinc phosphate conversion coatings for producing metals which exhibit enhanced corrosion prevention characteristics are prepared by the addition of a transition-metal-compound promoter comprising a manganese, iron, cobalt, nickel, or copper compound and an electrolyte such as polyacrylic acid, polymethacrylic acid, polyitaconic acid and poly-L-glutamic acid to a phosphating solution. These coatings are further improved by the incorporation of Fe ions. Thermal treatment of zinc phosphate coatings to generate {alpha}-phase anhydrous zinc phosphate improves the corrosion prevention qualities of the resulting coated metal. 33 figs.

  10. Discussion about magnesium phosphating

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2016-07-01

    Full Text Available The paper describes results from recently published research focused on production of non-conventional magnesium phosphate Mg3(PO42・4H2O – bobierrite, or MgHPO4・3H2O – newberyite coating for both magnesium alloys and/or mild steel. This new kind of coating is categorized in the context of current state of phosphating technology and its potential advantages and crystal structure is discussed. At the same time, the suitable comparison techniques for magnesium phosphate coating and conventional zinc phosphate coating are discussed.

  11. Phosphorus, phosphorous, and phosphate.

    Science.gov (United States)

    Iheagwara, O Susan; Ing, Todd S; Kjellstrand, Carl M; Lew, Susie Q

    2013-10-01

    This article distinguishes the terms "phosphorus, phosphorous, and phosphate" which are frequently used interchangeably. We point out the difference between phosphorus and phosphate, with an emphasis on the unit of measure. Expressing a value without the proper name or unit of measure may lead to misunderstanding and erroneous conclusions. We indicate why phosphate must be expressed as milligrams per deciliter or millimoles per liter and not as milliequivalents per liter. Therefore, we elucidate the distinction among the terms "phosphorus, phosphorous, and phosphate" and the importance of saying precisely what one really means. © 2012 The Authors. Hemodialysis International © 2012 International Society for Hemodialysis.

  12. Role of SrO on the bioactivity behavior of some ternary borate glasses and their glass ceramic derivatives.

    Science.gov (United States)

    Abdelghany, A M; Ouis, M A; Azooz, M A; ElBatal, H A; El-Bassyouni, G T

    2016-01-05

    Borate glasses containing SrO substituting both CaO and NaO were prepared and characterized for their bioactivity or bone bonding ability. Glass ceramic derivatives were prepared by thermal heat treatment process. FTIR, XRD and SEM measurements for the prepared glass and glass-ceramics before and after immersion in sodium phosphate solution for one and two weeks were carried out. The appearance of two IR peaks within the range 550-680cm(-1) after immersion in phosphate solution indicates the formation of hydroxyapatite or equivalent Sr phosphate layer. X-ray diffraction data agree with the FTIR spectral analysis. The solubility test was carried out for both glasses and glass ceramics derivatives in the same phosphate solution. The introduction of SrO increases the solubility for both glasses and glass ceramics and this is assumed to be due to the formation of Sr phosphate which is more soluble than calcium phosphate (hydroxyapatite). SEM images reveal varying changes in the surfaces of glass ceramics after immersion according to the SrO content. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. PREFACE: Symposium 13: Ceramics for Medicine, Biotechnology and Biomimetics

    Science.gov (United States)

    Ohtsuki, Chikara

    2011-10-01

    Preface to Symposium 13 (Ceramics for Medicine, Biotechnology and Biomimetics) of the International Congress on Ceramics III, 14-18 November 2010, Osaka, Japan Ceramic materials are now widely used in biomedical fields, such as applications of artificial bones, joints and teeth. The high potential of ceramics to exhibit biological functionality is expected to produce novel materials supporting biotechnology. These applications are governed by the interactions of materials and biological molecules. So far, 'bioceramics' is a type of biomaterial used for repairing damaged tissues. The orthopaedic application of bioceramics has advanced rapidly since the invention of Bioglass® that was found to encourage direct bonding with living bone. Hydroxyapatite and calcium phosphate ceramics are now popular bioceramics for use in artificial bones. While the bone-bonding behavior of materials was understood phenomenologically, very little has been known about the mechanism of either hard or soft tissue attachment or tissue growth on ceramic-based materials, such as glasses, glass-ceramics, ceramic composites and organic-inorganic hybrids. This symposium discussed the scientific understanding of the interface between biomedical materials and soft/hard tissues, and the design and construction of nanoscopic interfaces. It also involved establishment of biomimetic structures, characterization of natural life-related hard and soft tissues, and their formation mechanisms for a wide range of applications in biotechnology through 45 oral presentations including 5 invited lectures and 45 posters. I wish to express my sincere appreciation to the organizers of this symposium in the ICC3 conference. I am also grateful to the invited speakers, all the participants and organizing committee of the ICC3. It is my great pleasure that this proceedings could be published as the fruit of this symposium's achievement, which includes the contributions in all aspect of scientific understanding and

  14. Ceramic Technology Project

    Energy Technology Data Exchange (ETDEWEB)

    1992-03-01

    The Ceramic Technology Project was developed by the USDOE Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the USDOE and NASA advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. These programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. A five-year project plan was developed with extensive input from private industry. In July 1990 the original plan was updated through the estimated completion of development in 1993. The objective is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. To facilitate the rapid transfer of this technology to US industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities.

  15. Incorporation of RANKL promotes osteoclast formation and osteoclast activity on β-TCP ceramics.

    Science.gov (United States)

    Choy, John; Albers, Christoph E; Siebenrock, Klaus A; Dolder, Silvia; Hofstetter, Wilhelm; Klenke, Frank M

    2014-12-01

    β-Tricalcium phosphate (β-TCP) ceramics are approved for the repair of osseous defects. In large defects, however, the substitution of the material by authentic bone is inadequate to provide sufficient long-term mechanical stability. We aimed to develop composites of β-TCP ceramics and receptor activator of nuclear factor κ-B ligand (RANKL) to enhance the formation of osteoclasts and promote cell mediated calcium phosphate resorption. RANKL was adsorbed superficially onto β-TCP ceramics or incorporated into a crystalline layer of calcium phosphate by the use of a co-precipitation technique. Murine osteoclast precursors were seeded onto the ceramics. After 15 days, the formation of osteoclasts was quantified cytologically and colorimetrically with tartrate-resistant acidic phosphatase (TRAP) staining and TRAP activity measurements, respectively. Additionally, the expression of transcripts encoding the osteoclast gene products cathepsin K, calcitonin receptor, and of the sodium/hydrogen exchanger NHA2 were quantified by real-time PCR. The activity of newly formed osteoclasts was evaluated by means of a calcium phosphate resorption assay. Superficially adsorbed RANKL did not induce the formation of osteoclasts on β-TCP ceramics. When co-precipitated onto β-TCP ceramics RANKL supported the formation of mature osteoclasts. The development of osteoclast lineage cells was further confirmed by the increased expression of cathepsin K, calcitonin receptor, and NHA2. Incorporated RANKL stimulated the cells to resorb crystalline calcium phosphate. Our in vitro study shows that RANKL incorporated into β-TCP ceramics induces the formation of active, resorbing osteoclasts on the material surface. Once formed, osteoclasts mediate the release of RANKL thereby perpetuating their differentiation and activation. In vivo, the stimulation of osteoclast-mediated resorption may contribute to a coordinated sequence of material resorption and bone formation. Further in vivo studies

  16. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-02-01

    This is the fifth quarterly report on a new study to develop a ceramic membrane/metal joint. Results of wetting experiments on commercially available Nickel based brazing alloys on perovskite surfaces are described. Additionally, experimental and numerical investigations on the strength of concentric ceramic/metal joints are presented.

  17. Thermal stability of hydroxyapatite in biphasic calcium phosphate ceramics

    CSIR Research Space (South Africa)

    Nilen, RWN

    2008-04-01

    Full Text Available . GALLAGHER and J. A. HUNT, Bioma- terials 26 (2005) 5313 9. R. AYERS, S. NIELSEN-PREISS, V. FERGUSON, G. GO- TOLLI, J. J. MOORE and H. J. KLEEBE, Mater. Sci. Eng. C 26 (2005) 1333 10. D. LE NIHOUANNEN, G. DACULSI, A. SAFFRAZADEH, O. GAUTHIER, S...

  18. Secondary waste form testing: ceramicrete phosphate bonded ceramics

    International Nuclear Information System (INIS)

    Singh, D.; Ganga, R.; Gaviria, J.; Yusufoglu, Y.

    2011-01-01

    The cleanup activities of the Hanford tank wastes require stabilization and solidification of the secondary waste streams generated from the processing of the tank wastes. The treatment of these tank wastes to produce glass waste forms will generate secondary wastes, including routine solid wastes and liquid process effluents. Liquid wastes may include process condensates and scrubber/off-gas treatment liquids from the thermal waste treatment. The current baseline for solidification of the secondary wastes is a cement-based waste form. However, alternative secondary waste forms are being considered. In this regard, Ceramicrete technology, developed at Argonne National Laboratory, is being explored as an option to solidify and stabilize the secondary wastes. The Ceramicrete process has been demonstrated on four secondary waste formulations: baseline, cluster 1, cluster 2, and mixed waste streams. Based on the recipes provided by Pacific Northwest National Laboratory, the four waste simulants were prepared in-house. Waste forms were fabricated with three filler materials: Class C fly ash, CaSiO 3 , and Class C fly ash + slag. Optimum waste loadings were as high as 20 wt.% for the fly ash and CaSiO 3 , and 15 wt.% for fly ash + slag filler. Waste forms for physical characterizations were fabricated with no additives, hazardous contaminants, and radionuclide surrogates. Physical property characterizations (density, compressive strength, and 90-day water immersion test) showed that the waste forms were stable and durable. Compressive strengths were >2,500 psi, and the strengths remained high after the 90-day water immersion test. Fly ash and CaSiO 3 filler waste forms appeared to be superior to the waste forms with fly ash + slag as a filler. Waste form weight loss was ∼5-14 wt.% over the 90-day immersion test. The majority of the weight loss occurred during the initial phase of the immersion test, indicative of washing off of residual unreacted binder components from the waste form surface. Waste forms for ANS 16.1 leach testing contained appropriate amounts of rhenium and iodine as radionuclide surrogates, along with the additives silver-loaded zeolite and tin chloride. The leachability index for Re was found to range from 7.9 to 9.0 for all the samples evaluated. Iodine was below detection limit (5 ppb) for all the leachate samples. Further, leaching of sodium was low, as indicated by the leachability index ranging from 7.6-10.4, indicative of chemical binding of the various chemical species. Target leachability indices for Re, I, and Na were 9, 11, and 6, respectively. Degradation was observed in some of the samples post 90-day ANS 16.1 tests. Toxicity characteristic leaching procedure (TCLP) results showed that all the hazardous contaminants were contained in the waste, and the hazardous metal concentrations were below the Universal Treatment Standard limits. Preliminary scale-up (2-gal waste forms) was conducted to demonstrate the scalability of the Ceramicrete process. Use of minimal amounts of boric acid as a set retarder was used to control the working time for the slurry. Flexibility in treating waste streams with wide ranging compositional make-ups and ease of process scale-up are attractive attributes of Ceramicrete technology.

  19. Identification of the Charge Carriers in Cerium Phosphate Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Hannah L.; Jonghe, Lutgard C. De

    2010-06-02

    The total conductivity of Sr-doped cerium orthophosphate changes by nearly two orders of magnitude depending on the oxygen and hydrogen content of the atmosphere. The defect model for the system suggests that this is because the identity of the dominant charge carrier can change from electron holes to protons when the sample is in equilibrium with air vs. humidified hydrogen. In this work are presented some preliminary measurements that can help to clarify this exchange between carriers. The conduction behavior of a 2percent Sr-doped CePO4 sample under symmetric atmospheric conditions is investigated using several techniques, including AC impedance, H/D isotope effects, and chronoamperometry.

  20. Secondary waste form testing : ceramicrete phosphate bonded ceramics.

    Energy Technology Data Exchange (ETDEWEB)

    Singh, D.; Ganga, R.; Gaviria, J.; Yusufoglu, Y. (Nuclear Engineering Division); ( ES)

    2011-06-21

    The cleanup activities of the Hanford tank wastes require stabilization and solidification of the secondary waste streams generated from the processing of the tank wastes. The treatment of these tank wastes to produce glass waste forms will generate secondary wastes, including routine solid wastes and liquid process effluents. Liquid wastes may include process condensates and scrubber/off-gas treatment liquids from the thermal waste treatment. The current baseline for solidification of the secondary wastes is a cement-based waste form. However, alternative secondary waste forms are being considered. In this regard, Ceramicrete technology, developed at Argonne National Laboratory, is being explored as an option to solidify and stabilize the secondary wastes. The Ceramicrete process has been demonstrated on four secondary waste formulations: baseline, cluster 1, cluster 2, and mixed waste streams. Based on the recipes provided by Pacific Northwest National Laboratory, the four waste simulants were prepared in-house. Waste forms were fabricated with three filler materials: Class C fly ash, CaSiO{sub 3}, and Class C fly ash + slag. Optimum waste loadings were as high as 20 wt.% for the fly ash and CaSiO{sub 3}, and 15 wt.% for fly ash + slag filler. Waste forms for physical characterizations were fabricated with no additives, hazardous contaminants, and radionuclide surrogates. Physical property characterizations (density, compressive strength, and 90-day water immersion test) showed that the waste forms were stable and durable. Compressive strengths were >2,500 psi, and the strengths remained high after the 90-day water immersion test. Fly ash and CaSiO{sub 3} filler waste forms appeared to be superior to the waste forms with fly ash + slag as a filler. Waste form weight loss was {approx}5-14 wt.% over the 90-day immersion test. The majority of the weight loss occurred during the initial phase of the immersion test, indicative of washing off of residual unreacted binder components from the waste form surface. Waste forms for ANS 16.1 leach testing contained appropriate amounts of rhenium and iodine as radionuclide surrogates, along with the additives silver-loaded zeolite and tin chloride. The leachability index for Re was found to range from 7.9 to 9.0 for all the samples evaluated. Iodine was below detection limit (5 ppb) for all the leachate samples. Further, leaching of sodium was low, as indicated by the leachability index ranging from 7.6-10.4, indicative of chemical binding of the various chemical species. Target leachability indices for Re, I, and Na were 9, 11, and 6, respectively. Degradation was observed in some of the samples post 90-day ANS 16.1 tests. Toxicity characteristic leaching procedure (TCLP) results showed that all the hazardous contaminants were contained in the waste, and the hazardous metal concentrations were below the Universal Treatment Standard limits. Preliminary scale-up (2-gal waste forms) was conducted to demonstrate the scalability of the Ceramicrete process. Use of minimal amounts of boric acid as a set retarder was used to control the working time for the slurry. Flexibility in treating waste streams with wide ranging compositional make-ups and ease of process scale-up are attractive attributes of Ceramicrete technology.

  1. Chemistry of tetravalent actinides phosphates. The thorium phosphate-diphosphate as immobilisation matrix of actinides

    International Nuclear Information System (INIS)

    Dacheux, N.

    2002-01-01

    The author presents in this document its scientific works from 1992 to 2001, in order to obtain the enabling to manage scientific and chemical researches at the university Paris Sud Orsay. The first part gives an abstract of the thesis on the characterizations, lixiviation and synthesis of uranium and thorium based phosphate matrix in the framework of the search for a ceramic material usable in the radioactive waste storage. The second part presents briefly the researches realized at the CEA, devoted to a reliable, independent and accurate measure of some isotopes activity. The last part presents the abstracts of researches activities from 1996 to 2001 on the tetravalent actinides phosphates chemistry, the sintering of PDT and solid solutions of PDTU and the kinetic and thermodynamical studies of the PDT dissolution. Many references and some publication in full text are provided. (A.L.B.)

  2. Combined delivery of bone morphogenetic protein-2 and insulin-like growth factor-1 from nano-poly (γ-glutamic acid)/β-tricalcium phosphate-based calcium phosphate cement and its effect on bone regeneration in vitro.

    Science.gov (United States)

    Shu, Xiulin; Feng, Jin; Feng, Jing; Huang, Xiaomo; Li, Liangqiu; Shi, Qingshan

    2017-11-01

    In this study, nano-doped calcium phosphate cement delivery systems (poly (γ-glutamic acid)/β-tricalcium phosphate/calcium phosphate ceramics and nano (γ-glutamic acid)/β-tricalcium phosphate/calcium phosphate ceramic) were fabricated, and low doses (10 µg/g) of two growth factors, insulin-like growth factor-1 and bone morphogenetic protein-2, were encapsulated then sequentially released. We characterized the delivery systems using Fourier transform infrared spectroscopy and X-ray diffraction and measured washout resistance and compressive strength, and thus optimized the most appropriate proportioning of delivery systems for the two growth factors. One of the growth factors was absorbed by the nano-poly (γ-glutamic acid)/β-tricalcium phosphate, which was then mixed into the calcium phosphate ceramic solid phase to create a new solid phase calcium phosphate ceramic. Nano-poly (γ-glutamic acid)/β-tricalcium phosphate/calcium phosphate ceramic carriers were then prepared by blending the new calcium phosphate ceramic solid phase powder with a solution of the remaining growth factor. The effects of different release patterns (studying sequential behavior) of insulin-like growth factor-1 and bone morphogenetic protein-2 on osteogenic proliferation and differentiation of the MC3t3-E1 mouse osteoblast cell were investigated. This combinational delivery system provided a controlled release of the two growth factors, in which nano-doping significantly affected their release kinetics. The incorporation of dual growth factors could potentially stimulate bone healing and promoting bone ingrowth processes at a low dose.

  3. Ceramics As Materials Of Construction

    OpenAIRE

    Zaki, A; Eteiba, M. B.; Abdelmonem, N.M.

    1988-01-01

    This paper attempts to review the limitations for using the important ceramics in contact with corrosive media. Different types of ceramics are included. Corrosion properties of ceramics and their electrical properties are mentioned. Recommendations are suggested for using ceramics in different media.

  4. Marginal Fit Metal-Ceramic and In-Ceram Single Crown Cement retained in Implant-supported Abutments.

    Science.gov (United States)

    Valente, Valdimar S; Francischone, Carlos E; Vilarinho Soares de Moura, C D; Francischone, C E; Silva, Antonio M; Ribeiro, Izabella S; Filho, E M Maia; Bandéca, Matheus C; Tonetto, Mateus R; de Jesus Tavarez, R R

    2016-12-01

    This study evaluated the cervical fit of cemented metal-ceramic and In-Ceram implant-supported crowns, before and after the cementing procedure. Twenty crowns cemented on implant abutments are divided into two groups (n = 10): Group 1 -cemented metal-ceramic crowns and group 2 - cemented In-Ceram crowns. The marginal adaptations before and after cementation were evaluated in a comparison microscope with an error of 1 μm. All crowns were cemented with zinc phosphate cement. The cervical misalignment of cemented crowns before cementation (52.65 ± 11.83 and 85.73 ± 14.06 μm) was lower than that after cementation (66.80 ± 15.86 and 89.36 ± 22.66 μm). The cementing procedure interferes with the marginal fit of cemented crowns on implant abutments, with the prosthesis having better adaptation before cementation. Cemented metal-ceramic crowns exhibited better cervical adaptation than In-Ceram crowns cemented before and after the cementing procedure. The maintenance of gum health and the longevity of prosthetic restorations are closely related to the restoration's marginal integrity.

  5. Phosphate acquisition efficiency and phosphate starvation tolerance ...

    Indian Academy of Sciences (India)

    2011 Developing rice with high yield under phosphorus deficiency: Pup1 sequence to application. Plant Physiol. 156, 1202–1216. Ciereszko I., Gniazdowska A., Mikulska M. and Rychter A. M.. 1996 Assimilate translocation in bean plants (Phaseolus vulgaris. L.) during phosphate deficiency. J. Plant Physiol. 149, 343–. 348.

