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Sample records for polyphosphate gels synthesis

  1. Dye incorporation in polyphosphate gels: synthesis and theoretical calculations

    Directory of Open Access Journals (Sweden)

    Jordan Del Nero

    2003-06-01

    Full Text Available In this work we described theoretical calculations on the electronic structure and optical properties of the dyes crystal violet and malachite green based in semiempirical methods (Parametric Method 3 and Intermediate Neglect of Differential Overlap / Spectroscopic - Configuration Interaction and the synthesis of a new hybrid material based upon the incorporation of these dyes in an aluminum polyphosphate gel network. The samples are nearly transparent, free-standing thick films. The optical properties of the entrapped dyes are sensitive to chemical changes within the matrix caused either by gel aging or external stimulli such as exposition to acidic and basic vapors that can percolate within the matrix. Our theoretical modeling is in good agreement with the experimental results for the dyes.

  2. Mechanism of polyphosphate kinase from Propionibacterium shermanii

    International Nuclear Information System (INIS)

    Robinson, N.A.

    1986-01-01

    Polyphosphate kinase, which catalyzes the reaction shown below, is one of two enzymes which have been reported to catalyze the synthesis of polyphosphate. Purification performed by ammonium sulfate precipitation (0-40% fraction) was followed by chromatography. The enzyme represents 70% of the protein in the hydroxylapatite pool and is stable at this level of purity. The subunit molecular weight was determined by SDS polyacrylamide gel analysis, (83,000 +/- 3000), nondenaturing polyacrylamide gel electrophoresis, (80,000 and 86,000 daltons), gel filtration (Biogel A 0.5m column was 85,000 +/- 4000.) Polyphosphate kinase appears to be a monomeric enzyme of ∼83,000 daltons. Four assays were developed for polyphosphate kinase. Basic proteins such as polylysine stimulate the synthesis of polyphosphate, these proteins cause precipitation of polyphosphate kinase from relatively impure enzyme extracts: Synthesized polyphosphate interacts noncovalently with the basic protein-enzyme precipitate. Efficient synthesis of polyphosphate requires the addition of either phosphate or short chain polyphosphate. Synthesis did occur at 1/10 the rate when neither of these two compounds were included. Initiation, elongation, and termination events of polyphosphate synthesis were examined. Short chain polyphosphate acts as a primer, with [ 32 P] short-chain polyphosphate incorporation into long chain polyphosphate by the kinase

  3. Polyphosphate-dependent synthesis of ATP and ADP by the family-2 polyphosphate kinases in bacteria.

    Science.gov (United States)

    Nocek, Boguslaw; Kochinyan, Samvel; Proudfoot, Michael; Brown, Greg; Evdokimova, Elena; Osipiuk, Jerzy; Edwards, Aled M; Savchenko, Alexei; Joachimiak, Andrzej; Yakunin, Alexander F

    2008-11-18

    Inorganic polyphosphate (polyP) is a linear polymer of tens or hundreds of phosphate residues linked by high-energy bonds. It is found in all organisms and has been proposed to serve as an energy source in a pre-ATP world. This ubiquitous and abundant biopolymer plays numerous and vital roles in metabolism and regulation in prokaryotes and eukaryotes, but the underlying molecular mechanisms for most activities of polyP remain unknown. In prokaryotes, the synthesis and utilization of polyP are catalyzed by 2 families of polyP kinases, PPK1 and PPK2, and polyphosphatases. Here, we present structural and functional characterization of the PPK2 family. Proteins with a single PPK2 domain catalyze polyP-dependent phosphorylation of ADP to ATP, whereas proteins containing 2 fused PPK2 domains phosphorylate AMP to ADP. Crystal structures of 2 representative proteins, SMc02148 from Sinorhizobium meliloti and PA3455 from Pseudomonas aeruginosa, revealed a 3-layer alpha/beta/alpha sandwich fold with an alpha-helical lid similar to the structures of microbial thymidylate kinases, suggesting that these proteins share a common evolutionary origin and catalytic mechanism. Alanine replacement mutagenesis identified 9 conserved residues, which are required for activity and include the residues from both Walker A and B motifs and the lid. Thus, the PPK2s represent a molecular mechanism, which potentially allow bacteria to use polyP as an intracellular energy reserve for the generation of ATP and survival.

  4. Sol gel-derived hydroxyapatite films over porous calcium polyphosphate substrates for improved tissue engineering of osteochondral-like constructs.

    Science.gov (United States)

    Lee, Whitaik David; Gawri, Rahul; Pilliar, Robert M; Stanford, William L; Kandel, Rita A

    2017-10-15

    Integration of in vitro-formed cartilage on a suitable substrate to form tissue-engineered implants for osteochondral defect repair is a considerable challenge. In healthy cartilage, a zone of calcified cartilage (ZCC) acts as an intermediary for mechanical force transfer from soft to hard tissue, as well as an effective interlocking structure to better resist interfacial shear forces. We have developed biphasic constructs that consist of scaffold-free cartilage tissue grown in vitro on, and interdigitated with, porous calcium polyphosphate (CPP) substrates. However, as CPP degrades, it releases inorganic polyphosphates (polyP) that can inhibit local mineralization, thereby preventing the formation of a ZCC at the interface. Thus, we hypothesize that coating CPP substrate with a layer of hydroxyapatite (HA) might prevent or limit this polyP release. To investigate this we tested both inorganic or organic sol-gel processing methods, asa barrier coating on CPP substrate to inhibit polyP release. Both types of coating supported the formation of ZCC in direct contact with the substrate, however the ZCC appeared more continuous in the tissue formed on the organic HA sol gel coated CPP. Tissues formed on coated substrates accumulated comparable quantities of extracellular matrix and mineral, but tissues formed on organic sol-gel (OSG)-coated substrates accumulated less polyP than tissues formed on inorganic sol-gel (ISG)-coated substrates. Constructs formed with OSG-coated CPP substrates had greater interfacial shear strength than those formed with ISG-coated and non-coated substrates. These results suggest that the OSG coating method can modify the location and distribution of ZCC and can be used to improve the mechanical integrity of tissue-engineered constructs formed on porous CPP substrates. Articular cartilage interfaces with bone through a zone of calcified cartilage. This study describes a method to generate an "osteochondral-like" implant that mimics this

  5. Sol-Gel Synthesis Of Aluminoborosilicate Powders

    Science.gov (United States)

    Bull, Jeffrey; Leiser, Daniel; Selvaduray, Guna

    1992-01-01

    Application of sol-gel process to synthesis of aluminoborosilicate powders shows potential for control of microstructures of materials. Development of materials having enhanced processing characteristics prove advantageous in extending high-temperature endurance of fibrous refractory composite insulation made from ceramic fibers.

  6. Sol-gel synthesis of hydroxyapatite

    International Nuclear Information System (INIS)

    Zupanski, M.D.; Lucena, M.P.P.; Bergmann, C.P.

    2010-01-01

    Hydroxyapatite (HAp) has been established as the calcium phosphate based compound with most applications in the biological field. Among the numerous techniques for synthesis of HAp, the sol-gel processing route affords great control over purity and formed phases using low processing temperatures. In addition, the sol-gel approach offers an option for homogeneous HAp coating on metal substrates, as well as the ability to generate nanocrystalline powders. In this work, the sol-gel synthesis of HAp was investigated employing triethyl phosphate and calcium nitrate tetrahydrate as phosphorous and calcium precursors, respectively. The aging effect on phase composition and powder morphology of the final product was studied in terms of temperature and aging time. The powders were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, particle size distribution by laser diffraction and scanning electron microscopy. (author)

  7. Gel combustion synthesis of yttria stabilized zirconia

    International Nuclear Information System (INIS)

    Vijay, Soja K.; Chandramouli, V.; Anthonysamy, S.

    2013-01-01

    Nano - crystalline 8 mol% yttria stabilized zirconia (YSZ) powders were synthesized by gel combustion technique employing both microwave heating as well as conventional heating method. Three different fuels - citric acid, urea and glycine were used for the synthesis with fuel to oxidant ratio as 1:1. The effect of fuel on the crystal structure, particle size, specific surface area, morphology and sintering density was studied. X-ray powder diffraction (XRD), BET gas adsorption technique, dynamic light scattering, transmission and scanning electron microscopy (TEM and SEM) and micro-Raman spectroscopy were used to characterize the powders. The results obtained for powders obtained using both methods - microwave assisted and hotplate - were compared. The specific surface area of powders in all cases are comparable except in the case of urea as fuel where microwave assisted synthesis yielded powders with lower surface area. The particle size distribution of all samples obtained using microwave method was unimodal, whereas the particle size distribution of samples prepared using hot plate method using urea fuel showed bimodal distribution. The compacts obtained using powders with citric acid and glycine as fuel showed more than 94% theoretical density, whereas the samples obtained using urea showed density below 90% of theoretical density. (author)

  8. Are Polyphosphates or Phosphate Esters Prebiotic Reagents?

    Science.gov (United States)

    Keefe, Anthony D.; Miller, Stanley L.

    1995-01-01

    It is widely held that there was a phosphate compound in prebiotic chemistry that played the role of adenosine triphosphate and that the first living organisms had ribose-phosphate in the backbone of their genetic material. However, there are no known efficient prebiotic synthesis of high-energy phosphates or phosphate esters. We review the occurrence of phosphates in nature, the efficiency of the volcanic synthesis of P4O10, the efficiency of polyphosphate synthesis by heating phosphate minerals under geological conditions, and the use of high-energy organic compounds such as cyanamide or hydrogen cyanide. These are shown to be inefficient processes especially when the hydrolysis of the polyphosphates is taken into account. For example, if a whole atmosphere of methane or carbon monoxide were converted to cyanide which somehow synthesized polyphosphates quantitatively, the polyphosphate concentration in the ocean would still have been insignificant. We also attempted to find more efficient high-energy polymerizing agents by spark discharge syntheses, but without success. There may still be undiscovered robust prebiotic syntheses of polyphosphates, or mechanisms for concentrating them, but we conclude that phosphate esters may not have been constituents of the first genetic material. Phosphoanhydrides are also unlikely as prebiotic energy sources.

  9. Sol-gel synthesis of hydroxyapatite; Sintese de hidroxiapatita via sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Zupanski, M.D.; Lucena, M.P.P.; Bergmann, C.P., E-mail: michelledunin@yahoo.com.b [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)

    2010-07-01

    Hydroxyapatite (HAp) has been established as the calcium phosphate based compound with most applications in the biological field. Among the numerous techniques for synthesis of HAp, the sol-gel processing route affords great control over purity and formed phases using low processing temperatures. In addition, the sol-gel approach offers an option for homogeneous HAp coating on metal substrates, as well as the ability to generate nanocrystalline powders. In this work, the sol-gel synthesis of HAp was investigated employing triethyl phosphate and calcium nitrate tetrahydrate as phosphorous and calcium precursors, respectively. The aging effect on phase composition and powder morphology of the final product was studied in terms of temperature and aging time. The powders were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, particle size distribution by laser diffraction and scanning electron microscopy. (author)

  10. Encapsulation of nanoclusters in dried gel materials via an inverse micelle/sol gel synthesis

    Science.gov (United States)

    Martino, Anthony; Yamanaka, Stacey A.; Kawola, Jeffrey S.; Showalter, Steven K.; Loy, Douglas A.

    1998-01-01

    A dried gel material sterically entrapping nanoclusters of a catalytically active material and a process to make the material via an inverse micelle/sol-gel synthesis. A surfactant is mixed with an apolar solvent to form an inverse micelle solution. A salt of a catalytically active material, such as gold chloride, is added along with a silica gel precursor to the solution to form a mixture. To the mixture are then added a reducing agent for the purpose of reducing the gold in the gold chloride to atomic gold to form the nanoclusters and a condensing agent to form the gel which sterically entraps the nanoclusters. The nanoclusters are normally in the average size range of from 5-10 nm in diameter with a monodisperse size distribution.

  11. Polyphosphates substitution for zeolite to in detergents

    International Nuclear Information System (INIS)

    Restrepo V, Gloria M.; Ocampo G, Aquiles; Saldarriaga M, Carlos

    1996-01-01

    The detergents, as well as the cleaning products, contain active ingredients that are good to increase their efficiency and some of them, as the sodium Tripoli-phosphate (TPF), they have turned out to be noxious for the environment. The zeolites use in the formulation of detergents has grown substantially since they fulfill the same function of the TPF and they have been recommended ecologically as substitutes from these when not being polluting. The objective of this work is to obtain a zeolite with appropriate characteristics for its use in the formulation of detergents, reproducing those of the zeolites used industrially. The zeolite synthesis is studied 4A starting from hydro-gels of different composition, varying the operation conditions and using two raw materials: (sodium meta-silicate, commercial degree and metallic aluminum) and clay type kaolin like silica source and aluminum It is looked for to get a product of beveled cubic morphology, or spherical, with glass size between 1 and 3 microns and that it possesses good capacity of conical exchange. Since the capacity and speed of ionic exchange is influenced by the particle size, time of contact and temperature, experimentation conditions settle down to measure the exchange of ions calcium and magnesium in watery solutions that they simulate the real situation of a laundry process in the country. This way the ability of the zeolite 4A obtained to diminish the concentration of these ions in the laundry waters is evaluated and its possibilities like component in the formulation of detergents non-phosphatates. Of the synthesized zeolites, the best in agreement is chosen with chemical properties as ionic and physical exchange capacity as crystalline, particle size and color, to prepare a detergent in which the polyphosphates is substituted partial and totally for the synthesized zeolite

  12. Sol – Gel synthesis and characterization of magnesium peroxide nanoparticles

    International Nuclear Information System (INIS)

    Jaison, J; Chan, Y S; Ashok raja, C; Balakumar, S

    2015-01-01

    Magnesium peroxide is an excellent source of oxygen in agriculture applications, for instance it is used in waste management as a material for soil bioremediation to remove contaminants from polluted underground water, biological wastes treatment to break down hydrocarbon, etc. In the present study, sol-gel synthesis of magnesium peroxide (MgO 2 ) nanoparticles is reported. Magnesium peroxide is odourless; fine peroxide which releases oxygen when reacts with water. During the sol-gel synthesis, the magnesium malonate intermediate is formed which was then calcinated to obtain MgO 2 nanoparticles. The synthesized nanoparticles were characterized using Thermo gravimetric -Differential Thermal Analysis (TG- DTA), X-Ray Diffraction studies (XRD) and High Resolution Transmission Electron Microscope (HRTEM). Our study provides a clear insight that the formation of magnesium malonate during the synthesis was due to the reaction between magnesium acetate, oxalic acid and ethanol. In our study, we can conclude that the calcination temperature has a strong influence on particle size, morphology, monodispersity and the chemistry of the particles. (paper)

  13. Synthesis of phthalocyanine doped sol-gel materials

    Science.gov (United States)

    Dunn, Bruce

    1993-01-01

    The synthesis of sol-gel silica materials doped with three different types of metallophthalocyanines has been studied. Homogeneous materials of good optical quality were prepared and the first optical limiting measurements of dyes in sol-gel hosts were carried out. The properties of these solid state limiters are similar to limiters based on phthalocyanine (Pc) in solution. Sol-gel silica materials containing copper, tin and germanium phthalocyanines were investigated. The initial step in all cases was to prepare silica sols by the sonogel method using tetramethoxy silane (TMOS), HCl and distilled water. Thereafter, the synthesis depended upon the specific Pc and its solubility characteristics. Copper phthalocyanine tetrasulfonic acid tetra sodium salt (CuPc4S) is soluble in water and various doping levels (1 x 10 (exp -4) M to 1 x 10 (exp -5) M) were added to the sol. The group IV Pc's, SnPc(OSi(n-hexyl)3)2 and GePc(OSi(n-hexyl)3)2, are insoluble in water and the process was changed accordingly. In these cases, the compounds were dissolved in THF and then added to the sol. The Pc concentration in the sol was 2 x 10(exp -5)M. The samples were then aged and dried in the standard method of making xerogel monoliths. Comparative nanosecond optical limiting experiments were performed on silica xerogels that were doped with the different metallophthalocyanines. The ratio of the net excited state absorption cross section (sigma(sub e)) to the ground state cross section (sigma(sub g)) is an important figure of merit that is used to characterize these materials. By this standard the SnPc sample exhibits the best limiting for the Pc doped sol-gel materials. Its cross section ratio of 19 compares favorably with the value of 22 that was measured in toluene. The GePc materials appear to not be as useful as those containing SnPc. The GePc doped solids exhibit a higher onset energy (2.5 mj and lower cross section ratio, 7. The CuPc4S sol-gel material has a still lower cross

  14. Synthesis of ZNO nanoparticles by Sol-Gel processing

    International Nuclear Information System (INIS)

    Savi, B.M.; Rodrigues, L.; Uggioni, E.; Bernardin, A.M.

    2011-01-01

    The aim of this study was to obtain and characterize ZnO nanoparticles by Sol-Gel technique. ZnCl 2 , Zn(NO 3 ) 2 , NaOH were used as precursors for the synthesis. NaOH was dissolved in distilled water at a concentration of 1.0 M with agitation to the desired reaction temperature (50°C and 90°C). 0.5 M ZnCl 2 and 0.5 M Zn(NO3)2 were added by dripping (60 and 30 min). The powder was characterized by XRD (Cu Kα), UV-Vis, and HR-TEM. Nano ZnO particles were obtained with crystallite size between 20 and 40 nm (HR-TEM and XRD). The results of UV-Vis spectrometry show that the band gap energy, given by the absorbance at 300 nm depends on the precursor used. (author)

  15. Synthesis, crystal structure, optical and thermal properties of lanthanide hydrogen-polyphosphates Ln[H(PO3)4] (Ln = Tb, Dy, Ho).

    Science.gov (United States)

    Förg, Katharina; Höppe, Henning A

    2015-11-28

    Lanthanide hydrogen-polyphosphates Ln[H(PO3)4] (Ln = Tb, Dy, Ho) were synthesised as colourless (Ln = Tb, Dy) and light pink (Ln = Ho) crystalline powders by reaction of Tb4O7/Dy2O3/Ho2O3 with H3PO3 at 380 °C. All compounds crystallise isotypically (P2(1)/c (no. 14), Z = 4, a(Tb) = 1368.24(4) pm, b(Tb) = 710.42(2) pm, c(Tb) = 965.79(3) pm, β(Tb) = 101.200(1)°, 3112 data, 160 parameters, wR2 = 0.062, a(Ho) = 1363.34(5) pm, b(Ho) = 709.24(3) pm, c(Ho) = 959.07(4) pm, β(Ho) = 101.055(1)°, 1607 data, 158 parameters, wR2 = 0.058). The crystal structure comprises two different infinite helical chains of corner-sharing phosphate tetrahedra. In-between these chains the lanthanide ions are located, coordinated by seven oxygen atoms belonging to four different polyphosphate chains. Vibrational, UV/Vis and fluorescence spectra of Ln[H(PO3)4] (Ln = Tb, Dy, Ho) as well as Dy[H(PO3)4]:Ln (Ln = Ce, Eu) and the magnetic and thermal behaviour of Tb[H(PO3)4] are reported.

  16. Glycogen-bound polyphosphate kinase from the archaebacterium Sulfolobus acidocaldarius.

    OpenAIRE

    Skórko, R; Osipiuk, J; Stetter, K O

    1989-01-01

    Glycogen-bound polyphosphate kinase has been isolated from a crude extract of Sulfolobus acidocaldarius by isopycnic centrifugation in CsCl. Divalent cations (Mn2+ greater than Mg2+) stimulated the reaction. The enzyme does not require the presence of histones for its activity; it is inhibited strongly by phosphate and slightly by fluoride. The protein from the glycogen complex migrated in a sodium dodecyl sulfate-polyacrylamide gel as a 57-kilodalton protein band; after isoelectric focusing ...

  17. Variables of synthesis in obtaining nanosilicas with sol-gel

    International Nuclear Information System (INIS)

    Elia, A; Martin-Aispuro, P; Musante, L; Martin-Martinez, J.M; Vazquez, P

    2008-01-01

    (c), as a catalyst, had a smaller particle size than those obtained with other acids (such as acetic acid, for example). These samples also revealed an almost spherical morphology with a nanometric particle size. Meanwhile, using the EDX analysis technique, the compositions of the synthesized samples were determined and the results show that the atomic percentage relationship between O and Si is about 66% to 33% (SiO 2 ), for specific study conditions. Therefore, this work offers a new proposal for the synthesis of materials with technological applications which involves easy processes and low costs for the region's small enterprises. The substitution of very expensive pyrogenic silica with silica obtained with sol-gel in its different uses is one of the aims of this research

  18. Synthesis of uranium and thorium dioxides by Complex Sol-Gel Processes (CSGP). Synthesis of uranium oxides by Complex Sol-Gel Processes (CSGP)

    International Nuclear Information System (INIS)

    Deptula, A.; Brykala, M.; Lada, W.; Olczak, T.; Wawszczak, D.; Chmielewski, A.G.; Modolo, G.; Daniels, H.

    2010-01-01

    In the Institute of Nuclear Chemistry and Technology (INCT), a new method of synthesis of uranium and thorium dioxides by original variant of sol-gel method - Complex Sol-Gel Process (CSGP), has been elaborated. The main modification step is the formation of nitrate-ascorbate sols from components alkalized by aqueous ammonia. Those sols were gelled into: - irregularly agglomerates by evaporation of water; - medium sized microspheres (diameter <150) by IChTJ variant of sol-gel processes by water extraction from drops of emulsion sols in 2-ethylhexanol-1 by this solvent. Uranium dioxide was obtained by a reduction of gels with hydrogen at temperatures >700 deg. C, while thorium dioxide by a simple calcination in the air atmosphere. (authors)

  19. Effect of DCCA on synthesis of inorganic mesoporous gels

    International Nuclear Information System (INIS)

    Nemancha, A.R.

    2004-01-01

    Full text.The porous texture of the monolith inorganic gels plays an important role in the utilization of porous material by control of several properties such as gas diffusion, thermal stability, mechanical strength. the sol gel process provides many possibilities to manufacture porous material with extremely low concentration of impurities at low sinter temperature. The serious problem in the production of the monolith gels is fracture and crack formation which may occur in the conversion of the wet gels to dry gels. This phenomenon is probably due to the capillary forces which appear during the drying steps. in order to reduce the effect of capillary forces a number of methods were applied (hyper critic drying, organic DCCAs). The purpose of the present work, is to understand the chemical changes that result from adding formamide as drying control chemical additives DCCA to the colloidal silica sols in the presence of acid catalyst. Fourier Transformed Infrared spectroscopy and Raman spectroscopy were used to investigate the influence of formamide on gel formation. The Nitrogen adsorption-desorption technique is used to investigate the effect of formamide on gel texture. The results show that the gels with formamide are monolith and obtained during a short time of gelling reaction, the silica particles link formation depend strongly on the formamide concentration. the BET and BJH results show that the presence of formamide promotes the creation of meso porous texture depending on formamide/silica molar ratio in the starting sol. The maximum average diameter of the obtained gel reaches a value close to 25 nm with a bulk density equal to 1.1 g/cm 3

  20. Study of nuclear glasses alteration gel and synthesis of some model gels

    International Nuclear Information System (INIS)

    Ricol, S.

    1995-01-01

    This work deals with the general problem of alteration of the reference nuclear glass R7T7. Attention is paid particularly to the altered layer formed at the glass surface during alteration process. In opposition to previous works, related essentially to glass dissolution kinetics based on chemical analyses of lixiviated elements, this thesis deals with alteration problems through structural studies of the reference glass and derived gel. This approach allows the determination of mechanisms for the gel formation and a better understanding of the behaviour of glasses towards lixiviation. Both approaches appeared complementary. Based on several spectroscopic techniques, this work showed the particular role of cations such as calcium, zirconium and iron. Studies of silica-based synthetic gels showed the synergic effect of formers cation and of one highly coordinated cation. The variation of the wavenumber related to Si-O-Si asymmetric stretching vibration can be correlated to O/Si ratio for ternary systems Si/Na/Zr. On the contrary, the Si losses of the materials depend on the number of non-bridging oxygen atoms. In the perspective of long-term behaviour, the alteration gel presents better characteristics than initial glass. It is therefore a highly stable material in static conditions. In the same way, synthetic gels are materials with very low solubilities (much lower than the alteration gel) and could be used as confining matrices. (authors). refs., 71 figs., 37 tabs

  1. Polyphosphate nanoparticles on the platelet surface trigger contact system activation

    NARCIS (Netherlands)

    Verhoef, Johan J F; Barendrecht, Arjan D; Nickel, Katrin F; Dijkxhoorn, Kim; Kenne, Ellinor; Labberton, Linda; McCarty, Owen J T; Schiffelers, Raymond; Heijnen, Harry F G; Hendrickx, Antoni P A; Schellekens, Huub; Fens, Marcel H; de Maat, Steven; Renné, Thomas; Maas, Coen

    2017-01-01

    Polyphosphate is an inorganic polymer that can potentiate several interactions in the blood coagulation system. Blood platelets contain polyphosphate, and the secretion of platelet-derived polyphosphate has been associated with increased thrombus formation and activation of coagulation factor XII.

  2. Synthesis and characterization of gel-grown cobalt tartrate crystals

    Indian Academy of Sciences (India)

    ... in electronics, optics and industries. A series of pure and mixed crystals ... bility method. A few researchers reported the growth of crystals of strontium tartrate ... grow it by chemical reaction method using the gel technique. The crystallization ...

  3. The Synthesis of a Novel Cellulose Physical Gel

    Directory of Open Access Journals (Sweden)

    Jiufang Duan

    2014-01-01

    Full Text Available Cellulose possessing β-cyclodextrin (β-CD was used as a host molecule and cellulose possessing ferrocene (Fc as a guest polymer. Infrared spectra, differential scanning calorimetry (DSC, ultraviolet spectroscopy (UV, and contact angle analysis were used to characterise the material structure and the inclusion behaviour. The results showed that the β-CD-cellulose and the Fc-cellulose can form inclusion complexes. Moreover, ferrocene oxidation, and reduction of state can be adjusted by sodium hypochlorite (NaClO as an oxidant and glutathione (GSH as a reductant. In this study, a physical gel based on β-CD-cellulose/Fc-cellulose was formed under mild conditions in which autonomous healing between cut surfaces occurred after 24 hours. The physical gel can be controlled in the sol-gel transition. The compressive strength of the Fc-cellulose/β-CD-cellulose gel increased with increased cellulose concentration. The host-guest interaction between the side chains of cellulose could strengthen the gel. The cellulose physical gel may eventually be used as a stimulus-responsive, healing material in biomedical applications.

  4. Sol-gel synthesis and densification of aluminoborosilicate powders. Part 1: Synthesis

    Science.gov (United States)

    Bull, Jeffrey; Selvaduray, Guna; Leiser, Daniel

    1992-01-01

    Aluminoborosilicate powders high in alumina content were synthesized by the sol-gel process utilizing various methods of preparation. Properties and microstructural effects related to these syntheses were examined. After heating to 600 C for 2 h in flowing air, the powders were amorphous with the metal oxides comprising 87 percent of the weight and uncombusted organics the remainder. DTA of dried powders revealed a T(sub g) at approximately 835 C and an exotherm near 900 C due to crystallization. Powders derived from aluminum secbutoxide consisted of particles with a mean diameter 5 microns less than those from aluminum isopropoxide. Powders synthesized with aluminum isopropoxide produced agglomerates comprised of rod shaped particulates while powders made with the secbutoxide precursor produced irregular glassy shards. Compacts formed from these powders required different loadings for equivalent densities according to the method of synthesis.

  5. Ultrasound-assisted sol-gel synthesis of ZrO2.

    Science.gov (United States)

    Guel, Marlene Lariza Andrade; Jiménez, Lourdes Díaz; Hernández, Dora Alicia Cortés

    2017-03-01

    Synthesis of tetragonal ZrO 2 by both conventional sol-gel and ultrasound-assisted sol-gel methods and using a non-ionic surfactant Tween-20, was performed. A porous microstructure composed of nanometric particles was observed. Tetragonal ZrO 2 was obtained using a low heat treatment temperature of powders, 500°C by both methods. A higher crystallinity and a shorter reaction time were observed when ultrasound was used in the sol-gel method due to the cavitation phenomenon. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Dry gel conversion synthesis of SAPO-34 nanocrystals

    International Nuclear Information System (INIS)

    Hirota, Yuichiro; Murata, Kenji; Tanaka, Shunsuke; Nishiyama, Norikazu; Egashira, Yasuyuki; Ueyama, Korekazu

    2010-01-01

    SAPO-34 nanocrystals were synthesized by a dry gel conversion method using tetraethylammonium hydroxide as a structure-directing agent. The crystal growth of SAPO-34 was studied by X-ray diffraction and field-emission scanning electron microscopy. After 3 h, 45-nm SAPO-34 crystals with an amorphous phase were observed. The crystal size increased to 70 nm after 6 h, but did not increase greatly thereafter. The average crystal size of the final product was 75 nm. The nucleation density for SAPO-34 crystals in dry gel conversion appeared to be much higher than that under hydrothermal conditions, resulting in the formation of small crystals.

  7. Glycogen-bound polyphosphate kinase from the archaebacterium Sulfolobus acidocaldarius.

    Science.gov (United States)

    Skórko, R; Osipiuk, J; Stetter, K O

    1989-09-01

    Glycogen-bound polyphosphate kinase has been isolated from a crude extract of Sulfolobus acidocaldarius by isopycnic centrifugation in CsCl. Divalent cations (Mn2+ greater than Mg2+) stimulated the reaction. The enzyme does not require the presence of histones for its activity; it is inhibited strongly by phosphate and slightly by fluoride. The protein from the glycogen complex migrated in a sodium dodecyl sulfate-polyacrylamide gel as a 57-kilodalton protein band; after isoelectric focusing it separated into several spots in the pH range of 5.6 to 6.7.

  8. Synthesis of hydroxyapatite nanopowders by sol–gel emulsion ...

    Indian Academy of Sciences (India)

    Administrator

    gel emulsion technique, where the sol (water medium) is emulsified, in a support ... The sol was prepared by mixing a 2 M solution of calcium acetate dissolved in ... powder using a punch and die set and a KBr press (model. M-15) with a ...

  9. 3D Architectured polyazomethine gel synthesis: its self-assembled ...

    Indian Academy of Sciences (India)

    2018-03-28

    Mar 28, 2018 ... Schiff's base reactions are well-known organic reactions that are the main source of ... it difficult to ver- satile applications and the determination of their structural ... Since non-covalent gel phase materials are formed through weak and .... nitrogen as major elements in the composition, which proves that the ...

  10. Sol-gel Synthesis of a Biotemplated Inorganic Photocatalyst

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Yue, Yuanzheng; He, Wen

    2012-01-01

    chemistry and photocatalysis, provides an opportunity to teach valuable laboratory skills and to introduce students to the synthesis, isolation, and characterization of inorganic materials. This laboratory activity is adaptable to a range of educational levels and to various instrumental techniques....

  11. Study of nuclear glasses alteration gel and synthesis of some model gels; Etude du gel d`alteration des verres nucleaires et synthese de gels modeles

    Energy Technology Data Exchange (ETDEWEB)

    Ricol, S

    1995-10-05

    This work deals with the general problem of alteration of the reference nuclear glass R7T7. Attention is paid particularly to the altered layer formed at the glass surface during alteration process. In opposition to previous works, related essentially to glass dissolution kinetics based on chemical analyses of lixiviated elements, this thesis deals with alteration problems through structural studies of the reference glass and derived gel. This approach allows the determination of mechanisms for the gel formation and a better understanding of the behaviour of glasses towards lixiviation. Both approaches appeared complementary. Based on several spectroscopic techniques, this work showed the particular role of cations such as calcium, zirconium and iron. Studies of silica-based synthetic gels showed the synergic effect of formers cation and of one highly coordinated cation. The variation of the wavenumber related to Si-O-Si asymmetric stretching vibration can be correlated to O/Si ratio for ternary systems Si/Na/Zr. On the contrary, the Si losses of the materials depend on the number of non-bridging oxygen atoms. In the perspective of long-term behaviour, the alteration gel presents better characteristics than initial glass. It is therefore a highly stable material in static conditions. In the same way, synthetic gels are materials with very low solubilities (much lower than the alteration gel) and could be used as confining matrices. (authors). refs., 71 figs., 37 tabs.

  12. Synthesis of cadmium tungstate films via sol-gel processing

    Energy Technology Data Exchange (ETDEWEB)

    Lennstrom, Kirk; Limmer, Steven J.; Cao Guozhong

    2003-06-23

    Cadmium tungstate is a scintillator material with excellent intrinsic photoluminescent properties. It is highly resistant to gamma radiation, has an almost non-existent afterglow and is highly efficient. Cadmium tungstate is also non-hydroscopic, unlike the more prevalent thallium-doped alkali halide scintillators. In order to create thin films of cadmium tungstate with precise stoichiometric control, a sol-gel processing technique has been applied to produce this material for the first time. In addition to lower processing temperatures, sol-gel-derived cadmium tungstate is cheaper and easier than other technologies, particularly for thin films. Furthermore, it has the potential to produce nanostructured materials with good optical quality. X-Ray diffraction results of sol-gel-derived materials fired at various temperatures imply crystallization of cadmium tungstate without the intermediate formation of either tungsten oxide or cadmium oxide. Scanning electron microscopy analysis shows the formation of nano-sized particles prior to heat treatment, which form meso-sized particles after the heat treatment. Photoluminesce analysis indicates emission of derived films at 480 nm, which agrees with other published data. Finally, the efficiency of derived films was approximately 6%{+-}1.8%.

  13. Synthesis of lithium doped zinc oxide by sol gel

    International Nuclear Information System (INIS)

    Meziane, K; Elhichou, A; Elhamidi, A; Almaggoussi, A; CHHIBA, M

    2016-01-01

    Li-doped ZnO thin films were prepared by sol-gel method and deposed on glass substrate using spin coating technique. The effects of Li on structural and optical properties were investigated. The X-ray diffraction (XRD) analysis reveals that Li incorporation leads to the great improvement of the crystalline quality of ZnO thin films. Scanning electron microscopy (SEM) images showed that nanowires are aligned nearly perpendicular to the substrate plane and are affected significantly by Li incorporation. The optical transmission of the films was higher than 80% in the visible region. It is found that the optical gap and the refractive index remain practically constant. (paper)

  14. Sol-gel synthesis and characterization of lithiummolybdosilicate glass

    International Nuclear Information System (INIS)

    Prakash, I.; Nallamuthu, N.; Muralidharan, P.; Satyanarayana, N.; Venkateswarlu, M.; Balasubramanyam, S.

    2008-01-01

    10 % Li 2 O + 0.9 % MoO 3 + 89.1 %SiO 2 (LMS) glassy sample was prepared using Sol-gel process and was characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC) techniques. The ion conducting mechanism was studied through impedance technique at various temperatures. The conductivity of the sample was found to be 4.1257 x 10 -8 Scm -1 at 613 K. The activation energy was calculated from the log (sT) vs. 1000/T plot and it was found to be (0.1466 ± 0.012) eV. (author)

  15. Sol gel synthesis for preparation of yttrium aluminium garnet

    NARCIS (Netherlands)

    Vrolijk, J.W.G.A.; Willems, J.W.M.M.; Metselaar, R.; With, de G.; Terpstra, R.A.; Metselaar, R.

    1989-01-01

    Sol-gel—synthesis for preparation of pure yttrium aluminium garnet powder with small grain size is subject of this ongoing study. Starting materials were sulfates and chlorides of yttrium and aluminium. To obtain pure YAG (Y3A1SO1Z) pH during hydrolysis as well as temperature during calcination and

  16. Osteoconducting bioglass synthesis via sol-gel process; Biovidro osteocondutor sintetizado pelo processo sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, R.V.; Aragones, A.; Barra, G.O.M.; Salmoria, G.V.; Fredel, M.C., E-mail: rafaelavpereira@gmail.com [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

    2012-07-01

    The presence of bioglasses in scaffolds has been studied as they promote the osteoconduction in bones. The scaffolds are developed in order to induce the repair and regeneration in bone tissue. An absorbable bioglass from SiO2-CaO-P2O5 system was synthesized by sol-gel process with the intent of producing these scaffolds. Bioglass 58S was define for these work once it presents ions (Ca and P) which assist at the carbonated apatite layer formation when released. The apatite layer presents an important role at the bone regeneration and metabolism, being involved at grow and mineralization of bones. FTIR was realized to characterize the synthesized bioglass on its chemical composition, XRD to analyze the crystalline structure, solubility test to observe the weight variance and SEM to observe the particles morphology. The obtained results confirmed the production of a bioglass with the desired composition to produce osteoconducting scaffolds. (author)

  17. Synthesis of Titania-Silica Materials by Sol-Gel

    Directory of Open Access Journals (Sweden)

    Rubia F. S. Lenza

    2002-10-01

    Full Text Available In this work TiO2-SiO2 glasses containing as much as 20 mol % of TiO2 were prepared via sol-gel process using titanium and silicon alkoxides, in the presence of chlorine, in the form of titanium tetrachloride or HCl. The gels were heat-treated until 800 °C. X-ray diffraction and Fourier transform infrared spectroscopy were used to understand the structural properties of TiO2-SiO2 oxides calcined at different temperatures and to evaluate the homogeneity of these materials. The degree of the compactness of the silica network is inferred from the frequency of the asymmetric stretching vibrations of Si-O-Si bonds. Formation of Si-O-Ti bridges, as monitored by the intensity of characteristic 945 cm-1 ¾ 960 cm-1 vibration, is particularly prominent if the method of basic two-step prehydrolysis of silicon alkoxide, addition of titanium alkoxide and completion of hydrolysis was used.

  18. Synthesis of all-silica zeolites from highly concentrated gels containing hexamethonium cations

    KAUST Repository

    Liu, Xiaolong

    2012-07-01

    A pure and highly crystalline all-silica EU-1 zeolite has been obtained from the crystallization of gels containing very low water contents in the presence of hexamethonium cations. Decreasing the water content in the gel down to H 2O/Si < 1 inhibited the formation of ZSM-48, which is usually observed under more diluted standard crystallization conditions. Moreover, addition of NH 4F to the synthesis led to the formation of "half-fluorinated" ITQ-13 in which fluoride anions occupied only the center of D4R cages. In larger cages, the charge of the template was compensated by framework connectivity defects, clearly demonstrating once more the essential role of F - in the formation of D4R units. The formation of such hybrid (F,OH) is particularly interesting from a synthesis point of view, particularly for understanding the respective roles of fluoride and hydroxide anions in the crystallization process. © 2012 Elsevier Inc. All rights reserved.

  19. Colloidal sol-gel synthesis of oxides: application to the precursors of nuclear fuels

    International Nuclear Information System (INIS)

    Gossard, Alban

    2014-01-01

    One of the main objectives for the future nuclear fuel cycle is the recycling of the minor actinides. Different options are considered: their integration into a new fuel for a prospect of a closed fuel cycle or their transmutation in order to significantly decrease the long-term radiotoxicity of ultimate wastes. In both cases, the synthesis of new advanced materials integrating the actinides jointly is required. Sol-gel processes allow the organization of the material at the colloidal scale or the insertion of controlled porosity using 'templates'. Furthermore, the possibility to work in a 'wet environment' prevents the formation of pulverulent powders which are contaminant in the case of materials incorporating radioactive elements. The main purpose of this work is to demonstrate the adaptability of this route to the nuclear field. Firstly, a methodology of synthesis from a colloidal sol-gel route was set up on a non-radioactive zirconium-based system in order to characterize and understand of the different mechanisms of this synthesis. Then, studies on shaping, including insertion of porosity, were performed. Zirconia monoliths have been obtained thanks to a coupling between a colloidal sol-gel process and the formation of an emulsion stabilized by clusters of solid particles. Finally, a transposition of this work to an uranium-based system was introduced, pointing out different promising perspectives specially concerning the possibilities of shaping of the final material. (author) [fr

  20. Sol-Gel Synthesis of Phosphate-Based Glasses for Hydrophilic Enamel Applications

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae-Sung; Ryu, Bong-ki [Pusan National University, Busan (Korea, Republic of)

    2017-04-15

    In this study, quaternary phosphate-based sol-gel derived glasses were synthesized from a P{sub 2}O{sub 5}-CaO-Na{sub 2}O-TiO{sub 2} system with a high TiO{sub 2} content of up to 50 mol%. The sol-gel method was chosen because incorporating a high percentage of titanium into a phosphate network via traditional melt-quench methods is non-trivial. The structure and thermal properties of the obtained stabilized sol-gel glasses were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC). The XRD results confirmed the amorphous nature of all of the stabilized sol–gel derived glasses. The FTIR results revealed that added TiO{sub 2} enters the network as (TiO{sub 6}), which likely acts as a modifier oxide. Consequently, the number of terminal oxygen atoms increases, leading to an increase in the number of P-OH bonds. In addition, DSC results confirmed a decrease in glass transition and crystallization temperatures with increasing TiO{sub 2} content. This is the first report of a sol-gel synthesis strategy combined with enameling to prepare glass at low processing temperatures and the first use of such a system for both hydrophilic and chemical resistance purposes.

  1. Sol-Gel Synthesis of Phosphate-Based Glasses for Hydrophilic Enamel Applications

    International Nuclear Information System (INIS)

    Kim, Dae-Sung; Ryu, Bong-ki

    2017-01-01

    In this study, quaternary phosphate-based sol-gel derived glasses were synthesized from a P 2 O 5 -CaO-Na 2 O-TiO 2 system with a high TiO 2 content of up to 50 mol%. The sol-gel method was chosen because incorporating a high percentage of titanium into a phosphate network via traditional melt-quench methods is non-trivial. The structure and thermal properties of the obtained stabilized sol-gel glasses were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC). The XRD results confirmed the amorphous nature of all of the stabilized sol–gel derived glasses. The FTIR results revealed that added TiO 2 enters the network as (TiO 6 ), which likely acts as a modifier oxide. Consequently, the number of terminal oxygen atoms increases, leading to an increase in the number of P-OH bonds. In addition, DSC results confirmed a decrease in glass transition and crystallization temperatures with increasing TiO 2 content. This is the first report of a sol-gel synthesis strategy combined with enameling to prepare glass at low processing temperatures and the first use of such a system for both hydrophilic and chemical resistance purposes.

  2. Characterization of Silver Nanoparticle In Situ Synthesis on Porous Sericin Gel for Antibacterial Application

    Directory of Open Access Journals (Sweden)

    Gang Tao

    2016-01-01

    Full Text Available Sericin from Bombyx mori cocoon has good hydrophilicity, reaction activity, biocompatibility, and biodegradability, which has shown great potentials for biomedical materials. Here, an ultraviolet light-assisted in situ synthesis approach is developed to immobilize silver nanoparticles on the surface of sericin gel. The amount of silver nanoparticles immobilized on the surface of sericin gel could be regulated by the irradiation time. The porous structure and property of sericin gel were not affected by the modification of AgNPs, as evidenced by the observation of scanning electron microscopy, X-ray diffractometry, and Fourier transform infrared spectroscopy. Differential scanning calorimetry analysis showed that the modification of AgNPs increased the thermal stability of sericin gel. The growth curve of bacteria and inhibition zone assays suggested that the sericin gel modified with AgNPs had good antimicrobial activities against both Gram-negative and Gram-positive bacteria. This novel sericin has shown a great potential for biomedical purpose.

  3. Synthesis of gels with basis of titanium tungstates as matrixes of radioactive generators

    International Nuclear Information System (INIS)

    Galico C, L.

    2005-01-01

    The heteropolyanions, compounds formed by the union of molybdates or tungstates polyanions with atoms of metals like zirconium, titanium, cerium, thorium, tin, etc., have been used as generator matrixes of 99m Tc or 188 Re. Particularly they have been studied and produced successfully in our laboratory, generators of 99 Mo/ 99 m Tc at basis of gels zirconium molybdates and titanium molybdates. Considering that the molybdenum and tungsten, as well as the technetium and the rhenium, its belong to the same groups of transition metals, it is feasible that gels can be synthesized at basis of titanium tungstates, continuing a methodology similar to that of the gels titanium molybdates or zirconium molybdates, to produce generators 188 W/ 188 Re. The 188 Re possess nuclear characteristics that make it attractive for therapeutic applications, since, it emits β - particles of a great energy (2.12 MeV); joined to the possibility of being able to unite to different ligands (bifunctional agents) and biomolecules (antibodies or fragments of proteins), as it makes the 99m Tc, useful in radioimmunotherapy. Commercially the 188 Re generators use a chromatographic column loaded with alumina where the 188 Re, it is adsorbed and eluted the 188 ReO 4 - by means of a saline solution The alumina adsorbs around 0.2% of the 188 Re, situation that forces to use 188 Re of a high specific activity. The use of the gels technology, allows to work with medium or low specific activities of 188 Re, opening the possibility of their production in countries whose nuclear capacity is medium or low. In particular, the synthesized gels with basis of titanium offer the possibility of being synthesized with non active material, for later on to be irradiated and directly produce the generator, since, the titanium 51 Ti, unique radioisotope produced by the titanium, has a half life of 5.79 min. This synthesis method avoids the manipulation of radioactive material during the synthesis of the gels, process

  4. Fast and facile preparation of CTAB based gels and their applications in Au and Ag nanoparticles synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Ravi Kant, E-mail: rkupadhyay85@gmail.com [Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, 201314 Uttar Pradesh (India); Soin, Navneet, E-mail: n.soin@bolton.ac.uk [Knowledge Centre for Materials Chemistry (KCMC), Institute for Materials Research and Innovation (IMRI), University of Bolton, Deane Road, Bolton BL3 5AB (United Kingdom); Saha, Susmita, E-mail: ssaha@bose.res.in [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Barman, Anjan, E-mail: abarman@bose.res.in [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Sinha Roy, Susanta, E-mail: susanta.roy@snu.edu.in [Department of Physics, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, 201314 Uttar Pradesh (India)

    2015-04-15

    We have demonstrated that the gel-like mesophase of Cetyltrimethylammonium bromide (CTAB) can be synthesized by judicial adjustment of water to surfactant molar ratio (W{sub 0}), without using any additional salts, gelating agents or co-surfactants. Gel formation was found to be highly dependent on the water to surfactant molar ratio (W{sub 0}), with the lowest value of W{sub 0} (41.5) resulting in rapid gel formation. Environmental scanning electron microscope (ESEM) analysis revealed that the gel was comprised of interconnected cylindrical structures. The presence of hydrogen bonding in the gel-like mesophase was confirmed by Fourier Transform Infrared spectroscopy (FTIR) analysis. Rheology measurements revealed that all the gel samples were highly viscoelastic in nature. Furthermore, Au and Ag containing CTAB gels were explored as precursors for the preparation of spherical Gold (Au) and Silver (Ag) nanoparticles using Sodium borohydride (NaBH{sub 4}) as reducing agent. The effects of NaBH{sub 4} concentration on the particle size and morphology of the Au and Ag nanoparticles have also been studied. - Highlights: • A facile synthesis of CTAB based gel-like mesophase is reported. • CTAB gels were obtained by adjusting water to surfactant molar ratio (W{sub 0}). • FTIR analysis revealed that hydrogen bonding plays a key role in gel formation. • Au, Ag nanoparticles were synthesized by using CTAB gel and NaBH{sub 4}.

  5. Synthesis of Single-walled Carbon Nanotubes Coated with Thiol-reactive Gel via Emulsion Polymerization.

    Science.gov (United States)

    Nagai, Yukiko; Tsutsumi, Yusuke; Nakashima, Naotoshi; Fujigaya, Tsuyohiko

    2018-06-15

    Single-walled carbon nanotubes (SWNTs) have unique near-infrared absorption and photoemission properties that are attractive for in vivo biological applications such as photothermal cancer treatment and bioimaging. Therefore, a smart functionalization strategy for SWNTs to create biocompatible surfaces and introduce various ligands to target active cancer cells without losing the unique optical properties of the SWNTs is strongly desired. This paper reports the de-sign and synthesis of a SWNT/gel hybrid containing maleimide groups, which react with various thiol compounds through Michael addition reactions. In this hybrid, the method called carbon nanotube micelle polymerization was used to non-covalently modify the surface of SWNTs with a cross-linked polymer gel layer. This method can form an extremely stable gel layer on SWNTs; such stability is essential for in vivo biological applications. The monomer used to form the gel layer contained a maleimide group, which was protected with furan in endo-form. The resulting hybrid was treated in water to induce deprotection via retro Diels-Alder reaction and then functionalized with thiol com-pounds through Michael addition. The functionalization of the hybrid was explored using a thiol-containing fluores-cent dye as a model thiol and the formation of the SWNT-dye conjugate was confirmed by energy transfer from the dye to SWNTs. Our strategy offers a promising SWNT-based platform for biological functionalization for cancer targeting, imaging, and treatment.

  6. Binding Cellulose and Chitosan via Intermolecular Inclusion Interaction: Synthesis and Characterisation of Gel

    Directory of Open Access Journals (Sweden)

    Jiufang Duan

    2015-01-01

    Full Text Available A novel cellulose-chitosan gel was successfully prepared in three steps: (1 ferrocene- (Fc- cellulose with degrees of substitution (DS of 0.5 wt% was synthesised by ferrocenecarboxylic acid and cellulose within dimethylacetamide/lithium chloride (DMAc/LiCl; (2 the β-cyclodextrin (β-CD groups were introduced onto the chitosan chains by reacting chitosan with epichlorohydrin in dimethyl sulphoxide and a DS of 0.35 wt%; (3 thus, the cellulose-chitosan gel was obtained via an intermolecular inclusion interaction of Fc-cellulose and β-CD-chitosan in DMA/LiCl, that is, by an intermolecular inclusion interaction, between the Fc groups of cellulose and the β-CD groups on the chitosan backbone at room temperature. The successful synthesis of Fc-cellulose and β-CD-chitosan was characterised by 13C-NMR spectroscopy. The gel based on β-CD-chitosan and Fc-cellulose was formed under mild conditions which can engender autonomous healing between cut surfaces after 24 hours: the gel cannot self-heal while the cut surfaces were coated with a solution of a competitive guest (adamantane acid. The cellulose-chitosan complex made by this method underwent self-healing. Therefore, this study provided a novel method of expanding the application of chitosan by binding it with another polymer.

  7. Mechanisms of polyphosphate glucokinase and polyphosphate kinase reactions

    International Nuclear Information System (INIS)

    Pepin, C.A.; Robinson, N.A.; Wood, H.G.

    1986-01-01

    Polyphosphate glucokinase [poly(P)GK] catalyzes the following reaction: poly(P)/sub n/ + glucose → poly(P)/sub n-1/ + G-6-P. With long chain poly(P) [n=750 to 400] the mechanism appeared to be processive, in which there is phosphorylation of glucose without release of intermediate sizes of the poly(P) until the chain is about 100, thereafter there were intermediate sizes formed apparently by a non-processive process. Poly(P) kinase catalyzes the following reaction: ATP + poly(P)/sub n/ ↔ ADP + poly(P)/sub n + 1/. Using short chain 32 [P] poly(P) as a primer and non-radioactive ATP, long chain poly(P) is formed processively. The resulting chain has a short length labeled with 32 [P] contributed by the primer on one end and the remainder is made up of unlabeled (P) from the ATP. The authors have used this 32 [P] poly(P) as a substrate with poly(P)GK. If the mechanism of the poly(P)GK were initially processive, there would be a 50% chance the phosphate would be utilized from the unlabeled end and 50% of the 32 [P] would remain in the shortened chain. However, all the 32 [P] was lost when 20% of the poly(P) was converted to G-6-P. In contrast, with poly(P) kinase, the % of poly(P) utilized was equivalent to the % of 32 [P] converted to ATP, which is consistent with a strictly processive mechanism. Even though the mechanism of poly(P)GK appeared to be processive with long chains, the on and off rate of poly(P) from the enzyme is such that there is random removal of (P) from both ends of the poly(P) chain

  8. Synthesis and luminescent properties of trivalent rare-earth (Eu{sup 3+}, Tb{sup 3+}) ions doped nanocrystalline AgLa(PO{sub 3}){sub 4} polyphosphates

    Energy Technology Data Exchange (ETDEWEB)

    Krishna Bharat, L.; Jeon, Yong Il; Yu, Jae Su, E-mail: jsyu@khu.ac.kr

    2014-11-25

    Highlights: • AgLa(PO{sub 3}){sub 4}:Eu{sup 3+}, Tb{sup 3+} nanocrystalline phosphors were prepared by a sol–gel process. • The luminescent properties were studies by near-UV excitation. • The intense MD transition indicates the presence of high inversion symmetry site. • These results suggest that the compound is a good candidate for optical applications. - Abstract: The AgLa(PO{sub 3}){sub 4} phosphors activated with trivalent rare-earth (Eu{sup 3+}, Tb{sup 3+}) ions were prepared by a sol–gel synthesis method. The crystal structure of the compound was studied by X-ray diffraction patterns and found to be crystallized in the monoclinic system with a space group P2{sub 1}/c, indicating the calculated lattice parameters of a = 10.08 Å, b = 13.12 Å, and c = 7.314 Å. The Fourier-transform infrared spectrum, photoluminescence excitation/emission spectra, and decay curves were examined to study the optical properties. The analysis of the Eu{sup 3+} ions related emission spectrum revealed the presence of highly symmetric sites for the activator ions. The Tb{sup 3+} ions related emission spectrum exhibited a {sup 5}D{sub 3} emission due to the prolonged calcination at high temperatures, which reduces the residual hydroxyl ions. The optical properties show that this host material is suitable for phosphor materials and laser crystals.

  9. Synthesis and sintering of nanocrystalline hydroxyapatite powders by citric acid sol-gel combustion method

    International Nuclear Information System (INIS)

    Han Yingchao; Li Shipu; Wang Xinyu; Chen Xiaoming

    2004-01-01

    The citric acid sol-gel combustion method has been used for the synthesis of nanocrystalline hydroxyapatite (HAP) powder from calcium nitrate, diammonium hydrogen phosphate and citric acid. The phase composition of HAP powder was characterized by X-ray powder diffraction analysis (XRD). The morphology of HAP powder was observed by transmission electron microscope (TEM). The HAP powder has been sintered into microporous ceramic in air at 1200 deg. C with 3 h soaking time. The microstructure and phase composition of the resulting HAP ceramic were characterized by scanning electron microscope (SEM) and XRD, respectively. The physical characterization of open porosity and flexural strength have also been carried out

  10. Synthesis of hybrid sol-gel coatings for corrosion protection of we54-ae magnesium alloy

    International Nuclear Information System (INIS)

    Hernández-Barrios, C A; Peña, D Y; Coy, A E; Duarte, N Z; Hernández, L M; Viejo, F

    2013-01-01

    The present work shows some preliminary results related to the synthesis, characterization and corrosion evaluation of different hybrid sol-gel coatings applied on the WE54-AE magnesium alloy attending to the two experimental variables, i.e. the precursors ratio and the aging time, which may affect the quality and the electrochemical properties of the coatings resultant. The experimental results confirmed that, under some specific experimental conditions, it was possible to obtain homogeneous and uniform, porous coatings with good corrosion resistance that also permit to accommodate corrosion inhibitors

  11. Synthesis of Copper-Based Transparent Conductive Oxides with Delafossite Structure via Sol-Gel Processing

    OpenAIRE

    Götzendörfer, Stefan

    2011-01-01

    Starting off with solubility experiments of possible precursors, the present study reveals the whole development of a sol gel processing route for transparent p type semiconductive thin films with delafossite structure right to the fabrication of functional p-n junctions. The versatile sol formulation could successfully be modified for several oxide compositions, enabling the synthesis of CuAlO2, CuCrO2, CuMnO2, CuFeO2 and more. Although several differences in the sintering behaviour of powde...

  12. Immobilization of bromelain protease on PVA gels for the oligopeptides synthesis

    International Nuclear Information System (INIS)

    Fagundes, Fabio P.; Madruga, Liszt Y.C.; Balaban, Rosangela de C.; Costa, Marta

    2015-01-01

    Enzymatic synthesis of peptides using proteases has attracted a great deal of attention in recent years. One key challenge in peptide synthesis is to find supports for protease immobilization capable of working in aqueous medium at high performance, producing water-soluble oligopeptides. Therefore, the aim of this paper was to immobilize the bromelain protease by Freezing / thawing method on polymeric gels of Poli (vinyl alcohol) in order to produce water-soluble oligopeptides derived from lysine. Calculations of oligolysine yield and average degree of polymerization (DPavg) were monitored by 1 H-NMR analysis. Scanning Electronic Micrograph (SEM) was responsible to associate to the porous size with performance of each system during the production of oligopeptides from lysine. These systems produced oligomers in only 1 hour with DPavg higher than free bromelain. (author)

  13. Combined sol–gel and carbothermal synthesis of ZrC–TiC powders for composites

    Energy Technology Data Exchange (ETDEWEB)

    Umalas, Madis [Institute of Physics, University of Tartu, Riia 142, 51014, Tartu (Estonia); Estonian Nanotechnology Competence Centre, Riia 142, 51014, Tartu (Estonia); Hussainova, Irina, E-mail: irina.hussainova@ttu.ee [Department of Materials Engineering, Tallinn University of Technology, Ehitajate 5, 19086, Tallinn (Estonia); ITMO University, Kronverksky 49, St. Petersburg, 197101 (Russian Federation); Reedo, Valter [Institute of Physics, University of Tartu, Riia 142, 51014, Tartu (Estonia); Young, Der-Liang [Department of Materials Engineering, Tallinn University of Technology, Ehitajate 5, 19086, Tallinn (Estonia); Cura, Erkin; Hannula, Simo-Pekka [Department of Materials Science and Engineering, Aalto University, School of Chemical Technology, POB 16200, Aalto, 00076 (Finland); Lõhmus, Rünno [Institute of Physics, University of Tartu, Riia 142, 51014, Tartu (Estonia); Estonian Nanotechnology Competence Centre, Riia 142, 51014, Tartu (Estonia); Lõhmus, Ants [Institute of Physics, University of Tartu, Riia 142, 51014, Tartu (Estonia)

    2015-03-01

    The TiC–ZrC binary compound of nanostructured powders was synthesised by combination of sol–gel and carbothermal reduction. The polymeric precursor of the blend was produced by sol–gel process from titanium tetrabutoxide, zirconium tetrabutoxide and benzene-1.4-diol; then carbothermally reduced to the TiC–ZrC blend at 1600 °C in an inert environment. The chemical reactions occurring in the system were monitored by infrared spectrometry. Stable alkoxide solution was obtained by adding acetylacetone to avoid premature gelation of the metal alkoxide mixture. A solid solution of ZrTiC{sub 2} was produced by spark plasma sintering at temperature of 2000 °C. - Highlights: • A polymeric precursor of TiC–ZrC blend was synthesised by sol–gel process. • The polymeric precursor synthesis was studied by infrared spectroscopy. • TiC–ZrC powder blend was carbothermally reduced from polymeric precursor. • TiC–ZrC powder blend was sintered to ZrTiC{sub 2} solid solution by spark plasma sintering. • Sintered ZrTiC{sub 2} have good mechanical properties.

  14. Combined sol–gel and carbothermal synthesis of ZrC–TiC powders for composites

    International Nuclear Information System (INIS)

    Umalas, Madis; Hussainova, Irina; Reedo, Valter; Young, Der-Liang; Cura, Erkin; Hannula, Simo-Pekka; Lõhmus, Rünno; Lõhmus, Ants

    2015-01-01

    The TiC–ZrC binary compound of nanostructured powders was synthesised by combination of sol–gel and carbothermal reduction. The polymeric precursor of the blend was produced by sol–gel process from titanium tetrabutoxide, zirconium tetrabutoxide and benzene-1.4-diol; then carbothermally reduced to the TiC–ZrC blend at 1600 °C in an inert environment. The chemical reactions occurring in the system were monitored by infrared spectrometry. Stable alkoxide solution was obtained by adding acetylacetone to avoid premature gelation of the metal alkoxide mixture. A solid solution of ZrTiC 2 was produced by spark plasma sintering at temperature of 2000 °C. - Highlights: • A polymeric precursor of TiC–ZrC blend was synthesised by sol–gel process. • The polymeric precursor synthesis was studied by infrared spectroscopy. • TiC–ZrC powder blend was carbothermally reduced from polymeric precursor. • TiC–ZrC powder blend was sintered to ZrTiC 2 solid solution by spark plasma sintering. • Sintered ZrTiC 2 have good mechanical properties

  15. Sol-gel synthesis and densification of aluminoborosilicate powders. Part 2: Densification

    Science.gov (United States)

    Bull, Jeffrey; Selvaduray, Guna; Leiser, Daniel

    1992-01-01

    Aluminoborosilicate (ABS) powders, high in alumina content, were synthesized by the sol-gel process utilizing four different methods of synthesis. The effect of these methods on the densification behavior of ABS powder compacts was studied. Five regions of shrinkage in the temperature range 25-1184 C were identified. In these regions, the greatest shrinkage occurred between the gel-to-glass transition temperature (T sub g approximately equal to 835 C) and the crystallization transformation temperature (T sub t approximately equal 900 C). The dominant mechanism of densification in this range was found to be viscous sintering. ABS powders were amorphous to x-rays up to T sub t at which a multiphasic structure crystallized. No 2Al2O3.B2O3 was found in these powders as predicted in the phase diagram. Above T sub t, densification was the result of competing mechanisms including grain growth and boria fluxed viscous sintering. Apparent activation energies for densification in each region varied according to the method of synthesis.

  16. Synthesis and application of silica gel modified with alkoxyalcohols. Alkoxyalcohol shushoku silica gel no gosei to riyo

    Energy Technology Data Exchange (ETDEWEB)

    Moriguchi, T.; Ishiguro, H.; Matsubara, Y.; Yoshihara, M.; Maeshima, T.; Ito, S. (Kinki University, Osaka (Japan). Faculty of Science and Engineering)

    1991-08-20

    Several kinds of silica gel modified by alkoxyalcohols were synthesized by refluxing and dehyration and the organic reactions were studied when these silica gels were used as the catalyst. It could be confirmed by FT-IR spectra, DTA and elementary analysis that alkoxylalcohols adhere to the surface of silica gels without any decomposition. The acetate was produced by using alkyl halides. It was found that the modified silica gels had clearly the catalytic action for the reaction with n-hexyl bromide and dibromoethane although unmodified silica gels did not show the catalytic action. The reducing reaction of carbonyl compounds was carried out. The reaction proceeded at 25 centigrade for acetophenone, cyclohexanone, 1-indanone and 2-octanone to produce the corresponding reduction products. 11 refs., 5 figs., 4 tabs.

  17. Room-temperature sol–gel synthesis of organic ligand-capped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zobel, Mirijam, E-mail: mirijam.zobel@fau.de; Chatterjee, Haimantee [Friedrich-Alexander University Erlangen-Nürnberg (FAU), Department of Physics, Lehrstuhl für Kristallographie und Strukturphysik (Germany); Matveeva, Galina; Kolb, Ute [Johannes Gutenberg-Universität, Institut für Physikalische Chemie (Germany); Neder, Reinhard B., E-mail: reinhard.neder@fau.de [Friedrich-Alexander University Erlangen-Nürnberg (FAU), Department of Physics, Lehrstuhl für Kristallographie und Strukturphysik (Germany)

    2015-05-15

    Powders of zinc oxide nanoparticles with individual particle sizes below 10 nm in diameter are readily produced in base-induced sol–gel processes from ethanolic solutions of zinc acetate dihydrate. These particles are covered with acetate molecules and without further stabilization, they grow when stored as a powder. Here, we present three organic ligands, which reproducibly stabilize individual particle sizes <5 nm within the agglomerated powders for extended periods of time, up to months. Citric acid and 1,5-diphenyl-1,3,5-pentanetrione result in average diameters of 3 nm, whereas dimethyl-L-tartrate stabilizes 2.1 nm. X-ray diffraction and pair distribution function analysis were used to investigate the structural properties of the particles. TEM data confirm the individual particle size and crystallinity and show that the particles are agglomerated without structural coherence. Besides the introduction of these novel ligands for ZnO nanoparticles, we investigated, in particular, the influence of each synthesis step onto the final nanoparticle size in the powder. Previous studies often reported the employed synthesis parameters, but did not motivate the reasoning for their choice based on detailed experimental observations. Herein, we regard separately the steps of (i) the synthesis of the colloids, (ii) their precipitation, and (iii) the drying of the resulting gel to understand the role of the ligands therein. ZnO particles only covered with acetate grow to 5 nm during the drying process, whereas particles with any of the additional ligands retain their colloidal size of 2–3 nm. This clearly shows the efficient binding and effect of the presented ligands.

  18. Synthesis of mesoporous silica nanoparticles by sol–gel as nanocontainer for future drug delivery applications

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez, N.I.; Gonzalez, Z.; Ferrari, B.; Castro, Y.

    2017-07-01

    Development of mesoporous silica nanoparticles as carriers for drug delivery systems has increased exponentially during the last decade. The present work is focused on the synthesis of silica carriers by sol–gel from tetraethyl orthosilicate (TEOS) as precursor of silica and cetyltrimethylammonium bromide (CTAB) as pore generating agent. The synthesis conditions were modified varying the molar ratio of water/TEOS, NH3/TEOS and amount of CTAB. The silica particles were characterized by scan electron microscopy techniques (FESEM), high resolution transmission electron microscopy (HR-TEM), N2 adsorption–desorption isotherms, Zeta-potential and Dynamic Light Scattering (DLS). The results show that the specific surface area and the porosity of silica particles were strongly affected by the addition of CTAB and the amount of H2O. The dispersion and stability of silica mesoporous particles is achieved in spite of the high surface reactivity. The synthesis formulation affects considerably to the particle morphology, which changes from spheres to rods when the molar ratio of H2O increases. A maximum specific surface area of 1480m2/g was obtained with pore sizes ranging 2.5–2.8nm. (Author)

  19. Sol–gel one-pot synthesis in soft conditions of mesoporous silica materials ready for drug delivery system

    NARCIS (Netherlands)

    Tourne-Peteilh, C.; Begu, S.; Lerner, D.A.; Galarneau, A.; Lafont, U.; Devoiselle, J.M.

    2011-01-01

    The present work reveals a new and simple strategy, a one-step sol–gel procedure, to encapsulate a low water-soluble drug in silica mesostructured microparticles and to improve its release in physiological media. The synthesis of these new materials is based on the efficient solubilisation of a

  20. Role of a waste-derived polymeric biosurfactant in the sol-gel synthesis of nanocrystalline titanium dioxide

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Perrone, Daniele G.; Magnacca, Giuliana

    2014-01-01

    An inexpensive polymeric biosurfactant isolated from urban bio-wastes is shown to be a useful chemical aid in the synthesis of nanostructured materials with tunable pore size and surface hydrophilicity. Photocatalytic active TiO2 powders were prepared by sol–gel reaction in the presence of variable...

  1. Synthesis of In2O3nanoparticles by thermal decomposition of a citrate gel precursor

    International Nuclear Information System (INIS)

    Rey, J. F. Q.; Plivelic, T. S.; Rocha, R. A.; Tadokoro, S. K.; Torriani, I.; Muccillo, E. N. S.

    2005-01-01

    This paper describes the synthesis of indium oxide by a modified sol-gel method, and the study of thermal decomposition of the metal complex in air. The characterization of the intermediate as well as the final compounds was carried out by thermogravimetry, differential thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and small angle X-ray scattering. The results show that the indium complex decomposes to In 2 O 3 with the formation of an intermediate compound. Nanoparticles of cubic In 2 O 3 with crystallite sizes in the nanosize range were formed after calcination at temperatures up to 900 deg. C. Calcined materials are characterized by a polydisperse distribution of spherical particles with sharp and smooth surfaces

  2. Silica-gel Catalyzed Facile Synthesis of 3,4-Dihydropyrimidinones

    International Nuclear Information System (INIS)

    Agarwal, Sameer; Aware, Umesh; Patil, Amit; Rohera, Vinita; Jain, Mukul; Patel, Pankaj; Ghate, Manjunath

    2012-01-01

    We have developed a mild and highly effective procedure for the one-pot synthesis of substituted dihydropyrimidinones in high yields using silica gel as a green, highly efficient and recyclable heterogeneous catalyst. Our approach can be applied to the preparation of a wide range of synthetic analogues for structure-activity studies. Investigations in this direction are ongoing. The pyrimidinone ring is a basic substructure of numerous biologically active alkaloids and pharmaceutical products. These cores are regarded as one of the most important groups of drug-like scaffolds. 3,4-dihydropyrimidinones above are known to exhibit variety of pharmacological activity such as calcium channel modulation, mitotic kinesin Eg5 inhibition, antiviral, anti-inflammatory, antibacterial activity, etc

  3. Silica-gel Catalyzed Facile Synthesis of 3,4-Dihydropyrimidinones

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, Sameer; Aware, Umesh; Patil, Amit; Rohera, Vinita; Jain, Mukul; Patel, Pankaj [Zydus Research Centre, Sarkhej-Bavla N.H., Ahmedabad (India); Ghate, Manjunath [Nirma University, Ahmedabad (India)

    2012-02-15

    We have developed a mild and highly effective procedure for the one-pot synthesis of substituted dihydropyrimidinones in high yields using silica gel as a green, highly efficient and recyclable heterogeneous catalyst. Our approach can be applied to the preparation of a wide range of synthetic analogues for structure-activity studies. Investigations in this direction are ongoing. The pyrimidinone ring is a basic substructure of numerous biologically active alkaloids and pharmaceutical products. These cores are regarded as one of the most important groups of drug-like scaffolds. 3,4-dihydropyrimidinones above are known to exhibit variety of pharmacological activity such as calcium channel modulation, mitotic kinesin Eg5 inhibition, antiviral, anti-inflammatory, antibacterial activity, etc.

  4. Synthesis and characterization of silver nanoparticles by sol-gel route from silver nitrate

    International Nuclear Information System (INIS)

    Morales, Jorge; Moran, Jose; Quintana, Maria; Estrada, Walter

    2009-01-01

    Silver nanoparticles colloids have been synthesized by sol-gel method. This synthesis consists in silver nitrate reduction by ethylene glycol in a process called polyol. The growth of the nanoparticles have been controlled by the steric stabilization of the colloid with polyvinylpyrrolidone (PVP, M w = 40 000). The silver nanoparticle size and structure was depending on the control of parameters such as: molar concentrations ratio of silver nitrate and PVP, temperature of reaction and the reflux time. Colloids have been characterized by UV-vis spectroscopy in the range from 300 to 1000 nm. The results show that the typical peak of surface plasmon resonance is formed at 400-450 nm indicating the formation of silver nanoparticles. The presences of silver nanoparticles of spherical shape with size among 20-40 nm were observed by transmission electronic microscopy (TEM). Electron diffraction patterns confirmed that synthesized colloids contain metallic silver with a crystal structure face centered cubic FCC. (author)

  5. Low temperature synthesis of hydroxyapatite nano-rods by a modified sol-gel technique

    International Nuclear Information System (INIS)

    Jadalannagari, Sushma; More, Sandeep; Kowshik, Meenal; Ramanan, Sutapa Roy

    2011-01-01

    Hydroxyapatite (HAp) nano-rods were successfully synthesized by a modified sol-gel method using a solution of CaCl 2 .2H 2 O in water, along with a solution of H 3 PO 4 in triethylamine and NH 4 OH as starting materials. The Ca/P molar ratio was maintained at 1.67. The sol obtained was dried in an oven for 2 days at 100 deg. C after being dialyzed for 12 h. Pellets were made from the crystalline powders and immersed in simulated body fluid (SBF) to check its biocompatibility after 15, 45 and 180 days of immersion. The HAp powders and pellets were characterized by X-Ray Diffraction crystallography (XRD), Fourier transform Infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The HAp nano-rods had an average diameter of 25 nm and length 110-120 nm. Immersion of the HAp pellets in SBF led to the formation of a highly porous interconnecting HAp layer on the surface. The porosity increased with increase in immersion time. Highlights: → Low temperature synthesis of hydroxyapatite nanorods using Ca and P sources and triethylamine. → The synthesis time was only 0.5 hours. → Crystalline material was obtained after drying at 100oC only in air. → SBF studies showed the HAP bodies to be biocompatible.

  6. Effect of reaction solvent on hydroxyapatite synthesis in sol-gel process

    Science.gov (United States)

    Nazeer, Muhammad Anwaar; Yilgor, Emel; Yagci, Mustafa Baris; Unal, Ugur; Yilgor, Iskender

    2017-12-01

    Synthesis of hydroxyapatite (HA) through sol-gel process in different solvent systems is reported. Calcium nitrate tetrahydrate (CNTH) and diammonium hydrogen phosphate (DAHP) were used as calcium and phosphorus precursors, respectively. Three different synthesis reactions were carried out by changing the solvent media, while keeping all other process parameters constant. A measure of 0.5 M aqueous DAHP solution was used in all reactions while CNTH was dissolved in distilled water, tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) at a concentration of 0.5 M. Ammonia solution (28-30%) was used to maintain the pH of the reaction mixtures in the 10-12 range. All reactions were carried out at 40 ± 2°C for 4 h. Upon completion of the reactions, products were filtered, washed and calcined at 500°C for 2 h. It was clearly demonstrated through various techniques that the dielectric constant and polarity of the solvent mixture strongly influence the chemical structure and morphological properties of calcium phosphate synthesized. Water-based reaction medium, with highest dielectric constant, mainly produced β-calcium pyrophosphate (β-CPF) with a minor amount of HA. DMF/water system yielded HA as the major phase with a very minor amount of β-CPF. THF/water solvent system with the lowest dielectric constant resulted in the formation of pure HA.

  7. The Role of Inorganic Polyphosphates in the Formation of Bioengineered Cartilage Incorporating a Zone of Calcified Cartilage In Vitro

    Science.gov (United States)

    St-Pierre, Jean-Philippe

    The development of bioengineered cartilage for replacement of damaged articular cartilage has gained momentum in recent years. One such approach has been developed in the Kandel lab, whereby cartilage is formed by seeding primary articular chondrocytes on the top surface of a porous biodegradable calcium polyphosphate (CPP) bone substitute, permitting anchorage of the tissue within the pores of the substrate; however, the interfacial shear properties of the tissue-substrate interface of these biphasic constructs are 1 to 2 orders of magnitude lower than the native cartilage-subchondral bone interface. To overcome this limitation, a strategy was devised to generate a zone of calcified cartilage (ZCC), thereby mimicking the native architecture of the osteochondral junction; however, the ZCC was located slightly above the cartilage-CPP interface. Thus, it was hypothesized that polyphosphate released from the CPP substrate and accumulating in the tissue inhibits the formation of the ZCC at the tissue-substrate interface. Based on this information, a strategy was devised to generate biphasic constructs incorporating a properly located ZCC. This approach involved the application of a thin calcium phosphate film to the surfaces of porous CPP via a sol-gel procedure, thereby limiting the accumulation of polyphosphate in the cartilaginous tissue. This modification to the substrate surface did not negatively impact the quality of the in vitro-formed cartilage tissue or the ZCC. Interfacial shear testing of biphasic constructs demonstrated significantly improved interfacial shear properties in the presence of a properly located ZCC. These studies also led to the observation that chondrocytes produce endogenous polyphosphate and that its levels in deep zone cartilage appear inversely related to mineral deposition within the tissue. Using an in vitro model of cartilage calcification, it was demonstrated that polyphosphate levels are modulated in part by the inhibitory effects

  8. Sol-gel synthesis and characterisation of nano-scale hydroxyapatite

    International Nuclear Information System (INIS)

    Bilton, M; Brown, A P; Milne, S J

    2010-01-01

    Hydroxyapatite (HAp) forms the main mineral component of bone and teeth. This naturally occurring HAp is in the form of nano-metre sized crystallites of Ca 10 (PO 4 ) 6 (OH) 2 that contain a number of cation and anion impurities, for example CO 3 2- , F - , Na + , Mg 2+ and Sr 2+ . Synthetic nano-sized HAp particles exhibit favourable biocompatibility and bioactivity and in order to better match the composition to natural HAp there is great interest in producing a range of chemically modified powders. In this study, two HAp powders have been synthesised via a water-based low-temperature sol-gel method and a third, commercial powder from Sigma-Aldrich have been analysed. Subsequent powder calcination has been carried out within the temperature range of 500-700 0 C and the products characterised by bulk chemical analysis, X-ray diffraction and electron microscopy. Energy dispersive X-ray spectroscopy (EDX) in the TEM has been used to assess the composition of individual HAp particles. In order to do this accurately it is first necessary to account for the sensitivity of the HAp structure and composition to irradiation by the high energy electron beam of the TEM. This was done by monitoring the estimated Ca/P ratio derived from TEM-EDX of stoichiometric HAp under increasing levels of electron fluence. A fluence threshold (at a given beam energy) was established below which the measured Ca/P ratio can be considered to be stable. Subsequent elemental analysis at or below this threshold has enabled the variation in composition between particles both within and between synthesis batches to be accurately assessed. Compositional variability between particles is also evident, even in the commercial powder, but is far greater in the powders prepared by the sol-gel method.

  9. Polyphosphate formation in Chlorella in relation to photosynthesis

    NARCIS (Netherlands)

    Wintermans, J.F.G.M.

    1955-01-01

    Suspensions of Chlorella converted orthophosphate into cellular phosphate in the light, especially in the absence of C0 2 , when orthophosphate was largely transformed into polyphosphate. Polyphosphate formation continued for several hours, slowly decreasing, and was saturated at

  10. Proteic sol-gel synthesis of copper doped misfit Ca-cobaltites with potential SOFC application

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Chrystian G.M. [Materials Science and Engineering Postgraduate Program, UFPB, 58051-900, João Pessoa (Brazil); Silva, Rinaldo M. [Department of Chemical Engineering, UFPB, 58051-900, João Pessoa (Brazil); Aquino, Flávia de M. [Alternative and Renewable Energy Center, UFPB, 58051-900, João Pessoa (Brazil); Raveau, Bernard; Caignaert, Vincent [Laboratoire CRISMAT ENSICAEN UMR CNRS 6508, 6 Boulevard du Maréchal Juin, 14050, Caen Cedex 04 (France); Cesário, Moisés R., E-mail: moises.cesario@ensicaen.fr [Laboratoire CRISMAT ENSICAEN UMR CNRS 6508, 6 Boulevard du Maréchal Juin, 14050, Caen Cedex 04 (France); Macedo, Daniel A., E-mail: damaced@gmail.com [Materials Science and Engineering Postgraduate Program, UFPB, 58051-900, João Pessoa (Brazil)

    2017-02-01

    The present work reports the synthesis, structure and electrochemical assessment of Cu-doped calcium cobaltites as cathode materials for solid oxide fuel cells (SOFCs). Powders of composition Ca{sub 3−x}Cu{sub x}Co{sub 4}O{sub 9−δ} (0 ≤ x ≤ 0.2) were obtained by a proteic sol-gel method which uses gelatin as polymerizing agent. As-prepared materials were calcined at 900 °C for 1 h and characterized by X-ray diffraction, with Rietveld refinement of the diffraction data, and scanning electron microscopy. Screen-printed porous electrodes fired (at 950 °C for 2 h) on both faces of ceria based electrolytes were electrochemically characterized by impedance spectroscopy between 600 and 800 °C in air atmosphere. The results indicated the attainment of Ca{sub 3−x}Cu{sub x}Co{sub 4}O{sub 9−δ} solid solutions with monoclinic misfit layered structure and around 2 vol% Co{sub 3}O{sub 4} as a secondary phase. Micro-plates like powders had irregular shape and average diameter near 2 μm. The area specific resistance (ASR) is in line with literature data for cathodes of similar compositions prepared by other synthetic routes. ASR was optimized for the composition Ca{sub 2.99}Cu{sub 0.01}Co{sub 4}O{sub 9−δ}, achieving 0.84 Ω cm{sup 2} at 800 °C in air. - Highlights: • Proteic sol-gel synthesis of Ca{sub 3−x}Cu{sub x}Co{sub 4}O{sub 9−δ} (0 ≤ x ≤ 0.2). • Cu{sup 2+} doping enhances electrode densification. • Area specific resistance (ASR = 0.84 Ω cm{sup 2} at 800 °C) optimized for Ca{sub 2.99}Cu{sub 0.01}Co{sub 4}O{sub 9−δ}.

