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Sample records for single oxides siosub

  1. Characterization of the acid strength of SiO[sub 2]-ZrO[sub 2] mixed oxides

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    Bosman, H.J.M.; Kruissink, E.C.; Spoel, J. van der; Brink, F. van den (DSM Research B.V., Gelenee (Netherlands))

    1994-08-01

    The preparation of SiO[sub 2]-ZrO[sub 2] mixed oxides and the single oxides SiO[sub 2] and ZrO[sub 2] from H[sub 2]SiF[sub 6] and/or H[sub 2]ZrF[sub 6] is described. The catalysts are characterized using Hammett colour indicators, temperature programmed desorption of ammonia, XRD, XPS, and infrared spectroscopy. New IR bands and absence of XRD crystallinity show mixing of SiO[sub 2] and ZrO[sub 2] on an atomic scale in the amorphous coprecipitate. However, as could be concluded from the difference between surface concentrations of Zr and Si measured with XPS and the mean bulk concentrations, the ZrO[sub 2] precipitates somewhat more quickly than SiO[sub 2]. The acid strength of the SiO[sub 2]-ZrO[sub 2] mixed oxides corresponds to an H[sub 0] value between -11.4 and 13.8 (super-acidity). There is a fair correlation between the surface concentration of strong acid sites, determined from NH[sub 3] TPD, and the performance in the acid catalyzed dehydration of cyclohexanol to cyclohexene. In addition to the concentration of acid sites, their acid strength is an important factor determining the performance of the SiO[sub 2]-ZrO[sub 2] catalysts in the dehydration of cyclohexanol. The acid strength needed for the dehydration of cyclohexanol corresponds to H[sub 0] [<=] +2.8. Chemically mixed SiO[sub 2]-ZrO[sub 2] oxides contain strong acid sites as opposed to the single oxides SiO[sub 2] and ZrO[sub 2], which contain only weak acid sites. XPS shows an oxygen depletion on the surface of the mixed oxides, which indicates that the strong acid sites are of the Lewis type. 27 refs., 11 figs., 4 tabs.

  2. Densification of ∼5 nm-thick SiO{sub 2} layers by nitric acid oxidation

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    Choi, Jaeyoung [Department of Energy Engineering, Dankook University, Cheonan 311-16 (Korea, Republic of); Joo, Soyeong [Institute for Advanced Engineering (IAE), Advanced Materials & Processing Center, Youngin 449-863 (Korea, Republic of); Park, Tae Joo [Department of Materials Science and Chemical Engineering, Hanyang University, Ansan 15588 (Korea, Republic of); Kim, Woo-Byoung, E-mail: woo7838@dankook.ac.kr [Department of Energy Engineering, Dankook University, Cheonan 311-16 (Korea, Republic of)

    2017-08-15

    Highlights: • Leakage current density of the commercial PECVD grown ∼5 nm SiO{sub 2} layer has been decreased about three orders of magnitude by densification. • The densification of SiO{sub 2} layer is achieved by high oxidation ability of O·. • Densities of suboxide, fixed charge (N{sub f}) and defect state (N{sub d}) in SiO{sub 2}/Si interface are decreased by NAOS and PMA. • Tunneling barrier height (Φ{sub t}) is increased because of the increase of atomic density in SiO{sub 2} layer. - Abstract: Low-temperature nitric acid (HNO{sub 3}) oxidation of Si (NAOS) has been used to improve the interface and electrical properties of ∼5 nm-thick SiO{sub 2}/Si layers produced by plasma-enhanced chemical vapor deposition (PECVD). Investigations of the physical properties and electrical characteristics of these thin films revealed that although their thickness is not changed by NAOS, the leakage current density at a gate bias voltage of −1 V decreases by about two orders of magnitude from 1.868 × 10{sup −5} A/cm{sup 2}. This leakage current density was further reduced by post-metallization annealing (PMA) at 250 °C for 10 min in a 5 vol.% hydrogen atmosphere, eventually reaching a level (5.2 × 10{sup −8} A/cm{sup 2}) approximately three orders of magnitude less than the as-grown SiO{sub 2} layer. This improvement is attributed to a decrease in the concentration of suboxide species (Si{sup 1+}, Si{sup 2+} and Si{sup 3+}) in the SiO{sub 2}/Si interface, as well as a decrease in the equilibrium density of defect sites (N{sub d}) and fixed charge density (N{sub f}). The barrier height (Φ{sub t}) generated by a Poole-Frenkel mechanism also increased from 0.205 to 0.371 eV after NAOS and PMA. The decrease in leakage current density is therefore attributed to a densification of the SiO{sub 2} layer in combination with the removal of OH species and increase in interfacial properties at the SiO{sub 2}/Si interface.

  3. First-principles study on the effect of SiO{sub 2} layers during oxidation of 4H-SiC

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    Ono, Tomoya, E-mail: ono@ccs.tsukuba.ac.jp [Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); JST-PRESTO, Kawaguchi, Saitama 332-0012 (Japan); Saito, Shoichiro [Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan)

    2015-02-23

    The effect of SiO{sub 2} layers during the thermal oxidation of a 4H-SiC(0001) substrate is examined by performing the first-principles total-energy calculations. Although it is expected that a CO molecule is the most preferable product during the oxidation, CO{sub 2} molecules are mainly emitted from the SiC surface at the initial stage of the oxidation. As the oxidation proceeds, CO{sub 2} emission becomes less favorable and CO molecules are emitted from the interface. We conclude that the interface stress due to the lattice constant mismatch between 4H-SiC(0001) and SiO{sub 2} is responsible for the removal of C during the oxidation, resulting in the characteristic electronic property of the interface fabricated by the thermal oxidation.

  4. Preparation and characterization of amorphous SiO{sub 2} coatings deposited by mirco-arc oxidation on sintered NdFeB permanent magnets

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    Xu, J.L., E-mail: jlxu@nchu.edu.cn [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Xiao, Q.F.; Mei, D.D. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Zhong, Z.C., E-mail: zzhong2014@sina.com [The Institute for Rare Earth Magnetic Materials and Devices, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Tong, Y.X. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Zheng, Y.F., E-mail: yfzheng@pku.edu.cn [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Li, L. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China)

    2017-03-15

    Amorphous SiO{sub 2} coatings were prepared on sintered NdFeB magnets by micro-arc oxidation (MAO) in silicate solution. The surface and cross-sectional morphologies, element and phase composition, corrosion resistance and magnetic properties of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization test and physical properties measurements system (PPMS). The results showed that the surface morphologies of the coatings exhibited the “coral reef” like structure, different from the typical MAO porous structure. With increasing the voltages, the thickness of the coatings increased from 12.72 to 19.90 µm, the content of Si element increased, while the contents of Fe, Nd and P elements decreased. The coatings were mainly composed of amorphous SiO{sub 2} and a few amorphous Fe{sub 2}O{sub 3} and Nd{sub 2}O{sub 3}. The amorphous SiO{sub 2} coatings presented excellent thermal shock resistance, while the thermal shock resistance decreased with increasing the voltages. The corrosion resistance of the coatings increased with increasing the voltages, and it could be enhanced by one order of magnitude compared to the uncoated NdFeB magnets. The MAO coatings slightly decreased the magnetic properties of the NdFeB samples in different degrees. - Highlights: • Amorphous SiO{sub 2} coatings were prepared on sintered NdFeB magnets by micro-arc oxidation. • The coatings presented excellent thermal shock resistance. • The corrosion resistance could be enhanced by one order of magnitude. • The MAO coatings slightly decreased the magnetic properties of the NdFeB samples.

  5. Single sheet iron oxides

    DEFF Research Database (Denmark)

    Yin, Zhou

    activity. LDH single sheets have been reported to be effective sorbents, catalysts in electrochemical and photochemical reactions, and building thin films together with other nanomaterials for designing new functionalities. Here we focus on the delamination of FeII-FeIII LDHs into single sheet iron oxide...... was rapid compared to other iron oxides, reaching equilibrium within 60 minutes. Arsenic sorption and acid-base titration data could be successfully described with a 1pk Basic Stern Model (BSM). The point of zero charge was around 8. The intrinsic surface complexation equilibrium constants (log K...... became abundant at low pH. (3) Electrochemical reduction of chlorinated compounds using an SSI modified electrode. Here, the electrochemical reactivity of SSIs coated on indium tin oxide coated glass electrodes was investigated. Iron on the SSI modified electrode showed a typical Cyclic Voltammetry...

  6. FTIR, AFM and PL properties of thin SiO{sub x} films deposited by HFCVD

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    Luna-Lopez, J.A., E-mail: jalbluna@siu.buap.mx [CIDS-ICUAP, BUAP, Ciudad Universitaria, Ed. 103 D, Col. San Manuel, C.P. 72570, Puebla (Mexico); Garcia-Salgado, G.; Diaz-Becerril, T.; Lopez, J. Carrillo; Vazquez-Valerdi, D.E.; Juarez-Santiesteban, H.; Rosendo-Andres, E.; Coyopol, A. [CIDS-ICUAP, BUAP, Ciudad Universitaria, Ed. 103 D, Col. San Manuel, C.P. 72570, Puebla (Mexico)

    2010-10-25

    In order to have optoelectronic functions integrated in a single chip, it is very important to obtain a silicon compatible material with an optimal photoluminescence response. The non-stoichiometric silicon oxide (SiO{sub x}) has shown photoluminescence response and is also compatible with silicon technology. In this work, the composition and optical properties of the SiO{sub x} films are studied using null ellipsometry, Fourier transformed infrared spectroscopy (FTIR), atomic force microscopy (AFM), and photoluminescence (PL). The SiO{sub x} films were growth to different temperatures. The IR absorption spectrum shows the presence of three typical Si-O-Si vibrations modes in SiO{sub 2}. However, changes in their intensity and position were observed. Also, when growth temperature decreased, the Si-H vibrations modes were observed. These changes are directly related with compositional variation in the SiO{sub x} films due to the growth temperature. A PL spectrum shows a considerable emission in the range 400-850 nm that varies with the growth temperatures.

  7. Towards ion beam synthesis of single CdSe nanocrystal quantum dots in a SiO{sub 2} matrix

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    Mangold, Hans Moritz; Kinzel, Joerg B.; Krenner, Hubert J. [Emmy Noether Group at Lehrstuhl Experimentalphysik 1, Universitaet Augsburg (Germany); Karl, Helmut [Lehrstuhl Experimentalphysik IV, Universitaet Augsburg (Germany); Wixforth, Achim [Lehrstuhl Experimentalphysik I, Universitaet Augsburg (Germany)

    2013-07-01

    II-VI compound semiconductor quantum dots (QDs) are a promising class of materials for applications in optical devices in the visible spectral domain. Here we show that in addition to traditional fabrication techniques such as molecular beam epitaxy or chemical synthesis, high fluence ion-beam implantation followed by a rapid thermal annealing step, can be readily applied to synthesize CdSe nanocrystals with superior optical properties within the thermal oxide on a Si wafer. In order to confine the implantation volume we employ chromium masks with arrays of nanoscale aperture openings with diameters smaller than 250 nm. We analyzed the such implanted and annealed samples by scanning electron microscopy and micro-photoluminescence spectroscopy. We observe a pronounced broadening and blue shift of the nanocrystal emission when decreasing the aperture diameter to <1000 nm. We attribute this behavior to a reduction of the mean nanocrystal size but increase of its size distribution. For the smallest aperture sizes used we observe a pronounced shell-filling behavior characteristic for single quantum dot nanoemitters.

  8. Fabrication and electrical properties of metal-oxide semiconductor capacitors based on polycrystalline p-Cu{sub x}O and HfO{sub 2}/SiO{sub 2} high-{kappa} stack gate dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Zou Xiao [Department of Electronic Science and Technology, School of Physical Science and Technology, Wuhan University, Wuhan, 430074 (China); Department of Electromachine Engineering, Jianghan University, Wuhan, 430056 (China); Fang Guojia, E-mail: gjfang@whu.edu.c [Department of Electronic Science and Technology, School of Physical Science and Technology, Wuhan University, Wuhan, 430074 (China); Yuan Longyan; Liu Nishuang; Long Hao; Zhao Xingzhong [Department of Electronic Science and Technology, School of Physical Science and Technology, Wuhan University, Wuhan, 430074 (China)

    2010-05-31

    Polycrystalline p-type Cu{sub x}O films were deposited after the growth of HfO{sub 2} dielectric on Si substrate by pulsed laser deposition, and Cu{sub x}O metal-oxide-semiconductor (MOS) capacitors with HfO{sub 2}/SiO{sub 2} stack gate dielectric were primarily fabricated and investigated. X-ray diffraction and X-ray photoelectron spectroscopy were applied to analyze crystalline structure and Cu{sup +}/Cu{sup 2+} ratios of Cu{sub x}O films respectively. SiO{sub 2} interlayer formed between the high-{kappa} dielectric and substrate was estimated by the transmission electron microscope. Results of electrical characteristic measurement indicate that the permittivity of HfO{sub 2} is about 22, and the gate leakage current density of MOS capacitor with 11.3 nm HfO{sub 2}/SiO{sub 2} stack dielectrics is {approx} 10{sup -4} A/cm{sup 2}. Results also show that the annealing in N{sub 2} can improve the quality of Cu{sub x}O/HfO{sub 2} interface and thus reduce the gate leakage density.

  9. Surface texture of single-crystal silicon oxidized under a thin V{sub 2}O{sub 5} layer

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, S. E., E-mail: nikitin@mail.ioffe.ru; Verbitskiy, V. N.; Nashchekin, A. V.; Trapeznikova, I. N.; Bobyl, A. V.; Terukova, E. E. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2017-01-15

    The process of surface texturing of single-crystal silicon oxidized under a V{sub 2}O{sub 5} layer is studied. Intense silicon oxidation at the Si–V{sub 2}O{sub 5} interface begins at a temperature of 903 K which is 200 K below than upon silicon thermal oxidation in an oxygen atmosphere. A silicon dioxide layer 30–50 nm thick with SiO{sub 2} inclusions in silicon depth up to 400 nm is formed at the V{sub 2}O{sub 5}–Si interface. The diffusion coefficient of atomic oxygen through the silicon-dioxide layer at 903 K is determined (D ≥ 2 × 10{sup –15} cm{sup 2} s{sup –1}). A model of low-temperature silicon oxidation, based on atomic oxygen diffusion from V{sub 2}O{sub 5} through the SiO{sub 2} layer to silicon, and SiO{sub x} precipitate formation in silicon is proposed. After removing the V{sub 2}O{sub 5} and silicon-dioxide layers, texture is formed on the silicon surface, which intensely scatters light in the wavelength range of 300–550 nm and is important in the texturing of the front and rear surfaces of solar cells.

  10. Dispersive hole transport in SiO/sub 2/. Final report, 1978-1987

    Energy Technology Data Exchange (ETDEWEB)

    McLean, F.B.; Boesch, H.E.; McGarrity, J.M.

    1987-10-01

    A detailed study is presented on the temperature, field, and thickness dependencies of the transient, radiation-induced hole transport in thin films of amorphous SiO/sub 2/ employed as the gate oxides of metal-oxide-semiconductor (MOS) structures. The samples used in the investigation are clean, radiation-hardened oxides in which less than 2% of the holes generated are permanently trapped and therefore are ideal for basic transport studies. The measurements show that for the entire range of temperature (78 to 293 K), field (1 to 6 MV/cm), and thickness (22 to 99 nm) investigated, the time dispersion of the transport can be adequately described by the continuous-time-random-walk (CTRW) model with a single value of the disorder parameter: alpha = 0.25 + or - 0.03. This is a crucial result which indicates rather strict universality of the hole transport with respect to temperature, field, and thickness in clean amorphous SiO/sub 2/. Changes in these parameters simply affect the time scale for the transport, but not the shape or overall dispersion of the response curves. The observed universality feature has implications for the microscopic basis of the transport, namely that the hole transport proceeds via hopping between localized trapping sites in the SiO/sub 2/ film, with the dispersion originating primarily from a broad distribution of intersite transfer integrals.

  11. New multicell model for describing the atomic structure of La{sub 3}Ga{sub 5}SiO{sub 14} piezoelectric crystal: Unit cells of different compositions in the same single crystal

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    Dudka, A. P., E-mail: dudka@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics” (Russian Federation)

    2017-03-15

    Accurate X-ray diffraction study of langasite (La{sub 3}Ga{sub 5}SiO{sub 14}) single crystal has been performed using the data obtained on a diffractometer equipped with a CCD area detector at 295 and 90.5 K. Within the known La{sub 3}Ga{sub 5}SiO{sub 14} model, Ga and Si cations jointly occupy the 2d site. A new model of a “multicell” consisting of two different unit cells is proposed. Gallium atoms occupy the 2d site in one of these cells, and silicon atoms occupy this site in the other cell; all other atoms correspondingly coordinate these cations. This structure implements various physical properties exhibited by langasite family crystals. The conclusions are based on processing four data sets obtained with a high resolution (sin θ/λ ≤ 1.35 Å{sup –1}), the results reproduced in repeated experiments, and the high relative precision of the study (sp. gr. P321, Z = 1; at 295 K, a = 8.1652(6) Å, c = 5.0958(5) Å, R/wR = 0.68/0.68%, 3927 independent reflections; at 90.5 K, a = 8.1559(4) Å, c = 5.0913(6) Å, R/wR = 0.92/0.93%, 3928 reflections).

  12. Molybdenum oxide supported on silica (MoO{sub 3}/SiO{sub 2}): an efficient and reusable catalyst for the synthesis of 1,8-dioxodecahydroacridines under solvent-free conditions

    Energy Technology Data Exchange (ETDEWEB)

    Khojastehnezhad, A.; Vafaei, M. [Islamic Azad University, Mashhad Branch, Department of Chemistry, Mashhad (Iran, Islamic Republic of); Moeinpour, F., E-mail: akhojastehnezhad@yahoo.com [Islamic Azad University, Bandar Abbas Branch, Department of Chemistry, Bandar Abbas (Iran, Islamic Republic of)

    2014-07-01

    Silica supported molybdenum oxide (MoO{sub 3}/SiO{sub 2}) was found to be and efficient, eco-friendly and heterogeneous catalyst for the multicomponent reaction of aromatic aldehydes, dimedone and ammonium acetate or aromatic amines under solvent-free conditions to afford the corresponding 1,8-dioxodecahydroacridines in high yields. The catalyst can be easily recovered and reused for several times without considerable loss of activity. Furthermore, the present method offers several advantages, such as an easy experimental and work-up procedures, short reaction times and good to excellent yields. For the characterization were used: Fourier transform infrared spectroscopy (Ft-IR), X-ray diffraction and scanning electron microscopy analyses. (Author)

  13. Studies on Y{sub 2}SiO{sub 5}:Ce phosphors prepared by gel combustion using new fuels

    Energy Technology Data Exchange (ETDEWEB)

    Muresan, L.E., E-mail: laura_muresan2003@yahoo.com [“Raluca Ripan” Institute for Research in Chemistry, Babeş Bolyai University, Fântânele 30, 400294 Cluj-Napoca (Romania); Oprea, B.F.; Cadis, A.I.; Perhaita, I. [“Raluca Ripan” Institute for Research in Chemistry, Babeş Bolyai University, Fântânele 30, 400294 Cluj-Napoca (Romania); Ponta, O. [Faculty of Physics, Babeş Bolyai University, 400084 Cluj-Napoca (Romania)

    2014-12-05

    Highlights: • Y{sub 2}SiO{sub 5}:Ce was prepared by combustion using aspartic or glutamic acid as fuels. • Combustion process occurs differently depending on the fuels amount. • Single phase X2-Y{sub 2}SiO{sub 5} phosphors were obtained in fuel rich conditions. • PL measurements indicate that aspartic acid is a better fuel than glutamic. • Optimal preparative conditions were established for synthesis of Y{sub 2}SiO{sub 5}:Ce. - Abstract: Cerium activated yttrium silicate (Y{sub 2}SiO{sub 5}:Ce) phosphors were prepared by combustion, using yttrium–cerium nitrate as oxidizer, aspartic or glutamic acid as fuel and TEOS as source of silicon. In this study, aspartic and glutamic acid are used for the first time for the synthesis of Y{sub 2}SiO{sub 5}:Ce phosphors. The fuels molar amount was varied from 0.5 mol to 1.5 mol in order to reveal the thermal behavior of intermediary products (gels and ashes) same as the structural and luminescent characteristics of final products (phosphors). According to thermal analysis correlated with FTIR and XPS investigations, the combustion process occurs differently depending on the fuel amount; unreacted nitrate compounds have been identified in fuel lean conditions and carbonate based compounds along with organic residue in rich fuel conditions. The conversion to well crystallized silicates was revealed by changes of FTIR vibration bands and confirmed by XRD measurements. Based on luminescent spectra, aspartic acid is a better fuel than glutamic acid. A positive effect on the luminescence have been observed for samples fired in air due to complete remove of organic residue. The best luminescence was obtained for combustions with 0.75 mol aspartic acid and 1.25 mol glutamic respectively, fired at 1400 °C for 4 h in air atmosphere.

  14. Heat capacities and entropies of Mg/sub 2/SiO/sub 4/, Mn/sub 2/SiO/sub 4/, and Co/sub 2/SiO/sub 4/ between 5 and 380 K

    Energy Technology Data Exchange (ETDEWEB)

    Robie, R.A. (U.s. Geological Survey, Reston, VA); Hemingway, B.S.; Takei, H.

    1982-05-01

    The heat capacities of synthetic single crystals of Mg/sub 2/SiO/sub 4/ (foresterite), Mn/sub 2/SiO/sub 4/ (tephroite), and Co/sub 2/SiO/sub 4/ (cobalt olivine), were measured between 5 and 380 K using an adiabatically shielded calorimeter. Mg/sub 2/SiO/sub 4/ is diamagnetic, and its heat capacity follows a normal sigmoidal curve at low temperatures. Co/sub 2/SiO/sub 4/ shows a single sharp lambda-type transition at 49.85 +/- 0.02 K associated with the antiferromagnetic ordering of the magnetic moments of the Co/sup 2 +/ ions into a collinear spin arrangement below 49.8 K. In contrast to Co/sub 2/SiO/sub 4/ Mn/sub 2/siO/sub 4/ has two transitions in C/sup o//sub p/, a sharp lambda-type transition at 47.38 +/- 0.05 K and a smaller ''shoulder'' in C/sup o//sub p/ centered near 12 K. The upper transition corresponds to the paramagnetic (disordered) to collinear antiferromagnetic ordering of the Mn/sup 2 +/ moments, whereas the shoulder near 12 K corresponds to the change from the collinear to a canted spin structure. Our calorimetric values for the antiferromagnetic-paramagnetic transition temperature (Neel Temperature) are in excellent agreement with those obtained by powder magnetic susceptibility measurements, 49 +/- 2 K and 50 +/- 5 K for Co/sub 2/SiO/sub 4/ and Mn/sub 2/SiO/sub 4/ respectively. The thermal Debye temperature, THETA/sup C//sub D/, of Mg/sub 2/SiO/sub 4/ calculated from our C/sup o//sub p/ measurements between 6.3 and 13.8 K is 768 +/- 15 K and agrees well with the elastic value THETA/sup E//sub D/ of 758 K based on the mean sound velocity calculated from the room temperature elastic stiffness constants (c/sub ij/) of Graham and Barsch. At 298.15 K (25/sup 0/C) the molar heat capacities are 118.6, 128.7, and 133.4 J/(mol . K) and the molar entropies are 94.11 +/- 0.10, 155.9 +/0 0.4 and 142.6 +/- 0.2 J/(mol . K) respectively for Mg/sub 2/SiO/sub 4/, Mn=2SiO/sub 4/, and Co/sub 2/SiO/sub 4/.

  15. Diffusion of single oxidation pond

    Directory of Open Access Journals (Sweden)

    Song Ruo-Yuan

    2016-01-01

    Full Text Available The hydraulic characteristic of an oxidation pond was studied by the tracer experiment, and an empirical formula of Peclet number was obtained, which can be well applied to the model of plug flow reactor with longitudinal diffusion.

  16. Growth and characterization of the La{sub 3}Ga{sub 4.85}Fe{sub 0.15}SiO{sub 14} piezoelectric single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Dou, Renqin [Chinese Academy of Sciences, The Key Laboratory of Photonic Devices and Materials, Anhui Institute of Optics and Fine Mechanics, Hefei, Anhui Province (China); University of Science and Technology of China, Hefei (China); Liu, Wenpeng; Zhang, Qingli; Ding, Shoujun; Sun, Dunlu [Chinese Academy of Sciences, The Key Laboratory of Photonic Devices and Materials, Anhui Institute of Optics and Fine Mechanics, Hefei, Anhui Province (China); Zhang, Qi [Anhui Firesky Crystal Science and Technology Co. Ltd, Tongling (China); Shi, Zibin [26th Institute of China Electronics Technology Group Corporation, Chongqing (China); Wang, Jiyang [Shandong University, State Key Laboratory of Crystal Materials, Jinan (China)

    2017-01-15

    A new piezoelectric single crystal La{sub 3}Ga{sub 4.85}Fe{sub 0.15}SiO{sub 14} (LGFS) was grown by the Czochralski method firstly. Its structural parameters were obtained by Rietveld refinement to the X-ray diffraction. The effective segregation coefficient k{sub eff} of Fe in the LGFS was determined to be 0.6. The cost of LGFS is reduced due to the doping of cheap Fe. The crystal density was measured to be 5.7 g cm{sup -3} by the buoyancy method. The defect structure of LGFS crystal was investigated by the chemical etching with 85% H{sub 2}SO{sub 4} etchant. Dislocation etching pit patterns of LGFS crystal are consistent with the corresponding atomic arrangement schematics. Compared with LGS, LGN, LGT, and LGAS crystal, the LGFS crystal exhibits outstanding dielectric and piezoelectric properties, and ε {sub 11}, ε {sub 33}, d{sub 11}, and d{sub 14} are 20.86, 51.99, 6.5 pC/N, and -5.10 pC/N, respectively. Therefore, LGFS may be a new potential piezoelectric crystal with high performance and low expense. (orig.)

  17. Creep of Oxide Single Crystals

    Science.gov (United States)

    1990-08-01

    earth oxide. -3- There are several rare earth sesquioxide compounds which could be included in Table 1, but only Y2 0 3 and Sc2 0 3 have been listed. This...was done since the rare earth sesquioxides all have densities considerably higher than yttria without any significant advantage in terms of melting...9.1 ɞ.1 ɚ.1 germanium < 69 < 0.16% < 330 < 180 < 260 gold ɘ.02 ɚ.8 ɘ.03 ɘ.002 <,0.001 hafnium 0.8% < 230 < 0.6 < 0.3 < 0.4 holmium < 1.9 < 5.1

  18. Thermoluminescent analysis of amorphous and crystalline SiO{sub 2} exposed to gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Villa S, G.; Mendoza A, D.; Gonzalez, P.R.; Espinosa P, M.E. [ININ, 52750 Ocoyoacac, EStado de Mexico (Mexico)

    2006-07-01

    Silicon oxide (SiO{sub 2}) has been used in electroluminescence and thermoluminescence (TL) devices. However, its emission mechanism have not been yet clearly explained. The crystalline and amorphous SiO{sub 2} luminescent analyses are important to compare their behaviour in order to understand the emission mechanism. For this reason, the present work has the goal to show and compare the thermoluminescent analysis of obsidian and quartz: amorphous and crystalline SiO{sub 2}, respectively. According to the results, quartz shows two TL peaks located at 145 and 215 C, while obsidian shows three TL peaks at 125, 195 and 298 C. Moreover, TL intensity was higher for quartz than obsidian samples. Nonetheless, both signals shown a linear correlation in the interval of radiation dose from 50 to 400 Gy. These facts suggest that the atomic array plays a very important role in the thermoluminescent behaviour of the SiO{sub 2} materials. (Author)

  19. Laser induced single spot oxidation of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Jwad, Tahseen, E-mail: taj355@bham.ac.uk; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-11-30

    Highlights: • A new high resolution laser induced oxidation (colouring) method is proposed (single spot oxidation). • The method is applied to control oxide films thicknesses and hence colours on titanium substrates in micro-scale. • The method enable imprinting high resolution coloured image on Ti substrate. • Optical and morphological periodic surface structures are also produced by an array of oxide spots using the proposed method. • Colour coding of two colours into one field is presented. - Abstract: Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels’ colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

  20. Laser induced single spot oxidation of titanium

    International Nuclear Information System (INIS)

    Jwad, Tahseen; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-01-01

    Highlights: • A new high resolution laser induced oxidation (colouring) method is proposed (single spot oxidation). • The method is applied to control oxide films thicknesses and hence colours on titanium substrates in micro-scale. • The method enable imprinting high resolution coloured image on Ti substrate. • Optical and morphological periodic surface structures are also produced by an array of oxide spots using the proposed method. • Colour coding of two colours into one field is presented. - Abstract: Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels’ colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

  1. Single sheet metal oxides and hydroxides

    DEFF Research Database (Denmark)

    Huang, Lizhi

    The synthesis of layered double hydroxides (LDHs) provides a relatively easy and traditional way to build versatile chemical compounds with a rough control of the bulk structure. The delamination of LDHs to form their single host layers (2D nanosheets) and the capability to reassemble them offer ......) Delamination of the LDHs structure (oxGRC12) with the formation of single sheet iron (hydr)oxide (SSI). (3) Assembly of the new 2D nanosheets layer by layer to achieve desired functionalities....

  2. Direct exchange between silicon nanocrystals and tunnel oxide traps under illumination on single electron photodetector

    Energy Technology Data Exchange (ETDEWEB)

    Chatbouri, S., E-mail: Samir.chatbouri@yahoo.com; Troudi, M.; Sghaier, N.; Kalboussi, A. [Avenue de I’environnement, Université de Monastir, Laboratoire de Micro électronique et Instrumentation (LR13ES12), Faculté des Sciences de Monastir (Tunisia); Aimez, V. [Université de Sherbrooke, Laboratoire Nanotechnologies et Nanosystémes (UMI-LN2 3463), Université de Sherbrooke—CNRS—INSA de Lyon-ECL-UJF-CPE Lyon, Institut Interdisciplinaire d’Innovation Technologique (Canada); Drouin, D. [Avenue de I’environnement, Université de Monastir, Laboratoire de Micro électronique et Instrumentation (LR13ES12), Faculté des Sciences de Monastir (Tunisia); Souifi, A. [Institut des Nanotechnologies de Lyon—site INSA de Lyon, UMR CNRS 5270 (France)

    2016-09-15

    In this paper we present the trapping of photogenerated charge carriers for 300 s resulted by their direct exchange under illumination between a few silicon nanocrystals (ncs-Si) embedded in an oxide tunnel layer (SiO{sub x} = 1.5) and the tunnel oxide traps levels for a single electron photodetector (photo-SET or nanopixel). At first place, the presence of a photocurrent limited in the inversion zone under illumination in the I–V curves confirms the creation of a pair electron/hole (e–h) at high energy. This photogenerated charge carriers can be trapped in the oxide. Using the capacitance-voltage under illumination (the photo-CV measurements) we show a hysteresis chargement limited in the inversion area, indicating that the photo-generated charge carriers are stored at traps levels at the interface and within ncs-Si. The direct exchange of the photogenerated charge carriers between the interface traps levels and the ncs-Si contributed on the photomemory effect for 300 s for our nanopixel at room temperature.

  3. Controlled fabrication of Si nanocrystal delta-layers in thin SiO{sub 2} layers by plasma immersion ion implantation for nonvolatile memories

    Energy Technology Data Exchange (ETDEWEB)

    Bonafos, C.; Ben-Assayag, G.; Groenen, J.; Carrada, M. [CEMES-CNRS and Université de Toulouse, 29 rue J. Marvig, 31055 Toulouse Cedex 04 (France); Spiegel, Y.; Torregrosa, F. [IBS, Rue G Imbert Prolongée, ZI Peynier-Rousset, 13790 Peynier (France); Normand, P.; Dimitrakis, P.; Kapetanakis, E. [NCSRD, Terma Patriarchou Gregoriou, 15310 Aghia Paraskevi (Greece); Sahu, B. S.; Slaoui, A. [ICube, 23 Rue du Loess, 67037 Strasbourg Cedex 2 (France)

    2013-12-16

    Plasma Immersion Ion Implantation (PIII) is a promising alternative to beam line implantation to produce a single layer of nanocrystals (NCs) in the gate insulator of metal-oxide semiconductor devices. We report herein the fabrication of two-dimensional Si-NCs arrays in thin SiO{sub 2} films using PIII and rapid thermal annealing. The effect of plasma and implantation conditions on the structural properties of the NC layers is examined by transmission electron microscopy. A fine tuning of the NCs characteristics is possible by optimizing the oxide thickness, implantation energy, and dose. Electrical characterization revealed that the PIII-produced-Si NC structures are appealing for nonvolatile memories.