  6. Phosphate acquisition efficiency and phosphate starvation tolerance ...

    Indian Academy of Sciences (India)

    Here, we have reported the presence as well as the expression of a previously characterized rice gene, phosphate starvation tolerance ... from a cross between Gobindabhog and Satabdi, also did not show any linkage with P-deficiency tolerance ability. Thus, ... vated in P-limiting conditions which work in a cascade and.

  7. Radioactivity of phosphate mineral products

    OpenAIRE

    Mitrović Branislava; Vitorović Gordana; Stojanović Mirjana; Vitorović Duško

    2011-01-01

    The phosphate industry is one of the biggest polluters of the environment with uranium. Different products are derived after processing phosphoric ore, such as mineral and phosphate fertilizers and phosphate mineral supplements (dicalcium-and monocalcium phosphate) for animal feeding. Phosphate mineral additives used in animal food may contain a high activity of uranium. Research in this study should provide an answer to the extent in which phosphate minera...

  8. Radioactivity of phosphate mineral products

    Directory of Open Access Journals (Sweden)

    Mitrović Branislava

    2011-01-01

    Full Text Available The phosphate industry is one of the biggest polluters of the environment with uranium. Different products are derived after processing phosphoric ore, such as mineral and phosphate fertilizers and phosphate mineral supplements (dicalcium-and monocalcium phosphate for animal feeding. Phosphate mineral additives used in animal food may contain a high activity of uranium. Research in this study should provide an answer to the extent in which phosphate mineral products (phosphate fertilizer and phosphate mineral feed additives contribute to the contamination of soil, plants and animals.

  9. Phosphate Management: FY2010 Results Of Phosphate Precipitation Tests

    International Nuclear Information System (INIS)

    Hay, M.; King, W.

    2011-01-01

    The Phosphate Management program seeks to develop treatment options for caustic phosphate solutions resulting from the caustic leaching of the bismuth phosphate sludge. The SRNL subtask investigated the precipitation of phosphate salts from caustic solutions through addition of fluoride and by crystallization. The scoping tests examined the: precipitation of phosphate by the addition of sodium fluoride to form the sodium fluorophosphate double salt, Na 7 F(PO 4 ) 2 · 19H 2 O, crystallization of phosphate by reducing the temperature of saturated phosphate solutions, and combinations of precipitation and crystallization. A simplified leachate simulant was used in the study produced by dissolving sodium phosphate in 1 M to 3.5 M sodium hydroxide solutions. The results show that all three processes; precipitation with sodium fluoride, crystallization, and combined precipitation/crystallization can be effective for removing large amounts of phosphate from solution. The combined process of precipitation/crystallization showed >90% removal of phosphate at all hydroxide concentrations when cooling a non-saturated phosphate solution from 65 C to 25 C. Based on the measured solubility of sodium phosphate, pH adjustment/caustic addition will also remove large amounts of phosphate from solution (>80%). For all three processes, the phosphate concentration in the caustic solution must be managed to keep the phosphate from becoming too concentrated and thereby potentially forming a solid mass of sodium phosphate after an effective phosphate removal process.

  10. Osteoinduction of calcium phosphate biomaterials in small animals

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Lijia; Shi, Yujun [Key Laboratory of Transplant Engineering and Immunology, Ministry of Health, West China Hospital, Sichuan University, Chengdu (China); Ye, Feng [Department of Pathology, West China Hospital, Sichuan University, Chengdu, 610041 (China); Bu, Hong, E-mail: hongbu@scu.edu.cn [Key Laboratory of Transplant Engineering and Immunology, Ministry of Health, West China Hospital, Sichuan University, Chengdu (China); Department of Pathology, West China Hospital, Sichuan University, Chengdu, 610041 (China)

    2013-04-01

    Although osteoinduction mechanism of calcium phosphate (CP) ceramics is still unclear, several essential properties have been reported, such as chemical composition, pore size and porosity, etc. In this study, calcium phosphate powder (Ca{sub 3}(PO{sub 4}){sub 2}, CaP, group 1), biphasic calcium phosphate ceramic powder (BCP, group 2), and intact BCP rods (group 3) were implanted into leg muscles of mice and dorsal muscles of rabbits. One month and three months after implantation, samples were harvested for biological and histological analysis. New bone tissues were observed in 10/10 samples in group 1, 3/10 samples in group 2, and 9/10 samples in group 3 at 3rd month in mice, but not in rabbits. In vitro, human mesenchymal stem cells (hMSCs) were cultured with trace CaP and BCP powder, and osteogenic differentiation was observed at day 7. Our results suggested that chemical composition is the prerequisite in osteoinduction, and pore structure would contribute to more bone formation. - Highlights: ► Intrinsic osteoinduction of calcium phosphate biomaterials was observed implanted in muscles of mice. ► Biomaterials powder also has osteoinduction property. ► Osteogenic genes and protein could be detected by RT-PCR and Western blot in implanted biomaterials. ► Osteogenic phenomenon could be observed by electron microscopy. ► The chemical composition is the prerequisite in osteoinduction, and pore structure would contribute to more bone formation.

  11. Calcium phosphate-based coatings on titanium and its alloys.

    Science.gov (United States)

    Narayanan, R; Seshadri, S K; Kwon, T Y; Kim, K H

    2008-04-01

    Use of titanium as biomaterial is possible because of its very favorable biocompatibility with living tissue. Titanium implants having calcium phosphate coatings on their surface show good fixation to the bone. This review covers briefly the requirements of typical biomaterials and narrowly focuses on the works on titanium. Calcium phosphate ceramics for use in implants are introduced and various methods of producing calcium phosphate coating on titanium substrates are elaborated. Advantages and disadvantages of each type of coating from the view point of process simplicity, cost-effectiveness, stability of the coatings, coating integration with the bone, cell behavior, and so forth are highlighted. Taking into account all these factors, the efficient method(s) of producing these coatings are indicated finally.

  12. A novel biphasic calcium phosphate derived from fish otoliths

    Science.gov (United States)

    Montañez-Supelano, N. D.; Sandoval-Amador, A.; Estupiñan-Durán, H. A.; Y Peña-Ballesteros, D.

    2017-12-01

    Calcium phosphates are bioceramics that have been widely used as bone substitutes because they encourage the formation of bone on their surface and can improve the healing of the bone. Hydroxyapatite HA (calcium/phosphorus ratio of 1.67) and tricalcium phosphate TCP (calcium/phosphorus ratio of 1.50) are the most common calcium phosphates. Natural materials have begun to be tested to make HA or TCP such as shells of cardiidae (family of mollusks) and eggshells. The calcium phosphate obtained has a high ability to precipitate apatite. In this work, the mixed phase ceramic of beta-Tri-calcium phosphate / hydroxyapatite (β-TCP/HA) was synthesized by aqueous precipitation from fish otoliths, which are monomineralic species composed of aragonite. Otoliths of the specie Plagioscion squamosissimus, commonly called the river croaker, were used. Techniques such as DRX, Raman spectroscopy and SEM-EDS were used to characterize the raw material and the obtained material. X-ray diffraction analysis revealed the presence of two crystalline phases of calcium phosphates with 86.2% crystallinity. SEM micrographs showed agglomeration of particles with porous structure and submicron particle sizes.

  13. Discussion about magnesium phosphating

    OpenAIRE

    Pokorny, P.; Tej, P.; Szelag, P.

    2016-01-01

    The paper describes results from recently published research focused on production of non-conventional magnesium phosphate Mg3(PO4)2・4H2O – bobierrite, or MgHPO4・3H2O – newberyite) coating for both magnesium alloys and/or mild steel. This new kind of coating is categorized in the context of current state of phosphating technology and its potential advantages and crystal structure is discussed. At the same time, the suitable comparison techniques for magnesium phosphate coating and convention...

  14. Corrosion resistant ceramic materials

    Science.gov (United States)

    Kaun, Thomas D.

    1996-01-01

    Ceramic materials which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  15. Ceramic breeder materials

    International Nuclear Information System (INIS)

    Johnson, C.E.

    1990-01-01

    The breeding blanket is a key component of the fusion reactor because it directly involves tritium breeding and energy extraction, both of which are critical to development of fusion power. The lithium ceramics continue to show promise as candidate breeder materials. This promise was recognized by the International Thermonuclear Reactor (ITER) design team in its selection of ceramics as the first option for the ITER breeder material. Blanket design studies have indicated properties in the candidate materials data base that need further investigation. Current studies are focusing on tritium release behavior at high burnup, changes in thermophysical properties with burnup, compatibility between the ceramic breeder and beryllium multiplier, and phase changes with burnup. Laboratory and in-reactor tests, some as part of an international collaboration for development of ceramic breeder materials, are underway. 32 refs., 1 fig., 1 tab

  16. Anionic Conducting Oxide Ceramics

    National Research Council Canada - National Science Library

    Dunn, Bruce

    1998-01-01

    This program has emphasized the interrelationships among synthesis, microstructure and properties for oxygen ion conducting ceramics based on copper-substituted bismuth vanadate (Bi V Cu O ), known as BICUVOX...

  17. Fracture resistance of metal- and galvano-ceramic crowns cemented with different luting cements: in vitro comparative study.

    Science.gov (United States)

    Ghazy, Mohamed H; Madina, Manal M Abo

    2006-01-01

    This study aimed to compare the fracture resistance of galvano-ceramic crowns with metal-ceramic crowns cemented to natural premolar teeth with different luting cements. Sixty intact maxillary premolars were prepared to receive full-coverage crown restorations and were divided into 2 equal groups (n = 30): galvano-ceramic crowns and metal-ceramic crowns. Each group was further subdivided into 3 equal subgroups (n = 10) according to the luting cement used: zinc-phosphate, glass-ionomer, or adhesive-resin cement. The specimens were then compressively loaded until failure in a universal testing machine. The metal-ceramic crowns exhibited higher resistance to fracture compared to galvano-ceramic crowns, but both exceeded the normal documented values of occlusal masticatory forces.

  18. Metal-phosphate binders

    Science.gov (United States)

    Howe, Beth Ann [Lewistown, IL; Chaps-Cabrera, Jesus Guadalupe [Coahuila, MX

    2009-05-12

    A metal-phosphate binder is provided. The binder may include an aqueous phosphoric acid solution, a metal-cation donor including a metal other than aluminum, an aluminum-cation donor, and a non-carbohydrate electron donor.

  19. Manganese phosphate-coating

    International Nuclear Information System (INIS)

    Peyre, Y.

    1999-01-01

    Manganese phosphate-coating is one of the numerous chemical surface treatment which is used industrially. Its applications are usual for improving the friction properties of a lot of mechanical parts. Used for the treatment of steels and cast steels, baths (containing phosphoric acid, manganese phosphate and different additives) lead to the formation of nonmetal coatings of a few micrometers. These manganese-iron or manganese phosphates crystals reduce the friction coefficient and retain the lubricant film in contact with the moving parts. The running noises, the wear and the seizure risks are then strongly reduced. Pure manganese phosphate-coating is currently developing because the obtained coatings are thinner and more regular. (O.M.)

  20. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-07-01

    This is the fourth quarterly report on a new study to develop a ceramic membrane/metal joint. The first experiments using the La-Sr-Fe-O ceramic are reported. Some of the analysis performed on the samples obtained are commented upon. A set of experiments to characterize the mechanical strength and thermal fatigue properties of the joints has been designed and begun. Finite element models of joints used to model residual stresses are described.

  1. Structural, electronic properties, and chemical bonding in quaternary layered titanium pnictide-oxides Na2Ti2Pn2O and BaTi2Pn2O (Pn = As, Sb) from FLAPW–GGA calculations

    International Nuclear Information System (INIS)

    Suetin, D.V.; Ivanovskii, A.L.

    2013-01-01

    Highlights: •Layered Na 2 Ti 2 Pn 2 O and BaTi 2 Pn 2 O (Pn = As, Sb) are probed from first principles. •Structural, electronic properties and Fermi surfaces are evaluated. •Chemical bonding is analyzed. -- Abstract: By means of the first-principles FLAPW–GGA calculations, we have investigated the main trends in structural, electronic properties, and chemical bonding for a series of quaternary titanium pnictide-oxides: Na 2 Ti 2 As 2 O, Na 2 Ti 2 Sb 2 O, BaTi 2 As 2 O, and BaTi 2 Sb 2 O, which attracted now much attention as parent phases for a novel group of layered Fe-free superconducting materials. Our results cover the optimized lattice parameters and atomic positions, electronic bands, Fermi surface topology, total and partial density of electronic states. Besides, Bader analysis and the charge density maps are used to discuss the chemical bonding for the examined materials. We find that the atomic substitutions lead to anisotropic deformation of the crystal structure; this effect is related to strong anisotropy of inter-atomic bonds, which are of a mixed (covalent-ionic-metallic) type – in blocks [Ti 2 Pn 2 O], whereas the bonding between blocks [Ti 2 Pn 2 O] and atomic sheets of Na, Ba ions is of an ionic type. The actual effective atomic charges differ from the formal ionic charges due to covalency in blocks [Ti 2 Pn 2 O]. The near-Fermi electronic bands, which are responsible for metallic-like behavior of these materials and will be involved in the formation of superconducting state, arise mainly from the Ti 3d xy , d x2−y2 , and d z2 states of the blocks [Ti 2 Pn 2 O], which define also the anisotropic character of conduction happening mainly in these blocks. The differences in the topology of the multi-sheet Fermi surfaces of these materials are discussed

  2. The use of Straumann (R) Bone Ceramic in a maxillary sinus floor elevation procedure: a clinical, radiological, histological and histomorphometric evaluation with a 6-month healing period

    NARCIS (Netherlands)

    Frenken, J.W.F.H.; Bouwman, W.F.; Bravenboer, N.; Zijderveld, S.A.; Schulten, E.A.J.M.; ten Bruggenkate, C.M.

    2010-01-01

    Objectives: In this study, we evaluated the quality and quantity of bone formation in maxillary sinus floor elevation procedure using a new fully synthetic biphasic calcium phosphate (BCP) consisting of a mixture of 60% hydroxyapatite and 40% of β-tricalcium phosphate (Straumann® Bone Ceramic).

  3. The use of Straumann Bone Ceramic in a maxillary sinus floor elevation procedure: a clinical, radiological, histological and histomorphometric evaluation with a 6-month healing period

    NARCIS (Netherlands)

    Frenken, J.W.F.H.; Bouwman, W.F.; Bravenboer, N.; Zijderveld, S.A.; Schulten, E.A.J.M.; Bruggenkate, C.M. ten

    2010-01-01

    OBJECTIVES: In this study, we evaluated the quality and quantity of bone formation in maxillary sinus floor elevation procedure using a new fully synthetic biphasic calcium phosphate (BCP) consisting of a mixture of 60% hydroxyapatite and 40% of beta-tricalcium phosphate (Straumann Bone Ceramic).

  4. Carbon-Fiber Framework for Full-Arch Implant-Supported Fixed Dental Prostheses Supporting Resin-Based Composite and Lithium Disilicate Ceramic Crowns: Case Report and Description of Features.

    Science.gov (United States)

    Castorina, Giuseppe

    2017-12-15

    This case report presents a new approach for shock-absorbing carbon-fiber composite frameworks for full-arch implant-supported fixed dental prostheses supporting resin-based and lithium disilicate ceramic crowns. It describes the characteristics of the materials used, the procedures for implementing the framework, and the requirements to achieve the best mechanical and clinical properties. The result is a full-arch prosthesis with masticatory load shock-absorption capacities, chemical bonding between materials, good esthetics, and wear similar to natural enamel. A 24-month follow-up full-arch bimaxillary implant-supported rehabilitation, performed with computer-guided surgery, is described.

  5. Clinical application of bio ceramics

    International Nuclear Information System (INIS)

    Anu, Sharma; Gayatri, Sharma

    2016-01-01

    Ceramics are the inorganic crystalline material. These are used in various field such as biomedical, electrical, electronics, aerospace, automotive and optical etc. Bio ceramics are the one of the most active areas of research. Bio ceramics are the ceramics which are biocompatible. The unique properties of bio ceramics make them an attractive option for medical applications and offer some potential advantages over other materials. During the past three decades, a number of major advances have been made in the field of bio ceramics. This review focuses on the use of these materials in variety of clinical scenarios.

  6. Resorption Rate Tunable Bioceramic: Si, Zn-Modified Tricalcium Phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xiang [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    This dissertation is organized in an alternate format. Several manuscripts which have already been published or are to be submitted for publication have been included as separate chapters. Chapter 1 is a general introduction which describes the dissertation organization and introduces the human bone and ceramic materials as bone substitute. Chapter 2 is the background and literature review on dissolution behavior of calcium phosphate, and discussion of motivation for this research. Chapter 3 is a manuscript entitled ''Si,Zn-modified tricalcium phosphate: a phase composition and crystal structure study'', which was published in ''Key Engineering Materials'' [1]. Chapter 4 gives more crystal structure details by neutron powder diffraction, which identifies the position for Si and Zn substitution and explains the stabilization mechanism of the structure. A manuscript entitled ''Crystal structure analysis of Si, Zn-modified Tricalcium phosphate by Neutron Powder Diffraction'' will be submitted to Biomaterials [2]. Chapter 5 is a manuscript, entitled ''Dissolution behavior and cytotoxicity test of Si, Zn-modified tricalcium phosphate'', which is to be submitted to Biomaterials [3]. This paper discusses the additives effect on the dissolution behavior of TCP, and cytotoxicity test result is also included. Chapter 6 is the study of hydrolysis process of {alpha}-tricalcium phosphate in the simulated body fluid, and the phase development during drying process is discussed. A manuscript entitled ''Hydrolysis of {alpha}-tricalcium phosphate in simulated body fluid and phase transformation during drying process'' is to be submitted to Biomaterials [4]. Ozan Ugurlu is included as co-authors in these two papers due to his TEM contributions. Appendix A is the general introduction of the materials synthesis, crystal structure and preliminary dissolution result. A manuscript entitled

  7. Density functional study of electronic, charge density, and chemical bonding properties of 9-methyl-3-Thiophen-2-YI-Thieno [3,2-e] [1, 2, 4] Thriazolo [4,3-c] pyrimidine-8-Carboxylic acid ethyl ester crystals

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A.H., E-mail: maalidph@yahoo.co.uk [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Kamarudin, H. [Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Alahmed, Z.A. [Department of Physics and Astronomy, King Saud University, Riyadh 11451 (Saudi Arabia); Auluck, S. [CSIR-National Physical Laboratory, Dr. K S Krishnan Marg, New Delhi 110012 (India); Chyský, Jan [Department of Instrumentation and Control Engineering, Faculty of Mechanical Engineering, CTU in Prague, Technicka 4, 166 07 Prague 6 (Czech Republic)

    2014-06-01

    A comprehensive theoretical density functional investigation of the electronic crystal structure, chemical bonding, and the electron charge densities of 9-Methyl-3-Thiophen-2-YI-Thieno [3, 2-e] [1, 2, 4] Thriazolo [4,3-c] Pyrimidine-8-Carboxylic Acid Ethyl Ester (C{sub 15}H{sub 12}N{sub 4}O{sub 2}S{sub 2}) is performed. The density of states at Fermi level equal to 5.50 (3.45) states/Ry cell, and the calculated bare electronic specific heat coefficient is found to be 0.95 (0.59) mJ/mole-K{sup 2} for the local density approximation (Engel–Vosko generalized gradient approximation). The electronic charge density space distribution contours in (1 0 0) and (1 1 0) planes were calculated. We find that there are two independent molecules (A and B) in the asymmetric unit exhibit intramolecular C–H…O, C–H…N interactions. This intramolecular interaction is different in molecules A and B, where A molecule show C–H…O interaction while B molecule exhibit C–H…N interaction. We should emphasis that there is π–π interaction between the pyrimidine rings of the two neighbors B molecules gives extra strengths and stabilizations to the superamolecular structure. The calculated distance between the two neighbors pyrimidine rings found to be 3.345 Å, in good agreement with the measured one (3.424(1) Å). - Highlights: • Electronic structure, chemical bonding, and electron charge density were studied. • Density of states at Fermi level is 5.50 (3.45) states/Ry cell, for LDA (EVGGA). • Bare electronic specific heat coefficient is 0.95 (0.59) mJ/mole-K{sup 2} for LDA(EVGGA). • There are two independent molecules (A and B) in the asymmetric unit.