  11. New synthesis parameters of GGG:Nd nanocrystalline powder prepared by sol–gel method: Structural and spectroscopic investigation

    Energy Technology Data Exchange (ETDEWEB)

    Alshikh Mohamad, Yassin, E-mail: yassinm@mail.ru; Atassi, Yomen; Moussa, Zafer

    2015-09-15

    GGG:Nd nanopowder is synthesized by the sol–gel method using formic acid and acetic acid as chelating agents and ethylene glycol as a cross linking agent. TGA–DSC, XRD, photoluminescence spectroscopy and fluorescence life time analysis (τ) are used to characterize the powder. XRD is used to optimize the synthesis parameters. According to XRD, complete phase of GGG nanopowder is formed at 800 °C for 1 min. Fluorescence life time analyses reveal that the optimum crystallization temperature is 1000 °C. - Highlights: • GGG:Nd nanopowder was prepared using formic acid by the sol gel method. • Optimization of sol gel parameters was done. • GGG phase formation was complete at 800 °C for 1 min • According to τ measurements, optimal temperature treatment is at 1000 °C. • Nanopowder prepared with formic acid was better than that formed with acetic acid.

  12. Vapour-phase method in the synthesis of polymer-ibuprofen sodium-silica gel composites.

    Science.gov (United States)

    Kierys, Agnieszka; Krasucka, Patrycja; Grochowicz, Marta

    2017-11-01

    The study discusses the synthesis of polymer-silica composites comprising water soluble drug (ibuprofen sodium, IBS). The polymers selected for this study were poly(TRIM) and poly(HEMA- co -TRIM) produced in the form of permanently porous beads via the suspension-emulsion polymerization method. The acid and base set ternary composites were prepared by the saturation of the solid dispersions of drug (poly(TRIM)-IBS and/or poly(HEMA- co -TRIM)-IBS) with TEOS, and followed by their exposition to the vapour mixture of water and ammonia, or water and hydrochloric acid, at autogenous pressure. The conducted analyses reveal that the internal structure and total porosity of the resulting composites strongly depend on the catalyst which was used for silica precursor gelation. The parameters characterizing the porosity of both of the acid set composites are much lower than the parameters of the base set composites. Moreover, the basic catalyst supplied in the vapour phase does not affect the ibuprofen sodium molecules, whereas the acid one causes transformation of the ibuprofen sodium into the sodium chloride and a derivative of propanoic acid, which is poorly water soluble. The release profiles of ibuprofen sodium from composites demonstrate that there are differences in the rate and efficiency of drug desorption from them. They are mainly affected by the chemical character of the polymeric carrier but are also associated with the restricted swelling of the composites in the buffer solution after precipitation of silica gel.

  13. Vapour-phase method in the synthesis of polymer-ibuprofen sodium-silica gel composites

    Directory of Open Access Journals (Sweden)

    Agnieszka Kierys

    2017-11-01

    Full Text Available The study discusses the synthesis of polymer-silica composites comprising water soluble drug (ibuprofen sodium, IBS. The polymers selected for this study were poly(TRIM and poly(HEMA-co-TRIM produced in the form of permanently porous beads via the suspension-emulsion polymerization method. The acid and base set ternary composites were prepared by the saturation of the solid dispersions of drug (poly(TRIM-IBS and/or poly(HEMA-co-TRIM-IBS with TEOS, and followed by their exposition to the vapour mixture of water and ammonia, or water and hydrochloric acid, at autogenous pressure. The conducted analyses reveal that the internal structure and total porosity of the resulting composites strongly depend on the catalyst which was used for silica precursor gelation. The parameters characterizing the porosity of both of the acid set composites are much lower than the parameters of the base set composites. Moreover, the basic catalyst supplied in the vapour phase does not affect the ibuprofen sodium molecules, whereas the acid one causes transformation of the ibuprofen sodium into the sodium chloride and a derivative of propanoic acid, which is poorly water soluble. The release profiles of ibuprofen sodium from composites demonstrate that there are differences in the rate and efficiency of drug desorption from them. They are mainly affected by the chemical character of the polymeric carrier but are also associated with the restricted swelling of the composites in the buffer solution after precipitation of silica gel.

  14. Synthesis and characterization of Cr2O3 nanoparticles through sol-gel proteic method

    International Nuclear Information System (INIS)

    Medeiros, Angela Maria de Lemos

    2007-01-01

    In the last years, nanoparticles have becoming important to several researchers. This research reside in the fact that new and uncommon physical and chemical properties, absent in the same material in macro and microscopic size, are observed in this new scale. The subject of this study is obtaining chromium oxide nanoparticles (Cr 2 O 3 ) by sol–gel proteic process using gelatin as an organic precursor. This process appears as a new alternative for the synthesis of oxides for great applications with high efficiency and low cost. The interest in that material is due to the several applications such as green pigments, coverings of materials for thermal protection and mainly as catalyst of countless products originating from of the industry of the petroleum, among others. This new route, using chromium salt as chromium source, produces nanoparticles with average particle size between 20 and 60nm. These values were obtained for different crystallographic direction by means of X-Ray Diffraction (XRD) technique and the structure refinement by Rietveld method were applied in several samples prepared at different temperatures. Other techniques have been used in order to complement the XRD results. (author)

  15. Synthesis of magnetic and multiferroic materials from polyvinyl alcohol-based gels

    Energy Technology Data Exchange (ETDEWEB)

    Lisnevskaya, I.V.; Bobrova, I.A.; Lupeiko, T.G.

    2016-01-01

    This review article summarizes results on the synthesis of the magnetic materials including modified nickel ferrite (Ni{sub 0.9}Co{sub 0.1}Cu{sub 0.1}Fe{sub 1.9}O{sub 4−δ}), yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}), lanthanum-containing manganites (M{sub x}La{sub 1−x}MnO{sub 3} (M=Pb, Ba or Sr; x=0.3−0.35)), and multiferroics (BiFeO{sub 3} and BiFe{sub 0.5}Mn{sub 0.5}O{sub 3}) from polyvinyl alcohol-based gels. It is shown that the ammonium nitrate accelerates destruction of organic components of xerogels and thus Ni{sub 0.9}Co{sub 0.1}Cu{sub 0.1}Fe{sub 1.9}O{sub 4−δ} and BiFeO{sub 3} can be prepared at record low temperatures (100 and 250 °C, respectively) which are 200–300 °C lower compared to the process where air is used as an oxidizing agent. As for the synthesis of Y{sub 3}Fe{sub 5}O{sub 12}, M{sub x}La{sub 1−x}MnO{sub 3} and BiFe{sub 0.5}Mn{sub 0.5}O{sub 3}, the presence of NH{sub 4}NO{sub 3} favors formation of foreign phases, which ultimately complicate reaction mechanisms and lead to the higher temperature to synthesize target products. Developed methods provide nanoscale magnetic and multiferroic materials with an average particle size of ∼20–50 nm. - Highlights: • This review summarizes results on the synthesis of the magnetic materials and multiferroics. • Ammonium nitrate accelerates destruction of organic components of xerogels. • Ni{sub 0.9}Co{sub 0.1}Cu{sub 0.1}Fe{sub 1.9}O{sub 4−δ} and BiFeO{sub 3} can be prepared at record low temperatures. • Developed methods provide nanoscale magnetic and multiferroic materials.

  16. A new sol-gel synthesis of 45S5 bioactive glass using an organic acid as catalyst.

    Science.gov (United States)

    Faure, J; Drevet, R; Lemelle, A; Ben Jaber, N; Tara, A; El Btaouri, H; Benhayoune, H

    2015-02-01

    In this paper a new sol-gel approach was explored for the synthesis of the 45S5 bioactive glass. We demonstrate that citric acid can be used instead of the usual nitric acid to catalyze the sol-gel reactions. The substitution of nitric acid by citric acid allows to reduce strongly the concentration of the acid solution necessary to catalyze the hydrolysis of silicon and phosphorus alkoxides. Two sol-gel powders with chemical compositions very close to that of the 45S5 were obtained by using either a 2M nitric acid solution or either a 5mM citric acid solution. These powders were characterized and compared to the commercial Bioglass®. The surface properties of the two bioglass powders were assessed by scanning electron microscopy (SEM) and by Brunauer-Emmett-Teller method (BET). The Fourier transformed infrared spectroscopy (FTIR) and the X-ray diffraction (XRD) revealed a partial crystallization associated to the formation of crystalline phases on the two sol-gel powders. The in vitro bioactivity was then studied at the key times during the first hours of immersion into acellular Simulated Body Fluid (SBF). After 4h immersion into SBF we clearly demonstrate that the bioactivity level of the two sol-gel powders is similar and much higher than that of the commercial Bioglass®. This bioactivity improvement is associated to the increase of the porosity and the specific surface area of the powders synthesized by the sol-gel process. Moreover, the nitric acid is efficiently substituted by the citric acid to catalyze the sol-gel reactions without alteration of the bioactivity of the 45S5 bioactive glass. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. A new sol–gel synthesis of 45S5 bioactive glass using an organic acid as catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Faure, J., E-mail: joel.faure@univ-reims.fr [Université de Reims Champagne-Ardenne, Laboratoire Ingénierie et Sciences des Matériaux, LISM EA 4695, 21 rue Clément ADER, 51685 REIMS Cedex 2 (France); Drevet, R., E-mail: richard.drevet@univ-reims.fr [Université de Reims Champagne-Ardenne, Laboratoire Ingénierie et Sciences des Matériaux, LISM EA 4695, 21 rue Clément ADER, 51685 REIMS Cedex 2 (France); Lemelle, A.; Ben Jaber, N.; Tara, A. [Université de Reims Champagne-Ardenne, Laboratoire Ingénierie et Sciences des Matériaux, LISM EA 4695, 21 rue Clément ADER, 51685 REIMS Cedex 2 (France); El Btaouri, H. [Université de Reims Champagne-Ardenne UMR CNRS MEDyC, EA 7369, Campus Moulin de la Housse, 51687 REIMS Cedex 2 (France); Benhayoune, H. [Université de Reims Champagne-Ardenne, Laboratoire Ingénierie et Sciences des Matériaux, LISM EA 4695, 21 rue Clément ADER, 51685 REIMS Cedex 2 (France)

    2015-02-01

    In this paper a new sol–gel approach was explored for the synthesis of the 45S5 bioactive glass. We demonstrate that citric acid can be used instead of the usual nitric acid to catalyze the sol–gel reactions. The substitution of nitric acid by citric acid allows to reduce strongly the concentration of the acid solution necessary to catalyze the hydrolysis of silicon and phosphorus alkoxides. Two sol–gel powders with chemical compositions very close to that of the 45S5 were obtained by using either a 2 M nitric acid solution or either a 5 mM citric acid solution. These powders were characterized and compared to the commercial Bioglass®. The surface properties of the two bioglass powders were assessed by scanning electron microscopy (SEM) and by Brunauer–Emmett–Teller method (BET). The Fourier transformed infrared spectroscopy (FTIR) and the X-ray diffraction (XRD) revealed a partial crystallization associated to the formation of crystalline phases on the two sol–gel powders. The in vitro bioactivity was then studied at the key times during the first hours of immersion into acellular Simulated Body Fluid (SBF). After 4 h immersion into SBF we clearly demonstrate that the bioactivity level of the two sol–gel powders is similar and much higher than that of the commercial Bioglass®. This bioactivity improvement is associated to the increase of the porosity and the specific surface area of the powders synthesized by the sol–gel process. Moreover, the nitric acid is efficiently substituted by the citric acid to catalyze the sol–gel reactions without alteration of the bioactivity of the 45S5 bioactive glass. - Highlights: • Citric acid is employed as a catalyzer of the sol–gel process. • This catalyzer is used at a very low concentration for the hydrolysis reaction. • The chemical composition of the bioglass synthesized by the sol–gel process is optimized. • The properties of two sol–gel bioglasses are compared with those of the commercial

  18. A new sol–gel synthesis of 45S5 bioactive glass using an organic acid as catalyst

    International Nuclear Information System (INIS)

    Faure, J.; Drevet, R.; Lemelle, A.; Ben Jaber, N.; Tara, A.; El Btaouri, H.; Benhayoune, H.

    2015-01-01

    In this paper a new sol–gel approach was explored for the synthesis of the 45S5 bioactive glass. We demonstrate that citric acid can be used instead of the usual nitric acid to catalyze the sol–gel reactions. The substitution of nitric acid by citric acid allows to reduce strongly the concentration of the acid solution necessary to catalyze the hydrolysis of silicon and phosphorus alkoxides. Two sol–gel powders with chemical compositions very close to that of the 45S5 were obtained by using either a 2 M nitric acid solution or either a 5 mM citric acid solution. These powders were characterized and compared to the commercial Bioglass®. The surface properties of the two bioglass powders were assessed by scanning electron microscopy (SEM) and by Brunauer–Emmett–Teller method (BET). The Fourier transformed infrared spectroscopy (FTIR) and the X-ray diffraction (XRD) revealed a partial crystallization associated to the formation of crystalline phases on the two sol–gel powders. The in vitro bioactivity was then studied at the key times during the first hours of immersion into acellular Simulated Body Fluid (SBF). After 4 h immersion into SBF we clearly demonstrate that the bioactivity level of the two sol–gel powders is similar and much higher than that of the commercial Bioglass®. This bioactivity improvement is associated to the increase of the porosity and the specific surface area of the powders synthesized by the sol–gel process. Moreover, the nitric acid is efficiently substituted by the citric acid to catalyze the sol–gel reactions without alteration of the bioactivity of the 45S5 bioactive glass. - Highlights: • Citric acid is employed as a catalyzer of the sol–gel process. • This catalyzer is used at a very low concentration for the hydrolysis reaction. • The chemical composition of the bioglass synthesized by the sol–gel process is optimized. • The properties of two sol–gel bioglasses are compared with those of the commercial

  19. Sol-gel synthesis of Bi3.25La0.75Ti3O12 nanotubes

    International Nuclear Information System (INIS)

    Wang Wen; Ke Hua; Rao Jiancun; Feng Jinbiao; Feng Ming; Jia Dechang; Zhou Yu

    2011-01-01

    Research highlights: → One-dimensional (1D) ferroelectrics have been successfully synthesized. The sol-gel template synthesis is a versatile and inexpensive technique for producing nanostructures, and particularly facilitates the fabrication of complex oxide nanotubes or nanowires. Compared with the synthesis of the general nanotubes such as carbon nanotubes with simple crystal structure, the synthesis of ferroelectric compound is difficult due to the multielement and the complex crystal structures of these ferroelectrics. Herein, we report the synthesis of one-dimensional BLT nanotubes on anodic alumina (AAO) templates by immersing a template membrane in sol without polymeric additive. - Abstract: Ferroelectric Bi 3.25 La 0.75 Ti 3 O 12 (BLT) nanotubes were synthesized by sol-gel technique using nanochannel porous anodic aluminum oxide (AAO) templates, and were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). BLT nanotubes with diameter of around 240 nm and the wall thickness of about 25 nm exhibited a single orthorhombic perovskite structure and highly preferential crystal growth along the [1 1 7] orientation, which have smooth wall morphologies and well-defined diameters corresponding to the diameter of the applied template. The formation mechanism of BLT nanotubes was discussed.

  20. Sol–gel synthesis and luminescence of undoped and Mn-doped zinc orthosilicate phosphor nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    El Ghoul, J., E-mail: ghoultn@yahoo.fr [Laboratoire de Physique des Matériaux et des Nanomatériaux Appliquée à l’Environnement, Faculté des Sciences de Gabès, Cité Erriadh Manara Zrig, 6072 Gabès (Tunisia); El Mir, L. [Laboratoire de Physique des Matériaux et des Nanomatériaux Appliquée à l’Environnement, Faculté des Sciences de Gabès, Cité Erriadh Manara Zrig, 6072 Gabès (Tunisia); Al Imam Mohammad Ibn Saud Islamic University (IMSIU), College of Sciences, Departement of Physics, Riyadh 11623 (Saudi Arabia)

    2014-04-15

    Zn{sub 2}SiO{sub 4} and Zn{sub 2}SiO{sub 4}:Mn particles embedded in SiO{sub 2} host matrix prepared by sol gel method under supercritical conditions of ethyl alcohol in two steps. Were prepared by a simple solid-phase reaction under natural atmosphere at 1200 °C after the incorporation of ZnO and ZnO:Mn nanoparticles, respectively, in silica monolith. In the case of SiO{sub 2}/Zn{sub 2}SiO{sub 4} nanocomposite, the powder with an average particle size of 80 nm shows a strong luminescence band centred at around 760 nm in the visible range. In addition, the PL spectrum for the SiO{sub 2}/Zn{sub 2}SiO{sub 4}:Mn nanocomposite showed that a dominant peak at 525 nm appeared, which originated from the {sup 4}T{sub 1}–{sup 6}A{sub 1} transitions of Mn{sup 2+} ions. The luminescence properties of nanocomposites were characterized by emission and excitation spectra as well their dependencies of upon temperature and power excitation density. -- Highlights: • The Synthesis of Zn{sub 2}SiO{sub 4} nanocomposites. • Structural and optical characterizations of Zn{sub 2}SiO{sub 4} and Zn{sub 2}SiO{sub 4}:Mn nanocomposites. • The willemite α-Zn{sub 2}SiO{sub 4} structure was formed to the heat treatment temperature 1200 °C. • The powder exhibits a nanometric size. • Strong bands of luminescence have appeared.

  1. Synthesis and Thermal Characterization of Hydroxyapatite Powders Obtained by Sol-Gel Technique

    Science.gov (United States)

    Jiménez-Flores, Y.; Camacho, N.; Rojas-Trigos, J. B.; Suárez, M.

    The development of bioactive materials presents an interesting and an extremely relevant problem to solve, in the development of customized cranial and maxillofacial prosthesis, bioactive coating, and cements, for example. In such areas, one of the more employed materials is the synthetic hydroxyapatite, due to its proved biocompatibility with the human body; however, there are few studies about the thermal affinity with the biological surroundings, and most of them are centered in the thermal stability of the hydroxyapatite instead of its transient thermal response. In the present paper, the synthesis and physical-chemical characterization of hydroxyapatite samples, obtained by the sol-gel technique employing ultrasonic mixing, are reported. Employing X-ray diffraction patterns, XEDS and FTIR spectra, the crystal symmetry, chemical elements, and the present functional groups of the studied samples were determined and found to correspond to those reported in the literature, with a stoichiometry close to the ideal for biological applications. Additionally, by means of the photoacoustic detection and infrared photothermal radiometry (IPTR) techniques, the thermal response of the samples was obtained. Analyzing the photoacoustic data, the synthetized samples show photoacoustic opaqueness, responding in the thermally thick regime in the measurement range, and their thermal effusivity was also determined, having values of 1.47 folds the thermal effusivity of the mandibular human bone. Finally, from the IPTR measurements, the thermal diffusivity and thermal conductivity of the samples were also determined, having good agreement with the reported values for synthetic hydroxyapatite. The structural and thermophysical properties of the here reported samples show that the synthesized samples have good thermal affinity with the mandibular human bone tissue, and are suitable for biomedical applications.

  2. Sol-gel synthesis of magnesium oxide-silicon dioxide glass compositions

    Science.gov (United States)

    Bansal, Narottam P.

    1988-01-01

    MgO-SiO2 glasses containing up to 15 mol pct MgO, which could not have been prepared by the conventional glass melting method due to the presence of stable liquid-liquid immiscibility, were synthesized by the sol-gel technique. Clear and transparent gels were obtained from the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) and magnesium nitrate hexahydrate when the water/TEOS mole ratio was four or more. The gelling time decreased with increase in magnesium content, water/TEOS ratio, and reaction temperature. Magnesium nitrate hexahydrate crystallized out of the gels containing 15 and 20 mol pct MgO on slow drying. This problem was partially alleviated by drying the gels quickly at higher temperatures. Monolithic gel samples were prepared using glycerol as the drying control additive. The gels were subjected to various thermal treatments and characterized by several methods. No organic groups could be detected in the glasses after heat treatments to approx. 800 C, but trace amounts of hydroxyl groups were still present. No crystalline phase was found from X-ray diffraction in the gel samples to approx. 890 C. At higher temperatures, alpha quartz precipitated out as the crystalline phase in gels containing up to 10 mol pct MgO. The overall activation energy for gel formation in 10MgO-90SiO2 (mol pct) system for water/TEOS mole ratio of 7.5 was calculated to be 58.7 kJ/mol.

  3. Synthesis of Alkylpoly glucoside from Dextrose-Decanol in the Presence of Silicotungstic Acid Sol-Gel Catalyst

    International Nuclear Information System (INIS)

    Izazi Azzahidah Amin; Mohd Ambar Yarmo; Nik Idris Nik Yusoff

    2013-01-01

    The purpose of this study is to synthesis alkylpoly glucoside via condensation of decanol with dextrose in the presence of heterogenous catalyst. In this study, silicotungstic acid sol-gel (STSG) prepared using sol-gel was used as solid acid catalyst. The catalyst was characterized using BET surface area measurement, X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) surface analysis. The final product was easy to be separated from catalyst without the need of a further neutralization. Silicotungstic acid sol-gel has been found efficient to be solid catalyst for synthesis alkylpoly glucosides. Condensation reaction was carried out 8 hours at 110-120 degree Celsius under vacuum condition at 10 mmHg. The determination of decyl glucoside has been achieved by LC/ ESI-MS/ MS (ToF) giving a mass peak at m/z = 343.2 correspond to the m/z of [M+Na] + . Alkylpoly glucoside produced was analysed by FTIR, 1 H and 13 C NMR spectrometric technique. (author)

  4. Synthesis and characterization of nanocomposite powders of calcium phosphate/silica-gel; Sintese e caracterizacao de pos nanoestruturados de fosfato de calcio/silica-gel

    Energy Technology Data Exchange (ETDEWEB)

    Muller, D.T.; Delima, S.A. [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Dept. de Engenharia Mecanica; Santos, R.B.M.; Camargo, N.H.A., E-mail: dem2nhac@joinville.udesc.b [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Programa de Pos Graduacao em Ciencia e Engenharia de Materiais

    2009-07-01

    In the recent years ceramics of calcium phosphate are pointed out as an outstanding material in substitution and regeneration in defects from osseous tissue, in reason of their similar mineralogical characteristics of apatite of bone structure. However, the challenge with phosphate calcium ceramics find out about the mechanical properties and the development of biomaterials similar of the bone structure, what sometimes is not so easy, about fragile materials. The aim of this work focused in synthesis and characterization nanocomposites powders of calcium phosphate/silica-gel with percentages 1, 2, 3 e 5% of nanometric silica. The method synthesis used for the compositions elaboration was dissolution-precipitation. The presented results are related with the optimization to method elaboration of nanostructured powders, the mineralogical characterization with X-ray diffraction, thermal behavior with thermal differential analysis, differential scanning calorimetry here is ADT and dilatometer. The scanning electronic microscopy was used to help of morphological characterization the nanostructured powders and the surfaces from body test recovered from the mechanical test. (author)

  5. Synthesis of all-silica zeolites from highly concentrated gels containing hexamethonium cations

    KAUST Repository

    Liu, Xiaolong; Ravon, Ugo; Tuel, Alain

    2012-01-01

    A pure and highly crystalline all-silica EU-1 zeolite has been obtained from the crystallization of gels containing very low water contents in the presence of hexamethonium cations. Decreasing the water content in the gel down to H 2O/Si < 1

  6. Synthesis and characterization of α-alumina col-gel nanometric: elaboration of biomaterials nanostructured for biomedical applications

    International Nuclear Information System (INIS)

    Passoni, L.S.; Feit, G.; Camargo, N.H.A.

    2010-01-01

    The production of nanostructured biomaterials are research themes for these present new characteristics of biocompatibility and bioactivity. The sol-gel process allows obtaining α-alumina nanometric with purity 99.99%. The use of nanoparticles of Al 2 O 3 -α, SiO 2 and TiO 2 are being employed as a second stage in the development of nanocomposites biomaterials. The presence of the second phase within a ceramic matrix leads to obtaining nanomaterials with micropores in micro and nanostructures interconnected, what contributes within the processes of osseous integration, osseous induction. The goal of this work focused on synthesis and characterization of an α- alumina by sol-gel process. Characterization studies were conducted using the various techniques: X-ray diffraction, scanning electron microscopy, exploratory differential scanning calorimetry and infrared spectrometry by Fourier transforms. The preliminary results showed the attainment the nanometric α-alumina powder. (author)

  7. Synthesis and studies of Y-Ba-Cu-O high temperature superconductor prepared by sol-gel method

    International Nuclear Information System (INIS)

    Grigoryan, S.G.; Manukyan, A.L.; Hayrapetyan, A.G.; Arzumanyan, A.M.; Rashidyan, L.H.; Mkrtichyan, N.Y.; Mkrtchyan, A.A.; Kurginyan, K.A.; Trozyan, A.H.; Vardanyan, R.S.

    2004-01-01

    The method of preparation of Y-Ba-Cu-O high temperature superconducting materials by sol-gel processing technique both for powders and thin films are described. All these methods are based on using yttrium alkoxides as precursors, which are not ready available reagents, besides the majority of these methods use copper alkoxides, which show low solubility in organic solvents, moreover they are very sensitive to hydrolysis in air. The new method of preparation of Y-Ba-Cu-O ceramic materials by sol-gel processing technique based on new and convenient precursors stable in air, having high compatibility with each other is offered. Basic scientific and technological issues related to the synthesis of bulk materials, their structure and electrical conductivity are discussed

  8. Synthesis of organic/inorganic hybrid gel with acid activated clay after γ-ray radiation.

    Science.gov (United States)

    Kim, Donghyun; Lee, Hoik; Sohn, Daewon

    2014-08-01

    A hybrid gel was prepared from acid activated clay (AA clay) and acrylic acid by gamma ray irradiation. Irradiated inorganic particles which have peroxide groups act as initiator because it generates oxide radicals by increasing temperature. Inorganic nanoparticles which are rigid part in hybrid gel also contribute to increase the mechanical property as a crosslinker. We prepared two hybrid gels to compare the effect of acid activated treatment of clay; one is synthesized with raw clay particles and another is synthesized with AA clay particles. The composition and structure of AA clay particles and raw clay particles were confirmed by X-ray diffraction (XRD), X-ray fluorescence instrument and surface area analyzer. And chemical and physical property of hybrid gel with different ratios of acrylic acid and clay particle was tested by Raman spectroscope and universal testing machine (UTM). The synthesized hydrogel with 76% gel contents can elongated approximately 1000% of its original size.

  9. Technology of boron-containing polyphosphate fertilizer 'Phosphobor'

    International Nuclear Information System (INIS)

    Aldabergenov, M.K.; Balakaeva, T.G.

    1995-01-01

    A technology is developed for producing 'Phosphobor' fertilizer based on the rock phosphate weal (17-18% P 2 O 5 ) with additions of boron-magnesium compound. Boron is part of polyphosphate fertilizer in the form of polymeric compounds of phosphorus and boron. Phosphorus and boron copolymers -boratophosphates - are easily formed in the process of polyphosphate fertilizers production, since borates undergo a mutual polycondensation reaction with phosphates. 8 refs., 1 fig

  10. Synthesis of Fluorite (CaF2 Crystal from Gypsum Waste of Phosphoric Acid Factory in Silica Gel

    Directory of Open Access Journals (Sweden)

    Mohammad Misbah Khunur

    2012-06-01

    Full Text Available This paper report the synthesis and characterization of fluorite single crystal prepared from gypsum waste of phosphoric acid production in silica gel. Instead of its high calcium, gypsum was used to recycle the waste which was massively produces in the phosphoric acid production. The gypsum waste, the raw material of CaCl2 supernatant, was dissolved in concentrated HCl and then precipitated as calcium oxalate (CaC2O4 by addition of ammonium oxalate. The CaCl2 was obtained by dissolving the CaC2O4 with HCl 3M. The crystals were grown at room temperature in silica gel and characterized by AAS, FTIR and powder XRD. The optimum crystal growth condition, which is pH of gel, CaCl2 concentration and growth time, were investigated. The result shows that at optimum condition of pH 5.80, CaCl2 concentrations of 1.2 M, and growth time of 144 hours, colorless crystals with the longest size of 3 mm, were obtained (72.57%. Characterization of the synthesized crystal by AAS indicates that the obtained crystal has high purity. Meanwhile, analysis by FTIR spectra shows a Ca–F peak at 775 cm-1, and powder-XRD analysis confirms that the obtained crystal was fluorite (CaF2. © 2012 BCREC UNDIP. All rights reservedReceived: 11st April 2012; Revised: 4th June 2012; Accepted: 13rd June 2012[How to Cite: M.M. Khunur, A. Risdianto, S. Mutrofin, Y.P. Prananto. (2012. Synthesis of Fluorite (CaF2 Crystal from Gypsum Waste of Phosphoric Acid Factory in Silica Gel. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1: 71-77.  doi:10.9767/bcrec.7.1.3171.71-77 ][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.3171.71-77 ] | View in 

  11. Ammonia sensing properties of V-doped ZnO:Ca nanopowders prepared by sol–gel synthesis

    International Nuclear Information System (INIS)

    Fazio, E.; Hjiri, M.; Dhahri, R.; El Mir, L.; Sabatino, G.; Barreca, F.; Neri, F.; Leonardi, S.G.; Pistone, A.; Neri, G.

    2015-01-01

    V-doped ZnO:Ca nanopowders with different V loading were prepared by sol–gel synthesis and successive drying in ethanol under supercritical conditions. Characterization data of nanopowders annealed at 700 °C in air, revealed that they have the wurtzite structure. Raman features of V-doped ZnO:Ca samples were found to be substantially modified with respect to pure ZnO or binary ZnO:Ca samples, which indicate the substitution of vanadium ions in the ZnO lattice. The ammonia sensing properties of V-doped ZnO:Ca thick films were also investigated. The results obtained demonstrate the possibility of a fine tuning of the sensing characteristics of ZnO-based sensors by Ca and V doping. In particular, their combined effect has brought to an enhanced response towards NH 3 compared to bare ZnO and binary V-ZnO and Ca-ZnO samples. Raman investigation suggested that the presence of Ca play a key role in enhancing the sensor response in these ternary composite nanomaterials. - Graphical abstract: V-doped ZnO:Ca nanopowders prepared by sol–gel synthesis possess enhanced sensing characteristics towards NH 3 compared to bare ZnO. - Highlights: • V-doped ZnO:Ca nanopowders with different V loading were prepared by sol–gel synthesis. • Raman features of V-doped ZnO:Ca samples indicate the substitution of V ions in the ZnO lattice. • Combined effects of dopants have brought to an enhanced response to NH 3 compared to ZnO. • Ca play a key role in enhancing the sensor response of ternary V-doped ZnO:Ca composites

  12. Synthesis of Bi4Si3O12 powders by a sol–gel method

    International Nuclear Information System (INIS)

    Xie Huidong; Jia Caixia; Jiang Yuanru; Wang Xiaochang

    2012-01-01

    Highlights: ► Bi 4 Si 3 O 12 were synthesized by a sol–gel method, using stoichiometric materials. ► The calcining process of the as-dried gel was studied by different analyses. ► Phase separation in the sol–gel process was found during the calcination. - Abstract: Micro-crystals of bismuth orthosilicate (Bi 4 Si 3 O 12 ) were synthesized by a sol–gel method, using stoichiometric Si(OC 2 H 5 ) 4 , Bi(NO 3 ) 3 ·5H 2 O as the precursors and acetic acid as the solvent. The calcining process of the as-dried gel was studied by total gravity/differential scanning calory (TG/DSC), X-ray diffraction (XRD) and infrared (IR) spectra. Experiments showed that single phase of Bi 4 Si 3 O 12 could be obtained by sol–gel method at a calcining temperature of 900 °C. Phase separation in the sol–gel process was found during the calcination.

  13. Progress of studies on preparation of TiO2 photocatalysts with sol-gel auto igniting synthesis

    Science.gov (United States)

    Wu, Di; Shi, Zaifeng; Zhang, Xiaopeng; Xinghui, Wu

    2017-11-01

    In this article, influencing factors on the kinetics of the process of Sol-gel Auto igniting Synthesis (SAS) which is an advanced technology for preparing nanometer particles of inorganic materials were reviewed. The studies on preparing of nanometer TiO2 photocatalysts with SAS were focused. It was concluded that SAS will play an important role in practical preparing of high-pure nanometer TiO2 powder, and as a technical support, preparation of titania TiO2 from titanic iron ore with SAS is feasible and practicable.

  14. Sol-gel synthesis of bioactive glass porous scaffolds with addition of porogen agent

    International Nuclear Information System (INIS)

    Guimaraes, F.B.A.P.; Barrioni, B.R.; Oliveira, A.C.X.; Oliveira, A.A.R.; Pereira, M.M.

    2016-01-01

    The use of biomaterials capable of generating a biological response has been one of the biggest progresses in regenerative medicine, due to their ability to support growth stimulation and damaged tissue regeneration. In this context, bioceramics, particularly bioactive glass (BG), were the subject of many studies. The technique of porogen agent addition for the synthesis of scaffolds is an interesting procedure, because several types of porogen agents can be used. The aim of the present work was to obtain scaffolds using four porogen agents and to evaluate the effects that a change in treatment temperature can have on their crystallinity. Scaffolds of sol-gel bioactive glass 100S (100% SiO 2 ) using as porogen agents paraffin 1, paraffin 2, wax and CMC (carboxymethyl cellulose) were synthesized and characterized. As the best results were obtained with paraffin 1, scaffolds 58S (60%SiO 2 -36%CaO-4%P 2 O 5 ) and 100S using paraffin 1 as porogen agent were prepared. The scaffolds were submitted to different treatment temperatures to evaluate the effect on their crystallinity. Pore structure was analyzed by scanning electron microscopy and micro-computed tomography. Scaffolds presented satisfactory pore size and pore size distribution, important characteristics for scaffolds because they allow cell migration, nutrient transport, vascularisation and tissue ingrowth. X-ray powder diffraction showed the amorphous nature of the scaffolds. At 900 °C, scaffolds BG 58S and 100S showed a small increase in crystallinity. BET analysis (N 2 -adsorption) indicated a mesoporous structure. The specific surface area varied from 73.2 m 2 /g for scaffold 58S treated at 800 °C to 331.2 m 2 /g for scaffold 100S treated at 800 °C. The materials obtained showed no toxic effects by MTT cytotoxicity assays. Results showed that the development of scaffolds is possible using porogen agents, with 3D interconnected porous structure and might therefore be a potential biomaterial for bone

  15. Sol-gel-cum-hydrothermal synthesis of mesoporous Co-Fe@Al2O3 ...

    Indian Academy of Sciences (India)

    Oxides; sol-gel; adsorption; surface properties; composite materials. 1. Introduction. Industrial dyes ... acid green 25, Congo red, N719), phenolic compounds. (bromophenol blue .... microscopy (TEM) images were obtained using Philips CM.

  16. Synthesis of Hollow Sphere and 1D Structural Materials by Sol-Gel Process.

    Science.gov (United States)

    Li, Fa-Liang; Zhang, Hai-Jun

    2017-08-25

    The sol-gel method is a simple and facile wet chemical process for fabricating advanced materials with high homogeneity, high purity, and excellent chemical reactivity at a relatively low temperature. By adjusting the processing parameters, the sol-gel technique can be used to prepare hollow sphere and 1D structural materials that exhibit a wide application in the fields of catalyst, drug or gene carriers, photoactive, sensors and Li-ion batteries. This feature article reviewed the development of the preparation of hollow sphere and 1D structural materials using the sol-gel method. The effects of calcination temperature, soaking time, pH value, surfactant, etc., on the preparation of hollow sphere and 1D structural materials were summarized, and their formation mechanisms were generalized. Finally, possible future research directions of the sol-gel technique were outlined.

  17. Synthesis of yttrium silicate luminescent materials by sol-gel method

    International Nuclear Information System (INIS)

    Arkhipov, D.V.; Vasina, O.Yu.; Popovich, N.V.; Galaktionov, S.S.; Soshchin, N.P.

    1996-01-01

    Several yttrium-silicate composition with Y 2 O 3 content within 44-56% have been synthesized. it is ascertained that employment of sol-gel technique permits preparation of luminescent materials on yttrium silicate basis, which compare favourably with bath-produced specimens. The influence of phase composition of sol-gel phosphors on basic performance indices: intensity and luminescence spectrum, has been analyzed

  18. Quantitative phase analysis and microstructure characterization of magnetite nanocrystals obtained by microwave assisted non-hydrolytic sol–gel synthesis

    International Nuclear Information System (INIS)

    Sciancalepore, Corrado; Bondioli, Federica; Manfredini, Tiziano; Gualtieri, Alessandro

    2015-01-01

    An innovative preparation procedure, based on microwave assisted non-hydrolytic sol–gel synthesis, to obtain spherical magnetite nanoparticles was reported together with a detailed quantitative phase analysis and microstructure characterization of the synthetic products. The nanoparticle growth was analyzed as a function of the synthesis time and was described in terms of crystallization degree employing the Rietveld method on the magnetic nanostructured system for the determination of the amorphous content using hematite as internal standard. Product crystallinity increases as the microwave thermal treatment is increased and reaches very high percentages for synthesis times longer than 1 h. Microstructural evolution of nanocrystals was followed by the integral breadth methods to obtain information on the crystallite size-strain distribution. The results of diffraction line profile analysis were compared with nanoparticle grain distribution estimated by dimensional analysis of the transmission electron microscopy (TEM) images. A variation both in the average grain size and in the distribution of the coherently diffraction domains is evidenced, allowing to suppose a relationship between the two quantities. The traditional integral breadth methods have proven to be valid for a rapid assessment of the diffraction line broadening effects in the above-mentioned nanostructured systems and the basic assumption for the correct use of these methods are discussed as well. - Highlights: • Fe 3 O 4 nanocrystals were obtained by MW-assisted non-hydrolytic sol–gel synthesis. • Quantitative phase analysis revealed that crystallinity up to 95% was reached. • The strategy of Rietveld refinements was discussed in details. • Dimensional analysis showed nanoparticles ranging from 4 to 8 nm. • Results of integral breadth methods were compared with microscopic analysis

  19. Quantitative phase analysis and microstructure characterization of magnetite nanocrystals obtained by microwave assisted non-hydrolytic sol–gel synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Sciancalepore, Corrado, E-mail: corrado.sciancalepore@unimore.it [Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Via Pietro Vivarelli 10, 41100 Modena (Italy); Bondioli, Federica [Department of Industrial Engineering, University of Parma, Parco Area delle Scienze, 181/A, 43124 Parma (Italy); INSTM Consortium, Via G. Giusti 9, 51121 Firenze (Italy); Manfredini, Tiziano [Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Via Pietro Vivarelli 10, 41100 Modena (Italy); INSTM Consortium, Via G. Giusti 9, 51121 Firenze (Italy); Gualtieri, Alessandro [Department of Chemical and Geological Science, University of Modena and Reggio Emilia, Via S. Eufemia 19, 41121 Modena Italy (Italy)

    2015-02-15

    An innovative preparation procedure, based on microwave assisted non-hydrolytic sol–gel synthesis, to obtain spherical magnetite nanoparticles was reported together with a detailed quantitative phase analysis and microstructure characterization of the synthetic products. The nanoparticle growth was analyzed as a function of the synthesis time and was described in terms of crystallization degree employing the Rietveld method on the magnetic nanostructured system for the determination of the amorphous content using hematite as internal standard. Product crystallinity increases as the microwave thermal treatment is increased and reaches very high percentages for synthesis times longer than 1 h. Microstructural evolution of nanocrystals was followed by the integral breadth methods to obtain information on the crystallite size-strain distribution. The results of diffraction line profile analysis were compared with nanoparticle grain distribution estimated by dimensional analysis of the transmission electron microscopy (TEM) images. A variation both in the average grain size and in the distribution of the coherently diffraction domains is evidenced, allowing to suppose a relationship between the two quantities. The traditional integral breadth methods have proven to be valid for a rapid assessment of the diffraction line broadening effects in the above-mentioned nanostructured systems and the basic assumption for the correct use of these methods are discussed as well. - Highlights: • Fe{sub 3}O{sub 4} nanocrystals were obtained by MW-assisted non-hydrolytic sol–gel synthesis. • Quantitative phase analysis revealed that crystallinity up to 95% was reached. • The strategy of Rietveld refinements was discussed in details. • Dimensional analysis showed nanoparticles ranging from 4 to 8 nm. • Results of integral breadth methods were compared with microscopic analysis.

  20. Synthesis of polymer gel electrolyte with high molecular weight poly(methyl methacrylate)-clay nanocomposite

    International Nuclear Information System (INIS)

    Meneghetti, Paulo; Qutubuddin, Syed; Webber, Andrew

    2004-01-01

    Polymer nanocomposite gel electrolytes consisting of high molecular weight poly(methyl methacrylate) PMMA-clay nanocomposite, ethylene carbonate (EC)/propylene carbonate (PC) as plasticizer, and LiClO 4 electrolyte are reported. Montmorillonite clay was ion exchanged with a zwitterionic surfactant (octadecyl dimethyl betaine) and dispersed in methyl methacrylate, which was then polymerized to synthesize PMMA-clay nanocomposites. The nanocomposite was dissolved in a mixture of EC/PC with LiClO 4 , heated and pressed to obtain polymer gel electrolyte. X-ray diffraction (XRD) of the gels indicated intercalated clay structure with d-spacings of 2.85 and 1.40 nm. In the gel containing plasticizer, the clay galleries shrink suggesting intercalation rather than partial exfoliation observed in the PMMA-clay nanocomposite. Ionic conductivity varied slightly and exhibited a maximum value of 8 x 10 -4 S/cm at clay content of 1.5 wt.%. The activation energy was determined by modeling the conductivity with a Vogel-Tamman-Fulcher expression. The clay layers are primarily trapped inside the polymer matrix. Consequently, the polymer does not interact significantly with LiClO 4 electrolyte as shown by FTIR. The presence of the clay increased the glass transition temperature (Tg) of the gel as determined by differential scanning calorimetry. The PMMA nanocomposite gel electrolyte shows a stable lithium interfacial resistance over time, which is a key factor for use in electrochemical applications

  1. Microwave-Assisted Synthesis of Chitosan/Polyvinyl Alcohol Silver Nanoparticles Gel for Wound Dressing Applications

    Directory of Open Access Journals (Sweden)

    Nguyen Thi Hiep

    2016-01-01

    Full Text Available The purpose of this study was to fabricate chitosan/poly(vinyl alcohol/Ag nanoparticles (CPA gels with microwave-assistance for skin applications. Microwave irradiation was employed to reduce silver ions to silver nanoparticles and to crosslink chitosan (CS with polyvinyl alcohol (PVA. The presence of silver nanoparticles in CPA gels matrix was examined using UV-Vis spectroscopy, transmission electron microscopy, and X-ray diffraction. The interaction of CS and PVA was analysed by Fourier transform infrared spectroscopy. The release of silver ions was determined by atomic absorption spectrometry. The antimicrobial properties of CPA gels against P. aeruginosa and S. aureus were investigated using agar diffusion method. Finally, the biocompatibility and wound-healing ability of the gels were studied using fibroblast cells (in vitro and mice models (in vivo. In conclusion, the results showed that CPA gels were successfully fabricated using microwave irradiation method. These gels can be applied to heal an open wound thanks to their antibacterial activity and biocompatibility.

  2. Synthesis and characterization of silica gel from siliceous sands of southern Tunisia

    Directory of Open Access Journals (Sweden)

    Ali Sdiri

    2014-09-01

    Full Text Available The present work aimed to achieve valorization of Albian sands for the preparation of sodium silicates that are commonly used as a precursor to prepare silica gel. A siliceous sand sample was mixed with sodium carbonate and heated at a high temperature (1060 °C to prepare sodium silicates. The sodium silicates were dissolved in distilled water to obtain high quality sodium silicate solution. Hydrochloric acid was then slowly added to the hydrated sodium silicates to obtain silica gel. The collected raw siliceous sands, as well as the prepared silica gels, were characterized by different techniques, such as X-ray fluorescence (XRF, X-ray diffraction (XRD, scanning electron microscopy (SEM and thermal analysis (DSC. XRF confirmed that the detrital sand deposits of southern Tunisia contain high amounts of silica, with content ranging from 88.8% to 97.5%. The internal porosity varied between 17% and 22%, and the specific surface area was less than 5 m2/g. After the treatment described above, it was observed that the porosity of the obtained silica gel reached 57% and the specific surface area exceeded 340 m2/g. Nitrogen adsorption isotherms showed that the prepared silica gels are microporous and mesoporous materials with high adsorption capacities. These results suggest that the obtained silica gels are promising materials for numerous environmental applications.

  3. Selective splitting of 3'-adenylated dinucleoside polyphosphates by specific enzymes degrading dinucleoside polyphosphates.

    Science.gov (United States)

    Guranowski, Andrzej; Sillero, Antonio; Günther Sillero, María Antonia

    2003-01-01

    Several 3'-[(32)P]adenylated dinucleoside polyphosphates (Np(n)N'p*As) were synthesized by the use of poly(A) polymerase (Sillero MAG et al., 2001, Eur J Biochem.; 268: 3605-11) and three of them, ApppA[(32)P]A or ApppAp*A, AppppAp*A and GppppGp*A, were tested as potential substrates of different dinucleoside polyphosphate degrading enzymes. Human (asymmetrical) dinucleoside tetraphosphatase (EC 3.6.1.17) acted almost randomly on both AppppAp*A, yielding approximately equal amounts of pppA + pAp*A and pA + pppAp*A, and GppppGp*, yielding pppG + pGp*A and pG + pppGp*A. Narrow-leafed lupin (Lupinus angustifolius) tetraphosphatase acted preferentially on the dinucleotide unmodified end of both AppppAp*A (yielding 90% of pppA + pAp*A and 10 % of pA + pppAp*A) and GppppGp*A (yielding 89% pppG + pGp*A and 11% of pG + pppGp*A). (Symmetrical) dinucleoside tetraphosphatase (EC 3.6.1.41) from Escherichia coli hydrolyzed AppppAp*A and GppppGp*A producing equal amounts of ppA + ppAp*A and ppG + ppGp*A, respectively, and, to a lesser extent, ApppAp*A producing pA + ppAp*A. Two dinucleoside triphosphatases (EC 3.6.1.29) (the human Fhit protein and the enzyme from yellow lupin (Lupinus luteus)) and dinucleoside tetraphosphate phosphorylase (EC 2.7.7.53) from Saccharomyces cerevisiae did not degrade the three 3'-adenylated dinucleoside polyphosphates tested.

  4. Can Polyphosphate Biochemistry Affect Biological Apatite Saturation?

    Science.gov (United States)

    Omelon, S. J.; Matsuura, N.; Gorelikov, I.; Wynnyckyj, C.; Grynpas, M. D.

    2010-12-01

    Phosphorus (P) is an important and limiting element for life. One strategy for storing ortho phosphates (Pi) is polymerization. Polymerized Pi's (polyphosphates: (PO3-)n: polyPs) serve as a Pi bank, as well as a catiion chelator, energy source, & regulator of responses to stresses in the stationary phase of culture growth and development1. PolyP biochemistry has been investigated in yeasts, bacteria & plants2. Bigeochemical cycling of P includes the condensation of Pi into pyro (P2O7-4), & polyPs, & the release of Pi from these compounds by the hydrolytic degradation of Pi from phosphomonoester bonds. Alkaline phosphatase (ALP) is one of the predominate enzymes for regenerating Pi in aquatic systems3, & it cleaves Pi from polyPs. ALP is also the enzyme associated with apatite biomineralization in vertebrates4. PolyP was proposed to be the ALP substrate in bone mineralization5. Where calcium ions are plentiful in many aquatic environments, there is no requirement for aquatic life to generate Ca-stores. However, terrestrial vertebrates benefit from a bioavailable Ca-store such as apatite. The Pi storage strategy of polymerizing PO4-3 into polyPs dovetails well with Ca-banking, as polyPs sequester Ca, forming a neutral calcium polyphosphate (Ca-polyP: (Ca(PO3)2)n) complex. This neutral complex represents a high total [Ca+2] & [PO4-3], without the threat of inadvertent apatite precipitation, as the free [Ca+2] & [PO4-3], and therefore apatite saturation, are zero. Recent identification of polyP in regions of bone resorption & calcifying cartilage5 suggests that vertebrates may use polyP chemistry to bank Ca+2 and PO4-3. In vitro experiments with nanoparticulate Ca-polyP & ALP were undertaken to determine if carbonated apatite could precipitate from 1M Ca-polyP in Pi-free “physiological fluid” (0.1 M NaCl, 2 mM Ca+2, 0.8 mM Mg+2, pH ~8.0 ±0.5, 37 °C), as this is estimated to generate the [Ca+2] & [PO4-3] required to form the apatite content of bone tissue

  5. Comparative analysis of synthesis and characterization of La_0_,_9Sr_0_,_1O_3 via sol-gel and combustion reaction

    International Nuclear Information System (INIS)

    Tarrago, D.P.; Haeser, G.S.; Malfatti, C.F.; Sousa, V.C.

    2011-01-01

    Strontium doped lanthanum manganites (LSM) are potential materials for cathode application in solid oxide fuel cells (SOFC) due to their properties and compatibility with yttria stabilized zirconia. In this work a LSM powder obtained by the sol-gel process is compared others previously obtained combustion synthesis using urea or sucrose as fuel. For the synthesis of LSM the nitrates of lanthanum, strontium and manganese were dissolved in citric acid and ethylene glycol forming a gel that was calcinated at 800 deg C. Both methods allowed the synthesis of a single phase powder, according to the X-ray diffraction patterns. Through gas adsorption it was found a specific surface area of 17m²/g, an intermediary value among the combustion synthesized powders. Scanning electron microscopy (SEM) revealed more compact agglomerates in the sol-gel powder, however, the transmission electron microscope (TEM) showed smaller and more uniform particles in this powder. (author)

  6. Synthesis and characterization of mixtures of cobalt and titanium oxides by mechanical alloyed and Sol-Gel

    International Nuclear Information System (INIS)

    Basurto S, R.; Bonifacio M, J.; Fernandez V, S. M.

    2009-01-01

    The mechanical alloyed techniques continued by combustion and Sol-Gel method, were used for the synthesis of CoTiO 3 . With the first technique was used Co 3 O 4 obtained in a balls mill SPEX in argon atmosphere, using cobalt nitrate and urea, the combustion is realized at 400 and 500 C, the characterization by X-ray diffraction showed the obtaining of the valence oxide mixed of cobalt with crystallite size from 10 to 12.5 nm and the particle size of 60 to 75 nm was obtained by scanning electron microscopy. To prepare the CoTiO 3 , the obtained Co 3 O 4 was mixed with TiO 2 on a relationship in weight (1:1) and with a milling time of 2.5 h and the combustion at 800 C. the mixed oxide of titanium cobalt was also obtained by the Sol-Gel technique starting from cobalt chloride and titanium propoxide in acetic-water acid, the gel is burned to temperature of 300, 500, 700 and 900 C, finding that this last temperature it is that provides the compound with crystalline size from 50 to 75 nm. (Author)

  7. Radiation Synthesis of PEGDA and Acrylated Palm Oil Nanosized Gel for Bioactives Immobilization

    International Nuclear Information System (INIS)

    Hamzah, M.Y.; Tajau, R.; Dahlan, K.Z. Mohd; Mahmood, M.H.; Hashim, K.

    2010-01-01

    The use of microemulsion in the development of nanosized gel based on polyethylene glycol diacrylate (PEGDA) and acrylated palm oil (APO) is demonstrated. PEGDA was solubilized in n-heptane with use of AOT at 0.15M concentration to form reverse micelles, while APO was solubilized with SDS in water to form direct micelles. Both of these systems were depicted by means of ternary phase diagram. These micelles were than irradiated at 1,3,5,10,15 and 30kGy using gamma irradiation or EB to crosslink the entrapped polymer in the micelles. Ionizing radiation was imparted to the emulsions to generate crosslinking reactions in the micelles formed. The nanosized gel was evaluated in terms of particle diameter using dynamic light scattering and the images of the nanosized gel were studied using transmission electron microscopy (TEM). Results show that the size, charge and shape of the particles are influenced by concentration of surfactants and radiation dose. This study showed that this method can be utilized to produce nanosized gel. Future work include the attachment of functional group to the nano sized gel, loading of drug such as curcumin and further characterization using dynamic light scattering. (author)

  8. Radiation Synthesis of PEGDA and Acrylated Palm Oil Nanosized Gel for Bioactives Immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Hamzah, M. Y.; Tajau, R.; Dahlan, K.Z. Mohd; Mahmood, M. H.; Hashim, K., E-mail: m_yusof@nuclearmalaysia.gov.my [Makmal Nanoteknologi, Blok 64, BTS, Jafan Denghil, Agensi Nuklear Malaysia, Bangi 43000 Kajang, Selangor (Malaysia)

    2010-07-01

    The use of microemulsion in the development of nanosized gel based on polyethylene glycol diacrylate (PEGDA) and acrylated palm oil (APO) is demonstrated. PEGDA was solubilized in n-heptane with use of AOT at 0.15M concentration to form reverse micelles, while APO was solubilized with SDS in water to form direct micelles. Both of these systems were depicted by means of ternary phase diagram. These micelles were than irradiated at 1,3,5,10,15 and 30kGy using gamma irradiation or EB to crosslink the entrapped polymer in the micelles. Ionizing radiation was imparted to the emulsions to generate crosslinking reactions in the micelles formed. The nanosized gel was evaluated in terms of particle diameter using dynamic light scattering and the images of the nanosized gel were studied using transmission electron microscopy (TEM). Results show that the size, charge and shape of the particles are influenced by concentration of surfactants and radiation dose. This study showed that this method can be utilized to produce nanosized gel. Future work include the attachment of functional group to the nano sized gel, loading of drug such as curcumin and further characterization using dynamic light scattering. (author)

  9. Sol-gel synthesis of lanthanum-gallate-based ceramic coatings

    International Nuclear Information System (INIS)

    Golubko, N.V.; Kaleva, G.M.; Roginskaya, Yu.E.; Politova, E.D.

    2007-01-01

    Phase-pure (La 0.9 Sr 0.1 )(Ga 0.7 Fe 0.3 )O 3-y and (Sr 1.8 La 0.2 )(GaFe)O 5.1 solid solutions with the perovskite and brownmillerite structures have been prepared from salt solutions by sol-gel processing at temperatures from 570 to 870 K. Ceramic coatings up to 100 μm in thickness have been produced by applying suspensions of the sol-gel powders to various substrates. The structure and microstructure of the ceramic coatings have been studied by X-ray diffraction and scanning electron microscopy [ru

  10. Sol-gel/hydrothermal synthesis of mixed metal oxide of Titanium and ...

    African Journals Online (AJOL)

    Mixed metal oxides of titanium and zinc nanocomposites were prepared through sol-gel method under hydrothermal condition using titanium oxy-(1, 2 - pentadione) and zinc acetate without hazardous additives. The resulting composites were characterized by X-Ray Diffractometer (XRD), Scanning Electron Microscope ...

  11. Sol-gel auto-combustion synthesis of hydroxyapatite nanotubes array in porous alumina template

    International Nuclear Information System (INIS)

    Yuan Yuan; Liu Changsheng; Zhang Yuan; Shan Xiaoqian

    2008-01-01

    In this paper, an array of highly ordered hydroxyapatite (HAP) nanotubes was synthesized by sol-gel auto-combustion method with porous anodic aluminum oxide (AAO) template for the first time. Based on thermogravimetry (DTA/TG), Fourier transform infrared (FTIR) and X-ray diffraction (XRD), the dried gel, derived from the sol solution with Ca(NO 3 ) 2 .4H 2 O and PO(CH 3 O) 3 as precursors and ethylene glycol as the polymeric matrix, exhibited a typical self-propagating combustion behavior at low temperature, directly resulting in hexagonal crystalline HAP materials. The resultant HAP arrays fabricated from the above sol-gel in the AAO template were uniformly distributed, highly ordered nanotubes with uniform length and diameter according to the observations of scanning electron microscopy (SEM) and transmission electron microscope (TEM). The electron diffraction (ED), XRD and X-ray photoelectron spectroscopy (XPS) survey proved the formation of HAP phase with polycrystalline structure in the AAO template. Based on these results, a potential mechanism of 'an auto-combustion from dried gel to nanoparticles and a subsequent in situ reaction from nanoparticles to nanotubes' was proposed

  12. Synthesis of nanocrystalline TiO2 by tartarate gel method

    Indian Academy of Sciences (India)

    Unknown

    mixture of tartaric acid and TiOCl2 solution forms a gel on heating on a water bath which decomposes at higher temperatures, > 423 K. During calcination process, a black fluffy mass (foam-like) is formed which occupies large volumes of the furnace. As the temperature increases, the black mass turns to white in colour with ...

  13. Synthesis and characterization of nanocrystalline hydroxyapatite gel and its application as scaffold aggregation

    Directory of Open Access Journals (Sweden)

    Leonardo Ribeiro Rodrigues

    2012-12-01

    Full Text Available The sol-gel process is a technique used to synthesize materials from colloidal suspensions and, therefore, is suitable for preparing materials in the nanoscale. In this work hydroxyapatite was used due to its known properties in tissue engineering. Hydroxyapatite Ca10(PO46(OH2 is a bioactive ceramic which is found in the mineral phase of bone tissue and is known for its great potential in tissue engineering applications. For this reason, this material can be applied as particle aggregates on ceramic slurry, coating or film on materials with a poorer biological response than hydroxyapatite. In this work, hydroxyapatite gel was obtained by the sol-gel process and applied as nanoparticle aggregation in the mixture of hydroxyapatite and tricalcium phosphate to form a ceramic slurry. This process is the polymer foam replication technique used to produce scaffolds, which are used in tissue engineering. For HA gel characterization it was used enviromental scanning electron microscopy (ESEM, transmission electron microscopy (TEM, electron energy loss spectroscopy (EELS, scanning electron microscopy (SEM, X-ray diffraction (XRD and X-ray fluorescence (XRF. The crystallite size was calculated from XRD data using the Scherrer equation. The nanoparticles size before firing was approximately 5nm. The crystallite size calculated after calcination was approximately 63 nm. The EELS results showed that calcium phosphate was obtained before firing. After HA gel calcination at 500 ºC the XRD results showed hydroxyapatite with a small content of beta-TCP. The scaffolds obtained by polymer foam replication technique showed a morphology with adequate porosity for tissue engineering.

  14. Identification of TiO2 clusters present during synthesis of sol-gel derived TiO2 nano-particles

    DEFF Research Database (Denmark)

    Simonsen, Morten Enggrob; Søgaard, Erik Gydesen

    Synthesis of titanium dioxide nanoparticles with controlled size distribution and morphology are of great interest for many applications i.e. photocatalysis and dye sensitized solar cells (DSSC). The sol-gel method has some advantages over other preparation techniques in the many parameters, whic...

  15. Inorganic polyphosphate in the yeast Saccharomyces cerevisiae with a mutation disturbing the function of vacuolar ATPase.

    Science.gov (United States)

    Tomaschevsky, A A; Ryasanova, L P; Kulakovskaya, T V; Kulaev, I S

    2010-08-01

    A mutation in the vma2 gene disturbing V-ATPase function in the yeast Saccharomyces cerevisiae results in a five- and threefold decrease in inorganic polyphosphate content in the stationary and active phases of growth on glucose, respectively. The average polyphosphate chain length in the mutant cells is decreased. The mutation does not prevent polyphosphate utilization during cultivation in a phosphate-deficient medium and recovery of its level on reinoculation in complete medium after phosphate deficiency. The content of short chain acid-soluble polyphosphates is recovered first. It is supposed that these polyphosphates are less dependent on the electrochemical gradient on the vacuolar membrane.

  16. Synthesis and Characterization of Oxide Dispersion Strengthened Ferritic Steel via a Sol-Gel Route

    International Nuclear Information System (INIS)

    Sun Qinxing; Zhang Tao; Wang Xianping; Fang Qianfeng; Hu Jing; Liu Changsong

    2012-01-01

    Nanocrystalline oxide dispersion strengthened (ODS) ferritic steel powders with nominal composition of Fe-14Cr-3W-0.3Ti-0.4Y 2 O 3 are synthesized using sol-gel method and hydrogen reduction. At low reduction temperature the impurity phase of CrO is detected. At higher reduction temperature the impurity phase is Cr 2 O 3 which eventually disappears with increasing reduction time. A pure ODS ferritic steel phase is obtained after reducing the sol-gel resultant products at 1200°C for 3 h. The HRTEM and EDS mapping indicate that the Y 2 O 3 particles with a size of about 15 nm are homogenously dispersed in the alloy matrix. The bulk ODS ferritic steel samples prepared from such powders exhibit good mechanical performance with an ultimate tensile stress of 960 MPa.

  17. Zr alkoxide chain effect on the sol-gel synthesis of lithium metazirconate

    International Nuclear Information System (INIS)

    Pfeiffer, Heriberto; Bosch, Pedro; Bulbulian, Silvia

    2003-01-01

    Lithium metazirconate (Li 2 ZrO 3 ) was synthesized by the sol-gel method, using four different Zr alkoxides: zirconium ethoxide, zirconium iso-propoxide, zirconium propoxide and zirconium butoxide. The syntheses were made under two different catalytic regimes, acid and basic. The resulting powders were mixtures of Li 2 ZrO 3 and ZrO 2 . The best yield of Li 2 ZrO 3 (100%) was obtained when the sol-gel reaction was developed with lithium methoxide and zirconium ethoxide under acid catalysis regime. This study establishes that, for base-catalyzed reactions the ZrO 2 formation decreases when the alkyl-chain increases in the alkoxides. By contrast, for acid-catalyzed reactions the ZrO 2 formation increases as the alkyl-chain increases. Finally, when Zr propoxide and Zr iso-propoxide were used, the Li 2 ZrO 3 amounts were different due to steric effects

  18. Synthesis of Fe Ni Alloy Nano materials by Proteic Sol-Gel Method: Crystallographic, Morphological, and Magnetic Properties

    International Nuclear Information System (INIS)

    Santos, C.M.D.; Martins, A.F.N.; Sasaki, J.M.; Costa, B. C.; Ribeiro, T.S.; Braga, T.P.; Soares, J.M.

    2016-01-01

    Proteic Sol-Gel method was used for the synthesis of Fe Ni alloy at different temperature conditions and flow reduction. The solids were characterized by XRD, H_2-TPR, SEM, TEM, Moessbauer spectroscopy, and VSM. It was observed by X-ray diffraction pure Fe Ni alloy in the samples reduced at 600 degree (40 ml/min H_2 flow) and 700 degree (25 ml/min H_2 flow). The Fe Ni alloy presented stability against the oxidizing atmosphere up to 250 degree. The morphology exhibited agglomerates relatively spherical and particles in the range of 10-40 nm. Moessbauer spectroscopy showed the presence of disordered ferromagnetic Fe Ni alloy, and magnetic hysteresis loop revealed a typical behavior of soft magnetic material.

  19. Trimetallic oxide nanocomposites of transition metals titanium and vanadium by sol-gel technique: synthesis, characterization and electronic properties

    Science.gov (United States)

    Kumar, Amit; Mishra, Neeraj Kumar; Sachan, Komal; Ali, Md Asif; Soaham Gupta, Sachchidanand; Singh, Rajeev

    2018-04-01

    Novel titanium and vanadium based trimetallic oxide nanocomposites (TMONCs) have been synthesized using metal salts of titanium-vanadium along with three others metals viz. tin, aluminium and zinc as precursors by the sol-gel method. Aqueous ammonia and hydrazine hydrate were used as the reducing agents. The preparations of nanocomposites were monitored by observing the visual changes during each step of synthesis. The synthesized TMONCs were characterized using UV–vis, SEM, EDX, TEM and DLS. Band gap of the synthesized TMONCs ranges from 3–4.5 eV determined using tauc plot. FTIR study revealed the molecular stretching and bending peaks of corresponding M–O/M–O–M bonds thus confirming their formation. Molecular composition and particle size were determined using EDX and DLS respectively. Molecular shape, size and surface morphology have been examined by SEM and TEM.

  20. Synthesis of FeNi Alloy Nanomaterials by Proteic Sol-Gel Method: Crystallographic, Morphological, and Magnetic Properties

    Directory of Open Access Journals (Sweden)

    Cássio Morilla dos Santos

    2016-01-01

    Full Text Available Proteic Sol-Gel method was used for the synthesis of FeNi alloy at different temperature conditions and flow reduction. The solids were characterized by XRD, H2-TPR, SEM, TEM, Mössbauer spectroscopy, and VSM. It was observed by X-ray diffraction pure FeNi alloy in the samples reduced at 600°C (40 mL/min H2 flow and 700°C (25 mL/min H2 flow. The FeNi alloy presented stability against the oxidizing atmosphere up to 250°C. The morphology exhibited agglomerates relatively spherical and particles in the range of 10–40 nm. Mössbauer spectroscopy showed the presence of disordered ferromagnetic FeNi alloy, and magnetic hysteresis loop revealed a typical behavior of soft magnetic material.

  1. Sol-gel synthesis of 45S5 bioglass – Prosthetic coating by electrophoretic deposition

    Directory of Open Access Journals (Sweden)

    Faure Joel

    2013-11-01

    Full Text Available In this work, the 45S5 bioactive glass has been prepared by the sol-gel process using an organic acid catalyst instead of nitric acid usually used. The physico-chemical and structural characterizations confirmed and validated the elemental composition of the resulting glass. In addition, the 45S5 bioactive glass powder thus obtained was successfully used to elaborate by electrophoretic deposition a prosthetic coating on titanium alloy Ti6Al4V.

  2. Synthesis of Sol-Gel Precursors for Ceramics from Lunar and Martian Soil Simulars

    Science.gov (United States)

    Sibille, L.; Gavira-Gallardo, J. A.; Hourlier-Bahloul, D.

    2004-01-01

    Recent NASA mission plans for the human exploration of our Solar System has set new priorities for research and development of technologies necessary to enable a long-term human presence on the Moon and Mars. The recovery and processing of metals and oxides from mineral sources on other planets is under study to enable use of ceramics, glasses and metals by explorer outposts. We report initial results on the production of sol-gel precursors for ceramic products using mineral resources available in martian or lunar soil. The presence of SO2, TiO2, and Al2O3 in both martian (44 wt.% SiO2, 1 wt.% TiO2, 7 wt.% Al2O3) and lunar (48 wt.% SiO2, 1.5 wt.% TiO2, 16 wt.% Al2O3) soils and the recent developments in chemical processes to solubilize silicates using organic reagents and relatively little energy indicate that such an endeavor is possible. In order to eliminate the risks involved in the use of hydrofluoric acid to dissolve silicates, two distinct chemical routes are investigated to obtain soluble silicon oxide precursors from lunar and martian soil simulars. Clear solutions of sol-gel precursors have been obtained by dissolution of silica from lunar soil similar JSC-1 in basic ethylene glycol (C2H4(OH)2) solutions to form silicon glycolates. Similarly, sol-gel solutions produced from martian soil simulars reveal higher contents of iron oxides. Characterization of the precursor molecules and efforts to further concentrate and hydrolyze the products to obtain gel materials will be presented for evaluation as ceramic precursors.

  3. Synthesis of polymeric fluorinated sol–gel precursor for fabrication of superhydrophobic coating

    International Nuclear Information System (INIS)

    Li, Qianqian; Yan, Yuheng; Yu, Miao; Song, Botao; Shi, Suqing; Gong, Yongkuan

    2016-01-01

    Graphical abstract: - Highlights: • A polymeric fluorinated sol–gel precursor PFT is designed to fabricate superhydrophobic coatings. • The superhydrophobicity could be governed by the concentration of PFT. • Bio-mimicking self-cleaning property similar to lotus leaves could also be achieved. - Abstract: A fluorinated polymeric sol–gel precursor (PFT) is synthesized by copolymerization of 2,3,4,5,5,5-hexafluoro-2,4-bis(trifluorinated methyl)pentyl methacrylate (FMA) and 3-methacryloxypropyltrimethoxysilane (TSMA) to replace the expensive long chain fluorinated alkylsilanes. The fluorinated silica sol is prepared by introducing PFT as co-precursor of tetraethyl orthosilicate (TEOS) in the sol–gel process with ammonium hydroxide as catalyst, which is then used to fabricate superhydrophobic coating on glass substrate through a simple dip-coating method. The effects of PFT concentrations on the chemical structure of the formed fluorinated silica, the surface chemical composition, surface morphology, wetting and self-cleaning properties of the resultant fluorinated silica coatings were studied by using X-ray powder diffraction (XRD), Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectrophotometer (XPS), scanning electron microscopy (SEM) and water contact angle measurements (WCA). The results show that the fluorinated silica sols are successfully obtained. The size and size distribution of the fluorinated silica particles are found greatly dependent on the concentration of PFT, which play a crucial role in the surface morphology of the corresponding fluorinated silica coatings. The suitable PFT concentration added in the sol–gel stage, i.e. for F-sol-1 and F-sol-2, is helpful to achieve both the low surface energy and multi-scaled microstructures, leading to the formation of the superhydrophobic coatings with bio-mimicking self-cleaning property similar to lotus leaves.

  4. Synthesis of Sol-Gel Precursors for Ceramics from Lunar and Martian Soil Simulars

    Science.gov (United States)

    Sibille, L.; Gavira-Gallardo, J. A.; Hourlier-Bahloul, D.

    2003-01-01

    Recent NASA mission plans for the human exploration of our Solar System has set new priorities for research and development of technologies necessary to enable a long-term human presence on the Moon and Mars. The recovery and processing of metals and oxides from mineral sources on other planets is under study to enable use of ceramics, glasses and metals by explorer outposts. We report initial results on the production of sol-gel precursors for ceramic products using mineral resources available in martian or lunar soil. The presence of SiO2, TiO2, and Al2O3 in both martian (44 wt.% SiO2, 1 wt.% TiO2,7 wt.% Al2O3) and lunar (48 wt.% SiO2, 1.5 wt.% TiO2, 16 wt.% Al2O3) soils and the recent developments in chemical processes to solubilize silicates using organic reagents and relatively little energy indicate that such an endeavor is possible. In order to eliminate the risks involved in the use of hydrofluoric acid to dissolve silicates, two distinct chemical routes are investigated to obtain soluble silicon oxide precursors from lunar and martian soil simulars. Clear solutions of sol-gel precursors have been obtained by dissolution of silica from lunar soil simular in basic ethylene glycol (C2H4(OH)2) solutions to form silicon glycolates. Similarly, sol-gel solutions produced from martian soil simulars reveal higher contents of iron oxides. The elemental composition and structure of the precursor molecules were characterized. Further concentration and hydrolysis of the products was performed to obtain gel materials for evaluation as ceramic precursors.

  5. Sol-gel synthesis of lithium metatitanate as tritium breeding material under different sintering conditions

    Science.gov (United States)

    Lu, Wei; Wang, Jing; Pu, Wenjing; Li, Kaiping; Ma, Shubing; Wang, Weihua

    2018-04-01

    Lithium metatitanate (Li2TiO3) is a promising tritium breeding material candidate for solid blanket of D-T fusion reactors, due to its high mechanical strength, chemical stability, and tritium release rate. In this paper, Li2TiO3 powder with homogeneous crystal structure is synthesized by sol-gel method. The chemical reactions in gel thermal cracking and sintering process are studied by thermo gravimetric/differential scanning calorimetry (TG-DSC). The relationship between the sintering condition and the particle/grain size is characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results show that below 673 K the gel precursor is completely decomposed and Li2TiO3 phase initially forms. The LiTiO2 by-product formed under the reductive atmosphere in muffle furnace, could be oxidized continually to Li2TiO3 at higher sintering temperature (≥1273 K) for longer sintering time (≥10 h). Both grain and particle sizes rely on a linear growth with the increase of sintering time at 1273 K. Over 1473 K, significant agglomerations exist among particles. The optimal sintering condition is selected as 1273 K for 10 h, for the purer Li2TiO3 phase (>99%), smaller grain and particle size.

  6. Water-based sol-gel synthesis of hydroxyapatite: process development.

    Science.gov (United States)

    Liu, D M; Troczynski, T; Tseng, W J

    2001-07-01

    Hydroxyapatite (HA) ceramics were synthesized using a sol-gel route with triethyl phosphite and calcium nitrate as phosphorus and calcium precursors, respectively. Two solvents, water and anhydrous ethanol, were used as diluting media for HA sol preparation. The sols were stable and no gelling occurred in ambient environment for over 5 days. The sols became a white gel only after removal of the solvents at 60 degrees C. X-ray diffraction showed that apatitic structure first appeared at a temperature as low as 350 degrees C. The crystal size and the HA content in both gels increase with increasing calcination temperature. The type of initial diluting media (i.e., water vs. anhydrous ethanol) did not affect the microstructural evolution and crystallinity of the resulting HA ceramic. The ethanol-based sol dip-coated onto a Ti substrate, followed by calcination at 450 degrees C, was found to be porous with pore size ranging from 0.3 to 1 microm. This morphology is beneficial to the circulation of physiological fluid when the coating is used for biomedical applications. The satisfactory adhesion between the coating and substrate suggests its suitability for load-bearing uses.

  7. MICROSTRUCTURE CHARACTERISTIC OF ALUMINUM TITANATE SYNTHESIED BY BOTH SOLID- STATE AND SOL-GEL PROCESSES

    Directory of Open Access Journals (Sweden)

    M. Khosravi Saghezchi

    2015-12-01

    Full Text Available A comparing study on formation and microstructure features of aluminum titanate is investigated through both solid-state and sol-gel processes. Aluminum titanate formed by firing at 1350ºC and 1450ºC for 4h in solid-state process. In the sol-gel process formation of submicron sized particles is followed by addition of sucrose into the transparent sol. XRD analysis was confirmed the formation of aluminum titanate at 1400ºC  in lower duration of calcination (3h without any additives in the sol-gel process. In this work 2wt% MgO is added to the samples as the additive for forming acceleration of aluminum titanate. The influence of MgO addition and heat treatment are studied on phase formation and microstructure development of aluminum titanate in both procedures. Additive optimizes aluminum titanate formation at lower temperatures (1300-1350ºC. Phase and microstructure studies of Mg containing samples optimally show significance in aluminum titanate formation.

  8. Hybrid titanium dioxide/PS-b-PEO block copolymer nanocomposites based on sol-gel synthesis

    International Nuclear Information System (INIS)

    Gutierrez, J; Tercjak, A; Garcia, I; Peponi, L; Mondragon, I

    2008-01-01

    The poly(styrene)-b-poly(ethylene oxide) (SEO) amphiphilic block copolymer, with two different molecular weights, has been used as a structure directing agent for generating nanocomposites of TiO 2 /SEO via the sol-gel process. SEO amphiphilic block copolymers are designed with a hydrophilic PEO-block which can interact with inorganic molecules, as well as a hydrophobic PS-block which builds the matrix. The addition of different amounts of sol-gel provokes strong variations in the self-assembled morphology of TiO 2 /SEO nanocomposites with respect to the neat block copolymer. As confirmed by atomic force microscopy (AFM), TiO 2 /PEO-block micelles get closer, forming well-ordered spherical domains, in which TiO 2 nanoparticles constitute the core surrounded by a corona of PEO-blocks. Moreover, for 20 vol% sol-gel the generated morphology changes to a hexagonally ordered structure for both block copolymers. The cylindrical structure of these nanocomposites has been confirmed by the two-dimensional Fourier transform power spectrum of the corresponding AFM height images. Affinity between titanium dioxide precursor and PEO-block of SEO allows us to generate hybrid inorganic/organic nanocomposites, which retain the optical properties of TiO 2 , as evaluated by UV-vis spectroscopy

  9. Synthesis and characterization of nanocrystalline hydroxyapatite gel and its application as scaffold aggregation

    OpenAIRE

    Rodrigues, Leonardo Ribeiro; d` Ávila, Marcos Akira; Monteiro, Fernando Jorge Mendes; Zavaglia, Cecília Amélia de Carvalho

    2012-01-01

    The sol-gel process is a technique used to synthesize materials from colloidal suspensions and, therefore, is suitable for preparing materials in the nanoscale. In this work hydroxyapatite was used due to its known properties in tissue engineering. Hydroxyapatite Ca10(PO4)6(OH)2 is a bioactive ceramic which is found in the mineral phase of bone tissue and is known for its great potential in tissue engineering applications. For this reason, this material can be applied as particle aggregates o...

  10. Low-temperature sol-gel synthesis of NaZr2P3O12

    International Nuclear Information System (INIS)

    Agrawal, D.K.; Adair, J.H.

    1990-01-01

    The NZP family of new low-expansion materials has attracted wide interest for its potential in advanced technological applications. NaZr 2 P 3 O 12 , which is the parent composition of this family, has been synthesized by the solution sol-gel method using special precursor solutions, which led to its formation (although poorly crystalline) at temperatures as low as 120 degrees C. The lowest temperature of formation of a single phase of NaZr 2 P 3 O 12 with a high degree of crystallinity was found to be 600 degrees C

  11. Synthesis of Titania-supported Copper Nanoparticles via Refined Alkoxide Sol-gel Process

    International Nuclear Information System (INIS)

    Wu, Jeffrey C.S.; Tseng, I.-Hsiang; Chang, W.-C.

    2001-01-01

    Nanoparticles of titania and copper-loaded titania were synthesized by a refined sol-gel method using titanium butoxide. Unlike the conventional sol-gel procedure of adding water directly, the esterification of anhydrous butanol and glacial acetic acid provided the hydrolyzing water. In addition, acetic acid also served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titania. Following the hydrolysis, Cu/TiO 2 was prepared by adding copper chloride to titania sol. The sol was dried, then calcined at 500 deg. C to remove organics and transformed to anatase titania which was verified by XRD. Cu/TiO 2 was further hydrogen-reduced at 300 deg. C. The recovery of Ti was exceeded by an average of 95% from titanium butoxide. TEM micrographs show that the Cu/TiO 2 particles are near uniform. The average crystallite sizes are 17-20 nm estimated from the peak broadening of XRD spectra. The bandgaps of TiO 2 and reduced Cu/TiO 2 range from 2.70 to 3.15 eV estimated from the diffusive reflective UV-Vis spectra. XPS analysis shows that Cu 2p 3/2 is 933.4 eV indicating primary Cu 2 O form on the TiO 2 supports. The binding energy of Ti does not exhibit chemical shift suggesting negligible interaction of Cu cluster and TiO 2 support

  12. Synthesis of hybrid chitosan/calcium aluminosilicate using a sol-gel method for optical applications

    Energy Technology Data Exchange (ETDEWEB)

    Elnahrawy, Amany Mohamed [Department of Solid State, Physics Division, National Research Center (NRC), Giza 12622, Cairo (Egypt); Kim, Yong Soo, E-mail: yskim2@ulsan.ac.kr [Department of Physics and Energy Harvest-Storage Research Center (EHSRC), University of Ulsan, Ulsan 44610 (Korea, Republic of); Ali, Ahmed I., E-mail: Ahmed_ali_2010@helwan.edu.eg [Department of Physics and Energy Harvest-Storage Research Center (EHSRC), University of Ulsan, Ulsan 44610 (Korea, Republic of); Basic Science Department, Faculty of Industrial Education & Technology, Helwan University, Cairo 11281 (Egypt)

    2016-08-15

    Hybrid chitosan (CS)/calcium aluminosilicate nanocomposites thin films and membranes were prepared using a sol–gel method with three different concentrations of Al{sub 2}O{sub 3} (5, 7 and 10 mol. %). The prepared nanocomposites were characterized by transmission electron microscopy, X-ray diffraction and Fourier Transform Infrared spectroscopy. The optical properties of the prepared samples were analyzed by UV/Vis spectrophotometry and photoluminescence (PL) spectroscopy. The optical parameters revealed an increase in both the refractive index and band gap of the nanocomposites with increasing Al concentration. In addition, the PL spectra revealed a blue shift that was consistent with an increase in the optical band gap. These results suggest that CS/calcium aluminosilicate in two different forms can be a good candidate for optical sensors applications. - Highlights: • We show a large specific surface area of hybrid CS/calcium aluminosilicate thin films and membranes using sol-gel method. • Inorganic SiO{sub 2}-based phase are perfectly embedded onto chitosan matrix has a reliable stability. • CS/calcium aluminosilicate could be usable for optical sensors, planar waveguide, and bio-sensing.