  4. Magneto-optical Kerr-effect studies on copper oxide thin films produced by atomic layer deposition on SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Fronk, Michael [Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz (Germany); Mueller, Steve [Center for Microtechnologies, Chemnitz University of Technology, D-09107 Chemnitz (Germany); Waechtler, Thomas; Schulz, Stefan E. [Center for Microtechnologies, Chemnitz University of Technology, D-09107 Chemnitz (Germany); Fraunhofer Institute for Electronic Nano Systems ENAS, D-09126 Chemnitz (Germany); Mothes, Robert; Lang, Heinrich [Inorganic Chemistry, Chemnitz University of Technology, D-09107 Chemnitz (Germany); Zahn, Dietrich R.T. [Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz (Germany); Salvan, Georgeta, E-mail: salvan@physik.tu-chemnitz.de [Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz (Germany)

    2012-05-01

    This work demonstrates the sensitivity of magneto-optical Kerr-effect (MOKE) spectroscopy to ultra-thin nonmagnetic films using the example of copper oxide. The films with an effective thickness between 0.6 nm and 6 nm are produced by atomic layer deposition (ALD) on silicon oxide substrates based on the Cu(I) {beta}-diketonate precursor [({sup n}Bu{sub 3}P){sub 2}Cu(acac)] (acac = acetylacetonate) at a process temperature of 120 Degree-Sign C. The copper oxide films exhibit magneto-optical activity in the spectral ranges around 2.6 eV and above 4 eV. The evolution of the spectral features as a function of the number of ALD cycles is simulated numerically using the dielectric function and the Voigt constant of Cu{sub 2}O as input parameters. The comparison between experimental and simulated MOKE spectra strengthens the conclusion drawn from spectroscopic ellipsometry studies that the thin film optical constants differ markedly from the bulk ones.

  5. Atomically flat single terminated oxide substrate surfaces

    Science.gov (United States)

    Biswas, Abhijit; Yang, Chan-Ho; Ramesh, Ramamoorthy; Jeong, Yoon H.

    2017-05-01

    Scientific interest in atomically controlled layer-by-layer fabrication of transition metal oxide thin films and heterostructures has increased intensely in recent decades for basic physics reasons as well as for technological applications. This trend has to do, in part, with the coming post-Moore era, and functional oxide electronics could be regarded as a viable alternative for the current semiconductor electronics. Furthermore, the interface of transition metal oxides is exposing many new emergent phenomena and is increasingly becoming a playground for testing new ideas in condensed matter physics. To achieve high quality epitaxial thin films and heterostructures of transition metal oxides with atomically controlled interfaces, one critical requirement is the use of atomically flat single terminated oxide substrates since the atomic arrangements and the reaction chemistry of the topmost surface layer of substrates determine the growth and consequent properties of the overlying films. Achieving the atomically flat and chemically single terminated surface state of commercially available substrates, however, requires judicious efforts because the surface of as-received substrates is of chemically mixed nature and also often polar. In this review, we summarize the surface treatment procedures to accomplish atomically flat surfaces with single terminating layer for various metal oxide substrates. We particularly focus on the substrates with lattice constant ranging from 4.00 Å to 3.70 Å, as the lattice constant of most perovskite materials falls into this range. For materials outside the range, one can utilize the substrates to induce compressive or tensile strain on the films and explore new states not available in bulk. The substrates covered in this review, which have been chosen with commercial availability and, most importantly, experimental practicality as a criterion, are KTaO3, REScO3 (RE = Rare-earth elements), SrTiO3, La0.18Sr0.82Al0.59Ta0.41O3 (LSAT), Nd

  6. Influence of silicon dangling bonds on germanium thermal diffusion within SiO{sub 2} glass

    Energy Technology Data Exchange (ETDEWEB)

    Barba, D.; Martin, F.; Ross, G. G. [INRS Centre for Energy, Materials and Telecommunications, 1650 Boul. Lionel-Boulet, Varennes, Québec J3X 1S2 (Canada); Cai, R. S.; Wang, Y. Q. [The Cultivation Base for State Key Laboratory, Qingdao University, Qingdao 266071 (China); Demarche, J.; Terwagne, G. [LARN, Centre de Recherche en Physique de la Matière et du Rayonnement (PMR), University of Namur (FUNDP), B-5000 Namur (Belgium); Rosei, F. [INRS Centre for Energy, Materials and Telecommunications, 1650 Boul. Lionel-Boulet, Varennes, Québec J3X 1S2 (Canada); Center for Self-Assembled Chemical Structures, McGill University, Montreal, Quebec H3A 2K6 (Canada)

    2014-03-17

    We study the influence of silicon dangling bonds on germanium thermal diffusion within silicon oxide and fused silica substrates heated to high temperatures. By using scanning electron microscopy and Rutherford backscattering spectroscopy, we determine that the lower mobility of Ge found within SiO{sub 2}/Si films can be associated with the presence of unsaturated SiO{sub x} chemical bonds. Comparative measurements obtained by x-ray photoelectron spectroscopy show that 10% of silicon dangling bonds can reduce Ge desorption by 80%. Thus, the decrease of the silicon oxidation state yields a greater thermal stability of Ge inside SiO{sub 2} glass, which could enable to considerably extend the performance of Ge-based devices above 1300 K.

  7. Electron-irradiation of oxide single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Caulfield, K.J.; Cooper, R.; Guy, L. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1996-12-31

    Full text: Point defects created in single crystals of CaO, MgO and {alpha}-Al{sub 2}O{sub 3} (sapphire) by electron-irradiation give rise to luminescence from colour centres. The luminescence may be used to monitor the formation of point defects by elastic collision processes. Such processes have great technological importance, in thermoluminescent dosimetry, the development of colour centre lasers, and particularly with the use of sapphire as a first-wall insulator in nuclear fusion reactors. Point defect formation is the initial process which can ultimately lead to dielectric breakdown. By controlling the energy of incident electrons irradiating single crystals, thresholds may be determined for atomic displacement. The time-dependent spectroscopy and decay kinetics of luminescence may also be studied. Displacement thresholds, luminescence spectroscopy and decay kinetics have been studied for CaO, MgO and {alpha}-Al{sub 2}O{sub 3}. Sapphire irradiated with 0.50 MeV electrons, exhibits a broad luminescence emission band around 300 nm at room temperature, which at temperatures below 60 K broadens into two distinct bands around 300 nm and 400 nm. Analysis of the logarithmic decay kinetics of the 300 nm band reveals distinctive features observed in similar oxides by other workers, namely a rapid decrease in intensity punctuated by discrete plateau regions. A model comprising bimolecular electron-hole recombination, in conjunction with unimolecular electron-detrapping, is able to account for these features. 4 refs.

  8. Critical influence of the amorphous silica-to-cristobalite phase transition on the performance of Mn/Na{sub 2}WO{sub 4}/SiO{sub 2} catalysts for the oxidative coupling of methane

    Energy Technology Data Exchange (ETDEWEB)

    Palermo, A. [UNMDP-CONICET, Mar del Plata (Argentina). Inst. of Materials Science and Technology; Vazquez, J.P.H. [CSIC-Univ. Sevilla-Junta de Andalucia (Spain). Inst. de Ciencia de Materiales; Lee, A.F.; Tikhov, M.S.; Lambert, R.M. [Univ. of Cambridge (United Kingdom). Dept. of Chemistry

    1998-07-25

    XRD, XPS/XAES, TPR analysis and catalytic testing have been applied to Na/W/Mn/SiO{sub 2} methane coupling catalysts and to corresponding formulations without one or more of Na, Mn, and W. The authors find a clear correlation between catalyst performance and support structure in the final calcined material. Amorphous silica yields active but very unselective catalysts. Crystalline SiO{sub 2} ({alpha}-cristobalite) generates active and highly selective catalysts--especially with respect to the formation of ethylene. The authors demonstrate that the presence of Na is essential for the anomalous low temperature silica {r_arrow} cristobalite support phase transition to occur. The structural, catalytic, and spectroscopic results indicate that Na plays a dual role as both structural and chemical promoter.

  9. Moisture barrier evaluation of SiO{sub x}/SiN{sub x} stacks on polyimide substrates using electrical calcium test

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shiyu; Xue, Wei; Yu, Zhinong, E-mail: znyu@bit.edu.cn

    2015-04-01

    Electrical calcium (Ca) test was used to measure water vapor transmission rate (WVTR) through polyimide (PI) substrate with barrier films. The WVTR was obtained by measuring the resistance of the Ca as a function of time. Barrier films consisted of silicon oxide (SiO{sub x})/silicon nitride (SiN{sub x}) stacks were consecutively deposited onto the PI substrate at 350 °C by plasma-enhanced chemical vapor deposition. SiN{sub x} and SiO{sub x} films show great moisture impermeability while the SiN{sub x} film presented higher moisture resistance than the SiO{sub x} film. The sample of PI coated with SiO{sub x}/SiN{sub x} stacks was kept flat by stress compensation of SiN{sub x} film and SiO{sub x} film. The WVTR value of the optimum barrier structure (5 pairs of SiO{sub x}/SiN{sub x}) is 5.58 × 10{sup −6} g/(m{sup 2} day) under an electrical Ca test (25 °C, 40% relative humidity). After 500 times cyclic bending in a compressive mode, WVTR value keeps below 4.32 × 10{sup −5} g/(m{sup 2} day). The SiO{sub x}/SiN{sub x} barrier stacks presented on PI have a great potential for flexible electronics applications. - Highlights: • The electrical Ca test was used to measure water vapor transmission rate. • SiO{sub x}/SiN{sub x} stacks as diffusion barrier of water vapor are effective. • The optimum barrier structure is 5 pairs of SiO{sub x}/SiN{sub x}.

  10. Unsupported single-atom-thick copper oxide monolayers

    Science.gov (United States)

    Yin, Kuibo; Zhang, Yu-Yang; Zhou, Yilong; Sun, Litao; Chisholm, Matthew F.; Pantelides, Sokrates T.; Zhou, Wu

    2017-03-01

    Oxide monolayers may present unique opportunities because of the great diversity of properties of these materials in bulk form. However, reports on oxide monolayers are still limited. Here we report the formation of single-atom-thick copper oxide layers with a square lattice both in graphene pores and on graphene substrates using aberration-corrected scanning transmission electron microscopy. First-principles calculations find that CuO is energetically stable and its calculated lattice spacing matches well with the measured value. Furthermore, free-standing copper oxide monolayers are predicted to be semiconductors with band gaps ∼3 eV. The new wide-bandgap single-atom-thick copper oxide monolayers usher a new frontier to study the highly diverse family of two-dimensional oxides and explore their properties and their potential for new applications.

  11. Single Molecule Scanning of DNA Radiation Oxidative Damage Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal will develop an assay to map genomic DNA, at the single molecule level and in a nanodevice, for oxidative DNA damage arising from radiation exposure;...

  12. Single Molecule Scanning of DNA Radiation Oxidative Damage, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal will develop an assay to map genomic DNA, at the single molecule level and in a nanodevice, for oxidative DNA damage arising from radiation exposure;...

  13. Single-photon imaging in complementary metal oxide semiconductor processes

    NARCIS (Netherlands)

    Charbon, E.

    2014-01-01

    This paper describes the basics of single-photon counting in complementary metal oxide semiconductors, through single-photon avalanche diodes (SPADs), and the making of miniaturized pixels with photon-counting capability based on SPADs. Some applications, which may take advantage of SPAD image

  14. Implantation of plasmonic nanoparticles in SiO{sub 2} by pulsed laser irradiation of gold films on SiO{sub x}-coated fused silica and subsequent thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Stolzenburg, H. [Laser-Laboratorium Göttingen, Hans-Adolf-Krebs-Weg 1, 37077 Göttingen (Germany); Peretzki, P.; Wang, N.; Seibt, M. [IV. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany); Ihlemann, J., E-mail: juergen.ihlemann@llg-ev.de [Laser-Laboratorium Göttingen, Hans-Adolf-Krebs-Weg 1, 37077 Göttingen (Germany)

    2016-06-30

    Highlights: • Gold nanoparticles are implanted in glass by pulsed UV-laser irradiation. • Implantation of gold into SiO{sub x} and annealing leads to Au-particles in quartz glass. • TEM investigations reveal particles with 10–60 nm diameter in a depth of 40 nm. • Implanted particles show plasmon resonance at 540 nm. - Abstract: The pulsed UV-laser irradiation of thin noble metal films deposited on glass substrates leads to the incorporation of metal particles in the glass, if a sufficiently high laser fluence is applied. This process is called laser implantation. For the implantation of gold into pure fused silica, high laser fluences (∼1 J/cm{sup 2} at 193 nm laser wavelength) are required. Using a SiO{sub x} (x ≈ 1) coated SiO{sub 2}-substrate, the implantation of gold into this coating can be accomplished at significantly lower fluences starting from 0.2 J/cm{sup 2} (comparable to those used for standard glass). Particles with diameters in the range of 10–60 nm are implanted to a depth of about 40 nm as identified by transmission electron microscopy. An additional high temperature annealing step in air leads to the oxidation of SiO{sub x} to SiO{sub 2}, without influencing the depth distribution of particles significantly. Only superficial, weakly bound particles are released and can be wiped away. Absorption spectra show a characteristic plasmon resonance peak at 540 nm. Thus, pure silica glass (SiO{sub 2}) with near surface incorporated plasmonic particles can be fabricated with this method. Such material systems may be useful for example as robust substrates for surface enhanced Raman spectroscopy (SERS).

  15. Low-temperature synthesis of Zn{sub 2}SiO{sub 4}:Mn green photoluminescence phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Sivakumar, V. [Saveetha Engineering College, Thandalam, Chennai 602105 (India); Lakshmanan, Arunachalam, E-mail: arunachalamlakshmanan@yahoo.com [Saveetha Engineering College, Thandalam, Chennai 602105 (India); Kalpana, S.; Sangeetha Rani, R.; Satheesh Kumar, R. [Saveetha Engineering College, Thandalam, Chennai 602105 (India); Jose, M.T. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2012-08-15

    Zn{sub 2}SiO{sub 4}:Mn green phosphor having comparable photoluminescence (PL) efficiency with commercial phosphor has been synthesized at 1000 Degree-Sign C using solid state reactions involving ZnO, silicic acid and manganese acetate. The water of crystallization attached to SiO{sub 2} in silicic acid whose dissociation at 1000 Degree-Sign C seem to promote the sintering efficiency of Zn{sub 2}SiO{sub 4}:Mn. Incremental ZnO addition and re-firing at 1000 Degree-Sign C promote the diffusion rate of ZnO and SiO{sub 2}. The formation of a single crystalline phase of willemite structure in the samples was confirmed by powder XRD measurements. The phosphor exhibit an intense excitation band centered around 275 nm and a relatively weak excitation centered around 380 nm while the broad band green emission peaks at 524 nm. Other parameters studied include PL spectra, grain morphology, ZnO/SiO{sub 2} molar ratio, Mn concentration, co-dopant/flux and the effect of chemical forms of Mn dopant as well as silica on the PL efficiency. - Highlights: Black-Right-Pointing-Pointer Synthesis of Zn{sub 2}SiO{sub 4}:Mn by solid state sintering at a low temperature of 1000 Degree-Sign C in air. Black-Right-Pointing-Pointer Dissociation of water of crystallization in silicic acid promote sintering efficiency. Black-Right-Pointing-Pointer Photoluminescence efficiency comparable with that of the commercial phosphor. Black-Right-Pointing-Pointer Enhancement in luminescence with MgCO{sub 3} co-doping and refiring as well as ZnO addition. Black-Right-Pointing-Pointer XRD confirm single phase willemite structure (rhombohedral) of Zn{sub 2}SiO{sub 4}:Mn.

  16. Mn-Na{sub 2}WO{sub 4}/SiO{sub 2}. An industrial catalyst for methane coupling?

    Energy Technology Data Exchange (ETDEWEB)

    Yildiz, M.; Arndt, S.; Otremba, T.; Thomas, A.; Schomaeker, R. [Technische Univ. Berlin (Germany). Dept. of Chemistry; Simon, U.; Berthold, A.; Goerke, O.; Schubert, H. [Technische Univ. Berlin (Germany). Dept. of Materials Science; Aksu, Y. [Akdeniz Univ. (Turkey). Dept. of Material Science and Engineering

    2012-07-01

    The oxidative coupling of methane (OCM) is one of the best reactions for the direct conversion of methane. Despite all efforts, a suitable OCM process has not been put into practice yet, due to a lack of active, selective and stable catalyst. Mn-Na{sub 2}WO{sub 4}/SiO{sub 2} has attracted great interest because of its proven long term stability and its highly suitable catalytic performance. In spite of the large number of studies on this catalyst, structural characterizations are very difficult due to its complex trimetallic and multiphase nature. Previously, we studied a broad variety of support materials for the Mn-Na{sub 2}WO{sub 4}/SiO{sub 2} catalyst, e.g. Al{sub 2}O{sub 3}, TiO{sub 2}, ZrO{sub 2} and MgO. We found that SiO{sub 2} is the most suitable support material. A variation of the SiO{sub 2} materials showed that the catalytic performance does not differ substantially. However, the performance of SBA-15 supported Mn-Na{sub 2}WO{sub 4} catalyst was outstanding in comparison to all other silica supported catalysts. The reason of this substantial increase in the activity could be the ordered mesoporous structure of its support material. To understand the reaction mechanism, the kinetic isotope effect (KIE) with CD{sub 4} over Mn-Na{sub 2}WO{sub 4}/SiO{sub 2} was studied, we found that the consecutive oxidation of the C{sub 2} products is an important constraint as described in the literature for other catalysts. In order to apply this catalyst in a miniplant, we developed an upscaled preparation procedure via a fluidized bed granulation, allowing the preparation of large amounts of this catalyst. (orig.)

  17. Direct partial oxidation of methane via single-site chemistry

    Science.gov (United States)

    Kakekhani, Arvin; Norskov, Jens

    Methane (CH4), the cheapest source of hydrocarbons, is a difficult-to-store and hard-to-convert chemical, due to strong and isotropic C-H bonds. Having a selective and efficient method to partially oxidize methane into more useful chemicals including methanol, formaldehyde and alkenes has long been an open challenge for catalysis community. The main challenge is selectivity: if a catalytic material interacts strongly with methane, sufficient to break one C-H bond, it breaks all other bonds of the derivative molecules, as well. This leads to over-oxidization to CO2. Here using density functional theory (DFT) modelings, we discuss the possibility of using defective (vacancy rich) 2-d materials e.g., MoS2 to effectively trap single transition metal atoms; thereby, creating a single-site chemistry to enhance the selectivity of methane oxidation process. A single-site chemistry leads to competition between intermediates and products for limited active sites. Our strategy is to use this as an effective means to block unwanted reaction pathways leading to over-oxidization. United States department of energy.

  18. Refractive-index tailoring and morphological evolutions in Gd{sub 2}O{sub 3}-SiO{sub 2} and ZrO{sub 2}-SiO{sub 2} composite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, N.K.; Thakur, S.; Tokas, R.B.; Kamble, N.M. [Bhabha Atomic Research Centre, Spectroscopy Division, Mumbai (India)

    2007-11-15

    Refractive-index tailoring and morphological evolutions in two different thin film composite systems of gadolinia-silica (Gd{sub 2}O{sub 3}:SiO{sub 2}) and zirconia-silica (ZrO{sub 2}:SiO{sub 2}) deposited through reactive electron-beam codeposition processes are discussed in this research paper. For Gd{sub 2}O{sub 3}:SiO{sub 2} the refractive-index tuning has been achieved from 1.45 to 2.18, whereas in the case of ZrO{sub 2}:SiO{sub 2} the achieved tunable range is from 1.45 to 2.45 in the ultraviolet region. Under certain compositional mixings with lower silica fractions both the systems demonstrated relative microstructural and morphological densifications. Such evolutions were very successfully derived through phase-modulated ellipsometry and atomic force microscopy. The composition-dependent refractive-index tailoring and microstructural densifications have been investigated by adopting Tauc-Lorentz and single-effective-oscillator models. The morphological correlation functions have also very aptly supported such evolutions in these composite films. These experimental results indicate their favourable properties and applicability down to the extreme ultraviolet wavelength region of the electromagnetic spectrum. (orig.)

  19. Epitaxially aligned cuprous oxide nanowires for all-oxide, single-wire solar cells.

    Science.gov (United States)

    Brittman, Sarah; Yoo, Youngdong; Dasgupta, Neil P; Kim, Si-in; Kim, Bongsoo; Yang, Peidong

    2014-08-13

    As a p-type semiconducting oxide that can absorb visible light, cuprous oxide (Cu2O) is an attractive material for solar energy conversion. This work introduces a high-temperature, vapor-phase synthesis that produces faceted Cu2O nanowires that grow epitaxially along the surface of a lattice-matched, single-crystal MgO substrate. Individual wires were then fabricated into single-wire, all-oxide diodes and solar cells using low-temperature atomic layer deposition (ALD) of TiO2 and ZnO films to form the heterojunction. The performance of devices made from pristine Cu2O wires and chlorine-exposed Cu2O wires was investigated under one-sun and laser illumination. These faceted wires allow the fabrication of well-controlled heterojunctions that can be used to investigate the interfacial properties of all-oxide solar cells.

  20. Preparation of transparent fluorocarbon/TiO{sub 2}-SiO{sub 2} composite coating with improved self-cleaning performance and anti-aging property

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jianping, E-mail: zf161162@163.com; Tan, Zhongyuan; Liu, Zhilei; Jing, Mengmeng; Liu, Wenjie; Fu, Wanli

    2017-02-28

    Graphical abstract: Semicrystalline colloidal particles of TiO{sub 2}-SiO{sub 2} composite oxide were prepared via a sol-gel approach and annealed by a microwave heating treatment. The fabricated fluorocarbon/TiO{sub 2}-SiO{sub 2} composite coatings are transparent, exhibit a highly stable and excellent hydrophilicity, an improved photocatalytic activity and outstanding self-cleaning performance. What’s more, the composite coatings display an excellent anti-aging performance toward UV irradiation. These findings indicate that the fluorocarbon/TiO{sub 2}-SiO{sub 2} composite coatings could be potentially used for outdoor applications. - Highlights: • Semicrystalline colloidal particles of TiO{sub 2}-SiO{sub 2} composite oxide presenting a particle size of 6–10 nm were prepared via a sol-gel approach and annealed by microwave heating method. • The fabricated transparent fluorocarbon/TiO{sub 2}-SiO{sub 2} composite coatings exhibited a superior hydrophilicity, an improved photocatalytic activity and excellent self-cleaning performance. • The fluorocarbon/TiO{sub 2}-SiO{sub 2} composite coatings exhibited an excellent anti-aging performance toward UV irradiation, rendering it quite suitable for outdoor applications. - Abstract: This work reports a facile method to fabricate transparent self-cleaning fluorocarbon coatings filled by semicrystalline colloidal particles of TiO{sub 2}-SiO{sub 2} composite oxide presenting a particle size ranging from 6 to 10 nm. Anatase-TiO{sub 2} crystallites were successfully obtained after microwave heating treatment of the TiO{sub 2}-SiO{sub 2} colloidal particles as confirmed by XRD, TEM and FTIR measurements. The fluorocarbon/TiO{sub 2}-SiO{sub 2} composite coatings exhibited a superior hydrophilicity and an improved photocatalytic activity in contrast to the TiO{sub 2}-filled coatings. In particular, a water contact angle (WCA) value of 4.5° and a decolorization ratio relative to methyl orange as high as 96.0% were

  1. Crystallization and electrical resistivity of Cu{sub 2}O and CuO obtained by thermal oxidation of Cu thin films on SiO{sub 2}/Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    De Los Santos Valladares, L., E-mail: ld301@cam.ac.uk [Cavendish Laboratory, University of Cambridge, J.J Thomson Av., Cambridge CB3 0HE (United Kingdom); Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan); Departamento de Fisica, Universidade Federal de Pernambuco, 50670-901, Recife-Pe (Brazil); Salinas, D. Hurtado [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan); Laboratorio de Ceramicos y Nanomateriales, Facultad de Ciencias Fisicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima (Peru); Dominguez, A. Bustamante [Laboratorio de Ceramicos y Nanomateriales, Facultad de Ciencias Fisicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima (Peru); Najarro, D. Acosta [Instituto de Fisica, Departamento de Materia Condensada, Universidad Nacional Autonoma de Mexico, Ap. Postal 20-364, CP 01000 (Mexico); Khondaker, S.I. [NanoScience Technology Centre and Department of Physics, University of Central Florida, Orlando, FL 32826 (United States); Mitrelias, T.; Barnes, C.H.W. [Cavendish Laboratory, University of Cambridge, J.J Thomson Av., Cambridge CB3 0HE (United Kingdom); Aguiar, J. Albino [Departamento de Fisica, Universidade Federal de Pernambuco, 50670-901, Recife-Pe (Brazil); Majima, Y. [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan); CREST, Japan Science and Technology Agency (JST), 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan)

    2012-08-01

    In this work, we study the crystallization and electrical resistivity of the formed oxides in a Cu/SiO{sub 2}/Si thin film after thermal oxidation by ex-situ annealing at different temperatures up to 1000 Degree-Sign C. Upon increasing the annealing temperature, from the X ray diffractogram the phase evolution Cu {yields} Cu + Cu{sub 2}O {yields} Cu{sub 2}O {yields} Cu{sub 2}O + CuO {yields} CuO was detected. Pure Cu{sub 2}O films are obtained at 200 Degree-Sign C, whereas uniform CuO films without structural surface defects such as terraces, kinks, porosity or cracks are obtained in the temperature range 300-550 Degree-Sign C. In both oxides, crystallization improves with annealing temperature. A resistivity phase diagram, which is obtained from the current-voltage response, is presented here. The resistivity was expected to increase linearly as a function of the annealing temperature due to evolution of oxides. However, anomalous decreases are observed at different temperatures ranges, this may be related to the improvement of the crystallization and crystallite size when the temperature increases. - Highlights: Black-Right-Pointing-Pointer The crystallization and electrical resistivity of oxides in a Cu films are studied. Black-Right-Pointing-Pointer In annealing Cu films, the phase evolution Cu + Cu{sub 2}O {yields} Cu{sub 2}O {yields} Cu{sub 2}O + CuO {yields} CuO occurs. Black-Right-Pointing-Pointer A resistivity phase diagram, obtained from the current-voltage response, is presented. Black-Right-Pointing-Pointer Some decreases in the resistivity may be related to the crystallization.

  2. Single crystal ternary oxide ferroelectric integration with Silicon

    Science.gov (United States)

    Bakaul, Saidur; Serrao, Claudy; Youun, Long; Khan, Asif; Salahuddin, Sayeef

    2015-03-01

    Integrating single crystal, ternary oxide ferroelectric thin film with Silicon or other arbitrary substrates has been a holy grail for the researchers since the inception of microelectronics industry. The key motivation is that adding ferroelectric materials to existing electronic devices could bring into new functionality, physics and performance improvement such as non-volatility of information, negative capacitance effect and lowering sub-threshold swing of field effect transistor (FET) below 60 mV/decade in FET [Salahuddin, S, Datta, S. Nano Lett. 8, 405(2008)]. However, fabrication of single crystal ferroelectric thin film demands stringent conditions such as lattice matched single crystal substrate and high processing temperature which are incompatible with Silicon. Here we report on successful integration of PbZr0.2Ti0.8O3 in single crystal form with by using a layer transfer method. The lattice structure, surface morphology, piezoelectric coefficient d33, dielectric constant, ferroelectric domain switching and spontaneous and remnant polarization of the transferred PZT are as good as these characteristics of the best PZT films grown by pulsed laser deposition on lattice matched oxide substrates. We also demonstrate Si based, FE gate controlled FET devices.

  3. Folate conjugated Mn{sub 3}O{sub 4}@SiO{sub 2} nanoparticles for targeted magnetic resonance imaging in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xinyi [The Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); Zhou, Zhiguo, E-mail: zgzhou@shnu.edu.cn [The Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); Wang, Li; Tang, Caizhi; Yang, Hong [The Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); Yang, Shiping, E-mail: shipingy@shnu.edu.cn [The Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); The Education Ministry Key Lab of Pesticide and Chemical Biology, South China Agricultural University, Guangzhou 510641 (China)

    2014-09-15

    Graphical abstract: The Mn{sub 3}O{sub 4}@SiO{sub 2}(PEG)–FA has been used as a T{sub 1}-MRI probe for in vivo. - Highlights: • The PEG and FA modified Mn{sub 3}O{sub 4}@SiO{sub 2} nanoparticles (Mn{sub 3}O{sub 4}@SiO{sub 2}–FA) were prepared. • Mn{sub 3}O{sub 4}@SiO{sub 2}–FA exhibited the good colloidal stability in the simulated biological medium. • Mn{sub 3}O{sub 4}@SiO{sub 2}–FA showed the targeting ability to HeLa cells overexpressed the FA receptor. • The T{sub 1}-weighted magnetic resonance (MR) imaging demonstrated the targeting ability of Mn{sub 3}O{sub 4}@SiO{sub 2}–FA in vivo tumor. - Abstract: The monodisperse silica-coated manganese oxide nanoparticles (Mn{sub 3}O{sub 4}@SiO{sub 2} NPs) were synthesized via the high temperature pyrolysis approach and were aminated through silanization. The amine-functionalized Mn{sub 3}O{sub 4} NPs enabled the covalent conjugation of hydrophilic methoxypoly(ethylene glycol) (PEG) and the targeting ligand of folate (FA) onto their surface. The formed PEG and FA modified Mn{sub 3}O{sub 4} NPs (Mn{sub 3}O{sub 4}@SiO{sub 2}(PEG)–FA) exhibited the good colloidal stability in the simulated biological medium and the targeting ability to HeLa cells overexpressed the FA receptor. The T{sub 1}-weighted magnetic resonance (MR) imaging and inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis of Mn{sub 3}O{sub 4}@SiO{sub 2}(PEG)–FA NPs further demonstrated their targeting ability in tumor.

  4. Single-cell nanotoxicity assays of superparamagnetic iron oxide nanoparticles.

    Science.gov (United States)

    Eustaquio, Trisha; Leary, James F

    2012-01-01

    Properly evaluating the nanotoxicity of nanoparticles involves much more than bulk-cell assays of cell death by necrosis. Cells exposed to nanoparticles may undergo repairable oxidative stress and DNA damage or be induced into apoptosis. Exposure to nanoparticles may cause the cells to alter their proliferation or differentiation or their cell-cell signaling with neighboring cells in a tissue. Nanoparticles are usually more toxic to some cell subpopulations than others, and toxicity often varies with cell cycle. All of these facts dictate that any nanotoxicity assay must be at the single-cell level and must try whenever feasible and reasonable to include many of these other factors. Focusing on one type of quantitative measure of nanotoxicity, we describe flow and scanning image cytometry approaches to measuring nanotoxicity at the single-cell level by using a commonly used assay for distinguishing between necrotic and apoptotic causes of cell death by one type of nanoparticle. Flow cytometry is fast and quantitative, provided that the cells can be prepared into a single-cell suspension for analysis. But when cells cannot be put into suspension without altering nanotoxicity results, or if morphology, attachment, and stain location are important, a scanning image cytometry approach must be used. Both methods are described with application to a particular type of nanoparticle, a superparamagnetic iron oxide nanoparticle (SPION), as an example of how these assays may be applied to the more general problem of determining the effects of nanomaterial exposure to living cells.

  5. Neon adsorption on oxidized single-walled carbon nanohorns

    Science.gov (United States)

    Krungleviciute, Vaiva; Migone, Aldo; Yudasaka, Masako; Iijima, Sumio

    2012-02-01

    We will present the results of a study of neon adsorption on oxidized single-walled carbon nanohorns. Our adsorption isotherm measurements were conducted at temperatures below 24.5 K, the triple point for Ne. Results for the effective specific surface area and for the effective pore volume of the nanohorn aggregates will be presented. We will also report on the sorbent-loading dependence of the isosteric heat of neon on the nanohorns, and on the binding energy. Our results for this system will be compared with those obtained for Ne on a sample of dahlia-like nanohorns annealed at 520 K.