  8. Laser technologies of ceramics treatment (review)

    International Nuclear Information System (INIS)

    Markov, E.M.; Voronezhtsev, Yu.I.; Gol'dade, V.A.

    1990-01-01

    Publications on the laser technologies of ceramic coating production, ceramics treatment and ceramics manufacture are analyzed for the past 5 years. Features of production processes utilizing the interaction of laser radiation with ceramics and other substances which form the ceramics as a result of such interaction are considered. Possible ways of improving laser technologies of ceramics treatment are outlined

  9. Ceramic scaffolds produced by computer-assisted 3D printing and sintering: characterization and biocompatibility investigations.

    NARCIS (Netherlands)

    Warnke, P.H.; Seitz, H.; Warnke, F.; Becker, S.T.; Sivananthan, S.; Sherry, E.; Liu, Q.; Wiltfang, J.; Douglas, T.E.L.

    2010-01-01

    Hydroxyapatite (HAP) and tricalcium phosphate (TCP) are two very common ceramic materials for bone replacement. However, in general HAP and TCP scaffolds are not tailored to the exact dimensions of the defect site and are mainly used as granules or beads. Some scaffolds are available as ordinary

  10. Engineering spinal fusion: evaluating ceramic materials for cell based tissue engineered approaches

    NARCIS (Netherlands)

    Wilson, C.E.

    2011-01-01

    The principal aim of this thesis was to advance the development of tissue engineered posterolateral spinal fusion by investigating the potential of calcium phosphate ceramic materials to support cell based tissue engineered bone formation. This was accomplished by developing several novel model

  11. New insights into phosphate based materials for the immobilisation of actinides

    Energy Technology Data Exchange (ETDEWEB)

    Neumeier, Stefan; Ji, Yaqi; Kowalski, Piotr M.; Kegler, Philip; Schlenz, Hartmut; Bosbach, Dirk; Deissmann, Guido [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Energie und Klimaforschung (IEK), Nukleare Entsorgung und Reaktorsicherheit (IEK-6); JARA High-Performance Computing, Aachen (Germany); Arinicheva, Yulia [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Energie und Klimaforschung (IEK), Nukleare Entsorgung und Reaktorsicherheit (IEK-6); JARA High-Performance Computing, Aachen (Germany); Forschungszentrum Juelich (Germany). Institut fuer Energie- und Klimaforschung (IEK), Werkstoffsynthese und Herstellungsverfahren (IEK-1); Heuser, Julia M. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Energie und Klimaforschung (IEK), Nukleare Entsorgung und Reaktorsicherheit (IEK-6); JARA High-Performance Computing, Aachen (Germany); Karlsruhe Institute of Technology (Germany). Inst. of Applied Materials (IAM)

    2017-07-01

    This paper focuses on major phosphate-based ceramic materials relevant for the immobilisation of Pu, minor actinides, fission and activation products. Key points addressed include the recent progress regarding synthesis methods, the formation of solid solutions by structural incorporation of actinides or their non-radioactive surrogates and waste form fabrication by advanced sintering techniques. Particular attention is paid to the properties that govern the long-term stability of the waste forms under conditions relevant to geological disposal. The paper highlights the benefits gained from synergies of state-of-the-art experimental approaches and advanced atomistic modeling tools for addressing properties and stability of f-element-bearing phosphate materials. In conclusion, this article provides a perspective on the recent advancements in the understanding of phosphate based ceramics and their properties with respect to their application as nuclear waste forms.

  12. Elaboration of thorium uranium phosphate-diphosphate({beta}-TUPD) and {beta}-TUPD/monazite composite materials from crystallized precursors: sintering and study of the long term behavior of the ceramics; Elaboration de phosphate-diphosphate de thorium et d'uranium ({beta}-PDTU) et de materiaux composites {beta}-PDTU/Monazite a partir de precurseurs cristallises. Etudes du frittage et de la durabilite chimique

    Energy Technology Data Exchange (ETDEWEB)

    Clavier, N

    2004-11-01

    Thorium Phosphate-Diphosphate ({beta}-TPD) is actually considered as potential host matrix for the immobilization of radionuclides, and especially actinides, in the field of an underground repository. The studies reported in this work are based on the precipitation of the Thorium Phosphate Hydrogen-Phosphate Hydrate (TPHPH) as a precursor of {beta}-TPD. The crystal structure of TPHPH was solved then the reactions involved during its transformation into {beta}-TPD were established. It allows us to put in evidence a new monoclinic variety of TPD, called {alpha}-TPD, acting as intermediate of reaction. Moreover, the existence of a complete solid solution between TPHPH and UPHPH was demonstrated.The experimental conditions of sintering leading to an optimal densification of the pellets were determined. The relative density of the samples was always between 95 and 100% of the calculated value while a significant improvement of the homogeneity of the samples was noted. By this way, the process based on the precipitation of low-temperature crystallized precursors followed by their heat treatment at high temperature was applied to the preparation of {beta}-TUPD/Monazite based composites in the aim to incorporate simultaneously tri- and tetravalent actinides. The chemical durability of {beta}-TUPD sintered samples was evaluated. The normalized leaching rates determined in several experimental conditions revealed the good resistance of the solids to aqueous alteration. Moreover, the normalized dissolution rates exhibited a low dependence to temperature, pH as well as to several ions present in the leachate. For all the samples, thorium was quickly precipitated as a neo-formed phosphate phase identified to TPHPH. (author)

  13. Phosphate control in dialysis

    Directory of Open Access Journals (Sweden)

    Cupisti A

    2013-10-01

    Full Text Available Adamasco Cupisti,1 Maurizio Gallieni,2 Maria Antonietta Rizzo,2 Stefania Caria,3 Mario Meola,4 Piergiorgio Bolasco31Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy; 2Nephrology and Dialysis Unit, San Carlo Borromeo Hospital, Milan, Italy; 3Territorial Department of Nephrology and Dialysis, ASL Cagliari, Italy; 4Sant'Anna School of Advanced Studies, University of Pisa, Pisa, ItalyAbstract: Prevention and correction of hyperphosphatemia is a major goal of chronic kidney disease–mineral and bone disorder (CKD–MBD management, achievable through avoidance of a positive phosphate balance. To this aim, optimal dialysis removal, careful use of phosphate binders, and dietary phosphate control are needed to optimize the control of phosphate balance in well-nourished patients on a standard three-times-a-week hemodialysis schedule. Using a mixed diffusive–convective hemodialysis tecniques, and increasing the number and/or the duration of dialysis tecniques are all measures able to enhance phosphorus (P mass removal through dialysis. However, dialytic removal does not equal the high P intake linked to the high dietary protein requirement of dialysis patients; hence, the use of intestinal P binders is mandatory to reduce P net intestinal absorption. Unfortunately, even a large dose of P binders is able to bind approximately 200–300 mg of P on a daily basis, so it is evident that their efficacy is limited in the case of an uncontrolled dietary P load. Hence, limitation of dietary P intake is needed to reach the goal of neutral phosphate balance in dialysis, coupled to an adequate protein intake. To this aim, patients should be informed and educated to avoid foods that are naturally rich in phosphate and also processed food with P-containing preservatives. In addition, patients should preferentially choose food with a low P-to-protein ratio. For example, patients could choose egg white or protein from a vegetable source

  14. Testing method for ceramic armour and bare ceramic tiles

    NARCIS (Netherlands)

    Carton, E.P.; Roebroeks, G.H.J.J.

    2016-01-01

    TNO developed an alternative, more configuration independent ceramic test method than the Depth-of-Penetration test method. In this alternative test ceramic tiles and ceramic based armour are evaluated as target without a semi-infinite backing layer. An energy approach is chosen to evaluate and rank

  15. Testing method for ceramic armor and bare ceramic tiles

    NARCIS (Netherlands)

    Carton, E.P.; Roebroeks, G.H.J.J.

    2014-01-01

    TNO has developed an alternative, more configuration independent ceramic test method than the standard Depth-of-Penetration test method. In this test ceramic tiles and ceramic based armor are evaluated as target without a semi-infinite backing layer. An energy approach is chosen to evaluate and rank

  16. Uranium production from phosphates

    International Nuclear Information System (INIS)

    Ketzinel, Z.; Folkman, Y.

    1979-05-01

    According to estimates of the world's uranium consumption, exploitation of most rich sources is expected by the 1980's. Forecasts show that the rate of uranium consumption will increase towards the end of the century. It is therefore desirable to exploit poor sources not yet in use. In the near future, the most reasonable source for developing uranium is phosphate rock. Uranium reserves in phosphates are estimated at a few million tons. Production of uranium from phosphates is as a by-product of phosphate rock processing and phosphoric acid production; it will then be possible to save the costs incurred in crushing and dissolving the rock when calculating uranium production costs. Estimates show that the U.S. wastes about 3,000 tons of uranium per annum in phosphoric acid based fertilisers. Studies have also been carried out in France, Yugoslavia and India. In Israel, during the 1950's, a small plant was operated in Haifa by 'Chemical and Phosphates'. Uranium processes have also been developed by linking with the extraction processes at Arad. Currently there is almost no activity on this subject because there are no large phosphoric acid plants which would enable production to take place on a reasonable scale. Discussions are taking place about the installation of a plant for phosphoric acid production utilising the 'wet process', producing 200 to 250,000 tons P 2 O 5 per annum. It is necessary to combine these facilities with uranium production plant. (author)

  17. FATIGUE OF DENTAL CERAMICS

    Science.gov (United States)

    Zhang, Yu; Sailer, Irena; Lawn, Brian R

    2013-01-01

    Objectives Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. Data/sources The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. Conclusions Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically-assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. Clinical significance Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy. PMID:24135295

  18. Diffusion in ceramics

    CERN Document Server

    Pelleg, Joshua

    2016-01-01

    This textbook provides an introduction to changes that occur in solids such as ceramics, mainly at high temperatures, which are diffusion controlled, as well as presenting research data. Such changes are related to the kinetics of various reactions such as precipitation, oxidation and phase transformations, but are also related to some mechanical changes, such as creep. The book is composed of two parts, beginning with a look at the basics of diffusion according to Fick's Laws. Solutions of Fick’s second law for constant D, diffusion in grain boundaries and dislocations are presented along with a look at the atomistic approach for the random motion of atoms. In the second part, the author discusses diffusion in several technologically important ceramics. The ceramics selected are monolithic single phase ones, including: A12O3, SiC, MgO, ZrO2 and Si3N4. Of these, three refer to oxide ceramics (alumina, magnesia and zirconia). Carbide based ceramics are represented by the technologically very important Si-ca...

  19. Mechanical properties of ceramics

    CERN Document Server

    Pelleg, Joshua

    2014-01-01

    This book discusses the mechanical properties of ceramics and aims to provide both a solid background for undergraduate students, as well as serving as a text to bring practicing engineers up to date with the latest developments in this topic so they can use and apply these to their actual engineering work.  Generally, ceramics are made by moistening a mixture of clays, casting it into desired shapes and then firing it to a high temperature, a process known as 'vitrification'. The relatively late development of metallurgy was contingent on the availability of ceramics and the know-how to mold them into the appropriate forms. Because of the characteristics of ceramics, they offer great advantages over metals in specific applications in which hardness, wear resistance and chemical stability at high temperatures are essential. Clearly, modern ceramics manufacturing has come a long way from the early clay-processing fabrication method, and the last two decades have seen the development of sophisticated technique...

  20. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-10-01

    This is the third quarterly report on oxygen Transport Ceramic Membranes. In the following, the report describes the progress made by our university partners in Tasks 1 through 6, experimental apparatus that was designed and built for various tasks of this project, thermodynamic calculations, where applicable and work planned for the future. (Task 1) Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. (Task 2) Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. (Task 3) Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. (Task 4) Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. (Task 5) Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. (Task 6) Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  1. Decontamination of liquid radioactive waste by thorium phosphate

    International Nuclear Information System (INIS)

    Rousselle, J.; Grandjean, S.; Dacheux, N.; Genet, M.

    2004-01-01

    In the field of the complete reexamination of the chemistry of thorium phosphate and of the improvement of the homogeneity of Thorium Phosphate Diphosphate (TPD, Th 4 (PO 4 ) 4 P 2 O 7 ) prepared at high temperature, several crystallized compounds were prepared as initial powdered precursors. Due to the very low solubility products associated to these phases, their use in the field of the efficient decontamination of high-level radioactive liquid waste containing actinides (An) was carefully considered. Two main processes (called 'oxalate' and 'hydrothermal' chemical routes) were developed through a new concept combining the decontamination of liquid waste and the immobilization of the actinides in a ceramic matrix (TPD). In phosphoric media ('hydrothermal route'), the key-precursor was the Thorium Phosphate Hydrogen Phosphate hydrate (Th 2 (PO 4 ) 2 (HPO 4 ). H 2 O, TPHP, solubility product log(K S,0 0 ) ∼ - 67). The replacement of thorium by other tetravalent actinides (U, Np, Pu) in the structure, leading to the preparation of Th 2-x/2 An x/2 (PO 4 ) 2 (HPO 4 ). H 2 O solid solutions, was examined. A second method was also considered in parallel to illustrate this concept using the more well-known precipitation of oxalate as the initial decontamination step. For this method, the final transformation to single phase TPD containing actinides was purchased by heating a mixture of phosphate ions with the oxalate precipitate at high temperature. (authors)

  2. Mechanism of calcium phosphates precipitation in liquid crystals

    International Nuclear Information System (INIS)

    Prelot, B.; Zemb, T.

    2004-04-01

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

  3. Ceramic composites: Enabling aerospace materials

    Science.gov (United States)

    Levine, S. R.

    1992-01-01

    Ceramics and ceramic matrix composites (CMC) have the potential for significant impact on the performance of aerospace propulsion and power systems. In this paper, the potential benefits are discussed in broad qualitative terms and are illustrated by some specific application case studies. The key issues in need of resolution for the potential of ceramics to be realized are discussed.

  4. Osteoinduction of calcium phosphate biomaterials in small animals.

    Science.gov (United States)

    Cheng, Lijia; Shi, Yujun; Ye, Feng; Bu, Hong

    2013-04-01

    Although osteoinduction mechanism of calcium phosphate (CP) ceramics is still unclear, several essential properties have been reported, such as chemical composition, pore size and porosity, etc. In this study, calcium phosphate powder (Ca3(PO4)2, CaP, group 1), biphasic calcium phosphate ceramic powder (BCP, group 2), and intact BCP rods (group 3) were implanted into leg muscles of mice and dorsal muscles of rabbits. One month and three months after implantation, samples were harvested for biological and histological analysis. New bone tissues were observed in 10/10 samples in group 1, 3/10 samples in group 2, and 9/10 samples in group 3 at 3rd month in mice, but not in rabbits. In vitro, human mesenchymal stem cells (hMSCs) were cultured with trace CaP and BCP powder, and osteogenic differentiation was observed at day 7. Our results suggested that chemical composition is the prerequisite in osteoinduction, and pore structure would contribute to more bone formation. Copyright © 2012 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Prelot, B.; Zemb, T

    2004-04-01

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

  6. Ceramic breeder materials

    International Nuclear Information System (INIS)

    Johnson, C.E.; Kummerer, K.R.; Roth, E.

    1987-01-01

    Ceramic materials are under investigation as potential breeder material in fusion reactors. This paper will review candidate materials with respect to fabrication routes and characterization, properties in as-fabricated and irradiated condition, and experimental results from laboratory and inpile investigations on tritium transport and release. Also discussed are the resources of beryllium, which is being considered as a neutron multiplier. The comparison of ceramic properties that is attempted here aims at the identification of the most-promising material for use in a tritium breeding blanket. 82 refs., 12 figs., 5 tabs

  7. Cyclic mechanical fatigue in ceramic-ceramic composites: an update

    International Nuclear Information System (INIS)

    Lewis, D. III

    1983-01-01

    Attention is given to cyclic mechanical fatigue effects in a number of ceramics and ceramic composites, including several monolithic ceramics in which significant residual stresses should be present as a result of thermal expansion mismatches and anisotropy. Fatigue is also noted in several BN-containing ceramic matrix-particulate composites and in SiC fiber-ceramic matrix composites. These results suggest that fatigue testing is imperative for ceramics and ceramic composites that are to be used in applications subject to cyclic loading. Fatigue process models are proposed which provide a rationale for fatigue effect observations, but do not as yet provide quantitative results. Fiber composite fatigue damage models indicate that design stresses in these materials may have to be maintained below the level at which fiber pullout occurs

  8. In vitro studies of human and rat osteoclast activity on hydroxyapatite, beta-tricalcium phosphate, calcium carbonate.

    Science.gov (United States)

    Monchau, F; Lefèvre, A; Descamps, M; Belquin-myrdycz, A; Laffargue, P; Hildebrand, H F

    2002-08-01

    Investigations on the ceramic degradation caused by osteoclasts are designed to assess osteoclast-ceramic interactions and to determine which ceramics are more suitable for use as bone substitute. This study investigated the resorptive activity of osteoclasts on ceramics presenting different solubility rates. Osteoclasts isolated from new-born rat and from human giant cell tumour were cultured on different bioceramics: hydroxyapatite (HA), beta-tricalcium phosphate (TCP) and calcium carbonate (calcite). Cytoskeletal was revealed by actin labelling and ceramic surfaces were observed by scanning electron microscopy (SEM). On all materials, the distribution of actin in typical ring was revealed. SEM examinations showed a clear difference in the shape and the depth of resorption lacunae on different ceramics. On pure HA, a superficial attack, clearly visible but very little extended. Numerous resorption lacunae, deep and well-delimited were observed on pure beta-TCP, but attacks less punctually were detected too. On pure calcite, an attack with form of spikes, very widespread but superficial was revealed. Degradation measurements revealed a significant increase of P release from the phosphocalcic ceramics and of Ca from all ceramics in the presence of osteoclasts. The both cell models found these characteristics, the rat osteoclasts were also an excellent model to study the ceramic resorption.

  9. Obtaining of ceramics biphasic dense and porous

    International Nuclear Information System (INIS)

    Pallone, E.M.J.A.; Rigo, E.C.S.; Fraga, A.F.