  13. Sol–gel synthesis of nanostructured indium tin oxide with controlled morphology and porosity

    Energy Technology Data Exchange (ETDEWEB)

    Kőrösi, László, E-mail: ltkorosi@gmail.com [Department of Biotechnology, Nanophage Therapy Center, Enviroinvest Corporation, Kertváros u. 2, H-7632 Pécs (Hungary); Scarpellini, Alice [Department of Nanochemistry, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Petrik, Péter [Institute for Technical Physics and Materials Science, Konkoly-Thege út 29-33, H-1121 Budapest (Hungary); Papp, Szilvia [Department of Biotechnology, Nanophage Therapy Center, Enviroinvest Corporation, Kertváros u. 2, H-7632 Pécs (Hungary); Dékány, Imre [MTA-SZTE Supramolecular and Nanostructured Materials Research Group, University of Szeged, Dóm tér 8, H-6720 Szeged (Hungary)

    2014-11-30

    Graphical abstract: - Highlights: • Nanocrystalline ITO thin films and powders were prepared by a sol–gel method. • The nature of the compounds used for hydrolysis plays a key role in the morphology. • Hydrolysis of In{sup 3+}/Sn{sup 4+} with EA led to a rod-like morphology. • Monodisperse spherical ITO nanoparticles were obtained on the use of AC. • ITO{sub E}A was highly porous, while ITO{sub A}C contained densely packed nanocrystals. - Abstract: Nanostructured indium tin oxide (ITO) powders and thin films differing in morphology and porosity were prepared by a sol–gel method. In{sup 3+} and Sn{sup 4+} were hydrolyzed in aqueous medium through the use of ethanolamine (EA) or sodium acetate (AC). X-ray diffraction measurements demonstrated that both EA and AC furnished indium tin hydroxide, which became nanocrystalline after aging for one day. The indium tin hydroxide samples calcined at 550 °C afforded ITO with a cubic crystal structure, but the morphology differed significantly, depending on the agent used for hydrolysis. Electron microscopy revealed the formation of round monodisperse nanoparticles when AC was used, whereas the application of EA led to rod-like ITO nanoparticles. Both types of nanoparticles were suitable for the preparation of transparent and conductive ITO thin films. The influence of the morphology and porosity on the optical properties is discussed.

  14. Synthesis and characterization of CdO nano particles by the sol-gel method

    Science.gov (United States)

    Vadgama, V. S.; Vyas, R. P.; Jogiya, B. V.; Joshi, M. J.

    2017-05-01

    Cadmium Oxide (CdO) is an inorganic compound and one of the main precursors to other cadmium compounds. It finds applications in cadmium plating, storage batteries, in transparent conducting film, etc. Here, an attempt is made to synthesize CdO nano particles by sol-gel technique. The gel was prepared using cadmium nitrate tetra hydrate (Cd(NO3)2.4H2O) and aqueous ammonium hydroxide (NH4OH) as a precursor. The synthesized powder is further characterized by techniques like Powder X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and Thermal gravimetric analysis (TGA). Powder XRD analysis suggested the nano-crystalline nature of the sample with the cubic crystal system. Nano scaled particles of spherical morphology with the size ranging from 50-100 nm are observed from TEM images. While, FT-IR study is used to confirm the presence of different functional groups. Thermo-gravimetric analysis suggests the highly thermally stable nature of the samples. The results are discussed.

  15. Synthesis of ZnO-CuO Nanocomposite Aerogels by the Sol-Gel Route

    Directory of Open Access Journals (Sweden)

    Rula M. Allaf

    2014-01-01

    Full Text Available The epoxide addition sol-gel method has been utilized to synthesize porous zinc-copper composite aerogels in the zinc-to-copper molar ratios of 50 : 50 to 90 : 10. A two-step mixing approach has been employed to produce aerogels composed of nano- to micrometer sized particles. The aerogels were characterized by ultrahigh resolution scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction. The as-synthesized aerogels had a thin flake- or petal-like microstructure comprised of clustered flakes on two size scales; they were identified as being crystalline with the crystalline species identified as copper nitrate hydroxide, zinc hydroxide chloride hydrate, and zinc hydroxide nitrate hydrate. Annealing of the aerogel materials at a relatively low temperature (400°C resulted in a complete phase transition of the material to give highly crystalline ZnO-CuO aerogels; the aerogels consisted of networked nanoparticles in the ~25–550 nm size range with an average crystallite size of ~3 nm and average crystallinity of 98%. ZnO-CuO aerogels are of particular interest due to their particular catalytic and sensing properties. This work emphasizes the versatility of this sol-gel route in synthesizing aerogels; this method offers a possible route for the fabrication of aerogels of different metal oxides and their composites.

  16. Synthesis of Titania-supported Copper Nanoparticles via Refined Alkoxide Sol-gel Process

    Science.gov (United States)

    Wu, Jeffrey C. S.; Tseng, I.-Hsiang; Chang, Wan-Chen

    2001-06-01

    Nanoparticles of titania and copper-loaded titania were synthesized by a refined sol-gel method using titanium butoxide. Unlike the conventional sol-gel procedure of adding water directly, the esterification of anhydrous butanol and glacial acetic acid provided the hydrolyzing water. In addition, acetic acid also served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titania. Following the hydrolysis, Cu/TiO2 was prepared by adding copper chloride to titania sol. The sol was dried, then calcined at 500°C to remove organics and transformed to anatase titania which was verified by XRD. Cu/TiO2 was further hydrogen-reduced at 300°C. The recovery of Ti was exceeded by an average of 95% from titanium butoxide. TEM micrographs show that the Cu/TiO2 particles are near uniform. The average crystallite sizes are 17-20 nm estimated from the peak broadening of XRD spectra. The bandgaps of TiO2 and reduced Cu/TiO2 range from 2.70 to 3.15 eV estimated from the diffusive reflective UV-Vis spectra. XPS analysis shows that Cu 2p3/2 is 933.4 eV indicating primary Cu2O form on the TiO2 supports. The binding energy of Ti does not exhibit chemical shift suggesting negligible interaction of Cu cluster and TiO2 support.

  17. Synthesis and characterization of NiO nanopowder by sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Ningsih, Sherly Kasuma Warda [Department of Chemistry, Faculty of Mathematics and Natural Sciences Padang State University, Kampus Air Tawar, Jl. Prof. Dr. Hamka, West Sumatera, 25161, Indonesia Email: sherly-kasuma@yahoo.com (Indonesia)

    2015-09-30

    Preparation of nickel oxide (NiO) nanopowder by sol-gel process has been studied. NiO nanopowders were obtained by sol-gel method by using nickel nitrate hexahydrate and sodium hydroxide and aquadest were used as precursor, agent precipitator and solvent, respectively. The powders were formed by drying at 110°C and followed by heating in the furnace at 400°C for 1.5 hours. The product was obtained black powder. The product was characterized by Energy Dispesive X-ray Fluorescence (ED-XRF), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The ED-XRF pattern shows the composition of NiO produced was 97.1%. The XRD pattern showed NiO forms were produced generally in monoclinic stucture. The crystalline size of NiO was obtained in the range 40-85 nm. SEM micrograph clearly showed that powder had a spherical with uniform distribution size is 0.1-1.0 µm approximately.

  18. Sol-Gel Synthesis and Characterization of Cubic Bismuth Zinc Niobium Oxide Nanopowders

    Directory of Open Access Journals (Sweden)

    Ganchimeg Perenlei

    2014-01-01

    Full Text Available Bismuth zinc niobium oxide (BZN was successfully synthesized by a diol-based sol-gel reaction utilizing metal acetate and alkoxide precursors. Thermal analysis of a liquid suspension of precursors suggests that the majority of organic precursors decompose at temperatures up to 150°C, and organic free powders form above 350°C. The experimental results indicate that a homogeneous gel is obtained at about 200°C and then converts to a mixture of intermediate oxides at 350–400°C. Finally, single-phased BZN powders are obtained between 500 and 900°C. The degree of chemical homogeneity as determined by X-ray diffraction and EDS mapping is consistent throughout the samples. Elemental analysis indicates that the atomic ratio of metals closely matches a Bi1.5ZnNb1.5O7 composition. Crystallite sizes of the BZN powders calculated from the Scherrer equation are about 33–98 nm for the samples prepared at 500–700°C, respectively. The particle and crystallite sizes increase with increased sintering temperature. The estimated band gap of the BZN nanopowders from optical analysis is about 2.60–2.75 eV at 500-600°C. The observed phase formations and measured results in this study were compared with those of previous reports.

  19. Surfactant-assisted sol–gel synthesis of forsterite nanoparticles as a novel drug delivery system

    Energy Technology Data Exchange (ETDEWEB)

    Hassanzadeh-Tabrizi, S.A., E-mail: tabrizi1980@gmail.com [Young Researchers and Elite Club, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan (Iran, Islamic Republic of); Bigham, Ashkan [Advanced Materials Research Center, Materials Engineering Department, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan (Iran, Islamic Republic of); Rafienia, Mohammad [Biosensor Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of)

    2016-01-01

    In the present study, forsterite nanoparticles were synthesized via surfactant-assisted sol–gel method using cetyltrimethyl ammonium bromide (CTAB) as a surfactant. The effects of CTAB contents and heat treatment on the textural properties and drug release from nanoparticles were investigated. The synthesized powders were studied by X-ray diffraction, Fourier transform infrared spectra, Brunauer–Emmett–Teller surface area analysis and transmission electron microscope images. Mg{sub 2}SiO{sub 4} materials demonstrated mesoporous characteristics and large specific surface area ranging from 159 to 30 m{sup 2}/g. The TEM results showed that forsterite nanorods had diameters about 4 nm and lengths ranging from 10 to 60 nm. It was found that the samples with 6 g CTAB show slower drug release rate than the other specimens, which is due to smaller pore size. This study revealed that the drug delivery of forsterite can be tailored by changing the amount of surfactant. - Highlights: • Forsterite nanoparticles were synthesized via surfactant-assisted sol–gel method. • Nanoparticles were loaded with ibuprofen as a novel drug delivery system. • Synthesized nanoparticles had a rod-like morphology. • CTAB concentration strongly affected the textural properties and drug release of the nanoparticles.

  20. Synthesis and characterization of cds-p (nipam-co-maa) hybrid micro gels

    International Nuclear Information System (INIS)

    Khan, M.S.; Khan, G.T.; Khan, A.

    2014-01-01

    Copolymer containing both pH and thermo sensitive properties are very much interesting due to their broad nature to various stimuli. Further, the incorporation of inorganic nanoparticles into stimuli responsive copolymers enhances their utility in different applied nature properties. In the present work such an attempt is made to synthesize copolymer of N-isopropyl acrylamide (NIPAM) and Methacrylic acid (MAA) with CdS nanoparticles. The copolymer of N-isopropyl acrylamide (NIPAM) and Methacrylic acid (MAA) was prepared through emulsion polymerization technique with various compositions and characterized by Fourier transform infrared spectroscopy (FTIR). The microspheres thus prepared were employed as micro-reactors for the deposition of semiconductor cadmium sulfide (CdS) nanoparticles. The obtained composite was characterized using optical, structural and thermal techniques. The micro gels were found to be stable up to 200 degree C. The crystal structure and grain size of Cadmium sulfide-poly (isopropylacrylamide-co-methacrylic acid) (CdS-P(NIPAM-co-MAA)) hybrid micro gels was studied by using X - ray Diffraction. UV Visible spectroscopy and photoluminescence spectroscopy was engaged to get the optical properties of the samples. It was found that the synthesized nanoparticles have a blue shift (higher energy) at about 360 nm which may be due to the typical quantum confinement effects. (author)

  1. Synthesis of LiFePO4/C composites based on natural iron stone using a sol gel method

    Science.gov (United States)

    Angela, Riyan; Islam, Humaatul; Sari, Vamellia; Latif, Chaironi; Zainuri, Mochamad; Pratapa, Suminar

    2017-01-01

    Synthesis of LiFePO4/C composites has been carried out using a sol gel method. The Fe precursor was made from a natural iron stone of Tanah Laut, South Kalimantan, while the other raw materials were commercial Li2CO3 powder and NH4H2PO4 powder with HCl and water as solvents. Citric acid was used as the carbon source in the synthesis. This study used a molar ratio of 1:1:2 for Li:Fe:P with variation of added citric acid of 1.5 and 2.5 g. The solutions were dried in air at 100°C. The dried powders were characterized using DSC-TGA and then calcined at 600 and 700°C under argon environment for 10 hours. The calcined powders were characterized by X-ray diffractometry (XRD), scanning electron microscopy-energy dispersive x-ray (SEM-EDX), and LCR meter. It was found that the samples contained LiFePO4 as the dominant phase and LiFeP2O7 and Fe2O3 as secondary phases. The analysis showed that the addition of citric acid influenced the electronic conductivity of the composites. A Rietveld relative weight fraction of up to 94.7% was achieved in the synthesis at temperature 600°C. The LFP/C sample exhibited electronic conductivity of 4.56×10-3 Scm-1 which was six times of that of the pure LFP.

  2. The enzymatic activity of the VEGFR2 receptor for the biosynthesis of dinucleoside polyphosphates.

    Science.gov (United States)

    Jankowski, Vera; Schulz, Anna; Kretschmer, Axel; Mischak, Harald; Boehringer, Falko; van der Giet, Markus; Janke, Doreen; Schuchardt, Mirjam; Herwig, Ralf; Zidek, Walter; Jankowski, Joachim

    2013-09-01

    The group of dinucleoside polyphosphates encompasses a large number of molecules consisting of two nucleosides which are connected by a phosphate chain of variable length. While the receptors activated by dinucleoside polyphosphates as well as their degradation have been studied in detail, its biosynthesis has not been elucidated so far. Since endothelial cells released the dinucleoside polyphosphate uridine adenosine tetraphosphate (Up4A), we tested cytosolic proteins of human endothelial cells obtained from dermal vessels elicited for enzymatic activity. When incubated with ADP and UDP, these cells showed increasing concentrations of Up4A. The underlying enzyme was isolated by chromatography and the mass spectrometric analysis revealed that the enzymatic activity was caused by the vascular endothelial growth factor receptor 2 (VEGFR2). Since VEGFR2 but neither VEGFR1 nor VEGFR3 were capable to synthesise dinucleoside polyphosphates, Tyr-1175 of VEGFR2 is most likely essential for the enzymatic activity of interest. Further, VEGFR2-containing cells like HepG2, THP-1 and RAW264.7 were capable of synthesising dinucleoside polyphosphates. VEGFR2-transfected HEK 293T/17 but not native HEK 293T/17 cells synthesised dinucleoside polyphosphates in vivo too. The simultaneous biosynthesis of dinucleoside polyphosphates could amplify the response to VEGF, since dinucleoside polyphosphates induce cellular growth via P2Y purinergic receptors. Thus the biosynthesis of dinucleoside polyphosphates by VEGFR2 may enhance the proliferative response to VEGF. Given that VEGFR2 is primarily expressed in endothelial cells, the biosynthesis of dinucleoside polyphosphates is mainly located in the vascular system. Since the vasculature is also the main site of action of dinucleoside polyphosphates, activating vascular purinoceptors, blood vessels appear as an autocrine system with respect to dinucleoside polyphosphates. We conclude that VEGFR2 receptor is capable of synthesising

  3. Sol-gel derived porous bioactive nanocomposites: Synthesis and in vitro bioactivity

    Science.gov (United States)

    Shankhwar, Nisha; Kothiyal, G. P.; Srinivasan, A.

    2013-06-01

    Porous bioactive composites consisting of SiO2-CaO-Na2O-P2O5 bioactive glass-ceramic and synthetic water soluble polymer Polyvinylpyrrolidone [PVP (C6H9NO)n, MW˜40000 g/mol] have been synthesized by sol-gel route. As-prepared polymeric composites were characterized by X-ray diffraction (XRD) technique. Two major bone mineral phases, viz., hydroxyapatite [Ca10(PO4)6(OH)2] and wollastonite [calcium silicate (CaSiO3)] have been identified in the XRD patterns of the composites. Presence of these bone minerals indicates the bioactive nature of the composites. In vitro bioactivity tests confirm bioactivity in the porous composites. The flexibility offered by these bioactive polymer composites is advantageous for its application as implant material.

  4. Sol-Gel Synthesis and Characterization of Selected Transition Metal Nano-Ferrites

    Directory of Open Access Journals (Sweden)

    Aurelija GATELYTĖ

    2011-09-01

    Full Text Available In the present work, the sinterability and formation of nanosized yttrium iron garnet (Y3Fe5O12, yttrium perovskite ferrite (YFeO3, cobalt, nickel and zinc iron spinel (CoFe2O4, NiFe2O4 and ZnFe2O4, respectively powders by an aqueous sol-gel processes are investigated. The metal ions, generated by dissolving starting materials of transition metals in the diluted acetic acid were complexed by 1,2-ethanediol to obtain the precursors for the transition metal ferrite ceramics. The phase purity of synthesized nano-compounds was characterized by infrared spectroscopy (IR and powder X-ray diffraction analysis (XRD. The microstructural evolution and morphological features of obtained transition metal ferrites were studied by scanning electron microscopy (SEM.http://dx.doi.org/10.5755/j01.ms.17.3.598

  5. Bulk synthesis of nanocrystalline urania powders by citrate gel-combustion method

    Science.gov (United States)

    Sanjay Kumar, D.; Ananthasivan, K.; Venkata Krishnan, R.; Amirthapandian, S.; Dasgupta, Arup

    2016-01-01

    Bulk quantities (60 g) of nanocrystalline (nc) free flowing urania powders with crystallite size ranging from 38 to 252 nm have been synthesized for the first time by the citrate gel combustion method. A systematic study of the influence of the fuel (citric acid) to oxidant (nitrate) ratio (R) on the characteristics of the urania powders has been carried out for the first time. Mixture with an "R" value of 0.25 exhibited a vigorous auto-ignition reaction. This reaction was investigated with Differential Scanning Calorimetry (DSC) and in-situ thermogravimetry coupled with differential thermal analysis and mass spectrometry (TG-DTA-MS). The bulk density, specific surface area, X-ray crystallite size, residual carbon and size distribution of particles of this powder were unique. Microscopic and microstructural investigation of selected samples revealed the presence of nanocrystals with irregular exfoliated morphology; their Electron Energy Loss Spectra testified the covalency of the U-O bond.

  6. Synthesis and Characterization of ZnO Nanoparticles Using Sol-gel Process

    Directory of Open Access Journals (Sweden)

    Jayasree ALURI

    2016-05-01

    Full Text Available In the Present work structural, morphological and compositional properties of ZnO nanopowders synthesized using Zinc nitrate and NaOH using sol-gel process were reported. The synthesized nanopowders were further analyzed using X-Ray Diffraction (XRD, Scanning electron microscopy (SEM and Fourier Transform Infrared (FTIR spectroscopic characterizations. Crystalline size and Lattice strain determined from XRD spectra. Morphology of Nanopowders viewed from SEM images observed at different magnifications. The presence of Functional groups analyzed from FTIR spectra. From the results it was very clear that particles synthesized using Zinc nitrate and NaOH plays a vital role on crystalline size, surface morphology of Nanopowders. Synthesized nanopowders can be utilized as building materials in fabrication of various optoelectronic devices including solar cells, LED’s etc. due to its significant structural, morphological and optical properties.

  7. Synthesis and Characterization of Nanostructure Tio2/Anthraquenone (AQ Prepared by Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    Fadhela M. Hussein

    2017-11-01

    Full Text Available sol–gel technique conducted to synthesize nano titanium dioxide with anthraquenone (AQ relatively in acidic pH. Nanoparticles were characterized using techniques like, Scanning Electrion Microscope (SEM, Atomic Force Microscope (AFM, UV-Visible Spectrioscopy, X-ray diffraction (XRD, Fourier transform infrared (FT-IR, SEM picture display that the TiO2/AQ is spherical in style, the band gap of TiO2/AQ nanoparticle is (3.05eV, BET and BJH analysis provides Pore volume and specific Surface area and the kinetic studie Suggest that the reaction is pseudo first order and the rate of reaction was reduce with rising initial concentration for p-Nitrotolune.

  8. Sol-gel synthesis and optical properties of titanium dioxide thin film

    Science.gov (United States)

    Ullah, Irfan; Khattak, Shaukat Ali; Ahmad, Tanveer; Saman; Ludhi, Nayab Ali

    2018-03-01

    The titanium dioxide (TiO2) is synthesized by sol-gel method using titanium-tetra-iso-propoxide (TTIP) as a starting material, and deposited on the pre-cleaned glass substrate using spin coating technique at optimized parameters. Energy dispersive X-ray (EDX) spectroscopy confirms successful TiO2 growth. The optical properties concerning the transmission and absorption spectra show 85% transparency and 3.28 eV wide optical band gap for indirect transition, calculated from absorbance. The exponential behavior of absorption edge is observed and attributed to the localized states electronic transitions, curtailed in the indirect band gap of the thin film. The film reveals decreasing refractive index with increasing wavelength. The photoluminescence (PL) study ascertains that luminescent properties are due to the surface defects.

  9. Synthesis, Consolidation and Characterization of Sol-gel Derived Tantalum-Tungsten Oxide Thermite Composites

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes, O [Univ. of California, Davis, CA (United States)

    2010-06-01

    Energetic composite powders consisting of sol-gel (SG) derived nanostructured tungsten oxide were produced with various amounts of micrometer-scale tantalum fuel metal. Such energetic composite powders were ignition-tested and results show that the powders are not sensitive to friction, spark and/or impact ignition. Initial consolidation experiments, using the High Pressure Spark Plasma Sintering (HPSPS) technique, on the SG derived nanostructured tungsten oxide produced samples with higher relative density than can be achieved with commercially available tungsten oxide. The SG derived nanostructured tungsten oxide with immobilized tantalum fuel metal (Ta - WO3) energetic composite was consolidated to a density of 9.17 g·cm-3 or 93% relative density. In addition, those samples were consolidated without significant pre-reaction of the constituents, thus retaining their stored chemical energy.

  10. Synthesis of Titania-supported Copper Nanoparticles via Refined Alkoxide Sol-gel Process

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jeffrey C.S., E-mail: Cswu@ccms.ntu.edu.tw; Tseng, I.-Hsiang; Chang, W.-C. [National Taiwan University, Department of Chemical Engineering (China)

    2001-06-15

    Nanoparticles of titania and copper-loaded titania were synthesized by a refined sol-gel method using titanium butoxide. Unlike the conventional sol-gel procedure of adding water directly, the esterification of anhydrous butanol and glacial acetic acid provided the hydrolyzing water. In addition, acetic acid also served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titania. Following the hydrolysis, Cu/TiO{sub 2} was prepared by adding copper chloride to titania sol. The sol was dried, then calcined at 500 deg. C to remove organics and transformed to anatase titania which was verified by XRD. Cu/TiO{sub 2} was further hydrogen-reduced at 300 deg. C. The recovery of Ti was exceeded by an average of 95% from titanium butoxide. TEM micrographs show that the Cu/TiO{sub 2} particles are near uniform. The average crystallite sizes are 17-20 nm estimated from the peak broadening of XRD spectra. The bandgaps of TiO{sub 2} and reduced Cu/TiO{sub 2} range from 2.70 to 3.15 eV estimated from the diffusive reflective UV-Vis spectra. XPS analysis shows that Cu 2p{sub 3/2} is 933.4 eV indicating primary Cu{sub 2}O form on the TiO{sub 2} supports. The binding energy of Ti does not exhibit chemical shift suggesting negligible interaction of Cu cluster and TiO{sub 2} support.

  11. Bulk synthesis of nanocrystalline urania powders by citrate gel-combustion method

    International Nuclear Information System (INIS)

    Sanjay Kumar, D.; Ananthasivan, K.; Venkata Krishnan, R.; Amirthapandian, S.; Dasgupta, Arup

    2016-01-01

    Bulk quantities (60 g) of nanocrystalline (nc) free flowing urania powders with crystallite size ranging from 38 to 252 nm have been synthesized for the first time by the citrate gel combustion method. A systematic study of the influence of the fuel (citric acid) to oxidant (nitrate) ratio (R) on the characteristics of the urania powders has been carried out for the first time. Mixture with an “R” value of 0.25 exhibited a vigorous auto-ignition reaction. This reaction was investigated with Differential Scanning Calorimetry (DSC) and in-situ thermogravimetry coupled with differential thermal analysis and mass spectrometry (TG-DTA-MS). The bulk density, specific surface area, X-ray crystallite size, residual carbon and size distribution of particles of this powder were unique. Microscopic and microstructural investigation of selected samples revealed the presence of nanocrystals with irregular exfoliated morphology; their Electron Energy Loss Spectra testified the covalency of the U–O bond. - Highlights: • Bulk quantities of nanocrystalline urania were prepared for the first time using citrate gel combustion method. • Volume combustion was observed in mixtures with fuel to nitrate ratio (R) 0.25. • The value of R was found to significantly influence the characteristics of the final product. • Typical exfoliated microstructure and nanopores were observed. • Established correlation between particle size distribution and bulk density, X-ray crystallite size and lattice strain. • Relationship between fuel to nitrate (R) mole ratio and physical characteristics of powders were also established.

  12. “Non-hydrolytic” sol–gel synthesis of molybdenum sulfides

    Energy Technology Data Exchange (ETDEWEB)

    Leidich, Saskia; Buechele, Dominique; Lauenstein, Raphael; Kluenker, Martin; Lind, Cora, E-mail: cora.lind@utoledo.edu

    2016-10-15

    Non-hydrolytic sol–gel reactions provide a low temperature solution based synthetic approach to solid-state materials. In this paper, reactions between molybdenum chloride and hexamethyldisilthiane in chloroform were explored, which gave access to both MoS{sub 2} and Mo{sub 2}S{sub 3} after heat treatment of as-recovered amorphous samples to 600–1000 °C. Interesting morphologies were obtained for MoS{sub 2}, ranging from fused spherical particles to well-defined nanoplatelets and nanoflakes. Both 2H- and 3R-MoS{sub 2} were observed, which formed thin hexagonal and triangular platelets, respectively. The platelets exhibited thicknesses of 10–30 nm, which corresponds to 15–50 MoS{sub 2} layers. No attempts to prevent agglomeration were made, however, well separated platelets were observed for many samples. Heating at 1000 °C led to formation of Mo{sub 2}S{sub 3} for samples that showed well-defined MoS{sub 2} at lower temperatures, while less crystalline samples had a tendency to retain the MoS{sub 2} structure. - Graphical abstract: Overlay of variable pressure X-ray diffraction data of Al{sub 2}Mo{sub 3}O{sub 12} collected in a diamond anvil cell. Both subtle and discontinuous phase transitions are clearly observed. - Highlights: • Molybdenum sulfides were prepared by non-hydrolytic sol–gel chemistry. • Nanocrystalline 3R-MoS{sub 2} and 2H-MoS{sub 2}, and microcrystalline Mo{sub 2}S{sub 3} were obtained. • Particle morphology correlated strongly with crystalline phases. • Ultrathin platelets with limited tendency to agglomerate were recovered.

  13. Synthesis, structure and electromagnetic properties of Mn–Zn ferrite by sol–gel combustion technique

    International Nuclear Information System (INIS)

    Wang, Wenjie; Zang, Chongguang; Jiao, Qingjie

    2014-01-01

    The electromagnetic absorbing behaviors of a thin coating fabricated by mixing Mn–Zn ferrite with epoxy resin (EP) were studied. The spinel ferrites Mn 1−x Zn x Fe 2 O 4 (x=0.2, 0.5 and 0.8) were synthesized with citrate acid as complex agent by sol–gel combustion method. The microstructure and surface morphology of Mn–Zn ferrite powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The complex permittivity and complex permeability of the fabricated ferrite/EP composites were investigated in terms of their contributions to the absorbing properties in the low frequency (10 MHz to 1 GHz). The microwave absorption of the prepared ferrite/EP composites could be tailored by matching the dielectric loss and magnetic loss and by controlling the doped metal ratio. The composites with the ferrite composition x=0.2 are found to show higher reflection loss compared with the composites with other compositions. It is proposed that the prepared composites can potentially be applied in electromagnetic microwave absorbing field. - Highlights: • We designed and synthesized Mn 1−x Zn x Fe 2 O 4 (x=0.2, 0.5 and 0.8), with citrate acid as complex agent by the sol–gel combustion method. • Citrate acid as the complex agent overcomes the aggregation of ferrite resulting in high purity and homogeneous particles. • We investigated the electromagnetic absorbing performance of a fabricated thin coating by introducing Mn–Zn ferrite into epoxy resin (EP). • The Mn 0.8 Zn 0.2 Fe 2 O 4 composite coatings could achieve the satisfactory absorbing value of −17 dB at 800 MHz. • The prepared composites can potentially be used for the application in electromagnetic microwave absorbing field

  14. Gas-phase acylation of aminopropyl-silica gel in the synthesis of some chemically bonded silica materials for analytical applications

    International Nuclear Information System (INIS)

    Basiuk, Vladimir; Khil'chevskaya, E.G.

    1991-01-01

    Gas-phase acylation of aminopropyl-silica gel with aliphatic dicarboxylic (succinic, adipic and sebacic) and 4-aminobenzoic acids is proposed as a rapid and efficient one-step method for the synthesis of carboxyalkyl- and 4-aminophenylamidopropyl-silica gels, usually used as zwitterion exchangers for liquid chromatography and matrices for multi-step syntheses of silica-bound aromatic azo reagents for the sorption and chromatographic separation of metal ions. Acylation degrees of 59-90% are achieved after 0.5 h. IR spectra of the acylation products and near-UV-visible spectra for bonded aromatic azo compounds, based on 4-aminobenzamidopropyl-silica gel, are presented. Some positive and negative aspects of the gas-phase acylation are discussed. (author). 34 refs.; 2 figs.; 2 tabs

  15. Synthesis and Characterization of ZNO/MN Nanocomposite by using Sol-Gel Method

    Science.gov (United States)

    Ningsih, S. K. W.; Bahrizal, B.; Nasra, E.; Nizar, U. K.; Farisya, R.

    2018-04-01

    Zink oxide doped Mn nanocomposites were synthesized by simple sol-gel method at low temperature by using combination of aquadest with methanol as the solvent and ethylene glycol as the additive. Zink acetate dehydrate and manganese chloride tetrahydrate were used as the precursors. Composition dopants were 1,3,5,and 7%. The crystals were formed by drying at 110°C for 1 hour, after which they were heated at ± 500°C for 2 hours. The as-prepared ZnO/Mn nanocomposites were characterized by X-ray diffraction (XRD) and UV Diffuse Reflectance Spectrometer (UVDRS). The XRD patterns of the ZnO nanocrystals showed that they are mostly hexagonal wurtzite with specific peaks at 2θ = 31, 34, 36, 47, 56, 63, 66 dan 69. The sizes of the ZnO doped Mn particles produced with 1%, 3%, 5% and 7% were18-95; 17-87; 18-96 19-98 nm, respectively. UVDRS analysis showed that the band gap of the ZnO were 2,60; 2,90; 2,99 dan 3,01 eV for 1%, 3%, 5% and 7% Mn respectively.

  16. Synthesis of hydroxyapatite nanoparticles from egg shells by sol-gel method

    Science.gov (United States)

    Azis, Y.; Adrian, M.; Alfarisi, C. D.; Khairat; Sri, R. M.

    2018-04-01

    Hydroxyapatite, [Ca10(PO4)6(OH)2, (HAp)] is widely used in medical fields especially as a bone and teeth substitute. Hydroxyapatite nanoparticles have been succesfully synthesized from egg shells as a source of calcium by using sol-gel method. The egg shells were calcined, hydrated (slaking) and undergone carbonation to form Precipitated Calcium Carbonate (PCC).Then the PCC was added (NH4)2HPO4 to form HAp with variation the mole ratio Ca and P (1.57; 1.67 and 1.77), aging time (24, 48, and 72 hr) and under basic condition pH (9, 10 and 11). The formation of hydroxyapatite biomaterial was characterized using XRD, FTIR, SEM-EDX. The XRD patterns showed that the products were hydroxyapatite crystals. The best result was obtained at 24 hr aging time, pH 9 with hexagonal structure of hydroxyapatite. Particle size of HAp was 35-54 nm and the morphology of hydroxyapatite observed using SEM, it showed that the uniformity crystal of hydroxyapatite.

  17. Effects of PEG4000 template on sol-gel synthesis of porous cerium titanate photocatalyst

    Science.gov (United States)

    Zhang, Wenjie; Tao, Yingjie; Li, Chuanguo

    2018-04-01

    Porous cerium titanate was synthesized by sol-gel method, using polyethylene glycol (PEG4000) as template agent. Brannerite structured CeTi2O6 in monoclinic system is the major substance formed in the materials. Formation of CeO2 and rutile TiO2 depends on the amount of PEG4000. The addition of PEG4000 leads to production of fine particles in the samples, but it does not apparently affect the band gap energy. Pore volume of the cerium titanate sample continuously increases with rising PEG4000 amount. The sample obtained using 3.5 g PEG4000 has BET surface area of 16.2 m2/g and pore volume of 0.0232 cm3/g. The addition of PEG4000 can obviously promote photocatalytic activity of cerium titanate, which can be proven by both enhanced production of hydroxyl radical and ofloxacin degradation efficiency. As much as 95.2% of the initial ofloxacin molecules are removed from the solution after 50 min of photocatalytic degradation on the cerium titanate obtained using 3.5 g PEG4000, while only 48.4% ofloxacin is removed on cerium titanate obtained without PEG4000.

  18. Synthesis of biocompatible hydrophobic silica-gelatin nano-hybrid by sol-gel process.

    Science.gov (United States)

    Smitha, S; Shajesh, P; Mukundan, P; Nair, T D R; Warrier, K G K

    2007-03-15

    Silica-biopolymer hybrid has been synthesised using colloidal silica as the precursor for silica and gelatin as the biopolymer counterpart. The surface modification of the hybrid material has been done with methyltrimethoxysilane leading to the formation of biocompatible hydrophobic silica-gelatin hybrid. Here we are reporting hydrophobic silica-gelatin hybrid and coating precursor for the first time. The hybrid gel has been evaluated for chemical modification, thermal degradation, hydrophobicity, particle size, transparency under the UV-visible region and morphology. FTIR spectroscopy has been used to verify the presence of CH(3) groups which introduce hydrophobicity to the SiO2-MTMS-gelatin hybrids. The hydrophobic property has also been tailored by varying the concentration of methyltrimethoxysilane. Contact angle by Wilhelmy plate method of transparent hydrophobic silica-gelatin coatings has been found to be as high as approximately 95 degrees . Oxidation of the organic group which induces the hydrophobic character occurs at 530 degrees C which indicates that the surface hydrophobicity is retained up to that temperature. Optical transmittance of SiO2-MTMS-gelatin hybrid coatings on glass substrates has been found to be close to 100% which will enable the hybrid for possible optical applications and also for preparation of transparent biocompatible hydrophobic coatings on biological substrates such as leather.

  19. Synthesis, structure and electromagnetic properties of Mn-Zn ferrite by sol-gel combustion technique

    Science.gov (United States)

    Wang, Wenjie; Zang, Chongguang; Jiao, Qingjie

    2014-01-01

    The electromagnetic absorbing behaviors of a thin coating fabricated by mixing Mn-Zn ferrite with epoxy resin (EP) were studied. The spinel ferrites Mn1-xZnxFe2O4 (x=0.2, 0.5 and 0.8) were synthesized with citrate acid as complex agent by sol-gel combustion method. The microstructure and surface morphology of Mn-Zn ferrite powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The complex permittivity and complex permeability of the fabricated ferrite/EP composites were investigated in terms of their contributions to the absorbing properties in the low frequency (10 MHz to 1 GHz). The microwave absorption of the prepared ferrite/EP composites could be tailored by matching the dielectric loss and magnetic loss and by controlling the doped metal ratio. The composites with the ferrite composition x=0.2 are found to show higher reflection loss compared with the composites with other compositions. It is proposed that the prepared composites can potentially be applied in electromagnetic microwave absorbing field.

  20. Green synthesis of magnetic chitosan nanocomposites by a new sol–gel auto-combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Ansari, Fatemeh [Institute of Nano Science and Nano Technology, University of Kashan, P.O. Box. 87317–51167, Kashan, Islamic Republic of Iran (Iran, Islamic Republic of); Sobhani, Azam [Department of Chemistry, Kosar University of Bojnord, Bojnord, Islamic Republic of Iran (Iran, Islamic Republic of); Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir [Institute of Nano Science and Nano Technology, University of Kashan, P.O. Box. 87317–51167, Kashan, Islamic Republic of Iran (Iran, Islamic Republic of)

    2016-07-15

    The Fe{sub 2}O{sub 3}/CuFe{sub 2}O{sub 4}/chitosan nanocomposites have been successfully synthesized via a new sol–gel auto-combustion route. To prepare the nanocomposites, copper ferrite (CuFe{sub 2}O{sub 4}) and iron (II) oxide (Fe{sub 2}O{sub 3}) nanostructures were first prepared utilizing onion as a green reductant for the first time, and characterized by SEM, TEM, XRD, IR and VSM. Then chitosan was added into the nanostructures dispersed in water. Chitosan was used to functionalize and modify the nanostructures and also to improve surface properties. The nanocomposites were also characterized by several techniques including SEM, TEM, XRD, IR and VSM. The effects of amount of onion and chitosan on the morphology and particle size of nanocomposites were evaluated. - Highlights: • Fe{sub 2}O{sub 3}/CuFe{sub 2}O{sub 4}/chitosan nanocomposites were synthesized for the first time. • A simple, low-cost and friendly route was used to synthesize the nanocomposites. • Effects of amount of onion and chitosan were investigated.

  1. Synthesis of palladium-doped silica nanofibers by sol-gel reaction and electrospinning process

    Energy Technology Data Exchange (ETDEWEB)

    San, Thiam Hui; Daud, Wan Ramli Wan; Kadhum, Abdul Amir Hassan; Mohamad, Abu Bakar; Kamarudin, Siti Kartom; Shyuan, Loh Kee; Majlan, Edy Herianto [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia and Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2012-06-29

    Nanofiber is drawing great attention nowadays with their high surface area per volume and flexibility in surface functionalities that make them favorable as a proton exchange membrane in fuel cell application. In this study, incorporation of palladium nanoparticles in silica nanofibers was prepared by combination of a tetraorthosilane (TEOS) sol-gel reaction with electrospinning process. This method can prevent the nanoparticles from aggregation by direct mixing of palladium nanoparticles in silica sol. The as-produced electrospun fibers were thermally treated to remove poly(vinyl pyrrolidone) (PVP) and condensation of silanol in silica framework. PVP is chosen as fiber shaping agent because of its insulting and capping properties for various metal nanoparticles. Scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the silica fibers and Pd nanoparticles on the fibers. Spun fibers with average diameter ranged from 100nm to 400nm were obtained at optimum operating condition and distribution of Pd nanoparticles on silica fibers was investigated.

  2. Quasi-one-dimensional nanostructured cobalt (Co) intercalated vanadium oxide (V{sub 2}O{sub 5}): Peroxovanadate sol gel synthesis and structural study

    Energy Technology Data Exchange (ETDEWEB)

    Langie da Silva, Douglas, E-mail: douglas.langie@ufpel.edu.br [Departamento de Física, Universidade Federal de Pelotas, Caixa Postal 354, Pelotas 96010-900 (Brazil); Moreira, Eduardo Ceretta [Laboratório de Espectroscopia, Universidade Federal do Pampa, Campus Bagé, Bagé 96400-970 (Brazil); Dias, Fábio Teixeira; Neves Vieira, Valdemar das [Departamento de Física, Universidade Federal de Pelotas, Caixa Postal 354, Pelotas 96010-900 (Brazil); Brandt, Iuri Stefani; Cas Viegas, Alexandre da; Pasa, André Avelino [Laboratório de Filmes Finos e Superfícies, Universidade Federal de Santa Catarina, Caixa Postal 476, Florianópolis 88.040-900 (Brazil)

    2015-01-15

    Nanostructured cobalt vanadium oxide (V{sub 2}O{sub 5}) xerogels spread onto crystalline Si substrates were synthesized via peroxovanadate sol gel route. The resulting products were characterized by distinct experimental techniques. The surface morphology and the nanostructure of xerogels correlate with Co concentration. The decrease of the structural coherence length is followed by the formation of a loose network of nanopores when the concentration of intercalated species was greater than 4 at% of Co. The efficiency of the synthesis route also drops with the increase of Co concentration. The interaction between the Co(OH{sub 2}){sub 6}{sup 2+} cations and the (H{sub 2}V{sub 10}O{sub 28}){sup 4−} anions during the synthesis was suggested as a possible explanation for the incomplete condensation of the V{sub 2}O{sub 5} gel. Finally the experimental results points for the intercalation of Co between the bilayers of the V{sub 2}O{sub 5}. In this scenario two possible preferential occupation sites for the metallic atoms in the framework of the xerogel were proposed. - Graphical abstract: Quasi-one-dimensional nanostructured cobalt (Co) intercalated vanadium oxide (V{sub 2}O{sub 5}) nanoribbons synthesized by peroxovanadate sol gel route. - Highlights: • Nanostructured cobalt V{sub 2}O{sub 5} gel spread onto c{sub S}i were synthesized via peroxovanadate sol gel route. • The micro and nanostructure correlates with the cobalt content. • The efficiency of the synthesis route shows to be also dependent of Co content. • The experimental results points for the intercalation of Co between the bilayers of the V{sub 2}O{sub 5} xerogel.

  3. Polyphosphate present in DNA preparations from fungal species of Collectotrichum inhibits restriction endonucleases and other enzymes

    Science.gov (United States)

    Rodriguez, R.J.

    1993-01-01

    During the development of a procedure for the isolation of total genomic DNA from filamentous fungi (Rodriguez, R. J., and Yoder, 0. C., Exp. Mycol. 15, 232-242, 1991) a cell fraction was isolated which inhibited the digestion of DNA by restriction enzymes. After elimination of DNA, RNA, proteins, and lipids, the active compound was purified by gel filtration to yield a single fraction capable of complete inhibition of restriction enzyme activity. The inhibitor did not absorb uv light above 220 nm, and was resistant to alkali and acid at 25°C and to temperatures as high as 100°C. More extensive analyses demonstrated that the inhibitor was also capable of inhibiting T4 DNA ligase and TaqI DNA polymerase, but not DNase or RNase. Chemical analyses indicated that the inhibitor was devoid of carbohydrates, proteins, lipids, and nucleic acids but rich in phosphorus. A combination of nuclear magnetic resonance, metachromatic shift of toluidine blue, and gel filtration indicated that the inhibitor was a polyphosphate (polyP) containing approximately 60 phosphate molecules. The mechanism of inhibition appeared to involve complexing of polyP to the enzymatic proteins. All species of Colletotrichum analyzed produced polyP equivalent in chain length and concentration. A modification to the original DNA extraction procedure is described which eliminates polyP and reduces the time necessary to obtain DNA of sufficient purity for restriction enzyme digestion and TaqI polymerase amplification.

  4. Synthesis of Silica Nanoparticles by Sol-Gel: Size-Dependent Properties, Surface Modification, and Applications in Silica-Polymer Nano composites-A Review

    International Nuclear Information System (INIS)

    Ismail, A.R.; Vejayakumaran, P.

    2012-01-01

    Application of silica nanoparticles as fillers in the preparation of nano composite of polymers has drawn much attention, due to the increased demand for new materials with improved thermal, mechanical, physical, and chemical properties. Recent developments in the synthesis of monodispersed, narrow-size distribution of nanoparticles by sol-gel method provide significant boost to development of silica-polymer nano composites. This paper is written by emphasizing on the synthesis of silica nanoparticles, characterization on size-dependent properties, and surface modification for the preparation of homogeneous nano composites, generally by sol-gel technique. The effect of nano silica on the properties of various types of silica-polymer composites is also summarized.

  5. Sol-gel synthesis and characterization of SiO{sub 2}/PEG hybrid materials containing quercetin as implants with antioxidant properties

    Energy Technology Data Exchange (ETDEWEB)

    Catauro, Michelina; Bollino, Flavia [Department of Industrial and Information Engineering, Second University of Naples, Via Roma 21, 81031 Aversa (Italy); Gloria, Antonio [Institute of Polymers, Composites and Biomaterials - National Research Council of Italy, V.le J. F. Kennedy 54 - Mostra d’Oltremare Pad. 20, 80125 Naples (Italy)

    2016-05-18

    In the present work, Silica/Polyethylene glycol (PEG) hybrid nanocomposites containing an antioxidant agent, the quercetin, were synthesized via sol-gel to be used as implants with antioxidant properties. Fourier transform infrared (FT-IR) analysis proved that a modification of both polymer and quercetin occurs due to synthesis process. Scanning electron microscope (SEM) showed that the proposed materials were hybrid nanocomposites. The bioactivity was ascertained by soaking the samples in a simulated body fluid (SBF).

  6. A highly active PtCu3 intermetallic core-shell, multilayered Pt-skin, carbon embedded electrocatalyst produced by a scale-up sol-gel synthesis.

    Science.gov (United States)

    Bele, M; Jovanovič, P; Pavlišič, A; Jozinović, B; Zorko, M; Rečnik, A; Chernyshova, E; Hočevar, S; Hodnik, N; Gaberšček, M

    2014-11-07

    We present a novel, scaled-up sol-gel synthesis which enables one to produce 20 g batches of highly active and stable carbon supported PtCu3 nanoparticles as cathode materials for low temperature fuel cell application. We confirm the presence of an ordered intermetallic phase underneath a multilayered Pt-skin together with firm embedment of nanoparticles in the carbon matrix.

  7. Polyphosphates in Intraradical and Extraradical Hyphae of an Arbuscular Mycorrhizal Fungus, Gigaspora margarita

    OpenAIRE

    Solaiman, M. Zakaria; Ezawa, Tatsuhiro; Kojima, Tomoko; Saito, Masanori

    1999-01-01

    The amount of polyphosphate in the intraradical and extraradical hyphae of Gigaspora margarita was estimated from successive extractions with trichloroacetic acid (TCA), EDTA, and phenol-chloroform (PC). In the intraradical hyphae, most of the polyphosphate was present in TCA- and EDTA-soluble (short-chain and long-chain) fractions, whereas most of the polyphosphate in the extraradical hyphae was present in EDTA- and PC-soluble (long-chain and granular) fractions.

  8. Synthesis and electron paramagnetic resonance study of a nitroxide free radical covalently bonded on aminopropyl-silica gel

    International Nuclear Information System (INIS)

    Tudose, Madalina; Constantinescu, Titus; Balaban, Alexandru T.; Ionita, Petre

    2008-01-01

    A solid spin-labeled material was obtained starting from 2-chloro-3,5-dinitro-N-(4-(2,2,6,6-tetramethyl-piperidine-1-oxyl) -benzamide) and aminopropyl-silica gel. Stability tests showed that even after several months the spin-labeled material had the same properties as immediately after synthesis. EPR properties of the TEMPO-derivatized silica were studied as a function of solvent polarity and temperature. Rotational correlation times were calculated from EPR spectra and correlated with solvent characteristics and temperature. Polar solvents induce a fast motion of the spin-label, clearly seen in the EPR spectra by the apparition of the well-known TEMPO radical triplet. The solid spin-labeled (dry) sample showed a high interspin interaction, which can be disrupted not only by different (liquid) solvents, but also by absorption of different solids, like cyclodextrins, dendrimers or polyethyleneglycols. Also, changes induced by the temperature were studied in the case of toluene wet sample. From 150 to 370 K, the spectrum is changing from a slow motion spectrum type to a fast motion regime. The preparative procedures to obtain the spin-labeled silica as well as some of its parameters are described

  9. Synthesis and electron paramagnetic resonance study of a nitroxide free radical covalently bonded on aminopropyl-silica gel

    Energy Technology Data Exchange (ETDEWEB)

    Tudose, Madalina; Constantinescu, Titus [Institute of Physical Chemistry, Spl. Independentei 202, 060021 Bucharest (Romania); Balaban, Alexandru T. [Texas A and M University at Galveston, Marine Sciences Department, Galveston, TX 77551 (United States); Ionita, Petre [Institute of Physical Chemistry, Spl. Independentei 202, 060021 Bucharest (Romania)], E-mail: pionita@icf.ro

    2008-01-30

    A solid spin-labeled material was obtained starting from 2-chloro-3,5-dinitro-N-(4-(2,2,6,6-tetramethyl-piperidine-1-oxyl) -benzamide) and aminopropyl-silica gel. Stability tests showed that even after several months the spin-labeled material had the same properties as immediately after synthesis. EPR properties of the TEMPO-derivatized silica were studied as a function of solvent polarity and temperature. Rotational correlation times were calculated from EPR spectra and correlated with solvent characteristics and temperature. Polar solvents induce a fast motion of the spin-label, clearly seen in the EPR spectra by the apparition of the well-known TEMPO radical triplet. The solid spin-labeled (dry) sample showed a high interspin interaction, which can be disrupted not only by different (liquid) solvents, but also by absorption of different solids, like cyclodextrins, dendrimers or polyethyleneglycols. Also, changes induced by the temperature were studied in the case of toluene wet sample. From 150 to 370 K, the spectrum is changing from a slow motion spectrum type to a fast motion regime. The preparative procedures to obtain the spin-labeled silica as well as some of its parameters are described.

  10. Fabrication of Mesoporous Silica/Alumina Hybrid Membrane Film Nanocomposites using Template Sol-Gel Synthesis of Amphiphilic Triphenylene

    Science.gov (United States)

    Lintang, H. O.; Jalani, M. A.; Yuliati, L.; Salleh, M. M.

    2017-05-01

    Herein we reported that by introducing a one-dimensional (1D) substrate with a porous structure such as anodic aluminum oxide (AAO) membrane, mesoporous silica/alumina hybrid nanocomposites were successfully fabricated by using amphiphilic triphenylene (TPC10TEG) as a template in sol-gel synthesis (TPC10TEG/silicahex). For the optical study of the nanocomposites, TPC10TEG/silicahex showed absorption peak at 264 nm due to the ordered and long-range π-π stacking of the disc-like aromatic triphenylene core. Moreover, the hexagonal arrangement of TPC10TEG/silicahex was proven based on their diffraction peaks of d 100 and d 200 at 2θ = 2.52° and 5.04° and images of transmission electron microscopy (TEM), respectively. For fabrication of mesoporous silica/alumina hybrid membrane, TPC10TEG/silicahex was drop-casted onto AAO membrane for penetration into the porous structure via gravity. X-ray diffraction (XRD) analysis on the resulted hybrid nanocomposites showed that the diffraction peaks of d 100 and d 200 of TPC10TEG/silicahex were still preserved, indicating that the hexagonal arrangements of mesoporous silica were maintained even on AAO substrate. The morphology study on the hybrid nanocomposites using TEM, scanning electron microscope (SEM) and field emission scanning electron microscope (FE-SEM) showed the successful filling of most AAO channels with the TPC10TEG/silicahex nanocomposites.

  11. Surfactant-directed synthesis of mesoporous films made single-step by a tandem photosol-gel/photocalcination route

    Energy Technology Data Exchange (ETDEWEB)

    De Paz-Simon, Héloïse; Chemtob, Abraham, E-mail: abraham.chemtob@uha.fr; Croutxé-Barghorn, Céline [Laboratory of Macromolecular Photochemistry and Engineering, ENSCMu, University of Haute-Alsace, 3 bis rue Alfred Werner, 68093 Mulhouse Cedex (France); Rigolet, Séverinne; Michelin, Laure; Vidal, Loïc; Lebeau, Bénédicte [Institut de Science des Matériaux de Mulhouse, UMR-CNRS 7361, University of Haute-Alsace, 3 rue Alfred Werner, 68093 Mulhouse Cedex (France)

    2014-11-01

    In view of their technological impact in materials chemistry, a simplified and more efficient synthetic route to mesoporous films is highly sought. We report, herein, a smart UV-mediated approach coupling in a one-stage process sol-gel photopolymerization and photoinduced template decomposition/ablation to making mesoporous silica films. Performed at room temperature with a solvent-free solution of silicate precursor and amphiphilic poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer, the synthesis relies on photoacid generation to induce the fast formation (≈10 min) of mesostructured silica/surfactant domains. Continuation of UV exposure for three additional hours enables subsequent and complete photodegradation of the polyether copolymer, resulting in ordered or disordered mesoporous silica film. One of the most attractive features is that the one-step procedure relies on a continuous illumination provided by the same conventional medium-pressure Hg-Xe arc lamp equipped with a 254 nm reflector to enhance the emission of energetic photons <300 nm. In addition to X-ray diffraction and transmission electron microscopy, time-resolved Fourier transform infrared spectroscopy has proved to be a powerful in situ technique to probe the different chemical transformations accompanying irradiation. Photocalcination strengthens the inorganic network, while allowing to preserve a higher fraction of residual silanol groups compared with thermal calcination. A polyether chain degradation mechanism based on oxygen reactive species-mediated photo-oxidation is proposed.

  12. Synthesis and Characterization of Silicotungstic Acid Nanoparticles Via Sol Gel Technique as a Catalyst in Esterification Reaction

    International Nuclear Information System (INIS)

    Wan Nor Roslam Wan Ishak; Manal Ismail

    2011-01-01

    The purpose of this work is to study the synthesis, characterization and catalytic performance of silicotungstic acid-silica sol gel (STA-SG) as acid catalyst in esterification reaction. The activity and selectivity of STA-SG have been investigated and compared to the STA bulk (STAB) and sulphuric acid (H 2 SO 4 ). The synthesized catalysts were characterized by various techniques shown that the STA-SG catalyst is relatively high in surface area compared to STAB of 460.11 m 2 /g and 0.98 m 2 /g, respectively. From the XPS analyses, there was a significant formation of W-O-Si, W-O-W and Si-O-Si bonding in STA-SG compared to that in STAB. Both the H 2 SO 4 and the STAB gave high conversion of 100 % and 98 %, while lower selectivity of glycerol monooleate (GMO) with 81.6 % and 89.9 %, respectively. On the contrary, the STA-SG enabled a conversion of 94 %, while significantly higher GMO selectivity of 95 % rendering it the more efficient acid catalyst. (author)

  13. Non-hydrolytic sol-gel synthesis of epoxysilane-based inorganic-organic hybrid resins

    International Nuclear Information System (INIS)

    Jana, Sunirmal; Lim, Mi Ae; Baek, In Chan; Kim, Chang Hae; Seok, Sang Il

    2008-01-01

    A silica-based inorganic-organic hybrid resins (IOHR) were synthesized by non-hydrolytic sol-gel process from 3-glycidoxypropyltrimethoxysilane (GLYMO) and diphenylsilanediol (DPSD) at a fixed amount of (20 mol%) phenyltrimethoxysilane using barium hydroxide as a catalyst. The confirmation of condensation reaction in the IOHR was done by liquid state 29 Si NMR (Nuclear Magnetic Resonance) spectroscopy, measurement of viscosity as well as weight average molecular weight (W m ) of the IOHR. The W m of the IOHR was varied from 1091 to 2151, depending upon the DPSD content. Fourier transform infrared (FTIR) spectroscopic measurements were performed to investigate the details of vibrational absorption bands in the IOHR. It was seen that up to 50 mol% of DPSD there were no absorption peaks in the region of 3000-3600 cm -1 responsible for O-H groups and it reappeared at 60 mol% of DPSD due to some unreacted OH groups present in the resin. The IOHR at all the compositions was oily transparent liquid, miscible with various organic solvents like toluene, cyclohexanone, chloroform, tehrahydrofuran (THF), etc., and also commercial epoxy resins but immiscible with water. The color of the IOHR was pale yellow, which lightened with increasing DPSD content. The IOHR having 40-50 mol% of DPSD were storable. The refractive index at 632.8 nm of the resin films varied from 1.556 to 1.588, depending upon the resin composition. Physico-chemical properties such as the thermal stability, visible transparency, etc. after curing were investigated as a function of the chemical composition

  14. The chemical and catalytic properties of nanocrystalline metal oxides prepared through modified sol-gel synthesis

    Science.gov (United States)

    Carnes, Corrie Leigh

    The goal of this research was to synthesize, characterize and study the chemical properties of nanocrystalline metal oxides. Nanocrystalline (NC) ZnO, CuO, NiO, Al2O3, and the binary Al2O 3/MgO and ZnO/CuO were prepared through modified sol gel methods. These NC metal oxides were studied in comparison to the commercial (CM) metal oxides. The samples were characterized by XRD, TGA, FTIR, BET, and TEM. The NC samples were all accompanied by a significant increase in surface area and decrease in crystallite size. Several chemical reactions were studied to compare the NC samples to the CM samples. One of the reactions involved a high temperature reaction between carbon tetrachloride and the oxide to form carbon dioxide and the corresponding metal chloride. A similar high temperature reaction was conducted between the metal oxide and hydrogen sulfide to form water and the corresponding metal sulfide. A room temperature gas phase adsorption was studied where SO2 was adsorbed onto the oxide. A liquid phase adsorption conducted at room temperature was the destructive adsorption of paraoxon (a toxic insecticide). In all reactions the NC samples exhibited greater activity, destroying or adsorbing a larger amount of the toxins compared to the CM samples. To better study surface area effects catalytic reactions were also studied. The catalysis of methanol was studied over the nanocrystalline ZnO, CuO, NiO, and ZnO/CuO samples in comparison to their commercial counterparts. In most cases the NC samples proved to be more active catalysts, having higher percent conversions and turnover numbers. A second catalytic reaction was also studied, this reaction was investigated to look at the support effects. The catalysis of cyclopropane to propane was studied over Pt and Co catalysts. These catalysts were supported onto NC and CM alumina by impregnation. By observing differences in the catalytic behavior, support effects have become apparent.

  15. Synthesis and characterization of nanosized MgxMn1−xFe2O4 ferrites by both sol-gel and thermal decomposition methods

    International Nuclear Information System (INIS)

    De-León-Prado, Laura Elena; Cortés-Hernández, Dora Alicia; Almanza-Robles, José Manuel; Escobedo-Bocardo, José Concepción; Sánchez, Javier; Reyes-Rdz, Pamela Yajaira; Jasso-Terán, Rosario Argentina; Hurtado-López, Gilberto Francisco

    2017-01-01

    This work reports the synthesis of Mg x Mn 1−x Fe 2 O 4 (x=0–1) nanoparticles by both sol-gel and thermal decomposition methods. In order to determine the effect of synthesis conditions on the crystal structure and magnetic properties of the ferrites, the synthesis was carried out varying some parameters, including composition. By both methods it was possible to obtain ferrites having a single crystalline phase with cubic inverse spinel structure and a behavior near to that of superparamagnetic materials. Saturation magnetization values were higher for materials synthesized by sol-gel. Furthermore, in both cases particles have a spherical-like morphology and nanometric sizes (11–15 nm). Therefore, these materials can be used as thermoseeds for the treatment of cancer by magnetic hyperthermia. - Highlights: • Mg–Mn ferrites were synthesized by sol-gel and thermal decomposition methods. • Materials showed a single cubic inverse spinel crystalline structure. • Ferrites have a soft ferrimagnetic behavior close to superparamagnetic materials.

  16. Membrane interaction and functional plasticity of inositol polyphosphate 5-phosphatases.

    Science.gov (United States)

    Braun, Werner; Schein, Catherine H

    2014-05-06

    In this issue of Structure, Trésaugues and colleagues determined the interaction of membrane-bound phosphoinositides with three clinically significant human inositol polyphosphate 5-phosphatases (I5Ps). A comparison to the structures determined with soluble substrates revealed differences in the binding mode and suggested how the I5Ps and apurinic endonuclease (APE1) activities evolved from the same metal-binding active center. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Polyphosphate Amendments for In-Situ Immobilization of Uranium Plumes

    International Nuclear Information System (INIS)

    Wellman, Dawn M.; Icenhower, Jonathan P.; Pierce, Eric M.; McNamara, Bruce K.; Burton, Sarah D.; Geiszler, Keith N.; Baum, Steven R.; Butler, Bart C.; R.F. Olfenbuttel; P.J. White

    2005-01-01

    A multi-faceted approach has been taken to address basic science questions with regards to the efficacy of utilizing phosphate amendments for subsurface immobilization of uranium plumes. Hydraulically saturated and unsaturated column tests demonstrate the ability of polyphosphate compounds to control the precipitation kinetics of insoluble phosphate minerals and optimize conditions for controlled application of phosphate amendments for subsurface remediation. X-Ray micro-focus tomography results illustrate long-term effects of phosphate mineralization on hydraulic conductivity. 31P NMR has been utilized to quantify the effect of sedimentary and aqueous components on the in-situ hydrolysis kinetics of condensed polyphosphates. Single-pass flow-through (SPFT) tests have been conducted to evaluate the longevity and quantify the effects of aqueous organic material on the dissolution kinetics of autunite minerals, X1-2[(UO2)(PO4)]2nH2O. Preliminary results indicate: (1) autunite minerals will precipitate within 1-2 months given a 0.05 M phosphate concentration and 10-6 M aqueous uranium concentration, under hydraulically saturated conditions; (2) polyphosphate chain lengths can be optimized for specific site conditions, given thorough knowledge of the subsurface environment; (3) the release of uranium from autunite minerals appears to be 6-7 order of magnitude slower than uranium (UO2) minerals formed by iron barrier reduction; and (4) understanding secondary uranyl-phase formation is necessary for predicting the long-term fate of uranium in the environment

  18. Synthesis of potassium sodium niobate nanostructures by hydrothermal combining with the sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Xianghe; Wang, Wen, E-mail: wangwen@hit.edu.cn; Ke, Hua; Rao, Jiancun; Zhou, Yu

    2016-10-15

    Graphical abstract: We prepared novel metastable perovskite K{sub 0.52}Na{sub 0.48}NbO{sub 3} microstructures with a morphotropic phase boundary (MPB) between rhombohedral and tetragonal via hydrothermal method with SDS surfactant-assist. - Highlights: • KNbO{sub 3}-type orthorhombic K{sub 1−x}Na{sub x}NbO{sub 3} nanowires were prepared by hydrothermal method. • Metastable K{sub 0.52}Na{sub 0.48}NbO{sub 3} microfingers have a morphotropic phase boundary. • Sodium dodecyl sulfate could improve the crystallinity of K{sub 0.52}Na{sub 0.48}NbO{sub 3} powders. • The Curie temperature of rhombohedral-tetragonal KNN was 555 °C. - Abstract: In this paper the K{sub 1−x}Na{sub x}NbO{sub 3}(KNN) nanostructures were synthesized by hydrothermal method using KNN gel powders as precursors. KNbO{sub 3}-type orthorhombic KNN nanowires and perovskite KNN microfingers with a morphotropic phase boundary (MPB) between rhombohedral and tetragonal characterized by X-ray diffraction and Raman spectroscopy were obtained at 190 °C and 220 °C, respectively. KNbO{sub 3}-type orthorhombic KNN nanowires had rectangular shape and the growth direction of these nanowires was [0 0 1]. The rhombohedral-tetragonal KNN microfingers were metastable, and changed the rhombohedral-tetragonal phase into the orthorhombic phase via thermal treatment at 600 °C then cooled down to room temperature. Sodium dodecyl sulfate (SDS) as surfactant was added to the hydrothermal reaction. It was found that SDS could improve the crystallinity of the rhombohedral-tetragonal K{sub 0.52}Na{sub 0.48}NbO{sub 3} and reduce the impurity effectively. The tetragonal-cubic phase transition temperature (Tc) of the rhombohedral-tetragonal powders appeared at 555 °C.

  19. Sol–gel synthesis of tantalum oxide and phosphonic acid-modified carbon nanotubes composite coatings on titanium surfaces

    International Nuclear Information System (INIS)

    Maho, Anthony; Detriche, Simon; Delhalle, Joseph; Mekhalif, Zineb

    2013-01-01

    composite coatings on titanium plates by sol–gel co-deposition. ► Synthesis and incorporation of MWCNTs bearing bisphosphonic acid moieties. ► Stronger “tantalum capture agent” effect of phosphonic-modified MWCNTs comparing to oxidized ones. ► Bioactivity of the resulting biomaterial qualitatively assessed by in vitro growth tests of hydroxyapatite

  20. Sol–gel synthesis of tantalum oxide and phosphonic acid-modified carbon nanotubes composite coatings on titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Maho, Anthony [Laboratory of Chemistry and Electrochemistry of Surfaces, University of Namur (FUNDP), Rue de Bruxelles 61, B-5000 Namur (Belgium); Fonds pour la Formation à la Recherche dans l' Industrie et dans l' Agriculture (FRIA), Rue d' Egmont 5, B-1000 Bruxelles (Belgium); Detriche, Simon; Delhalle, Joseph [Laboratory of Chemistry and Electrochemistry of Surfaces, University of Namur (FUNDP), Rue de Bruxelles 61, B-5000 Namur (Belgium); Mekhalif, Zineb, E-mail: zineb.mekhalif@fundp.ac.be [Laboratory of Chemistry and Electrochemistry of Surfaces, University of Namur (FUNDP), Rue de Bruxelles 61, B-5000 Namur (Belgium)

    2013-07-01

    /carbon nanotube composite coatings on titanium plates by sol–gel co-deposition. ► Synthesis and incorporation of MWCNTs bearing bisphosphonic acid moieties. ► Stronger “tantalum capture agent” effect of phosphonic-modified MWCNTs comparing to oxidized ones. ► Bioactivity of the resulting biomaterial qualitatively assessed by in vitro growth tests of hydroxyapatite.

  1. Sol-gel synthesis of Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12} nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang Wen, E-mail: wangwen@hit.edu.cn [Institute for Advanced Ceramics, School of Materials Science and Engineering, Harbin Institute of Technology, No. 92 West Da-Zhi Street, Harbin 150001, Heilongjiang (China); Hua, Ke; Jiancun, Rao; Jinbiao, Feng; Ming, Feng; Dechang, Jia; Yu, Zhou [Institute for Advanced Ceramics, School of Materials Science and Engineering, Harbin Institute of Technology, No. 92 West Da-Zhi Street, Harbin 150001, Heilongjiang (China)

    2011-04-07

    Research highlights: > One-dimensional (1D) ferroelectrics have been successfully synthesized. The sol-gel template synthesis is a versatile and inexpensive technique for producing nanostructures, and particularly facilitates the fabrication of complex oxide nanotubes or nanowires. Compared with the synthesis of the general nanotubes such as carbon nanotubes with simple crystal structure, the synthesis of ferroelectric compound is difficult due to the multielement and the complex crystal structures of these ferroelectrics. Herein, we report the synthesis of one-dimensional BLT nanotubes on anodic alumina (AAO) templates by immersing a template membrane in sol without polymeric additive. - Abstract: Ferroelectric Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12} (BLT) nanotubes were synthesized by sol-gel technique using nanochannel porous anodic aluminum oxide (AAO) templates, and were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). BLT nanotubes with diameter of around 240 nm and the wall thickness of about 25 nm exhibited a single orthorhombic perovskite structure and highly preferential crystal growth along the [1 1 7] orientation, which have smooth wall morphologies and well-defined diameters corresponding to the diameter of the applied template. The formation mechanism of BLT nanotubes was discussed.

  2. Low-field NMR determination of water distribution in meat batters with NaCl and polyphosphate addition.

    Science.gov (United States)

    Shao, Jun-Hua; Deng, Ya-Min; Jia, Na; Li, Ru-Ren; Cao, Jin-Xuan; Liu, Deng-Yong; Li, Jian-Rong

    2016-06-01

    The objective was to elucidate the influence of NaCl and polyphosphates in the stage of protein swelling on the water-holding capacity (WHC) of meat batter. The meat batters were formulated with salt in different ways by adding established amounts of only NaCl, only polyphosphates, jointly adding NaCl and polyphosphates, and a control without any salt. An increase (pwater retention was found when a combination of NaCl and polyphosphates was used. A high textural parameter was observed in the two treatments with NaCl, but not in the group with only polyphosphate. For the polyphosphate group, T22 was lower (pwater, particularly with polyphosphate, but polyphosphate could not be an equal substitute for NaCl given its resulting lowest textural properties and poor microstructure. By presenting different hydration states in the protein swelling stage, the meat batter qualities were differentiated. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Synthesis and characterization of mixtures of cobalt and titanium oxides by mechanical alloyed and Sol-Gel;Sintesis y caracterizacion de mezclas de oxidos de cobalto y titanio por aleado mecanico y Sol-Gel

    Energy Technology Data Exchange (ETDEWEB)

    Basurto S, R.; Bonifacio M, J.; Fernandez V, S. M., E-mail: rafael.basurto@inin.gob.m [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico)

    2009-07-01

    The mechanical alloyed techniques continued by combustion and Sol-Gel method, were used for the synthesis of CoTiO{sub 3}. With the first technique was used Co{sub 3}O{sub 4} obtained in a balls mill SPEX in argon atmosphere, using cobalt nitrate and urea, the combustion is realized at 400 and 500 C, the characterization by X-ray diffraction showed the obtaining of the valence oxide mixed of cobalt with crystallite size from 10 to 12.5 nm and the particle size of 60 to 75 nm was obtained by scanning electron microscopy. To prepare the CoTiO{sub 3}, the obtained Co{sub 3}O{sub 4} was mixed with TiO{sub 2} on a relationship in weight (1:1) and with a milling time of 2.5 h and the combustion at 800 C. the mixed oxide of titanium cobalt was also obtained by the Sol-Gel technique starting from cobalt chloride and titanium propoxide in acetic-water acid, the gel is burned to temperature of 300, 500, 700 and 900 C, finding that this last temperature it is that provides the compound with crystalline size from 50 to 75 nm. (Author)

  4. Inexpensive sol-gel synthesis of multiwalled carbon nanotube-TiO{sub 2} hybrids for high performance antibacterial materials

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Nadir; Shao, Godlisten N. [Department of Fusion Chemical Engineering, Hanyang University, 1271 Sa 3-dong, Sangnok-gu, Ansan-si, Gyeonggi-do 426-791 (Korea, Republic of); Haider, M. Salman [Department of Civil and Environmental System Engineering, Hanyang University, 1271 Sa 3-dong, Sangnok-gu, Ansan-si, Gyeonggi-do 426-791 (Korea, Republic of); Imran, Syed Muhammad; Park, Sung Soo; Jeon, Sun-Jeong [Department of Fusion Chemical Engineering, Hanyang University, 1271 Sa 3-dong, Sangnok-gu, Ansan-si, Gyeonggi-do 426-791 (Korea, Republic of); Kim, Hee Taik, E-mail: khtaik@hanyang.ac.kr [Department of Fusion Chemical Engineering, Hanyang University, 1271 Sa 3-dong, Sangnok-gu, Ansan-si, Gyeonggi-do 426-791 (Korea, Republic of)

    2016-11-01

    This study reports an inexpensive sol-gel method to synthesize TiO{sub 2}-CNT hybrid materials. Synthesized TiO{sub 2}-CNT materials show strong antibacterial activity in the absence of light. Cheap TiO{sub 2} source TiOCl{sub 2} is used during synthesis in the absence of high temperatures, high pressures and organic solvents. TiO{sub 2}-CNT materials with 0, 2, 5, 10, 15 and 20 wt% of CNT were synthesized and compared for antibacterial activity, surface area, porosity, crystalline structure, chemical state, and HaCaT cell proliferation. The antibacterial strength of hybrid materials increased significantly with the increase in CNT loading amount, and the TiO{sub 2}-CNT samples with a CNT loading of 10 wt% or more nearly removed all of the E.coli bacteria. HaCaT cell proliferation studies of synthesized hybrid materials illustrated that prepared TiO{sub 2}-CNT systems exhibit minimum cytotoxicity. The characteristics of prepared materials were analyzed by means of XRD, FTIR, Raman spectroscopy, XPS, TEM, and nitrogen gas physisorption studies, compared and discussed. - Highlights: • An inexpensive scheme of preparing TiO{sub 2}-CNT hybrids is presented. • Significant increase in the antibacterial properties of TiO{sub 2} in absence of light • Effects of CNT addition on the physicochemical properties of hybrids are studied. • Antibacterial activity increases with increase in CNT content. • Hybrids show no toxicity towards HaCaT skin cell line.

  5. Synthesis of gels with basis of titanium tungstates as matrixes of radioactive generators; Sintesis de geles a base de titanio tungstenatos como matrices de generadores radiactivos

    Energy Technology Data Exchange (ETDEWEB)

    Galico C, L

    2005-07-01

    synthesis method avoids the manipulation of radioactive material during the synthesis of the gels, process that consumes around 7 hours. Therefore, in base to the studies carried out with titanium molybdates, it is intends in this work, the synthesis of titanium tungstates gels, to be used as matrixes of the generators {sup 188} W / {sup 188} Re. This type of studies has not been reported in the literature, for what is necessary to undertake basic studies on those preparation conditions and the effect of the characteristics of the titanium tungstates gels in the efficiency of the generators. Parameters like the pH of those initial solutions of tungsten and titanium, the molar relation W:Ti and very particularly the drying of the final product are fundamental to determine the preparation conditions of these gels. Therefore, in order to finding new alternatives of production of {sup 188} W {yields} {sup 188} Re, easy to produce and with high titration efficiencies, it is intends in this work, to develop a generator with basis of titanium and tungsten compounds that could be irradiated after their synthesis. (Author)

  6. Sol-Gel synthesis of MgO-SiO2 glass compositions having stable liquid-liquid immiscibility

    Science.gov (United States)

    Bansal, Narottam P.

    1987-01-01

    MgO-SiO2 glasses containing up to 15 mol % MgO, which could not have been prepared by the conventional glass melting method due to the presence of stable liquid-liquid immiscibility, were synthesized by the sol-gel technique. Clear and transparent gels were obtained from the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) and magnesium nitrate hexahydrate when the water/TEOS mole ratio was four or more. The gelling time decreased with increase in magnesium content, water/TEOS ratio, and reaction temperature. Magnesium nitrate hexahydrate crystallized out of the gels containing 15 and 20 mol % MgO on slow drying. This problem was partially alleviated by drying the gels quickly at higher temperatures. Monolithic gel samples were prepared using glycerol as the drying control additive. The gels were subjected to various thermal treatments and characterized by several methods. No organic groups could be detected in the glasses after heat treatments to approx. 800 C, but trace amounts of hydroxyl groups were still present. No crystalline phase was found from X-ray diffraction in the gel samples to approx. 890 C. At higher temperatures, alpha quartz precipitated out as the crystalline phase in gels containing up to 10 mol % MgO. The overall activation energy for gel formation in 10MgO-90SiO2 (mol %) system for water/TEOS mole ratio of 7.5 was calculated to be 58.7 kJ/mol.

  7. The effects of high pressure treatments on C. jejuni in ground poultry products containing polyphosphate additives

    Science.gov (United States)

    Marinades containing polyphosphates have been previously implicated in the enhanced survival of Campylobacter spp. in poultry product exudates. The enhanced Campylobacter survival was attributed primarily to the ability of some polyphosphates to change the pH of the exudate to one more amenable to ...

  8. Synthesis and characterization of a cryo gel starting from chitosan and their study as adsorbent of Cu (II) ions in aqueous solution

    International Nuclear Information System (INIS)

    Arcos A, A. J.

    2012-01-01

    The present work consisted in the synthesis of cryo gels from chitosan, which were cross-linked with ethylene glycol diglycidyl ether to obtain a stable, porous and resistant material to the interaction with aqueous solutions, in order that can be used in metal sorption processes. The performed synthesis consisted in a aqueous chitosan gel preparation crosslinked with ethylene glycol diglycidyl ether (Edge), evaluating two levels of crosslinking (1 and 2%); later to obtain the cryo gels, the aqueous gels were subjected to an ice segregation induced self-assembly process (ISISA), considering two levels of speed of materials formation. The obtained materials were characterized first determining their solubility in aqueous solutions and to the pair was determined the degree of swelling of the materials. Later, were used techniques like: the sweeping electronic microscopy to be able to observe the morphology of the obtained cryo gels, X-ray diffraction to know the crystallinity of the same, zeta potential with the aim of know the electrical potential in the materials, specific area determination, Fourier transformation infrared spectroscopy (Ftir) and X-ray photoelectrons spectroscopy (XP S), to know the functional groups and chemical interactions of the present elements in the materials before and after the copper ions sorption. The evaluation of the cryo gels as sorbents was performed obtaining the sorption kinetics for the Cu (II) ion at 25 and 30 grades C, and adjusting the experimental data obtained to the Lagergren and Ho kinetic models, as well as was performed adsorption isotherms at 25 and 35 grades C for the copper ion, adjusting the obtained data to the Langmuir, Freundlich and Langmuir-Freundlich models. In general, it was observed that the obtained materials show a macroporous structure, which presents and uniform swelling without significant deformations. Furthermore, was observed that the speed of formation of the materials affects the pores size and the

  9. Low-temperature synthesis and characterization of anatase TiO2 nanoparticles by an acid assisted sol–gel method

    International Nuclear Information System (INIS)

    Leyva-Porras, C.; Toxqui-Teran, A.; Vega-Becerra, O.; Miki-Yoshida, M.; Rojas-Villalobos, M.; García-Guaderrama, M.

    2015-01-01

    The synthesis of anatase TiO 2 nanoparticles by an acid-assisted sol–gel method at 25 and 80 °C is described. Specifically, acetic acid (AA) was used and the evolution of the anatase phase with the amount of AA was observed. The results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) both showed that a pure anatase phase was obtained with particle size smaller than 5 nm. Structural refinements and quantitative determination of phase composition was achieved by using the Rietveld method. The particle size distribution became slightly narrower as the amount of AA was increased. Raman spectroscopy showed that when the amount of AA was increased a small amount of brookite was present at the contamination level. The anatase phase was studied by differential thermal analysis (DTA), providing phase stability up to 600 °C. These and other results were discussed in terms of particle size and structure. Likewise, the formation of the anatase phase under these synthesis conditions was explained. - Highlights: • Synthesis of anatase TiO 2 nanoparticles by an acid assisted sol–gel method at mild conditions. • Microstructure characterization by XRD, TEM and Raman spectroscopy. • Observation of the formation and evolution of the anatase phase as acetic acid was increased. • Anatase thermal stability up to 600 °C and band gap range between 3.2 and 3.5 eV. • A simplified method which can be considered as a green chemistry process

  10. Preparation of 99Mo/99mTc generators based on 99Mo zirconium molybdates in the Gel Synthesis Device for Generators

    International Nuclear Information System (INIS)

    Lopez M, I. Z.; Monroy G, F.; Rivero G, T.; Rojas N, P.

    2008-01-01

    The 99m Tc is used for diagnosis and therapy. It is produced commercially from 99 Mo obtained from the fission of 235 U, which is retained in chromatographic columns filled with alumina whose maximum capacity is 0.2%. Given these constraints new methods of preparation 99 Mo/ 99m Tc generators have been developed using zirconium molybdates gels containing up to 30% of Mo, which is part of the generator matrix, and retaining quality and purity similar characteristics to those commercial generators. The present study aims to determine the flow of agitation, temperature and drying time optimal to prepare 99 Mo/ 99m Tc generators based on 99 Mo zirconium molybdates in the Gel Synthesis Device 99 Mo/ 99m Tc Generators designed and built by groups of the Radioactive Materials Research Laboratory and Automation and Instrumentation Department of the National Institute of Nuclear Research. (Author)

  11. Diadenosine polyphosphates in the tears of aniridia patients.

    Science.gov (United States)

    Peral, Assumpta; Carracedo, Gonzalo; Pintor, Jesús

    2015-08-01

    To quantify diadenosine polyphosphate levels in tears of congenital aniridia patients to estimate the ocular surface changes associated with congenital aniridia compared to normal individuals. Fifteen patients diagnosed with congenital aniridia and a control group of forty volunteers were studied. Tears were collected to quantify the levels of diadenosine polyphosphates Ap4 A and Ap5 A by high-performance liquid chromatography (H.P.L.C). Break-up time (BUT), corneal staining, McMonnies questionnaire and the Schirmer I test were applied to both groups. Dinucleotides in congenital aniridia patients were higher than in control subjects. For the congenital aniridia group, under 15 years old, the values were 0.77 ± 0.01 μm and 0.17 ± 0.02 μm for Ap4 A and Ap5 A, respectively. The group aged from 15 to 40 years old provided concentrations of 4.37 ± 0.97 μm and 0.46 ± 0.05 μm for Ap4 A and Ap5 A, the group over 40 gave concentrations of 11.17 ± 5.53 μm and 0.68 ± 0.17 μm for Ap4 A and Ap5 A. Dinucleotide concentrations increased with age, being statistically significant different among the three age groups (p tear secretion and no dry eye McMonnies scores, except for the group over 40 years old. BUT values decreased and corneal staining increased with age and correlated with the levels of diadenosine polyphosphates (p tears increase in aniridia patients compared with healthy subjects, and they seem to be related with the progression of corneal disorders in aniridia patients, both of which increase with ageing. © 2014 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  12. Preparation and characterization of a novel hyperbranched polyphosphate ester

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Sufang [College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou, Jiangsu Province 215123 (China); Key Laboratory for Green Chemical Process of Ministry of Education, Wuhan Institute of Technology, Wuhan, Hubei 430073 (China); Zhang, Daohong, E-mail: zhangdh@163.com [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, South-Central University for Nationalities, Wuhan, Hubei Province 430074 (China); Cheng, Xinjian; Li, Tingcheng; Zhang, Aiqing [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, South-Central University for Nationalities, Wuhan, Hubei Province 430074 (China); Li, Jinlin [College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou, Jiangsu Province 215123 (China); Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, South-Central University for Nationalities, Wuhan, Hubei Province 430074 (China)

    2012-11-15

    Polyphosphate esters have received a great deal of attention due to their important application in biomaterials field. Hyperbranched structure of polymers may support unique properties, including low viscosity and perfect intrinsic property. We report here three generations of hyperbranched polyphosphate esters (HPPE-1, HPPE-2 and HPPE-3) synthesized from a dehydrochlorination reaction between 1,3,5-tris(2-hydroxyethyl)cyanuric acid (THEIC) and phosphorus oxychloride (POCl{sub 3}), and characterize their chemical structures by FT-IR, {sup 1}H NMR, {sup 13}C NMR, {sup 31}P NMR and 2D NMR ({sup 1}H,{sup 1}H-COSY and {sup 13}C, {sup 1}H-HSQC) techniques. Degrees of branching of HPPE-1, HPPE-2 and HPPE-3 are 0.90, 0.91 and 0.87 respectively from the calculation of their {sup 13}C NMR spectra. Molecular weights of HPPE-1, HPPE-2 and HPPE-3 are m/z 1530, 1768 and 2750 from their MALDI-TOF-MS spectra. Study on thermal degradation mechanism of the HPPE-2 by a 3D FT-IR/TG technology shows that there are two cracking processes of its molecular chains, including the thermal degradation of hydroxylethyl-ended groups, nitrogen heterocycle and -CH{sub 2}CH{sub 2}- groups of HPPE-2. -- Highlights: Black-Right-Pointing-Pointer We prepared three novel hyperbranched polyphosphate esters (HPPE-1, HPPE-2 and HPPE-3). Black-Right-Pointing-Pointer Their chemical structures were characterized by FT-IR, 1D NMR and 2D NMR techniques. Black-Right-Pointing-Pointer Their degrees of branching were over 0.87. Black-Right-Pointing-Pointer TG-FTIR was used to study thermal degradation mechanism of the HPPE-2.