  6. Single drop steam explosions of binary oxides in subcooled water

    International Nuclear Information System (INIS)

    Roberta, C. Hansson; Hyun Sun Park; Bal Raj Sehgal

    2005-01-01

    Full text of publication follows: A steam explosion (vapor explosion or energetic molten fuel-coolant interaction) may occur when a high temperature liquid comes into contact with a cold and volatile liquid. This phenomenon has received much attention in in nuclear industry since it is one of the important safety concerns for the failure of a nuclear containment during a postulated severe accident. Recent well-controlled experiments show, for instance, mixed results on the triggerability of various molten materials (from pure metallic melts to prototypic corium melts). The KROTOS and FARO tests revealed only a mild propagation on triggering of the corium composite melt (UO 2 -ZrO 2 ) in water. On the contrary, highly energetic explosions were observed in the KROTOS tests with pure alumina melt. These different results for the energetics of these materials are not understood. It has been suspected for quite some time that these different results are caused by the different thermo-physical properties and material structure of those melts. Perhaps there are some limiting mechanisms which suppress the vapor explosion process for the corium material (a non-eutectic mixture of oxide materials), in comparison to that for the pure metallic or single oxidic material. To understand these mechanisms, we have performed a series of experimental investigations with various types of molten materials, as corium simulants which range from pure metallic melt to non-eutectic binary oxide melts. The experiments employed a high-speed continuous X-ray radiography system (up to 100,000 fps) to visualize the dynamic fine fragmentation process during steam explosions. Previously X-ray radiography has been successfully employed at the McGill university in Canada and at the University of California at Santa Barbara, USA. Both used flash X-ray systems that take one image per test because of the X-ray recharging time. In spite of this disadvantage, Ciccarelli and Frost successfully visualized

  7. Single-photon imaging in complementary metal oxide semiconductor processes

    Science.gov (United States)

    Charbon, E.

    2014-01-01

    This paper describes the basics of single-photon counting in complementary metal oxide semiconductors, through single-photon avalanche diodes (SPADs), and the making of miniaturized pixels with photon-counting capability based on SPADs. Some applications, which may take advantage of SPAD image sensors, are outlined, such as fluorescence-based microscopy, three-dimensional time-of-flight imaging and biomedical imaging, to name just a few. The paper focuses on architectures that are best suited to those applications and the trade-offs they generate. In this context, architectures are described that efficiently collect the output of single pixels when designed in large arrays. Off-chip readout circuit requirements are described for a variety of applications in physics, medicine and the life sciences. Owing to the dynamic nature of SPADs, designs featuring a large number of SPADs require careful analysis of the target application for an optimal use of silicon real estate and of limited readout bandwidth. The paper also describes the main trade-offs involved in architecting such chips and the solutions adopted with focus on scalability and miniaturization. PMID:24567470

  8. Microstructural characterization of thin SiO{sub x} films obtained by physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Curiel, M.A. [Institute of Engineering, Autonomous University of Baja California, Benito Juarez Blvd. esc. Calle de la Normal, s/n, C. P. 21280 Mexicali, B. C. (Mexico); Nedev, N., E-mail: nicola@iing.mxl.uabc.mx [Institute of Engineering, Autonomous University of Baja California, Benito Juarez Blvd. esc. Calle de la Normal, s/n, C. P. 21280 Mexicali, B. C. (Mexico); Nesheva, D. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd, 1784 Sofia (Bulgaria); Soares, J.; Haasch, R.; Sardela, M. [Center for Microanalysis of Materials, Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, IL 61801 (United States); Valdez, B. [Institute of Engineering, Autonomous University of Baja California, Benito Juarez Blvd. esc. Calle de la Normal, s/n, C. P. 21280 Mexicali, B. C. (Mexico); Sankaran, B. [Center for Microanalysis of Materials, Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, IL 61801 (United States); Manolov, E.; Bineva, I. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd, 1784 Sofia (Bulgaria); Petrov, I. [Center for Microanalysis of Materials, Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, IL 61801 (United States)

    2010-10-25

    X-ray diffraction and reflectivity, X-ray photoelectron spectroscopy and spectroscopic ellipsometry were applied to study the initial composition, thickness, lattice structure and refractive index of 'fresh' and annealed thin SiO{sub x} films ({approx}15 nm) on crystalline silicon substrates, prepared by thermal evaporation of SiO in vacuum. It has been ascertained that the film thickness and composition (x = 1.3) of the 'fresh' films are very close to the values set during the deposition. It has been shown that furnace annealing of the films at 1000 deg. C causes phase separation, film densification and small modification of the Si-SiO{sub x} interface. Transmission electron microscopy results have proven that a self-assembling process leads to formation of Si nanocrystals with a diameter of {approx}4-5 nm and to epitaxial overgrowth of the Si substrate, increasing the c-Si/SiO{sub x} interface transition region to 6-7 monolayers. The nanocrystals are randomly distributed in an amorphous SiO{sub 2} matrix being closer to the Si-SiO{sub x} interface. Formation of tunnel oxide layer with a thickness of 3-5 nm has been found upon annealing. Clockwise hysteresis has been observed in the capacitance-voltage characteristics measured which has been explained by assuming charging and discharging of the nanocrystals with holes, which tunnel from the Si substrate.

  9. Structural and phonon properties of InN synthesized by ion implantation in SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Graine, R. [Laboratoire LPR, Département de Physique, Faculté des Sciences, Université de Annaba, BP 12, Annaba 23000 (Algeria); Centre de Développement des Technologies Avancées, Unité de Recherche en Photonique et Optique (CDTA,URPO), Sétif 19000 (Algeria); Chemam, R., E-mail: che_raf@yahoo.fr [Laboratoire LPR, Département de Physique, Faculté des Sciences, Université de Annaba, BP 12, Annaba 23000 (Algeria); Gasmi, F.Z. [Laboratoire LPR, Département de Physique, Faculté des Sciences, Université de Annaba, BP 12, Annaba 23000 (Algeria); Muller, D. [ICube, Université de Strasbourg UdS and CNRS (UMR7357), 23 rue du Loess, 67037 Strasbourg (France); Schmerber, G. [Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504 du CNRS, Université de Strasbourg UdS-ECPM, 23 Rue du Loess, 67034 Strasbourg (France)

    2015-11-30

    Ion-implantation is a powerful technique for the formation of compound semiconductor nanocrystal precipitates in a host medium. The aim is to elaborate quantum dots for device technology purposes. High dose (5.2 × 10{sup 16} ions/cm{sup 2}) implantations of Indium (In) and Nitrogen (N) ions have been performed in a 206 nm thick SiO{sub 2} layer thermally grown on < 111 > silicon. The implantation energies have been chosen from 12 to 180 keV to produce 5–10 at.% profiles overlapping at a mean depth of about 100 nm. Thermal treatments between 500 °C and 900 °C for different annealing times lead to the formation of InN nanometric precipitates and to cure the oxide defects. In addition, the In{sub 2}O{sub 3} and metallic indium phases have been observed. Their sizes, crystalline structures and depth distributions have been studied as a function of annealing temperature using grazing incidence X-ray diffraction, transmission electron microscopy, Rutherford back scattering spectrometry and Raman spectroscopy. - Highlights: • InN nanocrystals were formed by sequential ion implantation of In and N in SiO{sub 2}. • The In{sub 2}O{sub 3} and metallic indium phases have been found. • Redistribution of In occurs during post-implantation thermal annealing. • Three different InN family sizes were observed in the SiO{sub 2} layer.

  10. Single-ion and single-chain magnetism in triangular spin-chain oxides

    Science.gov (United States)

    Seikh, Md. Motin; Caignaert, Vincent; Perez, Olivier; Raveau, Bernard; Hardy, Vincent

    2017-05-01

    S r4 -xC axM n2Co O9 oxides (x =0 and x =2 ) are found to exhibit magnetic responses typical of single-chain magnets (SCMs) and single-ion magnets (SIMs), two features generally investigated in coordination polymers or complexes. The compound x =0 appears to be a genuine SCM, in that blocking effects associated with slow spin dynamics yield remanence and coercivity in the absence of long-range ordering (LRO). In addition, SIM signatures of nearly identical nature are detected in both compounds, coexisting with SCM in x =0 and with LRO in x =2 . It is also observed that a SCM response can be recovered in x =2 after application of magnetic field. These results suggest that purely inorganic systems could play a valuable role in the topical issue of the interplay among SIM, SCM, and LRO phenomena in low-dimensional magnetism.

  11. Genetic biosensors for imaging nitric oxide in single cells.

    Science.gov (United States)

    Eroglu, Emrah; Charoensin, Suphachai; Bischof, Helmut; Ramadani, Jeta; Gottschalk, Benjamin; Depaoli, Maria R; Waldeck-Weiermair, Markus; Graier, Wolfgang F; Malli, Roland

    2018-02-01

    Over the last decades a broad collection of sophisticated fluorescent protein-based probes was engineered with the aim to specifically monitor nitric oxide (NO), one of the most important signaling molecules in biology. Here we report and discuss the characteristics and fields of applications of currently available genetically encoded fluorescent sensors for the detection of NO and its metabolites in different cell types. Because of its radical nature and short half-life, real-time imaging of NO on the level of single cells is challenging. Herein we review state-of-the-art genetically encoded fluorescent sensors for NO and its byproducts such as peroxynitrite, nitrite and nitrate. Such probes enable the real-time visualization of NO signals directly or indirectly on the level of single cells and cellular organelles and, hence, extend our understanding of the spatiotemporal dynamics of NO formation, diffusion and degradation. Here, we discuss the significance of NO detection in individual cells and on subcellular level with genetic biosensors. Currently available genetically encoded fluorescent probes for NO and nitrogen species are critically discussed in order to provide insights in the functionality and applicability of these promising tools. As an outlook we provide ideas for novel approaches for the design and application of improved NO probes and fluorescence imaging protocols. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

  12. Steps to detect catalytic ethylene oxide formation on single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Boecklein, Sebastian; Guenther, Sebastian; Reichelt, Robert; Seibald, Markus; Preimesser, Andreas; Ehrensberger, Martin; Rozsa, Gergely; Wintterlin, Joost [Ludwig-Maximilians-Universitaet, 81377 Muenchen (Germany)

    2010-07-01

    As part of a project to bridge the ''pressure gap'' for the catalytic synthesis of ethylene oxide (EtO) on Ag surfaces we have undertaken extensive studies in a model reactor. The investigations aimed at finding conditions under which the production of EtO can be unambiguously and quantitatively detected on single crystal Ag surfaces, a challenging task because of the extremely low ethylene-to-EtO reaction probability. The experiments were performed in a specially designed reactor, and they involved the variation of partial pressures, temperature, and type of Ag samples (powders and polycrystalline sheets), and great effort was expended for proper background subtraction. We find that for the sheets an essential ingredient is an activation treatment by annealing in oxygen, which raises the activity by more than one order of magnitude. There are indications that subsurface O atoms are created by this pretreatment. The maximum values obtained for activity, selectivity, yield, and reaction probability allow us to predict that EtO produced on a single Ag crystal can indeed be detected under flow conditions in a UHV chamber. Experiments on the deactivation show that sintering plays an important role for the dispersed samples, but that there is an additional deactivation process for the sheets that is not caused by sintering or poisoning.

  13. A New Multiphase Equation of State for SiO>2

    Energy Technology Data Exchange (ETDEWEB)

    Maerzke, Katie A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gammel, J. Tinka [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-06

    SiO>2 is found as α-quartz at ambient conditions. Under shock compression, it transforms into a much higher density stishovite-like phase around 20 GPa, then into a liquid phase above 100 GPa. The SESAME library contains older equations of state for α-quartz, polycrystalline quartz, and fused quartz. These equations of state model the material as a single phase; i.e., there is no high pressure phase transition. Somewhat more recently (in 1992), Jon Boettger published equations of state for α-quartz, coesite, and stishovite, along with a phase transition model to mix them. However, we do not have a multiphase EOS that captures the phase transitions in this material. Others are working on a high-accuracy model for very high pressure SiO>2, since liquid quartz is used as an impedance matching standard above 100 GPa; however, we are focused on the 10-50 GPa range. This intermediate pressure range is most relevant for modeling the decomposition products of silicone polymers such as Sylgard 184 and SX358.

  14. Single Particle Studies of Heterogeneous Atmospheric Chemistry on Aluminum Oxide Particles in a Quadrupole Trap

    National Research Council Canada - National Science Library

    Hunter, A

    2000-01-01

    ... on upper atmospheric chemical cycles and ozone. The experimental investigation employs a laboratory quadrupole trap electrodynamic levitation apparatus to study heterogeneous processes on single aluminum oxide particles representative...

  15. Development of single chamber solid oxide fuel cells (SCFC)

    Energy Technology Data Exchange (ETDEWEB)

    Viricelle, J.-P.; Udroiu, S.; Gadacz, G.; Pijolat, M.; Pijolat, C. [Ecole Nationale Superieure des Mines de Saint-Etienne, Centre SPIN, LPMG-UMR CNRS 5148, 158 cours Fauriel, 42023 Saint-Etienne Cedex 02 (France)

    2010-08-15

    Single Chamber Solid Oxide Fuel Cells (SCFC) have been prepared using an electrolyte as support (Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} named GDC). Anode (Ni-GDC) and different cathodes (Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3} (SSC), Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (BSCF) and La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSM)) were placed on the same side of the electrolyte. All the electrodes were deposited using screen-printing technology. A gold collector was also deposited on the cathode to decrease the over-potential. The different materials and fuel cell devices were tested under propane/air mixture, after a preliminary treatment under hydrogen to reduce the as-deposited nickel oxide anode. The results show that SSC and BSCF cathodes are not stable in these conditions, leading to a very low open circuit voltage (OCV) of 150 mV. Although LSM material is not the more adequate cathode regarding its high catalytic activity towards hydrocarbon conversion, it has a better chemical stability than SSC and BSCF. Ni-GDC-LSM SCFC devices were elaborated and tested; an OCV of nearly 750 mV could be obtained with maximum power densities around 20 mW cm{sup -2} at 620 C, under air-propane mixture with C{sub 3}H{sub 8}/O{sub 2} ratio equal to 0.53. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  16. Platinum-modified SiO{sub 2} with tubular morphology as efficient membrane-type microreactors for mineralization of formic acid

    Energy Technology Data Exchange (ETDEWEB)

    Anastasescu, Crina; Anastasescu, Mihai; Zaharescu, Maria; Balint, Ioan, E-mail: ibalint@icf.ro [Romanian Academy, Institute of Physical Chemistry (Romania)

    2012-10-15

    SiO{sub 2} amorphous tubes with the internal diameter ranging between 5 and 170 nm and having the aspect ratios typically >50, were prepared using DL-tartaric acid as inorganic template. The tubular SiO{sub 2} was impregnated with a platinum precursor (H{sub 2}PtCl{sub 6}), dried and then reduced with H{sub 2}. The TEM, XPS, FTIR characterization methods revealed that platinum species were located preferentially on the inner walls of tubes having diameter smaller than 100 nm. The walls of SiO{sub 2} nanotubes proved to be amorphous and highly porous, the diameter of pores covering a wide range of radii. The macroporosity of the SiO{sub 2} tubes originated from the open ends of the tubes with the diameter {>=}100 nm, whereas the pores located in the walls of tubes were responsible for the meso and microporosity. Finer Pt nanoparticles (0.9 nm average size) were obtained after the catalyst was dried in air in mild conditions compared to the catalytic material reduced with H{sub 2} (5.3 nm mean size) According to FTIR results, strong metal-support interaction was evidenced between platinum nanoparticles and inner walls of SiO{sub 2} nanotubes. In order to observe the effect of Pt nanoparticle morphology on catalytic behavior, the activity of platinum-modified SiO{sub 2} tubes (1 wt% Pt/SiO{sub 2}) for the oxidation of formic acid to CO{sub 2} was investigated in the 20-75 Degree-Sign C temperature range. The catalytic activity-morphology relationship of Pt/SiO{sub 2} nanotubes was studied and the results were explained in light of experimental results. The catalytic experiments revealed for the first time that SiO{sub 2} nanotubes with highly permeable walls behave as efficient membrane-type microreactors for the oxidation of formic acid to CO{sub 2}. This type of morphological-dependent catalysis may prove to be an efficient tool in near future for the abatement of pollutants in liquid phase.

  17. Nanogranular SiO{sub 2} proton gated silicon layer transistor mimicking biological synapses

    Energy Technology Data Exchange (ETDEWEB)

    Liu, M. J.; Huang, G. S., E-mail: gshuang@fudan.edu.cn, E-mail: pfeng@nju.edu.cn; Guo, Q. L.; Tian, Z. A.; Li, G. J.; Mei, Y. F. [Department of Materials Science, Fudan University, Shanghai 200433 (China); Feng, P., E-mail: gshuang@fudan.edu.cn, E-mail: pfeng@nju.edu.cn; Shao, F.; Wan, Q. [School of Electronic Science and Engineering and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2016-06-20

    Silicon on insulator (SOI)-based transistors gated by nanogranular SiO{sub 2} proton conducting electrolytes were fabricated to mimic synapse behaviors. This SOI-based device has both top proton gate and bottom buried oxide gate. Electrical transfer properties of top proton gate show hysteresis curves different from those of bottom gate, and therefore, excitatory post-synaptic current and paired pulse facilitation (PPF) behavior of biological synapses are mimicked. Moreover, we noticed that PPF index can be effectively tuned by the spike interval applied on the top proton gate. Synaptic behaviors and functions, like short-term memory, and its properties are also experimentally demonstrated in our device. Such SOI-based electronic synapses are promising for building neuromorphic systems.

  18. Selective-area growth of GaN nanowires on SiO{sub 2}-masked Si (111) substrates by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Kruse, J. E.; Doundoulakis, G. [Department of Physics, University of Crete, P. O. Box 2208, 71003 Heraklion (Greece); Institute of Electronic Structure and Laser, Foundation for Research and Technology–Hellas, N. Plastira 100, 70013 Heraklion (Greece); Lymperakis, L. [Max-Planck-Institut für Eisenforschung, Max-Planck-Straße 1, 40237 Düsseldorf (Germany); Eftychis, S.; Georgakilas, A., E-mail: alexandr@physics.uoc.gr [Department of Physics, University of Crete, P. O. Box 2208, 71003 Heraklion (Greece); Adikimenakis, A.; Tsagaraki, K.; Androulidaki, M.; Konstantinidis, G. [Institute of Electronic Structure and Laser, Foundation for Research and Technology–Hellas, N. Plastira 100, 70013 Heraklion (Greece); Olziersky, A.; Dimitrakis, P.; Ioannou-Sougleridis, V.; Normand, P. [Institute of Nanoscience and Nanotechnology, NCSR Demokritos, Patriarchou Grigoriou and Neapoleos 27, 15310 Aghia Paraskevi, Athens (Greece); Koukoula, T.; Kehagias, Th.; Komninou, Ph. [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2016-06-14

    We analyze a method to selectively grow straight, vertical gallium nitride nanowires by plasma-assisted molecular beam epitaxy (MBE) at sites specified by a silicon oxide mask, which is thermally grown on silicon (111) substrates and patterned by electron-beam lithography and reactive-ion etching. The investigated method requires only one single molecular beam epitaxy MBE growth process, i.e., the SiO{sub 2} mask is formed on silicon instead of on a previously grown GaN or AlN buffer layer. We present a systematic and analytical study involving various mask patterns, characterization by scanning electron microscopy, transmission electron microscopy, and photoluminescence spectroscopy, as well as numerical simulations, to evaluate how the dimensions (window diameter and spacing) of the mask affect the distribution of the nanowires, their morphology, and alignment, as well as their photonic properties. Capabilities and limitations for this method of selective-area growth of nanowires have been identified. A window diameter less than 50 nm and a window spacing larger than 500 nm can provide single nanowire nucleation in nearly all mask windows. The results are consistent with a Ga diffusion length on the silicon dioxide surface in the order of approximately 1 μm.

  19. Thin films of metal oxides on metal single crystals: Structure and growth by scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Galloway, H.C.

    1995-12-01

    Detailed studies of the growth and structure of thin films of metal oxides grown on metal single crystal surfaces using Scanning Tunneling Microscopy (STM) are presented. The oxide overlayer systems studied are iron oxide and titanium oxide on the Pt(III) surface. The complexity of the metal oxides and large lattice mismatches often lead to surface structures with large unit cells. These are particularly suited to a local real space technique such as scanning tunneling microscopy. In particular, the symmetry that is directly observed with the STM elucidates the relationship of the oxide overlayers to the substrate as well as distinguishing, the structures of different oxides

  20. The crack healing behavior of Si{sub 3}N{sub 4} ceramics with SiO{sub 2} 1.3 wt.% nano-colloid additive

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Ki Woo [Materials Science and Engineering, Pukyong Nat' l Univ, Busan, 608-739 (Korea, Republic of); Park, Sang Hyun [UR Interdisciplinary program of Mechanical Engineering, Pukyong Nat l Univ, Busan, 608-739 (Korea, Republic of); Kim, Jong Soon, E-mail: 1namkw@pknu.ac.kr, E-mail: ybf9522@naver.com, E-mail: jskimO122@ngetech.com [NGE Tech Co Ltd., 1545-1 Songjeong-dong, Gangseo-gu, Busan, 618-818 (Korea, Republic of)

    2011-10-29

    This study analyzed the crack healing behavior of Si{sub 3}N{sub 4} composite ceramics (SSTS-1) with SiO{sub 2} 1.3 wt.% nano-colloid additive, compared with that of Si{sub 3}N{sub 4} composite ceramics (SSTS-2) with SiO{sub 2} 0.0 wt.% nano-colloid additive. Cracks of about 100 - 500 {mu}m were obtained from a single and multi-Vickers indenter using the load of 24.5 - 98N. All specimens underwent heat treatment in an air atmosphere for one hour at temperatures of 1,273 K after hydraulic pressure coating on the specimens surface with cracks was implemented. In this study, the SSTS-2 specimens with SiO{sub 2} 1.3 wt.% nano-colloid additive exhibited much higher strength values than that of the SSTS-1 specimens with SiO{sub 2} 0.0 wt.% nano-colloid additive in each condition.Introduction.

  1. Pyrolysis synthesis of Zn{sub 2}SiO{sub 4}:Mn{sup 2+} phosphors – effect of fuel, flux and co-dopants

    Energy Technology Data Exchange (ETDEWEB)

    Sivakumar, V.; Lakshmanan, Arunachalam, E-mail: arunachalamlakshmanan@yahoo.com

    2014-01-15

    Green emitting α-Zn{sub 2}SiO{sub 4}:Mn{sup 2+} phosphors were made by pyrolysis route at 600 °C followed by sintering at a moderate temperature of 1000 °C for 1 h duration. The effects of different fuels (urea, citric acid, polyethylene glycol and glycine), flux materials (H{sub 3}BO{sub 3}, NH{sub 4}Cl, NH{sub 4}F, NH{sub 4}Br, BaCl{sub 2}, BaBr{sub 2}, CaF{sub 2} and BaF{sub 2}), divalant co-dopants (Ca{sup 2+}, Ba{sup 2+}, Mg{sup 2+} and Sr{sup 2+}), trivalent co-dopants (Al{sup 3+}, Y{sup 3+} and Gd{sup 3+}) and sintering temperature (800–1000 °C) on the photoluminescence (PL) efficiency of Zn{sub 2}SiO{sub 4}:Mn{sup 2+} were studied. Among the fuels, urea and among the flux, H{sub 3}BO{sub 3} gave a maximum broad band green PL emission peak at 525 nm on excitation at 254 nm. Divalent co-dopants improved the PL intensity much more than the trivalent co-dopants used. Highest PL efficiency was observed with Sr{sup 2+} co-doped Zn{sub 2}SiO{sub 4}:Mn{sup 2+} sintered at 1000 °C in reducing atmosphere which was 20% higher than that of the commercial Zn{sub 2}SiO{sub 4}:Mn{sup 2+}. The formation of a single crystalline phase of willemite structure in the α-Zn{sub 2}SiO{sub 4}:Mn{sup 2+} samples synthesized was confirmed by powder XRD measurements. -- Highlights: • Zn{sub 2}SiO{sub 4}:Mn{sup 2+} green phosphors were made by pyrolysis route. • Effect of fuel, flux and co dopant on PL intensity. • Enhancement in luminescence with divalent co-dopants, notably Sr. • PL efficiency 20% higher than that of the commercial phosphor. • XRD confirm single phase willemite structure of Zn{sub 2}SiO{sub 4}:Mn{sup 2+}.

  2. Development of damage resistant sputtered oxide optical coatings for use at 248 NM

    Energy Technology Data Exchange (ETDEWEB)

    Pawlewicz, W.T.; Martin, P.M.; Hays, D.D.; Mann, I.B.

    1981-10-01

    This report summarizes the results of a six-month effort to develop damage-resistant Kr*F laser mirrors by using and refining reactive sputter deposition techniques for the fabricaton of multilayer oxide optical coatings. Mirror performance goals included a reflectivity of 99% at 248 nm and a laser damage threshold of 5 J/cm/sup 2/ for 20 ns pulses. Oxide multilayer coating combinations selected for development were SiO/sub 2//Al/sub 2/O/sub 3/, SiO/sub 2//HfO/sub 2/ and SiO/sub 2//Y/sub 2/O/sub 3/. Selection was based on review and compilation of the optical properties of oxide materials reported in the recent literature. Twenty-eight coatings of selected designs were fabricated on LLNL substrates for laser damage testing by LLNL. Forty other coatings were fabricated on PNL substrates for optical, microstructural and topographical characterization by PNL aimed at optimization of their performance. Specimens for damage testing consisted of single layers of Al/sub 2/O/sub 3/, HfO/sub 2/ and Y/sub 2/O/sub 3/ in thicknesses of lambda/2, 3lambda/2 and 2lambda at 248 nm plus high reflectors of the design LL (HL)/sup m/ HLL.

  3. Thermodynamics of the Li{sub 4}SiO{sub 4}/H{sub 2}O system

    Energy Technology Data Exchange (ETDEWEB)

    Alvani, C.; Casadio, S. [ENEA, Casaccia (Italy); Johnson, C.

    1998-03-01

    The chemical interaction of He or He+0.1%H{sub 2} purge gases with Li{sub 4}SiO{sub 4} pebbles has been examined as a function temperature and partial pressure of water vapor by Temperature Programmed Reduction (TPR) and Temperature Programmed Desorption (TPD) measurements. The experimental conditions were selected to be representative of those envisaged occurring in the HCPB (Helium-Cooled Pebble Bed) blanket. At constant partial pressure of moisture, water adsorption on Li{sub 4}SiO{sub 4} decreases with increasing temperature up to 973K. Above that temperature water absorption increases due of the increasing water solubility of lithium hydroxide with temperature. Using these data, thermodynamic calculations have been carried out to evaluate the behavior of lithium orthosilicate in a moisture-containing environment. The evaluation was done over the 773 to 1173K temperature range. In general, the behavior of lithium orthosilicate was similar to earlier studies on lithium oxide except that the orthosilicate is not as strong in its deviations from ideality as the oxide. (author)

  4. Reaction kinetics of oxygen on single-phase alloys, oxidation of nickel and niobium alloys

    International Nuclear Information System (INIS)

    Lalauze, Rene

    1973-01-01

    This research thesis first addresses the reaction kinetics of oxygen on alloys. It presents some generalities on heterogeneous reactions (conventional theory, theory of jumps), discusses the core reaction (with the influence of pressure), discusses the influence of metal self-diffusion on metal oxidation kinetics (equilibrium conditions at the interface, hybrid diffusion regime), reports the application of the hybrid diffusion model to the study of selective oxidation of alloys (Wagner model, hybrid diffusion model) and the study of the oxidation kinetics of an alloy forming a solid solution of two oxides. The second part reports the investigation of the oxidation of single phase nickel and niobium alloys (phase α, β and γ)

  5. Generation of silicon nanocrystals by damage free continuous wave laser annealing of substrate-bound SiO{sub x} films

    Energy Technology Data Exchange (ETDEWEB)

    Fricke-Begemann, T., E-mail: fricke-begemann@llg-ev.de; Ihlemann, J. [Laser-Laboratorium Göttingen e.V., Hans-Adolf-Krebs-Weg 1, 37077 Göttingen (Germany); Wang, N.; Peretzki, P.; Seibt, M. [IV. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany)

    2015-09-28

    Silicon nanocrystals have been generated by laser induced phase separation in SiO{sub x} films. A continuous wave laser emitting at 405 nm is focused to a 6 μm diameter spot on 530 nm thick SiO{sub x} films deposited on fused silica substrates. Irradiation of lines is accomplished by focus scanning. The samples are investigated by atomic force microscopy, TEM, Raman spectroscopy, and photoluminescence measurements. At a laser power of 35 mW corresponding to an irradiance of about 1.2 × 10{sup 5 }W/cm{sup 2}, the formation of Si-nanocrystals in the film without any deterioration of the surface is observed. At higher laser power, the central irradiated region is oxidized to SiO{sub 2} and exhibits some porous character, while the surface remains optically smooth, and nanocrystals are observed beside and beneath this oxidized region. Amorphous Si-nanoclusters are formed at lower laser power and around the lines written at high power.

  6. Luminescent and magnetic properties of Fe{sub 3}O{sub 4}@SiO{sub 2}:phen:Eu{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Raphael Lucas de Sousa; Figueiredo, Alberthmeiry Teixeira de; Barrado, Cristiano Morita, E-mail: alberth@ufg.br [Universidade Federal de Goiás (UFG), Catalão, GO (Brazil). Departamento de Química; Sousa, Marcelo Henrique [Universidade de Brasília (UnB), DF (Brazil). Faculdade de Ceilândia

    2017-10-15

    Magnetite was doped with rare earth ions (europium) to produce core-shell materials with both magnetic and luminescent properties, i.e., a magnetic Fe{sub 3}O{sub 4} oxide core and a SiO{sub 2} :phen:Eu{sup 3+} shell. The resulting material was analyzed by X-ray powder diffraction and transmission electron microscopy, and subjected to magnetic and luminescence emission measurements. All the synthesized materials exhibited superparamagnetic behavior and luminescence emission. The magnetic behavior of Fe{sub 3}O{sub 4} and luminescence emission of SiO{sub 2} :phen:Eu{sup 3+} of the materials were compared to precursors. (author)

  7. Single crystal particles of a mesoporous mixed transition metal oxide with a wormhole structure.

    Science.gov (United States)

    Lee, B; Lu, D; Kondo, J N; Domen, K

    2001-10-21

    A new type of mesoporous mixed transition metal oxide of Nb and Ta (NbTa-TIT-1) has been prepared through a two-step calcination, which consists of single crystal particles with wormhole mesoporous structure.

  8. Catalytic water oxidation by single-site ruthenium catalysts.

    Science.gov (United States)

    Concepcion, Javier J; Jurss, Jonah W; Norris, Michael R; Chen, Zuofeng; Templeton, Joseph L; Meyer, Thomas J

    2010-02-15

    A series of monomeric ruthenium polypyridyl complexes have been synthesized and characterized, and their performance as water oxidation catalysts has been evaluated. The diversity of ligand environments and how they influence rates and reaction thermodynamics create a platform for catalyst design with controllable reactivity based on ligand variations.

  9. Role of N-methyl-2-pyrrolidone for preparation of Fe{sub 3}O{sub 4}@SiO{sub 2} controlled the shell thickness

    Energy Technology Data Exchange (ETDEWEB)

    Wee, Sung-Bok [Hanyang University, Division of Materials Science and Engineering (Korea, Republic of); Oh, Hyeon-Cheol [Korea Nano Plus, Inc. (Korea, Republic of); Kim, Tae-Gyun; An, Gye-Seok; Choi, Sung-Churl, E-mail: choi0505@hanyang.ac.kr [Hanyang University, Division of Materials Science and Engineering (Korea, Republic of)

    2017-04-15

    We developed a simple and novel approach for the synthesis of Fe{sub 3}O{sub 4}@SiO{sub 2} nanoparticles with controlled shell thickness, and studied the mechanism. The introduction of N-methyl-2-pyrrolidone (NMP) led to trapping of monomer nuclei in single shell and controlled the shell thickness. Fe{sub 3}O{sub 4}@SiO{sub 2} controlled the shell thickness, showing a high magnetization value (64.47 emu/g). Our results reveal the role and change in the chemical structure of NMP during the core-shell synthesis process. NMP decomposed to 4-aminobutanoic acid in alkaline condition and decreased the hydrolysis rate of the silica coating process.

  10. Method for harvesting rare earth barium copper oxide single crystals

    Science.gov (United States)

    Todt, Volker R.; Sengupta, Suvankar; Shi, Donglu

    1996-01-01

    A method of preparing high temperature superconductor single crystals. The method of preparation involves preparing precursor materials of a particular composition, heating the precursor material to achieve a peritectic mixture of peritectic liquid and crystals of the high temperature superconductor, cooling the peritectic mixture to quench directly the mixture on a porous, wettable inert substrate to wick off the peritectic liquid, leaving single crystals of the high temperature superconductor on the porous substrate. Alternatively, the peritectic mixture can be cooled to a solid mass and reheated on a porous, inert substrate to melt the matrix of peritectic fluid while leaving the crystals melted, allowing the wicking away of the peritectic liquid.

  11. Nanocrystalline diamond in carbon implanted SiO{sub 2}.

    Energy Technology Data Exchange (ETDEWEB)

    Tsoi, K.A.; Prawer, S.; Nugent, K.W.; Walker, R. J.; Weiser, P.S. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1996-12-31

    Recently, it was reported that nanocrystalline diamond can be produced via laser annealing of a high dose C implanted fused quartz (SiO{sub 2}) substrate. The aim of this investigation is to reproduce this result on higher C{sup +} dose samples and the non-implanted silicon sample, as well as optimise the power range and annealing time for the production of these nanocrystals of diamond. In order to provide a wide range of laser powers the samples were annealed using an Ar ion Raman laser. The resulting annealed spots were analysed using scanning electron microscopy (SEM) and Raman analysis. These techniques are employed to determine the type of bonding produced after laser annealing has occurred. 4 refs., 5 figs.

