Sample records for zinc borate glasses

  1. Thermoluminescence response of rare earth activated zinc lithium borate glass

    NASA Astrophysics Data System (ADS)

    Saidu, A.; Wagiran, H.; Saeed, M. A.; Obayes, H. K.; Bala, A.; Usman, F.

    2018-03-01

    New glasses of zinc lithium borate doped with terbium oxide were synthesized by high temperature solid-state reaction. The amorphous nature of the glasses was confirmed using x-ray diffraction analysis (XRD). Thermoluminescence (TL) response of pure zinc lithium borate (ZLB) and zinc lithium borate doped with terbium (ZLB: Tb) exposed to gamma radiation was measured and compared. There is significant enhancement in the TL yields of ZLB: Tb compared to that of pure ZLB. Effect of varying concentration of dopant (Tb4O7) on the TL response of zinc lithium borate was investigated. 0.3 mol% concentration of Tb exhibited strongest TL intensity. Thermoluminescence curve of the phosphor consist of single isolated peak. The TL response of the new materials to the exposed radiation is linear within 0.5-100 Gy range of dose with sublinearity at the lower region of the curve. High sensitivity was exhibited by the new amorphous materials. Reproducibility, thermal fading and energy response of the proposed TLD were investigated and shows remarkable result that made the phosphor suitable for radiation dosimetry.

  2. Photon Interaction Parameters for Some Borate Glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mann, Nisha; Kaur, Updesh; Singh, Tejbir

    2010-11-06

    Some photon interaction parameters of dosimetric interest such as mass attenuation coefficients, effective atomic number, electron density and KERMA relative to air have been computed in the wide energy range from 1 keV to 100 GeV for some borate glasses viz. barium-lead borate, bismuth-borate, calcium-strontium borate, lead borate and zinc-borate glass. It has been observed that lead borate glass and barium-lead borate glass have maximum values of mass attenuation coefficient, effective atomic number and KERMA relative to air. Hence, these borate glasses are suitable as gamma ray shielding material, packing of radioactive sources etc.

  3. Red light emission from europium doped zinc sodium bismuth borate glasses

    NASA Astrophysics Data System (ADS)

    Hegde, Vinod; Viswanath, C. S. Dwaraka; Upadhyaya, Vyasa; Mahato, K. K.; Kamath, Sudha D.

    2017-12-01

    Zinc sodium bismuth borate (ZNBB) glasses doped with different concentrations of europium were prepared by conventional melt quenching method and characterized through the measurements of density, refractive index, X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectra, optical absorption, luminescence and radiative lifetimes. FTIR spectra showed seven characteristic peaks of bismuth and borate functional groups in the range of 400-1600 cm-1. The optical band gap and bonding parameters have been calculated from absorption spectra. Photoluminescence spectra recorded in the visible region with 394 nm excitation are used to calculate the Judd-Ofelt (JO) intensity parameters (Ω2 and Ω4). The JO intensity parameters have been used to calculate the radiative parameters such as branching ratio (β), stimulated emission cross-section (σse), transition probability (A) for the fluorescent level of 5D0→7F2. Decay rates through single exponential are used to calculate the lifetime (τm) of the meta-stable state 5D0 of (Eu3+ ion) these glasses. The radiative parameters measured for all these glasses show 0.7 mol% europium doped zinc sodium bismuth borate glass 5D0→7F2 transition has the potential for red laser applications. The quality of the colour emitted by the present glasses are estimated quantitatively by CIE chromaticity coordinates, which confirms the suitability of these glasses as a red emitting material for field emission technologies and LEDs.

  4. Third order nonlinear optical properties of bismuth zinc borate glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shanmugavelu, B.; Ravi Kanth Kumar, V. V., E-mail: ravi.phy@pondiuni.edu.in; Kuladeep, R.

    2013-12-28

    Third order nonlinear optical characterization of bismuth zinc borate glasses are reported here using different laser pulse durations. Bismuth zinc borate glasses with compositions xBi{sub 2}O{sub 3}-30ZnO-(70-x) B{sub 2}O{sub 3} (where x = 30, 35, 40, and 45 mol. %) have been prepared by melt quenching method. These glasses were characterized by Raman, UV-Vis absorption, and Z scan measurements. Raman and UV-Vis spectroscopic results indicate that non-bridging oxygens increase with increase of bismuth content in the glass. Nonlinear absorption and refraction behavior in the nanosecond (ns), picosecond (ps), and femtosecond (fs) time domains were studied in detail. Strong reverse saturable absorption due tomore » dominant two-photon absorption (TPA) was observed with both ps and fs excitations. In the case of ns pulse excitations, TPA and free-carrier absorption processes contribute for the nonlinear absorption. Two-photon absorption coefficient (β) and the absorption cross section due to free carriers (σ{sub e}) are estimated by theoretical fit of the open aperture Z-scan measurements and found to be dependent on the amount of bismuth oxide in the glass composition. In both ns and fs regimes the sign and magnitude of the third order nonlinearity are evaluated, and the optical limiting characteristics are also reported.« less

  5. Synthesis and studies on microhardness of alkali zinc borate glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Subhashini,, E-mail: subhashini.p.p@gmail.com; Bhattacharya, Soumalya, E-mail: subhashini.p.p@gmail.com; Shashikala, H. D., E-mail: subhashini.p.p@gmail.com

    2014-04-24

    The mixed alkali effect on zinc borate glasses have been reported. The glass systems of nominal composition 10Zn+xLi{sub 2}O+yNa{sub 2}O+80B{sub 2}O{sub 3} (x = y = 0, 5, 10, 15 mol%) were prepared using standard melt quenching method. The structural, physical and mechanical properties of the samples have been studied using X-ray diffraction(XRD), density measurement and Vickers hardness measurement, respectively. A consistent increase in the density was observed, which explains the role of the modifiers (Li{sub 2}O and Na{sub 2}O) in the network modification of borate structure. The molar volume is decreasing linearly with the alkali concentration, which is attributedmore » to the conversion of tetrahedral boron (BO{sub 4/2}){sup −} into (BO{sub 3/2}){sup −}. The microhardness studies reveals the anisotropy nature of the material. It further confirms that the samples belong to hard glass category.« less

  6. VO2+ ions in zinc lead borate glasses studied by EPR and optical absorption techniques.

    PubMed

    Prakash, P Giri; Rao, J Lakshmana

    2005-09-01

    Electron paramagnetic resonance (EPR) and optical absorption spectra of vanadyl ions in zinc lead borate (ZnO-PbO-B2O3) glass system have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of VO2+ ions. The values of spin-Hamiltonian parameters indicate that the VO2+ ions in zinc lead borate glasses were present in octahedral sites with tetragonal compression and belong to C4V symmetry. The spin-Hamiltonian parameters g and A are found to be independent of V2O5 content and temperature but changing with ZnO content. The decrease in Deltag( parallel)/Deltag( perpendicular) value with increase in ZnO content indicates that the symmetry around VO2+ ions is more octahedral. The decrease in intensity of EPR signal above 10 mol% of V2O5 is attributed to a fall in the ratio of the number of V4+ ions (N4) to the number of V5+ ions (N5). The number of spins (N) participating in resonance was calculated as a function of temperature for VO2+ doped zinc lead borate glass sample and the activation energy was calculated. From the EPR data, the paramagnetic susceptibility was calculated at various temperatures and the Curie constant was evaluated from the 1/chi-T graph. The optical absorption spectra show single absorption band due to VO2+ ions in tetragonally distorted octahedral sites.

  7. Effect of zinc-borate glass addition on the thermal properties of the cordierite/Al2O3 composites containing nano-sized spinel crystal.

    PubMed

    Jo, Sinae; Kang, Seunggu

    2013-11-01

    Low-melting zinc-borate glass was added to the cordierite/Al2O3 composite in order to improve the sintering facility of Al2O3 and formation of nano-sized spinel crystal of high thermal conductivity. Increasing the ZnO/B2O3 ratio in the zinc-borate glass increased the ZnAl2O4 spinel and decreased the Al4B2O9 crystal peak intensities in X-ray diffraction pattern. The XRD peak intensities of the ZnAl2O4 spinel and Al4B2O9 crystals in the specimen containing 10 wt% zinc-borate glass (10G series) are higher than that of the specimen containing 5 wt% zinc-borate glass (5G series). The microstructures of most 10G series specimens had the flower-shaped crystal which was composed of 50 nm wide and 250 nm long needle-like crystals and identified as ZnAl2O4 spinel phase. The thermal conductivity of the 10G series specimen was higher than that of the 5G series in any ZnO/B2O3 ratio due to the formation of plenty of nano-sized ZnAl2O4 spinel of high thermal conductivity. Particularly, the thermal conductivity of the cordierite/Al2O3 composite containing 10 wt% zinc-borate glass of ZnO/B2O3 weight ratio = 1.5 was 3.8 W/Km which is much higher than that of the published value (3.0 W/Km).

  8. Optical characterization of Eu3+ and Tb3+ ions doped zinc lead borate glasses.

    PubMed

    Thulasiramudu, A; Buddhudu, S

    2007-02-01

    This paper reports on the spectral analysis of Eu3+ or Tb3+ ions (0.5 mol%) doped heavy metal oxide (HMO) based zinc lead borate glasses from the measurement of their absorption, emission spectra and also different physical properties. From the XRD, DSC profiles, the glass nature and glass thermal properties have been studied. The measured emission spectrum of Eu3+ glass has revealed five transitions (5D0-->7F0, 7F1, 7F2, 7F3 and 7F4) at 578, 591, 613, 654 and 702 nm, respectively, with lambdaexci=392 nm (7F0-->5L6). In the case of Tb3+:ZLB glass, four emission transitions such as (5D4-->7F6, 7F5, 7F4 and 7F3) that are located at 489, 542, 585 and 622 nm, respectively, have been measured with lambdaexci=374 nm. For all these emission bands decay curves have been plotted to evaluate their lifetimes and the emission processes that arise in the glasses have been explained in terms of energy level schemes.

  9. The impact of gallium content on degradation, bioactivity, and antibacterial potency of zinc borate bioactive glass.

    PubMed

    Rahimnejad Yazdi, Alireza; Torkan, Lawrence; Stone, Wendy; Towler, Mark R

    2018-01-01

    Zinc borate glasses with increasing gallium content (0, 2.5, 5, 10, and 15 Wt % Ga) were synthesized and their degradation, bioactivity in simulated body fluid (SBF), and antibacterial properties were investigated. ICP measurements showed that increased gallium content in the glass resulted in increased gallium ion release and decreased release of other ions. Degradability declined with the addition of gallium, indicating the formation of more symmetric BO 3 units with three bridging oxygens and asymmetric BO 3 units with two bridging oxygens in the glass network as the gallium content in the series increased. The formation of amorphous CaP on the glass surface after 24 h of incubation in SBF was confirmed by SEM, XRD, and FTIR analyses. Finally, antibacterial evaluation of the glasses using the agar disc-diffusion method demonstrated that the addition of gallium increased the antibacterial potency of the glasses against P. aeruginosa (Gram-negative) while decreasing it against S. epidermidis (Gram-positive); considering the ion release trends, this indicates that the gallium ion is responsible for the glasses' antibacterial behavior against P. aeruginosa while the zinc ion controls the antibacterial activity against S. epidermidis. The statistical significance of the observed trends in the measurements were confirmed by applying the Kruskal-Wallis H Test. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 367-376, 2018. © 2017 Wiley Periodicals, Inc.

  10. Optical studies of Sm³⁺ ions doped zinc alumino bismuth borate glasses.

    PubMed

    Swapna, K; Mahamuda, Sk; Srinivasa Rao, A; Shakya, S; Sasikala, T; Haranath, D; Vijaya Prakash, G

    2014-05-05

    Zinc Alumino Bismuth Borate (ZnAlBiB) glasses doped with different concentrations of samarium (Sm(3+)) ions were prepared by using melt quenching technique and characterized for their lasing potentialities in visible region by using the techniques such as optical absorption, emission and emission decay measurements. Radiative properties for various fluorescent levels of Sm(3+) ions were estimated from absorption spectral information using Judd-Ofelt (JO) analysis. The emission spectra and con-focal photoluminescence images obtained by 410 nm laser excitation demonstrates very distinct and intense orange-red emission for all the doped glasses. The suitable concentration of Sm(3+) ions in these glasses to act as an efficient lasing material has been discussed by measuring the emission cross-section and branching ratios for the emission transitions. The quantum efficiencies were also been estimated from emission decay measurements recorded for the (4)G5/2 level of Sm(3+) ions. From the measured emission cross-sections, branching ratios, strong photoluminescence features and CIE chromaticity coordinates, it was found that 1 mol% of Sm(3+) ions doped ZnAlBiB glasses are most suitable for the development of visible orange-red lasers. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Improved synthesis of fine zinc borate particles using seed crystals

    NASA Astrophysics Data System (ADS)

    Gürhan, Deniz; Çakal, Gaye Ö.; Eroğlu, İnci; Özkar, Saim

    2009-03-01

    Zinc borate is a flame retardant additive used in polymers, wood applications and textile products. There are different types of zinc borate having different chemical compositions and structures. In this study, the production of zinc borate having the molecular formula of 2ZnO·3B 2O 3·3.5H 2O was reexamined by studying the effects of reaction parameters on the properties of product as well as the reaction kinetics. Production of zinc borate from the reaction of boric acid and zinc oxide in the presence of seed crystals was performed in a continuously stirred, temperature-controlled batch reactor having a volume of 1.5 L. Samples taken in regular time intervals during the experiments were analyzed for the concentration of zinc oxide and boron oxide in the solid as well as for the conversion of zinc oxide to zinc borate versus time. The zinc borate production reaction was fit to the logistic model. The reaction rate, reaction completion time, composition and particle size distribution of zinc borate product were determined by varying the following parameters: the boric acid to zinc oxide ratio (H 3BO 3:ZnO=3:1, 3.5:1, 5:1 and 7:1), the particle size of zinc oxide (10 and 25 μm), stirring rate (275, 400, 800 and 1600 rpm), temperature (75, 85 and 95 °C) and the size of seed crystals (10 and 2 μm). The products were also analyzed for particle size distribution. The experimental results showed that the reaction rate increases with the increase in H 3BO 3:ZnO ratio, particle size of zinc oxide, stirring rate and temperature. Concomitantly, the reaction completion time is decreased by increasing the H 3BO 3:ZnO ratio, stirring rate and temperature. The average particle sizes of the zinc borate products are in the range 4.3-16.6 μm (wet dispersion analysis).

  12. Degradable borate glass polyalkenoate cements.

    PubMed

    Shen, L; Coughlan, A; Towler, M; Hall, M

    2014-04-01

    Glass polyalkenoate cements (GPCs) containing aluminum-free borate glasses having the general composition Ag2O-Na2O-CaO-SrO-ZnO-TiO2-B2O3 were evaluated in this work. An initial screening study of sixteen compositions was used to identify regions of glass formation and cement compositions with promising rheological properties. The results of the screening study were used to develop four model borate glass compositions for further study. A second round of rheological experiments was used to identify a preferred GPC formulation for each model glass composition. The model borate glasses containing higher levels of TiO2 (7.5 mol %) tended to have longer working times and shorter setting times. Dissolution behavior of the four model GPC formulations was evaluated by measuring ion release profiles as a function of time. All four GPC formulations showed evidence of incongruent dissolution behavior when considering the relative release profiles of sodium and boron, although the exact dissolution profile of the glass was presumably obscured by the polymeric cement matrix. Compression testing was undertaken to evaluate cement strength over time during immersion in water. The cements containing the borate glass with 7.5 mol % TiO2 had the highest initial compressive strength, ranging between 20 and 30 MPa. No beneficial aging effect was observed-instead, the strength of all four model GPC formulations was found to degrade with time.

  13. Bioactive borate glass coatings for titanium alloys.

    PubMed

    Peddi, Laxmikanth; Brow, Richard K; Brown, Roger F

    2008-09-01

    Bioactive borate glass coatings have been developed for titanium and titanium alloys. Glasses from the Na(2)O-CaO-B(2)O(3) system, modified by additions of SiO(2), Al(2)O(3), and P(2)O(5), were characterized and compositions with thermal expansion matches to titanium were identified. Infrared and X-ray diffraction analyses indicate that a hydroxyapatite surface layer forms on the borate glasses after exposure to a simulated body fluid for 2 weeks at 37 degrees C; similar layers form on 45S5 Bioglass((R)) exposed to the same conditions. Assays with MC3T3-E1 pre-osteoblastic cells show the borate glasses exhibit in vitro biocompatibility similar to that of the 45S5 Bioglass((R)). An enameling technique was developed to form adherent borate glass coatings on Ti6Al4V alloy, with adhesive strengths of 36 +/- 2 MPa on polished substrates. The results show these new borate glasses to be promising candidates for forming bioactive coatings on titanium substrates.

  14. In vitro stimulation of vascular endothelial growth factor by borate-based glass fibers under dynamic flow conditions.

    PubMed

    Chen, Sisi; Yang, Qingbo; Brow, Richard K; Liu, Kun; Brow, Katherine A; Ma, Yinfa; Shi, Honglan

    2017-04-01

    Bioactive borate glass has been recognized to have both hard and soft tissue repair and regeneration capabilities through stimulating both osteogenesis and angiogenesis. However, the underlying biochemical and cellular mechanisms remain unclear. In this study, dynamic flow culturing modules were designed to simulate the micro-environment near the vascular depletion and hyperplasia area in wound-healing regions, thus to better investigate the mechanisms underlying the biocompatibility and functionality of borate-based glass materials. Glass fibers were dosed either upstream or in contact with the pre-seeded cells in the dynamic flow module. Two types of borate glasses, doped with (1605) or without (13-93B3) CuO and ZnO, were studied along with the silicate-based glass, 45S5. Substantial fiber dissolution in cell culture medium was observed, leading to the release of ions (boron, sodium and potassium) and the deposition of a calcium phosphate phase. Different levels of vascular endothelial growth factor secretion were observed from cells exposed to these three glass fibers, and the copper/zinc containing borate 1605 fibers exhibited the most positive influence. These results indicate that dynamic studies of in vitro bioactivity provide useful information to understand the in vivo response to bioactive borate glasses. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Fluorescence properties of Eu3+ ions doped borate and fluoroborate glasses containing lithium, zinc and lead.

    PubMed

    Venkatramu, V; Babu, P; Jayasankar, C K

    2006-02-01

    The influence of glass composition on the fluorescence properties of Eu3+ ions doped borate and fluoroborate glasses modified with Li+, Zn2+ and Pb2+ cations have been investigated. The magnitude of splittings of 7F1 levels are analyzed using crystal-field (CF) analysis. The relative intensities of 5D0 --> 7F2 to 5D0 --> 7F1 transitions, crystal-field strength parameters and decay times of the 5D0 level have been determined and are found to be lower for Pb based glasses than those of Zn/Li based glasses. The lifetimes of 5D0 level are found to increase when borate glasses are modified with pure fluorides than with oxides and oxyfluorides. The fluorescence decay of 5D0 level fits perfect single exponential in the Eu3+:glass systems studied which indicates the absence of energy transfer between Eu3+ ions in these glasses.

  16. Effect of modifying agents on the hydrophobicity and yield of zinc borate synthesized by zinc oxide

    NASA Astrophysics Data System (ADS)

    Acarali, Nil Baran; Bardakci, Melek; Tugrul, Nurcan; Derun, Emek Moroydor; Piskin, Sabriye

    2013-06-01

    The aim of this study was to synthesize zinc borate using zinc oxide, reference boric acid, and reference zinc borate (reference ZB) as the seed, and to investigate the effects of modifying agents and reaction parameters on the hydrophobicity and yield, respectively. The reaction parameters include reaction time (1-5 h), reactant ratio (H3BO3/ZnO by mass: 2-5), seed ratio (seed crystal/(H3BO3+ZnO) by mass: 0-2wt%), reaction temperature (50-120°C), cooling temperature (10-80°C), and stirring rate (400-700 r/min); the modifying agents involve propylene glycol (PG, 0-6wt%), kerosene (1wt%-6wt%), and oleic acid (OA, 1wt%-6wt%) with solvents (isopropyl alcohol (IPA), ethanol, and methanol). The results of reaction yield obtained from either magnetically or mechanically stirred systems were compared. Zinc borate produced was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and contact angle tests to identify the hydrophobicity. In conclusion, zinc borate is synthesized successfully under the optimized reaction conditions, and the different modifying agents with various solvents affect the hydrophobicity of zinc borate.

  17. Judd-Ofelt analysis and spectral properties of Dy3+ ions doped niobium containing tellurium calcium zinc borate glasses

    NASA Astrophysics Data System (ADS)

    Ravi, O.; Reddy, C. Madhukar; Reddy, B. Sudhakar; Deva Prasad Raju, B.

    2014-02-01

    Niobium containing tellurium calcium zinc borate (TCZNB) glasses doped with different concentrations of Dy3+ ions were prepared by the melt quenching method and their optical properties have been studied. The Judd-Ofelt (J-O) intensity parameters Ωt (t=2, 4 and 6) were calculated using the least square fit method. Based on the magnitude of Ω2 parameter the hypersensitivity of 6H15/2→6F11/2 has also been discussed. From the evaluated J-O intensity parameters as well as from the emission and lifetime measurements, radiative transition properties such as radiative transition probability rates and branching ratios were calculated for 4F9/2 excited level. It is found that for Dy3+ ion, the transition 4F9/2→6H13/2 shows highest emission cross-section at 1.0 mol% TCZNB glass matrix. From the visible luminescence spectra, yellow to blue (Y/B) intensity ratios and chromaticity color coordinates were also estimated. The TCZNB glasses exhibit good luminescence properties and are suitable for generation of white light.

  18. Transition and post-transition metal ions in borate glasses: Borate ligand speciation, cluster formation, and their effect on glass transition and mechanical properties.

    PubMed

    Möncke, D; Kamitsos, E I; Palles, D; Limbach, R; Winterstein-Beckmann, A; Honma, T; Yao, Z; Rouxel, T; Wondraczek, L

    2016-09-28

    A series of transition and post-transition metal ion (Mn, Cu, Zn, Pb, Bi) binary borate glasses was studied with special consideration of the cations impact on the borate structure, the cations cross-linking capacity, and more generally, structure-property correlations. Infrared (IR) and Raman spectroscopies were used for the structural characterization. These complementary techniques are sensitive to the short-range order as in the differentiation of tetrahedral and trigonal borate units or regarding the number of non-bridging oxygen ions per unit. Moreover, vibrational spectroscopy is also sensitive to the intermediate-range order and to the presence of superstructural units, such as rings and chains, or the combination of rings. In order to clarify band assignments for the various borate entities, examples are given from pure vitreous B 2 O 3 to meta-, pyro-, ortho-, and even overmodified borate glass compositions. For binary metaborate glasses, the impact of the modifier cation on the borate speciation is shown. High field strength cations such as Zn 2+ enhance the disproportionation of metaborate to polyborate and pyroborate units. Pb 2+ and Bi 3+ induce cluster formation, resulting in PbO n - and BiO n -pseudophases. Both lead and bismuth borate glasses show also a tendency to stabilize very large superstructural units in the form of diborate polyanions. Far-IR spectra reflect on the bonding states of modifier cations in glasses. The frequency of the measured cation-site vibration band was used to obtain the average force constant for the metal-oxygen bonding, F M-O . A linear correlation between glass transition temperature (T g ) and F M-O was shown for the metaborate glass series. The mechanical properties of the glasses also correlate with the force constant F M-O , though for cations of similar force constant the fraction of tetrahedral borate units (N 4 ) strongly affects the thermal and mechanical properties. For paramagnetic Cu- and Mn-borate glasses

  19. Angiogenic effects of borate glass microfibers in a rodent model.

    PubMed

    Lin, Yinan; Brown, Roger F; Jung, Steven B; Day, Delbert E

    2014-12-01

    The primary objective of this research was to evaluate the use of bioactive borate-based glass microfibers for angiogenesis in soft tissue repair applications. The effect of these fibers on growth of capillaries and small blood vessels was compared to that of 45S5 silica glass microfibers and sham implant controls. Compressed mats of three types of glass microfibers were implanted subcutaneously in rats and tissues surrounding the implant sites histologically evaluated 2-4 weeks post surgery. Bioactive borate glass 13-93B3 supplemented with 0.4 wt % copper promoted extensive angiogenesis as compared to silica glass microfibers and sham control tissues. The angiogenic responses suggest the copper-containing 13-93B3 microfibers may be effective for treating chronic soft tissue wounds. A second objective was to assess the possible systemic cytotoxicity of dissolved borate ions and other materials released from implanted borate glass microfibers. Cytotoxicity was assessed via histological evaluation of kidney tissue collected from animals 4 weeks after subcutaneously implanting high amounts of the borate glass microfibers. The evaluation of the kidney tissue from these animals showed no evidence of chronic histopathological changes in the kidney. The overall results indicate the borate glass microfibers are safe and effective for soft tissue applications. © 2014 Wiley Periodicals, Inc.

  20. Devitrification properties of lead borate glasses

    NASA Astrophysics Data System (ADS)

    Bajaj, Anu; Khanna, Atul; Krishnan, K.; Aggarwal, Suresh K.

    2013-06-01

    Lead borate glasses containing 30 to 60 mol% PbO were prepared by melt quenching technique and devitrified by long duration heat treament in the supercooled region. Glasses crystallized on heating above their glass transition temperature, and the crystalline phases produced on devitrification were characterized by XRD and DSC analyses. Glass with 30 mol% PbO slowly formed a solid solution of Pb6B10O21 and Pb5B8O17 crystalline phases, while glasses with 40 and 50 mol% PbO formed a mixture of Pb6B10O21, Pb5B8O17 and the remanent glassy phase. Glasses with higher PbO concentration of 56 to 60 mol% devitrified completely and produced only Pb5B8O17 crystalline phase. Lead borate glasses with PbO concentration of 40 to 50 mol% showed maximum thermal stability against devitrification, the ease of crystallization of glasses was correlated with the fraction of tetrahedral borons in them.

  1. Laboratory evaluation of borate/amine/zinc formulations for fungal decay protection

    Treesearch

    George C. Chen; Rebecca E. Ibach

    2010-01-01

    The goals of this study were to evaluate borate/amine/zinc formulations in wood for fungal decay protection as well as the permanence of zinc and boron in wood. Wood treated with each of four formulations of borate/amine/zinc prevented or decreased fungal degradation after a 12-week AWPA Standard soil-block test. For non-leached specimens, wood treated with borax/amine...

  2. Impact of vanadium ions in barium borate glass

    NASA Astrophysics Data System (ADS)

    Abdelghany, A. M.; Hammad, Ahmed H.

    2015-02-01

    Combined optical and infrared spectral measurements of prepared barium borate glasses containing different concentrations of V2O5 were carried out. Vanadium containing glasses exhibit extended UV-visible (UV/Vis.) bands when compared with base binary borate glass. UV/Vis. spectrum shows the presence of an unsymmetrical strong UV broad band centered at 214 nm attributed to the presence of unavoidable trace iron impurities within the raw materials used for the preparation of such glass. The calculated direct and indirect optical band gaps are found to decrease with increasing the vanadium content (2.9:137 for indirect and 3.99:2.01 for direct transition). This change was discussed in terms of structural changes in the glass network. Infrared absorption spectra of the glasses reveal the appearance of both triangular and tetrahedral borate units. Electron spin resonance analyses indicate the presence of unpaired species in sufficient quantity to be identified and to confirm the spectral data.

  3. Impact of vanadium ions in barium borate glass.

    PubMed

    Abdelghany, A M; Hammad, Ahmed H

    2015-02-25

    Combined optical and infrared spectral measurements of prepared barium borate glasses containing different concentrations of V2O5 were carried out. Vanadium containing glasses exhibit extended UV-visible (UV/Vis.) bands when compared with base binary borate glass. UV/Vis. spectrum shows the presence of an unsymmetrical strong UV broad band centered at 214 nm attributed to the presence of unavoidable trace iron impurities within the raw materials used for the preparation of such glass. The calculated direct and indirect optical band gaps are found to decrease with increasing the vanadium content (2.9:137 for indirect and 3.99:2.01 for direct transition). This change was discussed in terms of structural changes in the glass network. Infrared absorption spectra of the glasses reveal the appearance of both triangular and tetrahedral borate units. Electron spin resonance analyses indicate the presence of unpaired species in sufficient quantity to be identified and to confirm the spectral data. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Strontium borate glass: potential biomaterial for bone regeneration

    PubMed Central

    Pan, H. B.; Zhao, X. L.; Zhang, X.; Zhang, K. B.; Li, L. C.; Li, Z. Y.; Lam, W. M.; Lu, W. W.; Wang, D. P.; Huang, W. H.; Lin, K. L.; Chang, J.

    2010-01-01

    Boron plays important roles in many life processes including embryogenesis, bone growth and maintenance, immune function and psychomotor skills. Thus, the delivery of boron by the degradation of borate glass is of special interest in biomedical applications. However, the cytotoxicity of borate glass which arises with the rapid release of boron has to be carefully considered. In this study, it was found that the incorporation of strontium into borate glass can not only moderate the rapid release of boron, but also induce the adhesion of osteoblast-like cells, SaOS-2, thus significantly increasing the cyto-compatibility of borate glass. The formation of multilayers of apatite with porous structure indicates that complete degradation is optimistic, and the spread of SaOS-2 covered by apatite to form a sandwich structure may induce bone-like tissue formation at earlier stages. Therefore, such novel strontium-incorporated borosilicate may act as a new generation of biomaterial for bone regeneration, which not only renders boron as a nutritious element for bone health, but also delivers strontium to stimulate formation of new bones. PMID:20031984

  5. Strontium borate glass: potential biomaterial for bone regeneration.

    PubMed

    Pan, H B; Zhao, X L; Zhang, X; Zhang, K B; Li, L C; Li, Z Y; Lam, W M; Lu, W W; Wang, D P; Huang, W H; Lin, K L; Chang, J

    2010-07-06

    Boron plays important roles in many life processes including embryogenesis, bone growth and maintenance, immune function and psychomotor skills. Thus, the delivery of boron by the degradation of borate glass is of special interest in biomedical applications. However, the cytotoxicity of borate glass which arises with the rapid release of boron has to be carefully considered. In this study, it was found that the incorporation of strontium into borate glass can not only moderate the rapid release of boron, but also induce the adhesion of osteoblast-like cells, SaOS-2, thus significantly increasing the cyto-compatibility of borate glass. The formation of multilayers of apatite with porous structure indicates that complete degradation is optimistic, and the spread of SaOS-2 covered by apatite to form a sandwich structure may induce bone-like tissue formation at earlier stages. Therefore, such novel strontium-incorporated borosilicate may act as a new generation of biomaterial for bone regeneration, which not only renders boron as a nutritious element for bone health, but also delivers strontium to stimulate formation of new bones.

  6. Low-energy vibrational dynamics of cesium borate glasses.

    PubMed

    Crupi, C; D'Angelo, G; Vasi, C

    2012-06-07

    Low-temperature specific heat and inelastic light scattering experiments have been performed on a series of cesium borate glasses and on a cesium borate crystal. Raman measurements on the crystalline sample have revealed the existence of cesium rattling modes in the same frequency region where glasses exhibit the boson peak (BP). These localized modes are supposed to overlap with the BP in cesium borate glasses affecting its magnitude. Their influence on the low frequency vibrational dynamics in glassy samples has been considered, and their contribution to the specific heat has been estimated. Evidence for a relation between the changes of the BP induced by the increased amount of metallic oxide and the variations of the elastic medium has been provided.

  7. Structural and Luminescent property of Holmium doped Borate Glasses

    NASA Astrophysics Data System (ADS)

    Usharani, V. L.; Eraiah, B.

    2018-02-01

    Holmium doped Lithium Lead Borate glasses of different compositions were prepared by melt quenching technique. Fourier transform infrared investigations on lithium lead borate glasses have been made to study the local order and vibrations of atoms in the glass network and it contains mainly BO3 and BO4 structural units. Photoluminescence techniques were employed to investigate the luminescent property of these glasses excited at 451nm. Blue emission have been observed from the transition 495 (5F3 → 5I8).

  8. In vitro study of improved wound-healing effect of bioactive borate-based glass nano-/micro-fibers.

    PubMed

    Yang, Qingbo; Chen, Sisi; Shi, Honglan; Xiao, Hai; Ma, Yinfa

    2015-10-01

    Because of the promising wound-healing capability, bioactive glasses have been considered as one of the next generation hard- and soft-tissue regeneration materials. The lack of understanding of the substantial mechanisms, however, indicates the need for further study on cell-glass interactions to better interpret the rehabilitation capability. In the present work, three bioactive glass nano-/micro-fibers, silicate-based 45S5, borate-based 13-93B3 and 1605 (additionally doped with copper oxide and zinc oxide), were firstly compared for their in vitro soaking/conversion rate. The results of elemental monitoring and electron microscopic characterization demonstrated that quicker ion releasing and glass conversion occurred in borate-based fibers than that of silicate-based one. This result was also reflected by the formation speed of hydroxyapatite (HA). This process was further correlated with original boron content and surrounding rheological condition. We showed that an optimal fiber pre-soaking time (or an ideal dynamic flow rate) should exist to stimulate the best cell proliferation and migration ability. Moreover, 13-93B3 and 1605 fibers showed different glass conversion and biocompatibility properties as well, indicating that trace amount variation in composition can also influence fiber's bioactivity. In sum, our in vitro rheological module closely simulated in vivo niche environment and proved a potentially improved wound-healing effect by borate-based glass fibers, and the results shall cast light on future improvement in bioactive glass fabrication. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Thermal property of holmium doped lithium lead borate glasses

    NASA Astrophysics Data System (ADS)

    Usharani, V. L.; Eraiah, B.

    2018-04-01

    The new glass system of holmium doped lithium lead borate glasses were prepared by conventional melt quenching technique. The thermal stability of the different compositions of Ho3+ ions doped lithium lead borate glasses were studied by using TG-DTA. The Tg values are ranging from 439 to 444 °C with respect to the holmium concentration. Physical parameters like polaron radius(rp), inter-nuclear distance (ri), field strength (F) and polarizability (αm) of oxide ions were calculated using appropriate formulae.

  10. Raman and Infrared Spectroscopy of Yttrium Aluminum Borate Glasses and Glass-ceramics

    NASA Technical Reports Server (NTRS)

    Bradley, J.; Brooks, M.; Crenshaw, T.; Morris, A.; Chattopadhyay, K.; Morgan, S.

    1998-01-01

    Raman spectra of glasses and glass-ceramics in the Y2O3-Al2O3-B2O3 system are reported. Glasses with B2O3 contents ranging from 40 to 60 mole percent were prepared by melting 20 g of the appropriate oxide or carbonate powders in alumina crucibles at 1400 C for 45 minutes. Subsequent heat treatments of the glasses at temperatures ranging from 600 to 800 C were performed in order to induce nucleation and crystallization. It was found that Na2CO3 added to the melt served as a nucleating agent and resulted in uniform bulk crystallization. The Raman spectra of the glasses are interpreted primarily in terms of vibrations of boron - oxygen structural groups. Comparison of the Raman spectra of the glass-ceramic samples with spectra of aluminate and borate crystalline materials reveal that these glasses crystallize primarily as yttrium aluminum borate, YAl3(BO3)4.

  11. Novel method for early investigation of bioactivity in different borate bio-glasses

    NASA Astrophysics Data System (ADS)

    Abdelghany, A. M.

    Some ternary borate glasses were prepared and corrosion behavior of such ternary borate glasses after immersion in aqueous dilute phosphate solution was studied using different immersion times. Fourier transform infrared (FTIR) absorption spectral measurements were done before and after immersion in the mentioned solution for extended times up to 2 days to justify the appearance of the characteristic FTIR bands due to calcium phosphate (hydroxyapatite (HA)) which is considered as the potential indication of bioactivity. Experimental IR data confirm the beginning of the appearance of FTIR bands at about 580 and 620 cm-1 after 3 days and the complete resolution with its characteristic split form after 1 week and more. Deconvolution analysis technique (DAT) of the FTIR spectrum was employed to investigate the bioactivity of such ternary borate system after a short period of immersion. The corrosion behavior of such glasses is explained in relation to a suggested hydrolysis followed by direct dissolution mechanism. The ease of dissolution of all the borate glasses constituents explains the formation of calcium phosphate and conversion to crystalline hydroxyapatite within the borate glass matrix. X-ray diffraction may be used to retrace the structural changes and degree of crystallinity of the prepared glasses.

  12. Novel method for early investigation of bioactivity in different borate bio-glasses.

    PubMed

    Abdelghany, A M

    2013-01-01

    Some ternary borate glasses were prepared and corrosion behavior of such ternary borate glasses after immersion in aqueous dilute phosphate solution was studied using different immersion times. Fourier transform infrared (FTIR) absorption spectral measurements were done before and after immersion in the mentioned solution for extended times up to 2 days to justify the appearance of the characteristic FTIR bands due to calcium phosphate (hydroxyapatite (HA)) which is considered as the potential indication of bioactivity. Experimental IR data confirm the beginning of the appearance of FTIR bands at about 580 and 620 cm(-1) after 3 days and the complete resolution with its characteristic split form after 1 week and more. Deconvolution analysis technique (DAT) of the FTIR spectrum was employed to investigate the bioactivity of such ternary borate system after a short period of immersion. The corrosion behavior of such glasses is explained in relation to a suggested hydrolysis followed by direct dissolution mechanism. The ease of dissolution of all the borate glasses constituents explains the formation of calcium phosphate and conversion to crystalline hydroxyapatite within the borate glass matrix. X-ray diffraction may be used to retrace the structural changes and degree of crystallinity of the prepared glasses. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Synthesis of hydrophobic zinc borate nanoflakes and its effect on flame retardant properties of polyethylene

    NASA Astrophysics Data System (ADS)

    Li, Shengli; Long, Beihong; Wang, Zichen; Tian, Yumei; Zheng, Yunhui; Zhang, Qian

    2010-04-01

    Zinc borate (2ZnO·3B 2O 3·3.5H 2O) has relatively high dehydration on-set temperature which property permits processing in a wide range of polymer system. But zinc borate particles are hardly dispersed in a polymer matrix so that they prevent their using in industry. To address this problem, we synthesized hydrophobic zinc borate (2ZnO·3B 2O 3·3.5H 2O) nanoflakes by employing solid-liquid reaction of zinc oxide (ZnO) and boric acid (H 3BO 3) in the presence of oleic acid. This method does not bring pollution. By conducting morphological and microscopic analyses, we found that this compound displayed nanoflake morphology with particle size of around 100-200 nm, thickness less than 100 nm and there were uniform mesopores with the diameter about 10 nm within the particles. Furthermore, our products had an effect on flame retardant of polyethylene, especially when the zinc borate was modified by oleic acid.

  14. Scale-up synthesis of zinc borate from the reaction of zinc oxide and boric acid in aqueous medium

    NASA Astrophysics Data System (ADS)

    Kılınç, Mert; Çakal, Gaye Ö.; Yeşil, Sertan; Bayram, Göknur; Eroğlu, İnci; Özkar, Saim

    2010-11-01

    Synthesis of zinc borate was conducted in a laboratory and a pilot scale batch reactor to see the influence of process variables on the reaction parameters and the final product, 2ZnO·3B 2O 3·3.5H 2O. Effects of stirring speed, presence of baffles, amount of seed, particle size and purity of zinc oxide, and mole ratio of H 3BO 3:ZnO on the zinc borate formation reaction were examined at a constant temperature of 85 °C in a laboratory (4 L) and a pilot scale (85 L) reactor. Products obtained from the reaction in both reactors were characterized by chemical analysis, X-ray diffraction, particle size distribution analysis, thermal gravimetric analysis and scanning electron microscopy. The kinetic data for the zinc borate production reaction was fit by using the logistic model. The results revealed that the specific reaction rate, a model parameter, decreases with increase in particle size of zinc oxide and the presence of baffles, but increases with increase in stirring speed and purity of zinc oxide; however, it is unaffected with the changes in the amount of seed and reactants ratio. The reaction completion time is unaffected by scaling-up.

  15. FTIR of binary lead borate glass: Structural investigation

    NASA Astrophysics Data System (ADS)

    Othman, H. A.; Elkholy, H. S.; Hager, I. Z.

    2016-02-01

    The glass samples were prepared according to the following formula: (100-x) B2O3 - x PbO, where x = 20-80 mol% by melt quenching method. The density of the prepared samples was measured and molar volume was calculated. IR spectra were measured for the prepared samples to investigate the glass structure. The IR spectra were deconvoluted using curves of Gaussian shape at approximately the same frequencies. The deconvoluted data were used to study the effect of PbO content on all the structural borate groups. Some structural parameters such as density, packing density, bond length and bond force constant were theoretically calculated and were compared to the obtained experimental results. Deviation between the experimental and theoretically calculated parameters reflects the dual role of PbO content on the network of borate glass.

  16. In vitro evaluation of cytotoxicity of silver-containing borate bioactive glass.

    PubMed

    Luo, Shi-Hua; Xiao, Wei; Wei, Xiao-Juan; Jia, Wei-Tao; Zhang, Chang-Qing; Huang, Wen-Hai; Jin, Dong-Xu; Rahaman, Mohamed N; Day, Delbert E

    2010-11-01

    The cytotoxicity of silver-containing borate bioactive glass was evaluated in vitro from the response of osteoblastic and fibroblastic cells in media containing the dissolution products of the glass. Glass frits containing 0-2 weight percent (wt %) Ag were prepared by a conventional melting and quenching process. The amount of Ag dissolved from the glass into a simulated body fluid (SBF), measured using atomic emission spectroscopy, increased rapidly within the first 48 h, but slowed considerably at longer times. Structural and microchemical analysis showed that the formation of a hydroxyapatite-like layer on the glass surface within 14 days of immersion in the SBF. The response of MC3T3-E1 and L929 cells to the dissolution products of the glass was evaluated using SEM observation of cell morphology, and assays of MTT hydrolysis, lactate dehydrogenase release, and alkaline phosphatase activity after incubation for up to 48 h. Cytotoxic effects were found for the borate glass containing 2 wt % Ag, but not for 0.75 and 1 wt % Ag. This borate glass containing up to ∼1 wt % Ag could provide a coating material for bacterial inhibition and enhanced bioactivity of orthopaedic implant materials such as titanium. © 2010 Wiley Periodicals, Inc.

  17. Self-assembled 3D zinc borate florets via surfactant assisted synthesis under moderate pressures: Process temperature dependent morphology study

    NASA Astrophysics Data System (ADS)

    Mahajan, Dhiraj S.; Deshpande, Tushar; Bari, Mahendra L.; Patil, Ujwal D.; Narkhede, Jitendra S.

    2018-04-01

    In the present study, we prepared zinc borates using aqueous phase synthesis under moderate pressures (MP) (<150 psi) with ethanol as a co-solvent in the presence of a quaternary ammonium surfactant-Cetyltrimethylammonium bromide (CTAB). 3D morphologies of self-assembled zinc borate (Zn(H2O)B2O4 · 0.12 H2O, Zn3B6O12 · 3.5H2O, ZnB2O4) resembling flower-like structures were obtained by varying temperature under moderate pressure conditions. Synthesized zinc borates’ florets were morphologically characterized by Field Emission Scanning Electron Microscopy. The x-ray diffractions of borate species reveal rhombohydra, monoclinic and cubic phases of zinc borate crystals as a function of process temperature. Additionally, thermal analysis confirms excellent dehydration/degradation behavior for the zinc borate crystals synthesized at moderate pressures and elevated temperatures and could be utilized as potential flame retardant fillers in the polymer matrices.

  18. CADMIUM-RARE EARTH BORATE GLASS AS REACTOR CONTROL MATERIAL

    DOEpatents

    Ploetz, G.L.; Ray, W.E.

    1958-11-01

    A reactor control rod fabricated from a cadmiumrare earth-borate glass is presented. The rare earth component of this glass is selected from among those rare earths having large neutron capture cross sections, such as samarium, gadolinium or europium. Partlcles of this glass are then dispersed in a metal matrix by standard powder metallurgy techniques.

  19. Rare earth-doped lead borate glasses and transparent glass-ceramics: structure-property relationship.

    PubMed

    Pisarski, W A; Pisarska, J; Mączka, M; Lisiecki, R; Grobelny, Ł; Goryczka, T; Dominiak-Dzik, G; Ryba-Romanowski, W

    2011-08-15

    Correlation between structure and optical properties of rare earth ions in lead borate glasses and glass-ceramics was evidenced by X-ray-diffraction, Raman, FT-IR and luminescence spectroscopy. The rare earths were limited to Eu(3+) and Er(3+) ions. The observed BO(3)↔BO(4) conversion strongly depends on the relative PbO/B(2)O(3) ratios in glass composition, giving important contribution to the luminescence intensities associated to (5)D(0)-(7)F(2) and (5)D(0)-(7)F(1) transitions of Eu(3+). The near-infrared luminescence and up-conversion spectra for Er(3+) ions in lead borate glasses before and after heat treatment were measured. The more intense and narrowing luminescence lines suggest partial incorporation of Er(3+) ions into the orthorhombic PbF(2) crystalline phase, which was identified using X-ray diffraction analysis. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. Dosimetric properties of dysprosium doped lithium borate glass irradiated by 6 MV photons

    NASA Astrophysics Data System (ADS)

    Ab Rasid, A.; Wagiran, H.; Hashim, S.; Ibrahim, Z.; Ali, H.

    2015-07-01

    Undoped and dysprosium doped lithium borate glass system with empirical formula (70-x) B2O3-30 Li2O-(x) Dy2O3 (x=0.1, 0.3, 0.5, 0.7, 1.0 mol%) were prepared using the melt-quenching technique. The dosimetric measurements were performed by irradiating the samples to 6 MV photon beam using linear accelerator (LINAC) over a dose range of 0.5-5.0 Gy. The glass series of dysprosium doped lithium borate glass produced the best thermoluminescence (TL) glow curve with the highest intensity peak from sample with 1.0 mol% Dy2O3 concentration. Minimum detectable dose was detected at 2.24 mGy, good linearity of regression coefficient, high reproducibility and high sensitivity compared to the undoped glass are from 1.0 mol% dysprosium doped lithium borate glass. The results indicated that the series of dysprosium doped lithium glasses have a great potential to be considered as a thermoluminescence dosimetry (TLD).

  1. Bright up-conversion white light emission from Er3+ doped lithium fluoro zinc borate glasses for photonic applications

    NASA Astrophysics Data System (ADS)

    Vijayalakshmi, L.; Naveen Kumar, K.; Rao, K. Srinivasa; Hwang, Pyung

    2018-03-01

    Various concentrations of Er3+ (0.3, 0.5, 1.0 and 1.5 mol %) doped lithium fluoro zinc borate glasses were synthesized by a traditional melt quenching method. XRD, FTIR and FESEM have been employed to analyze the structural, compositional and morphological analysis respectively. Judd-Ofelt theory has been employed to analyze the intensity parameters (Ωλ, λ = 2, 4 and 6) which can be used to estimate the radiative properties of fluorescent levels of Er3+. We have been observed a strong NIR emission peak at 1.53 μm (4I13/2 → 4I15/2) under the excitation of 980 nm from Er3+: LBZ glasses. Nevertheless, the NIR emission is remarkably enhanced by increasing the Er3+ ions concentration until the optimized concentration of 0.5 mol%. The lifetime of the excited level of 4I13/2 in the NIR emission transition is evaluated and it is found to be1.22 ms from the decay analysis of 0.5 mol% Er3+: LBZ glass. Apart from the NIR emission, a bright up-conversion green emission is observed at 544 nm (4S3/2 → 4I15/2) along with an intense red emission at 659 nm (4F9/2 → 4I15/2) and a weak blue emission (2H9/2 → 4I15/2) under the excitation of 980 nm. Up-conversion emission features were significantly enhanced with increasing the Er3+ concentration up to 1.0 mol%. The combination of the obtained up-conversion emission colors of green, red and blue could generate white light emission. The cool white-light emission from the optimized glass sample has been confirmed from the Commission International de I'Echairage (CIE) 1931 chromaticity diagram analysis and their correlated color temperature (CCT) values. Based on the NIR and up-conversion emission features, Er3+: LBZ glasses could be suggested as promising candidates for optical amplifiers, optical telecommunication windows and white light photonic applications.

  2. Structural properties of molybdenum-lead-borate glasses.

    PubMed

    Rada, M; Rada, S; Pascuta, P; Culea, E

    2010-11-01

    Glasses and glass ceramics in the system xMoO₃·(100 - x)[3B₂O₃·PbO] with 0 ≤ x ≤ 30 mol% have been prepared from melt quenching method and characterized by means of X-ray diffraction, FTIR, UV-VIS and EPR spectroscopy. We have examined and analyzed the effects of systematic molybdenum ions intercalation on lead-borate glasses and glass ceramics with interesting results. The observations present in these mechanisms show the lead ions bonded ionic have a strong affinity towards [BO₃] units containing non-bridging oxygens and [MoO₄]²⁻ molybdate units. The pronounced affinity towards molybdate anions yields the formation of the PbMoO₄ crystalline phase. Then, the excess of oxygen can be supported into the glass network by the formation of [MoO₆] and [Mo₂O₇] structural units. Pb²(+) ions with 6s² configuration show strong absorption in the ultraviolet due to parity allowed s²-sp transition and yield an absorption band centered at about 310 nm. The changes in the features of the absorption bands centered at about 310 nm can be explained as a consequence of the appearance of additional absorption shoulder due to photoinduced color centers in the glass such as the formation of borate-molybdate and lead-molybdate paramagnetic defect centers in the glasses. The concentration of molybdenum ions influences the shape and width of the EPR signals located at g ∼ 1.86, 1.91 and 5.19. The microenvironment of molybdenum ions in glasses is expected to have mainly sixfold coordination. However, there is a possibility of reduction of a part of molybdenum ions from the Mo⁶(+) to the Mo⁵(+) and Mo⁴(+) to the Mo³(+) states. Copyright © 2010 Elsevier B.V. All rights reserved.

  3. Optical absorption and photoluminescence properties of Er3+ doped mixed alkali borate glasses.

    PubMed

    Ratnakaram, Y C; Kumar, A Vijaya; Naidu, D Tirupathi; Rao, J L

    2005-07-01

    An investigations of the optical absorption and fluorescence spectra of 0.2 mol% Er2O3 in mixed alkali borate glasses of the type 67.8B2O3 x xLi2O(32-x)Na2O, 67.8B2O3 x xLi2O(32-x)K2O and 67.8B2O3 x xNa2O(32-x)K2O (where x = 8, 12, 16, 20 and 24) are presented. The glasses were obtained by quenching melts consisting of H3BO3, Li2CO3, Na2CO3, K2CO3 and Er2O3 (950-1100 degrees C, 1.5-2 h) between two brass plates. Spectroscopic parameters like Racah (E1, E2 and E3), spin-orbit (xi(4f)) and configuration interaction (alpha) parameters are deduced as function of x. Using Judd-Ofelt theory, Judd-Ofelt intensity parameters (omega2, omega4 and omega6) are obtained. Radiative and non-radiative transition rates (A(T) and W(MPR)), radiative lifetimes (tauR), branching ratios (beta) and integrated absorption cross-sections (sigma) have been computed for certain excited states of Er3+ in these mixed alkali borate glasses. Emission spectra have been studied for all the three Er3+ doped mixed alkali borate glasses. The present paper throws light on the trends observed in the intensity parameters, radiative lifetimes, branching ratios and emission cross-sections as a function of x in these borate glasses, keeping in view the effect of mixed alkalies in borate glasses.

  4. Cell adhesion to borate glasses by colloidal probe microscopy.

    PubMed

    Wiederhorn, Sheldon M; Chae, Young-Hun; Simon, Carl G; Cahn, Jackson; Deng, Yan; Day, Delbert

    2011-05-01

    The adhesion of osteoblast-like cells to silicate and borate glasses was measured in cell growth medium using colloidal probe microscopy. The probes consisted of silicate and borate glass spheres, 25-50 μm in diameter, attached to atomic force microscope cantilevers. Variables of the study included glass composition and time of contact of the cell to the glasses. Increasing the time of contact from 15 to 900 s increased the force of adhesion. The data could be plotted linearly on a log-log plot of adhesive force versus time. Of the seven glasses tested, five had slopes close to 0.5, suggesting a square root dependence of the adhesive force on the contact time. Such behavior can be interpreted as a diffusion limited process occurring during the early stages of cell attachment. We suggest that the rate limiting step in the adhesion process is the diffusion of integrins resident in the cell membrane to the area of cell attachment. Data presented in this paper support the hypothesis of Hench et al. that strong adhesion depends on the formation of a calcium phosphate reaction layer on the surfaces of the glass. Glasses that did not form a calcium phosphate layer exhibited a weaker adhesive force relative to those glasses that did form a calcium phosphate layer. Published by Elsevier Ltd.

  5. Synthesis and characterization of cerium- and gallium-containing borate bioactive glass scaffolds for bone tissue engineering.

    PubMed

    Deliormanlı, Aylin M

    2015-02-01

    Bioactive glasses are widely used in biomedical applications due to their ability to bond to bone and even to soft tissues. In this study, borate based (13-93B3) bioactive glass powders containing up to 5 wt% Ce2O3 and Ga2O3 were prepared by the melt quench technique. Cerium (Ce+3) and gallium (Ga+3) were chosen because of their low toxicity associated with bacteriostatic properties. Bioactive glass scaffolds were fabricated using the polymer foam replication method. In vitro degradation and bioactivity of the scaffolds were evaluated in SBF under static conditions. Results revealed that the cerium- and gallium-containing borate glasses have much lower degradation rates compared to the bare borate glass 13-93B3. In spite of the increased chemical durability, substituted glasses exhibited a good in vitro bioactive response except when the Ce2O3 content was 5 wt%. Taking into account the high in vitro hydroxyapatite forming ability, borate glass scaffolds containing Ce+3 and Ga+3 therapeutic ions are promising candidates for bone tissue engineering applications.

  6. Crystallization of lithium borate glasses

    NASA Technical Reports Server (NTRS)

    Goktas, A. A.; Neilson, G. F.; Weinberg, M. C.

    1992-01-01

    The glass-forming ability and crystallization behavior of lithium borate compositions, in the diborate-to-metaborate-range, were studied. In particular, the nature and sequence of formation of crystalline phases and the tendency toward devitrification were investigated as functions of temperature, thermal history and batch composition. It was found that the sequence of crystalline phase formation was sensitive to all of the three latter factors, and it was observed that under certain conditions metastable defect structures of the metaborate can appear.

  7. Structural study and DC conductivity of vanadyl doped zinc lithium borate glasses

    NASA Astrophysics Data System (ADS)

    Seema, Khasa, S.; Dahiya, M. S.; Yadav, Arti; Agarwal, A.; Dahiya, S.

    2015-06-01

    Glasses with composition xZnOṡ(30 - x)ṡLi2Oṡ70B2O3 containing 2 mol% of V2O5 (x = 0, 2, 5, 7 and 10) were prepared by standard melt-quench technique. The amorphous nature of the glass samples was confirmed by using x-ray diffraction. The structural changes in these glasses have been investigated by employing IR spectroscopy in the mid-IR range. The infrared spectroscopic analysis confirms the presence of both triangular and tetraheldral coordinated boron units and absence of boroxol ring. It also shows that metal-oxide vibrations are present which are due to the bonding of lithium and zinc ions with oxygen. The dc conductivity was measured in the temperature range 353-523 K. The dc conductivity results show that conductivity decreases and activation energy increases when Li2O is replaced by ZnO, keeping the concentration of B2O3 constant. Decrease in conductivity and increase in activation energy shows that addition of ZnO to the glass matrix shows a "blocking effect" on the overall mobility of alkali ions, but at higher concentration the hopping effect was also observed.

  8. Magnesium and zinc borate enhance osteoblastic differentiation of stem cells from human exfoliated deciduous teeth in vitro.

    PubMed

    Liu, Yao-Jen; Su, Wen-Ta; Chen, Po-Hung

    2018-01-01

    Various biocompatible and biodegradable scaffolds blended with biochemical signal molecules with adequate osteoinductive and osteoconductive properties have attracted significant interest in hard tissue engineering regeneration. We evaluated the distinct effects of magnesium borate, zinc borate, and boric acid blended into chitosan scaffold for osteogenic differentiation of stem cells from exfoliated deciduous teeth. Stem cells from exfoliated deciduous teeth cells are a potential source of functional osteoblasts for applications in bone tissue engineering, but the efficiency of osteoblastic differentiation is low, thereby significantly limiting their clinical applications. Divalent metal borates have potential function in bone remodeling because they can simulate bone formation and decrease bone resorption. These magnesium, zinc, and B ions can gradually be released into the culture medium from the scaffold and induce advanced osteoblastic differentiation from stem cells from exfoliated deciduous teeth. Stem cells from exfoliated deciduous teeth with magnesium borate or zinc borate as inducer demonstrated more osteoblastic differentiation after 21 days of culture. Differentiated cells exhibited activity of alkaline phosphatase, bone-related gene expression of collagen type I, runt-related transcription factor 2, osteopontin, osteocalcin, vascular endothelial growth factor, and angiopoietin-1, as noted via real-time polymerase chain reaction analysis, as well as significant deposits of calcium minerals. Divalent mental magnesium and zinc and nonmetal boron can be an effective inducer of osteogenesis for stem cells from exfoliated deciduous teeth. This experiment might provide useful inducers for osteoblastic differentiation of stem cells from exfoliated deciduous teeth for tissue engineering and bone repair.

  9. Characterization of the third-order optical nonlinearity spectrum of barium borate glasses

    NASA Astrophysics Data System (ADS)

    Santos, S. N. C.; Almeida, J. M. P.; Paula, K. T.; Tomazio, N. B.; Mastelaro, V. R.; Mendonça, C. R.

    2017-11-01

    Borate glasses have proven to be an important material for applications ranging from radiation dosimetry to nonlinear optics. In particular, B2O3-BaO based glasses are attractive to frequency generation since their barium metaborate phase (β-BaB2O4 or β-BBO) may be crystallized under proper heat treatment. Despite the vast literature covering their linear and second-order optical nonlinear properties, their third-order nonlinearities remain overlooked. This paper thus reports a study on the nonlinear refraction (n2) of BBO and BBS-DyEu glasses through femtosecond Z-scan technique. The results were modeled using the BGO approach, which showed that oxygen ions are playing a role in the nonlinear optical properties of the glasses studied here. In addition, the barium borate glasses containing rare-earths ions were found to exhibit larger nonlinearities, which is in agreement with previous studies.

  10. Spectroscopic and ultrasonic investigations on structural characterization of borate glass specimen doped with transition metal ions.

    PubMed

    Sathish, K; Thirumaran, S

    2015-08-05

    The present work describes the glass samples of composition (x% V₂O₅-(80-x)% B₂O₃-20% Na₂CO₃) VBS glass system and (x%MnO₂-(80-x)% B₂O₃-20% Na₂CO₃) in MBS glass system with mol% ranging from x=3, 6, 9, 12, 15 and 18 in steps of 3 mol% are prepared by melt quenching technique. For these prepared glass systems, sound velocity (longitudinal and shear velocities) and density have been measured. The sound velocity (longitudinal and shear) was measured by using pulse-echo technique at 5 MHz. The XRD study was carried to out to ascertain the amorphous nature of the glass specimen. Using these measured values, the elastic moduli, Poisson's ratio, Debye temperature, acoustic impedance and thermal expansion coefficient of the two glass systems were evaluated. The elastic and mechanical properties of the prepared glass systems are analyzed from ultrasonic study and the structural characterization from spectroscopic study. The effects due to the doping of transition metal ions with borate have been discussed. In the V₂O₅ doped glass system,(VBS glass system) the sound velocity, density and elastic moduli, steeply increases after 12 mol% comparatively with MnO₂ doped glass system (VBS glass system). The present study critically observes the doping of V₂O₅ with borate enhances the strengthening of network linkage and hardening of the glassy network structure than MnO₂. The IR spectral analysis reveals depolymerization of the borate network and conversion of BO₃ or BO4 units with the formation of non-bridging oxygen. The FTIR spectral studies confirm the presence of various functional groups of the sample. FTIR spectrum of sample exhibits broad absorption bands indicating the wide distribution of borate structural units. The effect of Na₂CO₃, V₂O₅ and MnO₂ contents on the structures of borate glass is evaluated from the FTIR spectra. The topological aspects of the prepared glass samples are exhaustively reported from SEM micrographs

  11. Relationship between Eu{sup 3+} reduction and glass polymeric structure in Al{sub 2}O{sub 3}-modified borate glasses under air atmosphere

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jiao, Qing; Yu, Xue; Xu, Xuhui

    2013-06-15

    The reduction of Eu{sup 3+} to Eu{sup 2+} is realized efficiently in Eu{sub 2}O{sub 3}-doped borate glasses prepared under air condition by melting-quenching method. Luminescent spectra show an increasing tendency of Eu{sup 2+} emission with increasing Al{sub 2}O{sub 3} concentration in B{sub 2}O{sub 3}–Na{sub 2}O glasses. It is interesting that significant enhancement appeared of Eu{sup 2+} luminescence in the Al{sub 2}O{sub 3}-rich sample comparing to the samples of Al{sub 2}O{sub 3} less than 6 mol%. FTIR and Raman scattering measurements indicated that some new vibration modes assigned to the low-polymerized structure groups decomposed from the slight Al{sub 2}O{sub 3} dopantmore » samples. These results demonstrated that the polymerization of the glass structure decreased with increasing incorporation of Al{sub 2}O{sub 3} into the borate glasses, linking to the efficiency of Eu{sup 3+} self-reduction in air at high temperature. - graphical abstract: A novel europium valence reduction phenomenon occurred in Al{sub 2}O{sub 3} modified borate glasses, FTIR and Raman measurements revealed that high polymeric groups were destroyed to low polymery structures with Al{sub 2}O{sub 3} addition. - Highlights: • The efficient reduction of Eu{sup 3+} to Eu{sup 2+} is observed in the B{sub 2}O{sub 3}–Na{sub 2}O glasses. • Eu{sup 2+} luminescence is significant enhanced in the Al{sub 2}O{sub 3}-rich glasses. • The introduction of Al{sub 2}O{sub 3} changed the network structure of the borate glasses. • High polymeric borate groups in the glass matrix may be destroyed to the lower ones.« less

  12. Visible luminescence of dysprosium ions in oxyhalide lead borate glasses.

    PubMed

    Pisarska, Joanna; Żur, Lidia; Pisarski, Wojciech A

    2011-08-15

    Visible luminescence of Dy(3+) ions in oxyhalide lead borate glasses was examined. Luminescence spectra show two intense bands at 480 nm and 573 nm due to (4)F(9/2)→(6)H(15/2) (blue) and (4)F(9/2)→(6)H(13/2) (yellow) transitions of Dy(3+). Luminescence decays from (4)F(9/2) state and yellow-to-blue luminescence intensity ratios (Y/B) were analysed with PbX(2) (X=F, Cl) content. An introduction of PbX(2) to the borate glass results in the increasing of (4)F(9/2) lifetime and the decreasing of yellow-to-blue luminescence intensity ratio, which is due to reduction of covalency between Dy(3+) and O(2-)/X(-) ions. Copyright © 2010 Elsevier B.V. All rights reserved.

  13. Effects of borate-based bioactive glass on neuron viability and neurite extension.

    PubMed

    Marquardt, Laura M; Day, Delbert; Sakiyama-Elbert, Shelly E; Harkins, Amy B

    2014-08-01

    Bioactive glasses have recently been shown to promote regeneration of soft tissues by positively influencing tissue remodeling during wound healing. We were interested to determine whether bioactive glasses have the potential for use in the treatment of peripheral nerve injury. In these experiments, degradable bioactive borate glass was fabricated into rods and microfibers. To study the compatibility with neurons, embryonic chick dorsal root ganglia (DRG) were cultured with different forms of bioactive borate glass. Cell viability was measured with no media exchange (static condition) or routine media exchange (transient condition). Neurite extension was measured within fibrin scaffolds with embedded glass microfibers or aligned rod sheets. Mixed cultures of neurons, glia, and fibroblasts growing in static conditions with glass rods and microfibers resulted in decreased cell viability. However, the percentage of neurons compared with all cell types increased by the end of the culture protocol compared with culture without glass. Furthermore, bioactive glass and fibrin composite scaffolds promoted neurite extension similar to that of control fibrin scaffolds, suggesting that glass does not have a significant detrimental effect on neuronal health. Aligned glass scaffolds guided neurite extension in an oriented manner. Together these findings suggest that bioactive glass can provide alignment to support directed axon growth. © 2013 Wiley Periodicals, Inc.

  14. Electrical Characteristics of MnO2 Doped Bismuth Borate Glass Systems

    NASA Astrophysics Data System (ADS)

    Nissar, Umair; Ahmad, Javed; Rana, Anwar Manzoor; Bukhari, S. H.; Jamil, M. T.; Khan, J. Alam; Shakeel, R.; Nadeem, M. Y.

    2018-02-01

    Transparent glasses have a large number of applications in the industry of electronics as well as optical devices. xMnO2-(25- x) Bi2O3-75H3BO3 (0 ≤ x ≤ 1.5 mol.%) transparent glasses have been prepared via melt-quench technique and characterized using dc electrical measurements, and by analyzing x-ray diffraction and Fourier transform infrared (FTIR) spectra. These characteristics were examined to understand the role of modifier oxides, i.e., Bi2O3 and MnO2 in the B2O3 glass network. Adding MnO2 into a glass network causes structural changes, which are responsible for any variations in electrical characteristics of bismuth borate glasses. Manganese bismuth borate glasses (MBBG) show Ohmic conduction at low fields; however, glasses with higher manganese content seem to conduct through bulk limited Poole-Frenkel mechanism. FTIR spectroscopy analyses depict the presence of BO3 and BO4 groups along with B-O-B and Bi-O-Bi bonding vibrations. Glasses with higher MnO2 content also show Mn-O bond vibrations. The reduction of BO4 groups and increase of BO3 units lead to the formation of non-bridging oxygens (NBOs) which are responsible for the variations in the electrical properties of these glasses.

  15. Spectroscopic properties of some borate glasses containg uranium

    NASA Astrophysics Data System (ADS)

    Culea, E.; Milea, I.; Bratu, I.

    1993-03-01

    Spectroscopic properties of some borate glasses containing 1-5%UO 3 have been studied in the fields of 700-1200 cm -1 and 10,000-30,000 cm -1 Absorption bands specific for U 6+ and U 4+ ions were observed. The increase of the melting time produces the reduction of U 6+ ions to U 4+.

  16. Infrared-to-visible conversion luminescence of Er 3+ ions in lead borate transparent glass-ceramics

    NASA Astrophysics Data System (ADS)

    Pisarski, Wojciech A.; Pisarska, Joanna; Lisiecki, Radosław; Grobelny, Łukasz; Dominiak-Dzik, Grażyna; Ryba-Romanowski, Witold

    2009-10-01

    Transparent glass-ceramics were successfully prepared during controlled heat treatment of lead borate glasses. The PbF 2 particles were dispersed into a borate glass matrix which was evidenced by X-ray diffraction analysis. The phase identification revealed that crystalline peaks can be related to the orthorhombic PbF 2 phase. Green up-conversion luminescence due to the 4S 3/2- 4I 15/2 transition of Er 3+ ions was registered. In comparison to the precursor glass the luminescence intensity was considerably higher, whereas the luminescence linewidth slightly decreased in the studied oxyfluoride transparent glass-ceramics. It indicated that a part of the trivalent erbium was incorporated into the PbF 2 crystalline phase.

  17. Spectroscopic and ultrasonic investigations on structural characterization of borate glass specimen doped with transition metal ions

    NASA Astrophysics Data System (ADS)

    Sathish, K.; Thirumaran, S.

    2015-08-01

    The present work describes the glass samples of composition (x% V2O5-(80-x)% B2O3-20% Na2CO3) VBS glass system and (x% MnO2-(80-x)% B2O3-20% Na2CO3) in MBS glass system with mol% ranging from x = 3, 6, 9, 12, 15 and 18 in steps of 3 mol% are prepared by melt quenching technique. For these prepared glass systems, sound velocity (longitudinal and shear velocities) and density have been measured. The sound velocity (longitudinal and shear) was measured by using pulse-echo technique at 5 MHz. The XRD study was carried to out to ascertain the amorphous nature of the glass specimen. Using these measured values, the elastic moduli, Poisson's ratio, Debye temperature, acoustic impedance and thermal expansion coefficient of the two glass systems were evaluated. The elastic and mechanical properties of the prepared glass systems are analyzed from ultrasonic study and the structural characterization from spectroscopic study. The effects due to the doping of transition metal ions with borate have been discussed. In the V2O5 doped glass system, (VBS glass system) the sound velocity, density and elastic moduli, steeply increases after 12 mol% comparatively with MnO2 doped glass system (VBS glass system). The present study critically observes the doping of V2O5 with borate enhances the strengthening of network linkage and hardening of the glassy network structure than MnO2. The IR spectral analysis reveals depolymerization of the borate network and conversion of BO3 or BO4 units with the formation of non-bridging oxygen. The FTIR spectral studies confirm the presence of various functional groups of the sample. FTIR spectrum of sample exhibits broad absorption bands indicating the wide distribution of borate structural units. The effect of Na2CO3, V2O5 and MnO2 contents on the structures of borate glass is evaluated from the FTIR spectra. The topological aspects of the prepared glass samples are exhaustively reported from SEM micrographs.

  18. Reaction of sodium calcium borate glasses to form hydroxyapatite.

    PubMed

    Han, Xue; Day, Delbert E

    2007-09-01

    This study investigated the transformation of two sodium calcium borate glasses to hydroxyapatite (HA). The chemical reaction was between either 1CaO . 2Na(2)O . 6B(2)O(3) or 2CaO . 2Na(2)O . 6B(2)O(3) glass and a 0.25 M phosphate (K(2)HPO(4)) solution at 37, 75 and 200 degrees C. Glass samples in the form of irregular particles (125-180 microm) and microspheres (45-90 and 125-180 microm) were used in order to understand the reaction mechanism. The effect of glass composition (calcium content) on the weight loss rate and reaction temperature on crystal size, crystallinity and grain shape of the reaction products were studied. Carbonated HA was made by dissolving an appropriate amount of carbonate (K(2)CO(3)) in the 0.25 M phosphate solution. X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy were used to characterize the reaction products. The results show that sodium calcium borate glasses can be transformed to HA by reacting with a phosphate solution. It is essentially a process of dissolution of glass and precipitation of HA. The transformation begins from an amorphous state to calcium-deficient HA without changing the size and shape of the original glass sample. Glass with a lower calcium content (1CaO . 2Na(2)O . 6B(2)O(3)), or reacted at an elevated temperature (75 degrees C), has a higher reaction rate. The HA crystal size increases and grain shape changes from spheroidal to cylindrical as temperature increases from 37 to 200 degrees C. Increase in carbonate concentration can also decrease the crystal size and yield a more needle-like grain shape.

  19. A medium range order structural connection to the configurational heat capacity of borate-silicate mixed glasses.

    PubMed

    Liu, Hao; Smedskjaer, Morten M; Tao, Haizheng; Jensen, Lars R; Zhao, Xiujian; Yue, Yuanzheng

    2016-04-28

    It has been reported that the configurational heat capacity (C(p,conf)) first increases and then becomes saturated with increasing B2O3/SiO2 ratio in borate-silicate mixed glasses. Through Raman spectroscopy measurements, we have, in this work, found an implication for the intermediate range order (IRO) structural connection to the composition dependence of the C(p,conf) of borate-silicate mixed glasses. In the silica-rich compositions, the C(p,conf) rapidly increases with increasing B2O3 content. This is attributed to the increase of the content of the B-O-Si network units ([B2Si2O8](2-)) and 6-membered borate rings with 1 or 2 B(4). In the boron-rich compositions, the C(p,conf) is almost constant, independent of the increase in the B2O3/SiO2 ratio. This is likely attributed to the counteraction between the decrease of the fraction of two types of metaborate groups and the increase of the fraction of other borate superstructural units (particularly 6-membered borate rings). The overall results suggest that the glasses containing more types of superstructural units have a larger C(p,conf).

  20. Exchange-mediated spin-lattice relaxation of Fe3+ ions in borate glasses.

    PubMed

    Misra, Sushil K; Pilbrow, John R

    2007-03-01

    Spin-lattice relaxation times (T1) of two borate glasses doped with different concentrations of Fe2O3 were measured using the Electron Spin-Echo (ESE) technique at X-band (9.630 GHz) in the temperature range 2-6K. In comparison with a previous investigation of Fe3+-doped silicate glasses, the relaxation rates were comparable and differed by no more than a factor of two. The data presented here extend those previously reported for borate glasses in the 10-250K range but measured using the amplitude-modulation technique. The T1 values were found to depend on temperature (T) as T(n) with n approximately 1 for the 1% and 0.1% Fe2O3-doped glass samples. These results are consistent with spin-lattice relaxation as effected by exchange interaction of a Fe3+ spin exchange-coupled to another Fe3+ spin in an amorphous material.

  1. Evaluation of borate bioactive glass scaffolds with different pore sizes in a rat subcutaneous implantation model.

    PubMed

    Deliormanli, Aylin M; Liu, Xin; Rahaman, Mohamed N

    2014-01-01

    Borate bioactive glass has been shown to convert faster and more completely to hydroxyapatite and enhance new bone formation in vivo when compared to silicate bioactive glass (such as 45S5 and 13-93 bioactive glass). In this work, the effects of the borate glass microstructure on its conversion to hydroxyapatite (HA) in vitro and its ability to support tissue ingrowth in a rat subcutaneous implantation model were investigated. Bioactive borate glass scaffolds, designated 13-93B3, with a grid-like microstructure and pore widths of 300, 600, and 900 µm were prepared by a robocasting technique. The scaffolds were implanted subcutaneously for 4 weeks in Sprague Dawley rats. Silicate 13-93 glass scaffolds with the same microstructure were used as the control. The conversion of the scaffolds to HA was studied as a function of immersion time in a simulated body fluid. Histology and scanning electron microscopy were used to evaluate conversion of the bioactive glass implants to hydroxyapatite, as well as tissue ingrowth and blood vessel formation in the implants. The pore size of the scaffolds was found to have little effect on tissue infiltration and angiogenesis after the 4-week implantation.

  2. Dosimetric properties of dysprosium doped calcium magnesium borate glass subjected to Co-60 gamma ray

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Omar, R. S., E-mail: ratnasuffhiyanni@gmail.com; Wagiran, H., E-mail: husin@utm.my; Saeed, M. A.

    Thermoluminescence (TL) dosimetric properties of dysprosium doped calcium magnesium borate (CMB:Dy) glass are presented. This study is deemed to understand the application of calcium as the modifier in magnesium borate glass with the presence of dysprosium as the activator to be performed as TL dosimeter (TLD). The study provides fundamental knowledge of a glass system that may lead to perform new TL glass dosimetry application in future research. Calcium magnesium borate glass systems of (70-y) B{sub 2}O{sub 3} − 20 CaO – 10 MgO-(y) Dy{sub 2}O{sub 3} with 0.05  mol % ≤ y ≤ 0.7  mol % of dyprosium weremore » prepared by melt-quenching technique. The amorphous structure and TL properties of the prepared samples were determined using powder X-ray diffraction (XRD) and TL reader; model Harshaw 4500 respectively. The samples were irradiated to Co-60 gamma source at a dose of 50 Gy. Dosimetric properties such as annealing procedure, time temperature profile (TTP) setting, optimization of Dy{sub 2}O{sub 3} concentration of 0.5 mol % were determined for thermoluminescence dosimeter (TLD) reader used.« less

  3. Structure-property relations in lanthanide borate glasses

    NASA Technical Reports Server (NTRS)

    Chakraborty, I. N.; Day, D. E.; Lapp, J. C.; Shelby, J. E.

    1985-01-01

    Glass formation in the system Ln2O3-B2O3 (Ln = Nd, Sm) was studied. Glasses could be formed in the range from 0 to 28 mol pct rare-earth oxide (Ln2O3), but liquid immiscibility in these systems limits the range of homogeneous glasses to 0 to 1.5 and 25 to 28 mol pct Ln2O3. The infrared spectra indicate that the rare-earth-rich glasses are structurally similar to rare-earth metaborates (LnB3O6) which contain (B3O6)-infinity chains. The variation in density, transformation temperature, thermal expansion coefficient, and transformation-range viscosity of these glasses with the size of the rare-earth ion is discussed. Glasses near the metaborate composition have a transformation temperature of about 700 C, which is high for binary borate glasses. Glasses could not be formed in the systems Eu2O3-, Gd2O3-, Ho2O3-, and Er2O3-B2O3, even by quenching at 1300 C/s. The sudden lack of glass formation in the system Ln2O3-B2O3 with Ln(3+) ions smaller than Sm(3+) is explained on the basis of the size effect of the Ln(3+) ion on the stability of (B3O6)-infinity chains in these metaborates.

  4. In vitro bioactivity, cytocompatibility, and antibiotic release profile of gentamicin sulfate-loaded borate bioactive glass/chitosan composites.

    PubMed

    Cui, Xu; Gu, Yifei; Li, Le; Wang, Hui; Xie, Zhongping; Luo, Shihua; Zhou, Nai; Huang, Wenhai; Rahaman, Mohamed N

    2013-10-01

    Borate bioactive glass-based composites have been attracting interest recently as an osteoconductive carrier material for local antibiotic delivery. In the present study, composites composed of borate bioactive glass particles bonded with a chitosan matrix were prepared and evaluated in vitro as a carrier for gentamicin sulfate. The bioactivity, degradation, drug release profile, and compressive strength of the composite carrier system were studied as a function of immersion time in phosphate-buffered saline at 37 °C. The cytocompatibility of the gentamicin sulfate-loaded composite carrier was evaluated using assays of cell proliferation and alkaline phosphatase activity of osteogenic MC3T3-E1 cells. Sustained release of gentamicin sulfate occurred over ~28 days in PBS, while the bioactive glass converted continuously to hydroxyapatite. The compressive strength of the composite loaded with gentamicin sulfate decreased from the as-fabricated value of 24 ± 3 MPa to ~8 MPa after immersion for 14 days in PBS. Extracts of the soluble ionic products of the borate glass/chitosan composites enhanced the proliferation and alkaline phosphatase activity of MC3T3-E1 cells. These results indicate that the gentamicin sulfate-loaded composite composed of chitosan-bonded borate bioactive glass particles could be useful clinically as an osteoconductive carrier material for treating bone infection.