  13. Constitutive and regulated expression vectors to construct polyphosphate deficient bacteria

    Directory of Open Access Journals (Sweden)

    Jerez Carlos A

    2009-03-01

    Full Text Available Abstract Background Inorganic polyphosphate (polyP, a polymer of tens or hundreds of phosphate residues linked by ATP-like bonds, is found in all organisms and performs a wide variety of functions. PolyP is synthesized in bacterial cells by the actions of polyphosphate kinases (PPK1 and PPK2 and degraded by an exopolyphosphatase (PPX. Bacterial cells with polyP deficiencies are impaired in many structural and important cellular functions such as motility, quorum sensing, biofilm formation and virulence. Knockout mutants of the ppk1 gene have been the most frequent strategy employed to generate polyP deficient cells. Results As an alternative method to construct polyP-deficient bacteria we developed constitutive and regulated broad-host-range vectors for depleting the cellular polyP content. This was achieved by the overexpression of yeast exopolyphosphatase (PPX1. Using this approach in a polyphosphate accumulating bacteria (Pseudomonas sp. B4, we were able to eliminate most of the cellular polyP (>95%. Furthermore, the effect of overexpression of PPX1 resembled the functional defects found in motility and biofilm formation in a ppk1 mutant from Pseudomonas aeruginosa PAO1. The plasmids constructed were also successfully replicated in other bacteria such as Escherichia coli, Burkholderia and Salmonella. Conclusion To deplete polyP contents in bacteria broad-host-range expression vectors can be used as an alternative and more efficient method compared with the deletion of ppk genes. It is of great importance to understand why polyP deficiency affects vital cellular processes in bacteria. The construction reported in this work will be of great relevance to study the role of polyP in microorganisms with non-sequenced genomes or those in which orthologs to ppk genes have not been identified.

  14. Sorption of molybdenum by cellulose polyphosphate from acid solutions

    International Nuclear Information System (INIS)

    Luneva, N.K.; Oputina, A.G.; Ermolenko, I.N.

    1985-01-01

    The sorption of molybdenum on cellulose polyphosphate from acid solutions of ammonium molybdate depending on the phosphorus content in samples, concentration and pH of the solution, sorption time is studied. It is shown that a maximum molybdenum content on the cellulose samples with different phosphorus content is pointed out at an ammonium molybdate concentration 0.02 M. Saturation of the sorption curve is attained at molar ratio of adsrbed molybdenum to phosphorus 1:4. In case of small fillings the compound with molybdenum to phosphorus ratio 1:10 is formed

  15. Enzymes of yeast polyphosphate metabolism: structure, enzymology and biological roles.

    Science.gov (United States)

    Gerasimaitė, Rūta; Mayer, Andreas

    2016-02-01

    Inorganic polyphosphate (polyP) is found in all living organisms. The known polyP functions in eukaryotes range from osmoregulation and virulence in parasitic protozoa to modulating blood coagulation, inflammation, bone mineralization and cellular signalling in mammals. However mechanisms of regulation and even the identity of involved proteins in many cases remain obscure. Most of the insights obtained so far stem from studies in the yeast Saccharomyces cerevisiae. Here, we provide a short overview of the properties and functions of known yeast polyP metabolism enzymes and discuss future directions for polyP research. © 2016 Authors; published by Portland Press Limited.

  16. Fast sol-gel synthesis of LiFePO{sub 4}/C for high power lithium-ion batteries for hybrid electric vehicle application

    Energy Technology Data Exchange (ETDEWEB)

    Beninati, Sabina; Damen, Libero; Mastragostino, Marina [University of Bologna, Department of Metal Science, Electrochemistry and Chemical Techniques, Via San Donato 15, 40127 Bologna (Italy)

    2009-12-01

    LiFePO{sub 4}/C of high purity grade was successfully synthesized by microwave accelerated sol-gel synthesis and showed excellent electrochemical performance in terms of specific capacity and stability. This cathode material was characterized in battery configuration with a graphite counter electrode by USABC-DOE tests for power-assist hybrid electric vehicle. It yielded a non-conventional Ragone plot that represents complexity of battery functioning in power-assist HEV and shows that the pulse power capability and available energy of such a battery surpasses the DOE goal for such an application. (author)

  17. Design and synthesis of vanadium hydrazide gels for Kubas-type hydrogen adsorption: a new class of hydrogen storage materials.

    Science.gov (United States)

    Hoang, Tuan K A; Webb, Michael I; Mai, Hung V; Hamaed, Ahmad; Walsby, Charles J; Trudeau, Michel; Antonelli, David M

    2010-08-25

    In this paper we demonstrate that the Kubas interaction, a nondissociative form of weak hydrogen chemisorption with binding enthalpies in the ideal 20-30 kJ/mol range for room-temperature hydrogen storage, can be exploited in the design of a new class of hydrogen storage materials which avoid the shortcomings of hydrides and physisorpion materials. This was accomplished through the synthesis of novel vanadium hydrazide gels that use low-coordinate V centers as the principal Kubas H(2) binding sites with only a negligible contribution from physisorption. Materials were synthesized at vanadium-to-hydrazine ratios of 4:3, 1:1, 1:1.5, and 1:2 and characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption, elemental analysis, infrared spectroscopy, and electron paramagnetic resonance spectroscopy. The material with the highest capacity possesses an excess reversible storage of 4.04 wt % at 77 K and 85 bar, corresponding to a true volumetric adsorption of 80 kg H(2)/m(3) and an excess volumetric adsorption of 60.01 kg/m(3). These values are in the range of the ultimate U.S. Department of Energy goal for volumetric density (70 kg/m(3)) as well as the best physisorption material studied to date (49 kg H(2)/m(3) for MOF-177). This material also displays a surprisingly high volumetric density of 23.2 kg H(2)/m(3) at room temperature and 85 bar--roughly 3 times higher than that of compressed gas and approaching the DOE 2010 goal of 28 kg H(2)/m(3). These materials possess linear isotherms and enthalpies that rise on coverage and have little or no kinetic barrier to adsorption or desorption. In a practical system these materials would use pressure instead of temperature as a toggle and can thus be used in compressed gas tanks, currently employed in many hydrogen test vehicles, to dramatically increase the amount of hydrogen stored and therefore the range of any vehicle.

  18. New apparatus for direct counting of β particles from two-dimensional gels and an application to changes in protein synthesis due to cell density

    International Nuclear Information System (INIS)

    Anderson, H.L.; Puck, T.T.; Shera, E.B.

    1987-07-01

    A new method is described for scanning two-dimensional gels by the direct counting of β particles instead of autoradiography. The methodology is described; results are compared with autoradiographic results; and data are presented demonstrating changed patterns of protein synthesis accompanying changes in cell density. The method is rapid and permits identification of differences in protein abundance of approximately 10% for a substantial fraction of the more prominent proteins. A modulation effect of more than 5 standard deviations, accompanying contact inhibition of cell growth, is shown to occur for an appreciable number of these proteins. The method promises to be applicable to a variety of biochemical and genetic experiments designed to delineate changes in protein synthesis accompanying changes in genome, molecular environment, history, and state of differentiation of the cell populations studied. 13 refs., 8 figs., 4 tabs

  19. Inositol Polyphosphate Kinases, Fungal Virulence and Drug Discovery

    Directory of Open Access Journals (Sweden)

    Cecilia Li

    2016-09-01

    Full Text Available Opportunistic fungi are a major cause of morbidity and mortality world-wide, particularly in immunocompromised individuals. Developing new treatments to combat invasive fungal disease is challenging given that fungal and mammalian host cells are eukaryotic, with similar organization and physiology. Even therapies targeting unique fungal cell features have limitations and drug resistance is emerging. New approaches to the development of antifungal drugs are therefore needed urgently. Cryptococcus neoformans, the commonest cause of fungal meningitis worldwide, is an accepted model for studying fungal pathogenicity and driving drug discovery. We recently characterized a phospholipase C (Plc1-dependent pathway in C. neoformans comprising of sequentially-acting inositol polyphosphate kinases (IPK, which are involved in synthesizing inositol polyphosphates (IP. We also showed that the pathway is essential for fungal cellular function and pathogenicity. The IP products of the pathway are structurally diverse, each consisting of an inositol ring, with phosphate (P and pyrophosphate (PP groups covalently attached at different positions. This review focuses on (1 the characterization of the Plc1/IPK pathway in C. neoformans; (2 the identification of PP-IP5 (IP7 as the most crucial IP species for fungal fitness and virulence in a mouse model of fungal infection; and (3 why IPK enzymes represent suitable candidates for drug development.

  20. 300 Area Uranium Stabilization Through Polyphosphate Injection: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Vermeul, Vincent R.; Bjornstad, Bruce N.; Fritz, Brad G.; Fruchter, Jonathan S.; Mackley, Rob D.; Newcomer, Darrell R.; Mendoza, Donaldo P.; Rockhold, Mark L.; Wellman, Dawn M.; Williams, Mark D.

    2009-06-30

    The objective of the treatability test was to evaluate the efficacy of using polyphosphate injections to treat uranium-contaminated groundwater in situ. A test site consisting of an injection well and 15 monitoring wells was installed in the 300 Area near the process trenches that had previously received uranium-bearing effluents. This report summarizes the work on the polyphosphate injection project, including bench-scale laboratory studies, a field injection test, and the subsequent analysis and interpretation of the results. Previous laboratory tests have demonstrated that when a soluble form of polyphosphate is injected into uranium-bearing saturated porous media, immobilization of uranium occurs due to formation of an insoluble uranyl phosphate, autunite [Ca(UO2)2(PO4)2•nH2O]. These tests were conducted at conditions expected for the aquifer and used Hanford soils and groundwater containing very low concentrations of uranium (10-6 M). Because autunite sequesters uranium in the oxidized form U(VI) rather than forcing reduction to U(IV), the possibility of re-oxidation and subsequent re-mobilization is negated. Extensive testing demonstrated the very low solubility and slow dissolution kinetics of autunite. In addition to autunite, excess phosphorous may result in apatite mineral formation, which provides a long-term source of treatment capacity. Phosphate arrival response data indicate that, under site conditions, the polyphosphate amendment could be effectively distributed over a relatively large lateral extent, with wells located at a radial distance of 23 m (75 ft) reaching from between 40% and 60% of the injection concentration. Given these phosphate transport characteristics, direct treatment of uranium through the formation of uranyl-phosphate mineral phases (i.e., autunite) could likely be effectively implemented at full field scale. However, formation of calcium-phosphate mineral phases using the selected three-phase approach was problematic. Although

  1. Ability of Polyphosphate and Nucleic Acids to Trigger Blood Clotting: Some Observations and Caveats

    Science.gov (United States)

    Smith, Stephanie A.; Gajsiewicz, Joshua M.; Morrissey, James H.

    2018-01-01

    Polyphosphate plays several roles in coagulation and inflammation, while extracellular DNA and RNA are implicated in thrombosis and as disease biomarkers. We sought to compare the procoagulant activities of polyphosphate versus DNA or RNA isolated from mammalian cells. In a recent study, we found that much of the procoagulant activity of DNA isolated from mammalian cells using Qiagen kits resisted digestion with nuclease or polyphosphatase, and even resisted boiling in acid. These kits employ spin columns packed with silica, which is highly procoagulant. Indeed, much of the apparent procoagulant activity of cellular DNA isolated with such kits was attributable to silica particles shed by the spin columns. Therefore, silica-based methods for isolating nucleic acids or polyphosphate from mammalian cells are not suitable for studying their procoagulant activities. We now report that polyphosphate readily co-purified with DNA and RNA using several popular isolation methods, including phenol/chloroform extraction. Thus, cell-derived nucleic acids are also subject to contamination with traces of cellular polyphosphate, which can be eliminated by alkaline phosphatase digestion. We further report that long-chain polyphosphate was orders of magnitude more potent than cell-derived DNA (purified via phenol/chloroform extraction) or RNA at triggering clotting. Additional experiments using RNA homopolymers found that polyG and polyI have procoagulant activity similar to polyphosphate, while polyA and polyC are not procoagulant. Thus, the procoagulant activity of RNA is rather highly dependent on base composition. PMID:29719836

  2. The importance of chain length for the polyphosphate enhancement of acidic potassium permanganate chemiluminescence.

    Science.gov (United States)

    Holland, Brendan J; Adcock, Jacqui L; Nesterenko, Pavel N; Peristyy, Anton; Stevenson, Paul G; Barnett, Neil W; Conlan, Xavier A; Francis, Paul S

    2014-09-09

    Sodium polyphosphate is commonly used to enhance chemiluminescence reactions with acidic potassium permanganate through a dual enhancement mechanism, but commercially available polyphosphates vary greatly in composition. We have examined the influence of polyphosphate composition and concentration on both the dual enhancement mechanism of chemiluminescence intensity and the stability of the reagent under analytically useful conditions. The average chain length (n) provides a convenient characterisation, but materials with similar values can exhibit markedly different distributions of phosphate oligomers. There is a minimum polyphosphate chain length (∼6) required for a large enhancement of the emission intensity, but no further advantage was obtained using polyphosphate materials with much longer average chain lengths. Providing there is a sufficient average chain length, the optimum concentration of polyphosphate is dependent on the analyte and in some cases, may be lower than the quantities previously used in routine detection. However, the concentration of polyphosphate should not be lowered in permanganate reagents that have been partially reduced to form high concentrations of the key manganese(III) co-reactant, as this intermediate needs to be stabilised to prevent formation of insoluble manganese(IV). Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Synthesis, characterization and in vitro bioactivity of sol-gel-derived SiO2-CaO-P2O5-MgO bioglass

    International Nuclear Information System (INIS)

    Saboori, A.; Rabiee, M.; Moztarzadeh, F.; Sheikhi, M.; Tahriri, M.; Karimi, M.

    2009-01-01

    In this study, the synthesis of SiO 2 -CaO-P 2 O 5 -MgO bioactive glass was performed by the sol-gel method. Sol-gel-derived bioglass material was produced both in powder and in discs form by uniaxial pressing, followed by sintering at 700 deg. C. The obtained material was evaluated by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) analyses. The biocompatibility evaluation of the formed glass was assessed through in vitro cell culture [alkaline phosphatase (AP) activity of osteoblasts] experiments and immersion studies in simulated body fluid (SBF) for different time intervals while monitoring the pH changes and the concentration of calcium, phosphorus and magnesium in the SBF medium. The SEM, XRD and FTIR studies were conducted before and after soaking of the material in SBF. At first, an amorphous calcium phosphate was formed; after 7 days this surface consisted of deposited crystalline apatite. The present investigation also revealed that the sol-gel derived quaternary bioglass system has the ability to support the growth of human fetal osteoblastic cells (hFOB 1.19). Finally, this material proved to be non-toxic and compatible for the proposed work in segmental defects in the goat model in vivo

  4. Use of Polyphosphate to Decrease Uranium Leaching in Hanford 300 Area Smear Zone Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Szecsody, James E.; Zhong, Lirong; Oostrom, Martinus; Vermeul, Vincent R.; Fruchter, Jonathan S.; Williams, Mark D.

    2012-09-30

    The primary objective of this study is to summarize the laboratory investigations performed to evaluate short- and long-term effects of phosphate treatment on uranium leaching from 300 area smear zone sediments. Column studies were used to compare uranium leaching in phosphate-treated to untreated sediments over a year with multiple stop flow events to evaluate longevity of the uranium leaching rate and mass. A secondary objective was to compare polyphosphate injection, polyphosphate/xanthan injection, and polyphosphate infiltration technologies that deliver phosphate to sediment.

  5. Novel route for rapid sol-gel synthesis of hydroxyapatite, avoiding ageing and using fast drying with a 50-fold to 200-fold reduction in process time

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Arfa, Basam A.E.; Salvado, Isabel M. Miranda, E-mail: isabelmsalvado@ua.pt; Ferreira, José M.F.; Pullar, Robert C., E-mail: rpullar@ua.pt

    2017-01-01

    We have developed an innovative, rapid sol-gel method of producing hydroxyapatite nanopowders that avoids the conventional lengthy ageing and drying processes (over a week), being 200 times quicker in comparison to conventional aqueous sol-gel preparation, and 50 times quicker than ethanol based sol-gel synthesis. Two different sets of experimental conditions, in terms of pH value (5.5 and 7.5), synthesis temperature (45 and 90 °C), drying temperature (60 and 80 °C) and calcination temperature (400 and 700 °C) were explored. The products were characterised by X-ray diffraction (XRD) Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and specific surface area (SSA) measurements. Pure hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}, HAp) was obtained for the powders synthesised at pH 7.5 and calcined at 400 °C, while biphasic mixtures of HAp/β-tricalcium phosphate (β-Ca{sub 3}(PO{sub 4}){sub 2}, TCP) were produced at pH 5.5 and (pH 7.5 at elevated temperature). The novel rapid drying was up to 200 times faster than conventional drying, only needing 1 h with no prior ageing step, and favoured the formation of smaller/finer nanopowders, while producing pure HAp or phase mixtures virtually identical to those obtained from the slow conventional drying method, despite the absence of a slow ageing process. The products of this novel rapid process were actually shown to have smaller crystallite sizes and larger SSA, which should result in increased bioactivity. - Highlights: • Fast, novel sol-gel synthesis of HAp nanopowders, requiring just 1 h for drying • A much shortened process, 200 times faster than the usual slow drying/ageing times • Compares rapidly produced HAp with that from a typical 216 h drying/ageing process • Both methods produce very similar products, but rapid HAp had a larger surface area. • Both methods produced pure HAp at 400 °C, and a HAp/TCP mix at 700 °C.

  6. Synthesis of LaNiO{sub 3} perovskite by the modified proteic gel method and study of catalytic properties in the syngas production

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Jose C.; Mesquita, Maria E.; Pedrosa, Anne M. Garrido, E-mail: annemgp@ufs.br, E-mail: annemgp@yahoo.com [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Departamento de Quimica e Engenharia Quimica; Souza, Marcelo J.B. [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Departamento de Engenharia Quimica; Ruiz, Juan A.C. [Centro de Tecnologias do Gas e Energias Renovaveis (CTGAS-ER), Natal, RN (Brazil). Laboratorio de Processamento do Gas; Melo, Dulce M.A. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Centro de Ciencias Exatas e da Terra. Depaertamento de Quimica

    2012-10-15

    This work describes a study on the synthesis of LaNiO{sub 3} perovskites via the modified proteic gel method, varying collagen content and on the catalytic activity of LaNiO{sub 3} and LaNiO{sub 3}/Al{sub 2}O{sub 3} in the syngas (CO + H{sub 2}) production. X-ray diffraction patterns revealed the formation of perovskite structure in all samples prepared by proteic gel synthesis method, varying collagen content and after calcination at 700 deg C for 2 h. LaNiO{sub 3}/Al{sub 2}O{sub 3} catalyst prepared by the impregnation method showed diffraction peaks due to the perovskite structure and to the support (Al{sub 2}O{sub 3}). This catalyst presented: specific surface of 46.1 m{sup 2} g{sup -1}, two reduction peaks in the temperature programmed reduction (TPR) profile and 46% of methane conversion (by the partial oxidation of methane using oxygen) after 18 h of reaction. (author)

  7. Optimization of Catalytic Ozonation Process for Formaldehyde Mineralization from Synthetic Wastewater by Fe/MgO Nanoparticles Synthesis by Sol-Gel Method by Response Surface Model

    Directory of Open Access Journals (Sweden)

    Ghorban Asgari

    2014-09-01

    Full Text Available Background: Design experiment stages of formalin mineralization process by center composition design (CCD cause ease of work, reducing the number of samples, increasing the accuracy of optimized conditions and the interaction parameters determined during the process. The aim of this study was optimization of catalytic ozonation process for formaldehyde mineralization from synthetic wastewater by Fe/MgO nanoparticles synthesis by sol-gel method by response surface model. Methods: This experimental study was conducted in a semi-batch reactor, using a RSM by taking 3 factors in the final stage of pH (7-9, reaction time (10-20 min and catalyst dose (1.1-1.3 g/L was investigated. Synthesis of nanoparticles was done by sol-gel method. The results were analyzed by Design Expert 7.0.1 software. Results: The results showed that the process was dependent on the parameters studied and changing each parameter, affected the process efficiency and other parameters. The optimum conditions predicted for the process was 86.51% of mineralization efficiency. Optimum condition included pH=8.82, reaction time of 20 minute and catalyst dose of 1.3 g/L. The correlation coefficient for the process was determined 0.91. Conclusion: Using a statistical model could reduce the number of experiments, the accuracy and the prediction process. The catalytic ozonation process has the ability to remove formaldehyde with high efficiency and the process was environmental friendly.

  8. In-situ sol-gel synthesis and thin film deposition of Cu(In,Ga)(S,Se)2 solar cells

    International Nuclear Information System (INIS)

    Oliveira, L.; Lyubenova, T.; Marti, R.; Fraga, D.; Rey, A.; Carda, J.; Kozhukharov, V.

    2013-01-01

    Full text: Nowadays chalcogenide-based solar cells, like Cu(In,Ga)Se 2 , are competitive in the photovoltaic market, due to its improved performances like higher efficiency (20,3%), long-time stability and excellent durability. In addition, CIGS stand out with an exceptionally high absorption coefficient (more than; 105/cm for 1.5eV) and higher energy photons. These properties make it an excellent candidate as an absorber material for large scale production of photovoltaic modules for building-integrated applications. Traditional methods of manufacture involve vacuum processes including co-evaporation and sputtering that increase production costs. With the aim to lower the expenses by using non-vacuum solution processes we propose an ‘in-situ’ sol-gel synthesis route and direct thin film deposition in the same production step. As a result, we achieved better stoichiometric control, simplicity in the procedure and cost reduction. In this work we describe a procedure to obtain CIGS absorber layer by soft chemistry technique and further deposition onto different substrates. Preparation parameters like precursors, chemical composition, solvents, thermal treatment factors (temperature, time, and atmosphere) were detailed studied. Finally, the resulting materials were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) coupled with Energy dispersive X-ray analysis (EDAX), UV-VIS Spectroscopy among others.; key words: sol-gel synthesis, thin film deposition, photovoltaic modules, solar cells

  9. Synthesis, structural investigation and magnetic properties of Zn2+ substituted cobalt ferrite nanoparticles prepared by the sol–gel auto-combustion technique

    International Nuclear Information System (INIS)

    Raut, A.V.; Barkule, R.S.; Shengule, D.R.; Jadhav, K.M.

    2014-01-01

    Structural morphology and magnetic properties of the Co 1−x Zn x Fe 2 O 4 (0.0≤x≥1.0) spinel ferrite system synthesized by the sol–gel auto-combustion technique using nitrates of respective metal ions have been studied. The ratio of metal nitrates to citric acid was taken at 1:3. The as prepared powder of cobalt zinc ferrite was sintered at 600 °C for 12 h after TG/DTA thermal studies. Compositional stoichiometry was confirmed by energy dispersive analysis of the X-ray (EDAX) technique. Single phase cubic spinel structure of Co–Zn nanoparticles was confirmed by XRD data. The average crystallite size (t), lattice constant (a) and other structural parameters of zinc substituted cobalt ferrite nanoparticles were calculated from XRD followed by SEM and FTIR. It is observed that the sol–gel auto-combustion technique has many advantages for the synthesis of technologically applicable Co–Zn ferrite nanoparticles. The present investigation clearly shows the effect of the synthesis method and possible relation between magnetic properties and microstructure of the prepared samples. Increase in nonmagnetic Zn 2+ content in cobalt ferrite nanoparticles is followed by decrease in n B , M s and other magnetic parameters. Squareness ratio for the Co-ferrite was 1.096 at room temperature. - Highlights: • Co–Zn nanoparticles are prepared by sol–gel auto-combustion method. • Structural properties were characterized by XRD, SEM, and FTIR. • Compositional stoichiometry was confirmed by EDAX analysis. • Magnetic parameters were measured by the pulse field hysteresis loop technique

  10. Sol-gel chemistry applied to the synthesis of polymetallic oxides including actinides reactivity and structure from solution to solid state

    International Nuclear Information System (INIS)

    Lemonnier, St.

    2006-02-01

    Minor actinides transmutation is studied at present in order to reduce the radiotoxicity of nuclear waste and the assessment of its technical feasibility requires specific designed materials. When considering americium, yttria stabilized zirconia (Am III YII Zriv)Or x is among the ceramic phases that one which presents the required physico-chemical properties. An innovative synthesis of this mixed oxide by sol-gel process is reported in this manuscript. The main aim of this work is to adjust the reactivity of the different metallic cations in aqueous media using complexing agent, in order to initiate a favourable interaction for a homogeneous elements repartition in the forming solid phase. The originality of the settled synthesis lies on an in-situ formation of a stable and monodisperse nano-particles dispersion in the presence of acetylacetone. The main reaction mechanisms have been identified: the sol stabilisation results from an original interaction between the three compounds (Zrly, trivalent cations and acetylacetone). The sol corresponds to a structured system at the nanometer scale for which zirconium and trivalent cations are homogeneously dispersed, preliminary to the sol-gel transition. Furthermore, preliminary studies were carried out with a view to developing materials. They have demonstrated that numerous innovative and potential applications can be developed by taking advantage of the direct and controlled formation of the sol and by adapting the sol-gel transition. The most illustrating result is the preparation of a sintered pellet with the composition Am0,13Zro,73Yo,0901,89 using this approach. (author)

  11. Novel route for rapid sol-gel synthesis of hydroxyapatite, avoiding ageing and using fast drying with a 50-fold to 200-fold reduction in process time.

    Science.gov (United States)

    Ben-Arfa, Basam A E; Salvado, Isabel M Miranda; Ferreira, José M F; Pullar, Robert C

    2017-01-01

    We have developed an innovative, rapid sol-gel method of producing hydroxyapatite nanopowders that avoids the conventional lengthy ageing and drying processes (over a week), being 200 times quicker in comparison to conventional aqueous sol-gel preparation, and 50 times quicker than ethanol based sol-gel synthesis. Two different sets of experimental conditions, in terms of pH value (5.5 and 7.5), synthesis temperature (45 and 90°C), drying temperature (60 and 80°C) and calcination temperature (400 and 700°C) were explored. The products were characterised by X-ray diffraction (XRD) Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and specific surface area (SSA) measurements. Pure hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 , HAp) was obtained for the powders synthesised at pH7.5 and calcined at 400°C, while biphasic mixtures of HAp/β-tricalcium phosphate (β-Ca 3 (PO 4 ) 2 , TCP) were produced at pH5.5 and (pH7.5 at elevated temperature). The novel rapid drying was up to 200 times faster than conventional drying, only needing 1h with no prior ageing step, and favoured the formation of smaller/finer nanopowders, while producing pure HAp or phase mixtures virtually identical to those obtained from the slow conventional drying method, despite the absence of a slow ageing process. The products of this novel rapid process were actually shown to have smaller crystallite sizes and larger SSA, which should result in increased bioactivity. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Synthesis, structural investigation and magnetic properties of Zn{sup 2+} substituted cobalt ferrite nanoparticles prepared by the sol–gel auto-combustion technique

    Energy Technology Data Exchange (ETDEWEB)

    Raut, A.V., E-mail: nano9993@gmail.com [Vivekanand Arts and Sardar Dalipsingh Commerce and Science College, Aurangabad, 431004 Maharastra (India); Barkule, R.S.; Shengule, D.R. [Vivekanand Arts and Sardar Dalipsingh Commerce and Science College, Aurangabad, 431004 Maharastra (India); Jadhav, K.M., E-mail: drjadhavkm@gmail.com [Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad, 431004 Maharastra (India)

    2014-05-01

    Structural morphology and magnetic properties of the Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (0.0≤x≥1.0) spinel ferrite system synthesized by the sol–gel auto-combustion technique using nitrates of respective metal ions have been studied. The ratio of metal nitrates to citric acid was taken at 1:3. The as prepared powder of cobalt zinc ferrite was sintered at 600 °C for 12 h after TG/DTA thermal studies. Compositional stoichiometry was confirmed by energy dispersive analysis of the X-ray (EDAX) technique. Single phase cubic spinel structure of Co–Zn nanoparticles was confirmed by XRD data. The average crystallite size (t), lattice constant (a) and other structural parameters of zinc substituted cobalt ferrite nanoparticles were calculated from XRD followed by SEM and FTIR. It is observed that the sol–gel auto-combustion technique has many advantages for the synthesis of technologically applicable Co–Zn ferrite nanoparticles. The present investigation clearly shows the effect of the synthesis method and possible relation between magnetic properties and microstructure of the prepared samples. Increase in nonmagnetic Zn{sup 2+} content in cobalt ferrite nanoparticles is followed by decrease in n{sub B}, M{sub s} and other magnetic parameters. Squareness ratio for the Co-ferrite was 1.096 at room temperature. - Highlights: • Co–Zn nanoparticles are prepared by sol–gel auto-combustion method. • Structural properties were characterized by XRD, SEM, and FTIR. • Compositional stoichiometry was confirmed by EDAX analysis. • Magnetic parameters were measured by the pulse field hysteresis loop technique.

  13. Sol-gel synthesis of YBa2Cu3O7-x superconductor by mixed organic-inorganic polymerization

    International Nuclear Information System (INIS)

    Valente, I.; Sanchez, C.; Henry, M.; Livage, J.

    1989-01-01

    Sol-gel processes are quite attractive methods to produce films or fibers of high Tc superconducting materials. The gel step allows a good chemical homogeneity and generally provides a rather low processing temperature. Blue sols or monolithic gels can be easily produced using mixed organic-inorganic polymerisation of molecular precursors. An aqueous solution of copper, barium acetates and yttrium nitrate is mixed with an acrylic acid solution where a radical organic polymerisation process has been initiated. After pH adjustments, the viscosity of the resulting solution can be adjusted by heating. After drying at 150 0 C and calcination above 700 0 C, the YBaCuO network is formed and superconducting properties appears above 850 0 C. Fine particles (0.1-1 μm) are obtained which can be sintered to produce a ceramic material with a particularly narrow resistive transition [fr

  14. Low-temperature synthesis and characterization of anatase TiO{sub 2} nanoparticles by an acid assisted sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Leyva-Porras, C. [Centro de Investigación en Materiales DIP-CUCEI, Universidad de Guadalajara, Av. Revolución # 1500, Col. Olímpica, C.P. 44430, Guadalajara (Mexico); Centro de Investigación en Materiales Avanzados, S.C. (CIMAV), Alianza Norte No. 202, Parque de Investigación e Innovación Tecnológica (PIIT), Carretera Aeropuerto km. 10, C.P. 66600, Apodaca, N.L. (Mexico); Toxqui-Teran, A.; Vega-Becerra, O. [Centro de Investigación en Materiales Avanzados, S.C. (CIMAV), Alianza Norte No. 202, Parque de Investigación e Innovación Tecnológica (PIIT), Carretera Aeropuerto km. 10, C.P. 66600, Apodaca, N.L. (Mexico); Miki-Yoshida, M. [Centro de Investigación en Materiales Avanzados, S.C. (CIMAV), Miguel de Cervantes No. 120, Parque Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico); Rojas-Villalobos, M.; García-Guaderrama, M. [Centro de Investigación en Materiales DIP-CUCEI, Universidad de Guadalajara, Av. Revolución # 1500, Col. Olímpica, C.P. 44430, Guadalajara (Mexico); and others

    2015-10-25

    The synthesis of anatase TiO{sub 2} nanoparticles by an acid-assisted sol–gel method at 25 and 80 °C is described. Specifically, acetic acid (AA) was used and the evolution of the anatase phase with the amount of AA was observed. The results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) both showed that a pure anatase phase was obtained with particle size smaller than 5 nm. Structural refinements and quantitative determination of phase composition was achieved by using the Rietveld method. The particle size distribution became slightly narrower as the amount of AA was increased. Raman spectroscopy showed that when the amount of AA was increased a small amount of brookite was present at the contamination level. The anatase phase was studied by differential thermal analysis (DTA), providing phase stability up to 600 °C. These and other results were discussed in terms of particle size and structure. Likewise, the formation of the anatase phase under these synthesis conditions was explained. - Highlights: • Synthesis of anatase TiO{sub 2} nanoparticles by an acid assisted sol–gel method at mild conditions. • Microstructure characterization by XRD, TEM and Raman spectroscopy. • Observation of the formation and evolution of the anatase phase as acetic acid was increased. • Anatase thermal stability up to 600 °C and band gap range between 3.2 and 3.5 eV. • A simplified method which can be considered as a green chemistry process.

  15. Probiotic-derived polyphosphate enhances the epithelial barrier function and maintains intestinal homeostasis through integrin-p38 MAPK pathway.

    Directory of Open Access Journals (Sweden)

    Shuichi Segawa

    Full Text Available Probiotics exhibit beneficial effects on human health, particularly in the maintenance of intestinal homeostasis in a complex manner notwithstanding the diversity of an intestinal flora between individuals. Thus, it is highly probable that some common molecules secreted by probiotic and/or commensal bacteria contribute to the maintenance of intestinal homeostasis and protect the intestinal epithelium from injurious stimuli. To address this question, we aimed to isolate the cytoprotective compound from a lactobacillus strain, Lactobacillus brevis SBC8803 which possess the ability to induce cytoprotective heat shock proteins in mouse small intestine. L. brevis was incubated in MRS broth and the supernatant was passed through with a 0.2-µm filter. Caco2/bbe cells were treated with the culture supernatant, and HSP27 expression was evaluated by Western blotting. HSP27-inducible components were separated by ammonium sulfate precipitation, DEAE anion exchange chromatography, gel filtration, and HPLC. Finally, we identified that the HSP27-inducible fraction was polyphosphate (poly P, a simple repeated structure of phosphates, which is a common product of lactobacilli and other bacteria associated with intestinal microflora without any definitive physiological functions. Then, poly P was synthesized by poly P-synthesizing enzyme polyphosphate kinase. The synthesized poly P significantly induced HSP27 from Caco2/BBE cells. In addition, Poly P suppressed the oxidant-induced intestinal permeability in the mouse small intestine and pharmacological inhibitors of p38 MAPK and integrins counteract its protective effect. Daily intrarectal administration of poly P (10 µg improved the inflammation grade and survival rate in 4% sodium dextran sulfate-administered mice. This study, for the first time, demonstrated that poly P is the molecule responsible for maintaining intestinal barrier actions which are mediated through the intestinal integrin β1-p38 MAPK.

  16. Levels of acid-soluble polyphosphate in growing cultures of Saccharomyces cerevisiae.

    OpenAIRE

    Solimene, R; Guerrini, A M; Donini, P

    1980-01-01

    Short-chain acid-soluble polyphosphates were extracted from growing cultures of Saccharomyces cerevisiae, and the changes in the levels of these compounds were determined. The production of acid-soluble polyphosphates correlated with the mitochondrial activities since it occurred in two bursts in respiration-competent yeast cells and in only one burst in respiration-deficient yeast cells. The possible role of these compounds is discussed.

  17. Synthesis and Characterization of a Gel-Type Electrolyte with Ionic Liquid Added for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Le-Yan Shi

    2013-01-01

    Full Text Available This study intends to develop the electrolyte needed in dye-sensitized solar cells (DSSCs. Moreover, three different ionic liquids in different molalities are added to the gel-type electrolyte. Experimental results show that the DSSC composed of the gel-type electrolyte with no ionic liquid added can acquire 4.13% photoelectric conversion efficiency. However, the DSSC composed of the gel-type electrolyte with 0.4 M of 1-butyl-3-methylimidazolium chloride added has an open-circuit voltage of 810 mV, a short-circuit current density of 9.56 mA/cm2, and photoelectric conversion efficiency reaching 4.89%. Comparing this DSSC with the DSSC with no ionic liquid added, the photoelectric conversion efficiency can be enhanced by 18.4%. As to durability, the DSSC composed of the gel-type electrolyte with ionic liquid added still has a photoelectric conversion efficiency of 3.28% on the 7th day after it is stored in an enclosed space and maintains 0.72% efficiency on the 14th day. When the proposed DSSC is compared with the DSSC prepared by using a liquid-type electrolyte, the durability of its photoelectric conversion efficiency can be increased by 7 times.

  18. Sol–gel immobilization of Alcalase from Bacillus licheniformis for application in the synthesis of C-terminal peptide amides

    NARCIS (Netherlands)

    Corici, L.N.; Frissen, A.E.; Zoelen, van D.J.; Eggen, I.F.; Peter, F.; Davidescu, C.M.; Boeriu, C.G.

    2011-01-01

    Alcalase 2.4L FG, a commercial preparation of Subtilisin A, was physically entrapped in glass sol–gel matrices using alkoxysilanes of different types mixed with tetramethoxysilane (TMOS). The materials were used for catalyzing C-terminal amidation of Z-Ala-Phe-OMe in a mixture of tert-butanol/DMF.

  19. Involvement of polyphosphate kinase in virulence and stress tolerance of uropathogenic Proteus mirabilis.

    Science.gov (United States)

    Peng, Liang; Jiang, Qiao; Pan, Jia-Yun; Deng, Cong; Yu, Jing-Yi; Wu, Xiao-Man; Huang, Sheng-He; Deng, Xiao-Yan

    2016-04-01

    Proteus mirabilis (P. mirabilis), a gram-negative enteric bacterium, frequently causes urinary tract infections. Many virulence factors of uropathogenic P. mirabilis have been identified, including urease, flagella, hemolysin and fimbriae. However, the functions of polyphosphate kinase (PPK), which are related to the pathogenicity of many bacteria, remain entirely unknown in P. mirabilis. In this study, a ppk gene encoding the PPK insertional mutant in P. mirabilis strain HI4320 was constructed, and its biological functions were examined. The results of survival studies demonstrated that the ppk mutant was deficient in resistance to oxidative, hyperosmotic and heat stress. The swarming and biofilm formation abilities of P. mirabilis were also attenuated after the ppk interruption. In vitro and in vivo experiments suggested that ppk was required for P. mirabilis to invade the bladder. The negative phenotypes of the ppk mutant could be restored by ppk gene complementation. Furthermore, two-dimensional gel electrophoresis and liquid chromatography-mass spectrometry were used to analyze the proteomes of the wild-type strain and the ppk mutant. Compared with the wild-type strain, seven proteins including TonB-dependent receptor, universal stress protein G, major mannose-resistant/Proteus-like fimbrial protein (MR/P fimbriae), heat shock protein, flagellar capping protein, putative membrane protein and multidrug efflux protein were down-regulated, and four proteins including exported peptidase, repressor protein for FtsI, FKBP-type peptidyl-prolyl cis-trans isomerase and phosphotransferase were up-regulated in the ppk mutant. As a whole, these results indicate that PPK is an important regulator and plays a crucial role in stress tolerance and virulence in uropathogenic P. mirabilis.

  20. Synthesis and characterization of hollow α-Fe2O3 sub-micron spheres prepared by sol–gel

    International Nuclear Information System (INIS)

    León, Lizbet; Bustamante, Angel; Osorio, Ana; Olarte, G. S.; Santos Valladares, Luis De Los; Barnes, Crispin H. W.; Majima, Yutaka

    2011-01-01

    In this work we report the preparation of magnetic hematite hollow sub-micron spheres (α-Fe 2 O 3 ) by colloidal suspensions of ferric nitrate nine-hydrate (Fe(NO 3 ) 3 ·9H 2 O) particles in citric acid solution by following the sol–gel method. After the gel formation, the samples were annealed at different temperatures in an oxidizing atmosphere. Annealing at 180°C resulted in an amorphous phase, without iron oxide formation. Annealing at 250°C resulted in coexisting phases of hematite, maghemite and magnetite, whereas at 400°C, only hematite and maghemite were found. Pure hematite hollow sub-micron spheres with porous shells were formed after annealing at 600°C. The characterization was performed by X-ray diffraction (XRD), Mössbauer spectroscopy (MS) and scanning electron microscopy (SEM).

  1. Synthesis, characterization and optical band gap of Pirochromite (MgCr2O4 Nanoparticles by Stearic Acid Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    Ehsan Jafarnejad

    2016-09-01

    Full Text Available Pirochromite (MgCr2O4 nanoparticles were successfully prepared in this study. During synthesis of the pirochromite nanoparticles, a sol-gel was prepared by using magnesium acetate and potassium dichromate as magnesium and chromium sources and by using stearic acid as the network. Infrared spectroscopy (FT-IR, X-ray diffraction (XRD, transmission electron microscope (TEM, scanning electron microscope (SEM, and energy-dispersive X-ray spectroscopy (EDX were used for the elemental analysis, and diffuse reflectance spectroscopy (DRS and vibrating sample magnetometer (VSM were used in order to identify, provide a fuzzy diagnosis, and determine the size and morphology of the particles, as well as to analyze the optical and magnetic properties of the particles. The particle size of MgCr2O4 nanoparticles was observed to fall within a range of 39 nm–71 nm.

  2. Synthesis and characterization of mesoporous ceria/alumina nanocomposite materials via mixing of the corresponding ceria and alumina gel precursors.

    Science.gov (United States)

    Khalil, Kamal M S

    2007-03-01

    Mesoporous ceria/alumina, CeO(2)/Al(2)O(3), composites containing 10, 20 and 30% (w/w) ceria were prepared by a novel gel mixing method. In the method, ceria gel (formed via hydrolysis of ammonium cerium(IV) nitrate by aqueous ammonium carbonate solution) and alumina gel (formed via controlled hydrolysis of aluminum tri-isopropoxide) were mixed together. The mixed gel was subjected to subsequent drying and calcination for 3 h at 400, 600, 800 and 1000 degrees C. The uncalcined (dried at 110 degrees C) and the calcined composites were investigated by different techniques including TGA, DSC, FTIR, XRD, SEM and nitrogen adsorption/desorption isotherms. Results indicated that composites calcined for 3 h at 800 degrees C mainly kept amorphous alumina structure and gamma-alumina formed only upon calcinations at 1000 degrees C. On the other hand, CeO(2) was found to crystallize in the common ceria, cerinite, phase and it kept this structure over the entire calcination range (400-1000 degrees C). Therefore, high surface areas, stable surface textures, and non-aggregated nano-sized ceria dispersions were obtained. A systematic texture change based on ceria ratio was observed, however in all cases mesoporous composite materials exposing thermally stable texture and structure were obtained. The presented method produces composite ceria/alumina materials that suit different applications in the field of catalysis and membranes technology, and throw some light on physicochemical factors that determine textural morphology and thermal stability of such important composite.

  3. Synthesis and characterization of high surface area nanosilica from rice husk ash by surfactant-free sol-gel method

    Czech Academy of Sciences Publication Activity Database

    Hassan, A F.; Abdelghny, A.M.; Elhadidy, Hassan; Youssef, A.M.

    2014-01-01

    Roč. 69, č. 3 (2014), 465-472 ISSN 0928-0707 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068; GA MŠk(CZ) EE2.3.20.0214 Institutional support: RVO:68081723 Keywords : Nanosilica * Rice husk * Sol-gel method * N-2 adsorption Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.532, year: 2014

  4. Sol-gel synthesis and characterization of fine-grained ceramics in the alumina-titania system

    Energy Technology Data Exchange (ETDEWEB)

    Otterstein, E. [Institute of Physics, University of Rostock, August-Bebel-Strasse 55, 18055 Rostock (Germany)], E-mail: otterstein@physik1.uni-rostock.de; Karapetyan, G. [Institute of Chemistry, University of Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock (Germany); Nicula, R. [Institute of Physics, University of Rostock, August-Bebel-Strasse 55, 18055 Rostock (Germany); Stir, M. [Institute of Physics, University of Rostock, August-Bebel-Strasse 55, 18055 Rostock (Germany); National Institute for Materials Physics, 105b Atomistilor Strasse, P.O.B. MG7, 077125 Bucharest-Magurele (Romania); Schick, C. [Institute of Physics, University of Rostock, Universitaetsplatz 3, 18051 Rostock (Germany); Burkel, E. [Institute of Physics, University of Rostock, August-Bebel-Strasse 55, 18055 Rostock (Germany)

    2008-02-05

    Fine-grained ceramics of the Al{sub 2}O{sub 3}-TiO{sub 2} system were synthesised by reactive sintering of sol-gel precursors (Al- and Ti-alkoxides). The thermal behaviour of the as-prepared xerogels was examined by thermal analysis and X-ray powder diffraction. Preliminary results concerning powder consolidation into bulk ceramic parts using spark plasma sintering (SPS) are discussed.

  5. Effect of synthesis route on the multiferroic properties of BiFeO3: A comparative study between solid state and sol–gel methods

    International Nuclear Information System (INIS)

    Suresh, Pittala; Srinath, S.

    2015-01-01

    Polycrystalline BiFeO 3 (BFO) powder was prepared through optimized solid state (SS) and sol–gel (SG) reaction methods. The effect of preparation routes on the crystal purity and multiferroic properties of the BFO was investigated. Sol–gel synthesis results almost a single-phase material at relatively lower temperatures while the solid-state method results into BFO with a small amount of Bi 2 Fe 4 O 9 secondary phase. The grain size of SG processed sample reduces to half the size of the one that is prepared by SS. Elemental analysis shows a stoichiometric Bi:Fe content for SG samples by restricting the Bi loss. In comparison with the SS samples, dielectric constant of SG samples exhibit higher values with Maxwell–Wagner type dielectric dispersion. A cusp at 50 K was seen in M–T curves for SS samples, for which no frequency dependence was observed in a.c susceptibility measurements ruling out the earlier predictions of spin glass nature in this system. M−H loops show a typical antiferromagnetic nature at 300 K while a weak ferromagnetic behavior is found at 10 K. A slight increase in H C and M r was observed for SG samples over SS. The improved properties of SG processed BFO makes it more promising for applications. - Highlights: • Optimized conditions to attain the BiFeO 3 with minimized impurities are reported. • The influence of the impurities on the dielectric, magnetic properties is reported. • Maxwell–Wagner relaxation is found for BiFeO 3 prepared by sol–gel technique. • a.c. susceptibility measurements ruled out the possibility of spin glass nature. • The anomalous behavior of H C with the temperature is reported

  6. Crystal structure of polyphosphates NaCd(PO3)3 and NaMn(PO3)3

    International Nuclear Information System (INIS)

    Murashova, E.V.; Chudinova, N.N.

    1997-01-01

    Crystal structure of NaCd(PO 3 ) 3 (1) and NaMn(PO 3 ) 3 (2) isostructural polyphosphates was determined for twin samples. Rhombic lattice parameters of (1): a = 14.678, b = 14.669, c = 14.705 A, sp. gr. P2 1 2 1 2 1 , Z = 16. The structure of compounds is of frame type. Polyphosphate chain with repetition period of 24 PO 4 tetrahedrons contacts with NaO 6 and M 2 O 6 octahedrons by means of common oxygen vertices. Similarities and differences in structure of mentioned polyphosphates and earlier analyzed NaMg(PO 3 ) 3 polyphosphate are noted [ru

  7. Synthesis of nanocrystalline LaF3 doped silica glasses by hydrofluoric acid catalyzed sol–gel process

    International Nuclear Information System (INIS)

    Nagayama, Shuhei; Kajihara, Koichi; Kanamura, Kiyoshi

    2012-01-01

    Highlights: ► Silica glasses doped by LaF 3 nanocrystals are obtained by HF-catalyzed sol–gel method. ► The processing time (∼1 week) is much shorter than that of previous studies. ► The uptake of SiF groups in the glass matrix greatly reduces the SiOH concentration. ► Effects of sintering conditions and properties of Er 3+ -doped samples are presented. - Abstract: Silica glasses doped with LaF 3 nanocrystals were prepared by HF-catalyzed sol–gel method. HF was used both as fluorine source and as catalyst of the sol–gel reaction, making it possible to shorten the processing time with reducing the concentration of SiOH groups to ∼10 18 cm −3 . The resultant glasses are transparent at visible spectral range, and the optical loss at the ultraviolet absorption edge is dominated by the Rayleigh scattering from LaF 3 crystallites. The size of LaF 3 crystallites increases with an increase in the sintering temperature and time, and is smaller than ∼40 nm in samples showing good visible transparency. Green upconversion photoluminescence is observed in an Er 3+ -doped sample under excitation at 980 nm.

  8. Simple and Efficient Synthesis of Iron Oxide-Coated Silica Gel Adsorbents for Arsenic Removal: Adsorption Isotherms and Kinetic Study

    Energy Technology Data Exchange (ETDEWEB)

    Arifin, Eric; Lee, Jiukyu [Interdisciplinary Program in Nanoscience and Technology, Virginia (United States); Cha, Jinmyung [Seoul National Univ., Seoul (Korea, Republic of)

    2013-08-15

    Iron oxide (ferrihydrite, hematite, and magnetite) coated silica gels were prepared using a low-cost, easily-scalable and straightforward method as the adsorbent material for arsenic removal application. Adsorption of the anionic form of arsenic oxyacids, arsenite (AsO{sup 2-}) and arsenate (AsO{sub 4}{sup -3}), onto hematite coated silica gel was fitted against non-linear 3-parameter-model Sips isotherm and 2-parameter-model Langmuir and Freundlich isotherm. Adsorption kinetics of arsenic could be well described by pseudo-second-order kinetic model and value of adsorption energy derived from non-linear Dubinin-Radushkevich isotherm suggests chemical adsorption. Although arsenic adsorption process was not affected by the presence of sulfate, chloride, and nitrate anions, as expected, bicarbonate and silicate gave moderate negative effects while the presence of phosphate anions significantly inhibited adsorption process of both arsenite and arsenate. When the actual efficiency to remove arsenic was tested against 1 L of artificial arsenic-contaminated groundwater (0.6 mg/L) in the presence competing anions, the reasonable amount (20 g) of hematite coated silica gel could reduce arsenic concentration to below the WHO permissible safety limit of drinking water of 10 μg/L without adjusting pH and temperature, which would be highly advantageous for practical field application.

  9. Synthesis and characterization of tough foldable and transparent poly(styrene-co-butyl acrylate/nanoporous cellulose gel (NCG nanocomposites

    Directory of Open Access Journals (Sweden)

    J. S. Borah

    2017-09-01

    Full Text Available Poly (styrene-co-butyl acrylate/nanoporous cellulose gel nanocomposites [P (St/BA/NCG] were synthesized by in-situ polymerization of styrene/butyl acrylate (St/BA monomer mixtures in nanoporous regenerated cellulose gels. The three-dimensional nanoporous cellulose gels (NCGs were fabricated via dissolution and coagulation of cellulose from aqueous sodium hydroxide (NaOH/urea solution. The NCG contents in nanocomposites were controlled between 16 and 44% v/v by changing water content of starting hydrogels via compression dewatering. Scanning electron microscopy (SEM analysis showed that the interconnected nanofibrillar network structure of NCGs was preserved well in the nanocomposites after insitu polymerization. The resulting nanocomposites exhibited excellent transparency (up to 82% in the visible region and high mechanical strength, with a tensile strength of up to 56.0 MPa, Young’s modulus of up to 2195 MPa and elongation at break up to 80.9%. Dynamic mechanical analysis (DMA showed a remarkable improvement (by over 3 orders of magnitude in tensile storage modulus above glass transition temperature of the copolymer. The nanocomposites also showed significant improvements in thermal stability as well as water resistance over NCG.

  10. Gel-combustion synthesis of CoSb2O6 and its reduction to powdery Sb2Co alloy

    Directory of Open Access Journals (Sweden)

    MAJA JOVIC

    2009-01-01

    Full Text Available Sb2Co alloy in powdery form was synthesized via reduction with gaseous hydrogen of the oxide CoSb2O6, obtained by the citrate gel-combustion technique. The precursor was an aqueous solution of antimony nitrate, cobalt nitrate and citric acid. The precursor solution with mole ratio Co(II/Sb(V of 1:2 was gelatinized by evaporation of water. The gel was heated in air up to the temperature of self-ignition. The product of gel combustion was a mixture of oxides and it had to be additionally thermally treated in order to be converted to pure CoSb2O6. The reduction of CoSb2O6 by gaseous hydrogen yielded powdery Sb2Co as the sole phase. The process of oxide reduction to alloy was controlled by thermogravimetry, while X-ray diffractometry was used to control the phase compositions of both the oxides and alloys.

  11. Synthesis of nanoparticles of magnetite by sol-gel and precipitation methods: study of chemical composition and structure

    International Nuclear Information System (INIS)

    Picasso, Gino; Vega, Jaime; Uzuriaga, Rosario; Ruiz, Gean Pieer

    2012-01-01

    In this work, nanoparticles based on magnetite have been prepared by sol-gel and precipitation methods. In the first case two variants have been applied: by growing of sol starting from nitrate precursor and ethylene glycol as solvent and to control the reduction process and force hydrolysis and steric control prepared from ferrum sulfate precursor and sodium citrate. In the second case the starting material was sulfate precursor, ammonium hydroxide as precipitaing agent and ethylene glycol as surfactant. The samples have been characterized by X-ray diffraction technique (XRD), adsorption-desorption of N 2 (BET equation model) and Moessbauer spectroscopy. XRD patterns of all samples showed typical peaks of magnetite which were detected in the following positions: 30,06 o , 35,42 o , 62,55 o . Average specific surface quantified by BET method was ranging from 40 to 50 m 2 /g with isotherm type IV corresponding to mesoporous surface. Moessbauer spectra of sample prepared from sol-gel (gel growing) carried out at home temperature detected the presence of 2 sextets consisting in 2 type of sites: first one due to octahedral positions (Fe 2+ , Fe 3+ ) and the second one due to tetrahedral positions (Fe 3+ ). Grain size of magnetite samples, evaluated by Scherrer equation and specific surface area, was ranging from 2 to 20 nm. (author).

  12. Synthesis and characterization of Li{sub 4}SiO{sub 4} nano-powders by a water-based sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Wu Xiangwei [Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); Wen Zhaoyin, E-mail: zywen@mail.sic.ac.c [Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); Xu Xiaogang; Wang Xiuyan; Lin Jiu [Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

    2009-08-01

    The water-based sol-gel process for the synthesis of Li{sub 4}SiO{sub 4} nano-powders was reported for the first time. LiOH.H{sub 2}O and aerosil SiO{sub 2} were used as the starting materials with citric acid (C{sub 6}H{sub 8}O{sub 7}.H{sub 2}O) as the chelating agent. Li{sub 4}SiO{sub 4} powders with particle size as small as 100 nm were successfully synthesized at the temperature as low as 675 deg. C. Phase analysis, morphology, sintering behavior of the powders and ionic conductivity of the sintered bodies were investigated systematically. The experimental results showed that the powders obtained by the water-based sol-gel process (SG) possessed excellent sinterability, exhibiting a linear shrinkage of 5.2% while sintered to 900 deg. C, more than 3 times that of the powders obtained by solid state reaction (SSR). The bulk conductivity of the SG sintered bodies was much higher than that of the SSR samples at the same testing temperature.

  13. Sol–gel synthesis of SnO2–MgO nanoparticles and their photocatalytic activity towards methylene blue degradation

    International Nuclear Information System (INIS)

    Bayal, Nisha; Jeevanandam, P.

    2013-01-01

    Graphical abstract: - Highlights: • A simple sol–gel method for the synthesis of SnO 2 –MgO nanoparticles is reported. • Band gap of SnO 2 can be tuned by varying the magnesium content in SnO 2 –MgO. • SnO 2 –MgO shows good photocatalytic activity towards degradation of methylene blue. - Abstract: SnO 2 –MgO mixed metal oxide nanoparticles were prepared by a simple sol–gel method. The nanoparticles were characterized by power X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The XRD results indicate the formation of mixed metal oxide nanoparticles and also a decrease of SnO 2 crystallite size in the mixed metal oxide nanoparticles with increasing magnesium oxide content. The reflectance spectroscopy results show a blue shift of the band gap of SnO 2 in the mixed metal oxide nanoparticles. The photocatalytic activity of the SnO 2 –MgO nanoparticles was tested using the photodegradation of aqueous methylene blue in the presence of sunlight. The results indicate that the mixed metal oxide nanoparticles possess higher efficiency for the photodegradation of methylene blue compared to pure SnO 2 nanoparticles

  14. Sol–gel synthesis of SnO{sub 2}–MgO nanoparticles and their photocatalytic activity towards methylene blue degradation

    Energy Technology Data Exchange (ETDEWEB)

    Bayal, Nisha; Jeevanandam, P., E-mail: jeevafcy@iitr.ernet.in

    2013-10-15

    Graphical abstract: - Highlights: • A simple sol–gel method for the synthesis of SnO{sub 2}–MgO nanoparticles is reported. • Band gap of SnO{sub 2} can be tuned by varying the magnesium content in SnO{sub 2}–MgO. • SnO{sub 2}–MgO shows good photocatalytic activity towards degradation of methylene blue. - Abstract: SnO{sub 2}–MgO mixed metal oxide nanoparticles were prepared by a simple sol–gel method. The nanoparticles were characterized by power X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The XRD results indicate the formation of mixed metal oxide nanoparticles and also a decrease of SnO{sub 2} crystallite size in the mixed metal oxide nanoparticles with increasing magnesium oxide content. The reflectance spectroscopy results show a blue shift of the band gap of SnO{sub 2} in the mixed metal oxide nanoparticles. The photocatalytic activity of the SnO{sub 2}–MgO nanoparticles was tested using the photodegradation of aqueous methylene blue in the presence of sunlight. The results indicate that the mixed metal oxide nanoparticles possess higher efficiency for the photodegradation of methylene blue compared to pure SnO{sub 2} nanoparticles.

  15. Synthesis of NiO–Al{sub 2}O{sub 3} nanocomposites by sol–gel process and their use as catalyst for the oxidation of styrene

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Sudheer Kumar; Jeevanandam, P., E-mail: jeevafcy@iitr.ac.in

    2014-10-15

    Highlights: • NiO–Al{sub 2}O{sub 3} nanocomposites have been synthesized by sol–gel method. • The synthesis takes shorter time (∼48 h) compared to reported methods. • The nanocomposites show high catalytic activity for the oxidation of styrene compared to NiO. - Abstract: NiO–Al{sub 2}O{sub 3} nanocomposites were prepared by sol–gel method. The synthesized nanocomposites were characterized by X-ray diffraction, FT-IR spectroscopy, Raman spectroscopy, field emission scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy, diffuse reflectance spectroscopy and magnetic measurements. XRD results indicate that the NiO–Al{sub 2}O{sub 3} nanocomposites consist of small NiO crystallites (mean size ∼2.6 nm). TEM results indicate uniform distribution of NiO nanoparticles in the Al{sub 2}O{sub 3} matrix. Increase in the band gap of NiO in the nanocomposites compared to pure NiO nanoparticles is observed and the nanocomposites show superparamagnetic behaviour. The NiO–Al{sub 2}O{sub 3} nanocomposites show high catalytic activity for the oxidation of styrene using tert-butyl hydroperoxide as the oxidant and also show higher selectivity for styrene oxide with higher total conversion compared to pure NiO nanoparticles.

  16. Acidocalcisomes as calcium- and polyphosphate-storage compartments during embryogenesis of the insect Rhodnius prolixus Stahl.

    Directory of Open Access Journals (Sweden)

    Isabela Ramos

    Full Text Available BACKGROUND: The yolk of insect eggs is a cellular domain specialized in the storage of reserve components for embryo development. The reserve macromolecules are stored in different organelles and their interactions with the embryo cells are mostly unknown. Acidocalcisomes are lysosome-related organelles characterized by their acidic nature, high electron density and large content of polyphosphate bound to several cations. In this work, we report the presence of acidocalcisome-like organelles in eggs of the insect vector Rhodnius prolixus. METHODOLOGY/PRINCIPAL FINDINGS: Characterization of the elemental composition of electron-dense vesicles by electron probe X-ray microanalysis revealed a composition similar to that previously described for acidocalcisomes. Following subcellular fractionation experiments, fractions enriched in acidocalcisomes were obtained and characterized. Immunofluorescence showed that polyphosphate polymers and the vacuolar proton translocating pyrophosphatase (V-H(+-PPase, considered as a marker for acidocalcisomes are found in the same vesicles and that these organelles are mainly localized in the egg cortex. Polyphosphate quantification showed that acidocalcisomes contain a significant amount of polyphosphate detected at day-0 eggs. Elemental analyses of the egg fractions showed that 24.5±0.65% of the egg calcium are also stored in such organelles. During embryogenesis, incubation of acidocalcisomes with acridine orange showed that these organelles are acidified at day-3 (coinciding with the period of yolk mobilization and polyphosphate quantification showed that the levels of polyphosphate tend to decrease during early embryogenesis, being approximately 30% lower at day-3 compared to day-0 eggs. CONCLUSIONS: We found that acidocalcisomes are present in the eggs and are the main storage compartments of polyphosphate and calcium in the egg yolk. As such components have been shown to be involved in a series of dynamic

  17. Sol-gel synthesis and characterization of hybrid inorganic-organic Tb(III)-terephthalate containing layered double hydroxides

    Science.gov (United States)

    Smalenskaite, A.; Salak, A. N.; Ferreira, M. G. S.; Skaudzius, R.; Kareiva, A.

    2018-06-01

    Mg3/Al1 and Mg3Al1-xTbx layered double hydroxides (LDHs) intercalated with terephthalate anion were synthesized using sol-gel method. The obtained materials were characterized by X-ray diffraction (XRD) analysis, infrared (FTIR) spectroscopy, fluorescence spectroscopy (FLS) and scanning electron microscopy (SEM). The Tb3+ substitution effects in the Mg3Al1-xTbx LDHs were investigated by changing the Tb3+ concentration in the cation layers. The study indicates that the organic guest-terephthalate in the interlayer spacing of the LDH host influences the luminescence of the hybrid inorganic-organic materials.

  18. Sol-gel synthesis of iron catalysers supported on silica and titanium for selectively oxidising methane to formaldehyde

    OpenAIRE

    Carlos Alberto Guerrero Fajardo; Francisco José Sánchez Castellanos; Anne Cécile Roger; Claire Courson

    2010-01-01

    Iron materials supported on silica were prepared by the sol-gel method for evaluating catalytic activity in selective o-xidation of methane to formaldehyde. Four catalysts were prepared, one corresponding to the silica support (catalyst 1S), another to the titanium support (catalyst 1T) and two more having 0.5% weight iron loads, one for the silica su-pport (catalyst 2FS) and the last one the titanium support (catalyst 2FT). The higher BET areas were 659 and 850 m2/g for catalysts 1S and 2FS,...

  19. Synthesis, Structural and Optical Properties of Co Doped TiO2 Nanocrystals by Sol-Gel Method

    OpenAIRE

    Sridevi , D.V ,; Ramesh , V; Sakthivel , T; Geetha , K ,; Ratchagar , V ,; Jagannathan , K ,; Rajarajan , K ,; Ramachadran , K ,

    2017-01-01

    International audience; A TiO2 nanoparticle doped with cobalt was synthesized by sol-gel technique employed at room temperature with appropriate reactants. In the present case, we used titanium tetra isoprotoxide (TTIP) and 2–propanol as a common starting material and the obtained products were calcined at 450˚C450˚450˚C. From the Powder XRD data the particle size was calculated by Scherrer method. The FE-SEM analysis shows the morphology of cobalt doped TiO2 nanoparticles. The various functi...

  20. Synthesis and characterization of uniform silica nanoparticles on nickel substrate by spin coating and sol-gel method

    Science.gov (United States)

    Ngoc Thi Le, Hien; Jeong, Hae Kyung

    2014-01-01

    Spin coating and sol-gel methods are proposed for the preparation of silica nanoparticles on a nickel substrate using silicon tetrachloride, 2-methoxyethanol, and four different types of alkaline solutions. The effects of the type of alkaline solution, concentration of silica solution, and speed of spin coating on the properties of silica nanoparticles are investigated systematically. Uniform spherical shape of silica nanoparticles on Ni with the smallest size are obtained with sodium carbonate among the alkaline solutions after stirring at 70 °C for 6 h and spin-coating at 7000 rpm. Physical and electrochemical properties of the silica particles are investigated.

  1. Silver nitrate based gel dosimeter

    International Nuclear Information System (INIS)

    Titus, D; Samuel, E J J; Srinivasan, K; Roopan, S M; Madhu, C S

    2017-01-01

    A new radiochromic gel dosimeter based on silver nitrate and a normoxic gel dosimeter was investigated using UV-Visible spectrophotometry in the clinical dose range. Gamma radiation induced the synthesis of silver nanoparticles in the gel and is confirmed from the UV-Visible spectrum which shows an absorbance peak at around 450 nm. The dose response function of the dosimeter is found to be linear upto12Gy. In addition, the gel samples were found to be stable which were kept under refrigeration. (paper)

  2. Catechol functionalized aminopropyl silica gel: synthesis, characterization and preconcentrative separation of uranium(VI) from thorium(IV)

    International Nuclear Information System (INIS)

    Metilda, P.; Mary Gladis, J.; Prasada Rao, T.P.

    2005-01-01

    A novel solid phase extractant is prepared by chemically immobilizing catechol with diazotized aminopropyl silica gel. The resulting catechol functionalized silica gel (CASG) was characterized by FTIR, and microanalysis and was used for selective enrichment of uranium(VI) from other inorganic ions. The optimum pH range for maximum sorption of uranium(VI) and thorium(IV) was found to be in the range 3.5-6.0. The above actinides were eluted with 10 cm 3 of 1.0 mol dm -3 HCl and determined by using an Arsenazo III spectrophotometric procedure. The calibration graph was rectilinear over the uranium(VI) concentration in the range 2-100 μg dm -3 with a relative standard deviation of 2.15% (for 25 μg of uranium(VI) present in 1.0 dm 3 of sample). The validation of the developed preconcentration procedure was carried out by analyzing marine sediment (MESS-3, NRC, Canada) and soil (IAEA soil-7, Austria) reference materials. The developed preconcentration method enables a simple instruments like a spectrophotometer gave comparable values of uranium(VI) to that of standard inductively coupled plasma-mass spectrometric values during the analysis of real soil and sediment samples. (orig.)

  3. Catechol functionalized aminopropyl silica gel: synthesis, characterization and preconcentrative separation of uranium(VI) from thorium(IV)

    Energy Technology Data Exchange (ETDEWEB)

    Metilda, P.; Mary Gladis, J.; Prasada Rao, T.P. [Regional Research Lab. (CSIR), Trivandrum (India)

    2005-07-01

    A novel solid phase extractant is prepared by chemically immobilizing catechol with diazotized aminopropyl silica gel. The resulting catechol functionalized silica gel (CASG) was characterized by FTIR, and microanalysis and was used for selective enrichment of uranium(VI) from other inorganic ions. The optimum pH range for maximum sorption of uranium(VI) and thorium(IV) was found to be in the range 3.5-6.0. The above actinides were eluted with 10 cm{sup 3} of 1.0 mol dm{sup -3} HCl and determined by using an Arsenazo III spectrophotometric procedure. The calibration graph was rectilinear over the uranium(VI) concentration in the range 2-100 {mu}g dm{sup -3} with a relative standard deviation of 2.15% (for 25 {mu}g of uranium(VI) present in 1.0 dm{sup 3} of sample). The validation of the developed preconcentration procedure was carried out by analyzing marine sediment (MESS-3, NRC, Canada) and soil (IAEA soil-7, Austria) reference materials. The developed preconcentration method enables a simple instruments like a spectrophotometer gave comparable values of uranium(VI) to that of standard inductively coupled plasma-mass spectrometric values during the analysis of real soil and sediment samples. (orig.)

  4. Sol-gel synthesis of TiO2-SiO2 photocatalyst for β-naphthol photodegradation

    International Nuclear Information System (INIS)

    Qourzal, S.; Barka, N.; Tamimi, M.; Assabbane, A.; Nounah, A.; Ihlal, A.; Ait-Ichou, Y.

    2009-01-01

    Silica gel supported titanium dioxide particles (TiO 2 -SiO 2 ) prepared by sol-gel method was as photocatalyst in the degradation of β-naphthol in water under UV-illumination. The prepared sample has been characterized by powder X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The supported catalyst had large surface area and good sedimentation ability. The photodegradation rate of β-naphthol under UV-irradiation depended strongly on adsorption capacity of the catalyst, and the photoactivity of the supported catalyst was much higher than that of the pure titanium dioxides. The experiments were measured by high performance liquid chromatography (HPLC). The photodegradation rate of β-naphthol using 60% TiO 2 -SiO 2 particles was faster than that using TiO 2 'Degussa P-25', TiO 2 'PC-50' and TiO 2 'Aldrich' as photocatalyst by 2.7, 4 and 7.8 times, respectively. The kinetics of photocatalytic β-naphthol degradation was found to follow a pseudo-first-order rate law. The effect of the TiO 2 loading on the photoactivity of TiO 2 -SiO 2 particles was also discussed. With good photocatalytic activity under UV-irradiation and the ability to be readily separated from the reaction system, this novel kind of catalyst exhibited the potential effective in the treatment of organic pollutants in aqueous systems.

  5. Computational investigation and synthesis of a sol-gel imprinted material for sensing application of some biologically active molecules

    Energy Technology Data Exchange (ETDEWEB)

    Atta, Nada F., E-mail: Nada_fah1@yahoo.com [Department of Chemistry, Faculty of Science, University of Cairo, Post Code 12613, Giza (Egypt); Hamed, Maher M.; Abdel-Mageed, Ali M. [Department of Chemistry, Faculty of Science, University of Cairo, Post Code 12613, Giza (Egypt)

    2010-05-14

    A hybrid sol-gel material was molecularly imprinted with a group of neurotransmitters. Imprinted material is a sol-gel thin film that is spin coated on the surface of a glassy carbon electrode. Imprinted films were characterized electrochemically using cyclic voltammetry (CV) and the encapsulated molecules were extracted from the films and complementary molecular cavities are formed that enable their rebind. The films were tested in their corresponding template solutions for rebinding using square wave voltammetry (SWV). Computational approach for exploring the primary intermolecular forces between templates and hydrolyzed form of the precursor monomer, tetraethylorthosilicate (TEOS), were carried out using Hartree-Fock method (HF). Interaction energy values were computed for each adduct formed between a monomer and a template. Analysis of the optimized conformations of various adducts could explain the mode of interaction between the templates and the monomer units. We found that interaction via the amino group is the common mode among the studied compounds and the results are in good agreement with the electrochemical measurements.

  6. Near white light emitting ZnAl2O4:Dy3+ nanocrystals: Sol–gel synthesis and luminescence studies

    International Nuclear Information System (INIS)

    Kumar, Mithlesh; Gupta, Santosh K.; Kadam, R.M.

    2016-01-01

    Highlights: • ZnAl 2 O 4 :Dy 3+ spinel synthesized using sol–gel method. • Characterized by XRD, SEM and PL spectroscopy. • Investigations of emission, excitation and lifetime properties. • Evaluation of defect centers and trap parameters of the system. • Evaluation of CIE indices of near white light emitting phosphor. - Abstract: ZnAl 2 O 4 :Dy 3+ nanoparticles were synthesized using citrate sol–gel method and characterized systematically using X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy. Emission spectrum of pure ZnAl 2 O 4 shows intense violet blue emission under ultra violet irradiation. Based on electron paramagnetic resonance (EPR) results; it was attributed to presence of singly ionized oxygen vacancy centres in ZnAl 2 O 4 . On doping Dy 3+ in ZnAl 2 O 4 , complete host–dopant energy transfer does not take place. Local structural investigation and lifetime measurements reveal that dysprosium ion is distributed between both Zn 2+ and Al 3+ sites. Near white light from ZnAl 2 O 4 :Dy 3+ is attributed to combined host and dopant luminescence. The trap parameters such as activation energy (E) and frequency factor (s) for TSL glow peak 165 °C were determined using different heating rate method. Thermally stimulated emission showed the presence of oxygen related defect centre.

  7. Synthesis and characterization of TiC nanopowders via sol-gel and subsequent carbothermal reduction process

    Science.gov (United States)

    Chen, Xu; Fan, Jinglian; Lu, Qiong

    2018-06-01

    TiC nanocrystalline powders were synthesized by in-situ carbothermic reduction of Ti-O-C precursor under vacuum atmosphere. And the Ti-O-C precursor was formed by sol-gel method from titanium butyrate (TBOT) and sucrose. To obtain stable sol, TBOT was directly added into mixed solution which contains water, sucrose, acetic acid (AcOH) and acetylacetone (ACAC). This procedure is more convenient and economical because it avoids the use of alcohol which is used as solvent in most reports of alkoxide hydrolysis sol-gel method. TG-DSC, XRD, FTIR and SEM/TEM were employed to analyze and characterize the product during the entire process. The phase composition and crystalline structure parameters of powders with different C/Ti molar ratio were investigated by Rietveld refinement method, and elemental quantitative analysis of the samples were performed. Furthermore, the optimal parameters of carbothermal reduction were obtained and the grain growth mechanism was demonstrated. The results show that TiC nanocrystalline powders (C/Ti molar ratio is 3.5 in the precursor) were synthesized at 1300 °C for 2 h, which have near standard lattice parameter, well crystallinity and fine average grain size ( 37.4 nm).

  8. Synthesis and characterization of nickel substituted cobalt ferrite nanoparticles by sol–gel auto-combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Hankare, P.P., E-mail: p_hankarep@rediffmail.com [Solid State Research Laboratory, Department of Chemistry, Shivaji University, Kolhapur, Maharashtra 416 004 (India); Sanadi, K.R., E-mail: sanadikishor@gmail.com [Solid State Research Laboratory, Department of Chemistry, Shivaji University, Kolhapur, Maharashtra 416 004 (India); Garadkar, K.M. [Solid State Research Laboratory, Department of Chemistry, Shivaji University, Kolhapur, Maharashtra 416 004 (India); Patil, D.R. [Material Research Laboratory, Department of Physics, R.L. College, Parola, Jalgaon, Maharashtra 425 111 (India); Mulla, I.S. [Emeritus Scientist-CSIR, Centre for Materials for Electronics and Technology (C-MET), Panchawati, Pune 411 008 (India)

    2013-03-15

    Highlights: ► Co{sub 1−x}Ni{sub x}Fe{sub 2}O{sub 4} Mixed Metal oxides. ► Sol–gel auto-combustion method. ► Cubic spinel symmetry. ► Nanocrystaline material. ► Semiconducting nature. -- Abstract: Nanocrystalline Co{sub 1−x}Ni{sub x}Fe{sub 2}O{sub 4} (where x = 0.0, 0.25, 0.50, 0.75, 1) were successfully synthesized by sol–gel method using citrate–nitrate precursors. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were effectively utilized to investigate the different structural parameters. XRD showed single cubic spinel phase for all the samples. The decrease in lattice parameter and increase in crystallite size of the ferrispinel was observed with increasing nickel content. The surface morphology and elemental composition were studied by Scanning electron microscope (SEM) and Energy Dispersive X-ray analysis (EDAX) respectively. The nanosize of the synthesized material had been identified by TEM investigation and which is lies in between 20–25 nm. The semiconducting nature of the samples was studied by variation of resistivity and thermal emf with temperature.

  9. Design and synthesis of new fluorescent probe for rapid and highly sensitive detection of proteins via electrophoretic gel stain.

    Science.gov (United States)

    Suzuki, Yoshio; Takagi, Nobuyuki; Chimuro, Tomoyuki; Shinohara, Atsushi; Sakaguchi, Nao; Hiratsuka, Atsunori; Yokoyama, Kenji

    2011-06-01

    A new fluorescent molecular probe, 2,2'-(1E,1'E)-2,2'-(4-(dicyanomethylene)-4H-pyrane-2,6-diyl)bis(ethene-2,1-diyl)bis(sodium benzenesulfonate) salt (1), possessing the cyanopyranyl moieties and two benzene sulfonic acid groups was designed and synthesized to detect proteins in solution and for high-throughput SDS-PAGE. Compound 1 exhibited no fluorescence in the absence of proteins; however, it exhibited strong fluorescence on the addition of bovine serum albumin as a result of intramolecular charge transfer. Compared with the conventional protocols for in-gel protein staining, such as SYPRO Ruby and silver staining, 1 achieves higher sensitivity, even though it offers a simplified, higher throughput protocol. In fact, the total time required for protein staining was 60-90 min under optimum conditions much shorter than that required by the less-sensitive silver staining or SYPRO Ruby staining protocols. Moreover, 1 was successfully applied to protein identification by mass spectrometry via in-gel tryptic digestion, Western blotting, and native PAGE together with protein staining by 1, which is a modified protocol of blue native PAGE (BN-PAGE). Thus, 1 may facilitate high-sensitivity protein detection, and it may be widely applicable as a convenient tool in various scientific and medical fields. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Modulation of Membrane Protein Lateral Mobility by Polyphosphates and Polyamines

    Science.gov (United States)

    Schindler, Melvin; Koppel, Dennis E.; Sheetz, Michael P.

    1980-03-01

    The lateral mobility of fluorescein-labeled membrane glycoproteins was measured in whole unlysed erythrocytes and erythrocyte ghosts by the technique of ``fluorescence redistribution after fusion.'' Measurements were made on polyethylene glycol-fused cell pairs in which only one member of the couplet was initially fluorescently labeled. Diffusion coefficients were estimated from the rate of fluorescence redistribution determined from successive scans with a focused laser beam across individual fused pairs. This technique allows for the analysis of diffusion within cell membranes without the possible damaging photochemical events caused by photobleaching. It was found that lateral mobility of erythrocyte proteins can be increased by the addition of polyphosphates (i.e., ATP and 2,3-diphosphoglycerate) and decreased by the addition of organic polyamines (i.e., neomycin and spermine). This control is exerted by these molecules only when they contact the cytoplasmic side of the membrane and is not dependent upon high-energy phosphates. Microviscosity experiments employing diphenylhexatriene demonstrated no changes in membrane lipid state as a function of these reagents. Our results, in conjunction with data on the physical interactions of cytoskeletal proteins, suggest that the diffusion effector molecules alter the lateral mobility of erythrocyte membrane proteins through modifications of interactions in the shell, which is composed of spectrin, actin, and component 4.1.

  11. Inorganic polyphosphate occurs in the cell wall of Chlamydomonas reinhardtii and accumulates during cytokinesis

    Directory of Open Access Journals (Sweden)

    Freimoser Florian M

    2007-09-01

    Full Text Available Abstract Background Inorganic polyphosphate (poly P, linear chains of phosphate residues linked by energy rich phosphoanhydride bonds, is found in every cell and organelle and is abundant in algae. Depending on its localization and concentration, poly P is involved in various biological functions. It serves, for example, as a phosphate store and buffer against alkali, is involved in energy metabolism and regulates the activity of enzymes. Bacteria defective in poly P synthesis are impaired in biofilm development, motility and pathogenicity. PolyP has also been found in fungal cell walls and bacterial envelopes, but has so far not been measured directly or stained specifically in the cell wall of any plant or alga. Results Here, we demonstrate the presence of poly P in the cell wall of Chlamydomonas reinhardtii by staining with specific poly P binding proteins. The specificity of the poly P signal was verified by various competition experiments, by staining with different poly P binding proteins and by correlation with biochemical quantification. Microscopical investigation at different time-points during growth revealed fluctuations of the poly P signal synchronous with the cell cycle: The poly P staining peaked during late cytokinesis and was independent of the high intracellular poly P content, which fluctuated only slightly during the cell cycle. Conclusion The presented staining method provides a specific and sensitive tool for the study of poly P in the extracellular matrices of algae and could be used to describe the dynamic behaviour of cell wall poly P during the cell cycle. We assume that cell wall poly P and intracellular poly P are regulated by distinct mechanisms and it is suggested that cell wall bound poly P might have important protective functions against toxic compounds or pathogens during cytokinesis, when cells are more vulnerable.