  12. Large-Scale Synthesis of Single-Crystalline Iron Oxide Magnetic Nanorings

    DEFF Research Database (Denmark)

    Jia, Chun-Jiang; Sun, Ling-Dong; Luo, Feng

    2008-01-01

    We present an innovative approach to the production of single-crystal iron oxide nanorings employing a solution-based route. Single-crystal hematite (alpha-Fe2O3) nanorings were synthesized using a double anion-assisted hydrothermal method (involving phosphate and sulfate ions), which can be divi...

  13. Functionalization of oxidized single-walled carbon nanotubes with 4 ...

    Indian Academy of Sciences (India)

    The low-dimension and remarkable physical proper- ties of single-walled carbon nanotubes (SWCNTs) ren- der them unique material properties with a wide range of potential applications.1,2 However, the lack of sol- ubility in solvents presents a considerable impediment toward harnessing of their applications.

  14. Surface spins disorder in uncoated and SiO{sub 2} coated maghemite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zeb, F. [Nanoscience and Technology Laboratory, International Islamic University, H-10, 44000 Islamabad (Pakistan); Nadeem, K., E-mail: kashif.nadeem@iiu.edu.pk [Nanoscience and Technology Laboratory, International Islamic University, H-10, 44000 Islamabad (Pakistan); Shah, S. Kamran Ali; Kamran, M. [Nanoscience and Technology Laboratory, International Islamic University, H-10, 44000 Islamabad (Pakistan); Gul, I. Hussain [School of Chemical & Materials Engineering, National University of Sciences and Technology (NUST), H-12, 44000 Islamabad, Pakistan (Pakistan); Ali, L. [Materials Research Laboratory, International Islamic University, H-10, 44000 Islamabad (Pakistan)

    2017-05-01

    We studied the surface spins disorder in uncoated and silica (SiO{sub 2}) coated maghemite (γ-Fe{sub 2}O{sub 3}) nanoparticles using temperature and time dependent magnetization. The average crystallite size for SiO{sub 2} coated and uncoated nanoparticles was about 12 and 29 nm, respectively. Scanning electron microscopy (SEM) showed that the nanoparticles are spherical in shape and well separated. Temperature scans of zero field cooled (ZFC)/field cooled (FC) magnetization measurements showed lower average blocking temperature (T{sub B}) for SiO{sub 2} coated maghemite nanoparticles as compared to uncoated nanoparticles. The saturation magnetization (M{sub s}) of SiO{sub 2} coated maghemite nanoparticles was also lower than the uncoated nanoparticles and is attributed to smaller average crystallite size of SiO{sub 2} coated nanoparticles. For saturation magnetization vs. temperature data, Bloch's law (M(T)= M(0).(1− BT{sup b})) was fitted well for both uncoated and SiO{sub 2} coated nanoparticles and yields: B =3×10{sup −7} K{sup -b}, b=2.22 and B=0.0127 K{sup -b}, b=0.57 for uncoated and SiO{sub 2} coated nanoparticles, respectively. Higher value of B for SiO{sub 2} coated nanoparticles depicts decrease in exchange coupling due to enhanced surface spins disorder (broken surface bonds) as compared to uncoated nanoparticles. The Bloch's exponent b was decreased for SiO{sub 2} coated nanoparticles which is due to their smaller average crystallite size or finite size effects. Furthermore, a sharp increase of coercivity at low temperatures (<25 K) was observed for SiO{sub 2} coated nanoparticles which is also due to contribution of increased surface anisotropy or frozen surface spins in these smaller nanoparticles. The FC magnetic relaxation data was fitted to stretched exponential law which revealed slower magnetic relaxation for SiO{sub 2} coated nanoparticles. All these measurements revealed smaller average crystallite size and enhanced surface

  15. Sol-gel coatings in the ZrO{sub 2}-SiO{sub 2} system for protection of historical works of glass

    Energy Technology Data Exchange (ETDEWEB)

    Carmona, N. [Fundacion Centro Nacional del Vidrio, Real Fabrica de Cristales. Po Pocillo, 1. 40100 La Granja de San Ildefonso (Segovia) (Spain)]. E-mail: ncarmona@cenim.csic.es; Villegas, M.A. [Centro Nacional de Investigaciones Metalurgicas, CSIC. Avda, Gregorio del Amo, 8. 28040 Madrid (Spain); Fernandez Navarro, J.M. [Instituto de Optica Daza de Valdes, CSIC. C. Serrano, 121. 28006 Madrid (Spain)

    2006-12-05

    Different kinds of protective treatments based on sol-gel coatings have been designed and prepared. Final application of these coatings would be used for protection and preventive conservation of a wide variety of historical glasses from several times and provenance. Historical glasses show a superficial deterioration depending on the exhibition conditions submitted by the ancient objects since their origin. The coatings effectiveness was confirmed by means of accelerated ageing tests under simulated atmospheric polluted conditions by using SO{sub 2} as a pollutant and different kind of glasses as reference substrates. Coatings with compositions 100SiO{sub 2} and 10ZrO{sub 2}.90SiO{sub 2} (mol%) proved to be highly protective when they were densified up to 250 and 400 deg. C for 1 h. Those coatings densified at lower temperature (for instance, 60 deg. C for 3 days) appeared partially cracked and detached after the ageing tests. For compositions 50ZrO{sub 2}.50SiO{sub 2} and 100ZrO{sub 2} the major problem was concerned to the high surface reflectance provided by the zirconium oxide, which modifies very much the appearance of the substrate glasses.

  16. Toluene and chlorobenzene dinitration over solid H{sub 3}PO{sub 4}/MoO{sub 3}/SiO{sub 2} catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Adamiak, Joanna, E-mail: jadamiak@ch.pw.edu.pl [Warsaw University of Technology, Faculty of Chemistry, Division of High Energetic Materials, Noakowskiego 3, 00-664 Warsaw (Poland); Kalinowska-Alichnewicz, Dorota; Szadkowski, Michal; Skupinski, Wincenty [Warsaw University of Technology, Faculty of Chemistry, Division of High Energetic Materials, Noakowskiego 3, 00-664 Warsaw (Poland)

    2011-11-15

    Highlights: {yields} A novel catalyst H{sub 3}PO{sub 4}/MoO{sub 3}/SiO{sub 2} was characterized and used in nitration. {yields} On the surface domains of phosphomolybdic acid (HPM) are obtained. {yields} Dinitrotoluene is obtained with very high yield i.e. 96 wt.% in mild conditions. {yields} Dinitrochlorobenzene is obtained with only twelve-fold excess of nitric acid. {yields} It is sulfuric acid free and solvent free nitration of aromatic compounds. - Abstract: A new catalyst, H{sub 3}PO{sub 4}/MoO{sub 3}/SiO{sub 2}, was prepared by modification of MoO{sub 3}/SiO{sub 2} using phosphoric acid. The characterization of the catalyst was performed using Infrared and Raman Spectroscopy, potentiometric titration and nitrogen adsorption-desorption methods. Molybdenum oxides were identified along with phosphomolybdic acid and polymolybdates on the modified surface. The suitability of the catalysts for toluene and chlorobenzene nitration in continuous process was examined. Toluene is effectively nitrated to dinitrotoluene (DNT) in one-stage process (96 wt.% of DNT in the product) and in mild conditions i.e. at room temperature and only with ten-fold excess of nitric acid. In chlorobenzene nitration only twelve-fold excess of nitric acid is needed to obtain as high yield as 95 wt.%. Most importantly, the novel catalysts we have developed, provide the opportunity for sulfuric acid- free nitration of aromatic compounds.

  17. Single-molecule study of oxidative enzymatic deconstruction of cellulose.

    Science.gov (United States)

    Eibinger, Manuel; Sattelkow, Jürgen; Ganner, Thomas; Plank, Harald; Nidetzky, Bernd

    2017-10-12

    LPMO (lytic polysaccharide monooxygenase) represents a unique paradigm of cellulosic biomass degradation by an oxidative mechanism. Understanding the role of LPMO in deconstructing crystalline cellulose is fundamental to the enzyme's biological function and will help to specify the use of LPMO in biorefinery applications. Here we show with real-time atomic force microscopy that C1 and C4 oxidizing types of LPMO from Neurospora crassa (NcLPMO9F, NcLPMO9C) bind to nanocrystalline cellulose with high preference for the very same substrate surfaces that are also used by a processive cellulase (Trichoderma reesei CBH I) to move along during hydrolytic cellulose degradation. The bound LPMOs, however, are immobile during their adsorbed residence time ( ~ 1.0 min for NcLPMO9F) on cellulose. Treatment with LPMO resulted in fibrillation of crystalline cellulose and strongly ( ≥ 2-fold) enhanced the cellulase adsorption. It also increased enzyme turnover on the cellulose surface, thus boosting the hydrolytic conversion.Understanding the role of enzymes in biomass depolymerization is essential for the development of more efficient biorefineries. Here, the authors show by atomic force microscopy the real-time mechanism of cellulose deconstruction by lytic polysaccharide monooxygenases.

  18. TiO{sub 2} and TiO{sub 2}-SiO{sub 2} thin films and powders by one-step soft-solution method: Synthesis and characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Ennaoui, A.; Sankapal, B.R.; Skryshevsky, V.; Lux-Steiner, M.Ch. [Division Solar Energy Research, Department Heterogeneous Material Systems, Hahn-Meitner-Institut, Glienicker Strasse 100, 14109 Berlin (Germany)

    2006-06-15

    Simple soft-solution method has been developed to synthesize films and powders of TiO{sub 2} and mixed TiO{sub 2}-SiO{sub 2} at relatively low temperatures. This method is simple and inexpensive. Furthermore, reactor can be designed for large-scale applications as well as to produce large quantities of composite powders in a single step. For the preparation of TiO{sub 2}, we used aqueous acidic medium containing TiOSO{sub 4} and H{sub 2}O{sub 2}, which results in a peroxo-titanium precursor while colloidal SiO{sub 2} has been added to the precursor for the formation of TiO{sub 2}-SiO{sub 2}. Post annealing at 500{sup o}C is necessary to have anatase structure. Resulting films and powders were characterized by different techniques. TiO{sub 2} (anatase) phase with (101) preferred orientation has been obtained. Also in TiO{sub 2}-SiO{sub 2} mixed films and powders, TiO{sub 2} (anatase) phase was found. Fourier transform infrared spectroscopy (FTIR) results for TiO{sub 2} and mixed TiO{sub 2}-SiO{sub 2} films have been presented and discussed. The method developed in this paper allowed obtaining compact and homogeneous TiO{sub 2} films. These compact films are highly photoactive when TiO{sub 2} is used as photo anode in an photoelectrochemical cell. Nanoporous morphology is obtained when SiO{sub 2} colloids are added into the solution. (author)

  19. Point defects in electron-irradiated oxide single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Caulfield, K.J.; Cooper, R. [Univ. of Melbourne, Parkville, Victoria (Australia). Dept. of Chemistry; Boas, J.F. [Australian Radiation Lab., Yallambie, Victoria (Australia)

    1995-04-01

    Point defects have been produced in CaO, MgO, and {alpha}-Al{sub 2}O{sub 3} single crystals by electron irradiation, and thresholds for atomic displacement have been measured using time-resolved luminescence spectroscopy. Oxygen displacement energies of approximately 50 eV have been determined; however, a temperature-dependent threshold observed for an emission band in MgO may arise from a magnesium displacement. A 300-nm emission in {alpha}-Al{sub 2}O{sub 3} may be due to an F-center transition. Studies of radiative recombination kinetics are consistent with an electron-detrapping model.

  20. 1.54 μm Photoluminescence emission from Er-implanted SiO{sub 2} crystal and SiO{sub 2} glass

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shiling, E-mail: shilingli@sdu.edu.cn [Department of Opto-electronics and Information Engineering, School of Precision Instruments and Opto-electronics Engineering, Tianjin University, Tianjin 300072 (China); College of Physics and Engineering, Shandong Provincial Key Laboratory of Laser and Information Technology, Qufu Normal University, Qufu 273165 (China); Fu, Gang [School of Science, Shandong Jianzhu University, Jinan 250014 (China); Ye, Yongkai [College of Physics and Engineering, Shandong Provincial Key Laboratory of Laser and Information Technology, Qufu Normal University, Qufu 273165 (China)

    2013-07-15

    Er-doped materials are of great importance for application in optical communication. SiO{sub 2} crystal and silica glass have been implanted with 500 keV Er ions at a fluence of 3 × 10{sup 15} ions/cm{sup 2}, with the aim of incorporating the rare-earth dopant on an optically active site. Erbium concentration profiles were analyzed by Rutherford backscattering technology. Photoluminescence (PL) spectrometry studies were performed at room temperature and at 12 K. The characteristic photoluminescence of Er{sup 3+} around 1.54 μm is observed at room temperature in as-implanted SiO{sub 2} crystal and SiO{sub 2} glass. And the influence of annealing on the PL intensity is studied.

  1. Development of nano SiO{sub 2} incorporated nano zinc phosphate coatings on mild steel

    Energy Technology Data Exchange (ETDEWEB)

    Tamilselvi, M. [Department of Chemistry, Thiru Kolanjiappar Government Arts College, Virudhachalam 606001 (India); Kamaraj, P. [Department of Chemistry, SRM University, Kattankulathur 603203 (India); Arthanareeswari, M., E-mail: arthanareeswari@gmail.com [Department of Chemistry, SRM University, Kattankulathur 603203 (India); Devikala, S.; Selvi, J. Arockia [Department of Chemistry, SRM University, Kattankulathur 603203 (India)

    2015-03-30

    Highlights: • Nano SiO{sub 2} incorporated nano zinc phosphate coating on mild steel was developed. • Coatings showed enhanced corrosion resistance. • The nano SiO{sub 2} is adsorbed on mild steel surface and become nucleation sites. • The nano SiO{sub 2} accelerates the phosphating process. - Abstract: This paper reports the development of nano SiO{sub 2} incorporated nano zinc phosphate coatings on mild steel at low temperature for achieving better corrosion protection. A new formulation of phosphating bath at low temperature with nano SiO{sub 2} was attempted to explore the possibilities of development of nano zinc phosphate coatings on mild steel with improved corrosion resistance. The coatings developed were studied by Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Electrochemical measurements. Significant variation in the coating weight, morphology and corrosion resistance was observed as nano SiO{sub 2} concentrations varied from 0.5–4 g/L. The results showed that, the nano SiO{sub 2} in the phosphating solution changed the initial potential of the interface between mild steel substrate and phosphating solution and reduce the activation energy of the phosphating process, increase the nucleation sites and yielded zinc phosphate coatings of higher coating weight, greater surface coverage and enhanced corrosion resistance. Better corrosion resistance was observed for coatings derived from phosphating bath containing 1.5 g/L nano SiO{sub 2}. The new formulation reported in the present study was free from Ni or Mn salts and had very low concentration of sodium nitrite (0.4 g/L) as accelerator.

  2. Highly active surface-enhanced Raman scattering (SERS) substrates based on gold nanoparticles infiltrated into SiO{sub 2} inverse opals

    Energy Technology Data Exchange (ETDEWEB)

    Ankudze, Bright; Philip, Anish [Department of Chemistry, University of Eastern Finland, P.O. Box 111, F1-80101, Joensuu (Finland); Pakkanen, Tuula T., E-mail: Tuula.Pakkanen@uef.fi [Department of Chemistry, University of Eastern Finland, P.O. Box 111, F1-80101, Joensuu (Finland); Matikainen, Antti; Vahimaa, Pasi [Institute of Photonics, University of Eastern Finland, P.O. Box 111, F1-80101, Joensuu (Finland)

    2016-11-30

    Highlights: • SERS substrates prepared by infiltration of nanoparticles into SiO{sub 2} inverse opal. • The SERS substrate gives an enhancement factor of 10{sup 7} for 4-aminothiophenol. • The sensitivity of the substrate is mainly attributed to gold nanoparticle clusters. - Abstract: SiO{sub 2} inverse opal (IO) films with embedded gold nanoparticles (AuNPs) for surface-enhanced Raman scattering (SERS) application are reported. SiO{sub 2} IO films were loaded with AuNPs by a simple infiltration in a single cycle to form Au-SiO{sub 2} IOs. The optical property and the morphology of the Au-SiO{sub 2} IO substrates were characterized; it was observed that they retained the Bragg diffraction of SiO{sub 2} IO and the localized surface plasmon resonance (LSPR) of AuNPs. The SERS property of the Au-SiO{sub 2} IO substrates were studied with methylene blue (MB) and 4-aminothiophenol (4-ATP). The SERS enhancement factors were 10{sup 7} and 10{sup 6} for 4-ATP and MB, respectively. A low detection limit of 10{sup −10} M for 4-ATP was also obtained with the Au-SiO{sub 2} IO substrate. A relative standard deviation of 18.5% for the Raman signals intensity at 1077 cm{sup −1} for 4-ATP shows that the Au-SiO{sub 2} IO substrates have good signal reproducibility. The results of this study indicate that the Au-SiO{sub 2} IO substrates can be used in sensing and SERS applications.

  3. CO oxidation studies over supported noble metal catalysts and single crystals: A review

    Science.gov (United States)

    Boecker, Dirk; Gonzalez, Richard D.

    1987-01-01

    The catalytic oxidation of CO over noble metal catalysts is reviewed. Results obtained on supported noble metal catalysts and single crystals both at high pressures and under UHV conditions are compared. The underlying causes which result in surface instabilities and multiple steady-state oscillations are considered, in particular, the occurrence of hot spots. CO islands of reactivity, surface oxide formation and phase transformations under oscillatory conditions are discussed.

  4. Evidence for Single Metal Two Electron Oxidative Addition and Reductive Elimination at Uranium

    OpenAIRE

    Gardner, Benedict M; Kefalidis, Christos E; Lu, Erli; Patel, Dipti; Mcinnes, Eric; Tuna, Floriana; Wooles, Ashley; Maron, Laurent; Liddle, Stephen

    2017-01-01

    Reversible single-metal two-electron oxidative addition and reductive elimination are common fundamental reactions for transition metals that underpin major catalytic transformations. However, these reactions have never been observed together in the f-block because these metals exhibit irreversible one- or multi-electron oxidation or reduction reactions. Here, we report that azobenzene oxidises sterically and electronically unsaturated uranium(III) complexes to afford a uranium(V)-imido compl...

  5. Subattoampere current induced by single ions in silicon oxide layers of nonvolatile memory cells

    International Nuclear Information System (INIS)

    Cellere, G.; Paccagnella, A.; Larcher, L.; Visconti, A.; Bonanomi, M.

    2006-01-01

    A single ion impinging on a thin silicon dioxide layer generates a number of electron/hole pairs proportional to its linear energy transfer coefficient. Defects generated by recombination can act as a conductive path for electrons that cross the oxide barrier, thanks to a multitrap-assisted mechanism. We present data on the dependence of this phenomenon on the oxide thickness by using floating gate memory arrays. The tiny number of excess electrons stored in these devices allows for extremely high sensitivity, impossible with any direct measurement of oxide leakage current. Results are of particular interest for next generation devices

  6. Ordered Ag nanocluster structures by vapor deposition on pre-patterned SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, Satoshi; Ranjan, Mukesh; Heinig, Karl-Heinz; Facsko, Stefan; Smith, Roger, E-mail: s.numazawa@hzdr.de [Helmholtz-Zentrum Dresden Rossendorf (HZDR), Institut fuer Ionenstrahlphysik und Materialforschung, PO Box 510119, 01314 Dresden (Germany)

    2011-06-08

    Highly ordered Ag nanocluster structures have been grown on pre-patterned amorphous SiO{sub 2} surfaces by oblique angle physical vapor deposition at room temperature. Despite the small undulation of the rippled surface, the stripe-like Ag nanoclusters are very pronounced, reproducible and well separated. Computer modeling of the growth has been performed with a lattice-based kinetic Monte Carlo (KMC) method using a combination of a simplified inter-atomic potential and experimental transition barriers taken from the literature. An effective transition event classification method is introduced which allows a boost factor of several thousand compared to a traditional KMC approach, thus allowing experimental time scales to be modeled. The simulation predicts a low sticking probability for the arriving atoms, millisecond order lifetimes for single Ag adatoms and {approx}1 nm square surface migration ranges of Ag adatoms. It is also shown that metal nucleations can trigger even on defect free surfaces. The simulations give excellent reproduction of the experimentally observed nanocluster growth patterns. (fast track communication)

  7. Single Whole-Body Cryostimulation Procedure versus Single Dry Sauna Bath: Comparison of Oxidative Impact on Healthy Male Volunteers

    Directory of Open Access Journals (Sweden)

    Paweł Sutkowy

    2015-01-01

    Full Text Available Exposure to extreme heat and cold is one of the environmental factors whose action is precisely based on the mechanisms involving free radicals. Fluctuations in ambient temperature are among the agents that toughen the human organism. The goal of the study was to evaluate the impact of extremely high (dry sauna, DS and low (whole-body cryostimulation, WBC environmental temperatures on the oxidant-antioxidant equilibrium in the blood of healthy male subjects. The subjects performed a single DS bath (n=10; 26.2 ± 4.6 years and a single WBC procedure (n=15; 27.5 ± 3.1 years. In the subjects’ blood taken immediately before and 20 min after the interventions, the activity of superoxide dismutase (SOD, catalase (CAT, and glutathione peroxidase (GPx and the concentration of thiobarbituric acid reactive substances in erythrocytes (TBARSer and blood plasma (TBARSpl were determined. Single WBC and DS procedures induced an increase in the activity of SOD and GPx, as well as SOD and CAT, respectively. The SOD activity was higher after WBC than after DS. Extremely high and low temperatures probably induce the formation of reactive oxygen species in the organisms of healthy men and, therefore, disturb the oxidant-antioxidant balance.

  8. X-ray photoelectron spectroscopy studies on single crystalline β-FeSi{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Wei, E-mail: mao@nuclear.jp [The Micro Analysis Laboratory, Tandem Accelerator, The University Museum, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Udono, Haruhiko [Department of Electrical and Electronic Engineering, Ibaraki University, Hitachi, Ibaraki 316-8511 (Japan); Yamaguchi, Kenji [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-shirane, Tokai, Naka, Ibaraki 319-1195 (Japan); Terai, Takayuki [Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Matsuzaki, Hiroyuki [The Micro Analysis Laboratory, Tandem Accelerator, The University Museum, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2016-05-01

    In order to realize the photoluminescence of semiconducting β-FeSi{sub 2} homoepitaxial films, surface preparation of single crystalline β-FeSi{sub 2} is of critical importance. An atomically flat and clean substrate surface of β-FeSi{sub 2} was prepared by sputtering with 2 keV Ar{sup +} ions or by heating at 850 °C. The structure of the native surface oxide and the removal of this layer were investigated though X-ray photoelectron spectroscopy measurements. No significant deviation of the stoichiometry was detected in the surface region. Our results suggest that a surface prepared in this way is an eligible substrate for homoepitaxy of β-FeSi{sub 2}. - Highlights: • A clean surface of single crystalline (beta)-FeSi{sub 2} was prepared by Ar{sup +} sputtering or by heating. • The removal of surface oxide during the surface treatment is elucidated. • The native surface oxides are identified as SiO{sub 2} on top and SiO{sub x} as the inner layer. • There is no significant deviation of surface stoichiometry on the clean surface.

  9. Cooperative properties of single phases of complex oxide catalyst for oxidation of propylene to acrolein

    International Nuclear Information System (INIS)

    Orel, L.I.; Udalova, O.V.; Korchak, V.N.; Isaev, O.V.; Krylov, O.V.; Gershenzon, Yu.M.; Aptekar', E.L.

    1992-01-01

    Synergetic effect of increase of acrolein yield during propylene oxidation on mechanical mixture of (α + β)CoMoO 4 and MoO 3 , as well as CO and CO 2 yield on mixture of CoMoO 4 and Bi 2 O 3 ·2MoO 3 was revealed. It is shown that CoMoO 4 generates allyl radicals, desorption of these radicals to gaseous phase is not practically observed with MoO 3 , bismuth molybdates and Fe 2 O 3 · Fe 2 O 3 ·3MoO 3

  10. Formation of single domain magnetite by green rust oxidation promoted by microbial anaerobic nitrate-dependent iron oxidation

    Science.gov (United States)

    Miot, Jennyfer; Li, Jinhua; Benzerara, Karim; Sougrati, Moulay Tahar; Ona-Nguema, Georges; Bernard, Sylvain; Jumas, Jean-Claude; Guyot, François

    2014-08-01

    Biomineralization of magnetite is a central geomicrobiological process that might have played a primordial role over Earth’s history, possibly leaving traces of life in the geological record or controlling trace metal(loid)s and organic pollutants mobility in modern environments. Magnetite biomineralization has been attributed to two main microbial pathways to date (namely magnetotactic bacteria and dissimilatory iron-reducing bacteria). Here, we uncover a new route of magnetite biomineralization involving the anaerobic nitrate-reducing iron(II) oxidizing bacterium Acidovorax sp. strain BoFeN1. Using transmission electron microscopy, scanning transmission X-ray microscopy, transmission Mössbauer spectroscopy and rock magnetic analyses, this strain is shown to promote the transformation of hydroxychloride green rust in equilibrium with dissolved Fe(II) to (1) periplasmic lepidocrocite (γ-FeOOH) and (2) extracellular magnetite, thus leading to strong redox heterogeneities at the nanometer scale. On the one hand, lepidocrocite was associated with protein moieties and exhibited an anisotropic texture, with the elongated axis parallel to the cell wall. On the other hand, magnetite crystals exhibited grain sizes and magnetic properties consistent with stable single domain particles. By comparison, abiotic controls led to a very slow (4 months vs. 2 days in BoFeN1 cultures) and incomplete oxidation of hydroxychloride green rust towards magnetite. As this abiotic magnetite exhibited the same size and magnetic properties (stable single domain particles) as magnetite produced in BoFeN1 cultures, only the co-occurrence of textured Fe(III)-oxides and magnetite, associated with the persistence of organic carbon molecules, might constitute valuable biosignatures to be looked for in the geological record. Our results furthermore contribute to a more complex picture of Fe redox cycling in the environment, providing an additional process of Fe(II)-bearing phase

  11. Interface engineered carbon nanotubes with SiO{sub 2} for flexible infrared detectors

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhenlong [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Gao, Min, E-mail: mingao@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Pan, Taisong [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Wei, Xianhua [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang, Sichuan 621010 (China); Chen, Chonglin [Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249 (United States); Department of Physics and the Texas Center for Superconductivity, University of Houston, Houston, TX 77204 (United States); Lin, Yuan, E-mail: linyuan@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China)

    2017-08-15

    Highlights: • Interface engineered carbon nanotubes with SiO{sub 2} is used to construct a kind of flexible infrared detector. • The interface between the MWCNTs and SiO{sub 2} could enhance the IR response speed. • Detector based on the integrated interface of MWCNTs and SiO{sub 2} has successfully detected the movements of the human fingers. - Abstract: Nitrogen-doped/non-doped carbon nanotubes (CNTs) were integrated on SiO{sub 2}/Si and PMMA substrates for understanding the infrared sensing mechanisms. The nanotube structures on SiO{sub 2} substrates exhibit a much shorter response time (about 40 ms) than those directly on PMMA substrates (about 1200 ms), indicating the interface effects between CNTs and the substrates. The infrared responses for both structures show a linear relationship with the light power density even at the radiation power as low as 0.1 mW/mm{sup 2}. Moreover, a new concept flexible IR detector was designed and fabricated by transferring the CNTs/SiO{sub 2} structure onto the PMMA substrate, which exhibits both short response time (50 ms) and good flexibility. The successful detection of human finger movements indicates the practical applications of the CNT-based detectors for the detection of weak thermal or far infrared radiation.

  12. Oxide-apertured microcavity single-photon-emitting diodes-simultaneous confinement of current and light

    International Nuclear Information System (INIS)

    Ellis, David J P; Bennett, Anthony J; Dewhurst, Samuel J; Shields, Andrew J; Atkinson, Paola; Nicoll, Christine A; Ritchie, David A

    2008-01-01

    We report on the development of a generation of microcavity single-photon sources in which an aluminium oxide aperture provides simultaneous confinement of the injected current and the optical mode. The aperture is formed by the wet oxidation of an aluminium-rich AlGaAs layer. This approach allows a high quality cavity to be successfully integrated into an electrical device, from which enhanced photon emission is observed through the Purcell effect. The resulting source demonstrated an improved photon collection efficiency and was shown to operate at repetition rates in excess of 0.5 GHz.

  13. Analysis of the temperature dependence of the thermal conductivity of insulating single crystal oxides

    Directory of Open Access Journals (Sweden)

    E. Langenberg

    2016-10-01

    Full Text Available The temperature dependence of the thermal conductivity of 27 different single crystal oxides is reported from ≈20 K to 350 K. These crystals have been selected among the most common substrates for growing epitaxial thin-film oxides, spanning over a range of lattice parameters from ≈3.7 Å to ≈12.5 Å. Different contributions to the phonon relaxation time are discussed on the basis of the Debye model. This work provides a database for the selection of appropriate substrates for thin-film growth according to their desired thermal properties, for applications in which heat management is important.

  14. Facile synthesis of SiO{sub 2} nanoparticles for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Scano, A., E-mail: alescano80@tiscali.it; Pilloni, M., E-mail: alescano80@tiscali.it; Cabras, V., E-mail: alescano80@tiscali.it; Ennas, G. [Università di Cagliari, Dipartimento di Scienze Chimiche e Geologiche and Research Unit of the National Consortium of Materials Science and Technology (INSTM), Cittadella Universitaria di Monserrato- 09042 Monserrato (Canada) (Italy); Vazquez-Vazquez, C. [Departamento de Química Física, Facultad de Química, Universidad de Santiago de Compostela, Santiago de Compostela, 15782 Galicia (Spain)

    2014-10-21

    Silica nanoparticles (SiO{sub 2} NPs) for biomedical applications have been prepared by using a facile modified Stöber-synthesis. Potassium borohydride (KBH{sub 4}) has been introduced in the synthesis procedure in order to control NP size. Several samples have been prepared varying tetraethylorthosilicate (TEOS) concentration, and using different process conditions (temperature, reaction time and atmosphere). In order to study the influence of the process conditions on the NP size, morphology and properties, several characterization techniques were used. Size and morphology of the as-prepared SiO{sub 2} NPs have been studied by using Transmission Electron Microscope (TEM) and Dynamic Light Scattering (DLS) techniques. Structural characterization was carried out by X-ray powder diffraction. To investigate the SiO{sub 2} NP fluorescence emission properties the fluorescence spectroscopy was also used.

  15. Pattern formation in single-phase FAC. A stability analysis of an oxide layer

    Energy Technology Data Exchange (ETDEWEB)

    Zinemanas, Daniel [The Israel Electric Corp., Haifa (Israel). Dept. of Chemistry; Herszage, Amiel [The Israel Electric Corp., Haifa (Israel). Dept. of Energy Technologies Development

    2013-03-15

    Pattern formation is a salient characteristic of the flow-accelerated corrosion process, particularly in single-phase flow, where a typical ''orange peel'' surface texture is normally formed. The process of such pattern formation is, however, not well understood. In order to gain some insight into the role of the various processes and parameters involved in this process, a linear stability analysis of an oxide layer based on the Sanchez-Caldera model was performed. According to the results obtained in this study, it follows that the oxide layer is stable regarding perturbations of the oxide thickness or the reaction constant, but it is unstable in respect to perturbations of the mass transfer coefficient. These results suggest therefore that the flow, and not local surface in homogeneities, plays a central role in the pattern formation process. (orig.)

  16. Effect of nano SiO{sub 2} particles on the morphology and mechanical properties of POSS nanocomposite dental resins

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yizhi; Sun, Yi, E-mail: sunyi@hit.edu.cn; Zeng, Fanlin [Harbin Institute of Technology, Department of Astronautic Science and Mechanics (China); Xie, Weili, E-mail: xwl811@126.com [Harbin Medical University, Department of Stomatology (China); Liu, Yang [Harbin Stomatology Hospital (China); Geng, Lin [Harbin Institute of Technology, School of Materials Science and Engineering (China)

    2014-12-15

    Nanocomposite dental resins composed of polyhedral oligomeric silsesquioxane nanocomposite matrix and 0, 0.5,1, 1.5 and 2 wt% nano SiO{sub 2} as filler were prepared by light curing method. The nanocomposite resins were characterized by performing compressive, three-point flexure, nanoindentation and nanoscratch testings as well as optical microscopy and scanning electron microscope analysis. The effects of different nano SiO{sub 2} contents were studied on compressive strength, flexural strength, hardness and resistance of composite resin. From the mechanical results, it was found that nano SiO{sub 2} effectively enhanced the mechanical properties of the composite resins at low content. With the increase of the nano SiO{sub 2} content, the mechanical properties decreased. It was attributed to the content of nano SiO{sub 2} and dispersion of nanoparticles in matrix.