    2010-01-01

    Among the bioceramic hydroxyapatite (HAP) and beta-tricalcium phosphate (beta-TCP) are materials commonly used in biomedical field. Their combined properties result in a material with absorbable and at the same time with bioactive surface. Called biphasic ceramics such materials respond more quickly when exposed to physiological environment. In this work, powders of HAP/beta-TCP were obtained by chemical precipitation. After obtaining the post-phase was added at a ratio of 0, 15% and 30w% aqueous solutions of corn starch in order to obtain porous bodies. After mixing the resulting solutions were dried, resigned in tablet form and sintered at 1300 deg C. The initial powder was characterized by X-ray diffraction with Rietveld refinement to quantify the phases present. Bodies-of-evidence has been characterized by calculating the bulk density, X-ray diffraction (XRD), scanning electron microscopy and diametral compression. (author)

  10. Obtaining tetracalcium phosphate and hydroxyapatite in powder form by wet method

    International Nuclear Information System (INIS)

    Oliveira, Sara Verusca de; Fook, Marcus Vinicius Lia; Araujo, Elaine Patricia; Medeiros, Keila Machado; Rabello, Guilherme Portela; Barbosa Renata; Araujo, Edcleide Maria

    2009-01-01

    The development of research in the area of advanced materials and tissue engineering has increased greatly in recent years found that bioceramics are outstanding in the replacement and regeneration of bone tissue, mainly formed by the calcium phosphate ceramics. The objective of this research is to obtain the calcium phosphate where Ca/P = 1.67 and 2.0, to observe the formation of phases after having subjected these materials to heat treatment. The calcium phosphate was produced by the wet method using a direct reaction of neutralization and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray microanalysis (EDS). The XRD results confirm the presence of hydroxyapatite phase in the sample with Ca/P = 1.67, whereas the phosphates prepared with Ca/P = 2.0 ratio show a combination of hydroxyapatite and phase β- tricalcium phosphate. The micrographs obtained are characteristic of ceramic material called calcium phosphate. EDS confirmed the presence of Ca, P and O in the material. (author)

  11. Tick-proof ceramics. Bo dani ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Shimono, F. (Ishizuka Glass Co. Ltd., Nagoya (Japan))

    1993-07-01

    Ishizuka Glass has developed SiO2-B2O3-R2O(RO) based tick-proof ceramics (trade name; Segrocera) in cooperation with Yamato Chemical Industry, insecticide maker. This article is a report on effectiveness of this ceramics. Ticks living indoors are roughly divided into two kinds, namely ticks living in a house itself and ticks which enter the house by parasitizing on animals and plants, and Segrocera has been developed aiming at the former ticks which, irrespective of its kind, need the temperature of 20-30[degree]C and the moisture of 60% or more as its breeding conditions. The tick-proof effect of Segrocera is as excellent as 90-99% and even after keeping its specimen at 75RH for 12 months, it has shown the ratio of inhibiting ticks' breeding of 98-99%. In comparison with that the effect of other tick-proof agent, pyrethroids-based aerosol is limited up to 24 hours, it is the feature of Segrocera that its life is considerably longer. Safety of Segrocera is also very high. 2 refs., 1 fig., 7 tabs.

  12. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendfra Nagabhushana

    2001-07-01

    The mechanical properties of model systems were analyzed. A reasonably accurate finite element model was implemented and a rational metric to predict the strength of ceramic/metal concentrical joints was developed. The mode of failure of the ceramic/metal joints was determined and the importance of the mechanical properties of the braze material was assessed. Thermal cycling experiments were performed on the model systems and the results were discussed. Additionally, experiments using the concept of placing diffusion barriers on the ceramic surface to limit the extent of the reaction with the braze were performed. It was also observed that the nature and morphology of the reaction zone depends greatly on the nature of the perovskite structure being used. From the experiments, it is observed that the presence of Cr in the Fe-occupied sites decreases the tendency of Fe to segregate and to precipitate out of the lattice. In these new experiments, Ni was observed to play a major role in the decomposition of the ceramic substrate.

  13. Coated ceramic breeder materials

    Science.gov (United States)

    Tam, Shiu-Wing; Johnson, Carl E.

    1987-01-01

    A breeder material for use in a breeder blanket of a nuclear reactor is disclosed. The breeder material comprises a core material of lithium containing ceramic particles which has been coated with a neutron multiplier such as Be or BeO, which coating has a higher thermal conductivity than the core material.

  14. Dense ceramic articles

    International Nuclear Information System (INIS)

    Cockbain, A.G.

    1976-01-01

    A method is described for the manufacture of articles of substantially pure dense ceramic materials, for use in severe environments. Si N is very suitable for use in such environments, but suffers from the disadvantage that it is not amenable to sintering. Some disadvantages of the methods normally used for making articles of Si N are mentioned. The method described comprises mixing a powder of the substantially pure ceramic material with an additive that promotes densification, and which is capable of nuclear transmutation into a gas when exposed to radiation, and hot pressing the mixture to form a billet. The billet is then irradiated to convert the additive into a gas which is held captive in the billet, and it is then subjected to a hot forging operation, during which the captive gas escapes and an article of substantially pure dense ceramic material is forged. The method is intended primarily for use for Si N, but may be applied to other ceramic materials. The additive may be Li or Be or their compounds, to the extent of at least 5 ppm and not more than 5% by weight. Irradiation is effected by proton or neutron bombardment. (UK)

  15. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-05-01

    The mechanical properties of model systems were analyzed. A reasonably accurate finite element model was implemented and a rational metric to predict the strength of ceramic/metal concentrical joints was developed. The mode of failure of the ceramic/metal joints was determined and the importance of the mechanical properties of the braze material was assessed. Thermal cycling experiments were performed on the model systems and the results were discussed. Additionally, experiments using the concept of placing diffusion barriers on the ceramic surface to limit the extent of the reaction with the braze were performed. It was also observed that the nature and morphology of the reaction zone depends greatly on the nature of the perovskite structure being used. From the experiments, it is observed that the presence of Cr in the Fe-occupied sites decreases the tendency of Fe to segregate and to precipitate out of the lattice. In these new experiments, Ni was observed to play a major role in the decomposition of the ceramic substrate.

  16. Thermoelectric, band structure, chemical bonding and dispersion of optical constants of new metal chalcogenides Ba{sub 4}CuGa{sub 5}Q{sub 12} (Q=S, Se)

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A.H. [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Azam, Sikander, E-mail: sikander.physicst@gmail.com [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic)

    2014-08-01

    The electronic structure and dispersion of optical constants of the Ba{sub 4}CuGa{sub 5}S{sub 12} and Ba{sub 4}CuGa{sub 5}Se{sub 12} compounds were calculated by the first-principles full-potential linearized augmented plane wave (FPLAPW) method. We employed the local density approximation (LDA), generalized gradient approximation (GGA) and Engel–Vosko GGA (EVGGA) to calculate the electronic structures, Fermi surface, thermoelectric, chemical bonding and dispersion of optical constants of these compounds. By investigating the influence of replacing S by Se, it has been found that the charge density around ‘Ga’ is greater in Ba{sub 4}CuGa{sub 5}Se{sub 12} than Ba{sub 4}CuGa{sub 5}S{sub 12}. Fermi surface of Ba{sub 4}CuGa{sub 5}S{sub 12} consists of an electronic sheet only because there is no empty region while Ba{sub 4}CuGa{sub 5}Se{sub 12} contains both holes and electronic sheets because this compound contains both empty and shaded region. As we replace S by Se the heights of the peaks decreases as a results the reflectivity also decreases. It is noticed that the reflectivity is over 68% (60%) for Ba{sub 4}CuGa{sub 5}S{sub 12} (Ba{sub 4}CuGa{sub 5}Se{sub 12}) compounds within the energy range studied. This implies that the material will serve as a good reflector. By replacing S by Se the figure of merit values increases from 0.97 to 1.0, which shows the good thermoelectric behavior of both compounds. - Highlights: • DFT-FPLAPW method used for calculating the properties. • For predicting the chemical bonding the charge density behavior is studied in 2D. • The optical properties were also calculated and analyzed. • The Fermi surface is composed of two bands crossing along the EF level. • The thermoelectric properties have also been calculated.

  17. Chemical bond properties and charge transfer bands of O(2-)-Eu(3+), O(2-)-Mo(6+) and O(2-)-W(6+) in Eu(3+)-doped garnet hosts Ln3M5O12 and ABO4 molybdate and tungstate phosphors.

    Science.gov (United States)

    Liu, Xiaoguang; Li, Ling; Noh, Hyeon Mi; Moon, Byung Kee; Choi, Byung Chun; Jeong, Jung Hyun

    2014-06-21

    Charge transfer (CT) energy from the ligand to the central ions is an important factor in luminescence properties for rare earth doped inorganic phosphors. The dielectric theory of complex crystals was used to calculate chemical bond properties. Combining the photoluminescence and the dielectric theory of complex crystals, the CT bands of O(2-)-Eu(3+), O(2-)-Mo(6+) and O(2-)-W(6+) for Eu(3+)-doped inorganic phosphors have been investigated experimentally and theoretically. Taking Eu(3+)-doped Ln3M5O12 (Ln = Y, Lu and M = Al, Ga), Gd3Ga5O12, MMoO4 (M = Ca, Sr, Ba) and MWO4 (M = Ca, Sr, Ba) as typical phosphors, we investigated the effects of the cation size on the CT bands and chemical bond properties including the bond length (d), the covalency (fc), the bond polarizability (αb) and the environmental factor (he) of O(2-)-Eu(3+), O(2-)-Mo(6+) and O(2-)-W(6+), respectively. For systematic isostructural Ln3M5O12 (Ln = Y, Lu and M = Al, Ga) phosphors, with the increasing M ion radius, the bond length of Ln-O decreases, but fc and αb increase, which is the main reason that the environmental factor increased. For the isostructural MMoO4:Eu, with the increasing M ion radius, the Mo-O bond length increases, but fc and αb decrease, and thus he decreases. However, in the compound system MWO4:Eu (M = Ca, Ba) with the increasing M ion radius, the O-W bond length increases, but fc and αb increase, and thus he increases and the O-W CT energy decreases. Their O(2-)-Eu(3+), O(2-)-Mo(6+) and O(2-)-W(6+) CT bands as well as their full width at half maximum (FWHM) were directly influenced by he. And with the increasing he, CT bands of O-Eu or O-Mo or O-W decrease and their FWHM increases. These results indicate a promising approach for changing the material properties, searching for new Eu(3+) doped molybdate, tungstate or other oxide phosphors and analyzing the experimental result.

  18. Chemistry of tetravalent actinides phosphates. The thorium phosphate-diphosphate as immobilisation matrix of actinides; Chimie des phosphates d'actinides tetravalents. Le phosphate-diphosphate de thorium en tant que matrice d'imobilisation des actinides

    Energy Technology Data Exchange (ETDEWEB)

    Dacheux, N

    2002-07-01

    The author presents in this document its scientific works from 1992 to 2001, in order to obtain the enabling to manage scientific and chemical researches at the university Paris Sud Orsay. The first part gives an abstract of the thesis on the characterizations, lixiviation and synthesis of uranium and thorium based phosphate matrix in the framework of the search for a ceramic material usable in the radioactive waste storage. The second part presents briefly the researches realized at the CEA, devoted to a reliable, independent and accurate measure of some isotopes activity. The last part presents the abstracts of researches activities from 1996 to 2001 on the tetravalent actinides phosphates chemistry, the sintering of PDT and solid solutions of PDTU and the kinetic and thermodynamical studies of the PDT dissolution. Many references and some publication in full text are provided. (A.L.B.)

  19. Triphenyl phosphate allergy from spectacle frames

    DEFF Research Database (Denmark)

    Carlsen, Lars; Andersen, Klaus E.; Egsgaard, Helge

    1986-01-01

    A case of triphenyl phosphate allergy from spectacle frames is reported. Patch tests with analytical grade triphenyl phosphate, tri-m-cresyl phosphate, and tri-p-cresyl phosphate in the concentrations 5%, 0.5% and 0.05% pet. showed positive reactions to 0.05% triphenyl phosphate and 0.5% tri...... triphenyl phosphate allergy in our patient....

  20. 21 CFR 184.1434 - Magnesium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium phosphate. 184.1434 Section 184.1434 Food... Specific Substances Affirmed as GRAS § 184.1434 Magnesium phosphate. (a) Magnesium phosphate includes both magnesium phosphate, dibasic, and magnesium phosphate, tribasic. Magnesium phosphate, dibasic (MgHPO4·3H2O...

  1. Wonderland of ceramics superplasticity; Ceramics chososei no sekai

    Energy Technology Data Exchange (ETDEWEB)

    Wakai, F. [National Industrial Research Inst. of Nagoya, Nagoya (Japan)

    1995-07-01

    It has been ten years since it was found that ceramics, which is strong and hard at room temperatures and does not deform at all, may exhibit a superplasticity phenomenon at high temperatures that it endlessly elongates when pulled as if it were chewing gum. This phenomenon is one of peculiar behaviours which nano-crystal ceramics, pulverized to an extent that the crystalline particle size is on the order of nanometers, show. The application of superplasticity made the material engineers`s old dream come true that hard ceramics are arbitrarily deformed and machined like metal. Using as models materials such as silicone nitride, alumina and zirconia, this paper describes the history and deformation mechanism of ceramics superplasticity, material design aiming at superplasticization and application of ceramics superplasticity to the machining technology. Furthermore, it describes the trend and future development of international joint researches on the basic surveys on ceramics superplasticity. 25 refs., 11 figs.

  2. Renal phosphate handling: Physiology

    Directory of Open Access Journals (Sweden)

    Narayan Prasad

    2013-01-01

    Full Text Available Phosphorus is a common anion. It plays an important role in energy generation. Renal phosphate handling is regulated by three organs parathyroid, kidney and bone through feedback loops. These counter regulatory loops also regulate intestinal absorption and thus maintain serum phosphorus concentration in physiologic range. The parathyroid hormone, vitamin D, Fibrogenic growth factor 23 (FGF23 and klotho coreceptor are the key regulators of phosphorus balance in body.

  3. Influence of MgO doping in hot-pressing tricalcium phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Acchar, W; Costa, A C S [Department of Physics, Federal University of Rio Grande do Norte, Natal-RN, Brazil, CEP:59072-97 (Brazil); Cairo, C A A, E-mail: acchar@dfte.ufrn.br [Centro Tecnico Aeroespacial (CTA), Sao Jose dos Campos - SP (Brazil)

    2011-10-29

    Tricalcium phosphate ceramics (TCP) has been widely investigated. The main advantage of this bioceramic is its bioresorbable behavior. The factor that still limits the application of these materials as temporary implants is the low strength resistance of the TCP sintered material. The tricalcium phosphate presents an allotropic transformation {beta} to {alpha} phase around 1250 deg. C that degrades its resistance, limiting the sintering temperature of the compacted samples. The objective of this work is to study the physical and mechanical properties of hot-pressed tricalcium phosphate with MgO additions. The results obtained have shown that the hot-pressed process increases significantly the mechanical properties of TCP materials. The addition of MgO has not improved the sintering process and the properties of hot-pressed tricalcium phosphate.

  4. Production and characterization of setting hydraulic cements based on calcium phosphate

    International Nuclear Information System (INIS)

    Oliveira, Luci C. de; Rigo, Eliana C.S.; Santos, Luis A dos; Boschi, Anselmo Ortega; Carrodeguas, Raul G.

    1997-01-01

    Setting hydraulic cements based on calcium phosphate has risen great interest in scientific literature during recent years due to their total bio compatibility and to the fact that they harden 'in situ', providing easy handling and adaptation to the shape and dimensions of the defect which requires correction, differently from the predecessors, the calcium phosphate ceramics (Hydroxy apatite, β-tri calcium phosphate, biphasic, etc) in the shape of dense or porous blocks and grains. In the work, three calcium-phosphate cement compositions were studied. The resulting compositions were characterized according to the following aspects: setting times, pH, mechanical resistance, crystalline phases, microstructure and solubility in SBF (Simulated Body Fluid). The results show a potential use for the compositions. (author)

  5. Ultrasonic and Thermal Properties of Borate and Phosphate Glasses Containing Bismuth and Lead

    International Nuclear Information System (INIS)

    Aziz, Sidek Hj. Abd.; Ahmad, Hamezan; Wahab, Zaidan A.; Sulaiman, Zainal Abidin; Talib, Zainal Abidin; Shaari, A. Halim; Senin, H. B.

    2007-01-01

    Systematic series of (B2O3,P2O5)-Bi2O3-PbO glasses have been successfully prepared by using the rapid quenching technique in which each oxide content changes for every series on the basis of its weight percentage. Their amorphous natures were confirmed earlier by the x-ray diffraction technique. The experimental results show that the density of both glasses, determined by using the Archimedes principle, increases with the glass modifier content. This is due to the replacement of Bi2O3 and PbO in the borate and phosphate glassy networks. The molar volume for borate glass increases with the addition of bismuth and lead oxides, but a reverse trend occurs for the phosphate glass. The longitudinal and shear ultrasound velocities, determined by the MBS 8000 system, of both lead bismuth borate and phosphate glasses show a decreasing trend as more PbO and Bi2O3 are added to the glass system. The increase in PbO/Bi2O3 content was probably related to the progressive increase in the concentration of non-bridging oxygen (NBOs). Thermal studies of the glass, using the Labsys DTA-Setaram machine, show that the value of the glass transition temperature (Tg) is closely related to the chemical bond in the system. In lead bismuth borate glasses, the addition of more Pb2+ and Bi3+ results in a more dominant ionic bond character in the system and hence decreases Tg of the sample. However, in lead bismuth phosphate glasses, the addition of Pb2+ and Bi3+ not only failed to weaken the covalent character in P-O-P bonds, but strengthened it further, leading to an increment in the values of Tg

  6. Novel selenium containing boro-phosphate glasses: Preparation and structural study

    International Nuclear Information System (INIS)

    Ciceo-Lucacel, R.; Radu, T.; Ponta, O.; Simon, V.

    2014-01-01

    We synthesized a new boro-phosphate glass system with different %mol SeO 2 content by conventional melt quenching technique. All samples were obtained in a glassy state with the vitreous structure confirmed by X-ray diffraction analysis. Scanning electron microscopy (SEM) revealed some non-homogeneous domains on the glasses surface, and their tendency to link each other once the selenium oxide content increases. Energy-dispersive X-ray analysis (EDAX) indicated similar elemental composition in different regions of each sample. X-ray photoelectron spectroscopy (XPS) was used to determine the nature of chemical bonding and the elemental composition at the sample surfaces, and Fourier transform infrared (FT-IR) spectroscopy was used to determine the structural groups in the obtained glass structure. Based on FT-IR results, the glass structure at short range order consists mainly of small phosphate units such as pyrophosphate (i.e. P 2 O 7 4− dimmers or terminating groups at the end of phosphate chains) and some metaphosphate (i.e. PO 3 − middle groups in the phosphate chains) units. The boron atoms are mainly placed in three-coordinated sites in BØ 3 or BØ 2 O − units. A small contribution of BØ 4 − units was also detected from the FT-IR spectra of glasses. For SeO 2 content higher than 5 mol%, the modifier role of selenium ions is strongly reflected on the local structure dominated in this case by pyrophosphate units. - Highlights: • New P 2 O 5 -CaO-B 2 O 3 -SeO 2 glasses synthesized by conventional melt quenching method. • Evidences for the Se ions modifier role in the local structure by FT-IR and XPS. • Significant advances in understanding the structural properties of the new system

  7. Novel selenium containing boro-phosphate glasses: preparation and structural study.

    Science.gov (United States)

    Ciceo-Lucacel, R; Radu, T; Ponta, O; Simon, V

    2014-06-01

    We synthesized a new boro-phosphate glass system with different %mol SeO2 content by conventional melt quenching technique. All samples were obtained in a glassy state with the vitreous structure confirmed by X-ray diffraction analysis. Scanning electron microscopy (SEM) revealed some non-homogeneous domains on the glasses surface, and their tendency to link each other once the selenium oxide content increases. Energy-dispersive X-ray analysis (EDAX) indicated similar elemental composition in different regions of each sample. X-ray photoelectron spectroscopy (XPS) was used to determine the nature of chemical bonding and the elemental composition at the sample surfaces, and Fourier transform infrared (FT-IR) spectroscopy was used to determine the structural groups in the obtained glass structure. Based on FT-IR results, the glass structure at short range order consists mainly of small phosphate units such as pyrophosphate (i.e. P2O7(4-) dimmers or terminating groups at the end of phosphate chains) and some metaphosphate (i.e. PO3(-) middle groups in the phosphate chains) units. The boron atoms are mainly placed in three-coordinated sites in BØ3 or BØ2O(-) units. A small contribution of BØ4(-) units was also detected from the FT-IR spectra of glasses. For SeO2 content higher than 5mol%, the modifier role of selenium ions is strongly reflected on the local structure dominated in this case by pyrophosphate units. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. The solid phase extraction of some metal ions using palladium nanoparticles attached to silica gel chemically bonded by silica-bonded N-propylmorpholine as new sorbent prior to their determination by flame atomic absorption spectroscopy.