  5. Mechanism for converting Al2O3-containing borate glass to hydroxyapatite in aqueous phosphate solution.

    PubMed

    Zhao, Di; Huang, Wenhai; Rahaman, Mohamed N; Day, Delbert E; Wang, Deping

    2009-05-01

    The effect of replacing varying amounts (0-2.5 mol.%) of B2O3 with Al2O3 in a borate glass on (1) the conversion of the glass to HA in an aqueous phosphate solution and (2) the compressive strength of the as-formed HA product was investigated. Samples of each glass (10 x 10 x 8 mm) were placed in 0.25 M K2HPO4 solution at 60 degrees C, and the conversion kinetics to HA were determined from the weight loss of the glass and the pH of the solution. The structure and composition of the solid reaction products were characterized using X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. While the conversion rate of the glass to HA decreased considerably with increasing Al2O3 content, the microstructure of the HA product became denser and the compressive strength of the HA product increased. The addition of SiO2 to the Al2O3-containing borate glass reversed the deterioration of the conversion rate, and produced a further improvement in the strength of the HA product. The compressive strength of the HA formed from the borate glass with 2.5 mol.% Al2O3 and 5 mol.% SiO2 was 11.1 +/- 0.2 MPa, which is equal to the highest strengths reported for trabecular bone. The results indicated that simultaneous additions of Al2O3 and SiO2 could be used to control the bioactivity of the borate glass and to enhance the mechanical strength of the HA product. Furthermore, the HA product formed from the glass containing both SiO2 and Al2O3 could be applied to bone repair.

  6. Preparation and properties of porous microspheres made from borate glass.

    PubMed

    Conzone, Samuel D; Day, Delbert E

    2009-02-01

    Dysprosium lithium-borate glass microspheres and particles, ranging from 45 to 150 microm in diameter, were reacted with a 0.25 M phosphate solution at 37 degrees C, whose pH was either 3 or 8.8. The glass reacted nonuniformly and was converted into a porous, amorphous, hydrated, dysprosium phosphate reaction product. The amorphous product had the same volume and shape (pseudomorphic) as the unreacted glass, and could be dried without cracking. After heating at 300 degrees C for 1 h, the amorphous reaction product had a specific surface area of approximately 200 m(2)/g, a pore size of approximately 30 nm, and nominal crushing strength of approximately 10 MPa. When the reaction product was heated to 600 degrees C for 15 min, the specific surface area decreased to approximately 90 m(2)/g and the nominal crushing strength increased to 35 MPa. Heating above 615 degrees C converted the amorphous dysprosium phosphate product into crystalline DyPO(4), which contained open porosity until heated above 800 degrees C for 15 min. Highly porous materials of different chemical composition can be prepared by chemically reacting a borate-based glass with an aqueous solution at low-temperature (<100 degrees C). These highly porous materials are easy to process, and are considered candidates for controlled drug delivery, catalysis, chromatographic separation, filtration, and as bioactive materials.

  7. The preparation and characterization of a lithium borate glass prepared by the gel technique

    NASA Technical Reports Server (NTRS)

    Weinberg, M. C.; Neilson, G. F.; Smith, G. L.; Dunn, B.; Moore, G. S.; Mackenzie, J. D.

    1985-01-01

    The preparation of an amorphous lithium borate gel by the metal organic procedure is described. In addition, a preliminary evaluation of the behavior of the gel upon heating is given. In particular the crystallization tendency of the gel is studied with the aid of DTA and X-ray diffraction, and the structural changes in the gel are monitored with the aid of IR spectroscopy. The glass produced from the lithium borate gel is compared to both the gel precursor material and a glass of similar composition prepared by conventional techniques. Specifically, the relevant water contents, crystallization behavior, and structural features are contrasted.

  8. Preparation and characterization of magnesium borate for special glass

    NASA Astrophysics Data System (ADS)

    Dou, Lishuang; Zhong, Jianchu; Wang, Hongzhi

    2010-05-01

    Magnesium borate with a variety of B2O3/MgO molar ratios, which can be applied for special glass, has been prepared through the reaction of light-burned magnesia with boric acid by a hydrothermal method. The effects of the B2O3/MgO molar ratio of raw materials, reaction time, temperature and liquid to solid ratio (ml g-1) on the synthetic product are investigated. The XRD and TG-DTG analyses indicate that the prepared magnesium borate is a mixture of magnesium hexaborate hydrate and ascharite. The results show that high B2O3/MgO molar ratios of raw materials and low reaction liquid-solid ratios favour the product with a high B2O3/MgO molar ratio and vice versa. There exists free MgO in the product when the reaction temperature is below 140 °C or the reaction time is not enough, because of the incomplete reaction of magnesium oxide with boric acid. The process of fractional crystallization for the magnesium borate mixture is also discussed.

  9. Er-doped lead borate glasses and transparent glass ceramics for near-infrared luminescence and up-conversion applications.

    PubMed

    Pisarski, Wojciech A; Goryczka, Tomasz; Pisarska, Joanna; Ryba-Romanowski, Witold

    2007-03-15

    Lead borate based glasses have been analyzed using Raman and infrared spectroscopy. The formation of different borate groups and the direction of BO3 <--> BO4 conversion strongly depends on the PbO- and/or PbF2-to-B2O3 ratio in chemical composition. PbF2-PbO-B2O3 based glasses containing Er3+ ions have been studied after annealing. The orthorhombic PbF2 crystallites are formed during thermal treatment, which was evidenced by X-ray diffraction analysis. Near-infrared luminescence at 1530 nm and green up-conversion at 545 nm have been registered for samples before and after annealing. The luminescence bands correspond to 4I13/2-4I15/2 and 4S3/2-4I15/2 transitions of Er3+ ions, respectively. In comparison to the precursor glasses, the luminescence intensities are higher in the studied transparent oxyfluoride glass ceramics. Simultaneously, the half-width of the luminescence lines slightly decreases. It can be the evidence that a small amount of the Er3+ ions is incorporated into the orthorhombic PbF2 phase.

  10. Synthesis, structural characterization and scalable preparation of new amino-zinc borates

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Imer, M. R.; González, M.; Veiga, N.

    2017-01-01

    Zinc borates are important materials. We report the preparation of three novel ones: [Zn(NH 3) 3B 4O 5(OH) 4]·H 2O (ZB1), Zn 3(H 2B 3O 7) 2·2NH 3·4H 2O (ZB2), and [Zn(NH 3) 4][B 4O 5(OH) 4]·4H 2O (ZB3).

  11. Borates

    USGS Publications Warehouse

    Angulo, M.A.

    2011-01-01

    The article discusses the latest developments in the borates industry, particularly in the U.S., as of June 2011. It claims that the biggest economically feasible deposits of borates are seen in the U.S.' Mojave Desert, the Alpide belt in southern Asia and the Andean belt of South America. Turkish state-owned mining firm Eti Maden AS reported that borates were mainly used in the manufacture of glass, ceramics, fertilizer and detergent in 2009.

  12. Optical stability of 3d transition metal ions doped-cadmium borate glasses towards γ-rays interaction

    NASA Astrophysics Data System (ADS)

    Marzouk, M.; ElBatal, H.; Eisa, W.

    2016-07-01

    This work reports the preparation of glasses of binary cadmium borate with the basic composition (mol% 45 CdO 55 B2O3) and samples of the same composition containing 0.2 wt% dopants of 3d transition metal (TM) oxides (TiO2 → CuO). The glasses have been investigated by combined optical and Fourier Transform infrared spectroscopic measurements before and after being subjected to gamma irradiation with a dose of 8 Mrad (8 × 104 Gy). Optical absorption of the undoped glass before irradiation reveals strong charge transfer UV absorption which is related to the presence of unavoidable contaminated trace iron impurities (mainly Fe3+) within the raw materials used for the preparation of the base cadmium borate glass. The optical spectra of the 3d TM ions exhibit characteristic bands which are related the stable oxidation state of the 3d TM ions within the host glass. Gamma irradiation produces some limited variations in the optical spectra due to the stability of the host glass containing high percent 45 mol% of heavy metal oxide (CdO) which causes some shielding effects towards irradiation. From the absorption edge data, the values of the optical band gap Eopt and Urbach energy (ΔE) have been calculated. The values of the optical energy gap are found to be dependent on the glass composition. Infrared absorption spectral measurements reveal characteristic absorption bands due to both triangular and tetrahedral borate groups with the BO3 units vibrations more intense than BO4 units due to the known limit value for the change of BO3 to BO4 groups. The introduction of 3d TM ions with the doping level (0.2 wt%) causes no changes in the number or position of the IR bands because of the presence of TM ions in modifying sites in the glass network. It is observed that gamma irradiation causes some limited changes in the FT-IR spectral bands due to the stability of the host heavy cadmium borate glass.

  13. Infrared and Raman spectroscopic studies on alkali borate glasses: evidence of mixed alkali effect.

    PubMed

    Padmaja, G; Kistaiah, P

    2009-03-19

    A lithium-potassium-borate glass system containing manganese and iron cations has been thoroughly investigated in order to obtain information about the mixed alkali effect and the structural role of both the manganese and iron in such glass hosts. Mixed alkali borate glasses of the (30 - x)Li(2)O - xK(2)O - 10CdO/ZnO - 59B(2)O(3) (x = 0, 10, 15, 20, and 30) doped with 1MnO(2)/1Fe(2)O(3) system were prepared by a melt quench technique. The amorphous phase of the prepared glass samples was confirmed from their X-ray diffraction. The spectroscopic properties of glass samples were studied using infrared (IR) and Raman spectroscopic techniques. The density of all the prepared glasses was measured using Archimedes principle. Molar volumes were estimated from the density data. IR spectra of these glasses revealed a dramatic variation of three- and four-coordinated boron structures as a function of mixed alkali concentration. The vibrations due to Li-O, K-O, and MnO(4)/FeO(4) arrangements are consistent in all the compositions and show a nonlinear variation in the intensity with alkali content. Raman spectra of different alkali combinations with CdO and ZnO present drastic changes in the intensity of various Raman bands. The observation of disappearance and reappearance of IR and Raman bands as a function of various alkali concentrations is an important result pertaining to the mixed alkali effect in borate glasses. Acting as complementary spectroscopic techniques, both types of measurements, IR and Raman, revealed that the network structure of the studied glasses is mainly based on BO(3) and BO(4) units placed in different structural groups, the BO(3) units being dominant. The measured IR and Raman spectra of different glasses are used to clarify the optical properties of the present glasses correlating them with their structure and composition.

  14. Influence of tellurite on lifetime for samarium doped lanthanum lead borate glass

    NASA Astrophysics Data System (ADS)

    Madhu, A.; Eraiah, B.

    2018-04-01

    Samarium substituted tellurium lanthanum lead borate glass is prepared using melt quenching technique. Luminescence spectra have been recorded upon excitation with 402 nm various transitions from 4G5/2 level, for samarium doped tellurite glasses are studied and also lifetime for all the samples exhibit single exponential behaviour of decay curve. Luminescence spectra of present glasses show quenching effect due to cross-relation channels of samarium ions. The lifetime of glass samples decrease as the tellurite concentration is decreased. So, it evidences that to attain longer lifetime for lasing material one can tune the host by selecting concentration of tellurite.

  15. Thermoluminescence (TL) dosimeter of dysprosium doped strontium borate glass for different glass modifiers (Na, Li, Ca) subjected from 1 to 9 Gy doses

    NASA Astrophysics Data System (ADS)

    Hamzah, S. A.; Saeed, M. A.; Wagiran, H.; Hashim, I. H.

    2017-10-01

    This article reports TL response for different glass modifier and doping concentration. Alkali oxides (Na2O and Li2O) and alkali earth oxide (CaO) will be used as a glass modifier for strontium borate based glass. The samples were prepared by melt quenching technique. Dy2O3 concentrations ranging from 0.00 to 0.70 mol% and exposure doses of 1 to 9 Gy will be varied. All glass samples exhibit the prominent peak temperature positioned at 186 oC to 232 oC. From all the samples, one of the samples shows an excellent linearity dose response, higher TL and show good reproducibility after 5 cycles exposure which is sodium strontium borate doped with 0.1 mol% Dy2O3 (optimum concentration).

  16. A novel injectable borate bioactive glass cement for local delivery of vancomycin to cure osteomyelitis and regenerate bone.

    PubMed

    Cui, Xu; Zhao, Cunju; Gu, Yifei; Li, Le; Wang, Hui; Huang, Wenhai; Zhou, Nai; Wang, Deping; Zhu, Yi; Xu, Jun; Luo, Shihua; Zhang, Changqing; Rahaman, Mohamed N

    2014-03-01

    Osteomyelitis (bone infection) is often difficult to cure. The commonly-used treatment of surgical debridement to remove the infected bone combined with prolonged systemic and local antibiotic treatment has limitations. In the present study, an injectable borate bioactive glass cement was developed as a carrier for the antibiotic vancomycin, characterized in vitro, and evaluated for its capacity to cure osteomyelitis in a rabbit tibial model. The cement (initial setting time = 5.8 ± 0.6 min; compressive strength = 25.6 ± 0.3 MPa) released vancomycin over ~25 days in phosphate-buffered saline, during which time the borate glass converted to hydroxyapatite (HA). When implanted in rabbit tibial defects infected with methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis, the vancomycin-loaded cement converted to HA and supported new bone formation in the defects within 8 weeks. Osteomyelitis was cured in 87 % of the defects implanted with the vancomycin-loaded borate glass cement, compared to 71 % for the defects implanted with vancomycin-loaded calcium sulfate cement. The injectable borate bioactive glass cement developed in this study is a promising treatment for curing osteomyelitis and for regenerating bone in the defects following cure of the infection.

  17. Optical absorption of Er3+ doped lithium lead borate glasses

    NASA Astrophysics Data System (ADS)

    Usharani, V. L.; Eraiah, B.

    2018-05-01

    A new glass system Lithium lead borate doped with erbium trioxide were perpared using conventional melt quenching method. The amorphous nature of the glass samples were confirmed by XRD spectrum. The density of these glass were measured using Archmides principle, the values lie in the range from 4.27 to 4.76 g/cm-3. The corresponding molar volumes are calculated and the values are in the range of 23.81 to 26.17 cm-3. Absorption spectra were recorded in the wavelength range of 200nm to 1100nm, for the prepared glass samples. The optical direct and indirect energy band gaps were measured, the values are in the range of 2.875 to 3.254 eV and 2.25 to 2.81 eV respectively. Photoluminescence technique was employed to study the luminescent property of the prepared glasses excited at 380nm, emission spectra were recorded and analyzed.

  18. Electron magnetic resonance and magnetooptical studies of nanoparticle-containing borate glasses

    NASA Astrophysics Data System (ADS)

    Kliava, Janis; Edelman, Irina; Ivanova, Oxana; Ivantsov, Ruslan; Petrakovskaja, Eleonora; Hennet, Louis; Thiaudière, Dominique; Saboungi, Marie-Louise

    2011-03-01

    We report electron magnetic resonance (EMR) and magnetooptical studies of borate glasses of molar composition 22.5K 2O-22.5Al 2O 3-55B 2O 3 co-doped with low concentrations of Fe 2O 3 and MnO. In as-prepared samples the paramagnetic ions, as a rule, are in diluted state. However, in the case where the ratio of the iron and manganese oxides in the charge is 3/2, magnetic nanoparticles with characteristics close to those of manganese ferrite are formed already at the first stage of the glass preparation, as evidenced by both magnetic circular dichroism (MCD) and EMR. After thermal treatment all glasses show characteristic MCD and EMR spectra, attesting to the presence of magnetic nanoparticles, predominantly including iron ions. Preliminary EXAFS measurements at the Fe K-absorption edge show an emergence of nanoparticles with a structure close to MnFe 2O 4 after annealing the glasses at 560 °C. By computer simulating the EMR spectra at variable temperatures, a superparamagnetic nature of relatively broad size and shape distribution with the average diameter of ca. 3-4 nm. The characteristic temperature-dependent shift of the apparent resonance field is explained by a strong temperature dependence of the magnetic anisotropy in the nanoparticles. The formation of magnetic nanoparticles confers to the potassium-alumina-borate glasses magnetic and magneto-optical properties typical of magnetically ordered substances. At the same time, they remain transparent in a part of the visible and near infrared spectral range and display a high Faraday rotation value.

  19. Effect of ZnSe and CdSe nanoparticles on the fluorescence and optical band gap of Sm3+ doped lead borate glasses

    NASA Astrophysics Data System (ADS)

    Fatokun, Stephen O.

    For the first part of this work, we prepared a series of Sm-doped lead borate (PbO-B2O3) glasses containing zinc selenide (ZnSe) and cadmium selenide (CdSe) nanoparticles (NPs) and studied the Sm 3+ fluorescence by varying the glass composition and size of the NPs. We have chosen these heavy metal oxide glasses to incorporate Sm3+ ions because they have large glass forming region, high refractive index, and good physical and thermal stability. Lead borate glasses with the following compositions xPbO:(96.5-x)B2O 3:0.5Sm2O3:3ZnSe/CdSe, x=36.5 and 56.5 mol%) are prepared using the melt-quenching method. Transmission electron microscopy characterization was done to confirm both nucleation and growth of the NPs for different annealing times. Fluorescence spectra of these samples are obtained with the excitation wavelengths at 403 and 477nm. Three fluorescence transitions are observed at 563 nm, 598 nm and 646 nm. The transition at 646 nm is a electric dipole (ED) transition that strongly depends on the covalency of the Sm-O bond and the asymmetry of the crystal field at the Sm3+ site. The 646 nm/598 nm fluorescence intensity ratio has been studied for different annealing times and PbO concentration for both ZnSe and CdSe samples. Longer annealing times tend to make the crystal field at the Sm3+ site more symmetric in nature for these glasses. The presence of CdSe NPs is seen to produce the greatest influence on the fluorescence intensity ratio. This is believed to be due to the larger size of the CdSe nanoparticles and its stronger influence on Sm3+ ions. The second part of this work was dedicated to the understanding of the optical band gap of samarium doped lead borate glasses with and without ZnSe/CdSe NPs. Optical absorption spectra for all these glass samples show their absorption edge in the ultraviolet region. Detailed analysis of the absorption edge was carried out using the Mott-Davis model and the optical band gap and the width of the tail in the band gap

  20. Synthesis and structural studies of praseodymium doped silver borate glasses

    NASA Astrophysics Data System (ADS)

    Jagadeesha Gowda, G. V.; Eraiah, B.

    2013-02-01

    Praseodymium doped silver borate glasses with nominal composition xPr6O11-(25-x)Ag2O-75B2O3 (x=0, 1, 2, 3, 4, 5) were prepared by melt quench technique. XRD pattern shows that there is no sharp peak it confirms the amorphous nature of the present glasses. The glass transition temperature (Tg) of this glass system have been studied using the Matac MBS-8000 Digital Signal Processing and Conventional Thermal Analysis (DTA) method. The Tg of these glasses increases with increase in concentration of Pr6O11 except at 0.2 mol%, Tg value is lower. 11B MAS-NMR shows the presence of sharp peak around 0.306 ppm. Chemical shift of these glasses decreases with mol% of rare earth oxide. FTIR spectra recorded in the region of 400 to 4000 cm-1. This studies revealed that the progressive addition Ag2O and Pr6O11 leads to modification of B2O3 into BO4 groups. Raman measurements of these glasses support the proposed interpretations of the experimental results.

  1. Titanium addition influences antibacterial activity of bioactive glass coatings on metallic implants.

    PubMed

    Rodriguez, Omar; Stone, Wendy; Schemitsch, Emil H; Zalzal, Paul; Waldman, Stephen; Papini, Marcello; Towler, Mark R

    2017-10-01

    In an attempt to combat the possibility of bacterial infection and insufficient bone growth around metallic, surgical implants, bioactive glasses may be employed as coatings. In this work, silica-based and borate-based glass series were synthesized for this purpose and subsequently characterized in terms of antibacterial behavior, solubility and cytotoxicity. Borate-based glasses were found to exhibit significantly superior antibacterial properties and increased solubility compared to their silica-based counterparts, with BRT0 and BRT3 (borate-based glasses with 0 and 15 mol% of titanium dioxide incorporated, respectively) outperforming the remainder of the glasses, both borate and silicate based, in these respects. Atomic Absorption Spectroscopy confirmed the release of zinc ions (Zn 2+ ), which has been linked to the antibacterial abilities of glasses SRT0, BRT0 and BRT3, with inhibition effectively achieved at concentrations lower than 0.7 ppm. In vitro cytotoxicity studies using MC3T3-E1 osteoblasts confirmed that cell proliferation was affected by all glasses in this study, with decreased proliferation attributed to a faster release of sodium ions over calcium ions in both glass series, factor known to slow cell proliferation in vitro .

  2. Production and characterization of hydrophobic zinc borate by using palm oil

    NASA Astrophysics Data System (ADS)

    Acarali, Nil Baran; Tugrul, Nurcan; Derun, Emek Moroydor; Piskin, Sabriye

    2013-11-01

    Zinc borate (ZB) was synthesized using zinc oxide, boric acid synthesized from colemanite, and reference ZB as seed. The effects of reaction parameters such as reaction time, reactant ratio, and seed ratio on its yield were examined. Then, the effects of palm oil with solvents (isopropyl alcohol (IPA), ethanol, and methanol) added to the reaction on its hydrophobicity were explored. Reactions were carried out under determined reaction conditions with magnetically and mechanically stirred systems. The produced ZB was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and measurements of contact angle identified hydrophobicity. The results showed that hydrophobic ZB was successfully produced under determined reaction conditions. The change of process parameters influenced its yield and the usage of palm oil provided hydrophobicity.

  3. Effect of silver nanoparticles on the fluorescence of Pb2+ and compositional dependence of Sm3+ fluorescence in borate glasses

    NASA Astrophysics Data System (ADS)

    Olumoroti, Akinloluwa T.

    Borate glasses have been widely studied due to their good optical and mechanical properties. Lead and bismuth (PbO/Bi2O 3:B2O3) borate glasses belong to a family of heavy metal oxide (HMO) glasses which are well known to be chemically durable, stable against atmospheric moisture, have low melting temperatures and good corrosion resistance. The first part of this work deals with lead borate glasses with silver nanoparticles (NPs) introduced into the glass matrix. Transmission electron microscopy characterization is done to verify the nucleation of NPs. Fluorescence and optical absorption experiments are then carried out after different heat treatment duration to investigate the influence of silver NPs on the optical properties of lead (Pb2+) by comparing with a glass sample without silver NPs. Optical absorption experiments show that a well-defined surface plasmon resonance (SPR) peak due to Ag NPs can be observed only for samples that were annealed for 36 hrs. Pb2+ fluorescence spectra reveal that the presence of silver NPs creates new emission centers for Pb2+ ions by altering their chemical environment. The second part of the work involves the use of samarium (a rare earth ion) as a dopant in lead and bismuth borate glasses. The concentration of samarium (Sm3+) is fixed and the base glass composition is varied. The goal is to investigate the compositional dependence of optical properties of samarium in the base glass (PbO/Bi2O3:B 2O3). Optical absorption spectra have been collected and the oscillator strength of each transition - including the hypersensitive - is obtained. The Optical absorption edge is found to shift toward lower energies with increasing PbO/Bi2O3 concentration. Both the oscillator strength and the peak position of the hypersensitive transition show significant variation with glass composition. Strong interaction between Sm3+ ions and Pb2+/Bi3+ ions can also be seen from the variations in the fluorescence emission properties of Sm3+ as a

  4. Compositional dependence of optical band gap and refractive index in lead and bismuth borate glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mallur, Saisudha B.; Czarnecki, Tyler; Adhikari, Ashish

    2015-08-15

    Highlights: • Refractive indices increase with increasing PbO/Bi{sub 2}O{sub 3} content. • Optical band gap arises due to direct forbidden transition. • Optical band gaps decrease with increasing PbO/Bi{sub 2}O{sub 3} content. • New empirical relation between the optical band gap and the refractive index. - Abstract: We prepared a series of lead and bismuth borate glasses by varying PbO/Bi{sub 2}O{sub 3} content and studied refractive index and optical band gap as a function of glass composition. Refractive indices were measured very accurately using a Brewster’s angle set up while the optical band gaps were determined by analyzing the opticalmore » absorption edge using the Mott–Davis model. Using the Lorentz–Lorentz method and the effective medium theory, we calculated the refractive indices and then compared them with the measured values. Bismuth borate glasses show better agreement between the calculated values of the refractive index and experimental values. We used a differential method based on Mott–Davis model to obtain the type of transition and optical band gap (E{sub opt}) which in turn was compared with the value of E{sub opt} obtained using the extinction coefficient. Our analysis shows that in both lead and bismuth borate glasses, the optical band gap arises due to direct forbidden transition. With increasing PbO/Bi{sub 2}O{sub 3} content, the absorption edge shifts toward longer wavelengths and the optical band gap decreases. This behavior can be explained in terms of changes to the Pb−O/Bi−O chemical bonds with glass composition. We obtained a new empirical relation between the optical band gap and the refractive index which can be used to accurately determine the electronic oxide polarizability in lead and bismuth oxide glasses.« less

  5. Effects of Chemically Doped Bioactive Borate Glass on Neuron Regrowth and Regeneration.

    PubMed

    Gupta, Brinda; Papke, Jason B; Mohammadkhah, Ali; Day, Delbert E; Harkins, Amy B

    2016-12-01

    Peripheral nerve injuries present challenges to regeneration. Currently, the gold standard for nerve repair is an autograft that results in another region of the body suffering nerve damage. Previously, bioactive borate glass (BBG) has been studied in clinical trials to treat patients with non-healing wounds, and we have reported that BBG is conducive for soft tissue repair. BBG provides structural support, degrades in a non-cytotoxic manner, and can be chemically doped. Here, we tested a wide range of chemical compounds that are reported to have neuroprotective characteristics to promote regeneration of peripheral neurons after traumatic injury. We hypothesized that chemical dopants added in trace amounts to BBG would improve neuronal survival and neurite outgrowth from dorsal root ganglion (DRG) explants. We measured neurite outgrowth from whole DRG explants, and survival rates of dissociated neurons and support cells that comprise the DRG. Results show that chemically doped BBGs have differentially variable effects on neuronal survival and outgrowth, with iron, gallium, and zinc improving outgrowth of neurons, and iodine causing the most detriment to neurons. Because chemically doped BBGs support increased nerve regrowth and survival, they show promise for use in peripheral nerve regeneration.

  6. Structural influence of mixed transition metal ions on lithium bismuth borate glasses

    NASA Astrophysics Data System (ADS)

    Yadav, Arti; Dahiya, Manjeet S.; Hooda, A.; Chand, Prem; Khasa, S.

    2017-08-01

    Lithium bismuth borate glasses containing mixed transition metals having composition 7CoO·23Li2O·20Bi2O3·50B2O3 (CLBB), 7V2O5·23Li2O·20Bi2O3·50B2O3 (VLBB) and x(2CoO·V2O5)·(30 - x)Li2O·20Bi2O3·50B2O3 (x = 0.0 (LBB) and x = 2.0, 5.0, 7.0, 10.0 mol% (CVLBB1-4)) are synthesized via melt quench route. The synthesized compositions are investigated for their physical properties using density (D) and molar volume (Vm), thermal properties by analyzing DSC/TG thermo-graphs, structural properties using IR absorption spectra in the mid-IR range and optical properties using UV-Vis-NIR spectroscopy. The Electron Paramagnetic Resonance (EPR) spectra of vanadyl and cobalt ion have been analyzed to study compositional effects on spin-Hamiltonian parameters. The non linear variations in physical properties depict a strong structural influence of Co/V- oxides on the glassy matrix. The compositional variations in characteristic temperatures (glass transition temperature Tg, glass crystallization temperature Tp and glass melting temperature Tm) reveals that Tg for glass samples CLBB is relatively less than that of pure lithium bismuth borate (LBB) glass sample wherein Tg for sample VLBB is higher than that of LBB. The increase in Tg (as compared with LBB) with an enhanced substitution of mixed transition metal oxides (2CoO·V2O5) shows a progressive structure modification of bismuth borate matrix. These predictions are very well corroborated by corresponding compositional trends of Tp and Tm. FTIR studies reveal that Co2+& VO2+ ions lead to structural rearrangements through the conversion of three-coordinated boron into four coordinated boron and thereby reducing number of non-bridging oxygen atoms. Bismuth is found to exist in [BiO6] octahedral units only, whereas boroxol rings are not present in the glass network. The theoretical values of optical basicity (Λth) and corresponding oxide ion polarizability (αo2-) have also been calculated to investigate oxygen covalency of

  7. Structural and optical properties of antimony-germanate-borate glass and glass fiber co-doped Eu3+ and Ag nanoparticles.

    PubMed

    Zmojda, Jacek; Kochanowicz, Marcin; Miluski, Piotr; Baranowska, Agata; Pisarski, Wojciech A; Pisarska, Joanna; Jadach, Renata; Sitarz, Maciej; Dorosz, Dominik

    2018-08-05

    In the paper analysis of structural and luminescent properties of antimony-germanate-borate glasses and glass fiber co-doped with 0.6AgNO 3 /0.2Eu 2 O 3 are presented. Heat treatment of the fabricated glass and optical fiber (400 °C, 12 h) enabled to obtain Ag nanoparticles (NPs) with average size 30-50 nm on their surface. It has been proofed that silver ions migrate to the glass surface, where they are reduced to Ag 0 nanoparticles. Simultaneously, FTIR analysis showed that heat treatment of the glass and optical fiber increases the local symmetry of the Eu 3+ site. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Thermoluminescent properties of Dy doped calcium borate based glass for dose measurement subjected to photon irradiation

    NASA Astrophysics Data System (ADS)

    Tajuddin, H. A.; WanHassan, W. M. S.; Abdul Sani, S. F..; Shaharin, Nurul Syazlin

    2017-10-01

    This study presents the thermoluminescent (TL) dosimetric properties of calcium borate glass with various dopant concentration of dysprosium (Dy). Calcium borate glass is a new potential material to be used in radiation measurement with absorption coefficient that is close to human bone. A series of glasses based on chemical equation xCaO-(100-x) B2O3 system, x = 0.1, 0.2, 0.3, 0.4, 0.5 (0< x <100) % weight have been prepared by melt quenching method. The X-ray diffraction analysis of glass samples were carried out and the result showed a broad peak, which confirmed the amorphous nature of the glass. The 70B2O3-30CaO glass sample was found as the most stable among other glass samples studied. Present work focuses on 70B2O3-30CaO glass of (0.01-0.4) mol% Dy-doped in order to investigate the thermoluminescence (TL) properties, in particular, dose-response and fading. The glass samples were irradiated to dose range of 0.5-4.0 Gy subjected to 6MV photon irradiations of LINAC Primus MLC 3339. TL response of 0.3 mol% Dy-doped 70B2O3-30CaO glass was found to produce highest response, with good linear dose- response relationship.

  9. Spectroscopic investigations on Pr3+ ions doped lead telluro-borate glasses for photonic applications

    NASA Astrophysics Data System (ADS)

    Suthanthirakumar, P.; Mariyappan, M.; Marimuthu, K.

    2018-04-01

    A new series of Lead telluro-borate glasses doped with different concentrations of Pr3+ ions (xPLTB) were prepared by melt quenching technique and their structural and spectroscopic properties were investigated by recording XRD, FTIR, optical absorption and luminescence spectral measurements. XRD measurements confirm the amorphous nature and the FTIR spectra reveal the presence of different vibrational modes of borate and tellurite networks in the prepared glasses. The bonding parameter values (δ) obtained from the absorption band positions indicates that the bonding between Pr3+ ions and their surrounding ligands is of ionic in nature. The optical band gap (Eopt) corresponding to the direct and indirect allowed transitions were determined with the framework of tauc's plot. From the luminescence spectra, important radiative parameters such as stimulated emission cross-section (σPE) , branching ratios (βR) and radiative lifetime (τR) were calculated for the dominant emission transition 3P0→3H4 (blue) in order to suggest the suitability of the studied glasses for suitable photonic applications.

  10. Optical and FT Infrared spectral studies of vanadium ions in cadmium borate glass and effects of gamma irradiation

    NASA Astrophysics Data System (ADS)

    AbdelAziz, T. D.; EzzElDin, F. M.; El Batal, H. A.; Abdelghany, A. M.

    2014-10-01

    Combined optical and infrared absorption spectra of V2O5-doped cadmium borate glasses were investigated before and after gamma irradiation with a dose of 8 Mrad (=8 × 104 Gy). The undoped base cadmium borate glass reveals a spectrum consisting of strong charge transfer UV absorption bands which are related to the presence of unavoidable contaminated trace iron impurities (mainly Fe3+). The V2O5-doped glasses reveal an extra band at 380 nm and the high V2O5-content glass also shows a further band at about 420 nm. The observed optical spectrum indicates the presence of vanadium ions mainly in the pentavalent state (d0 configuration). The surplus band at 420 nm shows that some trivalent vanadium ions are identified at high V2O5 content. The optical spectra of the glasses after gamma irradiation show small decrease of the intensity of the UV absorption which are interpreted by assuming the transformation of some Fe3+ ions by photochemical reactions with the presence of high content (45 mol%) of heavy massive CdO causing some shielding behavior. FT infrared absorption spectra of the glasses show vibrational bands due to collective presence of triangular and tetrahedral borate groups in their specific wavenumbers. The FTIR spectra are observed to be slightly affected by both the V2O5-dopants being present in modifying low percent or gamma irradiation due to the presence of high content heavy CdO.

  11. Effect of 3d-transition metal doping on the shielding behavior of barium borate glasses: a spectroscopic study.

    PubMed

    ElBatal, H A; Abdelghany, A M; Ghoneim, N A; ElBatal, F H

    2014-12-10

    UV-visible and FT infrared spectra were measured for prepared samples before and after gamma irradiation. Base undoped barium borate glass of the basic composition (BaO 40%-B2O3 60mol.%) reveals strong charge transfer UV absorption bands which are related to unavoidable trace iron impurities (Fe(3+)) within the chemical raw materials. 3d transition metal (TM)-doped glasses exhibit extra characteristic absorption bands due to each TM in its specific valence or coordinate state. The optical spectra show that TM ions favor generally the presence in the high valence or tetrahedral coordination state in barium borate host glass. Infrared absorption bands of all prepared glasses reveal the appearance of both triangular BO3 units and tetrahedral BO4 units within their characteristic vibrational modes and the TM-ions cause minor effects because of the low doping level introduced (0.2%). Gamma irradiation of the undoped barium borate glass increases the intensity of the UV absorption together with the generation of an induced broad visible band at about 580nm. These changes are correlated with suggested photochemical reactions of trace iron impurities together with the generation of positive hole center (BHC or OHC) within the visible region through generated electrons and positive holes during the irradiation process. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Evaluation of gamma-ray attenuation properties of bismuth borate glass systems using Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Tarim, Urkiye Akar; Ozmutlu, Emin N.; Yalcin, Sezai; Gundogdu, Ozcan; Bradley, D. A.; Gurler, Orhan

    2017-11-01

    A Monte Carlo method was developed to investigate radiation shielding properties of bismuth borate glass. The mass attenuation coefficients and half-value layer parameters were determined for different fractional amounts of Bi2O3 in the glass samples for the 356, 662, 1173 and 1332 keV photon energies. A comparison of the theoretical and experimental attenuation coefficients is presented.

  13. Lasing transition at 1.06 μm emission in Nd3+ -doped borate-based tellurium calcium zinc niobium oxide glasses for high-power solid-state lasers.

    PubMed

    Ravi, O; Prasad, K; Jain, Rajiv; Venkataswamy, M; Chaurasia, Shivanand; Deva Prasad Raju, B

    2017-08-01

    The spectroscopic properties of Tellurium Calcium Zinc Niobium oxide Borate (TCZNB) glasses of composition (in mol%) 10TeO 2  + 15CaO + 5ZnO + 10 Nb 2 O 5  + (60 - x)B 2 O 3  + Nd 2 O 3 (x = 0.1, 0.5, 1.0 or 1.5 mol%) have been investigated experimentally. The three phenomenological intensity parameters Ω 2 , Ω 4, Ω 6 have been calculated using the Judd-Ofelt theory and in turn radiative properties such as radiative transition probabilities, emission cross-sections, branching ratios and radiative lifetimes have been estimated. The trend found in the JO intensity parameter is Ω 2  > Ω 6  > Ω 4 If Ω 6  > Ω 4 , the glass system is favourable for the laser emission 4 F 3 /2  →  4 I 11 /2 in the infrared (IR) wavelength. The experimental values of branching ratio of 4 F 3 /2  →  4 I 11 /2 transition indicate favourable lasing action with low threshold power. The evaluated total radiative transition probabilities (A T ), stimulated emission cross-section (σ e ) and gain bandwidth parameters (σ e  × Δλ p ) were compared with earlier reports. An energy level analysis has been carried out considering the experimental energy positions of the absorption and emission bands. Copyright © 2016 John Wiley & Sons, Ltd.

  14. Treatment of osteomyelitis and repair of bone defect by degradable bioactive borate glass releasing vancomycin.

    PubMed

    Xie, Zongping; Liu, Xin; Jia, Weitao; Zhang, Changqing; Huang, Wenhai; Wang, Jianqiang

    2009-10-15

    The effectiveness of a degradable and bioactive borate glass has been compared with the clinically used calcium sulfate in the treatment of osteomyelitis of rabbits, as a carrier for vancomycin. The bone infections were induced in the tibias of 65 rabbits by injecting methicillin-resistant Staphylococcus aureus (MRSA). After 3 weeks, these rabbits were distributed into 4 groups and treated by debridement. Pure borate glass (BG), vancomycin-loaded calcium sulfate (VCS) and vancomycin-loaded borate glass (VBG) were implanted into the infection sites of groups 2 to 4 respectively. After 8 weeks, the effectiveness of treatment was assessed radiographically, bacteriologically, and histopathologically. The results showed that the negative rates of MRSA examination for rabbits were 36.36%, 18.18%, 73.33% and 81.25% respectively for groups 1 to 4. Significant differences were observed radiographically, bacteriologically, and histopathologically between groups 1 and 4, groups 2 and 3, and between groups 2 and 4. The best result of treatment was observed in group 4. Radiographically, VBG was found to be mostly reabsorbed and replaced by lots of new bones, whereas, VCS was completely reabsorbed and replaced by modest new bones. Histopathologically, there were lots of newly formed bones around VBG without any foreign body response, and only modest new bones around VCS with obvious foreign body response. VBG proved to have excellent biocompatibility and to be very effective in eradicating osteomyelitis and simultaneously stimulating bone regeneration, avoiding the disadvantages of VCS.

  15. Conversion of borate-based glass scaffold to hydroxyapatite in a dilute phosphate solution.

    PubMed

    Liu, Xin; Pan, Haobo; Fu, Hailuo; Fu, Qiang; Rahaman, Mohamed N; Huang, Wenhai

    2010-02-01

    Porous scaffolds of a borate-based glass (composition in mol%: 6Na2O, 8K2O, 8MgO, 22CaO, 36B2O3, 18SiO2, 2P2O5), with interconnected porosity of approximately 70% and pores of size 200-500 microm, were prepared by a polymer foam replication technique. The degradation of the scaffolds and conversion to a hydroxyapatite-type material in a 0.02 M K2HPO4 solution (starting pH = 7.0) at 37 degrees C were studied by measuring the weight loss of the scaffolds, as well as the pH and the boron concentration of the solution. X-ray diffraction, scanning electronic microscopy and energy dispersive x-ray analysis showed that a hydroxyapatite-type material was formed on the glass surface within 7 days of immersion in the phosphate solution. Cellular response to the scaffolds was assessed using murine MLO-A5 cells, an osteogenic cell line. Scanning electron microscopy showed that the scaffolds supported cell attachment and proliferation during the 6 day incubation. The results indicate that this borate-based glass could provide a promising degradable scaffold material for bone tissue engineering applications.

  16. Optical and FT Infrared spectral studies of vanadium ions in cadmium borate glass and effects of gamma irradiation.

    PubMed

    AbdelAziz, T D; EzzElDin, F M; El Batal, H A; Abdelghany, A M

    2014-10-15

    Combined optical and infrared absorption spectra of V2O5-doped cadmium borate glasses were investigated before and after gamma irradiation with a dose of 8 Mrad (=8×10(4) Gy). The undoped base cadmium borate glass reveals a spectrum consisting of strong charge transfer UV absorption bands which are related to the presence of unavoidable contaminated trace iron impurities (mainly Fe(3+)). The V2O5-doped glasses reveal an extra band at 380nm and the high V2O5-content glass also shows a further band at about 420nm. The observed optical spectrum indicates the presence of vanadium ions mainly in the pentavalent state (d(0) configuration). The surplus band at 420nm shows that some trivalent vanadium ions are identified at high V2O5 content. The optical spectra of the glasses after gamma irradiation show small decrease of the intensity of the UV absorption which are interpreted by assuming the transformation of some Fe(3+) ions by photochemical reactions with the presence of high content (45mol%) of heavy massive CdO causing some shielding behavior. FT infrared absorption spectra of the glasses show vibrational bands due to collective presence of triangular and tetrahedral borate groups in their specific wavenumbers. The FTIR spectra are observed to be slightly affected by both the V2O5-dopants being present in modifying low percent or gamma irradiation due to the presence of high content heavy CdO. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

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

    PubMed

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

    2016-01-05

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

  19. Role of oxygen on the optical properties of borate glass doped with ZnO

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Abdel-Baki, Manal; El-Diasty, Fouad, E-mail: fdiasty@yahoo.com

    2011-10-15

    Lithium tungsten borate glass (0.56-x)B{sub 2}O{sub 3}-0.4Li{sub 2}O-xZnO-0.04WO{sub 3} (0{<=}x{<=}0.1 mol%) is prepared by the melt quenching technique for photonic applications. Small relative values of ZnO are used to improve the glass optical dispersion and to probe as well the role of oxygen electronic polarizability on its optical characteristics. The spectroscopic properties of the glass are determined in a wide spectrum range (200-2500 nm) using a Fresnel-based spectrophotometric technique. Based on the Lorentz-Lorenz theory, as ZnO content increases on the expense of B{sub 2}O{sub 3} the glass molar polarizability increased due to an enhanced unshared oxide ion 2p electron density,more » which increases ionicity of the chemical bonds of glass. The role of oxide ion polarizability is explained in accordance with advanced measures and theories such as optical basicity, O 1s binding energy, the outer most cation binding energy in Yamashita-Kurosawa's interionic interaction parameter and Sun's average single bond strength. FT-IR measurements confirm an increase in bridging oxygen bonds, as a result of replacement of ZnO by B{sub 2}O{sub 3}, which increase the UV glass transmission window and transmittance. - Graphical abstract: O1s, Yamashita-Kurosawa's parameter and average single bond strength of charge overlapping between electronic shells are used to explain enhanced oxide ion 2p electron density, which increases refractive index of glasses. Highlights: > New borate glass for photonic application is prepared. > The dispersion property of the glass is effectively controlled using small amounts of ZnO. > ZnO is used to probe the glass structure and investigate the role of oxygen on the obtained optical properties of the glasses. > Modern theories are used to explain enhanced unshared oxide ion 2p electron density, which increases ionicity of chemical bonds of the glass.« less

  20. Large Faraday effect of borate glasses with high Tb3+ content prepared by containerless processing

    NASA Astrophysics Data System (ADS)

    Suzuki, Futoshi; Sato, Fumio; Oshita, Hiroyuki; Yao, Situ; Nakatsuka, Yuko; Tanaka, Katsuhisa

    2018-02-01

    Borate glasses containing a large amount of Tb3+ ions have been prepared by containerless processing. The content of Tb2O3 reached 60 mol%. The glass bearing the highest content of Tb3+ ions showed a large Faraday effect; the Verdet constant was 234 rad/T m. Annealing of the glasses in H2/N2 atmosphere resulted in a low optical absorption coefficient, leading to an extremely large magneto-optical figure of merit that was ∼1.7 times higher than that of Tb3Ga5O12 single crystal.

  1. Effect of RE (Nd3+, Sm3+) oxide on structural, optical properties of Na2O-Li2O-ZnO-B2O3 glass system

    NASA Astrophysics Data System (ADS)

    Hivrekar, Mahesh M.; Bhoyar, D. N.; Mande, V. K.; Dhole, V. V.; Solunke, M. B.; Jadhav, K. M.

    2018-05-01

    Zinc borate glass activated with rare earth oxide (Nd2O3, Sm2O3) of Na2O-Li2O-ZnO-B2O3 quaternary system has been prepared successfully by melt quenching method. The nucleation and growth of RE oxide were controlled temperature range 950-1000° C and rapid cooling at room temperature. The physical, structural and optical properties were characterized by using X-ray diffraction (XRD), SEM, Ultraviolet-visible spectroscopy (UV-Vis). XRD and SEM studies confirmed the amorphous nature, surface morphology of prepared zinc borate glass. The physical parameters like density, molar volume, molar mass of Nd3+, Sm3+ doped borate glass are summarized in the present article. The optical absorption spectra along with tauc's plot are presented. The optical energy band gap increases due to the addition of rare earth oxide confirming the role of network modifier.

  2. A mechanistic study of the interaction of water-soluble borate glass with apatite-bound heterocyclic nitrogen-containing bisphosphonates.

    PubMed

    Pramanik, Chandrani; Sood, Parveen; Niu, Li-Na; Yuan, He; Ghoshal, Sushanta; Henderson, Walter; Liu, Yaodong; Jang, Seung Soon; Kumar, Satish; Pashley, David H; Tay, Franklin R

    2016-02-01

    Long-term oral and intravenous use of nitrogen-containing bisphosphonates (N-BPs) is associated with osteonecrosis of the jaw. Although N-BPs bind strongly to bone surfaces via non-covalent bonds, it is possible for extrinsic ions to dissociate bound N-BPs from mineralized bone by competitive desorption. Here, we investigate the effects and mechanism of using an ionic cocktail derived from borate bioactive glass for sequestration of heterocyclic N-BPs bound to apatite. By employing solid-state and solution-state analytical techniques, we confirmed that sequestration of N-BPs from bisphosphonate-bound apatite occurs in the presence of the borate-containing ionic cocktail. Simulations by density functional theory computations indicate that magnesium cation and borate anion are well within the extent of the risedronate or zoledronate anion to form precipitate complexes. The sequestration mechanism is due to the borate anion competing with bisphosphonates for similar electron-deficient sites on the apatite surface for binding. Thus, application of the borate-containing ionic cocktail represents a new topical lavage approach for removing apatite-bound heterocyclic N-BPs from exposed necrotic bone in bisphosphonate-related osteonecrosis of the jaw. Long-term oral consumption and injections of nitrogen-containing bisphosphonates (N-BPs) may result in death of the jaw bone when there is traumatic injury to the bone tissues. To date, there is no effective treatment for such a condition. This work reported the use of an ionic cocktail derived from water-soluble borate glass microfibers to displace the most potent type of N-BPs that are bound strongly to the mineral component on bone surfaces. The mechanism responsible for such an effect has been identified to be cation-mediated complexation of borate anions with negatively-charged N-BPs, allowing them to be released from the mineral surface. This borate-containing cocktail may be developed into a novel topical rinse for

  3. A study of physical and optical absorption spectra of VO2+ ions in potassium and sodium oxide borate glasses

    NASA Astrophysics Data System (ADS)

    Srinivas, G.; Ramesh, B.; Kumar, J. Siva; Shareefuddin, Md.; Chary, M. N.; Sayanna, R.

    2016-05-01

    Spectroscopic and physical properties of V2O5 doped mixed alkali borate glasses are investigated. Borate glasses containing fixed concentrations of alkaline earth oxides (MgO and BaO) and alkali oxides (K2O and Na2O) were changes and are prepared by melt quenching technique. The values of ri, rp, Rm, αm molar volume and Λth increase and oxygen packing density, density and dopant ion concentration decrease with increasing of K2O content. As a result there shall be an increase in the disorder of the glass network. The optical band gap energies, Urbach energy, boron-boron separation,refractive index, dielectric constant, electronic polarizability and reflection loss values are varies nonlinearly with the K2O content which manifests the mixed alkali effect.

  4. Spectroscopic and nonlinear optical studies of pure and Nd-doped lanthanum strontium borate glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Harde, G. B.; Department of Physics, Sant Gadge Baba Amravati University, Amravati, Maharashtra, India-444602; Muley, G. G., E-mail: gajananggm@yahoo.co.in

    2016-05-06

    Borate glasses of the system xNd{sub 2}O{sub 3}-(1-x) La{sub 2}O{sub 3}-SrCO{sub 3}-10H{sub 3}BO{sub 3} (with x = 0 and 0.05) were prepared by using a convectional melt quenching technique. The amorphous nature of the quenched glasses has been confirmed by powder X-ray diffraction analysis. In order to study the spectroscopic and nonlinear optical properties of fabricated glasses, ultraviolet-visible transmission spectroscopy and open aperture z-scan measurements have been employed. In Nd doped glasses, the transition {sup 4}I{sub 9/2} → {sup 4}G{sub 5/2} + {sup 2}G{sub 7/2} has found more prominent than the other transitions. Optical band gap energies of glasses havemore » been determined and found less for Nd doped glass.« less

  5. Broad-spectrum antibacterial properties of metal-ion doped borate bioactive glasses for clinical applications

    NASA Astrophysics Data System (ADS)

    Ottomeyer, Megan

    Bioactive glasses with antimicrobial properties can be implemented as coatings on medical devices and implants, as well as a treatment for tissue repair and prevention of common hospital-acquired infections such as MRSA. A borate-containing glass, B3, is also undergoing clinical trials to assess wound-healing properties. The sensitivities of various bacteria to B3, B3-Ag, B3-Ga, and B3-I bioactive glasses were tested. In addition, the mechanism of action for the glasses was studied by spectroscopic enzyme kinetics experiments, Live-Dead staining fluorescence microscopy, and luminescence assays using two gene fusion strains of Escherichia coli. It was found that gram-positive bacteria were more sensitive to all four glasses than gram negative bacteria, and that a single mechanism of action for the glasses is unlikely, as the rates of catalysis for metabolic enzymes as well as membrane permeability were altered after glass exposure.

  6. Kinetics and mechanisms of the conversion of silicate (45S5), borate, and borosilicate glasses to hydroxyapatite in dilute phosphate solutions.

    PubMed

    Huang, Wenhai; Day, Delbert E; Kittiratanapiboon, Kanisa; Rahaman, Mohamed N

    2006-07-01

    Bioactive glasses with controllable conversion rates to hydroxyapatite (HA) may provide a novel class of scaffold materials for bone tissue engineering. The objective of the present work was to comprehensively characterize the conversion of a silicate bioactive glass (45S5), a borate glass, and two intermediate borosilicate glass compositions to HA in a dilute phosphate solution at 37 degrees Celsius. The borate glass and the borosilicate glasses were derived from the 45S5 glass by fully or partially replacing the SiO(2) with B(2)O(3). Higher B(2)O(3) content produced a more rapid conversion of the glass to HA and a lower pH value of the phosphate solution. Whereas the borate glass was fully converted to HA in less than 4 days, the silicate (45S5) and borosilicate compositions were only partially converted even after 70 days, and contained residual SiO(2) in a Na-depleted core. The concentration of Na(+) in the phosphate solution increased with reaction time whereas the PO(4) (3-) concentration decreased, both reaching final limiting values at a rate that increased with the B(2)O(3) content of the glass. However, the Ca(2+) concentration in the solution remained low, below the detection limit of atomic absorption, throughout the reaction. Immersion of the glasses in a mixed solution of K(2)HPO(4) and K(2)CO(3) produced a carbonate-substituted HA but the presence of the K(2)CO(3) had little effect on the kinetics of conversion to HA. The kinetics and mechanisms of the conversion process of the four glasses to HA are compared and used to develop a model for the process.

  7. Thermoluminescence glow curve deconvolution and trapping parameters determination of dysprosium doped magnesium borate glass

    NASA Astrophysics Data System (ADS)

    Salama, E.; Soliman, H. A.

    2018-07-01

    In this paper, thermoluminescence glow curves of gamma irradiated magnesium borate glass doped with dysprosium were studied. The number of interfering peaks and in turn the number of electron trap levels are determined using the Repeated Initial Rise (RIR) method. At different heating rates (β), the glow curves were deconvoluted into two interfering peaks based on the results of RIR method. Kinetic parameters such as trap depth, kinetic order (b) and frequency factor (s) for each electron trap level is determined using the Peak Shape (PS) method. The obtained results indicated that, the magnesium borate glass doped with dysprosium has two electron trap levels with the average depth energies of 0.63 and 0.79 eV respectively. These two traps have second order kinetic and are formed at low temperature region. The obtained results due to the glow curve analysis could be used to explain some observed properties such as, high thermal fading and light sensitivity for such thermoluminescence material. In this work, systematic procedures to determine the kinetic parameters of any thermoluminescence material are successfully introduced.

  8. Optical and physical properties of sodium lead barium borate glasses doped with praseodymium ion

    NASA Astrophysics Data System (ADS)

    Lenkennavar, Susheela K.; Madhu, A.; Eraiah, B.; Kokila, M. K.

    2018-05-01

    Praseodymium doped sodium lead barium borate glasses have been prepared using single step melt quenching technique. The XRD spectrum confirms amorphous nature of glasses. The optical absorbance studies were carried out on these glasses using PekinElemer Lambda-35 Uv-Vis spectrometer in the range of 200 -1100 nm. The optical direct band gap energies were found to be in the range of 3.62 eV to 3.69 eV and indirect band gap energies were found to be in the range of 3.57 eV to 3.62eV. The refractive indices were measured by using Abbe refractometer the values are in the range of 1.620 to 1.625.

  9. Synthesis and properties of silver nanoparticles in sodium bismuth borate glasses

    NASA Astrophysics Data System (ADS)

    Patwari, D. Rajeshree; Eraiah, B.

    2018-04-01

    Rare earth doped Sodium Bismuth Borate glass samples with silver chloride were prepared by melt quenching method. X-Ray diffraction pattern was used to confirm the amorphous nature of the samples. UV-Visible Spectra was recorded to study the optical properties. Surface plasmon resonance (SPR) peak was observed due to the formation of silver nanoparticles before and after heat treatment and the presence of silver nanoparticles were confirmed by UV-Visible Spectral studies and transmission electron microscopy. The surface plasmon resonance band became wider and red shifted after longer heat treatment.

  10. Structural studies of lead lithium borate glasses doped with silver oxide.

    PubMed

    Coelho, João; Freire, Cristina; Hussain, N Sooraj

    2012-02-01

    Silver oxide doped lead lithium borate (LLB) glasses have been prepared and characterized. Structural and composition characterization were accessed by XRD, FTIR, Raman, SEM and EDS. Results from FTIR and Raman spectra indicate that Ag(2)O acts as a network modifier even at small quantities by converting three coordinated to four coordinated boron atoms. Other physical properties, such as density, molar volume and optical basicity are also evaluated. Furthermore, they are also affected by the silver oxide composition. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Volume and structural relaxation in compressed sodium borate glass.

    PubMed

    Svenson, Mouritz N; Youngman, Randall E; Yue, Yuanzheng; Rzoska, Sylwester J; Bockowski, Michal; Jensen, Lars R; Smedskjaer, Morten M

    2016-11-21

    The structure and properties of glass can be modified through compression near the glass transition temperature (T g ), and such modified structure and properties can be maintained at ambient temperature and pressure. However, once the compressed glass undergoes annealing near T g at ambient pressure, the modified structure and properties will relax. The challenging question is how the property relaxation is correlated with both the local and the medium-range structural relaxation. In this paper, we answer this question by studying the volume (density) and structural relaxation of a sodium borate glass that has first been pressure-quenched from its T g at 1 GPa, and then annealed at ambient pressure under different temperature-time conditions. Using 11 B MAS NMR and Raman spectroscopy, we find that the pressure-induced densification of the glass is accompanied by a conversion of six-membered rings into non-ring trigonal boron (B III ) units, i.e. a structural change in medium-range order, and an increase in the fraction of tetrahedral boron (B IV ), i.e. a structural change in short-range order. These pressure-induced structural conversions are reversible during ambient pressure annealing near T g , but exhibit a dependence on the annealing temperature, e.g. the ring/non-ring B III ratio stabilizes at different values depending on the applied annealing temperature. We find that conversions between structural units cannot account for the pressure-induced densification, and instead we suggest the packing of structural units as the main densification mechanism.

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

    NASA Astrophysics Data System (ADS)

    Melo, B. M. G.; Graça, M. P. F.; Prezas, P. R.; Valente, M. A.; Almeida, A. F.; Freire, F. N. A.; Bih, L.

    2016-08-01

    In this work, phosphate-borate based glasses with molar composition 20.7P2O5-17.2Nb2O5-13.8WO3-34.5A2O-13.8B2O3, where A = Li, Na, and K, were prepared by the melt quenching technique. The as-prepared glasses were heat-treated in air at 800 °C for 4 h, which led to the formation of glass-ceramics. These high chemical and thermal stability glasses are good candidates for several applications such as fast ionic conductors, semiconductors, photonic materials, electrolytes, hermetic seals, rare-earth ion host solid lasers, and biomedical materials. The present work endorses the analysis of the electrical conductivity of the as-grown samples, and also the electrical, dielectric, and structural changes established by the heat-treatment process. The structure of the samples was analyzed using X-Ray powder Diffraction (XRD), Raman spectroscopy, and density measurements. Both XRD and Raman analysis confirmed crystals formation through the heat-treatment process. The electrical ac and dc conductivities, σac and σdc, respectively, and impedance spectroscopy measurements as function of the temperature, varying from 200 to 380 K, were investigated for the as-grown and heat-treated samples. The impedance spectroscopy was measured in the frequency range of 100 Hz-1 MHz.

  13. Structural investigation of Zn doped sodium bismuth borate glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bhatia, V., E-mail: vijetabhatia0712@gmail.com; Kumar, D.; Singh, D.

    2016-05-06

    A series of Bismuth Borate Oxide Glass samples with composition x(ZnO):(15-x)Na{sub 2}O:15Bi{sub 2}O{sub 3}:70B{sub 2}O{sub 3} (variation in x is from 6 to 12 mole %) have been prepared by conventional melt quenching technique. All the chemicals used were of Analytical Grade. In order to verify the amorphous nature of the prepared samples the X-Ray Diffraction (XRD) was done. The physical and structural properties have been explored by using the techniques such as density, molar volume and FTIR in order to understand the effect of alkali and transition metal ions on the structure of these glasses. The results obtained bymore » these techniques are in good agreement to one another and with literature as well. With the increase in the content of ZnO, the increase in density and some variations in structural coordination (ratio of BO{sub 3} & BO{sub 4} structural units) have been observed.« less

  14. Gentamicin-loaded borate bioactive glass eradicates osteomyelitis due to Escherichia coli in a rabbit model.

    PubMed

    Xie, Zongping; Cui, Xu; Zhao, Cunju; Huang, Wenhai; Wang, Jianqiang; Zhang, Changqing

    2013-07-01

    The treatment of osteomyelitis induced by Gram-negative bacilli is rarely reported in the literature. This study established a rabbit tibia model of osteomyelitis induced by the Gram-negative bacillus Escherichia coli. Using this model, pellets composed of a chitosan-bonded mixture of borate bioactive glass and gentamicin were evaluated in vitro and in vivo for the treatment of osteomyelitis induced by Escherichia coli. Our results showed that the pellets in phosphate-buffered saline released gentamicin continuously over 26 days. Without the simultaneous use of a systemic antibiotic, the implantation of the gentamicin-loaded pellets into the osteomyelitis region of the tibia resulted in the eradication of 81.82% of infections, as determined by microbiological, histological and radiographic evaluation, and supported the ingrowth of new bone into the tibia defects after 6 weeks of implantation. The results indicate that the gentamicin-loaded borate bioactive glass implant, combining sustained drug release with the ability to support new bone formation, could provide a method for treating osteomyelitis induced by Gram-negative bacilli.

  15. Gentamicin-Loaded Borate Bioactive Glass Eradicates Osteomyelitis Due to Escherichia coli in a Rabbit Model

    PubMed Central

    Xie, Zongping; Cui, Xu; Zhao, Cunju; Huang, Wenhai; Wang, Jianqiang

    2013-01-01

    The treatment of osteomyelitis induced by Gram-negative bacilli is rarely reported in the literature. This study established a rabbit tibia model of osteomyelitis induced by the Gram-negative bacillus Escherichia coli. Using this model, pellets composed of a chitosan-bonded mixture of borate bioactive glass and gentamicin were evaluated in vitro and in vivo for the treatment of osteomyelitis induced by Escherichia coli. Our results showed that the pellets in phosphate-buffered saline released gentamicin continuously over 26 days. Without the simultaneous use of a systemic antibiotic, the implantation of the gentamicin-loaded pellets into the osteomyelitis region of the tibia resulted in the eradication of 81.82% of infections, as determined by microbiological, histological and radiographic evaluation, and supported the ingrowth of new bone into the tibia defects after 6 weeks of implantation. The results indicate that the gentamicin-loaded borate bioactive glass implant, combining sustained drug release with the ability to support new bone formation, could provide a method for treating osteomyelitis induced by Gram-negative bacilli. PMID:23629702

  16. Bone regeneration in rat calvarial defects implanted with fibrous scaffolds composed of a mixture of silicate and borate bioactive glasses.

    PubMed

    Gu, Yifei; Huang, Wenhai; Rahaman, Mohamed N; Day, Delbert E

    2013-11-01

    Previous studies have evaluated the capacity of porous scaffolds composed of a single bioactive glass to regenerate bone. In the present study, scaffolds composed of a mixture of two different bioactive glasses (silicate 13-93 and borate 13-93B3) were created and evaluated for their response to osteogenic MLO-A5 cells in vitro and their capacity to regenerate bone in rat calvarial defects in vivo. The scaffolds, which have similar microstructures (porosity=58-67%) and contain 0, 25, 50 and 100 wt.% 13-93B3 glass, were fabricated by thermally bonding randomly oriented short fibers. The silicate 13-93 scaffolds showed a better capacity to support cell proliferation and alkaline phosphatase activity than the scaffolds containing borate 13-93B3 fibers. The amount of new bone formed in the defects implanted with the 13-93 scaffolds at 12 weeks was 31%, compared to values of 25, 17 and 20%, respectively, for the scaffolds containing 25, 50 and 100% 13-93B3 glass. The amount of new bone formed in the 13-93 scaffolds was significantly higher than in the scaffolds containing 50 and 100% 13-93B3 glass. While the 13-93 fibers were only partially converted to hydroxyapatite at 12 weeks, the 13-93B3 fibers were fully converted and formed a tubular morphology. Scaffolds composed of an optimized mixture of silicate and borate bioactive glasses could provide the requisite architecture to guide bone regeneration combined with a controllable degradation rate that could be beneficial for bone and tissue healing. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  17. Luminescence study and CIE diagram of certain alkaline sodium lead borate glass for LED applications

    NASA Astrophysics Data System (ADS)

    Lenkennavar, S. K.; Madhu, A.; Eraiah, B.; Kokila, M. K.

    2018-04-01

    In the present work, the glass composition 20Na2O -10PbO-10MO -60B2O3 doped with Praseodymium ions have been synthesised using muffle furnace by the conventional melt quenching technique and the effect of Pr3+ ions on optical properties of present glasses have been examined. The emission spectra were recorded in the wavelength range of 450-750nm upon excitation at 450 and 550nm. The Commission International deI'Eclairage (CIE) chromaticity coordinates are determined to estimate the emission colour of the Pr3+ incorporated barium/calcium/strontium sodium lead borate glasses. It is observed that blue LED and red LED applications can be expected by tuning the excitation wavelength applied to the same glass matrices.

  18. Evaluation of an injectable bioactive borate glass cement to heal bone defects in a rabbit femoral condyle model.

    PubMed

    Cui, Xu; Huang, Wenhai; Zhang, Yadong; Huang, Chengcheng; Yu, Zunxiong; Wang, Lei; Liu, Wenlong; Wang, Ting; Zhou, Jie; Wang, Hui; Zhou, Nai; Wang, Deping; Pan, Haobo; Rahaman, Mohamed N

    2017-04-01

    There is a need for synthetic biomaterials to heal bone defects using minimal invasive surgery. In the present study, an injectable cement composed of bioactive borate glass particles and a chitosan bonding solution was developed and evaluated for its capacity to heal bone defects in a rabbit femoral condyle model. The injectability and setting time of the cement in vitro decreased but the compressive strength increased (8±2MPa to 31±2MPa) as the ratio of glass particles to chitosan solution increased (from 1.0gml -1 to 2.5gml -1 ). Upon immersing the cement in phosphate-buffered saline, the glass particles reacted and converted to hydroxyapatite, imparting bioactivity to the cement. Osteoblastic MC3T3-E1 cells showed enhanced proliferation and alkaline phosphatase activity when incubated in media containing the soluble ionic product of the cement. The bioactive glass cement showed a better capacity to stimulate bone formation in rabbit femoral condyle defects at 12weeks postimplantation when compared to a commercial calcium sulfate cement. The injectable bioactive borate glass cement developed in this study could provide a promising biomaterial to heal bone defects by minimal invasive surgery. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Mixed alkali effect on the spectroscopic properties of alkali-alkaline earth oxide borate glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Srinivas, G., E-mail: srinu123g@gmail.com; Ramesh, B.; Shareefuddin, Md.

    2016-05-06

    The mixed alkali and alkaline earth oxide borate glass with the composition xK{sub 2}O - (25-x) Li{sub 2}O-12.5BaO-12.5MgO-50B{sub 2}O{sub 3} (x = 0, 5, 10, 15, 20 and 25mol %) and doped with 1mol% CuO were prepared by the melt quenching technique. From the optical absorption spectra the optical band gap, electronic polarizability(α{sub 0}2-), interaction parameter (A), theoretical and experimental optical basicity (Λ) values were evaluated. From the Electron Paramagnetic Resonance (EPR) spectral data the number of spins (N) and susceptibility (χ) were evaluated. The values of (α{sub 0}2-), and (Λ) increases with increasing of K{sub 2}O content and electronicmore » polarizability and interaction parameter show opposite behaviuor which may be due to the creation of non-bridging oxygens and expansion of borate network. The reciprocal of susceptibility (1/χ) and spin concentration (N) as a function of K{sub 2}O content, varied nonlinearly which may be due to creation of non-bridging oxygens in the present glass system. This may be attributed to mixed alkali effect (MAE).« less

  20. Effect of bioactive borate glass microstructure on bone regeneration, angiogenesis, and hydroxyapatite conversion in a rat calvarial defect model.

    PubMed

    Bi, Lianxiang; Rahaman, Mohamed N; Day, Delbert E; Brown, Zackary; Samujh, Christopher; Liu, Xin; Mohammadkhah, Ali; Dusevich, Vladimir; Eick, J David; Bonewald, Lynda F

    2013-08-01

    Borate bioactive glasses are biocompatible and enhance new bone formation, but the effect of their microstructure on bone regeneration has received little attention. In this study scaffolds of borate bioactive glass (1393B3) with three different microstructures (trabecular, fibrous, and oriented) were compared for their capacity to regenerate bone in a rat calvarial defect model. 12weeks post-implantation the amount of new bone, mineralization, and blood vessel area in the scaffolds were evaluated using histomorphometric analysis and scanning electron microscopy. The amount of new bone formed was 33%, 23%, and 15%, respectively, of the total defect area for the trabecular, oriented, and fibrous microstructures. In comparison, the percent new bone formed in implants composed of silicate 45S5 bioactive glass particles (250-300μm) was 19%. Doping the borate glass with copper (0.4 wt.% CuO) had little effect on bone regeneration in the trabecular and oriented scaffolds, but significantly enhanced bone regeneration in the fibrous scaffolds (from 15 to 33%). The scaffolds were completely converted to hydroxyapatite within the 12week implantation. The amount of hydroxyapatite formed, 22%, 35%, and 48%, respectively, for the trabecular, oriented, and fibrous scaffolds, increased with increasing volume fraction of glass in the as-fabricated scaffold. Blood vessels infiltrated into all the scaffolds, but the trabecular scaffolds had a higher average blood vessel area compared with the oriented and fibrous scaffolds. While all three scaffold microstructures were effective in supporting bone regeneration, the trabecular scaffolds supported more bone formation and may be more promising in bone repair. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  1. A study of physical and optical absorption spectra of VO{sup 2+} ions in potassium and sodium oxide borate glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Srinivas, G., E-mail: srinu123g@gmail.com; Ramesh, B.; Kumar, J. Siva

    2016-05-23

    Spectroscopic and physical properties of V{sub 2}O{sub 5} doped mixed alkali borate glasses are investigated. Borate glasses containing fixed concentrations of alkaline earth oxides (MgO and BaO) and alkali oxides (K{sub 2}O and Na{sub 2}O) were changes and are prepared by melt quenching technique. The values of r{sub i}, r{sub p}, R{sub m}, α{sub m} molar volume and Λ{sub th} increase and oxygen packing density, density and dopant ion concentration decrease with increasing of K{sub 2}O content. As a result there shall be an increase in the disorder of the glass network. The optical band gap energies, Urbach energy, boron-boronmore » separation,refractive index, dielectric constant, electronic polarizability and reflection loss values are varies nonlinearly with the K{sub 2}O content which manifests the mixed alkali effect.« less

  2. Tris(thioimidazolyl)borate-zinc-thiolate complexes for the modeling of biological thiolate alkylations.

    PubMed

    Ibrahim, Mohamed M; Seebacher, Jan; Steinfeld, Gunther; Vahrenkamp, Heinrich

    2005-11-14

    The S3Zn-SR coordination of thiolate-alkylating enzymes such as the Ada DNA repair protein was reproduced in tris(thioimidazolyl)borate-zinc-thiolate complexes Tti(R)Zn-SR'. Four different Tti(R) ligands and nine different thiolates were employed, yielding a total of 12 new complexes. In addition, one Tti(R)Zn-SH complex and two thiolate-bridged [Tti(R)-SEt-Tti(R)]+ complexes were obtained. A selection of six thiolate complexes was converted with methyl iodide to the corresponding methyl thioethers and Tti(R)Zn-I. According to a kinetic analysis these reactions are second-order processes, which implies that the alkylations are likely to occur at the zinc-bound thiolates. They are much faster than the alkylations of zinc thiolates with N3 or N2S tripod ligands. The most reactive thiolate, Tti(Xyl)Zn-SEt, reacts slowly with trimethyl phosphate in a nonpolar medium at room temperature, yielding methyl-ethyl-thioether and Tti(Xyl)Zn-OPO(OMe)2 which can be converted back to the thiolate complex with NaSEt. This is the closest reproduction of the Ada repair process so far.

  3. Synthesis and characterization of γ-irradiated cadmium-borate glasses doped V2O5

    NASA Astrophysics Data System (ADS)

    Bahammam, S.; Abd El Al, S.; Ezz-Eldin, F. M.

    In this work, we study the relationship between the optical and magnetic properties for the irradiated and unirradiated V2O5-doped cadmium borate glasses and examined their optical band energy that has compromise of non-bridging oxygen (NBO) and bridging oxygen (BO), V3+, V4+ and V5+, and BO3 units and BO4 units. The induced defects created by γ-rays were characterized by optical and EPR spectroscopy. The dependability of the defects and the tendency for recombination or conversion of the defects besides the environment of optically dynamic V centers was also discussed. It is concluded that the development of both optical and magnetic intensity is related to V4+ ions at tetrahedral sites whereas the decrease in their intensity is recognized to the ligand-metal charge transfer transitions of V4+ ions coupled to V5+. The optical band gap energy (Eg) has been observed to decrease with increasing either V2O5 content or γ-doses. High γ-dose reduces the values of the allowed direct optical band gap Eg of 0.5 Mol% V2O5 glass up to 45 kGy after which Eg increases, but remain lower than that of un-irradiated glass. Borate glasses under this study showed linear optical absorption response over the dose range of 5-80 kG. Fading under dark and room light in 2 h after exposure in the course of 30 days have been studied in detail and presented. Our results and findings indicate that, the investigated samples may be seemed to be a good candidate for radiation processing purposes.

  4. Influence of MO/MF2 modifiers (M = Ca, Sr, Ba) on spectroscopic properties of Eu3+ ions in germanate and borate glasses

    NASA Astrophysics Data System (ADS)

    Zur, Lidia; Janek, Joanna; Pietrasik, Ewa; Sołtys, Marta; Pisarska, Joanna; Pisarski, Wojciech A.

    2016-11-01

    Series of Eu3+-doped lead-free germanate and borate glasses were synthesized. The MO glass modifiers (M = Ca, Sr or Ba) were partially or totally substituted by MF2 in chemical composition. In contrast to samples modified by CaO/CaF2 or SrO/SrF2, the germanate glass samples containing BaO and/or BaF2 are fully amorphous, while the lead-free borate glasses are fully amorphous, independently from glass modifiers. Effect of glass modifiers on spectroscopic properties of Eu3+ were systematically investigated. For that reason, excitation and emission spectra of Eu3+ ions in examined systems were registered. Based on the emission spectra, ratio of integrated luminescence intensity of the 5D0 → 7F2 transition to that of the 5D0 → 7F1 transition (R factor) was calculated. Moreover, the luminescence decay curves were collected and the luminescence lifetimes of the 5D0 excited state of Eu3+ ions were determined in function of MF2 concentration.

  5. Emission properties of Ce3+ centers in barium borate glasses prepared from different precursor materials

    NASA Astrophysics Data System (ADS)

    Torimoto, Aya; Masai, Hirokazu; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki; Ohkubo, Takahiro

    2017-10-01

    The photoluminescence (PL) and X-ray induced luminescence properties of Ce-doped barium borate glasses prepared from different precursor materials have been investigated. Oxidation of Ce3+ takes place during the melting process performed using a pre-vitrified non-doped glass. Residual groups originated from the precursor materials, such as fluorine atoms and OH groups, are found to affect the optical and emission properties of the glasses. Moreover, both the PL and the X-ray induced luminescence properties of the glasses depend on the precursor materials used for their synthesis. Based on a thorough analysis of the emission properties, we conclude that the best synthesis conditions involve melting a batch containing Ce(CH3COO)3·H2O, BaCO3, and B2O3 in Ar atmosphere.

  6. Spectroscopy and energy transfer in lead borate glasses doubly doped with Tm3+ and Dy3+ ions

    NASA Astrophysics Data System (ADS)

    Górny, Agata; Sołtys, Marta; Pisarska, Joanna; Pisarski, Wojciech A.

    2018-03-01

    Lead borate glasses singly and doubly doped with Tm3+ and Dy3+ were prepared by traditional melt-quenching technique. The emission spectra of rare earths in studied glass systems were registered under different excitation wavelengths. The observed emission bands are located in the visible spectral region. They correspond to 1D2 → 3F4 (blue) and 1G4 → 3H6 (blue) transitions of Tm3+ as well as 4F9/2 → 6H15/2 (blue), 4F9/2 → 6H13/2 (yellow) and 4F9/2 → 6H11/2 (red) transitions of Dy3+. Moreover, the energy transfer process from Tm3+ to Dy3+ was observed. The luminescence bands originating to characteristic transitions of thulium and dysprosium ions are present on emission spectra under direct excitation of Tm3+. Luminescence lifetimes for the excited states of Tm3+ and Dy3+ ions in lead borate glass were also determined based on decay measurements. The luminescence intensities and lifetimes depend significantly on the relative concentrations of the optically active dopants.

  7. Teicoplanin-loaded borate bioactive glass implants for treating chronic bone infection in a rabbit tibia osteomyelitis model.

    PubMed

    Zhang, Xin; Jia, Weitao; Gu, Yifei; Xiao, Wei; Liu, Xin; Wang, Deping; Zhang, Changqing; Huang, Wenhai; Rahaman, Mohamed N; Day, Delbert E; Zhou, Nai

    2010-08-01

    The treatment of chronic osteomyelitis (bone infection) remains a clinical challenge. In this work, pellets composed of a chitosan-bonded mixture of borate bioactive glass particles (<50microm) and teicoplanin powder (antibiotic), were evaluated in vitro and in vivo for treating chronic osteomyelitis induced by methicillin-resistant Staphylococcus aureus (MRSA) in a rabbit model. When immersed in phosphate-buffered saline, the pellets showed sustained release of teicoplanin over 20-30 days, while the bioactive glass converted to hydroxyapatite (HA) within 7 days, eventually forming a porous HA structure. Implantation of the teicoplanin-loaded pellets in a rabbit tibia osteomyelitis model resulted in the detection of teicoplanin in the blood for about 9 days. The implants converted to a bone-like HA graft, and supported the ingrowth of new bone into the tibia defects within 12 weeks of implantation. Microbiological, histological and scanning electron microscopy techniques showed that the implants provided a cure for the bone infection. The results indicate that the teicoplanin-loaded borate bioactive glass implant, combining sustained drug release with the ability to support new bone ingrowth, could provide a method for treating chronic osteomyelitis. Copyright 2010 Elsevier Ltd. All rights reserved.