  17. Theoretical study of catalytic mechanism for single-site water oxidation process.

    Science.gov (United States)

    Lin, Xiangsong; Hu, Xiangqian; Concepcion, Javier J; Chen, Zuofeng; Liu, Shubin; Meyer, Thomas J; Yang, Weitao

    2012-09-25

    Water oxidation is a linchpin in solar fuels formation, and catalysis by single-site ruthenium complexes has generated significant interest in this area. Combining several theoretical tools, we have studied the entire catalytic cycle of water oxidation for a single-site catalyst starting with [Ru(II)(tpy)(bpm)(OH(2))](2+) (i.e., [Ru(II)-OH(2)](2+); tpy is 2,2':6',2''-terpyridine and bpm is 2,2'-bypyrimidine) as a representative example of a new class of single-site catalysts. The redox potentials and pK(a) calculations for the first two proton-coupled electron transfers (PCETs) from [Ru(II)-OH(2)](2+) to [Ru(IV) = O](2+) and the following electron-transfer process to [Ru(V) = O](3+) suggest that these processes can proceed readily in acidic or weakly basic conditions. The subsequent water splitting process involves two water molecules, [Ru(V) = O](3+) to generate [Ru(III)-OOH](2+), and H(3)O(+) with a low activation barrier (~10 kcal/mol). After the key O-O bond forming step in the single-site Ru catalysis, another PECT process oxidizes [Ru(III)-OOH](2+) to [Ru(IV)-OO](2+) when the pH is lower than 3.7. Two possible forms of [Ru(IV)-OO](2+), open and closed, can exist and interconvert with a low activation barrier (catalytic cycle. This understanding is helpful in the design of new catalysts for water oxidation.

  18. Pulmonary Responses of Sprague-Dawley Rats in Single Inhalation Exposure to Graphene Oxide Nanomaterials

    Directory of Open Access Journals (Sweden)

    Sung Gu Han

    2015-01-01

    Full Text Available Graphene is receiving increased attention due to its potential widespread applications in future. However, the health effects of graphene have not yet been well studied. Therefore, this study examined the pulmonary effects of graphene oxide using male Sprague-Dawley rats and a single 6-hour nose-only inhalation technique. Following the exposure, the rats were allowed to recover for 1 day, 7 days, or 14 days. A total of three groups were compared: control (fresh air, low concentration (0.46±0.06 mg/m3, and high concentration (3.76±0.24 mg/m3. The exposure to graphene oxide did not induce significant changes in the body weights, organ weights, and food consumption during the 14 days of recovery time. The microalbumin and lactate dehydrogenase levels in the bronchoalveolar lavage (BAL fluid were not significantly changed due to the exposure. Similarly, total cell count, macrophages, polymorphonuclear leukocytes, and lymphocytes were not significantly altered in the BAL fluid. Plus, the histopathological examination of the rat lungs only showed an uptake of graphene oxide in the alveolar macrophages of the high-concentration group. Therefore, these results demonstrate that the single inhalation exposure to graphene oxide induce minimal toxic responses in rat lungs at the concentrations and time points used in the present study.

  19. Selected oxidative stress parameters after single and repeated administration of octabromodiphenyl ether to rats

    Directory of Open Access Journals (Sweden)

    Elżbieta Bruchajzer

    2014-10-01

    Full Text Available Objectives: Octabromodiphenyl ether (OctaBDE was used as a flame retardant applied mostly in the manufacture of plastics utilized in the electrical and electronic industries. Owing to its long half-life and being regarded as an environmental pollutant, OctaBDE, like other polybrominated diphenyl ethers, has been classified as a persistent organic pollutant (POP. This study was carried out to assess the effects of oxidative stress (redox homeostasis induced in rats by OctaBDE. Material and Methods: Female Wistar rats exposed intragastrically to OctaBDE at single (25, 200 or 2000 mg/kg b.w., or repeated (0.4, 2, 8, 40 or 200 mg/kg/day doses during 7–28 days were used in the experiment. Selected oxidative stress parameters were determined in the liver and blood serum. Results: Administration (single or repeated of OctaBDE to rats resulted in the impaired redox homeostasis, as evidenced by the increased levels of reduced (GSH and oxidized (GSSG glutathione in the liver, the reduced total antioxidant status (TAS in serum and the increased concentration of malondialdehyde (MDA in the liver. After multiple doses of OctaBDE, elevated activity of glutathione transferase (GST in the liver was also noted. Conclusions: After repeated administration of OctaBDE at the lowest dose (0.4 mg/kg/day, changes were observed in the parameters (MDA, TAS, GSSG indicative of oxidative stress.

  20. Synthesis of metallic nanoparticles in SiO{sub 2} matrices; Sintesis de nanoparticulas metalicas en matrices de SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez W, C.; Mondragon G, G.; Perez H, R.; Mendoza A, D. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2004-07-01

    Metallic nanoparticles was synthesized in SiO{sub 2} matrices by means of a process of two stages. The first one proceeded via sol-gel, incorporating the metallic precursors to the reaction system before the solidification of the matrix. Later on, the samples underwent a thermal treatment in atmosphere of H{sub 2}, carrying out the reduction of the metals that finally formed to the nanoparticles. Then it was detected the presence of smaller nanoparticles than 20 nm, dispersed and with the property of being liberated easily of the matrix, conserving a free surface, chemically reactive and with response to external electromagnetic radiation. The system SiO{sub 2}-Pd showed an important thermoluminescent response. (Author)

  1. Crystal structure and optical spectra of LiLa{sub 9}(SiO{sub 4}){sub 6}O{sub 2} crystals activated with Er{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Bettinelli, Marco [Dipartimento Scientifico e Tecnologico, University of Verona and INSTM, UdR Verona, Ca Vignal, Strada Le Grazie 15, 37134 Verona (Italy)], E-mail: marco.bettinelli@univr.it; Speghini, Adolfo [Dipartimento di Scienze, Tecnologie e Mercati della Vite e de Vino, University of Verona and INSTM, Villa Lebrecht, San Floriano, 37029 Verona (Italy); Falcomer, Daniele [Dipartimento Scientifico e Tecnologico, University of Verona and INSTM, UdR Verona, Ca Vignal, Strada Le Grazie 15, 37134 Verona (Italy); Cavalli, Enrico; Calestani, Gianluca [Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica e Chimica Fisica, Universita di Parma, Viale G. P. Usberti 17/a, 43100 Parma (Italy); Quintanilla, Marta; Cantelar, Eugenio; Cusso, Fernando [Departamento de Fisica de los Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Madrid 28049 (Spain)

    2008-05-15

    LiLa{sub 9}(SiO{sub 4}){sub 6}O{sub 2} (LLS) crystals activated with Er{sup 3+} have been grown by the flux growth method. Their apatite structure has been characterized by single-crystal X-ray diffraction. The absorption and emission spectra have been measured in the visible and NIR regions. They are affected by a significant inhomogeneous broadening making these crystals interesting active media for tunable solid-state laser operation.

  2. Synthesis of Li{sub 2}SiO{sub 3} at low temperature; Sintesis de Li{sub 2}SiO{sub 3} a baja temperatura

    Energy Technology Data Exchange (ETDEWEB)

    Mondragon G, G. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)

    2007-07-01

    The main objective of this work is to develop a new synthesis method to obtain one of the more studied ceramics in this field Li{sub 2}SiO{sub 3}) in a simple and economic way using different solutions (urea and ammonium hydroxide). The particular objectives are first to prepare the Li{sub 2}SiO{sub 3} ceramic, by means of the use of the reaction conventional technique in solid state at temperatures between 800 and 900 C to compare it with the one proposed in this work and this way to observe the advantages that it would gives us the new method. Later on, the same one was synthesized lithium ceramic (Li{sub 2}SiO{sub 3}) by means of the new method at low temperature (between 80 and 90 C), using silicic acid and lithium hydroxide like precursory reagents and different solutions (urea and ammonium hydroxide) for the optimization in their synthesis. Finally, it was carried out the characterization of these materials by means of X-ray diffraction (XRD), electronic microscopes (SEM and TEM), nitrogen physisorption (method BET) and thermal gravimetric analysis (TGA) to observe the differences that exist among the conventional method and the proposed method and by this way to determine the advantages of the last method. (Author)

  3. Ag-decorated Fe{sub 3}O{sub 4}@SiO{sub 2} core-shell nanospheres: Seed-mediated growth preparation and their antibacterial activity during the consecutive recycling

    Energy Technology Data Exchange (ETDEWEB)

    Li, Miaomiao; Wu, Wenjie [College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004 (China); Qiao, Ru, E-mail: qiaoru@zjnu.cn [College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004 (China); Tan, Linxiang [College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004 (China); Li, Zhengquan [Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004 (China); Zhang, Yong [College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004 (China); Department of Biomedical Engineering, National University of Singapore 117575 (Singapore)

    2016-08-15

    We demonstrated a seed-mediated growth approach to synthesize Ag nanoparticles-decorated Fe{sub 3}O{sub 4}@SiO{sub 2} core-shell nanospheres without use of surface functionalization. The particle size and decoration density of the immobilized Ag nanoparticles on SiO{sub 2} surface were tunable by adjusting the added AgNO{sub 3} concentration and the alternating repetition times in seed-mediated growth procedure. The as-prepared Ag-decorated Fe{sub 3}O{sub 4}@SiO{sub 2} nanospheres exhibited excellent antibacterial activities against Escherichia coli, Bacillus subtilis and Candida albicans, in which the minimum inhibitory concentration were 12.5 μg mL{sup −1}, 50 μg mL{sup −1} and 50 μg mL{sup −1}, respectively. It is speculated that their antibacterial activity is attributed to both the interaction of released Ag ions with the functional groups of vital enzymes and proteins and the strong oxidation of reactive oxygen species generated under the action of photoinduced electrons in Ag nanoparticles. Besides studying their antibacterial mechanism, we also investigated the variation of antibacterial activity of these heterostructured nanospheres during the consecutive magnetic separation and recycling. It shows that the magnetic antibacterial agent could be reused and its activity remained stable even after nine cycles, which enable it to be promisingly applied in biomedical areas. - Highlights: • Ag-decorated Fe{sub 3}O{sub 4}@SiO{sub 2} were synthesized via a seed-mediated growth method. • The core-shell heterostructures exhibited excellent antibacterial activity. • The activity was attributed to the effect of released Ag{sup +} with ROS oxidation. • The antibacterial agent was reused during magnetic separation and recycling.

  4. Photocatalytic activity of the binary composite CeO{sub 2}/SiO{sub 2} for degradation of dye

    Energy Technology Data Exchange (ETDEWEB)

    Phanichphant, Sukon [Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Nakaruk, Auppatham [Department of Industrial Engineering, Faculty of Engineering, Naresuan University, Phitsanulok 65000 (Thailand); Centre of Excellence for Innovation and Technology for Water Treatment, Naresuan University, Phitsanulok 65000 (Thailand); Channei, Duangdao, E-mail: duangdaoc@nu.ac.th [Department of Chemistry, Faculty of Science, Naresuan University, Phitsanulok 65000 (Thailand); Research Center for Academic Excellence in Petroleum, Petrochemicals and Advanced Materials, Naresuan University, Phitsanulok 65000 (Thailand)

    2016-11-30

    Highlights: • The enhanced photocatalytic activity of the CeO{sub 2}/SiO{sub 2} composite can be explained by the presence of the SiO{sub 2} adsorbent, which effectively increased the surface area of the CeO{sub 2}. • The increased surface area of CeO{sub 2} should be helpful to facilitate more effective adsorption sites, which enhances the photocatalytic degradation of organic pollutant significantly. • SiO{sub 2} modification is effective in separating the photogenerated electrons and holes, which is of great importance for photocatalytic activity. • SiO{sub 2} acted as a carrier for CeO{sub 2} attachment and avoided the agglomeration of CeO{sub 2} particles. - Abstract: In this study, CeO{sub 2} photocatalyst was modified by composite with SiO{sub 2} to increase efficiency and improve photocatalytic activity. The as-prepared SiO{sub 2} particles have been incorporated into the precursor mixture of CeO{sub 2} by homogeneous precipitation and subsequent calcination process. The phase compositions of CeO{sub 2} before and after compositing with SiO{sub 2} were identified by X-ray diffraction (XRD). The morphology and particle size of CeO{sub 2}/SiO{sub 2} composite was analyzed by high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). The results showed SiO{sub 2} spheres with the particle size approximately 100–120 nm, and a uniform layer of CeO{sub 2} nanoparticles with a diameter of about 5–7 nm that were fully composite to the surfaces of SiO{sub 2}. The X-ray photoelectron spectroscopy (XPS) technique was carried out in order to characterize the change in valence state and composite characteristic by shifted peaks of binding energies. The photocatalytic activity was studied through the degradation of Rhodamine B in aqueous solution under visible light exposure. The highest photocatalytic efficiency of CeO{sub 2}/SiO{sub 2} composite was also obtained. To explain the high photocatalytic

  5. Single-Site Palladium(II) Catalyst for Oxidative Heck Reaction: Catalytic Performance and Kinetic Investigations

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Hui; Li, Mengyang; Zhang, Guanghui; Gallagher, James R.; Huang, Zhiliang; Sun, Yu; Luo, Zhong; Chen, Hongzhong; Miller, Jeffrey T.; Zou, Ruqiang; Lei, Aiwen; Zhao, Yanli

    2015-01-01

    ABSTRACT: The development of organometallic single-site catalysts (SSCs) has inspired the designs of new heterogeneous catalysts with high efficiency. Nevertheless, the application of SSCs in certain modern organic reactions, such as C-C bond formation reactions, has still been less investigated. In this study, a single-site Pd(II) catalyst was developed, where 2,2'-bipyridine-grafted periodic mesoporous organosilica (PMO) was employed as the support of a Pd(II) complex. The overall performance of the single-site Pd(II) catalyst in the oxidative Heck reaction was then investigated. The investigation results show that the catalyst displays over 99% selectivity for the product formation with high reaction yield. Kinetic profiles further confirm its high catalytic efficiency, showing that the rate constant is nearly 40 times higher than that for the free Pd(II) salt. X-ray absorption spectroscopy reveals that the catalyst has remarkable lifetime and recyclability.

  6. Metal (Hydr)oxides@Polymer Core-Shell Strategy to Metal Single-Atom Materials.

    Science.gov (United States)

    Zhang, Maolin; Wang, Yang-Gang; Chen, Wenxing; Dong, Juncai; Zheng, Lirong; Luo, Jun; Wan, Jiawei; Tian, Shubo; Cheong, Weng-Chon; Wang, Dingsheng; Li, Yadong

    2017-08-16

    Preparing metal single-atom materials is currently attracting tremendous attention and remains a significant challenge. Herein, we report a novel core-shell strategy to synthesize single-atom materials. In this strategy, metal hydroxides or oxides are coated with polymers, followed by high-temperature pyrolysis and acid leaching, metal single atoms are anchored on the inner wall of hollow nitrogen-doped carbon (CN) materials. By changing metal precursors or polymers, we demonstrate the successful synthesis of different metal single atoms dispersed on CN materials (SA-M/CN, M = Fe, Co, Ni, Mn, FeCo, FeNi, etc.). Interestingly, the obtained SA-Fe/CN exhibits much higher catalytic activity for hydroxylation of benzene to phenol than Fe nanoparticles/CN (45% vs 5% benzene conversion). First-principle calculations further reveal that the high reactivity originates from the easier formation of activated oxygen species at the single Fe site. Our methodology provides a convenient route to prepare a variety of metal single-atom materials representing a new class of catalysts.

  7. Electron beam guiding by grooved SiO{sub 2} parallel plates without energy loss

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Yingli; Yu, Deyang, E-mail: d.yu@impcas.ac.cn; Liu, Junliang; Zhang, Mingwu; Yang, Bian; Zhang, Yuezhao; Cai, Xiaohong [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2015-12-21

    Using a pair of grooved SiO{sub 2} parallel plates, stably guided electron beams were obtained without energy loss at 800–2000 eV. This shows that the transmitted electrons are guided by a self-organized repulsive electric field, paving the way for a self-adaptive manipulation of electron beams.

  8. Single-step synthesis of PtRu/N-doped graphene for methanol electrocatalytic oxidation

    International Nuclear Information System (INIS)

    Xu, Xiao; Zhou, Yingke; Lu, Jiming; Tian, Xiaohui; Zhu, Hongxi; Liu, Jiangbo

    2014-01-01

    In this work, a single-step route was applied to achieve the reduction of graphene oxide, functional doping of graphene with nitrogen, and deposition of well-dispersed PtRu alloy nanoparticles on the doped graphene simultaneously in the solvent mixture of ethylene glycol and N-methyl-2-pyrrolidone. Transmission electron microscopy, X-ray powder diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy were used to characterize the morphology and microstructure, while cyclic voltammetry, chronoamperometry and electrochemical impedance techniques were carried out to evaluate the electrocatalytic methanol oxidation activity and durability of the obtained PtRu/nitrogen-doped graphene catalysts. Compared to undoped PtRu/graphene, the nitrogen-doped PtRu/graphene catalyst presented better particle size distribution and improved activity and durability of methanol electrocatalytic oxidation, which could be further improved by optimization of the reaction time, temperature, as well as the composition of the reaction medium. The convenient single-step synthesis process for the PtRu/nitrogen-doped graphene catalysts is promising for the potential application of direct methanol fuel cells

  9. Evidence for single metal two electron oxidative addition and reductive elimination at uranium.

    Science.gov (United States)

    Gardner, Benedict M; Kefalidis, Christos E; Lu, Erli; Patel, Dipti; McInnes, Eric J L; Tuna, Floriana; Wooles, Ashley J; Maron, Laurent; Liddle, Stephen T

    2017-12-01

    Reversible single-metal two-electron oxidative addition and reductive elimination are common fundamental reactions for transition metals that underpin major catalytic transformations. However, these reactions have never been observed together in the f-block because these metals exhibit irreversible one- or multi-electron oxidation or reduction reactions. Here we report that azobenzene oxidises sterically and electronically unsaturated uranium(III) complexes to afford a uranium(V)-imido complex in a reaction that satisfies all criteria of a single-metal two-electron oxidative addition. Thermolysis of this complex promotes extrusion of azobenzene, where H-/D-isotopic labelling finds no isotopomer cross-over and the non-reactivity of a nitrene-trap suggests that nitrenes are not generated and thus a reductive elimination has occurred. Though not optimally balanced in this case, this work presents evidence that classical d-block redox chemistry can be performed reversibly by f-block metals, and that uranium can thus mimic elementary transition metal reactivity, which may lead to the discovery of new f-block catalysis.

  10. Effects of thermal treatment on infrared optical properties of SiO{sub 2} films on Si Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Yiqin, E-mail: jiyiqin@gmail.com [National Key Laboratory of Science and Technology on Tunable Laser, Institute of Optical-electronics, Harbin Institute of Technology, Harbin, 150080 (China); Tianjin Key Laboratory of Optical Thin Film, Tianjin Jinhang Institute of Technical Physics, Tianjin 300192 (China); Jiang, Yugang [Tianjin Key Laboratory of Optical Thin Film, Tianjin Jinhang Institute of Technical Physics, Tianjin 300192 (China); Key Laboratory of Advanced Micro-structure Materials, Ministry of Education, Department of Physics, Tongji University, Shanghai, 200092 (China); Liu, Huasong; Wang, Lishuan; Liu, Dandan; Jiang, Chenghui [Tianjin Key Laboratory of Optical Thin Film, Tianjin Jinhang Institute of Technical Physics, Tianjin 300192 (China); Fan, Rongwei; Chen, Deying [National Key Laboratory of Science and Technology on Tunable Laser, Institute of Optical-electronics, Harbin Institute of Technology, Harbin, 150080 (China)

    2013-10-31

    The effects of thermal treatment on infrared optical properties of SiO{sub 2} films on Si substrates by ion beam sputtering technology were investigated. Complex refractive index of SiO{sub 2} films was calculated from Fourier transform infrared transmission spectrum from 400 to 4000 cm{sup −1}. Absorption band properties associated with Si-O-Si stretching, bending, rocking mode at about 1080 cm{sup −1}, 816 cm{sup −1}, 460 cm{sup −1} were analyzed. With the increase of thermal annealing temperature, the absorption peak with Si-O-Si stretching, rocking mode shift to long wave number, but the bending mode shifts to short. After thermal treatment, the infrared optical constants are close to the value of the more stabilized thermal grown SiO{sub 2}. So, it can be concluded that the structure of Si-O-Si network in SiO{sub 2} films deposited on Si was modified to the stable structure of thermal grown SiO{sub 2}. - Highlights: • Effects of annealing on IR optical properties of SiO{sub 2} films are achieved. • Complex dielectric functions of SiO{sub 2} films in the IR wave band are calculated. • Absorption bands properties with three modes are analyzed with thermal treatment.

  11. Electrochemistry and determination of epinephrine using a mesoporous Al-incorporated SiO{sub 2} modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Zeng Yanhong; Yang Jinquan [Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China); Wu Kangbing [Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China)], E-mail: kbwu@mail.hust.edu.cn

    2008-05-30

    The potential application of Al-incorporated mesoporous SiO{sub 2} (denoted as Al-MCM-41) in electrochemistry as a novel electrode material was investigated. The peak currents of K{sub 3}[Fe(CN){sub 6}] remarkably increase and the peak potential separation obviously decreases at the mesoporous Al-MCM-41 modified carbon paste electrode (CPE). These phenomena suggest that the mesoporous Al-MCM-41 modified CPE possesses larger electrode area and electron transfer rate constant. Furthermore, the electrochemical behavior of epinephrine (EP) was investigated in different supporting electrolytes such as 0.01 mol L{sup -1} HClO{sub 4} and pH 7.0 phosphate buffer. It is found that the mesoporous Al-MCM-41 modified CPE exhibits catalytic ability to the oxidation of EP due to remarkable peak current enhancement and negative shift of peak potential. The electrochemical oxidation mechanism was also discussed. Finally, a novel electrochemical method was proposed for the determination of EP, which used to determine EP in urine samples.

  12. Electrochemistry and determination of epinephrine using a mesoporous Al-incorporated SiO{sub 2} modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Yanhong; Yang, Jinquan; Wu, Kangbing [Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2008-05-30

    The potential application of Al-incorporated mesoporous SiO{sub 2} (denoted as Al-MCM-41) in electrochemistry as a novel electrode material was investigated. The peak currents of K{sub 3}[Fe(CN){sub 6}] remarkably increase and the peak potential separation obviously decreases at the mesoporous Al-MCM-41 modified carbon paste electrode (CPE). These phenomena suggest that the mesoporous Al-MCM-41 modified CPE possesses larger electrode area and electron transfer rate constant. Furthermore, the electrochemical behavior of epinephrine (EP) was investigated in different supporting electrolytes such as 0.01 mol L{sup -1} HClO{sub 4} and pH 7.0 phosphate buffer. It is found that the mesoporous Al-MCM-41 modified CPE exhibits catalytic ability to the oxidation of EP due to remarkable peak current enhancement and negative shift of peak potential. The electrochemical oxidation mechanism was also discussed. Finally, a novel electrochemical method was proposed for the determination of EP, which used to determine EP in urine samples. (author)

  13. Aeration Strategies To Mitigate Nitrous Oxide Emissions from Single-Stage Nitritation/Anammox Reactors

    DEFF Research Database (Denmark)

    Domingo Felez, Carlos; Mutlu, A. Gizem; Jensen, Marlene Mark

    2014-01-01

    Autotrophic nitrogen removal is regarded as a resource efficient process to manage nitrogen-rich residual streams. However, nitrous oxide emissions of these processes are poorly documented and strategies to mitigate emissions unknown. In this study, two sequencing batch reactors performing single......-stage nitritation/anammox were operated under different aeration strategies, gradually adjusted over six months. At constant but limiting oxygen loading, synthetic reject water was fed (0.75g-N/L.d) and high nitrogen removal efficiencies (83 +/- 5 and 88 +/- 2%) obtained. Dynamics of liquid phase nitrous (N2O......) and nitric oxide (NO) concentrations were monitored and N2O emissions calculated. Significant decreases in N2O emissions were obtained when the frequency of aeration was increased while maintaining a constant air flow rate (from >6 to 1.7% Delta N2O/Delta TN). However, no significant effect on the emissions...

  14. Single crystal cupric oxide nanowires: Length- and density-controlled growth and gas-sensing characteristics

    Science.gov (United States)

    Duc, Le Duy; Le, Dang Thi Thanh; Duy, Nguyen Van; Hoa, Nguyen Duc; Hieu, Nguyen Van

    2014-04-01

    Nanowire structured p-type CuO semiconductor is a promising material for gas-sensing applications because of its unique electrical and optical properties. In this study, we demonstrate the length and density controlled synthesis of single crystal CuO nanowires (CuO NWs) by a simple and convenient thermal oxidation of high-purity copper foils in ambient atmosphere. The density and length of the CuO NWs are controlled by varying the oxidation temperature and heating duration to investigate their growth mechanism. As-synthesized materials are characterized by different techniques, such as X-ray diffraction, field emission-scanning electron microscopy, and high-resolution transmission electron microscopy. The gas-sensing characteristics of the CuO NWs are tested using hydrogen and ethanol gases. The results show that the CuO NWs could potentially sense hydrogen and ethanol gases given a working temperature of 400 °C.

  15. Synthesis of highly monodispersed teardrop-shaped core–shell SiO{sub 2}/TiO{sub 2} nanoparticles and their photocatalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Lihong; Zhou, Yifeng, E-mail: yifengzhou@126.com; Nie, Wangyan; Song, Linyong; Chen, Pengpeng, E-mail: chenpp@ahu.edu.cn

    2015-10-01

    Graphical abstract: - Highlights: • Uniform chitosan coated magnetic mesoporous silica nanoparticles (CMMSNs) were successfully synthesized. • The CMMSNs were applied to highly efficient methylene blue (MB) dyes removal, and the saturated adsorption capacity of MB was 43.03 mg/g. • The MB adsorption kinetic and adsorption isotherm analysis were studied. • The CMMSNs had a saturation magnetization of 12.6 emu/g and could be easily separated by a magnet after dye adsorption. - Abstract: In this study, teardrop-shaped SiO{sub 2}/TiO{sub 2} nanoparticles (TST-NPs) with core–shell structure were fabricated from tetraethoxysilane (TEOS) and tetrabutyl titanate (TBT) by sol–gel method. And these nanoparticles were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and UV–vis spectroscopy. Photocatalytic activity of teardrop-shaped SiO{sub 2}/TiO{sub 2} nanoparticles after calcination (CST-NPs) was studied towards degradation of methylene blue under sunlight irradiation. The result showed that CST-NPs possessed good photocatalytic activity. The photocatalytic mechanism was also studied by adding different capture agent. Results showed that addition of 0.003 M of I{sup −} decreased the degradation of MB more than same amount of Ag{sup +}, indicating that the photogenerated holes may play a more essential role than photoinjected electrons in the oxidation of MB.

  16. High fluence swift heavy ion structure modification of the SiO{sub 2}/Si interface and gate insulator in 65 nm MOSFETs

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yao [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Lab of Microelectronics Sichuan Province, Sichuan University, Chengdu, Sichuan 610064 (China); College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan 610064 (China); Gao, Bo, E-mail: gaobo@scu.edu.cn [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Lab of Microelectronics Sichuan Province, Sichuan University, Chengdu, Sichuan 610064 (China); College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan 610064 (China); Gong, Min [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Lab of Microelectronics Sichuan Province, Sichuan University, Chengdu, Sichuan 610064 (China); College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan 610064 (China); Willis, Maureen [College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan 610064 (China); Yang, Zhimei [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Lab of Microelectronics Sichuan Province, Sichuan University, Chengdu, Sichuan 610064 (China); Guan, Mingyue [College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan 610064 (China); Li, Yun [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Lab of Microelectronics Sichuan Province, Sichuan University, Chengdu, Sichuan 610064 (China); College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan 610064 (China)

    2017-04-01

    In this work, a study of the structure modification, induced by high fluence swift heavy ion radiation, of the SiO{sub 2}/Si structures and gate oxide interface in commercial 65 nm MOSFETs is performed. A key and novel point in this study is the specific use of the transmission electron microscopy (TEM) technique instead of the conventional atomic force microscope (AFM) or scanning electron microscope (SEM) techniques which are typically performed following the chemical etching of the sample to observe the changes in the structure. Using this method we show that after radiation, the appearance of a clearly visible thin layer between the SiO{sub 2} and Si is observed presenting as a variation in the TEM intensity at the interface of the two materials. Through measuring the EDX line scans we reveal that the Si:O ratio changed and that this change can be attributed to the migration of the Si towards interface after the Si-O bond is destroyed by the swift heavy ions. For the 65 nm MOSFET sample, the silicon substrate, the SiON insulator and the poly-silicon gate interfaces become blurred under the same irradiation conditions.

  17. Wannier–Stark electro-optical effect, quasi-guided and photonic modes in 2D macroporous silicon structures with SiO{sub 2} coatings

    Energy Technology Data Exchange (ETDEWEB)

    Karachevtseva, L., E-mail: lakar@isp.kiev.ua [Ningbo University of Technology, No. 55-155 Cui Bai Road, Ningbo 315016 (China); V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, 41 Nauky Pr., 03028 Kyiv (Ukraine); Goltviansky, Yu., E-mail: ecoflam@voliacable.com [V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, 41 Nauky Pr., 03028 Kyiv (Ukraine); Sapelnikova, O., E-mail: e_kolesnik84@mail.ru [V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, 41 Nauky Pr., 03028 Kyiv (Ukraine); Lytvynenko, O., E-mail: lytvole@gmail.com [V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, 41 Nauky Pr., 03028 Kyiv (Ukraine); Stronska, O., E-mail: yaschichek@ukr.net [V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, 41 Nauky Pr., 03028 Kyiv (Ukraine); Bo, Wang, E-mail: bo305@hotmail.com [Ningbo University of Technology, No. 55-155 Cui Bai Road, Ningbo 315016 (China); Kartel, M., E-mail: nikar@kartel.kiev.ua [Ningbo University of Technology, No. 55-155 Cui Bai Road, Ningbo 315016 (China)

    2016-12-01

    Highlights: • The IR absorption spectra of oxidized macroporous silicon were studied. • The Wannier–Stark electro-optical effect on Si-SiO{sub 2} boundary was confirmed. • An additional electric field of quasi-guided optical modes was evaluated. • The photonic modes and band gaps were measured as peculiarities in absorption spectra. - Abstract: Opportunities to enhance the properties of structured surfaces were demonstrated on 2D macroporous silicon structures with SiO{sub 2} coatings. We investigated the IR light absorption oscillations in macroporous silicon structures with SiO2 coatings 0–800 nm thick. The Wannier–Stark electro-optical effect due to strong electric field on Si-SiO{sub 2}boundary and an additional electric field of quasi-guided optical modes were taken into account. The photonic modes and band gaps were also considered as peculiarities in absorbance spectra of macroporous silicon structures with a thick SiO{sub 2} coating. The photonic modes do not coincide with the quasi-guided modes in the silicon matrix and do not appear in absorption spectra of 2D macroporous silicon structures with surface nanocrystals.

  18. Sorption kinetics of cesium on ZrO{sub 2} and ZrO{sub 2}-SiO{sub 2}-TiO{sub 2} microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Tel, H.; Altas, Y.; Guer, F.; Ugur, A. [Ege Univ., Inst. of Nuclear Sciences, Bornova-Izmir (Turkey)

    2010-07-01

    ZrO{sub 2} and ZrO{sub 2}-SiO{sub 2}-TiO{sub 2} (with 1:1:1 mol ratio) microspheres have been prepared by the sol-gel method and characterized to study the sorption kinetics of cesium. The effect of pH on the adsorption capacity was determined for both type sorbents and the maximum adsorption percentage of cesium was observed at pH 10. To elucidate the kinetics of the ion-exchange reaction on pure and ternary oxide microspheres, the isotopic exchange rates of cesium ions between both types of sorbent microspheres and aqueous solution were measured radiochemically and compared with each other. The diffusion coefficients of Cs{sup +} ion for ZrO{sub 2} and ZrO{sub 2}-SiO{sub 2}-TiO{sub 2} sorbent microspheres at pH 10 were calculated as 3.648 x 10{sup -8} m{sup 2}s{sup -1} and 6.383 x 10{sup -8} m{sup 2}s{sup -1}, respectively, under particle diffusion controlled conditions. (orig.)