    Science.gov (United States)

    Ghaedi, M; Rezakhani, M; Khodadoust, S; Niknam, K; Soylak, M

    2012-01-01

    In this research at first palladium nanoparticle attached to a new chemically bonded silica gel has been synthesized and has been characterized with different techniques such as X-ray diffraction (XRD), fourier transform infrared (FT-IR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Then, this new sorbent (chemically modified silica gel with N-propylmorpholine (PNP-SBNPM)) was efficiently used for preconcentration of some metal ions in various food samples. The influence of effective variables including mass of sorbent, flow rate, pH of sample solutions and condition of eluent such as volume, type and concentration on the recoveries of understudy metal ions were investigated. Following the optimization of variables, the interfering effects of some foreign ions on the preconcentration and determination of the investigated metal ions described. At optimum values of variables, all investigated metal ions were efficiently recovered with efficiency more than 95%, relative standard deviation (RSD) between 2.4 and 2.8, and detection limit in the range of 1.4-2.7 ng mL⁻¹. The present method is simple and rapidly applicable for the determination of the understudied metal ions (ng mL⁻¹) in different natural food samples.

  9. The Solid Phase Extraction of Some Metal Ions Using Palladium Nanoparticles Attached to Silica Gel Chemically Bonded by Silica-Bonded N-Propylmorpholine as New Sorbent prior to Their Determination by Flame Atomic Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    M. Ghaedi

    2012-01-01

    Full Text Available In this research at first palladium nanoparticle attached to a new chemically bonded silica gel has been synthesized and has been characterized with different techniques such as X-ray diffraction (XRD, fourier transform infrared (FT-IR, transmission electron microscopy (TEM, and scanning electron microscopy (SEM. Then, this new sorbent (chemically modified silica gel with N-propylmorpholine (PNP-SBNPM was efficiently used for preconcentration of some metal ions in various food samples. The influence of effective variables including mass of sorbent, flow rate, pH of sample solutions and condition of eluent such as volume, type and concentration on the recoveries of understudy metal ions were investigated. Following the optimization of variables, the interfering effects of some foreign ions on the preconcentration and determination of the investigated metal ions described. At optimum values of variables, all investigated metal ions were efficiently recovered with efficiency more than 95%, relative standard deviation (RSD between 2.4 and 2.8, and detection limit in the range of 1.4–2.7 ng mL−1. The present method is simple and rapidly applicable for the determination of the understudied metal ions (ng mL−1 in different natural food samples.

  10. Long-term survival of calcium phosphate-coated dental implants: a meta-analytical approach to the clinical literature

    NARCIS (Netherlands)

    Oirschot, B.A. van; Bronkhorst, E.M.; Beucken, J.J.J.P van den; Meijer, G.J.; Jansen, J.A.; Junker, R.

    2013-01-01

    BACKGROUND: Calcium phosphate ceramic coatings have the potential to compensate for challenging bone conditions such as delayed or impaired bone healing and low bone quantity or density. Thus, the increasing universal prevalence of subjects with such challenging bone conditions might be paralleled

  11. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Mechanical properties and microstructures of a chemically bonded phosphate ceramic (CBPC) and its composite with 1.0 wt% graphite nanoplatelets (GNPs) reinforcement have been investigated. Microstructure was identified by using optical and scanning electron microscopes, X-ray tomography, and X-ray diffraction.

  12. Positron annihilation in transparent ceramics

    International Nuclear Information System (INIS)

    Husband, P; Selim, F A; Bartošová, I; Slugeň, V

    2016-01-01

    Transparent ceramics are emerging as excellent candidates for many photonic applications including laser, scintillation and illumination. However achieving perfect transparency is essential in these applications and requires high technology processing and complete understanding for the ceramic microstructure and its effect on the optical properties. Positron annihilation spectroscopy (PAS) is the perfect tool to study porosity and defects. It has been applied to investigate many ceramic structures; and transparent ceramics field may be greatly advanced by applying PAS. In this work positron lifetime (PLT) measurements were carried out in parallel with optical studies on yttrium aluminum garnet transparent ceramics in order to gain an understanding for their structure at the atomic level and its effect on the transparency and light scattering. The study confirmed that PAS can provide useful information on their microstructure and guide the technology of manufacturing and advancing transparent ceramics. (paper)

  13. Joining ceramics, glass and metal

    International Nuclear Information System (INIS)

    Kraft, W.

    1989-01-01

    In many areas of electronics, engine manufacturing, machine and apparatus construction and aearospace, different combinations of materials such as ceramics/metal and glass/metal are gaining increasingly in importance. The proceedings cover the 53 papers presented to the 3rd International Conference on Joining Ceramics, Glass and Metal, held in Bad Nauheim (FRG) from April 26 to 28, 1989. The papers discuss problems and results under the following main topics of the conference: (1) Active brazing applied to non-oxide ceramics and oxide ceramics. (2) Diffusion bonding of metals and ceramics. (3) Friction welding, reaction bonding, and other joining methods. (4) Properties of metal-ceramic joints (as e.g. residual stress, fracture toughness, thermal stress) and various investigation methods for their determination. (MM) [de

  14. Ceramic hot-gas filter

    Science.gov (United States)

    Connolly, Elizabeth Sokolinski; Forsythe, George Daniel; Domanski, Daniel Matthew; Chambers, Jeffrey Allen; Rajendran, Govindasamy Paramasivam

    1999-01-01

    A ceramic hot-gas candle filter having a porous support of filament-wound oxide ceramic yarn at least partially surrounded by a porous refractory oxide ceramic matrix, and a membrane layer on at least one surface thereof. The membrane layer may be on the outer surface, the inner surface, or both the outer and inner surface of the porous support. The membrane layer may be formed of an ordered arrangement of circularly wound, continuous filament oxide ceramic yarn, a ceramic filler material which is less permeable than the filament-wound support structure, or some combination of continuous filament and filler material. A particularly effective membrane layer features circularly wound filament with gaps intentionally placed between adjacent windings, and a filler material of ceramic particulates uniformly distributed throughout the gap region. The filter can withstand thermal cycling during backpulse cleaning and is resistant to chemical degradation at high temperatures.

  15. Bioactivity of thermal plasma synthesized bovine hydroxyapatite/glass ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Yoganand, C P; Selvarajan, V [Plasma Laboratory, Department of Physics, Bharathiar University, Coimbatore - 641 046 (India); Rouabhia, Mahmoud [Faculte de Medicine Dentaire et Groupe de Recherche en E cologie Buccale, Pavillon de Medecine Dentaire, Local 1728, Universite Laval, Quebec City, Quebec, G1K 7P4 (Canada); Cannillo, Valeria; Sola, Antonella, E-mail: vselvrjn47@rediffmail.co [Dipartimento di Ingegneria dei Materiali e dell' Ambiente, University of Modena and Reggio Emilia, Modena (Italy)

    2010-02-01

    Bone injuries and failures often require the inception of implant biomaterials. Research in this area is receiving increasing attention worldwide. A variety of artificial bone materials, such as metals, polymeric materials, composites and ceramics, are being explored to replace diseased bones. Calcium phosphate ceramics are currently used as biomaterials for many applications in both dentistry and orthopedics. Bioactive silicate-based glasses show a higher bioactive behaviour than calcium phosphate materials. It is very interesting to study the mixtures of HA and silicate-based glasses. In the present study; natural bovine hydroxyapatite / SiO{sub 2}-CaO-MgO glass composites were produced using the Transferred arc plasma (TAP) melting method. TAP melting route is a brisk process of preparation of glass-ceramics in which the raw materials are melted in the plasma and crystallization of the melt occurs while cooling down at a much faster rate in relatively short processing times compared to the conventional methods of manufacture of glass ceramics/composites. It is well known that; one essential step to the understanding of the biological events occurring at the bone tissue/material interface is the biological investigation by in vitro tests. Cell lines are commonly used for biocompatibility tests, and are very efficient because of their reproducibility and culture facility. In this study, we report the results of a study on the response of primary cultures of human fibroblast cells to TAP melted bioactive glass ceramics.

  16. Bioactivity of thermal plasma synthesized bovine hydroxyapatite/glass ceramic composites

    Science.gov (United States)

    Yoganand, C. P.; Selvarajan, V.; Rouabhia, Mahmoud; Cannillo, Valeria; Sola, Antonella

    2010-02-01

    Bone injuries and failures often require the inception of implant biomaterials. Research in this area is receiving increasing attention worldwide. A variety of artificial bone materials, such as metals, polymeric materials, composites and ceramics, are being explored to replace diseased bones. Calcium phosphate ceramics are currently used as biomaterials for many applications in both dentistry and orthopedics. Bioactive silicate-based glasses show a higher bioactive behaviour than calcium phosphate materials. It is very interesting to study the mixtures of HA and silicate-based glasses. In the present study; natural bovine hydroxyapatite / SiO2-CaO-MgO glass composites were produced using the Transferred arc plasma (TAP) melting method. TAP melting route is a brisk process of preparation of glass-ceramics in which the raw materials are melted in the plasma and crystallization of the melt occurs while cooling down at a much faster rate in relatively short processing times compared to the conventional methods of manufacture of glass ceramics/composites. It is well known that; one essential step to the understanding of the biological events occurring at the bone tissue/material interface is the biological investigation by in vitro tests. Cell lines are commonly used for biocompatibility tests, and are very efficient because of their reproducibility and culture facility. In this study, we report the results of a study on the response of primary cultures of human fibroblast cells to TAP melted bioactive glass ceramics.

  17. Ceramics for fusion applications

    International Nuclear Information System (INIS)

    Clinard, F.W. Jr.

    1987-01-01

    Ceramics are required for a variety of uses in both near-term fusion devices and in commercial powerplants. These materials must retain adequate structural and electrical properties under conditions of neutron, particle and ionizing irradiation; thermal and applied stresses; and physical and chemical sputtering. Ceramics such as Al 2 O 3 , MgAl 2 O 4 , BeO, Si 3 N 4 and SiC are currently under study for fusion applications, and results to date show widely-varying responses to the fusion environment. Materials can be identified today that will meet initial operating requirements, but improvements in physical properties are needed to achieve satisfactory lifetimes for critical applications. (author)

  18. Ceramics for fusion applications

    International Nuclear Information System (INIS)

    Clinard, F.W. Jr.

    1986-01-01

    Ceramics are required for a variety of uses in both near-term fusion devices and in commercial powerplants. These materials must retain adequate structural and electrical properties under conditions of neutron, particle, and ionizing irradiation; thermal and applied stresses; and physical and chemical sputtering. Ceramics such as Al 2 O 3 , MgAl 2 O 4 , BeO, Si 3 N 4 and SiC are currently under study for fusion applications, and results to date show widely-varying response to the fusion environment. Materials can be identified today which will meet initial operating requirements, but improvements in physical properties are needed to achieve satisfactory lifetimes for critical applications

  19. Triphenyl phosphate allergy from spectacle frames

    DEFF Research Database (Denmark)

    Carlsen, L; Andersen, K E; Egsgaard, Helge

    1986-01-01

    A case of triphenyl phosphate allergy from spectacle frames is reported. Patch tests with analytical grade triphenyl phosphate, tri-m-cresyl phosphate, and tri-p-cresyl phosphate in the concentrations 5%, 0.5% and 0.05% pet. showed positive reactions to 0.05% triphenyl phosphate and 0.5% tri......-m-cresyl phosphate, but no reaction to tri-p-cresyl phosphate. Gas chromatography of the tricresyl phosphate 5% pet. patch test material supplied from Trolab showed that it contained a mixture of a wide range of triaryl phosphates, including 0.08% triphenyl phosphate which is above the threshold for detecting...

  20. Piezoelectric Ceramics Characterization

    National Research Council Canada - National Science Library

    Jordan, T

    2001-01-01

    ... the behavior of a piezoelectric material. We have attempted to cover the most common measurement methods as well as introduce parameters of interest. Excellent sources for more in-depth coverage of specific topics can be found in the bibliography. In most cases, we refer to lead zirconate titanate (PZT) to illustrate some of the concepts since it is the most widely used and studied piezoelectric ceramic to date.

  1. Advanced ceramic in structural engineering

    OpenAIRE

    Alonso Rodea, Jorge

    2012-01-01

    The work deals with "Advanced Ceramics in Structural Engineering”. Throughout this work we present the different types of ceramic that are currently in wider use, and the main research lines that are being followed. Ceramics have very interesting properties, both mechanical and electrical and refractory where we can find some of the most interesting points of inquiry. Through this work we try tounderstand this complex world, analyzing both general and specific properties of ...

  2. Mechanical behaviour of new zirconia-hydroxyapatite ceramic materials

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, J.A.; Morejon, L. [La Habana Univ. (Cuba). Centro de Biomateriales; Martinez, S. [Barcelona Univ. (Spain). Dept. Cristallografia, Mineralogia; Ginebra, M.P.; Carlsson, N.; Fernandez, E.; Planell, J.A. [Universidad Politecnica de Cataluna, Barcelona (Spain). CREB; Clavaguera-Mora, M.T.; Rodriguez-Viejo, J. [Universitat Autonoma de Barcelona (Spain). Dept. de Fisica

    2001-07-01

    In this work a new zirconia-hydroxyapatite ceramic material was obtained by uniaxial pressing and sintering in humid environment. The powder X-ray diffraction (XRD) patterns and infrared spectra (FT-IR) showed that the hydroxyapatite (HA) is the only calcium phosphate phase present. The fracture toughness for HA with 20 wt.% of magnesia partially stabilised zirconia (Mg-PSZ) was around 2.5 times higher than those obtained for HA pure, also the highest value of bending strength (160 MPa) was obtained for material reinforced with Mg-PSZ. For the MgPSZ-HA (20%) the fracture mechanism seems to be less transgranular. (orig.)

  3. Ion conductivity of nasicon ceramics

    International Nuclear Information System (INIS)

    Hoj, J.W.; Engell, J.

    1989-01-01

    The Nasicon ss ,Na 1 + X Zr 2 Si X P 3 - X O 12 o , X , 3, includes some of the best solid state sodium conductors known today. Compositions in the interval 1.6 , X , 2.6 show conductivities comparable to the best β double-prime-alumina ceramics. It is well known that the ion conductivity of β-alumina is strongly dependent on the texture of the ceramic. Here a similar behavior is reported for Nasicon ceramics. Ceramics of the bulk composition Na 2.94 Zr 1.49 Si 2.20 P 0.80 O 10.85 were prepared by a gel method. The final ceramics consist of Nasicon crystals with x = 2.14 and a glass phase. The grain size and texture of the ceramics were controlled by varying the thermal history of the gel based raw materials and the sintering conditions. The room temperature resistivity of the resulting ceramics varies from 3.65*10 3 ohm cm to 1.23*10 3 ohm cm. Using the temperature comparison method and estimates of the area of grain boundaries in the ceramics, the resistivity of the Nasicon phase is estimated to be 225 ohm cm at 25 degrees C. B 2 O 3 - or Al 2 O 3 -doping of the glass bearing Nasicon ceramic lower the room temperature resistivity by a factor 2 to 5. The dopants do not substitute into the Nasicon phase in substantial amounts

  4. The ultrastructure and processing properties of Straumann Bone Ceramic and NanoBone.

    Science.gov (United States)

    Dietze, S; Bayerlein, T; Proff, P; Hoffmann, A; Gedrange, T

    2006-02-01

    The ultrastructure, fundamental chemistry, and processing modes of fully synthetic bone grafting materials are relevant to the reconstruction of osseous defects. Rapid progress in the profitable market of biomaterials has led to the development of various bone substitutes. Despite all these efforts, an ideal and full substitute of autologous bone is not yet in sight. With regard to anorganic calcium phosphate ceramics, Straumann Bone Ceramic and NanoBone are compared. These have a similar composition and are osteoconductive, which indispensably requires contact with well-vascularised bone.

  5. Integrated assessment of the phosphate industry

    International Nuclear Information System (INIS)

    Ryan, M.T.; Cotter, S.J.

    1980-05-01

    The phosphate industry in the United States includes three major activities, namely, mining and milling of phosphate rock, phosphate product manufacture, and phosphate product use. Phosphatic materials contain uranium, thorium, and their decay products in greater than background amounts. This assessment of the radiological impacts associated with the redistribution of radioactive components of phosphate materials may provide insight into the effects of uranium extraction from phosphate materials for use in the nuclear fuel cycle

  6. Pyridoxal phosphate-dependent neonatal epileptic encephalopathy

    OpenAIRE

    Bagci, S; Zschocke, J; Hoffmann, G F; Bast, T; Klepper, J; Müller, A; Heep, A; Bartmann, P; Franz, A R

    2009-01-01

    Pyridox(am)ine-5′-phosphate oxidase converts pyridoxine phosphate and pyridoxamine phosphate to pyridoxal phosphate, a cofactor in many metabolic reactions, including neurotransmitter synthesis. A family with a mutation in the pyridox(am)ine-5′-phosphate oxidase gene presenting with neonatal seizures unresponsive to pyridoxine and anticonvulsant treatment but responsive to pyridoxal phosphate is described. Pyridoxal phosphate should be considered in neonatal epileptic encephalopathy unrespons...

  7. One hundred years of Lewis Chemical Bond!

    Indian Academy of Sciences (India)

    2016-09-20

    , it did not take long for chemists to realize that noble gases can form bonds with other elements, under appropriate conditions. Hydrogen bonding is discussed in articles by Banerjee, Bhattacharya and Chakraborty; Karir, ...

  8. The correlation theory of the chemical bond

    Czech Academy of Sciences Publication Activity Database

    Szalay, S.; Barcza, G.; Szilvási, T.; Veis, Libor; Legeza, Ö.

    2017-01-01

    Roč. 7, MAY 2017 (2017), č. článku 2237. ISSN 2045-2322 R&D Projects: GA ČR GA16-12052S Institutional support: RVO:61388955 Keywords : density matrix * quantum chemistry * theoretical model Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.259, year: 2016

  9. One hundred years of Lewis Chemical Bond!

    Indian Academy of Sciences (India)

    2016-09-20

    Sep 20, 2016 ... Having understood the stable electronic configuration of the rare gases, Lewis suggested that H and F atom can both attain such configuration, if they were to share one electron with each other. He developed a cubic model of atoms with each surrounded by 8 electrons after forming electron pair bonds.