  8. Effect of silver ions and clusters on the luminescence properties of Eu-doped borate glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jiao, Qing, E-mail: jiaoqing@nbu.edu.cn; Wang, Xi; Qiu, Jianbei

    2015-12-15

    Highlights: • Ag{sup +} and Ag clusters are investigated in the borate glasses via ion exchange method. • The aggregation of silver ions to the clusters was controlled by the ion exchange concentration. • Eu{sup 3+}/Eu{sup 2+} ions emission was enhanced with the sensitization of the silver species. • Energy transfer process from Ag ions and Ag clusters to Eu ions is identified by the lifetime measurements. - Abstract: Silver ions and clusters were applied to Eu{sup 3+}-doped borate glasses via the Ag{sup +}–Na{sup +} ion exchange method. Eu{sup 3+}/Eu{sup 2+} ion luminescence enhancement was achieved after silver ion exchange.more » Absorption spectra showed no band at 420 nm, which indicates that silver nanoparticles can be excluded as a silver state in the glass. Silver ion aggregation into clusters during the ion exchange process may be inferred. The effect of silver ions and clusters on rare earth emissions was investigated using spectral information and lifetime measurements. Significant luminescence enhancements were observed from the energy transfer of Ag{sup +} ions and clusters to Eu{sup 3+}/Eu{sup 2+} ions, companied with the silver ions aggregated into the clusters state. The results of this research may extend the current understanding of interactions between rare-earth ions and Ag species.« less

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Melo, B. M. G.; Graça, M. P. F., E-mail: mpfg@ua.pt; Prezas, P. R.

    2016-08-07

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

  10. Bioactive borate glass scaffolds: in vitro and in vivo evaluation for use as a drug delivery system in the treatment of bone infection.

    PubMed

    Liu, Xin; Xie, Zongping; Zhang, Changqing; Pan, Haobo; Rahaman, Mohamed N; Zhang, Xin; Fu, Qiang; Huang, Wenhai

    2010-02-01

    The objective of this work was to evaluate borate bioactive glass scaffolds (with a composition in the system Na(2)O-K(2)O-MgO-CaO-B(2)O(3)-P(2)O(5)) as devices for the release of the drug Vancomycin in the treatment of bone infection. A solution of ammonium phosphate, with or without dissolved Vancomycin, was used to bond borate glass particles into the shape of pellets. The in vitro degradation of the pellets and their conversion to a hydroxyapatite-type material in a simulated body fluid (SBF) were investigated using weight loss measurements, chemical analysis, X-ray diffraction, and scanning electron microscopy. The results showed that greater than 90% of the glass in the scaffolds degraded within 1 week, to form poorly crystallized hydroxyapatite (HA). Pellets loaded with Vancomycin provided controlled release of the drug over 4 days. Vancomycin-loaded scaffolds were implanted into the right tibiae of rabbits infected with osteomyelitis. The efficacy of the treatment was assessed using microbiological examination and histology. The HA formed in the scaffolds in vivo, resulting from the conversion of the glass, served as structure to support the growth of new bone and blood vessels. The results in this work indicate that bioactive borate glass could provide a promising biodegradable and bioactive material for use as both a drug delivery system and a scaffold for bone repair.

  11. [Injectable borate glass/chitosan composite as drug carrier for treatment of chronic osteomyelitis].

    PubMed

    Zhao, Cunju; Wang, Xinfu; Zhang, Changqing; Cui, Xu; Jia, Weitao; Huang, Wenchan

    2012-06-01

    To evaluate the characterization, biocompatibility in vitro and in vivo, and antimicrobial activity of an injectable vancomycin-loaded borate glass/chitosan composite (VBC) so as to lay the foundation for its further clinical application. The solid phase of VBC was constituted by borate glass and vancomycin, liquid phase was a mixture of chitosan, citric acid, and glucose with the proportion of 1 : 10 : 20. Solid phase and liquid phase was mixed with the ratio of 2 : 1. Vancomycin-loaded calcium sulfate (VCS) was produced by the same method using calcium sulfate instead of borate glass and saline instead of chitosan, as control. High performance liquid chromatography was applied to detect the release rate of antibiotics from VBC and VCS, and minimum inhibitory concentration (MIC) was tested by using an antibiotic tube dilution method. The structure of the VBC and VCS specimens before and 2, 4, 8, 16, and 40 days after immersion in D-Hank's was examined by scanning electron microscopy, and the phase composition of VBC was analysed by X-ray diffraction after soaked for 40 days. Thirty-three healthy adult New Zealand white rabbits (weighing, 2.25-3.10 kg; male or female) were used to establish the osteomyelitis models according to Norden method. After 4 weeks, the models of osteomyelitis were successfully established in 28 rabbits, and they were randomly divided into 4 groups (groups A, B, C, and D). In group A (n=8), simple debridement was performed; in groups B and C (n=8), defect was treated by injecting VCS or VBC after debridement; and in group D (n=4), no treatment was given. The effectiveness of treatment was assessed using radiological and histological techniques after 2 months. The releases of vancomycin from VBC lasted for 30 days; the release rate of vancomycin reached 75% at the first 8 days, then could reached more than 90%. The releases of vancomycin from VCS lasted only for 16 days. The MIC of VBC and VCS were both 2 microg/mL. The VCS had a smooth

  12. XRD and FTIR analysis heat treated lithium bismo-borate glasses doped with 1.0 mol% copper ferrite

    NASA Astrophysics Data System (ADS)

    Yadav, Arti; Narwal, P.; Dahiya, Manjeet S.; Dahiya, T.; Agarwal, A.; Khasa, S.

    2018-05-01

    Glasses of compositions of 20Li20 • xBi2O3• (79-x)B2O3 + (1.0 mol%) CuFe2O4, with 0 ≤ x ≤ 40 were prepared by melt-quench technique. To obtain the glass-ceramics the controlled heat treatment were given to the prepared glasses. Two nano crystalline phases, i.e., Li2B4O7 and LiB3O5 were observed from X-ray diffraction patterns of the prepared glass- ceramic samples. We investigated the change in coordination number of network formers B2O3 and Bi2O3 and network modifiers Bi2O3, Li2O and CuFe2O4. Crystallites size (lies in range ˜47-50nm) and lattice strain (ɛ) were calculated for major phases for all prepared samples. FT-IR study revealed the de-polymerization of borate groups that change with heat treatment and Bi2O3 content. Deconvolution of IR absorption spectra resolves the overlapped and hidden peaks in IR spectra. Sharp and more intense FTIR peaks confirm the vibrations due to crystallites Li2B4O7 and LiB3O5 and change in coordination of network forming borate units.

  13. In vitro bioactivity behavior of modified multicomponent borate glasses containing dopants of Ag2O, CuO, CeO2 or V2O5

    NASA Astrophysics Data System (ADS)

    Marzouk, M. A.; ElBatal, F. H.; Ghoneim, N. A.

    2018-02-01

    Some multi-component borate glasses containing dopants of Ag2O, CuO, CeO2 or V2O5 were prepared. Multi-characterization techniques were carried out to investigate their bioactivity, corrosion weight loss after immersion in phosphate solution. Controlled thermal heat-treatment by two-step technique was done to convert the prepared glasses to their corresponding glass-ceramic derivatives. X-ray diffraction analysis was performed to identify the crystalline phases formed by thermal treatment. Infrared absorption of glasses and glass-ceramics reveal vibrational bands due to combined main triangular and tetrahedral borate groups in their specific wavenumbers besides some sharing of phosphate group. After immersion in the phosphate solution, two extra characteristic peaks are generated indicating the bioactivity of the studied glasses and glass-ceramics through the formation of calcium phosphate (hydroxyapatite). X-ray diffraction data indicate the formation of crystalline phases which are variable with the introduced dopants. The main crystalline phase identified is calcium borate together with some other phases some of which contain phosphate ions. These data indicate that the presence of CaO and P2O5 initiates phase separation and subsequent crystallization of the parent and doped glasses. Weight loss data indicate that glass-ceramics are obviously durable than the parent glasses. SEM micrographs of glass-ceramics before immersion show multiconstituent crystalline phases due to the basic chemical composition consisting of multicomponent mixed alkali and alkaline earth oxides beside P2O5 and with the main B2O3 constituent. After immersion, the crystalline phases are identified to be more distinct in different shapes because of the multi-composition involved.

  14. Structure and luminescence properties of Dy 2O 3 doped bismuth-borate glasses

    DOE PAGES

    Mugoni, Consuelo; Gatto, C.; Pla-Dalmau, A.; ...

    2017-07-05

    In this study heavy bismuth-borate glasses were studied as host matrices of Dy 2O 3 rare earth, for potential application as scintillator materials in high energy physics experiments and in general radiation detection systems. Glass matrices were prepared from 20BaO-xBi 2O 3-(80-x)B 2O 3 (x = 20, 30, 40 mol%) ternary systems and synthesized by the melt-quenching method at different temperatures in order to obtain high density and high transparency in the UV/Vis range. Particularly, the glass manifesting the higher transparency and with sufficiently high density was doped with Dy 2O 3 (2.5 and 5 mol%) in order to inducemore » the luminescence characteristics. The effects of Bi 2O 3 and Dy 2O 3 on density, thermal behaviour, transmission as well as luminescence properties under UV excitation, were investigated. The experimental results show that the synthesized glasses can be considered promising candidate materials as dense scintillators, due to the Dy 3 + centres emission.« less

  15. Optical properties of Nd3+ doped bismuth zinc borate glasses

    NASA Astrophysics Data System (ADS)

    Shanmugavelu, B.; Venkatramu, V.; Ravi Kanth Kumar, V. V.

    2014-03-01

    Glasses with compositions of (100-x) (Bi2ZnOB2O6) - x Nd2O3 (where x = 0.1, 0.3, 0.5, 1 and 2 mol%) were prepared by melt quenching method and characterized through optical absorption, emission and decay curve measurements. Optical absorption spectra have been analyzed using Judd-Ofelt theory. The emission spectra exhibit three peaks at 919, 1063 and 1337 nm corresponding to 4F3/2 to 4I9/2, 4I11/2 and 4I13/2 transitions in the near infrared region. The emission intensity of the 4F3/2 to 4I11/2 transition increases with increase of Nd3+ concentration up to 1 mol% and then concentration quenching is observed for 2 mol% of Nd3+ concentration. The lifetimes for the 4F3/2 level are found to decrease with increase in Nd2O3 concentration in the glasses. The decay curves of the glass up to 0.3 mol% of Nd3+ exhibit single exponential nature and thereafter the curves become nonexponential nature (0.5, 1 and 2 mol%). The nonexponential curve has been fitted to the Inokuti-Hirayama model to understand the nature of energy transfer process.

  16. New High Capacity Cathode Materials for Rechargeable Li-ion Batteries: Vanadate-Borate Glasses

    NASA Astrophysics Data System (ADS)

    Afyon, Semih; Krumeich, Frank; Mensing, Christian; Borgschulte, Andreas; Nesper, Reinhard

    2014-11-01

    V2O5 based materials are attractive cathode alternatives due to the many oxidation state switches of vanadium bringing about a high theoretical specific capacity. However, significant capacity losses are eminent for crystalline V2O5 phases related to the irreversible phase transformations and/or vanadium dissolution starting from the first discharge cycle. These problems can be circumvented if amorphous or glassy vanadium oxide phases are employed. Here, we demonstrate vanadate-borate glasses as high capacity cathode materials for rechargeable Li-ion batteries for the first time. The composite electrodes of V2O5 - LiBO2 glass with reduced graphite oxide (RGO) deliver specific energies around 1000 Wh/kg and retain high specific capacities in the range of ~ 300 mAh/g for the first 100 cycles. V2O5 - LiBO2 glasses are considered as promising cathode materials for rechargeable Li-ion batteries fabricated through rather simple and cost-efficient methods.

  17. New high capacity cathode materials for rechargeable Li-ion batteries: vanadate-borate glasses.

    PubMed

    Afyon, Semih; Krumeich, Frank; Mensing, Christian; Borgschulte, Andreas; Nesper, Reinhard

    2014-11-19

    V2O5 based materials are attractive cathode alternatives due to the many oxidation state switches of vanadium bringing about a high theoretical specific capacity. However, significant capacity losses are eminent for crystalline V2O5 phases related to the irreversible phase transformations and/or vanadium dissolution starting from the first discharge cycle. These problems can be circumvented if amorphous or glassy vanadium oxide phases are employed. Here, we demonstrate vanadate-borate glasses as high capacity cathode materials for rechargeable Li-ion batteries for the first time. The composite electrodes of V2O5 - LiBO(2) glass with reduced graphite oxide (RGO) deliver specific energies around 1000 Wh/kg and retain high specific capacities in the range of ~ 300 mAh/g for the first 100 cycles. V2O5 - LiBO(2) glasses are considered as promising cathode materials for rechargeable Li-ion batteries fabricated through rather simple and cost-efficient methods.

  18. New High Capacity Cathode Materials for Rechargeable Li-ion Batteries: Vanadate-Borate Glasses

    PubMed Central

    Afyon, Semih; Krumeich, Frank; Mensing, Christian; Borgschulte, Andreas; Nesper, Reinhard

    2014-01-01

    V2O5 based materials are attractive cathode alternatives due to the many oxidation state switches of vanadium bringing about a high theoretical specific capacity. However, significant capacity losses are eminent for crystalline V2O5 phases related to the irreversible phase transformations and/or vanadium dissolution starting from the first discharge cycle. These problems can be circumvented if amorphous or glassy vanadium oxide phases are employed. Here, we demonstrate vanadate-borate glasses as high capacity cathode materials for rechargeable Li-ion batteries for the first time. The composite electrodes of V2O5 – LiBO2 glass with reduced graphite oxide (RGO) deliver specific energies around 1000 Wh/kg and retain high specific capacities in the range of ~ 300 mAh/g for the first 100 cycles. V2O5 – LiBO2 glasses are considered as promising cathode materials for rechargeable Li-ion batteries fabricated through rather simple and cost-efficient methods. PMID:25408200

  19. Optical properties of Nd3+ doped bismuth zinc borate glasses.

    PubMed

    Shanmugavelu, B; Venkatramu, V; Ravi Kanth Kumar, V V

    2014-03-25

    Glasses with compositions of (100-x) (Bi2ZnOB2O6) -x Nd2O3 (where x=0.1, 0.3, 0.5, 1 and 2 mol%) were prepared by melt quenching method and characterized through optical absorption, emission and decay curve measurements. Optical absorption spectra have been analyzed using Judd-Ofelt theory. The emission spectra exhibit three peaks at 919, 1063 and 1337 nm corresponding to (4)F3/2 to (4)I9/2, (4)I11/2 and (4)I13/2 transitions in the near infrared region. The emission intensity of the (4)F3/2 to (4)I11/2 transition increases with increase of Nd(3+) concentration up to 1 mol% and then concentration quenching is observed for 2 mol% of Nd(3+) concentration. The lifetimes for the (4)F3/2 level are found to decrease with increase in Nd2O3 concentration in the glasses. The decay curves of the glass up to 0.3 mol% of Nd(3+) exhibit single exponential nature and thereafter the curves become nonexponential nature (0.5, 1 and 2 mol%). The nonexponential curve has been fitted to the Inokuti-Hirayama model to understand the nature of energy transfer process. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Impact of Nd3+ ions on physical and optical properties of Lithium Magnesium Borate glass

    NASA Astrophysics Data System (ADS)

    Mhareb, M. H. A.; Hashim, S.; Ghoshal, S. K.; Alajerami, Y. S. M.; Saleh, M. A.; Dawaud, R. S.; Razak, N. A. B.; Azizan, S. A. B.

    2014-11-01

    Enhancing the up-conversion efficiency of borate glass via optimized doping of rare earth ions is an ever-ending quest in lasing glass. Neodymium (Nd3+) doped Lithium Magnesium Borate (LMB) glasses are prepared using the melt-quenching method. X-ray diffraction (XRD), Fourier transformed infrared (FTIR), UV-Vis-NIR absorption and Photoluminescence (PL) spectroscopic characterizations are made to examine the influence of Nd3+ concentration on physical properties and optical properties. Nd3+ contents dependent density, molar volume, refractive index, ion concentration, Polaron radius, inter nuclear distance, field strength, energy band gap and oscillator strength are calculated. XRD patterns confirm the amorphous nature of all glasses and the FTIR spectra reveal the presence of BO3 and BO4 functional groups. UV-Vis-IR spectra exhibit ten prominent bands centered at 871, 799, 741, 677, 625, 580, 522, 468, 426, 349 nm corresponding to the transitions from the ground state to 4F3/2, (4F5/2 + 2H9/2), (4F7/2 + 4S3/2), 4F9/2, 2H11/2, (4G5/2 + 2G7/2), (2K13/2 + 4G7/2 + 4G9/2), (2G9/2 + 2D3/2 + 2P3/2), (2P1/2 + 2D5/2), (4D3/2 + 4D5/2) excited states, respectively. A hyper-sensitive transition related to (4G5/2 + 2G7/2) level is evidenced at 580 nm. The room temperature up-conversion emission spectra at 800 nm excitation displays three peaks centered at 660, 610 and 540 nm. Glass with 0.5 mol% of Nd3+ showing an emission enhancement by a factor to two is attributed to the energy transfer between Mg2+ and Nd3+ ions. Our results suggest that these glasses can be nominated for solid state lasers and other photonic devices.

  1. Composition-structure-properties relationship of strontium borate glasses for medical applications.

    PubMed

    Hasan, Muhammad S; Werner-Zwanziger, Ulrike; Boyd, Daniel

    2015-07-01

    We have synthesized TiO2 doped strontium borate glasses, 70B2O3-(30-x)SrO-xTiO2 and 70B2 O3 -20SrO(10-x)Na2 O-xTiO2 . The composition dependence of glass structure, density, thermal properties, durability, and cytotoxicity of degradation products was studied. Digesting the glass in mineral acid and detecting the concentrations of various ions using an ICP provided the actual compositions that were 5-8% deviated from the theoretical values. The structure was investigated by means of (11)B magic angle spinning (MAS) NMR spectroscopy. DSC analyses provided the thermal properties and the degradation rates were measured by measuring the weight loss of glass disc-samples in phosphate buffered saline at 37°C in vitro. Finally, the MTT assay was used to analyze the cytotoxicity of the degradation products. The structural analysis revealed that replacing TiO2 for SrO or Na2 O increased the BO3/BO4 ratio suggesting the network-forming role of TiO2 . Thermal properties, density, and degradation rates also followed the structural changes. Varying SrO content predominantly controlled the degradation rates, which in turn controlled the ion release kinetics. A reasonable control (2-25% mass loss in 21 days) over mass loss was achieved in current study. Even though, very high concentrations (up to 5500 ppm B, and 1200 ppm Sr) of ions were released from the ternary glass compositions that saturated the degradation media in 7 days, the degradation products from ternary glass system was found noncytotoxic. However, quaternary glasses demonstrated negative affect on cell viability due to very high (7000 ppm) Na ion concentration. All the glasses investigated in current study are deemed fast degrading with further control over degradation rates, release kinetics desirable. © 2014 Wiley Periodicals, Inc.

  2. Spectroscopic investigations of Nd3+ doped flouro- and chloro-borate glasses.

    PubMed

    Mohan, Shaweta; Thind, Kulwant Singh; Sharma, Gopi; Gerward, Leif

    2008-10-01

    Spectroscopic and physical properties of Nd3+ doped sodium lead flouro- and chloro-borate glasses of the type 20NaX-30PbO-49.5B2O3-0.5Nd2O3 (X=F and Cl) have been investigated. Optical absorption spectra have been used to determine the Slater Condon (F2, F4, and F6), spin orbit xi4f and Racah parameters (E1, E2, and E3). The oscillator strengths and the intensity parameters Omega2, Omega4 and Omega6 have been determined by the Judd-Ofelt theory, which in turn provide the radiative transition probability (A), total transition probability (A(T)), radiative lifetime (tauR) and branching ratio (beta) for the fluorescent level 4F3/2. The lasing efficiency of the prepared glasses has been characterized by the spectroscopic quality factor (Omega4/Omega6), the value of which is in the range of 0.2-1.5, typical for Nd3+ in different laser hosts. Nephelauxetic effect results in a red shift in the energy levels of Nd3+ for chloroborate glass. The radiative transition probability of the potential lasing transition 4F3/2-->4I11/2 of Nd3+ ions is found to be higher for flouroborate as compared to chloroborate glass.

  3. Visible properties of Sm{sup 3+} ions in chloro-fluoro-borate glasses for reddish - orange emission

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rao, K. Venkata, E-mail: drvenkataraok@gmail.com; Babu, S.; Ratnakaram, Y. C.

    2016-05-23

    Optical properties of different concentration (0.2, 0.4, 0.6, 0.8 and 1.0 mol %) of Sm{sup 3+} doped chloro-fluoro-borate glasses have been synthesized and discussed. Structural characterizations have been studied through XRD analysis. Spectroscopic analysis has done from absorption spectra, luminescence spectra and decay lifetime profiles. From the emission spectra, concentration quenching is observed, with increase of samarium concentration and discussed behind the phenomena. The nature of decay curve analysis was performed for the {sup 4}G{sub 5/2} level. These glasses are expected to give interesting application in the field of optics.

  4. Experimental and theoretical studies of the structure of tellurate-borate glasses network.

    PubMed

    Rada, Simona; Culea, Eugen; Neumann, Manfred

    2010-08-01

    The structural properties of the xTeO(2) x (1-x)B(2)O(3) glasses (x = 0.6; 0.7) were investigated by FT-IR spectroscopy. From the analysis of the FTIR spectra, it is reasonable to assume that by the increasing of boron ions content, the tetrahedral [BO(4)] units are gradually replaced by the trigonal [BO(3)] units. The increase in the number of non-bridging oxygen atoms would decrease the connectivity of the glass network and will yield the depolymerization of the borate chains. The molecular structure and vibrational frequencies of the proposed structural models have been studied by exploring the density functional theory (DFT) calculations. The FTIR spectra of the xTeO(2) x (1-x)B(2)O(3) vitreous systems were compared with the calculated spectrum. This procedure allowed us to assign most of the observed IR bands.

  5. Multimodal emissions from Tb{sup 3+}/Yb{sup 3+} co-doped lithium borate glass: Upconversion, downshifting and quantum cutting

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bahadur, A.; Yadav, R.S.; Yadav, R.V.

    This paper reports the optical properties of Tb{sup 3+}/Yb{sup 3+} co-doped lithium borate (LB) glass prepared by melt quench method. The absorption spectrum of the Yb{sup 3+} doped LB glass contains intense NIR band centered at 976 nm due to {sup 2}F{sub 7/2}→{sup 2}F{sub 5/2} transition. The emission spectra of the prepared glasses have been monitored on excitation with 266, 355 and 976 nm. The Yb{sup 3+} doped glass emits a broad NIR band centered at 976 nm whereas the Tb{sup 3+} doped glass gives off visible bands on excitations with 266 and 355 nm. When the Tb{sup 3+} andmore » Yb{sup 3+} ions are co-doped together, the emission intensity in the visible region decreases whereas it increases in the NIR region significantly. The increase in the emission intensity in the NIR region is due to efficient cooperative energy transfer (CET) from Tb{sup 3+} to Yb{sup 3+} ions. The quantum cutting efficiency for Tb{sup 3+}/Yb{sup 3+} co-doped glass has been calculated and compared for 266 and 355 nm excitations. The quantum cutting efficiency is larger for 355 nm excitation (137%). The Tb{sup 3+}/Yb{sup 3+} co-doped LB glass also emits upconverted visible bands on excitation with 976 nm. The mechanisms involved in the energy transfer have been discussed using schematic energy level diagram. The Tb{sup 3+}/Yb{sup 3+} co-doped LB glass may be used in the optical devices and in solar cell for solar spectral conversion and behaves as a multi-modal photo-luminescent material. - Graphical abstract: The Tb{sup 3+}/Yb{sup 3+} co-doped lithium borate (LB) glass prepared by melt quench method emits upconverted visible emissions through upconversion CET from Yb{sup 3+} to Tb{sup 3+} ions and quantum cutting emissions through downconversion CET from Tb{sup 3+} to Yb{sup 3+} ions. Therefore, the Tb{sup 3+}/Yb{sup 3+} co-doped LB glass may find applications in optical devices and solar cell and behaves as a multi-modal photo-luminescent material. - Highlights: • The Tb{sup 3

  6. Effect of SiO2 addition and gamma irradiation on the lithium borate glasses

    NASA Astrophysics Data System (ADS)

    Raut, A. P.; Deshpande, V. K.

    2018-01-01

    The physical properties like density, glass transition temperature (Tg), and ionic conductivity of lithium borate (LB) glasses with SiO2 addition were measured before and after gamma irradiation. Remarkable changes in properties have been obtained in the physical properties of LB glasses with SiO2 addition and after gamma irradiation. The increase in density and glass transition temperature of LB glasses with SiO2 addition has been explained with the help of increase in density of cross linking due to SiO4 tetrahedra formation. The increase in ionic conductivity with SiO2 addition was explained with the help of ‘mixed glass former effect’. The increase in density and Tg of LB glasses with SiO2 addition after gamma irradiation has been attributed to fragmentation of bigger ring structure into smaller rings, which increases the density of cross linking and hence compaction. The exposure of gamma irradiation has lead to decrease in ionic conductivity of LB glasses with SiO2 addition. The atomic displacement caused by gamma irradiation resulted in filling of interstices and decrease in trapping sites. This explains the obtained decrease in ionic conductivity after gamma irradiation of glasses. The obtained results of effect of SiO2 addition and gamma irradiation on the density, Tg and ionic conductivity has been supported by FTIR results.

  7. Optical and spectroscopic properties of neodymium doped cadmium-sodium borate glasses

    NASA Astrophysics Data System (ADS)

    Mohan, Shaweta; Thind, Kulwant Singh

    2017-10-01

    Neodymium doped cadmium sodium borate glasses having composition xCdO-(40-x) Na2CO3-59.5H3BO3-0.5Nd2O3; x = 10, 20 and 30 mol% were prepared by conventional melt-quenching technique. X-ray diffraction studies confirmed the amorphous nature of the prepared glasses. Conventional methods were used to determine the physical properties such as density, molar volume, refractive index, and rare earth ion concentration. The Judd-Ofelt theory was applied on the optical absorption spectra of the glasses to evaluate the three phenomenological intensity parameters Ω2, Ω4 and Ω6. The calculated intensity parameters were further used to predict the radiative transition probability (A), radiative lifetime (τR) and branching ratio (βR) for the various fluorescent levels of Nd3+ ion in the prepared glass series. The effect of the compositional changes on the spectroscopic characteristics of Nd3+ ions have been studied and reported. The value of Ω2 is found to decrease with the decrease in the sodium content and the corresponding increase in the cadmium content. This can be ascribed to the changes in the asymmetry of the ligand field at the rare earth ion site and the change in rare earth oxygen (RE-O) covalency. Florescence spectra has been used to determine the peak wavelength (λp), effective line widths (Δλeff) and stimulated emission cross-section (σp) for the 4F3/2 → 4I9/2,4I11/2,4I13/2 transitions of the Nd3+ ion. The reasonably higher values of branching ratios and stimulated emission cross-section for the prepared glasses points towards the efficacy of these glasses as laser host materials. However, the glass with more sodium content is found to show better lasing properties.

  8. Appearance of small polaron hopping conduction in iron modified cobalt lithium bismuth borate glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dahiya, M. S.; Khasa, S., E-mail: skhasa@yahoo.com; Yadav, Arti

    2016-05-23

    Lithium bismuth borate glasses containing different amounts of cobalt and iron oxides having chemical composition xFe{sub 2}O{sub 3}•(20-x)CoO•30Li{sub 2}O•10Bi{sub 2}O{sub 3}•40B{sub 2}O{sub 3} (x = 0, 5, 10, 15 and 20 mol% abbreviated as CFLBB1-5 respectively) prepared via melt quench technique have been investigated for their dc electrical conductivity. The amorphous nature of prepared glasses has been confirmed through X-ray diffraction measurements. The dc electrical conductivity has been analyzed by applying Mott’s small polaron hopping model. Activation energies corresponding to lower and higher temperature region have been evaluated. The iron ion concentration (N), mean spacing between iron ions (R) and polaronmore » radius (R{sub p}) has been evaluated using the values of phonon radius (R{sub ph}) and Debye temperature (θ{sub D}). The glass sample without iron (CFLBB1) shows ionic conductivity but the incorporation of iron in the glass matrix results in the appearance of electronic conductivity.« less

  9. Narrow Energy Gap between Triplet and Singlet Excited States of Sn2+ in Borate Glass

    PubMed Central

    Masai, Hirokazu; Yamada, Yasuhiro; Suzuki, Yuto; Teramura, Kentaro; Kanemitsu, Yoshihiko; Yoko, Toshinobu

    2013-01-01

    Transparent inorganic luminescent materials have attracted considerable scientific and industrial attention recently because of their high chemical durability and formability. However, photoluminescence dynamics of ns2-type ions in oxide glasses has not been well examined, even though they can exhibit high quantum efficiency. We report on the emission property of Sn2+-doped strontium borate glasses. Photoluminescence dynamics studies show that the peak energy of the emission spectrum changes with time because of site distribution of emission centre in glass. It is also found that the emission decay of the present glass consists of two processes: a faster S1-S0 transition and a slower T1-S0 relaxation, and also that the energy difference between T1 and S1 states was found to be much smaller than that of (Sn, Sr)B6O10 crystals. We emphasize that the narrow energy gap between the S1 and T1 states provides the glass phosphor a high quantum efficiency, comparable to commercial crystalline phosphors. PMID:24345869

  10. Role of electron transfer in Ce{sup 3+} sensitized Yb{sup 3+} luminescence in borate glass

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sontakke, Atul D., E-mail: sontakke.atul.55a@st.kyoto-u.ac.jp; Katayama, Yumiko; Zhuang, Yixi

    2015-01-07

    In a Ce{sup 3+}-Yb{sup 3+} system, two mechanisms are proposed so far namely, the quantum cutting mechanism and the electron transfer mechanism explaining Yb{sup 3+} infrared luminescence under Ce{sup 3+} excitation. Among them, the quantum cutting mechanism, where one Ce{sup 3+} photon (ultraviolet/blue) gives rise to two Yb{sup 3+} photons (near infrared) is widely sought for because of its huge potential in enhancing the solar cell efficiency. In present study on Ce{sup 3+}-Yb{sup 3+} codoped borate glasses, Ce{sup 3+} sensitized Yb{sup 3+} luminescence at ∼1 μm have been observed on Ce{sup 3+} 5d state excitation. However, the intensity of sensitized Yb{supmore » 3+} luminescence is found to be very weak compared to the strong quenching occurred in Ce{sup 3+} luminescence in Yb{sup 3+} codoped glasses. Moreover, the absolute luminescence quantum yield also showed a decreasing trend with Yb{sup 3+} codoping in the glasses. The overall behavior of the luminescence properties and the quantum yield is strongly contradicting with the quantum cutting phenomenon. The results are attributed to the energetically favorable electron transfer interactions followed by Ce{sup 3+}-Yb{sup 3+} ⇌ Ce{sup 4+}-Yb{sup 2+} inter-valence charge transfer and successfully explained using the absolute electron binding energies of dopant ions in the studied borate glass. Finally, an attempt has been presented to generalize the electron transfer mechanism among opposite oxidation/reduction property dopant ions using the vacuum referred electron binding energy (VRBE) scheme for lanthanide series.« less

  11. Silicate and borate glasses as composite fillers: a bioactivity and biocompatibility study.

    PubMed

    Lopes, P P; Ferreira, B J M Leite; Gomes, P S; Correia, R N; Fernandes, M H; Fernandes, M H V

    2011-06-01

    Composites filled with a silicate glass (CSi) and a new borate glass (CB) were developed and compared in terms of their in vitro behaviour both in acellular and cellular media. Acellular tests were carried out in SBF and the composites were characterized by SEM-EDS, XRD and ICP. Biocompatibility studies were investigated by in vitro cell culture with MG-63 osteoblast-like and human bone marrow cells. The growth of spherical calcium phosphate aggregates was observed in acellular medium on all composite surfaces indicating that these materials became potentially bioactive. The biological assessment resulted in a dissimilar behavior of the composites. The CSi demonstrated an inductive effect on the proliferation of cells. The cells showed a normal morphology and high growth rate when compared to standard culture plates. Contrarily, inhibition of cell proliferation occurred in the CB probably due to its high degradation rate, leading to high B and Mg ionic concentration in the cell culture medium.

  12. Electronic polarizability and interaction parameter of gadolinium tungsten borate glasses with high WO{sub 3} content

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Taki, Yukina; Shinozaki, Kenji; Honma, Tsuyoshi

    2014-12-15

    Glasses with the compositions of 25Gd{sub 2}O{sub 3}–xWO{sub 3}–(75−x)B{sub 2}O{sub 3} with x=25–65 were prepared by using a conventional melt quenching method, and their electronic polarizabilities, optical basicities Λ(n{sub o}), and interaction parameters A(n{sub o}) were estimated from density and refractive index measurements in order to clarify the feature of electronic polarizability and bonding states in the glasses with high WO{sub 3} contents. The optical basicity of the glasses increases monotonously with the substitution of WO{sub 3} for B{sub 2}O{sub 3}, and contrary the interaction parameter decreases monotonously with increasing WO{sub 3} content. A good linear correlation was observed betweenmore » Λ(n{sub o}) and A(n{sub o}) and between the glass transition temperature and A(n{sub o}). It was proposed that Gd{sub 2}O{sub 3} oxide belongs to the category of basic oxide with a value of A(n{sub o})=0.044 Å{sup −3} as similar to WO{sub 3}. The relationship between the glass formation and electronic polarizability in the glasses was discussed, and it was proposed that the glasses with high WO{sub 3} and Gd{sub 2}O{sub 3} contents would be a floppy network system consisting of mainly basic oxides. - Graphical abstract: This figure shows the correlation between the optical basicity and interaction parameter in borate-based glasses. The data obtained in the present study for Gd{sub 2}O{sub 3}–WO{sub 3}–B{sub 2}O{sub 3} glasses are locating in the correlation line for other borate glasses. These results shown in Fig. 8 clearly demonstrate that Gd{sub 2}O{sub 3}–WO{sub 3}–B{sub 2}O{sub 3} glasses having a wide range of optical basicity and interaction parameter are regarded as glasses consisting of acidic and basic oxides. - Highlights: • Gd{sub 2}O{sub 3}–WO{sub 3}–B{sub 2}O{sub 3} glasses with high WO{sub 3} contents were prepared. • Electronic polarizability and interaction parameter were estimated. • Optical basicity

  13. Spectroscopy and energy transfer in lead borate glasses doubly doped with Dy(3)(+)-Tb(3+) and Tb(3)(+)-Eu(3+) ions.

    PubMed

    Pisarska, Joanna; Kos, Agnieszka; Pisarski, Wojciech A

    2014-08-14

    Lead borate glasses doubly doped with Dy(3)(+)-Tb(3+) and Tb(3+)-Eu(3+) were investigated using optical spectroscopy. Luminescence spectra of rare earths were detected under various excitation wavelengths. The main green emission band due to (5)D4→(7)F5 transition of Tb(3+) is observed under excitation of Dy(3+), whereas the main red emission band related to (5)D0→(7)F2 transition of Eu(3+) is successfully observed under direct excitation of Tb(3+). In both cases, the energy transfer processes from Dy(3+) to Tb(3+) and from Tb(3+) to Eu(3+) in lead borate glasses occur through a nonradiative processes with efficiencies up to 16% and 18%, respectively. The presence of energy transfer process was also confirmed by excitation spectra measurements. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Electrically conductive borate-based bioactive glass scaffolds for bone tissue engineering applications.

    PubMed

    Turk, Mert; Deliormanlı, Aylin M

    2017-07-01

    In this study, electrically conductive, borate-based, porous 13-93B3 bioactive glass composite scaffolds were prepared using a polymer foam replication technique. For this purpose, a slurry containing 40 vol% glass particles and 0-10 wt% graphene nanoplatelets was prepared by dispersing the particles in ethanol in the presence of ethyl cellulose. Composite scaffolds were subjected to a controlled heat treatment, in air atmosphere, to decompose the foam and sinter the glass particles into a dense network. It was found that the applied heat treatment did not influence the structure of graphene in the glass network. Graphene additions did not negatively affect the mechanical properties and enhanced the electrical conductivity of the glass scaffolds. In X-ray diffraction analysis, the crystalline peak corresponding to hydroxyapatite was observed in all the samples suggesting that all of the samples were bioactive after 30 days of immersion in simulated body fluid. However, Fourier transform infrared spectroscopy analysis and scanning electron microscope observations revealed that hydroxyapatite formation rate decreased with increasing graphene concentration especially for samples treated in simulated body fluid for shorter times. Based on the cytotoxicity assay findings, the MC3T3-E1 cell growth was significantly inhibited by the scaffolds containing higher amount of graphene compared to bare glass scaffolds. Best performance was obtained for 5 wt% graphene which yielded an enhancement of electrical conductivity with moderate cellular response and in vitro hydroxyapatite forming ability. The study revealed that the electrically conductive 13-93B3 graphene scaffolds are promising candidates for bone tissue engineering applications.

  15. Optical and vibrational spectroscopy of Ba0.85Ca0.15Zr0.1Ti0.9O3 modified lithium borate glass ceramics

    NASA Astrophysics Data System (ADS)

    Viswanath, Pamarti; Prashanth, Sadhu Sai Pavan; Molli, Muralikrishna; Wicram, Jaschin Prem; Sai Muthukumar, V.

    2018-04-01

    Glass ceramics are excellent replacement for single crystalline materials which are expensive and difficult to fabricate. In this context, we have attempted to fabricate glass nanocomposites comprising of Lithium Borate glass matrix embedded with lead free ferroelectric Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT). Both of these functional materials are known to exhibit excellent ferroelectric behavior and are currently explored for various device applications. We have prepared these novel glass nanocomposite using melt-quenching techniquein various chemical composition involving different molar ratio. x(Ba0.85Ca0.15Zr0.1Ti0.9O3)-(1-x)(Li2O.2B2O3) where (x=0.1,0.2,0.3,0.4). The as-quenched samples exhibited amorphous nature as revealed by X-ray Diffraction studies. With the increase in BCZT content we have observed significant alteration in optical bandgap and Urbach energy. The tailoring of optical properties by tuning the structure was probed by Raman vibrational spectroscopy which confirmed the dominant role played by BCZT as a network modifier in these borate glasses. Concomitantly, these glass nanocomposites were found to be excellent UV absorbers.

  16. Spectroscopic investigations on Pr³+ and Nd³+ doped strontium-lithium-bismuth borate glasses.

    PubMed

    Rajesh, D; Balakrishna, A; Seshadri, M; Ratnakaram, Y C

    2012-11-01

    Spectroscopic investigations on different concentrations (0.1, 0.5, 1.0, 1.5 and 2.0mol%) of Pr(3+) and Nd(3+) doped strontium lithium bismuth borate glasses have been done. X-ray diffraction, SEM with EDS, absorption and luminescence spectra were recorded for all the glass matrices and analyzed. X-ray diffraction profiles and SEM images conformed amorphous nature of investigated glass samples. EDS spectra of host glass and Pr(3+)doped glass matrices gave information about the chemical composition of glass samples. From the absorption spectra of Pr(3+) and Nd(3+) ions, Judd-Ofelt (J-O) intensity parameters (Ω(λ),λ=2, 4 and 6) have been calculated and compared with other glass matrices. The emission characteristics such as radiative lifetimes (τ(R)), measured and calculated branching ratios (β) and stimulated emission cross-sections (σ(P)) have been obtained for the observed emission transitions of Pr(3+) and Nd(3+) ions in the above glass matrix for all the concentrations. From the emission spectra of Pr(3+) and Nd(3+) doped glass matrices, the effect of concentration on the quenching of intensity of (1)D(2)→(3)H(4) transition of Pr(3+) ion and (4)F(3/2)→(4)I(9/2), (4)I(11/2) and (4)I(13/2) transitions of Nd(3+) have been studied and discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. XRD and FTIR structural investigation of gadolinium-zinc-borate glass ceramics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Borodi, G.; Pascuta, P.; Dan, V.

    2013-11-13

    X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy measurements have been employed to investigate the (Gd{sub 2}O{sub 3}){sub x}⋅(B{sub 2}O{sub 3}){sub (60−x)}⋅(ZnO){sub 40} glass ceramics system, with 0 ≤ x ≤ 15 mol%. After heat treatment applied at 860 °C for 2 h, some structural changes were observed and new crystalline phases appeared in the structure of the samples. In these glass ceramics four crystalline phases were identified using powder diffraction files (PDF 2), namely ZnB{sub 4}O{sub 7}, Zn{sub 4}O(B{sub 6}O{sub 12}), Zn{sub 3}(BO{sub 3}){sub 2} and GdBO{sub 3}. From the XRD data, the average unit-cell parameter and themore » quantitative ratio of the crystallographic phases in the studied samples were evaluated. FTIR data revealed that the BO{sub 3}, BO{sub 4} and ZnO{sub 4} are the main structural units of these glass ceramics network. The compositional dependence of the different structural units which appear in the studied samples was followed.« less

  18. Elution characteristics of teicoplanin-loaded biodegradable borate glass/chitosan composite.

    PubMed

    Jia, Wei-Tao; Zhang, Xin; Zhang, Chang-Qing; Liu, Xin; Huang, Wen-Hai; Rahaman, Mohamed N; Day, Delbert E

    2010-03-15

    Local antibiotic delivery system has an advantage over systemic antibiotic for osteomyelitis treatment due to the delivery of high local antibiotic concentration while avoiding potential systemic toxicity. Composite biomaterials with multifunctional roles, consisting of a controlled antibiotic release, a mechanical (load-bearing) function, and the ability to promote bone regeneration, gradually become the most active area of investigation and development of local antibiotic delivery vehicles. In the present study, a composite of borate glass and chitosan (designated BG/C) was developed as teicoplanin delivery vehicle. The in vitro elution kinetics and antibacterial activity of teicoplanin released from BG/C composite as a function of immersion time were determined. Moreover, the pH changes of eluents and the bioactivity of the composite were characterized using scanning electron microscopy coupled with energy-dispersive spectroscopy and X-ray diffraction analysis. 2009 Elsevier B.V. All rights reserved.

  19. Optically stimulated luminescence of borate glasses containing magnesia, quicklime, lithium and potassium carbonates

    NASA Astrophysics Data System (ADS)

    Valença, J. V. B.; Silveira, I. S.; Silva, A. C. A.; Dantas, N. O.; Antonio, P. L.; Caldas, L. V. E.; d'Errico, F.; Souza, S. O.

    2017-11-01

    The OSL characteristics of three different borate glass matrices containing magnesia (LMB), quicklime (LCB) or potassium carbonate (LKB) were examined. Five different formulations for each composition were produced using a melt-quenching method and analyzed in terms of both dose-response curves and OSL shape decay. The samples were irradiated using a 90Sr/90Y beta source with doses up to 30 Gy. Dose-response curves were plotted using the initial OSL intensity as the chosen parameter. The OSL analysis showed that LKB glasses are the most sensitive to beta irradiation. For the most sensitive LKB composition, the irradiation process was also done using a 60Co gamma source in a dose range from 200 to 800 Gy. In all cases, no saturation was observed. A fitting process using a three-term exponential function was performed for the most sensitive formulations of each composition, which suggested a similar behavior in the OSL decay.

  20. Spectroscopic analysis of lead borate systems

    NASA Astrophysics Data System (ADS)

    Georgi, Akash Daniel; Ramesh, K. P.; Mallikarjunaiah, K. J.

    2018-04-01

    Oxide glass systems are interesting because of their bonding like bridging and non-bridging oxygens. Depending on the modifier, the B2O3 glass system can have various Boron-Oxygen network. It is found that, PbO modifies the borate network and increases the formation of penta and diborate groups. In this work, we investigated optical properties of Lead Borate glass systems (x PbO: (1-x) B2O3) with x varying from 30-85 mol % using UV-VIS Spectra and the corresponding band gap was estimated using Tauc relation and these systems behave like direct allowed band gap systems. These results show that, Eg decreases with the addition of lead content. Further the refractive index measurements also have been carried out at various wavelengths. Many correlation is found between the band gap and refractive index for different compositions. Using different theoretical models a best fit has been tried and Ravindra's relation is found to match with our experimental results.

  1. In vivo and in vitro studies of borate based glass micro-fibers for dermal repairing.

    PubMed

    Zhou, Jie; Wang, Hui; Zhao, Shichang; Zhou, Nai; Li, Le; Huang, Wenhai; Wang, Deping; Zhang, Changqing

    2016-03-01

    Full-thickness skin defects represent urgent clinical problem nowadays. Wound dressing materials are hotly needed to induce dermal reconstruction or to treat serious skin defects. In this study, the borate bioactive glass (BG) micro-fibers were fabricated and compared with the traditional material 45S5 Bioglass(®) (SiG) micro-fibers. The morphology, biodegradation and bioactivity of BG and SiG micro-fibers were investigated in vitro. The wound size reduction and angiogenic effects of BG and SiG micro-fibers were evaluated by the rat full-thickness skin defect model and Microfil technique in vivo. Results indicated that the BG micro-fibers showed thinner fiber diameter (1 μm) and better bioactivity than the SiG micro-fibers did. The ionic extracts of BG and SiG micro-fibers were not toxic to human umbilical vein endothelial cells (HUVECs). In vivo, the BG micro-fiber wound dressings obviously enhanced the formation of blood vessel, and resulted in a much faster wound size reduction than the SiG micro-fibers, or than the control groups, after 9 days application. The good skin defect reconstruction ability of BG micro-fibers contributed to the B element in the composition, which results in the better bioactivity and angiogenesis. As shown above, the novel bioactive borate glass micro-fibers are expected to provide a promising therapeutic alternative for dermal reconstruction or skin defect repair. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Ho3+-doped strontium-aluminium-bismuth-borate glasses for green light emission.

    PubMed

    Rajesh, D; Dhamodhara Naidu, M; Ratnakaram, Y C; Balakrishna, A

    2014-11-01

    Strontium-aluminium-bismuth-borate glasses (SAlBiB) doped with different concentrations of Ho(3+) were prepared using conventional melt quenching technique and their structural and optical properties investigated. X-ray diffraction and scanning electron microscopy analysis were used to study the structural properties. Optical properties were studied by measuring the optical absorption and visible luminescence spectra. The Judd-Ofelt (J-O) theory was applied to evaluate J-O intensity parameters, Ω(λ) (λ = 2, 4 and 6). Using J-O intensity parameters, radiative properties such as spontaneous transition probabilities (A(R)), branching ratios (β(R)) and radiative lifetimes (τ(R)) were determined. From the emission spectra, a strong green emission nearly at 549 nm corresponding to the transition, (5)S2 ((5)F4)→(5)I(8) was observed. Emission peak positions (λ(P)), effective bandwidths (Δλ(eff)) and stimulated emission cross-sections (σ(p)) were calculated for the observed emission transitions, (5)F3 →(5)I(8), (5)S2((5)F4)→(5)I(8) and (5)F5 →(5)I(8) of Ho(3+) in all the glass matrices. Chromaticity color coordinates were calculated using the emission spectra. The experimental results suggest that SAlBiB glass matrix with 1.5 mol% of Ho(3+) has better emission properties. Copyright © 2014 John Wiley & Sons, Ltd.

  3. Evaluation of the proliferation and differentiation behaviors of mesenchymal stem cells with partially converted borate glass containing different amounts of strontium in vitro.

    PubMed

    Zhu, Yi; Ouyang, Yuanming; Chang, Yi; Luo, Congfeng; Xu, Jun; Zhang, Changqing; Huang, Wenhai

    2013-04-01

    The objective of this study was to examine the proliferation and differentiation behaviors of different compositions of strontium-containing (from 0-12 mol%) borate glasses with mesenchymal stem cells (MSCs). The Cell Counting Kit-8 (CCK-8) assay revealed that after three days of culturing, the 6Sr group had the highest cell growth rate. Analysis of cell morphology revealed that cells proliferated well near the particles of the samples in all the groups on day 3. On day 7, cells in the 6Sr group demonstrated a higher proliferation rate than other 4 groups under the microscope. When performing the Live-Dead staining experiment, the 6Sr group had the least number of dead cells. Total DNA qualification indicated that the 6Sr group had a statistically higher concentration compared with the remaining groups. It was found that on day 7, compared with the 0Sr group, the core binding factor α1 (Cbfa1) mRNA expression level was significantly higher in the 6Sr, 9Sr and 12Sr groups. On day 14, compared with the 0Sr group, the bone sialoprotein (BSP) mRNA level was significantly higher in the 6Sr group. Additionally, on day 21, the 6Sr and 9Sr groups demonstrated higher osteocalcin (OCN) mRNA expression levels compared with the 0Sr group. In the alkaline phosphatase (ALP) activity test, on day 21, the 6Sr group presented a higher activity than the 0Sr group. Further, the number of mineralized nodules per unit in MSCs was measured by Alizarin Red S staining. The results showed that the 6Sr and 9Sr groups had the greatest number of mineralized nodules. Therefore, it could be concluded that borate glasses containing strontium oxide of 0, 3, 6, 9 and 12 mol% demonstrate a significant level of proliferation when interacting with MSCs. The borate glass containing 6 mol% strontium oxide had the greatest level of proliferation when cultured with MSCs. The borate glass containing 6 and 9 mol% strontium oxide facilitated an improved bone formation ability compared with the remaining

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

    NASA Astrophysics Data System (ADS)

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

    2017-11-01

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

  5. Structural and optical properties of lithium sodium borate glasses doped with Sm3+ ions

    NASA Astrophysics Data System (ADS)

    Dawaud, R. S. E. S.; Hashim, S.; Alajerami, Y. S. M.; Mhareb, M. H. A.; Maqableh, M. M.; Tamchek, N.

    2014-07-01

    Absorption and emission spectra of Sm3+ doped lithium sodium borate (LNB) have been reported. The samples were prepared by the melt-quenching technique and characterized by X-ray diffraction (XRD), diffraction thermal analysis (DTA), Fourier transforms infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM). From the thermo-grams spectrum, glass transition (Tg), crystallization (Tc) and melting temperatures (Tm) have been evaluated. Direct and indirect optical band gaps have been calculated based on the glasses UV absorption spectra. These glasses have shown strong nine absorption bands with hypersensitive transition at 1221 nm (6H5/2→4H3/2) and five emission bands for the transition at 4I7/2→6H13/2 (green color), 4I7/2→6H7/2 (orange color), 4I7/2→6H9/2 (orange color), 4I7/2→6H11/2 (red color) and 4I7/2→6H13/2 (red color) with performing an excitation of 400 nm. The oscillator strengths, refractive index, ions concentration, polaron radius and other parameters have been calculated for each dopant.

  6. Thermoluminescence properties of lithium magnesium borate glasses system doped with dysprosium oxide.

    PubMed

    Mhareb, M H A; Hashim, S; Ghoshal, S K; Alajerami, Y S M; Saleh, M A; Razak, N A B; Azizan, S A B

    2015-12-01

    We report the impact of dysprosium (Dy(3+)) dopant and magnesium oxide (MgO) modifier on the thermoluminescent properties of lithium borate (LB) glass via two procedures. The thermoluminescence (TL) glow curves reveal a single prominent peak at 190 °C for 0.5 mol% of Dy(3+). An increase in MgO contents by 10 mol% enhances the TL intensity by a factor of 1.5 times without causing any shift in the maximum temperature. This enhancement is attributed to the occurrence of extra electron traps created via magnesium and the energy transfer to trivalent Dy(3+) ions. Good linearity in the range of 0.01-4 Gy with a linear correlation coefficient of 0.998, fading as low as 21% over a period of 3 months, excellent reproducibility without oven annealing and tissue equivalent effective atomic numbers ~8.71 are achieved. The trap parameters, including geometric factor (μg), activation energy (E) and frequency factor (s) associated with LMB:Dy are also determined. These favorable TL characteristics of prepared glasses may contribute towards the development of Li2O-MgO-B2O3 radiation dosimeters. Copyright © 2015 John Wiley & Sons, Ltd.

  7. Tb3+ and Eu3+ doped zinc phosphate glasses for solid state lighting applications

    NASA Astrophysics Data System (ADS)

    Jha, Kaushal; Vishwakarma, Amit K.; Jayasimhadri, M.; Haranath, D.; Jang, Kiwan

    2018-04-01

    Tb3+ and Eu3+ doped zinc phosphate (ZP) glasses were prepared by conventional melt-quenching technique and their photoluminescence properties were investigated in detail. For, Tb3+ doped glasses the intense emission was at 545 nm corresponding to 5D4→7F5 transition under 377 nm n-UV excitation. The optimized concentration for Tb3+ doped zinc phosphate glass was 3 mol% and above this concentration quenching takes place. The Eu3+ doped zinc phosphate glass revealed intense emission at 613 nm attributed to the 5D0→7F2 transition under intense 392 nm n-UV excitation. The concentration quenching phenomenon was not observed in the Eu3+ doped ZP glasses. The CIE chromaticity coordinates for 3 mol% Tb3+ and 5 mol% Eu3+ doped ZP glasses were found to (0.283, 0.615) and (0.652, 0.331) lying in the green and red regions, respectively. The above mentioned results indicate that the prepared glass are suitable for application in the field of lighting and display devices.

  8. XRD and FTIR studies the effect of heat treatment and doping the transition metal oxide on LiNbO3 and LiNb3O8 nano-crystallite phases in lithium borate glass system.

    PubMed

    Kashif, Ismail; Soliman, Ashia A; Sakr, Elham M; Ratep, Asmaa

    2013-09-01

    Glasses of various compositions in the system 90 Li2B4O7-10 Nb2O5 mixed with T.M ions (where T.M is the transition metal) were prepared by quenching technique. Heat-treatment of the parent glasses was performed at 540, 570 and 620 °C, for 5 and 16 h. The glass structure evolution during the controlled crystallization was examined by XRD and FT-IR spectroscopy analysis. The crystalline phases present in the glass ceramics were identified via X-ray diffraction as a function of heat treatment. The FT-IR data propose for these glasses and heat-treated glass network structures mainly built by: di-, tri-, tetra-, penta-and ortho-borate groups. It was found that the quantitative evolution of these various borate species in the glass structures is influenced by the transition metal. A detailed discussion relating to the N4 evolution with the T.M content was made. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Characterization and in vitro bioactivity of zinc-containing bioactive glass and glass-ceramics.

    PubMed

    Du, Rui Lin; Chang, Jiang; Ni, Si Yu; Zhai, Wan Yin; Wang, Jun Ying

    2006-04-01

    Zinc-containing glass is prepared by the substitution of CaO in 58S bioactive glass with 0.5 and 4 wt% ZnO, and glass-ceramics are obtained by heat-treating the glass at 1,200 C. The bending strength and in vitro bioactivity of the glass and glass-ceramics are evaluated. The results indicate that Zn promotes the crystallization of SiO(2) and wollastonite in glass-ceramics, and proper crystallization can enhance the bending strength of the glass-ceramic. The in vitro results show that ZnO in glass retards the hydroxyapatite (HA) nucleation at the initial stage of simulated body fluid (SBF) soaking, but does not affect the growth of HA after long periods of soaking, and the ionic products of 58S4Z glass can stimulate the proliferation of osteoblast at certain concentrations. Osteoblasts attach well on both glass samples and glass-ceramic samples, but the high Si ion concentration released from glass samples restrains the proliferation of osteoblasts after 3 days of culture. In contrast, osteoblasts show good proliferation on glass-ceramic samples, and ZnO in glass-ceramics promotes the proliferation rate. The results in this study suggest that the glass and glass-ceramics with different ZnO content might be used as bioactive bone implant materials in different applications.

  10. The network formers role of gadolinium(III) ions in some zinc-borate glass ceramics

    NASA Astrophysics Data System (ADS)

    Bosca, Maria; Pop, Lidia; Pascuta, Petru

    2017-12-01

    EPR and magnetic susceptibility measurements were performed on glass ceramics from the (Gd2O3)x.(B2O3)(60-x).(ZnO)40 system, with 0 ≤ x ≤ 15 mol%, in order to determine the role of gadolinium ions on structural and magnetic properties. At low Gd2O3 contents (x ≤ 1 mol%) the EPR spectra show four resonance lines with effective g-values of ˜ 6, 4.8, 2.8 and 2, typical for Gd3+ ions uniformly distributed in the glass and glass ceramic samples. For higher contents of gadolinium ions (x ≥ 3 mol%) the EPR spectra are dominated by a single broad line centered at g ˜ 2, which can be due to the magnetic clusters containing Gd3+ ions. The magnetic susceptibility data show that the gadolinium ions are involved in superexchange interactions in all the investigated glass ceramics, being antiferromagnetically coupled.

  11. Identification of ε-Fe2O3 nano-phase in borate glasses doped with Fe and Gd

    NASA Astrophysics Data System (ADS)

    Ivanova, O. S.; Ivantsov, R. D.; Edelman, I. S.; Petrakovskaja, E. A.; Velikanov, D. A.; Zubavichus, Y. V.; Zaikovskii, V. I.; Stepanov, S. A.

    2016-03-01

    A new type of magnetic nanoparticles was revealed in borate glasses co-doped with low contents of iron and gadolinium. Structure and magnetic properties of the particles differ essentially from that of the α-Fe2O3, γ-Fe2O3, or Fe3O4 nanoparticles which were detected earlier in similar glass matrices. Transmission electron microscopy including STEM-HAADF and EDX, synchrotron radiation-based XRD, static magnetic measurements, magnetic circular dichroism, and electron magnetic resonance studies allow referring the nanoparticles to the iron oxide phase-ε-Fe2O3. Analysis of the data set has shown that it is Gd atoms that govern the process of nanoparticles' nucleation and its incorporation into the particles in different proportions can be used to adjust their magnetic and magneto-optical characteristics.

  12. Local distortion and EPR parameters of copper(II) in borate glasses

    NASA Astrophysics Data System (ADS)

    Kuang, Min-Quan; Wang, Li-Dan; Duan, Shu-Kai

    2017-12-01

    The EPR parameters (g and A tensors) of the paramagnetic Cu2+ sites in CaB4O7, LiCaBO3, Li2B4O7, KLiB4O7 glasses are well explained by utilizing the fourth-order perturbation formulas for 3 d9 ions in the tetragonally elongated octahedral [CuO6]10- clusters. The magnitude of the local distortion for the [CuO6]10- clusters suffering the Jahn-Teller effect is denoted by the relative elongation ratio ρ which is proportional to the ratio Δg///Δg⊥ (Δg//= g//-gs and Δg⊥ = g⊥-gs). The g isotropies giso (=(g//+2g⊥)/3) undergo an linear increase with the decline of the covalecny of the glass systems (i.e., the augment of the orbital reduction factor k). The signs of the hyperfine structure constants are determined by computing the quantitative contributions arising from the isotropic and anisotropic copper 3d-3s (4s) orbital admixtures indicated by the core polarization constant κ and the reduction factor H, respectively. The above correlations are proved to be available for analogous borate glasses doping with copper ions, e.g., MRbB4O7 (M = Li, Na and K), 90M2B4O7·9PbO·CuO (M = Li, Na and K), 10MO·30ZnO·60B2O3 (M = Mg, Ca and Sr) and xLi2O·(30-x)Na2O·69.5B2O3 (5 ≤ x ≤ 25 mol%), and all the results are discussed.

  13. Effects of copper on the preparation and characterization of Na-Ca-P borate glasses.

    PubMed

    Shailajha, S; Geetha, K; Vasantharani, P; Sheik Abdul Kadhar, S P

    2015-03-05

    Glasses in the system Na2O-CaO-B2O3-P2O5: CuO have been prepared by melt quenching at 1200°C and rapidly cooling at room temperature. The structural, optical and thermal properties have been investigated using X-ray diffraction (XRD), ultraviolet-visible (UV-VIS) spectroscopy, thermogravimetric-differential thermal analysis (TG-DTA), Fourier transform infrared (FTIR) spectroscopy, high resolution scanning electron microscopy (HRSEM) with energy dispersive X-ray (EDX) spectroscopy and high resolution transmission electron microscope (HRTEM) with energy dispersive X-ray (EDAX). The amorphous and crystalline nature of these samples was verified by XRD. Glass transition, crystallization and thermal stability were determined by TG-DTA investigations. Direct optical energy band gaps before and after doping with different percents of copper oxide were evaluated from 4.81eV to 2.99eV indicated the role of copper in the glassy matrix by UV spectra. FTIR spectrum reveals characteristic absorption bands due to various groups of triangular and tetrahedral borate network. Due to the amorphous nature, the particles like agglomerates on the glass surface were investigated by the HRSEM analysis. The crystalline nature of the samples in XRD is confirmed by SAED pattern using HRTEM. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Thermo-optical characteristics and concentration quenching effects in Nd3+doped yttrium calcium borate glasses

    NASA Astrophysics Data System (ADS)

    Santos, D. R. S.; Santos, C. N.; de Camargo, A. S. S.; Silva, W. F.; Santos, W. Q.; Vermelho, M. V. D.; Astrath, N. G. C.; Malacarne, L. C.; Li, M. S.; Hernandes, A. C.; Ibanez, A.; Jacinto, C.

    2011-03-01

    In this work we present a comprehensive study of the spectroscopic and thermo-optical properties of a set of samples with composition xNd2O3-(5-x)Y2O3-40CaO-55B2O3 (0 ≤ x ≤ 1.0 mol%). Their fluorescence quantum efficiency (η) values were determined using the thermal lens technique and the dependence on the ionic concentration was analyzed in terms of energy transfer processes, based on the Förster-Dexter model of multipolar ion-ion interactions. A maximum η = 0.54 was found to be substantially higher than for yttrium aluminoborate crystals and glasses with comparable Nd3+ content. As for the thermo-optical properties of yttrium calcium borate, they are comparable to other well-known laser glasses. The obtained energy transfer microparameters and the weak dependence of η on the Nd3+ concentration with a high optimum Nd3+ concentration put this system as a strong candidate for photonics applications.

  15. Theoretical studies of the local structures and spin Hamiltonian parameters for Cu2+ in alkaline earth alumino borate glasses

    NASA Astrophysics Data System (ADS)

    Guo, Jia-Xing; Wu, Shao-Yi; Kuang, Min-Quan; Peng, Li; Wu, Li-Na

    2018-01-01

    The local structures and spin Hamiltonian parameters are theoretically studied for Cu2+ in alkaline earth alumino borate (XAB, X = Mg, Ca and Sr) glasses by using the perturbation calculations for tetragonally elongated octahedral 3d9 groups. The [CuO6]10- groups are subject to the large relative tetragonal elongation ratios of 15.4%, 13.4% and 13.0% for MgAB, CaAB and SrAB glasses, respectively, arising from the Jahn-Teller effect. The decreasing cubic field parameter Dq, orbital reduction factor k and relative elongation ratio with the increase of the radius of alkaline earth ion X from Mg to Ca or Sr are analyzed for the studied systems in a uniform way.

  16. Chemical composition and mineralogy of borate from Rio Grande deposit, Uyuni (Bolivia) as raw materials for industrial applications

    NASA Astrophysics Data System (ADS)

    Guillen Vargas, Julio; Arancibia, Jony Roger Hans; Alfonso, Pura; Garcia-Valles, Maite; Parcerisa, David; Martinez, Salvador

    2014-05-01

    Bolivia has large tailings as a result of the historic and present-day Sn mining activity developed extensively in that country. Tailings produced in these mining activities have an appropriate composition to reprocess them and make silicate glass and glass-ceramics, obtaining the valorization of wastes and reducing the visual and chemical impact. Reprocessing the wastes to make glass and glass-ceramics prevents the leaching of heavy metals from those wastes because they are retained in the structure of the glass. Furthermore, an option to increase the economic value of these glasses is the introduction of boron and other additives to produce borosilicate glass. In this study a characterization of the Rio Grande borate deposit for its use in the manufacture of borosilicate glass is presented. Mineralogy was determined by X-ray diffraction (XRD), and Fourier transforms infrared spectroscopy (FTIR); textures were observed by scanning electron microscopy (SEM) and chemical composition was determined by inductively coupled plasma mass spectrometry (ICP-MS). The Rio Grande borate deposit is located in an area of about 50 km2 close to the south of the Salar of Uyuni, in the Río Grande de Lípez Delta. Borates occur in the contact between fluvio-deltaic and lacustrine sediments from water raising the surface by capillarity. The borates crop out in an extent area but towards the west they are covered by fluvio-deltaic sediments, which can be up to 2 m thick. These borates occur as lenses 50-100 m in diameter and layers up to 1 m thick. They usually form brittle nodules with a cotton-ball texture. Chemical composition of the Rio Grande borates is CaO, 11.82-13.83 wt%; Na2O, 13.50-19.35 wt%; K2O, 0.05- 1.04 wt%; MgO, 0.42-1.46 wt%; B2O3, 36.21-42.60 wt%; SiO2, up to 0.53 wt% and SO2, up to 0.60 wt%. Trace elements are low: Sr content is between 151-786 ppm, Al 12-676 ppm, Mn between 1-17 ppm, As 2-10 ppm and Fe between 9-376 ppm. The most abundant borate mineral in this

  17. Negative induced absorption and negative index of refraction for iron doped potash-alumina-borate glasses subjected to thermal-radiation treatment

    NASA Astrophysics Data System (ADS)

    Salakhitdinov, Amritdin; Ibragimova, Elvira; Salakhitdinova, Maysara

    2018-02-01

    This work experimentally revealed, that 60Co-gamma-irradiation of potash-alumina-borate glasses doped with 1 and 2 mass% of iron oxide to the dose of 1.7 MR in the temperature range of 150-300 °C induced differential optical density changes within - 6 ≤ Δ D ≤ 0 in the wave length range of 300-350 nm, which is characteristic for meta-material. Calculations have shown that variation of optical refraction index within - 0.05 ≤ Δ n ω ≤ 0.05 due to microstructure transformation causes changes in the differential absorption index of the glass - 0.5 < Δ α ω < 0.55.

  18. Nano crystalline Bi2(VO5) phases in lithium bismuth borate glasses containing mixed vanadium-nickel oxides

    NASA Astrophysics Data System (ADS)

    Yadav, Arti; Khasa, S.; Dahiya, M. S.; Agarwal, A.

    2016-05-01

    Glass composition 7V2O5.23Li2O.20Bi2O3.50B2O3 and x(2NiO.V2O5).(30-x)Li2O.20Bi2O3.50B2O3, x=0, 2, 5, 7 and 10, were produced by conventional melt quenching technique. The quenched amorphous glass samples were annealed at temperatures 400°C and 500°C for 6 hours. The Bi2(VO5) crystallite were grown in all prepared glass matrix. Tn vanadium lithium bismuth borate glass (annealed), the some phrase of V2O5-crystal were observed along with the nano crystalline Bi2(VO5) phase. The sharp peaks in FTTR spectra of all annealed compositions were also compatible with the XRD diffraction peaks of the system under investigation. Average crystalline size (D) of the Bi2(VO5) nano-crystallite was ~30nm for samples annealed at 400°C and ~42nm for samples annealed at 500°C. Lattice parameter and the lattice strain for all the samples was also calculated corresponding to the (113) plane of Bi2(VO5) crystallite.

  19. Dosimetric properties of germanium doped calcium borate glass subjected to 6 MV and 10 MV X-ray irradiations

    NASA Astrophysics Data System (ADS)

    Tengku Kamarul Bahri, T. N. H.; Wagiran, H.; Hussin, R.; Saeed, M. A.; Hossain, I.; Ali, H.

    2014-10-01

    Germanium doped calcium borate glasses are investigated in term of thermoluminescence properties to seek their possibility to use as glass radiation dosimeter. The samples were exposed to 6 MV, and 10 MV photon beams in a dose range of 0.5-4.0 Gy. There is a single and broad thermoluminescence glow curve that exhibits its maximum intensity at about 300 °C. Linear dose response behavior has been found in this dose range for the both photon energies. Effective atomic number, TL sensitivity, and reproducibility have also been studied. It is found that the sensitivity of germanium doped sample at 6 MV is only 1.28% and it is superior to the sensitivity at 10 MV. The reproducibility of germanium doped sample is good with a percentage of relative error less than 10%. The results indicate that this glass has a potential to be used as a radiation dosimetry, especially for application in radiotherapy.

  20. Scintillation properties of phosphate-borate-fluoride glass doped with Tb3+/Pr3+

    NASA Astrophysics Data System (ADS)

    Valiev, D.; Stepanov, S.; Polisadova, E.; Yao, G.

    2018-06-01

    Scintillation glass doped with Tb3+ and Pr3+ ions with different concentrations were prepared by the melt-quenching method. Optical, photoluminescence and decay kinetic characteristics of the pulse cathodoluminescence (PCL) were investigated. It was shown that the absorption coefficient of the induced absorption in the visible range of the spectrum decreases significantly with the increase of the Pr2O3 content starting from 0.2 to 1 wt%. There was the difference in the luminescence spectra of the glass at a selective and non-selective type of excitation. The "green" emission (λem= 542 nm, 5D4→7F5 radiative transition of Tb3+ ions) was excited an electron beam. The "red" emission (λem= 600 nm, 3P0→3H6 radiative transition of Pr3+ ion) was observed under selective excitation action (λexc= 450 nm). It was demonstrated that decreasing of intensity the main bands of Tb3+ ions at 487, 544, 622 nm connected with increases of concentration Pr3+ ions. The luminescence decay time of terbium ions at 487, 544, 622 nm emission bands depend on Pr3+ concentration. The tendency of reducing the luminescence decay time in the main luminescence bands of Tb3+ ions at increasing the Pr3+ concentration was presented. The results showed that Tb3+/ Pr3+ co-doped phosphate-borate-fluoride glasses are promising non-crystalline scintillation materials.

  1. Revival of nitrogen-containing bisphosphonate-induced inhibition of osteoclastogenesis and osteoclast function by water-soluble microfibrous borate glass.

    PubMed

    Yuan, He; Niu, Li-Na; Jiao, Kai; Pei, Dan-Dan; Pramanik, Chandrani; Li, Ji-Yao; Messer, Regina; Kumar, Satish; Pashley, David H; Tay, Franklin R

    2016-02-01

    Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a serious skeletal complication associated with the long-term oral or intravenous use of nitrogen-containing bisphosphonates (N-BPs). Here, we investigated the effects of an ionic cocktail prepared from water-soluble microfibrous borate glass on neutralizing the inhibitory effects of two heterocyclic N-BPs, risedronate or zoledronic acid, on osteoclastogenesis, apoptosis of differentiated osteoclasts and osteoclast function. Cell growth and proliferation assays were first performed on RAW 264.7 cells to optimize the concentrations of the ionic cocktail and N-BPs to be used for static cell culture. The pre-osteoclasts were then stimulated with RANKL to differentiate into osteoclasts. The effects of the ionic cocktail and N-BPs on osteoclast differentiation, apoptosis and function were subsequently examined using 3 series of experiments conducted at the gene, protein, morphological and functional levels. After concentration optimization, the ionic cocktail was found to partially reverse N-BP-induced inhibition of osteoclastogenesis, stimulation of osteoclasts apoptosis and reduction of osteoclast resorptive activity. Ultrastructural examination of osteoclasts that had been exposed to either N-BP identified classical features of late apoptosis and secondary necrosis, while osteoclasts exposed simultaneously to the concentration-optimized ionic cocktail and N-BPs exhibited only signs of early apoptosis that were possibly reversible. Taken together, the results of the 4 series of experiments indicate that the ionic cocktail produced from dissolution of borate glass dressings has the potential to rescue the adverse effects of heterocyclic N-BPs on osteoclast differentiation and function. These results warrant further confirmation using dynamic cell culture and small animal BRONJ models. Long-term oral and intravenous use of nitrogen-containing bisphosphonates (N-BPs) may result in bisphosphonate

  2. Biological Impact of Bioactive Glasses and Their Dissolution Products.

    PubMed

    Hoppe, Alexander; Boccaccini, Aldo R

    2015-01-01

    For many years, bioactive glasses (BGs) have been widely considered for bone tissue engineering applications due to their ability to bond to hard as well as soft tissue (a property termed bioactivity) and for their stimulating effects on bone formation. Ionic dissolution products released during the degradation of the BG matrix induce osteogenic gene expression leading to enhanced bone regeneration. Recently, adding bioactive metallic ions (e.g. boron, copper, cobalt, silver, zinc and strontium) to silicate (or phosphate and borate) glasses has emerged as a promising route for developing novel BG formulations with specific therapeutic functionalities, including antibacterial, angiogenic and osteogenic properties. The degradation behaviour of BGs can be tailored by adjusting the glass chemistry making these glass matrices potential carrier systems for controlled therapeutic ion release. This book chapter summarises the fundamental aspects of the effect of ionic dissolution products from BGs on osteogenesis and angiogenesis, whilst discussing novel BG compositions with controlled therapeutic ion release. © 2015 S. Karger AG, Basel.

  3. A Novel Injectable Borate Bioactive Glass Cement as an Antibiotic Delivery Vehicle for Treating Osteomyelitis

    PubMed Central

    Cui, Xu; Gu, Yi-Fei; Jia, Wei-Tao; Rahaman, Mohamed N.; Wang, Yang; Huang, Wen-Hai; Zhang, Chang-Qing

    2014-01-01

    Background A novel injectable cement composed of chitosan-bonded borate bioactive glass (BG) particles was evaluated as a carrier for local delivery of vancomycin in the treatment of osteomyelitis in a rabbit tibial model. Materials and Methods The setting time, injectability, and compressive strength of the borate BG cement, and the release profile of vancomycin from the cement were measured in vitro. The capacity of the vancomycin-loaded BG cement to eradicate methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis in rabbit tibiae in vivo was evaluated and compared with that for a vancomycin-loaded calcium sulfate (CS) cement and for intravenous injection of vancomycin. Results The BG cement had an injectability of >90% during the first 3 minutes after mixing, hardened within 30 minutes and, after hardening, had a compressive strength of 18±2 MPa. Vancomycin was released from the BG cement into phosphate-buffered saline for up to 36 days, and the cumulative amount of vancomycin released was 86% of the amount initially loaded into the cement. In comparison, vancomycin was released from the CS cement for up 28 days and the cumulative amount released was 89%. Two months post-surgery, radiography and microbiological tests showed that the BG and CS cements had a better ability to eradicate osteomyelitis when compared to intravenous injection of vancomycin, but there was no significant difference between the BG and CS cements in eradicating the infection. Histological examination showed that the BG cement was biocompatible and had a good capacity for regenerating bone in the tibial defects. Conclusions These results indicate that borate BG cement is a promising material both as an injectable carrier for vancomycin in the eradication of osteomyelitis and as an osteoconductive matrix to regenerate bone after the infection is cured. PMID:24427311

  4. A novel injectable borate bioactive glass cement as an antibiotic delivery vehicle for treating osteomyelitis.

    PubMed

    Ding, Hao; Zhao, Cun-Ju; Cui, Xu; Gu, Yi-Fei; Jia, Wei-Tao; Rahaman, Mohamed N; Wang, Yang; Huang, Wen-Hai; Zhang, Chang-Qing

    2014-01-01

    A novel injectable cement composed of chitosan-bonded borate bioactive glass (BG) particles was evaluated as a carrier for local delivery of vancomycin in the treatment of osteomyelitis in a rabbit tibial model. The setting time, injectability, and compressive strength of the borate BG cement, and the release profile of vancomycin from the cement were measured in vitro. The capacity of the vancomycin-loaded BG cement to eradicate methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis in rabbit tibiae in vivo was evaluated and compared with that for a vancomycin-loaded calcium sulfate (CS) cement and for intravenous injection of vancomycin. The BG cement had an injectability of >90% during the first 3 minutes after mixing, hardened within 30 minutes and, after hardening, had a compressive strength of 18 ± 2 MPa. Vancomycin was released from the BG cement into phosphate-buffered saline for up to 36 days, and the cumulative amount of vancomycin released was 86% of the amount initially loaded into the cement. In comparison, vancomycin was released from the CS cement for up 28 days and the cumulative amount released was 89%. Two months post-surgery, radiography and microbiological tests showed that the BG and CS cements had a better ability to eradicate osteomyelitis when compared to intravenous injection of vancomycin, but there was no significant difference between the BG and CS cements in eradicating the infection. Histological examination showed that the BG cement was biocompatible and had a good capacity for regenerating bone in the tibial defects. These results indicate that borate BG cement is a promising material both as an injectable carrier for vancomycin in the eradication of osteomyelitis and as an osteoconductive matrix to regenerate bone after the infection is cured.

  5. Sensitivity of novel silicate and borate-based glass structures on in vitro bioactivity and degradation behaviour.

    PubMed

    Mancuso, Elena; Bretcanu, Oana; Marshall, Martyn; Dalgarno, Kenneth W

    2017-10-15

    Three novel glass compositions, identified as NCL2 (SiO 2 -based), NCL4 (B 2 O 3 -based) and NCL7 (SiO 2 -based), along with apatite-wollastonite (AW) were processed to form sintered dense pellets, and subsequently evaluated for their in vitro bioactive potential, resulting physico-chemical properties and degradation rate. Microstructural analysis showed the carbonated hydroxyapatite (HCA) precipitate morphology following SBF testing to be composition-dependent. AW and the NCL7 formulation exhibited greater HCA precursor formation than the NCL2 and NCL4-derived pellets. Moreover, the NCL4 borate-based samples showed the highest biodegradation rate; with silicate-derived structures displaying the lowest weight loss after SBF immersion. The results of this study suggested that glass composition has significant influence on apatite-forming ability and also degradation rate, indicating the possibility to customise the properties of this class of materials towards the bone repair and regeneration process.

  6. Silicate, borosilicate, and borate bioactive glass scaffolds with controllable degradation rate for bone tissue engineering applications. II. In vitro and in vivo biological evaluation.