  19. Modification of erbium photoluminescence decay rate due to ITO layers on thin films of SiO{sub 2}:Er doped with Si-nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Wojdak, M., E-mail: m.wojdak@ucl.ac.uk [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom); Jayatilleka, H. [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom); Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Toronto, Ontario, Canada M5S 3G4 (Canada); Shah, M. [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom); Kenyon, A.J., E-mail: t.kenyon@ucl.ac.uk [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom); Gourbilleau, F.; Rizk, R. [Centre de Recherche sur les Ions, les Matériaux et la Photonique (CIMAP), ENSICAEN, CNRS, CEA/IRAMIS, Université de Caen, 14050 CAEN cedex (France)

    2013-04-15

    During the fabrication of MOS light emitting devices, the thin film of active material is usually characterized by photoluminescence measurements before electrical contacts are deposited. However, the presence of a conductive contact layer can alter the luminescent properties of the active material. The local optical density of states changes due to the proximity of luminescent species to the interface with the conductive medium (the top electrode), and this modifies the radiative rate of luminescent centers within the active layer. In this paper we report enhancement of the observed erbium photoluminescence rate after deposition of indium tin oxide contacts on thin films of SiO{sub 2}:Er containing silicon nanoclusters, and relate this to Purcell enhancement of the erbium radiative rate. -- Highlights: ► We studied photoluminescence of Er in SiO{sub 2} thin films doped with Si nanoclusters. ► Presence of ITO layer on the top enhances photoluminescence decay rate of Er. ► The effect depends on the thickness of active film. ► Radiative rate change in proximity of ITO layer was calculated theoretically. ► The calculation results are compared with the experiment and discussed.

  20. Effect of Eu/sup 3 +/ on the formation of color centers by the UV irradiation of a Na/sub 2/O X 3SiO/sub 2/ glass

    Energy Technology Data Exchange (ETDEWEB)

    Abruzov, V.I.; Elerts, M.A.; Tolstoi, M.N.

    1986-07-01

    The authors investigate the nature of the 4.1-eV band to color centers (CC) of an electron or hole type, and determine the quantitative characteristics of the hole CC in a reliable, experimental model glass of the composition Na/sub 2/O X 3SiO/sub 2/. In particular, the authors studied very pure glass of the composition 75 mole% of SiO/sub 2/ and 25 mole% of Na/sub 2/O without an activator and also with 0.5 parts by weight of Eu/sub 2/O/sub 3/ (added to 100 parts of glass), melted under oxidizing conditions. It was found that when a Na/sub 2/O X 3SiO/sub 2/ glass containing Eu/sup 3 +/ is irradiated by UV light in the region of the fundamental absorption edge of the matrix, some of the Eu/sup 3 +/ is reduced to Eu/sup 2 +/ and hole color centers are formed. In the IA spectrum of such a glass there are no bands of electron CC. It is shown that the IA band at 4.1 eV in the glass studied has a hole nature.

  1. Theoretical study on the photocatalytic properties of graphene oxide with single Au atom adsorption

    Science.gov (United States)

    Ju, Lin; Dai, Ying; Wei, Wei; Li, Mengmeng; Jin, Cui; Huang, Baibiao

    2018-03-01

    The photocatalytic properties of graphene oxide (GO) with single Au atom adsorption are studied via the first-principles calculations based on the density functional theory. The present study addresses the origin of enhancement in photocatalytic efficiency of GO derived from single Au atom depositing. Compared with the clean one, the work function of the single Au atom adsorbed GO is lowered due to the charge transfer from Au to GO, indicating enhanced surface activity. The Au atom plays as an electron trapping center and a mediating role in charge transfer from photon excited GO to target species. The photogenerated electron-hole pairs can be separated effectively. For the GO configuration with atomic Au dispersion, there are some states introduced in the band gap, which are predominantly composed of Au 6s states. Through the in-gap state, the photo-generated electron transfer from the valence band of clean GO to the conductive band more easily. In addition, the reduction of the gap in the system is also presented in the current work, which indicates that the single Au atom adsorption improves light absorption for the GO based photocatalyst. These theoretical results are valuable for the future applications of GO materials as photocatalyst for water splitting.

  2. Single crystal growth and optical properties of a transparent perovskite oxide LaInO3

    Science.gov (United States)

    Jang, Dong Hyun; Lee, Woong-Jhae; Sohn, Egon; Kim, Hyung Joon; Seo, Dongmin; Park, Ju-Young; Choi, E. J.; Kim, Kee Hoon

    2017-03-01

    Transparent LaInO3 single crystals have been grown using the optical floating zone method. Optimal growth, resulting in the highest optical transparency and best crystallinity, has been found at a growth speed of 15 mm/h and an O2 gas pressure of 10 bar. Under these conditions, single crystals as large as ˜4 × 4 mm2 have been obtained. Chemical compositions and structural analyses reveal that the resulting LaInO3 single crystal is stoichiometric without any impurity phase and forms an orthorhombic perovskite structure. Optical transmission spectra exhibit multiple optical transitions in a wide spectral range (0.5-4.2 eV). Although the main optical absorption occurs at ˜4.13 eV, weak absorption starts to develop from ˜1.4 eV, in agreement with an activation energy of ˜0.7 eV derived from electrical resistivity measurements. The dielectric constant ɛ is found to be 23.7 at room temperature. This LaInO3 single crystal can be used as a transparent perovskite substrate for growing oxide semiconductors with lattice constants close to ˜4.12 Å, such as doped BaSnO3.

  3. A single acute hepatotoxic dose of CCl4 causes oxidative stress in the rat brain

    Directory of Open Access Journals (Sweden)

    K.R. Ritesh

    2015-01-01

    Full Text Available Carbon tetrachloride (CCl4, a hepatotoxic agent is widely used to study the toxic mechanisms in experimental animals. We have investigated whether oxidative stress is induced in the brain at a single hepatotoxic dosage (1 ml/kg bw of CCl4. Increased lipid peroxidation (LPO, protein carbonyls (PC content and glutathione (GSH depletion were observed in the brain regions of rats treated with CCl4 which was higher than that of liver. A drastic reduction in the activity of glutathione-S-transferase (GST was seen in the brain regions which was higher than that of liver. Similarly, activities of glutathione peroxidase (GPx, glutathione reductase (GR, superoxide dismutase (SOD, catalase (CAT, NADH- and NADPH-dehydrogenase were reduced in the brain regions similar to that of liver. Higher induction of oxidative stress in the brain compared to that of liver implies vulnerability of the brain for CCl4 neurotoxicity. Our study shows that a single hepatotoxic dose of CCl4 is equally neurotoxic to rats.

  4. Growth of cadmium oxide whiskers on cadmium sulphide single crystals with copper as growth activator

    International Nuclear Information System (INIS)

    Koparanova, N.; Simov, S.

    1985-01-01

    Some results on the growth and morphology of cadmium oxide whiskers, obtained on cadmium sulphide single crystals with copper as a growth activator, are presented in this work. Cadmium oxide whiskers have been obtained on brace 112-bar0 brace faces of cadmium sulphide plates with a copper layer deposited in advance. The whiskers grew during the annealing of the plates in a weak stream of technically pure argon at temperatures 670 to 730 deg C for 15 min to 3.5 h. Details about the procedure have been given elsewhere. The composition and morphology of the whiskers have been studied by an X-ray microanalyser JEOL 35 DDS and a scanning electron microscope JEOL, JSM 35. The optical microscopic observations have shown that after annealing, a gray-black granular layer is formed on the cadmium sulphide single crystals and this layer can easily be separated from the crystal substrate. Under the granular layer the crystal is heavily damaged. The whiskers grow on the granular layer and they are coloured yellow-brown or red-brown. The maximum whisker length attains several hundreds of micrometres and in some cases up to 1 mm or more. (author)

  5. Growth of cadmium oxide whiskers on cadmium sulphide single crystals with copper as growth activator

    Energy Technology Data Exchange (ETDEWEB)

    Koparanova, N.; Simov, S. (Bylgarska Akademiya na Naukite, Sofia. Inst. po Fizika na Tvyrdoto Tyalo); Genchev, D. (Bylgarska Akademiya na Naukite, Sofia. Inst. za Yadrena Izsledvaniya i Yadrena Energetika); Metchenov, G. (Research Inst. of Criminalistics and Criminology, Sofia (Bulgaria))

    1985-02-01

    Some results on the growth and morphology of cadmium oxide whiskers, obtained on cadmium sulphide single crystals with copper as a growth activator, are presented in this work. Cadmium oxide whiskers have been obtained on brace 112-bar0 brace faces of cadmium sulphide plates with a copper layer deposited in advance. The whiskers grew during the annealing of the plates in a weak stream of technically pure argon at temperatures 670 to 730 deg C for 15 min to 3.5 h. Details about the procedure have been given elsewhere. The composition and morphology of the whiskers have been studied by an X-ray microanalyser JEOL 35 DDS and a scanning electron microscope JEOL, JSM 35. The optical microscopic observations have shown that after annealing, a gray-black granular layer is formed on the cadmium sulphide single crystals and this layer can easily be separated from the crystal substrate. Under the granular layer the crystal is heavily damaged. The whiskers grow on the granular layer and they are coloured yellow-brown or red-brown. The maximum whisker length attains several hundreds of micrometres and in some cases up to 1 mm or more.

  6. A comparison of buried oxide characteristics of single and multiple implant SIMOX and bond and etch back wafers

    International Nuclear Information System (INIS)

    Annamalai, N.K.; Bockman, J.F.; McGruer, N.E.; Chapski, J.

    1990-01-01

    The current through the buried oxides of single and multiple implant SIMOX and bond and etch back silicon-on-insulator (BESOI) wafers were measured as a function of radiation dose. From these measurements, conductivity and static capacitances were derived. High frequency capacitances were also measured. Leakage current through the buried oxide of multiple implant SIMOX is considerably less than that of single implant SIMOX (more than an order of magnitude). High frequency and static capacitances, as a function of total dose, were used to study the buried oxide---top silicon interface and the buried oxide---bottom silicon interface. Multiple implant had fewer interface traps than single implant at pre-rad and after irradiation

  7. Deposition of phospholipid layers on SiO{sub 2} surface modified by alkyl-SAM islands

    Energy Technology Data Exchange (ETDEWEB)

    Tero, R.; Takizawa, M.; Li, Y.J.; Yamazaki, M.; Urisu, T

    2004-11-15

    Formation of the supported planar bilayer of dipalmitoylphosphatidylcholine (DPPC) on SiO{sub 2} surfaces modified with the self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) has been investigated by atomic force microscopy (AFM). DPPC was deposited by the fusion of vesicles on SiO{sub 2} surfaces with OTS-SAM islands of different sizes and densities. The DPPC bilayer membrane formed self-organizingly on the SiO{sub 2} surface with small and sparse OTS islands, while did not when the OTS islands were larger and denser. The relative size between the vesicles and the SiO{sub 2} regions is the critical factor for the formation of the DPPC bilayer membrane.

  8. Optimizing conditions of preparation of thermoresponsive SiO{sub 2}-POEGMA particles via AGET-ATRP

    Energy Technology Data Exchange (ETDEWEB)

    Du, Zhiping, E-mail: duzhiping@sxu.edu.cn [Institute of Resources and Environment Engineering, Shanxi University, No. 92 Wucheng Road, Taiyuan 030006 (China); China Research Institute of Daily Chemical Industry, No.34 Wenyuan Road, Taiyuan 030001 (China); Sun, Xiaofeng; Tai, Xiumei; Wang, Guoyong; Liu, Xiaoying [China Research Institute of Daily Chemical Industry, No.34 Wenyuan Road, Taiyuan 030001 (China)

    2015-02-28

    Graphical abstract: - Highlights: • Thermosensitive SiO{sub 2} nanoparticles were prepared with POEGMA via AGET-ATRP. • Reaction conditions were optimized. • Thermosensitive properties of SiO{sub 2}-POEGMA particles were pronounced. - Abstract: Thermosensitive poly(ethylene glycol) methyl ether methacrylate (POEGMA) was grafted on SiO{sub 2} nanoparticles using activators generated by electron transfer atom transfer radical polymerization (AGET-ATRP) technique. The effects of the amount of ligand, catalyst, ascorbic acid and monomer, as well as the reaction temperature and time were systematically investigated and optimized to get a high grafting density. The structure of the hybrid materials was characterized by Fourier transform infrared (FTIR) spectroscopy, and the morphology was characterized by transmission electron microscopy (TEM) observations. Thermosensitive properties of SiO{sub 2}-POEGMA particles were investigated at different grafting densities by turbidity measurements.

  9. Powerful greenhouse gas nitrous oxide adsorption onto intrinsic and Pd doped Single walled carbon nanotube

    International Nuclear Information System (INIS)

    Yoosefian, Mehdi

    2017-01-01

    Highlights: • Investigation of the adsorption of Nitrous oxide on SWCNT and Pd/SWCNT. • Nitrous oxide adsorbed on Pd/SWCNT system demonstrates a strong adsorption. • The Pd/SWCNT is potential sensor for the Nitrous oxide gaseous molecule detection. - Abstract: Density functional studies on the adsorption behavior of nitrous oxide (N 2 O) onto intrinsic carbon nanotube (CNT) and Pd-doped (5,5) single-walled carbon nanotube (Pd-CNT) have been reported. Introduction of Pd dopant facilitates in adsorption of N 2 O on the otherwise inert nanotube as observed from the adsorption energies and global reactivity descriptor values. Among three adsorption features of N 2 O onto CNT, the horizontal adsorption with E ads = −0.16 eV exhibits higher adsorption energy. On the other hand the Pd-CNT exhibit strong affinity toward gas molecule and would cause a huge increase in N 2 O adsorption energies. Chemical and electronic properties of CNT and Pd-CNT in the absence and presence of N 2 O were investigated. Adsorption of N 2 O gas molecule would affect the electronic conductance of Pd-CNT that can serve as a signal of gas sensors and the increased energy gaps demonstrate the formation of more stable systems. The atoms in molecules (AIM) theory and the natural bond orbital (NBO) calculations were performed to get more details about the nature and charge transfers in intermolecular interactions within adsorption process. As a final point, the density of states (DOSs) calculations was achieved to confirm previous results. According to our results, intrinsic CNT cannot act as a suitable adsorbent while Pd-CNT can be introduced as novel detectable complex for designing high sensitive, fast response and high efficient carbon nanotube based gas sensor to detect N 2 O gas as an air pollutant. Our results could provide helpful information for the design and fabrication of the N 2 O sensors.

  10. Nanoporous SiO{sub 2}/TiO{sub 2} coating with enhanced interfacial compatibility for orthopedic applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xiaobing, E-mail: zhaoxiaobing00@163.com [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 (China); Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164 (China); Cao, Hengchun; You, Jing; Cheng, Xingbao [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Xie, Youtao [Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 (China); Cao, Huiliang [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Liu, Xuanyong, E-mail: xyliu@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2015-11-15

    Graphical abstract: - Highlights: • The SiO{sub 2}/TiO{sub 2} coatings were fabricated on the cp-Ti substrates by plasma spraying. • Nanoporous topography was formed on SiO{sub 2}/TiO{sub 2} coating by HF-hydrothermal etching. • The hydrothermal conditions had important effects on the nanoporous topographies. • Nanoporous SiO{sub 2}/TiO{sub 2} coating exhibited enhanced cytocompatibility. - Abstract: Topographic modification in nanoscale is one of the most often used strategies to enhance the interfacial biocompatibility of implant materials. The aim of this work is to produce SiO{sub 2}/TiO{sub 2} coatings with nanoporous structures and favorable biological properties by atmospheric plasma spraying technology and subsequently hydrothermal etching method in hydrogen fluoride solution. The effects of hydrothermal time and temperature on the microstructures and osteoblast behavior of the SiO{sub 2}/TiO{sub 2} coatings were investigated. Results demonstrated that the as-sprayed SiO{sub 2}/TiO{sub 2} coating was mainly composed of rutile and quartz phases. After etching, nanoporous topographies were formed on the surface of the coatings and the hydrothermal parameters had important influences on the size and shape of the pores. The interconnected network pores on the coating surface could only produce at the appropriate hydrothermal conditions (the hydrothermal time and temperature were 60 min and 100 °C, respectively). Compared to TiO{sub 2} and SiO{sub 2}/TiO{sub 2} coatings, nanoporous SiO{sub 2}/TiO{sub 2} coatings could enhance osteoblast adhesion and promote cell proliferation. The results suggested the potential application of the porous coatings for enhancing the biological performance of the currently used dental and orthopedic implant materials.

  11. Phase transformation in SiO{sub x}/SiO{sub 2} multilayers for optoelectronics and microelectronics applications

    Energy Technology Data Exchange (ETDEWEB)

    Roussel, M. [Groupe de Physique des Matériaux, Université et INSA de Rouen, UMR CNRS 6634, Avenue de l' Université, BP 12, 76801 Saint Etienne du Rouvray, France, Europe (France); Talbot, E., E-mail: etienne.talbot@univ-rouen.fr [Groupe de Physique des Matériaux, Université et INSA de Rouen, UMR CNRS 6634, Avenue de l' Université, BP 12, 76801 Saint Etienne du Rouvray, France, Europe (France); Pratibha Nalini, R.; Gourbilleau, F. [Centre de Recherche sur les Ions, les Matériaux et la Photonique (CIMAP), CEA/CNRS/ENSICAEN/UCBN, 6 Bd. Maréchal Juin, 14050 Caen Cedex 4, France, Europe (France); Pareige, P. [Groupe de Physique des Matériaux, Université et INSA de Rouen, UMR CNRS 6634, Avenue de l' Université, BP 12, 76801 Saint Etienne du Rouvray, France, Europe (France)

    2013-09-15

    Due to the quantum confinement, silicon nanoclusters (Si-ncs) embedded in a dielectric matrix are of prime interest for new optoelectronics and microelectronics applications. In this context, SiO{sub x}/SiO{sub 2} multilayers have been prepared by magnetron sputtering and subsequently annealed to induce phase separation and Si clusters growth. The aim of this paper is to study phase separation processes and formation of nanoclusters in SiO{sub x}/SiO{sub 2} multilayers by atom probe tomography. Influences of the silicon supersaturation, annealing temperature and SiO{sub x} and SiO{sub 2} layer thicknesses on the final microstructure have been investigated. It is shown that supersaturation directly determines phase separation regime between nucleation/classical growth and spinodal decomposition. Annealing temperature controls size of the particles and interface with the surrounding matrix. Layer thicknesses directly control Si-nc shapes from spherical to spinodal-like structures. - Highlights: ► SiO{sub x}/SiO{sub 2} multilayers containing Si-ncs have been characterized using atom probe. ► Influence of SiO{sub x} composition on decomposition mode has been investigated. ► Influence of sublayer thicknesses on phase separation has been studied.

  12. Electron irradiation response on Ge and Al-doped SiO{sub 2} optical fibres

    Energy Technology Data Exchange (ETDEWEB)

    Yaakob, N.H.; Wagiran, H. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Hossain, I., E-mail: imamhossain@utm.m [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Ramli, A.T. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Bradley, D.A [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Hashim, S. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Ali, H. [Department of Radiotherapy and Oncology, Hospital Sultan Ismail, Johor Darul Takzim (Malaysia)

    2011-05-01

    This paper describes the thermoluminescence response, sensitivity, stability and reproducibility of SiO{sub 2} optical fibres with various electron energies and doses. The TL materials that comprise Al- and Ge-doped silica fibres were used in this experiment. The TL results are compared with those of the commercially available TLD-100. The doped SiO{sub 2} optical fibres and TLD-100 are placed in a solid phantom and irradiated with 6, 9 and 12 MeV electron beams at doses ranging from 0.2 to 4.0 Gy using the LINAC at Hospital Sultan Ismail, Johor Bahru, Malaysia. It was found that the commercially available Al- and Ge-doped optical fibres have a linear dose-TL signal relationship. The intensity of TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre.

  13. Single step synthesis, characterization and applications of curcumin functionalized iron oxide magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bhandari, Rohit; Gupta, Prachi; Dziubla, Thomas; Hilt, J. Zach, E-mail: zach.hilt@uky.edu

    2016-10-01

    Magnetic iron oxide nanoparticles have been well known for their applications in magnetic resonance imaging (MRI), hyperthermia, targeted drug delivery, etc. The surface modification of these magnetic nanoparticles has been explored extensively to achieve functionalized materials with potential application in biomedical, environmental and catalysis field. Herein, we report a novel and versatile single step methodology for developing curcumin functionalized magnetic Fe{sub 3}O{sub 4} nanoparticles without any additional linkers, using a simple coprecipitation technique. The magnetic nanoparticles (MNPs) were characterized using transmission electron microscopy, X-ray diffraction, fourier transform infrared spectroscopy and thermogravimetric analysis. The developed MNPs were employed in a cellular application for protection against an inflammatory agent, a polychlorinated biphenyl (PCB) molecule. - Graphical abstract: Novel single step curcumin coated magnetic Fe{sub 3}O{sub 4} nanoparticles without any additional linkers for medical, environmental, and other applications. Display Omitted - Highlights: • A novel and versatile single step methodology for developing curcumin functionalized magnetic Fe{sub 3}O{sub 4} nanoparticles is reported. • The magnetic nanoparticles (MNPs) were characterized using TEM, XRD, FTIR and TGA. • The developed MNPs were employed in a cellular application for protection against an inflammatory agent, a polychlorinated biphenyl (PCB).

  14. SiO{sub 2} coating of silver nanoparticles by photoinduced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Boies, Adam M; Girshick, Steven L [Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, MN 55455 (United States); Roberts, Jeffrey T [Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455 (United States); Zhang Bin; Nakamura, Toshitaka; Mochizuki, Amane, E-mail: jtrob@umn.ed, E-mail: slg@umn.ed [Nitto Denko Technical Corporation, 501 Via Del Monte, Oceanside, CA 92058 (United States)

    2009-07-22

    Gas-phase silver nanoparticles were coated with silicon dioxide (SiO{sub 2}) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO{sub 2} precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating a chemical reaction that forms SiO{sub 2} coatings on the particle surfaces. Coating thicknesses were measured for a variety of operation parameters using tandem differential mobility analysis and transmission electron microscopy. The chemical composition of the particle coatings was analyzed using energy dispersive x-ray spectrometry and Fourier transform infrared spectroscopy. The highest purity films were produced at 300-400 {sup 0}C with low flow rates of additional oxygen. The photo-CVD coating technique was shown to effectively coat nanoparticles and limit core particle agglomeration at concentrations up to 10{sup 7} particles cm{sup -3}.

  15. Fluorocarbon based atomic layer etching of Si{sub 3}N{sub 4} and etching selectivity of SiO{sub 2} over Si{sub 3}N{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chen [Department of Physics, and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Metzler, Dominik; Oehrlein, Gottlieb S., E-mail: oehrlein@umd.edu [Department of Materials Science and Engineering, and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Lai, Chiukin Steven; Hudson, Eric A. [Lam Research Corporation, 4400 Cushing Parkway, Fremont, California 94538 (United States)

    2016-07-15

    Angstrom-level plasma etching precision is required for semiconductor manufacturing of sub-10 nm critical dimension features. Atomic layer etching (ALE), achieved by a series of self-limited cycles, can precisely control etching depths by limiting the amount of chemical reactant available at the surface. Recently, SiO{sub 2} ALE has been achieved by deposition of a thin (several Angstroms) reactive fluorocarbon (FC) layer on the material surface using controlled FC precursor flow and subsequent low energy Ar{sup +} ion bombardment in a cyclic fashion. Low energy ion bombardment is used to remove the FC layer along with a limited amount of SiO{sub 2} from the surface. In the present article, the authors describe controlled etching of Si{sub 3}N{sub 4} and SiO{sub 2} layers of one to several Angstroms using this cyclic ALE approach. Si{sub 3}N{sub 4} etching and etching selectivity of SiO{sub 2} over Si{sub 3}N{sub 4} were studied and evaluated with regard to the dependence on maximum ion energy, etching step length (ESL), FC surface coverage, and precursor selection. Surface chemistries of Si{sub 3}N{sub 4} were investigated by x-ray photoelectron spectroscopy (XPS) after vacuum transfer at each stage of the ALE process. Since Si{sub 3}N{sub 4} has a lower physical sputtering energy threshold than SiO{sub 2}, Si{sub 3}N{sub 4} physical sputtering can take place after removal of chemical etchant at the end of each cycle for relatively high ion energies. Si{sub 3}N{sub 4} to SiO{sub 2} ALE etching selectivity was observed for these FC depleted conditions. By optimization of the ALE process parameters, e.g., low ion energies, short ESLs, and/or high FC film deposition per cycle, highly selective SiO{sub 2} to Si{sub 3}N{sub 4} etching can be achieved for FC accumulation conditions, where FC can be selectively accumulated on Si{sub 3}N{sub 4} surfaces. This highly selective etching is explained by a lower carbon consumption of Si{sub 3}N{sub 4} as compared to SiO{sub

  16. Detection of short range order in SiO{sub 2} thin-films by grazing-incidence wide and small-angle X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Nagata, Kohki, E-mail: nagata.koki@iri-tokyo.jp [Tokyo Metropolitan Industrial Technology Research Institute, 2-4-10 Aomi, Koto-ku, Tokyo 135-0064 (Japan); School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Ogura, Atsushi [School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Hirosawa, Ichiro [Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Suwa, Tomoyuki; Teramoto, Akinobu; Ohmi, Tadahiro [New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aramakiazaaoba, Aoba-ku, Sendai, Miyagi 980-8579 (Japan)

    2016-04-21

    The effects of the fabrication process conditions on the microstructure of silicon dioxide thin films of <10 nm thickness are presented. The microstructure was investigated using grazing-incidence wide and small-angle X-ray scattering methods with synchrotron radiation. The combination of a high brilliance light source and grazing incident configuration enabled the observation of very weak diffuse X-ray scattering from SiO{sub 2} thin films. The results revealed different microstructures, which were dependent on oxidizing species or temperature. The micro-level properties differed from bulk properties reported in the previous literature. It was indicated that these differences originate from inner stress. The detailed structure in an amorphous thin film was not revealed owing to detection difficulties.

  17. A Facile Route to Metal Oxides/Single-Walled Carbon Nanotube Macrofilm Nanocomposites for Energy Storage

    Directory of Open Access Journals (Sweden)

    Zeyuan eCao

    2015-05-01

    Full Text Available Nanocomposites consisting of transition-metal oxides and carbon nanomaterials with a desired size and structure are highly demanded for high performance energy storage devices. Here, a facile two-step and cost-efficient approach relying on directly thermal treatment of chemical-vapor-deposition products is developed as a general synthetic method to prepare a family of metal oxides (MxOy (M=Fe, Co, Ni/single-walled carbon nanotube (SWNT macrofilm nanocomposites. The MxOy nanoparticles obtained are of 3-17 nm in diameter and homogeneously anchor on the free-standing SWNT macrofilms. NiO/SWNT also exhibits a high specific capacitance of 400 F g-1 and fast charge-transfer Faradaic redox reactions to achieve asymmetric supercapacitors with a high power and energy density. All MxOy/SWNT nanocomposites could deliver a high capacity beyond 1000 mAh g-1 and show excellent cycling stability for lithium-ion batteries. The impressive results demonstrate the promise for energy storage devices and the general approach may pave the way to synthesize other functional nanocomposites.

  18. Single Pd Atoms on θ-Al2O3 (010) Surface do not Catalyze NO Oxidation.

    Science.gov (United States)

    Narula, Chaitanya K; Allard, Lawrence F; Moses-DeBusk, Melanie; Stocks, G Malcom; Wu, Zili

    2017-04-03

    New convenient wet-chemistry synthetic routes have made it possible to explore catalytic activities of a variety of single supported atoms, however, the single supported atoms on inert substrates (e.g. alumina) are limited to adatoms and cations of Pt, Pd, and Ru. Previously, we have found that single supported Pt atoms are remarkable NO oxidation catalysts. In contrast, we report that Pd single atoms are completely inactive for NO oxidation. The diffuse reflectance infra-red spectroscopy (DRIFTS) results show the absence of nitrate formation on catalyst. To explain these results, we explored modified Langmuir-Hinshelwood type pathways that have been proposed for oxidation reactions on single supported atom. In the first pathway, we find that there is energy barrier for the release of NO 2 which prevent NO oxidation. In the second pathway, our results show that there is no driving force for the formation of O=N-O-O intermediate or nitrate on single supported Pd atoms. The decomposition of nitrate, if formed, is an endothermic event.

  19. On the elastic properties of single-walled carbon nanotubes/poly(ethylene oxide) nanocomposites using molecular dynamics simulations.

    Science.gov (United States)

    Rouhi, S; Alizadeh, Y; Ansari, R

    2016-01-01

    Molecular dynamics simulations are used to study the physical and mechanical properties of single-walled carbon nanotubes/poly(ethylene oxide) nanocomposites. The effects of nanotube atomic structure, diameter, and volume fraction on the polymer density distribution, polymer atom distribution, stress-strain curves of nanocomposites and Young's, and shear moduli of single-walled carbon nanotubes/poly(ethylene oxide) nanocomposites are explored. It is shown that the density of polymer, surrounding the nanotube surface, has a peak near the nanotube surface. However, increasing distance leads to dropping it to the value near the density of pure polymer. It is seen that for armchair nanotubes, the average polymer atoms distances from the single-walled carbon nanotubes are larger than the polymer atom distance from zigzag nanotubes. It further is shown that zigzag nanotubes are better candidates to reinforce poly (ethylene oxide) than their armchair counterparts.

  20. Single photon sources using oxide apertured micropillars with integrated electrical control for novel functionalities

    Science.gov (United States)

    Stoltz, Nicholas G.

    The goal of this thesis is to apply the oxide apertured vertical cavity laser structure in order to explore quantum dot-microcavity coupling for the development of novel single photon sources (SPS). Optical microcavities combined with active emitters provide an opportunity to study the light matter interaction on a fundamental level. Edward Purcell first theorized in 1947 that the spontaneous emission (SE) rate of an optical emitter could be modified in the presence of an optical cavity. As semiconductor microcavity technology has advanced many optoelectronic devices have benefited from the increased SE rates predicted by the Purcell effect. The development of quantum emitters on an integrated semiconductor platform in the form of semiconductor self-assembled quantum dots (QDs) has expanded applications in the field. Coupling atomic emitters to optical microcavities in the solid state allows for the study of cavity quantum electrodynamics and the fabrication single photon (SP) devices. Optoelectronic devices providing non-classical light states have a broad range of applications in quantum information science, including quantum key distribution systems, quantum lithography, and quantum computing. Here, the oxide apertured micropillar approach demonstrates high quality microcavities with cavity quality factors up to 50,000 and measured Purcell enhancements of 10. In addition the inherent advantages provided by the oxide apertured micropillar, specifically high collection efficiency, have produced SPSs with record high SP rates and quantum efficiencies representing a six-fold improvement over reported values. In addition we have developed and integrated a scheme allowing for on-chip electrical control of SP devices for the implementation of SPSs with novel functionalities. The active electrical control of QD charge state has allowed for the elimination of dark states which severely limit SP rates and efficiencies. The active electrical tuning of QD emission energy

  1. Nanoampere charge pump by single-electron ratchet using silicon nanowire metal-oxide-semiconductor field-effect transistor

    Science.gov (United States)

    Fujiwara, Akira; Nishiguchi, Katsuhiko; Ono, Yukinori

    2008-01-01

    Nanoampere single-electron pumping is presented at 20K using a single-electron ratchet comprising silicon nanowire metal-oxide-semiconductor field-effect transistors. The ratchet features an asymmetric potential with a pocket that captures single electrons from the source and ejects them to the drain. Directional single-electron transfer is achieved by applying one ac signal with the frequency up to 2.3GHz. We find anomalous shapes of current steps which can be ascribed to nonadiabatic electron capture.

  2. Powerful greenhouse gas nitrous oxide adsorption onto intrinsic and Pd doped Single walled carbon nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Yoosefian, Mehdi, E-mail: m.yoosefian@kgut.ac.ir

    2017-01-15

    Highlights: • Investigation of the adsorption of Nitrous oxide on SWCNT and Pd/SWCNT. • Nitrous oxide adsorbed on Pd/SWCNT system demonstrates a strong adsorption. • The Pd/SWCNT is potential sensor for the Nitrous oxide gaseous molecule detection. - Abstract: Density functional studies on the adsorption behavior of nitrous oxide (N{sub 2}O) onto intrinsic carbon nanotube (CNT) and Pd-doped (5,5) single-walled carbon nanotube (Pd-CNT) have been reported. Introduction of Pd dopant facilitates in adsorption of N{sub 2}O on the otherwise inert nanotube as observed from the adsorption energies and global reactivity descriptor values. Among three adsorption features of N{sub 2}O onto CNT, the horizontal adsorption with E{sub ads} = −0.16 eV exhibits higher adsorption energy. On the other hand the Pd-CNT exhibit strong affinity toward gas molecule and would cause a huge increase in N{sub 2}O adsorption energies. Chemical and electronic properties of CNT and Pd-CNT in the absence and presence of N{sub 2}O were investigated. Adsorption of N{sub 2}O gas molecule would affect the electronic conductance of Pd-CNT that can serve as a signal of gas sensors and the increased energy gaps demonstrate the formation of more stable systems. The atoms in molecules (AIM) theory and the natural bond orbital (NBO) calculations were performed to get more details about the nature and charge transfers in intermolecular interactions within adsorption process. As a final point, the density of states (DOSs) calculations was achieved to confirm previous results. According to our results, intrinsic CNT cannot act as a suitable adsorbent while Pd-CNT can be introduced as novel detectable complex for designing high sensitive, fast response and high efficient carbon nanotube based gas sensor to detect N{sub 2}O gas as an air pollutant. Our results could provide helpful information for the design and fabrication of the N{sub 2}O sensors.