  12. Artificial cartilage bio-matrix formed of hyaluronic acid and Mg2+-polyphosphate

    Directory of Open Access Journals (Sweden)

    X Wang

    2016-11-01

    Full Text Available Here we show that inorganic polyphosphate (polyP, a polyanionic metabolic regulator consisting of multiple phosphate residues linked by energy-rich phosphoanhydride bonds, is present in the synovial fluid. In a biomimetic approach, to enhance cartilage synthesis and regeneration, we prepared amorphous polyP microparticles with Mg2+ as counterions. The particles were characterised by X-ray diffraction (XRD, energy-dispersive X-ray (EDX and Fourier transformed infrared spectroscopic (FTIR analyses. Similar particles were obtained after addition of Mg2+ ions to a solution containing hyaluronic acid, as a major component of the synovial fluid, and soluble Na-polyP. The viscous paste-like material formed, composed of globular microparticles with diameter of 400 nm, strongly promoted the adhesion of chondrocytes and caused a significant upregulation of the expression of the genes encoding collagen type 3A1, as a marker for chondrocyte differentiation, and SOX9, a transcription factor that regulates chondrocyte differentiation and proliferation. The expression level of the collagen type 3A1 gene was also enhanced by exposure of chondrocytes to synovial fluid that was found to contain polyP with a size of about 80 phosphate residues. This stimulatory effect was abolished after pre-incubation of the synovial fluid with the polyP degrading alkaline phosphatase. We propose a strategy for treatment of joint dysfunctions caused by osteoarthritis based on the application of amorphous Mg2+-polyP microparticles thatprevent calcium crystal formation in the synovial fluid using scavenging Ca2+ ions (Mg2+/Ca2+ exchange and enhance chondrocyte function after binding of the Ca2+-polyP to hyaluronic acid at the cartilage surface.

  13. MglA/SspA complex interactions are modulated by inorganic polyphosphate.

    Science.gov (United States)

    Wrench, Algevis P; Gardner, Christopher L; Siegel, Sara D; Pagliai, Fernando A; Malekiha, Mahsa; Gonzalez, Claudio F; Lorca, Graciela L

    2013-01-01

    The transcription factors MglA and SspA of Francisella tularensis form a heterodimer complex and interact with the RNA polymerase to regulate the expression of the Francisella pathogenicity island (FPI) genes. These genes are essential for this pathogen's virulence and survival within host cells. Our goal was to determine if an intracellular metabolite modulate these protein/protein interactions. In this study, we identified inorganic polyphosphate (polyP) as a signal molecule that promotes the interaction of MglA and SspA from F. tularensis SCHU S4. Analysis of the Mgla/SspA interaction was carried out using a two-hybrid system. The Escherichia coli reporter strain contained a deletion on the ppK-ppX operon, inhibiting polyP synthesis. The interaction between MglA and SspA was significantly impaired, as was the interaction between the MglA/SspA complex and the regulatory protein, FevR, indicating the stabilizing effect of polyP. In F. tularensis, chromatin immune precipitation studies revealed that in the absence of polyP, binding of the MglA/SspA complex to the promoter region of the pdpD, iglA, fevR and ppK genes is decreased. Isothermal titration calorimetry (ITC) indicated that polyP binds directly to the MglA/SspA complex with high affinity (KD = 0.3 µM). These observations directly correlated with results obtained from calorimetric scans (DSC), where a strong shift in the mid-transition temperature (Tm) of the MglA/SspA complex was observed in the presence of polyP.

  14. MglA/SspA complex interactions are modulated by inorganic polyphosphate.

    Directory of Open Access Journals (Sweden)

    Algevis P Wrench

    Full Text Available The transcription factors MglA and SspA of Francisella tularensis form a heterodimer complex and interact with the RNA polymerase to regulate the expression of the Francisella pathogenicity island (FPI genes. These genes are essential for this pathogen's virulence and survival within host cells. Our goal was to determine if an intracellular metabolite modulate these protein/protein interactions. In this study, we identified inorganic polyphosphate (polyP as a signal molecule that promotes the interaction of MglA and SspA from F. tularensis SCHU S4. Analysis of the Mgla/SspA interaction was carried out using a two-hybrid system. The Escherichia coli reporter strain contained a deletion on the ppK-ppX operon, inhibiting polyP synthesis. The interaction between MglA and SspA was significantly impaired, as was the interaction between the MglA/SspA complex and the regulatory protein, FevR, indicating the stabilizing effect of polyP. In F. tularensis, chromatin immune precipitation studies revealed that in the absence of polyP, binding of the MglA/SspA complex to the promoter region of the pdpD, iglA, fevR and ppK genes is decreased. Isothermal titration calorimetry (ITC indicated that polyP binds directly to the MglA/SspA complex with high affinity (KD = 0.3 µM. These observations directly correlated with results obtained from calorimetric scans (DSC, where a strong shift in the mid-transition temperature (Tm of the MglA/SspA complex was observed in the presence of polyP.

  15. Synthesis, characterization and bioactivity of a calcium-phosphate glass-ceramics obtained by the sol-gel processing method

    Energy Technology Data Exchange (ETDEWEB)

    Jmal, Nouha, E-mail: jmalnouha@gmail.com; Bouaziz, Jamel

    2017-02-01

    In this work, a calcium-phosphate glass-ceramics was successfully obtained by heat treatment of a mixture of 26.52 in wt.% of fluorapatite (Fap) and 73.48 in wt.% of 77S (77 SiO{sub 2}−14 CaO−9 P{sub 2}O{sub 5} in wt.%) gel. The calcium phosphate-glass-ceramics was prepared by sol-gel process with tetraethyl orthosilicate (TEOS), triethyl phosphate (TEP), calcium nitrate and fluorapatite. The synthesized powders were characterized by some commonly used tools such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), {sup 31}P magic angle spinning nuclear magnetic resonance (MAS-NMR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and thin-film X-ray diffraction (TF-XRD). The obtained results seemed to confirm the nucleation and growth of hydroxyapatite (Hap) nano-phase in the glass. Moreover, an in-vitro evaluation of the glass-ceramic was performed. In addition, to assess its bioactive capacity, it was soaked in simulated body fluid (SBF) at different time intervals. The SEM, EDS and TF-XRD analyses showed the deposition of hydroxyapatite on the surface of the specimens after three days of immersion in SBF solution. The mechanical properties of the obtained material such as rupture strength, Vickers hardness and elastic modulus were measured. In addition, the friction coefficient of calcium phosphate-glass-ceramics was tested. The values of the composite of rupture strength (24 MPa), Vickers hardness (214 Hv), Young's modulus (52.3 GPa), shear modulus (19 GPa) and friction coefficient (0.327) were obtained. This glass-ceramics can have useful applications in dental prostheses. Indeed, this material may have promising applications for implants because of its content of fluorine, the effective protector against dental caries. - Highlights: • A novel three phases Fap-Hap-glass-ceramics is prepared by sol–gel route. • Results showed a nucleation and growth of hydroxyapatite nano-phase in the glass.

  16. Synthesis, characterization and bioactivity of a calcium-phosphate glass-ceramics obtained by the sol-gel processing method

    International Nuclear Information System (INIS)

    Jmal, Nouha; Bouaziz, Jamel

    2017-01-01

    In this work, a calcium-phosphate glass-ceramics was successfully obtained by heat treatment of a mixture of 26.52 in wt.% of fluorapatite (Fap) and 73.48 in wt.% of 77S (77 SiO 2 −14 CaO−9 P 2 O 5 in wt.%) gel. The calcium phosphate-glass-ceramics was prepared by sol-gel process with tetraethyl orthosilicate (TEOS), triethyl phosphate (TEP), calcium nitrate and fluorapatite. The synthesized powders were characterized by some commonly used tools such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), 31 P magic angle spinning nuclear magnetic resonance (MAS-NMR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and thin-film X-ray diffraction (TF-XRD). The obtained results seemed to confirm the nucleation and growth of hydroxyapatite (Hap) nano-phase in the glass. Moreover, an in-vitro evaluation of the glass-ceramic was performed. In addition, to assess its bioactive capacity, it was soaked in simulated body fluid (SBF) at different time intervals. The SEM, EDS and TF-XRD analyses showed the deposition of hydroxyapatite on the surface of the specimens after three days of immersion in SBF solution. The mechanical properties of the obtained material such as rupture strength, Vickers hardness and elastic modulus were measured. In addition, the friction coefficient of calcium phosphate-glass-ceramics was tested. The values of the composite of rupture strength (24 MPa), Vickers hardness (214 Hv), Young's modulus (52.3 GPa), shear modulus (19 GPa) and friction coefficient (0.327) were obtained. This glass-ceramics can have useful applications in dental prostheses. Indeed, this material may have promising applications for implants because of its content of fluorine, the effective protector against dental caries. - Highlights: • A novel three phases Fap-Hap-glass-ceramics is prepared by sol–gel route. • Results showed a nucleation and growth of hydroxyapatite nano-phase in the glass. • Fap

  17. Synthesis and Characterization of Fluoro- and Chlorobimetallic Alkoxides as Precursors for Luminescent Metal Oxide Materials via Sol-Gel Technique

    Institute of Scientific and Technical Information of China (English)

    ATHAR, Taimur; SEOK, Sang II; KWON, Jeong Oh

    2007-01-01

    Heterobimetallic alkoxides are broadly recognized as versatile precursors for luminescence materials, and efforts are being made to develop novel routes by applying the concept of geometrical molecular design, for their synthesis and to design a single source precursor suited to photoluminescent materials. Novel and new series of bimetallic alkoxides has been prepared by metathesis route. They exhibit a lower sensitivity towards hydrolysis and so they are easier to handle as compared to other alkoxides. All the compounds were characterized by elemental analysis, FT-IR and multinuclear NMR spectroscopies. FT-IR revealed that the molecular structure of these metal spectroscopy provided useful information about chemical shifts for better understanding the likely structure based on interactions with their coordinate metals. The mass spectra show similar types of fragmentation pattern.SEM-EDS analyses showed consistency with the formulation. XRD patterns show an enhanced homogeneity at high temperature. TGA measurements show that thermal decomposition occured in steps that depended entirely on the chemical compositions and the synthesis routes. SEM observation reveals that the morphology and particle size strongly depend on synthesis routes for their precursors.

  18. Synthesis of hierarchical porous materials with ZSM-5 structures via template-free sol–gel method

    Directory of Open Access Journals (Sweden)

    Wei Han et al

    2007-01-01

    Full Text Available Interests are focused on preparation of hierarchical porous materials with zeolite structures by using soft or rigid templates in order to solve diffusion and mass transfer limitations resulting from the small pore sizes of zeolites. Here we develop a convenient template-free sol–gel method to synthesize hierarchical porous materials with ZSM-5 structures. This method involves hydrothermal recrystallization of the xerogel converted from uniform ZSM-5 sol by a vacuum drying process. By utilizing this method we can manipulate the size of zeolite nanocrystals as building units of porous structures based on controlling temperature of recrystallization, consequently obtain hierarchical porous materials with different intercrystalline pore sizes and ZSM-5 structures.

  19. Synthesis by Sol-gel and characterization of catalysts Ag/Al2O3-CeO2

    International Nuclear Information System (INIS)

    Zayas, M.L.; Perez H, R.; Rubio, E.; Velasco, A.

    2004-01-01

    Aluminia, cerium and mixed oxides Al 2 O 3 -CeO 2 with different relationship Al/Ce (0.75, 0.50 and 0.25) were prepared by sol-gel and used as support for the Ag. The samples were characterized by XRD, DRIFT, TPR and adsorption of N 2 to temperature of liquid nitrogen. The surface area BET showed that the materials that contain aluminia present near values among them. XRD allowed to identify to the cerianite in the oxides that whose support contains cerium and to the α-aluminia. A mixture of phases was observed in the aluminia. Vibration bands attributed to the bond Al-O and Ce-O were observed by DRIFT in the catalytic materials. TPR showed differences in the reducibility of the Ag precursor in the indicative catalysts of a different interaction with the support. (Author)

  20. Facile synthesis of Ca-doped manganite nanoparticles by a nonaqueous sol-gel method and their magnetic properties

    International Nuclear Information System (INIS)

    Zhou, S.M.; Zhao, S.Y.; He, L.F.; Guo, Y.Q.; Shi, L.

    2010-01-01

    Perovskite manganite La 1-x Ca x MnO 3 (x=1/3, 1/2 and 2/3) nanoparticles with the average particle size of about 20 nm have been synthesized by a facile nonaqueous sol-gel method using methanol as a solvent and characterized by X-ray diffraction, transmission electron microscopy and superconducting quantum interference device magnetometer. Magnetic measurements reveal that although their bulk counterparts have quite different magnetic ground states, the three-nanosized samples exhibit similar ferromagnetic behaviors below about 270 K. This result implies that with the particle size reduced to nanoscale, the ferromagnetism for x=1/3 is weaken, while it is enhanced, accompanied by the suppression of the charge ordering, for x=1/2 and 2/3. Moreover, the exchange bias phenomena are observed in the two latter nanoparticles, which is of special interest for potential applications.

  1. Synthesis, Structural and Optical Properties of Co Doped TiO2 Nanocrystals by Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    D.V. Sridevi

    2017-06-01

    Full Text Available A TiO2 nanoparticle doped with cobalt was synthesized by sol-gel technique employed at room temperature with appropriate reactants. In the present case, we used titanium tetra isoprotoxide (TTIP and 2–propanol as a common starting material and the obtained products were calcined at 450˚ C. From the Powder XRD data the particle size was calculated by Scherrer method. The FE-SEM analysis shows the morphology of cobalt doped TiO2 nanoparticles. The various functional groups of the samples were identified by Fourier transform spectroscopy (FT-IR. The UV-Vis-NIR spectra of cobalt doped TiO2 material shows two absorption peaks in the visible region related to d-d transitions of Co2+ in TiO2 lattice. Compared to un-doped TiO2 nanoparticles, the cobalt doped material show a red shift in the band gap.

  2. Structural, Optical, Morphological and Elemental Analysis on Sol-gel Synthesis of Ni Doped TiO2 Nanocrystallites

    Directory of Open Access Journals (Sweden)

    T. Sakthivel

    2017-06-01

    Full Text Available Pure and Ni doped titanium dioxide nanoparticles were successfully synthesized by sol-gel method and characterized usingXRD, UV-Visible, FTIR, FESEM and EDS techniques. XRD pattern confirms the formation of tetragonal TiO2. The absorbance spectra of pure and Ni doped TiO2 showed absorption spectrum at ultra-violet region due to electronic transition between bonding and anti-bonding orbital (π-π•. Bandgap energy of Ni doped TiO2 decreased to 2.5 eV when compared to pure TiO2 (3.39 eV. FESEM study reveals agglomerated spherical shaped morphology. The functional groups of the prepared samples were identified using FTIR spectroscopy and the elemental analysis was further supported with EDS analysis.

  3. Tailoring of transition metal alkoxides via complexation for the synthesis of hybrid organic-inorganic sols and gels

    International Nuclear Information System (INIS)

    Sanchez, C.; In, M.; Toledano, P.; Griesmar, P.

    1992-01-01

    This paper reports that the chemical control of hydrolysis-condensation reactions of transition metal alkoxides can be performed through the modification of the transition metal coordination sphere by using strong complexing ligands (SCL). Complexing organic groups can be bonded to the transition metal oxide network in two different ways, as network modifiers or network formers. Different illustrations of the role of complexing ligands on Ti(IV) and Zr(IV) alkoxides are presented. As a network modifier, SCL act as termination agents for condensation reactions allowing a control of particle growth. The complexing ligands being located at the periphery of the oxo core open many opportunities for colloid surface protection. SCL carrying organofunctional groups which exhibit non linear optical (NLO) properties have also been used as probes to study sol-gel transformations. SCL functionalized with organic polymerizable functions act as network formers

  4. Sol-gel auto-combustion synthesis and properties of Co2Z-type hexagonal ferrite ultrafine powders

    Science.gov (United States)

    Liu, Junliang; Yang, Min; Wang, Shengyun; Lv, Jingqing; Li, Yuqing; Zhang, Ming

    2018-05-01

    Z-type hexagonal ferrite ultrafine powders with chemical formulations of (BaxSr1-x)3Co2Fe24O41 (x varied from 0.0 to 1.0) have been synthesized by a sol-gel auto-combustion technique. The average particle sizes of the synthesized powders ranged from 2 to 5 μm. The partial substitution of Ba2+ by Sr2+ led to the shrinkage of the crystal lattices and resulted in changes in the magnetic sub-lattices, which tailored the static and dynamic magnetic properties of the as-synthesized powders. As the substitution ratio of Ba2+ by Sr2+, the saturation magnetization of the synthesized powders almost consistently increased from 43.3 to 56.1 emu/g, while the real part of permeability approached to a relatively high value about 2.2 owing to the balance of the saturation magnetization and magnetic anisotropy field.

  5. Sol-Gel Synthesis and Luminescence of Green Light Emitting Phosphors Zn2SiO4/Mn2+

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Mn2+ doped Zn2SiO4 phosphors were synthesized by sol-gel method, and the influence of zinc source, Mn2+ dopant concentration and annealing temperature were investigated. Results show that zinc nitrate based precursor with strong green emission intensities is better than zinc acetate based precursor. The intensity of green light emission reaches a peak at 254 nm when the Mn2+ dopant concentration is about 5%( molar percentage). Structural details of the phosphors were examined through X-ray diffractometry, thermogravimetric and differential thermal analysis. The result indicates that they are both rhombohedral structures, which remain amorphous below 700 ℃and crystallize completely around 1 000℃. The luminescent properties of Zn2SiO4/Mn2+ phosphors were characterized by excitation and emission spectra.

  6. Synthesis and characterization of the Pt/SiO2 nanocomposite by the sol-gel method

    Directory of Open Access Journals (Sweden)

    A. Salabat

    2011-01-01

    Full Text Available The silica supported platinum nanoparticles was synthesized by using the sol-gel method. The possibility of using diamminedinitro platinum (II as Pt precursor and effect of metal precursor concentration on the final Pt nanoparticle size was investigated. A stable silica sol was prepared via hydrolysis of tetraethyl orthosilicate (TEOS as a metal alcoxide and condensation reaction. Subsequently, diamminedinitro platinum (II was added to sol to form the Pt/silica sol. After drying and calcination of the sol, the Pt/SiO2 nanocpmposite has been obtained. Crystallographic information and crystalline size of the synthesized Pt/SiO2 were determined by X-ray diffraction (XRD method. Morphology of the nanoparticles and hydrogen-bonding interaction between silanol groups and amine ligands were characterized by SEM and Fourier transform infrared (FTIR spectra, respectively. Transmission Electron Microscopy (TEM was employed in evaluating the distribution and size of the platinum nanoparticles in the silica.

  7. Sol-gel synthesis of 8 nm magnetite (Fe 3O 4) nanoparticles and their magnetic properties

    KAUST Repository

    Lemine, O. M.

    2012-10-01

    Magnetite (Fe 3O 4) nanoparticles were successfully synthesized by a sol-gel method. The obtained nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive analysis by X-ray (EDAX), transmission electron microscopy (TEM), superconducting quantum interference device (SQUID) and Mössbauer spectrometry. XRD and Mössbauer measurements indicate that the obtained nanoparticles are single phase. TEM analysis shows the presence of spherical nanoparticles with homogeneous size distribution of about 8 nm. Room temperature ferromagnetics behavior was confirmed by SQUID measurements. The mechanism of nanoparticles formation and the comparison with recent results are discussed. Finally, the synthesized nanoparticles present a potential candidate for hyperthermia application given their saturation magnetization. © 2012 Elsevier Ltd. All rights reserved.

  8. Synthesis and characterization of LiFePO4/C cathode materials by sol-gel method.

    Science.gov (United States)

    Liu, Shuxin; Yin, Hengbo; Wang, Haibin; Wang, Hong

    2014-09-01

    The carbon coated LiFePO4 cathode materials (LiFePO4/C) were successfully synthesized by sol-gel method with glucose, citric acid and PEG-4000 as dispersant and carbon source, respectively. The microstructure and grain size of LiFePO4/C composite were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy. The results showed that the carbon source and calcination temperature had important effect on the graphitization degree of carbon; the carbon decomposed by citric acid had higher graphitization degree; with calcination temperature rising, the graphitization degree of carbon increased and the particles size increased. The graphitization degree and grain size were very important for improving the electrochemical performance of LiFePO4 cathode materials, according to the experimental results, the sample LFP-700 (LFP-C) which was synthesized with citric acid as dispersant at 700 degree C had lower polarization and larger discharge capacity.

  9. Sol-gel synthesis of 8 nm magnetite (Fe 3O 4) nanoparticles and their magnetic properties

    KAUST Repository

    Lemine, O. M.; Omri, Karim; Zhang, Bei; El Mir, Lassaad; Sajieddine, Mohammed; Alyamani, Ahmed Y.; Bououdina, M.

    2012-01-01

    Magnetite (Fe 3O 4) nanoparticles were successfully synthesized by a sol-gel method. The obtained nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive analysis by X-ray (EDAX), transmission electron microscopy (TEM), superconducting quantum interference device (SQUID) and Mössbauer spectrometry. XRD and Mössbauer measurements indicate that the obtained nanoparticles are single phase. TEM analysis shows the presence of spherical nanoparticles with homogeneous size distribution of about 8 nm. Room temperature ferromagnetics behavior was confirmed by SQUID measurements. The mechanism of nanoparticles formation and the comparison with recent results are discussed. Finally, the synthesized nanoparticles present a potential candidate for hyperthermia application given their saturation magnetization. © 2012 Elsevier Ltd. All rights reserved.

  10. Synthesis and nonlinear optical properties of zirconia-protected gold nanoparticles embedded in sol-gel derived silica glass

    Science.gov (United States)

    Le Rouge, A.; El Hamzaoui, H.; Capoen, B.; Bernard, R.; Cristini-Robbe, O.; Martinelli, G.; Cassagne, C.; Boudebs, G.; Bouazaoui, M.; Bigot, L.

    2015-05-01

    A new approach to dope a silica glass with gold nanoparticles (GNPs) is presented. It consisted in embedding zirconia-coated GNPs in a silica sol to form a doped silica gel. Then, the sol-doped nanoporous silica xerogel is densified leading to the formation of a glass monolith. The spectral position and shape of the surface plasmon resonance (SPR) reported around 520 nm remain compatible with small spherical GNPs in a silica matrix. The saturable absorption behavior of this gold/zirconia-doped silica glass has been evidenced by Z-scan technique. A second-order nonlinear absorption coefficient β of about -13.7 cm GW-1 has been obtained at a wavelength near the SPR of the GNPs.

  11. Synthesis and photoluminescent properties of yttrium vanadate phosphor prepared by the non-hydrolytic sol–gel process

    International Nuclear Information System (INIS)

    Matos, Marcela G.; Faria, Emerson H. de; Rocha, Lucas A.; Calefi, Paulo S.; Ciuffi, Katia J.; Nassar, Eduardo J.; Sarmento, Victor Hugo Vitorino

    2014-01-01

    We used the non-hydrolytic sol–gel route to synthesize YVO 4 crystalline phases doped with europium III ion. We heat-treated the samples at 600, 800, and 1000 °C and characterized the materials by thermal analysis, X-ray diffraction, small-angle X-ray scattering, and photoluminescence. Larger weight loss occurred until 500 °C, ascribed to removal of residual precursor molecules. X-ray diffraction patterns evidenced YVO 4 phase formation at 600 °C. The crystallite size depended on the heat treatment temperature. SAXS showed that the nature of the system interfaces changed as a function of the thermal treatment. The excitation spectra of the samples displayed the charge transfer band. The photoluminescence data revealed the characteristic transition bands arising from the 5 D 0 → 5 F J (J=0, 1, 2, 3, and 4) manifolds under maximum excitation at the charge transfer band and the 5 L 6 level of the Eu 3+ ion. The 5 D 0 → 7 F 2 transition dominated the emission spectra, indicating that the Eu 3+ ion occupies a site without inversion center. The lifetime and quantum efficiency values were about 0.70 ms and 50%, respectively, corroborating literature results. -- Highlights: • This study described the preparation of the yttrium vanadate by non-hydrolytic sol–gel. • The SAXS curves can be interpreted from the fractal theory for a two-phase model. • The goal of the work is the preparation of the phosphors at low temperature. • The lifetimes depend on wavelength of the excitation

  12. Synthesis and photoluminescent properties of yttrium vanadate phosphor prepared by the non-hydrolytic sol–gel process

    Energy Technology Data Exchange (ETDEWEB)

    Matos, Marcela G.; Faria, Emerson H. de; Rocha, Lucas A.; Calefi, Paulo S.; Ciuffi, Katia J. [Universidade de Franca, Av. Dr. Armando Salles Oliveira, 201 Franca, SP, CEP 14404-600 (Brazil); Nassar, Eduardo J., E-mail: ejnassar@unifran.br [Universidade de Franca, Av. Dr. Armando Salles Oliveira, 201 Franca, SP, CEP 14404-600 (Brazil); Sarmento, Victor Hugo Vitorino [Universidade Federal de Sergipe, Av. Ver. Olimpio Grande s/n Itabaiana, SE, CEP 49500-000 (Brazil)

    2014-03-15

    We used the non-hydrolytic sol–gel route to synthesize YVO{sub 4} crystalline phases doped with europium III ion. We heat-treated the samples at 600, 800, and 1000 °C and characterized the materials by thermal analysis, X-ray diffraction, small-angle X-ray scattering, and photoluminescence. Larger weight loss occurred until 500 °C, ascribed to removal of residual precursor molecules. X-ray diffraction patterns evidenced YVO{sub 4} phase formation at 600 °C. The crystallite size depended on the heat treatment temperature. SAXS showed that the nature of the system interfaces changed as a function of the thermal treatment. The excitation spectra of the samples displayed the charge transfer band. The photoluminescence data revealed the characteristic transition bands arising from the {sup 5}D{sub 0}→{sup 5}F{sub J} (J=0, 1, 2, 3, and 4) manifolds under maximum excitation at the charge transfer band and the {sup 5}L{sub 6} level of the Eu{sup 3+} ion. The {sup 5}D{sub 0}→{sup 7}F{sub 2} transition dominated the emission spectra, indicating that the Eu{sup 3+} ion occupies a site without inversion center. The lifetime and quantum efficiency values were about 0.70 ms and 50%, respectively, corroborating literature results. -- Highlights: • This study described the preparation of the yttrium vanadate by non-hydrolytic sol–gel. • The SAXS curves can be interpreted from the fractal theory for a two-phase model. • The goal of the work is the preparation of the phosphors at low temperature. • The lifetimes depend on wavelength of the excitation.

  13. Sol-gel synthesis and characterization of single-phase Ni ferrite nanoparticles dispersed in SiO2 matrix

    International Nuclear Information System (INIS)

    Nadeem, K.; Traussnig, T.; Letofsky-Papst, I.; Krenn, H.; Brossmann, U.; Wuerschum, R.

    2010-01-01

    Nanoparticles of NiFe 2 O 4 dispersed in SiO 2 (25 wt%) matrix were synthesized by sol-gel method using tetraethyl orthosilicate (TEOS), as a precursor for SiO 2 . The sol-gel method for nanocomposites normally provides multi-phase nanoparticles. We investigated by a synopsis of different analysis methods, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and SQUID-magnetometry, how the various chemical phases are transformed to a single-phase spinel structure during the various stages of annealing from 300 to 900 o C. We have developed a full phase diagram of chemical phases as a function of annealing temperature. The average particle size lies in the range 16-27 nm. The chemical phases formed below 900 o C are NiFe, NiO, γ-Fe 2 O 3 , α-Fe 2 O 3 , and NiFe 2 O 4 , respectively. The role of the TEOS prepared SiO 2 matrix is to restrict the particle size in a small range in order to rule out particle size effects. In the mid-infrared, a shift of the vibrational Fe-O bond is observed from 568 to 586 cm -1 for annealing between 500 and 700 o C which indicates an increasing NiFe 2 O 4 phase formation. A systematic study of coercivity field (ranging from 32 to 200 Oe) and saturation magnetic moment (ranging from 12.2 to 32.1 emu/g) for differently annealed samples supports our findings about the evolution of single-phase NiFe 2 O 4 at 900 o C. The opposite trend of saturation magnetic moment and coercivity with respect to annealing temperature clearly separates the different phases of metallic, antiferromagnetic, and finally single-phase spinel NiFe 2 O 4 .

  14. Caffeine-catalyzed gels.

    Science.gov (United States)

    DiCiccio, Angela M; Lee, Young-Ah Lucy; Glettig, Dean L; Walton, Elizabeth S E; de la Serna, Eva L; Montgomery, Veronica A; Grant, Tyler M; Langer, Robert; Traverso, Giovanni

    2018-07-01

    Covalently cross-linked gels are utilized in a broad range of biomedical applications though their synthesis often compromises easy implementation. Cross-linking reactions commonly utilize catalysts or conditions that can damage biologics and sensitive compounds, producing materials that require extensive post processing to achieve acceptable biocompatibility. As an alternative, we report a batch synthesis platform to produce covalently cross-linked materials appropriate for direct biomedical application enabled by green chemistry and commonly available food grade ingredients. Using caffeine, a mild base, to catalyze anhydrous carboxylate ring-opening of diglycidyl-ether functionalized monomers with citric acid as a tri-functional crosslinking agent we introduce a novel poly(ester-ether) gel synthesis platform. We demonstrate that biocompatible Caffeine Catalyzed Gels (CCGs) exhibit dynamic physical, chemical, and mechanical properties, which can be tailored in shape, surface texture, solvent response, cargo release, shear and tensile strength, among other potential attributes. The demonstrated versatility, low cost and facile synthesis of these CCGs renders them appropriate for a broad range of customized engineering applications including drug delivery constructs, tissue engineering scaffolds, and medical devices. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Synthesis of sub-10 nm VO{sub 2} nanoparticles films with plasma-treated glass slides by aqueous sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Shi-Di [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd, Taipei 106, Taiwan, ROC (China); Cheng, Chih-Chia [Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, Taiwan (China); Huang, Chi-Hsien [Department of Materials Engineering, Ming Chi University of Technology, 84 Gungjuan Road, Taishan Dist., New Taipei City 24301, Taiwan (China); Chen, Jem-Kun, E-mail: jkchen@mail.ntust.edu.tw [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd, Taipei 106, Taiwan, ROC (China)

    2015-12-01

    Highlights: • Sub-10 nm VO{sub 2} nanoparticles (VNPs) are synthesized on a plasma-treated glass. • Glass slides generate negative charges sites after plasma treatment to attract VO{sub 2}{sup +}. • Doping tungsten with 1 wt% in VNPs did not change particle size significantly. • The particle size of VNP can be tuned by the density of negative charge sites. • Sub-10 nm structured VO{sub 2} particle films exhibited high visible transmittance. - Abstract: This paper describes an aqueous sol–gel synthesis of thermochromic thin films consisted of vanadium dioxide nanoparticles (VNPs) on glass slides. The glass slides were treated by argon/oxygen plasma to generate dispersedly negative charge sites on the surface to attract VO{sub 2}{sup +} from a sol–gel solution. After heat treatment in a low-pressure carbon monoxide/carbon dioxide (CO/CO{sub 2}) atmosphere, the VNPs could be generated in sub-10 nm of particle size on the surface. Various levels of doping were achieved by adding small quantities of a water-soluble tungsten compound to the sol; however, the particle size increased slightly with the tungsten doping levels. The change in electrical conductivity with temperature for VNP films were measured and compared to VO{sub 2} crystalline films. VNP films exhibited the lower transition temperature of the semiconductor to metal phase change; at a doping level of 4 wt% the transition temperature was measured at 32.2 ± 1.2 and 24.1 ± 1.2 °C for the VO{sub 2} and VNP films, respectively. The VNP films showed excellent visible transparency and a large change in transmittance at near-infrared (NIR) wavelengths before and after the metal–insulator phase transition (MIT). The current method is a landmark in the development of nanostructured material toward applications in energy-saving smart windows.

  16. Synthesis of sub-10 nm VO2 nanoparticles films with plasma-treated glass slides by aqueous sol–gel method

    International Nuclear Information System (INIS)

    Lan, Shi-Di; Cheng, Chih-Chia; Huang, Chi-Hsien; Chen, Jem-Kun

    2015-01-01

    Highlights: • Sub-10 nm VO 2 nanoparticles (VNPs) are synthesized on a plasma-treated glass. • Glass slides generate negative charges sites after plasma treatment to attract VO 2 + . • Doping tungsten with 1 wt% in VNPs did not change particle size significantly. • The particle size of VNP can be tuned by the density of negative charge sites. • Sub-10 nm structured VO 2 particle films exhibited high visible transmittance. - Abstract: This paper describes an aqueous sol–gel synthesis of thermochromic thin films consisted of vanadium dioxide nanoparticles (VNPs) on glass slides. The glass slides were treated by argon/oxygen plasma to generate dispersedly negative charge sites on the surface to attract VO 2 + from a sol–gel solution. After heat treatment in a low-pressure carbon monoxide/carbon dioxide (CO/CO 2 ) atmosphere, the VNPs could be generated in sub-10 nm of particle size on the surface. Various levels of doping were achieved by adding small quantities of a water-soluble tungsten compound to the sol; however, the particle size increased slightly with the tungsten doping levels. The change in electrical conductivity with temperature for VNP films were measured and compared to VO 2 crystalline films. VNP films exhibited the lower transition temperature of the semiconductor to metal phase change; at a doping level of 4 wt% the transition temperature was measured at 32.2 ± 1.2 and 24.1 ± 1.2 °C for the VO 2 and VNP films, respectively. The VNP films showed excellent visible transparency and a large change in transmittance at near-infrared (NIR) wavelengths before and after the metal–insulator phase transition (MIT). The current method is a landmark in the development of nanostructured material toward applications in energy-saving smart windows.

  17. Treatability Test Plan for 300 Area Uranium Stabilization through Polyphosphate Injection

    Energy Technology Data Exchange (ETDEWEB)

    Vermeul, Vincent R.; Williams, Mark D.; Fritz, Brad G.; Mackley, Rob D.; Mendoza, Donaldo P.; Newcomer, Darrell R.; Rockhold, Mark L.; Williams, Bruce A.; Wellman, Dawn M.

    2007-06-01

    The U.S. Department of Energy has initiated a study into possible options for stabilizing uranium at the 300 Area using polyphosphate injection. As part of this effort, PNNL will perform bench- and field-scale treatability testing designed to evaluate the efficacy of using polyphosphate injections to reduced uranium concentrations in the groundwater to meet drinking water standards (30 ug/L) in situ. This technology works by forming phosphate minerals (autunite and apatite) in the aquifer that directly sequester the existing aqueous uranium in autunite minerals and precipitates apatite minerals for sorption and long term treatment of uranium migrating into the treatment zone, thus reducing current and future aqueous uranium concentrations. Polyphosphate injection was selected for testing based on technology screening as part of the 300-FF-5 Phase III Feasibility Study for treatment of uranium in the 300-Area.

  18. Treatability Test Plan for 300 Area Uranium Stabilization through Polyphosphate Injection

    International Nuclear Information System (INIS)

    Vermeul, Vince R.; Williams, M. D.; Fritz, Brad G.; Mackley, Rob D.; Mendoza, Donaldo P.; Newcomer, Darrell R.; Rockhold, Mark L.; Williams, Bruce A.; Wellman, Dawn M.

    2007-01-01

    The U.S. Department of Energy has initiated a study into possible options for stabilizing uranium at the 300 Area using polyphosphate injection. As part of this effort, PNNL will perform bench- and field-scale treatability testing designed to evaluate the efficacy of using polyphosphate injections to reduced uranium concentrations in the groundwater to meet drinking water standards (30 (micro)g/L) in situ. This technology works by forming phosphate minerals (autunite and apatite) in the aquifer that directly sequester the existing aqueous uranium in autunite minerals and precipitates apatite minerals for sorption and long term treatment of uranium migrating into the treatment zone, thus reducing current and future aqueous uranium concentrations. Polyphosphate injection was selected for testing based on technology screening as part of the 300-FF-5 Phase III Feasibility Study for treatment of uranium in the 300-Area

  19. Non-Aqueous Sol-Gel Synthesis of FePt Nanoparticles in the Absence of In Situ Stabilizers

    Directory of Open Access Journals (Sweden)

    Tobias Preller

    2018-05-01

    Full Text Available The synthesis of FePt nanocrystals is typically performed in an organic solvent at rather high temperatures, demanding the addition of the in situ stabilizers oleic acid and oleylamine to produce monomodal particles with well-defined morphologies. Replacing frequently-used solvents with organic media bearing functional moieties, the use of the stabilizers can be completely circumvented. In addition, various morphologies and sizes of the nanocrystals can be achieved by the choice of organic solvent. The kinetics of particle growth and the change in the magnetic behavior of the superparamagnetic FePt nanocrystals during the synthesis with a set of different solvents, as well as the resulting morphologies and stoichiometries of the nanoparticles were determined by powder X-ray diffraction (PXRD, small-angle X-ray scattering (SAXS, transmission electron microscopy (TEM, inductively coupled plasma optical emission spectroscopy (ICP-OES/mass spectrometry (ICP-MS, and superconducting quantum interference device (SQUID measurements. Furthermore, annealing of the as-prepared FePt nanoparticles led to the ordered L10 phase and, thus, to hard magnetic materials with varying saturation magnetizations and magnetic coercivities.

  20. Synthesis and characterization of Fe-doped TiO2 photocatalyst by the sol–gel method

    International Nuclear Information System (INIS)

    Luu, Cam Loc; Ho, Si Thoang; Nguyen, Quoc Tuan

    2010-01-01

    Thin layers of pure TiO 2 and TiO 2 doped by different amounts of Fe 2 O 3 have been prepared by the sol–gel method with tetraisopropyl orthotitanate and Fe(NO 3 ) 3 . Physico-chemical properties of catalysts were characterized by BET Adsorption, x-ray Diffraction (XRD), FE-SEM, as well as Raman and UV-Vis spectroscopy. The photocatalytic activity of the obtained materials was investigated in the reaction of complete oxidation of p-xylene in gas phase under the radiation of UV (λ=365 nm) and LED (λ=470 nm) lamps. It has been found that the particle size of all samples was distributed in the range 20–30 nm. The content of the rutile phase in Fe-doped TiO 2 samples varied in the range 6.8 to 41.8% depending on the Fe content. Iron oxide doped into TiO 2 enables the photon absorbing zone of TiO 2 to extend from UV towards visible waves as well as to reduce its band gap energy from 3.2 to 2.67 eV. Photocatalytic activities of the TiO 2 samples modified by Fe 3+ have been found to be higher than those of pure TiO 2 by about 2.5 times

  1. Novel kaolin/polysiloxane based organic-inorganic hybrid materials: Sol-gel synthesis, characterization and photocatalytic properties

    Science.gov (United States)

    dos Reis, Glaydson Simões; Lima, Eder Cláudio; Sampaio, Carlos Hoffmann; Rodembusch, Fabiano Severo; Petter, Carlos Otávio; Cazacliu, Bogdan Grigore; Dotto, Guillherme Luiz; Hidalgo, Gelsa Edith Navarro

    2018-04-01

    New hybrid materials using kaolin and the organosilicas methyl-polysiloxane (MK), methyl-phenyl-polysiloxane (H44), tetraethyl-ortho-silicate (TEOS) and 3-amino-propyl-triethoxysilane (APTES) were obtained by sol-gel process. These materials presented specific surfaces areas (SBET) in the range of 20-530 m2 g-1. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed remarkable differences between the kaolin and hybrid structures. Thermogravimetric analysis (TGA) revealed that the hybrid materials presented higher thermal stability when compared with their precursors. The electronic properties of the materials were also studied by Ultraviolet-Visible Diffuse Reflectance Absorption (DRUV) and Diffuse Reflectance spectroscopy (DR), where a new absorption band was observed located around 400-660 nm. In addition, these materials exhibit a decrease in DR from 30% to 70% in the blue-cyan green region and are significantly more transparent in the UV region than the kaolin, which could be useful for photocatalysis applications. These results show that the electronic structure of the final material was changed, indicating a significant interaction between the kaolin and the respective silica derivative. These findings support the main idea of the hybridization afforded by pyrolysis between kaolin and organosilica precursors. In addition, as a proof of concept, these hybrid materials were successfully employed as photocatalyst in the photoreduction of Cr(VI) to Cr(III).

  2. Synthesis of anatase nanopowders by sol-gel method and influence of temperatures of calcination to their photocatalitic properties

    Directory of Open Access Journals (Sweden)

    Golubović A.

    2015-01-01

    Full Text Available The titanium dioxide (TiO2 nanopowders were produced by sol-gel technique from tetrabutyl titanate as a precursor, varying the temperature оf calcination (from 500 to 550°C with the step of 10 °C. XRPD results have shown that all synthesized nanopowders are dominantly in anatase phase. The analysis of the shift and linewidth of the most intensive anatase Eg Raman mode confirmed the XRPD results and added the presence of small amount of highly disordered brookite phase in all samples. The analysis of pore structure from nitrogen sorption experimental data described all samples as mesoporous, with mean pore diameters in the range of 1.5 and 4.5 nm. Nanopowder properties have been related to the photocatalytic activity, tested in degradation of the textile dye (C.I. Reactive Orange 16. The sample calcined at temperature of 510°C showed the best photocatalytic performance. [Projekat Ministarstva nauke Republike Srbije, br. III45018 i br. OI171032

  3. Sol-gel synthesis of anatase nanopowders for efficient photocatalytic degradation of herbicide Clomazone in aqueous media

    Directory of Open Access Journals (Sweden)

    Golubović Aleksandar

    2017-01-01

    Full Text Available TiO2 nanopowders were produced by sol-gel technique using TiCl4 as a starting material. For the preparation of crystalline anatase with developed surface area, this aqueous solution has been mixed with 0.05 M or 0.07 M (NH42SO4 solution in a temperature-controlled bath. The pH values of the suspension were 7, 8 or 9. According to the x-ray diffraction (XRD analysis the anatase crystallite sizes were about 12 nm, which coincided with the average particle size revealed by scanning electron microscopy (SEM. The Raman scattering measurements have shown the presence of a small amount of highly disordered brookite phase in addition to dominant anatase phase with similar nanostructure in all synthesized powders. BET measurements revealed that all synthesized catalysts were fully mesoporous, except the sample synthesized with 0.07 M (NH42SO4 at pH=9, which had small amount of micropores. The photocatalytic degradation of herbicide Clomazone was carried out for both the pure active substance and as the commercial product (GAMIT 4-EC under UV irradiation. The best photocatalytic efficiency was obtained for the catalyst with the largest specific surface area, confirming this parameter as crucial for enhanced photocatalytic degradation of the pure active substance and commercial product of herbicide Clomazone. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III45018

  4. Sol–gel synthesis of highly TiO2 aerogel photocatalyst via high temperature supercritical drying

    Directory of Open Access Journals (Sweden)

    Rebah Moussaoui

    2017-09-01

    Full Text Available Nanocrystalline powders of TiO2 xerogel and aerogel were prepared by using acid-modified sol–gel approach. For TiO2 aerogel material (TA, the solvent was high temperature supercritically extracted at 300 °C and 100 bars. However, the TiO2 xerogel material (TX was dried at 200 °C and ambient pressure. The effects of the drying processes on the crystalline structure, phase transformation and grain growth were determined by Raman spectroscopy, SAED and X-ray diffraction (XRD analyses using Rietveld refinement method. The TiO2 aerogel was composed of anatase crystalline structure. The TiO2 xerogel material was composed of anatase, brookite and small amount of amorphous phase with anatase as dominant phase. The TX sample still contains a relatively high concentration of carbon than that of TA, indicating the amorphous character of TiO2 xerogel. These materials were applied as catalyst for the degradation of indigo carmine in aqueous medium. Photo-degradation ability of TA and TX was compared to the TiO2 commercial Degussa P25. The photo-catalytic results showed that the degradation efficiency was in the order TA > P25 > TX. The photo-degradation of indigo carmine followed pseudo first order reaction kinetics.

  5. Synthesis and photocatalytic properties of porous TiO2 films prepared by ODA/sol-gel method

    International Nuclear Information System (INIS)

    Zhang Wenjie; Bai Jiawei

    2012-01-01

    Porous TiO 2 films were deposited on SiO 2 pre-coated glass-slides by sol-gel method using octadecylamine (ODA) as template. The amount of ODA in the sol played an important role on the physicochemical properties and photocatalytic performance of the TiO 2 films. The films prepared at different conditions were all composed of anatase titanium dioxide crystals, and TiO 2 crystalline size got larger with increasing ODA amount. The maximum specific surface area of 41.5 m 2 /g was obtained for TiO 2 powders prepared from titanium sol containing 2.0 g ODA. Methyl orange degradation rate was enhanced along with increasing ODA amount and reached the maximal value at 2.0 g addition of ODA. After 40 min of UV-light irradiation, methyl orange degradation rate reached 30.5% on the porous film, which was about 10% higher than that on the smooth film. Porous TiO 2 film showed almost constant activity with slight decrease from 30.5% to 28.5% after 4 times of recycles.

  6. Sol-gel synthesis and luminescent properties of red-emitting Y(P,V)O4:Eu(3+) phosphors.

    Science.gov (United States)

    Zhang, Xinguo; Zhou, Fangxiang; He, Pei; Zhang, Min; Gong, Menglian

    2016-02-01

    Eu(3+)-activated Y(P,V)O4 phosphors were prepared by the EDTA sol-gel method, and the corresponding morphologies and luminescent properties were investigated. The sample particles were relatively spheroid with size of 2-3 µm and had a smooth surface. The excitation spectra for Y(P,V)O4:Eu(3+) consisted of three strong excitation bands in the 200-350 nm range, which were attributed to a Eu(3+)- O(2-) charge-transfer band and (1)A1-(1) T1/(1) T2 transitions in VO4(3-). The as-synthesized phosphors exhibited a highly efficient red luminescence at 613 nm due to the Eu(3+5) D0-(7) F2 electric dipole transition. With the increase in the V(5+)/P(5+) ratio, the luminescence intensity of the red phosphor under UV excitation was greatly improved due to enhanced VO4(3-) → Eu(3+) energy transfer. Copyright © 2015 John Wiley & Sons, Ltd.

  7. Occlusion of chromophore oxides by Sol-Gel methods: Application to the synthesis of hematite-silica red pigments

    Directory of Open Access Journals (Sweden)

    Vicent, J. B.

    2000-02-01

    Full Text Available Heteromorphic pigments present the chromophore particle occluded in an encapsulating matrix which is thermally stable and insoluble in glazes. The occluded chromophore compound is also insoluble in the host matrix. In this work the mechanisms of formation of this type of pigments are analyzed and the occlusion of hematite into silica matrix is discussed. The formation of this hematite-silica red pigment follows a sintering-coarsening mechanism, and, consequently, the control of both hematite particles nucleation and their crystal growth results to be decisive to obtain a good coloring effectiveness.

    En los pigmentos heteromórficos la partícula de cromóforo es ocluida en una matriz encapsuladora estable tanto termicamente como frente a los vidriados. El compuesto cromóforo ocluido y la matriz no coloreada son insolubles. En este trabajo se analiza los diferentes mecanismos de formación de estos pigmentos heteromórficos y se estudia la oclusión de hematita en sílice mediante métodos sol-gel acuoso. El pigmento sigue un mecanismo de sinterización-crecimiento cristalino por lo que es muy importante controlar el momento de nucleación y la velocidad de crecimiento de las partículas de hematita en el seno de la matriz.

  8. Highly transparent ITO thin films on photosensitive glass: sol-gel synthesis, structure, morphology and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Koroesi, Laszlo; Papp, Szilvia; Dekany, Imre [University of Szeged, Supramolecular and Nanostructured Materials Research Group of the Hungarian Academy of Sciences, Szeged (Hungary); Beke, Szabolcs [Italian Institute of Technology, Department of Nanophysics, Genova (Italy); Pecz, Bela; Horvath, Robert; Petrik, Peter; Agocs, Emil [Research Institute for Technical Physics and Materials Science, Budapest (Hungary)

    2012-05-15

    Conductive and highly transparent indium tin oxide (ITO) thin films were prepared on photosensitive glass substrates by the combination of sol-gel and spin-coating techniques. First, the substrates were coated with amorphous Sn-doped indium hydroxide, and these amorphous films were then calcined at 550 {sup circle} C to produce crystalline and electrically conductive ITO layers. The resulting thin films were characterized by means of scanning electron microscopy, UV-Vis spectroscopy, X-ray photoelectron spectroscopy and spectroscopic ellipsometry. The measurements revealed that the ITO films were composed of spherical crystallites around 20 nm in size with mainly cubic crystal structure. The ITO films acted as antireflection coatings increasing the transparency of the coated substrates compared to that of the bare supports. The developed ITO films with a thickness of {proportional_to}170-330 nm were highly transparent in the visible spectrum with sheet resistances of 4.0-13.7 k{omega}/sq. By coating photosensitive glass with ITO films, our results open up new perspectives in micro- and nano-technology, for example in fabricating conductive and highly transparent 3D microreactors. (orig.)

  9. Synthesis and Application of Iron Oxide/Silica Gel Nanocomposite for Removal of Sulfur Dyes from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Naser Tavassoli

    2017-03-01

    Full Text Available Background & Aims of the Study: water pollution by synthetic organic dyes is mainly regarded as environmental and ecological critical issues worldwide. In this research, magnetite iron oxide/silica gel nanocomposite (termed as Fe3O4/SG was synthesized chemically and then used as an effective adsorbent for removal of sulfur dyes from aqueous solution. Materials and Methods: The various parameters such as pH, sorbent dosage, initial dye concentration, contact time and dye solution temperature were investigated in a batch system. The equilibrium data were analyzed by Langmuir and Freundlich isotherm models. Results: The experimental data fit well with pseudo-second-order kinetic model (R2≥0.998 and conformed better to Langmuir isotherm model (R2≥0.997. The maximum adsorption capacity for Fe3O4/SG obtained from the Langmuir model was 11.1mg/g. Evaluation of thermodynamic parameters proved that the adsorption process was normally feasible, spontaneous and exothermic. Conclusion: It can be concluded that the Fe3O4/SG can be considered as a cost-effective and an environmental friendly adsorbent for efficient removal of sulfur dyes from aqueous solutions.

  10. New inorganic (an)ion exchangers based on Mg–Al hydrous oxides: (Alkoxide-free) sol–gel synthesis and characterisation

    KAUST Repository

    Chubar, Natalia

    2011-01-01

    New inorganic ion exchangers based on double Mg-Al hydrous oxides were generated via the new non-traditional sol-gel synthesis method which avoids using metal alkoxides as raw materials. Surface chemical and adsorptive properties of the final products were controlled by several ways of hydrogels and xerogels treatments which produced the materials of the layered structure, mixed hydrous oxides or amorphous adsorbents. The final adsorptive materials obtained via thermal treatment of xerogels were the layered mesoporous materials with carbonate in the interlayer space, surface abundance with hydroxylic groups and maximum adsorptive capacity to arsenate. Higher affinity of Mg-Al hydrous oxides towards H2AsO4- is confirmed by steep adsorption isotherms having plateau (removal capacity) at 220. mg[As]. gdw-1 for the best sample at pH = 7, fast adsorption kinetics and little pH effect. Adsorption of arsenite, fluoride, bromate, bromide, selenate, borate by Mg-Al hydrous oxides was few times high either competitive (depending on the anion) as compare with the conventional inorganic ion exchange adsorbents. © 2011 Elsevier Inc.

  11. Effect of Various Solvent on the Synthesis of NiO Nanopowders by Simple Sol-Gel Methods and Its Characterization

    Directory of Open Access Journals (Sweden)

    Sherly Kasuma Warda Ningsih

    2015-03-01

    Full Text Available Synthesis of nickel oxide (NiO with various solvents by simple sol-gel process has been done. NiO nanopowders were obtained by using nickel nitrate hexahydrate and sodium hydroxide 5 M were used as precursor and agent precipitator, respectively. The addition of various solvents that used in this research were aquadest, methanol and isopropanol. The powders were formed by drying in the temperature of 100-110 °C for 1 h and after heating at ±450 °C for 1 h. The products were obtained black powders. The products were characterized by Energy Dispersive X-Ray Fluorescence (ED-XRF, X-Ray Diffraction (XRD and Scanning Electron Microscopy (SEM. The ED-XRF pattern show that composition of NiO produced was 96.9%. The XRD patterns showed NiO forms were in monoclinic structure with aquadest solvent and cubic structure with methanol and isopropanol used. Crystal sizes of NiO particles produced with aquadest, methanol, isopropanol were obtained in the range 37.05; 72.16; 66.04 nm respectively. SEM micrograph clearly showed that powder had a spherical shape with uniform distribution size is 0.1-1.0 µm approximately.

  12. New inorganic (an)ion exchangers based on Mg–Al hydrous oxides: (Alkoxide-free) sol–gel synthesis and characterisation

    KAUST Repository

    Chubar, Natalia

    2011-05-01

    New inorganic ion exchangers based on double Mg-Al hydrous oxides were generated via the new non-traditional sol-gel synthesis method which avoids using metal alkoxides as raw materials. Surface chemical and adsorptive properties of the final products were controlled by several ways of hydrogels and xerogels treatments which produced the materials of the layered structure, mixed hydrous oxides or amorphous adsorbents. The final adsorptive materials obtained via thermal treatment of xerogels were the layered mesoporous materials with carbonate in the interlayer space, surface abundance with hydroxylic groups and maximum adsorptive capacity to arsenate. Higher affinity of Mg-Al hydrous oxides towards H2AsO4- is confirmed by steep adsorption isotherms having plateau (removal capacity) at 220. mg[As]. gdw-1 for the best sample at pH = 7, fast adsorption kinetics and little pH effect. Adsorption of arsenite, fluoride, bromate, bromide, selenate, borate by Mg-Al hydrous oxides was few times high either competitive (depending on the anion) as compare with the conventional inorganic ion exchange adsorbents. © 2011 Elsevier Inc.

  13. Sol-gel synthesis, structure and photoluminescence properties of nanocrystalline Lu{sub 2}MoO{sub 6}:Eu

    Energy Technology Data Exchange (ETDEWEB)

    Li, Huaiyong; Yang, Hyun Kyoung [Department of Physics, Pukyong National University, 599-1 Nam-Gu, Daeyeon 3 Dong, Busan 608-737 (Korea, Republic of); Jeong, Jung Hyun, E-mail: jhjeong@pknu.ac.kr [Department of Physics, Pukyong National University, 599-1 Nam-Gu, Daeyeon 3 Dong, Busan 608-737 (Korea, Republic of); Jang, Kiwan; Lee, Ho Sueb [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Yi, Soung Soo [Department of Electronic Material Engineering, Silla University, Busan 617-736 (Korea, Republic of)

    2011-09-15

    Highlights: {yields} Monoclinic-structural Lu{sub 2}MoO{sub 6} has strong absorption of near-UV light. {yields} The absorbed energy can be transferred from MoO{sub 5} groups to doped Eu{sup 3+} and luminescence. {yields} The absorption edge and the peak of the MoO{sub 5} excitation band shift in reverse ways. {yields} The decline of the crystallinity and the introduced defect respond for the variation. -- Abstract: In this paper, we reported the obtention of Eu{sup 3+} ion doped Lu{sub 2}MoO{sub 6} powders synthesized by a sol-gel method, and followed by annealing at different temperatures. The structure and photoluminescence properties of these powders were investigated. The X-ray diffraction pattern suggests that Lu{sub 2}MoO{sub 6} powder has a monoclinic structure. It was observed that the UV-visible and photoluminescence spectra of Lu{sub 2}MoO{sub 6}:Eu nanocrystallines varied systematically with the calcination temperature. The near-UV absorption edge shifts to long wavelength direction with the decreasing of the calcination temperature, while the peak of MoO{sub 5} excitation band shifts in an opposite way. The decline of the crystallinity and the introduced lattice defect were considered to respond for these variations. Additionally, due to the efficient red light emission under near-UV light excitation, the powder can be a candidate as red phosphor for white-light-emitting diodes.

  14. Synthesis and characterization of nanosized Mg{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 4} ferrites by both sol-gel and thermal decomposition methods

    Energy Technology Data Exchange (ETDEWEB)

    De-León-Prado, Laura Elena, E-mail: laura.elena.prado@gmail.com [Cinvestav-Unidad Saltillo, Av. Industria Metalúrgica #1062, Parque Industrial Saltillo-Ramos Arizpe, CP 25900, Ramos Arizpe, Coahuila, México (Mexico); Cortés-Hernández, Dora Alicia; Almanza-Robles, José Manuel; Escobedo-Bocardo, José Concepción; Sánchez, Javier; Reyes-Rdz, Pamela Yajaira; Jasso-Terán, Rosario Argentina [Cinvestav-Unidad Saltillo, Av. Industria Metalúrgica #1062, Parque Industrial Saltillo-Ramos Arizpe, CP 25900, Ramos Arizpe, Coahuila, México (Mexico); Hurtado-López, Gilberto Francisco [Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna Hermosillo #140, CP 25294, Saltillo, Coahuila, México (Mexico)

    2017-04-01

    This work reports the synthesis of Mg{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 4} (x=0–1) nanoparticles by both sol-gel and thermal decomposition methods. In order to determine the effect of synthesis conditions on the crystal structure and magnetic properties of the ferrites, the synthesis was carried out varying some parameters, including composition. By both methods it was possible to obtain ferrites having a single crystalline phase with cubic inverse spinel structure and a behavior near to that of superparamagnetic materials. Saturation magnetization values were higher for materials synthesized by sol-gel. Furthermore, in both cases particles have a spherical-like morphology and nanometric sizes (11–15 nm). Therefore, these materials can be used as thermoseeds for the treatment of cancer by magnetic hyperthermia. - Highlights: • Mg–Mn ferrites were synthesized by sol-gel and thermal decomposition methods. • Materials showed a single cubic inverse spinel crystalline structure. • Ferrites have a soft ferrimagnetic behavior close to superparamagnetic materials.

  15. Sol-gel synthesis of bioactive glass porous scaffolds with addition of porogen agent; Sintese sol-gel de scaffolds porosos de vidro bioativo com adicao de agente porogenico

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, F.B.A.P.; Barrioni, B.R.; Oliveira, A.C.X.; Oliveira, A.A.R.; Pereira, M.M., E-mail: fabianabapg@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Escola de Engenharia. Dept. Engenharia Metalurgica e de Materiais

    2016-10-15

    The use of biomaterials capable of generating a biological response has been one of the biggest progresses in regenerative medicine, due to their ability to support growth stimulation and damaged tissue regeneration. In this context, bioceramics, particularly bioactive glass (BG), were the subject of many studies. The technique of porogen agent addition for the synthesis of scaffolds is an interesting procedure, because several types of porogen agents can be used. The aim of the present work was to obtain scaffolds using four porogen agents and to evaluate the effects that a change in treatment temperature can have on their crystallinity. Scaffolds of sol-gel bioactive glass 100S (100% SiO{sub 2}) using as porogen agents paraffin 1, paraffin 2, wax and CMC (carboxymethyl cellulose) were synthesized and characterized. As the best results were obtained with paraffin 1, scaffolds 58S (60%SiO{sub 2} -36%CaO-4%P{sub 2}O{sub 5} ) and 100S using paraffin 1 as porogen agent were prepared. The scaffolds were submitted to different treatment temperatures to evaluate the effect on their crystallinity. Pore structure was analyzed by scanning electron microscopy and micro-computed tomography. Scaffolds presented satisfactory pore size and pore size distribution, important characteristics for scaffolds because they allow cell migration, nutrient transport, vascularisation and tissue ingrowth. X-ray powder diffraction showed the amorphous nature of the scaffolds. At 900 °C, scaffolds BG 58S and 100S showed a small increase in crystallinity. BET analysis (N{sub 2} -adsorption) indicated a mesoporous structure. The specific surface area varied from 73.2 m{sup 2} /g for scaffold 58S treated at 800 °C to 331.2 m{sup 2} /g for scaffold 100S treated at 800 °C. The materials obtained showed no toxic effects by MTT cytotoxicity assays. Results showed that the development of scaffolds is possible using porogen agents, with 3D interconnected porous structure and might therefore be a

  16. Sol-gel synthesis of iron catalysers supported on silica and titanium for selectively oxidising methane to formaldehyde

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Guerrero Fajardo

    2008-01-01

    Full Text Available Iron materials supported on silica were prepared by the sol-gel method for evaluating catalytic activity in selective o-xidation of methane to formaldehyde. Four catalysts were prepared, one corresponding to the silica support (catalyst 1S, another to the titanium support (catalyst 1T and two more having 0.5% weight iron loads, one for the silica su-pport (catalyst 2FS and the last one the titanium support (catalyst 2FT. The higher BET areas were 659 and 850 m2/g for catalysts 1S and 2FS, respectively while catalysts 1T and 2FT displayed areas of 65 and 54 m2/g, respec-tively. Scanning and transmission electronic microscopy displayed an amorphous structure in the silica-supported materials while titanium-supported materials displayed dense materials having defined structure. X-ray diffraction confirmed the silica’s amorphous structure in 1S and 2FS catalysts and displayed the 1T and 2FT catalysts’ anatase structure. The programmed temperature reduction for the 1S and 2FS catalysts did not display reducible species, while displaying hydrogen consumption peaks related to Fe3O4 reduction to α-Fe via FexO route for 1T and 2FT ca-talysts. The electronic spectroscopy X-ray photo confirmed the Fe(III specie as having 710.6 e.V binding energy for both 2FS and 2FT catalysts. Catalytic activity was carried out at atmospheric pressure in a quartz reactor, reaction mixture as CH4/O2/N2 =7.5/1/4 at 400-800°C temperature range. The reaction products were analysed by gas chromatography on Hayesep R and T columns using 5Å molecular screening. The best response for selective oxida-tion of methane to formaldehyde was displayed by the 2FS catalyst with 3.4% mol methane conversion at 650°C, 11.9% mol formaldehyde selectivity and 0.0211 g HCHO/Kg catalyst yield.

  17. Apatite mineralization in elasmobranch skeletons via a polyphosphate intermediate

    Science.gov (United States)

    Omelon, Sidney; Lacroix, Nicolas; Lildhar, Levannia; Variola, Fabio; Dean, Mason

    2014-05-01

    All vertebrate skeletons are stiffened with apatite, a calcium phosphate mineral. Control of apatite mineralization is essential to the growth and repair of the biology of these skeletons, ensuring that apatite is deposited in the correct tissue location at the desired time. The mechanism of this biochemical control remains debated, but must involve increasing the localized apatite saturation state. It was theorized in 1923 that alkaline phosphatase (ALP) activity provides this control mechanism by increasing the inorganic phosphate (Pi) concentration via dephosphorylation of phosphorylated molecules. The ALP substrate for biological apatite is not known. We propose that polyphosphates (polyPs) produced by mitochondria may be the substrate for biological apatite formation by ALP activity. PolyPs (PO3-)n, also known as condensed phosphates, represent a concentrated, bioavailable Pi-storage strategy. Mitochondria import Pi and synthesize phosphate polymers through an unknown biochemical mechanism. When chelated with calcium and/or other cations, the effective P-concentration of these neutrally charged, amorphous, polyP species can be very high (~ 0.5 M), without inducing phosphate mineral crystallization. This P-concentration in the low Pi-concentration biological environment offers a method of concentrating P well above an apatite supersaturation required for nucleation. Bone is the most studied mineralized skeletal tissue. However, locating and analyzing active mineralizing areas is challenging. We studied calcified cartilage skeletons of elasmobranch fishes (sharks, stingrays and relatives) to analyse the phosphate chemistry in this continually mineralizing skeleton. Although the majority of the elasmobranch skeleton is unmineralized cartilage, it is wrapped in an outer layer of mineralized tissue comprised of small tiles called tesserae. These calcified tesserae continually grow through the formation of new mineral on their borders. Co-localization of ALP and

  18. The new method for check of polyphosphate content in H333PO4 production

    International Nuclear Information System (INIS)

    Popov, Y.S.; Anichenkov, S.V.; Makarov, I.B.

    1993-01-01

    In the future, the quality of the final products of chemical technology and analysis will be checked with the express non-destructive methods with computer data processing. An automated facility is developed to check polyphosphate content in production of orthophosphoric acid labelled with phosphorus 33. The construction and operation methods are described

  19. Influence of sludge retention time on tolerance of copper toxicity for polyphosphate accumulating organisms linked to polyhydroxyalkanoates metabolism and phosphate removal.

    Science.gov (United States)

    Tsai, Yung-Pin; Chen, Hsiu-Ting

    2011-12-01

    This study explored the influence of sludge retention time (SRT) on tolerance of copper invasion for polyphosphate accumulating organisms (PAOs) in an enhanced biological phosphorus removal (EBPR). The experimental data showed the anaerobic polyhydroxyalkanoates (PHA) storage for the sludge at 10d SRT was less influenced by copper invasion than those at 5d and 15d SRTs. The reaction of PAOs aerobically taking up phosphate for the sludge at 5d or 15d SRT almost ceased at 2 mg Cu L(-1), whereas PAOs in the sludge at 10d SRT retained half of the ability to take up phosphate. Both the PHAs degradation and synthesis rates decreased with increasing copper concentration, regardless of the SRTs. However, the copper inhibition of the former was greater than that of the later. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Multiple antibiotic susceptibility of polyphosphate kinase mutants (ppk1 and ppk2 from Pseudomonas aeruginosa PAO1 as revealed by global phenotypic analysis

    Directory of Open Access Journals (Sweden)

    Javiera Ortiz-Severín

    2015-01-01

    Full Text Available BACKGROUND: Pseudomonas aeruginosa is known to be a multidrug resistant opportunistic pathogen. Particularly, P. aeruginosa PAO1 polyphosphate kinase mutant (ppk1 is deficient in motility, quorum sensing, biofilm formation and virulence FINDINGS: By using Phenotypic Microarrays (PM we analyzed near 2000 phenotypes of P. aeruginosa PAO1 polyP kinase mutants (ppk1 and ppk2. We found that both ppk mutants shared most of the phenotypic changes and interestingly many of them related to susceptibility toward numerous and different type of antibiotics such as Ciprofloxacin, Chloramphenicol and Rifampicin CONCLUSIONS: Combining the fact that ppk1 mutants have reduced virulence and are more susceptible to antibiotics, polyP synthesis and particularly PPK1, is a good target for the design of molecules with anti-virulence and anti-persistence properties.

  1. In Vitro and In Vivo Evaluation of Sol-Gel Derived TiO2 Coatings Based on a Variety of Precursors and Synthesis Conditions

    Directory of Open Access Journals (Sweden)

    Krzysztof Marycz

    2014-01-01

    Full Text Available The effect of synthesis way of TiO2 coatings on biocompatibility of transplanted materials using an in vitro and in vivo rat model was investigated. TiO2 layers were synthesized by a nonaqueous sol-gel dip-coating method on stainless steel 316L substrates applying two different precursors and their combination. Morphology and topography of newly formed biomaterials were determined as well as chemical composition and elemental distribution of a surface samples. In vitro tests were conducted by adipose-derived mesenchymal stem cells cultured on TiO2 coatings and stainless steel without coatings to assess the bioreactivity of obtained materials. A positive biological effect of TiO2/316L/1 coatings—based on titanium(IV ethoxide—was found in both in vitro and in vivo models. The TiO2/316L/1 exhibited the highest roughness and the lowest titanium concentration in TiO2 than TiO2/316L/2—based on titanium(IV propoxide and TiO2/316L/3—based on both above-mentioned precursors. The proper fibroblast-like morphology and higher proliferation rate of cells cultured on TiO2/316L/1 were observed when compared to the other biomaterials. No inflammatory response in the bone surrounding implant covered by each of the obtained TiO2 was present. Our results showed that improvement of routinely used stainless steel 316L with TiO2/316L/1 layer can stimulate beneficial biological response.

  2. Synthesis and physical properties of TEOS-based silica aerogels prepared by two step (acid-base) sol-gel process

    International Nuclear Information System (INIS)

    Venkateswara Rao, A.; Bhagat, S.D.

    2004-01-01

    The experimental results on the synthesis and physical properties of tetra-ethoxy-silane- (TEOS) based silica aerogels produced by two step (acid-base) sol-gel process, are reported. The oxalic acid (A) and NH 4 OH (B) concentrations were varied from 0 to 0.1 M and from 0.4 to 3 M, respectively. Monolithic and transparent aerogels have been obtained for the values of A=0.001 M and B=1 M. The effect of time interval (t) before the base catalyst (NH 4 OH) addition to the acidic sol was studied from 0 to 72 h. The time interval at t=24 h of NH 4 OH addition was found to be the best, in terms of low volume shrinkage, high optical transmission and monolithicity. The molar ratio of EtOH/TEOS (S) was varied from 3 to 7.5. Monolithic and transparent aerogels were obtained for an S value of 6.9. Also, the effects of molar ratio of acidic water, i.e., H 2 O/TEOS (W1) and basic water, i.e., H 2 O/TEOS (W2) on the physical properties of the aerogels have been studied. Highly transparent (about 90%) and monolithic aerogels with lower volume shrinkage ( 2 O):basic (H 2 O). The results are discussed by taking into consideration the hydrolysis and poly-condensation reactions. The aerogels were characterized by scanning electron microscopy (SEM), optical transmission, bulk density, volume shrinkage and porosity measurements. (authors)

  3. Utilization of Snail (Achatina fulica Shell Waste for Synthesis of Calcium Tartrate Tetrahydrate (CaC4H4O6.4H2O Single Crystals in Silica Gel

    Directory of Open Access Journals (Sweden)

    Imam Sakdi

    2012-01-01

    Full Text Available Snail (Achatina fulica shell waste is massively produced by many home industries in Indonesia, especially in East Java. The snail shell is known for high calcium; therefore it is potential to be used as calcium source of supernatant in the synthesis of piezoeletric material, such as single crystal of calcium tartrate tetrahydrate (CaTT. The aim of this research is to study the synthesis and characterization of CaTT or CaC4H4O6.4H2O from snail shell waste in silica gel. Supernatant solution of CaCl2 was prepared from CaO, which previously made by calcinating the shell at 1000°C, and then reacted with HCl 1,5M. Synthesis of CaTT was conducted in a single-tube reaction at room temperature in which silica gel was used as growth medium with gelling time of 10 days and growth time of 2 weeks. The pH of gel and CaCl2 concentration were varied, 3.00; 3.50; 4.00; 4.50; 5.00; and 0.27; 0.36; 0.45; 0.54 M respectively, in order to obtain optimum condition of the synthesis, which is indicated from crystal yields. The synthesized crystals were characterized by atomic adsorption spectrophotometry (AAS, infrared spectroscopy (IR and powder X-ray diffraction (XRD. Experimental data shows that optimum condition was obtained at pH of 3.50 and [CaCl2] of 0.45M with yield of 69.37%. The obtained single crystal has clear color and octahedral-like shape with size ranged between 4 – 9 mm. Analysis data by FTIR and powder XRD confirmed that the obtained crystal was CaTT single crystals with crystal system of orthorhombic.

  4. Low temperature synthesis of CaO-SiO2 glasses having stable liquid-liquid immiscibility by sol-gel process

    Science.gov (United States)

    Bansal, Narottam P.

    1990-01-01

    Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, were synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol percent calcium nitrate resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water:TEOS mole ratio, calcium content, and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(sub gel), was evaluated from temperature dependence of the gel time. Presence of Ca(2+) ions or the water:TEOS mole ratio did not have an appreciable effect on the value of E(sub gel). Presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using DTA, TGA, IR-spectroscopy, x ray diffraction, surface area and pore size distribution measurements.

  5. Low temperature synthesis of CaO-SiO2 glasses having stable liquid-liquid immiscibility by the sol-gel process

    Science.gov (United States)

    Bansal, N. P.

    1992-01-01

    Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, were synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol percent calcium nitrate resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water: TEOS mole ratio, calcium content, and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(sub gel), was evaluated from temperature dependence of the gel time. Presence of Ca(2+) ions or the water:TEOS mole ratio did not have an appreciable effect on the value of E(sub gel). Presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using DTA, TGA, IR-spectroscopy, X-ray diffraction, surface area and pore size distribution measurements.

  6. Synthesis, structural, spectroscopic and thermoanalytical study of sol–gel derived SiO{sub 2}–CaO–P{sub 2}O{sub 5} gel and ceramic materials

    Energy Technology Data Exchange (ETDEWEB)

    Catauro, Michelina, E-mail: michelina.catauro@unina2.it [Department of Industrial and Information Engineering, Second University of Naples, via Roma 29, Aversa (CE) (Italy); Dell’Era, Alessandro [Department D.M.E., ‘Guglielmo Marconi’ University, via Plinio 44, Roma (Italy); Vecchio Ciprioti, Stefano, E-mail: stefano.vecchio@uniroma1.it [Department S.B.A.I., Sapienza University of Rome, via del Castro Laurenziano 7, Roma (Italy)

    2016-02-10

    Highlights: • Four different SiO{sub 2}–CaO–P{sub 2}O{sub 5} gel-glasses were synthesized by the sol–gel method. • FTIR, XRD, SEM-EDS and TG/DTA techniques were used to fully characterize the gels. • Integral isoconversional OFW method was used to study dehydration kinetics. • Appropriate temperatures of 600 and 1200 °C were chosen to thermally treat them. • All amorphous gels at 1200 °C crystallize as wollastonite and pseudowollastonite. - Abstract: In the present work bioactive powders of the ternary SiO{sub 2}·CaO·P{sub 2}O{sub 5} systems, which differ in the Ca/P molar ratio, were synthesized by means of a sol–gel route, using tetraethyl orthosilicate (TEOS, Si(OC{sub 2}H{sub 5}){sub 4}), calcium nitrate tetrahydrate (Ca(NO{sub 3}){sub 2}·4H{sub 2}O) and triethyl phosphate (TEP, OP(OC{sub 2}H{sub 5}){sub 3}) as precursors of SiO{sub 2}, CaO and P{sub 2}O{sub 5}, respectively. In order to investigate the influence of the relative amount of each phase (in this study: SiO{sub 2}, CaO and P{sub 2}O{sub 5}) the thermal properties of the synthesized gel-glass materials were studied as a function of the Ca/P molar ratio using thermogravimetric and differential thermal analysis (TG/DTA). After dehydration (in a single step), described from a kinetic point of view as a simple water evaporation without rupture of chemical bonds, all gels undergo a complex multi-step decomposition with endo and exothermic effects, followed by crystallization of calcium silicate phases at about 950 °C. Furthermore, Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning Electron Microscopy, coupled with energy dispersive spectroscopy (SEM/EDS), allowed us to detect the chemical modifications induced by modifying the Ca/P molar ratio and the sintering. This process is obtained by thermal treatment of the gel-glass precursors after analyzing their thermal behavior in the temperature range 600–1000 °C, with the aim to convert them into

  7. A Soluble Pyrophosphatase Is Essential to Oogenesis and Is Required for Polyphosphate Metabolism in the Red Flour Beetle (Tribolium castaneum

    Directory of Open Access Journals (Sweden)

    Klébea Carvalho

    2015-03-01

    Full Text Available Polyphosphates have been found in all cell types examined to date and play diverse roles depending on the cell type. In eukaryotic organisms, polyphosphates have been mainly investigated in mammalian cells with few studies on insects. Some studies have demonstrated that a pyrophosphatase regulates polyphosphate metabolism, and most of them were performed on trypanosomatids. Here, we investigated the effects of sPPase gene knocked down in oogenesis and polyphosphate metabolism in the red flour beetle (Tribolium castaneum. A single sPPase gene was identified in insect genome and is maternally provided at the mRNA level and not restricted to any embryonic or extraembryonic region during embryogenesis. After injection of Tc-sPPase dsRNA, female survival was reduced to 15% of the control (dsNeo RNA, and egg laying was completely impaired. The morphological analysis by nuclear DAPI staining of the ovarioles in Tc-sPPase dsRNA-injected females showed that the ovariole number is diminished, degenerated oocytes can be observed, and germarium is reduced. The polyphosphate level was increased in cytoplasmic and nuclear fractions in Tc-sPPase RNAi; Concomitantly, the exopolyphosphatase activity decreased in both fractions. Altogether, these data suggest a role for sPPase in the regulation on polyphosphate metabolism in insects and provide evidence that Tc-sPPase is essential to oogenesis.

  8. Functional coatings: the sol-gel approach

    International Nuclear Information System (INIS)

    Belleville, Ph.

    2010-01-01

    CEA's sol-gel laboratory is specialized in the development of innovative sol-gel optical coatings and has extended its application field to membrane materials and coatings for energy conversion, to electric coatings for microelectronics devices and to thin films for gas sensing. This article describes, by way of examples, the laboratory's research on sol-gel functional coatings, including nano-material synthesis, organic-inorganic hybrid-based solution preparation as well as deposition process development and prototyping. (author)

  9. Up-regulation of phosphoinositide metabolism in tobacco cells constitutively expressing the human type I inositol polyphosphate 5-phosphatase

    Science.gov (United States)

    Perera, Imara Y.; Love, John; Heilmann, Ingo; Thompson, William F.; Boss, Wendy F.; Brown, C. S. (Principal Investigator)

    2002-01-01

    To evaluate the impact of suppressing inositol 1,4,5-trisphosphate (InsP(3)) in plants, tobacco (Nicotiana tabacum) cells were transformed with the human type I inositol polyphosphate 5-phosphatase (InsP 5-ptase), an enzyme which specifically hydrolyzes InsP(3). The transgenic cell lines showed a 12- to 25-fold increase in InsP 5-ptase activity in vitro and a 60% to 80% reduction in basal InsP(3) compared with wild-type cells. Stimulation with Mas-7, a synthetic analog of the wasp venom peptide mastoparan, resulted in an approximately 2-fold increase in InsP(3) in both wild-type and transgenic cells. However, even with stimulation, InsP(3) levels in the transgenic cells did not reach wild-type basal values, suggesting that InsP(3) signaling is compromised. Analysis of whole-cell lipids indicated that phosphatidylinositol 4,5-bisphosphate (PtdInsP(2)), the lipid precursor of InsP(3), was greatly reduced in the transgenic cells. In vitro assays of enzymes involved in PtdInsP(2) metabolism showed that the activity of the PtdInsP(2)-hydrolyzing enzyme phospholipase C was not significantly altered in the transgenic cells. In contrast, the activity of the plasma membrane PtdInsP 5 kinase was increased by approximately 3-fold in the transgenic cells. In vivo labeling studies revealed a greater incorporation of (32)P into PtdInsP(2) in the transgenic cells compared with the wild type, indicating that the rate of PtdInsP(2) synthesis was increased. These studies show that the constitutive expression of the human type I InsP 5-ptase in tobacco cells leads to an up-regulation of the phosphoinositide pathway and highlight the importance of PtdInsP(2) synthesis as a regulatory step in this system.

  10. Electrochemical assessing corrosion inhibiting effects of zinc aluminum polyphosphate (ZAPP) as a modified zinc phosphate pigment

    International Nuclear Information System (INIS)

    Naderi, R.; Attar, M.M.

    2008-01-01

    Undesirable anti-corrosion performance of zinc phosphate pigment, the classical chromate replacement, has led researchers to take modification into account. Polyphosphate-based anti-corrosion pigments as a result of modification of zinc orthophosphate have been found to function much more efficiently. This study aimed to evaluate performance of steel samples immersed in 3.5% NaCl aqueous solution-containing zinc aluminum polyphosphate (ZAPP) pigment extract compared to those involving conventional zinc phosphate (ZP) pigment extract and also no pigment (blank) using electrochemical tests such as electrochemical impedance spectroscopy (EIS) and linear polarization (LP) as well as surface analysis. Impedance spectra and polarization curves revealed two different trends, showing the superiority of ZAPP pigment. Based on the results of scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), presence of a precipitated layer on the surface was confirmed when steel sample was immersed into the solution-containing ZAPP

  11. Characterisation of Phosphate Accumulating Organisms and Techniques for Polyphosphate Detection: A Review

    Directory of Open Access Journals (Sweden)

    Cédric Tarayre

    2016-05-01

    Full Text Available Phosphate minerals have long been used for the production of phosphorus-based chemicals used in many economic sectors. However, these resources are not renewable and the natural phosphate stocks are decreasing. In this context, the research of new phosphate sources has become necessary. Many types of wastes contain non-negligible phosphate concentrations, such as wastewater. In wastewater treatment plants, phosphorus is eliminated by physicochemical and/or biological techniques. In this latter case, a specific microbiota, phosphate accumulating organisms (PAOs, accumulates phosphate as polyphosphate. This molecule can be considered as an alternative phosphate source, and is directly extracted from wastewater generated by human activities. This review focuses on the techniques which can be applied to enrich and try to isolate these PAOs, and to detect the presence of polyphosphate in microbial cells.