    PubMed

    Fu, Qiang; Rahaman, Mohamed N; Bal, B Sonny; Bonewald, Lynda F; Kuroki, Keiichi; Brown, Roger F

    2010-10-01

    In Part I, the in vitro degradation of bioactivAR52115e glass scaffolds with a microstructure similar to that of human trabecular bone, but with three different compositions, was investigated as a function of immersion time in a simulated body fluid. The glasses consisted of a silicate (13-93) composition, a borosilicate composition (designated 13-93B1), and a borate composition (13-93B3), in which one-third or all of the SiO2 content of 13-93 was replaced by B2O3, respectively. This work is an extension of Part I, to investigate the effect of the glass composition on the in vitro response of osteogenic MLO-A5 cells to these scaffolds, and on the ability of the scaffolds to support tissue infiltration in a rat subcutaneous implantation model. The results of assays for cell viability and alkaline phosphatase activity showed that the slower degrading silicate 13-93 and borosilicate 13-93B1 scaffolds were far better than the borate 13-93B3 scaffolds in supporting cell proliferation and function. However, all three groups of scaffolds showed the ability to support tissue infiltration in vivo after implantation for 6 weeks. The results indicate that the required bioactivity and degradation rate may be achieved by substituting an appropriate amount of SiO2 in 13-93 glass with B2O3, and that these trabecular glass scaffolds could serve as substrates for the repair and regeneration of contained bone defects. Copyright 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

  7. Evaluation of the gamma radiation shielding parameters of bismuth modified quaternary glass system

    NASA Astrophysics Data System (ADS)

    Kaur, Parminder; Singh, K. J.; Thakur, Sonika

    2018-05-01

    Glasses modified with heavy metal oxides (HMO) are an interesting area of research in the field of gamma-ray shielding. Bismuth modified lithium-zinc-borate glasses have been studied whereby bismuth oxide is added from 0 to 50 mol%. The gamma ray shielding properties of the glasses were evaluated at photon energy 662 keV with the help of XMuDat computer program by using the Hubbell and Seltzer database. Various gamma ray shielding parameters such as attenuation coefficient, shield thickness in terms of half and tenth value layer, effective atomic number have been studied in this work. A useful comparison of this glass system has been made with standard radiation shielding concretes viz. ordinary, barite and iron concrete. The glass samples containing 20 to 50 mol% bismuth oxide have shown better gamma ray shielding properties and hence have the potential to become good radiation absorbers.

  8. Conversion of melt-derived microfibrous borate (13-93B3) and silicate (45S5) bioactive glass in a simulated body fluid.

    PubMed

    Liu, Xin; Rahaman, Mohamed N; Day, Delbert E

    2013-03-01

    Microfibrous bioactive glasses are showing a considerable capacity to heal soft tissue wounds, but little information is available on the mechanism of healing. In the present study, the conversion of microfibrous borate bioactive glass (diameter = 0.2-5 μm) with the composition designated 13-93B3 (5.5 Na2O, 11.1 K2O, 4.6 MgO, 18.5 CaO, 3.7 P2O5, 56.6 B2O3 wt%) was evaluated in vitro as a function of immersion time in a simulated body fluid (SBF) at 37 °C using structural and chemical techniques. Silicate 45S5glass microfibers (45 SiO2, 24.5 Na2O, 24.5 CaO, 6 P2O5 wt%) were also studied for comparison. Microfibrous 13-93B3 glass degraded almost completely and converted to a calcium phosphate material within 7-14 days in SBF, whereas >85 % of the silica remained in the 45S5 microfibers, forming a silica gel phase. An amorphous calcium phosphate (ACP) product that formed on the 13-93B3 microfibers crystallized at a slower rate to hydroxyapatite (HA) when compared to the ACP that formed on the 45S5 fibers. For immersion times >3 days, the 13-93B3 fibers released a higher concentration of Ca into the SBF than the 45S5 fibers. The fast and more complete degradation, slow crystallization of the ACP product, and higher concentration of dissolved Ca in SBF could contribute to the capacity of the microfibrous borate 13-93B3 glass to heal soft tissue wounds.

  9. Wound dressings composed of copper-doped borate bioactive glass microfibers stimulate angiogenesis and heal full-thickness skin defects in a rodent model.

    PubMed

    Zhao, Shichang; Li, Le; Wang, Hui; Zhang, Yadong; Cheng, Xiangguo; Zhou, Nai; Rahaman, Mohamed N; Liu, Zhongtang; Huang, Wenhai; Zhang, Changqing

    2015-01-01

    There is a need for better wound dressings that possess the requisite angiogenic capacity for rapid in situ healing of full-thickness skin wounds. Borate bioactive glass microfibers are showing a remarkable ability to heal soft tissue wounds but little is known about the process and mechanisms of healing. In the present study, wound dressings composed of borate bioactive glass microfibers (diameter = 0.4-1.2 μm; composition 6Na2O, 8K2O, 8MgO, 22CaO, 54B2O3, 2P2O5; mol%) doped with 0-3.0 wt.% CuO were created and evaluated in vitro and in vivo. When immersed in simulated body fluid, the fibers degraded and converted to hydroxyapatite within ∼7 days, releasing ions such as Ca, B and Cu into the medium. In vitro cell culture showed that the ionic dissolution product of the fibers was not toxic to human umbilical vein endothelial cells (HUVECs) and fibroblasts, promoted HUVEC migration, tubule formation and secretion of vascular endothelial growth factor (VEGF), and stimulated the expression of angiogenic-related genes of the fibroblasts. When used to treat full-thickness skin defects in rodents, the Cu-doped fibers (3.0 wt.% CuO) showed a significantly better capacity to stimulate angiogenesis than the undoped fibers and the untreated defects (control) at 7 and 14 days post-surgery. The defects treated with the Cu-doped and undoped fibers showed improved collagen deposition, maturity and orientation when compared to the untreated defects, the improvement shown by the Cu-doped fibers was not markedly better than the undoped fibers at 14 days post-surgery. These results indicate that the Cu-doped borate glass microfibers have a promising capacity to stimulate angiogenesis and heal full-thickness skin defects. They also provide valuable data for understanding the role of the microfibers in healing soft tissue wounds. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Optical, Structural, and Thermal Properties of Cerium-Doped Zinc Borophosphate Glasses.

    PubMed

    Choi, Su-Yeon; Ryu, Bong-Ki

    2015-11-01

    In this study, we verify the relationship between the optical properties and structure of cerium-doped zinc borophosphate glasses that have concurrence of non-bridging oxygen (NBO) and bridging oxygen (BO), Ce3+ and Ce4+, and BO3 structure and BO4 structure. We prepared cerium-doped zinc borophosphate glass with various compositions, given by xCeO2-(100-x)[50ZnO-10B2O3 -40P2O5] (x = 1 mol% to 6 mol%), and analyzed their optical band energy, glass transition temperature, crystallization temperature, density, and molar volume. Some of the techniques used for analysis were Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). In the investigated glasses, the optical band gap energy decreased from 3.28 eV to 1.73 eV. From these results, we can deduce the changes when transitions occur from BO to NBO, from Ce3+ to Ce4+, and from the BO3 structure to the BO4 structure with increasing CeO2 content using FT-IR and XPS analysis. We also verified the changes in structural and physical properties from quantitative properties such as glass transition temperature, crystallization temperature, density, and molar volume.

  11. Silica-Based and Borate-Based, Titania-Containing Bioactive Coatings Characterization: Critical Strain Energy Release Rate, Residual Stresses, Hardness, and Thermal Expansion.

    PubMed

    Rodriguez, Omar; Matinmanesh, Ali; Phull, Sunjeev; Schemitsch, Emil H; Zalzal, Paul; Clarkin, Owen M; Papini, Marcello; Towler, Mark R

    2016-12-01

    Silica-based and borate-based glass series, with increasing amounts of TiO₂ incorporated, are characterized in terms of their mechanical properties relevant to their use as metallic coating materials. It is observed that borate-based glasses exhibit CTE (Coefficient of Thermal Expansion) closer to the substrate's (Ti6Al4V) CTE, translating into higher mode I critical strain energy release rates of glasses and compressive residual stresses and strains at the coating/substrate interface, outperforming the silica-based glasses counterparts. An increase in the content of TiO₂ in the glasses results in an increase in the mode I critical strain energy release rate for both the bulk glass and for the coating/substrate system, proving that the addition of TiO₂ to the glass structure enhances its toughness, while decreasing its bulk hardness. Borate-based glass BRT3, with 15 mol % TiO₂ incorporated, exhibits superior properties overall compared to the other proposed glasses in this work, as well as 45S5 Bioglass ® and Pyrex.

  12. Silica-Based and Borate-Based, Titania-Containing Bioactive Coatings Characterization: Critical Strain Energy Release Rate, Residual Stresses, Hardness, and Thermal Expansion

    PubMed Central

    Rodriguez, Omar; Matinmanesh, Ali; Phull, Sunjeev; Schemitsch, Emil H.; Zalzal, Paul; Clarkin, Owen M.; Papini, Marcello; Towler, Mark R.

    2016-01-01

    Silica-based and borate-based glass series, with increasing amounts of TiO2 incorporated, are characterized in terms of their mechanical properties relevant to their use as metallic coating materials. It is observed that borate-based glasses exhibit CTE (Coefficient of Thermal Expansion) closer to the substrate’s (Ti6Al4V) CTE, translating into higher mode I critical strain energy release rates of glasses and compressive residual stresses and strains at the coating/substrate interface, outperforming the silica-based glasses counterparts. An increase in the content of TiO2 in the glasses results in an increase in the mode I critical strain energy release rate for both the bulk glass and for the coating/substrate system, proving that the addition of TiO2 to the glass structure enhances its toughness, while decreasing its bulk hardness. Borate-based glass BRT3, with 15 mol % TiO2 incorporated, exhibits superior properties overall compared to the other proposed glasses in this work, as well as 45S5 Bioglass® and Pyrex. PMID:27916951

  13. Evaluation of injectable strontium-containing borate bioactive glass cement with enhanced osteogenic capacity in a critical-sized rabbit femoral condyle defect model.

    PubMed

    Zhang, Yadong; Cui, Xu; Zhao, Shichang; Wang, Hui; Rahaman, Mohamed N; Liu, Zhongtang; Huang, Wenhai; Zhang, Changqing

    2015-02-04

    The development of a new generation of injectable bone cements that are bioactive and have enhanced osteogenic capacity for rapid osseointegration is receiving considerable interest. In this study, a novel injectable cement (designated Sr-BBG) composed of strontium-doped borate bioactive glass particles and a chitosan-based bonding phase was prepared and evaluated in vitro and in vivo. The bioactive glass provided the benefits of bioactivity, conversion to hydroxyapatite, and the ability to stimulate osteogenesis, while the chitosan provided a cohesive biocompatible and biodegradable bonding phase. The Sr-BBG cement showed the ability to set in situ (initial setting time = 11.6 ± 1.2 min) and a compressive strength of 19 ± 1 MPa. The Sr-BBG cement enhanced the proliferation and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells in vitro when compared to a similar cement (BBG) composed of chitosan-bonded borate bioactive glass particles without Sr. Microcomputed tomography and histology of critical-sized rabbit femoral condyle defects implanted with the cements showed the osteogenic capacity of the Sr-BBG cement. New bone was observed at different distances from the Sr-BBG implants within eight weeks. The bone-implant contact index was significantly higher for the Sr-BBG implant than it was for the BBG implant. Together, the results indicate that this Sr-BBG cement is a promising implant for healing irregularly shaped bone defects using minimally invasive surgery.

  14. Optical and physical properties of samarium doped lithium diborate glasses

    NASA Astrophysics Data System (ADS)

    Hanumantharaju, N.; Sardarpasha, K. R.; Gowda, V. C. Veeranna

    2018-05-01

    Sm3+ doped lithium di-borate glasses with composition 30Li2O-60B2O3-(10-x) PbO, (where 0 < x < 2 mole. %) were prepared by melt quenching method. The addition of modifier oxide to vitreous B2O3 modifies the glass network by converting three coordinated trigonal boron units (BO3) to weaker anionic four coordinated tetrahedral borons (BO4). The decrease in density and increase in molar volume with samarium ion content indicates the openness of the glass structure. The gradual increase in average separation of boron-boron atoms with VmB clearly indicates deterioration of borate glass network, which in turn leads to decrease in the oxygen packing density. The replacements of Sm2O3 for PbO depolymerise the chain structure and that would increase the concentration of non-bridging oxygens. The marginal increase of optical band gap energy after 1.0 mol.% of Sm2O3 is explained by considering the structural modification in lead-borate. The influence of Sm3+ ion on physical and optical properties in lithium-lead-borate glasses is investigated and the results were discussed in view of the structure of borate glass network.

  15. Borates

    USGS Publications Warehouse

    Crangle, R.D.

    2013-01-01

    Four minerals represent 90 percent of the borates used by industry worldwide — the sodium borates (tincal and kernite), calcium borate (colemanite) and the sodium-calcium borate (ulexite). Borax is a white crystalline substance, chemically known as sodium tetraborate decahydrate, and is found naturally as the mineral tincal. Boric acid is a colorless crystalline solid sold in technical, national formulary and special quality grades as granules or powder and marketed most often as anhydrous boric acid. Deposits of borates are associated with volcanic activity and arid climates, with the largest economically viable deposits located in the Mojave Desert of the United States near Boron, CA, the Alpide belt in southern Asia and the Andean belt of South America.

  16. Crystal nucleation in lithium borate glass

    NASA Technical Reports Server (NTRS)

    Smith, Gary L.; Neilson, George F.; Weinberg, Michael C.

    1988-01-01

    Crystal nucleation measurements were made on three lithium borate compositions in the vicinity of Li2O-2Br2O3. All nucleation measurements were performed at 500 C. Certain aspects of the nucleation behavior indicated (tentatively) that it proceeded by a homogeneous mechanism. The steady state nucleation rate was observed to have the largest value when the Li2O concentration was slightly in excess of the diborate composition. The change in nucleation rate with composition is controlled by the variation of viscosity as well as the change in free energy with composition. The variation of nucleation rate is explained qualitatively in these terms.

  17. The peculiarity of the formation of zinc films on a glass substrate

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tomaev, V. V., E-mail: tvaza@mail.ru; Saint Petersburg Mining University, Russia, 199106, St. Petersburg, V.O., 21-st line, 2; Polishchuk, V. A., E-mail: vpvova2010@yandex.ru

    2016-06-17

    Thin Nanocrystalline films of the zinc have been fabricated by thermal spraying on the glass substrate. Morphologies and structure of the films had been investigated by the methods X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). It is found that the surface of the films has a different types of the nanocrystals zinc. Were detected intergrowths of two or more the nanocrystals, hexagonal shape. Using the theory of homogeneous and heterogeneous nucleation of a new phase, had been evaluated the geometrical and thermodynamic parameters nanocrystals zinc.

  18. Effect of Bi2O3 on spectroscopic and structural properties of Er3+ doped cadmium bismuth borate glasses.

    PubMed

    Sanghi, S; Pal, I; Agarwal, A; Aggarwal, M P

    2011-12-01

    Glasses with composition 20CdO·xBi(2)O(3)·(79.5-x)B(2)O(3) (15≤x≤35, x in mol%) containing 0.5 mol% of Er(3+) ions were prepared by melt-quench technique (1150°C in air). The amorphous nature of the glasses was confirmed by X-ray diffraction. The spectroscopic properties of the glasses were investigated using optical absorption spectra and fluorescence spectra. The phenomenological Judd-Ofelt intensity parameters Ω(λ) (λ=2, 4, 6) were determined from the spectral intensities of absorption bands in order to calculate the radiative transition probability (A(R)), radiative life time (τ(R)), branching ratios (β(R)) for various excited luminescent states. Using the near infrared emission spectra, full width at half maxima (FWHM), stimulated emission cross-section (σ(e)) and figure of merit (FOM) were evaluated and compared with other hosts. Especially, the numerical values of these parameters indicate that the emission transition (4)I(13/2)→(4)I(15/2) at 1.506 μm in Er(3+)-doped cadmium bismuth borate glasses may be useful in optical communication. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Effect of Bi2O3 on structural, optical, and other physical properties of semiconducting zinc vanadate glasses

    NASA Astrophysics Data System (ADS)

    Punia, R.; Kundu, R. S.; Hooda, J.; Dhankhar, S.; Dahiya, Sajjan; Kishore, N.

    2011-08-01

    Zinc bismuth vanadate glasses with compositions 50V2O5-xBi2O3-(50-x) ZnO have been prepared using a conventional melt-quenching method and the solubility limit of Bi2O3 in zinc vanadate glass system has been investigated using x-ray diffraction. Density has been measured using Archimedes' principle; molar volume (Vm) and crystalline volumes (Vc) have also been estimated. With an increase in Bi2O3 content, there is an increase in density and molar volume of the glass samples. The glass transition temperature (Tg) and Hurby coefficient (Kgl) have been determined using differential scanning calorimetry (DSC) and are observed to increase with increase in Bi2O3 content (i.e., x), up to x = 15, thereby indicating the structural modifications and increased thermal stability of zinc vanadate glasses on addition of Bi2O3. FTIR spectra have been recorded and the analysis of FTIR shows that the structure depends upon the Bi2O3 content in the glass compositions. On addition of Bi2O3 into the zinc vanadate system, the structure of V2O5 changes from VO4 tetrahedral to VO5 trigonal bi-pyramid configuration. The optical parameters have been calculated by using spectroscopic ellipsometry for bulk oxide glasses (perhaps used first time for bulk glasses) and optical bandgap energy is found to increase with increase in Bi2O3 content.

  20. Energy transfer and colour tunability in UV light induced Tm3+/Tb3+/Eu3+: ZnB glasses generating white light emission.

    PubMed

    Naresh, V; Gupta, Kiran; Parthasaradhi Reddy, C; Ham, Byoung S

    2017-03-15

    A promising energy transfer (Tm 3+ →Tb 3+ →Eu 3+ ) approach is brought forward to generate white light emission under ultraviolet (UV) light excitation for solid state lightening. Tm 3+ /Tb 3+ /Eu 3+ ions are combinedly doped in zinc borate glass system in view of understanding energy transfer process resulting in white light emission. Zinc borate (host) glass displayed optical and luminescence properties due to formation of Zn(II) x -[O(-II)] y centres in the ZnB glass matrix. At 360nm (UV) excitation, triply doped Tm 3+ /Tb 3+ /Eu 3+ : ZnB glasses simultaneously shown their characteristic emission bands in blue (454nm: 1 D 2 → 3 F 4 ), green (547nm: 5 D 4 → 7 F 5 ) and red (616nm: 5 D 0 → 7 F 2 ) regions. In triple ions doped glasses, energy transfer dynamics is discussed in terms of Forster-Dexter theory, excitation & emission profiles, lifetime curves and from partial energy level diagram of three ions. The role of Tb 3+ in ET from Tm 3+ →Eu 3+ was discussed using branch model. From emission decay analysis, energy transfer probability (P) and efficiency (η) were evaluated. Colour tunability from blue to white on varying (Tb 3+ , Eu 3+ ) content is demonstrated from Commission Internationale de L'Eclairage (CIE) chromaticity coordinates. Based on chromaticity coordinates, other colour related parameters like correlated colour temperature (CCT) and colour purity are also computed for the studied glass samples. An appropriate blending of such combination of rare earth ions could show better suitability as potential candidates in achieving multi-colour and warm/cold white light emission for white LEDs application in the field of solid state lightening. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Energy transfer and colour tunability in UV light induced Tm3 +/Tb3 +/Eu3 +: ZnB glasses generating white light emission

    NASA Astrophysics Data System (ADS)

    Naresh, V.; Gupta, Kiran; Parthasaradhi Reddy, C.; Ham, Byoung S.

    2017-03-01

    A promising energy transfer (Tm3 + → Tb3 + → Eu3 +) approach is brought forward to generate white light emission under ultraviolet (UV) light excitation for solid state lightening. Tm3 +/Tb3 +/Eu3 + ions are combinedly doped in zinc borate glass system in view of understanding energy transfer process resulting in white light emission. Zinc borate (host) glass displayed optical and luminescence properties due to formation of Zn(II)x-[O(- II)]y centres in the ZnB glass matrix. At 360 nm (UV) excitation, triply doped Tm3 +/Tb3 +/Eu3 +: ZnB glasses simultaneously shown their characteristic emission bands in blue (454 nm: 1D2 → 3F4), green (547 nm: 5D4 → 7F5) and red (616 nm: 5D0 → 7F2) regions. In triple ions doped glasses, energy transfer dynamics is discussed in terms of Forster-Dexter theory, excitation & emission profiles, lifetime curves and from partial energy level diagram of three ions. The role of Tb3 + in ET from Tm3 + → Eu3 + was discussed using branch model. From emission decay analysis, energy transfer probability (P) and efficiency (η) were evaluated. Colour tunability from blue to white on varying (Tb3 +, Eu3 +) content is demonstrated from Commission Internationale de L'Eclairage (CIE) chromaticity coordinates. Based on chromaticity coordinates, other colour related parameters like correlated colour temperature (CCT) and colour purity are also computed for the studied glass samples. An appropriate blending of such combination of rare earth ions could show better suitability as potential candidates in achieving multi-colour and warm/cold white light emission for white LEDs application in the field of solid state lightening.

  2. Effect of erbium(III) oxide addition on thermal properties and crystallization behavior of some zinc-borate glasses

    NASA Astrophysics Data System (ADS)

    Borodi, G.; Bolundut, L. C.; Pascuta, P.

    2017-12-01

    The effect of replacing B2O3 with Er2O3 on the thermal properties and crystallization behaviour of B2O3-ZnO glasses were investigated by Differential Thermal Analysis (DTA) and X-ray Diffraction Analysis (XRD) measurements. DTA measurements reveal that the temperature of vitreous transition and the glass stability increase with the increasing in concentration the erbium ions added in the samples. The fragility index of the glasses increases also, when the dopant concentration from the studied samples increases. The glass was obtained from kinetically strong-glass-forming liquid (KS type glass). The most stable sample from the thermal point of view seems to be the sample that contains 10 mol% of Er2O3. The XRD patterns of the heat-treated samples at 860°C show new crystalline phases that contain erbium when the concentration of Er2O3 in the samples is higher than 3 mol%.

  3. Effect of R(3+) ions on the structure and properties of lanthanum borate glasses

    NASA Technical Reports Server (NTRS)

    Chakraborty, I. N.; Day, D. E.

    1985-01-01

    The present investigation of glass formation in the (mole percent) systems 25La2O3 (x)R2O3 (75-x)B2O3, where R = Al, Ga, and (25-x)La2O3 (x)Ln2O3 75B2O3, where Ln = Gd, Er, Y, notes that up to 25 mol pct Al2O3 or Ga2O3 can be substituted for B2O3, while no more than about 5 mol pct Ln2O3, substituted for La2O3, caused macro-phase separation. The substitution of either R2O3 or Ln2O3 in the lanthanum borate system changes the separation distance between adjacent B3O6 chains. The effect of this structural change on the molar volume, transformation temperature, thermal expansion coefficient, and transformation-range viscosity is discussed.

  4. X-Ray Absorption Spectroscopy Studies of the Atomic Structure of Zirconium-Doped Lithium Silicate Glasses and Glass-Ceramics, Zirconium-Doped Lithium Borate Glasses, and Vitreous Rare-Earth Phosphates

    NASA Astrophysics Data System (ADS)

    Yoo, Changhyeon

    In the first part of this work, the atomic-scale structure around rare-earth (RE = Pr, Nd, Eu, Dy, and Er) cations (RE3+) in rare-earth sodium ultraphosphate (REUP) glasses were investigated using RE LIII -edge (RE = Nd, Er, Dy, and Eu) and K-edge (RE = Pr and Dy) Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. (RE2O 3)x(Na2O)y(P2O5) 1-x-y glasses in the compositional range 0 ≤ x ≤ 0.14 and 0.3 ≤ x + y ≤ 0.4 were studied. For the nearest oxygen shell, the RE-oxygen (RE-O) coordination number decreases from 10.8 to 6.5 with increasing RE content for Pr-, Nd-, Dy-, and Er-doped sodium ultraphosphate glasses. For Eu-doped samples, the Eu-O coordination number was between 7.5 and 8.8. Also, the RE-O mean distance ranges were between 2.43-2.45 A, 2.40-2.43 A, 2.36-2.38 A, 2.30-2.35 A, and 2.28-2.30 A for Pr-, Nd-, Eu-, Dy-, and Er-doped samples, respectively. In the second part, a series of Zr-doped (3-10 mol%) lithium silicate (ZRLS) glass-ceramics and their parent glasses and a series of Zr-doped (2-6 mol% ZrO2) lithium borate (ZRLB) glasses were investigated using Zr K-edge EXAFS and X-ray Absorption Near Edge Structure (XANES) spectroscopy. Immediate coordination environments of all ZRLS glasses are remarkably similar for different compositions. For the nearest oxygen shell, the Zr-O coordination number ranges were between 6.1 and 6.3 for nucleated and crystallized samples, respectively. Also, the Zr-O mean distance remains similar around 2.10 A. For these glasses, the composition dependence of structural parameters was small. Small changes in the coordination environment were observed for ZRLS glass-ceramics after thermal treatments. In contrast, Zr coordination environment in ZRLB glasses appear to depend appreciably on the Zr concentration. For the nearest oxygen shell, the Zr-O coordination number increased from 6.1 to 6.8 and the Zr-O distance decreased from 2.18 A to 2.14 A with decreasing ZrO2 content.

  5. Spectroscopic studies of Sm3+ ions activated lithium lead alumino borate glasses for visible luminescent device applications

    NASA Astrophysics Data System (ADS)

    Deopa, Nisha; Rao, A. S.

    2017-10-01

    Photoluminescence (PL) characterization of Lithium Lead Alumino Borate (LiPbAlB) glasses doped with Sm3+ ions at varying concentrations have been studied by using absorption, excitation, emission, time resolved and confocal image measurements. From the absorption spectra, Judd-Ofelt (J-O) intensity parameters were evaluated and in turn used to estimate various radiative parameters for the fluorescent levels of Sm3+ ion doped LiPbAlB glasses. The PL spectra of Sm3+ ions exhibit three emission bands corresponding to the transitions 4G5/2 → 6H5/2, 6H7/2 and 6H9/2, for which the emission cross-sections and branching ratios were evaluated to know the potentialities of these materials as visible luminescent devices. The decay spectral profiles measured for 4G5/2 → 6H7/2 transition level were used to estimate quantum efficiency of the as-prepared glasses. The non-exponential decay curves observed for higher Sm3+ ion concentrations were well fitted to Inokuti-Hirayama model to understand the predominant energy transfer mechanism involved in the as-prepared glasses. CIE chromaticity coordinates and correlated color temperatures (CCT) were evaluated to understand the utility of the titled glasses in cool white light generation. The confocal images captured under 405 nm CW laser excitation show intense reddish-orange color. From the evaluated radiative parameters, emission cross-sections, quantum efficiency, CIE co-ordinates, CCT temperatures and confocal images, it was observed that LiPbAlB glass with 0.5 mol% Sm3+ ions are more suitable for w-LEDs and reddish-orange luminescent device applications.

  6. Spectroscopic analysis of a novel Nd3+-activated barium borate glass for broadband laser amplification

    NASA Astrophysics Data System (ADS)

    Vázquez, G. V.; Muñoz H., G.; Camarillo, I.; Falcony, C.; Caldiño, U.; Lira, A.

    2015-08-01

    Spectroscopic parameters of a novel Nd3+-activated barium borate (BBONd) glass have been analyzed for broadband laser amplification. The Judd-Ofelt (JO) intensity parameters were determined through a systematic analysis of the absorption spectrum of Nd3+ ions in the BBONd glass. High values of the JO intensity parameters reveal a great centro-symmetrical loss of the Nd3+ sites and high covalency degree of the ligand field. The very high Ω6 intensity parameter value makes evident both a great structural distortion of the Nd3+ sites and a strong electron-phonon coupling between Nd3+ and free OH- ions, which is consistent with the phonon energy maximum (3442.1 cm-1) recorded by Raman spectroscopy. This strong electron-phonon coupling favors high effective bandwidth and gain bandwidth values of the laser emission (4F3/2 → 4I11/2) of Nd3+ ions. The electric-dipole oscillator strengths of all the Nd3+ absorption transitions, and in particular that of the hypersensitive transition (4I9/2 → 4G5/2), are enhanced by this great structural distortion of the host. Broadband laser amplification of the 4F3/2 → 4I11/2 emission (1062 nm) of Nd3+ ions in the BBONd glass pumped at 805 nm (4I9/2 → 4F5/2 + 2H9/2) is evaluated through the main fluorescent parameters in competition with non-radiative processes. In general, the BBONd glass exhibits spectroscopic parameters comparable with those reported in the literature for broadband laser amplification into the IR region.

  7. Combination of platelet-rich plasma with degradable bioactive borate glass for segmental bone defect repair.

    PubMed

    Zhang, Ya-Dong; Wang, Gang; Sun, Yan; Zhang, Chang-Qing

    2011-02-01

    Porous scaffold biomaterials may offer a clinical alternative to bone grafts; however, scaffolds alone are typically insufficient to heal large bone defects. Numerous studies have demonstrated that osteoinductive growth factor significantly improves bone repair. In this study, a strategy combining degradable bioactive borate glass (BG) scaffolds with platelet-rich plasma (PRP) was tested. The bone defect was filled with BG alone, BG combined with autologous PRP or left empty. Bone formation was analyzed at 4, 8 and 12 weeks using both histology and radiology. The PRP treated group yielded better bone formation than the pure BG scaffold as determined by both histology and microcomputer tomography after 12 weeks. In conclusion, PRP improved bone healing in a diaphyseal rabbit model on BG. The combination of PRP and BG may be an effective approach to repair critical defects.

  8. Effect of pyrophosphate ions on the conversion of calcium-lithium-borate glass to hydroxyapatite in aqueous phosphate solution.

    PubMed

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

    2010-10-01

    The conversion of glass to a hydroxyapatite (HA) material in an aqueous phosphate solution is used as an indication of the bioactive potential of the glass, as well as a low temperature route for preparing biologically useful materials. In this work, the effect of varying concentrations of pyrophosphate ions in the phosphate solution on the conversion of a calcium-lithium-borate glass to HA was investigated. Particles of the glass (150-355 μm) were immersed for up to 28 days in 0.25 M K(2)HPO(4) solution containing 0-0.1 M K(4)P(2)O(7). The kinetics of degradation of the glass particles and their conversion to HA were monitored by measuring the weight loss of the particles and the ionic concentration of the solution. The structure and composition of the conversion products were analyzed using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. For K(4)P(2)O(7) concentrations of up to 0.01 M, the glass particles converted to HA, but the time for complete conversion increased from 2 days (no K(4)P(2)O(7)) to 10 days (0.01 M K(4)P(2)O(7)). When the K(4)P(2)O(7) concentration was increased to 0.1 M, the product consisted of an amorphous calcium phosphate material, which eventually crystallized to a pyrophosphate product (predominantly K(2)CaP(2)O(7) and Ca(2)P(2)O(7)). The consequences of the results for the formation of HA materials and devices by the glass conversion route are discussed.

  9. Effect of pyrophosphate ions on the conversion of calcium–lithium–borate glass to hydroxyapatite in aqueous phosphate solution

    PubMed Central

    Fu, Hailuo; Day, Delbert E.; Huang, Wenhai

    2010-01-01

    The conversion of glass to a hydroxyapatite (HA) material in an aqueous phosphate solution is used as an indication of the bioactive potential of the glass, as well as a low temperature route for preparing biologically useful materials. In this work, the effect of varying concentrations of pyrophosphate ions in the phosphate solution on the conversion of a calcium–lithium–borate glass to HA was investigated. Particles of the glass (150–355 µm) were immersed for up to 28 days in 0.25 M K2HPO4 solution containing 0–0.1 M K4P2O7. The kinetics of degradation of the glass particles and their conversion to HA were monitored by measuring the weight loss of the particles and the ionic concentration of the solution. The structure and composition of the conversion products were analyzed using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. For K4P2O7 concentrations of up to 0.01 M, the glass particles converted to HA, but the time for complete conversion increased from 2 days (no K4P2O7) to 10 days (0.01 M K4P2O7). When the K4P2O7 concentration was increased to 0.1 M, the product consisted of an amorphous calcium phosphate material, which eventually crystallized to a pyrophosphate product (predominantly K2CaP2O7 and Ca2P2O7). The consequences of the results for the formation of HA materials and devices by the glass conversion route are discussed. PMID:20680413

  10. Extraction of heavy metal ions from waste colored glass through phase separation.

    PubMed

    Chen, Danping; Masui, Hirotsugu; Miyoshi, Hiroshi; Akai, Tomoko; Yazawa, Tetsuo

    2006-01-01

    A new method utilizing phase separation phenomena for the extraction of heavy metal ions used as colorants in colored glass is proposed. Colored soda-lime-silica glass containing Co or Cr as a colorant was remelted with B2O3 to yield soda-lime-borosilicate glass. The soda-lime-borosilicate glass thus obtained was leached in 1M nitric acid at 90 degrees C to dissolve the borate phase. All cations (Na, Ca, Cr and Co) concentrated in the borate phase are successfully leached out with the dissolution of the borate phase, when the amount of the B2O3 added to the glass and heat treatment conditions are properly chosen. Porous silicate glass powders with high SiO2 purity are obtained as the result of the leaching. Porous glass can also be formed as bulk material by controlling the composition of additives during the remelting.

  11. Laboratory strength of glass ionomer and zinc phosphate cements.

    PubMed

    Piwowarczyk, A; Ottl, P; Lauer, H C

    2001-09-01

    The present in vitro study examined 3 mechanical properties, namely compressive, flexural, and diametral tensile strength, of various commercially available cements and core materials as a function of time after mixing. The examined materials were 2 cermet cements (Ketac Silver [ESPE, Seefeld, Germany] and Chelon Silver [ESPE]), 1 metal-reinforced glass ionomer cement (Miracle Mix [GC Dental Industrial Corp, Tokyo, Japan]), 2 conventional glass ionomer cements (Ketac Bond [ESPE] and Ketac Cem [ESPE]), 1 standard cure zinc phosphate cement (Harvard Cement [Richter and Hoffmann, Berlin, Germany]), and 1 zinc phosphate cement with the addition of 30% silver amalgam alloy powder (Harvard Cement 70% with Dispersalloy 30% [Richter and Hoffmann/Johnson and Johnson, East Windsor, NJ]). Properties were measured using a universal testing machine at 15 minutes, 1 hour, and 24 hours after first mixing. Compressive strengths varied widely between the 3 times of measurement from 5.8 +/- 6.6 MPa for Ketac Cem to 144.3 +/- 10.2 MPa for Ketac Silver. Twenty-four hours after mixing, the Bonferroni test showed significant (p glass ionomer cement reinforced with sintered glass-silver particles, showed the highest mechanical properties of the examined materials. Copyright 2001 by The American College of Prosthodontists.

  12. Experimental and theoretical approach on the optical properties of zinc borotellurite glass doped with dysprosium oxide

    NASA Astrophysics Data System (ADS)

    Halimah, M. K.; Ami Hazlin, M. N.; Muhammad, F. D.

    2018-04-01

    A series of glass samples with chemical formula {[(TeO2)0.7(B2O3)0.3]0.7(ZnO)0.3}1 - x(Dy2O3)x where x = 0.01, 0.02, 0.03, 0.04 and 0.05 M fraction were synthesized through conventional melt-quenching method. The most common way to fabricate a glass material is by fusion of two or more component oxides followed by their quenching. This technique is known as melt-quenching technique. Kaur et al. (2016) [1] highlighted that the melt-quenching method able to enhance the mechanical properties like hardness and flexural strength of the material. The nature of the glass systems is proven to be amorphous based on the XRD pattern. The FTIR spectra of the glass systems confirm the existence of five bands which are assigned for the BO4, BO3, TeO4 and TeO3 vibrational groups. The density of the glass systems is increased with the addition of Dy2O3 while the molar volume is found to be inversely proportional to the density of the proposed glass. The optical properties of the glasses are determined through the absorption spectra obtained from the UV-VIS spectrophotometer. From the absorption spectra, the indirect and direct optical band gaps and the Urbach energy are found to be inversely proportional to each other. As the molar fraction of the Dy2O3 increased, the optical band gaps are observed to increase as opposed to the Urbach energy. For this glass system, the values of refractive index, electronic polarizability, oxide ion polarizability and the optical basicity are found to decrease as the addition of the dysprosium oxide is increased. From the emission spectra, two intense blue and yellow emission bands are observed, which correspond to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3 + ions respectively. The CIE chromaticity coordinates of the zinc borotellurite glass systems are found to be located in the white light region. Generation of white light The generation of the white light can be achieved by using two emission bands which comprise of the yellow

  13. Secondary relaxations in supercooled and glassy sucrose-borate aqueous solutions.

    PubMed

    Longinotti, M Paula; Corti, Horacio R; Pablo, Juan J de

    2008-10-13

    The dielectric relaxation spectra of concentrated aqueous solutions of sucrose-borate mixtures have been measured in the supercooled and glassy regions in the frequency range of 40Hz to 2MHz. The secondary (beta) relaxation process was analyzed in the temperature range 183-233K at water contents between 20 and 30wt%. The relaxation times were obtained, and the activation energy of that process was calculated. In order to assess the effect of borate on the relaxation of disaccharide-water mixtures, we also studied the dielectric behavior of sucrose aqueous solutions in the same range of temperatures and water contents. Our findings support the view that, beyond a water content of approximately 20wt%, the secondary relaxation of water-sucrose and water-sucrose-borate mixtures adopts a universal character that can be explained in terms of a simple exponential function of the temperature scaled by the glass transition temperature (T(g)). The behavior observed for water-sucrose and water-sucrose-borate mixtures is compared with previous results obtained in other water-carbohydrate systems.

  14. In vitro and in vivo dissolution behavior of a dysprosium lithium borate glass designed for the radiation synovectomy treatment of rheumatoid arthritis.

    PubMed

    Conzone, Samuel D; Brown, Roger F; Day, Delbert E; Ehrhardt, Gary J

    2002-05-01

    Dysprosium lithium borate (DyLB) glass microspheres were investigated for use in the radiation synovectomy treatment of rheumatoid arthritis. In vitro testing focused on weight loss and cation dissolution from glass microspheres immersed in simulated synovial fluid (SSF) at 37 degrees C for up to 64 days. In vivo testing was performed by injecting glass microspheres into the stifle joints of Sprague-Dawley rats and monitoring the biodegradability of the microspheres and the tissue response within the joints. The DyLB microspheres reacted nonuniformly in SSF with the majority of lithium and boron being dissolved, whereas nearly all of the dysprosium (>99.7%) remained in the reacted microspheres. Because the DyLB glasses released negligible amounts of dysprosium while reacting with SSF, they are considered safe for radiation synovectomy from the standpoint of unwanted radiation release from the joint capsule. Furthermore, the DyLB microspheres fragmented, degraded, and reacted with body fluids while in the joints of rats without histologic evidence of joint damage. Copyright 2002 Wiley Periodicals, Inc. J Biomed Mater Res 60: 260--268, 2002; DOI 10.1002/jbm.10047

  15. Quantifying the mode II critical strain energy release rate of borate bioactive glass coatings on Ti6Al4V substrates.

    PubMed

    Matinmanesh, A; Li, Y; Clarkin, O; Zalzal, P; Schemitsch, E H; Towler, M R; Papini, M

    2017-11-01

    Bioactive glasses have been used as coatings for biomedical implants because they can be formulated to promote osseointegration, antibacterial behavior, bone formation, and tissue healing through the incorporation and subsequent release of certain ions. However, shear loading on coated implants has been reported to cause the delamination and loosening of such coatings. This work uses a recently developed fracture mechanics testing methodology to quantify the critical strain energy release rate under nearly pure mode II conditions, G IIC , of a series of borate-based glass coating/Ti6Al4V alloy substrate systems. Incorporating increasing amounts of SrCO 3 in the glass composition was found to increase the G IIC almost twofold, from 25.3 to 46.9J/m 2 . The magnitude and distribution of residual stresses in the coating were quantified, and it was found that the residual stresses in all cases distributed uniformly over the cross section of the coating. The crack was driven towards, but not into, the glass/Ti6Al4V substrate interface due to the shear loading. This implied that the interface had a higher fracture toughness than the coating itself. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Glass microspheres for medical applications

    NASA Astrophysics Data System (ADS)

    Conzone, Samuel David

    Radioactive dysprosium lithium borate glass microspheres have been developed as biodegradable radiation delivery vehicles for the radiation synovectomy treatment of rheumatoid arthritis. Once injected into a diseased joint, the microspheres deliver a potent dose of radiation to the diseased tissue, while a non-uniform chemical reaction converts the glass into an amorphous, porous, hydrated dysprosium phosphate reaction product. The non-radioactive, lithium-borate component is dissolved from the glass (up to 94% weight loss), while the radioactive 165Dy reacts with phosphate anions in the body fluids, and becomes "chemically" trapped in a solid, dysprosium phosphate reaction product that has the same size as the un-reacted glass microsphere. Ethylene diamine tetraacetate (EDTA) chelation therapy can be used to dissolve the dysprosium phosphate reaction product after the radiation delivery has subsided. The dysprosium phosphate reaction product, which formed in vivo in the joint of a Sprague-Dawley rat, was dissolved by EDTA chelation therapy in <1 week, without causing any detectable joint damage. The combination of dysprosium lithium borate glass microspheres and EDTA chelation therapy provides an unique "tool" for the medical community, which can deliver a large dose (>100 Gy) of localized beta radiation to a treatment site within the body, followed by complete biodegradability. The non-uniform reaction process is a desirable characteristic for a biodegradable radiation delivery vehicle, but it is also a novel material synthesis technique that can convert a glass to a highly porous materials with widely varying chemical composition by simple, low-temperature, glass/solution reaction. The reaction product formed by nonuniform reaction occupies the same volume as the un-reacted glass, and after drying for 1 h at 300°C, has a specific surface area of ≈200 m2/g, a pore size of ≈30 nm, and a nominal crushing strength of ≈10 MPa. Finally, rhenium glass

  17. Manganese modified structural and optical properties of zinc soda lime silica glasses.

    PubMed

    Samsudin, Nur Farhana; Matori, Khamirul Amin; Wahab, Zaidan Abdul; Fen, Yap Wing; Liew, Josephine Ying Chi; Lim, Way Foong; Mohd Zaid, Mohd Hafiz; Omar, Nur Alia Sheh

    2016-03-20

    A series of MnO-doped zinc soda lime silica glass systems was prepared by a conventional melt and quenching technique. In this study, the x-ray diffraction analysis was applied to confirm the amorphous nature of the glasses. Fourier transform infrared spectroscopy shows the glass network consists of MnO4, SiO4, and ZnO4 units as basic structural units. The glass samples under field emission scanning electron microscopy observation demonstrated irregularity in shape and size with glassy phase-like structure. The optical absorption studies revealed that the optical bandgap (Eopt) values decrease with an increase of MnO content. Through the results of various measurements, the doping of MnO in the glass matrix had effects on the performance of the glasses and significantly improved the properties of the glass sample as a potential host for phosphor material.

  18. Er{sup 3+}-doped strontium lithium bismuth borate glasses for broadband 1.5 {mu}m emission - optical properties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rajesh, D.; Balakrishna, A.; Ratnakaram, Y. C.

    2013-02-05

    Strontium lithium bismuth borate glasses (SLBiB) doped with various concentrations of Er{sup 3+} were prepared using conventional melt quench technique and investigated their optical properties. The amorphous nature of the prepared glass samples was confirmed by X-ray diffraction and SEM analysis. Optical properties were studied by measuring the optical absorption and near infrared luminescence spectra at room temperature. Judd-Ofelt (J-O) theory has been applied for the f.f transitions of Er{sup 3+} ions to evaluate J-O intensity parameters, {Omega}{lambda} ({lambda} = 2, 4 and 6). Using the J-O intensity parameters, radiative properties such as transition probabilities (A{sub R}), branching ratios ({beta})more » and radiative lifetimes ({tau}) are estimated for certain transitions. From the emission spectra, peak emission-cross sections ({sigma}{sub p}) and products of stimulated emission cross-section and full width at half maximum ({sigma}{sub p} Multiplication-Sign FWHM) were calculated for the observed emission transition, {sup 4}I{sub 13/2}{yields}{sup 4}I{sub 15/2}.« less

  19. Nano crystalline Bi{sub 2}(VO{sub 5}) phases in lithium bismuth borate glasses containing mixed vanadium-nickel oxides

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yadav, Arti, E-mail: artidabhur@gmail.com; Khasa, S.; Dahiya, M. S.

    2016-05-23

    Glass composition 7V{sub 2}O{sub 5}·23Li{sub 2}O·20Bi{sub 2}O{sub 3}·50B{sub 2}O{sub 3} and x(2NiO·V{sub 2}O{sub 5})·(30-x)Li{sub 2}O·20Bi{sub 2}O{sub 3}·50B{sub 2}O{sub 3}, x=0, 2, 5, 7 and 10, were produced by conventional melt quenching technique. The quenched amorphous glass samples were annealed at temperatures 400°C and 500°C for 6 hours. The Bi{sub 2}(VO{sub 5}) crystallite were grown in all prepared glass matrix. Tn vanadium lithium bismuth borate glass (annealed), the some phrase of V{sub 2}O{sub 5}-crystal were observed along with the nano crystalline Bi{sub 2}(VO{sub 5}) phase. The sharp peaks in FTTR spectra of all annealed compositions were also compatible with the XRDmore » diffraction peaks of the system under investigation. Average crystalline size (D) of the Bi{sub 2}(VO{sub 5}) nano-crystallite was ~30 nm for samples annealed at 400°C and ~42 nm for samples annealed at 500°C. Lattice parameter and the lattice strain for all the samples was also calculated corresponding to the (113) plane of Bi{sub 2}(VO{sub 5}) crystallite.« less

  20. ROLE OF THE NETWORK FORMER IN SEMICONDUCTING OXIDE GLASSES.

    DTIC Science & Technology

    SEMICONDUCTOR DEVICES, * GLASS ), (*ELECTRICAL NETWORKS, GLASS ), ELECTRICAL PROPERTIES, SEEBECK EFFECT, BORATES, PHOSPHATES, ELECTRICAL RESISTANCE, X RAY DIFFRACTION, ANNEALING, OXIDATION, OXIDES, ELECTRODES, VANADIUM

  1. Effects of rare-earth doping on femtosecond laser waveguide writing in zinc polyphosphate glass

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fletcher, Luke B.; Witcher, Jon J.; Troy, Neil

    We have investigated waveguide writing in Er-Yb doped zinc polyphosphate glass using a femtosecond laser with a repetition rate of 1 KHz. We find that fabrication of good waveguides requires a glass composition with an O/P ratio of 3.25. The dependence on laser writing parameters including laser fluence, focusing conditions, and scan speed is reported. Waveguide properties together with absorption and emission data indicate that these glasses can be used for the fabrication of compact, high gain amplifying devices.

  2. Low loss photonic components in high index bismuth borate glass by femtosecond laser direct writing.

    PubMed

    Yang, Weijia; Corbari, Costantino; Kazansky, Peter G; Sakaguchi, Koichi; Carvalho, Isabel C S

    2008-09-29

    Single mode, low loss waveguides were fabricated in high index bismuth borate glass by femtosecond laser direct writing. A specific set of writing parameters leading to waveguides perfectly mode matched to standard single-mode fibers at 1.55 microm with an overall insertion loss of approximately 1 dB and with propagation loss below 0.2 dB/cm was identified. Photonic components such as Y-splitters and directional couplers were also demonstrated. A close agreement between their performances and theoretical predictions based upon the characterization of the waveguide properties is shown. Finally, the nonlinear refractive index of the waveguides has been measured to be 6.6 x 10(-15) cm(2)/W by analyzing self-phase modulation of the propagating femtosecond laser pulse at the wavelength of 1.46 microm. Broadening of the transmitted light source as large as 500 nm was demonstrated through a waveguide with the length of 1.8 cm.

  3. Raman scattering boson peak and differential scanning calorimetry studies of the glass transition in tellurium-zinc oxide glasses.

    PubMed

    Stavrou, E; Tsiantos, C; Tsopouridou, R D; Kripotou, S; Kontos, A G; Raptis, C; Capoen, B; Bouazaoui, M; Turrell, S; Khatir, S

    2010-05-19

    Raman scattering and differential scanning calorimetry (DSC) measurements have been carried out on four mixed tellurium-zinc oxide (TeO(2))(1 - x)(ZnO)(x) (x = 0.1, 0.2, 0.3, 0.4) glasses under variable temperature, with particular attention being given to the respective glass transition region. From the DSC measurements, the glass transition temperature T(g) has been determined for each glass, showing a monotonous decrease of T(g) with increasing ZnO content. The Raman study is focused on the low-frequency band of the glasses, the so-called boson peak (BP), whose frequency undergoes an abrupt decrease at a temperature T(d) very close to the respective T(g) values obtained by DSC. These results show that the BP is highly sensitive to dynamical effects over the glass transition and provides a means for an equally reliable (to DSC) determination of T(g) in tellurite glasses and other network glasses. The discontinuous temperature dependence of the BP frequency at the glass transition, along with the absence of such a behaviour by the high-frequency Raman bands (due to local atomic vibrations), indicates that marked changes of the medium range order (MRO) occur at T(g) and confirms the correlation between the BP and the MRO of glasses.

  4. Framework influence of erbium doped oxyfluoride glasses on their optical properties

    NASA Astrophysics Data System (ADS)

    Środa, Marcin; Cholewa-Kowalska, Katarzyna; Różański, Marek; Nocuń, Marek

    2011-01-01

    Glasses of different matrix (phosphate, borate, silicate and lead-silicate) were studied for their optical properties. The effect of Er dopant on transmittance and luminescence properties was presented. The significant “red shift” and “blue shift” of UV edge absorption were discussed based on the changes in the framework of the borate and phosphate glasses, respectively. It was showed that the integral intensity of the two main optical absorption transitions monotonically increases with the order: phosphate < borate < silicate < lead-silicate. Ellipsometric measurement was applied to obtain the refractive index of the glasses. The correlation between the shift of edge absorption and the change of refractive index was presented. Effect of glassy matrix on luminescence of Er3+ was discussed.

  5. [Vancomycin-loaded bioactive borate glass for treatment of chronic osteomyelitis in rabbits].

    PubMed

    Xie, Zongping; Liu, Xin; Jia, Weitao; Zhang, Changqing; Huang, Wenhai

    2011-07-01

    Bioactive borate glass (BG) has good biocompatibility and biodegradation. To investigate the feasibility of bioactive borate glass as a carrier of the antibiotic controlled-releasing by implanting vancomycin-loaded BG (VBG) into the focus of tibia chronic osteomyelitis after debridement. VBG and vancomycin-loaded calcium sulfate (VCS) were prepared with a vancomycin content of 80 mg/g. Sixty-five New Zealand white rabbits, weighing 2.12-3.91 kg (mean, 2.65 kg), were used. The tibia chronic osteomyelitis rabbit models were established by injecting methicillin-resistant Staphylococcus aureus (MRSA, 0.1 mL, 1 x 10(9) cfu/mL) into the right tibia of 65 rabbits. After 3 weeks of injection, 54 rabbits of successful models were randomly divided into groups A (n=11), B (n=11), C (n=16), and D (n=16). Simple debridement was performed in group A; BG, VCS, and VBG were implanted into the infection sites of groups B, C, and D respectively after thorough debridement. A sample of the debrided tissues was harvested for bacterial examination. The vancomycin serum levels were determined in groups C and D at 1, 2, 4, 10, 24, and 48 hours after operation. The boron serum levels were determined in groups B and D at 10, 24, 48, 72, and 120 hours after operation. After 8 weeks, the effectiveness was assessed radiographically, bacteriologically, and histopathologically. Ten rabbits died after operation. No vancomycin was detected in group C; the vancomycin level increased gradually, reached the highest level at 4 hours after operation, and then decreased rapidly in group D. No boron was detected in group B; the boron reached the highest serum level at 10 hours after operation, and then decreased gradually in group D. At 8 weeks, calcium sulfate degraded in group C; BG degraded partially in group D; and no obvious degradation was observed in group B. The repair effect was better in group D than in group C. There was no significant difference in radiograph scoring between groups A, B, C

  6. Physical and optical absorption studies of Fe{sup 3+} - ions doped lithium borate glasses containing certain alkaline earths

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bhogi, Ashok; Kumar, R. Vijaya; Kistaiah, P., E-mail: pkistaiah@yahoo.com

    Iron ion doped lithium borate glasses with the composition 15RO-25Li{sub 2}O-59B{sub 2}O{sub 3}-1Fe{sub 2}O{sub 3} (where R= Ca, Sr and Ba) have been prepared by the conventional melt quenching technique and characterized to investigate the physical and optical properties using XRD, density, molar volume and UV-Visible spectroscopy. The optical absorption spectra exhibit a band at around 460 nm which is assigned to {sup 6}A{sub 1g}(S) → 4E{sub g} (G) of Fe{sup 3+} ions with distorted octahedral symmetry. From ultraviolet absorption edges, the optical band gap and Urbach energies have been evaluated. The effect of alkaline earths on these properties ismore » discussed.« less

  7. Variation of photoluminescence features in Pr{sup 3+} doped lithium-fluoro-borate glass by changing different modifier oxides (MgO, CaO, CdO and PbO)-Judd-Ofelt theory application

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Balakrishna, A.; Rajesh, D.; Babu, S.

    2015-06-24

    Pr{sup 3+} (1.0 mol%) doped different modifier oxide based six lithium-fluoro-borate glasses with chemical composition of 49Li{sub 2}B{sub 4}O{sub 7}-20BaF{sub 2}-10NaF-20MO (where M= Mg, Ca, Cd and Pb), 49Li{sub 2}B{sub 4}O{sub 7}-20BaF{sub 2}-10NaF-10MgO-10CaO and 49Li{sub 2}B{sub 4}O{sub 7}-20BaF{sub 2}-10NaF-10CdO-10PbO were prepared by conventional melt quenching technique. Judd-Ofelt theory has been applied for evaluating the Judd-Ofelt intensity parameters for Pr{sup 3+} ion in these glass compositions and are in turn to used to predict radiative properties such as radiative transition probabilities (A{sub T}), branching ratios (β) and stimulated emission cross-section (σ{sub P}). Stimulated emission cross-section (σ{sub p}) of prominent emission transitions,more » {sup 3}P{sub 0}→{sup 3}H{sub 4} and {sup 1}D{sub 2}→{sup 3}H{sub 4} of Pr{sup 3+} ion in all lithium-fluoro-borate glasses were calculated. Among all the emission transitions, {sup 3}P{sub 0}→{sup 3}H{sub 4} posseses higher branching ratio and stimulated emission cross-section in Mg-Ca glass, which leads to the best laser excitation at 487 nm wavelength.« less

  8. Optical basicity and polarizability for copper-zinc doped sol-gel glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kaur, G., E-mail: gkapds@gmail.com; Pandey, O. P.; Amjotkaur,, E-mail: amjotkaur93@gmail.com

    2016-05-06

    CaO-SiO{sub 2}-B{sub 2}O{sub 3}-P{sub 2}O{sub 5} glasses have been studied by varying ratios of Copper oxide and Zinc oxide. Glasses were prepared using Sol-Gel technique. Opitical Basicity and oxide ion Polarizability were calculated and discussed in relation with non bridging Oxygen ions (NBOs). Optical basicity is average electron donating capability of an oxide atom. All glasses had a little difference in optical basicity and polarizability values but CZ8 glass (20CaO-60SiO{sub 2}-5B{sub 2}O{sub 3}-5P{sub 2}O{sub 5}-2CuO-8ZnO) came out to show highest optical basicity and polarizability with value 0.5177 and 0.9798 respectively. This showed the highest electron donating tendency of CZ8 glassmore » and highest number of NBOs. These were minimum for CZ2 glass with 8CuO and 2ZnO. In aspect of optical basicity and polarizability glasses follow the series CZ2 < CZ4 < CZ6 < CZ8. Increasing concentration of ZnO and decreasing concentration of CuO lead to higher optical basicity and oxide ion polarizability.« less

  9. Spectroscopic investigations of Nd3+ doped Lithium Lead Alumino Borate glasses for 1.06 μm laser applications

    NASA Astrophysics Data System (ADS)

    Deopa, Nisha; Rao, A. S.; Gupta, Mohini; Vijaya Prakash, G.

    2018-01-01

    Neodymium doped lithium lead alumino borate glasses were synthesized with the molar composition 10Li2Osbnd 10PbOsbnd (10-x) Al2O3sbnd 70B2O3sbnd x Nd2O3 (where, x = 0.1, 0.5, 1.0, 1.5, 2.0 and 2.5 mol %) via conventional melt quenching technique to understand their lasing potentialities using the absorption, emission and photoluminescence decay spectral measurements. The oscillator strengths measured from the absorption spectra were used to estimate the Judd-Ofelt intensity parameters using least square fitting procedure. The emission spectra recorded for the as-prepared glasses under investigation exhibit two emission transitions 4F3/2 → 4I11/2 (1063 nm) and 4F3/2 → 4I9/2 (1350 nm) for which radiative parameters have been evaluated. The emission intensity increases with increase in Nd3+ ion concentration up to 1 mol % and beyond concentration quenching took place. The decay profile shows single exponential nature for lower Nd3+ ion concentration and non-exponential for higher concentration. To elucidate the nature of energy transfer process, the non-exponential decay curves were well fitted to Inokuti-Hirayama model. The relatively higher values of emission cross-sections, branching ratios and quantum efficiency values obtained for 1.0 mol% of Nd3+ ions in LiPbAlB glass suggests it's aptness in generating lasing action at 1063 nm in NIR region.

  10. Glass transition and heat capacities of inorganic glasses: Diminishing change in the heat capacity at T{sub g} for xNa{sub 2}S + (1{minus}x)B{sub 2}S{sub 3} glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kincs, J.; Cho, J.; Bloyer, D.

    1994-09-01

    The T{sub g}`s and heat capacity functions have been measured for a series of Na{sub 2}S + B{sub 2}S{sub 3} glasses for the first time. Unlike the alkali borates, T{sub g} decreases rapidly as Na{sub 2}S is added to B{sub 2}S{sub 3}. This effect, even in the presence of a rapidly increasing fraction of tetrahedrally coordinated borons, has been associated with the ``over crosslinking`` effect of the sulfide ion. Unlike the borate glasses where each added oxygen produces two tetrahedral borons, the conversion rate for the thioborates is between four and six. This behavior is suggested to result in themore » formation of local tightly-bonded molecular-like structures that exhibit less long-range network bonding than the alkali borite glasses. A a result, T{sub g} decreases with added alkali in alkali thioborates rather than increases as in the alkali borate glasses. The change in heat capacity at T{sub g}, {Delta}C{sub p}(T{sub g}) has been carefully measured and is found to also decrease dramatically as alkali sulfide is added to the glass. Again this effect is opposite to the trends observed for the alkali borate glasses. The decreasing {Delta}C{sub p}(T{sub g}) occurs even in the presence of a decreasing T{sub g}. The authors have tentatively associated the diminishing {Delta}C{sub p}(T{sub g}) values to the decreasing density of the configurational states above T{sub g}. This is attributed to the high coordination number and site specificity caused by the added alkali sulfide. The glassy state heat capacities were analyzed and found to reach {approximately}90% of the classical limiting DuLong-Petit value just below T{sub g} for all glasses. This was used to suggest that the diminishing {Delta}C{sub p}(T{sub g}) values are associated with a unique behavior in the system to become a liquid with very little change in the density of configurational states.« less

  11. Resonant excited UV luminescence of the Gd3+ centres in borate glasses, co-doped with Gd and Ag

    NASA Astrophysics Data System (ADS)

    Padlyak, B. V.; Drzewiecki, A.; Padlyak, T. B.; Adamiv, V. T.; Teslyuk, I. M.

    2018-05-01

    The Li2B4O7:Gd, CaB4O7:Gd, LiCaBO3:Gd, and Li2B4O7:Gd, Ag glasses of high optical quality, obtained by standard technology, have been investigated by electron paramagnetic resonance (EPR) and optical spectroscopy at room temperature. The Gd impurity was added in the raw materials as Gd2O3 oxide in amounts 0.5 and 1.0 mol.%. The Ag impurity was introduced into the Li2B4O7 composition as AgNO3 and as highly dispersed metallic Ag in amount 2.0 mol.%. In all Gd-doped glasses was observed typical for glasses EPR U-spectrum of the Gd3+ (8S7/2, 4f7) ions. In the Gd-doped glasses upon the 273 nm excitation was observed weak UV emission line at 311 nm that is attributed to the 6P7/2 → 8S7/2 intraconfiguration 4f - 4f transition of the Gd3+ ions. In the Li2B4O7:Gd, Ag glass has been observed significant (∼100 times) increasing of peak intensity of the Gd3+ emission line at 311 nm in comparison with this line in CaB4O7:Gd glass. In luminescence excitation spectra of the CaB4O7:Gd and Li2B4O7:Gd, Ag glasses are observed characteristic groups of lines corresponding to the 8S7/2 → 6IJ, 6DJ transitions of the Gd3+ ions. Significant increasing of the Gd3+ emission line at 311 nm in the Li2B4O7:Gd, Ag glass is explained by energy transfer from Ag+ (4d10) to Gd3+ (4f7) upon 273 nm excitation that is resonant for 4d10 → 4d9 5s1 (1S0 → 1D2) and 8S7/2 → 6IJ transitions of the Ag+ and Gd3+ ions. Luminescence kinetics of the Gd3+ and Ag+ centres was investigated and analysed. Obtained results show that the borate glasses, co-activated by Gd3+ and Ag+, can be promising materials for effective UVB light sources for biomedical applications.

  12. Electrical conductivity and modulus formulation in zinc modified bismuth boro-tellurite glasses

    NASA Astrophysics Data System (ADS)

    Dhankhar, Sunil; Kundu, R. S.; Dult, Meenakshi; Murugavel, S.; Punia, R.; Kishore, N.

    2016-09-01

    The ac conductivity of zinc modified tellurium based quaternary glasses having composition 60 TeO2-10 B2O3-(30 - x) Bi2O3-x ZnO; x = 10, 15, 20, 25 and 30 has been investigated in the frequency range 10-1-105 Hz and in temperature range 483-593 K. Frequency and temperature dependent ac conductivity found to obey Jonscher power law modified by Almond-West. DC conductivity, crossover frequency and frequency exponent have been estimated from the fitting of the experimental data of conductivity with Jonscher power law modified by Almond-West. The ac conductivity and its frequency exponent have been analyzed by various theoretical models. In presently studied glasses ac conduction takes place via tunneling of overlapping large polaron tunneling. Activation energy is found to be increased with increase in zinc content and dc conduction takes place via variable range hopping proposed by Mott with some modification suggested by Punia et al. The value of the stretched exponent ( β) obtained by fitting of M^' ' }} reveals the presence of non-Debye type relaxation. Scaling spectra of ac conductivity and electric modulus collapse into a single master curve for all compositions and temperatures, reveals the presence of composition and temperature independent conduction and relaxation process in these glasses. Activation energy of conduction ( W) and electric modulus ( E R ) are nearly equal, indicating that polaron have to overcome the same energy barrier during conduction as well as relaxation processes.

  13. Method of recycling lithium borate to lithium borohydride through methyl borate

    DOEpatents

    Filby, Evan E.

    1977-01-01

    This invention provides a method for the recycling of lithium borate to lithium borohydride which can be reacted with water to generate hydrogen for utilization as a fuel. The lithium borate by-product of the hydrogen generation reaction is reacted with hydrogen chloride and water to produce boric acid and lithium chloride. The boric acid and lithium chloride are converted to lithium borohydride through a methyl borate intermediate to complete the recycle scheme.

  14. New High Index Optical Glasses

    NASA Astrophysics Data System (ADS)

    Blair, Gerald E.; Greco, Edgar J.; DeJager, Donald; Wylot, James M.

    1982-02-01

    The pioneering work of Charles W. Frederick and George W. Morey on the design by Frederick of an "ideal photographic lens" using hypothetical glasses, and the subsequent discovery and development of rare-element borate glasses by Morey, has been resumed at Eastman Kodak. New ultra-high index, low dispersion crown glasses and companion flint glasses have been developed, based on the needs dictated by lens design studies for novel fast cine' and still camera lenses. These new glasses reduce the number of elements required in a lens while maintaining or improving lens performance. Composition studies leading to these new glasses will be discussed.

  15. Optical properties of zinc borotellurite glass doped with trivalent dysprosium ion

    NASA Astrophysics Data System (ADS)

    Ami Hazlin, M. N.; Halimah, M. K.; Muhammad, F. D.; Faznny, M. F.

    2017-04-01

    The zinc borotellurite doped with dysprosium oxide glass samples with chemical formula {[(TeO2) 0 . 7(B2O3) 0 . 3 ] 0 . 7(ZnO) 0 . 3 } 1 - x(Dy2O3)x (where x=0.01, 0.02, 0.03, 0.04 and 0.05 M fraction) were prepared by using conventional melt quenching technique. The structural and optical properties of the proposed glass systems were characterized by using X-ray diffraction (XRD) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, and UV-VIS spectroscopy. The amorphous nature of the glass systems is confirmed by using XRD technique. The infrared spectra of the glass systems indicate three obvious absorption bands which are assigned to BO3 and TeO4 vibrational groups. Based on the absorption spectra obtained, the direct and indirect optical band gaps, as well as the Urbach energy were calculated. It is observed that both the direct and indirect optical band gaps increase with the concentration of Dy3+ ions. On the other hand, the Urbach energy is observed to decrease as the concentration of Dy3+ ions increases.

  16. X-ray-induced fluorescent centers formation in zinc- phosphate glasses doped with Ag and Cu ions

    NASA Astrophysics Data System (ADS)

    Klyukin, D. A.; Pshenova, A. S.; Sidorov, A. I.; Stolyarchuk, M. V.

    2016-08-01

    Fluorescent properties of silver and copper doped zinc-phosphate glasses were studied. By X-ray irradiation of silver and copper co-doped glasses we could create and identify new emission centers which do not exist in single-doped samples. Doping of the glass with both silver and copper ions leads to the increase of quantum yield by 2.7 times. The study was complemented by quantum chemical calculations using the time-dependent density functional theory. It was shown that fluorescence may be attributed to the formation of mixed Ag-Cu molecular clusters.

  17. Dual role of the six-coordinated molybdenum and lead ions in novel of photochromic properties of the molybdenum-lead-borate glasses.

    PubMed

    Rada, M; Maties, V; Culea, M; Rada, S; Culea, E

    2010-02-01

    Transparent glasses were prepared by conventional melting-quenching method in the xMoO(3).(100-x)[3B(2)O(3).PbO] system where 0borate network. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  18. Bioactive glass in tissue engineering

    PubMed Central

    Rahaman, Mohamed N.; Day, Delbert E.; Bal, B. Sonny; Fu, Qiang; Jung, Steven B.; Bonewald, Lynda F.; Tomsia, Antoni P.

    2011-01-01

    This review focuses on recent advances in the development and use of bioactive glass for tissue engineering applications. Despite its inherent brittleness, bioactive glass has several appealing characteristics as a scaffold material for bone tissue engineering. New bioactive glasses based on borate and borosilicate compositions have shown the ability to enhance new bone formation when compared to silicate bioactive glass. Borate-based bioactive glasses also have controllable degradation rates, so the degradation of the bioactive glass implant can be more closely matched to the rate of new bone formation. Bioactive glasses can be doped with trace quantities of elements such as Cu, Zn and Sr, which are known to be beneficial for healthy bone growth. In addition to the new bioactive glasses, recent advances in biomaterials processing have resulted in the creation of scaffold architectures with a range of mechanical properties suitable for the substitution of loaded as well as non-loaded bone. While bioactive glass has been extensively investigated for bone repair, there has been relatively little research on the application of bioactive glass to the repair of soft tissues. However, recent work has shown the ability of bioactive glass to promote angiogenesis, which is critical to numerous applications in tissue regeneration, such as neovascularization for bone regeneration and the healing of soft tissue wounds. Bioactive glass has also been shown to enhance neocartilage formation during in vitro culture of chondrocyte-seeded hydrogels, and to serve as a subchondral substrate for tissue-engineered osteochondral constructs. Methods used to manipulate the structure and performance of bioactive glass in these tissue engineering applications are analyzed. PMID:21421084

  19. Spectroscopic investigation of zinc tellurite glasses doped with Yb3 + and Er3 + ions

    NASA Astrophysics Data System (ADS)

    Bilir, Gökhan; Kaya, Ayfer; Cinkaya, Hatun; Eryürek, Gönül

    2016-08-01

    This paper presents a detailed spectroscopic investigation of zinc tellurite glasses with the compositions (0.80 - x - y) TeO2 + (0.20) ZnO + xEr2O3 + yYb2O3 (x = 0, y = 0; x = 0.004, y = 0; x = 0, y = 0.05 and x = 0.004, y = 0.05 per moles). The samples were synthesized by the conventional melt quenching method. The optical absorption and emission measurements were conducted at room temperature to determine the spectral properties of lanthanides doped zinc tellurite glasses and, to study the energy transfer processes between dopant lanthanide ions. The band gap energies for both direct and indirect possible transitions and the Urbach energies were measured from the absorption spectra. The absorption spectra of the samples were analyzed by using the Judd-Ofelt approach. The effect of the ytterbium ions on the emission properties of erbium ions was investigated and the energy transfer processes between dopant ions were studied by measuring the up-conversion emission properties of the materials. The color quality parameters of obtained visible up-conversion emission were also determined as well as possibility of using the Er3 + glasses as erbium doped fiber amplifiers at 1.55 μm in infrared emission region.

  20. Enhanced osteointegration of poly(methylmethacrylate) bone cements by incorporating strontium-containing borate bioactive glass

    PubMed Central

    Huang, Chengcheng; Zhang, Meng; Ruan, Changshun; Peng, Songlin; Li, Li; Liu, Wenlong; Wang, Ting; Li, Bing; Huang, Wenhai; Rahaman, Mohamed N.; Lu, William W.; Pan, Haobo

    2017-01-01

    Although poly(methylmethacrylate) (PMMA) cements are widely used in orthopaedics, they have numerous drawbacks. This study aimed to improve their bioactivity and osseointegration by incorporating strontium-containing borate bioactive glass (SrBG) as the reinforcement phase and bioactive filler of PMMA cement. The prepared SrBG/PMMA composite cements showed significantly decreased polymerization temperature when compared with PMMA and retained properties of appropriate setting time and high mechanical strength. The bioactivity of SrBG/PMMA composite cements was confirmed in vitro, evidenced by ion release (Ca, P, B and Sr) from SrBG particles. The cellular responses of MC3T3-E1 cells in vitro demonstrated that SrBG incorporation could promote adhesion, migration, proliferation and collagen secretion of cells. Furthermore, our in vivo investigation revealed that SrBG/PMMA composite cements presented better osseointegration than PMMA bone cement. SrBG in the composite cement could stimulate new-bone formation around the interface between the composite cement and host bone at eight and 12 weeks post-implantation, whereas PMMA bone cement only stimulated development of an intervening connective tissue layer. Consequently, the SrBG/PMMA composite cement may be a better alternative to PMMA cement in clinical applications and has promising orthopaedic applications by minimal invasive surgery. PMID:28615491

  1. Enhanced osteointegration of poly(methylmethacrylate) bone cements by incorporating strontium-containing borate bioactive glass.

    PubMed

    Cui, Xu; Huang, Chengcheng; Zhang, Meng; Ruan, Changshun; Peng, Songlin; Li, Li; Liu, Wenlong; Wang, Ting; Li, Bing; Huang, Wenhai; Rahaman, Mohamed N; Lu, William W; Pan, Haobo

    2017-06-01

    Although poly(methylmethacrylate) (PMMA) cements are widely used in orthopaedics, they have numerous drawbacks. This study aimed to improve their bioactivity and osseointegration by incorporating strontium-containing borate bioactive glass (SrBG) as the reinforcement phase and bioactive filler of PMMA cement. The prepared SrBG/PMMA composite cements showed significantly decreased polymerization temperature when compared with PMMA and retained properties of appropriate setting time and high mechanical strength. The bioactivity of SrBG/PMMA composite cements was confirmed in vitro , evidenced by ion release (Ca, P, B and Sr) from SrBG particles. The cellular responses of MC3T3-E1 cells in vitro demonstrated that SrBG incorporation could promote adhesion, migration, proliferation and collagen secretion of cells. Furthermore, our in vivo investigation revealed that SrBG/PMMA composite cements presented better osseointegration than PMMA bone cement. SrBG in the composite cement could stimulate new-bone formation around the interface between the composite cement and host bone at eight and 12 weeks post-implantation, whereas PMMA bone cement only stimulated development of an intervening connective tissue layer. Consequently, the SrBG/PMMA composite cement may be a better alternative to PMMA cement in clinical applications and has promising orthopaedic applications by minimal invasive surgery. © 2017 The Author(s).

  2. Bioactive glass/polymer composites for bone and nerve repair and regeneration

    NASA Astrophysics Data System (ADS)

    Mohammadkhah, Ali

    Bioactive glasses have several attractive properties in hard and soft tissue repair but their brittleness limited their use, as scaffolding materials, for applications in load-bearing hard tissue repair. At the same time, because of their bioactive properties, they are being studied more often for soft tissue repair. In the present work, a new glass/polymer composite scaffold was developed for the repair of load-bearing bones with high flexural strength and without brittle behavior. The new composites have 2.5 times higher flexural strength and ˜100 times higher work of fracture (without catastrophic failure) compared to a similar bare glass scaffold. Also the use of two known bioactive glasses (13-93-B3 and 45S5) was investigated in developing glass/Poly(epsilon-caprolactone) (PCL) composite films for peripheral nerve repair. It was found that a layer of globular hydroxyapatite (HA) formed on both sides of the composites. The borate glass in the composites was fully reacted in SBF and different ions were released into the solution. The addition of bioactive glass particles to the PCL lowered its elastic modulus and yield strength, but the composites remained intact after the 14 day period in SBF at 37°C. Finally, in an effort to design a better bioactive glass, new borosilicate glass compositions were developed that possess advantages of borate and silicate bioactive glasses at the same time. It was found that replacing small amounts of B2O3 with SiO2 improved glass formation, resistance to nucleation and crystallization, and increased the release rate of boron and silicon in vitro. This new borosilicate glass could be a good alternative to existing silicate and borate bioactive glasses.

  3. Effect of AlF3 on the Density and Elastic Properties of Zinc Tellurite Glass Systems

    PubMed Central

    Sidek, Haji Abdul Aziz; Rosmawati, Shaharuddin; Halimah, Mohamed Kamari; Matori, Khamirul Amin; Talib, Zainal Abidin

    2012-01-01

    This paper presents the results of the physical and elastic properties of the ternary zinc oxyfluoro tellurite glass system. Systematic series of glasses (AlF3)x(ZnO)y(TeO2)z with x = 0–19, y = 0–20 and z = 80, 85, 90 mol% were synthesized by the conventional rapid melt quenching technique. The composition dependence of the physical, mainly density and molar volume, and elastic properties is discussed in term of the AlF3 modifiers addition that are expected to produce quite substantial changes in their physical properties. The absence of any crystalline peaks in the X-ray diffraction (XRD) patterns of the present glass samples indicates the amorphous nature. The addition of AlF3 lowered the values of the densities in ternary oxyfluorotellurite glass systems. The longitudinal and transverse ultrasonic waves propagated in each glass sample were measured using a MBS8020 ultrasonic data acquisition system. All the velocity data were taken at 5 MHz frequency and room temperature. The longitudinal modulus (L), shear modulus (G), Young’s modulus (E), bulk modulus (K) and Poisson’s ratio (σ) are obtained from both velocities data and their respective density. Experimental data shows the density and elastic moduli of each AlF3-ZnO-TeO2 series are found strongly depend upon the glass composition. The addition of AlF3 modifiers into the zinc tellurite causes substantial changes in their density, molar volume as well as their elastic properties.

  4. New laser media based on microporous glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Altshuler, G.B.; Bakanov, V.A.; Dulneva, E.G.

    The results of the investigation of new class of the laser media based on dye solutions impregnated microporous glasses are presented. Based on such media highly effective active elements of tunable dye lasers and passive modulators for solid-state lasers are created. This article is devoted to laser media of the new type - the heterogenous solid-liquid media on the basis of the impregnated by the solutions of the dyes of the microporous glasses. The microporous glasses represent themselves the products of the leaching of heat - treated sodium borosilicate glasses of a certain composition range. As a result of heatmore » treatment is realized the phase separated glass. It consists of two interconnected phases: the silica rich phase and the chemical unstable sodium - borate - rich phase. If we place this glass in the acid then the ions of sodium and borate will be transfered to the solution. As a result we obtain the porous glass and this process produces the continuous claster. Therefore it could be easily impregnated by liquids and gases. We now have the technology that permits us to obtain the samples with the volume porosity from ten to fifty percent and the size of this poroses could be varied from twenty angstroms up to one thousand angstroms.« less

  5. Effect of Variable Oxidation States of Vanadium on the Structural, Optical, and Dielectric Properties of B2O3-Li2O-ZnO-V2O5 Glasses.

    PubMed

    Arya, S K; Danewalia, S S; Arora, Manju; Singh, K

    2016-12-01

    In the present study, the effect of variable vanadium oxidation states on the structural, optical, and dielectric properties of vanadium oxide containing lithium borate glasses has been investigated. Electron paramagnetic resonance studies indicate that vanadium in these glasses is mostly in the V 4+ state, having a tetragonal symmetry. As the glass composition of V 2 O 5 increases, tetragonality also increases at the cost of octahedral symmetry. The photoluminescence (PL) spectra of these glasses are dominated by zinc oxide transition, whereas the peaks pertaining to the vanadyl group are not visible in the PL spectra. The optical absorption spectra show a single wide absorption band, which is attributed to V 4+ ions in these glasses. The ac conductivity of the glasses increases with an increase in vanadium content. The highest electrical conductivity observed is ∼10 -5 S cm -1 at 250 °C for the glass with 2.5 mol % V 2 O 5 . Electrical conductivity is dominated by electron conduction, as indicated by the activation energy calculation.