  3. Highly efficient electrochemical responses on single crystalline ruthenium-vanadium mixed metal oxide nanowires.

    Science.gov (United States)

    Chun, Sung Hee; Choi, Hyun-A; Kang, Minkyung; Koh, Moonjee; Lee, Nam-Suk; Lee, Sang Cheol; Lee, Minyung; Lee, Youngmi; Lee, Chongmok; Kim, Myung Hwa

    2013-09-11

    Highly efficient single crystalline ruthenium-vanadium mixed metal oxide (Ru1-xVxO2, 0≤x≤1) nanowires were prepared on a SiO2 substrate and a commercial Au microelectrode for the first time through a vapor-phase transport process by adjusting the mixing ratios of RuO2 and VO2 precursors. Single crystalline Ru1-xVxO2 nanowires show homogeneous solid-solution characteristics as well as the distinct feature of having remarkably narrow dimensional distributions. The electrochemical observations of a Ru1-xVxO2 (x=0.28 and 0.66)-decorated Au microelectrode using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrate favorable charge-transfer kinetics of [Fe(CN)6]3-/4- and Ru(NH3)6(3+/2+) couples compared to that of a bare Au microelectrode. The catalytic activity of Ru1-xVxO2 for oxygen and H2O2 reduction at neutral pH increases as the fraction of vanadium increases within our experimental conditions, which might be useful in the area of biofuel cells and biosensors.

  4. Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives: Synthesis and the effects on chemical mechanical polishing (CMP) performances of sapphire wafers

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Tingting; Lei, Hong, E-mail: hong_lei2005@aliyun.com

    2017-08-15

    Highlights: • The novel Nd{sup 3+}-doped colloidal SiO{sub 2} abrasives were synthesized by seed-introduced method. • The Nd{sup 3+}-doped colloidal SiO{sub 2} abrasives exhibited lower Ra and higher MRR on sapphire during CMP. • The cores SiO{sub 2} were coated by the shells (SiO{sub 2}, Nd{sub 2}Si{sub 2}O{sub 7} and Nd(OH){sub 3}) via chemical bonds and hydrogen bonds. • XPS analysis revealed the solid-state chemical reaction between Nd{sup 3+}-doped colloidal SiO{sub 2} abrasives and sapphire during CMP. - Abstract: Abrasive is one of the most important factors in chemical mechanical polishing (CMP). In order to improve the polishing qualities of sapphire substrates, the novel Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives were prepared by seed-induced growth method. In this work, there were a series of condensation reactions during the synthesis process of Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives and the silica cores were coated by shells (which contains SiO{sub 2}, Nd{sub 2}Si{sub 2}O{sub 7} and Nd(OH){sub 3}) via chemical bonds and hydrogen bonds in the Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives, which made the composite abrasives’ core-shell structure more sTable Scanning electron microscopy (SEM) showed that Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives were spherical and uniform in size. And the acting mechanisms of Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives on sapphire in CMP were investigated. Time-of-flight secondary ion mass spectroscopy (TOF-SIMS) analysis and X-ray photoelectron spectroscopy (XPS) analysis demonstrated that the solid-state chemical reactions between the shells (which contained SiO{sub 2}, Nd{sub 2}Si{sub 2}O{sub 7} and Nd(OH){sub 3}) of Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives and the sapphire occurred during the CMP process. Furthermore, Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives exhibited lower surface roughness and

  5. Nanotubes oxidation temperature controls the height of single-walled carbon nanotube forests on gold micropatterned thin layers.

    Science.gov (United States)

    Lamberti, Francesco; Agnoli, Stefano; Meneghetti, Moreno; Elvassore, Nicola

    2010-07-06

    We developed a simple methodology for a direct control of the height of carboxylated single-walled carbon nanotube (SWNT) forests. We found that the important step is a good control of the oxidation temperature of the nanotubes. SWNTs oxidation at different temperature was followed by Raman and X-ray photoelectron spectroscopies. Atomic force microscopy images showed that micropatterned self-assembled monolayers forests have average height from 20 to 80 nm using SWNTs oxidized in the temperature ranging from 323 to 303 K, respectively.

  6. Microstructural, thermal, physical and mechanical behavior of the self compacting concrete containing SiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nazari, Ali, E-mail: alinazari84@aut.ac.ir [Department of Technical and Engineering Sciences, Islamic Azad University (Saveh Branch), Saveh (Iran, Islamic Republic of); Riahi, Shadi [Department of Technical and Engineering Sciences, Islamic Azad University (Saveh Branch), Saveh (Iran, Islamic Republic of)

    2010-11-15

    Research highlights: {yields} TiO{sub 2} nanoparticles effects on flexural strength of self compacting concrete. {yields} Physical and microstructural consideration. {yields} Mechanical tests. {yields} Thermal analysis. {yields} Porosimetry. - Abstract: In the present study, flexural strength, thermal properties and microstructure of self compacting concrete with different amount of SiO{sub 2} nanoparticles has been investigated. SiO{sub 2} nanoparticles with the average particle size of 15 nm were partially added to self compacting concrete and various behaviors of the specimens have been measured. The results indicate that SiO{sub 2} nanoparticles are able to improve the flexural strength of self compacting concrete and recover the negative effects of superplasticizer on flexural strength of the specimens. SiO{sub 2} nanoparticle as a partial replacement of cement up to 4 wt% could accelerate C-S-H gel formation as a result of the increased crystalline Ca(OH){sub 2} amount at the early ages of hydration. The increased the SiO{sub 2} nanoparticles' content more than 4 wt%, causes the reduced the flexural strength because of unsuitable dispersion of nanoparticles in the concrete matrix. Accelerated peak appearance in conduction calorimetry tests, more weight loss in thermogravimetric analysis and more rapid appearance of peaks related to hydrated products in X-ray diffraction results, all also indicate that SiO{sub 2} nanoparticles up to 4 wt% could improve the mechanical and physical properties of the specimens. Finally, SiO{sub 2} nanoparticles could improve the pore structure of concrete and shift the distributed pores to harmless and few-harm pores.

  7. Structure and magnetic properties of SiO{sub 2}/PCL novel sol–gel organic–inorganic hybrid materials

    Energy Technology Data Exchange (ETDEWEB)

    Catauro, Michelina, E-mail: michelina.catauro@unina2.it [Department of Industrial and Information Engineering, Second University of Naples, Via Roma 29, 81031 Aversa (Italy); Bollino, Flavia [Department of Industrial and Information Engineering, Second University of Naples, Via Roma 29, 81031 Aversa (Italy); Cristina Mozzati, Maria [Department of Physics, CNISM and INSTM, University of Pavia, Via Bassi 6, 27100 Pavia (Italy); Ferrara, Chiara; Mustarelli, Piercarlo [Department of Chemistry, Section of Physical Chemistry, University of Pavia and INSTM, Via Taramelli 16, 27100 Pavia (Italy)

    2013-07-15

    Organic–inorganic nanocomposite materials have been synthesized via sol–gel. They consist of an inorganic SiO{sub 2} matrix, in which different percentages of poly(ε-caprolactone) (PCL) have been incorporated. The formation of H-bonds among the carbonyl groups of the polymer chains and Si–OH group of the inorganic matrix has been proved by means of Fourier transform infrared spectroscopy (FT-IR) analysis and has been confirmed by solid-state nuclear magnetic resonance (NMR). X-Ray diffraction (XRD) analysis highlighted the amorphous nature of the synthesized materials. Scanning electron microscope (SEM) micrograph and atomic force microscope (AFM) topography showed their homogeneous morphology and nanostructure nature. Considering the opportunity to synthesize these hybrid materials under microgravity conditions by means of magnetic levitation, superconducting quantum interference device (SQUID) magnetometry has been used to quantify their magnetic susceptibility. This measure has shown that the SiO{sub 2}/PCL hybrid materials are diamagnetic and that their diamagnetic susceptibility is independent of temperature and increases with the PCL amount. - Graphical abstract: Characterization and magnetic properties of SiO{sub 2}/PCL organic–inorganic hybrid materials synthesized via sol–gel. FT-IR, Fourier transform infrared spectroscopy; solid-state NMR: solid-state nuclear magnetic resonance; SQUID: superconducting quantum interference device. - Highlights: • Sol–gel synthesis of SiO{sub 2}/PCL amorphous class I organic–inorganic hybrid materials. • FT-IR and NMR analyses show the hydrogen bonds formation between SiO{sub 2} and PCL. • AFM and SEM analyses confirm that the SiO{sub 2}/PCL are homogenous hybrid materials. • The SQUID measures show that the simples are diamagnetic. • Diamagnetic susceptibility of SiO{sub 2}/PCL materials increases with the PCL amount.

  8. Single-bilayer graphene oxide sheet tolerance and glutathione redox system significance assessment in faba bean ( Vicia faba L.)

    Science.gov (United States)

    Anjum, Naser A.; Singh, Neetu; Singh, Manoj K.; Shah, Zahoor A.; Duarte, Armando C.; Pereira, Eduarda; Ahmad, Iqbal

    2013-07-01

    Adsorbents based on single-bilayer graphene oxide sheet (hereafter termed "graphene oxide") are widely used in contaminated environments cleanup which may easily open the avenues for their entry to different environmental compartments, exposure to organisms and their subsequent transfer to human/animal food chain. Considering a common food crop—faba bean ( Vicia faba L.) germinating seedlings as a model plant system, this study assesses the V. faba-tolerance to different concentrations (0, 100, 200, 400, 800, and 1600 mg L-1) of graphene oxide (0.5-5 μm) and evaluates glutathione (γ-glutamyl-cysteinyl-glycine) redox system significance in this context. The results showed significantly increased V. faba sensitivity under three graphene oxide concentrations (in order of impact: 1,600 > 200 > 100 mg graphene oxide L-1), which was accompanied by decreased glutathione redox (reduced glutathione-to-oxidized glutathione) ratio, reduced glutathione pool, as well as significant and equally elevated activities of glutathione-regenerating (glutathione reductase) and glutathione-metabolizing (glutathione peroxidase; glutathione sulfo-transferase) enzymes. Contrarily, the two graphene oxide concentrations (in order of impact: 800 > 400 graphene oxide mg L-1) yielded promising results; where, significant improvements in V. faba health status (measured as increased graphene oxide tolerance) were clearly perceptible with increased ratio of the reduced glutathione-to-oxidized glutathione, reduced glutathione pool and glutathione reductase activity but decreased activities of glutathione-metabolizing enzymes. It is inferred that V. faba seedlings-sensitivity and/or tolerance to graphene oxide concentrations depends on both the cellular redox state (reduced glutathione-to-oxidized glutathione ratio) and the reduced glutathione pool which in turn are controlled by a finely tuned modulation of the coordination between glutathione-regenerating and glutathione-metabolizing enzymes.

  9. Optical refractive index and static permittivity of mixed Zr-Si oxide thin films prepared by ion beam induced CVD

    Energy Technology Data Exchange (ETDEWEB)

    Ferrer, F.J. [Centro Nacional de Aceleradores, Av. Thomas A. Edison, 7, 41092 Sevilla (Spain)], E-mail: fjferrer@us.es; Frutos, F. [E.T.S. de Ingenieria Informatica, Avda. Reina Mercedes, s/n, 41012 Sevilla (Spain); Garcia-Lopez, J. [Centro Nacional de Aceleradores, Av. Thomas A. Edison, 7, 41092 Sevilla (Spain); Gonzalez-Elipe, A.R.; Yubero, F. [Insituto de Ciencia de Materiales de Sevilla, c/ Americo vespucio, no. 49, 41092 Sevilla (Spain)

    2007-12-03

    Mixed oxides Zr{sub x}Si{sub 1-x}O{sub 2} (0 < x < 1) thin films have been prepared at room temperature by decomposition of (CH{sub 3}CH{sub 2}O){sub 3}SiH and Zr[OC(CH{sub 3}){sub 3}]{sub 4} volatile precursors induced by mixtures of O{sub 2}{sup +} and Ar{sup +} ions. The films were flat and amorphous independently of the Si/Zr ratio and did not present phase segregation of the pure single oxides (SiO{sub 2} and ZrO{sub 2}). A 10-23 at.% of H and 1-5 at.% of C atoms remained incorporated in the films depending on the mixture ratio of the Si and Zr precursors and the composition of the bombarding gas used during the deposition process. These impurities are mainly forming hydroxyl and carboxylic groups. Optical refractive index and static permittivity of the films were determined by reflection NIR-Vis spectroscopy and C-V electrical characterization, respectively. It is found that the refractive index increases non-linearly from 1.45 to 2.10 as the Zr content in the thin films increases. The static permittivity also increases non-linearly from {approx} 4 for pure SiO{sub 2} to {approx} 15 for pure ZrO{sub 2}. Optical and electrical characteristics of the films are justified by their impurity content and the available theories.

  10. A single cysteine post-translational oxidation suffices to compromise globular proteins kinetic stability and promote amyloid formation

    Directory of Open Access Journals (Sweden)

    Patrizia Marinelli

    2018-04-01

    Full Text Available Oxidatively modified forms of proteins accumulate during aging. Oxidized protein conformers might act as intermediates in the formation of amyloids in age-related disorders. However, it is not known whether this amyloidogenic conversion requires an extensive protein oxidative damage or it can be promoted just by a discrete, localized post-translational modification of certain residues. Here, we demonstrate that the irreversible oxidation of a single free Cys suffices to severely perturb the folding energy landscape of a stable globular protein, compromise its kinetic stability, and lead to the formation of amyloids under physiological conditions. Experiments and simulations converge to indicate that this specific oxidation-promoted protein aggregation requires only local unfolding. Indeed, a large scale analysis indicates that many cellular proteins are at risk of undergoing this kind of deleterious transition; explaining how oxidative stress can impact cell proteostasis and subsequently lead to the onset of pathological states. Keywords: Protein oxidation, Protein misfolding, Protein aggregation, Oxidative stress, Post-translational modification

  11. Electro-oxidized epitaxial graphene channel field-effect transistors with single-walled carbon nanotube thin film gate electrode.

    Science.gov (United States)

    Ramesh, Palanisamy; Itkis, Mikhail E; Bekyarova, Elena; Wang, Feihu; Niyogi, Sandip; Chi, Xiaoliu; Berger, Claire; de Heer, Walt; Haddon, Robert C

    2010-10-20

    We report the effect of electrochemical oxidation in nitric acid on the electronic properties of epitaxial graphene (EG) grown on silicon carbide substrates; we demonstrate the availability of an additional reaction channel in EG, which is not present in graphite but which facilitates the introduction of the reaction medium into the graphene galleries during electro-oxidation. The device performance of the chemically processed graphene was studied by patterning the EG wafers with two geometrically identical macroscopic channels; the electro-oxidized channel showed a logarithmic increase of resistance with decreasing temperature, which is ascribed to the scattering of charge carriers in a two-dimensional electronic gas, rather than the presence of an energy gap at the Fermi level. Field-effect transistors were fabricated on the electro-oxidized and pristine graphene channels using single-walled carbon nanotube thin film top gate electrodes, thereby allowing the study of the effect of oxidative chemistry on the transistor performance of EG. The electro-oxidized channel showed higher values for the on-off ratio and the mobility of the graphene field-effect transistor, which we ascribe to the availability of high-quality internal graphene layers after electro-oxidation of the more defective top layers. Thus, the present oxidative process provides a clear contrast with previously demonstrated covalent chemistry in which sp(3) hybridized carbon atoms are introduced into the graphitic transport layer of the lattice by carbon-carbon bond formation, thereby opening an energy gap.

  12. Single-bilayer graphene oxide sheet tolerance and glutathione redox system significance assessment in faba bean (Vicia faba L.)

    International Nuclear Information System (INIS)

    Anjum, Naser A.; Singh, Neetu; Singh, Manoj K.; Shah, Zahoor A.; Duarte, Armando C.; Pereira, Eduarda; Ahmad, Iqbal

    2013-01-01

    Adsorbents based on single-bilayer graphene oxide sheet (hereafter termed “graphene oxide”) are widely used in contaminated environments cleanup which may easily open the avenues for their entry to different environmental compartments, exposure to organisms and their subsequent transfer to human/animal food chain. Considering a common food crop—faba bean (Vicia faba L.) germinating seedlings as a model plant system, this study assesses the V. faba-tolerance to different concentrations (0, 100, 200, 400, 800, and 1600 mg L −1 ) of graphene oxide (0.5–5 μm) and evaluates glutathione (γ-glutamyl-cysteinyl-glycine) redox system significance in this context. The results showed significantly increased V. faba sensitivity under three graphene oxide concentrations (in order of impact: 1,600 > 200 > 100 mg graphene oxide L −1 ), which was accompanied by decreased glutathione redox (reduced glutathione-to-oxidized glutathione) ratio, reduced glutathione pool, as well as significant and equally elevated activities of glutathione-regenerating (glutathione reductase) and glutathione-metabolizing (glutathione peroxidase; glutathione sulfo-transferase) enzymes. Contrarily, the two graphene oxide concentrations (in order of impact: 800 > 400 graphene oxide mg L −1 ) yielded promising results; where, significant improvements in V. faba health status (measured as increased graphene oxide tolerance) were clearly perceptible with increased ratio of the reduced glutathione-to-oxidized glutathione, reduced glutathione pool and glutathione reductase activity but decreased activities of glutathione-metabolizing enzymes. It is inferred that V. faba seedlings-sensitivity and/or tolerance to graphene oxide concentrations depends on both the cellular redox state (reduced glutathione-to-oxidized glutathione ratio) and the reduced glutathione pool which in turn are controlled by a finely tuned modulation of the coordination between glutathione-regenerating and glutathione

  13. Grain growth behavior of Li{sub 4}SiO{sub 4} pebbles fabricated by agar method for tritium breeder

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Maoqiao [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Zhang, Yingchun, E-mail: zycustb@126.com [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Zhang, Yun; Wang, Chaofu; Liu, Wei [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Yu, Yonghong [Department of Physics, Renmin University of China, Beijing, 100872 (China)

    2016-11-15

    Highlights: • Grain sizes of Li{sub 4}SiO{sub 4} were adjusted by different silicon sources. • Grain growth exponent of Li{sub 4}SiO{sub 4} was about 3. • Grain growth activation energy of Li{sub 4}SiO{sub 4} was about 125.54 kJ/mol. • Grain growth of Li{sub 4}SiO{sub 4} pebble was controlled by vapor transport. - Abstract: The Li{sub 4}SiO{sub 4} tritium breeding pebbles will be filled in the blanket and used for 2 years or more at high temperatures, which would increase the grain size and affect tritium release. Hence, grain sizes of the Li{sub 4}SiO{sub 4} pebbles fabricated by agar method were investigated, and two kinds of different silicon sources (crystal and amorphous SiO{sub 2}) with different particle sizes were used. The particle size of SiO{sub 2} could affect grain size and density of the Li{sub 4}SiO{sub 4} pebble. And the isothermal sintering was carried out to study the grain growth kinetics of Li{sub 4}SiO{sub 4}. The grain growth exponent (n) and the activation energy (Q) were calculated by the phenomenological kinetic equation. The calculated n values were 4.10, 3.98, 3.34 and 2.96, and corresponding Q values were 152.15, 147.99, 125.54 and 110.58 kJ/mol, respectively. At the higher sintering temperatures (950 and 1000 °C), the grain growth of Li{sub 4}SiO{sub 4} was controlled by vapor transport.

  14. Plasma process-induced latent damage on gate oxide - demonstrated by single-layer and multi-layer antenna structures

    NARCIS (Netherlands)

    Wang, Zhichun; Ackaert, Jan; Salm, Cora; Kuper, F.G.

    2001-01-01

    In this paper, by using both single-layer (SL) and multi-layer (ML) or stacked antenna structures, a simple experimental method is proposed to directly demonstrate the pure plasma process-induced latent damage on gate oxide without any impact of additional defects generated by normal constant

  15. Analysis of thermal detrapping of holes created by electron irradiation in high purity amorphous SiO{sub 2} using the induced and secondary current measurements

    Energy Technology Data Exchange (ETDEWEB)

    Said, K., E-mail: kamel.said@fss.rnu.tn [LaMaCoP, Université de Sfax, BP 1171, 3000 Sfax (Tunisia); Moya, G.; Si Ahmed, A. [Im2np, UMR 7334 CNRS, Aix-Marseille Université, 13397 Marseille Cedex 20 (France); Damamme, G. [CEA, DAM, GRAMAT, 46500 Gramat (France); Kallel, A. [LaMaCoP, Université de Sfax, BP 1171, 3000 Sfax (Tunisia)

    2016-01-15

    Graphical abstract: - Highlights: • Positive charging of high purity amorphous SiO{sub 2} achieved by electron irradiation in a specially equipped scanning electron microscope. • Quantity of detrapped holes evaluated via measurements of induced and secondary electron currents. • Study of isothermal detrapping for different temperatures (300–663 K). • Analysis of the hole detrapping via a first order kinetics. • Evaluation of the hole detrapping parameters (activation energy and frequency factor). - Abstract: Isothermal detrapping of holes after electron irradiation (using a SEM) in high purity amorphous SiO{sub 2} is evaluated at different temperatures (in the range 300–663 K) by means of the induced and secondary current measurements. In order to single out the hole detrapping, the specific charging conditions (1 keV defocused electron beam of low density) leading to positive charging are adopted. The thermal detrapping, which stems from a single trap, begins at 523 K and is completed at 663 K. After annealing in air at 973 K during 48 h, two detrapping stages are revealed: the former is connected with an additional shallow trap, while the latter requires temperatures above 663 K for a complete detrapping. The first order kinetics describes reasonably well the detrapping process. The frequency factors (near 10{sup 10} s{sup −1}) and the activation energies (about 1.6 eV) deduced from this analysis could be assigned, respectively, to the relaxation connected to detrapping and to the trap energy level of the charged oxygen vacancy.

  16. Determining the impact of oxidation on the motility of single muscle-fibres expressing different myosin isoforms

    DEFF Research Database (Denmark)

    Spanos, Dimitrios; Li, M.; Baron, Caroline P.

    2013-01-01

    (motility speed) and force-generation capacity of specific MyHC isoforms. In the experimental procedure, single muscle fibres were split in different segments and each segment was exposed to a different concentration of hydrogen peroxide. Speed and force measurements were recorded and compared, to assess...... the effect of myosin oxidation on motility and force. The MyHC isoform expression in the single muscle fibre was subsequently determined on silver-stained gel SDS-PAGE. Preliminary results indicate a decrease of directionality and speed of the in-vitro motility as a result of an oxidative environment......, and the successful use of the assay in determining fibre-specific responses to oxidation. Subsequent analyses will focus on the location of protein modifications on the myosin molecule and on how these modifications induce changes in speed and force....

  17. The nucleic acid metabolism in rat liver after single and long-term administration of tritium oxide

    International Nuclear Information System (INIS)

    Shorokhova, V.B.

    1984-01-01

    It was shown that after a single administration of tritiUm oxide in a dose of 22.2 MBq/g body mass the liver mass increased, the concentration of nucleic acids decreased and the biosynthesjs rate increased dUring a one-month observation. By the end of the observation period (the first year) the parameters under study were normalized. The long-term administration of tritium oxide in daily doses of 0.37, 0.925 and 1.85 MBq/g body mass caused changes in the nucleac acid metabolism which were less manifest (at early times), than in the case of a single injection. At the same time, the long-term administration of tritium oxide in the dose of 0.925 MBq/g caused a substantial disturbance of the nucleic acid metabolism at later times (after 2-9 months)

  18. Neutral and cationic free-space oxygen–silicon clusters SiO{sub n} (1SiO{sub 2} under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Forte, G. [Dipartimento di Scienze del Farmaco, Facoltà di Farmacia, Università di Catania, Viale A. Doria, 6, I-95126 Catania (Italy); Angilella, G.G.N., E-mail: giuseppe.angilella@ct.infn.it [Dipartimento di Fisica e Astronomia, Università di Catania, 64, Via S. Sofia, I-95123 Catania (Italy); Scuola Superiore di Catania, Università di Catania, Via S. Nullo, 5/i, I-95123 Catania (Italy); CNISM, UdR Catania, 64, Via S. Sofia, I-95123 Catania (Italy); INFN, Sezione di Catania, 64, Via S. Sofia, I-95123 Catania (Italy); Pittalà, V. [Dipartimento di Scienze del Farmaco, Facoltà di Farmacia, Università di Catania, Viale A. Doria, 6, I-95126 Catania (Italy); March, N.H. [Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Oxford University, Oxford (United Kingdom); Pucci, R. [Dipartimento di Fisica e Astronomia, Università di Catania, 64, Via S. Sofia, I-95123 Catania (Italy); CNISM, UdR Catania, 64, Via S. Sofia, I-95123 Catania (Italy)

    2012-01-09

    Motivated by the theoretical study of Saito and Ono (2011) on three crystalline forms of SiO{sub 2} under pressure, quantum-chemical calculations on various free-space clusters of SiO{sub n} and GeO{sub n} for 1SiO{sub n} and GeO{sub n} clusters. ► Both neutral and cationic clusters. ► Varying coordination numbers. ► Relevant for high pressure studies.

  19. A study of the effect of binary oxide materials in a single droplet vapor explosion

    Energy Technology Data Exchange (ETDEWEB)

    Hansson, R.C., E-mail: rch@kth.se [Royal Institute of Technology, Stockholm (Sweden); Dinh, T.N.; Manickam, L.T. [Royal Institute of Technology, Stockholm (Sweden)

    2013-11-15

    In an effort to explore fundamental mechanisms that may govern the effect of melt material on vapor explosion's triggering, fine fragmentation and energetics, a series of experiments using a binary-oxide mixture with eutectic and non-eutectic compositions were performed. Interactions of a hot liquid (WO{sub 3}–CaO) droplet and a volatile liquid (water) were investigated in well-controlled, externally triggered, single-droplet experiments conducted in the Micro-interactions in steam explosion experiments (MISTEE) facility. The tests were visualized by means of a synchronized digital cinematography and continuous X-ray radiography system, called simultaneous high-speed acquisition of X-ray radiography and photography (SHARP). The acquired images followed by further analysis indicate milder interactions for the droplet with non-eutectic melt composition in the tests with low melt superheat, whereas no evident differences between eutectic and non-eutectic melt compositions regarding bubble dynamics, energetics and melt preconditioning was observed in the tests with higher melt superheat.

  20. The effect of binary oxide materials on a single droplet vapor explosion triggering

    Energy Technology Data Exchange (ETDEWEB)

    Hansson, R.C.; Manickam, L.T.; Dinh, T.N. [Royal Inst. of Tech., Stockholm (Sweden)

    2011-07-01

    In order to explore the fundamental mechanism dictated by the material influence on triggering, fine fragmentation and subsequent vapor explosion energetics, a series of experiments using a mixture of eutectic and non-eutectic binary oxide were initiated. Dynamics of the hot liquid (WO{sub 3}-CaO) droplet and the volatile liquid (water) were investigated in the MISTEE (Micro-Interactions in Steam Explosion Experiments) facility by performing well-controlled, externally triggered, single-droplet experiments, using a high-speed visualization system with synchronized digital cinematography and continuous X-ray radiography, called SHARP (Simultaneous High-speed Acquisition of X-ray Radiography and Photography). The acquired images followed by further analysis showed a milder interaction for the non-eutectic melt composition for the tests with low melt superheat, whether no evident differences between eutectic and non-eutectic melt compositions regarding bubble dynamics, energetics and melt preconditioning was perceived for the high melt superheat tests. (author)

  1. A study of the effect of binary oxide materials in a single droplet vapor explosion

    International Nuclear Information System (INIS)

    Hansson, R.C.; Dinh, T.N.; Manickam, L.T.

    2013-01-01

    In an effort to explore fundamental mechanisms that may govern the effect of melt material on vapor explosion's triggering, fine fragmentation and energetics, a series of experiments using a binary-oxide mixture with eutectic and non-eutectic compositions were performed. Interactions of a hot liquid (WO 3 –CaO) droplet and a volatile liquid (water) were investigated in well-controlled, externally triggered, single-droplet experiments conducted in the Micro-interactions in steam explosion experiments (MISTEE) facility. The tests were visualized by means of a synchronized digital cinematography and continuous X-ray radiography system, called simultaneous high-speed acquisition of X-ray radiography and photography (SHARP). The acquired images followed by further analysis indicate milder interactions for the droplet with non-eutectic melt composition in the tests with low melt superheat, whereas no evident differences between eutectic and non-eutectic melt compositions regarding bubble dynamics, energetics and melt preconditioning was observed in the tests with higher melt superheat

  2. Poly(ethylene oxide) Crystallization in Single Walled Carbon Nanotube Based Nanocomposites: Kinetics and Structural Consequences

    Energy Technology Data Exchange (ETDEWEB)

    T Chatterjee; A Lorenzo; R Krishnamoorti

    2011-12-31

    The overall isothermal crystallization behavior of poly(ethylene oxide) (PEO) in single walled carbon nanotube (SWNT) based nanocomposites is studied with a focus on growth kinetics and morphological evolution of PEO using differential scanning calorimetry and in-situ small angle x-ray scattering measurements respectively. The characteristic time for crystallization of PEO increases due to the presence of lithium dodecyl sulfate (LDS) stabilized carbon nanotubes. Further, analysis of crystallization data using the Lauritzen-Hoffman regime theory of crystal growth shows the PEO chains stiffen in presence of LDS with an increased energy barrier associated with the nucleation and crystal growth, and the nanotubes further act as a barrier to chain transport or enhance the efficacy of the LDS action. The energy penalty and diffusional barrier to chain transport in the nanocomposites disrupt the crystalline PEO helical conformation. This destabilization leads to preferential growth of local nuclei resulting in formation of thinner crystal lamellae and suggests that the crystallization kinetics is strongly affected by the nucleation and crystal growth events. This study is particularly interesting considering the suppression of the PEO crystallinity in presence of small fraction of Lithium ion based surfactant and carbon nanotubes.

  3. Modification of mechanical properties of single crystal aluminum oxide by ion beam induced structural changes

    International Nuclear Information System (INIS)

    Ensinger, W.; Nowak, R.; Horino, Y.; Baba, K.

    1993-01-01

    The mechanical behaviour of ceramics is essentially determined by their surface qualities. As a surface modification technique, ion implantation provides the possibility to modify the mechanical properties of ceramics. Highly energetic ions are implanted into the near-surface region of a material and modify its composition and structure. Ions of aluminum, oxygen, nickel and tantalum were implanted into single-crystal α-aluminum oxide. Three-point bending tests showed that an increase in flexural strength of up to 30% could be obtained after implantation of aluminum and oxygen. Nickel and tantalum ion implantation increased the fracture toughness. Indentation tests with Knoop and Vickers diamonds and comparison of the lengths of the developed radial cracks showed that ion implantation leads to a reaction in cracking. The observed effects are assigned to radiation induced structural changes of the ceramic. Ion bombardment leads to radiation damage and formation of compressive stress. In case of tantalum implantation, the implanted near-surface zone becomes amorphous. These effects make the ceramic more resistant to fracture. (orig.)

  4. Single Additive Enables 3D Printing of Highly Loaded Iron Oxide Suspensions.

    Science.gov (United States)

    Hodaei, Amin; Akhlaghi, Omid; Khani, Navid; Aytas, Tunahan; Sezer, Dilek; Tatli, Buse; Menceloglu, Yusuf Z; Koc, Bahattin; Akbulut, Ozge

    2018-03-21

    A single additive, a grafted copolymer, is designed to ensure the stability of suspensions of highly loaded iron oxide nanoparticles (IOPs) and to facilitate three-dimensional (3D) printing of these suspensions in the filament form. This poly (ethylene glycol)-grafted copolymer of N-[3(dimethylamino)propyl]methacrylamide and acrylic acid harnesses both electrostatic and steric repulsion to realize an optimum formulation for 3D printing. When used at 1.15 wt % (by the weight of IOPs), the suspension attains ∼81 wt % solid loading-96% of the theoretical limit as calculated by the Krieger-Dougherty equation. Rectangular, thick-walled toroidal, and thin-walled toroidal magnetic cores and a porous lattice structure are fabricated to demonstrate the utilization of this suspension as an ink for 3D printing. The electrical and magnetic properties of the magnetic cores are characterized through impedance spectroscopy (IS) and vibrating sample magnetometry (VSM), respectively. The IS indicates the possibility of utilizing wire-wound 3D printed cores as the inductive coils. The VSM verifies that the magnetic properties of IOPs before and after the ink formulation are kept almost unchanged because of the low dosage of the additive. This particle-targeted approach for the formulation of 3D printing inks allows embodiment of a fully aqueous system with utmost target material content.