  12. Electrospun bioactive mats enriched with Ca-polyphosphate/retinol nanospheres as potential wound dressing

    OpenAIRE

    Müller, Werner E.G.; Tolba, Emad; Dorweiler, Bernhard; Schröder, Heinz C.; Diehl-Seifert, Bärbel; Wang, Xiaohong

    2015-01-01

    Background While electrospun materials have been frequently used in tissue engineering no wound dressings exist that significantly improved wound healing effectively. Methods We succeeded to fabricate three-dimensional (3D) electrospun poly(D,l-lactide) (PLA) fiber mats into which nanospheres, formed from amorphous calcium polyphosphate (polyP) nanoparticles (NP) and encapsulated retinol (“retinol/aCa-polyP-NS” nanospheres [NS]), had been incorporated. Results Experiments with MC3T3-E1 cells ...

  13. Reaction of lithium, sodium and potassium polyphosphates with potassium permanganate at elevated temperatures

    International Nuclear Information System (INIS)

    Paderova, L.V.; Onuchina, T.V.; Kochergin, V.P.

    1996-01-01

    A study was made on destruction of molten polyphosphates of alkaline metals by potassium permanganate during change of KMnO 4 content, test time and temperature. Ortho-, di, tri- and tetraphosphate-anions, as well as manganese compounds with different oxidation degree were revealed in products of component interaction. Empirical equations of the dependence of the value of average molecular mass on change of melt temperature were derived. 11 refs.; 2 figs.; 2 tabs

  14. Polifosfatos em detergentes em pó comerciais Polyphosphates in commercial powder detergents

    Directory of Open Access Journals (Sweden)

    Viktoria Klara Lakatos Osorio

    2001-10-01

    Full Text Available A didactic experiment is proposed in order to identify inorganic phosphates in home laundry detergents by ascending paper chromatography. Chemical principles related with hard water are also investigated. The role of polyphosphates in detergent formulations is discussed and the softening of hard water by sodium tripolyphosphate is illustrated. Several chemical concepts, related to the daily experience of the students, can be explored in post-lab discussions.

  15. Fabrication of targets for transmutation of americium : synthesis of inertial matrix by sol-gel method. Procedure study on the infiltration of a radioactive solutions

    International Nuclear Information System (INIS)

    Fernandez Carretero, A.

    2002-01-01

    Transmutation and incineration are innovative options in the management and disposal of fission products and actinides. nevertheless, the fabrication of targets for transmutation and incineration of actinides and fission products require a reconsideration of conventional processes (mechanical blending) and the development of new procedures compatible with the high activity of these materials. This work presents th R and D of a new fabrication method called INRAM (Infiltration of Radioactive Materials) based on the infiltration of an actinide solution in a porous non radiotoxic material in the form of a pellet (up to 12% An), or beads (up to 40% An) produced by sol-gel. The first method have been used for the fabrication of spinel (MgAl 2 O 4 ) targets containing 11% Am, which have been irradiated in HFR-Petten (358.4 full power days). Post-test burn-up calculations showed that at the end of the irradiation the initial Am-241 concentration was reduced to 4%. The fraction of the initial americum atoms that have been fissioned is 28%. The main advantage of the INRAM method is that matrices with low or zero activity can be fabricated and formed into the required shape in an unshielded facility. This method offers other advantages over conventional ones, such as the active wastes are reduced, is easy to automate, adoptable to telemanipulation and dust free, which facilitate operator intervention and minimise radiation exposure to the personal. In addition, the infiltrant needs only be present in liquid form, i. e. it could be transferred directly from the reprocessing plant for fabrication into targets without conversion into-solid form. In order to optimise the infiltration process in depth investigations of all important process parameters, e. g. infiltration kinetics and metal (pu, Am) concentration in the feed solution, and also on extensive study or powder metallurgy parameters for the preparation of high quality fuel pellets with a high density, have been made. In

  16. Cadmium Tolerance and Removal from Cunninghamella elegans Related to the Polyphosphate Metabolism

    Directory of Open Access Journals (Sweden)

    Hercília M. L. Rolim

    2013-03-01

    Full Text Available The aim of the present work was to study the cadmium effects on growth, ultrastructure and polyphosphate metabolism, as well as to evaluate the metal removal and accumulation by Cunninghamella elegans (IFM 46109 growing in culture medium. The presence of cadmium reduced growth, and a longer lag phase was observed. However, the phosphate uptake from the culture medium increased 15% when compared to the control. Moreover, C. elegans removed 70%–81% of the cadmium added to the culture medium during its growth. The C. elegans mycelia showed a removal efficiency of 280 mg/g at a cadmium concentration of 22.10 mg/L, and the removal velocity of cadmium was 0.107 mg/h. Additionally, it was observed that cadmium induced vacuolization, the presence of electron dense deposits in vacuoles, cytoplasm and cell membranes, as well as the distinct behavior of polyphosphate fractions. The results obtained with C. elegans suggest that precipitation, vacuolization and polyphosphate fractions were associated to cadmium tolerance, and this species demonstrated a higher potential for bioremediation of heavy metals.

  17. Hydrothermal synthesis and sol-gel methods for CdS particle production in different morphologies and their use in wastewater applications

    OpenAIRE

    Tuncer, Cansel

    2018-01-01

    In this study, CdSnanoparticles were synthesized in different sizes and morphologies using twodifferent methods. First, the synthesis of both cauliflower-type CdS microspheresand CdS nanoflower-type microstructures by hydrothermal synthesis was carriedout in a steel reactors with teflon chamber. While polyethylene glycol andthioacetamide were used in the synthesis of cauliflower-type CdS microspheres,thiourea was used as a sulfur source in the synthesis of nanoflower CdS microstructures.Spher...

  18. Al2O3 - TiO2-A simple sol-gel strategy to the synthesis of low temperature sintered alumina-aluminium titanate composites through a core-shell approach

    International Nuclear Information System (INIS)

    Jayasankar, M.; Ananthakumar, S.; Mukundan, P.; Wunderlich, W.; Warrier, K.G.K.

    2008-01-01

    A simple sol-gel based core-shell approach for the synthesis of alumina-aluminium titanate composite is reported. Alumina is the core and titania is the shell. The coating of titania has been performed in aqueous medium on alumina particle by means of heterocoagulation of titanyl chloride. Further heat treatment results in low temperature formation of aluminium titanate as well as low temperature sintering of alumina-aluminium titanate composites. The lowering of the reaction temperature can be attributed to the maximisation of the contact surface between the reactants due to the core-shell approach involving nanoparticles. The mechanism of formation of aluminium titanate and the observations on densification features in the present process are compared with that of mixture of oxides under identical conditions. The sintered alumina-aluminium titanate composite has an average grain size of 2 μm. - Graphical abstract: The article presents a simple sol-gel process through core-shell approach to the synthesis of low temperature sintered alumina-aluminium titanate. The lowering of the reaction temperature can be attributed to the maximisation of the contact surface between the reactant due to the core-shell approach. This material showed the better microstructure control compared to the standard solid-state mixing route

  19. Synthesis and characterization of sodium vanadium oxide gels: the effects of water (n) and sodium (x) content on the electrochemistry of Na(x)V2O5·nH2O.

    Science.gov (United States)

    Lee, Chia-Ying; Marschilok, Amy C; Subramanian, Aditya; Takeuchi, Kenneth J; Takeuchi, Esther S

    2011-10-28

    Sodium vanadium oxide gels, Na(x)V(2)O(5)·nH(2)O, of varying sodium content (0.12 n > 0.01) and interlayer spacing were found to be inversely proportional to the sodium level (x), thus control of sodium (x) content provided a direct, chimie douce approach for control of hydration level (n) and interlayer spacing, without the need for high temperature treatment to affect dehydration. Notably, the use of high temperatures to modify hydration levels can result in crystallization and collapse of the interlayer structure, highlighting the distinct advantage of our novel chimie douce synthesis strategy. Subsequent to synthesis and characterization, results from an electrochemical study of a series of Na(x)V(2)O(5)·nH(2)O samples highlight the significant impact of interlayer water on delivered capacity of the layered materials. Specifically, the sodium vanadium oxide gels with higher sodium content and lower water content provided higher capacities in lithium based cells, where capacity delivered to 2.0 V under C/20 discharge ranged from 170 mAh/g for Na(0.12)V(2)O(5)·0.23H(2)O to 300 mAh/g for Na(0.32)V(2)O(5)·0.01H(2)O. The capacity differences were maintained as the cells were cycled. This journal is © the Owner Societies 2011

  20. Sol-gel chemistry applied to the synthesis of polymetallic oxides including actinides reactivity and structure from solution to solid state; Synthese par voie douce d'oxydes polymetalliques incluant des actinides: reactivite et structure de la solution au solide

    Energy Technology Data Exchange (ETDEWEB)

    Lemonnier, St

    2006-02-15

    Minor actinides transmutation is studied at present in order to reduce the radiotoxicity of nuclear waste and the assessment of its technical feasibility requires specific designed materials. When considering americium, yttria stabilized zirconia (Am{sup III} YII Zriv)Or{sub x} is among the ceramic phases that one which presents the required physico-chemical properties. An innovative synthesis of this mixed oxide by sol-gel process is reported in this manuscript. The main aim of this work is to adjust the reactivity of the different metallic cations in aqueous media using complexing agent, in order to initiate a favourable interaction for a homogeneous elements repartition in the forming solid phase. The originality of the settled synthesis lies on an in-situ formation of a stable and monodisperse nano-particles dispersion in the presence of acetylacetone. The main reaction mechanisms have been identified: the sol stabilisation results from an original interaction between the three compounds (Zrly, trivalent cations and acetylacetone). The sol corresponds to a structured system at the nanometer scale for which zirconium and trivalent cations are homogeneously dispersed, preliminary to the sol-gel transition. Furthermore, preliminary studies were carried out with a view to developing materials. They have demonstrated that numerous innovative and potential applications can be developed by taking advantage of the direct and controlled formation of the sol and by adapting the sol-gel transition. The most illustrating result is the preparation of a sintered pellet with the composition Am0,13Zro,73Yo,0901,89 using this approach. (author)

  1. Purification and properties of recombinant exopolyphosphatase PPN1 and effects of its overexpression on polyphosphate in Saccharomyces cerevisiae.

    Science.gov (United States)

    Andreeva, Nadeshda; Trilisenko, Ludmila; Kulakovskaya, Tatiana; Dumina, Maria; Eldarov, Michail

    2015-01-01

    Inorganic polyphosphate performs many regulatory functions in living cells. The yeast exopolyphosphatase PPN1 is an enzyme with multiple cellular localization and probably variable functions. The Saccharomyces cerevisiae strain with overexpressed PPN1 was constructed for large-scale production of the enzyme and for studying the effect of overproduction on polyphosphate metabolism. The ΔPPN1 strain was transformed by the vector containing this gene under a strong constitutive promoter of glycerol aldehyde-triphosphate dehydrogenase of S. cerevisiae. Exopolyphosphatase activity in the transformant increased 28- and 11-fold compared to the ΔPPN1 and parent strains, respectively. The content of acid-soluble polyphosphate decreased ∼6-fold and the content of acid-insoluble polyphosphate decreased ∼2.5-fold in the cells of the transformant compared to the ΔPPN1 strain. The recombinant enzyme was purified. The substrate specificity, cation requirement, and inhibition by heparin were found to be similar to native PPN1. The molecular mass of a subunit (∼33 kD) and the amino acid sequence of the recombinant enzyme were the same as in mature PPN1. The recombinant enzyme was localized mainly in the cytoplasm (40%) and vacuoles (20%). The overproducer strain had no growths defects under phosphate deficiency or phosphate excess. In contrast to the parent strains accumulating polyphosphate, the transformant accumulated orthophosphate under phosphate surplus. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  2. 300 Area Treatability Test: Laboratory Development of Polyphosphate Remediation Technology for In Situ Treatment of Uranium Contamination in the Vadose Zone and Capillary Fringe

    Energy Technology Data Exchange (ETDEWEB)

    Wellman, Dawn M.; Pierce, Eric M.; Bacon, Diana H.; Oostrom, Martinus; Gunderson, Katie M.; Webb, Samuel M.; Bovaird, Chase C.; Cordova, Elsa A.; Clayton, Eric T.; Parker, Kent E.; Ermi, Ruby M.; Baum, Steven R.; Vermeul, Vincent R.; Fruchter, Jonathan S.

    2008-09-30

    This report presents results from bench-scale treatability studies conducted under site-specific conditions to optimize the polyphosphate amendment for implementation of a field-scale technology demonstration to stabilize uranium within the 300 Area vadose and smear zones of the Hanford Site. The general treatability testing approach consisted of conducting studies with site sediment and under site conditions, to develop an effective chemical formulation and infiltration approach for the polyphosphate amendment under site conditions. Laboratory-scale dynamic column tests were used to 1) quantify the retardation of polyphosphate and its degradation products as a function of water content, 2) determine the rate of polyphosphate degradation under unsaturated conditions, 3) develop an understanding of the mechanism of autunite formation via the reaction of solid phase calcite-bound uranium and aqueous polyphosphate remediation technology, 4) develop an understanding of the transformation mechanism, the identity of secondary phases, and the kinetics of the reaction between uranyl-carbonate and -silicate minerals with the polyphosphate remedy under solubility-limiting conditions, and 5) quantify the extent and rate of uranium released and immobilized based on the infiltration rate of the polyphosphate remedy and the effect of and periodic wet-dry cycling on the efficacy of polyphosphate remediation for uranium in the vadose zone and smear zone.

  3. Cell wall canals formed upon growth of Candida maltosa in the presence of hexadecane are associated with polyphosphates.

    Science.gov (United States)

    Zvonarev, Anton N; Crowley, David E; Ryazanova, Lubov P; Lichko, Lydia P; Rusakova, Tatiana G; Kulakovskaya, Tatiana V; Dmitriev, Vladimir V

    2017-05-01

    Canals are supramolecular complexes observed in the cell wall of Candida maltosa grown in the presence of hexadecane as a sole carbon source. Such structures were not observed in glucose-grown cells. Microscopic observations of cells stained with diaminobenzidine revealed the presence of oxidative enzymes in the canals. 4΄,6΄-diamino-2-phenylindole staining revealed that a substantial part of cellular polyphosphate was present in the cell wall of cells grown on hexadecane in condition of phosphate limitation. The content and chain length of polyphosphates were higher in hexadecane-grown cells than in glucose grown ones. The treatment of cells with yeast polyphosphatase PPX1 resulted in the decrease of the canal size. These data clearly indicated that polyphosphates are constituents of canals; they might play an important role in the canal structure and functioning. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Biological Apatite Formed from Polyphosphate and Alkaline Phosphatase May Exchange Oxygen Isotopes from Water through Carbonate

    Science.gov (United States)

    Omelon, S. J.; Stanley, S. Y.; Gorelikov, I.; Matsuura, N.

    2011-12-01

    The oxygen isotopic composition in bone mineral phosphate is known to reflect the local water composition, environmental humidity, and diet1. Once ingested, biochemical processes presumably equilibrate PO43- with "body water" by the many biochemical reactions involving PO43- 2. Blake et al. demonstrated that enzymatic release of PO43- from organophosphorus compounds, and microbial metabolism of dissolved orthophosphate, significantly exchange the oxygen in precipitated apatite within environmental water3,4, which otherwise does not exchange with water at low temperatures. One of the enzymes that can cleave phosphates from organic substrates is alkaline phosphastase5, the enzyme also associated with bone mineralization. The literature often states that the mineral in bone in hydroxylapatite, however the mineral in bone is carbonated apatite that also contains some fluoride6. Deprotonation of HPO32- occurs at pH 12, which is impossibly high for biological system, and the predominate carbonate species in solution at neutral pH is HCO3-. To produce an apatite mineral without a significant hydroxyl content, it is possible that apatite biomineralization occurs through a polyphosphate pathway, where the oxygen atom required to transform polyphosphate into individual phosphate ions is from carbonate: [PO3-]n + CO32- -> [PO3-]n-1 + PO43- + CO2. Alkaline phosphatase can depolymerise polyphosphate into orthophosphate5. If alkaline phosphatase cleaves an oxygen atom from a calcium-carbonate complex, then there is no requirement for removing a hydrogen atom from the HCO3- or HPO43- ions of body water to form bioapatite. A mix of 1 mL of 1 M calcium polyphosphate hydogel, or nano-particles of calcium polyphosphate, and amorphous calcium carbonate were reacted with alkaline phosphatase, and maintained at neutral to basic pH. After two weeks, carbonated apatite and other calcium phosphate minerals were identified by powder x-ray diffraction. Orthophosphate and unreacted

  5. Characterization of mercury bioremediation by transgenic bacteria expressing metallothionein and polyphosphate kinase

    Directory of Open Access Journals (Sweden)

    Gonzalez-Ruiz Gloriene

    2011-08-01

    Full Text Available Abstract Background The use of transgenic bacteria has been proposed as a suitable alternative for mercury remediation. Ideally, mercury would be sequestered by metal-scavenging agents inside transgenic bacteria for subsequent retrieval. So far, this approach has produced limited protection and accumulation. We report here the development of a transgenic system that effectively expresses metallothionein (mt-1 and polyphosphate kinase (ppk genes in bacteria in order to provide high mercury resistance and accumulation. Results In this study, bacterial transformation with transcriptional and translational enhanced vectors designed for the expression of metallothionein and polyphosphate kinase provided high transgene transcript levels independent of the gene being expressed. Expression of polyphosphate kinase and metallothionein in transgenic bacteria provided high resistance to mercury, up to 80 μM and 120 μM, respectively. Here we show for the first time that metallothionein can be efficiently expressed in bacteria without being fused to a carrier protein to enhance mercury bioremediation. Cold vapor atomic absorption spectrometry analyzes revealed that the mt-1 transgenic bacteria accumulated up to 100.2 ± 17.6 μM of mercury from media containing 120 μM Hg. The extent of mercury remediation was such that the contaminated media remediated by the mt-1 transgenic bacteria supported the growth of untransformed bacteria. Cell aggregation, precipitation and color changes were visually observed in mt-1 and ppk transgenic bacteria when these cells were grown in high mercury concentrations. Conclusion The transgenic bacterial system described in this study presents a viable technology for mercury bioremediation from liquid matrices because it provides high mercury resistance and accumulation while inhibiting elemental mercury volatilization. This is the first report that shows that metallothionein expression provides mercury resistance and

  6. Low Concentration Fe-Doped Alumina Catalysts Using Sol-Gel and Impregnation Methods: The Synthesis, Characterization and Catalytic Performance during the Combustion of Trichloroethylene

    Directory of Open Access Journals (Sweden)

    Carolina Solis Maldonado

    2014-03-01

    Full Text Available The role of iron in two modes of integration into alumina catalysts was studied at 0.39 wt% Fe and tested in trichloroethylene combustion. One modified alumina was synthesized using the sol-gel method with Fe added in situ during hydrolysis; another modification was performed using calcined alumina, prepared using the sol-gel method and impregnated with Fe. Several characterization techniques were used to study the level of Fe modification in the γ-Al2O3 phase formed and to correlate the catalytic properties during trichloroethylene (TCE combustion. The introduction of Fe in situ during the sol-gel process influenced the crystallite size, and three iron species were generated, namely, magnetite, maghemite and hematite. The impregnated Fe-alumina formed hematite and maghemite, which were highly dispersed on the γ-Al2O3 surface. The X-ray photoelectron spectra (XPS, FT-IR and Mössbauer spectroscopy analyses revealed how Fe interacted with the γ-Al2O3 lattice in both catalysts. The impregnated Fe-catalyst showed the best catalytic performance compared to the catalyst that was Fe-doped in situ by the sol-gel method; both had better catalytic activity than pure alumina. This difference in activity was correlated with the accessibility of the reactants to the hematite iron species on the surface. The chlorine poisoning for all three catalysts was less than 1.8%.

  7. Low Concentration Fe-Doped Alumina Catalysts Using Sol-Gel and Impregnation Methods: The Synthesis, Characterization and Catalytic Performance during the Combustion of Trichloroethylene.

    Science.gov (United States)

    Maldonado, Carolina Solis; De la Rosa, Javier Rivera; Lucio-Ortiz, Carlos J; Hernández-Ramírez, Aracely; Barraza, Felipe F Castillón; Valente, Jaime S

    2014-03-12

    The role of iron in two modes of integration into alumina catalysts was studied at 0.39 wt% Fe and tested in trichloroethylene combustion. One modified alumina was synthesized using the sol-gel method with Fe added in situ during hydrolysis; another modification was performed using calcined alumina, prepared using the sol-gel method and impregnated with Fe. Several characterization techniques were used to study the level of Fe modification in the γ-Al₂O₃ phase formed and to correlate the catalytic properties during trichloroethylene (TCE) combustion. The introduction of Fe in situ during the sol-gel process influenced the crystallite size, and three iron species were generated, namely, magnetite, maghemite and hematite. The impregnated Fe-alumina formed hematite and maghemite, which were highly dispersed on the γ-Al₂O 3 surface. The X-ray photoelectron spectra (XPS), FT-IR and Mössbauer spectroscopy analyses revealed how Fe interacted with the γ-Al₂O₃ lattice in both catalysts. The impregnated Fe-catalyst showed the best catalytic performance compared to the catalyst that was Fe-doped in situ by the sol-gel method; both had better catalytic activity than pure alumina. This difference in activity was correlated with the accessibility of the reactants to the hematite iron species on the surface. The chlorine poisoning for all three catalysts was less than 1.8%.

  8. Synthesis and optical characterization of C-SiO2 and C-NiO sol-gel composite films for use as selective solar absorbers

    CSIR Research Space (South Africa)

    Makiwa, G

    2008-08-01

    Full Text Available The authors present a cheaper and environmentally friendly method to fabricate efficient spectrally selective solar absorber materials. The sol-gel technique was used to fabricate carbon-silica (C-SiO2) and carbon-nickel oxide (C-NiO) composite...

  9. Water swelling, brine soluble imidazole based zwitterionic polymers-synthesis and study of reversible UCST behaviour and gel-sol transitions

    NARCIS (Netherlands)

    Vasantha, Vivek Arjunan; Jana, Satyasankar; Parthiban, Anbanandam; Vancso, Julius G.

    2014-01-01

    New vinylbenzene substituted imidazole based zwitterionic polymers with unique characteristics like swelling in water and solubility in concentrated brine solution in which they exhibited a reversible upper critical solution temperature (UCST) and gel-sol transitions are reported herein. © 2014 The

  10. Aluminium trihydroxide in combination with ammonium polyphosphate as flame retardants for unsaturated polyester resin

    Directory of Open Access Journals (Sweden)

    2009-11-01

    Full Text Available The thermal and reaction to fire characteristics of a flame retardant unsaturated polyester (UP ternary system are presented here. Thermal gravimetric analysis showed an improved thermal stability between 200–600°C with the addition of ammonium polyphosphate (APP and aluminium trihydroxide (ATH formulation. Cone calorimetry tests indicated that ATH is more efficient than calcium carbonate at delaying the ignition time, lowering the carbon monoxide yield and lowering the peak heat release (PHRR. However the addition of APP and ATH to the formulation failed to demonstrate any significant synergistic effect at reducing the PHRR.

  11. On the synthesis of CoAPO-46, -11 and -44 molecular sieves from a Co(Ac)2 · 4H2O· Al(iPrO)3·H3PO4 · Pr2NH·H2O gel via experimental design

    NARCIS (Netherlands)

    Gao, Q.; Weckhuysen, B.M.; Schoonheydt, R.A.

    1999-01-01

    The hydrothermal synthesis of cobalt-substituted microporous alumino-phosphates from an r[Pr2NH] ·[CoxAl1−xP1]O4 · y[H2O] gel is described. A well-defined set of experiments, based on an experimental design, was carried out in order to rationalize the influence of the crystallization

  12. One-step synthesis of highly efficient nanocatalysts on the supports with hierarchical pores using porous ionic liquid-water gel.

    Science.gov (United States)

    Kang, Xinchen; Zhang, Jianling; Shang, Wenting; Wu, Tianbin; Zhang, Peng; Han, Buxing; Wu, Zhonghua; Mo, Guang; Xing, Xueqing

    2014-03-12

    Stable porous ionic liquid-water gel induced by inorganic salts was created for the first time. The porous gel was used to develop a one-step method to synthesize supported metal nanocatalysts. Au/SiO2, Ru/SiO2, Pd/Cu(2-pymo)2 metal-organic framework (Cu-MOF), and Au/polyacrylamide (PAM) were synthesized, in which the supports had hierarchical meso- and macropores, the size of the metal nanocatalysts could be very small (esterification of benzyl alcohol to methyl benzoate, benzene hydrogenation to cyclohexane, and oxidation of benzyl alcohol to benzaldehyde because they combined the advantages of the nanocatalysts of small size and hierarchical porosity of the supports. In addition, this method is very simple.

  13. Synthesis and characterization of hollow {alpha}-Fe{sub 2}O{sub 3} sub-micron spheres prepared by sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Leon, Lizbet, E-mail: lizbetlf@gmail.com; Bustamante, Angel; Osorio, Ana; Olarte, G. S. [Universidad Nacional Mayor de San Marcos (Peru); Santos Valladares, Luis De Los, E-mail: ld301@cam.ac.uk; Barnes, Crispin H. W. [University of Cambridge, Cavendish Laboratory (United Kingdom); Majima, Yutaka [Tokyo Institute of Technology, Materials and Structures Laboratory (Japan)

    2011-11-15

    In this work we report the preparation of magnetic hematite hollow sub-micron spheres ({alpha}-Fe{sub 2}O{sub 3}) by colloidal suspensions of ferric nitrate nine-hydrate (Fe(NO{sub 3}){sub 3}{center_dot}9H{sub 2}O) particles in citric acid solution by following the sol-gel method. After the gel formation, the samples were annealed at different temperatures in an oxidizing atmosphere. Annealing at 180 Degree-Sign C resulted in an amorphous phase, without iron oxide formation. Annealing at 250 Degree-Sign C resulted in coexisting phases of hematite, maghemite and magnetite, whereas at 400 Degree-Sign C, only hematite and maghemite were found. Pure hematite hollow sub-micron spheres with porous shells were formed after annealing at 600 Degree-Sign C. The characterization was performed by X-ray diffraction (XRD), Moessbauer spectroscopy (MS) and scanning electron microscopy (SEM).

  14. Synthesis of SrCo {sub x} Ti {sub x} Fe{sub (12-2{sub x})}O{sub 19} through sol-gel auto-ignition and its characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Simon [Chemistry and Physics, Nottingham Trent University, Clifton Lane, Clifton, Nottingham, NG11 8NS (United Kingdom); Shirtcliffe, Neil J. [Chemistry and Physics, Nottingham Trent University, Clifton Lane, Clifton, Nottingham, NG11 8NS (United Kingdom)]. E-mail: neil.shirtcliffe@ntu.ac.uk; O' Keefe, Eoin S. [QinetiQ, Farnborough, Hampshire (United Kingdom); Appleton, Steve [QinetiQ, Farnborough, Hampshire (United Kingdom); Perry, Carole C. [Chemistry and Physics, Nottingham Trent University, Clifton Lane, Clifton, Nottingham, NG11 8NS (United Kingdom)]. E-mail: carole.perry@ntu.ac.uk

    2005-04-15

    Cobalt-titanium-doped strontium hexaferrites SrCo {sub x} Ti {sub x} Fe{sub (12-2{sub x})}O{sub 19} were synthesised via a sol-gel route using two different complexing agents (ethylene glycol and citric acid). Both routes led to quite pure undoped Sr ferrites, but the citric acid route formed purer doped materials. All synthesised materials consisted of particles smaller than 1 {mu}m, which is the size of a single magnetic domain, and various doping levels were achieved with the final elemental composition being within the bounds of experimental error. The materials synthesised using citric acid were compared with materials synthesised by a solid-state route using ferromagnetic resonance measurements and they were identical within experimental error. Citrate auto-ignition synthesis is more rapid and less prone to contamination than the standard solid-state method and doping levels can be easily varied between runs.

  15. Investigation of lanthanum- and neodymium ion interaction with potassium polyphosphate in aqueous solution

    International Nuclear Information System (INIS)

    Ezhova, Zh.A.; Tananaev, I.V.; Koval', E.M.

    1983-01-01

    A study was made on the interaction in the LaCl 3 -KPO 3 -H 2 O and NdCl 3 -KPO 3 -H 2 O systems at 0 deg C by methods of solubility of residual concentrations and measurement of the pH value. The formation of binary KLa 2 (PO 3 ) 7 x10H 2 O and KLa(PO 3 ) 4 X5H 2 O lanthanum- and potassium polyphosphates, as well as KNd 2 (PO 3 ) 7 X10H 2 O and KNd(PO 3 ) 4 X5H 2 O neodymium- apd potassiUm polyphasphates was established. Chemical, paper-chromatographic, infrared spectroscopic, X-ray diffraction and differential thermal analyses of the prepared compoUnds were conducted. Anhydrous binary lanthanum- and neodymium polyphosphates with potassium-=Kla(PO 3 ) 4 , KNd(PO 3 ) 4 , KLa 2 (PO 3 ) 7 and KNd 2 x(PO 3 ) 7 - eere prepared

  16. Preparation, characterization of microencapsulated ammonium polyphosphate and its flame retardancy in polyurethane composites

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Ming-Yuan; Chen, Wei-Jen [Department of Aviation Mechanical Engineering, China University of Science and Technology, Hsinchu County, 303, Taiwan (China); Kuan, Chen-Feng; Kuan, Hsu-Chiang [Department of Computer Application Engineering, Far East University, Tainan, 744, Taiwan (China); Yang, Jia-Ming [Green Flame Retardant Material Research Laboratory, Department of Safety, Health and Environmental Engineering, Hung-Kuang University, Taichung, 433, Taiwan (China); Chiang, Chin-Lung, E-mail: dragon@sunrise.hk.edu.tw [Green Flame Retardant Material Research Laboratory, Department of Safety, Health and Environmental Engineering, Hung-Kuang University, Taichung, 433, Taiwan (China)

    2016-04-15

    In this study, a novel microencapsulated flame retardant containing ammonium polyphosphate (APP) and an 4,4′-oxydianiline-formaldehyde (OF) resin as the core and shell material was synthesized using in situ polymerization technology. The structure and performance of OF microencapsulated APP (OFAPP) were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. The thermal properties of OFAPP were systematically analyzed through thermogravimetric analysis. Flame retardancy tests, such as limiting oxygen index (LOI) and UL-94, were conducted to evaluate the effect of varying the composition of APP and OFAPP in silanol-terminated polyurethane (Si-PU) composites. The results indicated that the microencapsulation of APP with the OF resin resulted in improved hydrophobicity. The results also revealed that the flame retardancy of the Si-PU/OFAPP composite (LOI = 37%) was higher than that of the Si-PU/APP composite (LOI = 23%) at the same additive loading. - Highlights: • A novel microencapsulated flame retardant was synthesized using in situ polymerization technology. • The microencapsulation of ammonium polyphosphate with the polymer resin resulted in improved hydrophobicity. • Polyurethane composites have excellent thermal stability and flame retardance.

  17. Experimental Plan: Uranium Stabilization Through Polyphosphate Injection 300 Area Uranium Plume Treatability Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    Wellman, Dawn M.; Fruchter, Jonathan S.; Vermeul, Vince R.

    2006-09-20

    This Test Plan describes a laboratory-testing program to be performed at Pacific Northwest National Laboratory (PNNL) in support of the 300-FF-5 Feasibility Study (FS). The objective of the proposed treatability test is to evaluate the efficacy of using polyphosphate injections to treat uranium contaminated groundwater in situ. This study will be used to: (1) Develop implementation cost estimates; (2) Identify implementation challenges; and (3) Investigate the technology's ability to meet remedial objectives These activities will be conducted in parallel with a limited field investigation, which is currently underway to more accurately define the vertical extent of uranium in the vadose zone, and in the capillary fringe zone laterally throughout the plume. The treatability test will establish the viability of the method and, along with characterization data from the limited field investigation, will provide the means for determining how best to implement the technology in the field. By conducting the treatability work in parallel with the ongoing Limited Field Investigation, the resulting Feasibility Study (FS) will provide proven, site-specific information for evaluating polyphosphate addition and selecting a suitable remediation strategy for the uranium plume within the FS time frame at an overall cost savings.

  18. Preparation, characterization of microencapsulated ammonium polyphosphate and its flame retardancy in polyurethane composites

    International Nuclear Information System (INIS)

    Shen, Ming-Yuan; Chen, Wei-Jen; Kuan, Chen-Feng; Kuan, Hsu-Chiang; Yang, Jia-Ming; Chiang, Chin-Lung

    2016-01-01

    In this study, a novel microencapsulated flame retardant containing ammonium polyphosphate (APP) and an 4,4′-oxydianiline-formaldehyde (OF) resin as the core and shell material was synthesized using in situ polymerization technology. The structure and performance of OF microencapsulated APP (OFAPP) were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. The thermal properties of OFAPP were systematically analyzed through thermogravimetric analysis. Flame retardancy tests, such as limiting oxygen index (LOI) and UL-94, were conducted to evaluate the effect of varying the composition of APP and OFAPP in silanol-terminated polyurethane (Si-PU) composites. The results indicated that the microencapsulation of APP with the OF resin resulted in improved hydrophobicity. The results also revealed that the flame retardancy of the Si-PU/OFAPP composite (LOI = 37%) was higher than that of the Si-PU/APP composite (LOI = 23%) at the same additive loading. - Highlights: • A novel microencapsulated flame retardant was synthesized using in situ polymerization technology. • The microencapsulation of ammonium polyphosphate with the polymer resin resulted in improved hydrophobicity. • Polyurethane composites have excellent thermal stability and flame retardance.

  19. The influence of phosphorus precursors on the synthesis and bioactivity of SiO2-CaO-P 2O 5 sol-gel glasses and glass-ceramics.

    Science.gov (United States)

    Siqueira, Renato Luiz; Zanotto, Edgar Dutra

    2013-02-01

    Bioactive glasses and glass-ceramics of the SiO(2)-CaO-P(2)O(5) system were synthesised by means of a sol-gel method using different phosphorus precursors according to their respective rates of hydrolysis-triethylphosphate (OP(OC(2)H(5))(3)), phosphoric acid (H(3)PO(4)) and a solution prepared by dissolving phosphorus oxide (P(2)O(5)) in ethanol. The resulting materials were characterised by differential scanning calorimetry and thermogravimetry, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and by in vitro bioactivity tests in acellular simulated body fluid. The different precursors significantly affected the main steps of the synthesis, beginning with the time required for gel formation. The most striking influence of these precursors was observed during the thermal treatments at 700-1,200 °C that were used to convert the gels into glasses and glass-ceramics. The samples exhibited very different mineralisation behaviours; especially those prepared using the phosphoric acid, which had a reduced onset temperature of crystallisation and an increased resistance to devitrification. However, all resulting materials were bioactive. The in vitro bioactivity of these materials was strongly affected by the heat treatment temperature. In general, their bioactivity decreased with increasing treatment temperature. For crystallised samples obtained above 900 °C, the bioactivity was favoured by the presence of two crystalline phases: wollastonite (CaSiO(3)) and tricalcium phosphate (α-Ca(3)(PO(4))(2)).

  20. Direct synthesis of La9.33Si6O26 ultrafine powder via sol-gel self-combustion method

    International Nuclear Information System (INIS)

    Tian Changan; Liu Junliang; Cai Jun; Zeng Yanwei

    2008-01-01

    Single phase La 9.33 Si 6 O 26 ultrafine powder, as a kind of highly activated precursor to prepare medium-to-low temperature electrolyte for solid oxide fuel cells (SOFCs), has been successfully synthesized via a non-aqueous sol-gel and self-combustion approach from the starting materials: lanthanum nitrate (La(NO 3 ) 3 .6H 2 O), citric acid, ethylene glycol (EG), tetraethyl orthosilicate (TEOS) and ammonium nitrate. The details of gel's self-combustion were investigated by DTA-TG and the structural characterization of as-synthesized powder from self-combustion was performed by XRD and SEM. The results show that La 9.33 Si 6 O 26 single phase of apatite-type crystal structure can be directly synthesized by sol-gel self-combustion method without further calcinations on the condition that the molar ratio (R) of NO 3 - to citric acid and ethylene glycol being 6:1. Such powders composed of well-dispersed particles with an average size of 200 nm and a specific surface area of 5.54 m 2 /g. It can be sintered to 90% of its theoretical density at 1500 deg. C for 10 h, about 200 deg. C lower than the sintering temperature for the powder derived from traditional solid reactions. The sintered material has a thermal expansion coefficient of 9.2 x 10 -6 K -1 between room temperature and 800 deg. C

  1. Simple sol-gel synthesis and characterization of new CoTiO3/CoFe2O4 nanocomposite by using liquid glucose, maltose and starch as fuel, capping and reducing agents.

    Science.gov (United States)

    Ansari, Fatemeh; Sobhani, Azam; Salavati-Niasari, Masoud

    2018-03-15

    The sol-gel auto-combustion technique is an effective method for the synthesis of the composites. In this research for the first time, CoTiO 3 /CoFe 2 O 4 nanocomposites are successfully synthesized via a new sol-gel auto-combustion technique. The glucose, maltose and starch are used as fuel, capping and reducing agents, also the optimal reducing agent is chosen. The effects of quantity of reducing agent, molar ratio of Ti:Co, calcination temperature and time on the morphology, particle size, magnetic property, purity and phase of the nanocomposites are investigated. XRD patterns show formation of CoTiO 3 /CoFe 2 O 4 spherical nanoparticles with nearly evenly distribution, when the molar ratio of Co/Ti is 1:1. EDS analysis confirm results of XRD. The magnetic behavior of the nanocomposites is studied by VSM. The nanocomposites exhibit a high coercivity at room temperature. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Synthesis, characterization and hemolysis studies of Zn{sub (1−x)}Ca{sub x}Fe{sub 2}O{sub 4} ferrites synthesized by sol-gel for hyperthermia treatment applications

    Energy Technology Data Exchange (ETDEWEB)

    Jasso-Terán, Rosario Argentina, E-mail: arg.jasso@gmail.com; Cortés-Hernández, Dora Alicia; Sánchez-Fuentes, Héctor Javier; Reyes-Rodríguez, Pamela Yajaira; León-Prado, Laura Elena de; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel

    2017-04-01

    The synthesis of Zn{sub (1−x)}Ca{sub x}Fe{sub 2}O{sub 4} nanoparticles, x=0, 0.25, 0.50, 0.75 and 1.0, was performed by sol-gel method followed by a heat treatment at 400 °C for 30 min. These ferrites showed nanometric sizes and nearly superparamagnetic behavior. The Zn{sub 0.50}Ca{sub 0.50}Fe{sub 2}O{sub 4} and CaFe{sub 2}O{sub 4} ferrites presented a size within the range of 12–14 nm and appropriate heating ability for hyperthermia applications. Hemolysis testing demonstrated that Zn{sub 0.50}Ca{sub 0.50}Fe{sub 2}O{sub 4} ferrite was not cytotoxic when using 10 mg of ferrite/mL of solution. According to the results obtained, Zn{sub 0.50}Ca{sub 0.50}Fe{sub 2}O{sub 4} is a potential material for cancer treatment by magnetic hyperthermia therapy. - Highlights: • The synthesis of Zn{sub (1−x)}Ca{sub x}Fe{sub 2}O{sub 4} ferrites was performed by sol-gel method. • CaFe{sub 2}O{sub 4} and Zn{sub 0.50}Ca{sub 0.}50Fe{sub 2}O{sub 4} ferrites showed heating ability. • The Zn{sub 0.50}Ca{sub 0.50}Fe{sub 2}O{sub 4} ferrite demonstrated to be no hemolytic.

  3. Polymer architecture of magnetic gels: a review

    Science.gov (United States)

    Weeber, Rudolf; Hermes, Melissa; Schmidt, Annette M.; Holm, Christian

    2018-02-01

    In this review article, we provide an introduction to ferrogels, i.e. polymeric gels with embedded magnetic particles. Due to the interplay between magnetic and elastic properties of these materials, they are promising candidates for engineering and biomedical applications such as actuation and controlled drug release. Particular emphasis will be put on the polymer architecture of magnetic gels since it controls the degrees of freedom of the magnetic particles in the gel, and it is important for the particle-polymer coupling determining the mechanisms available for the gel deformation in magnetic fields. We report on the different polymer architectures that have been realized so far, and provide an overview of synthesis strategies and experimental techniques for the characterization of these materials. We further focus on theoretical and simulational studies carried out on magnetic gels, and highlight their contributions towards understanding the influence of the gels’ polymer architecture.

  4. In situ identification of polyphosphate- and polyhydroxyalkanoate-accumulating traits for microbial populations in a biological phosphorus removal process

    DEFF Research Database (Denmark)

    Liu, W.-T.; Nielsen, Alex Toftgaard; Wu, JH

    2001-01-01

    , electron microscopy with energy-dispersive X-ray analysis was used to validate the staining specificity of 4,6-diamino-2-phenylindole (DAPI) for intracellular polyphosphate and revealed the composition of polyphosphate granules accumulated in predominant bacteria as mostly P, Ca and Na. As a result, DAPI......, one novel rod-shaped group, closely related to coccus-shaped Tetrasphaera, and one filamentous group resembling Candidatus Nostocoidia limicola in the HGC group were found to accumulate polyphosphate but not PHA, No cellular inclusions were detected in most members of the alpha -Proteobacteria...

  5. Rational Synthesis of Imprinted Organofunctional Sol-Gel Materials for Toxic Metal Separation - Final Report - 09/15/1997 - 09/14/2001

    International Nuclear Information System (INIS)

    Xue, Ziling; Barnes, Craig E.; Dai, Shang

    2001-01-01

    Current cost estimates for the environmental remediation of contaminated installations under the auspices of the Department of Energy (DOE) are staggering. On this basis alone, there is a critical need to develop the scientific basis for new approaches to the treatment and disposal of toxic metal ions from wastes or contaminated areas at many DOE sites. The overall goal of this project is to rationally design and synthesize imprinted, hybrid inorganic-organic sol-gel materials containing metal binding sites through template approaches, and to develop a scientific basis for metal ion binding and recognition by such tailored hybrid inorganic-organic materials. After removal of the template M, functionalized cavities are created which contain both grafted binding sites and functionality inherent to the silica network (Si-OH, Si-O-Si). These cavities are expected to 'recognize' and bind the target metal ions through the high affinities between the binding sites and M, and their retained shapes. Our approaches utilize both the metal ion binding and the tailored impressions of the template metal ions in the imprinted cavities. Such imprinted organofunctional sol-gel networks are expected to exhibit both high selectivity and capacity for binding targeted ions in fluid waste streams. The principles of sol-gel chemistry and imprinting techniques will guide our approaches to optimize the chemical and physical properties of the imprinted organofunctional sol-gel materials. Cold isotopes or non-radioactive surrogate ions of similar size and charge will be used in imprinting investigations to minimize hazardous waste production. The design strategy we will follow is based on imprinted binding sites cross-linked by rigid, hydrophilic inorganic SiO2 or M'O2 networks. These hydrophilic metal oxide-based materials are expected to exhibit fast ion mass transfer and binding kinetics in comparison to functionalized hydrophobic organic polymers. Success in this research will lead to a

  6. Rational Synthesis of Imprinted Organofunctional Sol-Gel Materials for Toxic Metal Separation - Final Report - 09/15/1997 - 09/14/2001

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Ziling (Ben); Barnes, Craig E.; Dai, Shang

    2001-09-14

    Current cost estimates for the environmental remediation of contaminated installations under the auspices of the Department of Energy (DOE) are staggering. On this basis alone, there is a critical need to develop the scientific basis for new approaches to the treatment and disposal of toxic metal ions from wastes or contaminated areas at many DOE sites. The overall goal of this project is to rationally design and synthesize imprinted, hybrid inorganic-organic sol-gel materials containing metal binding sites through template approaches, and to develop a scientific basis for metal ion binding and recognition by such tailored hybrid inorganic-organic materials. After removal of the template M, functionalized cavities are created which contain both grafted binding sites and functionality inherent to the silica network (Si-OH, Si-O-Si). These cavities are expected to ''recognize'' and bind the target metal ions through the high affinities between the binding sites and M, and their retained shapes. Our approaches utilize both the metal ion binding and the tailored impressions of the template metal ions in the imprinted cavities. Such imprinted organofunctional sol-gel networks are expected to exhibit both high selectivity and capacity for binding targeted ions in fluid waste streams. The principles of sol-gel chemistry and imprinting techniques will guide our approaches to optimize the chemical and physical properties of the imprinted organofunctional sol-gel materials. Cold isotopes or non-radioactive surrogate ions of similar size and charge will be used in imprinting investigations to minimize hazardous waste production. The design strategy we will follow is based on imprinted binding sites cross-linked by rigid, hydrophilic inorganic SiO{sub 2} or MiO{sub 2} networks. These hydrophilic metal oxide-based materials are expected to exhibit fast ion mass transfer and binding kinetics in comparison to functionalized hydrophobic organic polymers

  7. Sol–gel synthesis of vanadium doped titania: Effect of the synthetic routes and investigation of their photocatalytic properties in the presence of natural sunlight

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Godlisten N., E-mail: shaogod@gmail.com [Department of Chemical Engineering, Hanyang University, 1271 Sa 3-dong, Sangnok-gu, Ansan-si, Gyeonggi-do 426-791 (Korea, Republic of); Department of Chemistry, Mkwawa College, University of Dar es Salaam, Iringa, United Republic of Tanzania (Tanzania, United Republic of); Imran, S.M.; Jeon, Sun Jeong; Kang, Shin Jae; Haider, S.M. [Department of Chemical Engineering, Hanyang University, 1271 Sa 3-dong, Sangnok-gu, Ansan-si, Gyeonggi-do 426-791 (Korea, Republic of); Kim, Hee Taik, E-mail: khtaik@yahoo.com [Department of Chemical Engineering, Hanyang University, 1271 Sa 3-dong, Sangnok-gu, Ansan-si, Gyeonggi-do 426-791 (Korea, Republic of)

    2015-10-01

    Highlights: • Sol–gel routes to yield vanadium doped titania from cheap source are proposed. • Photocatalysts with different titania polymorphs are yielded through calcination. • The vanadium doped titania samples show strong absorption in the visible region. • The activities of the photocatalysts are assessed in the presence of visible light. • The calcined samples are obtained through two-step process exhibit superior activities. - Abstract: The development of visible-light effective TiO{sub 2} photocatalysts allows low cost degradation of toxic non-biodegradable organic pollutants. In the present study a series of vanadium doped titania (V-TiO{sub 2}) photocatalysts with V-to-Ti of 0.03, 0.06 and 0.1 were synthesized by either one-step or two-step modified sol–gel approaches. Titanium oxychloride solution was used as a titania source while vanadium pentaoxide was used as a vanadia source to form V-TiO{sub 2} in the absence of surfactants. One-step process was performed through the reaction of the TiO{sub 2} source with vanadium source. In two-step route the Ti(OH){sub 4} gel was preformed through gelation of the TiO{sub 2} source using ammonium solution and then peptized in the acidic vanadium solution. The physicochemical properties of the samples were examined by XRF, XRD, UV–visible DRS, SEM-EDAX, TEM, DTA-TGA, XPS and nitrogen gas physisorption studies analyses. It was observed that the morphology, crystal structure and photochemical properties of the obtained samples were largely dependent on the calcination temperature, synthetic approach and V-to-Ti ratios. Calcination of the samples yielded large ultrafine and perhaps monodispersed particles with different sizes depending on the synthetic technique. The photocatalytic performance of the samples was tested in the photodegradation of methylene blue in the presence of natural sunlight. The photocatalytic activities of the samples synthesized by two-step route were higher than that of the

  8. Enhancing the versatility of alternate current biosusceptometry (ACB) through the synthesis of a dextrose-modified tracer and a magnetic muco-adhesive cellulose gel

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Murillo L., E-mail: murillolongo@gmail.com [Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark); Instituto de Biociências, Universidade Estadual Paulista, CP 510, 18618–970 Botucatu SP (Brazil); Calabresi, Marcos F.; Quini, Caio; Matos, Juliana F.; Miranda, José R.A.; Saeki, Margarida J. [Instituto de Biociências, Universidade Estadual Paulista, CP 510, 18618–970 Botucatu SP (Brazil); Bordallo, Heloisa N. [Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark)

    2015-03-01

    Alternate Current Biosusceptometry (ACB) is a promising bio-magnetic method, radiation free and easily performed used for gastric emptying exams. Due to development on its sensitivity level, interesting nature, noninvasiveness and low cost it has attracted a lot of attention. In this work, magnetic nanoparticles of Mn–Zn ferrite as well as dextrose-modified nanoparticles were synthesized to be used as possible tracers in ACB gastric emptying exams. In addition, a magnetic muco-adhesive gel was obtained by modifying the ferrite nanoparticles with cellulose. Based on in-vivo tests in rats, we show that the pure ferrite nanoparticles, whose isoelectric point was found to be at pH = 3.2, present a great sensitivity to pH variations along the gastrointestinal tract, while the reduction of the isoelectric point by the dextrose modification leads to suitable nanoparticles for rapid gastric emptying examinations. On the other hand, the in-vivo tests show that the muco-adhesive cellulose gel presents substantial stomach adhesion and is a potential drug delivery system easily traceable by the ACB system.

  9. Enhancing the versatility of alternate current biosusceptometry (ACB) through the synthesis of a dextrose-modified tracer and a magnetic muco-adhesive cellulose gel

    International Nuclear Information System (INIS)

    Martins, Murillo L.; Calabresi, Marcos F.; Quini, Caio; Matos, Juliana F.; Miranda, José R.A.; Saeki, Margarida J.; Bordallo, Heloisa N.

    2015-01-01

    Alternate Current Biosusceptometry (ACB) is a promising bio-magnetic method, radiation free and easily performed used for gastric emptying exams. Due to development on its sensitivity level, interesting nature, noninvasiveness and low cost it has attracted a lot of attention. In this work, magnetic nanoparticles of Mn–Zn ferrite as well as dextrose-modified nanoparticles were synthesized to be used as possible tracers in ACB gastric emptying exams. In addition, a magnetic muco-adhesive gel was obtained by modifying the ferrite nanoparticles with cellulose. Based on in-vivo tests in rats, we show that the pure ferrite nanoparticles, whose isoelectric point was found to be at pH = 3.2, present a great sensitivity to pH variations along the gastrointestinal tract, while the reduction of the isoelectric point by the dextrose modification leads to suitable nanoparticles for rapid gastric emptying examinations. On the other hand, the in-vivo tests show that the muco-adhesive cellulose gel presents substantial stomach adhesion and is a potential drug delivery system easily traceable by the ACB system

  10. Low-Temperature Sol-Gel Synthesis of Nitrogen-Doped Anatase/Brookite Biphasic Nanoparticles with High Surface Area and Visible-Light Performance

    Directory of Open Access Journals (Sweden)

    Liang Jiang

    2017-12-01

    Full Text Available Nitrogen doping in combination with the brookite phase or a mixture of TiO2 polymorphs nanomaterials can enhance photocatalytic activity under visible light. Generally, nitrogen-dopedanatase/brookite mixed phases TiO2 nanoparticles obtained by hydrothermal or solvothermal method need to be at high temperature and with long time heating treatment. Furthermore, the surface areas of them are low (<125 m2/g. There is hardly a report on the simple and direct preparation of N-doped anatase/brookite mixed phase TiO2 nanostructures using sol-gel method at low heating temperature. In this paper, the nitrogen-doped anatase/brookite biphasic nanoparticles with large surface area (240 m2/g were successfully prepared using sol-gel method at low temperature (165 °C, and with short heating time (4 h under autogenous pressure. The obtained sample without subsequent annealing at elevated temperatures showed enhanced photocatalytic efficiency for the degradation of methyl orange (MO with 4.2-, 9.6-, and 7.5-fold visible light activities compared to P25 and the amorphous samples heated in muffle furnace with air or in tube furnace with a flow of nitrogen at 165 °C, respectively. This result was attributed to the synergistic effects of nitrogen doping, mixed crystalline phases, and high surface area.

  11. Facile synthesis of radial-like macroporous superparamagnetic chitosan spheres with in-situ co-precipitation and gelation of ferro-gels.

    Directory of Open Access Journals (Sweden)

    Chih-Hui Yang

    Full Text Available Macroporous chitosan spheres encapsulating superparamagnetic iron oxide nanoparticles were synthesized by a facile and effective one-step fabrication process. Ferro-gels containing ferrous cations, ferric cations and chitosan were dropped into a sodium hydroxide solution through a syringe pump. In addition, a sodium hydroxide solution was employed for both gelation (chitosan and co-precipitation (ferrous cations and ferric cations of the ferro-gels. The results showed that the in-situ co-precipitation of ferro-ions gave rise to a radial morphology with non-spheroid macro pores (large cavities inside the chitosan spheres. The particle size of iron oxide can be adjusted from 2.5 nm to 5.4 nm by tuning the concentration of the sodium hydroxide solution. Using Fourier Transform Infrared Spectroscopy and X-ray diffraction spectra, the synthesized nanoparticles were illustrated as Fe(3O(4 nanoparticles. In addition, the prepared macroporous chitosan spheres presented a super-paramagnetic behaviour at room temperature with a saturation magnetization value as high as ca. 18 emu/g. The cytotoxicity was estimated using cell viability by incubating doses (0∼1000 µg/mL of the macroporous chitosan spheres. The result showed good viability (above 80% with alginate chitosan particles below 1000 µg/mL, indicating that macroporous chitosan spheres were potentially useful for biomedical applications in the future.

  12. Enhancing the versatility of alternate current biosusceptometry (ACB) through the synthesis of a dextrose-modified tracer and a magnetic muco-adhesive cellulose gel.

    Science.gov (United States)

    Martins, Murillo L; Calabresi, Marcos F; Quini, Caio; Matos, Juliana F; Miranda, José R A; Saeki, Margarida J; Bordallo, Heloisa N

    2015-03-01

    Alternate Current Biosusceptometry (ACB) is a promising bio-magnetic method, radiation free and easily performed used for gastric emptying exams. Due to development on its sensitivity level, interesting nature, noninvasiveness and low cost it has attracted a lot of attention. In this work, magnetic nanoparticles of Mn-Zn ferrite as well as dextrose-modified nanoparticles were synthesized to be used as possible tracers in ACB gastric emptying exams. In addition, a magnetic muco-adhesive gel was obtained by modifying the ferrite nanoparticles with cellulose. Based on in-vivo tests in rats, we show that the pure ferrite nanoparticles, whose isoelectric point was found to be at pH=3.2, present a great sensitivity to pH variations along the gastrointestinal tract, while the reduction of the isoelectric point by the dextrose modification leads to suitable nanoparticles for rapid gastric emptying examinations. On the other hand, the in-vivo tests show that the muco-adhesive cellulose gel presents substantial stomach adhesion and is a potential drug delivery system easily traceable by the ACB system. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Sol-gel synthesis and characterizations of crystalline NaGd(WO4)2 powder for anisotropic transparent ceramic laser application

    Science.gov (United States)

    Durairajan, A.; Thangaraju, D.; Balaji, D.; Moorthy Babu, S.

    2013-02-01

    NaGd(WO4)2 powders were synthesized at different pH (3.5, 4.5, 5.5, 6.5 and 7.5) values by conventional Pechini method. Sodium and gadolinium nitrate salts and ammonium paratungstate are used as starting precursors. Metal cations were chelated by citric acid and individual citrates were bound together with ethylene glycol. Synthesized gel was analyzed using differential thermal analysis (DTA), thermo gravimetric (TG) and FT-IR spectroscopy to understand the degradation of gel and formation of metal citrates. Calcined powders (250, 600, 700 and 800 °C) were characterized by powder XRD, FT-IR, Raman and FE-SEM analysis. The temperature dependent phase formation was examined by powder XRD. The morphological changes at different pH derived powders were observed with FE-SEM micrographs. Stepwise organic liberation with respect to temperature and presence of carbon content in the pre-fired powder were analyzed using FT-IR analysis. Raman spectrum reveals disordered tungstate vibrations in the NGW matrix.

  14. Stabilized γ-BIMNVOX solid electrolyte: Ethylene glycol–citrate sol–gel synthesis, microwave-assisted calcination, and structural and electrical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Al-Areqi, Niyazi A.S., E-mail: niyazi.alareqi@gmail.com [Department of Chemistry, Faculty of Applied Science, Taiz University, Taiz, Republic of Yemen (Yemen); Beg, Saba [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India); Al-Alas, Ahlam [Department of Chemistry, Faculty of Applied Science, Taiz University, Taiz, Republic of Yemen (Yemen); Hafeez, Shehla [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India)

    2013-12-25

    Highlights: •γ-BIMNVOX was synthesized by ethylene glycol–citrate sol–gel route. •γ-BIMNVOX crystallizes by 25-min microwave-assisted calcination. •Smaller particle sizes for microwave calcined BIMNVOX samples. •Best oxide-ion performance for microwave calcined BIMNVOX samples. -- Abstract: Samples of γ-BIMNVOX (Bi{sub 2}V{sub 1−x}Mn{sub x}O{sub 5.5−x/2}; 0.13 ⩽ x ⩽ 0.20) system were synthesized by an ethylene glycol–citrate sol–gel route. The resulting xerogels were then calcined by the microwave heating using a modified domestic microwave oven operated at 2.45 GHz. Microwave-assisted calcination samples in comparison with other conventionally calcined samples were characterized in terms of phase crystallization, stabilization and particle size using simultaneous thermogravimetric–differential thermal analysis (TG–DTA), X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM). The AC impedance spectroscopy was employed for electrical characterization. It was found that the microwave-assisted calcination route successfully produces better crystalline stabilized γ-BIMNVOX samples with appreciably small average particle sizes after only 25 min of microwave heating. The electrical properties of microwave calcined γ-BIMNVOX system make it an advanced low-temperature solid electrolyte suitable for use in oxide-ion based electrochemical applications.

  15. Sol-gel auto-combustion synthesis of SiO{sub 2}-doped NiZn ferrite by using various fuels

    Energy Technology Data Exchange (ETDEWEB)

    Wu, K.H. [Department of Applied Chemistry, Chung Cheng Institute of Technology, NDU, No. 190, Sanyuan 1st Street, Dashi Jen, Tahsi, Taoyuan 335, Taiwan (China)]. E-mail: khwu@ccit.edu.tw; Ting, T.H. [Department of Applied Chemistry, Chung Cheng Institute of Technology, NDU, No. 190, Sanyuan 1st Street, Dashi Jen, Tahsi, Taoyuan 335, Taiwan (China); Li, M.C. [Department of Applied Chemistry, Chung Cheng Institute of Technology, NDU, No. 190, Sanyuan 1st Street, Dashi Jen, Tahsi, Taoyuan 335, Taiwan (China); Ho, W.D. [Chemical Systems Research Division, Chung Shan Institute of Science and Technology, Taoyuan, Taiwan (China)

    2006-03-15

    A nitrate-chelate-silica gel was prepared from metallic nitrates, citric acid and tetraethoxysilane (TEOS) by sol-gel process with different complexing agents such as glycine, hydrazine and citric acid, and it was further used to synthesize Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}/20 wt% SiO{sub 2} nanocomposites by auto-combustion. The effect of varying complexing agent on the structural and magnetic properties of the composites was studied by FTIR, {sup 29}Si CP/MAS NMR, XRD, TEM, EPR and SQUID measurements. The complexing agent in the starting solution influenced the magnetic interaction between NiZn ferrite and silica, and then determined on the particle size. Further, the complexing agent type had a direct effect on the EPR parameters ({delta}H {sub PP}, g-factor and T {sub 2}) and SQUID parameters (M {sub s}, M {sub r} and H {sub c}) of the as-synthesized powder.

  16. One-pot synthesis of a graphene oxide coated with an imprinted sol–gel for use in electrochemical sensing of paracetamole

    International Nuclear Information System (INIS)

    Luo, Jing; Cong, Jiaojiao; Fang, Ruixue; Fei, Xiaoma; Liu, Xiaoya

    2014-01-01

    A route is described for the preparation of a composite consisting of graphene oxide and a molecularly imprinted sol–gel polymer (GO/MIPs) through one-pot room temperature polymerization in aqueous solution. The material was obtained by mixing graphene oxide with the monomers (phenyltriethoxysilane and tetramethoxysilane) and the template paracetamole, followed by sol–gel copolymerization and extraction. The monomer and template concentrations and the incubation time were optimized. The composite was characterized by FTIR, TGA, XRD, Raman spectroscopy and SEM. It was then deposited as a thin film acting as a molecular recognition element on a glassy carbon electrode to obtain an electrochemical sensor for paracetamole. The electrode displayed an excellent recognition capacity toward paracetamole compared to its analogs. The peak current is linearly proportional to the concentration of paracetamole in the 0.1 μM to 80 μM range, and the detection limit is 20 nM (at an SNR of 3). Hence, this electrode possesses a wider response range and lower detection limit compared to most previously reported electrochemical sensors for paracetamole. It also exhibits excellent stability and has been successfully used to determine paracetamole in tablets and spiked human urine samples. (author)

  17. Synthesis of ZrO2-TiO2 mixed oxide spheres by sol-gel method and investigation of Sr adsorption behaviours by experimental design approach

    International Nuclear Information System (INIS)

    Cetinkaya, B.; Tel, H.; Altas, Y.; Eral, M.; Sert, S.; Inan, S.; Talip, Z.

    2009-01-01

    ZrO 2 -TiO 2 gel spheres were synthesized by sol-gel method. Zr-Ti sol solution was prepared from ZrCl 4 and TiCl 4 (1:1 mol ratio) via partial neutralization by ammonia to obtain 0.5M final metal concentration. ZrO 2 -TiO 2 sol was transferred to vibrating nozzle system by peristaltic pump. Vibrating nozzle system was designed and produced in Institute of Nuclear Sciences. Sol drops formed by nozzle were gelled in gelation column. Synthesized ZrO 2 -TiO 2 spheres were aged for 24h then washed with deionized water and dried in oven. Sr + 2 adsorption behaviors of ZrO 2 -TiO 2 mixed oxides were investigated with central composite design (CCD). Four independent parameters (pH, initial Sr + 2 concentration, temperature and contact time) were investigated with 7 replicates at central points. Sorption data have been interpreted in terms of Langmuir, Freundlich and Dubinin Radushkevich equations. Thermodynamic parameters for the sorption system have been determined.

  18. Decreased bone uptake of technetium-99m polyphosphate in thalassemia major

    International Nuclear Information System (INIS)

    Valdez, V.A.; Jacobstein, J.G.

    1980-01-01

    Bone scans were performed with Tc-99m stannous polyphosphate on four patients with thalassemia major. Three of the scans show generalized decrease in skeletal uptake of the radiopharmaceutical, associated with renal enlargement and markedly increased renal radioactivity. The skeletal findings are consistent with the known bone abnormalities in thalassemia major, which are secondary to the extensive marrow hyperplasia and include loss of trabeculae and cortical thinning with consequent loss of bone mass. The increased renal uptake is probably due in part to the increased renal excretion (secondary to the poor bone uptake) and in part to the tubular dilatation and renal enlargement associated with thalassemia major. In addition, the presence of excessive amounts of iron in these patients may play a role in both the skeletal and renal findings

  19. Spores of the mycorrhizal fungus Glomus mosseae host yeasts that solubilize phosphate and accumulate polyphosphates.

    Science.gov (United States)

    Mirabal Alonso, Loreli; Kleiner, Diethelm; Ortega, Eduardo

    2008-04-01

    The present paper reports the presence of bacteria and yeasts tightly associated with spores of an isolate of Glomus mosseae. Healthy spores were surface disinfected by combining chloramine-T 5%, Tween-40, and cephalexin 2.5 g L(-1) (CTCf). Macerates of these spores were incubated on agar media, microorganisms were isolated, and two yeasts were characterized (EndoGm1, EndoGm11). Both yeasts were able to solubilize low-soluble P sources (Ca and Fe phosphates) and accumulate polyphosphates (polyPs). Sequence analysis of 18S ribosomal deoxyribonucleic acid showed that the yeasts belong to the genera Rhodotorula or Rhodosporidium (EndoGm1) and Cryptococcus (EndoGm11). Results from inoculation experiments showed an effect of the spore-associated yeasts on the root growth of rice, suggesting potential tripartite interactions with mycorrhizal fungi and plants.

  20. New structural and functional defects in polyphosphate deficient bacteria: A cellular and proteomic study

    Directory of Open Access Journals (Sweden)

    Chávez Francisco P

    2010-01-01

    Full Text Available Abstract Background Inorganic polyphosphate (polyP, a polymer of tens or hundreds of phosphate residues linked by ATP-like bonds, is found in all organisms and performs a wide variety of functions. PolyP is synthesized in bacterial cells by the actions of polyphosphate kinases (PPK1 and PPK2 and degraded by exopolyphosphatase (PPX. Bacterial cells with polyP deficiencies due to knocking out the ppk1 gene are affected in many structural and important cellular functions such as motility, quorum sensing, biofilm formation and virulence among others. The cause of this pleiotropy is not entirely understood. Results The overexpression of exopolyphosphatase in bacteria mimicked some pleitropic defects found in ppk1 mutants. By using this approach we found new structural and functional defects in the polyP-accumulating bacteria Pseudomonas sp. B4, which are most likely due to differences in the polyP-removal strategy. Colony morphology phenotype, lipopolysaccharide (LPS structure changes and cellular division malfunction were observed. Finally, we used comparative proteomics in order to elucidate the cellular adjustments that occurred during polyP deficiency in this bacterium and found some clues that helped to understand the structural and functional defects observed. Conclusions The results obtained suggest that during polyP deficiency energy metabolism and particularly nucleoside triphosphate (NTP formation were affected and that bacterial cells overcame this problem by increasing the flux of energy-generating metabolic pathways such as tricarboxilic acid (TCA cycle, β-oxidation and oxidative phosphorylation and by reducing energy-consuming ones such as active transporters and amino acid biosynthesis. Furthermore, our results suggest that a general stress response also took place in the cell during polyP deficiency.

  1. Synthesis of ZnO thin film by sol-gel spin coating technique for H2S gas sensing application

    Science.gov (United States)

    Nimbalkar, Amol R.; Patil, Maruti G.

    2017-12-01

    In this present work, zinc oxide (ZnO) thin film synthesized by a simple sol-gel spin coating technique. The structural, morphology, compositional, microstructural, optical, electrical and gas sensing properties of the film were studied by using XRD, FESEM, EDS, XPS, HRTEM, Raman, FTIR and UV-vis techniques. The ZnO thin film shows hexagonal wurtzite structure with a porous structured morphology. Gas sensing performance of synthesized ZnO thin film was tested initially for H2S gas at different operating temperatures as well as concentrations. The maximum gas response is achieved towards H2S gas at 300 °C operating temperature, at 100 ppm gas concentration as compared to other gases like CH3OH, Cl2, NH3, LPG, CH3COCH3, and C2H5OH with a good stability.

  2. Synthesis of xanthate functionalized silica gel and its application for the preconcentration and separation of uranium(VI) from inorganic components

    International Nuclear Information System (INIS)

    Gopi Krishna, P.; Naidu, G.R.K.; Rao, K.S.

    2005-01-01

    A new chelating solid extractant prepared by the chemical immobilization of xanthate on silica gel was characterized by Fourier transform infra red spectrometry (FTIR), thermogravimetric analysis (TGA) and microanalysis and used for the preconcentration and separation of uranyl ion prior to its determination by Arsenazo-III. The effect of pH, weight of the solid extractant, volume of the aqueous phase and the interference of neutral electrolytes, cations and anions on the determination of uranium, have been studied in detail to optimize the conditions for trace determination of uranium(VI). The accuracy of the developed procedure was tested by analyzing marine sediment (MESS-3) and soil (IAEA-SOIL-7) reference materials. The results obtained on analysis of soil and sediment samples are comparable to standard ICP-MS values. (author)

  3. Sol-gel synthesis of Cu-doped p-CdS nanoparticles and their analysis as p-CdS/n-ZnO thin film photodiode

    Science.gov (United States)

    Arya, Sandeep; Sharma, Asha; Singh, Bikram; Riyas, Mohammad; Bandhoria, Pankaj; Aatif, Mohammad; Gupta, Vinay

    2018-05-01

    Copper (Cu) doped p-CdS nanoparticles have been synthesized via sol-gel method. The as-synthesized nanoparticles were successfully characterized and implemented for fabrication of Glass/ITO/n-ZnO/p-CdS/Al thin film photodiode. The fabricated device is tested for small (-1 V to +1 V) bias voltage. Results verified that the junction leakage current within the dark is very small. During reverse bias condition, the maximum amount of photocurrent is obtained under illumination of 100 μW/cm2. Electrical characterizations confirmed that the external quantum efficiency (EQE), gain and responsivity of n-ZnO/p-CdS photodiode show improved photo response than conventional p-type materials for such a small bias voltage. It is therefore revealed that the Cu-doped CdS nanoparticles is an efficient p-type material for fabrication of thin film photo-devices.

  4. Nickel-based xerogel catalysts: Synthesis via fast sol-gel method and application in catalytic hydrogenation of p-nitrophenol to p-aminophenol

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jin; Wang, Qiang; Fan, Dongliang; Ma, Lirong; Jiang, Deli; Xie, Jimin, E-mail: xiejm391@sohu.com; Zhu, Jianjun, E-mail: zhjj029@sina.com

    2016-09-30

    Graphical abstract: In order to investigate the roles of three-dimensional network structure and calcium on Ni catalysts, the Ni, Ni-Al{sub 2}O{sub 3}, Ni-Ca-Al{sub 2}O{sub 3} xerogel catalysts were successfully synthesized via the fast sol-gel process and chemical reduction method. - Highlights: • Epoxide-driven sol-gel and chemical reduction method subsequently were used to prepare Ni, Ni-Al{sub 2}O{sub 3} and Ni-Ca-Al{sub 2}O{sub 3} catalysts. • Three-dimensional network structure of the gel was employed to adjust the size and distribution of Ni nanoparticles. • Calcium was employed to shorten the gelation time, improve the nickel dispersion, decrease thenickel particle size and strengthen the Ni-Al{sub 2}O{sub 3} interaction. • The rate constants of Ni-Ca-Al2O3 catalysts (2.85 × 10{sup −3} s{sup −1}) is 2.8 times higher than the Ni catalysts (1.02 × 10{sup −3} s{sup −1}) and 2 times higher than the Ni-Al{sub 2}O{sub 3} catalysts(1.42 × 10{sup −3} s{sup −1}). • After 5 cycles, the conversion of PNP to PAP catalyzed by Ni, Ni-Al{sub 2}O{sub 3}, Ni-Ca-Al{sub 2}O{sub 3} remained 85%, 82%, 80%, respectively. - Abstract: In order to investigate the roles of three-dimensional network structure and calcium on Ni catalysts, the Ni, Ni-Al{sub 2}O{sub 3}, Ni-Ca-Al{sub 2}O{sub 3} xerogel catalysts were successfully synthesized via the fast sol-gel process and chemical reduction method. The crystal structure of three different catalysts was observed with X-ray powder diffraction (XRD). Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and nitrogen adsorption-desorption were employed to investigate the role of network structure of xerogel catalysts and the size distribution of Ni nanoparticles. The catalyst composition was determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) measurement and energy-dispersive X-ray spectroscopy (EDS). Temperature-programmed reduction (TPR) experiments were carried

  5. Sol–gel synthesis of long-lasting phosphors CdSiO3: Mn2+, RE3+ (RE = Tb, Eu, Nd) and luminescence mechanism research

    International Nuclear Information System (INIS)

    Qu, Xiaofei; Cao, Lixin; Liu, Wei; Su, Ge; Wang, Pingping; Schultz, Isabel

    2012-01-01

    Highlights: ► New long-lasting CdSiO 3 : Mn 2+ , RE 3+ (RE = Tb, Eu, Nd) phosphors were synthesized by a sol–gel method. ► The afterglow performance of the CdSiO 3 : Mn 2+ , Eu 3+ phosphor was the best. ► The role of RE 3+ co-doped into the CdSiO 3 : Mn 2+ matrix was discussed in this paper. -- Abstract: Mn 2+ and RE 3+ (RE = Tb, Eu, Nd) co-doped CdSiO 3 orange phosphors were prepared at 1050 °C by a sol–gel method. The phase and crystallinity of the synthesized materials were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The luminescence characteristics were analyzed using photoluminescence (PL) spectra, afterglow decay curves, long-lasting phosphorescence spectra, and thermoluminescence (TL) spectra. Due to the difference in co-doped rare earth ionic radii, it varied greatly in trap density and trap depth caused by the different defects deriving from RE 3+ ions co-doping into the CdSiO 3 : Mn 2+ host. The afterglow intensity and time for these samples increased as follows: CdSiO 3 : Mn 2+ 0.2%, Nd 3+ 0.8% 3 : Mn 2+ 0.4%, Tb 3+ 0.8% 3 : Mn 2+ 0.4%, Eu 3+ 0.3%. CdSiO 3 : Mn 2+ 0.4%, Eu 3+ 0.3% had the best afterglow properties, which could be due to the proper traps formed by Eu 3+ ions co-doping into the host. The role of RE 3+ co-doped into the CdSiO 3 : Mn 2+ matrix and the possible long-lasting phosphorescence process was also discussed in this paper.

  6. Sol-gel synthesis of TiO{sub 2}-SiO{sub 2} photocatalyst for {beta}-naphthol photodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Qourzal, S., E-mail: samir_qourzal@yahoo.fr [Equipe de Materiaux Photocatalyse et Environnement, Departement de Chimie, Faculte des Sciences, Universite Ibn Zohr, B. P. 8106 Cite Dakhla, Agadir (Morocco); Barka, N.; Tamimi, M.; Assabbane, A. [Equipe de Materiaux Photocatalyse et Environnement, Departement de Chimie, Faculte des Sciences, Universite Ibn Zohr, B. P. 8106 Cite Dakhla, Agadir (Morocco); Nounah, A. [Ecole Superieure de Technologie, Avenue Prince Heritier Sidi Mohamed, B. P. 227, Sale-Medina (Morocco); Ihlal, A. [Laboratoire de Physique des Semi-conducteurs et Energie Solaire, Departement de Physique, Faculte, des Sciences, Universite Ibn Zohr, B. P. 8106 Cite Dakhla, Agadir (Morocco); Ait-Ichou, Y. [Equipe de Materiaux Photocatalyse et Environnement, Departement de Chimie, Faculte des Sciences, Universite Ibn Zohr, B. P. 8106 Cite Dakhla, Agadir (Morocco)

    2009-06-01

    Silica gel supported titanium dioxide particles (TiO{sub 2}-SiO{sub 2}) prepared by sol-gel method was as photocatalyst in the degradation of {beta}-naphthol in water under UV-illumination. The prepared sample has been characterized by powder X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The supported catalyst had large surface area and good sedimentation ability. The photodegradation rate of {beta}-naphthol under UV-irradiation depended strongly on adsorption capacity of the catalyst, and the photoactivity of the supported catalyst was much higher than that of the pure titanium dioxides. The experiments were measured by high performance liquid chromatography (HPLC). The photodegradation rate of {beta}-naphthol using 60% TiO{sub 2}-SiO{sub 2} particles was faster than that using TiO{sub 2} 'Degussa P-25', TiO{sub 2} 'PC-50' and TiO{sub 2} 'Aldrich' as photocatalyst by 2.7, 4 and 7.8 times, respectively. The kinetics of photocatalytic {beta}-naphthol degradation was found to follow a pseudo-first-order rate law. The effect of the TiO{sub 2} loading on the photoactivity of TiO{sub 2}-SiO{sub 2} particles was also discussed. With good photocatalytic activity under UV-irradiation and the ability to be readily separated from the reaction system, this novel kind of catalyst exhibited the potential effective in the treatment of organic pollutants in aqueous systems.

  7. Tapioca starch: An efficient fuel in gel-combustion synthesis of photocatalytically and anti-microbially active ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ramasami, Alamelu K. [Centre for Nano and Material Sciences, Jain University, Jakkasandra, Kanakapura (T) (India); Raja Naika, H. [Dept. of Biotechnology, University College of Science, Tumkur University, Tumkur (India); Nagabhushana, H. [CNR Rao Centre for Advanced Materials, Tumkur University, Tumkur (India); Ramakrishnappa, T.; Balakrishna, Geetha R. [Centre for Nano and Material Sciences, Jain University, Jakkasandra, Kanakapura (T) (India); Nagaraju, G., E-mail: nagarajugn@rediffmail.com [Centre for Nano and Material Sciences, Jain University, Jakkasandra, Kanakapura (T) (India); Dept. of Chemistry, Siddaganga Institute of Technology, Tumkur (India)

    2015-01-15

    Zinc oxide nanoparticles were synthesized by gel-combustion method using novel bio-fuel tapioca starch pearls, derived from the tubers of Manihotesculenta. The product is characterized using various techniques. The X-ray diffraction pattern correspond to a hexagonal zincite structure. Fourier transform infrared spectrum showed main absorption peaks at 394 and 508 cm{sup −} {sup 1} due to stretching vibration of Zn–O. Ultravoilet–visible spectrum of zinc oxide nanoparticles showed absorption maximum at 373 nm whereas the maximum of the bulk zinc oxide was 377 nm. The morphology of the product was studied using scanning electron microscopy and transmission electron microscopy. The scanning electron microscopic images showed that the products are agglomerated and porous in nature. The transmission electron microscopic images revealed spherical particles of 40–50 nm in diameter. The photocatalytic degradation of methylene blue was examined using zinc oxide nanoparticles and found more efficient in sunlight than ultra-violet light due to reduced band gap. The antibacterial properties of zinc oxide nanoparticles were investigated against four bacterial strains Klebsiella aerogenes, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aereus, where Pseudomonas aeruginosa and Staphylococcus aereus exhibited significant antibacterial activity in agar well diffusion method when compared to positive control. - Highlights: • ZnO nanoparticles have been prepared from a new bio-fuel, tapioca starch by gel combustion method. • XRD pattern revealed hexagonal zincite crystal structure with crystallite size 33 nm. • ZnO nanoparticles exhibited a band gap of 2.70 eV. • The ZnO nanoparticles exhibited superior degradation in sunlight in comparison with UV light. • The product showed a good anti-bacterial activity against two bacterial strains.

  8. Sol-Gel Derived Hafnia Coatings

    Science.gov (United States)

    Feldman, Jay D.; Stackpoole, Mairead; Blum, Yigal; Sacks, Michael; Ellerby, Don; Johnson, Sylvia M.; Venkatapathy, Ethiras (Technical Monitor)

    2002-01-01

    Sol-gel derived hafnia coatings are being developed to provide an oxidation protection layer on ultra-high temperature ceramics for potential use in turbine engines (ultra-efficient engine technology being developed by NASA). Coatings using hafnia sol hafnia filler particles will be discussed along with sol synthesis and characterization.

  9. On the sol-gel synthesis and thermal, structural, and magnetic studies of transition metal (Ni, Co, Mn) containing ZnO powders

    Energy Technology Data Exchange (ETDEWEB)

    Thota, Subhash; Dutta, Titas; Kumar, Jitendra [Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur-208016 (India)

    2006-03-01

    Transition metal containing ZnO powders (Zn{sub 1-x}M{sub x}O, 0{<=}x{<=}0.30; M = Ni, Mn, Co) have been synthesized by a sol-gel process using zinc acetate dihydrate, respective acetate and oxalic acid as precursors with ethanol as a solvent. The process essentially involves gel formation, drying at 80 {sup 0}C for 24 h to provide the oxalate, and calcination at 500 {sup 0}C for 2 h to undergo an exothermic reaction and yield Zn{sub 1-x}M{sub x}O powder. Their XRD patterns correspond to a wurtzite hcp structure similar to that of pure ZnO, but with the lattice parameters varying slightly with type and extent of doping. It is shown that the dissolution of nickel and cobalt in ZnO is less than 10 at.%, whereas that of manganese lies between 10 and 15 at.%. Other phases that emerge include NiO (hexagonal, a = 2.954 A, c = 7.236 A), ZnCo{sub 2}O{sub 4} (cubic, a = 8.094 A) and ZnMnO{sub 3} (cubic, a = 8.35 A) in the Ni, Co and Mn containing ZnO systems, respectively. Observations of hysteresis loops both at 10 and 320 K and the nature of ESR spectra provide evidence for the ferromagnetic state in nickel containing ZnO powder. Besides, the deviation occurs in the magnetization versus temperature curves in zero field cooled (ZFC) and field cooled (FC) conditions (blocking temperature T{sub B} being 32 K for 5 at.% Ni). The magnetic behaviour of manganese and cobalt doped zinc oxide is, however, different, namely (i) no hysteresis loops (ii) decrease in magnetization with increase of Mn or Co content, and (iii) identical M-T curves under ZFC and FC conditions. The inverse susceptibility versus temperature curves of Zn{sub 1-x}Mn{sub x}O compounds reveal ferrimagnetism with Neel temperature T{sub N} of 4 K for x = 0.02, but antiferromagnetism for x = 0.15 and 0.25 with Curie-Weiss temperature of -43 and -30 K, respectively.