  6. Exchange bias in zinc ferrite-FeNiMoB based metallic glass composite thin films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    R, Lisha; P, Geetha; B, Aravind P.

    2015-06-24

    The Exchange bias phenomenon and methods to manipulate the bias field in a controlled manner are thrust areas in magnetism due to its sophisticated theoretical concepts as well as advanced technological utility in the field of spintronics. The Exchange bias effect is observed as a result of ferromagnetic-antiferromagnetic (FM-AFM) exchange interaction, usually observed as a loop shift on field cooling below the Neel temperature of AFM. In the present study, we have chosen zinc ferrite which is a well known antiferromagnet, and FeNiMoB based metallic glass as the ferromagnet. The films were prepared by RF sputtering technique. The thickness andmore » composition was obtained by RBS. The magnetic studies using SQUID VSM indicate exchange bias effect in the system. The effect of thermal annealing on exchange bias effect was studied. The observed exchange bias in the zinc ferrite-FeNiMoB system is not due to FM-AFM coupling but due to spin glass-ferromagnetic interaction.« less

  7. Exchange bias in zinc ferrite-FeNiMoB based metallic glass composite thin films

    NASA Astrophysics Data System (ADS)

    R, Lisha; T, Hysen; P, Geetha; B, Aravind P.; Ojha, S.; Avasthi, D. K.; Ramanujan, R. V.; Anantharaman, M. R.

    2015-06-01

    The Exchange bias phenomenon and methods to manipulate the bias field in a controlled manner are thrust areas in magnetism due to its sophisticated theoretical concepts as well as advanced technological utility in the field of spintronics. The Exchange bias effect is observed as a result of ferromagnetic-antiferromagnetic (FM-AFM) exchange interaction, usually observed as a loop shift on field cooling below the Neel temperature of AFM. In the present study, we have chosen zinc ferrite which is a well known antiferromagnet, and FeNiMoB based metallic glass as the ferromagnet. The films were prepared by RF sputtering technique. The thickness and composition was obtained by RBS. The magnetic studies using SQUID VSM indicate exchange bias effect in the system. The effect of thermal annealing on exchange bias effect was studied. The observed exchange bias in the zinc ferrite-FeNiMoB system is not due to FM-AFM coupling but due to spin glass-ferromagnetic interaction.

  8. Spectroscopic investigation of zinc tellurite glasses doped with Yb(3+) and Er(3+) ions.

    PubMed

    Bilir, Gökhan; Kaya, Ayfer; Cinkaya, Hatun; Eryürek, Gönül

    2016-08-05

    This paper presents a detailed spectroscopic investigation of zinc tellurite glasses with the compositions (0.80-x-y) TeO2+(0.20) ZnO+xEr2O3+yYb2O3 (x=0, y=0; x=0.004, y=0; x=0, y=0.05 and x=0.004, y=0.05 per moles). The samples were synthesized by the conventional melt quenching method. The optical absorption and emission measurements were conducted at room temperature to determine the spectral properties of lanthanides doped zinc tellurite glasses and, to study the energy transfer processes between dopant lanthanide ions. The band gap energies for both direct and indirect possible transitions and the Urbach energies were measured from the absorption spectra. The absorption spectra of the samples were analyzed by using the Judd-Ofelt approach. The effect of the ytterbium ions on the emission properties of erbium ions was investigated and the energy transfer processes between dopant ions were studied by measuring the up-conversion emission properties of the materials. The color quality parameters of obtained visible up-conversion emission were also determined as well as possibility of using the Er(3+) glasses as erbium doped fiber amplifiers at 1.55μm in infrared emission region. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Silicate, borosilicate, and borate bioactive glass scaffolds with controllable degradation rate for bone tissue engineering applications. I. Preparation and in vitro degradation.

    PubMed

    Fu, Qiang; Rahaman, Mohamed N; Fu, Hailuo; Liu, Xin

    2010-10-01

    Bioactive glass scaffolds with a microstructure similar to that of dry human trabecular bone but with three different compositions were evaluated for potential applications in bone repair. The preparation of the scaffolds and the effect of the glass composition on the degradation and conversion of the scaffolds to a hydroxyapatite (HA)-type material in a simulated body fluid (SBF) are reported here (Part I). The in vitro response of osteogenic cells to the scaffolds and the in vivo evaluation of the scaffolds in a rat subcutaneous implantation model are described in Part II. Scaffolds (porosity = 78-82%; pore size = 100-500 microm) were prepared using a polymer foam replication technique. The glasses consisted of a silicate (13-93) composition, a borosilicate composition (designated 13-93B1), and a borate composition (13-93B3), in which one-third or all of the SiO2 content of 13-93 was replaced by B2O3, respectively. The conversion rate of the scaffolds to HA in the SBF increased markedly with the B2O3 content of the glass. Concurrently, the pH of the SBF also increased with the B2O3 content of the scaffolds. The compressive strengths of the as-prepared scaffolds (5-11 MPa) were in the upper range of values reported for trabecular bone, but they decreased markedly with immersion time in the SBF and with increasing B2O3 content of the glass. The results show that scaffolds with a wide range of bioactivity and degradation rate can be achieved by replacing varying amounts of SiO(2) in silicate bioactive glass with B2O3. Copyright 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

  10. A crystal-chemical classification of borate structures with emphasis on hydrated borates

    USGS Publications Warehouse

    Christ, C.L.; Clark, J.R.

    1977-01-01

    The rules governing formation of hydrated borate polyanions that were proposed by C.L. Christ in 1960 are critically reviewed and new rules added on the basis of recent crystal structure determinations. Principles and classifications previously published by others are also critically reviewed briefly. The fundamental building blocks from which borate polyanions can be constructed are defined on the basis of the number n of boron atoms, and the fully hydrated polyanions are illustrated. Known structures are grouped accordingly, and a shorthand notation using n and symbols ?? = triangle, T = tetrahedron is introduced so that the polyanions can be easily characterized. For example, 3:??+2T describes [B3O3(OH)5]2-. Correct structural formulas are assigned borates with known structures whereas borates of unknown structure are grouped separately. ?? 1977 Springer-Verlag.

  11. Role of lithium ions on the physical, structural and optical properties of zinc boro tellurite glasses

    NASA Astrophysics Data System (ADS)

    Rani, S.; Ahlawat, N.; Parmar, R.; Dhankhar, S.; Kundu, R. S.

    2018-07-01

    Lithium zinc boro tellurite glasses with compositions xLi2O-(100-x) [0.25ZnO-0.15B2O3-0.60TeO2] [where x = 0, 5, 10, 15 and 20 mol%] have been prepared by melt-quench technique. The amorphous nature of the prepared system is ascertained by X-ray diffraction. The density and molar volume are found to decrease with the increase in concentration of Li2O. The differential scanning calorimetry is used to calculate the glass transition temperature (Tg) and the observed values are found to be decreased. The IR and Raman spectra indicate that Li2O acts as a network modifier in the glass matrix. In the present system, tellurium exists as TeO4 and TeO3, B2O3 in the form of BO4 and BO3 and zinc oxide exists as ZnO4 structural units. The values of the optical band gap are estimated from the fitting of Mott and Davis's and model. A better convergence is achieved between experimental observed spectra of absorption coefficient and hydrogenic excitonic model. The optical band gap energy increases, whereas refractive index and molar refractivity follow the reverse trend with Li2O. The range of metallization criterion suggests that these glasses may be a potential candidate for nonlinear optical materials.

  12. Role of lithium ions on the physical, structural and optical properties of zinc boro tellurite glasses

    NASA Astrophysics Data System (ADS)

    Rani, S.; Ahlawat, N.; Parmar, R.; Dhankhar, S.; Kundu, R. S.

    2018-01-01

    Lithium zinc boro tellurite glasses with compositions xLi2O-(100-x) [0.25ZnO-0.15B2O3-0.60TeO2] [where x = 0, 5, 10, 15 and 20 mol%] have been prepared by melt-quench technique. The amorphous nature of the prepared system is ascertained by X-ray diffraction. The density and molar volume are found to decrease with the increase in concentration of Li2O. The differential scanning calorimetry is used to calculate the glass transition temperature (Tg) and the observed values are found to be decreased. The IR and Raman spectra indicate that Li2O acts as a network modifier in the glass matrix. In the present system, tellurium exists as TeO4 and TeO3, B2O3 in the form of BO4 and BO3 and zinc oxide exists as ZnO4 structural units. The values of the optical band gap are estimated from the fitting of Mott and Davis's and model. A better convergence is achieved between experimental observed spectra of absorption coefficient and hydrogenic excitonic model. The optical band gap energy increases, whereas refractive index and molar refractivity follow the reverse trend with Li2O. The range of metallization criterion suggests that these glasses may be a potential candidate for nonlinear optical materials.

  13. Enhanced transparency, mechanical durability, and antibacterial activity of zinc nanoparticles on glass substrate

    PubMed Central

    Choi, Hyung-Jin; Choi, Jin-Seok; Park, Byeong-Ju; Eom, Ji-Ho; Heo, So-Young; Jung, Min-Wook; An, Ki-Seok; Yoon, Soon-Gil

    2014-01-01

    Homogeneously distributed zinc nanoparticles (NPs) on the glass substrate were investigated for the transmittance, mechanical durability, and antibacterial effect. The buffered Ti NPs between Zn NPs and glass substrate were studied for an enhancement of the transmittance and mechanical endurance. The Ti NPs buffered Zn NPs showed a high transmittance of approximately 91.5% (at a wavelength of 550 nm) and a strong antibacterial activity for Staphylococcus aureus and Escherichia coli bacteria. The buffered Ti NPs are attractive for an excellent mechanical endurance of the Zn NPs. The Zn NPs did not require the protection layer to prevent the degradation of the performance for both the antibacterial effect and the transmittance. PMID:25183360

  14. N-Alkyl-N-methylpyrrolidinium Difluoro(oxalato)borate Ionic Liquids: Physical/Electrochemical Properties and Al Corrosion

    DTIC Science & Technology

    2013-01-01

    U.S. Army Research Laboratory, Adelphi, MD 20783, USA The synthesis and physical properties of difluoro(oxalato) borate (DFOB-)-based ionic...have a melting point (Tm) of -5°C and 31°C, respectively, whereas the PY15DFOB salt does not crystallize. Instead, this salt has a glass transition

  15. Laser stimulated third harmonic generation studies in ZnO-Ta2O5-B2O3 glass ceramics entrenched with Zn3Ta2O8 crystal phases

    NASA Astrophysics Data System (ADS)

    Siva Sesha Reddy, A.; Jedryka, J.; Ozga, K.; Ravi Kumar, V.; Purnachand, N.; Kityk, I. V.; Veeraiah, N.

    2018-02-01

    In this study zinc borate glasses doped with different concentrations Ta2O5 were synthesized and were crystallized by heat treatment for prolonged times. The samples were characterized by XRD, SEM, IR and Raman spectroscopy techniques. The SEM images of the crystallized samples have indicated that the samples contain randomly distributed crystal grains with size ∼1 μm entrenched in the residual amorphous phase. XRD studies have exhibited diffraction peaks identified as being due to the reflections from (1 1 1) planes of monoclinic Zn3Ta2O8 crystal phase that contains intertwined tetrahedral zinc and octahedral tantalate structural units. The concentration of such crystal phases in the bulk samples is observed to increase with increase of Ta2O5 up to 3.0 mol%. The IR and Raman spectroscopy studies have confirmed the presence of ZnO4 and TaO6 structural units in the glass network in addition to the conventional borate structural units. For measuring third harmonic generation (THG) in the samples, the samples were irradiated with 532 nm laser beam and the intensity of THG of probing beam (Nd:YAG λ = 1064 nm 20 ns pulsed laser (ω)) is measured as a function of fundamental beam power varying up to 200 J/m2. The intensity of THG is found to be increasing with increase of fundamental beam power and found to be the maximal for the glass crystallized with 3.0 mol% of Ta2O5. The intensity of THG of the ceramicized samples is found to be nearly 5 times higher with respect to that of pre-crystallized samples. The generation of 3ω is attributed to the perturbation/interaction between Zn3Ta2O8 anisotropic crystal grains and the incident probing beam.

  16. Influence of silver and copper doping on luminescent properties of zinc-phosphate glasses after x-ray irradiation

    NASA Astrophysics Data System (ADS)

    Murashov, Alexander A.; Sidorov, Alexander I.; Shakhverdov, Teimur A.; Stolyarchuk, Maxim V.

    2017-11-01

    It is shown, experimentally, that in silver- and copper-containing zinc-phosphate glasses, metal molecular clusters are formed during the glass synthesis. X-ray irradiation of these glasses led to the considerable increase of its luminescence in visible spectral range. This effect is caused by the transformation of the charged metal molecular clusters into the neutral state. Luminescence and excitation spectra of the glass, doped with silver and copper simultaneously, change significantly in comparison with the spectra of glasses doped with one metal. The reason for this can be the formation of hybrid AgnCum molecular clusters. The computer simulation of the structure and optical properties of such clusters by the time-dependent density functional theory method is presented. It is shown that the optimal luminescent material for photonics application, in comparison with other studied materials, is glass, containing hybrid molecular clusters.

  17. Quantitative determination of copper in a glass matrix using double pulse laser induced breakdown and electron paramagnetic resonance spectroscopic techniques.

    PubMed

    Khalil, Ahmed A I; Morsy, Mohamed A

    2016-07-01

    A series of lithium-lead-borate glasses of a variable copper oxide loading were quantitatively analyzed in this work using two distinct spectroscopic techniques, namely double pulse laser induced breakdown spectroscopy (DP-LIBS) and electron paramagnetic resonance (EPR). DP-LIBS results measured upon a combined nanosecond lasers irradiation running at 266nm and 1064nm pulses of a collinear configuration directed to the surface of borate glass samples with a known composition. This arrangement was employed to predict the electron's temperature (Te) and density (Ne) of the excited plasma from the recorded spectra. The intensity of elements' responses using this scheme is higher than that of single-pulse laser induced breakdown spectroscopy (SP-LIBS) setup under the same experimental conditions. On the other hand, the EPR data shows typical Cu (II) EPR-signals in the borate glass system that is networked at a distorted tetragonal Borate-arrangement. The signal intensity of the Cu (II) peak at g⊥=2.0596 has been used to quantify the Cu-content accurately in the glass matrix. Both techniques produced linear calibration curves of Cu-metals in glasses with excellent linear regression coefficient (R(2)) values. This study establishes a good correlation between DP-LIBS analysis of glass and the results obtained using EPR spectroscopy. The proposed protocols prove the great advantage of DP-LIBS system for the detection of a trace copper on the surface of glasses. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. A comparative study of retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements with stainless steel crowns--an in vitro study.

    PubMed

    Reddy, R; Basappa, N; Reddy, V V

    1998-03-01

    This study was conducted on 30 extracted human primary molars to assess the retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements. The teeth were embedded in resin blocks and were randomly divided into 3 groups of 10 each. The occlusal surfaces of all teeth were reduced uniformly by 1.0 to 1.5 mm. All mesial, distal undercuts were removed and sharp angles rounded. This was followed by cementing pretrimmed and precontoured stainless steel crowns on each tooth with hand pressure and storing in artificial saliva at 37 degrees C for 24 hours. Retentive strength was tested using Instron Universal Testing Machine. The load was applied starting from a zero reading and gradually increased until the cemented stainless steel crowns showed signs of movement and then the readings were recorded. It was found that retentive strengths of zinc phosphate and glass ionomer cements were statistically better (P < 0.05) when compared to the polycarboxylate cement. Negligible difference (0. 59 kg/cm2) was however observed between zinc phosphate and glass ionomer cements.

  19. Formation, structural and optical characterization of neodymium doped-zinc soda lime silica based glass

    NASA Astrophysics Data System (ADS)

    Zamratul, M. I. M.; Zaidan, A. W.; Khamirul, A. M.; Nurzilla, M.; Halim, S. A.

    New glass system of neodymium - doped zinc soda lime silica glass has been synthesized for the first time by melt-quenching of glass waste soda lime silica (SLS) with zinc oxide (ZnO) as precursor glass and Nd2O3 as dopant. In order to examine the effect of Nd3+ on the structural and optical properties, the prepared sample of structure [(ZnO)0.5(SLS)0.5](Nd2O3)x (x = 0, 1, 2, 3, 4 and 5 wt%) was characterized through X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-Vis spectroscopy (UV-Vis) and the photoluminescence (PL). XRD pattern justifies the amorphous nature of synthesized glasses. FTIR spectroscopy has been used to observe the structural evolution of ZnO4 and SiO4 groups. The UV-Vis-NIR absorption spectra reveals seven peaks centered at excitation of electron from ground state 4I9/2 to 4D3/2 + 4D5/2 (∼360 nm), 2G9/2 + 2D3/2 + 2P3/2(∼470 nm), 2K13/2 + 4G7/2 + 4G9/2 (∼523 nm), 4G5/2 + 2G7/2 (∼583 nm), 4F9/2 (∼678 nm), 4S3/2 + 4F7/2 (∼748 nm) and 4F5/2 + 2H9/2 (∼801 nm). PL spectra under the excitation of 800 nm display four emission bands centered at 531 nm, 598 nm, 637 nm and 671 nm corresponding to 4G7/2 → 4I9/2, (4G7/2 → 4I11/2, 4G5/2 → 4I9/2), (4G5/2 → 4I11/2) and (4G7/2 → 4I13/2, 4G5/2 → 4I11/2) respectively.

  20. A comparative study of retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements with stainless steel crowns - an in vitro study.

    PubMed

    Raghunath Reddy, M H; Subba Reddy, V V; Basappa, N

    2010-01-01

    An in vitro study was conducted to compare the retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements using Instron universal testing machine. Thirty preformed and pretrimmed stainless steel crowns were used for cementation on 30 extracted human primary molars which were divided into three groups of 10 teeth in each group. Then the teeth were stored in artificial saliva and incubated at 37°C for 24 h. A load was applied on to the crown and was gradually increased till the crown showed dislodgement, and then the readings were recorded using Instron recorder and analyzed for statistical significance. The surface area of crown was measured by graphical method. The retentive strength was expressed in terms of kg/cm 2 , which was calculated by the equation load divided by area. Retentive strengths of zinc phosphate (ranged from a minimum of 16.93 to amaximum of 28.13 kg/cm 2 with mean of 21.28 kg/cm 2 ) and glass ionomer cement (minimum of 13.69 - 28.15 kg/cm 2 with mean of 20.69 kg/cm 2 ) were greater than that of polycarboxylate cement (minimum of 13.26 - 22.69 kg/cm 2 with mean of 16.79 kg/cm 2 ). Negligible difference (0.59 kg/cm 2 ) of retentive strength was observed between zinc phosphate (21.28 kg/cm 2 ) and glass ionomer cements (20.69 kg/cm 2 ). Glass ionomer cements can be recommended for cementation of stainless steel crowns because of its advantages and the retentive strength was almost similar to that of zinc phosphate cement.

  1. Physical and absorption properties of titanium nanoparticles incorporated into zinc magnesium phosphate glass

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ismail, S.F.; Sahar, M.R., E-mail: mrahim057@gmail.com; Ghoshal, S.K.

    We report the influences of Titania (TiO{sub 2}) nanoparticles (NPs) on the physical and optical properties of melt quench synthesized zinc magnesium phosphate glasses. Five glass samples with composition (42 − x)P{sub 2}O{sub 5}–50ZnO–8MgO–xTiO{sub 2}, where x = 0, 1, 2, 3, 4 mol% are prepared and characterized. XRD pattern verified the amorphous nature of all samples. TEM images manifested the growth of Ti NPs of average size ≈ 5.78 nm. TiO{sub 2} NP concentration dependent variation in the physical properties including glass density, molar volume, molar refractivity, electronic polarizability and ionic packing density are determined. The values of glassmore » refractive indices, density and ionic packing density are increased with the increase of TiO{sub 2} NP contents. Conversely, the Urbach energy, direct and indirect optical band gap are found to decrease with the increase of TiO{sub 2} NP concentration. These glass compositions may be potential for various solid state devices including laser. - Highlights: • TiO{sub 2} NP embedded self-cleaning phosphate glass are synthesized for the first time. • Well dispersed and uniform sized TiO{sub 2} NPs are grown. • Absorption spectra revealed prominent peak in the UV region. • TiO{sub 2} NPs strongly influenced the physical and absorption features of synthesized glasses. • The effects of TiO{sub 2} NPs on the physical and optical properties of these glasses are determined.« less

  2. Study of electrical conductivity and memory switching in the zinc-vanadium-phosphate glasses

    NASA Astrophysics Data System (ADS)

    Mirzayi, M.; Hekmatshoar, M. H.

    2013-07-01

    Vanadium zinc phosphate glasses were prepared by the conventional melt quenching technique and effect of V2O5 concentration on d.c. conductivity of prepared samples were investigated. X-ray diffraction patterns confirmed the glassy character of the samples. The d.c. conductivity increased with increase in V2O5 content. Results showed that activation energy has a single value in the investigated range of temperature, which can be explained in accordance with Mott small pollaron hopping model. I-V characteristics at high electric field showed that switching in these glasses was memory type. The threshold field of switching was found to decrease with increase in V2O5 content. Non-linear behavior and switching phenomenon was explained by Pool-Frenkel effect and thermal model.

  3. Preparation of Ferroelectric KNbO3 Based Borate Glass System.

    PubMed

    Kruea-In, Chatchai; Intawin, Pratthana; Leenakul, Wilaiwan

    2015-11-01

    The incorporation method was employed to produce ferroelectric glass ceramics from the K2O-Nb2O5-B2O3 glass system. The nanocrystalline potassium niobate (KNbO3) was first prepared using a simple mixed oxide method, where the B2O3 was initially mixed and then melted to form glass. The successfully produced optically transparent glass was then subjected to a heat treatment schedule for further crystallization at temperatures ranging from 500 to 650 degrees C, which resulted in the precipitation of the KNbO3 phase, together with the K3B2Nb3O12 phase. Scanning electron microscopy (SEM) showed the presence of randomly oriented KNbO3 crystals dispersed in a continuous glass matrix. It was found that the glass ceramics subjected to the heat treatment at temperatures higher than 545 degrees C were opaque, while the lower gave a highly transparent glass ceramics. The crystal size and crystallinity were found to increase with increasing heat treatment temperature, which in turn plays an important role in controlling the properties of the glass ceramics, including physical, optical, and dielectric properties.

  4. Electronic polarizability, optical basicity and interaction parameter for Nd2O3 doped lithium-zinc-phosphate glasses

    NASA Astrophysics Data System (ADS)

    Algradee, M. A.; Sultan, M.; Samir, O. M.; Alwany, A. Elwhab B.

    2017-08-01

    The Nd3+-doped lithium-zinc-phosphate glasses were prepared by means of conventional melt quenching method. X-ray diffraction results confirmed the glassy nature of the studied glasses. The physical parameters such as the density, molar volume, ion concentration, polaron radius, inter-ionic distance, field strength and oxygen packing density were calculated using different formulae. The transmittance and reflectance spectra of glasses were recorded in the wavelength range 190-1200 nm. The values of optical band gap and Urbach energy were determined based on Mott-Davis model. The refractive indices for the studied glasses were evaluated from optical band gap values using different methods. The average electronic polarizability of the oxide ions, optical basicity and an interaction parameter were investigated from the calculated values of the refractive index and the optical band gap for the studied glasses. The variations in the different physical and optical properties of glasses with Nd2O3 content were discussed in terms of different parameters such as non-bridging oxygen and different concentrations of Nd cation in glass system.

  5. Retentive [correction of Preventive] efficacy of glass ionomer, zinc phosphate and zinc polycarboxylate luting cements in preformed stainless steel crowns: a comparative clinical study.

    PubMed

    Khinda, V I S; Grewal, N

    2002-06-01

    This study was undertaken to assess the efficacy of three luting cements, namely, glass ionomer, zinc phosphate and zinc polycarboxylate in retainng the preformed stainless steel crowns in-vivo. Twenty subjects, with an indication for restoration of three primary molars with stainless steel crowns, were selected. Sixty teeth were taken up for the study, and twenty crowns were cemented with each of the three luting cements. After an eight month follow up the crowns were assessed for their presence/ absence or "rocking". Statistical analysis was done using Chi-square test. The results have shown no significant difference in retentivity of stainless steel crowns with the use of either of the three luting agents.

  6. Effect of incorporation of zinc oxide nanoparticles on mechanical properties of conventional glass ionomer cements.

    PubMed

    Panahandeh, Narges; Torabzadeh, Hassan; Aghaee, Mohammadamin; Hasani, Elham; Safa, Saeed

    2018-01-01

    The aim of this study is to investigate the physical properties of conventional and resin-modified glass ionomer cements (GICs) compared to GICs supplemented with zinc oxide (ZnO) nanofiller particles at 5% (w/w). In this in vitro study, ZnO nanoparticles of different morphologies (nanospherical, nanorod, and nanoflower) were incorporated to glass ionomer powder. The samples were subjected to the flexural strength ( n = 20) and surface hardness test ( n = 12) using a universal testing machine and a Vickers hardness machine, respectively. Surface analysis and crystal structure of samples were performed with scanning electron microscope and X-radiation diffraction, respectively. The data were analyzed using one-way ANOVA, Shapiro-Wilk, and Tukey's tests ( P < 0.05). Flexural strength of glass ionomer containing nanoparticles was not significantly different from the control group ( P > 0.05). The surface hardness of the glass ionomer containing nanospherical or nanoflower ZnO was significantly lower than the control group ( P < 0.05). However, the surface hardness of glass ionomer containing nanorod ZnO was not significantly different from the control group ( P = 0.868). Incorporation of nanospherical and nanoflower ZnO to glass ionomer decreased their surface hardness, without any changes on their flexural strength. Incorporation of nanorod ZnO particles caused no effect on the mechanical properties.

  7. Polarized localization and borate-dependent degradation of the Arabidopsis borate transporter BOR1 in tobacco BY-2 cells

    PubMed Central

    Matsuoka, Ken

    2013-01-01

    In Arabidopsis the borate transporter BOR1, which is located in the plasma membrane, is degraded in the presence of excess boron by an endocytosis-mediated mechanism. A similar mechanism was suggested in rice as excess boron decreased rice borate transporter levels, although in this case whether the decrease was dependent on an increase in degradation or a decrease in protein synthesis was not elucidated. To address whether the borate-dependent degradation mechanism is conserved among plant cells, we analyzed the fate of GFP-tagged BOR1 (BOR1-GFP) in transformed tobacco BY-2 cells. Cells expressing BOR1-GFP displayed GFP fluorescence at the plasma membrane, especially at the membrane between two attached cells. The plasma membrane signal was abolished when cells were incubated in medium with a high concentration of borate (3 to 5 mM). This decrease in BOR1-GFP signal was mediated by a specific degradation of the protein after internalization by endocytosis from the plasma membrane. Pharmacological analysis indicated that the decrease in BOR1-GFP largely depends on the increase in degradation rate and that the degradation was mediated by a tyrosine-motif and the actin cytoskeleton. Tyr mutants of BOR1-GFP, which has been shown to inhibit borate-dependent degradation in Arabidopsis root cells, did not show borate-dependent endocytosis in tobacco BY-2 cells. These findings indicate that the borate-dependent degradation machinery of the borate transporter is conserved among plant species. PMID:24715955

  8. Polarized localization and borate-dependent degradation of the Arabidopsis borate transporter BOR1 in tobacco BY-2 cells.

    PubMed

    Yamauchi, Noboru; Gosho, Tadashi; Asatuma, Satoru; Toyooka, Kiminori; Fujiwara, Toru; Matsuoka, Ken

    2013-01-01

    In Arabidopsis the borate transporter BOR1, which is located in the plasma membrane, is degraded in the presence of excess boron by an endocytosis-mediated mechanism. A similar mechanism was suggested in rice as excess boron decreased rice borate transporter levels, although in this case whether the decrease was dependent on an increase in degradation or a decrease in protein synthesis was not elucidated. To address whether the borate-dependent degradation mechanism is conserved among plant cells, we analyzed the fate of GFP-tagged BOR1 (BOR1-GFP) in transformed tobacco BY-2 cells. Cells expressing BOR1-GFP displayed GFP fluorescence at the plasma membrane, especially at the membrane between two attached cells. The plasma membrane signal was abolished when cells were incubated in medium with a high concentration of borate (3 to 5 mM). This decrease in BOR1-GFP signal was mediated by a specific degradation of the protein after internalization by endocytosis from the plasma membrane. Pharmacological analysis indicated that the decrease in BOR1-GFP largely depends on the increase in degradation rate and that the degradation was mediated by a tyrosine-motif and the actin cytoskeleton. Tyr mutants of BOR1-GFP, which has been shown to inhibit borate-dependent degradation in Arabidopsis root cells, did not show borate-dependent endocytosis in tobacco BY-2 cells. These findings indicate that the borate-dependent degradation machinery of the borate transporter is conserved among plant species.

  9. Improved ionic conductivity of lithium-zinc-tellurite glass-ceramic electrolytes

    NASA Astrophysics Data System (ADS)

    Widanarto, W.; Ramdhan, A. M.; Ghoshal, S. K.; Effendi, M.; Cahyanto, W. T.; Warsito

    An enhancement in the secondary battery safety demands the optimum synthesis of glass-ceramics electrolytes with modified ionic conductivity. To achieve improved ionic conductivity and safer operation of the battery, we synthesized Li2O included zinc-tellurite glass-ceramics based electrolytes of chemical composition (85-x)TeO2·xLi2O·15ZnO, where x = 0, 5, 10, 15 mol%. Samples were prepared using the melt quenching method at 800 °C followed by thermal annealing at 320 °C for 3 h and characterized. The effects of varying temperature, alternating current (AC) frequency and Li2O concentration on the structure and ionic conductivity of such glass-ceramics were determined. The SEM images of the annealed glass-ceramic electrolytes displayed rough surface with a uniform distribution of nucleated crystal flakes with sizes less than 1 μm. X-ray diffraction analysis confirmed the well crystalline nature of achieved electrolytes. Incorporation of Li2O in the electrolytes was found to generate some new crystalline phases including hexagonal Li6(TeO6), monoclinic Zn2Te3O8 and monoclinic Li2Te2O5. The estimated crystallite size of the electrolyte was ranged from ≈40 to 80 nm. AC impedance measurement revealed that the variation in the temperatures, Li2O contents, and high AC frequencies have a significant influence on the ionic conductivity of the electrolytes. Furthermore, electrolyte doped with 15 mol% of Li2O exhibited the optimum performance with an ionic conductivity ≈2.4 × 10-7 S cm-1 at the frequency of 54 Hz and in the temperature range of 323-473 K. This enhancement in the conductivity was attributed to the sizable alteration in the ions vibration and ruptures of covalent bonds in the electrolytes network structures.

  10. Effect of MoO3 on electron paramagnetic resonance spectra, optical spectra and dc conductivity of vanadyl ion doped alkali molybdo-borate glasses

    NASA Astrophysics Data System (ADS)

    Agarwal, A.; Khasa, S.; Seth, V. P.; Sanghi, S.; Arora, M.

    2014-02-01

    Alkali molybdo-borate glasses having composition xMoO3·(30 - x)M2O·70B2O3 and xMoO3·(70 - x)B2O3·30M2O (M = Li, Na, K) with 0 ⩽ x ⩽ 15 (mol%) doped with 2.0 mol% of V2O5 have been prepared in order to study the influence of MoO3 on electrical conductivity, electron paramagnetic resonance (EPR) and optical spectra. From EPR studies it is observed that V4+ ions in these samples exist as VO2+ ions in octahedral coordination with a tetragonal compression and belong to C4V symmetry. The tetragonal nature and octahedral symmetry of V4+O6 complex increase as well as decrease depending upon the composition of glasses with increase in MoO3 but 3dxy orbit of unpaired electron in the VO2+ ion expands in all the glasses. The decrease in optical band gap suggests that there is an increase in the concentration of non-bridging oxygen's. From the study of optical transmission spectra it is observed that for all the glasses the degree of covalency of the σ-bonding decreases with increase in MoO3 content and the degree of covalency of the π-bonding also varies. These results based on optical spectroscopy are in agreement with EPR findings. It is found that dc conductivity decreases and activation energy increases with increase in MoO3:M2O (M = Li, Na, K) ratio in MoO3·M2O·B2O3 glasses, whereas the conductivity increases and activation energy decreases with increase in MoO3:B2O3 ratio in xMoO3·B2O3·M2O glasses, which is governed by the increase in nonbridging oxygen's. The variation in theoretical optical basicity, Λth is also studied.

  11. Bioactive borate glass promotes the repair of radius segmental bone defects by enhancing the osteogenic differentiation of BMSCs.

    PubMed

    Zhang, Jieyuan; Guan, Junjie; Zhang, Changqing; Wang, Hui; Huang, Wenhai; Guo, Shangchun; Niu, Xin; Xie, Zongping; Wang, Yang

    2015-11-20

    Bioactive borate glass (BG) has emerged as a promising alternative for bone regeneration due to its high osteoinductivity, osteoconductivity, compressive strength, and biocompatibility. However, the role of BG in large segmental bone repair is unclear and little is known about the underlying mechanism of BG's osteoinductivity. In this study, we demonstrated that BG possessed pro-osteogenic effects in an experimental model of critical-sized radius defects. Transplanting BG to radius defects resulted in better repair of bone defects as compared to widely used β-TCP. Histological and morphological analysis indicated that BG significantly enhanced new bone formation. Furthermore, the degradation rate of the BG was faster than that of β-TCP, which matched the higher bone regeneration rate. In addition, ions from BG enhanced cell viability, ALP activity, and osteogenic-related genes expression. Mechanistically, the critical genes Smad1/5 and Dlx5 in the BMP pathway and p-Smad1/5 proteins were significantly elevated after BG transplantation, and these effects could be blocked by the BMP/Smad specific inhibitor. Taken together, our findings suggest that BG could repair large segmental bone defects through activating the BMP/Smad pathway and osteogenic differentiation in BMSCs.

  12. Penetration of boron from topically applied borate solutions

    Treesearch

    Stan T. Lebow; Patricia K. Lebow; Steven A. Halverson

    2010-01-01

    Borate penetration relies on diffusion when borate and glycol-borate preservatives are applied to the surface of wood. This study evaluated the extent of borate penetration in framing lumber as a function of preservative formulation, wood moisture content, and diffusion time after treatment. In Phase I of the study, end-matched specimens were conditioned to target...

  13. Spectral analysis of Cu 2+: B 2O 3-ZnO-PbO glasses

    NASA Astrophysics Data System (ADS)

    Lakshminarayana, G.; Buddhudu, S.

    2005-11-01

    A new series of heavy metal oxide (PbO) based zinc borate glasses in the chemical composition of (95 - x)B 2O 3-5ZnO- xPbO ( x = 10, 15, 20, 25, 30, 35, 40, 45 and 50 mol%) have been prepared to verify their UV filtering performance. Both direct and indirect optical band gaps ( Eopt) have been evaluated for these glasses. For a reference glass of 45B 2O 3-5ZnO-50PbO, refractive indices at different wavelengths are measured and found the results satisfactorily correlated with the theoretical data upon the computation of Cauchy's constants of A = 1.766029949, B = 159531.024 nm 2 and C = -1.078 × 10 10 nm 4. Measurements concerning X-ray diffraction (XRD), FT-IR, differential scanning colorimeter (DSC) profiles have been carried out for this glass. The FT-IR profile has revealed that the glass has both BO 3 and BO 4 units. From DSC thermogram, glass transition temperature ( Tg), crystallization temperature ( Tc) and melting temperature ( Tm) have been located and from them, other related parameters of the glass have also been calculated. Visible absorption spectra of 45B 2O 3-5ZnO-(50 - x)PbO- xCuO ( x = 0. 1, 0.2, 0.5 and 1.0 mol%) have revealed two absorption bands at around 400 nm ( 2B 1g → 2E g) and 780 nm ( 2B 1g → 2B 2g) of Cu 2+ ions, respectively. Emission bands at 422 and 512 nm are found for the 1 mol% CuO doped glass with excitations at 306 and 332 nm.

  14. Zinc chloride modified electronic transport and relaxation studies in barium-tellurite glasses

    NASA Astrophysics Data System (ADS)

    Dhankhar, Sunil; Kundu, R. S.; Rani, Sunita; Sharma, Preeti; Murugavel, S.; Punia, Rajesh; Kishore, N.

    2017-09-01

    The ac conductivity of halide based tellurium glasses having composition 70 TeO2-(30-x) BaO-x ZnCl2; x = 5, 10, 15, 20 and 25 has been investigated in the frequency range 10-1 Hz to 105Hz and in the temperature range 453 K to 553 K. The frequency and temperature dependent ac conductivity show mixed behaviour with increase in halide content and found to obey Jonscher's universal power law. The values of dc conductivity, crossover frequency and frequency exponent have been estimated from the fitting of experimental data of ac conductivity with Jonscher's universal power law. For determining the conduction mechanism in studied glass system, frequency exponent has been analyzed by various theoretical models. In presently studied glasses, the ac conduction takes place via overlapping large polaron tunneling (OLPT). The values of activation energy for dc conduction (W) and the one associated with relaxation process ( E R) are found to increase with increase in x up to glass sample with x = 15 and thereafter it decrease with increase in zinc chloride content. DC conduction takes place via variable range hopping (VRH) as proposed by Mott with some modification suggested by Punia et al. The value of real part of modulus ( M') is observed to decrease with increase in temperature. The value of stretched exponent (β) obtained from fitting of M'' reveals the presence of non-Debye type of relaxation in presently studied glass samples. Scaling spectra of ac conductivity and values of electric modulus ( M' and M'') collapse into a single master curve for all the compositions and temperatures. The values of relaxation energy ( E R) for all the studied glass compositions are almost equal to W, suggesting that polarons have to overcome same barrier while relaxing and conducting. The conduction and relaxation processes in the studied glass samples are composition and temperature independent. [Figure not available: see fulltext.

  15. The Feasibility and Functional Performance of Ternary Borate-Filled Hydrophilic Bone Cements: Targeting Therapeutic Release Thresholds for Strontium

    PubMed Central

    MacDonald, Kathleen; Price, Richard B.; Boyd, Daniel

    2017-01-01

    We examine the feasibility and functionality of hydrophilic modifications to a borate glass reinforced resin composite; with the objective of meeting and maintaining therapeutic thresholds for Sr release over time, as a potential method of incorporating antiosteoporotic therapy into a vertebroplasty material. Fifteen composites were formulated with the hydrophilic agent hydroxyl ethyl methacrylate (HEMA, 15, 22.5, 30, 37.5 or 45 wt% of resin phase) and filled with a borate glass (55, 60 or 65 wt% of total cement) with known Sr release characteristics. Cements were examined with respect to degree of cure, water sorption, Sr release, and biaxial flexural strength over 60 days of incubation in phosphate buffered saline. While water sorption and glass degradation increased with increasing HEMA content, Sr release peaked with the 30% HEMA compositions, scanning electron microscope (SEM) imaging confirmed the surface precipitation of a Sr phosphate compound. Biaxial flexural strengths ranged between 16 and 44 MPa, decreasing with increased HEMA content. Degree of cure increased with HEMA content (42 to 81%), while no significant effect was seen on setting times (209 to 263 s). High HEMA content may provide a method of increasing monomer conversion without effect on setting reaction, providing sustained mechanical strength over 60 days. PMID:28708123

  16. The Feasibility and Functional Performance of Ternary Borate-Filled Hydrophilic Bone Cements: Targeting Therapeutic Release Thresholds for Strontium.

    PubMed

    MacDonald, Kathleen; Price, Richard B; Boyd, Daniel

    2017-07-14

    We examine the feasibility and functionality of hydrophilic modifications to a borate glass reinforced resin composite; with the objective of meeting and maintaining therapeutic thresholds for Sr release over time, as a potential method of incorporating antiosteoporotic therapy into a vertebroplasty material. Fifteen composites were formulated with the hydrophilic agent hydroxyl ethyl methacrylate (HEMA, 15, 22.5, 30, 37.5 or 45 wt% of resin phase) and filled with a borate glass (55, 60 or 65 wt% of total cement) with known Sr release characteristics. Cements were examined with respect to degree of cure, water sorption, Sr release, and biaxial flexural strength over 60 days of incubation in phosphate buffered saline. While water sorption and glass degradation increased with increasing HEMA content, Sr release peaked with the 30% HEMA compositions, scanning electron microscope (SEM) imaging confirmed the surface precipitation of a Sr phosphate compound. Biaxial flexural strengths ranged between 16 and 44 MPa, decreasing with increased HEMA content. Degree of cure increased with HEMA content (42 to 81%), while no significant effect was seen on setting times (209 to 263 s). High HEMA content may provide a method of increasing monomer conversion without effect on setting reaction, providing sustained mechanical strength over 60 days.

  17. Structural and luminescence studies of Ho{sup 3+}-doped zinc-aluminium-sodium-phosphate (ZANP) glasses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brahmachary, K.; Rajesh, D.; Ratnakaram, Y. C., E-mail: ratnakaramsvu@gmail.com

    Trivalent holmium doped zinc-aluminium-sodium-phosphate (ZANP) glasses were prepared by conventional melt-quenching technique and characterized for their structural and luminescence properties. The amorphous nature, elemental analysis and thermal stability of the glasses were studied by using X-ray diffraction, energy dispersive spectrum and differential scanning calorimetry analysis, respectively. The absorption and fluorescence spectra have been recorded at room temperature. Based on the absorption spectra, the Judd-Ofelt parameters and radiative parameters such as spontaneous transition probabilities (A{sub R}), branching ratios (β{sub R}), radiative lifetimes (τ{sub R}) were calculated and discussed. From the emission spectra emission peak positions (λ{sub P}), effective bandwidths (Δλ{sub eff})more » and stimulated emission cross-sections (σ{sub P}) were calculated for the observed emission transitions,{sup 5}S{sub 2} ({sup 5}F{sub 4}→{sup 5}I{sub 8}) and {sup 5}F{sub 5}→{sup 5}I{sub 8} in all the glass samples. The stimulated emission cross-section is higher for ZANPHo10 glass matrix and so it may be useful for laser excitation.« less

  18. Comparison of Borate Bioactive Glass and Calcium Sulfate as Implants for the Local Delivery of Teicoplanin in the Treatment of Methicillin-Resistant Staphylococcus aureus-Induced Osteomyelitis in a Rabbit Model

    PubMed Central

    Jia, Wei-Tao; Fu, Qiang; Huang, Wen-Hai

    2015-01-01

    There is growing interest in biomaterials that can cure bone infection and also regenerate bone. In this study, two groups of implants composed of 10% (wt/wt) teicoplanin (TEC)-loaded borate bioactive glass (designated TBG) or calcium sulfate (TCS) were created and evaluated for their ability to release TEC in vitro and to cure methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis in a rabbit model. When immersed in phosphate-buffered saline (PBS), both groups of implants provided a sustained release of TEC at a therapeutic level for up to 3 to 4 weeks while they were gradually degraded and converted to hydroxyapatite. The TBG implants showed a longer duration of TEC release and better retention of strength as a function of immersion time in PBS. Infected rabbit tibiae were treated by debridement, followed by implantation of TBG or TCS pellets or intravenous injection with TEC, or were left untreated. Evaluation at 6 weeks postimplantation showed that the animals implanted with TBG or TCS pellets had significantly lower radiological and histological scores, lower rates of MRSA-positive cultures, and lower bacterial loads than those preoperatively and those of animals treated intravenously. The level of bone regeneration was also higher in the defects treated with the TBG pellets. The results showed that local TEC delivery was more effective than intravenous administration for the treatment of MRSA-induced osteomyelitis. Borate glass has the advantages of better mechanical strength, more desirable kinetics of release of TEC, and a higher osteogenic capacity and thus could be an effective alternative to calcium sulfate for local delivery of TEC. PMID:26416858

  19. Comparison of Borate Bioactive Glass and Calcium Sulfate as Implants for the Local Delivery of Teicoplanin in the Treatment of Methicillin-Resistant Staphylococcus aureus-Induced Osteomyelitis in a Rabbit Model.

    PubMed

    Jia, Wei-Tao; Fu, Qiang; Huang, Wen-Hai; Zhang, Chang-Qing; Rahaman, Mohamed N

    2015-12-01

    There is growing interest in biomaterials that can cure bone infection and also regenerate bone. In this study, two groups of implants composed of 10% (wt/wt) teicoplanin (TEC)-loaded borate bioactive glass (designated TBG) or calcium sulfate (TCS) were created and evaluated for their ability to release TEC in vitro and to cure methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis in a rabbit model. When immersed in phosphate-buffered saline (PBS), both groups of implants provided a sustained release of TEC at a therapeutic level for up to 3 to 4 weeks while they were gradually degraded and converted to hydroxyapatite. The TBG implants showed a longer duration of TEC release and better retention of strength as a function of immersion time in PBS. Infected rabbit tibiae were treated by debridement, followed by implantation of TBG or TCS pellets or intravenous injection with TEC, or were left untreated. Evaluation at 6 weeks postimplantation showed that the animals implanted with TBG or TCS pellets had significantly lower radiological and histological scores, lower rates of MRSA-positive cultures, and lower bacterial loads than those preoperatively and those of animals treated intravenously. The level of bone regeneration was also higher in the defects treated with the TBG pellets. The results showed that local TEC delivery was more effective than intravenous administration for the treatment of MRSA-induced osteomyelitis. Borate glass has the advantages of better mechanical strength, more desirable kinetics of release of TEC, and a higher osteogenic capacity and thus could be an effective alternative to calcium sulfate for local delivery of TEC. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  20. 40 CFR 721.10631 - Mixed metal borate (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed metal borate (generic). 721... Substances § 721.10631 Mixed metal borate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal borate (PMN P-12-64...

  1. 40 CFR 721.10631 - Mixed metal borate (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed metal borate (generic). 721... Substances § 721.10631 Mixed metal borate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal borate (PMN P-12-64...

  2. Optical constants, single-oscillator modal and refractive index dispersion analysis of lithium zinc bismuth borate glasses doped with Eu{sup 3+} ions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Boda, Ramesh; Srinivas, G.; Komaraiah, D.

    2016-05-06

    The glasses of composition xLi{sub 2}O-15ZnO- 20Bi{sub 2}O{sub 3}- (64 - x) B{sub 2}O{sub 3}- 1EuO (ZLB) (where x=0, 5, 10, 15, 20 mole %) prepared by melt-quenching technique. The amorphous nature of the prepared glasses was confirmed by XRD spectra. The UV-Vis optical absorption spectrum was recorded in the wave length range of 200-1000 nm. It is observed that the optical band gap is inversely changing with Urbach energy. The optical constants such as G (a constant proportional to the second-order deformation potential) and E{sub f} (a constant that depends on local coordination and is called as free energy ofmore » the glass system). The most significant result of the present work is the refractive index dispersion curves of the ZLB glasses obey the single-oscillator model and oscillator parameters (E{sub o}, E{sub d}) changed with the Li{sub 2}O content. the absorption edge, band gap and Urbach energy is changing nonlinearly with increasing content of Li{sub 2}O, which can be used to calculate the optical, physical, and other constants.« less

  3. Optical absorption, luminescence, and energy transfer processes studies for Dy3+/Tb3+-codoped borate glasses for solid-state lighting applications

    NASA Astrophysics Data System (ADS)

    Lakshminarayana, G.; Kaky, Kawa M.; Baki, S. O.; Lira, A.; Caldiño, U.; Kityk, I. V.; Mahdi, M. A.

    2017-10-01

    By using melt quenching technique, good optical quality singly doped Dy3+ or Tb3+ and Dy3+/Tb3+-codoped borate glasses were synthesized and studied by optical absorption, excitation, emission and decay lifetimes curve analysis. Following the absorption spectrum, the evaluated Judd-Ofelt (J-O) intensity parameters (Ωλ (λ = 2, 4 and 6)) were used to calculate the transition probability (AR), the branching ratio (βR), and the radiative lifetime (τR) for different luminescent transitions such as 4I15/2 → 6H15/2, 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 and 4F9/2 → 6H9/2,6F11/2 for the 0.5 mol % singly Dy3+-doped glass. The βR calculated (65%) indicates that for lasing applications, 4F9/2 → 6H13/2 emission transition is highly suitable. For all the Dy3+/Tb3+-codoped glasses, Tb3+: 5D3→7F6 emission decay lifetime curves are found to be non-exponential in nature for different concentrations of Dy3+ codoping. Using the Inokuti-Hirayama model, these nonexponential decay curves were analyzed to identify the nature of the energy transfer (ET) processes and here the electric dipole-dipole interaction is dominant for the ET. Based on the excitation and emission spectra and decay lifetimes curve analysis, the cross relaxation and ET processes between Dy3+ and Tb3+ were confirmed. For the 0.5 mol % Tb3+ and 2.0 mol % Dy3+-codoped glass, the evaluated Tb3+→Dy3+ ET efficiency (η) is found to be 45% under 369 nm excitation. Further, for Tb3+/Dy3+ -codoped glasses, an enhancement of Tb3+ green emission is observed up to 1.5 mol % Dy3+ codoping, and this is due to the non-radiative resonant ET from Dy3+ to Tb3+ upon 395 nm excitation. For singly 0.5 mol % Dy3+ or 0.5 mol % Tb3+-doped glass, the calculated color coordinates (x,y) and correlated color temperatures (CCT) represent the neutral white or warm white light regions, whereas Dy3+/Tb3+-codoped glasses (x,y) and CCT values fall in the yellowish green region with respect to the different Dy3

  4. Synthesis and different optical properties of Gd2O3 doped sodium zinc tellurite glasses

    NASA Astrophysics Data System (ADS)

    Samanta, Buddhadev; Dutta, Dibakar; Ghosh, Subhankar

    2017-06-01

    A series of Gd2O3 doped sodium zinc tellurite [xGd2O3-(0.8-x) TeO2-0.1Na2O-0.1ZnO] glasses are prepared by the conventional melt quenching method and their optical properties have been studied. UV-vis spectrophotometric studies within the wavelength range from 230 nm-800 nm are carried out in the integrating sphere mode to study the effect of Gd2O3 doping on the optical band gap (Eg), refractive index (n), dielectric constant (εr) and susceptibility (χ). Other physical properties like molar volume, molar refraction, polarizability, metallization criterion, number density of rare-earth ions (N), polaron radius (rp), inter ionic distance (ri), molar cation polarizability (∑αi), number of oxide ions in chemical composition (NO2-), optical band gap based electronic oxide ion polarizability (αO2-) and optical basicity (Λ) of glass samples have been studied on the basis of UV-vis spectra and density profile of the different glasses.

  5. Influence of europium (Eu3+) ions on the optical properties of lithium zinc phosphate glasses

    NASA Astrophysics Data System (ADS)

    Shwetha, M.; Eraiah, B.

    2018-02-01

    Europium doped lithium zinc phosphate glasses with composition xEu2O3-(15-x) Li2O-45ZnO-40P2O5 (where x=0, 0.1, 0.3 and 0.5 mol %) named as EP0, EP1, EP3 and EP5 respectively, are prepared by melt-quenching method and the influence of Eu3+ ions on physical and optical properties of these glasses has been studied. Optical properties were studied using optical absorption spectra which was recorded at room temperature in the UV-Visible region. Optical direct band gap and indirect band gap energies were measured and their values range from 3.167 to 4.23eV and 2.08 to 3.02eV, respectively. Refractive indices have been measured with respect to different concentration of europium ions. Fluorescence spectroscopy measurements have been performed by excitation in the UV-Visible range, which resulted in the significant fluorescence peaks. The luminescence color of the glass system is characterized using Commission International de l’Eclairage de France 1931 standards.

  6. Optical spectroscopy and luminescence properties of Ho3+ doped zinc fluorophosphate (ZFP) glasses for green luminescent device applications

    NASA Astrophysics Data System (ADS)

    Reddy Prasad, V.; Damodaraiah, S.; Ratnakaram, Y. C.

    2018-04-01

    Ho3+ doped zinc fluorophosphate (ZFP) glasses with molar chemical compositions, (60-x) NH4H2PO4+20ZnO+10BaF2+10NaF+xHo2O3 (where x = 0.1, 0.3, 0.5, 1.0 and 1.5 mol%) were prepared by melt quenching technique. These glasses were characterized through physical, structural, optical, excitation, luminescence and decay curve analysis. From the absorption spectra, spectral intensities (fexp and fcal), Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6), radiative transition probabilities (AT), radiative lifetimes (τR) and branching ratios (βR) were evaluated for all Ho3+ doped ZFP glass matrices. From the photoluminescence spectra, peak stimulated emission cross-sections (σP) were calculated for all Ho3+ doped ZFP glasses. The Ho3+ doped ZFP glasses show strong green emission at 545 nm and red emission at 656 nm under excitation, 450 nm. The measured lifetimes (τmeas) of (5S2)5F4 level of Ho3+ doped ZFP glasses were obtained from decay profiles. The CIE color coordinates of Ho3+ doped ZFP glasses were calculated from emission spectra and 1.0 mol% of Ho3+ doped ZFP glass matrix gives green emission. Hence, these results confirm that the Ho3+ doped ZFP glasses could be considered as a promising candidate for visible green laser applications.

  7. Crystal growth in zinc borosilicate glasses

    NASA Astrophysics Data System (ADS)

    Kullberg, Ana T. G.; Lopes, Andreia A. S.; Veiga, João P. B.; Monteiro, Regina C. C.

    2017-01-01

    Glass samples with a molar composition (64+x)ZnO-(16-x)B2O3-20SiO2, where x=0 or 1, were successfully synthesized using a melt-quenching technique. Based on differential thermal analysis data, the produced glass samples were submitted to controlled heat-treatments at selected temperatures (610, 615 and 620 °C) during various times ranging from 8 to 30 h. The crystallization of willemite (Zn2SiO4) within the glass matrix was confirmed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Under specific heat-treatment conditions, transparent nanocomposite glass-ceramics were obtained, as confirmed by UV-vis spectroscopy. The influence of temperature, holding time and glass composition on crystal growth was investigated. The mean crystallite size was determined by image analysis on SEM micrographs. The results indicated an increase on the crystallite size and density with time and temperature. The change of crystallite size with time for the heat-treatments at 615 and 620 °C depended on the glass composition. Under fixed heat-treatment conditions, the crystallite density was comparatively higher for the glass composition with higher ZnO content.

  8. Zinc oxyfluoride transparent conductor

    DOEpatents

    Gordon, Roy G.

    1991-02-05

    Transparent, electrically conductive and infrared-reflective films of zinc oxyfluoride are produced by chemical vapor deposition from vapor mixtures of zinc, oxygen and fluorine-containing compounds. The substitution of fluorine for some of the oxygen in zinc oxide results in dramatic increases in the electrical conductivity. For example, diethyl zinc, ethyl alcohol and hexafluoropropene vapors are reacted over a glass surface at 400.degree. C. to form a visibly transparent, electrically conductive, infrared reflective and ultraviolet absorptive film of zinc oxyfluoride. Such films are useful in liquid crystal display devices, solar cells, electrochromic absorbers and reflectors, energy-conserving heat mirrors, and antistatic coatings.

  9. White light generation via up-conversion and blue tone in Er3+/Tm3+/Yb3+-doped zinc-tellurite glasses

    NASA Astrophysics Data System (ADS)

    Rivera, V. A. G.; Ferri, F. A.; Nunes, L. A. O.; Marega, E.

    2017-05-01

    Yb3+, Er3+ and Tm3+ triply doped zinc-tellurite glass have been prepared containing up to 3.23 wt% of rare-earth ion oxides, were characterized by absorption spectroscopy, excitation, emission and up-conversion spectra. Transparent and homogeneous glasses have been produced, managing the red, green and blue emission bands, in order to generate white light considering the human eye perception. The energy transfer (resonant or non-resonant) between those rare-earth ions provides a color balancing mechanism that maintains the operating point in the white region, generating warm white light, cool white light and artificial daylight through the increase of the 976/980 nm diode laser excitation power from 4 to 470 mW. A light source at 4000 K is obtained under the excitation at 980 nm with 15 mW, providing a white light environment that is comfortable to the human eye vision. The spectroscopic study presented in this work describes the white light generation by the triply-doped zinc-tellurite glass, ranging from blue, green and red, by controlling the laser excitation power and wavelength at 976/980 nm. Such white tuning provokes healthy effects on human health throughout the day, especially the circadian system.

  10. Luminescence properties of Dy3+ doped lithium zinc borosilicate glasses for photonic applications.

    PubMed

    Jaidass, N; Krishna Moorthi, C; Mohan Babu, A; Reddi Babu, M

    2018-03-01

    Different concentrations of Dy 3+ ions doped lithium zinc borosilicate glasses of chemical composition (30-x) B 2 O 3 - 25 SiO 2 -10 Al 2 O 3 -30 LiF - 5 ZnO - x Dy 2 O 3 (x = 0, 0.1, 0.5, 1.0 and 2.0 mol%) were prepared by the melt quenching technique. The prepared glasses were investigated through X-ray diffraction, optical absorption, photoluminescence and decay measurements. Intensities of absorption bands expressed in terms of oscillator strengths (f) were used to determine the Judd-Ofelt (J-O) intensity parameters Ω λ (λ = 2, 4 and 6). The evaluated J-O parameters were used to determine the radiative parameters such as transition probabilities (A R ), total transition probability rate (A T ), radiative lifetime (τ R ) and branching ratios (β R ) for the excited 4 F 9/2 level of Dy 3+ ions. The chromaticity coordinates determined from the emission spectra were found to be located in the white light region of CIE chromaticity diagram.

  11. Ultraviolet and infrared absorption spectra of Cr2O3 doped-sodium metaphosphate, lead metaphosphate and zinc metaphosphate glasses and effects of gamma irradiation: a comparative study.

    PubMed

    Marzouk, M A; ElBatal, F H; Abdelghany, A M

    2013-10-01

    The effects of gamma irradiation on spectral properties of Cr2O3-doped phosphate glasses of three varieties, namely sodium metaphosphate, lead metaphosphate and zinc metaphosphate have been investigated. Optical spectra of the undoped samples reveal strong UV absorption bands which are attributed to the presence of trace iron impurities in both the sodium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV near visible bands due to combined absorption of both trace iron impurities and divalent lead ions. The effect of chromium oxide content has been investigated. The three different Cr2O3-doped phosphate glasses reveal spectral visible bands varying in their position and intensity and splitting due to the different field strengths of the Na(+), Pb(2+), Zn(2+) cations, together with the way they are housed in the network and their effects on the polarisability of neighboring oxygens ligands. The effects of gamma irradiation on the optical spectral properties of the various glasses have been compared. The different effects for lead and zinc phosphate are related to the ability of Pb(2+), and Zn(2+) to form additional structural units causing stability of the network towards gamma irradiation. Also, the introduction of the transition metal chromium ions reveals some shielding behavior towards irradiation. Infrared absorption spectra of the three different base phosphate glasses show characteristic vibrations due to various phosphate groups depending on the type of glass and Cr2O3 is observed to slightly affect the IR spectra. Gamma irradiation causes minor variations in some of the intensities of the IR spectra but the main characteristic bands due to phosphate groups remain in their number and position. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Plasmonic Three-Dimensional Transparent Conductor Based on Al-Doped Zinc Oxide-Coated Nanostructured Glass Using Atomic Layer Deposition

    DOE PAGES

    Malek, Gary A.; Aytug, Tolga; Liu, Qingfeng; ...

    2015-04-02

    Transparent nanostructured glass coatings, fabricated on glass substrates, with a unique three-dimensional (3D) architecture were utilized as the foundation for the design of plasmonic 3D transparent conductors. Transformation of the non-conducting 3D structure to a conducting 3D network was accomplished through atomic layer deposition of aluminum-doped zinc oxide (AZO). After AZO growth, gold nanoparticles (AuNPs) were deposited by electronbeam evaporation to enhance light trapping and decrease the overall sheet resistance. Field emission scanning electron microscopy and atomic force microcopy images revealed the highly porous, nanostructured morphology of the AZO coated glass surface along with the in-plane dimensions of the depositedmore » AuNPs. Sheet resistance measurements conducted on the coated samples verified that the electrical properties of the 3D network are comparable to that of the untextured two-dimensional AZO coated glass substrates. In addition, transmittance measurements of the glass samples coated with various AZO thicknesses showed preservation of the highly transparent nature of each sample, while the AuNPs demonstrated enhanced light scattering as well as light-trapping capability.« less

  13. Plasmonic Three-Dimensional Transparent Conductor Based on Al-Doped Zinc Oxide-Coated Nanostructured Glass Using Atomic Layer Deposition

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Malek, Gary A.; Aytug, Tolga; Liu, Qingfeng

    Transparent nanostructured glass coatings, fabricated on glass substrates, with a unique three-dimensional (3D) architecture were utilized as the foundation for the design of plasmonic 3D transparent conductors. Transformation of the non-conducting 3D structure to a conducting 3D network was accomplished through atomic layer deposition of aluminum-doped zinc oxide (AZO). After AZO growth, gold nanoparticles (AuNPs) were deposited by electronbeam evaporation to enhance light trapping and decrease the overall sheet resistance. Field emission scanning electron microscopy and atomic force microcopy images revealed the highly porous, nanostructured morphology of the AZO coated glass surface along with the in-plane dimensions of the depositedmore » AuNPs. Sheet resistance measurements conducted on the coated samples verified that the electrical properties of the 3D network are comparable to that of the untextured two-dimensional AZO coated glass substrates. In addition, transmittance measurements of the glass samples coated with various AZO thicknesses showed preservation of the highly transparent nature of each sample, while the AuNPs demonstrated enhanced light scattering as well as light-trapping capability.« less

  14. Electric double-layer capacitor based on zinc metaphosphate glass-derived hydrogel

    NASA Astrophysics Data System (ADS)

    Akamatsu, Takafumi; Kasuga, Toshihiro; Nogami, Masayuki

    2006-04-01

    The present work reports the electrochemical characteristics of an electric double-layer capacitor (EDC) cell with an electrolyte consisting of a glass-derived zinc metaphosphate hydrogel (ZP gel) or H3PO4 solution. The EDC cell showed specific discharge capacities of 2.06 and 3.21F/g using the ZP gel and H3PO4 solution, respectively. The EDC cell performed higher voltage retentionability for self-discharge behavior after constant voltage using the ZP gel (0.83V after 24h) than using H3PO4 solution (0.45V after 24h). Self-discharge behaviors of the ZP gel and H3PO4 solution were controlled by a diffusion and current leakage process, respectively. These results show that the ZP gel has a great potential for practical use as an EDC electrolyte.

  15. Luminescence performance of Eu{sup 3+} doped lead free zinc phosphate glasses for red emission

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Prasad, V. Reddy; Babu, S.; Ratnakaram, Y. C., E-mail: ratnakaramsvu@gmail.com

    2016-05-06

    Luminescence performance of zinc phosphate glasses containing Eu{sup 3+} ion with the chemical compositions (60-x)NH{sub 4}H{sub 2}PO{sub 4}-20ZnO-10BaF{sub 2}-10NaF-x Eu{sub 2}O{sub 3} (where x = 0.2, 0.5, 1.0 and 1.5 mol%) has been studied. The Fourier Transform Infrared Spectroscopy (FT-IR) shows several vibrations bands. Luminescence spectra of these glasses exhibit characteristic emission of Eu{sup 3+} ion with an intense and most prominent red emission (614 nm) which is attributed to {sup 5}D{sub 0}→{sup 7}F{sub 2} transition. Judd-Ofelt (Ω{sub 2}, Ω{sub 4}) parameters have been evaluated from the luminescence intensity ratios of {sup 5}D{sub 0}→{sup 7}F{sub J} (where J = 2 and 4)more » to {sup 5}D{sub 0}→{sup 7}F{sub 1} transition as well as absorption spectra under different constraints. Using J-O parameters and excitation spectra, the radiative parameters are calculated for different Eu{sup 3+} doped glasses.« less

  16. Structural and optical properties of CuO in zinc phosphate glasses and effects of gamma irradiation

    NASA Astrophysics Data System (ADS)

    Ouis, M. A.; ElBatal, H. A.; Abdelghany, A. M.; Hammad, Ahmed H.

    2016-01-01

    Collective optical and infrared measurements have been employed to investigate the state of increasing copper ions in host 0.5ZnO-0.5P2O5 glass composition. The same spectral measurements were repeated after gamma irradiation with a dose of 20 and 80 KGy. Optical absorption spectra reveal strong UV absorption due to trace ferric ions present as unavoidable impurities within the chemicals used in the preparation of the glasses. Copper containing glasses show an additional broad visible-near infrared band due to distorted octahedrally coordinated Cu2+ ions which at high CuO contents exhibit splitting to several component absorption peaks. Gamma irradiation causes several variations between the response of the base host zinc phosphate glass and effect of increasing CuO. These changes are correlated with both the formation of induced defects through suggested photochemical reactions in the UV region and some shielding effects with increasing CuO in the visible-near infrared spectrum. Infrared absorption spectra reveal repetitive vibrational bands due to phosphate groups mainly from metaphosphate units and the spectra show some variations with the increase of CuO content visualize by the increase of the intensity of the mid broad band extending in the range 800-1500 cm-1.

  17. The effect of MgO on the optical properties of lithium sodium borate doped with Cu+ ions

    NASA Astrophysics Data System (ADS)

    Alajerami, Yasser Saleh Mustafa; Hashim, Suhairul; Hassan, Wan Muhamad Saridan Wan; Ramli, Ahmad Termizi; Saleh, Muneer Aziz

    2013-04-01

    The current work presented the photoluminescence (PL) properties of a new glass system, which are reported for the first time. Based on the attractive properties of borate glass, a mixture of boric acid (70-x mol %) modified with lithium (20 mol %) and sodium carbonate (10 mol %) was prepared. The current study illustrated the effect of dopant and co-dopant techniques on the lithium sodium borate (LNB). Firstly, 0.1 mol % of copper ions doped with LNB was excited at 610 nm. The emission spectrum showed two prominent peaks in the violet region (403 and 440 nm). Then, we remarked the effect of adding different concentration of MgO on the optical properties of LNB. The results showed the great effect of magnesium oxide on the PL intensities (enhanced more than two times). Moreover, an obvious shifting has been defined toward the blue region (440 → 475 nm). The up-conversion optical properties were observed in all emission spectra. This enhancement is contributed to the energy transfer from MgO ions to monovalent Cu+ ion. It is well known that magnesium oxide alone generates weak emission intensity, but during this increment the MgO act as an activator (co-doped) for Cu+ ions. Finally, energy band gap, density, ion concentration, molar volume, Polaron radius and inter-nuclear distance all were measured for the current samples. The current samples were subjected to XRD for amorphous confirmation and IR for glass characterization before and after dopants addition. Finally, some of significant physical and optical parameters were also calculated.

  18. Serum zinc concentrations: contamination from laboratory equipment.

    PubMed

    Ralstin, J O; Schneider, P J; Blackstone, L; Ruberg, R L

    1979-01-01

    The following experiment was designed because of high serum zinc reported in patients who were reciving total parenteral nutrition (TPN) concentrations. Blood samples were collected, divided into 3 containers: a clean glass control test tube, a vacuum collecting tube with a rubber stopper, and paraffin clot activator. It was found that compared to glass control tubes, vacuum collection with rubber stoppers contributed an average of 76 +/- 14 microgram/dl of zinc as contaminants. Moreover, tubes with a rubber stopper and clot activator contributed 198 +/- 42 microgram/dl of zinc as contaminants. It is concluded that care must be used to avoid trace element contaminants when plasma zinc concentrations are analyzed. Without proper methodology, including selection of the container in which the sample is taken, erroneous results will be reported.

  19. Mixed polyanion glass cathodes: Effect of polyanion content

    DOE PAGES

    Kercher, Andrew K.; Kolopus, James A.; Sacci, Robert L.; ...

    2017-02-18

    Mixed polyanion glass cathodes in lithium-ion batteries have very high capacities (200-500 mAh/g), but currently these materials have fundamental problems with 1 st-cycle irreversible loss, cycling efficiency, and capacity fade. It is well established that polyanion substitutions into glasses can dramatically affect their physical properties, but the effect of polyanion content on the electrochemical performance has not been previously established. The proper amount of lithium and borate substitution in copper phosphate/vanadate glasses was shown to nearly eliminate 1 st-cycle irreversible loss and improve cycling efficiency. As a result, Raman and IR spectroscopy were used to identify polyanions that correlated withmore » electrochemical performance changes.« less

  20. Physical, structural and optical characterizations of borate modified bismuth-silicate-tellurite glasses

    NASA Astrophysics Data System (ADS)

    Berwal, Neelam; Kundu, R. S.; Nanda, Kirti; Punia, R.; Kishore, N.

    2015-10-01

    Quaternary bismuthate glasses with compositions xB2O3-(80 - x) Bi2O3-15SiO2-5TeO2 have been prepared by melt-quench technique. X-ray diffraction studies were performed to ascertain the amorphous nature of samples. The density, molar volume and crystalline volume decrease with increase in B2O3 content whereas the glass transition temperature shows the reverse trend. The Raman and FTIR spectra of the studied glasses indicate that B2O3 has been found to exist in the form of BO3 trigonal and BO4 tetrahedral structural units and vibrations corresponding to these structural units increase with increase in B2O3 content. SiO2 is present in the form of SiO4 tetrahedral structural units and TeO2 in the form of TeO3 structural units. Bismuth plays the role of network modifier [BiO6 octahedra] as well as network former [BiO3 pyramids] for all the glass compositions. The optical band gap energy has been calculated from the fitting of both Mott and Davis's model and Hydrogenic excitonic model with the experimentally observed absorption spectra. A good fitting of experimental data with HEM indicates the excitonic formation in the studies glass system. The values of optical band gap energy show nonlinear behavior due to the structural changes that take place in the present glass samples. The Urbach energy calculated using Urbach empirical formula for studied glass samples suggest the possibility of reduction in defect concentrations. The metallization criterion of the presently studied samples suggests that the prepared glasses may be potential candidates for nonlinear optical applications.

  1. Novel borate glass/chitosan composite as a delivery vehicle for teicoplanin in the treatment of chronic osteomyelitis.

    PubMed

    Jia, Wei-Tao; Zhang, Xin; Luo, Shi-Hua; Liu, Xin; Huang, Wen-Hai; Rahaman, Mohamed N; Day, Delbert E; Zhang, Chang-Qing; Xie, Zong-Ping; Wang, Jian-Qiang

    2010-03-01

    Composite materials composed of borate bioactive glass and chitosan (designated BGC) were investigated in vitro and in vivo as a new delivery system for teicoplanin in the treatment of chronic osteomyelitis induced by methicillin-resistant Staphylococcus aureus (MRSA). In vitro, the release of teicoplanin from BGC pellets into phosphate-buffered saline (PBS), as well as its antibacterial activity, were determined. The compressive strength of the pellets was measured after specific immersion times, and the structure of the pellets was characterized using scanning electron microscopy and X-ray diffraction. In vivo, the tibial cavity of New Zealand White rabbits was injected with MRSA strain to induce chronic osteomyelitis, treated by debridement after 4weeks, implanted with teicoplanin-loaded BGC pellets (designated TBGC) or BGC pellets, or injected intravenously with teicoplanin. After 12weeks' implantation, the efficacy of the TBGC pellets for treating osteomyelitis was evaluated using hematological, radiological, microbiological and histological techniques. When immersed in PBS, the TBGC pellets provided a sustained release of teicoplanin, while the surface of the pellets was converted to hydroxyapatite (HA). In vivo, the best therapeutic effect was observed in animals implanted with TBGC pellets, resulting in significantly lower radiological and histological scores, a lower positive rate of MRSA culture, and an excellent bone defect repair, without local or systemic side effects. The results indicate that TBGC pellets are effective in treating chronic osteomyelitis by providing a sustained release of teicoplanin, in addition to participating in bone regeneration. Copyright 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  2. Borate minerals and origin of the RNA world.

    PubMed

    Grew, Edward S; Bada, Jeffrey L; Hazen, Robert M

    2011-08-01

    The RNA World is generally thought to have been an important link between purely prebiotic (>3.7 Ga) chemistry and modern DNA/protein biochemistry. One concern about the RNA World hypothesis is the geochemical stability of ribose, the sugar moiety of RNA. Prebiotic stabilization of ribose by solutions associated with borate minerals, notably colemanite, ulexite, and kernite, has been proposed as one resolution to this difficulty. However, a critical unresolved issue is whether borate minerals existed in sufficient quantities on the primitive Earth, especially in the period when prebiotic synthesis processes leading to RNA took place. Although the oldest reported colemanite and ulexite are 330 Ma, and the oldest reported kernite, 19 Ma, boron isotope data and geologic context are consistent with an evaporitic borate precursor to 2400-2100 Ma borate deposits in the Liaoning and Jilin Provinces, China, as well as to tourmaline-group minerals at 3300-3450 Ma in the Barberton belt, South Africa. The oldest boron minerals for which the age of crystallization could be determined are the metamorphic tourmaline species schorl and dravite in the Isua complex (metamorphism between ca. 3650 and ca. 3600 Ma). Whether borates such as colemanite, ulexite and kernite were present in the Hadean (>4000 Ma) at the critical juncture when prebiotic molecules such as ribose required stabilization depends on whether a granitic continental crust had yet differentiated, because in its absence we see no means for boron to be sufficiently concentrated for borates to be precipitated.

  3. Host responses to a strontium releasing high boron glass using a rabbit bilateral femoral defect model.

    PubMed

    O'Connell, Kathleen; Pierlot, Caitlin; O'Shea, Helen; Beaudry, Diane; Chagnon, Madeleine; Assad, Michel; Boyd, Daniel

    2017-10-01

    Borate glasses have shown promising potential as bioactive materials. With recent research demonstrating that glass properties may be modulated by appropriate compositional design. This may provide for indication specific material characteristics and controlled release of therapeutic inorganic ions (i.e., strontium); controlling such release is critical in order to harness the therapeutic potential. Within this sub-chronic pilot study, a rabbit long-bone model was utilized to explore the safety and efficacy of a high borate glass (LB102: 70B 2 O 3 -20SrO-6Na 2 O-4La 2 O 3 ) particulate (90 - 710 μm) for bone regeneration. Six bilateral full-thickness defects (Ø = 3.5 mm; L = 8 mm) were created in three white New Zealand rabbits. Longitudinal non-decalcified sections of each defect site were produced and stained with Goldner's Trichrome. Histopathological examination revealed that LB102 demonstrated osteoconductive and osseointegrative properties with greater new bone being formed within and surrounding LB102 particles, when compared to the sham control. The inflammatory cell infiltration was observed to be slightly higher in the control when compared to LB102 defect sites, while no significant difference in fibrosis and neovascularization was determined, indicating that healing was occurring in a normal fashion. These data further suggest the possible utility of high borate glasses with appropriate compositional design for medical applications, such as bone augmentation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1818-1827, 2017. © 2016 Wiley Periodicals, Inc.

  4. Synthesis and optical property of holmium doped Lithium lead borate glasses

    NASA Astrophysics Data System (ADS)

    Usharani, V. L.; Eraiah, B.

    2017-05-01

    The new glass system 60B2O3-30PbO-(10-x)Li2O-xHo2O3 (where x =0, 0.1, 0.3 and 0.5 mol%) were prepared by conventional melt quenching method. The XRD spectrum confirms the amorphous nature of the sample. The density of these glasses is measured by using Archimedes principle, the values range from 4.23 g/cm-3 to 4.34 g/cm-3 and the corresponding molar volumes are calculated. The optical absorbance studies were carried out on these glasses in the wavelength range of 200nm to 1100nm. The measured optical direct band gap energies were in the range of 3.072eV to 3.259eV and the optical indirect band gap energies in the range of 2.658eV to 2.846eV. The refractive indices of these glasses were measured by using Abbe refractometer and the corresponding polarizabilities of oxide ions are calculated by using Lorentz-Lorentz relations.

  5. Femtosecond laser-induced refractive index modification in multicomponent glasses

    NASA Astrophysics Data System (ADS)

    Bhardwaj, V. R.; Simova, E.; Corkum, P. B.; Rayner, D. M.; Hnatovsky, C.; Taylor, R. S.; Schreder, B.; Kluge, M.; Zimmer, J.

    2005-04-01

    We present a comprehensive study on femtosecond laser-induced refractive index modification in a wide variety of multicomponent glasses grouped as borosilicate, aluminum-silicate, and heavy-metal oxide glasses along with lanthanum-borate and sodium-phosphate glasses. By using high-spatial resolution refractive index profiling techniques, we demonstrate that under a wide range of writing conditions the refractive index modification in multicomponent glasses can be positive, negative, or nonuniform, and exhibits a strong dependence on the glass composition. With the exception of some aluminum-silicate glasses all other glasses exhibited a negative/nonuniform index change. We also demonstrate direct writing of waveguides in photosensitive Foturan® glass with a femtosecond laser without initiating crystallization by thermal treatment. Upon ceramization of lithium-aluminum-silicate glasses such as Foturan®, Zerodur®, and Robax® we observe switching of laser-induced refractive index change from being positive to negative. The measured transmission losses in the waveguides at 1550nm agree with the index profile measurements in alkali-free aluminum-silicate glasses.

  6. SnO-containing oxide glasses emitting in 1.0–2.0 µm spectral range

    NASA Astrophysics Data System (ADS)

    Denker, B. I.; Galagan, B. I.; Sverchkov, S. E.; Dianov, E. M.

    2018-06-01

    Different SnO-containing oxide glasses with various net formers (silicate, phosphate, germanate, borate, and a number of mixed compositions) were investigated for the presence of near-infrared photoluminescence. It was found that SnO-containing silicate and germanate, and also a plurality of mixed glass compositions, exhibit wideband photoluminescence peaking at 1.5–1.6 µm and with lifetimes in the order of 100 µs. These glasses are interesting as promising active materials for widely tunable fiber lasers and wideband amplifiers.