  10. The chemical bond as an emergent phenomenon.

    Science.gov (United States)

    Golden, Jon C; Ho, Vinh; Lubchenko, Vassiliy

    2017-05-07

    We first argue that the covalent bond and the various closed-shell interactions can be thought of as symmetry broken versions of one and the same interaction, viz., the multi-center bond. We use specially chosen molecular units to show that the symmetry breaking is controlled by density and electronegativity variation. We show that the bond order changes with bond deformation but in a step-like fashion, regions of near constancy separated by electronic localization transitions. These will often cause displacive transitions as well so that the bond strength, order, and length are established self-consistently. We further argue on the inherent relation of the covalent, closed-shell, and multi-center interactions with ionic and metallic bonding. All of these interactions can be viewed as distinct sectors on a phase diagram with density and electronegativity variation as control variables; the ionic and covalent/secondary sectors are associated with on-site and bond-order charge density wave, respectively, the metallic sector with an electronic fluid. While displaying a contiguity at low densities, the metallic and ionic interactions represent distinct phases separated by discontinuous transitions at sufficiently high densities. Multi-center interactions emerge as a hybrid of the metallic and ionic bond that results from spatial coexistence of delocalized and localized electrons. In the present description, the issue of the stability of a compound is that of the mutual miscibility of electronic fluids with distinct degrees of electron localization, supra-atomic ordering in complex inorganic compounds coming about naturally. The notions of electronic localization advanced hereby suggest a high throughput, automated procedure for screening candidate compounds and structures with regard to stability, without the need for computationally costly geometric optimization.

  11. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    Science.gov (United States)

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Inflammatory cell response to calcium phosphate biomaterial particles: an overview.

    Science.gov (United States)

    Velard, Frédéric; Braux, Julien; Amedee, Joëlle; Laquerriere, Patrice

    2013-02-01

    Bone is a metabolically active and highly organized tissue consisting of a mineral phase of hydroxyapatite (HA) and amorphous calcium phosphate (CaP) crystals deposited in an organic matrix. One objective of bone tissue engineering is to mimic the chemical and structural properties of this complex tissue. CaP ceramics, such as sintered HA and beta-tricalcium phosphate, are widely used as bone substitutes or prosthesis coatings because of their osteoconductive properties. These ceramic interactions with tissues induce a cell response that can be different according to the composition of the material. In this review, we discuss inflammatory cell responses to CaP materials to provide a comprehensive overview of mechanisms governing the integration or loosening of implants, which remains a major concern in tissue engineering. A focus on the effects of the functionalization of CaP biomaterials highlights potential ways to increase tissue integration and limit rejection processes. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  13. Deodorant ceramic catalyst. Dasshu ceramics shokubai

    Energy Technology Data Exchange (ETDEWEB)

    Arai, K. (Kobe Steel Ltd., Kobe (Japan)); Naka, R. (Hitachi Ltd., Tokyo (Japan))

    1993-07-01

    Concerning debromination to be used for the filter of deodorizing device, those of long life and high deodorizing performance are demanded a great deal. As one of this kind of debromination, a deodorant ceramic catalyst (mangantid) has been developed and put for practical use as deodorant for refrigerator. In this article, the information and knowledge obtained by the development of mangantid, the features as well as several properties of the product are stated. The deodorizing methods currently used practically are roughly divided into 6 kinds such as the adsorption method, the direct combustion method, the catalytic method and the oxidation method, but each of them has its own merit and demerit, hence it is necessary to select the method in accordance with the kind of odor and its generating condition. Mangantid is a compound body of high deodorant material in a honeycomb configuration, and has the features that in comparison with the existing deordorants, its pressure loss is smaller, its deodorizing rate is bigger, and acidic, neutral and basic gaseous components can be removed in a well-balanced manner. Deodorization with mangantid has the mechanism to let the odorous component contact and react with the catalyst and change the component to the non-odorous component in the temperature range from room temperature to the low temperature region. 5 refs., 11 figs., 1 tab.

  14. Laser Sintered Calcium Phosphate Bone

    National Research Council Canada - National Science Library

    Vail, Neil

    1999-01-01

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

  15. Glass ceramic approaches for energy storage materials

    Science.gov (United States)

    Davis, Calvin Goodwin, III

    Glass ceramics are an advanced material class that exhibit excellent potential for energy storage applications. Unique properties can be obtained through the controlled crystallization that is used to form these glassy and crystalline composite materials from an amorphous bulk. By exploiting this synthesis route, materials can be optimized to offer the best balance between the crystalline ceramic phase, and the amorphous glass phase. The topic of this dissertation focuses on the structure-property relationships for glass ceramic systems for energy storage applications. Specifically, a lithium aluminum titanium phosphate system, and a barium sodium niobate system were explored for battery and capacitor applications, respectively. Li1+xAlxTi2-x(PO4)3 (LATP) is a lithium ion conductor which has shown potential for use in current and future battery technology. In its glass ceramic form the material has a conductivity of approximately 10-4 S/cm, which makes it an excellent conductor compared to other solid state lithium ion conductors. This conductivity is still lower than ionic liquids and polymers with currently used as electrolytes with conductivity higher than 10-3 S/cm. In exploring synthesis routes, it was found that microwave hybrid heating offered improve conductivity, as opposed to conventional crystallization methods. The role of microstructure and the crystallization kinetics on the overall have been investigated. It was shown that commonly used Johnson-Mehl-Avrami equation could not accurately describe the kinetics of LATP's nucleation and growth. An empirical Sestak-Berggren model was used in combination with differential scanning calorimetry data to model the kinetics of LATP. Glass ceramic systems based on a NaBa2Nb5O 15 (BNN) crystalline have shown potential as dielectrics in high energy density capacitors. Here microwave hybrid heating and conventional heating were used to crystallize BNN glass ceramics in the range of 750°C - 1000°C, and the results

  16. Influence of contamination on bonding to zirconia ceramic.

    Science.gov (United States)

    Yang, Bin; Scharnberg, Michael; Wolfart, Stefan; Quaas, Anne C; Ludwig, Klaus; Adelung, Rainer; Kern, Matthias

    2007-05-01

    The purpose of this study was to investigate the influences of contaminations and cleaning methods on bonding to dental zirconia ceramic. After saliva immersion and using silicone disclosing agent, airborne-particle abraded ceramic specimens were cleaned with isopropanol (AL), acetone (AC), 37% phosphoric acid (PA), additional airborne-particle abrasion (AA), or only with water rinsing (SS). Airborne-particle abraded specimens without contaminations (CL) were used as control group. For chemical analysis specimens of all groups were examined with X-ray photoelectron spectroscopy (XPS). Plexiglas tubes filled with composite resin were bonded to ceramic specimens using a phosphate-monomer containing composite luting resin. After 3-day water storage, tensile bond strengths (TBS) were tested. XPS analysis of group SS showed the presence of saliva and silicone (Si) contamination on the surface. The ratios of carbon/zirconium and oxygen/zirconium for groups PA and AA were comparable to those ratios obtained for group CL, indicating the removal of the organic saliva contamination. Airborne-particle abrasion and acetone completely removed Si contamination from ceramic surfaces. Isopropanol had little cleaning effect on the two contaminants. TBS (median +/- standard deviation) in MPa of the groups SS (11.6 +/- 3.1), AL (10.0 +/- 2.9), and AC (13.0 +/- 2.8) were statistically lower than those of groups PA (33.6 +/- 5.5), AA (40.1 +/- 3.6), and CL (47.0 +/- 8.1) (p 0.5). Contamination significantly reduced bond strengths to zirconia ceramic. Airborne-particle abrasion was the most effective cleaning method.

  17. Science and Technology of Ceramics

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 12. Science and Technology of Ceramics - Functional Ceramics. Sheela K Ramasesha. Series Article Volume 4 Issue 12 December 1999 pp 21-30. Fulltext. Click here to view fulltext PDF. Permanent link:

  18. Science and Technology of Ceramics

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 8. Science and Technology of Ceramics - Traditional Ceramics. Sheela K Ramasesha. Series Article Volume 4 Issue 8 August 1999 pp 16-24. Fulltext. Click here to view fulltext PDF. Permanent link:

  19. Ceramics in nuclear waste management

    Energy Technology Data Exchange (ETDEWEB)

    Chikalla, T D; Mendel, J E [eds.

    1979-05-01

    Seventy-three papers are included, arranged under the following section headings: national programs for the disposal of radioactive wastes, waste from stability and characterization, glass processing, ceramic processing, ceramic and glass processing, leaching of waste materials, properties of nuclear waste forms, and immobilization of special radioactive wastes. Separate abstracts were prepared for all the papers. (DLC)

  20. Micromolding for ceramic microneedle arrays

    NARCIS (Netherlands)

    van Nieuwkasteele-Bystrova, Svetlana Nikolajevna; Lüttge, Regina

    2011-01-01

    The fabrication process of ceramic microneedle arrays (MNAs) is presented. This includes the manufacturing of an SU-8/Si-master, its double replication resulting in a PDMS mold for production by micromolding and ceramic sintering. The robustness of the replicated structures was tested by means of

  1. Improved Tensile Test for Ceramics

    Science.gov (United States)

    Osiecki, R. A.

    1982-01-01

    For almost-nondestructive tensile testing of ceramics, steel rod is bonded to sample of ceramic. Assembly is then pulled apart in conventional tensile-test machine. Test destroys only shallow surface layer which can be machined away making specimen ready for other uses. Method should be useful as manufacturing inspection procedure for low-strength brittle materials.

  2. Phosphate Recovery From Sewage Sludge Containing Iron Phosphate

    NARCIS (Netherlands)

    Wilfert, P.K.

    2018-01-01

    The scope of this thesis was to lay the basis for a phosphate recovery technology that can be applied on sewage sludge containing iron phosphate. Such a technology should come with minimal changes to the existing sludge treatment configuration while keeping the use of chemicals or energy as small as

  3. The Use of Rock Phosphate and Phosphate Solubilising Fungi ...

    African Journals Online (AJOL)

    User

    Department of Soil Science, University of Ghana, Legon. *Corresponding author; Email: sbrempong@yahoo.com. Abstract. Field experiment was conducted to study the effect of rock phosphate (RP) and phosphate solubilizing fungi application on upland rice yield intercropped with pigeon pea from 2009 to 2011 at the ...

  4. 21 CFR 137.175 - Phosphated flour.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Phosphated flour. 137.175 Section 137.175 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Related Products § 137.175 Phosphated flour. Phosphated flour, phosphated white flour, and phosphated...

  5. Micro-Raman spectroscopy studies of the phase separation mechanisms of transition-metal phosphate glasses

    International Nuclear Information System (INIS)

    Mazali, Italo Odone; Alves, Oswaldo Luiz; Gimenez, Iara de Fatima

    2009-01-01

    Glass-ceramics are prepared by controlled separation of crystal phases in glasses, leading to uniform and dense grain structures. On the other hand, chemical leaching of soluble crystal phases yields porous glass-ceramics with important applications. Here, glass/ceramic interfaces of niobo-, vanado- and titano-phosphate glasses were studied by micro-Raman spectroscopy, whose spatial resolution revealed the multiphase structures. Phase-separation mechanisms were also determined by this technique, revealing that interface composition remained unchanged as the crystallization front advanced for niobo- and vanadophosphate glasses (interface-controlled crystallization). For titanophosphate glasses, phase composition changed continuously with time up to the equilibrium composition, indicating a spinodal-type phase separation. (author)

  6. Modelling structure and properties of amorphous silicon boron nitride ceramics

    Directory of Open Access Journals (Sweden)

    Johann Christian Schön

    2011-06-01

    Full Text Available Silicon boron nitride is the parent compound of a new class of high-temperature stable amorphous ceramics constituted of silicon, boron, nitrogen, and carbon, featuring a set of properties that is without precedent, and represents a prototypical random network based on chemical bonds of predominantly covalent character. In contrast to many other amorphous materials of technological interest, a-Si3B3N7 is not produced via glass formation, i.e. by quenching from a melt, the reason being that the binary components, BN and Si3N4, melt incongruently under standard conditions. Neither has it been possible to employ sintering of μm-size powders consisting of binary nitrides BN and Si3N4. Instead, one employs the so-called sol-gel route starting from single component precursors such as TADB ((SiCl3NH(BCl2. In order to determine the atomic structure of this material, it has proven necessary to simulate the actual synthesis route.Many of the exciting properties of these ceramics are closely connected to the details of their amorphous structure. To clarify this structure, it is necessary to employ not only experimental probes on many length scales (X-ray, neutron- and electron scattering; complex NMR experiments; IR- and Raman scattering, but also theoretical approaches. These address the actual synthesis route to a-Si3B3N7, the structural properties, the elastic and vibrational properties, aging and coarsening behaviour, thermal conductivity and the metastable phase diagram both for a-Si3B3N7 and possible silicon boron nitride phases with compositions different from Si3N4: BN = 1 : 3. Here, we present a short comprehensive overview over the insights gained using molecular dynamics and Monte Carlo simulations to explore the energy landscape of a-Si3B3N7, model the actual synthesis route and compute static and transport properties of a-Si3BN7.

  7. Low thermal expansion glass ceramics

    CERN Document Server

    1995-01-01

    This book is one of a series reporting on international research and development activities conducted by the Schott group of companies With the series, Schott aims to provide an overview of its activities for scientists, engineers, and managers from all branches of industry worldwide where glasses and glass ceramics are of interest Each volume begins with a chapter providing a general idea of the current problems, results, and trends relating to the subjects treated This volume describes the fundamental principles, the manufacturing process, and applications of low thermal expansion glass ceramics The composition, structure, and stability of polycrystalline materials having a low thermal expansion are described, and it is shown how low thermal expansion glass ceramics can be manufactured from appropriately chosen glass compositions Examples illustrate the formation of this type of glass ceramic by utilizing normal production processes together with controlled crystallization Thus glass ceramics with thermal c...

  8. Zirconia based ceramics

    International Nuclear Information System (INIS)

    Bressiani, J.C.; Bressiani, A.H.A.

    1989-05-01

    Within the new generation of ceramic materials, zirconia continues to attract ever increasing attention of scients, technologists and users by virtue of its singular combination of properties and being able to perform thermo-mechanical, electroeletronic, chemico-biological functions. Nevertheless, in order to obtain these properties, a through understanding of the phase transformation mechanisms and microstructural changes is necessary. This paper discusses the main parameters that require control during fabrication of these materials to obtain desired properties for a specific application. (author) [pt

  9. Transformation Toughening of Ceramics

    Science.gov (United States)

    1992-03-01

    irilugal Coimoi’datiio of Ai:0, and Al.O,/ZrO1 Compositte Slurries vit December 1991 Enhanced Fracture Toughness in Layered Microcomposites of Ce-ZrOz and...34 Nature (London), 258, 703-705 (1975). 2. K.E. Tsukuma and M. Shimada, *Strength, Fracture Toughness, and Vickers Hardness of CeO2 -Stabilized Tetragonal...Transformation Plasticity of CeO2 -stabllized Tetragonal Zirconia Polycrystals and I Stress Assistance and Autocatalysis," 3. Am. Ceram. Soc. 72(5] 343-53

  10. Zirconia based ceramics

    International Nuclear Information System (INIS)

    Bressiani, J.C.; Bressiani, A.H.A.

    1988-01-01

    Within the new generation of ceramic materials, zirconia continues to attract ever increasing attention of scientists, technologists and users by virtue of its singular combination of properties and being able to perform thermo-mechanical, electro-electronic, chemico-biological functions. Nevertheless, in order to obtain these properties, a through understanding of the phase transformation mechanisms and microstructural changes is necessary. This paper discusses the main parameters that require control during fabrication of these materials to obtain desired properties for a specific application. (author) [pt

  11. Indentation Damage in Ceramics.

    Science.gov (United States)

    1987-05-30

    resistance have finer grain sizes (cf. A999 and Vistal ). Most interesting, however, is the quantitative correlation between grinding resistance and...a 0.1 3 4.3 2.2 Vistal I a 0.1 20 4.1 1.7 Vistal 1, a 0.1 40 4.6 1.5 Glass-ceramic Pyroceram c - 1.5 2.3 2.0 Macor C _ 13 2.3 1.0 a. Coors Porcelain

  12. Tribology of Ceramics

    Science.gov (United States)

    1988-01-01

    techniques that do not require a vacuum (e.g., optical techniques such as FTIR , Raman, etc.). a Explore methods such as the use of a small spot...not require a vacuum (e.g., optical techniques such as FTIR , Raman, etc.). 0 Explore methods such as the use of a small spot ESCA device with an... inden - tation of ceramics. J. Mat. Sci., Vol. 16, pp. 1177-1182. Oh, H. L., and I. Finnie. 1966. An analysis of rock drilling by erosion. Proc. 1st Cong

  13. Study on the performance of ceramic composite projectile penetrating into ceramic composite target

    Directory of Open Access Journals (Sweden)

    Rong-cheng Yi

    2017-08-01

    Full Text Available In order to study the performance of ceramic composite projectile penetrating into ceramic composite target, the contrast test and numerical simulations of the penetration of standard projectile and the ceramic composite projectile into a ceramic composite target were conducted. The results show that the penetration performance of ceramic composite projectile is obvious superior to that of standard projectile for ceramic composite target. The ceramic nose of ceramic composite projectile fully destroys the ceramic panels anterior to its following armor-piercing projectile body, thus maintaining the penetration ability of the following armor-piercing projectile body.

  14. Method of forming a ceramic matrix composite and a ceramic matrix component

    Science.gov (United States)

    de Diego, Peter; Zhang, James

    2017-05-30

    A method of forming a ceramic matrix composite component includes providing a formed ceramic member having a cavity, filling at least a portion of the cavity with a ceramic foam. The ceramic foam is deposited on a barrier layer covering at least one internal passage of the cavity. The method includes processing the formed ceramic member and ceramic foam to obtain a ceramic matrix composite component. Also provided is a method of forming a ceramic matrix composite blade and a ceramic matrix composite component.

  15. Evaluation of the capacity of mosaic-like porous ceramics with designed pores to support osteoconduction.

    Science.gov (United States)

    Teraoka, Kay; Kato, Tomotaka; Hattori, Koji; Ohgushi, Hajime

    2013-12-01

    Under osteoconductive conditions, porous calcium phosphate ceramics are known to induce new bone formation within their pores. A critical aspect of the design of porous ceramics is the geometrical features of their pores, with regard to promoting bone formation and mass transfer management in pore networks. However, the pore geometries of common porous ceramics lack clear details. Further, the connections between pores are hard to characterize and thus have not been thoroughly researched. To address these issues, we have developed an original method for fabricating porous ceramics, which we have termed "mosaic-like ceramics fabrication (MLCF)." Using MLCF, pore geometries can be designed and fabricated by each unit, and a network covering all the pores can be fabricated. Furthermore, MLCF can be used to build porous ceramics with custom-made shapes. In this study, we assessed the osteogenic influences of MLCF products (MLPC) composed of hydroxyapatite units on the differentiation of rat bone-marrow-derived mesenchymal stem cells (MSCs) in vitro and in vivo. Two types of commercial porous artificial bone were used as positive controls. MLPC was superior in osteogenic potential, and proved to be a reliable scaffold for bone tissue engineering. Furthermore, this study succeeded in defining the important geometries for osteoconduction. Copyright © 2013 Wiley Periodicals, Inc.

  16. Nano-ceramics and its molding technologies

    International Nuclear Information System (INIS)

    Liu Jian; Xu Yunshu

    2007-01-01

    Nano-ceramics and its related knowledge were introduced. Fabrication of nano-ceramic powder, as well as the molding and sintering technologies of nano-ceramics were reviewed. Features of the present molding technologies were analyzed. The applications of nano-ceramics were prospected. (authors)

  17. Preparation of 147Pm ceramic source core

    International Nuclear Information System (INIS)

    Mielcarski, M.

    1989-01-01

    Preparation of ceramic pellets containing fixed promethium-147 is described. Incorporation rate of 147 Pm into the ceramic material was determined. The leachability and vaporization of promethium from the obtained ceramics was investigated. The ceramic pellets prepared by the described procedure, mounted in special holders, can be applied as point sources in beta backscatter thickness gauges. (author)

  18. Ceramic fiber reinforced filter

    Science.gov (United States)

    Stinton, David P.; McLaughlin, Jerry C.; Lowden, Richard A.