  10. Enhancement of Wound Healing in Normal and Diabetic Mice by Topical Application of Amorphous Polyphosphate. Superior Effect of a Host–Guest Composite Material Composed of Collagen (Host and Polyphosphate (Guest

    Directory of Open Access Journals (Sweden)

    Werner E.G. Müller

    2017-07-01

    Full Text Available The effect of polyphosphate (polyP microparticles on wound healing was tested both in vitro and in a mice model in vivo. Two approaches were used: pure salts of polyphosphate, fabricated as amorphous microparticles (MPs, consisting of calcium and magnesium salts of polyP, “Ca–polyp-MPs” and “Mg–polyp-MPs”, and host–guest composite particles, prepared from amorphous collagen (host and polyphosphate (guest, termed “col/polyp-MPs”. Animal experiments with polyP on healing of excisional wounds were performed using both normal mice and diabetic mice. After a healing period of 7 days “Ca–polyp-MP” significantly improved re-epithelialization in normal mice from 31% (control to 72% (polyP microparticle-treated. Importantly, in diabetic mice, particularly the host–guest particles “col/polyp-MP”, increased the rate of re-epithelialization to ≈40% (control, 23%. In addition, those particles increased the expression of COL-I and COL-III as well as the expression the α-smooth muscle actin and the plasminogen activator inhibitor-1. We propose that “Ca–polyp-MPs”, and particularly the host–guest “col/polyp-MPs” are useful for topical treatment of wounds.

  11. Polyphosphates as a source of enhanced P fluxes in marine sediments overlain by anoxic waters: Evidence from 31P NMR

    Directory of Open Access Journals (Sweden)

    Ingall Ellery

    2005-06-01

    Full Text Available Sedimentary phosphorus (P composition was investigated in Effingham Inlet, a fjord located on the west coast of Vancouver Island in Barkley Sound. Solid-state 31P nuclear magnetic resonance (NMR spectroscopy was applied to demineralized sediment samples from sites overlain by oxic and anoxic bottom waters. The two sites were similar in terms of key diagenetic parameters, including the mass accumulation rate, integrated sulfate reduction rate, and bulk sediment organic carbon content. In contrast, P benthic fluxes were much higher at the anoxic site. 31P NMR results show that P esters and phosphonates are the major organic P species present at the surface and at depth in sediments at both sites. Polyphosphates were only found in the surface sediment of the site overlain by oxic waters. The varying stability of polyphosphates in microorganisms under different redox conditions may, in part, explain their distribution as well as differences in P flux between the two sites.

  12. Synthesis of LaVO4/TiO2 heterojunction nanotubes by sol-gel coupled with hydrothermal method for photocatalytic air purification.

    Science.gov (United States)

    Zou, Xuejun; Li, Xinyong; Zhao, Qidong; Liu, Shaomin

    2012-10-01

    With the aim of improving the effective utilization of visible light, the LaVO(4)/TiO(2) heterojunction nanotubes were fabricated by sol-gel coupled with hydrothermal method. The photocatalytic ability was demonstrated through catalytic removal of gaseous toluene species. The nanotube samples were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), surface photovoltage (SPV), Raman spectra and N(2) adsorption-desorption measurements. The characterization results showed that the samples with high specific surface areas were of typical nanotubular morphology, which would lead to the high separation and transfer efficiency of photo induced electron-hole pairs. The as-prepared nanotubes exhibited high photocatalytic activity in decomposing toluene species under visible light irradiation with fine photochemical stability. The enhanced photocatalytic performance of LaVO(4)/TiO(2) nanotubes might be attributed to the matching band potentials, the interconnected heterojunction of LaVO(4) versus TiO(2), and the large specific surface areas of nanotubes. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. The effect of concentration ratio and type of functional group on synthesis of CNT-ZnO hybrid nanomaterial by an in situ sol-gel process

    Science.gov (United States)

    Hosseini Largani, Sekineh; Akbarzadeh Pasha, Mohammad

    2017-12-01

    In this research, MWCNT-ZnO hybrid nanomaterials were synthesized by a simple sol-gel process using Zn(CH3COO)2·2H2O and functionalized MWCNT with carboxyl(COOH) and hydroxyl(OH) groups. Three different mass ratios of MWCNT:ZnO = 3:1, 1:1 and 1:3 were examined. The prepared nanomaterials were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR). Successful growth of MWCNT-ZnO hybrids for both COOH and OH functional groups and all the three mass ratios were obtained. The ZnO nanoparticles attached on the surfaces of CNTs have rather spherical shapes and hexagonal crystal structure. By increasing the concentration of ZnO, the number and average size of ZnO nanoparticles decorated the body of CNTs in hybrid structures increase. By increasing the ZnO precursor, the distribution of ZnO nanoparticles that appeared on the surface of CNTs becomes more uniform. The SEM observation beside EDX analysis revealed that at the same concentration ratio the amount of ZnO loading on the surface of MWCNT-COOH is more than MWCNT-OH. Moreover, the average size of ZnO nanoparticles attached on the surface of COOH functionalized CNTs is relatively smaller than that of OH functionalized ones.

  14. An efficient method for the synthesis of photo catalytically active ZnO nanoparticles by a gel-combustion method for the photo-degradation of Caffeine

    Directory of Open Access Journals (Sweden)

    Rajesha Bedre Jagannatha

    2017-01-01

    Full Text Available In this study, Zinc oxide nanoparticles were synthesized by gel-combustion method using a novel bio-fuel tapioca starch pearls, derived from the tubers of Mannihot esculenta, to investigate the photocatalytic degradation of ccaffeine. The ZnO photocatalyst was characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, and UV-visible spectroscopy. X-ray diffractometry result for the ZnO nanoparticles exhibit normal crystalline phase features. All observed peaks can be indexed to the pure hexagonal wurtzite crystal structures. There are no other impurities in the diffraction peak. In addition, SEM measurement shows that most of the nanoparticles are spongy and spherical in shape and fairly mono dispersed. A significant degradation of the Caffeine was observed when the catalyst was added into the solution even without the UV light exposure. In addition, the photo degradation increaseds with the photocatalyst loading. Besides the photocatalyst loading, the effect of some parameters on the photo degradation efficiency such as initial concentration and pH were also studied.

  15. Synthesis of sol–gel silica particles in reverse micelles with mixed-solvent polar cores: tailoring nanoreactor structure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Bürglová, Kristýna; Hlaváč, Jan [Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry (Czech Republic); Bartlett, John R., E-mail: jbartlett@usc.edu.au [University of the Sunshine Coast, Faculty of Science, Health, Education and Engineering (Australia)

    2015-07-15

    In this paper, we describe a new approach for producing metal oxide nano- and microparticles via sol–gel processing in confined media (sodium bis(2-ethylhexyl)sulfosuccinate reverse micelles), in which the chemical and physical properties of the polar aqueous core of the reverse micelles are modulated by the inclusion of a second polar co-solvent. The co-solvents were selected for their capacity to solubilise compounds with low water solubility and included dimethylsulfoxide, dimethylformamide, ethylene glycol, n-propanol, dimethylacetamide and N-methylpyrrolidone. A broad range of processing conditions across the sodium bis(2-ethylhexyl)sulfosuccinate/cyclohexane/water phase diagram were identified that are suitable for preparing particles with dimensions <50 to >500 nm. In contrast, only a relatively narrow range of processing conditions were suitable for preparing such particles in the absence of the co-solvents, highlighting the role of the co-solvent in modulating the properties of the polar core of the reverse micelles. A mechanism is proposed that links the interactions between the various reactive sites on the polar head group of the surfactant and the co-solvent to the nucleation and growth of the particles.

  16. Synthesis of LaCoO{sub 3} nano-powders by aqueous gel-casting for intermediate temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Chia Siang; Zhang, Lan; Jiang, San Ping [School of Mechanical and Aerospace Engineering, Nanyang Technological University (Singapore); Zhang, Yu.Jun [Key Lab for Liquid Structure and Heredity of Ministry of Education, School of Materials Science and Engineering, Shandong University, Jinan (China)

    2008-04-15

    LaCoO{sub 3} (LC) perovskite powders for intermediate temperature solid oxide fuel cells (IT-SOFCs) are synthesized by a simple and cost-effective aqueous gel-casting technique using metal nitrates as raw materials. Effect of the ratio of organic precursors (acrylamide (AM) monomer and N,N'-Methylenebisacrylamide (MBAM) crosslinker) to metal nitrates (lanthanum nitrate, cobalt nitrate) and the ratio of AM to MBAM on the particle size are investigated in detail. TEM results indicate that the particle size of LC nano-powders is in the range of 31-60 nm and decreases with increasing ratio of organic precursor to metal nitrates but is not affected by the ratio of AM to MBAM. Preliminary results show that the nano-structured electrode approach based on wet impregnation is effective to combine the high electrocatalytic activity of LC nano-powders and the structural stability of La{sub 0.72}Sr{sub 0.18}MnO{sub 3} {sub -} {sub {delta}} (LSM) electrodes for the development of IT-SOFC cathodes. (author)

  17. Synthesis and characterization of organically modified silica gel with 4-amino-5-(4-pyridyl)-4h-1 ,2,4-triazole-3-thiol (APTT)

    International Nuclear Information System (INIS)

    Magossi, M.S.; Carmo, D.R. do

    2014-01-01

    This work object the preparation and characterization of a silica gel (SG) organically with a triazole compound, 4-amino-5-(4-pyridyl)-4H-1,2,4-triazole-3- thiol (APTT). The prepared organofunctionalized material (SGAPTT) was preliminarily characterized by spectroscopic techniques such as: Spectroscopy in the Region of Infrared (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy X-ray (EDX). The vibrational spectrum (FTIR) showed characteristic bands of the starting materials, such as bands at ∼ 1120cm"-"1 related to the asymmetric stretching Si-O-Si (νSi-O-Si) as well as the bands between 1350 and 1650 cm"-"1 assigned vibrations and deformations of the ring APTT. The SGAPTT material was tested as support for adsorption of cupric ions in aqueous solution, ethanol and 42% ethanol. The maximum amount of copper (II) adsorbed (Nf "m"a"x".) was 22.0 × 10"-"5 mol g"-"1, 31.4 × 10-5 mol g-1 and 47.17 × 10"-"5 mol g"-"1 to aqueous media, 42% ethanol and 99% ethanol respectively. (author)

  18. Sol-gel route of synthesis of nanoparticles of MgFe2O4 and XRD, FTIR and VSM study

    International Nuclear Information System (INIS)

    Pradeep, A.; Priyadharsini, P.; Chandrasekaran, G.

    2008-01-01

    Nanoparticles of MgFe 2 O 4 are synthesized using sol-gel autocombustion method. Structural studies are carried out using X-ray diffraction (XRD). The XRD pattern of MgFe 2 O 4 provides information about single-phase formation of spinel structure with cubic symmetry. The grain size and lattice constant are obtained using XRD data. The cation distribution is also proposed theoretically. The change in site preference of cations in nano-MgFe 2 O 4 is compared with its bulk counterpart. The structural morphology of the nanoparticles is studied using Scanning Electron Microscopy (SEM). Formation of spinel structure is conformed using Fourier transform infrared spectroscopy (FTIR), which also lends support for the cation distribution proposed using XRD data. The effect of nanoregime on parameters such as bond length, vibration frequency and force constant are discussed with the help of FTIR data. The M-H loop of MgFe 2 O 4 has been traced using the Vibrating Sample Magnetometer (VSM) and magnetic parameters such as saturation magnetization (M S ), coercivity (H C ) and retentivity (M R ) are obtained from VSM data

  19. Sol-gel synthesis of TiO2 nanoparticles and photocatalytic degradation of methyl orange in aqueous TiO2 suspensions

    International Nuclear Information System (INIS)

    Yang Huaming; Zhang Ke; Shi Rongrong; Li Xianwei; Dong Xiaodan; Yu Yongmei

    2006-01-01

    Anatase TiO 2 nanoparticles of about 16 nm in crystal size have been successfully synthesized via a sol-gel method. Thermal treatment of the precursor at 500-600 deg. C results in the formation of different TiO 2 phase compositions. The samples were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Effects of the pH value of the solution, H 2 O 2 addition, TiO 2 phase composition and recycled TiO 2 on the photocatalytic degradation of methyl orange (MeO) in TiO 2 suspensions under ultraviolet (UV) illumination were primarily investigated. The results indicate that a low pH value, proper amount of H 2 O 2 and pure anatase TiO 2 will facilitate the photocatalytic oxidation of the MeO solution. The photodegradation degree decreases with increasing the pH value of the solution and varies with different amounts of H 2 O 2 . Pure anatase TiO 2 shows better photocatalytic activity for MeO decolorization than biphase TiO 2 . The photocatalytic mechanism of the as-synthesized TiO 2 nanoparticles was discussed

  20. Gelatin Template Synthesis of Aluminum Oxide and/or Silicon Oxide Containing Micro/Mesopores Using the Proteic Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    Amanda Sayure Kasuya de Oliveira

    2017-01-01

    Full Text Available Aluminum oxide and/or silicon oxide-based supports were synthesized by proteic sol-gel method. The characterization was performed through the analysis of TG, XRD, FTIR, SEM, and N2 physisorption. The XRD diffractograms showed an amorphous material profile. TG results indicate the total liberation of the organic and inorganic material in the calcination temperature used, occurring in different mass loss range. This piece of information was reaffirmed by the FTIR spectra, which presented characteristic bands of gelatin structure before calcinations which disappear in the spectrum of the solid after calcinations, indicating the loss of organic matter from gelatin after heat treatment. The spectra exhibited M-O stretching vibration at low wavenumbers after calcinations related to metal oxides. The acquired images by SEM suggest the obtaining of a highly porous material with very different characteristics depending on the composition of the support. The N2 isotherms indicate the presence of a micro/mesoporous oxide with interesting textural properties, particularly for the supports containing aluminum and silicon oxide. The ethanol dehydration results showed greater selectivity to diethyl ether compared to ethylene. From the reaction data, the following order of acid strength was obtained: 2Si-Al > Si-2Al > Si-Al > Al, which is related to the Si-Al ratio.

  1. Synthesis and Characterization of SiO2@Y2MoO6:Eu3+ Core-Shell Structured Spherical Phosphors by Sol-Gel Process.

    Science.gov (United States)

    Li, G Z; Liu, F H; Chu, Z S; Wu, D M; Yang, L B; Li, J L; Wang, M N; Wang, Z L

    2016-04-01

    SiO2@Y2MoO6:Eu3+ core-shell phosphors were prepared by the sol-gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), photoluminescence (PL) spectra as well as kinetic decays were used to characterize the resulting SiO2@Y2MoO6:Eu3+ core-shell phosphors. The XRD results demonstrated that the Y2MoO6:Eu3+ layers on the SiO2 spheres crystallized after being annealed at 700 °C and the crystallinity increased with raising the annealing temperature. The obtained core-shell phosphors have spherical shape with narrow size distribution (average size ca. 640 nm), non-agglomeration, and smooth surface. The thickness of the Y2MoO6:Eu3+ shells on the SiO2 cores could be easily tailored by varying the number of deposition cycles (70 nm for four deposition cycles). The Eul+ shows a strong PL emission (dominated by 5D0-7F2 red emission at 614 nm) under the excitation of 347 nm UV light. The PL intensity of Eu3+ increases with increasing the annealing temperature and the number of coating cycles.

  2. Characterization of particulate sol-gel synthesis of LiNi0.8Co0.2O2 via maleic acid assistance with different solvents

    International Nuclear Information System (INIS)

    Zhong, Y.D.; Zhao, X.B.; Cao, G.S.; Tu, J.P.; Zhu, T.J.

    2006-01-01

    Particulate sol-gel LiNi 0.8 Co 0.2 O 2 has been synthesized by a maleic-acid-assisted process using de-ionized water or ethanol as the solvent. A comparison of the effect on these two different solvents was made on the basis of thermal studies, Fourier transform infrared spectroscopy, X-ray diffraction analysis, chemical diffusion coefficients measurement, and electrochemical cyclability tests. An esterification reaction occurred on the xerogel prepared with ethanol as solvent, reducing Ni and Co from their nitrate salts. LiNi 0.8 Co 0.2 O 2 grew at the expense of Li 2 CO 3 , NiO, and CoO during calcination. Better results of capacity and cyclability were obtained in a DI-water-solvent sample associated with a larger interslab thickness between O-Li-O and lower Ni occupancy on the Li site. The activation energy for the calcinations of DI-water-solvent sample is one-half of that of the ethanol-solvent one, which could be the reason for its better properties. Chemical diffusion coefficients of Li + ion are of the same order 10 -10 cm 2 /s, is not affected by the solvents used and/or the temperature raise to 55 deg. C

  3. Synthesis, characterization and humidity sensing properties of sol-gel derived novel nanomaterials of LaFe1-xSrxO3-δ

    International Nuclear Information System (INIS)

    Mary Teresita, V.; Avila Josephine, B.; Jeseentharani, V.; Jeyaraj, B.; Arul Antony, S.

    2011-01-01

    LaFe 1-x Sr x O 3-δ (x = 0, 0.2, 0.4, 0.6, 0.8, 1) were prepared by sol-gel method. The compounds were sintered at 700 deg C for 5 h. Then the compounds were characterized by X-ray diffraction, scanning electron microscopy (SEM) and BET analysis. The dc electrical resistance in different relative humidity (RH%) for the samples in the form of pellets was determined by two-probe method. The change in surface conductivity as a function of applied field was measured using picoammeter (Keithley-6485). The sensitivity factor S f was calculated by the ratio of resistances, R 5% /R 98% , where R 5% and R 98% are the dc resistances 5 and 98% RH, respectively. Response and recovery times were measured. Among various composites, the LaSrO 3δ (x = 1) composite possessed the highest humidity response with S f = 3290, while the LaFe 0.8 Sr 0.2 O 3δ (x = 0.2) possessed low sensitivity factors of 0.1. (author)

  4. Effect of polyvinyl alcohol content and after synthesis neutralization on structure, mechanical properties and cytotoxicity of sol-gel derived hybrid foams

    Directory of Open Access Journals (Sweden)

    Agda Aline Rocha de Oliveira

    2009-06-01

    Full Text Available Bioactive glass/polymer hybrids are promising materials for biomedical applications because they combine the bioactivity of these glasses with the flexibility of polymers. In this work it was evaluated the effect of increasing the PVA content of the on structural characteristics and mechanical properties of hybrid. The hybrids were prepared with 70 wt. (% SiO2-30 wt. (% CaO and PVA fractions of 20 to 60 wt. (% by the sol-gel method. The structural and mechanical characterization was done by FTIR, SEM and compression tests. To reduce the acidic character of the hybrids due to the catalysts added, different neutralization solutions were tested. The calcium acetate alcoholic solution was the best neutralizing method, resulting in foams with final pH of about 7.0 and small sample contraction. The foams presented porosity of 60-85 wt. (% and pore diameters of 100-500 μm with interconnected structure. An increase of PVA fraction in the hybrids improved their mechanical properties. The scaffolds produced provided a good environment for the adhesion and proliferation of osteoblasts.

  5. Key step in the synthesis of ultrafine strontium ferrite powders (SrFe{sub 12}O{sub 19}) by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Nga, Tran Thi Viet, E-mail: vietnga@itims.edu.vn; Duong, Nguyen Phuc; Loan, To Thanh; Hien, Than Duc

    2014-10-15

    Highlights: • The variations in the properties of SrM powders, resulting from different parameter. • Appropriate pH, R{sub M} ratio, and T{sub ca} were adjusted to producing a single-phase nanosized SrM. • The average particle sizes were evenly distributed in the range of 80° nm to 100° nm. - Abstract: Submicron strontium hexaferrite (SrFe{sub 12}O{sub 19}) particles were synthesized using the sol–gel route. Magnetic properties and structure of strontium ferrite powders were studied at various ranges of calcination temperature (T{sub ca}) (750–900 °C), calcination time (3 min–2 h), Fe/Sr molar ratios (R{sub M}) (10.5–12), and pH (1–8). The resultant particles were investigated using X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometer. At 750 °C, the Sr–M phase could be obtained for 3 min in air. However, single-phase Sr–M, which had stabilized magnetic properties, was obtained at T{sub ca} of 850 °C for 2 h. In solutions at pH 1, magnetic properties of the obtained sample at R{sub M} = 10.5 were found to be optimal with maximum saturation magnetization of 56 emu/g and intrinsic coercive force of 6.7 kOe.

  6. Sol-Gel Synthesis and in Situ X-ray Diffraction Study of Li3Nd3W2O12 as a Lithium Container.

    Science.gov (United States)

    Luo, Minghe; Yu, Haoxiang; Cheng, Xing; Ye, Wuquan; Zhu, Haojie; Liu, Tingting; Peng, Na; Shui, Miao; Shu, Jie

    2018-04-18

    In this work, garnet-framework Li 3 Nd 3 W 2 O 12 as a novel insertion-type anode material has been prepared via a facile sol-gel method and examined as a lithium container for lithium ion batteries (LIBs). Li 3 Nd 3 W 2 O 12 shows a charge capacity of 225 mA h g -1 at 50 mA g -1 , and with the current density increasing up to 500 mA g -1 , the charge capacity can still be maintained at 186 mA h g -1 . After cycling at 500 mA g -1 for 500 cycles, Li 3 Nd 3 W 2 O 12 retains about 85% of its first charge capacity changed from 190.2 to 161 mA h g -1 . Furthermore, in situ X-ray diffraction technique is adopted for the understanding of the insertion/extraction mechanism of Li 3 Nd 3 W 2 O 12 . The full-cell configuration LiFePO 4 /Li 3 Nd 3 W 2 O 12 is also assembled to evaluate the potential of Li 3 Nd 3 W 2 O 12 for practical application. These results show that Li 3 Nd 3 W 2 O 12 is such a promising anode material for LIBs with excellent electrochemical performance and stable structure.

  7. Sol-gel route to synthesis of microporous ceramic membranes: Thermal stability of TiO2-ZrO2 mixed oxides

    International Nuclear Information System (INIS)

    Qunyin Xu; Anderson, M.A.

    1993-01-01

    In this paper concerning the synthesis of microporous ceramic membranes, the authors focus on the preparation and thermal stability of unsupported microporous TiO 2 -ZrO 2 mixed-oxide membranes. It has been observed that, by adding up to 20% ZrO 2 into TiO 2 or up to 10% TiO 2 into ZrO 2 , these microporous membranes display improved thermal stability. They can be fired up to 500 C for 0.5 h without closing micropores. However, membranes containing almost equal percentages of each component have lost microporous features and have low surface areas and low porosities. A phase diagram of a two-component TiO 2 -ZrO 2 mixed-oxide membrane has been prepared based on DTA and X-ray diffraction data in order to better understand the microstructure changes upon firing

  8. Synthesis and characterization of erbium-doped SiO2 nanoparticles fabricated by using reverse micelle and sol-gel processing

    International Nuclear Information System (INIS)

    Park, Hoyyul; Bae, Dongsik

    2012-01-01

    Erbium-doped SiO 2 nanoparticles have been synthesized using a reverse micelle technique combined with metal-alkoxide hydrolysis and condensation. The sizes and the morphologies of the erbium-doped SiO 2 nanoparticles could be changed by varying the molar ratio of water to surfactant. The sizes and the morphologies of the erbium-doped SiO 2 nanoparticles were examined by using a transmission electron microscope. The average size of synthesized erbium-doped SiO 2 nanoparticles was approximately 20 - 25 nm and that of the erbium particles was 3 - 5 nm. The effects of the synthesis parameters, such as the molar ratio of water to surfactant, are discussed.

  9. Thermal synthesis of oxide molecular sieve and Mn (K-OMS-2) from K-birnessite obtained from Sol-gel method

    International Nuclear Information System (INIS)

    Rezende, D.S.; Figueira, B.A.M.; Moraes, M.C. de; Silva, L.N. da; Mercury, J.M.R.; Figueiredo, G.P. de

    2016-01-01

    This study presents the thermal synthesis of molecular sieve with K-OMS2 structure from K-birnessite tunneling process, one Mn oxide with structure in layer. According X-Ray diffraction data it was possible to monitoring the conversion of the layered structure around 550 deg C for (K-OMS-2) tunnel with tetragonal system and I2/m space group. The FTIR main spectrum bands of K-OMS-2 was observed in 700, 525 e 470 cm-1 region and are related to elongation Mn 3+ -O e Mn 4+ -O in the tunnel structure. The product morphology identified by Scanning Electron Microscopy it was verified as pseudo tetragonal, reflecting externally the crystallographic system of cryptomelane structure. The results reveal one simple route for the Mn oxide molecular sieve with K-OMS-2 structure

  10. Studies on the flammability of polypropylene/ammonium polyphosphate and montmorillonite by using the cone calorimeter test

    Directory of Open Access Journals (Sweden)

    Hanna A.A.

    2018-03-01

    Full Text Available Fire performance of polypropylene (PP containing different percentages of ammonium polyphosphate (APP with montmorillonite (Mt or treated montmorillonite (MtT was carried out by using the cone calorimeter test (CCT. Different samples from ammonium polyphosphate and montmorillonite were mixed with 90% polypropylene. The characterization of the prepared samples indicates that there is incorporation between the components of the samples. Heat release rate (HRR, peak heat release rate (PHRR, average heat release rate (Av-HRR, and time to ignition (TTI of the samples were obtained from the cone calorimeter test. Also, the fire performance index (FPI and the fire growth rate (FIGRA were calculated. The interpretation of the curves and the parameters results from the cone calorimeter test which indicates that the addition of montmorillonite to APP increases its action as a flame retardant for PP. Moreover, the samples contain acid treatment montmorillonite showed an increase in the efficiency of ammonium polyphosphate when used. This result may be due to an increase in the SiO2 content by acid treatment.

  11. Synthesis and characterization of NaCo(1-x)MnxO2 solid electrolyte using sol-gel method: the effect of milling speed variations

    Science.gov (United States)

    Suyati, L.; Widyayanti, O. A.; Qushoyyi, M.; Darmawan, A.; Nuryanto, R.

    2018-04-01

    Battery is a device that converts chemical energy into electrical energy through electrochemical process. Further research on the synthesis of cathode of Na-ion battery that has good conductivity to maximize the battery performance needs to be conducted. One of the production steps of the NaCo(1-x)NaCo cathode synthesis in the Na-Ion battery was a ball-milling process, in which by the ball-milling process, the crystal size of NaCo(1-x)MnxO2 cathode can be minimized. The purpose of this study was to determine the effect of variation of ball-milling speed to the characteristics of resulting product including the oxide types composing NaCo(1-x)MnxO2 cathode, surface morphology, and conductivity. The main ingredients used were sodium acetate, manganese acetate, cobalt acetate with molar ratio of 0.7: 0.66: 0.22, respectively and citric acid as chelating agent with the M/CA ratio of 1: 1. The variations of milling speed were 0, 300, 400, 500, 600 and 700 rpm. Characterization of the product was conducted using XRD, SEM-EDS, and conductivity meter (LCR-meter). The result showed that a solid electrolyte of NaCo(1-x)MnxO2 consisting of NaMnO2, NaO2, CoO, Co2O3, MnO2 components was successfully synthesized. The observation on the milling speed at 400 rpm showed that the solid electrolyte produced had the highest conductivity i.e. 4.08 x 10-6 Scm-1 with a homogeneous surface morphology and had a spinel formula NaCo0,65Mn0,35O2.

  12. Removing water from gels

    International Nuclear Information System (INIS)

    Lane, E.S.; Winter, J.A.

    1982-01-01

    Water is removed from a gel material by contacting the gel material with an organic liquid and contacting the organic liquid with a gas such that water is taken up by the gas. The invention, in one embodiment, may be used to dry gel materials whilst maintaining an open porous network therein. In one example, the invention is applied to gel precipitated spheres containing uranium and plutonium. (author)

  13. Influence of synthesis conditions on microstructure and phase transformations of annealed Sr2FeMoO6−x nanopowders formed by the citrate–gel method

    Directory of Open Access Journals (Sweden)

    Marta Yarmolich

    2016-08-01

    Full Text Available The sequence of phase transformations during Sr2FeMoO6−x crystallization by the citrate–gel method was studied for powders synthesized with initial reagent solutions with pH values of 4, 6 and 9. Scanning electron microscopy revealed that the as-produced and annealed powders had the largest Sr2FeMoO6−x agglomerates with diameters in the range of 0.7–1.2 µm. The average grain size of the powders in the dispersion grows from 250 to 550 nm with increasing pH value. The X-ray diffraction analysis of the powders annealed at different temperatures between 770 and 1270 K showed that the composition of the initially formed Sr2FeMoO6−x changes and the molybdenum content increases with further heating. This leads to a change in the Sr2FeMoO6−x crystal lattice parameters and a contraction of the cell volume. An optimized synthesis procedure based on an initial solution of pH 4 allowed a single-phase Sr2FeMoO6−x compound to be obtained with a grain size in the range of 50–120 nm and a superstructural ordering of iron and molybdenum cations of 88%.

  14. Optimization and complexing agent-assisted synthesis of green SrAl{sub 2}O{sub 4}: Eu{sup 2+}, Dy{sup 3+} phosphors through sol–gel process

    Energy Technology Data Exchange (ETDEWEB)

    Du, Hongli; Shan, Wenfei; Wang, Liying; Xu, De; Yin, Hao [School of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Chen, Yanwen [Hunan Labour Protection Institute of Nonferrous Metals, Changsha 410014 (China); Guo, Dongcai, E-mail: dcguo2001@hnu.edu.cn [School of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Hunan Provincial Key Laboratory for Cost-effective Utilization of Fossil Fuel Aimed at Reducing Carbon-dioxide Emissions, Changsha 410082 (China)

    2016-08-15

    A novel Eu{sup 2+}–Dy{sup 3+}co-doped strontium aluminate green long-lasting phosphors were synthesized via conventional sol–gel method with citric acid and polyethylene glycol used as chelating agent, respectively. Orthogonal experiments were employed to optimize the main synthesis conditions and obtain the optimum technological parameters. Subsequently, the crystal structure, morphology, decay curve and luminescence property of the composites were characterized. X-ray diffraction (XRD) showed that the samples were composed of single-phase SrAl{sub 2}O{sub 4}. Scanning electron microscopy (SEM) revealed that the resultant nanoparticles performed graininess with a size of 100 nm around. The excitation and emission spectra indicated that, excitation broadband chiefly lay in the ultraviolet range, and nanocrystalline particles emitted strong light at 510 nm, which corresponding to the typical characteristic 5d–4f transition of Eu{sup 2+} ion excited at around 360 nm. The long afterglow photoluminescence of nanoparticles SrAl{sub 2}O{sub 4}: Eu{sup 2+}, Dy{sup 3+} (denoted as SAO: ED) was observed in the dark with the naked eye even after the removal of the excitation light. The luminescence properties suggested that SAO: ED phosphor may be regarded as a potential green phosphor candidate for near-UV and blue light-emitting diodes (LEDs).

  15. Sol-gel synthesis, characterization and optical properties of mercury-doped TiO{sub 2} thin films deposited on ITO glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Mechiakh, R., E-mail: raouf_mechiakh@yahoo.fr [Departement de Medecine, Faculte de Medecine, Universite Hadj Lakhdar, Batna (Algeria); Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP 95, Hammam-Lif 2050 (Tunisia); Ben Sedrine, N.; Chtourou, R. [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP 95, Hammam-Lif 2050 (Tunisia)

    2011-08-15

    The Hg-doped and undoped nano-crystalline TiO{sub 2} films on ITO glass substrates surface and polycrystalline powders were prepared by sol-gel dip coating technique. The crystal structure and surface morphology of TiO{sub 2} were characterized by means of X-ray diffractometer (XRD), atomic force microscope (AFM), spectrophotometer, Fourier-transform infrared (FTIR), and spectroscopic ellipsometry (SE). The results indicated that the powder of TiO{sub 2}, doped with 5% Hg in room temperature was only composed of the anatase phase whereas in the undoped powder exhibits an amorphous phase were present. After heat treatments of thin films, titanium oxide starts to crystallize at the annealing temperature 400 {sup o}C. The average crystallite size of the undoped TiO{sub 2} films was about 8.17 nm and was increased with Hg-doping in the TiO{sub 2} films. Moreover, the grains distributed more uniform and the surface roughness was greater in the Hg-doped TiO{sub 2} films than in the undoped one. Refractive index and porosity were calculated from the measured transmittance spectrum. The values of the index of refraction are in the range (1.95-2.49) and the porosity is in the range (47-2.8). The coefficient of transmission varies from 60 to 90%. SE study was used to determine the annealing temperature effect on the optical properties in the wavelength range from 0.25 to 2 {mu}m and the optical gap of the Hg-doped TiO{sub 2} thin films.

  16. Sol-gel synthesis and in vitro bioactivity of copper and zinc-doped silicate bioactive glasses and glass-ceramics.

    Science.gov (United States)

    Bejarano, Julian; Caviedes, Pablo; Palza, Humberto

    2015-03-11

    Metal doping of bioactive glasses based on ternary 60SiO2-36CaO-4P2O5 (58S) and quaternary 60SiO2-25CaO-11Na2O-4P2O5 (NaBG) mol% compositions synthesized using a sol-gel process was analyzed. In particular, the effect of incorporating 1, 5 and 10 mol% of CuO and ZnO (replacing equivalent quantities of CaO) on the texture, in vitro bioactivity, and cytocompatibility of these materials was evaluated. Our results showed that the addition of metal ions can modulate the textural property of the matrix and its crystal structure. Regarding the bioactivity, after soaking in simulated body fluid (SBF) undoped 58S and NaBG glasses developed an apatite surface layer that was reduced in the doped glasses depending on the type of metal and its concentration with Zn displaying the largest inhibitions. Both the ion release from samples and the ion adsorption from the medium depended on the type of matrix with 58S glasses showing the highest values. Pure NaBG glass was more cytocompatible to osteoblast-like cells (SaOS-2) than pure 58S glass as tested by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. The incorporation of metal ions decreased the cytocompatibility of the glasses depending on their concentration and on the glass matrix doped. Our results show that by changing the glass composition and by adding Cu or Zn, bioactive materials with different textures, bioactivity and cytocompatibility can be synthesized.

  17. Facile one step synthesis of novel TiO2 nanocoral by sol-gel method using Aloe vera plant extract

    Science.gov (United States)

    Venkatesh, K. S.; Krishnamoorthi, S. R.; Palani, N. S.; Thirumal, V.; Jose, Sujin P.; Wang, Fu-Ming; Ilangovan, R.

    2015-05-01

    Titanium oxide (TiO2) nanoparticles (NPs) were synthesized by sol gel method using Aloe vera plant extract as a biological capping agent and a cauliflower-nanocoral morphology was observed in this technique. The assynthesized TiO2 nanopowder was calcined at a range of temperatures (300-600 °C) for 1 h. The influence of A. vera plant extract on the thermal, structural and morphological properties of TiO2 nanopowder was evaluated. Thermogravimetric analysis/differential thermal analysis was employed to study the thermal properties of the assynthesized TiO2 nanopowder. The crystallinity, phase transformation and the crystallite size of the calcined samples were studied by X-ray diffraction technique. XRD result confirmed the presence of TiO2 with anatase phase. FT Raman spectra showed the Raman active modes pertaining to the TiO2 anatase phase and Raman band shift was also observed with respect to particle size variation. The different functional group vibrations of as dried pure A. vera plant extract were compared with the mixture of TiO2 and A. vera plant extract by FT-IR analysis. The scanning electron microscopy images apparently showed the formation of spherical shaped NPs and also it demonstrated the effect of A. vera plant extract on the reduction of particles size. The surface area of the TiO2 NPs was measured through Brunauer-Emmett-Teller analysis. Transmission electron microscopy images ascertained that the spherical shaped TiO2 NPs were formed with cauliflower-nanocoral morphology decorated with nanopolyps with the size range between 15 and 30 nm.

  18. Polymer gels and networks

    National Research Council Canada - National Science Library

    Osada, Yoshihito; Khokhlov, A. R

    2002-01-01

    ... or magnetic field, etc.). It was realized that not only can polymer gels absorb and hold a considerable volume of liquids, but they can also be forced to expel the absorbed liquid in a controlled manner. Of particular interest are hydrogels, i.e., polymer gels, which swell extensively in water. The most common hydrogels are polyelectrolyte gels: ...

  19. Experimental Plan: 300 Area Treatability Test: In Situ Treatment of the Vadose Zone and Smear Zone Uranium Contamination by Polyphosphate Infiltration

    International Nuclear Information System (INIS)

    Wellman, Dawn M.; Pierce, Eric M.; Oostrom, Mart; Fruchter, Jonathan S.

    2007-01-01

    The overall objectives of the treatability test is to evaluate and optimize polyphosphate remediation technology for infiltration either from ground surface, or some depth of excavation, providing direct stabilization of uranium within the deep vadose and capillary fringe above the 300 Area aquifer. Expected result from this experimental plan is a data package that includes: (1) quantification of the retardation of polyphosphate, (2) the rate of degradation and the retardation of degradation products as a function of water content, (3) an understanding of the mechanism of autunite formation via the reaction of solid phase calcite-bound uranium and aqueous polyphosphate remediation technology, (4) an understanding of the transformation mechanism, identity of secondary phases, and the kinetics of the reaction between uranyl-carbonate and silicate minerals with the polyphosphate remedy under solubility-limiting conditions, (5) quantification of the extent and rate of uranium released and immobilized based on the infiltration rate of the polyphosphate remedy and the effect of and periodic wet-dry cycling on the efficacy of polyphosphate remediation for uranium in the vadose zone and capillary fringe, and (6) quantification of reliable equilibrium solubility values for autunite under hydraulically unsaturated conditions allowing accurate prediction of the long-term stability of autunite. Moreover, results of intermediate scale testing will quantify the transport of polyphosphate and degradation products, and yield degradation rates, at a scale that is bridging the gap between the small-scale UFA studies and the field scale. These results will be used to test and verify a site-specific, variable saturation, reactive transport model and to aid in the design of a pilot-scale field test of this technology. In particular, the infiltration approach and monitoring strategy of the pilot test would be primarily based on results from intermediate-scale testing. Results from this

  20. Applications of gel dosimetry

    International Nuclear Information System (INIS)

    Ibbott, Geoffrey S

    2004-01-01

    Gel dosimetry has been examined as a clinical dosimeter since the 1950s. During the last two decades, however, a rapid increase in the number of investigators has been seen, and the body of knowledge regarding gel dosimetry has expanded considerably. Gel dosimetry is still considered a research project, and the introduction of this tool into clinical use is proceeding slowly. This paper will review the characteristics of gel dosimetry that make it desirable for clinical use, the postulated and demonstrated applications of gel dosimetry, and some complications, set-backs, and failures that have contributed to the slow introduction into routine clinical use

  1. Carbon as amorphous shell and interstitial dopant in mesoporous rutile TiO2: Bio-template assisted sol-gel synthesis and photocatalytic activity

    International Nuclear Information System (INIS)

    Mohamed Azuwa Mohamad; Wan Norharyati Wan Salleh; Juhana Jaafar; Mohamad Saufi Rosmi; Zul Adlan Mohd Hir; Muhazri Abd Mutalib; Ahmad Fauzi Ismail; Tanemura, Masaki

    2017-01-01

    Highlights: • RCM as bio-template and in-situ carbon shell and interstitial carbon doping. • Photo-sensitizers by carbonaceous layer grafted onto the surface of TiO 2 . • Visible light response could be tailored depending on the annealing temperature. • Photocatalytic properties and charge carrier transfer mechanism was proposed. - Abstract: Regenerated cellulose membrane was used as bio-template nanoreactor for the formation of rutile TiO 2 mesoporous, as well as in-situ carbon dopant in acidified sol-gel system. The effects of calcination temperature on the physicochemical characteristic of core-shell nanostructured of bio-templated C-doped mesoporous TiO 2 are highlighted in this study. By varying the calcination temperature, the thickness of the carbon shell coating on TiO 2 , crystallinity, surface area, and optical properties could be tuned as confirmed by HRTEM, nitrogen adsorption/desorption measurement, XRD and UV–vis-NIR spectroscopy. The results suggested that increment in the calcination temperature would lead to the band gap narrowing from 2.95 to 2.80 eV and the thickness of carbon shell increased from 0.40 to 1.20 nm. The x-ray photoelectron spectroscopy showed that the visible light absorption capability was mainly due to the incorporation of carbon dopant at interstitial position in the TiO 2 to form O−Ti−C or Ti−O−C bond. In addition, the formation of the carbon core-shell nanostructured was due to carbonaceous layer grafted onto the surface of TiO 2 via Ti−O−C and Ti−OCO bonds. The result indicated that bio-templated C-doped core-shell mesoporous TiO 2 prepared at 300 °C exhibited the highest photocatalytic activity. It is worthy to note that, the calcination temperature provided a huge impact towards improving the physicochemical and photocatalytic properties of the prepared bio-templated C-doped core-shell mesoporous TiO 2 .

  2. Carbon as amorphous shell and interstitial dopant in mesoporous rutile TiO{sub 2}: Bio-template assisted sol-gel synthesis and photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed Azuwa Mohamad [Advanced Membrane Technology Research Centre, Universiti Teknologi Malaysia, 81310, Skudai, Johor Bahru (Malaysia); Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, Skudai, Johor Bahru (Malaysia); Wan Norharyati Wan Salleh, E-mail: hayati@petroleum.utm.my [Advanced Membrane Technology Research Centre, Universiti Teknologi Malaysia, 81310, Skudai, Johor Bahru (Malaysia); Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, Skudai, Johor Bahru (Malaysia); Juhana Jaafar, E-mail: juhana@petroleum.utm.my [Advanced Membrane Technology Research Centre, Universiti Teknologi Malaysia, 81310, Skudai, Johor Bahru (Malaysia); Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, Skudai, Johor Bahru (Malaysia); Mohamad Saufi Rosmi [Department of Chemistry, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, 35900, Tanjung Malim, Perak (Malaysia); Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Zul Adlan Mohd Hir [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Muhazri Abd Mutalib; Ahmad Fauzi Ismail [Advanced Membrane Technology Research Centre, Universiti Teknologi Malaysia, 81310, Skudai, Johor Bahru (Malaysia); Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, Skudai, Johor Bahru (Malaysia); Tanemura, Masaki [Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

    2017-01-30

    Highlights: • RCM as bio-template and in-situ carbon shell and interstitial carbon doping. • Photo-sensitizers by carbonaceous layer grafted onto the surface of TiO{sub 2}. • Visible light response could be tailored depending on the annealing temperature. • Photocatalytic properties and charge carrier transfer mechanism was proposed. - Abstract: Regenerated cellulose membrane was used as bio-template nanoreactor for the formation of rutile TiO{sub 2} mesoporous, as well as in-situ carbon dopant in acidified sol-gel system. The effects of calcination temperature on the physicochemical characteristic of core-shell nanostructured of bio-templated C-doped mesoporous TiO{sub 2} are highlighted in this study. By varying the calcination temperature, the thickness of the carbon shell coating on TiO{sub 2}, crystallinity, surface area, and optical properties could be tuned as confirmed by HRTEM, nitrogen adsorption/desorption measurement, XRD and UV–vis-NIR spectroscopy. The results suggested that increment in the calcination temperature would lead to the band gap narrowing from 2.95 to 2.80 eV and the thickness of carbon shell increased from 0.40 to 1.20 nm. The x-ray photoelectron spectroscopy showed that the visible light absorption capability was mainly due to the incorporation of carbon dopant at interstitial position in the TiO{sub 2} to form O−Ti−C or Ti−O−C bond. In addition, the formation of the carbon core-shell nanostructured was due to carbonaceous layer grafted onto the surface of TiO{sub 2} via Ti−O−C and Ti−OCO bonds. The result indicated that bio-templated C-doped core-shell mesoporous TiO{sub 2} prepared at 300 °C exhibited the highest photocatalytic activity. It is worthy to note that, the calcination temperature provided a huge impact towards improving the physicochemical and photocatalytic properties of the prepared bio-templated C-doped core-shell mesoporous TiO{sub 2}.

  3. Synthesis of nanocrystalline NiO/ZnO heterostructured composite powders by sol-gel auto combustion method and their characterizations

    Science.gov (United States)

    Tangcharoen, Thanit; Klysubun, Wantana; Kongmark, Chanapa

    2018-03-01

    Nanocrystalline NiO/ZnO heterostructured composite powders were prepared by the sol-gel auto combustion method, based on nickel and zinc nitrate precursors and using diethanolamine (DEA) as novel fuel. The composition of different NiO and ZnO ratios, ranging from 100/0, 95/5, 90/10, 80/20, 60/40, 50/50, 40/60, 20/80, 10/90, 5/95 to 0/100, were studied. The structural, chemical bonding, morphological, optical, and fluorescence properties including the local atomic structure of each calcined sample were systematically investigated by means of X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV-visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence (PL) spectroscopy, and synchrotron X-ray absorption spectroscopy (XAS), respectively. For the ZnO concentration below 20%, both XRD and Raman spectroscopy results revealed only the NiO phase. This conformed to the observation of Zn K-edge and Ni K-edge X-ray absorption near edge structure (XANES). The Zn ions found in the samples of low ZnO concentration exhibited six-fold coordination with oxygen atoms rather than the four-fold coordination found in the wurtzite (WZ) structure of ZnO. In contrast, the Ni ions which are found in the samples of low NiO concentration (≤10%) are coordinated both tetrahedrally and octahedrally by four or six oxygen atoms, respectively, rather than the six-fold coordination which is usually observed for Ni ions in the rock salt (RS) form of NiO. All analytical results obtained from experimental XANES spectra were verified by the theoretical calculation of absorption spectra using the FEFF9.7 code. The UV-DRS results showed that there was an increase in the reflectance efficiency for both infrared and visible light conditions as the content of ZnO increases; meanwhile, the values for the energy gap (Eg) of all composite samples were higher than that of pure NiO and ZnO. In addition, the PL spectra revealed major blue emission bands observed at 490

  4. Synthesis by sol-gel and characterization of catalysts Ag/Al2O3- CeO2 for the elimination of nitric oxide

    International Nuclear Information System (INIS)

    Zayas R, M.L.

    2005-01-01

    The environmental pollution is one from the big problems to solve at the present time, because the quality of the alive beings life is affected. For such reason, more clean and economic technologies are required, that it conduces to develop new catalytic alternatives to diminish the nitrogen oxides that due to its chemical processes in the environment contribute considerably in the air pollution. The main objective of the present work, is the preparation and characterization of catalytic materials with base of silver supported in simple and mixed aluminium oxides (Al 2 O 3 ) and Cerium oxide (CeO 2 ), and its catalytic evaluation that through of the reduction of nitric oxide (NO) using hydrogen (H 2 ) as reducer agent. It was synthesized alumina (Al 2 O 3 ) and Cerium oxide (CeO 2 ) and mixed oxides (Al 2 O 3 - CeO 2 ), by the sol-gel method and the cerium oxide (CeO 2 ) by precipitation of the cerium nitrate (III) hexa hydrated. The oxides were stabilized thermally at 900 C by 5 hr. The catalysts were prepared by impregnation using silver nitrate (AgNO 3 ), the nominal concentration of Ag was of 5% in weight. The catalysts were reduced at 400 C by 2 hr, in hydrogen flow of 60 cc/min. The characterization of the catalytic materials was carried out through different techniques as: nitrogen adsorption to determine the surface area BET, scanning electron microscopy (SEM) to observe the final morphology of the catalysts, X-ray diffraction (XRD) to identify the crystalline phases of the catalytic materials, Infrared spectroscopy (DRIFT) to know the structural characterization of the catalysts, reduction to programmed temperature (TPR) to evidence the interaction metal-support. The catalytic properties of the catalysts were evaluated in the model reaction NO + H 2 , to determine the activity and selectivity. The results indicate that the preparation technique, the precursors and the thermal treatments that underwent these materials influence in the catalyst and by

  5. Transport Phenomena in Gel

    Directory of Open Access Journals (Sweden)

    Masayuki Tokita

    2016-05-01

    Full Text Available Gel becomes an important class of soft materials since it can be seen in a wide variety of the chemical and the biological systems. The unique properties of gel arise from the structure, namely, the three-dimensional polymer network that is swollen by a huge amount of solvent. Despite the small volume fraction of the polymer network, which is usually only a few percent or less, gel shows the typical properties that belong to solids such as the elasticity. Gel is, therefore, regarded as a dilute solid because its elasticity is much smaller than that of typical solids. Because of the diluted structure, small molecules can pass along the open space of the polymer network. In addition to the viscous resistance of gel fluid, however, the substance experiences resistance due to the polymer network of gel during the transport process. It is, therefore, of importance to study the diffusion of the small molecules in gel as well as the flow of gel fluid itself through the polymer network of gel. It may be natural to assume that the effects of the resistance due to the polymer network of gel depends strongly on the network structure. Therefore, detailed study on the transport processes in and through gel may open a new insight into the relationship between the structure and the transport properties of gel. The two typical transport processes in and through gel, that is, the diffusion of small molecules due to the thermal fluctuations and the flow of gel fluid that is caused by the mechanical pressure gradient will be reviewed.

  6. Synthesis, characterization, temperature dependent electrical and magnetic properties of Ca{sub 3}Co{sub 4}O{sub 9} by a starch assisted sol–gel combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Agilandeswari, K.; Ruban Kumar, A., E-mail: arubankumar@vit.ac.in

    2014-09-01

    In this present work we discussed the synthesis of pure Ca{sub 3}Co{sub 4}O{sub 9} ceramic powder by a starch assisted sol–gel combustion method. The products were characterized by powder X-ray diffraction (XRD), thermogravimetric and differential thermal analyses (TGA–DTA), Fourier transformation infrared spectroscopy (FTIR), scanning electron microscope (SEM) and UV–visible diffuse reflectance spectroscopy (DRS). X-ray diffraction pattern confirmed the formation of single phase Ca{sub 3}Co{sub 4}O{sub 9} at a sintering temperature of 1073 K, and it is also confirmed in the thermal analysis. SEM images indicate the presence of diffused microporous sphere like morphology and the grain sizes are in the range of 150–300 nm. Optical properties of Ca{sub 3}Co{sub 4}O{sub 9} ceramic show a band gap at an energy level of 2.10 eV. A maximum electrical resistivity of 0.002 mΩ cm was exhibited by Ca{sub 3}Co{sub 4}O{sub 9} that was decreased to 0.0012 mΩ cm, when the temperature increased from 300 K to 473 K. Dielectric studies were conducted at various temperatures from room temperature to 673 K and the results indicate that the space charge polarization contributes to the conduction mechanism. It also shows that the dielectric relaxation with activation energy is 0.96 eV. The magnetic properties as a function of temperature represent the ferri-paramagnetic phase transition at above 50 K. M–H curve shows the hysteresis loop with saturation magnetization (M{sub s}) and confirms the presence of soft magnetic materials. - Highlights: • Ca{sub 3}Co{sub 4}O{sub 9} has not yet been reported by this starch assisted sol–gel combustion method. • SEM image shows microporous sphere like morphology. • The optical and dielectric properties of Ca{sub 3}Co{sub 4}O{sub 9} sample were studied. • Temperature dependent magnetic property has been studied for Ca{sub 3}Co{sub 4}O{sub 9}. It behaves as a soft magnetic material at 5 K.

  7. Fire Performance of Plywood Treated with Ammonium Polyphosphate and 4A Zeolite

    Directory of Open Access Journals (Sweden)

    Mingzhi Wang

    2014-07-01

    Full Text Available Plywood samples treated with ammonium polyphosphate (APP and 4A zeolite were prepared to investigate the effect of zeolite on wood’s burning behavior using a cone calorimeter under a heat flux of 35 kW/m2. Results showed that APP decreased the heat release rate (HRR, total heat release (THR, and mass loss rate (MLR of treated plywood. However, APP significantly increased the total smoke release (TSR and carbon monoxide (CO yield. The addition of 4A zeolite reduced the HRR, peak HRR, and THR of the plywood treated with only APP. The second HRR peak in a typical plywood curve diminished with the addition of as little as 2% 4A zeolite. The average specific extinction area (ASEA and CO yield decreased significantly with the presence of zeolite in the APP. The ignition time did not change significantly and the TSR increased when zeolite was present. Thus, a suitable amount of 4A zeolite works synergistically with APP in promoting flame retardancy in flame retardant plywood.

  8. Brownian motion of polyphosphate complexes in yeast vacuoles: characterization by fluorescence microscopy with image analysis.

    Science.gov (United States)

    Puchkov, Evgeny O

    2010-06-01

    In the vacuoles of Saccharomyces cerevisiae yeast cells, vividly moving insoluble polyphosphate complexes (IPCs) movement of the IPCs and to evaluate the viscosity in the vacuoles using the obtained data. Studies were conducted on S. cerevisiae cells stained by DAPI and fluorescein isothyocyanate-labelled latex microspheres, using fluorescence microscopy combined with computer image analysis (ImageJ software, NIH, USA). IPC movement was photorecorded and shown to be Brownian motion. On latex microspheres, a methodology was developed for measuring a fluorescing particle's two-dimensional (2D) displacements and its size. In four yeast cells, the 2D displacements and sizes of the IPCs were evaluated. Apparent viscosity values in the vacuoles of the cells, computed by the Einstein-Smoluchowski equation using the obtained data, were found to be 2.16 +/- 0.60, 2.52 +/- 0.63, 3.32 +/- 0.9 and 11.3 +/- 1.7 cP. The first three viscosity values correspond to 30-40% glycerol solutions. The viscosity value of 11.3 +/- 1.7 cP was supposed to be an overestimation, caused by the peculiarities of the vacuole structure and/or volume in this particular cell. This conclusion was supported by the particular quality of the Brownian motion trajectories set in this cell as compared to the other three cells.

  9. Smoke suppression properties of ferrite yellow on flame retardant thermoplastic polyurethane based on ammonium polyphosphate

    International Nuclear Information System (INIS)

    Chen, Xilei; Jiang, Yufeng; Jiao, Chuanmei

    2014-01-01

    Highlights: • Smoke suppression of FeOOH on flame retardant TPU composites has been investigated. • FeOOH has excellent smoke suppression abilities for flame retardant TPU composites. • FeOOH has good ability of char formation, hence improved smoke suppression property. -- Abstract: This article mainly studies smoke suppression properties and synergistic flame retardant effect of ferrite yellow (FeOOH) on flame retardant thermoplastic polyurethane (TPU) composites using ammonium polyphosphate (APP) as a flame retardant agent. Smoke suppression properties and synergistic flame retardant effect of FeOOH on flame retardant TPU composites were intensively investigated by smoke density test (SDT), cone calorimeter test (CCT), scanning electron microscopy (SEM), and thermal-gravimetric analysis (TGA). Remarkably, the SDT results show that FeOOH can effectively decrease the amount of smoke production with or without flame. On the other hand, the CCT data reveal that the addition of FeOOH can apparently reduce heat release rate (HRR), total heat release (THR), and total smoke release (TSR), etc. Here, FeOOH is considered to be an effective smoke suppression agent and a good synergism with APP in flame retardant TPU composites, which can greatly improve the structure of char residue realized by TGA and SEM results

  10. Suppressive effects of lysozyme on polyphosphate-mediated vascular inflammatory responses

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Jiwoo [College of Pharmacy, CMRI, Research Institute of Pharmaceutical Sciences, BK21 Plus KNU Multi-Omics Based Creative Drug Research Team, Kyungpook National University, Daegu 41566 (Korea, Republic of); Ku, Sae-Kwang [Department of Anatomy and Histology, College of Korean Medicine, Daegu Haany University, Gyeongsan 38610 (Korea, Republic of); Lee, Suyeon [College of Pharmacy, CMRI, Research Institute of Pharmaceutical Sciences, BK21 Plus KNU Multi-Omics Based Creative Drug Research Team, Kyungpook National University, Daegu 41566 (Korea, Republic of); Bae, Jong-Sup, E-mail: baejs@knu.ac.kr [College of Pharmacy, CMRI, Research Institute of Pharmaceutical Sciences, BK21 Plus KNU Multi-Omics Based Creative Drug Research Team, Kyungpook National University, Daegu 41566 (Korea, Republic of)

    2016-06-10

    Lysozyme, found in relatively high concentration in blood, saliva, tears, and milk, protects us from the ever-present danger of bacterial infection. Previous studies have reported proinflammatory responses of endothelial cells to the release of polyphosphate(PolyP). In this study, we examined the anti-inflammatory responses and mechanisms of lysozyme and its effects on PolyP-induced septic activities in human umbilical vein endothelial cells (HUVECs) and mice. The survival rates, septic biomarker levels, behavior of human neutrophils, and vascular permeability were determined in PolyP-activated HUVECs and mice. Lysozyme suppressed the PolyP-mediated vascular barrier permeability, upregulation of inflammatory biomarkers, adhesion/migration of leukocytes, and activation and/or production of nuclear factor-κB, tumor necrosis factor-α, and interleukin-6. Furthermore, lysozyme demonstrated protective effects on PolyP-mediated lethal death and the levels of the related septic biomarkers. Therefore, these results indicated the therapeutic potential of lysozyme on various systemic inflammatory diseases, such as sepsis or septic shock. -- Highlights: •PolyP is shown to be an important mediator of vascular inflammation. •Lysozyme inhibited PolyP-mediated hyperpermeability. •Lysozyme inhibited PolyP-mediated septic response. •Lysozyme reduced PolyP-induced septic mortality.

  11. A Lactobacillus mutant capable of accumulating long-chain polyphosphates that enhance intestinal barrier function.

    Science.gov (United States)

    Saiki, Asako; Ishida, Yasuaki; Segawa, Shuichi; Hirota, Ryuichi; Nakamura, Takeshi; Kuroda, Akio

    2016-05-01

    Inorganic polyphosphate (polyP) was previously identified as a probiotic-derived substance that enhances intestinal barrier function. PolyP-accumulating bacteria are expected to have beneficial effects on the human gastrointestinal tract. In this study, we selected Lactobacillus paracasei JCM 1163 as a strain with the potential to accumulate polyP, because among the probiotic bacteria stored in our laboratory, it had the largest amount of polyP. The chain length of polyP accumulated in L. paracasei JCM 1163 was approximately 700 phosphate (Pi) residues. L. paracasei JCM 1163 accumulated polyP when Pi was added to Pi-starved cells. We further improved the ability of L. paracasei JCM 1163 to accumulate polyP by nitrosoguanidine mutagenesis. The mutant accumulated polyP at a level of 1500 nmol/mg protein-approximately 190 times that of the wild-type strain. PolyP extracted from the L. paracasei JCM 1163 significantly suppressed the oxidant-induced intestinal permeability in mouse small intestine. In conclusion, we have succeeded in breeding the polyP-accumulating Lactobacillus mutant that is expected to enhance intestinal barrier function.

  12. Decreasing extracellular Na+ concentration triggers inositol polyphosphate production and Ca2+ mobilization

    International Nuclear Information System (INIS)

    Smith, J.B.; Dwyer, S.D.; Smith, L.

    1989-01-01

    Removing extracellular Na+ (Na+o) evoked a large increase in cytosolic free Ca2+ concentration ([Ca2+]i in human skin fibroblasts. Decreasing [Na+]o from 120 to 14 mM caused the half-maximal peak increase in [Ca2+]i. Removing Na+o strongly stimulated 45 Ca2+ efflux and decreased total cell Ca2+ by about 40%. Bradykinin caused changes in [Ca2+]i, total Ca2+, and 45 Ca2+ fluxes similar to those evoked by removing Na+o. Prior stimulation of the cells with bradykinin prevented Na+o removal from increasing [Ca2+]i and vice versa. Na+o removal rapidly increased [ 3 H]inositol polyphosphate production. Loading the cells with Na+ had no effect on the increase in 45 Ca2+ efflux produced by Na+o removal. Therefore, decreasing [Na+]o probably stimulates a receptor(s) which is sensitive to extracellular, not intracellular, Na+. Removing Na+o also mobilized intracellular Ca2+ in smooth muscle and endothelial cells cultured from human umbilical and dog coronary arteries, respectively

  13. Polyphosphate is a key factor for cell survival after DNA damage in eukaryotic cells.

    Science.gov (United States)

    Bru, Samuel; Samper-Martín, Bàrbara; Quandt, Eva; Hernández-Ortega, Sara; Martínez-Laínez, Joan M; Garí, Eloi; Rafel, Marta; Torres-Torronteras, Javier; Martí, Ramón; Ribeiro, Mariana P C; Jiménez, Javier; Clotet, Josep

    2017-09-01

    Cells require extra amounts of dNTPs to repair DNA after damage. Polyphosphate (polyP) is an evolutionary conserved linear polymer of up to several hundred inorganic phosphate (Pi) residues that is involved in many functions, including Pi storage. In the present article, we report on findings demonstrating that polyP functions as a source of Pi when required to sustain the dNTP increment essential for DNA repair after damage. We show that mutant yeast cells without polyP produce less dNTPs upon DNA damage and that their survival is compromised. In contrast, when polyP levels are ectopically increased, yeast cells become more resistant to DNA damage. More importantly, we show that when polyP is reduced in HEK293 mammalian cell line cells and in human dermal primary fibroblasts (HDFa), these cells become more sensitive to DNA damage, suggesting that the protective role of polyP against DNA damage is evolutionary conserved. In conclusion, we present polyP as a molecule involved in resistance to DNA damage and suggest that polyP may be a putative target for new approaches in cancer treatment or prevention. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. A novel surface modification on calcium polyphosphate scaffold for articular cartilage tissue engineering

    International Nuclear Information System (INIS)

    Lien, S.-M.; Liu, C.-K.; Huang, T.-J.

    2007-01-01

    The surface of porous three-dimensional (3D) calcium polyphosphate (CPP) scaffold was modified by treatment of quenching-after-sintering in the fabrication process. Scanning electron microscopic examination and degradation tests confirmed a new type of surface modification. A rotary-shaking culture was compared to that of a stationary culture and the results showed that rotary shaking led to enhanced extracellular matrices (ECM) secretion of both proteoglycans and collagen. Rotary-shaking cultured results showed that the quenching-treated CPP scaffold produced a better cartilage tissue, with both proteoglycans and collagen secretions enhanced, than the air-cooled-after-sintering scaffolds. Moreover, β-CPP scaffolds were better for the ECM secretion of both proteoglycans and collagen than the β-CPP + γ-CPP multiphase scaffold. However, the multiphase scaffold led to higher growth rate than that of β-CPP scaffold; the quenching-after-sintering treatment reversed this. In addition, the ECM secretions of both proteoglycans and collagen in the quenching-treated β-CPP scaffold were higher than those in the air-cooled one. Thus, the novel treatment of quenching-after-sintering has shown merits to the porous 3D CPP scaffolds for articular cartilage tissue engineering

  15. Distribution Patterns of Polyphosphate Metabolism Pathway and Its Relationships With Bacterial Durability and Virulence

    Directory of Open Access Journals (Sweden)

    Liang Wang

    2018-04-01

    Full Text Available Inorganic polyphosphate (polyP is a linear polymer of orthophosphate residues. It is reported to be present in all life forms. Experimental studies showed that polyP plays important roles in bacterial durability and virulence. Here we investigated the relationships of polyP with bacterial durability and virulence theoretically. Bacterial lifestyle, environmental persistence, virulence factors (VFs, and species evolution are all included in the analysis. The presence of seven genes involved in polyP metabolism (ppk1, ppk2, pap, surE, gppA, ppnK, and ppgK and 2595 core VFs were verified in 944 bacterial reference proteomes for distribution patterns via HMMER. Proteome size and VFs were compared in terms of gain and loss of polyP pathway. Literature mining and phylogenetic analysis were recruited to support the study. Our analyzes revealed that the presence of polyP metabolism is positively correlated with bacterial proteome size and the number of virulence genes. A potential relationship of polyP in bacterial lifestyle and environmental durability is suggested. Evolutionary analysis shows that polyP genes are randomly lost along the phylogenetic tree. In sum, based on our theoretical analysis, we confirmed that bacteria with polyP metabolism are associated with high environmental durability and more VFs.

  16. Caveats in studies of the physiological role of polyphosphates in coagulation.

    Science.gov (United States)

    Lindahl, Tomas L; Ramström, Sofia; Boknäs, Niklas; Faxälv, Lars

    2016-02-01

    Platelet-derived polyphosphates (polyP), stored in dense granule and released upon platelet activation, have been claimed to enhance thrombin activation of coagulation factor XI (FXI) and to activate FXII directly. The latter claim is controversial and principal results leading to these conclusions are probably influenced by methodological problems. It is important to consider that low-grade contact activation is initiated by all surfaces and is greatly amplified by the presence of phospholipids simulating the procoagulant membranes of activated platelets. Thus, proper use of inhibitors of the contact pathway and a careful choice of materials for plates and tubes is important to avoid artefacts. The use of phosphatases used to degrade polyP has an important drawback as it also degrades the secondary activators ADP and ATP, which are released from activated platelets. In addition, the use of positively charged inhibitors, such as polymyxin B, to inhibit polyP in platelet-rich plasma and blood is problematic, as polymyxin B also slows coagulation in the absence of polyP. In conclusion we hope awareness of the above caveats may improve research on the physiological roles of polyP in coagulation. © 2016 Authors; published by Portland Press Limited.

  17. Flame Retardancy and Mechanical Properties of Kenaf Filled Polypropylene (PP) Containing Ammonium Polyphosphate (APP)

    International Nuclear Information System (INIS)

    Atikah Ismail; Azman Hassan; Aznizam Abu Bakar; Jawaid, M.

    2013-01-01

    The effects of ammonium polyphosphate (APP) as flame retardant and kenaf as fillers on flammability, thermal and mechanical properties of polypropylene (PP) composites were determined. Test specimens were prepared by using a co-rotating twin screw extruder for the compounding process followed by injection molding. The flame retardancy of the composites was determined by using limiting oxygen index (LOI) test. Addition of flame retardant into kenaf-PP composites significantly increased the LOI values that indicated the improvement of flame retardancy. Thermogravimetric analysis was done to examine the thermal stability of the composites. The addition of kenaf fiber in PP composites decreased the thermal stability significantly but the influence of APP on thermal properties of the kenaf-filled PP composites was not significant. The flexural strength and modulus of composites increased with the addition of APP into kenaf filled PP composite. The addition of APP into kenaf filled PP causes increase in the impact strength while increasing the APP content in the kenaf filled PP composite show decrease in impact strength. (author)

  18. Suppressive effects of lysozyme on polyphosphate-mediated vascular inflammatory responses

    International Nuclear Information System (INIS)

    Chung, Jiwoo; Ku, Sae-Kwang; Lee, Suyeon; Bae, Jong-Sup

    2016-01-01

    Lysozyme, found in relatively high concentration in blood, saliva, tears, and milk, protects us from the ever-present danger of bacterial infection. Previous studies have reported proinflammatory responses of endothelial cells to the release of polyphosphate(PolyP). In this study, we examined the anti-inflammatory responses and mechanisms of lysozyme and its effects on PolyP-induced septic activities in human umbilical vein endothelial cells (HUVECs) and mice. The survival rates, septic biomarker levels, behavior of human neutrophils, and vascular permeability were determined in PolyP-activated HUVECs and mice. Lysozyme suppressed the PolyP-mediated vascular barrier permeability, upregulation of inflammatory biomarkers, adhesion/migration of leukocytes, and activation and/or production of nuclear factor-κB, tumor necrosis factor-α, and interleukin-6. Furthermore, lysozyme demonstrated protective effects on PolyP-mediated lethal death and the levels of the related septic biomarkers. Therefore, these results indicated the therapeutic potential of lysozyme on various systemic inflammatory diseases, such as sepsis or septic shock. -- Highlights: •PolyP is shown to be an important mediator of vascular inflammation. •Lysozyme inhibited PolyP-mediated hyperpermeability. •Lysozyme inhibited PolyP-mediated septic response. •Lysozyme reduced PolyP-induced septic mortality.

  19. Sol-gel processes. January 1970-September 1989 (Citations from the NTIS data base). Report for January 1970-September 1989

    International Nuclear Information System (INIS)

    1989-09-01

    This bibliography contains citations concerning the development and utilization of sol-gel processes and techniques. Topics include antireflective coatings, studies of sol-gel transitions, sol-gel synthesis and polymerization, sol-gel derived thin films and glasses, and sol-gel production of microspheres. Applications in nuclear waste management, nuclear-fuel manufacturing, glass optical waveguide development, and solar-energy collection are presented. (This updated bibliography contains 179 citations, 39 of which are new entries to the previous edition.)

  20. Sol-Gel Glasses

    Science.gov (United States)

    Mukherjee, S. P.

    1985-01-01

    Multicomponent homogeneous, ultrapure noncrystalline gels/gel derived glasses are promising batch materials for the containerless glass melting experiments in microgravity. Hence, ultrapure, homogeneous gel precursors could be used to: (1) investigate the effect of the container induced nucleation on the glass forming ability of marginally glass forming compositions; and (2) investigate the influence of gravity on the phase separation and coarsening behavior of gel derived glasses in the liquid-liquid immiscibility zone of the nonsilicate systems having a high density phase. The structure and crystallization behavior of gels in the SiO2-GeO2 as a function of gel chemistry and thermal treatment were investigated. As are the chemical principles involved in the distribution of a second network former in silica gel matrix being investigated. The procedures for synthesizing noncrystalline gels/gel-monoliths in the SiO2-GeO2, GeO2-PbO systems were developed. Preliminary investigations on the levitation and thermal treatment of germania silicate gel-monoliths in the Pressure Facility Acoustic Levitator were done.

  1. Making MgO/SiO2 Glasses By The Sol-Gel Process

    Science.gov (United States)

    Bansal, Narottam P.

    1989-01-01

    Silicon dioxide glasses containing 15 mole percent magnesium oxide prepared by sol-gel process. Not made by conventional melting because ingredients immiscible liquids. Synthesis of MgO/SiO2 glass starts with mixing of magnesium nitrate hexahydrate with silicon tetraethoxide, both in alcohol. Water added, and transparent gel forms. Subsequent processing converts gel into glass. Besides producing glasses of new composition at lower processing temperatures, sol-gel method leads to improved homogeneity and higher purity.

  2. Sol–gel assisted synthesis and photoluminescence property of Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, Dy{sup 3+} red phosphor for white light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wentao, E-mail: zhangwentao2005@163.com [College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China); Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institutions, Chengdu 610059 (China); Wang, Yulong; Gao, Yang [College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China); Long, Jianping [College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China); Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institutions, Chengdu 610059 (China); Li, Junfeng [College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China)

    2016-05-15

    Eu{sup 2+}, Dy{sup 3+} co-doped Sr{sub 2}Si{sub 5}N{sub 8} red phosphors were prepared using a sol–gel-nitridation method at a lower temperature comparing with traditional solid state reaction. Effects of synthesis process, Eu{sup 2+} and Dy{sup 3+} doping concentration on the crystal structure and luminescence property of as-prepared phosphors were investigated. X-ray diffraction patterns indicated that all Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, Dy{sup 3+} phosphors have the standard phase of Sr{sub 2}Si{sub 5}N{sub 8} structure. With a broad excitation from UV to blue light, a strong emission of Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, Dy{sup 3+} with 4f{sup 6}5d{sup 1}→4f{sup 7} transition of Eu{sup 2+} ions was obtained at red region in photoluminescence spectra. Emission peaks in spectra were red-shifted from 611 to 632 nm for all Sr{sub 2}Si{sub 5}N{sub 8}:xEu{sup 2+} as Eu{sup 2+} ion concentrations increased, which due to Eu{sup 2+} ions occupying from the tenfold coordinated site (Sr1) to the eightfold coordinated site (Sr2). These Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} phosphors with Dy{sup 3+} co-doping showed excellent luminescence properties, included emission intensity and luminescence quenching. It is potential that Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, Dy{sup 3+} phosphors can be applied in white LEDs combining with blue InGaN LEDs. - Highlights: • Eu{sup 2+}/Dy{sup 3+} co-doped Sr{sub 2}Si{sub 5}N{sub 8} red phosphor were prepared by sol–gel-nitridation. • Sol–gel-nitridation method decreased the crystallization temperature of Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, Dy{sup 3+} effectively. • Luminescence properties of Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} were improved obviously by Dy{sup 3+} co-doping. • Luminescence properties of Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, Dy{sup 3+} phosphors are superior to commercial Y{sub 2}O{sub 2}S:Eu{sup 3+}.

  3. TiO2/SiO2 prepared via facile sol-gel method as an ideal support for green synthesis of Ag nanoparticles using Oenothera biennis extract and their excellent catalytic performance in the reduction of 4-nitrophenol

    Directory of Open Access Journals (Sweden)

    Bahar Khodadadi

    2017-01-01

    Full Text Available In the present study, the extract of the plant of Oenothera biennis was used to green synthesis of silver nanoparticles (Ag NPs as an environmentally friendly, simple and low cost method. And Additionally, TiO2/SiO2 was prepared via facile sol-gel method using starch as an important, naturally abundant organic polymer as an ideal support. The Ag NPs/TiO2/SiO2 as an effective catalyst was prepared through reduction of Ag+ ions using Oenothera biennis extract as the reducing and stabilizing agent and Ag NPs immobilization on TiO2/SiO2 surface in the absence of any stabilizer or surfactant. Several techniques such as FT-IR spectroscopy, UV-Vis spectroscopy, X-ray Diffraction (XRD, sScanning eElectron mMicroscopy (FE-SEM, Eenergy dDispersive X-ray sSpectroscopy (EDS, and Ttransmission Eelectron Mmicroscopy (TEM were used to characterize TiO2/SiO2, silver nanoparticles (Ag NPs, and Ag NPs/TiO2/SiO2. Moreover, the catalytic activity of the Ag NPs/ TiO2/SiO2 was investigated in the reduction of 4-nitrophenol (4-NP at room temperature. On the basis of the results, the Ag NPs/TiO2/SiO2 was found to be high catalytic activity highly active catalyst according to the experimental results in this study. In addition, Ag NPs/TiO2/SiO2 can be recovered and reused several times in the reduction of 4-NP with no significant loss of catalytic activity.

  4. GelTouch

    DEFF Research Database (Denmark)

    Miruchna, Viktor; Walter, Robert; Lindlbauer, David

    2015-01-01

    We present GelTouch, a gel-based layer that can selectively transition between soft and stiff to provide tactile multi-touch feedback. It is flexible, transparent when not activated, and contains no mechanical, electromagnetic, or hydraulic components, resulting in a compact form factor (a 2mm thin...... touchscreen layer for our prototype). The activated areas can be morphed freely and continuously, without being limited to fixed, predefined shapes. GelTouch consists of a poly(N-isopropylacrylamide) gel layer which alters its viscoelasticity when activated by applying heat (>32 C). We present three different...

  5. Thorium inorganic gels

    International Nuclear Information System (INIS)

    Genet, M.; Brandel, V.

    1988-01-01

    The optimum pH and concentration values of thorium salts and oxoacids or oxoacid salts which lead to transparent and stable inorganic gels have been determined. The isotherm drying process of the gel at 50 0 C leads successively to a partly dehydrated gel, then, to the formation of an unusual liquid phase and, finally to a dry amorphous solid phase which is still transparent. This kind of transparent inorganic gels and amorphous phase can be used as matrices for spectroscopic studies [fr

  6. Polyphosphate induces matrix metalloproteinase-3-mediated proliferation of odontoblast-like cells derived from induced pluripotent stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Ozeki, Nobuaki; Hase, Naoko; Yamaguchi, Hideyuki; Hiyama, Taiki; Kawai, Rie [Department of Endodontics, School of Dentistry, Aichi Gakuin University, 2-11 Suemori-dori, Chikusa-ku, Nagoya, Aichi 464-8651 (Japan); Kondo, Ayami [Department of Medicinal Biochemistry, School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto, Chikusa-ku, Nagoya 464-8650 (Japan); Nakata, Kazuhiko [Department of Endodontics, School of Dentistry, Aichi Gakuin University, 2-11 Suemori-dori, Chikusa-ku, Nagoya, Aichi 464-8651 (Japan); Mogi, Makio, E-mail: makio@dpc.agu.ac.jp [Department of Medicinal Biochemistry, School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto, Chikusa-ku, Nagoya 464-8650 (Japan)

    2015-05-01

    Inorganic polyphosphate [Poly(P)] may represent a physiological source of phosphate and has the ability to induce bone differentiation in osteoblasts. We previously reported that cytokine-induced matrix metalloproteinase (MMP)-3 accelerates the proliferation of purified odontoblast-like cells. In this study, MMP-3 small interfering RNA (siRNA) was transfected into odontoblast-like cells derived from induced pluripotent stem cells to investigate whether MMP-3 activity is induced by Poly(P) and/or is associated with cell proliferation and differentiation into odontoblast-like cells. Treatment with Poly(P) led to an increase in both cell proliferation and additional odontoblastic differentiation. Poly(P)-treated cells showed a small but significant increase in dentin sialophosphoprotein (DSPP) and dentin matrix protein-1 (DMP-1) mRNA expression, which are markers of mature odontoblasts. The cells also acquired additional odontoblast-specific properties including adoption of an odontoblastic phenotype typified by high alkaline phosphatase (ALP) activity and a calcification capacity. In addition, Poly(P) induced expression of MMP-3 mRNA and protein, and increased MMP-3 activity. MMP-3 siRNA-mediated disruption of the expression of these effectors potently suppressed the expression of odontoblastic biomarkers ALP, DSPP, and DMP-1, and blocked calcification. Interestingly, upon siRNA-mediated silencing of MMP-3, we noted a potent and significant decrease in cell proliferation. Using specific siRNAs, we revealed that a unique signaling cascade, Poly(P)→MMP-3→DSPP and/or DMP-1, was intimately involved in the proliferation of odontoblast-like cells. - Highlights: • Polyphosphate increases proliferation of iPS cell-derived odontoblast-like cells. • Polyphosphate-induced MMP-3 results in an increase of cell proliferation. • Induced cell proliferation involves MMP-3, DSPP, and/or DMP-1 sequentially. • Induced MMP-3 also results in an increase of odontoblastic

  7. Inositol Polyphosphate Multikinase Inhibits Angiogenesis via Inositol Pentakisphosphate-Induced HIF-1α Degradation.

    Science.gov (United States)

    Fu, Chenglai; Tyagi, Richa; Chin, Alfred C; Rojas, Tomas; Li, Ruo-Jing; Guha, Prasun; Bernstein, Isaac A; Rao, Feng; Xu, Risheng; Cha, Jiyoung Y; Xu, Jing; Snowman, Adele M; Semenza, Gregg L; Snyder, Solomon H

    2018-02-02

    Inositol polyphosphate multikinase (IPMK) and its major product inositol pentakisphosphate (IP5) regulate a variety of cellular functions, but their role in vascular biology remains unexplored. We have investigated the role of IPMK in regulating angiogenesis. Deletion of IPMK in fibroblasts induces angiogenesis in both in vitro and in vivo models. IPMK deletion elicits a substantial increase of VEGF (vascular endothelial growth factor), which mediates the regulation of angiogenesis by IPMK. The regulation of VEGF by IPMK requires its catalytic activity. IPMK is predominantly nuclear and regulates gene transcription. However, IPMK does not apparently serve as a transcription factor for VEGF. HIF (hypoxia-inducible factor)-1α is a major determinant of angiogenesis and induces VEGF transcription. IPMK deletion elicits a major enrichment of HIF-1α protein and thus VEGF. HIF-1α is constitutively ubiquitinated by pVHL (von Hippel-Lindau protein) followed by proteasomal degradation under normal conditions. However, HIF-1α is not recognized and ubiquitinated by pVHL in IPMK KO (knockout) cells. IP5 reinstates the interaction of HIF-1α and pVHL. HIF-1α prolyl hydroxylation, which is prerequisite for pVHL recognition, is interrupted in IPMK-deleted cells. IP5 promotes HIF-1α prolyl hydroxylation and thus pVHL-dependent degradation of HIF-1α. Deletion of IPMK in mouse brain increases HIF-1α/VEGF levels and vascularization. The increased VEGF in IPMK KO disrupts blood-brain barrier and enhances brain blood vessel permeability. IPMK, via its product IP5, negatively regulates angiogenesis by inhibiting VEGF expression. IP5 acts by enhancing HIF-1α hydroxylation and thus pVHL-dependent degradation of HIF-1α. © 2017 American Heart Association, Inc.