  7. Structural and optical studies of Er3+-doped alkali/alkaline oxide containing zinc boro-aluminosilicate glasses for 1.5 μm optical amplifier applications

    NASA Astrophysics Data System (ADS)

    Kaky, Kawa M.; Lakshminarayana, G.; Baki, S. O.; Lira, A.; Caldiño, U.; Meza-Rocha, A. N.; Falcony, C.; Kityk, I. V.; Taufiq-Yap, Y. H.; Halimah, M. K.; Mahdi, M. A.

    2017-07-01

    In the present work, we report on the optical spectral properties of Er3+-doped zinc boro-aluminosilicate glasses with an addition of 10 mol % alkali/alkaline modifier regarding the fabrication of new optical materials for optical amplifiers. A total of 10 glasses were prepared using melt-quenching technique with the compositions (40-x)B2O3 - 10SiO2 - 10Al2O3 - 30ZnO - 10Li2O - xEr2O3 and (40-x)B2O3 - 10SiO2 - 10Al2O3 - 30ZnO - 10MgO - xEr2O3 (x = 0.1, 0.25, 0.5, 1.0, and 2.0 mol %). We confirm the amorphous-like structure for all the prepared glasses using X-ray diffraction (XRD). To study the functional groups of the glass composition after the melt-quenching process, Raman spectroscopy was used, and various structural units such as triangular and tetrahedral-borates (BO3 and BO4) have been identified. All the samples were characterized using optical absorption for UV, visible and NIR regions. Judd-Ofelt (JO) intensity parameters (Ωλ, λ = 2, 4 and 6) were calculated from the optical absorption spectra of two glasses LiEr 2.0 and MgEr 2.0 (doped with 2 mol % of Er3+). JO parameters for LiEr 2.0 and MgEr 2.0 glasses follow the trend as Ω6>Ω2>Ω4. Using Judd-Ofelt intensity parameters, we obtained radiative probability A (S-1), branching ratios (β), radiative decay lifetimes τrad (μs) of emissions from excited Er+3 ions in LiEr 2.0 and MgEr 2.0 to all lower levels. Quantum efficiency (η) of 4I13/2 and 4S3/2 levels for LiEr 2.0 and MgEr 2.0 with and without 4D7/2 level was calculated using the radiative decay lifetimes τrad. (μs) and measured lifetimes τexp. (μs). We measured the visible photoluminescence under 377 nm excitation for both LiEr and MgEr glass series within the region 390-580 nm. Three bands were observed in the visible region at 407 nm, 530 nm, and 554 nm, as a result of 2H9/2 → 4I15/2, 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions, respectively. Decay lifetimes for emissions at 407 nm, 530 nm, and 554 nm were measured and they show

  8. Formation of metallic cation-oxygen network for anomalous thermal expansion coefficients in binary phosphate glass.

    PubMed

    Onodera, Yohei; Kohara, Shinji; Masai, Hirokazu; Koreeda, Akitoshi; Okamura, Shun; Ohkubo, Takahiro

    2017-05-31

    Understanding glass structure is still challenging due to the result of disorder, although novel materials design on the basis of atomistic structure has been strongly demanded. Here we report on the atomic structures of the zinc phosphate glass determined by reverse Monte Carlo modelling based on diffraction and spectroscopic data. The zinc-rich glass exhibits the network formed by ZnO x (averaged x<4) polyhedra. Although the elastic modulus, refractive index and glass transition temperature of the zinc phosphate glass monotonically increase with the amount of ZnO, we find for the first time that the thermal expansion coefficient is very sensitive to the substitution of the phosphate chain network by a network consisting of Zn-O units in zinc-rich glass. Our results imply that the control of the structure of intermediate groups may enable new functionalities in the design of oxide glass materials.

  9. Formation of metallic cation-oxygen network for anomalous thermal expansion coefficients in binary phosphate glass

    NASA Astrophysics Data System (ADS)

    Onodera, Yohei; Kohara, Shinji; Masai, Hirokazu; Koreeda, Akitoshi; Okamura, Shun; Ohkubo, Takahiro

    2017-05-01

    Understanding glass structure is still challenging due to the result of disorder, although novel materials design on the basis of atomistic structure has been strongly demanded. Here we report on the atomic structures of the zinc phosphate glass determined by reverse Monte Carlo modelling based on diffraction and spectroscopic data. The zinc-rich glass exhibits the network formed by ZnOx (averaged x<4) polyhedra. Although the elastic modulus, refractive index and glass transition temperature of the zinc phosphate glass monotonically increase with the amount of ZnO, we find for the first time that the thermal expansion coefficient is very sensitive to the substitution of the phosphate chain network by a network consisting of Zn-O units in zinc-rich glass. Our results imply that the control of the structure of intermediate groups may enable new functionalities in the design of oxide glass materials.

  10. Synthesis and characterization of PbTiO3 based glass ceramics

    NASA Astrophysics Data System (ADS)

    Shankar, J.; Rani, G. Neeraja; Mamatha, B.; Deshpande, V. K.

    2017-05-01

    Glass samples with composition (50 - X) PbO - XCaO - 25 TiO2 - 25 B2O3 (where = 0, .5, 10 and 15 mol %) were prepared using conventional quenching technique. It was observed that with the addition of alkaline earth oxides to lead borate glass containing TiO2 alters the network (conversion of BO3 to BO4) increasing the rigidity of the glass which enhances the Tg. These glass samples were converted to glass ceramics by following two stage heat treatment schedule. The density values of glass ceramic samples are higher than those of corresponding glass samples. It was observed that there was good correlation between the density and CTE results of the glass-ceramics. The XRD results in the glass ceramics revealed the formation of tetragonal lead titanate as a major crystalline phase and Ca3Ti2O7 as minor crystalline phase. The ferroelectric nature of all the glass ceramic samples is confirmed by P - E hysteresis measurements.

  11. Cytotoxicity assessment of modified bioactive glasses with MLO-A5 osteogenic cells in vitro.

    PubMed

    Modglin, Vernon C; Brown, Roger F; Jung, Steven B; Day, Delbert E

    2013-05-01

    The primary objective of this study was to evaluate in vitro responses of MLO-A5 osteogenic cells to two modifications of the bioactive glass 13-93. The modified glasses, which were designed for use as cell support scaffolds and contained added boron to form the glasses 13-93 B1 and 13-93 B3, were made to accelerate formation of a bioactive hydroxyapatite surface layer and possibly enhance tissue growth. Quantitative MTT cytotoxicity tests revealed no inhibition of growth of MLO-A5 cells incubated with 13-93 glass extracts up to 10 mg/ml, moderate inhibition of growth with 13-93 B1 glass extracts, and noticeable inhibition of growth with 13-93 B3 glass extracts. A morphology-based biocompatibility test was also performed and yielded qualitative assessments of the relative biocompatibilities of glass extracts that agree with those obtained by the quantitative MTT test. However, as a proof of concept experiment, when MLO-A5 cells were seeded onto 13-93 B3 scaffolds in a dynamic in vitro environment, cell proliferation occurred as evidenced by qualitative and quantitative MTT labeling of scaffolds. Together these results demonstrate the in vitro toxicity of released borate ion in static experiments; however borate ion release can be mitigated in a dynamic environment similar to the human body where microvasculature is present. Here we argue that despite toxicity in static environments, boron-containing 13-93 compositions may warrant further study for use in tissue engineering applications.

  12. Experimental and theoretical approach on the optical properties of zinc borotellurite glass doped with dysprosium oxide.

    PubMed

    Halimah, M K; Ami Hazlin, M N; Muhammad, F D

    2018-04-15

    A series of glass samples with chemical formula {[(TeO 2 ) 0.7 (B 2 O 3 ) 0.3 ] 0.7 (ZnO) 0.3 } 1-x (Dy 2 O 3 ) x where x=0.01, 0.02, 0.03, 0.04 and 0.05M fraction were synthesized through conventional melt-quenching method. The most common way to fabricate a glass material is by fusion of two or more component oxides followed by their quenching. This technique is known as melt-quenching technique. Kaur et al. (2016) [1] highlighted that the melt-quenching method able to enhance the mechanical properties like hardness and flexural strength of the material. The nature of the glass systems is proven to be amorphous based on the XRD pattern. The FTIR spectra of the glass systems confirm the existence of five bands which are assigned for the BO 4 , BO 3, TeO 4 and TeO 3 vibrational groups. The density of the glass systems is increased with the addition of Dy 2 O 3 while the molar volume is found to be inversely proportional to the density of the proposed glass. The optical properties of the glasses are determined through the absorption spectra obtained from the UV-VIS spectrophotometer. From the absorption spectra, the indirect and direct optical band gaps and the Urbach energy are found to be inversely proportional to each other. As the molar fraction of the Dy 2 O 3 increased, the optical band gaps are observed to increase as opposed to the Urbach energy. For this glass system, the values of refractive index, electronic polarizability, oxide ion polarizability and the optical basicity are found to decrease as the addition of the dysprosium oxide is increased. From the emission spectra, two intense blue and yellow emission bands are observed, which correspond to the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions of Dy 3+ ions respectively. The CIE chromaticity coordinates of the zinc borotellurite glass systems are found to be located in the white light region. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Using neutrons, X-rays and nuclear magnetism to determine the role of transition metal oxide inclusions on both glass structure and stability in automotive glass enamels.

    PubMed

    Bowron, Daniel T; Booth, Jonathan; Barrow, Nathan S; Sutton, Patricia; Johnson, Simon R

    2018-05-23

    Low levels of transition metal oxides in alkali borosilicate glass systems can drastically influence crystallisation and phase separation properties. We investigated the non-monotonic effect of manganese doping on suppressing crystallisation, and the influence on optical properties by iron oxide doping, in terms of local atomic structure. Structural models based on empirical potential structure refinement were generated from neutron and X-ray scattering data, and compared against multinuclear solid-state NMR. This revealed that a 2.5% manganese doping had a disruptive effect on the entire glass network, supressing crystallisation of an undesired bismuth silicate phase, and that iron species preferentially locate near borate tetrahedra. Preventing phase separation and controlling crystallisation behaviour of glass are critical to the ultimate properties of automotive glass enamels.

  14. Experimental insights on the electron transfer and energy transfer processes between Ce{sup 3+}-Yb{sup 3+} and Ce{sup 3+}-Tb{sup 3+} in borate glass

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sontakke, Atul D., E-mail: sontakke.atul.55a@st.kyoto-u.ac.jp; Katayama, Yumiko; Tanabe, Setsuhisa

    2015-03-30

    A facile method to describe the electron transfer and energy transfer processes among lanthanide ions is presented based on the temperature dependent donor luminescence decay kinetics. The electron transfer process in Ce{sup 3+}-Yb{sup 3+} exhibits a steady rise with temperature, whereas the Ce{sup 3+}-Tb{sup 3+} energy transfer remains nearly unaffected. This feature has been investigated using the rate equation modeling and a methodology for the quantitative estimation of interaction parameters is presented. Moreover, the overall consequences of electron transfer and energy transfer process on donor-acceptor luminescence behavior, quantum efficiency, and donor luminescence decay kinetics are discussed in borate glass host.more » The results in this study propose a straight forward approach to distinguish the electron transfer and energy transfer processes between lanthanide ions in dielectric hosts, which is highly advantageous in view of the recent developments on lanthanide doped materials for spectral conversion, persistent luminescence, and related applications.« less

  15. Effect of certain alkaline metals on Pr doped glasses to investigate spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Lenkennavar Susheela, K.; Madhu, A.; Eraiah, B.; Kokila, M. K.

    2018-02-01

    Incorporation of different Alkaline earth metal like Barium, Calcium and strontium in sodium lead borate glass doped with Pr3+ is studied. Physical parameters such as density, molar volume, molar refractivity etc have been evaluated. Effect of different atomic size of alkaline metal using optical and physical parameters is analysed. XRD and FTIR were carried out to know the structural behaviour of the glasses. Absorption and Emission spectra are recorded at room temperature and the results were discussed.

  16. Understanding the structural drivers governing glass-water interactions in borosilicate based model bioactive glasses.

    PubMed

    Stone-Weiss, Nicholas; Pierce, Eric M; Youngman, Randall E; Gulbiten, Ozgur; Smith, Nicholas J; Du, Jincheng; Goel, Ashutosh

    2018-01-01

    The past decade has witnessed a significant upsurge in the development of borate and borosilicate based resorbable bioactive glasses owing to their faster degradation rate in comparison to their silicate counterparts. However, due to our lack of understanding about the fundamental science governing the aqueous corrosion of these glasses, most of the borate/borosilicate based bioactive glasses reported in the literature have been designed by "trial-and-error" approach. With an ever-increasing demand for their application in treating a broad spectrum of non-skeletal health problems, it is becoming increasingly difficult to design advanced glass formulations using the same conventional approach. Therefore, a paradigm shift from the "trial-and-error" approach to "materials-by-design" approach is required to develop new-generations of bioactive glasses with controlled release of functional ions tailored for specific patients and disease states, whereby material functions and properties can be predicted from first principles. Realizing this goal, however, requires a thorough understanding of the complex sequence of reactions that control the dissolution kinetics of bioactive glasses and the structural drivers that govern them. While there is a considerable amount of literature published on chemical dissolution behavior and apatite-forming ability of potentially bioactive glasses, the majority of this literature has been produced on silicate glass chemistries using different experimental and measurement protocols. It follows that inter-comparison of different datasets reveals inconsistencies between experimental groups. There are also some major experimental challenges or choices that need to be carefully navigated to unearth the mechanisms governing the chemical degradation behavior and kinetics of boron-containing bioactive glasses, and to accurately determine the composition-structure-property relationships. In order to address these challenges, a simplified

  17. Corrosion studies of titanium in borated water for TPX

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wilson, D.F.; Pawel, S.J.; DeVan, J.H.

    1995-12-31

    Corrosion testing was performed to demonstrate the compatibility of the titanium vacuum vessel with borated water. Borated water is proposed to fill the annulus of the double wall vacuum vessel to provide effective radiation shielding. Borating the water with 110 grams of boric acid per liter is sufficient to reduce the nuclear heating in the Toroidal Field Coil set and limit the activation of components external to the vacuum vessel. Constant extension rate tensile (CERT) and electrochemical potentiodynamic tests were performed. Results of the CERT tests confirm that stress corrosion cracking is not significant for Ti-6Al4V or Ti-3AI-2.5V. Welded andmore » unwelded specimens were tested in air and in borated water at 150{degree}C. Strength, elongation, and time to failure were nearly identical for all test conditions, and all the samples exhibited ductile failure. Potentiodynamic tests on Ti-6A1-4V and Ti in borated water as a function of temperature showed low corrosion rates over a wide passive potential range. Further, this passivity appeared stable to anodic potentials substantially greater than those expected from MHD effects.« less

  18. Ternary borate-nucleoside complex stabilization by Ribonuclease A demonstrates phosphate mimicry

    PubMed Central

    Gabel, Scott A.; London, Robert E.

    2010-01-01

    Phosphate esters play a central role in cellular energetics, biochemical activation, signal transduction and conformational switching. The structural homology of the borate anion with phosphate, combined with its ability to spontaneously esterify hydroxyl groups, suggested that phosphate-ester recognition sites on proteins might exhibit significant affinity for non-enzymatically formed borate esters. 11B NMR studies and activity measurements on ribonuclease A in the presence of borate and several cytidine analogs demonstrate the formation of a stable ternary RNase A•3′-deoxycytidine-2′-borate ternary complex that mimics the complex formed between RNase A and a 2′-cytidine monophosphate (2′-CMP) inhibitor. Alternatively, no slowly exchanging borate resonance is observed for a ternary RNase A, borate, 2′-deoxycytidine mixture, demonstrating the critical importance of the 2′-hydroxyl group for complex formation. Titration of the ternary complex with 2′-CMP shows that it can displace the bound borate ester with a binding constant that is close to the reported inhibition constant of RNase A by 2′CMP. RNase A binding of a cyclic cytidine-2′,3′-borate ester, which is a structural homolog of the cytidine-2′,3′-cyclic phosphate substrate, could also be demonstrated. The apparent dissociation constant for the cytidine-2′,3′-borate•RNase A complex is 0.8 mM, which compares with a Michaelis constant of 11 mM for cCMP at pH 7, indicating considerably stronger binding. However, the value is 1000-fold larger than the reported dissociation constant of the RNase A complex with uridine-vanadate. These results are consistent with recent reports suggesting that in situ formation of borate esters that mimic the corresponding phosphate esters support enzyme catalysis. PMID:17957392

  19. Impedance spectroscopic characterization of Sm2O3 containing lithium borate glasses.

    PubMed

    Ramteke, D D; Gedam, R S

    2014-12-10

    27.5 Li2O-(72.5-X) B2O3-X Sm2O3 (X=0.5, 1, 1.5 and 2) were prepared by conventional melt quench technique. Impedance spectroscopy (IS) is used to study the electrical properties of these prepared glasses. Modulus formalism is introduced to study relaxation behaviour of these glasses. Scaling model shows the good overlap of data on single master curve which suggests that conduction mechanism in these glasses is compositional dependent. Variation of dielectric constant and dielectric loss with the addition of Sm2O3 and frequency are discussed here. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Gamma-ray shielding effect of Gd3+ doped lead barium borate glasses

    NASA Astrophysics Data System (ADS)

    Kummathi, Harshitha; Naveen Kumar, P.; Vedavathi T., C.; Abhiram, J.; Rajaramakrishna, R.

    2018-05-01

    The glasses of the batch xPbO: 10BaO: (90-x)B2O3: 0.2Gd2O3 (x = 40,45,50 mol %) were prepared by melt-quench technique. The work emphasizes on gamma ray shielding effect on doped lead glasses. The role of Boron is significant as it acts as better neutron attenuator as compared with any other materials, as the thermal neutron cross-sections are high for Gadolinium, 0.2 mol% is chosen as the optimum concentration for this matrix, as higher the concentration may lead to further increase as it produces secondary γ rays due to inelastic neutron scattering. Shielding effects were studied using Sodium Iodide (NaI) - Scintillation Gamma ray spectrometer. It was found that at higher concentration of lead oxide (PbO) in the matrix, higher the attenuation which can be co-related with density. Infra-red (I.R.) spectra reveals that the conversion of Lose triangles to tight tetrahedral structure results in enhancement of shielding properties. The Differential Scanning Calorimeter (D.S.C.) study also reveals that the increase in glass forming range increases the stability which in-turn results in inter-conversion of BO3 to BO4 units such that the density of glass increases with increase in PbO content, resulting in much stable and efficient gamma ray shielding glasses.

  1. Green colorants based on energetic azole borates.

    PubMed

    Glück, Johann; Klapötke, Thomas M; Rusan, Magdalena; Stierstorfer, Jörg

    2014-11-24

    The investigation of green-burning boron-based compounds as colorants in pyrotechnic formulations as alternative for barium nitrate, which is a hazard to health and to the environment, is reported. Metal-free and nitrogen-rich dihydrobis(5-aminotetrazolyl)borate salts and dihydrobis(1,3,4-triazolyl)borate salts have been synthesized and characterized by NMR spectroscopy, elemental analysis, mass spectrometry, and vibrational spectroscopy. Their thermal and energetic properties have been determined as well. Several pyrotechnic compositions using selected azolyl borate salts as green colorants were investigated. Formulations with ammonium dinitramide and ammonium nitrate as oxidizers and boron and magnesium as fuels were tested. The burn time, dominant wavelength, spectral purity, luminous intensity, and luminous efficiency as well as the thermal and energetic properties of these compositions were measured. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Effect of mixed transition metal ions on DC conductivity in lithium bismuth borate glasses

    NASA Astrophysics Data System (ADS)

    Khasa, S.; Yadav, Arti; Dahiya, M. S.; Seema, Ashima, Agarwal, A.

    2015-06-01

    The DC conductivities of glasses having composition x(2NiO.V2O5).(30-x)Li2O.20Bi2O3.50B2O3 (with x=0, 2, 5, 7 and 10, i.e. NVLBB glasses) and glass samples having composition 7NiO.23 Li2O.20Bi2O3.50B2O3 and 7V2O5.23Li2O.20Bi2O3.50B2O3 (NLBB and VLBB respectively) are investigated as a function of temperature. Conductivity for glasses containing higher percentage of lithium ions is predominantly ionic and in glasses containing higher percentage of transition metal (TM) ions is predominantly electronic. The observed increase in conductivity with x and peak-like behavior at x=7 in NVLBB glasses due to competitive transport of small polaron contributing to a significant structural change in NVLBB glasses. Variation of molar volume and density was also observed with x. In NVLBB glasses, as x increases density increases except a slight decrease at x=7. Also density increases in NLBB whereas in case of VLBB it decreases in comparison to NVLBB1 glass composition. Mott's small polaron hopping (SPH) model has been applied to analyze the high temperature conductivity data and activation energy.

  3. Boron environments in Pyrex® glass--a high resolution, Double-Rotation NMR and thermodynamic modelling study.

    PubMed

    Howes, A P; Vedishcheva, N M; Samoson, A; Hanna, J V; Smith, M E; Holland, D; Dupree, R

    2011-07-07

    It is shown, using the important technological glass Pyrex® as an example, that 1D and 2D (11)B Double-Rotation (DOR) NMR experiments, in combination with thermodynamic modelling, are able to provide unique structural information about complex glasses. (11)B DOR NMR has been applied to Pyrex® glass in order to remove both dipolar and quadrupolar broadening of the NMR lines, leading to high resolution spectra that allow unambiguous, accurate peak fitting to be carried out, of particular importance in the case of the 3-coordinated [BO(3)] (B3) trigonal planar environments. The data obtained are of sufficient quality that they can be used to test the distributions of borate and borosilicate superstructural units predicted by the thermodynamics-based Model of Associated Solutions. The model predicts the dominant boron-containing chemical groupings in Pyrex® glass to be those associated with B(2)O(3) and sodium tetraborate (with smaller amounts of sodium triborate, sodium diborate, sodium pentaborate, danburite and reedmergnerite). Excellent agreement is found between model and experiment provided the (11)B peaks with isotropic chemical shifts of -1.4 ppm and 0.5 ppm are assigned to B4 species from borosilicate units ([B(OSi)(4)] and [B(OSi)(3)(OB)]) and borate superstructural units (mainly triborate rings with some pentaborate and diborate) respectively. The peaks with isotropic shifts of 14 ppm and 18.1 ppm are then assigned to B3 in borate superstructural units (mainly triborate and pentaborate along with connecting B3) and boroxol rings respectively. The assignments of the DOR NMR peaks, are supported by the presence of cross-peaks in (11)B spin-diffusion DOR NMR spectra which can be used to develop a structural model in which B(2)O(3)-like regions are linked, via borate and borosilicate superstructural units, to the majority silica network. Pyrex® is thus shown to have a heterogeneous structure, with distinct molecular groupings that are far removed from a

  4. Spectroscopic study of Pr3+ ions doped Zinc Lead Tungsten Tellurite glasses for visible photonic device applications

    NASA Astrophysics Data System (ADS)

    Sharma, Ritu; Rao, A. S.; Deopa, Nisha; Venkateswarlu, M.; Jayasimhadri, M.; Haranath, D.; Prakash, G. Vijaya

    2018-04-01

    Zinc Lead Tungsten Tellurite (ZnPbWTe) glasses doped with different Pr3+ ion concentrations having the composition 5ZnO + 15PbO + 20WO3 + (60-x)TeO2 + xPr6O11 (where x = 0.5, 1, 1.5, 2.0 and 2.5 mol%) were prepared by using sudden quenching technique and characterized to understand their visible emission characteristic features using spectroscopic techniques such as absorption, excitation and emission. The Judd-Ofelt (J-O) theory has been applied to the absorption spectral features with an aim to evaluate various radiative properties for the prominent fluorescent levels of Pr3+ions in the as-prepared glasses. The emission spectra recorded for the as-prepared glasses under 468 nm excitation show three prominent emission transitions 3P0→3H6, 3P0→3F2 and 3P1→3F4, of which 3P0→3F2 observed in visible red region (648 nm), is relatively more intense. The intensity of 3P0→3F2 emission transition in the titled glasses increases up to 1mol% of Pr3+ ions and beyond concentration quenching is observed. Branching ratios (βR) and emission cross-sections (σse) were estimated for 3P0→3F2 transition to understand the luminescence efficiency in visible red region (648 nm). The CIE chromaticity coordinates were also evaluated in order to understand the suitability of these glasses for visible red luminescence devices. From the emission cross-sections, quantum efficiency and CIE coordinates, it was concluded that 1mol% of Pr3+ ions in ZnPbWTe glasses are quite suitable for preparing visible reddish orange luminescent devices.

  5. Luminescence properties of erbium doped sodium barium borate glass with silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Rajeshree Patwari, D.; Eraiah, B.

    2018-02-01

    Alteration in the absorption features of rare earth (RE) doped glasses with silver nanoparticles is ever-challenging in photonics. Erbium (Er3+) doped glasses with composition (60-x-y)B2O3-30Na2CO3-10BaO-xEr2O3-yAgCl where (x=0.5, 1.0 and y=1.0 mol %) are synthesized using melt-quenching method. The density is determined by Archimedes principle and molar volumes are calculated. Glass samples were characterized by XRD and UV-Visible spectroscopy. UV-Visible spectra shows eleven prominent absorption peaks centred around 366, 378, 408, 442, 452, 489, 521, 547, 652, 800 and 977 nm equivalent to the rare earth (Er3+) ion transitions. The sample without rare earth shows no peaks which specifies that rare earth ion plays a spirited role in the glass matrix. The glass samples with silver and without rare earth ion shows plasmon peak on heat treatment. The energy band gap values calculated for direct and indirect transitions are in the range of 3.126-3.440eV and 2.58-3.177eV respectively. The refractive indices and Urbach energies are also determined. Photoluminescence spectra are recorded and studied for excitation of the most intense peaks of wavelengths 378 and 521nm. The luminescence of erbium ion is enhanced by the presence of silver when the concentration of rare earth ion is less than that of silver.

  6. Emission properties of Ce-doped alkaline earth borate glasses for scintillator applications

    NASA Astrophysics Data System (ADS)

    Torimoto, Aya; Masai, Hirokazu; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

    2017-11-01

    We investigate the photoluminescence (PL) and X-ray-induced luminescence properties of 0.1 mol% Ce-doped MO-B2O3 (M = Ca, Sr, and Ba) glasses. We also determine the Ce3+/(Ce3++Ce4+) ratio by X-ray absorption near-edge structure analyses. The emission intensities of PL, X-ray scintillation, and thermally stimulated luminescence (TSL) depend on the host glass composition. The order of the PL intensity from highest to lowest is as follows: Ca-substituted glass, Ba-substituted glass, and Sr-substituted glass. Our results suggest that the optical absorption edge and quantum yield (QY) are influenced by the local coordination state of Ce3+, which, in turn, is likely to be affected by the optical basicity. The order of the X-ray scintillation intensity from highest to lowest is reverse of that of the PL intensity. This is probably because the interaction probability of X-rays with matter depends on the effective atomic number of the material and the effective atomic number has a stronger influence on the scintillation intensity than does the QY. Though the TSL glow curves reveal that the density and energy depth of the trap sites depend on the substituted alkaline earth oxides, we are unable to correlate the electron spin resonance (ESR) spectra with the TSL results. Therefore, it is considered that the ESR active sites are not responsible for the TSL in these systems.

  7. Optical properties of zinc lead tellurite glasses

    NASA Astrophysics Data System (ADS)

    Alazoumi, Salah Hassan; Aziz, Sidek Abdul; El-Mallawany, R.; Aliyu, Umar Sa'ad; Kamari, Halimah Mohamed; Zaid, Mohd Hafiz Mohd Mohd; Matori, Khamirul Amin; Ushah, Abdulbaset

    2018-06-01

    Tellurite glass systems in the form of [ZnO]x [(TeO2)0.7-(PbO)0.3]1-x with x = 0.15, 0.17, 0.20, 0.22 and 0.25 mol% were prepared using the melt quenching technique. XRD of the prepared samples have been measured for all samples. Both FTIR (280-4000 cm-1) and UV-Vis (200-800 nm) spectra have been measured. Optical band gap and refractive index were calculated for every glass sample. Density of glass, molar volume and oxygen packing density (OPD) were obtained. Values of the direct, indirect band gap ranged were found in the range 3.41-3.94 eV and 2.40-2.63 eV with increasing of ZnO concentration. Refractive index 2.58 and dielectric constant 6.66 were heigh at 17 ZnO mol% concentration. Molar polarizability, metallization criterion, polaron radius have been calculated for every glass composition.

  8. Disordered Zinc in Zn4Sb3 with Phonon-Glass and Electron-Crystal Thermoelectric Properties

    NASA Technical Reports Server (NTRS)

    Snyder, G. Jeffrey; Christensen, Mogens; Nishibori, Eiji; Caillat, Thierry; Brummerstedt Iversen, Bo

    2004-01-01

    By converting waste heat into electricity, thermoelectric generators could be an important part of the solution to today's energy challenges. The compound Zn4Sb3 is one of the most efficient thermoelectric materials known. Its high efficiency results from an extraordinarily low thermal conductivity in conjunction with the electronic structure of a heavily doped semiconductor. Previous structural studies have been unable to explain this unusual combination of properties. Here, we show through a comprehensive structural analysis using single-crystal X-ray and powder-synchrotron-radiation diffraction methods, that both the electronic and thermal properties of Zn4Sb3 can be understood in terms of unique structural features that have been previously overlooked. The identification of Sb3- ions and Sb-2(4-) dimers reveals that Zn4Sb3 is a valence semiconductor with the ideal stoichiometry Zn13Sb10. In addition, the structure contains significant disorder, with zinc atoms distributed over multiple positions. The discovery of glass-like interstitial sites uncovers a highly effective mechanism for reducing thermal conductivity. Thus Zn4Sb3 is in many ways an ideal 'phonon glass, electron crystal' thermoelectric material.

  9. Fabrication and characterization of poly-(ε)-caprolactone and bioactive glass composites for tissue engineering applications.

    PubMed

    Mohammadkhah, Ali; Marquardt, Laura M; Sakiyama-Elbert, Shelly E; Day, Delbert E; Harkins, Amy B

    2015-04-01

    Much work has focused on developing synthetic materials that have tailored degradation profiles and physical properties that may prove useful in developing biomaterials for tissue engineering applications. In the present study, three different composite sheets consisting of biodegradable poly-ε-caprolactone (PCL) and varying types of bioactive glass were investigated. The three composites were composed of 50wt.% PCL and (1) 50wt.% 13-93 B3 borate glass particles, (2) 50wt.% 45S5 silicate glass particles, or (3) a blend of 25wt.% 13-93 B3 and 25wt.% 45S5 glass particles. Degradation profiles determined for each composite showed the composite that contained only 13-93 B3 borate glass had a higher degradation rate compared to the composite containing only 45S5 silicate glass. Uniaxial tensile tests were performed on the composites to determine the effect of adding glass to the polymer on mechanical properties. The peak stress of all of the composites was lower than that of PCL alone, but 100% PCL had a higher stiffness when pre-reacted in cell media for 6weeks, whereas composite sheets did not. Finally, to determine whether the composite sheets would maintain neuronal growth, dorsal root ganglia isolated from embryonic chicks were cultured on composite sheets, and neurite outgrowth was measured. The bioactive glass particles added to the composites showed no negative effects on neurite extension, and neurite extension increased on PCL:45S5 PCL:13-93 B3 when pre-reacted in media for 24h. This work shows that composite sheets of PCL and bioactive glass particles provide a flexible biomaterial for neural tissue engineering applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Mineralogy and sedimentology of the Miocene Göcenoluk borate deposit, Kırka district, western Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    García-Veigas, Javier; Helvacı, Cahit

    2013-05-01

    The Miocene boratiferous district of Kırka, in western Anatolia (Turkey), is the most important Na-borate (borax) resource in the world. Two separate deposits in the Kırka district are located near the villages of Sarıkaya and Göcenoluk (Eskişehir Province). Borax is intensively exploited in open-pit mines in the Sarıkaya deposit while only small quarries of colemanite are known in the Göcenoluk deposit. Recent exploratory drilling in the Göcenoluk area intersected a thick succession of dolostones, tuffs and three borate-bearing units (Lower, Intermediate and Upper Borate Units). In them, the most abundant borate mineral is ulexite (Ca-Na-borate) passing at depth to probertite. Borax (Na-borate) is only present in the Intermediate Borate Unit. Minor amounts of colemanite (Ca-borate) and hydroboracite (Ca-Mg-borate) occur at the base, and/or top, of each mineralized unit. Pyroclastic layers within the borate units show intense alteration by alkaline, boron-bearing waters and formation of diagenetic clay minerals (smectites), zeolites (analcime) and borosilicates (searlesite). The Göcenoluk succession is interpreted as a shallow, ephemeral, alkaline lake deposit in which carbonates formed as stromatolites and travertines. Borate precipitation in the Göcenoluk area took place interstitially within muddy and carbonate sediments in a lateral progression from marginal Ca-borates towards Na-Ca-borates and rarely to Na-borates in the center of the lake. Authigenic silicate mineral distribution shows parallel changes toward the center of the lake that reflect increasing pH gradient.

  11. Synthesis, characterization, bioactivity and antibacterial studies of silver doped calcium borosilicate glass-ceramics

    NASA Astrophysics Data System (ADS)

    Kumar, Alesh; Mariappan, C. R.

    2018-04-01

    Bioactive glass-ceramics 45.8 mol% SiO- 45.8 CaO - 8.4 B2O3 doped with Ag2O were synthesized by sol-gel method. The glass-ceramic nature of samples was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. Fourier transform infrared (FT-IR) spectra reveal the probable stretching and bending vibration modes of silicate and borate groups. UV-Visible spectra reveal the presence of Ag+ ions and metallic Ag in the glass matrix for Ag2O doped ceramic sample. Biocompatibility of the glass nature of samples was studied by soaking of samples in Dulbecco's Modified Eagle's Medium (DMEM) with subsequent XRD studies. It was found that bone-like apatite formation on the glasses after soaked in DMEM. Antibacterial studies of glass ceramics powder against gram positive and negative microorganisms were carried out.

  12. Multisample conversion of water to hydrogen by zinc for stable isotope determination

    USGS Publications Warehouse

    Kendall, C.; Coplen, T.B.

    1985-01-01

    Two techniques for the conversion of water to hydrogen for stable isotope ratio determination have been developed that are especially suited for automated multisample analysis. Both procedures involve reaction of zinc shot with a water sample at 450 ??C. in one method designed for water samples in bottles, the water is put in capillaries and is reduced by zinc in reaction vessels; overall savings in sample preparation labor of 75% have been realized over the standard uranium reduction technique. The second technique is for waters evolved under vacuum and is a sealed-tube method employing 9 mm o.d. quartz tubing. Problems inherent with zinc reduction include surface inhomogeneity of the zinc and exchange of hydrogen both with the zinc and with the glass walls of the vessels. For best results, water/zinc and water/glass surface area ratios of vessels should be kept as large as possible.

  13. Low-energy collisionally activated dissociation of pentose-borate complexes

    NASA Astrophysics Data System (ADS)

    Pepi, Federico; Garzoli, Stefania; Tata, Alessandra; Giacomello, Pierluigi

    2010-01-01

    Pentose-borate 1:1 complexes were generated in the ESI source of a triple quadrupole and ion trap mass spectrometer by electrospray ionization of Na2B4O7 and pentose (arabinose, lyxose, ribose, xylose) 2:1 solution in CH3CN/H2O. The study of their low-energy collisionally activated dissociation (CAD) demonstrated that ribose and lyxose are preferentially complexed at the C2-C3 cis-diol function whereas arabinose and xylose are esterified at the C1-C2 hydroxyl groups. No evidence was found of the stronger affinity for ribose to borate. The ribose probiotic rule can be explained by considering its peculiar capability, among the investigated pentoses, to almost totally complex the borate anion at the C2-C3 hydroxyl group, thus enabling the subsequent stages of nucleotide assembly, such as phosphorylation and linkage to the nucleobases. Finally, the differences observed in the pentose-borate complex CAD spectra can be used for the mass spectrometric discrimination of isomeric pentoses in complex mixtures.

  14. Structural investigation and electron paramagnetic resonance of vanadyl doped alkali niobium borate glasses.

    PubMed

    Agarwal, A; Sheoran, A; Sanghi, S; Bhatnagar, V; Gupta, S K; Arora, M

    2010-03-01

    Glasses with compositions xNb(2)O(5).(30-x)M(2)O.69B(2)O(3) (where M=Li, Na, K; x=0, 4, 8 mol%) doped with 1 mol% V(2)O(5) have been prepared using normal melt quench technique. The IR transmission spectra of the glasses have been studied over the range 400-4000 cm(-1). The changes caused by the addition of Nb(2)O(5) on the structure of these glasses have been reported. The electron paramagnetic resonance spectra of VO(2+) ions in these glasses have been recorded in X-band (9.14 GHz) at room temperature (300 K). The spin Hamiltonian parameters, dipolar hyperfine coupling parameter and Fermi contact interaction parameter have been calculated. It is observed that the resultant resonance spectra contain hyperfine structures (hfs) due to V(4+) ions which exist as VO(2+) ions in octahedral coordination with a tetragonal compression in the present glasses. The tetragonality of V(4+)O(6) complex decreases with increasing concentration of Nb(2)O(5). The 3d(xy) orbit contracts with increase in Nb(2)O(5):M(2)O ratio. Values of the theoretical optical basicity, Lambda(th), have also been reported. Copyright 2009 Elsevier B.V. All rights reserved.

  15. Thin transparent W-doped indium-zinc oxide (WIZO) layer on glass.

    PubMed

    Lee, Young-Jun; Lim, Byung-Wook; Kim, Joo-Hyung; Kim, Tae-Won; Oh, Byeong-Yun; Heo, Gi-Seok; Kim, Kwang-Young

    2012-07-01

    Annealing effect on structural and electrical properties of W-doped IZO (WIZO) films for thin film transistors (TFT) was studied under different process conditions. Thin WIZO films were deposited on glass substrates by RF magnetron co-sputtering technique using indium zinc oxide (10 wt.% ZnO-doped In2O3) and WO3 targets in room temperature. The post annealing temperature was executed from 200 degrees C to 500 degrees C under various O2/Ar ratios. We could not find any big difference from the surface observation of as grown films while it was found that the carrier density and sheet resistance of WIZO films were controlled by O2/Ar ratio and post annealing temperature. Furthermore, the crystallinity of WIZO film was changed as annealing temperature increased, resulting in amorphous structure at the annealing temperature of 200 degrees C, while clear In2O3 peak was observed for the annealed over 300 degrees C. The transmittance of as-grown films over 89% in visible range was obtained. As an active channel layer for TFT, it was found that the variation of resistivity, carrier density and mobility concentration of WIZO film decreased by annealing process.

  16. Antibacterial and osteo-stimulatory effects of a borate-based glass series doped with strontium ions.

    PubMed

    Li, Yiming; Stone, Wendy; Schemitsch, Emil H; Zalzal, Paul; Papini, Marcello; Waldman, Stephen D; Towler, Mark R

    2016-11-01

    This work considered the effect of both increasing additions of Strontium (Sr 2+ ) and incubation time on solubility and both antibacterial and osteo-stimulatory effects of a series of glasses based on the B 2 O 3 -P 2 O 5 -CaCO 3 -Na 2 CO 3 -TiO 2 -SrCO 3 series. The amorphous nature of all the glasses was confirmed by X-ray diffraction. Discs of each glass were immersed in de-ionized water for 1, 7 and 30 days, and the water extracts were used for ion release profiles, pH measurements and cytotoxicity testing. Atomic absorption spectroscopy was employed to detect the release of Na + , Ca 2+ and Sr 2+ ions from the glasses with respect to maturation, which indicated that the addition of Sr 2+ retarded solubility of the glass series. This effect was also confirmed by weight loss analysis through comparing the initial weight of glass discs before and after periods of incubation. The incorporation of Sr 2+ in the glasses did not influence the pH of the water extracts when the glasses were stored for up to 30 days. Cytotoxicity testing with an osteoblastic cell line (MC3T3-E1) indicated that glasses with the higher (20 mol% and 25 mol%) Sr 2+ incorporation promoted proliferation of osteoblast cells, while the glasses with lower Sr 2+ contents inhibited cell growth. The glass series, except for Ly-B5 (which contained the highest Sr 2+ incorporation; 25 mol%), were bacteriostatic against S. aureus in the short term (1-7 days) as a result of the dissolution products released. © The Author(s) 2016.

  17. Combined effects of lithium and borate ions on the hydration of calcium sulfoaluminate cement

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cau Dit Coumes, Céline, E-mail: celine.cau-dit-coumes@cea.fr; Dhoury, Mélanie; Champenois, Jean-Baptiste

    This work investigates the combined influence of borate and lithium ions on the hydration of two calcium sulfoaluminate (CSA) cements containing 0 or 10 wt% gypsum. On the one hand, borates are known to retard CSA cement hydration due to the rapid precipitation of ulexite. On the other hand, lithium ions accelerate CSA cement hydration thanks to the fast precipitation of Li-containing aluminum hydroxide. When borates and lithium are present simultaneously, these two mechanisms are superimposed. With a gypsum-free cement, a third process is additionally observed: lithium promotes the initial precipitation of a borated AFm phase which is later convertedmore » into a borated AFt phase when hydration accelerates. Lithium salts can counteract the retardation by sodium borate. However, their influence is limited once a sufficient amount of Li-containing Al(OH){sub 3} seeds is formed. For the CSA cements under investigation, the threshold lithium concentration is close to 0.03 mmol/g of cement and similar with or without borate.« less

  18. Amount of leachant and water absorption levels of wood treated with borates and water repellents.

    PubMed

    Baysal, Ergun; Sonmez, Abdullah; Colak, Mehmet; Toker, Hilmi

    2006-12-01

    Wood protection efficacy of borates against biological agents, flame retardancy, and suitability to the environment is well known. Since borates can be applied to timber as water based solutions, they are preferred economically as well. Even though they are highly mobile in wood, boron compounds are widely used in timber preservation. Borates migrate in liquid and increase the hygroscopicity of wood in damp conditions. This study deals with the physical restriction of water access in wood by impregnating water repellent agents into wood to limit amount of leachant and water absorption levels of wood after boron treatment. Borates were incorporated with polyethylene glycol-400 (PEG-400) their bulking effect in wood was considered. Results indicated that the amount of leachates from wood treated with borates in PEG-400 was remarkably higher compared to those of wood treated with the aqueous solutions of borates. Water absorption (WA) levels of wood treated with aqueous solutions of borates were higher than those of their treated samples with the solutions in PEG-400. Secondary treatments of wood with the water repellent (WR) chemicals following borate impregnation reduced the leaching of chemicals from wood in water and also WA of the specimens were less than those of the wood treated with only borates from aqueous and PEG solutions. Styrene (St) was the most effective monomer among the other agents used in terms of immobility effect on borates and WA.

  19. Three-dimensional zinc incorporated borosilicate bioactive glass scaffolds for rodent critical-sized calvarial defects repair and regeneration.

    PubMed

    Wang, Hui; Zhao, Shichang; Xiao, Wei; Cui, Xu; Huang, Wenhai; Rahaman, Mohamed N; Zhang, Changqing; Wang, Deping

    2015-06-01

    The biomaterials with high osteogenic ability are being intensively investigated. In this study, we evaluated the bioactivity and osteogenesis of BG-Zn scaffolds in vitro and in vivo with a rodent calvarial defects model. Zinc containing borosilicate bioactive glass was prepared by doping glass with 1.5, 5 and 10 wt.% ZnO (denoted as BG-1.5Zn, BG-5Zn and BG-10Zn, respectively). When immersed in simulated body fluid, dopant ZnO retarded the degradation process, but did not affect the formation of hydroxyapatite (HA) after long-period soaking. BG-Zn scaffolds showed controlled release of Zn ions into the medium for over 8 weeks. Human bone marrow derived stem cells (hBMSCs) attached well on the BG-1.5Zn and BG-5Zn scaffolds, which exhibited no cytotoxicity to hBMSCs. In addition, the alkaline phosphatase activity of the hBMSCs increased with increasing dopant amount in the glass, while the BG-10Zn group showed over-dose of Zn. Furthermore, when implanted in rat calvarial defects for 8 weeks, the BG-5Zn scaffolds showed a significantly better capacity to regenerate bone tissue compared to the non-doping scaffolds. Generally, these results showed the BG-Zn scaffolds with high osteogenic capacity will be promising candidates using in bone tissue repair and regeneration. Copyright © 2015. Published by Elsevier B.V.

  20. Investigations on the spectroscopic properties of Dy3 + ions doped Zinc calcium tellurofluoroborate glasses

    NASA Astrophysics Data System (ADS)

    Karthikeyan, P.; Arunkumar, S.; Annapoorani, K.; Marimuthu, K.

    2018-03-01

    A new series of Dy3 + doped (30-x)B2O3 + 30TeO2 + 20CaCO3 + 10ZnO + 10ZnF2 + xDy2O3 (x = 0.01, 0.1, 0.5, 1, 2 and 3 in wt%) Zinc calcium tellurofluoroborate glasses were prepared and their structural, luminescence and excited state dynamics have been studied and reported. The structural properties have been characterized through XRD and FTIR studies to confirm the amorphous nature and to explore the presence of fundamental stretching vibrations. The bonding parameters (δ and β), optical band gap, Urbach's energy, oscillator strengths and Judd-Ofelt (JO) intensity parameters were calculated from the absorption spectra. The JO intensity parameters and the Y/B intensity ratio values have been used to explore the nature of the bonding and asymmetry around the Dy-ligand field environment. The luminescence properties of the present Dy3 + doped glasses have been analyzed through luminescence excited state dynamics and radiative properties such as transition probability (A), stimulated emission cross-section (σPE) branching ratio (β) and radiative lifetime (τR) values. The combination of dominant blue (4F9/2 → 6H15/2) and yellow (4F9/2 → 6H13/2) emissions generates white light emission in the CIE chromaticity diagram thus suggests that the present Dy3 + doped glasses are suitable for white light applications. The lifetime of the 4F9/2 excited state is found to decrease with the increase in Dy3 + ion content and the concentration quenching of the Dy3 + ions emission could be ascribed due to the resonant energy transfer and cross-relaxation processes. The non-exponential behavior of the decay curves has been analyzed with Inokuti-Hirayama model and the interaction between the Dy3 + ions is of electric dipole-dipole in nature.

  1. TiO2 induced structural modifications in Cs containing borosilicate glasses: Raman and infrared studies

    NASA Astrophysics Data System (ADS)

    Pandey, M.; Banerjee, D.; Sudarsan, V.; Kshirsagar, R. J.

    2018-04-01

    Effect of TiO2 addition in Cs containing Sodium-borosilicate glasses is studied using Raman and infrared spectroscopic techniques. As revealed from infrared and Raman studies, TiO2 does not form segregated phase, but instead enters into the borosilicate network. It is further observed that TiO2 addition results in modifications of the borate and silicate structural units by transforming into tetraborates and metasilicate structural units. These structural modifications are responsible for Cs immobilization, leach rate and chemical durability of these glasses.

  2. Extended electron energy loss fine structure simulation of the local boron environment in sodium aluminoborosilicate glasses containing gadolinium

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Qian, Morris; Li, Hong; Li, Liyu

    Gadolinium can be dissolved in sodium-alumino-borosilicate glasses up to 47 wt% in a baseline borosilicate glass (mol%) 20 B2O3, 5 Al2O3, 60 SiO2,and 20 Na2O. Understanding of Gd dissolution in borosilicate melts is important in glass formulation optimization. Electron energy loss fine structure (ELFS) spectroscopy is chosen, which provides well resolved local atomic structure information for both amorphous and crystalline materials with high sensitivity to low Z elements such as Al, B, Na, O, and Si where the x-ray absorption fine structure (XAFS) technique faces experimental difficulty. In this study, we report our results of boron K-edge ELFS study. Twomore » borosilicate glass samples with 30 and 47 mass% Gd2O3, B20Gd30 and B20Gd47were chosen for B K-edge ELFS study. EEL spectra were acquired on a Philips 430 TEM equipped with Gatan PEELS system 666 and EL/P 2.1 software with Custom function AcqLong. The ELFS data analysis was performed using UWELFS, UWXAFS and FEFF software. From our Gd solubility study, the local structure of Gd in the borate environment possibly resembles double chain structure found in crystalline Gd(BO2)3 as proposed by Chakraborty et al. The B/Gd ratio's in both glasses are smaller then 3, which means the excess Gd atoms in the Si-sites would be 17 and 60 mol% of the total Gd atoms, respectively according to the model, yet the local environment of borate sites saturated with Gd should be remained. To verity above hypothesis, the double chain structure model was applied to fit boron K-edge. The model was shown to well fit experimental boron K-edge EELS spectra for both glasses with some degree of distance distortion which is understandable in amorphous structure. Therefore, it is very likely that Gd stabilized in borate sites has a local structure resembling the double chain Gd(BO2)3 structure as proposed by our solubility study and literature.« less

  3. 21 CFR 872.3400 - Karaya and sodium borate with or without acacia denture adhesive.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... denture adhesive. 872.3400 Section 872.3400 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... and sodium borate with or without acacia denture adhesive. (a) Identification. A karaya and sodium borate with or without acacia denture adhesive is a device composed of karaya and sodium borate with or...

  4. Conversion of Nuclear Waste to Molten Glass: Cold-Cap Reactions in Crucible Tests

    DOE PAGES

    Xu, Kai; Hrma, Pavel; Rice, Jarrett A.; ...

    2016-05-23

    The feed-to-glass conversion, which comprises complex chemical reactions and phase transitions, occurs in the cold cap during nuclear waste vitrification. Here, to investigate the conversion process, we analyzed heat-treated samples of a simulated high-level waste feed using X-ray diffraction, electron probe microanalysis, leaching tests, and residual anion analysis. Feed dehydration, gas evolution, and borate phase formation occurred at temperatures below 700°C before the emerging glass-forming melt was completely connected. Above 700°C, intermediate aluminosilicate phases and quartz particles gradually dissolved in the continuous borosilicate melt, which expanded with transient foam. Finally, knowledge of the chemistry and physics of feed-to-glass conversion willmore » help us control the conversion path by changing the melter feed makeup to maximize the glass production rate.« less

  5. Mg- and K-bearing borates and associated evaporites at Eagle Borax spring, Death Valley, California: A spectroscopic exploration

    USGS Publications Warehouse

    Crowley, J.K.

    1996-01-01

    Efflorescent crusts at the Eagle Borax spring in Death Valley, California, contain an array of rare Mg and K borate minerals, several of which are only known from one or two other localities. The Mg- and/or K-bearing borates include aristarainite, hydroboracite, kaliborite, mcallisterite, pinnoite, rivadavite, and santite. Ulexite and probertite also occur in the area, although their distribution is different from that of the Mg and K borates. Other evaporite minerals in the spring vicinity include halite, thenardite, eugsterite, gypsum-anhydrite, hexahydrite, and bloedite. Whereas the first five of these minerals are found throughout Death Valley, the last two Mg sulfates are more restricted in occurrence and are indicative of Mg-enriched ground water. Mineral associations observed at the Eagle Borax spring, and at many other borate deposits worldwide, can be explained by the chemical fractionation of borate-precipitating waters during the course of evaporative concentration. The Mg sulfate and Mg borate minerals in the Eagle Borax efflorescent crusts point to the fractionation of Ca by the operation of a chemical divide involving Ca carbonate and Na-Ca borate precipitation in the subsurface sediments. At many other borate mining localities, the occurrence of ulexite in both Na borate (borax-kernite) and Ca borate (ulexite-colemanite) deposits similarly reflects ulexite's coprecipitation with Ca carbonate at an early concentration stage. Such ulexite may perhaps be converted to colemanite by later reaction with the coexisting Ca carbonate - the latter providing the additional Ca2+ ions needed for the conversion. Mg and Ca-Mg borates are the expected late-stage concentration products of waters forming ulexite-colemanite deposits and are therefore most likely to occur in the marginal zones or nearby mud facies of ulexite-colemanite orebodies. Under some circumstances, Mg and Ca-Mg borates might provide a useful prospecting guide for ulexite-colemanite deposits

  6. Investigations on the local structures of Cu2+ at various BaO concentrations in 59B2O3-10K2O-(30-x)ZnO-xBaO-1CuO glasses

    NASA Astrophysics Data System (ADS)

    Jin, Jia-Rui; Wu, Shao-Yi; Hong, Jian; Liu, Shi-Nan; Song, Min-Xian; Teng, Bao-Hua; Wu, Ming-He

    2017-11-01

    The local structures and electron paramagnetic resonance (EPR) parameters for Cu2+ in 59B2O3-10K2O-(30-x)ZnO-xBaO-1CuO (BKZBC) glasses are theoretically investigated with distinct modifier BaO concentrations x (= 0, 6, 12, 18, 24 and 30 mol %). The ? clusters are found to undergo the relative tetragonal elongations of about 13.5 and 5.0% at zero and higher BaO concentrations. The concentration dependences of the measured d-d transition bands, g factors and A// are suitably reproduced from the Fourier type functions or sign functions of the relevant quantities with x by using only six adjustable parameters. The features of the EPR parameters and the local structures of Cu2+ are analysed in a consistent way by considering the differences in the local ligand field strength and electronic cloud admixtures around Cu2+ under addition of Ba2+ with the highest ionicity and polarisability. The present theoretical studies would be helpful to the researches on the structures, optical and EPR properties for the similar potassium barium zinc borate glasses containing copper with variation concentration of modifier BaO.

  7. An evaluation of the processing conditions, structure, and properties (biaxial flexural strength and antibacterial efficacy) of sintered strontium-zinc-silicate glass ceramics.

    PubMed

    Looney, Mark; Shea, Helen O'; Gunn, Lynda; Crowley, Dolores; Boyd, Daniel

    2013-05-01

    The use of artificial bone grafts has increased in order to satisfy a growing demand for bone replacement materials. Initial mechanical stability of synthetic bone grafts is very advantageous for certain clinical applications. Coupled with the advantage of mechanical strength, a material with inherent antibacterial properties would be very beneficial. A series of strontium-doped zinc silicate (Ca-Sr-Na-Zn-Si) glass ceramics have been characterized in terms of their crystalline structure, biaxial flexural strength and antibacterial efficacy based on the identification of optimum sintering conditions. All three glass ceramics, namely, BT110, BT111, and BT112 were found to be fully crystalline, with BT111 and BT112 comprising of biocompatible crystalline phases. The biaxial flexural strengths of the three glass ceramics ranged from 70 to 149 MPa and were shown to be superior to those of clinically established ceramics in dry conditions and following incubation in simulated physiological conditions. The bacteriostatic effect for each glass ceramic was also established, where BT112 showed an inhibitory effect against three of the most common bacteria found at implantation sites, namely, Enterococcus faecalis, methicillin-resistant Staphylococcus aureus (MRSA), and Pseudomonas aeruginosa. The results of the evaluation suggest that the materials studied offer advantages over current clinical materials and indicate the potential suitability of the glass ceramics as therapeutic bone grafts.

  8. Effective binding of perhalogenated closo-borates to serum albumins revealed by spectroscopic and ITC studies

    NASA Astrophysics Data System (ADS)

    Kuperman, Marina V.; Losytskyy, Mykhaylo Yu.; Bykov, Alexander Yu.; Yarmoluk, Sergiy M.; Zhizhin, Konstantin Yu.; Kuznetsov, Nikolay T.; Varzatskii, Oleg A.; Gumienna-Kontecka, Elzbieta; Kovalska, Vladyslava B.

    2017-08-01

    The interactions of boron cluster compounds closo-borates with biomolecules are widely studied due to their efficiency as agents for boron neutron capture therapy of cancer. In present work the binding abilities of anionic halogen closo-borates [B10Hal10]2- (Hal = Cl, Br, I) and [B12Hal12]2- (Hal = Cl, I) towards bovine and human serum albumins were investigated by spectroscopic and isothermal titration calorimetry (ITC) methods. The protein fluorescence quenching method and ITC studies confirmed the complex formation. The degree of protein fluorescence quenching increased from chlorine to iodine boron derivatives that is attributed to external heavy atom effect. The ITC data point on the existence in the protein structure of two types of binding sites: with higher and lower affinity to closo-borates. Albumin-closo-borate complex binding ratio, n (4-5 anions per protein molecule) is higher than for the parent hydrogen closo-borates (2 anions per protein molecule). Binding constants estimated by fluorescent and ITC methods indicate higher affinity of halogen closo-borates to albumins (K in the range of 104-106 M-1) comparing to that of the hydrogen closo-borate (K about 103 M-1). Due to their high affinity and high binding ratio to albumins halogen closo-borates are proposed for further studies as agents for boron neutron capture therapy.

  9. Spectroscopic attributes of Sm3+ doped magnesium zinc sulfophosphate glass: Effects of silver nanoparticles inclusion

    NASA Astrophysics Data System (ADS)

    Ahmadi, F.; Hussin, R.; Ghoshal, S. K.

    2017-11-01

    We report the modified optical properties of Sm3+ doped magnesium zinc sulfophosphate glass system with silver nanoparticles (Ag NPs) inclusion. Three glass samples were prepared using melt quenching method and characterized. TEM images revealed the nucleation of Ag NPs with average diameter ≈12.50 nm. The UV-Vis-NIR spectra showed thirteen absorption bands. The surface plasmon resonance (SPR) band of Ag NPs was manifested at 446 nm. FTIR spectra disclosed the bonding vibrations for P-O bonds, P-O-P linkages, and PO2 units. Ag NPs concentration dependent bonding parameters and Judd-Ofelt (JO) intensity parameters were calculated. The JO parameter Ω2 was reduced with the increase of Ag NPs contents, indicating the ionicity and symmetry enhancement between Sm3+ ions with their surrounding ligands. The emission spectra of all samples under the excitation wavelength of 402 nm exhibited four significant peaks centered at 562, 599, 644 and 702 nm which are allocated to 4G5/2 →6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions, respectively. Inclusion of Ag NPs was discerned to augment the luminescence intensity by a factor of two, which was majorly ascribed to the local field effect of Ag NPs and subsequent energy transfer from the NPs to Sm3+ ions.

  10. Structure-composition trends in multicomponent borosilicate-based glasses deduced from molecular dynamics simulations with improved B-O and P-O force fields.

    PubMed

    Stevensson, Baltzar; Yu, Yang; Edén, Mattias

    2018-03-28

    We present a comprehensive molecular dynamics (MD) simulation study of composition-structure trends in a set of 25 glasses of widely spanning compositions from the following four systems of increasing complexity: Na 2 O-B 2 O 3 , Na 2 O-B 2 O 3 -SiO 2 , Na 2 O-CaO-SiO 2 -P 2 O 5 , and Na 2 O-CaO-B 2 O 3 -SiO 2 -P 2 O 5 . The simulations involved new B-O and P-O potential parameters developed within the polarizable shell-model framework, thereby combining the beneficial features of an overall high accuracy and excellent transferability among different glass systems and compositions: this was confirmed by the good accordance with experimental data on the relative BO 3 /BO 4 populations in borate and boro(phospho)silicate networks, as well as with the orthophosphate fractions in bioactive (boro)phosphosilicate glasses, which is believed to strongly influence their bone-bonding properties. The bearing of the simulated melt-cooling rate on the borate/phosphate speciations is discussed. Each local {BO 3 , BO 4 , SiO 4 , PO 4 } coordination environment remained independent of the precise set of co-existing network formers, while all trends observed in bond-lengths/angles mainly reflected the glass-network polymerization, i.e., the relative amounts of bridging oxygen (BO) and non-bridging oxygen (NBO) species. The structural roles of the Na + /Ca 2+ cations were also probed, targeting their local coordination environments and their relative preferences to associate with the various borate, silicate, and phosphate moieties. We evaluate and discuss the common classification of alkali/alkaline-earth metal ions as charge-compensators of either BO 4 tetrahedra or NBO anions in borosilicate glasses, also encompassing the less explored NBO-rich regime: the Na + /Ca 2+ cations mainly associate with BO/NBO species of SiO 4 /BO 3 groups, with significant relative Na-BO 4 contacts only observed in B-rich glass networks devoid of NBO species, whereas NBO-rich glass networks also

  11. Optical and EPR studies of barium alumino borate glasses containing Cu2+ ions

    NASA Astrophysics Data System (ADS)

    Ahmed, Mohamad Raheem; Phani, A. V. Lalitha; Narsimha Chary, M.; Shareefuddin, Md.

    2018-05-01

    Glass containing Cu2+ ions in (30-x) BaO-xAl2O3-69.5B2O3-0.5CuO (0 ≤ x ≤ 15 mol %) were prepared by the conventional melt quenching technique. Peak free X-ray diffractograms confirmed the amorphous nature of the glass samples. Spectroscopic studies such as optical absorption, EPR were studied to understand the effect of modifier oxide and CuO dopant. From EPR spectra the spin-Hamiltonian parameter were evaluated. The ground state of Cu2+ is dx2-y2 (2B1g state) and the site symmetry around Cu2+ is tetragonally distorted octahedral. A broad optical absorption band was observed for all the glasses containing Cu2+ ions corresponding to the 2B1g → 2B2g transition. The optical band gap and Urbach energy values are calculated.

  12. The role of halides on a chromium ligand field in lead borate glasses

    NASA Astrophysics Data System (ADS)

    Sekhar, K. Chandra; Srinivas, B.; Narsimlu, N.; Narasimha Chary, M.; Shareefuddin, Md

    2017-10-01

    Glasses with a composition of PbX-PbO-B2O3 (X  =  F2, Cl2 and Br2) containing Cr3+ ions were prepared by a melt quenching technique and investigated by using x-ray diffraction (XRD), optical absorption and electron paramagnetic resonance (EPR) studies. X-ray diffractograms revealed the amorphous nature of the glasses. The density and molar volume were determined. Density values increased for the PFPBCR glass system and decreased for the PCPBCR and PBPBCR glass systems with the composition. Optical absorption spectra were recorded at room temperature (RT) to evaluate the optical band gap E opt and Urbach energies. All the spectra showed characteristic peaks at around 450 nm, 600 nm and 690 nm, and they are assigned to 4 A 2g  →  4 T 1g, 4 A 2g  →  4 T 2g, 4 A 2g  →  2 E transitions respectively. From the optical absorption spectral data, the crystal field (D q ) and Racah parameters (B and C) have been evaluated. Variations in optical band gaps were explained using the electro negativity of halide ions. Electron paramagnetic resonance (EPR) studies were carried out by introducing Cr3+ as the spin probe. The EPR spectra of all the glass samples were recorded at X-band frequencies. The EPR spectra exhibit two resonance signals with effective g values at g  ≈  4.82 and g  ≈  1.99 and are attributed to isolated Cr3+ ions and exchange coupled Cr3+ pairs respectively. The number of spins along with susceptibility are also calculated from the EPR spectra.

  13. Optical and Physical Investigations of Lanthanum Bismuth Borate glasses doped with Ho2O3

    NASA Astrophysics Data System (ADS)

    Ramesh, P.; Jagannath, G.; Eraiah, B.; Kokila, M. K.

    2018-02-01

    Holmium doped 10La2O3-15Bi2O3-(75-x) B2O3 (Ho3+: LBB) glasses have been prepared by melt quench technique and the impact of holmium ions concentration on optical and physical properties of present glasses have been examined. Ho3+ dependent density, molar volume, refractive index, rare earth ion concentration, polaron radius, inter ionic distance, field strength and energy band gap are calculated and tabulated. Amorphous nature of the all glasses has been confirmed by XRD patterns. The room temperature (RT) Uv-Vis absorption spectrum doped with 1 mol% of Ho2O3 exhibit eight prominent bands centred at 895, 641, 537, 486, 472, 467, 451 and 416 due to transition between ground state to various excited states. The results show that, the density is increases and molar volume of the glasses is decreases with an increase in Ho2O3 concentration and consequently generate more non-bridging oxygen (NBOs) in the glass matrix. The Urbach energy is increases with holmium concentration which exemplifies the degree of disorder present in the LBB glasses. The considerable increase in field strength observed in present glasses is attributed to occurrence of strong bridge between Ho3+ and B- ions and this strong bridge is possibly due to the displacement between Ho3+ and oxygen atoms which are generated from the conversion BO3-BO4 units.

  14. Low-temperature heat capacities of 1-alkyl-3-methylimidazolium bis(oxalato)borate ionic liquids and the influence of anion structural characteristics on thermodynamic properties.

    PubMed

    Yang, Miao; Zhao, Jun-Ning; Liu, Qing-Shan; Sun, Li-Xian; Yan, Pei-Fang; Tan, Zhi-Cheng; Welz-Biermann, Urs

    2011-01-07

    Two chelated orthoborate ionic liquids (ILs), 1-butyl-3-methylimidazolium bis(oxalato)borate ([Bmim][BOB]) and 1-hexyl-3-methylimidazolium bis(oxalato)borate ([Hmim][BOB]), were prepared and characterized. Their thermodynamic properties were studied using adiabatic calorimetry and differential scanning calorimetry (DSC). The thermodynamic properties of the two ILs were evaluated and compared with each other, and then with those of other [Bmim] type ILs. The results clearly indicate that for a given cation (or anion) and at a certain temperature, the more atoms in the anion (or cation), the higher the heat capacity; the higher glass-transition temperatures of [BOB] type ILs than others are mainly caused by the higher symmetry of the orthoborate anion structure. It is suggested that a high content of strong electronegative atoms and C(n) or C(nv) (n = 1,2,3,…,∞) point group symmetry in the anion are favorable for the design and synthesis of room temperature ILs with a wide liquid range.

  15. Glass transition and crystallization kinetics of a barium borosilicate glass by a non-isothermal method

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lopes, Andreia A. S.; Soares, Roque S.; Lima, Maria M. A.

    2014-01-28

    The glass transition and crystallization kinetics of a glass with a molar composition 60BaO-30B{sub 2}O{sub 3}-10SiO{sub 2} were investigated by differential scanning calorimetry (DSC) under non-isothermal conditions. DSC curves exhibited an endothermic peak associated with the glass transition and two partially overlapped exothermic peaks associated with the crystallization of the glass. The dependence of the glass transition temperature (T{sub g}) and of the maximum crystallization temperature (T{sub p}) on the heating rate was used to determine the activation energy associated with the glass transition (E{sub g}), the activation energy for crystallization (E{sub c}), and the Avrami exponent (n). X-ray diffractionmore » (XRD) revealed that barium borate (β-BaB{sub 2}O{sub 4}) was the first crystalline phase to be formed followed by the formation of barium silicate (Ba{sub 5}Si{sub 8}O{sub 21}). The variations of activation energy for crystallization and of Avrami exponent with the fraction of crystallization (χ) were also examined. When the crystallization fraction (χ) increased from 0.1 to 0.9, the value of local activation energy (E{sub c}(χ)) decreased from 554 to 458 kJ/mol for the first exothermic peak and from 1104 to 831 kJ/mol for the second exothermic peak. The value determined for the Avrami exponent was near 2 indicating a similar one-dimensional crystallization mechanism for both crystalline phases. This was confirmed by the morphological studies performed by scanning electron microscopy (SEM) on glass samples heat-treated at the first and at the second crystallization temperatures.« less

  16. Could borate have played a role in the RNA World?

    NASA Astrophysics Data System (ADS)

    Grew, E. S.; Bada, J. L.; Hazen, R. M.

    2012-12-01

    Two scenarios have been proposed for boron to play a critical role in the stabilization of ribose and other sugars in the ribonucleic acid (RNA) World, >3.8 Ga ago. One scenario envisages oligomeric RNA being synthesized in subaerial intermountane desert valleys in which groundwater was enriched in borate from breakdown of tourmaline (Benner et al. 2012 doi: 10.1021/ar200332w). In the alternative scenario, borates are enriched in hydrothermal environments (<150°C) in oceanic crust where ferromagnesian minerals are altered to brucite, serpentine and other minerals that can extract borate from the circulating seawater (Holm et al. 2006 doi:10.1186/1467-4866-7-7). Both scenarios presume that (1) B concentrations in non-marine water or sea water were about the same at >3.8 Ma as they are today and (2) plate tectonics was the prevailing regime. The postulated non-marine borate deposits would have been associated with continental collision and subduction with volcanism releasing B, whereas in the second scenario, ocean floor caught up in an early phase of subduction is considered a favorable site for borate formation. Because borate deposits are typically ephemeral and poorly preserved, the lack of evidence in the geologic record for these scenarios does not invalidate them. For example, the oldest reported non-marine borate deposits analogous to the type postulated in first scenario are only 20 Ma, but metamorphosed borates of Precambrian age have been interpreted to have non-marine evaporite precursors, the oldest being 2.4-2.1 Ga in the Liaoning-Jilin area, China. The first B minerals so far reported in the geologic record are metamorphic dravite-schorl tourmalines in the 3.7-3.8 Ga Isua supracrustal belt (southern West Greenland), where there is good evidence for seafloor spreading and subduction. The precursors to the Isua tourmalines are reported to include B-bearing marine clay minerals and detrital tourmaline. The relatively high Li contents in zircon from Jack

  17. [Influence of adhesion on the color of glass infiltrated alumina ceramic restorations].

    PubMed

    Jiang, Li; Yang, Liu; Xu, Qiang; Guan, Hong-Yu; Wan, Qian-Bing

    2006-10-01

    To investigate the effects of luting agent on the final color of glass infiltrated alumina ceramic restorations. 12 plate-shaped specimens with 12.5 mm in diameter and 0.5 mm thickness were fabricated from GI-II (color IG2). Vitadur alpha veneering porcelain (color A2) with 1.0 mm thickness was fired to GI- II glass/alumina composite. 12 plate-shaped background specimens simulating the metal alloy post-and-core 12.5 mm in diameter and 2 mm thickness were also made from Ni-Cr alloy. All-ceramic specimens were luted to the metal alloy by Zinc Phosphate cement, glass ionomer cement and composite resin. The color shifts of the specimens were measured by colorimeter. Luting agents had effect on the final color of restorations. The influence of composite resin was least, followed by glass ionomer cement and Zinc Phosphate cement. The color difference between with and without Zinc Phosphate cement could be identified by the eye. To reduce the effect of luting agents, composite resin is recommended to all-ceramic restorations' adhesion.

  18. A review of bioactive glasses: Their structure, properties, fabrication and apatite formation.

    PubMed

    Kaur, Gurbinder; Pandey, Om P; Singh, Kulvir; Homa, Dan; Scott, Brian; Pickrell, Gary

    2014-01-01

    Bioactive glass and glass-ceramics are used in bone repair applications and are being developed for tissue engineering applications. Bioactive glasses/Bioglass are very attractive materials for producing scaffolds devoted to bone regeneration due to their versatile properties, which can be properly designed depending on their composition. An important feature of bioactive glasses, which enables them to work for applications in bone tissue engineering, is their ability to enhance revascularization, osteoblast adhesion, enzyme activity and differentiation of mesenchymal stem cells as well as osteoprogenitor cells. An extensive amount of research work has been carried out to develop silicate, borate/borosilicate bioactive glasses and phosphate glasses. Along with this, some metallic glasses have also been investigated for biomedical and technological applications in tissue engineering. Many trace elements have also been incorporated in the glass network to obtain the desired properties, which have beneficial effects on bone remodeling and/or associated angiogenesis. The motivation of this review is to provide an overview of the general requirements, composition, structure-property relationship with hydroxyapatite formation and future perspectives of bioglasses.Attention has also been given to developments of metallic glasses and doped bioglasses along with the techniques used for their fabrication. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

  19. Tris-borate is a poor counterion for RNA: a cautionary tale for RNA folding studies

    PubMed Central

    Buchmueller, Karen L.; Weeks, Kevin M.

    2004-01-01

    Native polyacrylamide gel electrophoresis is a powerful approach for visualizing RNA folding states and folding intermediates. Tris-borate has a high-buffering capacity and is therefore widely used in electrophoresis-based investigations of RNA structure and folding. However, the effectiveness of Tris-borate as a counterion for RNA has not been systematically investigated. In a recirculated Hepes/KCl buffer, the catalytic core of the bI5 group I intron RNA undergoes a conformational collapse characterized by a bulk transition midpoint, or Mg1/2, of ∼3 mM, consistent with extensive independent biochemical experiments. In contrast, in Tris-borate, RNA collapse has a much smaller apparent Mg1/2, equal to 0.1 mM, because in this buffer the RNA undergoes a different, large amplitude, folding transition at low Mg2+ concentrations. Analysis of structural neighbors using a short-lived, RNA-tethered, photocrosslinker indicates that the global RNA structure eventually converges in the two buffer systems, as the divalent ion concentration approaches ∼1 mM Mg2+. The weak capacity of Tris-borate to stabilize RNA folding may reflect relatively unfavorable interactions between the bulky Tris-borate ion and RNA or partial coordination of RNA functional groups by borate. Under some conditions, Tris-borate is a poor counterion for RNA and its use merits careful evaluation in RNA folding studies. PMID:15601995

  20. Method of recycling lithium borate to lithium borohydride through diborane

    DOEpatents

    Filby, Evan E.

    1976-01-01

    This invention provides a method for the recycling of lithium borate to lithium borohydride which can be reacted with water to generate hydrogen for utilization as a fuel. The lithium borate by-product of the hydrogen generation reaction is reacted with hydrogen chloride and water to produce boric acid and lithium chloride. The boric acid and lithium chloride are converted to lithium borohydride through a diborane intermediate to complete the recycle scheme.

  1. Relaxation dynamics in AgI-doped silver vanadate superionic glasses.

    PubMed

    Bhattacharya, S; Ghosh, A

    2005-09-22

    Relaxation dynamics of Ag+ ions in several series of AgI-Ag2O-V2O5 superionic glasses has been studied in the frequency range from 10 Hz to 2 MHz and in the temperature range from 93 to 323 K. The composition dependence of the dc conductivity and the activation energy of these glasses has been compared with those of AgI-doped silver phosphate and borate glasses. The frequency-dependent electrical data have been analyzed in the framework of conductivity formalism. We have obtained the mobile ion concentration and the power-law exponent from the analysis of the conductivity spectra. We have observed that the concentration of Ag+ ions is independent of temperature and the conductivity is primarily determined by the mobility. A fraction of the Ag+ ions in the glass compositions are involved in the dynamic process. We have also shown that the power-law exponent is independent of temperature. The results are also supported by the temperature and composition independence of the scaling of the conductivity spectra.

  2. A method for predicting service life of zinc rich primers on carbon steel

    NASA Technical Reports Server (NTRS)

    Hoppesch, C. W.

    1986-01-01

    The service life of zinc rich primers on carbon steel can be estimated by immersing a primer coated glass slide into an aqueous copper sulfate solution and measuring the amount of zinc that reacts with the copper in 15 minutes. This zinc availability test was used to evaluate eleven primers currently available for which marine beach exposure data was available from previous programs. Results were evaluated and a correlation between zinc availability and ASTM rust grade was shown.

  3. Unusual stoichiometry control in the atomic layer deposition of manganese borate films from manganese bis(tris(pyrazolyl)borate) and ozone

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Klesko, Joseph P.; Bellow, James A.; Saly, Mark J.

    The atomic layer deposition (ALD) of films with the approximate compositions Mn{sub 3}(BO{sub 3}){sub 2} and CoB{sub 2}O{sub 4} is described using MnTp{sub 2} or CoTp{sub 2} [Tp = tris(pyrazolyl)borate] with ozone. The solid state decomposition temperatures of MnTp{sub 2} and CoTp{sub 2} are ∼370 and ∼340 °C, respectively. Preparative-scale sublimations of MnTp{sub 2} and CoTp{sub 2} at 210 °C/0.05 Torr afforded >99% recoveries with <0.1% nonvolatile residues. Self-limited ALD growth was demonstrated at 325 °C for MnTp{sub 2} or CoTp{sub 2} with ozone as the coreactant. The growth rate for the manganese borate process was 0.19 Å/cycle within the ALD window of 300–350 °C. The growth ratemore » for the cobalt borate process was 0.39–0.42 Å/cycle at 325 °C. X-ray diffraction of the as-deposited films indicated that they were amorphous. Atomic force microscopy of 35–36 nm thick manganese borate films grown within the 300–350 °C ALD window showed root mean square surface roughnesses of 0.4–0.6 nm. Film stoichiometries were assessed by x-ray photoelectron spectroscopy and time of flight-elastic recoil detection analysis. The differing film stoichiometries obtained from the very similar precursors MnTp{sub 2} and CoTp{sub 2} are proposed to arise from the oxidizing ability of the intermediate high valent manganese oxide layers and lack thereof for cobalt.« less

  4. Synthesis and optical properties of antimony oxide glasses doped with holmium trioxide

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Raghunatha, S.; Eraiah, B., E-mail: eraiah@rediffmail.com

    2016-05-06

    Holmium doped lithium-antimony-lead borate glasses having 1 mol% AgNO{sub 3} with composition 50B{sub 2}O{sub 3}-20PbO-25Sb{sub 2}O{sub 3}-5Li{sub 2}O have been prepared using single step melt quenching technique. The XRD spectrum confirms amorphous nature of glasses. The optical absorbance studies were carried out on these glasses. The optical direct band gap energies were found to be in the range of 3.10 eV to 3.31 eV and indirect band gap energies were found to be in the range of 2.28 eV to 3.00 eV. The refractive indexes have been calculated by using Lorentz-Lorenz formula and the calculated values in the range ofmore » 2.31 to 2.37.« less

  5. Ac-conductivity and dielectric response of new zinc-phosphate glass/metal composites

    NASA Astrophysics Data System (ADS)

    Maaroufi, A.; Oabi, O.; Lucas, B.