    1991-01-01

    A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

  19. Ceramics and magnetohydrodynamics

    International Nuclear Information System (INIS)

    Yvars, M.

    1982-01-01

    The principle of MHD conversion using ionized gases is briefly recalled. The enthalpy and temperature of the gas at the outlet of the MHD nozzle are still very high, so it is therefore essential to use this heat with care, by associating the MHD generator with a conventional steam or gas thermal unit (''head cycle''). The block diagrams of the open or closed cycles are particularly examined. The main difficulties of the MHD cycles are summed up. Closer interest is given to those relating to the alkaline seed cycle before moving on to the technology of the high temperature exchanger and the MHD nozzle. The use of MHD at the industrial stage is confronted with the problem of developing ceramics that operate at high temperatures, with significant thermal gradients. The ceramics for insulating walls, for conducting electrodes and those used for thermal exchangers are examined in turn. The article ends with a brief review of the progress of MHD work in the world [fr

  20. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2003-01-01

    In the present quarter, the possibility of using a more complex interfacial engineering approach to the development of reliable and stable oxygen transport perovskite ceramic membranes/metal seals is discussed. Experiments are presented and ceramic/metal interactions are characterized. Crack growth and fracture toughness of the membrane in the reducing conditions are also discussed. Future work regarding this approach is proposed are evaluated for strength and fracture in oxygen gradient conditions. Oxygen gradients are created in tubular membranes by insulating the inner surface from the reducing environment by platinum foils. Fracture in these test conditions is observed to have a gradient in trans and inter-granular fracture as opposed to pure trans-granular fracture observed in homogeneous conditions. Fracture gradients are reasoned to be due to oxygen gradient set up in the membrane, variation in stoichiometry across the thickness and due to varying decomposition of the parent perovskite. The studies are useful in predicting fracture criterion in actual reactor conditions and in understanding the initial evolution of fracture processes.

  1. Phosphate glasses, containing nitrogen

    International Nuclear Information System (INIS)

    Lisitsyna, E.A.; Khalilev, V.D.; Koryavin, A.A.; Goncharova, L.N.

    1987-01-01

    Possibilities of nitrogen-containing glass synthesis by the introduction into the charge of ammonium salts, as well as aluminium nitride, are studied. Zinc alumoyttrium phosphate glass (mol. %) Zn(PO 3 ) 2 - 4O, Al(PO 3 ) 3 - 3O, Y(PO 3 ) 3 -3O is suggested as a matrix. It is shown that the effect of amide and imide groups on the properties of the glass is less noticeable than the effect of nitride groups. Direct introduction of nitride constituent was realized using AlN, but aluminium introduction was taken into account so that the oxide was subtracted. The attempt to introduce more than 2.5 mass % of nitrogen into initial matrix by aluminium nitride has failed due to repeated restoration of glass with amorphous phosphorus isolation

  2. Copper scandium zirconium phosphate

    DEFF Research Database (Denmark)

    Bond, Andrew David; Warner, Terence Edwin

    2013-01-01

    The title compound, with nominal formula Cu(2)ScZr(PO(4))(3), has a beige coloration and displays fast Cu(+) cation conduction at elevated temperatures. It adopts a NASICON-type structure in the space group R3c. The examined crystal was an obverse-reverse twin with approximately equal twin...... components. The [Sc(III)Zr(IV)(PO(4))(3)](2-) framework is composed of corner-sharing Sc/ZrO(6) octahedra and PO(4) tetrahedra. The Sc and Zr atoms are disordered on one atomic site on a crystallographic threefold axis. The P atom of the phosphate group lies on a crystallographic twofold axis. Nonframework...... Cu(+) cations occupy three positions. Two of the Cu(+) positions generate an approximately circular distribution around a site of 3 symmetry, referred to as the M1 site in the NASICON-type structure. The other Cu(+) position is situated close to the twofold symmetric M2 site, displaced...

  3. Correlation between ceramics translucency and polymerization efficiency through ceramics.

    Science.gov (United States)

    Ilie, Nicoleta; Hickel, Reinhard

    2008-07-01

    The aim of this study was to analyse the effects of curing with a high intensity curing unit for different exposure times, for different ceramic types, thicknesses and corresponding different ceramic translucencies. The relationship between ceramic translucency and hardness, as well as the critical translucency value for sufficient curing were also determined. All these effects were expressed in terms of Vickers hardness measured with an automatic micro hardness indenter on thin luting composite films (Variolink II), stored for 24h in distilled water at 37 degrees C. Two preliminary studies determined the time necessary to achieve maximum hardness in the luting composite, with and without an additional chemical catalyst. The main study aimed to estimate the effect on luting composite hardness, without an additional chemical catalyst, of the following parameters: curing time (5, 10 and 15s), ceramic thickness (0.5, 1, 2 and 3mm), ceramic type (two leucite-reinforced and two lithium disilicate glass-ceramics) and ceramic translucency (TP), measured using a reflection spectrophotometer as a function of wavelength. The minimum curing time necessary to achieve maximum hardness in the luting composite was 15s for both groups, with and without an additional chemical catalyst. However, dual curing caused a hardness enhancement of ca. 50%. The two leucite-reinforced glass-ceramics did not reduced the hardness of the luting composite up to a ceramic thickness of 2mm, whereas the more dense lithium disilicate glass-ceramics had already caused this effect at a thickness of 1mm. ANOVA analyses revealed that the greatest effect on the luting composite hardness resulted from the curing time (eta square=0.62) followed by translucency (eta square=0.32 TP650 nm and 0.28 for TP470 nm), ceramic type (eta square=0.17) and ceramic thickness (eta square=0.03). High-power curing units are not able to consistently reduce the exposure time. In both systems, at least 15s were necessary to

  4. High density, low open porosity magnesia ceramics

    International Nuclear Information System (INIS)

    Alecu, I.D.; Stead, R.J.

    1998-01-01

    Many modern high-tech applications require magnesia ceramic components with high bulk densities and very low apparent porosities. Quite commonly, bulk densities above 3500 kg.m -3 and open porosities close to zero are specified for such applications of magnesia ceramics. The paper presents the recent achievements of Rojan Advanced Ceramics in the field of high density, very low open porosity magnesia ceramic materials and special products, including labware and planar components. Copyright (1998) Australasian Ceramic Society

  5. Development of low-expansion ceramics with strength retention to elevated temperatures. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hirschfeld, D.A.; Brown, J.J. Jr. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)

    1994-09-01

    The development of advanced engines has resulted in the need for new ceramic compositions which exhibit thermo-mechanical properties suitable for the engine environment, e.g., low thermal expansion, stability to 1,200 C, and thermal shock resistance. To meet these goals, a two phase research program was instituted. In the first phase, new oxide ceramics were identified in the AlPO{sub 4}-{beta}-eucryptite, {beta}-cristobalite, mullite and zircon systems. This research focused on screening and property characterization of ceramics in the four systems. The most promising compositions in the AlPO{sub 4}-{beta}-eucryptite and zircon systems were then further evaluated and developed in the second phase with the goal of being ready for prototype testing in actual engines. Of the compositions, calcium magnesium zirconium phosphate (zircon system) exhibits the most desirable properties and is presently being developed for commercialization.

  6. Bone bonding ability of some borate bio-glasses and their corresponding glass-ceramic derivatives

    Directory of Open Access Journals (Sweden)

    Fatma H. Margha

    2012-12-01

    Full Text Available Ternary borate glasses from the system Na2O·CaO·B2O3 together with soda-lime-borate samples containing 5 wt.% of MgO, Al2O3, SiO2 or P2O5 were prepared. The obtained glasses were converted to their glass-ceramic derivatives by controlled heat treatment. X-ray diffraction was employed to investigate the separated crystalline phases in glass-ceramics after heat treatment of the glassy samples. The glasses and corresponding glass-ceramics after immersion in water or diluted phosphate solution for extended times were characterized by the grain method (adopted by several authors and recommended by ASTM and Fourier-transform infrared spectra to justify the formation of hydroxyapatite as an indication of the bone bonding ability. The influence of glass composition on bioactivity potential was discussed too.

  7. Radiation-disorder and aperiodicity in irradiated ceramics

    International Nuclear Information System (INIS)

    Hobbs, L.W.

    1992-01-01

    This final technical report documents the accomplishments of the program of research entitled ''Radiation Disorder and Aperiodicity in Irradiated Ceramics'' for the period June 22, 1989--June 21, 1992. This research forms the latest part on an on-going program, begun at MIT in 1983 under DOE support, which has had as its objectives investigation of the responses in radiation environments of ceramics heavily-irradiated with electrons, neutrons and ions, with potential applications to fusion energy technology and high-level nuclear waste storage. Materials investigated have included SiO 2 , MgAl 2 O 4 , Al 23 O 27 N 5 , SiC, BeO, LiAlO 2 , Li 2 ZrO 3 , CaTiO 3 KTaO 3 and Ca(Zr, Pu)Ti 2 O 7 . The program initially proposed for 1989 had as its major objectives two main thrusts: (1) research on defect aggregation in irradiated non-oxide ceramics, and (2) research on irradiation-induced amorphization of network silicas and phosphates

  8. Gel adsorption processing for waste solidification in NZP ceramics

    International Nuclear Information System (INIS)

    Yang, L.J.; Komareni, S.; Roy, R.

    1984-01-01

    Simulated PW-4b waste solution along with Na additive was mixed with Zr-P-O gel, dried and then fired to form the desired sodium zirconium phosphate, NaZr 2 (PO 4 ) 3 [NZP] ceramic. NZP and monazite were the only phases produced upon firing at 900 0 C with 10 to 40% of PW-4b mixed with the gel. CsZr 2 (PO 4 ) 3 which is isostructural with NZP was also identified when fired under reducing conditions. The -200 mesh powders of these waste forms prepared under reducing conditions showed excellent leach resistance under hydro-thermal conditions. Alternatively, PW-4b and Three Mile Island (TMI) wastes were adsorbed on Zr-P-O gel in a column. The gel was dried, pelletized and fired to form the desired [NZP] ceramic. Cesium was found to be selective on the Zr-P-O gel because no breakthrough of Cs was detected up to 38 column volumes of TMI waste. Thus, it is possible to use a tailored gel to sorb Cs and/or Sr from accident waste water and then fire the bed to form the [NZP] ceramic below 1000 0 C. The main advantages of the gel adsorption process are its simplicity and its enormous compositional flexibility. 12 references, 2 figures, 4 tables

  9. A high performance ceramic-polymer separator for lithium batteries

    Science.gov (United States)

    Kumar, Jitendra; Kichambare, Padmakar; Rai, Amarendra K.; Bhattacharya, Rabi; Rodrigues, Stanley; Subramanyam, Guru

    2016-01-01

    A three-layered (ceramic-polymer-ceramic) hybrid separator was prepared by coating ceramic electrolyte [lithium aluminum germanium phosphate (LAGP)] over both sides of polyethylene (PE) polymer membrane using electron beam physical vapor deposition (EB-PVD) technique. Ionic conductivities of membranes were evaluated after soaking PE and LAGP/PE/LAGP membranes in a 1 Molar (1M) lithium hexafluroarsenate (LiAsF6) electrolyte in ethylene carbonate (EC), dimethyl carbonate (DMC) and ethylmethyl carbonate (EMC) in volume ratio (1:1:1). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were employed to evaluate morphology and structure of the separators before and after cycling performance tests to better understand structure-property correlation. As compared to regular PE separator, LAGP/PE/LAGP hybrid separator showed: (i) higher liquid electrolyte uptake, (ii) higher ionic conductivity, (iii) lower interfacial resistance with lithium and (iv) lower cell voltage polarization during lithium cycling at high current density of 1.3 mA cm-2 at room temperature. The enhanced performance is attributed to higher liquid uptake, LAGP-assisted faster ion conduction and dendrite prevention. Optimization of density and thickness of LAGP layer on PE or other membranes through manipulation of PVD deposition parameters will enable practical applications of this novel hybrid separator in rechargeable lithium batteries with high energy, high power, longer cycle life, and higher safety level.

  10. Hardness of ion implanted ceramics

    International Nuclear Information System (INIS)

    Oliver, W.C.; McHargue, C.J.; Farlow, G.C.; White, C.W.

    1985-01-01

    It has been established that the wear behavior of ceramic materials can be modified through ion implantation. Studies have been done to characterize the effect of implantation on the structure and composition of ceramic surfaces. To understand how these changes affect the wear properties of the ceramic, other mechanical properties must be measured. To accomplish this, a commercially available ultra low load hardness tester has been used to characterize Al 2 O 3 with different implanted species and doses. The hardness of the base material is compared with the highly damaged crystalline state as well as the amorphous material

  11. Ceramics for Turbine Engine Applications.

    Science.gov (United States)

    1980-03-01

    DEVELOPMENT OF CERAMIC NOZZLE SECTION FOR SMIALL RADIAL GAS TURBINE by J.C.Napier and J.P. Arnold 12 DEVELOPMENT OF A CERAMIC TURBINE NOZZLE RING by H.Burfeindt...this way, for instance, a Daimler engine was in 1911 awarded the prize of the "Automobiltechnische Gesell - schaft". In 1912, a Benz engine won the...blade development Turtle U~nion RB 199 v)ln BENEFITS OF CERAMICS TO GAS TURBINES by Arnold Brooks and Albert I. Bellin Aircraft Engine Group General

  12. Porous ceramics out of oxides

    International Nuclear Information System (INIS)

    Bakunov, V.S.; Balkevich, V.L.; Vlasov, A.S.; Guzman, I.Ya.; Lukin, E.S.; Poluboyarinov, D.N.; Poliskij, R.Ya.

    1977-01-01

    A review is made of manufacturing procedures and properties of oxide ceramics intended for high-temperature thermal insulation and thermal protection applications. Presented are structural characteristics of porous oxide refractories and their properties. Strength and thermal conductivity was shown to depend upon porosity. Described is a procedure for manufacturing porous ceramic materials from aluminium oxide, zirconium dioxide, magnesium oxide, beryllium oxide. The thermal resistance of porous ceramics from BeO is considerably greater than that of other high-refractoriness oxides. Listed are areas of application for porous materials based on oxides

  13. Ceramic drug-delivery devices.

    Science.gov (United States)

    Lasserre, A; Bajpai, P K

    1998-01-01

    A variety of ceramics and delivery systems have been used to deliver chemicals, biologicals, and drugs at various rates for desired periods of time from different sites of implantation. In vitro and in vivo studies have shown that ceramics can successfully be used as drug-delivery devices. Matrices, inserts, reservoirs, cements, and particles have been used to deliver a large variety of therapeutic agents such as antibiotics, anticancer drugs, anticoagulants, analgesics, growth factors, hormones, steroids, and vaccines. In this article, the advantages and disadvantages of conventional drug-delivery systems and the different approaches used to deliver chemical and biological agents by means of ceramic systems will be reviewed.

  14. Electrochemical Reduction of Zinc Phosphate

    International Nuclear Information System (INIS)

    Kim, Chang Hwan; Lee, Jung Hyun; Shin, Woon Sup

    2010-01-01

    We demonstrated first that the electrochemical reduction of zinc phosphate in neutral phosphate buffer is possible and potentially applicable to bio-compatible rechargeable battery. The actual redox component is Zn(s)/Zn phosphate(s) and the future research about the control of crystal formation for the better cyclability is required. In lead-acid battery, the electrochemical redox reaction of Pb (s) /PbSO 4(s) is used by reducing Pb(II) and oxidizing Pb(0) in sulfate rich solution. Since both reduced form and oxidized form are insoluble, they cannot diffuse to the opposite electrodes and react. It is a very common strategy to make a stable battery electrode that a metal element is reduced and oxidized in solution containing an abundance of anion readily precipitating with the metal ion. For the application of this strategy to construction of rechargeable battery using bio-compatible electrode materials and electrolytes, the use of phosphate ion can be considered as anion readily precipitating with metal ions. If phosphate buffer with neutral pH is used as electrolyte, the better bio-compatibility will be achieved than most of rechargeable battery using strong acid, strong base or organic solvent as electrolyte solution. There are many metal ions readily precipitating with phos-phate ion, and zinc is one of them

  15. Dynamic crack arrest in ceramics and ceramic composites

    Science.gov (United States)

    Kobayashi, A. S.; Yang, K. H.

    1989-01-01

    The results of past dynamic crack arrest experiments involving structural ceramics and ceramic composites are reviewed and analyzed. The lack of dynamic crack arrest in very brittle materials is discussed and contrasted with dynamic crack arrest in somewhat brittle metallic and polymeric materials. Numerical analyses show that the lack of crack arrest is due to reduced dynamic fracture resistance of the material and is not due to the kinetic energy.

  16. Primary retention following nuclear recoil in β-decay: Proposed synthesis of a metastable rare gas oxide ((38)ArO4) from ((38)ClO4(-)) and the evolution of chemical bonding over the nuclear transmutation reaction path.

    Science.gov (United States)

    Timm, Matthew J; Matta, Chérif F

    2014-12-01

    Argon tetroxide (ArO4) is the last member of the N=50 e(-) isoelectronic and isosteric series of ions: SiO4(4-), PO4(3-), SO4(2-), and ClO4(-). A high level computational study demonstrated that while ArO4 is kinetically stable it has a considerable positive enthalpy of formation (of ~298kcal/mol) (Lindh et al., 1999. J. Phys. Chem. A 103, pp. 8295-8302) confirming earlier predictions by Pyykkö (1990. Phys. Scr. 33, pp. 52-53). ArO4 can be expected to be difficult to synthesize by traditional chemistry due to its metastability and has not yet been synthesized at the time of writing. A computational investigation of the changes in the chemical bonding of chlorate (ClO4(-)) when the central chlorine atom undergoes a nuclear transmutation from the unstable artificial chlorine isotope (38)Cl to the stable rare argon isotope (38)Ar through β-decay, hence potentially leading to the formation of ArO4, is reported. A mathematical model is presented that allows for the prediction of yields following the recoil of a nucleus upon ejecting a β-electron. It is demonstrated that below a critical angle between the ejected β-electron and that of the accompanying antineutrino their respective linear momentums can cancel to such an extent as imparting a recoil to the daughter atom insufficient for breaking the Ar-O bond. As a result, a primary retention yield of ~1% of ArO4 is predicted following the nuclear disintegration. The study is conducted at the quadratic configuration interaction with single and double excitations [QCISD/6-311+G(3df)] level of theory followed by an analysis of the electron density by the quantum theory of atoms in molecules (QTAIM). Crossed potential energy surfaces (PES) were used to construct a PES from the metastable ArO4 ground singlet state to the Ar-O bond dissociation product ArO3+O((3)P) from which the predicted barrier to dissociation is ca. 22kcal/mol and the exothermic reaction energy is ca. 28kcal/mol [(U)MP2/6-311+G(d)]. Copyright © 2014

  17. Simple additive manufacturing of an osteoconductive ceramic using suspension melt extrusion.

    Science.gov (United States)

    Slots, Casper; Jensen, Martin Bonde; Ditzel, Nicholas; Hedegaard, Martin A B; Borg, Søren Wiatr; Albrektsen, Ole; Thygesen, Torben; Kassem, Moustapha; Andersen, Morten Østergaard

    2017-02-01

    Craniofacial bone trauma is a leading reason for surgery at most hospitals. Large pieces of destroyed or resected bone are often replaced with non-resorbable and stock implants, and these are associated with a variety of problems. This paper explores the use of a novel fatty acid/calcium phosphate suspension melt for simple additive manufacturing of ceramic tricalcium phosphate implants. A wide variety of non-aqueous liquids were tested to determine the formulation of a storable 3D printable tricalcium phosphate suspension ink, and only fatty acid-based inks were found to work. A heated stearic acid-tricalcium phosphate suspension melt was then 3D printed, carbonized and sintered, yielding implants with controllable macroporosities. Their microstructure, compressive strength and chemical purity were analyzed with electron microscopy, mechanical testing and Raman spectroscopy, respectively. Mesenchymal stem cell culture was used to assess their osteoconductivity as defined by collagen deposition, alkaline phosphatase secretion and de-novo mineralization. After a rapid sintering process, the implants retained their pre-sintering shape with open pores. They possessed clinically relevant mechanical strength and were chemically pure. They supported adhesion of mesenchymal stem cells, and these were able to deposit collagen onto the implants, secrete alkaline phosphatase and further mineralize the ceramic. The tricalcium phosphate/fatty acid ink described here and its 3D printing may be sufficiently simple and effective to enable rapid, on-demand and in-hospital fabrication of individualized ceramic implants that allow clinicians to use them for treatment of bone trauma. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Ceramics for fusion devices

    International Nuclear Information System (INIS)

    Clinard, F.W. Jr.