  8. In Vitro Effects of Polyphosphate against Prevotella intermedia in Planktonic Phase and Biofilm.

    Science.gov (United States)

    Jang, Eun-Young; Kim, Minjung; Noh, Mi Hee; Moon, Ji-Hoi; Lee, Jin-Yong

    2016-02-01

    Polyphosphate (polyP) has gained a wide interest in the food industry due to its potential as a decontaminating agent. In this study, we examined the effect of sodium tripolyphosphate (polyP3; Na5P3O10) against planktonic and biofilm cells of Prevotella intermedia, a major oral pathogen. The MIC of polyP3 against P. intermedia ATCC 49046 determined by agar dilution method was 0.075%, while 0.05% polyP3 was bactericidal against P. intermedia in time-kill analysis performed using liquid medium. A crystal violet binding assay for the assessment of biofilm formation by P. intermedia showed that sub-MICs of polyP3 significantly decreased biofilm formation. Under the scanning electron microscope, decreased numbers of P. intermedia cells forming the biofilms were observed when the bacterial cells were incubated with 0.025% or higher concentrations of polyP3. Assessment of biofilm viability with LIVE/DEAD staining and viable cell count methods showed that 0.05% or higher concentrations of polyP3 significantly decreased the viability of the preformed biofilms in a concentration-dependent manner. The zone sizes of alpha-hemolysis formed on horse blood agar produced by P. intermedia were decreased in the presence of polyP3. The expression of the genes encoding hemolysins and the genes of the hemin uptake (hmu) locus was downregulated by polyP3. Collectively, our results show that polyP is an effective antimicrobial agent against P. intermedia in biofilms as well as planktonic phase, interfering with the process of hemin acquisition by the bacterium. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  9. Combination effect of melamine polyphosphate and graphene on flame retardant properties of poly(vinyl alcohol)

    International Nuclear Information System (INIS)

    Huang Guobo; Liang Huading; Wang Yong; Wang Xu; Gao Jianrong; Fei Zhengdong

    2012-01-01

    Highlights: ► PVA/graphene/MPP composites were prepared by solvent blending. ► PVA/graphene systems improved the flame retardancy of the nanocomposites. ► Flame retardation mechanism was explained by SEM, FT-IR and XPS. - Abstract: A novel flame retardant poly(vinyl alcohol) (PVA)/melamine polyphosphate (MPP)–graphene nanocomposite has been prepared by solvent blending. Results from X-ray diffraction (XRD) and transmission electron microscopy (TEM) suggest that an excellent dispersion of exfoliated graphene and MPP in the PVA matrix was achieved. The thermal and flammability properties of the nanocomposite were investigated using thermogravimetry, cone calorimetry, and flammability tests (UL 94 and LOI). The presence of both MPP and graphene in the polymer matrix led to an enhanced thermal stability and significantly reduced flammability for the nanocomposite. PVA composites filled with 10 wt% MPP and 1 wt% graphene (PVA/G1/MPP10) achieved the LOI value of 29.6 and UL-94 V0 grade. Compared to pure PVA, the peak heat release rate (PHRR) of PVA/G1/MPP10 is reduced by about 60%. Meanwhile, the mechanical properties of PVA/G1/MPP10 composites exhibit almost no deterioration compared with pure PVA. The morphology and composition of residues generated after cone calorimeter tests were investigated by scanning electronic microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The SEM images showed the compact and dense intumescent char jammed with graphene sheets was formed for PVA/G1/MPP10 during combustion. The results of XPS confirmed that carbon content of the char for PVA/G1/MPP10 is increased obviously by the combination effect of the flame retardant MPP and graphene.

  10. Copper tolerance mediated by polyphosphate degradation and low-affinity inorganic phosphate transport system in Escherichia coli

    OpenAIRE

    Grillo-Puertas, Mariana; Schurig-Briccio, Lici Ariane; Rodríguez-Montelongo, Luisa; Rintoul, María Regina; Rapisarda, Viviana Andrea

    2014-01-01

    Background Metal tolerance in bacteria has been related to polyP in a model in which heavy metals stimulate the polymer hydrolysis, forming metal-phosphate complexes that are exported. As previously described in our laboratory, Escherichia coli cells grown in media containing a phosphate concentration >37 mM maintained an unusually high polyphosphate (polyP) level in stationary phase. The aim of the present work was to evaluate the influence of polyP levels as the involvement of low-affinity ...

  11. Linear-to-λ-Shape P-O-P Bond Transmutation in Polyphosphates with Infinite (PO3)∞ Chain.

    Science.gov (United States)

    Wang, Ying; Li, Lin; Han, Shujuan; Lei, Bing-Hua; Abudoureheman, Maierhaba; Yang, Zhihua; Pan, Shilie

    2017-09-05

    A new metal polyphosphate, α-CsBa 2 (PO 3 ) 5 , exhibiting the first example of a linear P-O-P bond angle in a one-dimensional (PO 3 ) ∞ chain has been reported. Interestingly, α → β phase transition occurs in CsBa 2 (PO 3 ) 5 along with the P-O-P bonds varying from linear to λ-shape, suggesting that α-CsBa 2 (PO 3 ) 5 with unfavorable linear P-O-P bonds is more stable at ambient temperature.

  12. Gamma ray induced synthesis of superabsorbent hydrogels

    International Nuclear Information System (INIS)

    Ramnani, S.P.; Sabharwal, S.; Rawat, K.P.; Majali, A.B.

    2000-01-01

    The synthesis of superabsorbent gel by grafting of acrylic acid on carboxymethyl cellulose has been carried out using gamma radiation. One gram of this gel absorbs and holds as high as 460 gm of water. The effect of various additives on water absorption characteristics was studied and possible applications of this gel to agriculture are proposed. (author)

  13. Cyanocobalamin Nasal Gel

    Science.gov (United States)

    ... to supply extra vitamin B12 to people who need unusually large amounts of this vitamin because they are pregnant or have certain diseases. ... Cyanocobalamin nasal gel will supply you with enough vitamin B12 only as ... it regularly. You may need to use cyanocobalamin nasal gel every week for ...

  14. Sealing wells with gel

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, E C

    1967-10-01

    A new system is being used in Mexico to temporarily plug producing wells. The temporary seal is a gel with a catalyst. The use of this temporary plug allows gas-lift wells to be taken off production in order to carry out emergency repairs. The gel solidifies by the action of the catalyst to a high temperature (70 - 150/sup 0/C). By locating the bottom of the tubing at the top of the production interval, the gel material will go into the permeable formation, and immediately set. When the gel has solidified, it seals off the horizon that must not be stimulated, and leaves the others exposed to the acid action. When the treatment is finished, the gel, by action of the catalyst, is liquefied and removed from the formation, being produced with the oil.

  15. Sol-gel growth of vanadium dioxide

    International Nuclear Information System (INIS)

    Speck, K.R.

    1990-01-01

    This thesis examines the chemical reactivity of vanadium (IV) tetrakis(t-butoxide) as a precursor for the sol-gel synthesis of vanadium dioxide. Hydrolysis and condensation of the alkoxide was studied by FTIR spectroscopy. Chemical modification of the vanadium tetraalkoxide by alcohol interchange was studied using 51 V NMR and FTIR. Vanadium dioxide thin films and powders were made from vanadium tetrakis(t-butoxide) by standard sol-gel techniques. Post-deposition heating under nitrogen was necessary to transform amorphous gels into vanadium dioxide. Crystallization of films and powders was studied by FTIR, DSC, TGA, and XRD. Gel-derived vanadium dioxide films undergo a reversible semiconductor-to-metal phase transition near 68C, exhibiting characteristic resistive and spectral changes. The electrical resistance decreased by two to three orders of magnitude and the infrared transmission sharply dropped as the material was cycled through this thermally induced phase transition. The sol-gel method was also used to make doped vanadium dioxide films. Films were doped with tungsten and molybdenum ions to effectively lower the temperature at which the transition occurs

  16. Fabrication of targets for transmutation of americium : synthesis of inertial matrix by sol-gel method. Procedure study on the infiltration of a radioactive solutions; Fabricacion de blancos para la transmutacion de americio: sintesis de matrices inertes por el metodo sol-gel. Estudio del procedimiento de infiltracion de disoluciones radiactivas

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez Carretero, A [Universidad Complutense de Madrid (Spain)

    2002-07-01

    Transmutation and incineration are innovative options in the management and disposal of fission products and actinides. nevertheless, the fabrication of targets for transmutation and incineration of actinides and fission products require a reconsideration of conventional processes (mechanical blending) and the development of new procedures compatible with the high activity of these materials. This work presents th R and D of a new fabrication method called INRAM (Infiltration of Radioactive Materials) based on the infiltration of an actinide solution in a porous non radiotoxic material in the form of a pellet (up to 12% An), or beads (up to 40% An) produced by sol-gel. The first method have been used for the fabrication of spinel (MgAl{sub 2}O{sub 4}) targets containing 11% Am, which have been irradiated in HFR-Petten (358.4 full power days). Post-test burn-up calculations showed that at the end of the irradiation the initial Am-241 concentration was reduced to 4%. The fraction of the initial americum atoms that have been fissioned is 28%. The main advantage of the INRAM method is that matrices with low or zero activity can be fabricated and formed into the required shape in an unshielded facility. This method offers other advantages over conventional ones, such as the active wastes are reduced, is easy to automate, adoptable to telemanipulation and dust free, which facilitate operator intervention and minimise radiation exposure to the personal. In addition, the infiltrant needs only be present in liquid form, i. e. it could be transferred directly from the reprocessing plant for fabrication into targets without conversion into-solid form. In order to optimise the infiltration process in depth investigations of all important process parameters, e. g. infiltration kinetics and metal (pu, Am) concentration in the feed solution, and also on extensive study or powder metallurgy parameters for the preparation of high quality fuel pellets with a high density, have been

  17. Phosphorus recycling from an unexplored source by polyphosphate accumulating microalgae and cyanobacteria – a step to phosphorus security in agriculture

    Directory of Open Access Journals (Sweden)

    Chandan eMukherjee

    2015-12-01

    Full Text Available Phosphorus (P, an essential element required for crop growth has no substitute. The global food security depends on phosphorus availability in soil for crop production. World phosphorus reserves are fast depleting and with an annual increase of 2.3% in phosphorus demand, the current reserves will be exhausted in coming 50-100 years. India and other Western countries are forced to import phosphorus fertilizers at high costs to meet their agricultural demands due to uneven distribution of phosphate rocks on earth. The present study from India, aims to draw attention to an unnoticed source of phosphorus being wasted as parboiled rice mill effluent and subsequent bio-recovery of the valuable element from this unconventional source. The research was conducted in West Bengal, India, a state with the highest number of parboiled rice mills where its effluent carries on an average ~40 mg/L of soluble phosphorus. Technology to recover and recycle this wastewater P in India in a simple, inexpensive mode is yet to be optimized. Our strategy to use microalgae, Chlorella sp. and cyanobacteria, Cyanobacterium sp., Lyngbya sp. and Anabaena sp. to sequester the excess phosphorus from the effluent as polyphosphate inclusions and its subsequent recycling as slow and moderate release phosphorus biofertilizers to aid plant growth, preventing phosphorus loss and pollution, is a contemporary venture to meet the need of the hour. These polyphosphate accumulating microorganisms play a dual role of remediation and recovery of phosphorus, preliminarily validated in laboratory scale.

  18. Complete Nutrient Removal Coupled to Nitrous Oxide Production as a Bioenergy Source by Denitrifying Polyphosphate-Accumulating Organisms.

    Science.gov (United States)

    Gao, Han; Liu, Miaomiao; Griffin, James S; Xu, Longcheng; Xiang, Da; Scherson, Yaniv D; Liu, Wen-Tso; Wells, George F

    2017-04-18

    Coupled aerobic-anoxic nitrous decomposition operation (CANDO) is a promising emerging bioprocess for wastewater treatment that enables direct energy recovery from nitrogen (N) in three steps: (1) ammonium oxidation to nitrite; (2) denitrification of nitrite to nitrous oxide (N 2 O); and (3) N 2 O conversion to N 2 with energy generation. However, CANDO does not currently target phosphorus (P) removal. Here, we demonstrate that denitrifying polyphosphate-accumulating organism (PAO) enrichment cultures are capable of catalyzing simultaneous biological N and P removal coupled to N 2 O generation in a second generation CANDO process, CANDO+P. Over 7 months (>300 cycles) of operation of a prototype lab-scale CANDO+P sequencing batch reactor treating synthetic municipal wastewater, we observed stable and near-complete N removal accompanied by sustained high-rate, high-yield N 2 O production with partial P removal. A substantial increase in abundance of the PAO Candidatus Accumulibacter phosphatis was observed, increasing from 5% of the total bacterial community in the inoculum to over 50% after 4 months. PAO enrichment was accompanied by a strong shift in the dominant Accumulibacter population from clade IIC to clade IA, based on qPCR monitoring of polyphosphate kinase 1 (ppk1) gene variants. Our work demonstrates the feasibility of combining high-rate, high-yield N 2 O production for bioenergy production with combined N and P removal from wastewater, and it further suggests a putative denitrifying PAO niche for Accumulibacter clade IA.

  19. Tuning the Phosphoryl Donor Specificity of Dihydroxyacetone Kinase from ATP to Inorganic Polyphosphate. An Insight from Computational Studies

    Directory of Open Access Journals (Sweden)

    Israel Sánchez-Moreno

    2015-11-01

    Full Text Available Dihydroxyacetone (DHA kinase from Citrobacter freundii provides an easy entry for the preparation of DHA phosphate; a very important C3 building block in nature. To modify the phosphoryl donor specificity of this enzyme from ATP to inorganic polyphosphate (poly-P; a directed evolution program has been initiated. In the first cycle of evolution, the native enzyme was subjected to one round of error-prone PCR (EP-PCR followed directly (without selection by a round of DNA shuffling. Although the wild-type DHAK did not show activity with poly-P, after screening, sixteen mutant clones showed an activity with poly-phosphate as phosphoryl donor statistically significant. The most active mutant presented a single mutation (Glu526Lys located in a flexible loop near of the active center. Interestingly, our theoretical studies, based on molecular dynamics simulations and hybrid Quantum Mechanics/Molecular Mechanics (QM/MM optimizations, suggest that this mutation has an effect on the binding of the poly-P favoring a more adequate position in the active center for the reaction to take place.

  20. Crystal structures and theoretical studies of polyphosphate LiZnP3O9 for nonlinear optical applications

    Science.gov (United States)

    Xie, Zhiqing; Su, Xin; Ding, Hanqin; Li, Hongyi

    2018-06-01

    Nonlinear optical materials have attracted worldwide attention owing to their wide range of applications, specially in the laser field. Phosphates with noncentrosymmetric structures are potential candidates for novel ultraviolet (UV)-NLO materials, because they usually display short UV cut-off edges. In this work, a polyphosphate, the LiZnP3O9 polyphosphate crystals were grown through spontaneous crystallization from high-temperature melts. It crystallizes in the orthorhombic space group P212121 with unit cell parameters a = 8.330(3) Å, b = 8.520(3) Å, c = 8.635(3) Å, and Z = 4. In the structure, all the P atoms are coordinated by four oxygen atoms forming the [PO4] tetrahedra and further connected to generate a zig-zag [PO3]∞ anionic framework. Thermal analysis, IR spectroscopy, UV-vis-NIR diffuse reflectance spectrum and powder second harmonic generation measurements are performed. In addition, the first-principles calculation was employed for better understanding the structure-property relationships of LiZnP3O9.

  1. Platelet-Derived Short-Chain Polyphosphates Enhance the Inactivation of Tissue Factor Pathway Inhibitor by Activated Coagulation Factor XI.

    Directory of Open Access Journals (Sweden)

    Cristina Puy

    Full Text Available Factor (F XI supports both normal human hemostasis and pathological thrombosis. Activated FXI (FXIa promotes thrombin generation by enzymatic activation of FXI, FIX, FX, and FV, and inactivation of alpha tissue factor pathway inhibitor (TFPIα, in vitro. Some of these reactions are now known to be enhanced by short-chain polyphosphates (SCP derived from activated platelets. These SCPs act as a cofactor for the activation of FXI and FV by thrombin and FXIa, respectively. Since SCPs have been shown to inhibit the anticoagulant function of TFPIα, we herein investigated whether SCPs could serve as cofactors for the proteolytic inactivation of TFPIα by FXIa, further promoting the efficiency of the extrinsic pathway of coagulation to generate thrombin.Purified soluble SCP was prepared by size-fractionation of sodium polyphosphate. TFPIα proteolysis was analyzed by western blot. TFPIα activity was measured as inhibition of FX activation and activity in coagulation and chromogenic assays. SCPs significantly accelerated the rate of inactivation of TFPIα by FXIa in both purified systems and in recalcified plasma. Moreover, platelet-derived SCP accelerated the rate of inactivation of platelet-derived TFPIα by FXIa. TFPIα activity was not affected by SCP in recalcified FXI-depleted plasma.Our data suggest that SCP is a cofactor for TFPIα inactivation by FXIa, thus, expanding the range of hemostatic FXIa substrates that may be affected by the cofactor functions of platelet-derived SCP.

  2. Inorganic Polyphosphates Regulate Hexokinase Activity and Reactive Oxygen Species Generation in Mitochondria of Rhipicephalus (Boophilus) microplus Embryo

    Science.gov (United States)

    Fraga, Amanda; Moraes, Jorge; da Silva, José Roberto; Costa, Evenilton P.; Menezes, Jackson; da Silva Vaz Jr, Itabajara; Logullo, Carlos; da Fonseca, Rodrigo Nunes; Campos, Eldo

    2013-01-01

    The physiological roles of polyphosphates (poly P) recently found in arthropod mitochondria remain obscure. Here, the possible involvement of poly P with reactive oxygen species generation in mitochondria of Rhipicephalus microplus embryos was investigated. Mitochondrial hexokinase and scavenger antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione reductase were assayed during embryogenesis of R. microplus. The influence of poly P3 and poly P15 were analyzed during the period of higher enzymatic activity during embryogenesis. Both poly Ps inhibited hexokinase activity by up to 90% and, interestingly, the mitochondrial membrane exopolyphosphatase activity was stimulated by the hexokinase reaction product, glucose-6-phosphate. Poly P increased hydrogen peroxide generation in mitochondria in a situation where mitochondrial hexokinase is also active. The superoxide dismutase, catalase and glutathione reductase activities were higher during embryo cellularization, at the end of embryogenesis and during embryo segmentation, respectively. All of the enzymes were stimulated by poly P3. However, superoxide dismutase was not affected by poly P15, catalase activity was stimulated only at high concentrations and glutathione reductase was the only enzyme that was stimulated in the same way by both poly Ps. Altogether, our results indicate that inorganic polyphosphate and mitochondrial membrane exopolyphosphatase regulation can be correlated with the generation of reactive oxygen species in the mitochondria of R. microplus embryos. PMID:23983617

  3. One-pot synthesis of hybrid gel by use of tributylstannyl ester of polymeric silicic acid, chlorosilane and organic monomer; Keisan no toribuchiru sutanniru esuteru kobuntai, kuroroshiran oyobi yuki monoma wo mochiita haiburiddo geru no ichidankai gosei

    Energy Technology Data Exchange (ETDEWEB)

    Moriya, O. [National Defense Academy, Kanagawa (Japan). Dept. of Chemistry; Sugisaki, T. [Lintec Co. Ltd., Saitama (Japan); Tomono, M.; Oikawa, M.; Kageyama, T. [Kanto-Gakuin Univ., Kanagawa (Japan)

    1999-12-10

    Organic-inorganic hybrid gels were obtained efficiently by one-pot procedure from tributylstannyl ester of polymeric silicic acid (PTBS), chloro (3-methacryloyloxypropyl) dimethylsilane (1a), and common monomers such as styrene, acrylonitrile, and methyl methacrylate. In the reaction system, substitution of tributylstannyl groups of PTBS by silyl groups of 1a and copolymerization of methacryloyloxy group of 1a with a monomer proceeded simultaneously under UV irradiation at room temperature. The resulting gel should be consisted of covalently bonded three components an regarded as a nanocomposite material The use of another chlorosilane 1b, which had cyanopropyl group, with 1a led to formation of a multifunctional hybrid gel. (author)

  4. Inorganic Polyphosphate Is Essential for Salmonella Typhimurium Virulence and Survival in Dictyostelium discoideum

    Directory of Open Access Journals (Sweden)

    Macarena A. Varas

    2018-01-01

    Full Text Available Inorganic polyphosphate (polyP deficiency in enteric bacterial pathogens reduces their ability to invade and establish systemic infections in different hosts. For instance, inactivation of the polyP kinase gene (ppk encoding the enzyme responsible for polyP biosynthesis reduces invasiveness and intracellular survival of Salmonella enterica serovar Typhimurium (S. Typhimurium in epithelial cells and macrophages in vitro. In addition, the virulence in vivo of a S. Typhimurium Δppk mutant is significantly reduced in a murine infection model. In spite of these observations, the role played by polyP during the Salmonella-host interaction is not well understood. The social amoeba Dictyostelium discoideum has proven to be a useful model for studying relevant aspects of the host-pathogen interaction. In fact, many intracellular pathogens can survive within D. discoideum cells using molecular mechanisms also required to survive within macrophages. Recently, we established that S. Typhimurium is able to survive intracellularly in D. discoideum and identified relevant genes linked to virulence that are crucial for this process. The aim of this study was to determine the effect of a polyP deficiency in S. Typhimurium during its interaction with D. discoideum. To do this, we evaluated the intracellular survival of wild-type and Δppk strains of S. Typhimurium in D. discoideum and the ability of these strains to delay the social development of the amoeba. In contrast to the wild-type strain, the Δppk mutant was unable to survive intracellularly in D. discoideum and enabled the social development of the amoeba. Both phenotypes were complemented using a plasmid carrying a copy of the ppk gene. Next, we simultaneously evaluated the proteomic response of both S. Typhimurium and D. discoideum during host-pathogen interaction via global proteomic profiling. The analysis of our results allowed the identification of novel molecular signatures that give insight into

  5. Dual protection of wood surface treated with melamine-modified urea-formaldehyde resin mixed with ammonium polyphosphate against both fire and decay

    Science.gov (United States)

    Xing-xia Ma; Grant T. Kirker; Ming-liang Jiang; Yu-zhang Wu

    2016-01-01

    Surface coatings of melamine-modified urea-formaldehyde resins (MUFs) containing ammonium polyphosphate (APP) have been shown to significantly improve the fire retardancy of wood by prolonging the ignition time and reducing the heat release rate, total heat released, and mass loss rate. Dual protection of wood against both decay and fire has been proposed for remedial...

  6. Polymer gel dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Baldock, C [Institute of Medical Physics, School of Physics, University of Sydney (Australia); De Deene, Y [Radiotherapy and Nuclear Medicine, Ghent University Hospital (Belgium); Doran, S [CRUK Clinical Magnetic Resonance Research Group, Institute of Cancer Research, Surrey (United Kingdom); Ibbott, G [Radiation Physics, UT M D Anderson Cancer Center, Houston, TX (United States); Jirasek, A [Department of Physics and Astronomy, University of Victoria, Victoria, BC (Canada); Lepage, M [Centre d' imagerie moleculaire de Sherbrooke, Departement de medecine nucleaire et de radiobiologie, Universite de Sherbrooke, Sherbrooke, QC (Canada); McAuley, K B [Department of Chemical Engineering, Queen' s University, Kingston, ON (Canada); Oldham, M [Department of Radiation Oncology, Duke University Medical Center, Durham, NC (United States); Schreiner, L J [Cancer Centre of South Eastern Ontario, Kingston, ON (Canada)], E-mail: c.baldock@physics.usyd.edu.au, E-mail: yves.dedeene@ugent.be

    2010-03-07

    Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose gradients exist such as in intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery. Polymer gel dosimeters also have specific advantages for brachytherapy dosimetry. Potential dosimetry applications include those for low-energy x-rays, high-linear energy transfer (LET) and proton therapy, radionuclide and boron capture neutron therapy dosimetries. These 3D dosimeters are radiologically soft-tissue equivalent with properties that may be modified depending on the application. The 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound. The fundamental science underpinning polymer gel dosimetry is reviewed along with the various evaluation techniques. Clinical dosimetry applications of polymer gel dosimetry are also presented. (topical review)

  7. Amorphous, Smart, and Bioinspired Polyphosphate Nano/Microparticles: A Biomaterial for Regeneration and Repair of Osteo-Articular Impairments In-Situ

    Directory of Open Access Journals (Sweden)

    Werner E. G. Müller

    2018-01-01

    Full Text Available Using femur explants from mice as an in vitro model, we investigated the effect of the physiological polymer, inorganic polyphosphate (polyP, on differentiation of the cells of the bone marrow in their natural microenvironment into the osteogenic and chondrogenic lineages. In the form of amorphous Ca-polyP nano/microparticles, polyP retains its function to act as both an intra- and extracellular metabolic fuel and a stimulus eliciting morphogenetic signals. The method for synthesis of the nano/microparticles with the polyanionic polyP also allowed the fabrication of hybrid particles with the bisphosphonate zoledronic acid, a drug used in therapy of bone metastases in cancer patients. The results revealed that the amorphous Ca-polyP particles promote the growth/viability of mesenchymal stem cells, as well as the osteogenic and chondrogenic differentiation of the bone marrow cells in rat femur explants, as revealed by an upregulation of the expression of the transcription factors SOX9 (differentiation towards osteoblasts and RUNX2 (chondrocyte differentiation. In parallel to this bone anabolic effect, incubation of the femur explants with these particles significantly reduced the expression of the gene encoding the osteoclast bone-catabolic enzyme, cathepsin-K, while the expression of the tartrate-resistant acid phosphatase remained unaffected. The gene expression data were supported by the finding of an increased mineralization of the cells in the femur explants in response to the Ca-polyP particles. Finally, we show that the hybrid particles of polyP complexed with zoledronic acid exhibit both the cytotoxic effect of the bisphosphonate and the morphogenetic and mineralization inducing activity of polyP. Our results suggest that the Ca-polyP nano/microparticles are not only a promising scaffold material for repairing long bone osteo-articular damages but can also be applied, as a hybrid with zoledronic acid, as a drug delivery system for

  8. Design of Autonomous Gel Actuators

    Directory of Open Access Journals (Sweden)

    Shuji Hashimoto

    2011-01-01

    Full Text Available In this paper, we introduce autonomous gel actuators driven by chemical energy. The polymer gels prepared here have cyclic chemical reaction networks. With a cyclic reaction, the polymer gels generate periodical motion. The periodic motion of the gel is produced by the chemical energy of the oscillatory Belouzov-Zhabotinsky (BZ reaction. We have succeeded in making synthetic polymer gel move autonomously like a living organism. This experimental fact represents the great possibility of the chemical robot.

  9. Review of Fricke gel dosimeters

    International Nuclear Information System (INIS)

    Schreiner, L J

    2004-01-01

    The innovation of adding a gel matrix to the traditional Fricke dosimeter to stabilize geometric information established the field of gel dosimetry for radiation therapy. A discussion of Fricke gels provides an overview of the issues that determine the dose response of all gel dosimeters in general. In this paper we review some of the features of Fricke systems to illustrate these issues and, in addition, to motivate renewed clinical interest in Fricke gels

  10. Sol-gel chemistry applied to the synthesis of polymetallic oxides including actinides reactivity and structure from solution to solid state; Synthese par voie douce d'oxydes polymetalliques incluant des actinides: reactivite et structure de la solution au solide

    Energy Technology Data Exchange (ETDEWEB)

    Lemonnier, St

    2006-02-15

    Minor actinides transmutation is studied at present in order to reduce the radiotoxicity of nuclear waste and the assessment of its technical feasibility requires specific designed materials. When considering americium, yttria stabilized zirconia (Am{sup III} YII Zriv)Or{sub x} is among the ceramic phases that one which presents the required physico-chemical properties. An innovative synthesis of this mixed oxide by sol-gel process is reported in this manuscript. The main aim of this work is to adjust the reactivity of the different metallic cations in aqueous media using complexing agent, in order to initiate a favourable interaction for a homogeneous elements repartition in the forming solid phase. The originality of the settled synthesis lies on an in-situ formation of a stable and monodisperse nano-particles dispersion in the presence of acetylacetone. The main reaction mechanisms have been identified: the sol stabilisation results from an original interaction between the three compounds (Zrly, trivalent cations and acetylacetone). The sol corresponds to a structured system at the nanometer scale for which zirconium and trivalent cations are homogeneously dispersed, preliminary to the sol-gel transition. Furthermore, preliminary studies were carried out with a view to developing materials. They have demonstrated that numerous innovative and potential applications can be developed by taking advantage of the direct and controlled formation of the sol and by adapting the sol-gel transition. The most illustrating result is the preparation of a sintered pellet with the composition Am0,13Zro,73Yo,0901,89 using this approach. (author)

  11. 3D MR gel dosimetry with lung equivalent gel

    International Nuclear Information System (INIS)

    Scherer, J.; Solleder, M.; Schiessl, I.; Bogner, L.; Herbst, M.

    1998-01-01

    The MR gel dosimetry is used to verify complex 3D treatment plans. Till now this method served only for dose evaluation in homogeneous phantoms. On the way to build a heterogeneous anthropomorphic gel phantom, a lung equivalent gel with the density 0.4 g/cm 3 was developed. First experiments show a 1.55 times higher dose reponse in the low density gel (LD gel). The comparison of a dose distribution in a gel/LD gel/gel slab phantom with Monte Carlo calculations shows good agreement within 5%. More over the accuray of the measuring device magnetic resonance imager was studied in respect to the now exclusive digital image processing with the software MRD (MR dosimetry). Because of the dimensions of the Fricke gel phantom an artefact correction, based on the data from the unirradiated phantom proved to be essential. (orig.) [de

  12. Structure of mineral gels

    International Nuclear Information System (INIS)

    Miranda Salvado, I.M.; Margaca, F.M.A.; Teixeira, J.

    1999-01-01

    Small Angle Neutron Scattering (SANS) measurements have been performed to investigate the nanoscale structure of materials of the systems xTiO 2 -(1-x)SiO 2 and xZrO 2 -(1-x)SiO 2 with x ≤ 10 mol % at different processing stages. The materials were prepared by sol-gel using the alkoxides method, in strong acidic conditions. Samples were studied as xerogels heat-treated at 120 and 850 deg. C and as wet gels at gel point and after aging. All samples showed identical microstructure at gel point, extended linear chains ∼10 nm long. The aged gel has a mass fractal structure with fractal dimension of 1.7 - 1.9. The 120 deg. C heat-treated xerogels show homogeneous oxide regions with mass fractal structure. For the 850 deg. C heat-treated xerogel the oxide regions average size has reduced and it has densified as compared to 120 deg. C heat-treated sample. (author)

  13. Structure determination, electronic and optical properties of rubidium holmium polyphosphate RbHo(PO3)4

    Science.gov (United States)

    Zhu, Jing; Chen, Hui; Wang, Yude; Guan, Hongtao; Xiao, Xuechun

    2012-12-01

    Structural, optical, and electronic properties of a new alkali metal-rare earth polyphosphate, RbHo(PO3)4, have been investigated by means of single-crystal X-ray diffraction, power X-ray diffraction, elemental analysis, and spectral measurement. RbHo(PO3)4 crystallizes in the monoclinic with space group P21/n and Z = 4. It is described as a three-dimensional (3D) architecture built up of PO4 double spiral chains and HoO8 polyhedra by corner-sharing. The 11-coordinated rubidium atoms are located in infinite tunnels. Additionally, in order to gain further insight into the relationship between property and structure of RbHo(PO3)4, theoretical calculation based on the density functional theory (DFT) was performed using the total-energy code CASTEP.

  14. Inositol polyphosphate multikinase is a coactivator for serum response factor-dependent induction of immediate early genes

    Science.gov (United States)

    Kim, Eunha; Tyagi, Richa; Lee, Joo-Young; Park, Jina; Kim, Young-ran; Beon, Jiyoon; Chen, Po Yu; Cha, Jiyoung Y.; Snyder, Solomon H.; Kim, Seyun

    2013-01-01

    Inositol polyphosphate multikinase (IPMK) is a notably pleiotropic protein. It displays both inositol phosphate kinase and phosphatidylinositol kinase catalytic activities. Noncatalytically, IPMK stabilizes the mammalian target of rapamycin complex 1 and acts as a transcriptional coactivator for CREB-binding protein/E1A binding protein p300 and tumor suppressor protein p53. Serum response factor (SRF) is a major transcription factor for a wide range of immediate early genes. We report that IPMK, in a noncatalytic role, is a transcriptional coactivator for SRF mediating the transcription of immediate early genes. Stimulation by serum of many immediate early genes is greatly reduced by IPMK deletion. IPMK stimulates expression of these genes, an influence also displayed by catalytically inactive IPMK. IPMK acts by binding directly to SRF and thereby enhancing interactions of SRF with the serum response element of diverse genes. PMID:24248338

  15. Surprising luminescent properties of the polyphosphates Ln(PO3)3:Eu (Ln = Y, Gd, Lu).

    Science.gov (United States)

    Höppe, Henning A; Kazmierczak, Karolina; Kacprzak, Sylwia; Schellenberg, Inga; Pöttgen, Rainer

    2011-10-21

    The optical emission properties of the lanthanoid catena-polyphosphates Ln(PO(3))(3) (Ln = Y, Gd, Lu) doped with europium were investigated. Incommensurately modulated β-Y(PO(3))(3):Eu (super space group Cc (0|0.364|0)0) and Gd(PO(3))(3):Eu (space group I2/a) show the usual emission characteristics of Eu(3+), while in Lu(PO(3))(3):Eu (space group Cc) the europium is unprecedentedly partially reduced to the divalent state, as proven by both a broad emission band at 406 nm excited at 279 nm and an EPR spectroscopic investigation. (151)Eu-Mössbauer spectroscopy showed that only a very small part of the europium is reduced in Lu(PO(3))(3):Eu. An explanation for this unusual behaviour is given. This journal is © The Royal Society of Chemistry 2011

  16. Process optimization by decoupled control of key microbial populations: distribution of activity and abundance of polyphosphate-accumulating organisms and nitrifying populations in a full-scale IFAS-EBPR plant

    DEFF Research Database (Denmark)

    Onnis-Hayden, Annalisa; Majed, Nehreen; Schramm, Andreas

    2011-01-01

    This study investigated the abundance and distribution of key functional microbial populations and their activities in a full-scale integrated fixed film activated sludgeeenhanced biological phosphorus removal (IFAS-EBPR) process. Polyphosphate accumulating organisms (PAOs) including Accumulibacter...

  17. Gel electrolytes and electrodes

    Science.gov (United States)

    Fleischmann, Sven; Bunte, Christine; Mikhaylik, Yuriy V.; Viner, Veronika G.

    2017-09-05

    Gel electrolytes, especially gel electrolytes for electrochemical cells, are generally described. In some embodiments, the gel electrolyte layers comprise components a) to c). Component a) may be at least one layer of at least one polymer comprising polymerized units of: a1) at least one monomer containing an ethylenically unsaturated unit and an amido group and a2) at least one crosslinker. Component b) may be at least one conducting salt and component c) may be at least one solvent. Electrodes may comprise the components a), d) and e), wherein component a) may be at least one layer of at least one polymer as described herein. Component d) may be at least one electroactive layer and component e) may be at least one ceramic layer. Furthermore, electrochemical cells comprising component a) which may be at least one layer of at least one polymer as described herein, are also provided.

  18. Electroblotting from Polyacrylamide Gels.

    Science.gov (United States)

    Goldman, Aaron; Ursitti, Jeanine A; Mozdzanowski, Jacek; Speicher, David W

    2015-11-02

    Transferring proteins from polyacrylamide gels onto retentive membranes is now primarily used for immunoblotting. A second application that was quite common up to about a decade ago was electroblotting of proteins for N-terminal and internal sequencing using Edman chemistry. This unit contains procedures for electroblotting proteins from polyacrylamide gels onto a variety of membranes, including polyvinylidene difluoride (PVDF) and nitrocellulose. In addition to the commonly used tank or wet transfer system, protocols are provided for electroblotting using semidry and dry systems. This unit also describes procedures for eluting proteins from membranes using detergents or acidic extraction with organic solvents for specialized applications. Copyright © 2015 John Wiley & Sons, Inc.

  19. gel template method

    Indian Academy of Sciences (India)

    TiO2 nanotubes have been synthesized by sol–gel template method using alumina membrane. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, UV absorption spectrum and X-ray diffraction techniques have been used to investigate the structure, morphology and optical ...

  20. Transdermal delivery of paeonol using cubic gel and microemulsion gel

    Science.gov (United States)

    Luo, Maofu; Shen, Qi; Chen, Jinjin

    2011-01-01

    Background The aim of this study was to develop new systems for transdermal delivery of paeonol, in particular microemulsion gel and cubic gel formulations. Methods Various microemulsion vehicles were prepared using isopropyl myristate as an oil phase, polyoxyethylated castor oil (Cremophor® EL) as a surfactant, and polyethylene glycol 400 as a cosurfactant. In the optimum microemulsion gel formulation, carbomer 940 was selected as the gel matrix, and consisted of 1% paeonol, 4% isopropyl myristate, 28% Cremophor EL/polyethylene glycol 400 (1:1), and 67% water. The cubic gel was prepared containing 3% paeonol, 30% water, and 67% glyceryl monooleate. Results A skin permeability test using excised rat skins indicated that both the cubic gel and microemulsion gel formulations had higher permeability than did the paeonol solution. An in vivo pharmacokinetic study done in rats showed that the relative bioavailability of the cubic gel and microemulsion gel was enhanced by about 1.51-fold and 1.28-fold, respectively, compared with orally administered paeonol suspension. Conclusion Both the cubic gel and microemulsion gel formulations are promising delivery systems to enhance the skin permeability of paeonol, in particular the cubic gel. PMID:21904450

  1. Intraosseous phlebography, intraosseous pressure measurements and sup(99m)Tc-polyphosphate scintigraphy in patients with various painful conditions in the hip and knee

    International Nuclear Information System (INIS)

    Arnoldi, C.C.; Djurhuus, J.C.; Heerfordt, J.; Karle, A.

    1980-01-01

    Twenty-five patients with pain in the knee or hip were examined by means of bilateral intraosseous phlebography, intraosseous pressure measurements and sup(99m) technetium polyphosphate scintigraphy. All patients with typical rest pain - either due to osteoarthritis or to the intraosseous engorgement-pain syndrome - showed venous statis and increased pressure in the bone marrow near the painful joint and abnormally high uptake of the radiotracer. In patients with other types of pain this correlation was absent. The results indicate that sup(99m)technetium polyphosphate scintigraphy can be used as a screening method in the diagnosis of the intraosseous engorgement-pain syndrome in patients with a typical history. However, increased isotope uptake in a joint region may be due to a variety of other causes. The identical findings with all three methods of investigation in patients with the intraosseous engorgement-pain syndrome and osteoarthritis suggest a common pathomechanism. (author)

  2. Improved Prediction of Phosphorus Dynamics in Biotechnological Processes by Considering Precipitation and Polyphosphate Formation: A Case Study on Antibiotic Production with Streptomyces coelicolor

    DEFF Research Database (Denmark)

    Bürger, Patrick; Flores-Alsina, Xavier; Arellano-Garcia, Harvey

    2018-01-01

    The multiplicity of physicochemical and biological processes, where phosphorus is involved, makes their accurate prediction using current mathematical models in biotechnology quite a challenge. In this work, an antibiotic production model of Streptomyces coelicolor is chosen as a representative...... approach describing intracellular polyphosphate accumulation and consumption has been developed and implemented. A heuristic re-estimation of selected parameters is carried out to improve overall model performance. The improved process model predicts phosphate dynamics (root mean squared error ≤52h: −90...

  3. Endoplasmic reticulum stress-induced apoptosis accompanies enhanced expression of multiple inositol polyphosphate phosphatase 1 (Minpp1): a possible role for Minpp1 in cellular stress response.

    Science.gov (United States)

    Kilaparty, Surya P; Agarwal, Rakhee; Singh, Pooja; Kannan, Krishnaswamy; Ali, Nawab

    2016-07-01

    Inositol polyphosphates represent a group of differentially phosphorylated inositol metabolites, many of which are implicated to regulate diverse cellular processes such as calcium mobilization, vesicular trafficking, differentiation, apoptosis, etc. The metabolic network of these compounds is complex and tightly regulated by various kinases and phosphatases present predominantly in the cytosol. Multiple inositol polyphosphate phosphatase 1 (Minpp1) is the only known endoplasmic reticulum (ER) luminal enzyme that hydrolyzes various inositol polyphosphates in vitro as well as in vivo conditions. However, access of the Minpp1 to cytosolic substrates has not yet been demonstrated clearly and hence its physiological function. In this study, we examined a potential role for Minpp1 in ER stress-induced apoptosis. We generated a custom antibody and characterized its specificity to study the expression of Minpp1 protein in multiple mammalian cells under experimentally induced cellular stress conditions. Our results demonstrate a significant increase in the expression of Minpp1 in response to a variety of cellular stress conditions. The protein expression was corroborated with the expression of its mRNA and enzymatic activity. Further, in an attempt to link the role of Minpp1 to apoptotic stress, we studied the effect of Minpp1 expression on apoptosis following silencing of the Minpp1 gene by its specific siRNA. Our results suggest an attenuation of apoptotic parameters following knockdown of Minpp1. Thus, in addition to its known role in inositol polyphosphate metabolism, we have identified a novel role for Minpp1 as a stress-responsive protein. In summary, our results provide, for the first time, a probable link between ER stress-induced apoptosis and Minpp1 expression.

  4. Studies on the influences of. gamma. -ray irradiation upon food additives, (8). Influences of. gamma. -ray irradiation on polyphosphates in aqueous solution and in 'kamaboko'

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, M; Ishio, S [Kyushu Univ., Fukuoka (Japan). Faculty of Agriculture

    1981-08-01

    The effect of ..gamma..-ray irradiation on polyphosphates in aqueous solution and in ''kamaboko'' was investigated to evaluate the rate of decomposition and to examine the safety of the decomposed products. Tripolyphosphate, pyrophosphate and o-phosphate in aqueous solution were very stable against ..gamma..-ray irradiation, respectively. Tripolyphosphate added to ''surimi'' (minced and washed flesh of Alaska Pollack) completely changed to o-phosphate during the period of processing ''kamaboko'', but pyrophosphate was retained. Pyrophosphate content in ''kamaboko'' decreased in proportion to the dose of ..gamma..-ray. Decreased pyrophosphate was presumed to change into such products as insolubles which can not be extracted with 6% per chloric acid solution. Both tripolyphosphate and pyrophosphate changed enzymatically to o-phosphate. The activity of exopolyphosphatase in ''surimi'' was still retained. Polyphosphates added to ''surimi'' changed completely to o-phosphate during the frozen storage of ''surimi'', therefore, the application of ..gamma..-ray irradiation on ''kamaboko'' was considered not to induce any injurious substances from polyphosphates.

  5. Microwave assisted highly efficient one-pot multi-component synthesis of novel 2-(tetrasubstituted-1H-pyrrol-3-yl-4H-chroman-4-ones catalyzed by heterogeneous reusable silica gel supported polyphosphoric acid (PPA/SiO2

    Directory of Open Access Journals (Sweden)

    Sumit Kumar

    2018-02-01

    Full Text Available A solvent-free, eco-friendly and facile approach for the synthesis of highly functionalized tetrasubstituted pyrroles has been reported through one-pot four-component reaction of aldehyde, amine, nitroalkane and 1,3-diketone using silica gel supported polyphosphoric acid (PPA–SiO2 under microwave condition. The reaction occured through the in situ formation of β-keto enamine and nitrostyrene analog following Michael addition and finally intramolecular annulation affording the products in good yields. The key features of the present method include clean reaction, mild conditions, low catalyst loading, straightforward, high to excellent yields, short reaction time, avoiding use of harmful metal catalyst and organic solvent, environmentally friendly compared to the existing methods, recovery and reusability of catalyst and easy workup procedure.

  6. Sol-Gel Synthesis of La(0.6)Sr(0.4)CoO(3-x) and Sm(0.5)Sr(0.5)CoO(3-x) Cathode Nanopowders for Solid Oxide Fuel Cells

    Science.gov (United States)

    Bansal, Narottam P.; Wise, Brent

    2011-01-01

    Nanopowders of La(0.6)Sr(0.4)CoO(3-x) (LSC) and Sm(0.5)Sr(0.5)CoO(3-x) (SSC) compositions, which are being investigated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFC) with La(Sr)Ga(Mg)O(3-x) (LSGM) as the electrolyte, were synthesized by low-temperature sol-gel method using metal nitrates and citric acid. Thermal decomposition of the citrate gels was followed by simultaneous DSC/TGA methods. Development of phases in the gels, on heat treatments at various temperatures, was monitored by x-ray diffraction. Solgel powders calcined at 550 to 1000 C consisted of a number of phases. Single perovskite phase La(0.6)Sr(0.4)CoO(3-x) or Sm(0.5)Sr(0.5)CoO(3-x) powders were obtained at 1200 and 1300 C, respectively. Morphological analysis of the powders calcined at various temperatures was done by scanning electron microscopy. The average particle size of the powders was approx.15 nm after 700 C calcinations and slowly increased to 70 to 100 nm after heat treatments at 1300 to 1400 C.

  7. The Gel Generator option

    International Nuclear Information System (INIS)

    Boyd, R.E.

    1999-01-01

    The development of a national policy for guaranteeing an ample supply of 99m Tc to nuclear medicine, involves issues which go beyond the means by which radioactivation is achieved. Indeed, in such an exercise the pragmatic dictates of business and the sensitivities of politics must also be taken into account. Furthermore where a preference towards the nuclear reactor or the potential of cyclotrons is being questioned, the debate is incomplete if the only options that are considered are the fission-based 99 Mo generator versus the direct cyclotron production of 99m Tc. There is a third option (also neutron γ-based), an alternative to the fission 99 Mo generator, which ought not be overlooked. The application of low specific activity (n,γ) 99 Mo to a new type of generator, the Gel Generator, has been the focus of much research, particularly in Australia and more recently in China. After the initial concept had been established in the laboratory, the Australian researchers then undertook a comprehensive program of tests on the Gel Generator to assess its potential, either in the clinical laboratory or the centralised radiopharmacy, for supplying 99m Tc suitable for nuclear medicine. The outcome of this program was a clear indication that the Gel Generator innovation had the capability to provide both technical and economic advantages to the nuclear medicine industry. These advantages are described. Since that time the Gel Generator has been selected for routine use in China where it now satisfies more than 30% of the 99m Tc demand. (author)

  8. Chiromagnetic nanoparticles and gels

    Science.gov (United States)

    Yeom, Jihyeon; Santos, Uallisson S.; Chekini, Mahshid; Cha, Minjeong; de Moura, André F.; Kotov, Nicholas A.

    2018-01-01

    Chiral inorganic nanostructures have high circular dichroism, but real-time control of their optical activity has so far been achieved only by irreversible chemical changes. Field modulation is a far more desirable path to chiroptical devices. We hypothesized that magnetic field modulation can be attained for chiral nanostructures with large contributions of the magnetic transition dipole moments to polarization rotation. We found that dispersions and gels of paramagnetic Co3O4 nanoparticles with chiral distortions of the crystal lattices exhibited chiroptical activity in the visible range that was 10 times as strong as that of nonparamagnetic nanoparticles of comparable size. Transparency of the nanoparticle gels to circularly polarized light beams in the ultraviolet range was reversibly modulated by magnetic fields. These phenomena were also observed for other nanoscale metal oxides with lattice distortions from imprinted amino acids and other chiral ligands. The large family of chiral ceramic nanostructures and gels can be pivotal for new technologies and knowledge at the nexus of chirality and magnetism.

  9. Anaerobic/oxic/anoxic granular sludge process as an effective nutrient removal process utilizing denitrifying polyphosphate-accumulating organisms.

    Science.gov (United States)

    Kishida, Naohiro; Kim, Juhyun; Tsuneda, Satoshi; Sudo, Ryuichi

    2006-07-01

    In a biological nutrient removal (BNR) process, the utilization of denitrifying polyphosphate-accumulating organisms (DNPAOs) has many advantages such as effective use of organic carbon substrates and low sludge production. As a suitable process for the utilization of DNPAOs in BNR, an anaerobic/oxic/anoxic granular sludge (AOAGS) process was proposed in this study. In spite of performing aeration for nitrifying bacteria, the AOAGS process can create anaerobic/anoxic conditions suitable for the cultivation of DNPAOs because anoxic zones exist inside the granular sludge in the oxic phase. Thus, DNPAOs can coexist with nitrifying bacteria in a single reactor. In addition, the usability of DNPAOs in the reactor can be improved by adding the anoxic phase after the oxic phase. These characteristics enable the AOAGS process to attain effective removal of both nitrogen and phosphorus. When acetate-based synthetic wastewater (COD: 600 mg/L, NH4-N: 60 mg/L, PO(4)-P: 10 mg/L) was supplied to a laboratory-scale sequencing batch reactor under the operation of anaerobic/oxic/anoxic cycles, granular sludge with a diameter of 500 microm was successfully formed within 1 month. Although the removal of both nitrogen and phosphorus was almost complete at the end of the oxic phase, a short anoxic period subsequent to the oxic phase was necessary for further removal of nitrogen and phosphorus. As a result, effluent concentrations of NH(4)-N, NO(x)-N and PO(4)-P were always lower than 1 mg/L. It was found that penetration depth of oxygen inside the granular sludge was approximately 100 microm by microsensor measurements. In addition, from the microbiological analysis by fluorescence in situ hybridization, existence depth of polyphosphate-accumulating organisms was further than the maximum oxygen penetration depth. The water quality data, oxygen profiles and microbial community structure demonstrated that DNPAOs inside the granular sludge may be responsible for denitrification in the

  10. Sol-gel processing of bioactive glass nanoparticles: A review.

    Science.gov (United States)

    Zheng, Kai; Boccaccini, Aldo R

    2017-11-01

    Silicate-based bioactive glass nanoparticles (BGN) are gaining increasing attention in various biomedical applications due to their unique properties. Controlled synthesis of BGN is critical to their effective use in biomedical applications since BGN characteristics, such as morphology and composition, determining the properties of BGN, are highly related to the synthesis process. In the last decade, numerous investigations focusing on BGN synthesis have been reported. BGN can mainly be produced through the conventional melt-quench approach or by sol-gel methods. The latter approaches are drawing widespread attention, considering the convenience and versatility they offer to tune the properties of BGN. In this paper, we review the strategies of sol-gel processing of BGN, including those adopting different catalysts for initiating the hydrolysis and condensation of silicate precursors as well as those combining sol-gel chemistry with other techniques. The processes and mechanism of different synthesis approaches are introduced and discussed in detail. Considering the importance of the BGN morphology and composition to their biomedical applications, strategies put forward to control the size, shape, pore structure and composition of BGN are discussed. BGN are particularly interesting biomaterials for bone-related applications, however, they also have potential for other biomedical applications, e.g. in soft tissue regeneration/repair. Therefore, in the last part of this review, recently reported applications of BGN in soft tissue repair and wound healing are presented. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Radiotherapy gel dosimetry

    International Nuclear Information System (INIS)

    Baldock, C.

    2002-01-01

    shapes and sizes while sparing normal tissue. The situation is further complicated if the normal tissues are critical organs or are particularly sensitive to radiation. Radiotherapy techniques employed to obtain a closer conformation of the dose distribution to the tumour volume are referred to as conformal radiotherapy techniques. The clinical implementation of conformal therapy has been delayed by limitations in the verification of conformal dose distributions calculated by treatment planning systems prior to the irradiation of the patient and the verification of complex treatments during its delivery to the patient. There are several aspects of conformal therapy that complicate dose verification. To achieve the dose distributions conforming to complex 3D volumes, high dose gradients arise in the treatment volume. Further, overdose or underdose regions can exist when separate radiation fields are used to deliver additional radiation. These aspects require that practical dose measurement (dosimetry) techniques be able to integrate dose over time and easily measure dose distributions in 3D with high spatial resolution. Traditional dosimeters, such as ion chambers, thermoluminescent dosimeters and radiographic film do not fulfil these requirements. Novel gel dosimetry techniques are being developed in which dose distributions can potentially be determined in vitro in 3D using anthropomorphic phantoms to simulate a clinically irradiated situation. As long ago as the 1950's, radiation-induced colour change in dyes was used to investigate radiation doses in gels. It was subsequently shown that radiation induced changes in nuclear magnetic resonance (NMR) relaxation properties of gels infused with conventional Fricke dosimetry solutions could be measured using magnetic resonance imaging (MRI). In Fricke gels, Fe 2+ ions in ferrous sulphate solutions are usually dispersed throughout a gelatin, agarose or PVA matrix. Radiation-induced changes in the dosimeters are considered to

  12. Evaluation of salt, polyphosphates and their blends at different levels on physicochemical properties of buffalo meat and patties.

    Science.gov (United States)

    Anjaneyulu, A S; Sharma, N; Kondaiah, N

    1989-01-01

    The effects of sodium pyrophosphate (SPP), sodium tripolyphosphate (STPP), sodium hexametaphosphate (SHMP), sodium acid pyrophosphate (SAPP) and their blends at different levels (0·3, 0·5 and 0·7%), along with 2% sodium chloride on certain quality parameters of buffalo meat and patties were evaluated. The SPP, STPP and phosphate blends significantly increased pH, water-holding capacity (WHC), emulsifying capacity (EC), extractability of salt soluble proteins (SSP), colour of ground meat, decreased cooking loss (CL), improved emulsion stability (ES) and enhanced yield, texture and moisture retention of cooked patties. Compared to these phosphates, SAPP and SHMP had significantly poorer effects on improving the quality of meat and patties. The order of effectiveness of phosphates was SPP > STPP > SHMP. In general, pH, WHC, SSP, ES, yield and moisture content of patties increased progressively with increasing level of phosphate while CL decreased. Among blends containing two polyphosphates, those of 90% SPP + 10% SHMP and 75% SPP + 25% STPP were relatively more effective. A phosphate blend consisting of 65% SPP, 17·5% STPP and 17·5% SAPP was equally effective as that of SPP in improving the functionality of hot and chilled meat and had the advantage of reducing the amount of sodium by 3%. Copyright © 1989. Published by Elsevier Ltd.

  13. Low acetate concentrations favor polyphosphate-accumulating organisms over glycogen-accumulating organisms in enhanced biological phosphorus removal from wastewater.

    Science.gov (United States)

    Tu, Yunjie; Schuler, Andrew J

    2013-04-16

    Glycogen-accumulating organisms (GAOs) are thought to compete with polyphosphate-accumulating organisms (PAOs) in enhanced biological phosphorus removal (EBPR) wastewater treatment systems. A laboratory sequencing batch reactor (SBR) was operated for one year to test the hypothesis that PAOs have a competitive advantage at low acetate concentrations, with a focus on low pH conditions previously shown to favor GAOs. PAOs dominated the system under conventional SBR operation with rapid acetate addition (producing high in-reactor concentrations) and pH values of 7.4-8.4. GAOs dominated when the pH was decreased (6.4-7.0). Decreasing the acetate addition rate led to very low reactor acetate concentrations, and PAOs recovered, supporting the study hypothesis. When the acetate feed rate was increased, EBPR failed again. Dominant PAOs and GAOs were Candidatus Accumulibacter phosphatis and Defluviicoccus Cluster 2, respectively, according to fluorescent in situ hybridization and 454 pyrosequencing. Surprisingly, GAOs were not the immediate causes of PAO failures, based on functional and population measurements. Pyrosequencing results suggested Dechloromonas and Tetrasphaera spp. may have also been PAOs, and additional potential GAOs were also identified. Full-scale systems typically have lower in-reactor acetate concentrations than laboratory SBRs, and so, previous laboratory studies may have overestimated the practical importance of GAOs as causes of EBPR failure.

  14. The Vip1 inositol polyphosphate kinase family regulates polarized growth and modulates the microtubule cytoskeleton in fungi.

    Directory of Open Access Journals (Sweden)

    Jennifer Pöhlmann

    2014-09-01

    Full Text Available Microtubules (MTs are pivotal for numerous eukaryotic processes ranging from cellular morphogenesis, chromosome segregation to intracellular transport. Execution of these tasks requires intricate regulation of MT dynamics. Here, we identify a new regulator of the Schizosaccharomyces pombe MT cytoskeleton: Asp1, a member of the highly conserved Vip1 inositol polyphosphate kinase family. Inositol pyrophosphates generated by Asp1 modulate MT dynamic parameters independent of the central +TIP EB1 and in a dose-dependent and cellular-context-dependent manner. Importantly, our analysis of the in vitro kinase activities of various S. pombe Asp1 variants demonstrated that the C-terminal phosphatase-like domain of the dual domain Vip1 protein negatively affects the inositol pyrophosphate output of the N-terminal kinase domain. These data suggest that the former domain has phosphatase activity. Remarkably, Vip1 regulation of the MT cytoskeleton is a conserved feature, as Vip1-like proteins of the filamentous ascomycete Aspergillus nidulans and the distantly related pathogenic basidiomycete Ustilago maydis also affect the MT cytoskeleton in these organisms. Consistent with the role of interphase MTs in growth zone selection/maintenance, all 3 fungal systems show aspects of aberrant cell morphogenesis. Thus, for the first time we have identified a conserved biological process for inositol pyrophosphates.

  15. In Situ Formation of Steroidal Supramolecular Gels Designed for Drug Release

    Directory of Open Access Journals (Sweden)

    Hana Bunzen

    2013-03-01

    Full Text Available In this work, a steroidal gelator containing an imine bond was synthesized, and its gelation behavior as well as a sensitivity of its gels towards acids was investigated. It was shown that the gels were acid-responsive, and that the gelator molecules could be prepared either by a conventional synthesis or directly in situ during the gel forming process. The gels prepared by both methods were studied and it was found that they had very similar macro- and microscopic properties. Furthermore, the possibility to use the gels as carriers for aromatic drugs such as 5-chloro-8-hydroxyquinoline, pyrazinecarboxamide, and antipyrine was investigated and the prepared two-component gels were studied with regard to their potential applications in drug delivery, particularly in a pH-controlled drug release.

  16. High transparent shape memory gel

    Science.gov (United States)

    Gong, Jin; Arai, Masanori; Kabir, M. H.; Makino, Masato; Furukawa, Hidemitsu

    2014-03-01

    Gels are a new material having three-dimensional network structures of macromolecules. They possess excellent properties as swellability, high permeability and biocompatibility, and have been applied in various fields of daily life, food, medicine, architecture, and chemistry. In this study, we tried to prepare new multi-functional and high-strength gels by using Meso-Decoration (Meso-Deco), one new method of structure design at intermediate mesoscale. High-performance rigid-rod aromatic polymorphic crystals, and the functional groups of thermoreversible Diels-Alder reaction were introduced into soft gels as crosslinkable pendent chains. The functionalization and strengthening of gels can be realized by meso-decorating the gels' structure using high-performance polymorphic crystals and thermoreversible pendent chains. New gels with good mechanical properties, novel optical properties and thermal properties are expected to be developed.

  17. Acquisition of a Scanning Ultrasound Analyzer for Gelation and Drying Studies in Sol-Gel Ceramic Coatings and Monoliths

    National Research Council Canada - National Science Library

    Archer, Lynden

    1997-01-01

    The overall goal of this research project was to develop a fundamental understanding of how colloid chemistry influences structure and properties of ceramic monoliths fabricated by sol-gel synthesis...

  18. Synthesis, spectroscopic characterization of palladium(II)-orthohydroxyacetophenone azine nano-optical sensor doped in sol–gel matrix and its use as probe for assessment of α-amylase activity in human saliva

    Energy Technology Data Exchange (ETDEWEB)

    El-Sayed, B.A. [Chemistry department, Faculty of Science, al Azhr University, Cairo (Egypt); Abo-Aly, M.M., E-mail: aboalymoh@hotmail.com [Chemistry department, Faculty of Science, Ain Shams University, Cairo (Egypt); Attia, M.S.; Gamal, S. [Chemistry department, Faculty of Science, Ain Shams University, Cairo (Egypt)

    2016-01-15

    PdAPA (palladium(II)-orthohydroxyacetophenone azine) complex doped in sol–gel matrix is synthesized. It is characterized using UV-visible, infrared spectra and TEM image. A novel, simple, sensitive spectrofluorometric method was developed for measuring the activity of the α-amylase enzyme in human saliva for smokers and non-smokers with age range (17–64 years) based on the quenching of the luminescence intensity at 450 nm of the new synthesized complex characterized by various concentrations of the maltose released from the hydrolysis of starch by α-amylase enzyme and was successfully used as nano-optical sensor. The calibration plot was achieved over the concentration range 4.7×10{sup −6}–9.3×10{sup −10} mol L{sup −1} maltose with a correlation coefficient of 0.996 and a detection minimum limit value of 7.55×10{sup −10} mol L{sup −1}. The method was satisfactorily used for the assessment of the α-amylase activity in a number of human saliva samples for various smokers and non-smoker's volunteers. - Highlights: • The (palladium(II)-orthohydroxyacetophenone azine) complex doped in sol–gel was prepared. • It was used for the assessment of of α-amylase enzyme activity. • By maltose resulting from the reaction of α-amylase enzyme with starch. • A novel, simple, sensitive and precise spectrofluorometric method was developed.

  19. Synthesis, spectroscopic characterization of palladium(II)-orthohydroxyacetophenone azine nano-optical sensor doped in sol–gel matrix and its use as probe for assessment of α-amylase activity in human saliva

    International Nuclear Information System (INIS)

    El-Sayed, B.A.; Abo-Aly, M.M.; Attia, M.S.; Gamal, S.

    2016-01-01

    PdAPA (palladium(II)-orthohydroxyacetophenone azine) complex doped in sol–gel matrix is synthesized. It is characterized using UV-visible, infrared spectra and TEM image. A novel, simple, sensitive spectrofluorometric method was developed for measuring the activity of the α-amylase enzyme in human saliva for smokers and non-smokers with age range (17–64 years) based on the quenching of the luminescence intensity at 450 nm of the new synthesized complex characterized by various concentrations of the maltose released from the hydrolysis of starch by α-amylase enzyme and was successfully used as nano-optical sensor. The calibration plot was achieved over the concentration range 4.7×10 −6 –9.3×10 −10 mol L −1 maltose with a correlation coefficient of 0.996 and a detection minimum limit value of 7.55×10 −10 mol L −1 . The method was satisfactorily used for the assessment of the α-amylase activity in a number of human saliva samples for various smokers and non-smoker's volunteers. - Highlights: • The (palladium(II)-orthohydroxyacetophenone azine) complex doped in sol–gel was prepared. • It was used for the assessment of of α-amylase enzyme activity. • By maltose resulting from the reaction of α-amylase enzyme with starch. • A novel, simple, sensitive and precise spectrofluorometric method was developed.

  20. Thoria sol-gel processes

    International Nuclear Information System (INIS)

    Matthews, R.B.

    1978-10-01

    Alternate fuel fabrication techniques are being developed at WNRE as part of the thorium fuel cycle program. The sol-gel techniques are attractive and this report assembles and summarizes information relating to thoria sol-gel fuels. Some background information on the behaviour and advantages of sol-gel fuel forms is presented, followed by a review of relevant colloid chemistry and an explanation of the fundamental steps of sol-gel processes. Finally, several variants to the basic process are reviewed and evaluated. (author)

  1. Gel polymer electrolytes for batteries

    Science.gov (United States)

    Balsara, Nitash Pervez; Eitouni, Hany Basam; Gur, Ilan; Singh, Mohit; Hudson, William

    2014-11-18

    Nanostructured gel polymer electrolytes that have both high ionic conductivity and high mechanical strength are disclosed. The electrolytes have at least two domains--one domain contains an ionically-conductive gel polymer and the other domain contains a rigid polymer that provides structure for the electrolyte. The domains are formed by block copolymers. The first block provides a polymer matrix that may or may not be conductive on by itself, but that can soak up a liquid electrolyte, thereby making a gel. An exemplary nanostructured gel polymer electrolyte has an ionic conductivity of at least 1.times.10.sup.-4 S cm.sup.-1 at 25.degree. C.

  2. Solution-mediated growth of NBA-ZSM-5 crystals retarded by gel entrapment

    Science.gov (United States)

    Aguilar-Mamani, Wilson; Akhtar, Farid; Hedlund, Jonas; Mouzon, Johanne

    2018-04-01

    The synthesis of flat tablet-shaped ZSM-5 crystals from a gel using metakaolin as aluminosilicate source and n-butyl amine as structure directing agent was investigated. The evolution inside the solid phase was characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetry and mass spectrometry. A kinetic study indicated that the nucleation of the majority crystals occurred concurrently with the formation of the gel upon heating the starting liquid suspension. Microstructural evidences undeniably showed that the gel precipitated on ZSM-5 crystals and mineral impurities originating from kaolin. As a result, crystal growth was retarded by gel entrapment, as indicated by the configuration and morphology of the embedded crystals. The results presented herein are harmonized with a solution-mediated nucleation and growth mechanism. Our observations differ from the autocatalytic model that suggests that the nuclei rest inside the gel until released when the gel is consumed. Our results show instead that it is crystals that formed in an early stage before entrapment inside the gel that rest inside the gel until exposed at the gel surface. These results illustrate the limitation of the classical method used in the field to determine nucleation profiles when the crystals become trapped inside the gel.

  3. Organo-gel de heptano: diagrama de fases e aplicações sintéticas

    Directory of Open Access Journals (Sweden)

    Queiroz Neide

    1999-01-01

    Full Text Available The phase diagram formation of microemulsion-based gels composed of an anionic surfactant aerosol-OT sodium bis (2-ethylhexyl-sulphosuccinate, water, gelatin and an organic solvent is presented for heptane. The stability of this organo- gel, when an enzyme is immobilized is discussed in terms of its reutilization in various esters synthesis.

  4. THERMALLY STABLE NANOCRYSTALLINE TIO2 PHOTOCATALYSTS SYNTHESIZED VIA SOL-GEL METHODS MODIFIED WITH IONIC LIQUID AND SURFACTANT MOLECULES

    Science.gov (United States)

    Recently, sol-gel methods employing ionic liquids (ILs) have shown significant implications for the synthesis of well-defined nanostructured inorganic materials. Herein, we synthesized nanocrystalline TiO2 particles via an alkoxide sol-gel method employing a water-immi...

  5. Synthesis by Sol-gel and characterization of catalysts Ag/Al{sub 2}O{sub 3}-CeO{sub 2}; Sintesis por Sol-gel y caracterizacion de catalizadores Ag/Al{sub 2}O{sub 3}-CeO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zayas, M.L.; Perez H, R. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Rubio, E. [BUAP, Centro de Vinculacion, 72000 Puebla (Mexico); Velasco, A. [BUAP, Facultad de Quimica, 72000 Puebla (Mexico)

    2004-07-01

    Aluminia, cerium and mixed oxides Al{sub 2}O{sub 3}-CeO{sub 2} with different relationship Al/Ce (0.75, 0.50 and 0.25) were prepared by sol-gel and used as support for the Ag. The samples were characterized by XRD, DRIFT, TPR and adsorption of N{sub 2} to temperature of liquid nitrogen. The surface area BET showed that the materials that contain aluminia present near values among them. XRD allowed to identify to the cerianite in the oxides that whose support contains cerium and to the {alpha}-aluminia. A mixture of phases was observed in the aluminia. Vibration bands attributed to the bond Al-O and Ce-O were observed by DRIFT in the catalytic materials. TPR showed differences in the reducibility of the Ag precursor in the indicative catalysts of a different interaction with the support. (Author)

  6. Studies on inorganic polyphosphate metabolism in Mycobacterium phlei. Pt. 1. The incorporation of 32P into various phosphorus fractions of M. phlei grown on normal and modified Loewenstein media

    International Nuclear Information System (INIS)

    Szymona, O.

    1974-01-01

    Mycobacterium phlei was grown on various media with radioactive orthophosphate added. At timed intervals the bacteria were fractionated and in particular fractions both total and 32 P was determined. The content of acid-insoluble polyphosphate was measured enzymatically by the use of specific glucokinase. The organism grown on normal Loewenstein medium proved to accumulate high amounts of polyphosphate which was formed in more than 50% at the expense of organic egg yolk phosphorus. In contrast, the nuclei acid phosphorus was derived to a greater extent from labeled orthophosphate. Concentration of polyphosphate was lower in the presence of either purified phosvitin or lecithin substituted for egg yolk, although lecithin ensured good growth of the bacteria. (author)

  7. Studies on inorganic polyphosphate metabolism in Mycobacterium phlei. I. The incorporation of /sup 32/P into various phosphorus fractions of M. phlei grown on normal and modified Loewenstein media

    Energy Technology Data Exchange (ETDEWEB)

    Szymona, O [Akademia Medyczna, Lublin (Poland)

    1974-01-01

    Mycobacterium phlei was grown on various media with radioactive orthophosphate added. At timed intervals the bacteria were fractionated and in particular fractions both total and /sup 32/P was determined. The content of acid-insoluble polyphosphate was measured enzymatically by the use of specific glucokinase. The organism grown on normal Loewenstein medium proved to accumulate high amounts of polyphosphate which was formed in more than 50% at the expense of organic egg yolk phosphorus. In contrast, the nuclei acid phosphorus was derived to a greater extent from labeled orthophosphate. Concentration of polyphosphate was lower in the presence of either purified phosvitin or lecithin substituted for egg yolk, although lecithin ensured good growth of the bacteria.

  8. Effects of phosphorus on polyphosphate accumulation by Cunninghamella elegans Efeitos do fósforo sobre a acumulação de polifosfato em Cunninghamella elegans

    Directory of Open Access Journals (Sweden)

    Marcos Antonio Barbosa de Lima

    2003-12-01

    Full Text Available The content of inorganic polyphosphate and the polymeric degree of these compounds were evaluated during the growth of Cunninghamella elegans in medium containing varying orthophosphate (Pi concentrations. For this purpose, a combination of chemical methods for polyphosphate extraction and ultrastructural cytochemistry were used. The orthophosphate and glucose consumption was also determined during the fungal cultivation. At Pi concentrations of 0.5, 2.5 and 0.0 g/L, the maximum amounts of biomass were 3.18, 3.29 and 0.24 g/L, respectively. During growth the cells accumulated Pi from the medium. At three days of growth the biomass consumed up to 100 and 95% of Pi from the media at initial concentrations of 0.5 and 2.5 g/L, respectively. Polyphosphate was observed at different Pi concentrations in medium and at different stages of growth. Polyphosphate was assayed by the content of labile phosphorus in water, acid-insoluble and alkali-soluble fractions. The content of fractions changed according to phosphorus concentration in the media and growth phase. During growth on all three media used, the cytochecmical behavior of polyphosphate changed considerably. The results obtained in this study reveal a potential of Cunninghamella elegans in the polyphosphate accumulation, and suggest a future application in the biotechnological processes.O crescimento, consumo de fosfato e glicose, bem como o conteúdo de fósforo, a distribuição, estrutura e localização de polifosfato foram avaliados no micélio de Cunninghamella elegans cultivado em meios contendo diferentes concentrações de fosfato. Os resultados permitiram verificar a influência dessas concentrações de fosfato sobre o crescimento do fungo estudado. A maior concentração de fosfato proporcionou maior rendimento da biomassa ao longo do crescimento. Uma relação entre consumo de fosfato e glicose do meio foi observada em relação ao crescimento e a quantidade de polifosfato total nos

  9. Soft chemistry routes to transparent metal oxide thin films. The case of sol–gel synthesis and structural characterization of Ta{sub 2}O{sub 5} thin films from tantalum chloromethoxide

    Energy Technology Data Exchange (ETDEWEB)

    Epifani, Mauro, E-mail: mauro.epifani@le.imm.cnr.it [Istituto per la Microelettronica e i Microsistemi, IMM-CNR, Via Monteroni, 73100 Lecce (Italy); Zamani, Reza [Catalonia Institute for Energy Research, IREC c/Jardins de les Dones de Negre, 1, 08930-Sant Adria del Besos, Barcelona (Spain); Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, 08193 Bellaterra, CAT (Spain); Arbiol, Jordi [Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, 08193 Bellaterra, CAT (Spain); Institucio Catalana de Recerca i Estudis Avançats, ICREA, 08010, Barcelona (Spain); Fabrega, Cristian; Andreu, Teresa [Catalonia Institute for Energy Research, IREC c/Jardins de les Dones de Negre, 1, 08930-Sant Adria del Besos, Barcelona (Spain); Pace, Giovanni Battista; Siciliano, Pietro [Istituto per la Microelettronica e i Microsistemi, IMM-CNR, Via Monteroni, 73100 Lecce (Italy); Morante, Joan R. [Catalonia Institute for Energy Research, IREC c/Jardins de les Dones de Negre, 1, 08930-Sant Adria del Besos, Barcelona (Spain); M2E-IN2UB-XaRMAE, Departament d’Electrònica, Universitat de Barcelona, C. Martí i Franquès 1, 08028 Barcelona, CAT (Spain)

    2014-03-31

    Ta{sub 2}O{sub 5} thin films were prepared by spin-coating methanol solutions of Ta chloromethoxide. It was prepared by reacting TaCl{sub 5} with methanol, followed by water addition (H{sub 2}O: Ta molar ratio was 16). Thin films were deposited by spin-coating onto SiO{sub 2}/Si substrates, followed by drying at 90 °C and heat-treatment up to 700 °C. The films were characterized by X-ray diffraction, transmission electron microscopy and field emission scanning electron microscopy. Crystallization was obtained only after heating at 700 °C, in the Ta{sub 2}O{sub 5} orthorhombic phase. The resulting films had a thickness of 100 nm. Their structure was constituted by porous crystals with size up to 50 nm, while the pores had a size of about 10 nm. The results demonstrated that TaCl{sub 5} is very convenient precursor for the wet chemical synthesis of Ta{sub 2}O{sub 5} thin films. - Highlights: • Development of convenient solution synthesis of Ta{sub 2}O{sub 5} thin films; • The precursor chemistry was established and related to the synthesis process; • Uniform films crystallized in the most stable orthorombic Ta{sub 2}O{sub 5} phase;.

  10. Soft chemistry routes to transparent metal oxide thin films. The case of sol–gel synthesis and structural characterization of Ta2O5 thin films from tantalum chloromethoxide

    International Nuclear Information System (INIS)

    Epifani, Mauro; Zamani, Reza; Arbiol, Jordi; Fabrega, Cristian; Andreu, Teresa; Pace, Giovanni Battista; Siciliano, Pietro; Morante, Joan R.

    2014-01-01

    Ta 2 O 5 thin films were prepared by spin-coating methanol solutions of Ta chloromethoxide. It was prepared by reacting TaCl 5 with methanol, followed by water addition (H 2 O: Ta molar ratio was 16). Thin films were deposited by spin-coating onto SiO 2 /Si substrates, followed by drying at 90 °C and heat-treatment up to 700 °C. The films were characterized by X-ray diffraction, transmission electron microscopy and field emission scanning electron microscopy. Crystallization was obtained only after heating at 700 °C, in the Ta 2 O 5 orthorhombic phase. The resulting films had a thickness of 100 nm. Their structure was constituted by porous crystals with size up to 50 nm, while the pores had a size of about 10 nm. The results demonstrated that TaCl 5 is very convenient precursor for the wet chemical synthesis of Ta 2 O 5 thin films. - Highlights: • Development of convenient solution synthesis of Ta 2 O 5 thin films; • The precursor chemistry was established and related to the synthesis process; • Uniform films crystallized in the most stable orthorombic Ta 2 O 5 phase;

  11. Synthesis of Pure Hydroxyapatite (Ca10 (PO46 (OH2 by the Sol –Gel Method and the Doxycycline Loaded in Presence of Gelatin for the Application of Drug Delivery DOI 10.2412/mmse.89.93.112

    Directory of Open Access Journals (Sweden)

    B. Shalini

    2017-06-01

    Full Text Available Hydroxyapatite (HAp is the most widely accepted biomaterial for the repair and reconstruction of bone tissue defects. The current study is based on HAp was synthesized using sol – gel method. The drug was loaded in presence of gelatin with pure HAp. Precursors like calcium nitrate tetrahydrate and diammonium hydrogen orthophosphate were used and ammonia solution was added to maintain the pH value at 10.5 throughout the reaction. The synthesized HAp and drug loaded HAp with gelatin were characterized using PXRD, FTIR, SEM, Drug loading, drug release studies. Results show that the average crystallite size for prepared HAp and drug loaded HAp with polymer are ~ 30 to 300 nm respectively was calculated using PXRD and morphology of pure HAp and drug loaded HAp with polymer was found using SEM. Drug loading and release percentage was calculated. Keeping the above points in the present study was aimed to produce the biocompatibility and bioactivity of HAp.

  12. Sol–gel synthesis and photoluminescence studies on colour tuneable Dy3+/Tm3+ co-doped NaGd(WO4)2 phosphor for white light emission

    International Nuclear Information System (INIS)

    Durairajan, A.; Balaji, D.; Rasu, K. Kavi; Moorthy Babu, S.; Hayakawa, Y.; Valente, M.A.

    2015-01-01

    A series of Dy 3+ /Tm 3+ ion co-doped NaGd(WO 4 ) 2 (NGW) phosphors were synthesised by a sol–gel method at low temperature for white light emission. The structural and luminescence properties of the synthesised phosphors were studied by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman and photoluminescence techniques. In Dy 3+ /Tm 3+ :NGW phosphors, the dopant ions substituted Gd 3+ ions that are located in S 4 sites of NGW host lattice. In NGW host, under UV excitation the Dy 3+ ions have shown strong yellow ( 4 F 9/2 → 6 H 13/2 ) and comparatively weak blue ( 4 F 9/2 → 6 H 15/2 ) emission transitions at 575 and 488 nm, respectively. Due to deficient blue colour the overall emission falls in yellow region. Hence, Tm 3+ ions having strong blue emission at 455 nm corresponding to the transition 1 D 2 → 3 F 4 were co-activated along with Dy 3+ ions in NGW matrix. By changing the doping concentrations of Tm 3+ and Dy 3+ ions in NGW, white light emission was tuned by 353 nm excitation wavelength. Their corresponding colour co-ordinates were calculated and found to be very close to the white colour chromaticity co-ordinates (0.333, 0.333). - Highlights: • Dy 3+ and Dy 3+ /Tm 3+ :NGW phosphors were synthesised by sol–gel methods. • The excitation spectrum confirmed the strong absorption in near-UV region. • The emission spectrum shows the yellow and white emission to doped and co-doped phosphors respectively. • The CIE co-ordinate conforms close to daylight emission

  13. Rheology and structure of milk protein gels

    NARCIS (Netherlands)

    Vliet, van T.; Lakemond, C.M.M.; Visschers, R.W.

    2004-01-01

    Recent studies on gel formation and rheology of milk gels are reviewed. A distinction is made between gels formed by aggregated casein, gels of `pure` whey proteins and gels in which both casein and whey proteins contribute to their properties. For casein' whey protein mixtures, it has been shown

  14. Sol-Gel Thin Films for Plasmonic Gas Sensors

    Science.gov (United States)

    Della Gaspera, Enrico; Martucci, Alessandro

    2015-01-01

    Plasmonic gas sensors are optical sensors that use localized surface plasmons or extended surface plasmons as transducing platform. Surface plasmons are very sensitive to dielectric variations of the environment or to electron exchange, and these effects have been exploited for the realization of sensitive gas sensors. In this paper, we review our research work of the last few years on the synthesis and the gas sensing properties of sol-gel based nanomaterials for plasmonic sensors. PMID:26184216

  15. Porous calcium polyphosphate bone substitutes: additive manufacturing versus conventional gravity sinter processing-effect on structure and mechanical properties.

    Science.gov (United States)

    Hu, Youxin; Shanjani, Yaser; Toyserkani, Ehsan; Grynpas, Marc; Wang, Rizhi; Pilliar, Robert

    2014-02-01

    Porous calcium polyphosphate (CPP) structures proposed as bone-substitute implants and made by sintering CPP powders to form bending test samples o