    2016-07-01

    The ac-conductivity and dielectric response of new composites based on zinc-phosphate glass with composition 45 mol%ZnO-55 mol%P2O5, filled with metallic powder of nickel (ZP/Ni) were investigated by impedance spectroscopy in the frequency range from 100 Hz to 1 MHz at room temperature. A high percolating jump of seven times has been observed in the conductivity behavior from low volume fraction of filler to the higher fractions, indicating an insulator - semiconductor phase transition. The measured conductivity at higher filler volume fraction is about 10-1 S/cm and is frequency independent, while, the obtained conductivity for low filler volume fraction is around 10-8 S/cm and is frequency dependent. Moreover, the elaborated composites are characterized by high dielectric constants in the range of 105 for conductive composites at low frequencies (100 Hz). In addition, the distribution of the relaxation processes was also evaluated. The Debye, Cole-Cole, Davidson-Cole and Havriliak-Negami models in electric modulus formalism were used to model the observed relaxation phenomena in ZP/Ni composites. The observed relaxation phenomena are fairly simulated by Davidson-Cole model, and an account of the interpretation of results is given.

  6. Structure and luminescence spectra of lutetium and yttrium borates synthesized from ammonium nitrate melt

    NASA Astrophysics Data System (ADS)

    Klassen, Nikolay V.; Shmurak, Semion Z.; Shmyt'ko, Ivan M.; Strukova, Galina K.; Derenzo, Stephen E.; Weber, Marvin J.

    2005-01-01

    Lutetium and yttrium borates doped with europium, terbium, gadolinium, etc. have been synthesized by dissolving initial oxides and nitrates in ammonium nitrate melt and thermal decomposition of the solvent. Annealings in the range of 500-1100°C modified the dimensions of the grains from 2 to 3 nm to more than 100 nm. Significant dependence of the structure of lutetium borate on slight doping with rare earth ions has been found: terbium makes high-temperature vaterite phase preferential at room temperature, whereas europium stabilizes low-temperature calcite phase. Influence of the structure of the borates on the pattern of the luminescence spectra of europium dopant was observed. Possibilities for manufacturing of scintillating lutetium borate ceramics by means of this method of synthesis are discussed.

  7. Recent advances in rare earth doped alkali-alkaline earth borates for solid state lighting applications

    NASA Astrophysics Data System (ADS)

    Verma, Shefali; Verma, Kartikey; Kumar, Deepak; Chaudhary, Babulal; Som, Sudipta; Sharma, Vishal; Kumar, Vijay; Swart, Hendrik C.

    2018-04-01

    As a novel class of inorganic phosphor, the alkali-alkaline earth borate phosphors have gained huge attention due to their charming applications in solid-state lighting (SSL) and display devices. The current research drive shows that phosphors based on the alkali-alkaline earth borates have transformed the science and technology due to their high transparency over a broad spectral range, their flexibility in structure and durability for mechanical and high-laser applications. Recent advances in various aspects of rare-earth (RE) doped borate based phosphors and their utilizations in SSL and light emitting diodes are summarized in this review article. Moreover, the present status and upcoming scenario of RE-doped borate phosphors were reviewed in general along with the proper credential from the existing literature. It is believed that this review is a sole compilation of crucial information about the RE-doped borate phosphors in a single platform.

  8. Geochemical characteristics of The Emet (Espey-Hisarcik) borate deposits, Kütahya, Turkey

    NASA Astrophysics Data System (ADS)

    Koçak, İ.; Koç, Ş.

    2018-06-01

    Nearly 72% world's borate reserves are in western part of Turkey. The Emet (Kütahya) deposit is one of these deposits. The Emet borate deposit, like other deposits in western Anatolia, was deposited in Miocene lacustrine environment whose formation coincides with volcanic activity started in Paleogene and lasted to the beginning of Quaternary. The borate ore displaying lenticular structure is alternated with claystone, marl, tuff and thin bedded limestone. The mineral paragenesis is composed of colemanite, hydroboracite, Veatchite, dolomite, calcite, montmorillonite and illite. The Emet borate deposit has been the subject of various geologic and mineralogical studies. In the present study major and trace element contents of 60 borate samples from this deposit are discussed. Among the trace elements, significant enrichment was found in As, Se, Sr, Cs, Sb and Li. Element correlations indicate volcanic source for boron (exhalations and hydrothermal solutions) whilst other elements are found to be derived from a terrestrial source. According to REE data, high Ce concentrations and anomalies are generally indicative of oxygenated depositional environment whilst low Ce contents facilitated the lake waters to be low oxygenated as a result of H2S-rich hydrothermal solutions. The weak negative anomaly detected only in the Hisarcık region is attributed to lacking of Eu contribution to the lake due to insufficient alteration on the continent.

  9. Physical and optical property studies on Bi3+ ion containing vanadium sodium borate glasses

    NASA Astrophysics Data System (ADS)

    Venkatesh, G.; Meera, B. N.; Eraiah, B.

    2018-04-01

    xBi2O3-(15-x)V2O5-45B2O3-40Na2O glasses have been prepared using melt quenching technique. Amorphous nature of the glasses is verified using powder XRD. Densities and molar volume have been determined as a function of bismuth content and interestingly both increases as a function of bismuth content. Further oxygen packing density (OPD) is found to decrease with bismuth content. The increase in the molar volume as a function of bismuth content may be due to structural changes in the glass network. The optical properties performed from the optical absorption spectra were recorded in the wavelength range 200-1100 nm using UV-Visible spectrophotometer. The theoretical optical basicity of the oxides have also been estimated. The calculated energy band gap values increases with increase in Bi2O3 content.

  10. Conversion of Nuclear Waste to Molten Glass: Cold-Cap Reactions in Crucible Tests

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xu, Kai; Hrma, Pavel; Rice, Jarrett A.

    2016-05-23

    The feed-to-glass conversion, which comprises complex chemical reactions and phase transitions, occurs in the cold-cap zone during nuclear waste vitrification. Knowledge of the chemistry and physics of feed-to-glass conversion will help us control the conversion path by changing the melter feed makeup to maximize the glass production rate. To investigate the conversion process, we analyzed heat-treated samples of a simulated high-level waste feed using X-ray diffraction, electron probe microanalysis – wavelength dispersive X-ray spectroscopy, leaching tests, and residual anion analysis. Feed dehydration, gas evolution, and borate phase formation occurred at temperatures below 700 °C before the emerging glass-forming melt wasmore » completely connected. Above 800 °C, intermediate aluminosilicate phases and quartz particles were gradually dissolving in the continuous borosilicate melt, which expanded into transient foam. Knowledge of the chemistry and physics of feed-to-glass conversion will help us control the conversion path by changing the melter feed makeup to maximize the glass production rate.« less

  11. Evaluating the critical strain energy release rate of bioactive glass coatings on Ti6Al4V substrates after degradation.

    PubMed

    Matinmanesh, A; Li, Y; Nouhi, A; Zalzal, P; Schemitsch, E H; Towler, M R; Papini, M

    2018-02-01

    It has been reported that the adhesion of bioactive glass coatings to Ti6Al4V reduces after degradation, however, this effect has not been quantified. This paper uses bilayer double cantilever (DCB) specimens to determine G IC and G IIC , the critical mode I and mode II strain energy release rates, respectively, of bioactive coating/Ti6Al4V substrate systems degraded to different extents. Three borate-based bioactive glass coatings with increasing amounts of incorporated SrO (0, 15 and 25mol%) were enamelled onto Ti6Al4V substrates and then immersed in de-ionized water for 2, 6 and 24h. The weight loss of each glass composition was measured and it was found that the dissolution rate significantly decreased with increasing SrO content. The extent of dissolution was consistent with the hypothesis that the compressive residual stress tends to reduce the dissolution rate of bioactive glasses. After drying, the bilayer DCB specimens were created and subjected to nearly mode I and mode II fracture tests. The toughest coating/substrate system (one composed of the glass containing 25mol% SrO) lost 80% and 85% of its G IC and G IIC , respectively, in less than 24h of degradation. The drop in G IC and G IIC occurred even more rapidly for other coating/substrate systems. Therefore, degradation of borate bioactive glass coatings is inversely related to their fracture toughness when coated onto Ti6A4V substrates. Finally, roughening the substrate was found to be inconsequential in increasing the toughness of the system as the fracture toughness was limited by the cohesive toughness of the glass itself. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Synthesis and evaluation of borates derived from boric acid and diols for the protection of wood against fungal decay and thermal degradation

    Treesearch

    George C. Chen

    2004-01-01

    N,N-dimethyl amino carbinol catechol borate(1). N,N-dimethyl amino carbinol-4-methyl catechol borate(2), N,N-dimethyl amino carbinol-4-t- butyl catechol borate(3). N,N-dimethyl amino carbinol-2,3-naphthyl borate 4) were synthesized by refluxing boric acid and diol in DMF(N,N-dimethyl formamide). The borates were characterized by NMR. Wood impregnated with borate 1,2 or...

  13. Preparation and characterization of Tb3+ ions doped zincborophosphate glasses for green emission

    NASA Astrophysics Data System (ADS)

    Bindu, S. Hima; Raju, D. Siva; Krishna, V. Vinay; Raju, Ch. Linga

    2017-06-01

    The present study reports the preparation of various concentrations of Tb3+ ions doped zincborophosphate glasses and analysis by XRD, FTIR, optical, emission and decay curve spectras. The effect of borate groups on the phosphate was evidenced by FTIR spectroscopy. The JO intensity parameters was calculated using Judd-Offlet theory. The fluroscence spectra of Tb3+ doped zincborophosphate glasses revealed the efficient blue and green emissions due to 5D3 and 5D4 excited levels to 7Fj ground state respectively. The decay curves exhibits single exponential curves for all the Tb3+ ion concentrations. Various radiative and fluorescence parameters are calculated using JO intensity parameters. Based on the results obtained in the present study, the Tb3+ ions doped zincborophosphate glasses behaves as a efficient laser active materials for highintensity emissions in the green region.

  14. Vibrational spectroscopy of the borate mineral kotoite Mg₃(BO₃)₂.

    PubMed

    Frost, Ray L; Xi, Yunfei

    2013-02-15

    Vibrational spectroscopy has been used to assess the structure of kotoite a borate mineral of magnesium which is isostructural with jimboite. The mineral is orthorhombic with point group: 2/m 2/m 2/m. The mineral has the potential as a new memory insulator material. The mineral has been characterised by a combination of Raman and infrared spectroscopy. The Raman spectrum is dominated by a very intense band at 835 cm(-1), assigned to the symmetric stretching mode of tetrahedral boron. Raman bands at 919, 985 and 1015 cm(-1) are attributed to the antisymmetric stretching modes of tetrahedral boron. Kotoite is strictly an hydrous borate mineral. An intense Raman band observed at 3559 cm(-1) is attributed to the stretching vibration of hydroxyl units, more likely to be associated with the borate mineral hydroxyborate. The lack of observation of water bending modes proves the absence of water in the kotoite structure. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Influence of sodium borate on the early age hydration of calcium sulfoaluminate cement

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Champenois, Jean-Baptiste; Dhoury, Mélanie; Cau Dit Coumes, Céline, E-mail: celine.cau-dit-coumes@cea.fr

    Calcium sulfoaluminate (CSA) cements are potential candidates for the conditioning of radioactive wastes with high sodium borate concentrations. This work thus investigates early age hydration of two CSA cements with different gypsum contents (0 to 20%) as a function of the mixing solution composition (borate and NaOH concentrations). Gypsum plays a key role in controlling the reactivity of cement. When the mixing solution is pure water, increasing the gypsum concentration accelerates cement hydration. However, the reverse is observed when the mixing solution contains sodium borate. Until gypsum exhaustion, the pore solution pH remains constant at ~ 10.8, and a poorlymore » crystallized borate compound (ulexite) precipitates. A correlation is established between this transient precipitation and the hydration delay. Decreasing the gypsum content in the binder, or increasing the sodium content in the mixing solution, are two ways of reducing the stability of ulexite, thus decreasing the hydration delay.« less

  16. Synthesis of zinc oxide nanostructures on graphene/glass substrate by electrochemical deposition: effects of current density and temperature.

    PubMed

    Hambali, Nur Ashikyn; Yahaya, Hafizal; Mahmood, Mohamad Rusop; Terasako, Tomoaki; Hashim, Abdul Manaf

    2014-01-01

    The electrochemical growth of zinc oxide (ZnO) nanostructures on graphene on glass using zinc nitrate hexahydrate was studied. The effects of current densities and temperatures on the morphological, structural, and optical properties of the ZnO structures were studied. Vertically aligned nanorods were obtained at a low temperature of 75°C, and the diameters increased with current density. Growth temperature seems to have a strong effect in generating well-defined hexagonal-shape nanorods with a smooth top edge surface. A film-like structure was observed for high current densities above -1.0 mA/cm(2) and temperatures above 80°C due to the coalescence between the neighboring nanorods with large diameter. The nanorods grown at a temperature of 75°C with a low current density of -0.1 mA/cm(2) exhibited the highest density of 1.45 × 10(9) cm(-2). X-ray diffraction measurements revealed that the grown ZnO crystallites were highly oriented along the c-axis. The intensity ratio of the ultraviolet (UV) region emission to the visible region emission, I UV/I VIS, showed a decrement with the current densities for all grown samples. The samples grown at the current density below -0.5 mA/cm(2) showed high I UV/I VIS values closer to or higher than 1.0, suggesting their fewer structural defects. For all the ZnO/graphene structures, the high transmittance up to 65% was obtained at the light wavelength of 550 nm. Structural and optical properties of the grown ZnO structures seem to be effectively controlled by the current density rather than the growth temperature. ZnO nanorod/graphene hybrid structure on glass is expected to be a promising structure for solar cell which is a conceivable candidate to address the global need for an inexpensive alternative energy source.

  17. Synthesis and study on the luminescence properties of cadmium borate phosphors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Annalakshmi, O.; Jose, M.T., E-mail: mtjosein@yahoo.co.in; Venkatraman, B.

    2014-02-01

    Highlights: • Cadmium borate synthesized by solid state sintering technique. • Neutron sensitivity of the material ten times that of TLD-600. • Gamma sensitivity is found to be twice that of TLD-100. • Gamma response is linear from 0.1 to 10{sup 3} mGy. - Abstract: Cadmium borate compound prepared through wet chemical reaction from the starting chemicals followed by high temperature solid state synthesis below the melting point to get the final TL phosphor powder. Phase purity and bond details of cadmium borate crystals are characterized using X-ray diffraction technique and infrared spectroscopy. Feasibility of these materials for radiation dosimetrymore » applications was studied after gamma and neutron irradiation. Gamma irradiation of undoped phosphors show a single peak around 185 °C whereas doping with gadolinium and silver, new more intense peak observed at 290 °C. Irradiation to thermal neutrons revealed single peak around 170 °C for all the phosphors. TL emission spectra and photoluminescence (PL) studies were also carried out on the phosphors. These borate materials are found to be highly sensitive to neutrons and hence can be used for neutron detection. Neutron sensitivity of the material is about ten times that of TLD-600.« less

  18. Synthesis and optical characterization of LiKB4O7, Li2B6O10, and LiCsB6O10 glasses.

    PubMed

    Adamiv, V; Teslyuk, I; Dyachok, Ya; Romanyuk, G; Krupych, O; Mys, O; Martynyuk-Lototska, I; Burak, Ya; Vlokh, R

    2010-10-01

    In the current work we report on the synthesis of LiKB(4)O(7), Li(2)B(6)O(10), and LiCsB(6)O(10) borate glasses. The results for their piezo-optic, acousto-optic, acoustic, elastic, refractive, optical transmission, and optical resistance properties are also presented. It is shown that some of these glasses represent efficient acousto-optic materials that are transparent down to the vacuum ultraviolet range and highly resistant to laser radiation.

  19. Synthesis and characterization of barium fluoride substituted zinc tellurite glasses

    NASA Astrophysics Data System (ADS)

    Aishwarya, K.; Vinitha, G.; Varma, G. Sreevidya; Asokan, S.; Manikandan, N.

    2017-12-01

    Glasses in the TeO2-ZnO-BaF2 system were prepared by standard melt quenching technique and were characterized for their thermal, optical and structural properties. Samples were found to show good thermal stability with values ranging above 100 °C for all the compositions. Optical bandgap and refractive index values were calculated from linear optical measurements using UV-Vis spectroscopy. Infrared spectra showed the presence of hydroxyl groups in the glasses indicating that the effect of fluorine was negligible in removing the hydroxyl impurities for the experimental conditions and compositions used. Raman measurements showed the modification occurring in the glass network due to addition of barium fluoride in terms of increase in the formation of non-bridging oxygen atoms compared to strong Te-O-Te linkages in the glass matrix.

  20. Co-precipitation synthesis of nano-composites consists of zinc and tin oxides coatings on glass with enhanced photocatalytic activity on degradation of Reactive Blue 160 KE2B.

    PubMed

    Habibi, Mohammad Hossein; Mardani, Maryam

    2015-02-25

    Nano-composite containing zinc oxide-tin oxide was obtained by a facile co-precipitation route using tin chloride tetrahydrate and zinc chloride as precursors and coated on glass by Doctor Blade deposition. The crystalline structure and morphology of composites were evaluated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The XRD results showed peaks relative to zinc oxide with hexagonal wurtzite structure and tin oxide with tetragonal structure. FESEM observations showed that the nano-composite consisted of aggregates of particles with an average particle size of 18 nm. The photocatalytic activity of the pure SnO2, pure ZnO, ZnSnO3-Zn2SnO4 and ZnO-SnO2 nano-structure thin films was examined using the degradation of a textile dye Reactive Blue 160 (KE2B). ZnO-SnO2 nano-composite showed enhanced photo-catalytic activity than the pure zinc oxide and tin oxide. The enhanced photo-catalytic activity of the nano-composite was ascribed to an improved charge separation of the photo-generated electron-hole pairs. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Effect of Gamma Radiation on Absorption of Light in Potassium-Aluminoborate Glasses with Additions of Iron Oxide

    NASA Astrophysics Data System (ADS)

    Ibragimova, E. M.; Salakhitdinov, A. N.; Salakhitdinova, M. K.; Yusupov, A. A.

    2018-05-01

    The effect of radiation on the absorption of light by potassium-alumina-borate glasses with various concentrations of iron additions and various thicknesses was investigated. It was shown that in contrast to samples of small thickness (1 mm) a bleaching effect was observed in the samples with a thickness of 8 mm. A possible mechanism involving the formation of nanostructured units is proposed for the observed effect.

  2. Graphene-containing PCL- coated Porous 13-93B3 Bioactive Glass Scaffolds for Bone Regeneration

    NASA Astrophysics Data System (ADS)

    Türk, Mert; Deliormanlı, Aylin M.

    2018-04-01

    Borate-based 13-93B3 bioactive glass scaffolds were coated with the graphene-containing poly-caprolactone (PCL) solution to prepare electrically conductive composites for biomedical applications. Results revealed that electrical conductivity of the scaffolds increased with increasing concentration of graphene nanoparticles. Significant difference was not observed in hydroxyapatite forming ability of the bare and the graphene-containing scaffolds immersed in simulated body fluid. In vitro cytotoxicity experiments (XTT tests) showed that pre-osteoblastic MC3T3-E1 cell viability percentages of the graphene- containing samples was higher than control group samples after 7 days of incubation. However, a decrease in cell viability rates was obtained after 14 days of incubation for samples coated with PCL containing graphene starting from 3 wt%. Additionally, results obtained in the live-dead assay were consistent with the results of XTT tests. A higher ALP activity was detected in cells cultured on the graphene-containing borate glass scaffolds than those on the bare PCL coated 13-93B3 scaffolds suggesting the presence of graphene nanopowders stimulated an early stage of osteoblastic differentiation. SEM analysis showed that MC3T3-E1 cells exhibited a flat appearance and spread out through the surface in all groups of scaffolds starting from 3 days of incubation.

  3. Lithium-aluminum-zinc phosphate glasses activated with Tb3+ and Tb3+/Eu3+ for green laser medium, reddish-orange and white phosphor applications

    NASA Astrophysics Data System (ADS)

    Francisco-Rodriguez, H. I.; Lira, A.; Soriano-Romero, O.; Meza-Rocha, A. N.; Bordignon, S.; Speghini, A.; Lozada-Morales, R.; Caldiño, U.

    2018-05-01

    A spectroscopic analysis of Tb3+ and Tb3+/Eu3+ doped lithium-aluminum-zinc phosphate glasses is performed through their absorbance and photoluminescence spectra, and decay time profiles. Laser parameter values (stimulated emission cross section, effective bandwidth, gain bandwidth and optical gain) were obtained for the terbium 5D4 → 7F5 green emission from the Tb3+ singly-doped glass (LAZT) excited at 350 nm to judge the suitability of the glass phosphor for fiber lasers. A quantum yield of (47.68 ± 0.49)% was measured for the 5D4 level luminescence. Upon 350 nm excitation the LAZT glass phosphor emits green light with a color purity of 65.6% and chromaticity coordinates (0.285, 0.585) very close to those (0.29, 0.60) of European Broadcasting Union illuminant green. The Tb3+/Eu3+codoped glass emission color can be tuned from reddish-orange of 1865 K upon 318 nm excitation to warm white of 3599 K and neutral white of 4049 K upon 359 and 340 nm excitations, respectively. Upon Tb3+ excitation at 340 nm Eu3+ is sensitized by Tb3+ through a non-radiative energy transfer with an efficiency of 0.23-0.26. An electric dipole-dipole interaction might be the dominant mechanism in the Tb3+ to Eu3+ energy transfer taking place into Tb3+ - Eu3+ clusters.

  4. Effect of Borates and Silicates on Wearing Properties of Mao Coatings

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Zhao, Yan-Wei; Xiang, Nan; Song, Ren-Guo

    In the present study, microarc oxidation (MAO) coatings were formed on ZL101A aluminum alloy in an electrolytic bath containing 3g/L KOH + 2g/L Na2WO4+ 4g/L KF. The morphology and wearing behavior were investigated. In both electrolytes, the additives were borates (Na2B4O718g/L) and silicates (Na2SiO3 18g/L), respectively. It was found that the coating formed in borates-containing electrolyte was of compact and smooth structure than that of the one formed in silicates-containing electrolyte at the optimum treatment time. It was found that all the coatings were composed of á-Al2O3 and ã-Al2O3. The microhardness and wear tests proved that the coating formed in borates-containing electrolyte was having better mechanical properties than those of the coating formed in silicates-containing electrolyte.

  5. Passive safety injection system using borated water

    DOEpatents

    Conway, Lawrence E.; Schulz, Terry L.

    1993-01-01

    A passive safety injection system relies on differences in water density to induce natural circulatory flow patterns which help maintain prescribed concentrations of boric acid in borated water, and prevents boron from accumulating in the reactor vessel and possibly preventing heat transfer.

  6. Supramolecular assembly of borate with quaternary ammonium: Crystal structure and tunable luminescent properties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liang, Jie; Wang, Yong-gang; Wang, Ying-xia, E-mail: wangyx@pku.edu.cn

    2013-04-15

    A new borate [C{sub 6}H{sub 16}N][B{sub 5}O{sub 6}(OH){sub 4}] (1) is synthesized hydrothermally by the reaction of isopropyltrimethylammonium hydroxide with boric acid. It crystallizes in the triclinic space group P-1 with the parameters a=9.1578(10) Å, b=9.372(9) Å, c=9.9812(10) Å, α=66.508(2)°, β=74.751(2)°, γ=81.893(2)°. The [B{sub 5}O{sub 6}(OH){sub 4}]{sup −} anions are interlinked via hydrogen bonding forming a 3D supramolecular network containing large cavities, where reside the (CH{sub 3}){sub 3}(i-C{sub 3}H{sub 7}) N{sup +} cations. This borate shows tunable luminescent properties with temperature, heating-treatment, exciting-light, and solvents. The fluorescent intensity of 1 enhances 6-fold with decreasing the temperature from 25 K tomore » 78 K. By treatment under different temperatures, the luminescence of 1 shifted from blue to white and the sample treated at 230 °C emits bright white light to naked eyes. The hybrid borate can disperse in different solvents, and shows a red-shifted and intense emission in polar solvents. - Graphical abstract: The new quaternary ammonium borate [C{sub 6}H{sub 17}N][B{sub 5}O{sub 6}(OH){sub 4}] contains a 3D supramolecular network formed by hydrogen bond linked [B{sub 5}O{sub 6}(OH){sub 4}]{sup −} anions and shows tunable luminescent properties with temperature, excitation light, and solvents. Highlights: ► A novel quaternary ammonium borate was synthesized. ► It possesses a supramolecular network fomed by H-bonded [B{sub 5}O{sub 6}(OH){sub 4}]{sup −} anions. ► This borate shows tunable luminescent properties with temperature, heating treatment, excitation light, and solvents.« less

  7. Laboratory evaluation of borate:amine:copper derivatives In wood for fungal decay protection

    Treesearch

    George Chen

    2011-01-01

    This study aimed to evaluate borate:amine:copper derivatives in wood for fungal decay protection as well as the permanence of copper and boron in wood. Each of four derivatives of borate:amine:copper prevented fungal decay in wood. Disodium tetraborate decahydrate (borax):amine:copper derivatives with 0.61-0.63% retention after water leaching prevented decay by...

  8. Atom probe tomography of lithium-doped network glasses.

    PubMed

    Greiwe, Gerd-Hendrik; Balogh, Zoltan; Schmitz, Guido

    2014-06-01

    Li-doped silicate and borate glasses are electronically insulating, but provide considerable ionic conductivity. Under measurement conditions of laser-assisted atom probe tomography, mobile Li ions are redistributed in response to high electric fields. In consequence, the direct interpretation of measured composition profiles is prevented. It is demonstrated that composition profiles are nevertheless well understood by a complex model taking into account the electronic structure of dielectric materials, ionic mobility and field screening. Quantitative data on band bending and field penetration during measurement are derived which are important in understanding laser-assisted atom probe tomography of dielectric materials. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Concentration-dependent studies of Nd3+ -doped zinc phosphate glasses for NIR photoluminescence at 1.05 μm.

    PubMed

    Reddy Prasad, V; Seshadri, M; Babu, S; Ratnakaram, Y C

    2017-05-01

    Nd 3 + -doped lead-free zinc phosphate glasses with the chemical compositions (60-x) NH 4 H 2 PO 4  + 20ZnO + 10BaF 2  + 10NaF + xNd 2 O 3 (where x = 0.5, 1.0, 1.5, 2.0 and 2.5 mol%) were prepared using a melt quenching technique. Vibrational bands were assigned and clearly elucidated by Raman spectral profiles for all the glass samples. Judd-Ofelt (J-O) intensity parameters (Ω λ : λ = 2, 4, 6) were obtained from the spectral intensities of different absorption bands of Nd 3 + ions. Radiative properties such as radiative transition probabilities (A R ), radiative lifetimes (τ R ) and branching ratios (β R ) for different excited states were calculated using J-O parameters. The near infrared (NIR) photoluminescence spectra exhibited three emission bands ( 4 F 3 /2 level to 4 I 13 /2 , 4 I 11 /2 and 4 I 9 /2 states) for all the concentrations of Nd 3 + ions. Various luminescence properties were studied by varying the Nd 3 + concentration for the three spectral profiles. Fluorescence decay curves of the 4 F 3 /2 level were recorded. The energy transfer mechanism that leads to quenching of the 4 F 3 /2 state lifetimes was discussed at higher concentration of Nd 3 + ions. These glasses are suggested as suitable hosts to produce efficient lasing action in NIR region at 1.05 μm. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Relaxation and physical aging in network glasses: a review.

    PubMed

    Micoulaut, Matthieu

    2016-06-01

    Recent progress in the description of glassy relaxation and aging are reviewed for the wide class of network-forming materials such as GeO2, Ge x Se1-x , silicates (SiO2-Na2O) or borates (B2O3-Li2O), all of which have an important usefulness in domestic, geological or optoelectronic applications. A brief introduction of the glass transition phenomenology is given, together with the salient features that are revealed both from theory and experiments. Standard experimental methods used for the characterization of the slowing down of the dynamics are reviewed. We then discuss the important role played by aspects of network topology and rigidity for the understanding of the relaxation of the glass transition, while also permitting analytical predictions of glass properties from simple and insightful models based on the network structure. We also emphasize the great utility of computer simulations which probe the dynamics at the molecular level, and permit the calculation of various structure-related functions in connection with glassy relaxation and the physics of aging which reveal the non-equilibrium nature of glasses. We discuss the notion of spatial variations of structure which leads to the concept of 'dynamic heterogeneities', and recent results in relation to this important topic for network glasses are also reviewed.

  11. Development of Natural Anthocyanin Dye-Doped Silica Nanoparticles for pH and Borate-Sensing Applications

    NASA Astrophysics Data System (ADS)

    Ha, Chu T.; Lien, Nghiem T. Ha; Anh, Nguyen D.; Lam, Nguyen L.

    2017-12-01

    Anthocyanin belongs to a large group of phenolic compounds called flavonoids. It is found primarily in fruits, flowers, roots and other parts of higher plants. Within the black carrot, it has been found that the cyanidin component 1,2 diol was the major anthocyanine. Since the terminal thiols potentially display chemical interactions with borate additives, anthocyanin from the black carrot can act as a sensing material for detecting borate in the environment. As a natural dye, anthocyanin responds to pH change of the medium. Here, we present an application of black carrot dyes for pH sensing and for the detection of borate additives within meats. The dyes were encapsulated within a mesoporous silica (SiO2) matrix in order to prevent the sensing materials from dissolution into the aqueous medium. The encapsulation was done in situ during preparation of silica nanoparticles (size from 100 nm to 500 nm) following an advanced Stöber method. These anthocyanin-encapsulated silica nanoparticles show a clear color change from green in an aqueous solution free of borate to GRAY-red in the presence of borate additive and red (pH 2) to green (pH 10).

  12. Sol-gel synthesis and in vitro bioactivity of copper and zinc-doped silicate bioactive glasses and glass-ceramics.

    PubMed

    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.

  13. Simultaneous immobilization of borate, arsenate, and silicate from geothermal water derived from mining activity by co-precipitation with hydroxyapatite.

    PubMed

    Sasaki, Keiko; Hayashi, Yoshikazu; Toshiyuki, Kenta; Guo, Binglin

    2018-09-01

    The treatment of the geothermal water discharged through mining activity is a critical issue because the rate of discharge is 12,000 m 3 per day and the discharge contains high concentrations of borate (>20 mg/L) and arsenate (ca. 0.4 mg/L) as well as silicate and carbonate. The simultaneous reduction of borate and arsenate concentrations to acceptable levels was successfully performed by co-precipitation with hydroxyapatite (HAp). Although the coexisting high concentrations of carbonate act as a disturbing element, the co-precipitation equilibrium of borate was shifted to lower values by adjusting the P/Ca molar ratio, and the removal rate of borate was accelerated by using Al 3+ additives, resulting in the efficient reduction of borate within 1 h. The initially immobilized boron in HAp is in the tetragonal form, which probably occupies the hydroxyl sites in HAp, gradually transforming into the trigonal form in the solid state, as interpreted by 1 H NMR and 11 B-NMR. The coexisting silicate was also immobilized in an ellestadite form, as confirmed by 29 Si-NMR measurements. Arsenate and silicate were immobilized before borate in geothermal water. A dissolution assay of borate in the solid residues after co-precipitation with HAp verified the acceptable stability of borate, which is independent of the amount of added Al 3+ . Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Rare earth separations by selective borate crystallization

    PubMed Central

    Yin, Xuemiao; Wang, Yaxing; Bai, Xiaojing; Wang, Yumin; Chen, Lanhua; Xiao, Chengliang; Diwu, Juan; Du, Shiyu; Chai, Zhifang; Albrecht-Schmitt, Thomas E.; Wang, Shuao

    2017-01-01

    Lanthanides possess similar chemical properties rendering their separation from one another a challenge of fundamental chemical and global importance given their incorporation into many advanced technologies. New separation strategies combining green chemistry with low cost and high efficiency remain highly desirable. We demonstrate that the subtle bonding differences among trivalent lanthanides can be amplified during the crystallization of borates, providing chemical recognition of specific lanthanides that originates from Ln3+ coordination alterations, borate polymerization diversity and soft ligand coordination selectivity. Six distinct phases are obtained under identical reaction conditions across lanthanide series, further leading to an efficient and cost-effective separation strategy via selective crystallization. As proof of concept, Nd/Sm and Nd/Dy are used as binary models to demonstrate solid/aqueous and solid/solid separation processes. Controlling the reaction kinetics gives rise to enhanced separation efficiency of Nd/Sm system and a one-step quantitative separation of Nd/Dy with the aid of selective density-based flotation. PMID:28290448

  15. 40 CFR 721.1880 - Borate(1-), tris(acetato-.kappa.O)hydro-, sodium, (T-4)-.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...)hydro-, sodium, (T-4)-. 721.1880 Section 721.1880 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.1880 Borate(1-), tris(acetato-.kappa.O)hydro-, sodium... substance identified as borate(1-), tris(acetato-.kappa.O)hydro-, sodium, (T-4)- (PMN P-00-0922; CAS No...

  16. 40 CFR 721.1880 - Borate(1-), tris(acetato-.kappa.O)hydro-, sodium, (T-4)-.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...)hydro-, sodium, (T-4)-. 721.1880 Section 721.1880 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.1880 Borate(1-), tris(acetato-.kappa.O)hydro-, sodium... substance identified as borate(1-), tris(acetato-.kappa.O)hydro-, sodium, (T-4)- (PMN P-00-0922; CAS No...

  17. Effect of B2O3 on luminescence of erbium doped tellurite glasses.

    PubMed

    Shen, Xiang; Nie, Qiuhua; Xu, Tiefeng; Dai, Shixun; Wang, Xunsi

    2007-02-01

    The B2O3 was introduced into the Er3+ doped TeO2-ZnO-Na2O glass to increase the phonon energy of the host. The effect of B2O3 on the non-radiative rate of the 4I11/2-->4I13/2 transition of Er3+, the lifetime of the 4I11/2 and 4I13/2 levels, the green and red upconversion emissions intensity, and the 4I13/2-->4I15/2 emission intensity was discussed. The results show that the phonon energy of boro-tellurite glass is close to that of germanate glass and is quite smaller than that of borate glass. The lifetime of 4I11/2 level and the upconversion emissions decrease with increasing B2O3 concentration. The higher OH group concentration presented in the boro-tellurite glass may shorten the lifetime of 4I13/2 level and also reduce the quantum efficiency of 4I13/2-->4I15/2 emission. The future dehydrating procedures are suggested to enhance the efficiency of amplification at 1.5 microm band.

  18. 76 FR 74831 - Aging Management of Stainless Steel Structures and Components in Treated Borated Water

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-01

    ... exposed to treated borated water. In response to a request from the Nuclear Energy Institute (NEI), the... NUCLEAR REGULATORY COMMISSION [NRC-2011-0256] Aging Management of Stainless Steel Structures and Components in Treated Borated Water AGENCY: Nuclear Regulatory Commission. ACTION: Draft interim staff...

  19. Metal-Enhanced Fluorescence from Nanoparticulate Zinc Films

    PubMed Central

    Aslan, Kadir; Previte, Michael J.R.; Zhang, Yongxia; Geddes, Chris D.

    2009-01-01

    A detailed study of metal-enhanced fluorescence (MEF) from fluorophores in the blue-to- red spectral region placed in close proximity to thermally evaporated zinc nanostructured films is reported. The zinc nanostructured films were deposited onto glass microscope slides as individual particles and were 1–10 nm in height and 20–100 nm in width, as characterized by Atomic Force Microscopy. The surface plasmon resonance peak of the zinc nanostructured films was ≈ 400 nm. Finite-difference time-domain calculations for single and multiple nanostructures organized in a staggered fashion on a solid support predict, as expected, that the electric fields are concentrated both around and between the nanostructures. Additionally, Mie scattering calculations show that the absorption and scattering components of the extinction spectrum are dominant in the UV and visible spectral ranges, respectively. Enhanced fluorescence emission accompanied by no significant changes in excited state lifetimes of fluorophores with emission wavelengths in the visible blue-to-red spectral range near-to zinc nanostructured films were observed, implying that MEF from zinc nanostructured films is mostly due to an electric field enhancement effect. PMID:19946356

  20. Thermoluminescent properties of rare earth doped lithium strontium borate phosphors

    NASA Astrophysics Data System (ADS)

    Jakathamani, S.; Annalakshmi, O.; Jose, M. T.

    2018-04-01

    Thermoluminescence (TL) of borates is remarkable in the field of radiation dosimetry because they can detect both neutron and gamma radiations. Usually, the TL efficiency of pure borates is low and hence dopants have to be added to increase their TL output. Their sensitivity and thermal stability vary widely and depend strongly on the preparation method. In this study polycrystalline powders of different rare earth doped thermoluminescent phosphors of Lithium Strontium borate (LSB) were synthesized by solid state sintering technique. Among the different rare earth dopants, the phosphor doped with cerium was found to have a simple glow curve structure with a dosimetric peak at around 265°C for a heating rate of 5°C/s. In order to study the effect of dopant on the TL characteristics, LSB phosphor with different concentrations of Ce dopant was synthesized and the TL intensity was found to be maximum for a dopant concentration of 0.7 mol%. All other important dosimetric characteristics like dose response and fading were carried out for the LSB:Ce (0.7 mol%) phosphor. Kinetic parameters like trap depth and frequency factor were determined using Peak shape method from Chen's equation.

  1. Engineering and Development Support of General Decon Technology for the DARCOM Installation Restoration Program. Task 4. General Technology Literature Searches (II) Solidification Techniques for Lagoon Waters

    DTIC Science & Technology

    1980-12-01

    40.8 Sodium 70.1 Zinc 0.01 37 The process includes the following steps (Pichat et al., 1979): - neutralization precipitation (silicates, borates...Compressive Strength of Polyester - Encapsulated Sodium Sulfate Waste Composite ....... .............. 64 9. Deep Chemical Mixer Mounted on a Barge...zinc, copper, lead, manganese and tin; sodium salts of arsenate, borate, phosphate, iodate, and sulfide; and sulfate salts. Sulfate salts form calcium

  2. Elastic, optical and structural features of wide range of CdO- Na2B4O7 glasses

    NASA Astrophysics Data System (ADS)

    Saddeek, Y. B.; Aly, K. A.; Shaaban, Kh S.; Mossad Ali, Atif; Sayed, M. A.

    2018-06-01

    Wide range of CdO—Na2B4O7 glasses have been prepared and characterized via XRD, FTIR and UV spectroscopies along with DTA and ultrasonic techniques. The compositional dependence of the physical parameters such as the density, the molar volume, the optical transmittance, the optical band gap, the ultrasonic velocities and the elastic moduli on CdO content were determined. The profiles of XRD assured the amorphous nature of the explored glasses. The clarification of the borate and cadmium functional groups besides their linkages was extracted from the deconvoluted FTIR spectra. Such a clarification was used in the analysis of the relation of the mechanical, T g and optical parameters versus CdO content. These physical parameters revealed the glass modifier role of CdO.

  3. Borate protection of softwood from Coptotermes acinaciformis (Isoptera: Rhinotermitidae) damage: variation in protection thresholds explained.

    PubMed

    Peters, Brenton C; Fitzgerald, Christopher J

    2006-10-01

    Laboratory and field data reported in the literature are confusing with regard to "adequate" protection thresholds for borate timber preservatives. The confusion is compounded by differences in termite species, timber species and test methodology. Laboratory data indicate a borate retention of 0.5% mass/mass (m/m) boric acid equivalent (BAE) would cause > 90% termite mortality and restrict mass loss in test specimens to < or = 5%. Field data generally suggest that borate retentions appreciably > 0.5% m/m BAE are required. We report two field experiments with varying amounts of untreated feeder material in which Coptotermes acinaciformis (Froggatt) (Isoptera: Rhinotermitidae) responses to borate-treated radiata (Monterey) pine, Pinus radiata D. Don, were measured. The apparently conflicting results between laboratory and field data are explained by the presence or absence of untreated feeder material in the test environment. In the absence of untreated feeder material, wood containing 0.5% BAE provided adequate protection from Coptotermes sp., whereas in the presence of untreated feeder material, increased retentions were required. Furthermore, the retentions required increased with increased amounts of susceptible material present. Some termites, Nasutitermes sp. and Mastotermes darwiniensis Froggatt, for example, are borate-tolerant and borate timber preservatives are not a viable management option with these species. The lack of uniform standards for termite test methodology and assessment criteria for efficacy across the world is recognized as a difficulty with research into the performance of timber preservatives with termites. The many variables in laboratory and field assays make "prescriptive" standards difficult to recommend. The use of "performance" standards to define efficacy criteria ("adequate" protection) is discussed.

  4. Remineralization Property of an Orthodontic Primer Containing a Bioactive Glass with Silver and Zinc

    PubMed Central

    Lee, Seung-Min; Kim, In-Ryoung; Park, Bong-Soo; Ko, Ching-Chang; Son, Woo-Sung; Kim, Yong-Il

    2017-01-01

    White spot lesions (WSLs) are irreversible damages in orthodontic treatment due to excessive etching or demineralization by microorganisms. In this study, we conducted a mechanical and cell viability test to examine the antibacterial properties of 0.2% and 1% bioactive glass (BAG) and silver-doped and zinc-doped BAGs in a primer and evaluated their clinical applicability to prevent WSLs. The microhardness statistically significantly increased in the adhesive-containing BAG, while the other samples showed no statistically significant difference compared with the control group. The shear bond strength of all samples increased compared with that of the control group. The cell viability of the control and sample groups was similar within 24 h, but decreased slightly over 48 h. All samples showed antibacterial properties. Regarding remineralization property, the group containing 0.2% of the samples showed remineralization properties compared with the control group, but was not statistically significant; further, the group containing 1% of the samples showed a significant difference compared with the control group. Among them, the orthodontic bonding primer containing 1% silver-doped BAG showed the highest remineralization property. The new orthodontic bonding primer used in this study showed an antimicrobial effect, chemical remineralization effect, and WSL prevention as well as clinically applicable properties, both physically and biologically. PMID:29088092

  5. New insight in the nature of surface magnetic anisotropy in iron borate

    NASA Astrophysics Data System (ADS)

    Strugatsky, M.; Seleznyova, K.; Zubov, V.; Kliava, J.

    2018-02-01

    The theory of surface magnetism of iron borate, FeBO3, has been extended by taking into consideration a crystal field contribution to the surface magnetic anisotropy energy. For this purpose, a model of distortion of the six-fold oxygen environment of iron ions in the near-surface layer of iron borate has been put forward. The spin Hamiltonian parameters for isolated Fe3+ ions in the distorted environment of the near-surface layer have been calculated using the Newman's superposition model. The crystal field contribution to the surface magnetic anisotropy energy has been calculated in the framework of the perturbation theory. The model developed allows concluding that the distortions of the iron environment produce a significant crystal field contribution to the surface magnetic anisotropy constant. The results of experimental studies of the surface magnetic anisotropy in iron borate can be described assuming the existence of relative contractions in the near-surface layer of the order of 1 %.

  6. Geochemical characteristics of Kırka (Sarıkaya) borate deposit, northwestern Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    Koçak, İ.; Koç, Ş.

    2016-02-01

    The Kırka borate deposit was deposited in a Miocene lacustrine basin which is closely associated with volcanic activity which lasted from Paleogene to the beginning of Quaternary. Borate mineralization alternates with claystone, mudstone, tuff and fine-layered limestone and mostly shows a lenticular structure. The mineral paragenesis is composed of borax, tincalconite, ulexite, kurnakovite, probertite, tunellite, colemanite, dolomite, smectite group minerals, illite and some firstly reported minerals for the Kırka deposit including hydrochloroborite, brianroulstonite, hilgardite-4M and searlesite minerals. In comparison to average values of earth crust, concentrations of Cs, Sr, Li, As and Se were significantly enriched with respective rates of 21, 15, 14, 3 and 188 folds. Regarding KY, KS1 and KS2 locations, there are differences in both element abundances and their geochemical tendencies which are attributed to variations in discharge regime and physico-chemical conditions of the depositional environment. Independent behaviour of B2O3 might indicate that boron is not associated with clays and carbonates and, therefore, most part of boron must be derived from volcanic activity (hydrothermal solutions, gases). REE data indicate that the Kırka borate deposit was formed in a sedimentary environment where highly alkaline (high pH) hydrothermal solutions also took part in borate precipitation process.

  7. Theoretical Studies of the Spin Hamiltonian Parameters and Local Distortions for Cu2+ in Alkaline Earth Lead Zinc Phosphate Glasses

    NASA Astrophysics Data System (ADS)

    Wang, Bo-Kun; Wu, Shao-Yi; Yuan, Zi-Yi; Liu, Zi-Xuan; Jiang, Shi-Xin; Liu, Zheng; Yao, Zi-Jian; Teng, Bao-Hua; Wu, Ming-He

    2016-08-01

    The spin Hamiltonian parameters and local structures are theoretically studied for Cu2+-doped alkaline earth lead zinc phosphate (RPPZ, R=Mg, Ca, Sr, and Ba) glasses based on the high-order perturbation calculations for a tetragonally elongated octahedral 3d9 cluster. The relative elongation ratios are found to be ρ≈3.2%, 4.4%, 4.6%, and 3.3% for R=Mg, Ca, Sr, and Ba, respectively, because of the Jahn-Teller effect. The whole decreasing crystal-field strength Dq and orbital reduction factor k from Mg to Sr are ascribed to the weakening electrostatic coulombic interactions and the increasing probability of productivity of nonbridge oxygen (and hence increasing Cu2+-O2- electron cloud admixtures) under PbO addition, respectively, with increasing alkali earth ionic radius. The anomalies (the largest Dq and the next highest k among the systems) for R=Ba are attributed to the cross linkage of this large cation in the network. The overall increasing order (Mg≤Baglasses containing copper dopants.

  8. 40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Boric acid and its salts, borax... salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric anhydride... its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric...

  9. 40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Boric acid and its salts, borax... salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric anhydride... its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric...

  10. 40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Boric acid and its salts, borax... salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric anhydride... its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric...

  11. 40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Boric acid and its salts, borax... salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric anhydride... its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric...

  12. Bandgap-Engineered Zinc-Tin-Oxide Thin Films for Ultraviolet Sensors.

    PubMed

    Cheng, Tien-Hung; Chang, Sheng-Po; Chang, Shoou-Jinn

    2018-07-01

    Zinc-tin-oxide thin-film transistors were prepared by radio frequency magnetron co-sputtering, while an identical zinc-tin-oxide thin film was deposited simultaneously on a clear glass substrate to facilitate measurements of the optical properties. When we adjusted the deposition power of ZnO and SnO2, the bandgap of the amorphous thin film was dominated by the deposition power of SnO2. Since the thin-film transistor has obvious absorption in the ultraviolet region owing to the wide bandgap, the drain current increases with the generation of electron-hole pairs. As part of these investigations, a zinc-tin-oxide thin-film transistor has been fabricated that appears to be very promising for ultraviolet applications.

  13. Borate cross-linked graphene oxide-chitosan as robust and high gas barrier films

    NASA Astrophysics Data System (ADS)

    Yan, Ning; Capezzuto, Filomena; Lavorgna, Marino; Buonocore, Giovanna G.; Tescione, Fabiana; Xia, Hesheng; Ambrosio, Luigi

    2016-05-01

    Chitosan (CS) is one of the most promising polymers due to its biocompatibility, biodegradability, and natural abundance. However, its poor mechanical and barrier properties make it difficult to satisfy a wide range of applications. Herein, borate ions, originating from the hydrolysis of sodium tetraborate decahydrate (borax), have been used to crosslink chitosan and graphene oxide (GO) nanocomposites. Chitosan films consisting of 1.0 wt% boron and 1.0 wt% GO exhibit a significant improvement in both the toughness and oxygen barrier properties compared to pristine chitosan. In particular the tensile strength of the samples after thermal treatment increases by ~160% compared to pristine chitosan, whereas their oxygen permeability reduces by ~90%. This is ascribed to the chemical crosslinking between chitosan and GO nanoplatelets through borate ions, as well as the formation of a layered morphology with graphene nanoplatelets oriented parallel to the sample surface. The exceptional robust and high gas barrier film has promising application in the packaging industry. The borate-crosslinking chemistry represents the potential strategy for improving properties of other polymer nanocomposites.Chitosan (CS) is one of the most promising polymers due to its biocompatibility, biodegradability, and natural abundance. However, its poor mechanical and barrier properties make it difficult to satisfy a wide range of applications. Herein, borate ions, originating from the hydrolysis of sodium tetraborate decahydrate (borax), have been used to crosslink chitosan and graphene oxide (GO) nanocomposites. Chitosan films consisting of 1.0 wt% boron and 1.0 wt% GO exhibit a significant improvement in both the toughness and oxygen barrier properties compared to pristine chitosan. In particular the tensile strength of the samples after thermal treatment increases by ~160% compared to pristine chitosan, whereas their oxygen permeability reduces by ~90%. This is ascribed to the chemical

  14. Crystal Structure Characterization of Thin Layer Zinc Oxide

    NASA Astrophysics Data System (ADS)

    Doyan, Aris; Susilawati; Azizatul Fitri, Siti; Ahzan, Sukainil

    2017-05-01

    In this research the characterization of the crystal structure of a thin layer of ZnO (zinc oxide) were synthesized by sol - gel method and spin coating deposited on a glass substrate. The samples were divided into three sol concentrations of 0.1, 0.3, 0.5 Molar and two deposition temperature is 350 °C, and 550 °C. UV-Vis. spectrophotometer results showed that in the spectrum of visible light (wavelength range 300-800 nm) has a transmittance value of which increases with increasing concentration and temperature deposition of zinc oxide, otherwise the value of the absorption and the band gap energy decreases with the addition of concentration and deposition temperature. The transmittances value of the highest and lowest absorption was 93.5% and 0.03 is at a concentration of 0.1 M and zinc oxide deposition temperature of 550 °C, with a value of band gap energy of 2.98 eV. The XRD results showed that the zinc oxide crystal orientation in the field of 013 with a crystal grain size 14.4472 nm. SEM results showed the surface morphology of zinc oxide such as rod-like.

  15. A preliminary analysis of the data from experiment 77-13 and final report on glass fining experiments in zero gravity

    NASA Technical Reports Server (NTRS)

    Wilcox, W. R.; Subramanian, R. S.; Meyyappan, M.; Smith, H. D.; Mattox, D. M.; Partlow, D. P.

    1981-01-01

    Thermal fining, thermal migration of bubbles under reduced gravity conditions, and data to verify current theoretical models of bubble location and temperatures as a function of time are discussed. A sample, sodium borate glass, was tested during 5 to 6 minutes of zero gravity during rocket flight. The test cell contained a heater strip; thermocouples were in the sample. At present quantitative data are insufficient to confirm results of theoretical calculations.

  16. Processing and optical characterization of lead calcium titanate borosilicate glass doped with germanium

    NASA Astrophysics Data System (ADS)

    Gautam, C. R.; Das, Sangeeta; Gautam, S. S.; Madheshiya, Abhishek; Singh, Anod Kumar

    2018-04-01

    In this study, various compositions of lead calcium titanate borosilicate glass doped with a fixed amount of germanium were synthesized using the rapid melt quench technique. The amorphous nature of the synthesized glass was confirmed by X-ray diffraction and scanning electron microscopy analyses. The structural and optical properties were deduced using Raman, Fourier transform infrared (FTIR), and ultraviolet-visible (UV-Vis) spectroscopy. FTIR spectroscopy confirmed the presence of borate groups in triangular and tetrahedral coordination. Infrared and Raman analyses detected the vibrational bonds of Gesbnd Osbnd Ge, Bsbnd Osbnd Ge, Sisbnd Osbnd Ge, Sisbnd Osbnd Si, and Pbsbnd Osbnd Ge. The energy band gaps were evaluated for the prepared glass samples based on Tauc plots of the UV-Vis spectra. The calculated values of the optical band gap decreased from 2.91 to 2.85 eV as the PbO content increased from x = 0.0 to x = 0.7. Furthermore, the Urbach energy was studied based on the UV-Vis results to confirm the disordered structure of the glass. The calculated densities of the glass samples (1.5835 g/cm3 to 3.9184 g/cm3) increased as the concentration of PbO increased, whereas they decreased with the molar volume.

  17. Calibration of the borated ion chamber at NIST reactor thermal column.

    PubMed

    Wang, Z; Hertel, N E; Lennox, A

    2007-01-01

    In boron neutron capture therapy and boron neutron capture enhanced fast neutron therapy, the absorbed dose of tissue due to the boron neutron capture reaction is difficult to measure directly. This dose can be computed from the measured thermal neutron fluence rate and the (10)B concentration at the site of interest. A borated tissue-equivalent (TE) ion chamber can be used to directly measure the boron dose in a phantom under irradiation by a neutron beam. Fermilab has two Exradin 0.5 cm(3) Spokas thimble TE ion chambers, one loaded with boron, available for such measurements. At the Fermilab Neutron Therapy Facility, these ion chambers are generally used with air as the filling gas. Since alpha particles and lithium ions from the (10)B(n,alpha)(7)Li reactions have very short ranges in air, the Bragg-Gray principle may not be satisfied for the borated TE ion chamber. A calibration method is described in this paper for the determination of boron capture dose using paired ion chambers. The two TE ion chambers were calibrated in the thermal column of the National Institute of Standards and Technology (NIST) research reactor. The borated TE ion chamber is loaded with 1,000 ppm of natural boron (184 ppm of (10)B). The NIST thermal column has a cadmium ratio of greater than 400 as determined by gold activation. The thermal neutron fluence rate during the calibration was determined using a NIST fission chamber to an accuracy of 5.1%. The chambers were calibrated at two different thermal neutron fluence rates: 5.11 x 10(6) and 4.46 x 10(7)n cm(-2) s(-1). The non-borated ion chamber reading was used to subtract collected charge not due to boron neutron capture reactions. An optically thick lithium slab was used to attenuate the thermal neutrons from the neutron beam port so the responses of the chambers could be corrected for fast neutrons and gamma rays in the beam. The calibration factor of the borated ion chamber was determined to be 1.83 x 10(9) +/- 5.5% (+/- 1sigma) n

  18. Effect of lithium on thermal and structural properties of zinc vanadate tellurite glass

    NASA Astrophysics Data System (ADS)

    Rani, Sunita; Kundu, R. S.; Ahlawat, Neetu; Rani, Suman; Sangwan, Kanta Maan; Ahlawat, Navneet

    2018-04-01

    Glasses having composition 60TeO2-15V2O5-(25-x) ZnO-xLi2O where x= 0, 5, 10 mol% were prepared by standard melt quench technique. The glass transition temperature is measured by DSC technique using TA instrument and found to decrease with increase in Li2O signifies that glass formation tendency, thermal stability and compactness of glass structure decreases. The deconvolution of FTIR spectra evidenced the existence of TeO4, TeO3 and TeO6 structural units in glass network and vanadium exists as VO4 and VO5 structural units.

  19. Synthesis, Tribological and Hydrolysis Stability Study of Novel Benzotriazole Borate Derivative

    PubMed Central

    Liping, Xiong; Zhongyi, He; Liang, Qian; Lin, Mu; Aixi, Chen; Sheng, Han; Jianwei, Qiu; Xisheng, Fu

    2014-01-01

    Benzotriazole and borate derivatives have long been used as multifunctional additives to lubricants. A novel, environmentally friendly additive borate ester (NHB), which contains boron, ethanolamine, and benzotriazole groups in one molecule, was synthesized by a multi-step reaction, and its tribological properties in rapeseed oil (RSO) were investigated by a four-ball tribometer. The hydrolysis stability of the additive was investigated by half-time and open observation methods, and the mechanism of hydrolysis stability was discussed through Gaussian calculation. The novel compound NHB showed excellent performance under extreme pressure, against wearing, and in reducing friction, and its hydrolysis time is more than 1,220 times, which is better than that of triethyl borate. The mass ratio of NHB is bigger than that of the mixed liquid of triethyl borate and ethanolamine. The lone electron of amino N atoms forms a coordination effect with the B atom to compensate for the shortage of electrons in the B atom and to improve the hydrolysis stability of NHB. The surface morphology and the traces of different elements in the tribofilms formed with 1.0 wt.% NHB in were detected with scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy (EDX)and X-ray photoelectron spectroscopy(XPS). The results shown that the additive caused a tribochemical reaction with the steel ball surface during the lubricating process. A mixed boundary lubrication film that contains organic nitrogen and inorganic salts, such as BN, B2O3, FeOx, Fe–O–B, and FeB, was also formed, and the formation of the lubricating film improved the tribological properties of the base oil. PMID:24465382

  20. Structural investigation and optical properties of xMnO2-25Li2O-5Na2O-15Bi2O3-(55-x)B2O3 glasses

    NASA Astrophysics Data System (ADS)

    Kulkarni, Shilpa; Jali, V. M.

    2018-02-01

    This paper deals with the new mixed system of glass compositions Lithium sodium bismuth borate glasses doped with transition metal oxide. The technique used to prepare a sample is by melt quenching. The XRD profile pattern confirmed the amorphous phase of the present glass system. The network structure is based on BO3, BO4 units and BiO6 octahedral units. No boroxyl rings observed in the glass structure. The addition of MnO2 in small amount does not account for major structural changes. Optical band gap lies in the range 1.89 to 0.96 eV. Density, molar volume, oxygen packing density, Tg, direct optical band gap and refractive index show anomalous behavior.

  1. Gels and gel-derived glasses in the system Na2O-B2O3-SiO2

    NASA Technical Reports Server (NTRS)

    Mukherjee, S. P.

    1983-01-01

    The containerless melting of high-purity multicomponent homogeneous gels and gel monoliths offers a unique approach to making ultrapure multicomponent optical glasses in the reduced gravity environment of space. Procedures for preparing and characterizing gels and gel-derived glasses in the system Na2O-B2O3-SiO2 are described. Preparation is based on the polymerization reactions of alkoxysilane with trimethyl borate or boric acid and a suitable sodium compound. The chemistry of the gelling process is discussed in terms of process parameters and the gel compositions. The physicochemical nature of gels prepared by three different procedures was found to be significantly different. Infrared absorption spectra indicate finite differences in the molecular structures of the different gels. The melting of the gel powders and the transformation of porous gel monoliths to transparent 'glass' without melting are described.

  2. Production and Characterization of a Ag- and Zn-Doped Glass-Ceramic Material and In Vitro Evaluation of Its Biological Effects

    NASA Astrophysics Data System (ADS)

    Baghbani, Fatemeh; Moztarzadeh, Fathollah; Mozafari, Masoud; Raz, Majid; Rezvani, Hamideh

    2016-08-01

    Bioactive glasses in the system SiO2-CaO-Na2O-P2O5-MgO with different amounts of zinc (Zn) and silver (Ag) were synthesized by the sol-gel technique and characterized. The bioactivity was studied during in vitro assays: the ability of hydroxycarbonate apatite (HCA) layer to form on the glass surface was examined after contact with simulated body fluid (SBF). The x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and inductively coupled plasma atomic emission spectrometry (ICP) studies were performed after immersion in vitro assays. Also, the antibacterial and antifungal activities of glass samples against Pseudomonas aeruginosa (ATCC 27853), E. coli (ATCC 25922), and Candida albicans were measured by the halo zone test. Introduction of zinc and silver as the trace elements induces several modifications on the observed phenomena at the glass surface and in SBF solution after immersion of the samples. The chemical durability of the glasses, the formation of the silica-rich layer, and the crystallization of the HCA layer were affected. Samples with the higher content of zinc and silver exhibited an excellent antibacterial/antifungal activity.

  3. Temperature and frequency dependent conductivity of bismuth zinc vanadate semiconducting glassy system

    NASA Astrophysics Data System (ADS)

    Punia, R.; Kundu, R. S.; Dult, Meenakshi; Murugavel, S.; Kishore, N.

    2012-10-01

    The ac conductivity of bismuth zinc vanadate glasses with compositions 50V2O5. xBi2O3. (50-x) ZnO has been studied in the frequency range 10-1 Hz to 2 MHz and in temperature range 333.16 K to 533.16 K. The temperature and frequency dependent conductivity is found to obey Jonscher's universal power law for all the compositions of bismuth zinc vanadate glass system. The dc conductivity (σdc), crossover frequency (ωH), and frequency exponent (s) have been estimated from the fitting of experimental data of ac conductivity with Jonscher's universal power law. Enthalpy to dissociate the cation from its original site next to a charge compensating center (Hf) and enthalpy of migration (Hm) have also been estimated. It has been observed that mobility of charge carriers and ac conductivity in case of zinc vanadate glass system increases with increase in Bi2O3 content. In order to determine the conduction mechanism, the ac conductivity and its frequency exponent have been analyzed in the frame work of various theoretical models based on classical hopping over barriers and quantum mechanical tunneling. The ac conduction takes place via tunneling of overlapping large polarons in all the compositions of presently studied vanadate glasses. The fitting of experimental data of ac conductivity with overlapping large polarons tunneling model has also been done. The parameters; density of states at Fermi level (N(EF)), activation energy associated with charge transfer between the overlapping sites (WHO), inverse localization length (α) and polaron radius (rp) obtained from fitting of this model with experimental data are reasonable.

  4. Application of zinc oxide quantum dots in food safety

    USDA-ARS?s Scientific Manuscript database

    Zinc oxide quantum dots (ZnO QDs) are nanoparticles of purified powdered ZnO. The ZnO QDs were directly added into liquid foods or coated on the surface of glass jars using polylactic acid (PLA) as a carrier. The antimicrobial activities of ZnO QDs against Listeria monocytogenes, Salmonella Enteriti...

  5. Thermophysical and structural studies on some glass-ceramics and role of nano size crystallites

    NASA Astrophysics Data System (ADS)

    Kothiyal, G. P.; Arvind, A.; Kumar, Rakesh; Dixit, Anupam; Sharma, Kuldeep; Goswami, Madhumita

    2009-07-01

    In this paper, we present some studies on structure and thermophysical properties of glass and glass-ceramics with possible bio-medical and sealing applications. The glass-ceramics prepared for bio-medical applications include phosphate as well as silico-phosphate compositions. In vitro bio-compatibility/activity of these materials is discussed. The glass-ceramics used for the sealing application are lithium aluminium silicate (LAS) and lithium zinc silicate (LZS). The phase formation and some aspects of thermophysical properties and sealing are discussed.

  6. Thermal and structural properties of zinc modified tellurite based glasses

    NASA Astrophysics Data System (ADS)

    Kundu, R. S.; Dhankhar, Sunil; Punia, R.; Dult, Meenakshi; Kishore, N.

    2016-05-01

    Glass system 60 TeO2 - 10 B2O3-(30-x) Bi2O3-x ZnO with mole fraction x = 10, 15, 20, 25 and 30 were synthesized by conventional melt quenching technique under controlled atmospheric conditions. The glass transition temperature (Tg) has been determined using differential scanning Calorimetry (DSC) and its value is observed to increase with increase in ZnO content. This increase may be due to the increase in the concentration of the bridging oxygen (BO) atoms. IR and Raman spectra of the present glass system indicate that ZnO acts as network modifier and exists in ZnO4 units. TeO2 exists as TeO3, TeO4, and TeO3+1 structural units. Bismuth plays the role of network modifier with BiO6 octahedral structural units whereas B2O3 exists in the form of BO3 trigonal and BO4 tetrahedral structural units.

  7. Bioactive calcium phosphate–based glasses and ceramics and their biomedical applications: A review

    PubMed Central

    Islam, Md Towhidul; Felfel, Reda M; Abou Neel, Ensanya A; Grant, David M; Ahmed, Ifty; Hossain, Kazi M Zakir

    2017-01-01

    An overview of the formation of calcium phosphate under in vitro environment on the surface of a range of bioactive materials (e.g. from silicate, borate, and phosphate glasses, glass-ceramics, bioceramics to metals) based on recent literature is presented in this review. The mechanism of bone-like calcium phosphate (i.e. hydroxyapatite) formation and the test protocols that are either already in use or currently being investigated for the evaluation of the bioactivity of biomaterials are discussed. This review also highlights the effect of chemical composition and surface charge of materials, types of medium (e.g. simulated body fluid, phosphate-buffered saline and cell culture medium) and test parameters on their bioactivity performance. Finally, a brief summary of the biomedical applications of these newly formed calcium phosphate (either in the form of amorphous or apatite) is presented. PMID:28794848

  8. Bioactive calcium phosphate-based glasses and ceramics and their biomedical applications: A review.

    PubMed

    Islam, Md Towhidul; Felfel, Reda M; Abou Neel, Ensanya A; Grant, David M; Ahmed, Ifty; Hossain, Kazi M Zakir

    2017-01-01

    An overview of the formation of calcium phosphate under in vitro environment on the surface of a range of bioactive materials (e.g. from silicate, borate, and phosphate glasses, glass-ceramics, bioceramics to metals) based on recent literature is presented in this review. The mechanism of bone-like calcium phosphate (i.e. hydroxyapatite) formation and the test protocols that are either already in use or currently being investigated for the evaluation of the bioactivity of biomaterials are discussed. This review also highlights the effect of chemical composition and surface charge of materials, types of medium (e.g. simulated body fluid, phosphate-buffered saline and cell culture medium) and test parameters on their bioactivity performance. Finally, a brief summary of the biomedical applications of these newly formed calcium phosphate (either in the form of amorphous or apatite) is presented.

  9. 40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric anhydride), sodium borate and sodium metaborate; exemptions from the requirement of a tolerance. 180.1121 Section 180.1121 Protection of Environment ENVIRONMENTAL PROTECTION...

  10. Treatment of cells with alkaline borate buffer extends the capability of interphase FISH mapping.

    PubMed

    Yokota, H; van den Engh, G; Mostert, M; Trask, B J

    1995-01-20

    Interphase fluorescence in situ hybridization (FISH) has been shown to be a means to map DNA sequences relative to each other in the 100 kb to 1-2 Mb genomic-separation range. At distances below 0.1 Mb, probe sites are infrequently resolved in interphase chromatin. In the 0.1- to 1-Mb range, interphase chromatin can be modeled as a freely flexible chain. The mean square interphase distance between two probes is proportional to the genomic separation between the probes on the linear DNA molecule. Above 1-2 Mb, the relationship between interphase distance and genomic separation changes abruptly and appears to level off. We have used alkaline-borate treatment to expand the capability of interphase FISH mapping. We show here that alkaline-borate treatment increases nuclear diameter, the interphase distance between probes on homologous chromosomes, and the distance between probes on the same chromosome. We also show that the mean square distance between hybridization sites in borate-treated nuclei is proportional to genomic separation up to 4 Mb. Thus, alkaline-borate treatment enhances the capability of interphase FISH mapping by increasing the absolute distance between probes and extending the range of the simple relationship between interphase distance and genomic separation.

  11. Treatment of cells with alkaline borate buffer extends the capability of interphase FISH mapping

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yokota, H.; Van Den Engh, G.; Mostert, M.

    1995-01-20

    Interphase fluorescence in situ hybridization (FISH) has been shown to be a means to map DNA sequences relative to each other in the 100 kb to 1-2 Mb genomic-separation range. At distances below 0.1 Mb, probe sites are infrequently resolved in interphase chromatin. In the 0.1- to 1-Mb range, interphase chromatin can be modeled as a freely flexible chain. The mean square interphase distance between two probes is proportional to the genomic separation between the probes on the linear DNA molecule. Above 1-2 Mb, the relationship between interphase distance and genomic separation changes abruptly and appears to level off. Wemore » have used alkaline-borate treatment to expand the capability of interphase FISH mapping. We show here that alkaline-borate treatment increases nuclear diameter, the interphase distance between probes on homologous chromosomes, and the distance between probes on the same chromosome. We also show that the mean square distance between hybridization sites in borate-treated nuclei is proportional to genomic separation up to 4 Mb. Thus, alkaline-borate treatment enhances the capability of interphase FISH mapping by increasing the absolute distance between probes and extending the range of the simple relationship between interphase distance and genomic separation. 31 refs., 5 figs.« less

  12. Acute and chronic respiratory effects of sodium borate particulate exposures.

    PubMed Central

    Wegman, D H; Eisen, E A; Hu, X; Woskie, S R; Smith, R G; Garabrant, D H

    1994-01-01

    This study examined work-related chronic abnormality in pulmonary function and work-related acute irritant symptoms associated with exposure to borate dust in mining and processing operations. Chronic effects were examined by pulmonary function at the beginning and end of a 7-year interval. Time-specific estimates of sodium borate particulate exposures were used to estimate cumulative exposure during the study interval. Change in pulmonary function over the 7 years was found unrelated to the estimate of cumulative exposure during that interval. Exposure-response associations also were examined with respect to short-term peak exposures and incidence of five symptoms of acute respiratory irritation. Hourly measures of health outcome and continuous measures of particulate exposure were made on each subject throughout the day. Whenever a subject reported one of the irritant symptoms, a symptom intensity score was also recorded along with the approximate time of onset. The findings indicated that exposure-response relationships were present for each of the specific symptoms at several symptom intensity levels. The associations were present when exposure was estimated by both day-long and short-term (15-min) time-weighted average exposures. Associations persisted after taking account of smoking, age, and the presence of a common cold. No significant difference in response rate was found between workers exposed to different types of sodium borate dusts. PMID:7889871

  13. Review: emerging developments in the use of bioactive glasses for treating infected prosthetic joints.

    PubMed

    Rahaman, Mohamed N; Bal, B Sonny; Huang, Wenhai

    2014-08-01

    Bacterial contamination of implanted orthopedic prostheses is a serious complication that requires prolonged systemic antibiotic therapy, major surgery to remove infected implants, bone reconstruction, and considerable morbidity. Local delivery of high doses of antibiotics using poly(methyl methacrylate) (PMMA) cement as the carrier, along with systemic antibiotics, is the standard treatment. However, PMMA is not biodegradable, and it can present a surface on which secondary bacterial infection can occur. PMMA spacers used to treat deep implant infections must be removed after resolution of the infection. Alternative carrier materials for antibiotics that could also restore deficient bone are therefore of interest. In this article, the development of bioactive glass-based materials as a delivery system for antibiotics is reviewed. Bioactive glass is osteoconductive, converts to hydroxyapatite, and heals to hard and soft tissues in vivo. Consequently, bioactive glass-based carriers can provide the combined functions of controlled local antibiotic delivery and bone restoration. Recently-developed borate bioactive glasses are of particular interest since they have controllable degradation rates coupled with desirable properties related to osteogenesis and angiogenesis. Such glasses have the potential for providing a new class of biomaterials, as substitutes for PMMA, in the treatment of deep bone infections. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Synthesis, characterisation, electrical and optical properties of copper borate compounds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kipcak, Azmi Seyhun; Senberber, Fatma Tugce; Aydin Yuksel, Sureyya

    2015-10-15

    Highlights: • Cu(BO{sub 2}){sub 2} was synthesized at the form of with pdf number of “00-001-0472”. • Particle sizes were found between 162.72 and 56.44 nm and 195.76 and 75.73 nm at CuSNaH. • Reaction yields were 90.4 ± 0.84, 96.9 ± 0.78 and 78.9 ± 0.76% for CuST, CuSB and CuSNaH. • The resistivity of CuST, CuSB and CuSNaH are 1.10 × 10{sup 7}, 7.02 × 10{sup 6} and 8.62 × 10{sup 5} Ωm. • The optical energy gap was 3.76 eV. - Abstract: The hydrothermal synthesis of copper borate compounds [Cu(BO{sub 2}){sub 2}] was studied, and several parametersmore » were found to affect the synthesis. Raw materials, including CuSO{sub 4}·5H{sub 2}O, Na{sub 2}B{sub 4}O{sub 7}·5H{sub 2}O, Na{sub 2}B{sub 4}O{sub 7}·10H{sub 2}O, NaOH and H{sub 3}BO{sub 3}, were used. Reaction temperatures and reaction times between 40 °C and 100 °C and 15 and 240 min, respectively, were used. The as-synthesised copper borate was analysed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The yields of the reactions were also calculated. Single-phase, nanoparticulate copper borate compounds (Cu(BO{sub 2}){sub 2}) possessing high XRD crystal scores were obtained; the reactions used to obtain these materials were highly efficient. Electrical resistivity and optical absorbance measurements were carried out on the compounds obtained from the highest yielding reactions. The results of this study showed that even using a reaction time of 15 min, copper borate formation was successfully achieved.« less

  15. Spectral-luminescent and laser properties of the (Y1-x,Ybx)2O3-Al2O3-B2O3 glasses

    NASA Astrophysics Data System (ADS)

    Malashkevich, G. E.; Kouhar, V. V.; Pestryakov, E. V.; Sigaev, V. N.; Golubev, N. V.; Ziyatdinova, M. Z.; Sukhodola, A. A.

    2018-02-01

    Yttrium-alumina-borate glasses activated by the Yb3+ ions with compositions close to the huntite-like (Y1-xLnx)Al3(BO3)4 crystals have been synthesized by conventional melt-quenching technique in a platinum crucible, and their spectral-luminescent and laser properties have been investigated. It is established that this activator forms in the given glass one type of optical centers having the radiation decay time of 870 ± 40 μs. The limiting quantum yield of its luminescence in the case of complete dehydration of the glass will amount to ≈94%. The main laser parameters have been calculated and the nonlinearity of the refractive index and the threshold of laser-induced destruction of the glass surface have been determined. The lasing has been obtained on the glass plate of 2.1 mm thickness with a threshold of ≈60 W/mm2 estimated by specific absorbed power.

  16. Structural, optical, physical and electrical properties of V2O5.SrO.B2O3 glasses.

    PubMed

    Sindhu, S; Sanghi, S; Agarwal, A; Seth, V P; Kishore, N

    2006-05-01

    The present work aims to study the structure and variation of optical band gap, density and dc electrical conductivity in vanadium strontium borate glasses. The glass systems xV2O5.(40-x)SrO.60B2O3 and xV2O5.(60-x)B2O3.40SrO with x varying from 0 to 20 mol% were prepared by normal melt quench technique. Structural studies were made by recording IR transmission spectra. The fundamental absorption edge for all the glasses was analyzed in terms of the theory proposed by Davis and Mott. The position of absorption edge and hence the value of the optical band gap was found to depend on the semiconducting glass composition. The absorption in these glasses is believed to be associated with indirect transitions. The origin of Urbach energy is associated with the phonon-assisted indirect transitions. The change in both density and molar volume was discussed in terms of the structural modifications that take place in the glass matrix on addition of V2O5. dc conductivity of the glass systems is also reported. The change of conductivity and activation energy with composition indicates that the conduction process varies from ionic to polaronic one.

  17. Delamination propensity of pharmaceutical glass containers by accelerated testing with different extraction media.

    PubMed

    Guadagnino, Emanuel; Zuccato, Daniele

    2012-01-01

    The delamination of pharmaceutical glass is a serious issue, as it can cause glass particles to appear in vials, a problem that has forced a number of drug product recalls in recent years. In Type I pharmaceutical glass vials, delamination occurs generally at the bottom and shoulder, where extensive flaming during the conversion process can favor a strong evaporation of alkali and borate species and the formation of heavily enriched silica layers. The contact with parenteral preparations dissolved in an alkaline medium increases the rate of glass corrosion, while the differential hydration of these layers can cause the detachment of flakes. The purpose of this study was to investigate the effect of the pH and the composition of the extraction solutions on the propensity of different glass types to delaminate. Repeated autoclave extractions at 121 °C were carried out on different glass types with different extraction media, including organic extractants like citric and glutaric acid. When vials were in contact with alkaline solutions and similarly aggressive media, an increase in silica extraction values indicated glass corrosion and an increasing risk for further delamination. Under such conditions expansion 33 glass is extensively corroded, showing high silica concentration and heavy flaking as compared to other glass types. Sulfur-treated glass also showed early flaking, even if SiO(2) concentration was very low. A similar ranking was observed with extractions carried out with glutaric and citric acids, but at far much higher SiO(2) concentration levels. Extractions with 0.9% KCl solution can be used as an accelerated test to highlight the propensity of a glass to delaminate, but in no case it can be taken as a guarantee that the glass will not delaminate when exposed to the pharmaceutical drug, whose extraction ability requires case-by-case study. How can injectable drug manufacturers prevent glass delamination? The issue of delamination is a serious one, as it

  18. Calcium and Zinc Containing Bactericidal Glass Coatings for Biomedical Metallic Substrates

    PubMed Central

    Esteban-Tejeda, Leticia; Díaz, Luis A.; Prado, Catuxa; Cabal, Belén; Torrecillas, Ramón; Moya, José S.

    2014-01-01

    The present work presents new bactericidal coatings, based on two families of non-toxic, antimicrobial glasses belonging to B2O3–SiO2–Na2O–ZnO and SiO2–Na2O–Al2O3–CaO–B2O3 systems. Free of cracking, single layer direct coatings on different biomedical metallic substrates (titanium alloy, Nb, Ta, and stainless steel) have been developed. Thermal expansion mismatch was adjusted by changing glass composition of the glass type, as well as the firing atmosphere (air or Ar) according to the biomedical metallic substrates. Formation of bubbles in some of the glassy coatings has been rationalized considering the reactions that take place at the different metal/coating interfaces. All the obtained coatings were proven to be strongly antibacterial versus Escherichia coli (>4 log). PMID:25056542

  19. EPR and impedance spectroscopic investigations on lithium bismuth borate glasses containing nickel and vanadium ions

    NASA Astrophysics Data System (ADS)

    Yadav, Arti; Khasa, Satish; Hooda, Ashima; Dahiya, Manjeet S.; Agarwal, Ashish; Chand, Prem

    2016-03-01

    Glasses having composition 7NiO • 23Li2O • 20Bi2O3 • 50B2O3, 7V2O5 • 23Li2O • 20Bi2O3 • 50B2O3 and x(2NiO • V2O5) • (30 - x)Li2O • 50B2O3 • 20Bi2O3 (with x = 0, 2, 5, 7 & 10 mol%) prepared through melt-quench route are explored by analyzing density, impedance spectroscopy and electron paramagnetic resonance (EPR). It is found that both density and molar volume increase with an increase in substitution of 2NiO • V2O5 in the base glass matrix. Different dielectric parameters viz. dielectric loss (ε), electrical modulus (M), loss tangent (tanδ) etc. are evaluated and their variations with frequency and temperature are analyzed which reveals that these glasses exhibit a non-Debye relaxation behavior. A phenomenal description of the capacitive behavior is obtained by considering the circuitry as a parallel combination of bulk resistance (Rb) and constant phase element (CPE). The conduction mechanism is found to follow Quantum Mechanical Tunneling (QMT) model. Spin Hamiltonian Parameters (SHPs) and covalency rates are calculated from the EPR spectra of vanadyl ion. The observed EPR spectra confirmed that V4 + ion exists as vanadyl ion in the octahedral coordination with tetragonal compression.