    1984-01-01

    Ceramics are required for a number of applications in fusion devices, among the most critical of which are magnetic coil insulators, windows for RF heating systems, and structural uses. Radiation effects dominate consideration of candidate materials, although good pre-irradiation properties are a requisite. Materials and components can be optimized by careful control of chemical and microstructural content, and application of brittle material design and testing techniques. Future directions for research and development should include further extension of the data base in the areas of electrical, structural, and thermal properties; establishment of a fission neutron/fusion neutron correlation including transmutation gas effects; and development of new materials tailored to meet the specific needs of fusion reactors

  19. Agglomeration of ceramic powders

    Science.gov (United States)

    Cawley, James D.; Larosa, Judith; Dirkse, Fredrick

    1989-01-01

    A research program directed at a critical comparison of numerical models for power agglomeration with experimental observations is currently underway. Central to this program is the quantitative characterization of the distribution of mass within an agglomerate as a function of time. Current experiments are designed to restrict agglomeration to a surface, which is oriented perpendicular to the force of gravity. These experiments are discussed with reference to: their significance to ceramic processing; artifacts which may be avoided in microgravity experiments; and the comparison of information available in real space (from optical microscopy) to that in reciprocal space (from light scattering). The principle machine requirement appears to be a need to obtain information at small scattering angles.

  20. Creep in electronic ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Routbort, J. L.; Goretta, K. C.; Arellano-Lopez, A. R.

    2000-04-27

    High-temperature creep measurements combined with microstructural investigations can be used to elucidate deformation mechanisms that can be related to the diffusion kinetics and defect chemistry of the minority species. This paper will review the theoretical basis for this correlation and illustrate it with examples from some important electronic ceramics having a perovskite structure. Recent results on BaTiO{sub 3}, (La{sub 1{minus}x}Sr){sub 1{minus}y}MnO{sub 3+{delta}}, YBa{sub 2}Cu{sub 3}O{sub x}, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x}, (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} and Sr(Fe,Co){sub 1.5}O{sub x} will be presented.

  1. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2003-01-01

    In the present quarter, experiments are presented on ceramic/metal interactions of Zirconia/Ni-B-Si system and with a thin Ti coating deposited on zirconia surface. Processing of perovskites of LSC, LSF and LSCF composition for evaluation of mechanical properties as a function of environment are begun. The studies are to be in parallel with LSFCO composition to characterize the segregation of cations and slow crack growth in environmental conditions. La{sub 1-x}Sr{sub x}FeO{sub 3-d} has also been characterized for paramagnetic ordering at room temperature and the evolution of magnetic moments as a function of temperature are investigated. Investigation on the thermodynamic properties of the membrane materials are continued to develop a complete model for the membrane transport.

  2. Recent progress in ceramic joining

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E.

    1998-09-01

    Both fundamental and practical aspects of ceramic joining are understood well enough for many, if not most, applications requiring moderate strengths at room temperature. This paper argues that the two greatest needs in ceramic joining are for techniques to join buried interfaces by selective heating, and methods for joining ceramics for use at temperatures of 800 to 1,200 C. Heating with microwave radiation or with high-energy electron beams has been used to join buried ceramic interfaces, for example SiC to SiC. Joints with varying levels of strength at temperatures of 600 to 1,000 C have been made using four techniques: (1) transient liquid phase bonding; (2) joining with refractory braze alloys; (3) joining with refractory glass compositions; and (4) joining using preceramic polymers. Joint strengths as high as 550 MPa at 1,000 C have been reported for silicon nitride-silicon nitride bonds tested in four-point flexure.

  3. Metals and Ceramics Information Center.

    Science.gov (United States)

    1981-07-01

    Specialization CURRENT AWARENESS BULLETIN (Continued) Noton, B. R. Program Manager Report on Conference Pattee , H. E. Staff Metallurgist Metals...Welding Duckworth, W. H. Staff Engineer Ceramics Pattee , H. Staff Engineer Welding HANDBOOKS /DATABOOKS Hucek, H. J. Staff Metallurgist Mechanical

  4. Moessbauer studies of Inca ceramics

    International Nuclear Information System (INIS)

    Wagner, U.; Wagner, F.E.; Marticorena, B.; Salazar, R.; Schwabe, R.; Riederer, J.

    1986-01-01

    To obtain information on the firing of Inca ceramics, 7 samples from different locations were studied by Moessbauer spectroscopy including a detailed laboratory refiring procedure. The glaze typical for the surface of this ware was studied by Moessbauer scattering. (Auth.)

  5. Inorganic glass ceramic slip rings

    Science.gov (United States)

    Glossbrenner, E. W.; Cole, S. R.

    1972-01-01

    Prototypes of slip rings have been fabricated from ceramic glass, a material which is highly resistant to deterioration due to high temperature. Slip ring assemblies were not structurally damaged by mechanical tests and performed statisfactorily for 200 hours.

  6. Geopolymers for Structural Ceramic Applications

    Science.gov (United States)

    2006-08-31

    Stow, Ohio 44224 Abstract Geopolymers , also called geo- cements and low-temperature synthesized glasses, are a class of cementious materials that do...Applications of geopolymers have included ceramic matrix composites,ŕ, 3 waste encapsulation 9-11and alternative cements .7,12,14 As adhesives...and H. Schneider, The American Ceramic Society, Westerville, OH, 2003. 3J. Bell and W. M. Kriven, "Nanoporosity in geopolymeric cements " pp. 590-591

  7. Ceramic Repair Without Hydrofluoric Acid.

    Science.gov (United States)

    Bergoli, César Dalmolin; de Carvalho, Rodrigo Furtado; Luz, Julio Nogueira; Luz, Murilo Souza; Meincke, Débora Könzgen; Saavedra, Guilherme de Siqueira Ferreira

    To evaluate the bond strength between composite resin and feldspathic ceramic following repair protocols with and without hydrofluoric acid and aging by thermocycling. Forty-eight glass feldspathic ceramic blocks (8 x 8 x 6 mm) were divided into three groups on the basis of their surface repair treatment: 1. 10% hydrofluoric acid + Signum Ceramic Primer I + Signum Ceramic Primer II (control group); 2. abrasive rubber tips + Signum Ceramic Primer I + Signum Ceramic Primer II (test group); 3. Signum Ceramic Primer I + Signum Ceramic Primer II (negative control group). The treated surface of each block was built up with composite and then sectioned to produce nontrimmed bars (adhesive area = 1 mm²). Half of the bars from each group were aged by 6000 cycles of 30-s immersions in water baths at 5°C and 55°C, with a transfer time of 2 s. The other bars were immediately subjected to microtensile bond strength testing. The mean bond strength for each block was then recorded and submitted to two-way ANOVA and Tukey's test (α = 0.05). The aging protocol influenced the bond strength values of all groups (p = 0.000). The non-aged groups submitted to surface treatment protocols 1 (13.1 ± 2.5 MPa) and 2 (11.5 ± 5.1 MPa) presented the highest bond strength values. The interface bond strength of all groups was susceptible to aging. Surface treatment protocol 2, with abrasive rubber tips and no hydrofluoric acid, appeared to be the most promising option, as the resulting bond strength values were similar to those of the control group.

  8. Extruded ceramic honeycomb and method

    Science.gov (United States)

    Day, J. Paul

    1995-04-04

    Extruded low-expansion ceramic honeycombs comprising beta-spodumene solid solution as the principal crystal phase and with less than 7 weight percent of included mullite are produced by compounding an extrusion batch comprising a lithium aluminosilicate glass powder and a clay additive, extruding a green honeycomb body from the batch, and drying and firing the green extruded cellular honeycomb to crystallize the glass and clay into a low-expansion spodumene ceramic honeycomb body.

  9. Fracture-dissociation of ceramic liner.

    Science.gov (United States)

    Hwang, Sung Kwan; Oh, Jin-Rok; Her, Man Seung; Shim, Young Jun; Cho, Tae Yeun; Kwon, Sung Min

    2008-08-01

    The use of BIOLOX delta ceramic (CeramTec AG, Plochingen, Germany) has been increasing. This ceramic prevents cracking by restraining the phase transformation due to the insertion of nano-sized, yttria-stabilized tetragonal zirconia into the alumina matrix. This restrains the progress of cracking through the formation of platelet-like crystal or whiskers due to the addition of an oxide additive. We observed a case of BIOLOX delta ceramic liner (CeramTec AG) rim fracture 4 months postoperatively. Radiographs showed that the ceramic liner was subluxated from the acetabular cup. Scratches on the acetabular cup and femoral neck were seen, and the fracture was visible on the rim of the liner. Under electron microscope, metal particle coatings from the ceramic liner were identified. The ceramic liner, fracture fragments, and adjacent tissues were removed and replaced with a ceramic liner and femoral head of the same size and design. We believe the mechanism of the fracture-dissociation of the ceramic liner in this case is similar to a case of separation of the ceramic liner from the polyethylene shell in a sandwich-type ceramic-ceramic joint. To prevent ceramic liner fracture-dissociation, the diameter of the femoral neck needs to be decreased in a new design, while the diameter of the femoral head needs to be increased to ensure an increase in range of motion.

  10. Ceramics as nuclear reactor fuels

    International Nuclear Information System (INIS)

    Reeve, K.D.

    1975-01-01

    Ceramics are widely accepted as nuclear reactor fuel materials, for both metal clad ceramic and all-ceramic fuel designs. Metal clad UO 2 is used commercially in large tonnages in five different power reactor designs. UO 2 pellets are made by familiar ceramic techniques but in a reactor they undergo complex thermal and chemical changes which must be thoroughly understood. Metal clad uranium-plutonium dioxide is used in present day fast breeder reactors, but may eventually be replaced by uranium-plutonium carbide or nitride. All-ceramic fuels, which are necessary for reactors operating above about 750 0 C, must incorporate one or more fission product retentive ceramic coatings. BeO-coated BeO matrix dispersion fuels and silicate glaze coated UO 2 -SiO 2 have been studied for specialised applications, but the only commercial high temperature fuel is based on graphite in which small fuel particles, each coated with vapour deposited carbon and silicon carbide, are dispersed. Ceramists have much to contribute to many aspects of fuel science and technology. (author)

  11. Method for Waterproofing Ceramic Materials

    Science.gov (United States)

    Cagliostro, Domenick E. (Inventor); Hsu, Ming-Ta S. (Inventor)

    1998-01-01

    Hygroscopic ceramic materials which are difficult to waterproof with a silane, substituted silane or silazane waterproofing agent, such as an alumina containing fibrous, flexible and porous, fibrous ceramic insulation used on a reentry space vehicle, are rendered easy to waterproof if the interior porous surface of the ceramic is first coated with a thin coating of silica. The silica coating is achieved by coating the interior surface of the ceramic with a silica precursor converting the precursor to silica either in-situ or by oxidative pyrolysis and then applying the waterproofing agent to the silica coated ceramic. The silica precursor comprises almost any suitable silicon containing material such as a silane, silicone, siloxane, silazane and the like applied by solution, vapor deposition and the like. If the waterproofing is removed by e.g., burning, the silica remains and the ceramic is easily rewaterproofed. An alumina containing TABI insulation which absorbs more that five times its weight of water, absorbs less than 10 wt. % water after being waterproofed according to the method of the invention.

  12. Microwave sintering of ceramic materials

    Science.gov (United States)

    Karayannis, V. G.

    2016-11-01

    In the present study, the potential of microwave irradiation as an innovative energy- efficient alternative to conventional heating technologies in ceramic manufacturing is reviewed, addressing the advantages/disadvantages, while also commenting on future applications of possible commercial interest. Ceramic materials have been extensively studied and used due to several advantages they exhibit. Sintering ceramics using microwave radiation, a novel technology widely employed in various fields, can be an efficient, economic and environmentally-friendlier approach, to improve the consolidation efficiency and reduce the processing cycle-time, in order to attain substantial energy and cost savings. Microwave sintering provides efficient internal heating, as energy is supplied directly and penetrates the material. Since energy transfer occurs at a molecular level, heat is generated throughout the material, thus avoiding significant temperature gradients between the surface and the interior, which are frequently encountered at high heating rates upon conventional sintering. Thus, rapid, volumetric and uniform heating of various raw materials and secondary resources for ceramic production is possible, with limited grain coarsening, leading to accelerated densification, and uniform and fine-grained microstructures, with enhanced mechanical performance. This is particularly important for manufacturing large-size ceramic products of quality, and also for specialty ceramic materials such as bioceramics and electroceramics. Critical parameters for the process optimization, including the electromagnetic field distribution, microwave-material interaction, heat transfer mechanisms and material transformations, should be taken into consideration.

  13. Calcium phosphates for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Canillas, M.; Pena, P.; Aza, A.H. de; Rodriguez, M.A.

    2017-07-01

    The history of calcium phosphates in the medicine field starts in 1769 when the first evidence of its existence in the bone tissue is discovered. Since then, the interest for calcium phosphates has increased among the scientific community. Their study has been developed in parallel with new advances in materials sciences, medicine or tissue engineering areas. Bone tissue engineering is the field where calcium phosphates have had a great importance. While the first bioceramics are selected according to bioinert, biocompatibility and mechanical properties with the aim to replace bone tissue damaged, calcium phosphates open the way to the bone tissue regeneration challenge. Nowadays, they are present in the majority of commercial products directed to repair or regenerate damaged bone tissue. Finally, in the last few decades, they have been suggested and studied as drug delivering devices and as vehicles of DNA and RNA for the future generation therapies. (Author)

  14. Calcium phosphates for biomedical applications

    Directory of Open Access Journals (Sweden)

    Maria Canillas

    2017-05-01

    Full Text Available The history of calcium phosphates in the medicine field starts in 1769 when the first evidence of its existence in the bone tissue is discovered. Since then, the interest for calcium phosphates has increased among the scientific community. Their study has been developed in parallel with new advances in materials sciences, medicine or tissue engineering areas. Bone tissue engineering is the field where calcium phosphates have had a great importance. While the first bioceramics are selected according to bioinert, biocompatibility and mechanical properties with the aim to replace bone tissue damaged, calcium phosphates open the way to the bone tissue regeneration challenge. Nowadays, they are present in the majority of commercial products directed to repair or regenerate damaged bone tissue. Finally, in the last few decades, they have been suggested and studied as drug delivering devices and as vehicles of DNA and RNA for the future generation therapies.

  15. Bone reaction adjacent to microplasma-sprayed calcium phosphate-coated oral implants subjected to an occlusal load, an experimental study in the dog

    NARCIS (Netherlands)

    Junker, R.; Manders, P.J.D.; Wolke, J.G.C.; Borisov, Y.; Braceras, I.; Jansen, J.A.

    2011-01-01

    BACKGROUND: A new microplasma spraying equipment (MSE) to deposit calcium phosphate (CaP) ceramic coatings onto titanium substrates has been developed. With this system, it is possible to spray fine particles and to apply textured hydroxylapatite coatings onto titanium surfaces. Moreover, due to the

  16. Ambient Volatility of Triethyl Phosphate

    Science.gov (United States)

    2017-08-01

    AMBIENT VOLATILITY OF TRIETHYL PHOSPHATE ECBC-TR-1476 James H. Buchanan John J. Mahle RESEARCH AND...2017 2. REPORT TYPE Final 3. DATES COVERED (From - To) Oct 2016 – Jan 2017 4. TITLE: Ambient Volatility of Triethyl Phosphate 5a. CONTRACT...humidity on TEPO volatility is nearly as predicted by Raoult’s law, that is, vapor pressure suppression is proportional to ambient relative humidity. An

  17. Construction material

    Science.gov (United States)

    Wagh, Arun S [Orland Park, IL; Antink, Allison L [Bolingbrook, IL

    2008-07-22

    A structural material of a polystyrene base and the reaction product of the polystyrene base and a solid phosphate ceramic is applied as a slurry which includes one or more of a metal oxide or a metal hydroxide with a source of phosphate to produce a phosphate ceramic and a poly (acrylic acid or acrylate) or combinations or salts thereof and polystyrene or MgO applied to the polystyrene base and allowed to cure so that the dried aqueous slurry chemically bonds to the polystyrene base. A method is also disclosed of applying the slurry to the polystyrene base.

  18. The diametral tensile strength and hydrostability of polymer-ceramic nano-composite (pcnc) material prototypes

    Science.gov (United States)

    Yepez, Johanna

    Statement of the problem: There is a weak connection between the filler and the resin matrix of dental composites caused primarily by hydrolysis of silane coupling agent, therefore, jeopardizing the mechanical properties of the dental restorations. Purpose: The purpose of this study was to compare the diametral tensile strength (DTS) of a nano-mechanically bonded polymer ceramic nano composite (pcnc) versus the chemically bonding prototype polymer ceramic nano composite (pcnc) fabricated by using hydrolytically stable interphase. Materials and Methods: Composites were made with 60wt % filler, 38% triethyleneglycol dimethacrylate (TEDGMA), 1% camphorquinone (CQ) and 1% 2-(dimethylamino) ethyl methacrylate (DMAEMA). Tests for DTS were performed using a universal testing machine. The disk-shaped specimens were loaded in compression between two supporting plates at a crosshead speed of 0.5 mm/min until fracture. The samples, measuring 3 mm in height and 6 mm in diameter, were produced in a round stainless steel (SS) mold. A total of 144 samples were created. Groups of 48 samples were made for each of three different fillers. Specimens were soaked in artificial saliva at 37° for four time periods, dry(t=0), 1 day, 7 days, 28 days). At the end of each soaking time DTS tests were performed. Results: There where statistically significant differences in the DTS between the filler groups and the soaking times (p=dental composites is a detrimental factor in the mechanical behavior. The silanation of the filler particles have a positive influence on the mechanical properties of dental composites but the hydrolysis of the silane coupling agent can dramatically reduce the average lifetime of dental composites.

  19. short communication agronomic effectiveness of novel phosphate

    African Journals Online (AJOL)

    A review of literature shows that work on non-conventional phosphate fertilisers has been done exclusively on sedimentary phosphate rocks. The potential of using novel phosphate fertiliser materials derived from unreactive igneous Dorowa (Zimbabwe) phosphate rock was investigated in a greenhouse experiment.

  20. Phosphate solubilization and multiple plant growth promoting ...

    African Journals Online (AJOL)

    Phosphate solubilizing efficiencies of the strains were analyzed using different insoluble phosphorus sources and the results show that most isolates released a substantial amount of soluble phosphate from tricalcium phosphate, rock phosphate and bone meal. Screening for multiple plant growth promoting attributes ...