  20. Prominent spectral features of Sm3+ ion in disordered zinc tellurite glass

    NASA Astrophysics Data System (ADS)

    Tanko, Y. A.; Sahar, M. R.; Ghoshal, S. K.

    Trivalent rare earth doped glasses with modified spectroscopic features are essential for solid state lasers and diverse photonic applications. Glass composition optimisation may fulfil such demand. Stimulating the spectral properties of samarium (Sm3+) ions in tellurite glass host with desired enhancement is the key issue. Glasses with composition (80 - x)TeO2-20ZnO-(x)Sm2O3, where 0 ⩽ x ⩽ 1.5 mol% are prepared using melt quenching method. The role of varying Sm3+ contents to improving the absorption and emission properties of the prepared glasses are determined. XRD pattern verifies amorphous nature of synthesised glasses. FTIR spectroscopy has been used to observe the structural modification of (TeO4) trigonal bipyramid structural units. DTA traces display prominent transition peaks for glass transition, crystallisation and melting temperature. Samples are discerned to be stable with desired Hruby parameter and superior glass forming ability. The UV-Vis-NIR absorption spectra reveals nine peaks centred at 470, 548, 947, 1085, 1238, 1385, 1492, 1550 and 1589 nm. These bands arise due to 6H5/2 → 4I11/2, 4G5/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2 and 6F1/2 transitions, respectively. The direct, indirect band gap and Urbach energy calculated from the absorption edge of UV-Vis-NIR spectra are found to appear within (2.75-3.18) eV, (3.22-3.40) eV, and (0.20-0.31) eV, respectively. The observed increase in refractive index from 2.45 to 2.47 is ascribed to the generation of non-bridging oxygen atoms via the conversion of TeO4 into TeO3 units. Conversely the decrease in refractive index to 2.39 is attributed to the lower ionic radii (1.079 Å) of Sm3+. PL spectra under the excitation of 452 nm display four emission bands centred at 563, 600, 644 and 705 nm corresponding to 4G5/2 → 6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions of samarium ions. Excellent features of the results nominate these compositions towards prospective applications.

  1. Spectroscopic and thermal study of a new glass from TeO2sbnd Ga2O3sbnd GeO2 system

    NASA Astrophysics Data System (ADS)

    Marczewska, Agnieszka; Środa, Marcin

    2018-07-01

    Tellurium oxide and germanium oxide based glasses are classified as the heavy metal oxide glasses, with phonon energies below 880 cm-1. These glasses transmit to longer wavelengths when compared to borate, phosphate and silicate glasses because of the heavier mass of germanium. In this paper we present a new promising TeO2sbnd Ga2O3sbnd GeO2 glasses with high thermal stability and good optical properties in the near and mid-IR regions. The glass can be easily obtained for the wide range of Te/Ge ratio, which gives opportunity to engineering desirable properties. Based on the FT-IR spectra it could be stated that the tellurite network is monotonically transformed into germanate one as the GeO2 content increases. Admixtures of GeO2 into the network of tellurite glass causes the conversion of [TeO4] to [TeO3] units. Thus, the network of the glass could be consider as a mixture of the [TeO4], [TeO3] and [GeO4] units and with Ga3+ ions playing the role of its modifier. The glasses demonstrate high transmittance in mid-IR up to 6 μm what makes these materials suitable for mid-IR applications.

  2. Effect of cement kiln dust and gamma irradiation on the ultrasonic parameters of HMO borate glasses

    NASA Astrophysics Data System (ADS)

    Abd elfadeel, G.; Saddeek, Yasser B.; Mohamed, Gehan Y.; Mostafa, A. M. A.; Shokry Hassan, H.

    2017-03-01

    Glass samples with the chemical formula x CKD-(100 - x) (5Na2O-65 B2O3-9 Bi2O3-21PbO), (0 ⩽ x ⩽ 32 mol%) were prepared. The density and the ultrasonic estimations of the investigated glasses were analyzed at room temperature before and after the impact of two dosages of gamma irradiation to study the effect of both CKD and gamma radiation. It was found that the density, and the ultrasonic parameters are sensitive to the variety of the content of CKD and the effect of γ-radiation. Replacement of oxides with higher atomic weights such as Bi2O3 and PbO by CKD decreases the density. Analysis of the behavior of the ultrasonic parameters demonstrates that creation of CaO6 and SiO4 on one hand and an alternate transformation between BO4 and BO3 structural units, on the other hand, affect the increase of the ultrasonic velocities and the elastic moduli. Moreover, the density and the ultrasonic parameters decrease somewhat with the increase of the doses of γ-irradiation. The variations of the previous physical parameters can be referred to the creation of radiation imperfections, which occupied the voids inside the glass structure.

  3. Gels and gel-derived glasses in the Na2O-B2O3-SiO2 system. [containerless melting in space

    NASA Technical Reports Server (NTRS)

    Mukherjee, S. P.

    1982-01-01

    The containerless melting of high-purity multicomponent homogeneous gels and gel-monoliths offers a unique approach to making ultrapure multicomponent optical glasses in the reduced gravity environment of space. Procedures for preparing and characterizing gels and gel-derived glasses in the Na2O-B2O3-SiO2 system are described. Preparation is based on the polymerization reactions of alkoxysilane with trimethyl borate or boric acid and a suitable sodium compound. The chemistry of the gelling process is discussed in terms of process parameters and the gel compositions. The physicochemical nature of gels prepared by three different procedures were found to be significantly different. IR absorption spectra indicate finite differences in the molecular structures of the different gels. The melting of the gel powders and the transformation of porous gel-monoliths to transparent 'glass' without melting are described.

  4. XRD, Electron Microscopy and Vibrational Spectroscopy Characterization of Simulated SB6 HLW Glasses - 13028

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stefanovsky, S.V.; Institute of Physical Chemistry and Electrochemistry RAS, Leninskii av. 31, Moscow 119991; Nikonov, B.S.

    2013-07-01

    Sample glasses have been made using SB6 high level waste (HLW) simulant (high in both Al and Fe) with 12 different frit compositions at a constant waste loading of 36 wt.%. As follows from X-ray diffraction (XRD) and optical and scanning electron microscopy (SEM) data, all the samples are composed of primarily glass and minor concentration of spinel phases which form both isometric grains and fine cubic (∼1 μm) crystals. Infrared spectroscopy (IR) spectra of all the glasses within the range of 400-1600 cm{sup -1} consist of the bands due to stretching and bending modes in silicon-oxygen, boron-oxygen, aluminum-oxygen andmore » iron-oxygen structural groups. Raman spectra showed that for the spectra of all the glasses within the range of 850-1200 cm{sup -1} the best fit is achieved by suggestion of overlapping of three major components with maxima at 911-936 cm{sup -1}, 988-996 cm{sup -1} and 1020-1045 cm{sup -1}. The structural network is primarily composed of metasilicate chains and rings with embedded AlO{sub 4} and FeO{sub 4} tetrahedra. Major BO{sub 4} tetrahedra and BO{sub 3} triangles form complex borate units and are present as separate constituents. (authors)« less

  5. Order–Disorder Transitions and Superionic Conductivity in the Sodium nido -Undeca(carba)borates

    DOE PAGES

    Tang, Wan Si; Dimitrievska, Mirjana; Stavila, Vitalie; ...

    2017-11-20

    The salt compounds NaB 11H 14, Na-7-CB10H13, Li-7-CB 10H 13, Na-7,8-C 2B 9H 12, and Na-7,9-C 2B 9H 12 all contain geometrically similar, monocharged, nido-undeca(carba)borate anions (i.e., truncated icosohedral-shaped clusters constructed of only 11 instead of 12 {B-H} + {C-H} vertices and an additional number of compensating bridging and/or terminal H atoms). We used first-principles calculations, X-ray powder diffraction, differential scanning calorimetry, neutron vibrational spectroscopy, neutron elastic-scattering fixed-window scans, quasielastic neutron scattering, and electrochemical impedance measurements to investigate their structures, bonding potentials, phase-transition behaviors, anion orientational mobilities, and ionic conductivities compared to those of their closo-poly(carba)borate cousins. All exhibited order-disordermore » phase transitions somewhere between room temperature and 375 K. All disordered phases appear to possess highly reorientationally mobile anions (> ~10 10 jumps s -1 above 300 K) and cation-vacancy-rich, close-packed or body-center-cubic-packed structures [like previously investigated closo-poly(carba)borates]. Moreover, all disordered phases display superionic conductivities but with generally somewhat lower values compared to those for the related sodium and lithium salts with similar monocharged 1-CB 9H 10- and CB 11H 12- closo-carbaborate anions. This study significantly expands the known toolkit of solid-state, poly(carba)borate-based salts capable of superionic conductivities and provides valuable insights into the effect of crystal lattice, unit cell volume, number of carbon atoms incorporated into the anion, and charge polarization on ionic conductivity.« less

  6. Preparation and elastic moduli of germanate glass containing lead and bismuth.

    PubMed

    Sidek, Hj A A; Bahari, Hamid R; Halimah, Mohamed K; Yunus, Wan M M

    2012-01-01

    This paper reports the rapid melt quenching technique preparation for the new family of bismuth-lead germanate glass (BPG) systems in the form of (GeO(2))(60)-(PbO)(40-) (x)-(½Bi(2)O(3))(x) where x = 0 to 40 mol%. Their densities with respect of Bi(2)O(3) concentration were determined using Archimedes' method with acetone as a floatation medium. The current experimental data are compared with those of bismuth lead borate (B(2)O(3))(20)-(PbO)(80-) (x)-(Bi(2)O(3))(x). The elastic properties of BPG were studied using the ultrasonic pulse-echo technique where both longitudinal and transverse sound wave velocities have been measured in each glass samples at a frequency of 15 MHz and at room temperature. Experimental data shows that all the physical parameters of BPG including density and molar volume, both longitudinal and transverse velocities increase linearly with increasing of Bi(2)O(3) content in the germanate glass network. Their elastic moduli such as longitudinal, shear and Young's also increase linearly with addition of Bi(2)O(3) but the bulk modulus did not. The Poisson's ratio and fractal dimensionality are also found to vary linearly with the Bi(2)O(3) concentration.

  7. High-pressure synthesis and characterization of the first cerium fluoride borate CeB{sub 2}O{sub 4}F

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hinteregger, Ernst; Wurst, Klaus; Tribus, Martina

    2013-08-15

    CeB{sub 2}O{sub 4}F is the first cerium fluoride borate, which is exclusively built up of one-dimensional, infinite chains of condensed trigonal-planar [BO{sub 3}]{sup 3−} groups. This new cerium fluoride borate was synthesized under high-pressure/high-temperature conditions of 0.9 GPa and 1450 °C in a Walker-type multianvil apparatus. The compound crystallizes in the orthorhombic space group Pbca (No. 61) with eight formula units and the lattice parameters a=821.63(5), b=1257.50(9), c=726.71(6) pm, V=750.84(9) Å{sup 3}, R{sub 1}=0.0698, and wR{sub 2}=0.0682 (all data). The structure exhibits a 9+1 coordinated cerium ion, one three-fold coordinated fluoride ion and a one-dimensional chain of [BO{sub 3}]{sup 3−}more » groups. Furthermore, IR spectroscopy, Electron Micro Probe Analysis and temperature-dependent X-ray powder diffraction measurements were performed. - Graphical abstract: A new rare-earth fluoride borate CeB{sub 2}O{sub 4}F could be synthesized under high-pressure/high-temperature conditions of 0.9 °GPa and 1450 °Cin a Walker-type multianvil apparatus. The crystal structure represents a new structure type in the class of rare-earth fluoride borates. The structure exhibits a 9+1 coordinated cerium ion, one three-fold coordinated fluoride ion and a one-dimensional chain of [BO{sub 3}]{sup 3−} groups. A closer view on the ac-plane shows an interesting wave-like modulation of the borate chains. Highlights: • CeB{sub 2}O{sub 4}F is the first fluoride borate exclusively built up of one-dimensional, infinite chains of condensed trigonal-planar [BO{sub 3}]{sup 3−} groups. • CeB{sub 2}O{sub 4}F is the first cerium fluoride borate. • High-pressure conditions were necessary to synthesize CeB{sub 2}O{sub 4}F.« less

  8. Role of aluminum on the physical and spectroscopic properties of chromium-doped strontium alumino borate glasses

    NASA Astrophysics Data System (ADS)

    Ahmed, Mohamed Raheem; Sekhar, K. Chandra; Hameed, Abdul; Chary, M. Narasimha; Shareefuddin, Md

    2018-03-01

    The glass samples were prepared in accordance with the formula: (30-x)SrO-xAl2O3-69.8B2O3-0.2Cr2O3 (0 ≤x ≤ 15 mol %) by melt quenching method. The absence of Bragg’s peaks confirmed the amorphous nature of the prepared glass samples. It was observed that the molar volume was increasing while the density is decreasing with increasing of Al2O3 content. Optical absorption study was performed to evaluate the optical bandgap, oxygen packing density, ionic packing density and Urbach energies. The Racah parameters (B and C) and Dq/B ratio have been calculated. Fourier transform infrared (FTIR) spectra recorded in the region from 400-1600 cm-1 at room-temperature (RT) confirmed the formation of BO3, BO4 and AlO4 groups upon the addition of strontium oxide as modifier. The Raman spectra of all the glasses recorded over continuous spectral range 200-1600 cm-1 exhibited different spectral bands. The EPR spectra recorded at 9.7 GHz (X-band frequency) have four resonance signals. The signal at g ≈ 5.33 is due to Cr3+ ion sites of rhombic symmetry and signal at g ≈ 1.97 is due to contribution from Cr3+ and Cr5+ ion pairs.

  9. Effect of borate glass composition on its conversion to hydroxyapatite and on the proliferation of MC3T3-E1 cells.

    PubMed

    Brown, Roger F; Rahaman, Mohamed N; Dwilewicz, Agatha B; Huang, Wenhai; Day, Delbert E; Li, Yadong; Bal, B Sonny

    2009-02-01

    Glasses containing varying amounts of B(2)O(3) were prepared by partially or fully replacing the SiO(2) in silicate 45S5 bioactive glass with B(2)O(3). The effects of the B(2)O(3) content of the glass on its conversion to hydroxyapatite (HA) and on the proliferation of MC3T3-E1 cells were investigated in vitro. Conversion of the glasses to HA in dilute (20 mM) K(2)HPO(4) solution was monitored using weight loss and pH measurements. Proliferation of MC3T3-E1 cells was determined qualitatively by assay of cell density at the glass interface after incubation for 1 day and 3 days, and quantitatively by fluorescent measurements of total DNA in cultures incubated for 4 days. Higher B(2)O(3) content of the glass increased the conversion rate to HA, but also resulted in a greater inhibition of cell proliferation under static culture conditions. For a given mass of glass in the culture medium, the inhibition of cell proliferation was alleviated by using glasses with lower B(2)O(3) content, by incubating the cell cultures under dynamic rather than static conditions, or by partially converting the glass to HA prior to cell culture.

  10. Influence of CuO and ZnO addition on the multicomponent phosphate glasses: Spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Szumera, Magdalena; Wacławska, Irena; Sułowska, Justyna

    2016-06-01

    The spectra of phosphate-silicate glasses from the P2O5-SiO2-K2O-MgO-CaO system modified with the addition of CuO or ZnO have been studied by means of FTIR, Raman and 31P MAS NMR spectroscopy. All glasses were synthesized by the conventional melt-quenching technique and their homogeneous chemical composition was controlled and confirmed. By using the aforementioned research techniques, the presence of structural units with various degrees of polymerization was shown in the structure of analyzed phosphate-silicate glasses: Q3, Q2, Q1 and Q0. It was found that an increase in the content of CuO or ZnO in the composition of analyzed glasses, which are introduced at the expense of decreasing amounts of CaO and MgO, has a different influence on the phospho-oxygen network. It was shown that copper ions cause its gradual polymerization, while zinc ions cause its depolymerization. At the same time, polymerization of the silico-oxygen subnetwork was found. Additionally, in the case of glasses containing increasing amounts of ZnO, a change of the role of zinc ions in the vitreous matrix was confirmed (from the modifier to a structure-forming component).

  11. Structural properties of alkaline sodium lead fluoride borate glasses incorporated with Praseodymium ion

    NASA Astrophysics Data System (ADS)

    Lenkennavar, Susheela K.; Madhu, A.; Eraiah, B.; Kokila, M. K.

    2018-05-01

    The effect of different alkaline and Pr ions on the density and structure of Na2O-PbO-MO-B2O3 (M represents Ba/Ca/Sr) has been investigated using X-ray diffraction (XRD), infrared spectrophotometer (FTIR). The amorphous phase has been identified based on X-ray diffraction analysis. The Praseodymium oxide plays the role as a glass-modifier and influences on BO3↔BO4 conversion. The same effect is also observed in density and molar volume variation due to non bridging oxygen's (NBO) created when BO3 units are converted.

  12. Alkali-free bioactive glasses for bone regeneration =

    NASA Astrophysics Data System (ADS)

    Kapoor, Saurabh

    Bioactive glasses and glass-ceramics are a class of third generation biomaterials which elicit a special response on their surface when in contact with biological fluids, leading to strong bonding to living tissues. The purpose of the present study was to develop diopside based alkali-free bioactive glasses in order to achieve good sintering behaviour, high bioactivity, and a dissolution/ degradation rates compatible with the target applications in bone regeneration and tissue engineering. Another aim was to understand the structure-property relationships in the investigated bioactive glasses. In this quest, various glass compositions within the Diopside (CaMgSi2O6) - Fluorapatite (Ca5(PO4)3F) - Tricalcium phosphate (3CaO•P2O5) system have been investigated. All the glasses were prepared by melt-quenching technique and characterized by a wide array of complementary characterization techniques. The glass-ceramics were produced by sintering of glass powders compacts followed by a suitable heat treatment to promote the nucleation and crystallization phenomena. Furthermore, selected parent glass compositions were doped with several functional ions and an attempt to understand their effects on the glass structure, sintering ability and on the in vitro bio-degradation and biomineralization behaviours of the glasses was made. The effects of the same variables on the devitrification (nucleation and crystallization) behaviour of glasses to form bioactive glass-ceramics were also investigated. Some of the glasses exhibited high bio-mineralization rates, expressed by the formation of a surface hydroxyapatite layer within 1-12 h of immersion in a simulated body fluid (SBF) solution. All the glasses showed relatively lower degradation rates in comparison to that of 45S5 Bioglass. Some of the glasses showed very good in vitro behaviour and the glasses co-doped with zinc and strontium showed an in vitro dose dependent behaviour. The as-designed bioactive glasses and glass

  13. Bioactivity studies on TiO₂-bearing Na₂O-CaO-SiO₂-B₂O₃ glasses.

    PubMed

    Jagan Mohini, G; Sahaya Baskaran, G; Ravi Kumar, V; Piasecki, M; Veeraiah, N

    2015-12-01

    Soda lime silica borate glasses mixed with different concentrations of TiO2 are synthesized by the melt-quenching technique. As a part of study on bioactivity of these glasses, the samples were immersed in simulated body fluid (SBF) solution for prolonged times (~21 days) during which weight loss along with pH measurements is carried out at specific intervals of time. The XRD and SEM analyses of post-immersed samples confirm the formation of crystalline hydroxyapatite layer (HA) on the surface of the samples. To assess the role of TiO2 on the formation of HA layer and degradability of the samples the spectroscopic studies viz. optical absorption and IR spectral studies on post- and pre-immersed samples have been carried out. The analysis of the results of degradability together with spectroscopic studies as a function of TiO2 concentration indicated that about 6.0 mol% of TiO2 is the optimal concentration for achieving better bioactivity of these glasses. The presence of the maximal concentration octahedral titanium ions in this glass that facilitates the formation of HA layer is found to be the reason for such a higher bioactivity. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. The new silver borate Ag{sub 3}B{sub 5}O{sub 9}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sohr, Gerhard; Falkowski, Viktoria; Huppertz, Hubert, E-mail: hubert.huppertz@uibk.ac.at

    2015-05-15

    Single crystals of Ag{sub 3}B{sub 5}O{sub 9} were obtained via high-pressure synthesis at 3 GPa and 600 °C, using a Walker-type multianvil high-pressure device. Ag{sub 3}B{sub 5}O{sub 9} crystalizes with a=674.7(2), b=943.5(2), c=1103.5(2) pm, V=0.7025(2) nm{sup 3}, and Z=4 in the noncentrosymmetric space group P2{sub 1}2{sub 1}2{sub 1} (no. 19). The orthorhombic structure was refined from 3740 independent reflections with R1=0.0496 and wR2=0.587 (all data). It is built up from infinite corner-sharing chains of BO{sub 4} tetrahedra along the a axis, which are interconnected by BO{sub 3} groups to form a network. In the structure, three crystallographically independent sites aremore » occupied with Ag{sup +} cations exhibiting argentophillic interactions. The synthetic conditions as well as the results of the single crystal structure analysis are presented. - Graphical abstract: Noncentrosymmetric silver borate: During investigations in the system Ag–B–O, a new noncentrosymmetric silver borate Ag{sub 3}B{sub 5}O{sub 9} was discovered. The new structure type is built up from corner-sharing BO{sub 3} and BO{sub 4} groups, forming a network. Argentophillic interactions are clearly indicated by the Ag{sup +}⋯Ag{sup +} distances present in the structure. - Highlights: • A noncentrosymmetric borate Ag{sub 3}B{sub 5}O{sub 9} is accessible via high-pressure synthesis. • Ag{sub 3}B{sub 5}O{sub 9} is the second high-pressure silver borate. • Ag{sup +}⋯Ag{sup +} distances in Ag3B5O9 clearly indicate the presence of argentophillic interactions.« less

  15. Physical, structural and luminescence investigation of Eu3+-doped lithium-gadolinium bismuth-borate glasses for LEDs

    NASA Astrophysics Data System (ADS)

    Zaman, F.; Rooh, G.; Srisittipokakun, N.; Wongdeeying, C.; Kim, H. J.; Kaewkhao, J.

    2018-06-01

    The aim of the current report is to fabricate Eu3+-doped glasses with the chemical composition of 50Li2O-15Gd2O3-5Bi2O3-(30-x)B2O3-xEu2O3 (where x = 0.5, 1.0, 1.5, 2.0 and 2.5 mol%), with the help of conventional melt quenching technique. The fabricated glasses have been studied with help of physical, structural and luminescence properties for application of LEDs. The structural properties were investigated by XRD and FTIR spectra. Physical properties have been measured. Direct and indirect optical energy band gap (Eg) have been calculated and found to be increasing with Eu2O3 concentration. Luminescence spectra have been observed from photo and radioluminescence spectra and found in good agreement with each other, however the concentration quenching was not determined for the samples. The high-covalence and asymmetric nature was confirmed from Photoluminescence emission and RL emission transition as well as from the higher values of luminescence intensity ratio. The JO parameters have been found for the better performance of lasing materials. The lifetime's data have been found to be decreasing from 1.64 to 1.50 ms, which is the confirmation of energy transfer in Eu3+ ions through cross relaxations. From the calculated properties it has been suggested that the present glass samples might be good for red-light emitting devices.

  16. Spectroscopic Properties of B2O3-PbO-Nd2O3 Glasses

    NASA Astrophysics Data System (ADS)

    Simon, V.; Ardelean, I.; Milea, I.; Peteanu, M.; Simon, S.

    Samples belonging to xNd2O3(100-x) [2B2O3·PbO] glass system, with 0≤ x≤ 40 mol%, are investigated by IR and UV-VIS spectroscopies in order to obtain evidence for the influence of Nd2O3 on the local order from 2B2O3·PbO glass matrix. Besides the IR absorption bands characteristic to lead and boron arrangements, typical absorption lines of Nd3+ ions around 4000 cm-1 and 6000 cm-1 are recorded. The 6000 cm-1 band appears only for the samples with x≥25 mol% Nd2O3. The split of some UV-VIS absorption bands arising from transitions of neodymium ions in doublet lines as well as the shift of the absorption bands as the Nd2O3 content increases denote the influence of the lead-borate matrix on the radiative transitions of the lanthanide ion.

  17. Effect of temperature and thermal history on borosilicate glass structure

    NASA Astrophysics Data System (ADS)

    Angeli, Frédéric; Villain, Olivier; Schuller, Sophie; Charpentier, Thibault; de Ligny, Dominique; Bressel, Lena; Wondraczek, Lothar

    2012-02-01

    The influence of the temperature and quenching rate on the structure of a borosilicate glass was studied by high-resolution solid-state 11B, 23Na, 29Si nuclear magnetic resonance (NMR) and high-temperature Raman spectroscopy. Data were obtained for glass in the solid state after annealing and quenching at cooling rates covering four orders of magnitude as well as in the liquid state from Raman experiments and from calorimetry and rheological data. Nuclear magnetic resonance measurements were used to calibrate the Raman spectra in order to quantify the change in boron coordination with temperature. This result can then be used to determine the fictive temperature of the glass directly from the boron coordination. The fictive temperature, heat capacity, and configurational entropy are extracted from calorimetry and viscosity measurements. Changes in the boron coordination account for only 25% of the configurational heat capacity of the liquid. The structural parameters capable of accounting for the remaining quantity are discussed on the basis of structural data, both local (inhomogeneity of the sodium distribution) and medium-range (from NMR parameter distribution). It has thus been shown that, although the B-O-B angular distributions of the boroxol rings (and probably the Si-O-Si distributions) are not affected by temperature, a structural disorder is identified through the angular distributions of the bonds linking borate and silicate groups.

  18. A method for determining the composition of methanol-trimethyl borate mixtures

    NASA Technical Reports Server (NTRS)

    Kaye, Samuel; Sordyl, Frank

    1955-01-01

    A study of mixtures of pure methanol and trimethyl borate showed that the composition can be accurately obtained by a simple density determination. The refractive-index determination gives the composition with much less accuracy. The potentiometric titration of boric acid is also discussed.

  19. Comprehensive study on compositional modification of Tb3+ doped zinc phosphate glass

    NASA Astrophysics Data System (ADS)

    Yaacob, S. N. S.; Sahar, M. R.; Sazali, E. S.; Mahraz, Zahra Ashur; Sulhadi, K.

    2018-07-01

    Series of glass composition (60-x) P2O5 -40 ZnO -(x) Tb2O3 where x = 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mol % are prepared by conventional melt quenching technique. X-Ray Diffraction (XRD), FTIR, UV-Vis-NIR and the photoluminescence (PL) spectroscopy are used to characterize the physical, structural and optical behavior of the glass sample. The XRD pattern confirms the amorphous nature and DTA verified the thermal stability of all the glass samples. Glass with 1.5 mol % of Tb2O3 possesses the highest thermal stability. Glass density is found to increase proportionally with increasing amount of Tb3+ while the molar volume behaves reversely. Six main IR absorption bands centered at about 540, 748, 891, 1085 and 1294 cm- 1 are evidenced. The UV-Vis NIR absorption spectra reveals the absorption center band at about 540, 376, 488 and 1920 nm corresponding to the absorption from 7F6 ground state to various excited state of Tb3+ ion. The optical band gaps for direct and indirect transition are in the range 4.53-5.07 eV and 4.30 eV-4.56 eV respectively. The Urbach energy decreases with the increasing concentration of Tb2O3. The PL emission spectra reveals several prominent peaks at 413, 435, 457, 488, 540, 585 and 620 nm due to electronic transition from 5D3→7F5, 5D3→7F4, 5D3→7F3, 5D4→7F6, 5D4→7F5, 5D4→7F3 and 5D4→7F5 respectively.

  20. Solar water oxidation using nickel-borate coupled BiVO4 photoelectrodes.

    PubMed

    Choi, Sung Kyu; Choi, Wonyong; Park, Hyunwoong

    2013-05-07

    A naturally abundant nickel-borate (Ni-Bi) complex is demonstrated to successfully catalyze the photoelectrochemical (PEC) water oxidation of BiVO4 electrodes at 1.23 VRHE with nearly 100% faradaic efficiency for oxygen evolution. Ni-Bi is electrodeposited (ED) and photodeposited (PD) for varying times on BiVO4 electrodes in the 0.1 M borate electrolyte with 1 mM Ni(2+) at pH 9.2. Surprisingly, optimally deposited Ni-Bi films (ED-10 s and PD-30 min) display the same layer thickness of ca. 40 nm. Both Ni-Bi films enhance the photocurrent generation of BiVO4 at 1.23 VRHE by a factor of 3-4 under AM 1.5-light irradiation (100 mW cm(-2)) along with ca. 250% increase in the incident and absorbed photon-to-current efficiencies. Impedance analysis further reveals that the charge transfer resistance at BiVO4 is markedly decreased by Ni-Bi deposits. The primary role of Ni-Bi has been suggested to be a hole-conductor making photogenerated electrons more mobile and catalyzing a four-hole transfer to water through cyclic changes between the lower and higher Ni oxidation states. However, thick Ni-Bi films (>~40 nm) significantly reduce the PEC performance of BiVO4 due to the kinetic bottleneck and charge recombination. Under identical PEC conditions (0.1 M, pH 9.2), the borate electrolyte (good proton acceptor) is found to be better than nitrate (poor proton acceptor), indicative of a proton-coupled electron transfer pathway in PEC water oxidation.

  1. Structure of zinc and niobium tellurite glasses by neutron and x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Hoppe, U.; Yousef, E.; Rüssel, C.; Neuefeind, J.; Hannon, A. C.

    2004-03-01

    Neutron and x-ray diffraction experiments of high resolving power with neutrons from a spallation source and high-energy photons from a synchrotron have been performed on compositional series of binary Zn, Nb and on mixed Zn/Nb tellurite glasses. The Te-O, Zn-O and Nb-O coordination numbers are determined by Gaussian fitting of the first-neighbour peaks in the neutron and x-ray data simultaneously. The transition of TeO4 to TeO3 units with increasing fraction of a second component is indicated by decreasing total Te-O coordination numbers. This transition appears different for glasses with ZnO or Nb2O5 additions. Details of the Te-O peaks suggest there are two species of Te-O bonds with lengths of {\\sim }0.19 and {\\sim }0.21 nm. The change of their fractions shows excellent agreement with the existence of TeO4 trigonal bipyramids and TeO3 trigonal pyramids. All oxygen atoms from ZnO and Nb2O5 are used for rupture of Te-O-Te bridges, which is accompanied with a change of nearly all participating TeO4 to TeO3 groups. The tendency for a {\\mathrm {TeO}}_{4} \\to {\\mathrm {TeO}}_{3} change decreases for glasses of higher second component content which is accompanied by the occurrence of TeO4 groups with non-bridging oxygens. The Nb tellurite glasses show transition to network-forming behaviour with the formation of Nb-O-Nb bridges. The fractions of TeO3 units of ternary Zn/Nb tellurite glasses agree with an additivity behaviour of the modifying effects of ZnO and Nb2O5 additions. Some of these results have already been presented in thesis work: Yousef E 2003 A study of some physical properties of tellurite glass (Al-Azhar University, Assiut Egypt).

  2. Fabrication and characterization of poly (bisphenol A borate) with high thermal stability

    NASA Astrophysics Data System (ADS)

    Wang, Shujuan; Wang, Xiao; Jia, Beibei; Jing, Xinli

    2017-01-01

    In this work, poly (bisphenol A borate) (PBAB), which has excellent thermal resistance and a high char yield, was synthesized via a convenient A2 + B3 strategy by using bisphenol A (BPA) and boric acid (BA). The chemical reaction between BPA and BA and the chemical structure of PBAB were investigated. The results demonstrate that PBAB consists of aromatic, Ph-O-B and B-O-B structures, as well as a small number of boron hydroxyl groups and phenolic hydroxyl groups. The thermal properties of PBAB were studied by DMA and TGA. The results indicate that the glass transition temperature and char yield are gradually enhanced by increasing the boron content, where the char yield of PBAB at 800 °C in nitrogen (N2) reaches up to 71.3%. It is of particular importance that PBAB show excellent thermal resistance in N2 and air atmospheres. By analysing the pyrolysis of PBAB, the high char yield of PBAB can be attributed to the formation of boron oxide and boron carbide at high temperatures, which reduced the release of volatile carbon dioxide and improved the thermal stability of the carbonization products. This study provides a new perspective on the design of novel boron-containing polymers and possesses significant potential for the improvement of the comprehensive performance of thermosetting resins to broaden their applicability in the field of advanced composites.

  3. Theoretical investigation, biological evaluation and VEGFR2 kinase studies of metal(II) complexes derived from hydrotris(methimazolyl)borate.

    PubMed

    Jayakumar, S; Mahendiran, D; Srinivasan, T; Mohanraj, G; Kalilur Rahiman, A

    2016-02-01

    The reaction of soft tripodal scorpionate ligand, sodium hydrotris(methimazolyl)borate with M(ClO4)2·6H2O [MMn(II), Ni(II), Cu(II) or Zn(II)] in methanol leads to the cleavage of B-N bond followed by the formation of complexes of the type [M(MeimzH)4](ClO4)2·H2O (1-4), where MeimzH=methimazole. All the complexes were fully characterized by spectro-analytical techniques. The molecular structure of the zinc(II) complex (4) was determined by X-ray crystallography, which supports the observed deboronation reaction in the scorpionate ligand with tetrahedral geometry around zinc(II) ion. The electronic spectra of complexes suggested tetrahedral geometry for manganese(II) and nickel(II) complexes, and square-planar geometry for copper(II) complex. Frontier molecular orbital analysis (HOMO-LUMO) was carried out by B3LYP/6-31G(d) to understand the charge transfer occurring in the molecules. All the complexes exhibit significant antimicrobial activity against Gram (-ve) and Gram (+ve) bacterial as well as fungal strains, which are quite comparable to standard drugs streptomycin and clotrimazole. The copper(II) complex (3) showed excellent free radical scavenging activity against DPPH in all concentration with IC50 value of 30μg/mL, when compared to the other complexes. In the molecular docking studies, all the complexes showed hydrophobic, π-π and hydrogen bonding interactions with BSA. The cytotoxic activity of the complexes against human hepatocellular liver carcinoma (HepG2) cells was assessed by MTT assay, which showed exponential responses toward increasing concentration of complexes. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Investigation of passive films formed on the surface of alloy 690 in borate buffer solution

    NASA Astrophysics Data System (ADS)

    Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Wenli, Guo

    2015-10-01

    The passive film formed on the surface of the alloy 690 in borate buffer solution was studied by potentiodynamic curves and electrochemical impedance spectroscopy. With the increasing of the passivation potential, the corrosion resistance of the alloy 690 reduced. Moreover, the corrosion resistance of the passive film was the lowest in the vicinity of 0.6 VSCE. These results were supported by XPS and Mott-Schottky analyses. The corrosion resistance of the alloy 690 increased with the increasing of passivated potential in borate buffer solution with chloride ion. The chloride ion decreased corrosion resistance of the alloy 690 according to point defect model.

  5. Effect of F ions on physical and optical properties of fluorine substituted zinc arsenic tellurite glasses

    NASA Astrophysics Data System (ADS)

    Kareem Ahmmad, Shaik; kondaul, Edu; Rahman, Syed

    2015-02-01

    The effect of substitution of fluoride ions for oxide ions on the physical and optical properties of glass system (20-x) ZnO-xZnF2-40As2O3-40TeO2 where x = 0, 4, 8,12,16,20 mole % were investigated. The samples prepared by melt quenching method under controlled condition. The amorphous nature of these glasses was checked by X-ray diffraction technique. The density was measured according to Archimedes principle. The room temperature absorption spectra of all glass samples were determined using UV-Vis-NIR spectrometer. The thermal behaviour, glass transition temperature and stability of glass samples were studied by a differential scanning calorimetric (DSC). The density reduction of present glasses with ZnF2 concentrations may be due to the low density of ZnF2 compared with that of ZnO. Breaking the oxide network, the cross linking degree of the glass former could be reduced which results in decrease of both Tg and Tx. In the present glass system when F ions replaced by oxygen ions UV-Vis absorption cut-off wavelength decreases. This resulted form the conversion of structural unit in the glass from TeO4 to Te(O,F)4 and then to Te(O, F)3.

  6. Preparation and Elastic Moduli of Germanate Glass Containing Lead and Bismuth

    PubMed Central

    Sidek, Hj A. A.; Bahari, Hamid R.; Halimah, Mohamed K.; Yunus, Wan M. M.

    2012-01-01

    This paper reports the rapid melt quenching technique preparation for the new family of bismuth-lead germanate glass (BPG) systems in the form of (GeO2)60–(PbO)40−x–(½Bi2O3)x where x = 0 to 40 mol%. Their densities with respect of Bi2O3 concentration were determined using Archimedes’ method with acetone as a floatation medium. The current experimental data are compared with those of bismuth lead borate (B2O3)20–(PbO)80−x–(Bi2O3)x. The elastic properties of BPG were studied using the ultrasonic pulse-echo technique where both longitudinal and transverse sound wave velocities have been measured in each glass samples at a frequency of 15 MHz and at room temperature. Experimental data shows that all the physical parameters of BPG including density and molar volume, both longitudinal and transverse velocities increase linearly with increasing of Bi2O3 content in the germanate glass network. Their elastic moduli such as longitudinal, shear and Young’s also increase linearly with addition of Bi2O3 but the bulk modulus did not. The Poisson’s ratio and fractal dimensionality are also found to vary linearly with the Bi2O3 concentration. PMID:22606000

  7. Cation coordination in oxychloride glasses

    NASA Astrophysics Data System (ADS)

    Johnson, J. A.; Holland, D.; Bland, J.; Johnson, C. E.; Thomas, M. F.

    2003-02-01

    Glasses containing mixtures of cations and anions of nominal compositions [Sb2O3]x - [ZnCl2]1-x where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Mössbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb)2(OZn)] and [Zn(ClZn)2(OSb)2].

  8. Photocatalysis of zinc oxide nanotip array/titanium oxide film heterojunction prepared by aqueous solution deposition

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Kwei; Lee, Bo-Wei; Kao, Chen-Yu

    2017-05-01

    A TiO2 film was prepared on indium tin oxide (ITO)/glass by aqueous solution deposition (ASD) with precursors of ammonium hexafluoro-titanate and boric acid at 40 °C. The photocatalysis of annealed TiO2 film increases with increasing growth time and decreases with increasing growth times longer than 60 min. A ZnO nanotip array was prepared on ZnO seed layer/TiO2 film/glass by aqueous solution deposition with precursors of zinc nitrate and ammonium hydroxide at 70 °C. The photocatalysis of ASD-ZnO/ASD-TiO2 film/ITO glass can be better than that of P25.

  9. Structural and luminescence behavior of Er(3+) ions doped Barium tellurofluoroborate glasses.

    PubMed

    Annapoorani, K; Maheshvaran, K; Arunkumar, S; Suriya Murthy, N; Marimuthu, K

    2015-01-25

    Er(3+) doped Barium tellurofluoroborate glasses (BTFBxE) with the chemical composition (30-x)TeO2+30B2O3+20BaO+20BaF+xEr2O3 (where x=0.01, 0.05, 0.1, 0.5, 1.0 and 2.0 in wt%) were prepared following the melt quenching technique. The different vibrational modes of borates and tellurites in the prepared glasses were explored through FTIR and Raman spectra. The optical absorption spectra have been used to determine the ionic/covalent nature of the metal-ligand bond in the prepared glasses with the help of Nephelauxetic ratio (β) and bonding parameter (δ) studies. The optical band gap of direct and indirect allowed transitions were determined from Tauc's plot and the variations of band gap energy with structural arrangements were discussed. The Urbach energy values were determined and the relatively lower values of the Urbach's energy reveal the minimal degree of disorderness in the prepared glasses. The oscillator strengths (fexp and fcal) and Judd-Ofelt (JO) intensity parameters (Ω2, Ω4 and Ω6) were calculated with the application of JO theory and the trends of the JO intensity parameters are found to be Ω2>Ω6>Ω4 for all the prepared glasses with a minimum variation in Ω2 intensity parameter values. A bright green emission was observed from the (2)H11/2+(4)S3/2→ (4)I15/2 transition and the radiative properties such as transition probability (A), stimulated emission cross-section (σP(E)), branching ratio (βr) and radiative lifetime (τ) were calculated using the JO parameters. The suitability of the prepared glasses for the fabrication of photonic devices were also discussed and reported in the present work. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Ab Initio Molecular Dynamics Simulations and GIPAW NMR Calculations of a Lithium Borate Glass Melt.

    PubMed

    Ohkubo, Takahiro; Tsuchida, Eiji; Takahashi, Takafumi; Iwadate, Yasuhiko

    2016-04-14

    The atomic structure of a molten 0.3Li2O-0.7B2O3 glass at 1250 K was investigated using ab initio molecular dynamics (AIMD) simulations. The gauge including projector augmented wave (GIPAW) method was then employed for computing the chemical shift and quadrupolar coupling constant of (11)B, (17)O, and (7)Li from 764 AIMD derived structures. The chemical shift and quadrupolar coupling constant distributions were directly estimated from the dynamical structure of the molten glass. (11)B NMR parameters of well-known structural units such as the three-coordinated ring, nonring, and four-coordinated tetrahedron were found to be in good agreement with the experimental results. In this study, more detailed classification of B units was presented based on the number of O species bonded to the B atoms. This highlights the limitations of (11)B NMR sensitivity for resolving (11)B local environment using the experimentally obtained spectra only. The (17)O NMR parameter distributions can theoretically resolve the bridging and nonbridging O atoms with different structural units such as nonring, single boroxol ring, and double boroxol ring. Slight but clear differences in the number of bridging O atoms surrounding Li that have not been reported experimentally were observed in the theoretically obtained (7)Li NMR parameters.

  11. Zinc electrode and rechargeable zinc-air battery

    DOEpatents

    Ross, Jr., Philip N.

    1989-01-01

    An improved zinc electrode is disclosed for a rechargeable zinc-air battery comprising an outer frame and a porous foam electrode support within the frame which is treated prior to the deposition of zinc thereon to inhibit the formation of zinc dendrites on the external surface thereof. The outer frame is provided with passageways for circulating an alkaline electrolyte through the treated zinc-coated porous foam. A novel rechargeable zinc-air battery system is also disclosed which utilizes the improved zinc electrode and further includes an alkaline electrolyte within said battery circulating through the passageways in the zinc electrode and an external electrolyte circulation means which has an electrolyte reservoir external to the battery case including filter means to filter solids out of the electrolyte as it circulates to the external reservoir and pump means for recirculating electrolyte from the external reservoir to the zinc electrode.

  12. Spectroscopic properties of Sm3 + ions doped Alkaliborate glasses for photonics applications

    NASA Astrophysics Data System (ADS)

    Nagaraj, R.; Suthanthirakumar, P.; Vijayakumar, R.; Marimuthu, K.

    2017-10-01

    A new series of Sm3 + doped alkaliborate glasses have been prepared by melt quenching technique and their structural and spectroscopic properties were analysed employing XRD, FTIR, optical absorption, photoluminescence and decay spectral measurements in order to explore their suitability for photonic applications. The amorphous nature have been confirmed through XRD analysis and the FTIR spectra reveal the presence of fundamental stretching and bending vibrations of the borate networks in the prepared glasses. From the absorption peak positions, bonding parameter (δ) values were calculated to examine the nature of the metal-ligand bond. The optical band gap (Eopt) corresponds to the direct and indirect allowed transitions and the Urbach energies (ΔE) were calculated from the absorption spectra to understand the electronic band structure of the studied glasses. The Judd-Ofelt (JO) intensity parameters Ωλ (λ = 2, 4 and 6) were determined to explore the symmetry of the ligand environment around the Sm3 + ions in the studied glasses. The luminescence spectra exhibit four emission bands in the visible region due to the 4G5/2 → 6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions. The radiative parameters such as transition probability (A), stimulated emission cross-section (σPE), branching ratios (βR) and radiative lifetime (τR) have been determined from the luminescence spectra using JO theory to ensure the suitability of the studied glasses for optoelectronic applications. The luminescence spectra were characterized through CIE 1931 chromaticity diagram to examine the dominant emission color of the studied glasses. The lifetime values of the Sm3 + doped studied glasses pertaining to the 4G5/2 excited level have been determined through decay curve measurements and the non-exponential decay curves were fitted to the Inokuti-Hirayama model to analyze the energy transfer mechanism between the nearby Sm3 + ions. The obtained results were discussed and compared with the

  13. Borate cross-linking chitosan/graphene oxide films: Toward the simultaneous enhancement of gases barrier and mechanical properties

    NASA Astrophysics Data System (ADS)

    Yan, Ning; Capezzuto, Filomena; Buonocore, Giovanna G.; Tescione, Fabiana; Lavorgna, Marino; Xia, Hesheng; Ambrosio, Luigi

    2015-12-01

    Borate adducts, originated from hydrolysis of sodium tetraborate decahydrate (borax), have been used to crosslink chitosan (CS) and graphene oxide (GO) nanosheets for the production of innovative composite sustainable materials. CS/GO film consisting of 10wt% borax and 1wt% GO exhibits a significant improvement of both toughness and oxygen barrier properties in comparison to pristine chitosan. In particular the tensile strength increases by about 100% and 150% after thermal annealing of samples at 90°C for 50min whereas the oxygen permeability reduces of about 90% compared to pristine chitosan. The enhancement of both mechanical and barrier properties is ascribed to the formation of a resistant network due to the chemical crosslinking, including borate orthoester bonds and hydroxyl moieties complexes, formed among borate ions, chitosan, and GO nanoplatelets. The crosslinked graphene-based chitosan material with its enhanced mechanical and barrier properties may significantly broad the range of applications of chitosan based-materials which presently are very limited and addressed only to packaging.

  14. Borosilicate glass structure: An investigation of high resolution B K-edge XANES

    NASA Astrophysics Data System (ADS)

    Dong, S.; Henderson, G. S.; Galoisy, L.; Calas, G.

    2009-05-01

    The Alkali-borosilicate glasses in the systems Na2O-B2O3-SiO2 and K2O- B2O3-SiO2 have been prepared by melting/quenching in air and studied using synchrotron radiation B K-edge XANES to estimate the evolution of boron coordination as a function of composition. The ratio of alkali/B2O3 (R) and SiO2/B2O3 (K) in the glasses are respectively between 0.5 to 2.0 and 0.5 to 7.0. The edge features of trigonal B ([3]B) and tetrahedral B ([4]B) in B K-edge XANES spectra have been interpreted carefully from B standards such as (B2O3 and BPO4), as well as, a wide range of borate minerals. We find that the proportion of tetrahedral B in glass is increasing as a function of both R and K, similar to previous studies. Contributions of the [3]B and [4]B features to the B K-edge XANES is complex with 6-7 individual transitions contributing to the overall spectral envelope. Many of these transitions are common to both B coordination states making extraction of quantitative [4]B numbers difficult. However, we can calculate the proportion of tetrahedral B accurately by appropriate curve- fitting.

  15. Physical, structural and spectroscopic investigations of Sm3+ doped ZnO mixed alkali borate glass

    NASA Astrophysics Data System (ADS)

    Sailaja, B.; Joyce Stella, R.; Thirumala Rao, G.; Jaya Raja, B.; Pushpa Manjari, V.; Ravikumar, R. V. S. S. N.

    2015-09-01

    Glass of 20ZnO-15 Li2O-15 Na2O-49.9 B2O3 doped with 0.1 mol% of Sm3+ (ZLNB) was prepared by the melt quenching technique. Physical properties were studied and analysed. The XRD studies confirm the amorphous nature of sample. The FT-IR spectral investigation discloses the BO3, BO4 groups, H and OH bonds. Optical absorption and emission spectra were recorded and characterized. Judd-Ofelt theory was applied to f ↔ f transitions to evaluate Judd-Ofelt intensity parameters (Ωλ). The oscillator strengths and bonding parameters were determined from absorption spectra. The trend observed was Ω4 > Ω6 > Ω2. High value of Ω4 reveals higher rigidity and covalency around the Sm3+ ion. Low value of Ω2 implies ionic nature of ligands and site symmetry around Sm3+ ion. luminescence data and Judd-Ofelt parameters Ωλ (λ = 2, 4, and 6) were used to evaluate various radiative probabilities like spontaneous radiative emission probabilities (AR), radiative lifetime (τR) and branching ratios (βR) stimulated emission cross section (σe) and CIE colour coordinates were measured, CCT temperature evaluated and the values were used to ascertain potential laser transitions at the optimum mixed alkali effect observed for the glass sample prepared. The preparedness of the material as the efficient laser active material is examined.

  16. Electron paramagnetic resonance spectra of CdO-Al2O3-Bi2O3-B2O3 quaternary glasses containing VO2+ ions

    NASA Astrophysics Data System (ADS)

    Lalithaphani, A. V.; Srinivas, B.; Hameed, Abdul; Chary, M. Narasimha; Shareefuddin, Md.

    2018-04-01

    Borate glasses containing different concentrations of heavy metal oxide (CdO) with 2mol% of V2O5 as the paramagnetic probe were prepared by the conventional melt quenching technique. The prepared glasses were characterized by XRD to confirm the amorphous nature. EPR and Optical absorption studies were carried out at room temperature. EPR spectra of these glass samples were recorded at X-band frequency with 100 kHz field modulation at room temperature. From the EPR spectra the spin-Hamiltonian parameters were evaluated. The spin-Hamiltonian parameter values indicated that g|| < g┴ < ge [=2.0023] and A∥︀ > A┴. This suggests that VO2+ ions are present in octahedral sites with tetragonal compression and belong to C4v symmetry with dxy being the ground state. The measure of tetragonal distortion (Δg∥︀/Δg┴)varies non-linearly with glass composition indicating change in tetragonal distortion. The covalency rates were estimated. The number of spins participating in the resonance [N] and susceptibility (χ) values were also evaluated.

  17. Experimental observation of the thermocapillary driven motion of bubbles in a molten glass under low gravity conditions

    NASA Technical Reports Server (NTRS)

    Smith, H. D.; Mattox, D. M.; Wilcox, W. R.; Subramanian, R. S.; Meyyappan, M.

    1982-01-01

    An experiment was carried out on board a Space Processing Applications Rocket with the aim of demonstrating bubble migration in molten glass due to a temperature gradient under low gravity conditions. During the flight, a sample of a sodium borate melt with a specific bubble array, contained in a platinum/fused silica cell, was subjected to a well defined temperature gradient for more than 4 minutes. Photographs taken at one second intervals during the experiment clearly show that the bubbles move toward the hot spot on the platinum heater strip. This result is consistent with the predictions of the theory of thermocapillary driven bubble motion.

  18. Immobilization of zinc phthalocyanines in silicate matrices and investigation of their photobactericidal effect on E. coli.

    PubMed

    Artarsky, Spas; Dimitrova, Stanislava; Bonnett, Raymond; Krysteva, Milka

    2006-03-26

    The aim of the present investigation was to immobilize zinc phthalocyanines in a silicate matrix and to test the photobactericidal properties of the matrices so prepared toward Esherichia coli in model aqueous media. For the purpose, tetra tertiary butyl zinc phthalocyanine (TBZnPc) and zinc phthalocyanine tetrasulfonic acid (ZnPcTS) were used. The abilities of these two photosensitizers to generate singlet oxygen in solution were compared by following the rate of photobleaching of 1,3-diphenylisobenzofuran (DPBF) at 430 nm in dimethylformamide (DMF). The results of this study show clearly that, under the conditions used here, the TBZnPc is the more effective generator of singlet oxygen; with it the DPBF was virtually completely photobleached in 4 min, while with the ZnPcTS under the same conditions, it took 12 min to reach this point. Glass conjugates with the two phthalocyanines were obtained by the sol-gel technique and were characterized by a well-defined color due to the phthalocyanine incorporated in the silicate matrix. Glasses with an intense, but inhomogeneous, green color were obtained when the tetrasulfonic derivative of the zinc phthalocyanine was used, while blue glasses of evenly distributed coloration were formed from the tetra tertiary butyl derivative. The ZnPcTS conjugate demonstrates more effective singlet oxygen evolution than is the case with the TBZnPc conjugate. These results are the opposite of those obtained for the free phthalocyanines in solution. The structural formulae of the compounds show that TBZnPc has a more pronounced hydrophobic character than the sulfonic derivative. In our view, the relative reactivities of the conjugates can be explained by the tetrasulfonic derivative being situated mainly in the surface parts of the glass matrix where the hydrophilic character is prevailing, while the tertiary butyl derivative is mainly present in the internal parts of the matrix as a result of which it is less accessible and therefore less

  19. Growth and characterization of a novel nonlinear optical borate crystal - Yttrium calcium borate (YCB)

    NASA Astrophysics Data System (ADS)

    Arun Kumar, R.; Arivanandhan, M.; Dhanasekaran, R.; Hayakawa, Y.

    2013-06-01

    A new nonlinear optical single crystal yttrium calcium borate Y2CaB10O19 (YCB) was grown for the first time from its melt. The starting materials were prepared by the solid-state reaction method. The melting point of the synthesized material was identified to be 967 °C. YCB crystal exhibits monoclinic crystal structure with the space group C2. The crystalline perfection of the grown YCB crystal was found to be good. From the UV-VIS-NIR studies, the lower cutoff wavelength of the crystal occurs below 200 nm. The functional groups of the grown crystal were assigned using the FTIR data. The second harmonic generation (SHG) of the YCB crystal was observed using a Nd:YAG laser with a fundamental wavelength of 1064 nm. The laser damage threshold value of the YCB crystal was found to be very high - 10.5 GW/cm2.

  20. Influence of CuO content on the structure of lithium fluoroborate glasses: Spectral and gamma irradiation studies.

    PubMed

    Abdelghany, A M; ElBatal, H A; EzzElDin, F M

    2015-10-05

    Glasses of lithium fluoroborate of the composition LiF 15%-B2O3 85% with increasing CuO as added dopant were prepared and characterized by combined optical and FTIR spectroscopy before and after gamma irradiation. The optical spectrum of the undoped glass reveals strong UV absorption with two distinct peaks at about 235 and 310 nm and with no visible bands. This strong UV absorption is related to the presence of unavoidable trace iron impurity (Fe(3+)) within the materials used for the preparation of this glass. After irradiation, the spectrum of the undoped glass shows a decrease of the intensity of the UV bands together with the resolution of an induced visible broad band centered at about 520 nm. The CuO doped glasses reveal the same UV absorption beside a very broad visible band centered at 780 nm and this band shows extension and splitting to several component peaks with higher CuO contents. Upon gamma irradiation, the spectra of all CuO-doped glasses reveal pronounced decrease of their intensities. The response of irradiation on the studied glasses is correlated with suggested photochemical reactions together with some shielding effect of the copper ions. The observed visible band is related to the presence of copper as distorted octahedral Cu(2+) ions. Infrared absorption spectra of the prepared glasses show repetitive characteristic triangular and tetrahedral borate units similar to that published from alkali or alkaline earth oxides B2O3 glasses. A suggested formation of (BO3/2F) tetrahedral units is advanced through action of LiF on B2O3 and these suggested units showing the same position and number as BO4 tetrahedra. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Zinc Absorption by Young Adults from Supplemental Zinc Citrate Is Comparable with That from Zinc Gluconate and Higher than from Zinc Oxide123

    PubMed Central

    Wegmüller, Rita; Tay, Fabian; Zeder, Christophe; Brnić, Marica; Hurrell, Richard F.

    2014-01-01

    The water-soluble zinc salts gluconate, sulfate, and acetate are commonly used as supplements in tablet or syrup form to prevent zinc deficiency and to treat diarrhea in children in combination with oral rehydration. Zinc citrate is an alternative compound with high zinc content, slightly soluble in water, which has better sensory properties in syrups but no absorption data in humans. We used the double-isotope tracer method with 67Zn and 70Zn to measure zinc absorption from zinc citrate given as supplements containing 10 mg of zinc to 15 healthy adults without food and compared absorption with that from zinc gluconate and zinc oxide (insoluble in water) using a randomized, double-masked, 3-way crossover design. Median (IQR) fractional absorption of zinc from zinc citrate was 61.3% (56.6–71.0) and was not different from that from zinc gluconate with 60.9% (50.6–71.7). Absorption from zinc oxide at 49.9% (40.9–57.7) was significantly lower than from both other supplements (P < 0.01). Three participants had little or no absorption from zinc oxide. We conclude that zinc citrate, given as a supplement without food, is as well absorbed by healthy adults as zinc gluconate and may thus be a useful alternative for preventing zinc deficiency and treating diarrhea. The more insoluble zinc oxide is less well absorbed when given as a supplement without food and may be minimally absorbed by some individuals. This trial was registered at clinicaltrials.gov as NCT01576627. PMID:24259556

  2. Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage.

    PubMed

    Hemilä, Harri

    2017-05-01

    To compare the efficacy of zinc acetate lozenges with zinc gluconate lozenges in common cold treatment and to examine the dose-dependency of the effect. Meta-analysis. Placebo-controlled zinc lozenge trials, in which the zinc dose was > 75 mg/day. The pooled effect of zinc lozenges on common cold duration was calculated by using inverse-variance random-effects method. Seven randomised trials with 575 participants with naturally acquired common colds. Duration of the common cold. The mean common cold duration was 33% (95% CI 21% to 45%) shorter for the zinc groups of the seven included trials. Three trials that used lozenges composed of zinc acetate found that colds were shortened by 40% and four trials that used zinc gluconate by 28%. The difference between the two salts was not significant: 12 percentage points (95% CI: -12 to + 36). Five trials used zinc doses of 80-92 mg/day, common cold duration was reduced by 33%, and two trials used zinc doses of 192-207 mg/day and found an effect of 35%. The difference between the high-dose and low-dose zinc trials was not significant: 2 percentage points (95% CI: -29 to + 32). Properly composed zinc gluconate lozenges may be as effective as zinc acetate lozenges. There is no evidence that zinc doses over 100 mg/day might lead to greater efficacy in the treatment of the common cold. Common cold patients may be encouraged to try zinc lozenges for treating their colds. The optimal lozenge composition and dosage scheme need to be investigated further.

  3. Development of cement solidification process for sodium borate waste generated from PWR plants

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hirofumi Okabe; Tatsuaki Sato; Yuichi Shoji

    2013-07-01

    A cement solidification process for treating sodium borate waste produced in pressurized water reactor (PWR) plants was studied. To obtain high volume reduction and high mechanical strength of the waste, simulated concentrated borate liquid waste with a sodium / boron (Na/B) mole ratio of 0.27 was dehydrated and powdered by using a wiped film evaporator. To investigate the effect of the Na/B mole ratio on the solidification process, a sodium tetraborate decahydrate reagent with a Na/B mole ratio of 0.5 was also used. Ordinary portland cement (OPC) and some additives were used for the solidification. Solidified cement prepared from powderedmore » waste with a Na/B mole ratio 0.24 and having a high silica sand content (silica sand/cement>2) showed to improved uniaxial compressive strength. (authors)« less

  4. Dietary phytate, zinc and hidden zinc deficiency.

    PubMed

    Sandstead, Harold H; Freeland-Graves, Jeanne H

    2014-10-01

    Epidemiological data suggest at least one in five humans are at risk of zinc deficiency. This is in large part because the phytate in cereals and legumes has not been removed during food preparation. Phytate, a potent indigestible ligand for zinc prevents it's absorption. Without knowledge of the frequency of consumption of foods rich in phytate, and foods rich in bioavailable zinc, the recognition of zinc deficiency early in the illness may be difficult. Plasma zinc is insensitive to early zinc deficiency. Serum ferritin concentration≤20μg/L is a potential indirect biomarker. Early effects of zinc deficiency are chemical, functional and may be "hidden". The clinical problem is illustrated by 2 studies that involved US Mexican-American children, and US premenopausal women. The children were consuming home diets that included traditional foods high in phytate. The premenopausal women were not eating red meat on a regular basis, and their consumption of phytate was mainly from bran breakfast cereals. In both studies the presence of zinc deficiency was proven by functional responses to controlled zinc treatment. In the children lean-mass, reasoning, and immunity were significantly affected. In the women memory, reasoning, and eye-hand coordination were significantly affected. A screening self-administered food frequency questionnaire for office might help caregiver's identify patients at risk of zinc deficiency. Copyright © 2014 Elsevier GmbH. All rights reserved.

  5. Electron Spin Resonance and optical absorption spectroscopic studies of manganese centers in aluminium lead borate glasses.

    PubMed

    SivaRamaiah, G; LakshmanaRao, J

    2012-12-01

    Electron Spin Resonance (ESR) and optical absorption studies of 5Al(2)O(3)+75H(3)BO(3)+(20-x)PbO+xMnSO(4) (where x=0.5, 1,1.5 and 2 mol% of MnSO(4)) glasses at room temperature have been studied. The ESR spectrum of all the glasses exhibits resonance signals with effective isotropic g values at ≈2.0, 3.3 and 4.3. The ESR resonance signal at isotropic g≈2.0 has been attributed to Mn(2+) centers in an octahedral symmetry. The ESR resonance signals at isotropic g≈3.3 and 4.3 have been attributed to the rhombic symmetry of the Mn(2+) ions. The zero-field splitting parameter (zfs) has been calculated from the intensities of the allowed hyperfine lines. The optical absorption spectrum exhibits an intense band in the visible region and it has been attributed to (5)E(g)→(5)T(2g) transition of Mn(3+)centers in an octahedral environment. The optical band gap and the Urbach energies have been calculated from the ultraviolet absorption edges. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Luminescent hybrid materials based on (8-hydroxyquinoline)-substituted metal-organic complexes and lead-borate glasses

    NASA Astrophysics Data System (ADS)

    Petrova, Olga B.; Anurova, Maria O.; Akkuzina, Alina A.; Saifutyarov, Rasim R.; Ermolaeva, Ekaterina V.; Avetisov, Roman I.; Khomyakov, Andrew V.; Taydakov, Ilya V.; Avetissov, Igor Ch.

    2017-07-01

    Novel luminescent organic-inorganic hybrid materials based on 8-hydroxyquinoline metal complexes (Liq, Kq, Naq, Rbq, Mgq2, Srq2, Znq2, Scq3, Alq3, Gaq3, and Inq3) have been synthesized by a high temperature exchange reaction with 80PbF2-20B2O3 inorganic low-melting glass. The mechanical and optical properties, transmission spectra, emission an excitation photoluminescence, and luminescence kinetic of hybrid materials were studied. All hybrid materials showed a wide luminescence band in the range 400-700 nm.

  7. Acute changes in cellular zinc alters zinc uptake rates prior to zinc transporter gene expression in Jurkat cells.

    PubMed

    Holland, Tai C; Killilea, David W; Shenvi, Swapna V; King, Janet C

    2015-12-01

    A coordinated network of zinc transporters and binding proteins tightly regulate cellular zinc levels. Canonical responses to zinc availability are thought to be mediated by changes in gene expression of key zinc transporters. We investigated the temporal relationships of actual zinc uptake with patterns of gene expression in membrane-bound zinc transporters in the human immortalized T lymphocyte Jurkat cell line. Cellular zinc levels were elevated or reduced with exogenous zinc sulfate or N,N,N',N-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), respectively. Excess zinc resulted in a rapid 44 % decrease in the rate of zinc uptake within 10 min. After 120 min, the expression of metallothionein (positive control) increased, as well as the zinc exporter, ZnT1; however, the expression of zinc importers did not change during this time period. Zinc chelation with TPEN resulted in a rapid twofold increase in the rate of zinc uptake within 10 min. After 120 min, the expression of ZnT1 decreased, while again the expression of zinc importers did not change. Overall, zinc transporter gene expression kinetics did not match actual changes in cellular zinc uptake with exogenous zinc or TPEN treatments. This suggests zinc transporter regulation may be the initial response to changes in zinc within Jurkat cells.

  8. Zinc Enzymes.

    ERIC Educational Resources Information Center

    Bertini, I.; And Others

    1985-01-01

    Discusses the role of zinc in various enzymes concerned with hydration, hydrolysis, and redox reactions. The binding of zinc to protein residues, properties of noncatalytic zinc(II) and catalytic zinc, and the reactions catalyzed by zinc are among the topics considered. (JN)

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

    NASA Astrophysics Data System (ADS)

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

    2018-01-01

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

  10. Barium borate nanorod decorated reduced graphene oxide for optical power limiting applications

    NASA Astrophysics Data System (ADS)

    Muruganandi, G.; Saravanan, M.; Vinitha, G.; Jessie Raj, M. B.; Sabari Girisun, T. C.

    2018-01-01

    By simple hydrothermal method, nanorods of barium boate were successfully loaded on reduced graphene oxide sheets. Powder XRD confirms the incorporation of barium borate (2θ = 29°, (202)) along with the transition of graphene oxide (2θ = 12°, (001)) into reduced graphene oxide (2θ = 25°, (002)). In the FTIR spectra, presence of characteristic absorption peaks of rGO (1572 and 2928 cm-1) and barium borate (510, 760 and 856 cm-1) further evidences the formation of BBO:rGO nanocomposite. FESEM images potray the existence of graphene sheets as thin layers and growth of barium borate as nanorods on the sheets of reduced graphene oxide. Ground state absorption studies reveal the hypsochromic shift in the absorption maxima of the graphene layers due to reduction of graphene oxide and hypochromic shift in the absorbance intensity due to the inclusion of highly transparent barium bortae. The photoluminescence of BBO:rGO shows maximum emission in the UV region arising from the direct transitions involving the valence band and conduction band in the band gap region. Z-scan technique using CW diode pumped Nd:YAG laser (532 nm, 50 mW) exposes that both nanocomposite and individual counterpart possess saturable absorption and self-defocusing behavior. Third-order nonlinear optical coefficients of BBO:rGO nanocomposite is found to be higher than bare graphene oxide. In particular the nonlinear refractive index of nanocomposite is almost four times higher than GO which resulted in superior optical power limiting action. Strong nonlinear refraction (self-defocusing) and lower onset limiting thershold makes the BBO:rGO nanocomposite preferable candidate for laser safety devices.

  11. Zinc

    MedlinePlus

    ... Using toothpastes containing zinc, with or without an antibacterial agent, appears to prevent plaque and gingivitis. Some ... is some evidence that zinc has some antiviral activity against the herpes virus. Low zinc levels can ...

  12. Crystallization and photoluminescence properties of α-RE2(WO4)3 (RE: Gd, Eu) in rare-earth tungsten borate glasses

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Honma, Tsuyoshi; Komatsu, Takayuki

    2013-03-01

    Glasses with the compositions of 22.5RE2O3-47.5WO3-30B2O3 (mol%) (RE: Gd, Eu) were prepared by a conventional melt quenching method, and α-Gd2(WO4)3 and α-Eu2(WO4)3 crystals were synthesized through their crystallization. The two types of WO4 tetrahedra present in α-RE2(WO4)3 provide the Raman bands at 931-934 cm-1 for WIIO4 tetrahrdra with much distortions and at 946-950 cm-1 for WIO4 tetrahedra with a near regular symmetry. The crystallized samples containing α-Eu2(WO4)3 exhibit strong red emissions under the excitation at 396 and 467 nm, although the base glass has no photoluminescence emission. α-Gd2(WO4)3 and α-Eu2(WO4)3 crystals were patterned on the glass surface by irradiations of a continuous wave Yb:YVO4 fiber laser (wavelength: 1080 nm).

  13. Synthesis, structure characterization, photoluminescence properties and TD-DFT calculations for two new borates.

    PubMed

    Hadjadj, Nasreddine; Dems, Mohamed AbdEsselem; Merazig, Hocine; Bendjeddou, Lamia

    2018-04-01

    Due to their rich structural chemistry and wide variety of applications, borate materials have provided a rich area of research. In a continuation of this research, diethylammonium bis(2-oxidobenzoato-κ 2 O 1 ,O 2 )borate, C 4 H 12 N + ·BO 4 (C 7 H 4 O) 2 - , (1), and propylammonium bis(2-oxidobenzoato-κ 2 O 1 ,O 2 )borate, C 3 H 10 N + ·BO 4 (C 7 H 4 O) 2 - , (2), have been synthesized by the reaction of boric acid with salicylic acid under ambient conditions. In both structures, the B atom exhibits a slightly distorted tetrahedral environment formed by the bidentate coordination of two salicylate anions via the O atoms of the central carboxylate and oxide groups. In the crystals of salts (1) and (2), mixed cation-anion layers lying parallel to the (101) plane are formed through N-H...O, C-H...O and C-H...π/N-H...O hydrogen-bonding interactions, resulting, in each case, in a two-dimensional supramolecular architecture in the solid state. The photoluminescence properties of the salts were studied using the as-synthesized samples and reveal that salts (1) and (2) both display a strong blue-light emission, with maxima at 489 and 491 nm, respectively. In DFT/TD-DFT (time-dependent density functional theory) studies, the blue emission appears to be derived from an intramolecular charge transfer (ICT) excited state. In addition, IR and UV-Vis spectroscopies were used to investigate the title salts.

  14. Growth study of self-assembled GaN nanocolumns on silica glass by plasma assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Liudi Mulyo, Andreas; Konno, Yuta; Nilsen, Julie S.; van Helvoort, Antonius T. J.; Fimland, Bjørn-Ove; Weman, Helge; Kishino, Katsumi

    2017-12-01

    We demonstrate GaN nanocolumn growth on fused silica glass by plasma-assisted molecular beam epitaxy. The effect of the substrate temperature, Ga flux and N2 flow rate on the structural and optical properties are studied. At optimum growth conditions, GaN nanocolumns are vertically aligned and well separated with an average diameter, height and density of 72 nm, 1.2 μm and 1.6 × 109 cm-2, respectively. The nanocolumns exhibit wurtzite crystal structure with no threading dislocations, stacking faults or twinning and grow in the [0 0 0 1] direction. At the interface adjacent to the glass, there is a few atom layers thick intermediate phase with ABC stacking order (zinc blende). Photoluminescence measurements evidence intense and narrow excitonic emissions, along with the absence of any defect-related zinc blende and yellow luminescence emission.

  15. Structural characterization of ZnCl2 modified tellurite based glasses

    NASA Astrophysics Data System (ADS)

    Dhankhar, Sunil; Kundu, R. S.; Punia, R.; Sunita, Parmar, R.; Sanjay, Kishore, N.

    2016-05-01

    Glass composition 70 TeO2-(30-x) BaO - x ZnCl2; x = 5, 10, 15, 20 and 25 have been prepared by rapid melt quenching technique under controlled atmospheric conditions. Amorphous nature of the samples was confirmed by x-ray diffractogram. The glass transition temperature (Tg) has been determined using differential scanning calorimetry (DSC) and its value is observed to decrease with increase in ZnCl2 content. The peaks in the Raman and FTIR spectra have been estimated by deconvolutation of the spectra and each of deconvoluted spectra exhibits several peaks. IR and Raman spectra of the present glass system indicate that TeO2 exists as TeO3 trigonal pyramidal (tp), TeO4 trigonal bipyramidal (tbp) and TeO6 polyhedra structural units. With increase in zinc halide content, transformation of some of TeO4 structural units into TeO3 structural units is observed Increase in TeO3 structural units shows that non-bridging oxygen contribution increases which confirms the decrease in glass transition temperature.

  16. Transparent and High Refractive Index Thermoplastic Polymer Glasses Using Evaporative Ligand Exchange of Hybrid Particle Fillers.

    PubMed

    Wang, Zongyu; Lu, Zhao; Mahoney, Clare; Yan, Jiajun; Ferebee, Rachel; Luo, Danli; Matyjaszewski, Krzysztof; Bockstaller, Michael R

    2017-03-01

    Development of high refractive index glasses on the basis of commodity polymer thermoplastics presents an important requisite to further advancement of technologies ranging from energy efficient lighting to cost efficient photonics. This contribution presents a novel particle dispersion strategy that enables uniform dispersion of zinc oxide (ZnO) particles in a poly(methyl methacrylate) (PMMA) matrix to facilitate hybrid glasses with inorganic content exceeding 25% by weight, optical transparency in excess of 0.8/mm, and a refractive index greater than 1.64 in the visible wavelength range. The method is based on the application of evaporative ligand exchange to synthesize poly(styrene-r-acrylonitrile) (PSAN)-tethered zinc oxide (ZnO) particle fillers. Favorable filler-matrix interactions are shown to enable the synthesis of isomorphous blends with high molecular PMMA that exhibit improved thermomechanical stability compared to that of the pristine PMMA matrix. The concurrent realization of high refractive index and optical transparency in polymer glasses by modification of a thermoplastic commodity polymer could present a viable alternative to expensive specialty polymers in applications where high costs or demands for thermomechanical stability and/or UV resistance prohibit the application of specialty polymer solutions.

  17. The development of latent fingerprints by zinc oxide and tin oxide nanoparticles prepared by precipitation technique

    NASA Astrophysics Data System (ADS)

    Luthra, Deepali; Kumar, Sacheen

    2018-05-01

    Fingerprints are the very important evidence at the crime scene which must be developed clearly with shortest duration of time to solve the case. Metal oxide nanoparticles could be the mean to develop the latent fingerprints. Zinc oxide and Tin Oxide Nanoparticles were prepared by using chemical precipitation technique which were dried and characterized by X-ray diffraction, UV-Visible spectroscopy and FTIR. The size of zinc oxide crystallite was found to be 14.75 nm with minimum reflectance at 360 nm whereas tin oxide have the size of 90 nm and reflectance at minimum level 321 nm. By using these powdered samples on glass, plastic and glossy cardboard, latent fingerprints were developed. Zinc oxide was found to be better candidate than tin oxide for the fingerprint development on all the three types of substrates.

  18. D-Tagatose production in the presence of borate by resting Lactococcus lactis cells harboring Bifidobacterium longum L-arabinose isomerase.

    PubMed

    Salonen, Noora; Salonen, Kalle; Leisola, Matti; Nyyssölä, Antti

    2013-04-01

    Bifidobacterium longum NRRL B-41409 L-arabinose isomerase (L-AI) was overexpressed in Lactococcus lactis using a phosphate depletion inducible expression system. The resting L. lactis cells harboring the B. longum L-AI were used for production of D-tagatose from D-galactose in the presence of borate buffer. Multivariable analysis suggested that high pH, temperature and borate concentration favoured the conversion of D-galactose to D-tagatose. Almost quantitative conversion (92 %) was achieved at 20 g L⁻¹ substrate and at 37.5 °C after 5 days. The D-tagatose production rate of 185 g L⁻¹ day ⁻¹ was obtained at 300 g L⁻¹ galactose, at 1.15 M borate, and at 41 °C during 10 days when the production medium was changed every 24 h. There was no significant loss in productivity during ten sequential 24 h batches. The initial D-tagatose production rate was 290 g L⁻¹ day⁻¹ under these conditions.

  19. Four-time 7Li stimulated-echo spectroscopy for the study of dynamic heterogeneities: Application to lithium borate glass.

    PubMed

    Storek, M; Tilly, J F; Jeffrey, K R; Böhmer, R

    2017-09-01

    To study the nature of the nonexponential ionic hopping in solids a pulse sequence was developed that yields four-time stimulated-echo functions of previously inaccessible spin-3/2-nuclei such as 7 Li. It exploits combined Zeeman and octupolar order as longitudinal carrier state. Higher-order correlation functions were successfully generated for natural-abundance and isotopically-enriched lithium diborate glasses. Four-time 7 Li measurements are presented and compared with two-time correlation functions. The results are discussed with reference to approaches devised to quantify the degree of nonexponentiality in glass forming systems and evidence for the occurrence of dynamic heterogeneities and dynamic exchange were found. Additional experiments using the 6 Li species illustrate the challenge posed by subensemble selection when the dipolar interactions are not very much smaller than the quadrupolar ones. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Temperature Effects on Aluminoborosilicate Glass and Melt Structure

    NASA Astrophysics Data System (ADS)

    Wu, J.; Stebbins, J. F.

    2008-12-01

    Quantitative determination of the atomic-scale structure of multi-component oxide melts, and the effects of temperature on them, is a complex problem. Ca- and Na- aluminoborosilicates are especially interesting, not only because of their major role in widespread technical applications (flat-panel computer displays, fiber composites, etc.), but because the coordination environments of two of their main network cations (Al3+ and B3+) change markedly with composition and temperature is ways that may in part be analogous to processes in silicate melts at high pressures in the Earth. Here we examine a series of such glasses with different cooling rates, chosen to evaluate the role modifier cation field strength (Ca2+ vs. Na+) and of non-bridging oxygen (NBO) content. To explore the effects of fictive temperature, fast quenched and annealed samples were compared. We have used B-11 and Al-27 MAS NMR to measure the different B and Al coordinations and calculated the contents of non-bridging oxygens (NBO). Lower cooling rates increase the fraction of [4]B species in all compositions. The conversion of [3]B to [4]B is also expected to convert NBO to bridging oxygens, which should affect thermodynamic properties such as configurational entropy and configurational heat capacity. For four compositions with widely varying compositions and initial NBO contents, analysis of the speciation changes with the same, simple reaction [3]B = [4]B + NBO yields similar enthalpy values of 25±7 kJ/mol. B-11 triple quantum MAS NMR allows as well the proportions of [3]B boroxol ring and non-ring sites to be determined, and reveals more [3]B boroxol ring structures present in annealed (lower temperature) glasses. In situ, high-temperature MAS NMR spectra have been collected on one of the Na-aluminoborosilicate and on a sodium borate glass at 14.1 T. The exchange of boron between the 3- and 4-coordinated sites is clearly observed well above the glass transition temperatures, confirming the