  5. Solution-processed zinc oxide nanoparticles/single-walled carbon nanotubes hybrid thin-film transistors

    Science.gov (United States)

    Liu, Fangmei; Sun, Jia; Qian, Chuan; Hu, Xiaotao; Wu, Han; Huang, Yulan; Yang, Junliang

    2016-09-01

    Solution-processed thin-film transistors (TFTs) are the essential building blocks for manufacturing the low-cost and large-area consumptive electronics. Herein, solution-processed TFTs based on the composites of zinc oxide (ZnO) nanoparticles and single-walled carbon nanotubes (SWCNTs) were fabricated by the methods of spin-coating and doctor-blading. Through controlling the weight of SWCNTs, the ZnO/SWCNTs TFTs fabricated by spin-coating demonstrated a field-effect mobility of 4.7 cm2/Vs and a low threshold voltage of 0.8 V, while the TFTs devices fabricated by doctor-blading technique showed reasonable electrical performance with a mobility of 0.22 cm2/Vs. Furthermore, the ion-gel was used as an efficient electrochemical gate dielectric because of its large electric double-layer capacitance. The operating voltage of all the TFTs devices is as low as 4.0 V. The research suggests that ZnO/SWCNTs TFTs have the potential applications in low-cost, large-area and flexible consumptive electronics, such as chemical-biological sensors and smart label.

  6. Effects of SiO/sub 2/ on Y-Ba-Cu-O compound

    International Nuclear Information System (INIS)

    Shih, I.; Qiu, C.X.

    1988-01-01

    Using bulk samples of Y-Ba-Cu-O with different ratios of Y:Ba:Cu:Si (1:2:3:x), effect of Si on this material has been investigated. It was observed that after a short heat treatment, the resistance transition characteristics of the samples improved as the SiO/sub 2/ content was increased from 0 to 0.6. However, the samples degraded as the Si content was further increased from 0.6 to 1.0. The degradation was also found for the samples with low Si content after prolonged treatment

  7. AN OVERVIEW OF TRAINING METHODS THAT PROMOTE THE HIGHEST LIPID OXIDATION DURING AND AFTER A SINGLE EXERCISE SESSION

    Directory of Open Access Journals (Sweden)

    Barbara Purkart

    2016-02-01

    Full Text Available Given that physical activity is the most effective way to increase lipid oxidation, its effects are influenced by several factors. The goal of this review was to identify the most effective methods that facilitate the highest lipid oxidation during and after a single exercise session. For this purpose, the available scientific literature was examined using PubMed, Web of Science, Google Scholar and Cochrane Library databases up to June 2013 with the following keywords: excess post exercise oxygen consumption, exercise fatty acid, energy expenditure exercise and interval training. From the identified 48,583 potentially relevant references, 172 of them met all the required criteria. It was found out that prolonged (> 30 min moderate intensity (55 − 70 % VO2max exercise such as walking, jogging or cycling is the most effective way to increase lipid oxidation during and after a single exercise session. Low-volume high-intensity interval exercise is supposed to be as effective as traditional exercise with continuous endurance, with the main effect on lipid oxidation after the session and similar long-term metabolic adaptations. However, more research is still needed to compare the effects of regular resistance exercise with traditional endurance and high-intensity interval exercise. Finally, nutrition is also a significant factor since food rich in fat and low in carbohydrates promotes greater lipid oxidation.

  8. Self-assembly surface modified indium-tin oxide anodes for single-layer light-emitting diodes

    CERN Document Server

    Morgado, J; Charas, A; Matos, M; Alcacer, L; Cacialli, F

    2003-01-01

    We study the effect of indium-tin oxide surface modification by self assembling of highly polar molecules on the performance of single-layer light-emitting diodes (LEDs) fabricated with polyfluorene blends and aluminium cathodes. We find that the efficiency and light-output of such LEDs is comparable to, and sometimes better than, the values obtained for LEDs incorporating a hole injection layer of poly(3,4-ethylene dioxythiophene) doped with polystyrene sulphonic acid. This effect is attributed to the dipole-induced work function modification of indium-tin oxide.

  9. Thin film complementary metal oxide semiconductor (CMOS) device using a single-step deposition of the channel layer

    KAUST Repository

    Nayak, Pradipta K.

    2014-04-14

    We report, for the first time, the use of a single step deposition of semiconductor channel layer to simultaneously achieve both n-and p-type transport in transparent oxide thin film transistors (TFTs). This effect is achieved by controlling the concentration of hydroxyl groups (OH-groups) in the underlying gate dielectrics. The semiconducting tin oxide layer was deposited at room temperature, and the maximum device fabrication temperature was 350C. Both n and p-type TFTs showed fairly comparable performance. A functional CMOS inverter was fabricated using this novel scheme, indicating the potential use of our approach for various practical applications.

  10. Self-assembly surface modified indium-tin oxide anodes for single-layer light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Morgado, Jorge [Instituto de Telecomunicacoes and Departamento de Engenharia Quimica, Instituto Superior Tecnico, Avenida Rovisco Pais, P-1049-001 Lisbon (Portugal); Barbagallo, Nunzio [Instituto de Telecomunicacoes and Departamento de Engenharia Quimica, Instituto Superior Tecnico, Avenida Rovisco Pais, P-1049-001 Lisbon (Portugal); Charas, Ana [Instituto de Telecomunicacoes and Departamento de Engenharia Quimica, Instituto Superior Tecnico, Avenida Rovisco Pais, P-1049-001 Lisbon (Portugal); Matos, Manuel [Departamento de Engenharia Quimica, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emidio Navarro-1, P-1949-001 Lisbon (Portugal); Alcacer, Luis [Instituto de Telecomunicacoes and Departamento de Engenharia Quimica, Instituto Superior Tecnico, Avenida Rovisco Pais, P-1049-001 Lisbon (Portugal); Cacialli, Franco [Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT (United Kingdom)

    2003-03-07

    We study the effect of indium-tin oxide surface modification by self assembling of highly polar molecules on the performance of single-layer light-emitting diodes (LEDs) fabricated with polyfluorene blends and aluminium cathodes. We find that the efficiency and light-output of such LEDs is comparable to, and sometimes better than, the values obtained for LEDs incorporating a hole injection layer of poly(3,4-ethylene dioxythiophene) doped with polystyrene sulphonic acid. This effect is attributed to the dipole-induced work function modification of indium-tin oxide.

  11. Single-Chamber Solid Oxide Fuel Cell Technology—From Its Origins to Today’s State of the Art

    Directory of Open Access Journals (Sweden)

    Teko W. Napporn

    2010-01-01

    Full Text Available In single-chamber solid oxide fuel cells (SC-SOFCs, both anode and cathode are situated in a common gas chamber and are exposed to a mixture of fuel and oxidant. The working principle is based on the difference in catalytic activity of the electrodes for the respective anodic and cathodic reactions. The resulting difference in oxygen partial pressure between the electrodes leads to the generation of an open circuit voltage. Progress in SC-SOFC technology has enabled the generation of power outputs comparable to those of conventional SOFCs. This paper provides a detailed review of the development of SC-SOFC technology.

  12. Electrical characteristics of mixed Zr-Si oxide thin films prepared by ion beam induced chemical vapor deposition at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ferrer, F.J., E-mail: fjferrer@us.e [Centro Nacional de Aceleradores (CSIC - U. Sevilla), Av. Thomas A. Edison 7, E-41092 Sevilla (Spain); Frutos, F. [E.T.S. de Ingenieria Informatica, Avda. Reina Mercedes s/n, E-41012 Sevilla (Spain); Garcia-Lopez, J. [Centro Nacional de Aceleradores (CSIC - U. Sevilla), Av. Thomas A. Edison 7, E-41092 Sevilla (Spain); Jimenez, C. [Laboratoire de Materiaux et de Genie Physique, BP 257 - INPGrenoble Minatec - 3 parvis Louis Neel - 38016 Grenoble (France); Yubero, F. [Instituto de Ciencia de Materiales de Sevilla (CSIC - U. Sevilla), c/ Americo Vespucio 49, E-41092 Sevilla (Spain)

    2009-07-31

    Mixed Zr-Si oxide thin films have been prepared at room temperature by ion beam decomposition of organometallic volatile precursors. The films were flat and amorphous. They did not present phase segregation of the pure single oxides. A significant amount of impurities (-C-, -CH{sub x}, -OH, and other radicals coming from partially decomposed precursors) remained incorporated in the films after the deposition process. This effect is minimized if the Ar content in the O{sub 2}/Ar bombarding gas is maximized. Static permittivity and breakdown electrical field of the films were determined by capacitance-voltage and current-voltage electrical measurements. It is found that the static permittivity increases non-linearly from {approx} 4 for pure SiO{sub 2} to {approx} 15 for pure ZrO{sub 2}. Most of the dielectric failures in the films were due to extrinsic breakdown failures. The maximum breakdown electrical field decreases from {approx} 10.5 MV/cm for pure SiO{sub 2} to {approx} 45 MV/cm for pure ZrO{sub 2}. These characteristics are justified by high impurity content of the thin films. In addition, the analysis of the conduction mechanisms in the formed dielectrics is consistent to Schottky and Poole-Frenkel emission for low and high electric fields applied, respectively.

  13. Energetics of Intermediate Temperature Solid Oxide Fuel Cell Electrolytes: Singly and Doubly doped Ceria Systems

    Science.gov (United States)

    Buyukkilic, Salih

    Solid oxide fuel cells (SOFCs) have potential to convert chemical energy directly to electrical energy with high efficiency, with only water vapor as a by-product. However, the requirement of extremely high operating temperatures (~1000 °C) limits the use of SOFCs to only in large scale stationary applications. In order to make SOFCs a viable energy solution, enormous effort has been focused on lowering the operating temperatures below 700 °C. A low temperature operation would reduce manufacturing costs by slowing component degradation, lessening thermal mismatch problems, and sharply reducing costs of operation. In order to optimize SOFC applications, it is critical to understand the thermodynamic stabilities of electrolytes since they directly influence device stability, sustainability and performance. Rare-earth doped ceria electrolytes have emerged as promising materials for SOFC applications due to their high ionic conductivity at the intermediate temperatures (500--700 °C). However there is a fundamental lack of understanding regarding their structure, thermodynamic stability and properties. Therefore, the enthalpies of formation from constituent oxides and ionic conductivities were determined to investigate a relationship between the stability, composition, structural defects and ionic conductivity in rare earth doped ceria systems. For singly doped ceria electrolytes, we investigated the solid solution phase of bulk Ce1-xLnxO2-0.5x where Ln = Sm and Nd (0 ≤ x ≤ 0.30) and analyzed their enthalpies of formation, mixing and association, and bulk ionic conductivities while considering cation size mismatch and defect associations. It was shown that for ambient temperatures in the dilute dopant region, the positive heat of formation reaches a maximum as the system becomes increasingly less stable due to size mismatch. In concentrated region, stabilization to a certain solubility limit was observed probably due to the defect association of trivalent cations

  14. Endothelial nitric oxide synthase single nucleotide polymorphism and left ventricular function in early chronic kidney disease.

    Directory of Open Access Journals (Sweden)

    Sourabh Chand

    Full Text Available Chronic kidney disease (CKD is associated with accelerated cardiovascular disease and heart failure. Endothelial nitric oxide synthase (eNOS Glu298Asp single nucleotide polymorphism (SNP genotype has been associated with a worse phenotype amongst patients with established heart failure and in patients with progression of their renal disease. The association of a cardiac functional difference in non-dialysis CKD patients with no known previous heart failure, and eNOS gene variant is investigated.140 non-dialysis CKD patients, who had cardiac magnetic resonance (CMR imaging and tissue doppler echocardiography as part of two clinical trials, were genotyped for eNOS Glu298Asp SNP retrospectively.The median estimated glomerular filtration rate (eGFR was 50 mls/min and left ventricular ejection fraction (LVEF was 74% with no overt diastolic dysfunction in this cohort. There were significant differences in LVEF across eNOS genotypes with GG genotype being associated with a worse LVEF compared to other genotypes (LVEF: GG 71%, TG 76%, TT 73%, p = 0.006. After multivariate analysis, (adjusting for age, eGFR, baseline mean arterial pressure, contemporary CMR heart rate, total cholesterol, high sensitive C-reactive protein, body mass index and gender GG genotype was associated with a worse LVEF, and increased LV end-diastolic and systolic index (p = 0.004, 0.049 and 0.009 respectively.eNOS Glu298Asp rs1799983 polymorphism in CKD patients is associated with relevant sub-clinical cardiac remodelling as detected by CMR. This gene variant may therefore represent an important genetic biomarker, and possibly highlight pathways for intervention, in these patients who are at particular risk of worsening cardiac disease as their renal dysfunction progresses.

  15. Powerful greenhouse gas nitrous oxide adsorption onto intrinsic and Pd doped Single walled carbon nanotube

    Science.gov (United States)

    Yoosefian, Mehdi

    2017-01-01

    Density functional studies on the adsorption behavior of nitrous oxide (N2O) onto intrinsic carbon nanotube (CNT) and Pd-doped (5,5) single-walled carbon nanotube (Pd-CNT) have been reported. Introduction of Pd dopant facilitates in adsorption of N2O on the otherwise inert nanotube as observed from the adsorption energies and global reactivity descriptor values. Among three adsorption features of N2O onto CNT, the horizontal adsorption with Eads = -0.16 eV exhibits higher adsorption energy. On the other hand the Pd-CNT exhibit strong affinity toward gas molecule and would cause a huge increase in N2O adsorption energies. Chemical and electronic properties of CNT and Pd-CNT in the absence and presence of N2O were investigated. Adsorption of N2O gas molecule would affect the electronic conductance of Pd-CNT that can serve as a signal of gas sensors and the increased energy gaps demonstrate the formation of more stable systems. The atoms in molecules (AIM) theory and the natural bond orbital (NBO) calculations were performed to get more details about the nature and charge transfers in intermolecular interactions within adsorption process. As a final point, the density of states (DOSs) calculations was achieved to confirm previous results. According to our results, intrinsic CNT cannot act as a suitable adsorbent while Pd-CNT can be introduced as novel detectable complex for designing high sensitive, fast response and high efficient carbon nanotube based gas sensor to detect N2O gas as an air pollutant. Our results could provide helpful information for the design and fabrication of the N2O sensors.

  16. Evaluation of natural organic matter adsorption on Fe-Al binary oxide: Comparison with single metal oxides.

    Science.gov (United States)

    Kim, Kyung-Jo; Jang, Am

    2017-10-01

    The adsorption characteristics of three types of standard natural organic matter (NOM) on iron-aluminum (Fe-Al) binary oxide (FAO) and heated aluminum oxide (HAO) under natural surface water condition were investigated using various adsorption isotherms and kinetic models. FAO was synthesized by Fe oxide and Al oxide, mixed using the sol-gel hydrothermal method, and aluminum sulfate was used to make HAO. The amount of adsorbed NOM was increased to 79.6 mg g -1 for humic acid (HA), 101.1 mg g -1 for sodium alginate (SA) in the FAO, but the maximum adsorption capacity of bovine serum albumin (BSA) (461.3 mg g -1 ) was identified on the HAO. The adsorption of HA, BSA, and SA dramatically increased (>70%) on FAO in 5 min and HA was significantly removed (90%) among the three NOM. Mutual interaction among the adsorbed NOM (BSA) occurred on the HAO surface during adsorption due to formation of monolayer by protein molecules at neutral pH. The pseudo second order clearly represented the adsorption kinetics for both adsorbents. The equilibrium isotherm data of FAO was better exhibited by the Langmuir isotherm model than by the Freundlich isotherm, but HAO was a slightly non-linear Langmuir type. Also, the free energy, enthalpy, and entropy of adsorption were determined from the thermodynamic experiments. Adsorption on FAO was spontaneous and an exothermic process. Fluorescence excitation-emission matrix (FEEM) spectra were used to elucidate the variation in organic components. The results obtained suggests that the significant changes in the surface property of the adsorbent (large surface area, increased crystalline intensity, and fine particle size) were effectively determined by the Fe-synthesized Al oxide mixed using the sol-gel hydrothermal method. The results also suggest that the changes enhanced the adsorption capacity, whereby three NOM were notably removed on FAO regardless of NOM characteristics (hydrophobic and hydrophilic). Copyright © 2017 Elsevier

  17. Conversion of Methane into Methanol and Ethanol over Nickel Oxide on Ceria-Zirconia Catalysts in a Single Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Okolie, Chukwuemeka [School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW Atlanta GA 30332 USA; Belhseine, Yasmeen F. [School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW Atlanta GA 30332 USA; Lyu, Yimeng [School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW Atlanta GA 30332 USA; Yung, Matthew M. [National Renewable Energy Laboratory, Golden CO 80401 USA; Engelhard, Mark H. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Lab, Richland WA 99354 USA; Kovarik, Libor [Environmental Molecular Sciences Laboratory, Pacific Northwest National Lab, Richland WA 99354 USA; Stavitski, Eli [National Synchrotron Light Source II, Brookhaven National Laboratory, Upton NY 11973 USA; Sievers, Carsten [School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW Atlanta GA 30332 USA

    2017-09-26

    Direct conversion of methane into alcohols is a promising technology for converting stranded methane reserves into liquids that can be transported in pipelines and upgraded to value-added chemicals. We demonstrate that a catalyst consisting of small nickel oxide clusters supported on ceria-zirconia (NiO/CZ) can selectively oxidize methane to methanol and ethanol in a single, steady-state process at 723 K using O2 as an abundantly available oxidant. The presence of steam is required to obtain alcohols rather than CO2 as the product of catalytic combustion. The unusual activity of this catalyst is attributed to the synergy between the small Lewis acidic NiO clusters and the redox-active CZ support, which also stabilizes the small NiO clusters.

  18. Poly(acrylic acid)-directed synthesis of colloidally stable single domain magnetite nanoparticles via partial oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Altan, Cem L. [Department of Chemical Engineering, Yeditepe University, Istanbul 34755 (Turkey); Laboratory of Materials and Interface Chemistry & Soft Matter cryoTEM Research Unit, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven 5600 MB (Netherlands); Gurten, Berna [Department of Chemical Engineering, Yeditepe University, Istanbul 34755 (Turkey); Sadza, Roel [Laboratory of Materials and Interface Chemistry & Soft Matter cryoTEM Research Unit, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven 5600 MB (Netherlands); Yenigul, Elcin [Department of Chemical Engineering, Yeditepe University, Istanbul 34755 (Turkey); Sommerdijk, Nico A.J.M., E-mail: n.sommerdijk@tue.nl [Laboratory of Materials and Interface Chemistry & Soft Matter cryoTEM Research Unit, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven 5600 MB (Netherlands); Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven 5600 MB (Netherlands); Bucak, Seyda, E-mail: seyda@yeditepe.edu.tr [Department of Chemical Engineering, Yeditepe University, Istanbul 34755 (Turkey)

    2016-10-15

    Octahedral, single domain magnetite nanoparticles with average size of ~55 nm were synthesized through oxidative aging of a ferrous hydroxide (Fe(OH){sub 2}) precursor at high pH in water. The synthesis was also carried out in the presence of the hydrophilic polymer poly(acrylic acid). Presence of the polymer changed the particle morphology from octahedral to spherical while average size decreased to 40–50 nm. Although these particles have a tendency to precipitate due to their high magnetic moment, dispersions of these particles were obtained in the presence of this particular polymer which made the particles stable in water for several days making them suitable for various biotechnological applications such as cell separation owing to their low toxicity. - Highlights: • Stable, single domain magnetite nanoparticles are synthesized via partial oxidation. • Particles are readily stabilized in water by a biocompatible polymer. • Steric barrier is essential for the stabilization of large magnetite nanoparticles.

  19. Update of Continuous-Energy Data for Hydrogen and SiO>2 Thermal Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Conlin, Jeremy Lloyd [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Parsons, Donald Kent [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-23

    The Nuclear Data Team has released updated continuous-energy neutron data files for: 1) hydrogen, and 2) S (α; β) (thermal scattering) on SiO>2. A list of new ZAIDs and the data that is updated (Old ZAID) is given in Table 1. The old data are still accessible, but are not the default.

  20. Thermal oxidation of single crystal aluminum antimonide and materials having the same

    Energy Technology Data Exchange (ETDEWEB)

    Sherohman, John William; Yee, Jick Hong; Coombs, III, Arthur William; Wu, Kuang Jen J.

    2012-12-25

    In one embodiment, a method for forming a non-conductive crystalline oxide layer on an AlSb crystal includes heat treating an AlSb crystal in a partial vacuum atmosphere at a temperature conducive for air adsorbed molecules to desorb, surface molecule groups to decompose, and elemental Sb to evaporate from a surface of the AlSb crystal and exposing the AlSb crystal to an atmosphere comprising oxygen to form a crystalline oxide layer on the surface of the AlSb crystal. In another embodiment, a method for forming a non-conductive crystalline oxide layer on an AlSb crystal includes heat treating an AlSb crystal in a non-oxidizing atmosphere at a temperature conducive for decomposition of an amorphous oxidized surface layer and evaporation of elemental Sb from the AlSb crystal surface and forming stable oxides of Al and Sb from residual surface oxygen to form a crystalline oxide layer on the surface of the AlSb crystal.

  1. Visualized effect of oxidation on magnetic recording fidelity in pseudo-single-domain magnetite particles

    DEFF Research Database (Denmark)

    Almeida, Trevor P.; Kasama, Takeshi; Muxworthy, Adrian R.

    2014-01-01

    fidelity of Fe3O4 particles is greatly diminished over time by progressive oxidation to less magnetic iron oxides, such as maghemite (γ-Fe2O3), with consequent alteration of remanent magnetization potentially having important geological significance. Here we use the complementary techniques...... of environmental transmission electron microscopy and off-axis electron holography to induce and visualize the effects of oxidation on the magnetization of individual nanoscale Fe3O4 particles as they transform towards γ-Fe2O3. Magnetic induction maps demonstrate a change in both strength and direction of remanent...

  2. XRD and EXAFS studies on the structure of Er{sup 3+}-doped SiO{sub 2}-HfO{sub 2} glass-ceramic waveguides: Er{sup 3+}-activated HfO{sub 2} nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Afify, N D; Dalba, G [Dipartimento di Fisica, Universita di Trento, Via Sommarive 14, I-38123 Povo (Trento) (Italy); Rocca, F [IFN-CNR, Istituto di Fotonica e Nanotecnologie del Consiglio Nazionale delle Ricerche, Sezione ' FBK-CeFSA' di Trento, Via alla Cascata 56/C, I-38123 Povo (Trento) (Italy)], E-mail: rocca@science.unitn.it

    2009-06-07

    This paper describes the structure of Er{sup 3+}-doped SiO{sub 2}-HfO{sub 2} waveguides containing nanocrystals of HfO{sub 2}. Pure and 1 mol% Er{sup 3+}-doped 70SiO{sub 2}-30HfO{sub 2} films were deposited by the sol-gel method on amorphous SiO{sub 2} substrates using the dip-coating technique. Each waveguide has experienced a single thermal treatment at temperatures ranging from 900 to 1200 deg. C, for either short (30 min) or long (24 h) durations. Crystallization and microstructure were studied by x-ray diffraction (XRD). The local environments of hafnium and erbium ions were determined, respectively, from Hf and Er L{sub 3}-edges extended x-ray absorption fine structure (EXAFS) experiments. Both XRD and EXAFS results demonstrate the substitution of Hf{sup 4+} by Er{sup 3+} ions in the crystalline structure. XRD shows the nucleation of tetragonal HfO{sub 2} nanocrystals after heat treatment at 1000 deg. C for 30 min in the pure waveguide, and at 900 deg. C for 24 h in the waveguide doped with Er{sup 3+}. In both series, partial transformation from tetragonal to monoclinic HfO{sub 2} nanocrystals starts after heat treatment at 1100 deg. C for 24 h. The average crystallite size and size distribution can be controlled by thermal annealing temperature and duration, respectively, with brief treatment yielding a more homogeneous nanocrystal size.

  3. Effect of a 1-hour single bout of moderate-intensity exercise on fat oxidation kinetics.

    Science.gov (United States)

    Chenevière, Xavier; Borrani, Fabio; Ebenegger, Vincent; Gojanovic, Boris; Malatesta, Davide

    2009-12-01

    The present study aimed to examine the effects of a prior 1-hour continuous exercise bout (CONT) at an intensity (Fat(max)) that elicits the maximal fat oxidation (MFO) on the fat oxidation kinetics during a subsequent submaximal incremental test (IncrC). Twenty moderately trained subjects (9 men and 11 women) performed a graded test on a treadmill (Incr), with 3-minute stages and 1-km.h(-1) increments. Fat oxidation was measured using indirect calorimetry and plotted as a function of exercise intensity. A mathematical model (SIN) including 3 independent variables (dilatation, symmetry, and translation) was used to characterize the shape of fat oxidation kinetics and to determine Fat(max) and MFO. On a second visit, the subjects performed CONT at Fat(max) followed by IncrC. After CONT performed at 57% +/- 3% (means +/- SE) maximal oxygen uptake (Vo(2max)), the respiratory exchange ratio during IncrC was lower at every stage compared with Incr (P rates from 35% to 70% Vo(2max) (P .05), whereas symmetry tended to be greater in IncrC (P = .096). This study showed that the prior 1-hour continuous moderate-intensity exercise bout increased Fat(max), MFO, and fat oxidation rates over a wide range of intensities during the postexercise incremental test. Moreover, the shape of the postexercise fat oxidation kinetics tended to have a rightward asymmetry.

  4. Synthesis and electrochemical performance of mesoporous SiO{sub 2}–carbon nanofibers composite as anode materials for lithium secondary batteries

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Yura; Choi, Jin-Yeong [Department of Chemistry, Keimyung University (Korea, Republic of); Park, Heai-Ku [Department of Chemical Engineering, Keimyung University (Korea, Republic of); Bae, Jae Young [Department of Chemistry, Keimyung University (Korea, Republic of); Lee, Chang-Seop, E-mail: surfkm@kmu.ac.kr [Department of Chemistry, Keimyung University (Korea, Republic of)

    2016-10-15

    Highlights: • Mesoporous SiO{sub 2}–carbon nanofibers composite synthesized on Ni foam without any binder. • This composite was directly applied as anode material of Li secondary batteries. • Showed the highest initial (2420 mAh/g) and discharging (2092 mAh/g) capacity. • This material achieved a retention rate of 86.4% after 30 cycles. - Abstract: In this study, carbon nanofibers (CNFs) and mesoporous SiO{sub 2}–carbon nanofibers composite were synthesized and applied as the anode materials in lithium secondary batteries. CNFs and mesoporous SiO{sub 2}–CNFs composite were grown via chemical vapor deposition method with iron-copper catalysts. Mesoporous SiO{sub 2} materials were prepared by sol–gel method using tetraethylorthosilicate as the silica source and cetyltrimethylammoniumchloride as the template. Ethylene was used as the carbon source and passes into a quartz reactor of a tube furnace heated to 600 °C, and the temperature was maintained at 600 °C for 10 min to synthesize CNFs and mesoporous SiO{sub 2}–CNFs composite. The electrochemical characteristics of the as-prepared CNFs and mesoporous SiO{sub 2}–CNFs composite as the anode of lithium secondary batteries were investigated using a three-electrode cell. In particular, the mesoporous SiO{sub 2}–CNFs composites synthesized without binder after depositing mesoporous SiO{sub 2} on Ni foam showed the highest charging and discharging capacity and retention rate. The initial capacity (2420 mAh/g) of mesoporous SiO{sub 2}–CNFs composites decreased to 2092 mAh/g after 30 cycles at a retention rate of 86.4%.

  5. Compare analysis for the nanotoxicity effects of different amounts of endocytic iron oxide nanoparticles at single cell level.

    Science.gov (United States)

    Huang, Chen-Yu; Ger, Tzong-Rong; Wei, Zung-Hang; Lai, Mei-Feng

    2014-01-01

    Developing methods that evaluate the cellular uptake of magnetic nanoparticles (MNPs) and nanotoxicity effects at single-cellular level are needed. In this study, magnetophoresis combining fluorescence based cytotoxicity assay was proposed to assess the viability and the single-cellular MNPs uptake simultaneously. Malignant cells (SKHep-1, HepG2, HeLa) were incubated with 10 nm anionic iron oxide nanoparticles. Prussian blue stain was performed to visualize the distribution of magnetic nanoparticles. MTT and fluorescence based assay analyzed the cytotoxicity effects of the bulk cell population and single cell, respectively. DAPI/PI stained was applied to evaluate death mechanism. The number of intracellular MNPs was found to be strongly correlated with the cell death. Significant differences between cellular MNP uptake in living and dead cells were observed. The method could be useful for future study of the nanotoxicity induced by MNPs.

  6. Single-electron-occupation metal-oxide-semiconductor quantum dots formed from efficient poly-silicon gate layout

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, Malcolm S.; rochette, sophie; Rudolph, Martin; Roy, A. -M.; Curry, Matthew Jon; Ten Eyck, Gregory A.; Manginell, Ronald P.; Wendt, Joel R.; Pluym, Tammy; Carr, Stephen M; Ward, Daniel Robert; Lilly, Michael; pioro-ladriere, michel

    2017-07-01

    We introduce a silicon metal-oxide-semiconductor quantum dot structure that achieves dot-reservoir tunnel coupling control without a dedicated barrier gate. The elementary structure consists of two accumulation gates separated spatially by a gap, one gate accumulating a reservoir and the other a quantum dot. Control of the tunnel rate between the dot and the reservoir across the gap is demonstrated in the single electron regime by varying the reservoir accumulation gate voltage while compensating with the dot accumulation gate voltage. The method is then applied to a quantum dot connected in series to source and drain reservoirs, enabling transport down to the single electron regime. Finally, tuning of the valley splitting with the dot accumulation gate voltage is observed. This split accumulation gate structure creates silicon quantum dots of similar characteristics to other realizations but with less electrodes, in a single gate stack subtractive fabrication process that is fully compatible with silicon foundry manufacturing.

  7. Defects in electron irradiated vitreous SiO[sub 2] probed by positron annihiliation

    Energy Technology Data Exchange (ETDEWEB)

    Uedono, Akira; Tanigawa, Shoichiro (Tsukuba Univ., Ibaraki (Japan). Inst. of Materials Science); Kawano, Takao (Tsukuba Univ., Ibaraki (Japan). Radioisotope Centre); Itoh, Hisayoshi (Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment)

    1994-10-10

    Defects in 3 MeV electron irradiated vitreous SiO[sub 2] (v-SiO[sub 2]) were probed by the positron annihilation technique. For unirradiated v-SiO[sub 2] specimens, almost all positrons were found to annihilate from positronium (Ps) states. This high formation probability of Ps was attributed to the trapping of positrons by open-space defects. The formation probability of Ps was decreased by the electron irradiation. The observed inhibition of the Ps formation was attributed to the trapping of positrons by point defects introduced and/or activated by the irradiation. From measurements of the lifetime distribution of Ps, it was found that, by the electron irradiation, the mean size of open-space defects was decreased and the size distribution of such defects was broadened. (Author).

  8. Oxidant production and SOD1 protein expression in single skeletal myofibers from Down syndrome mice

    Directory of Open Access Journals (Sweden)

    Patrick M. Cowley

    2017-10-01

    Full Text Available Down syndrome (DS is a genetic condition caused by the triplication of chromosome 21. Persons with DS exhibit pronounced muscle weakness, which also occurs in the Ts65Dn mouse model of DS. Oxidative stress is thought to be an underlying factor in the development of DS-related pathologies including muscle dysfunction. High-levels of oxidative stress have been attributed to triplication and elevated expression of superoxide dismutase 1 (SOD1; a gene located on chromosome 21. The elevated expression of SOD1 is postulated to increase production of hydrogen peroxide and cause oxidative injury and cell death. However, it is unknown whether SOD1 protein expression is associated with greater oxidant production in skeletal muscle from Ts65Dn mice. Thus, our objective was to assess levels of SOD1 expression and oxidant production in skeletal myofibers from the flexor digitorum brevis obtained from Ts65Dn and control mice. Measurements of oxidant production were obtained from myofibers loaded with 2′,7′-dichlorodihydrofluorescein diacetate (DCFH2-DA in the basal state and following 15 min of stimulated unloaded contraction. Ts65Dn myofibers exhibited a significant decrease in basal DCF emissions (p 0.05. Myofibers from Ts65Dn mice tended to be smaller and myonuclear domain was lower (p < 0.05. In summary, myofibers from Ts65Dn mice exhibited decreased basal DCF emissions that were coupled with elevated protein expression of SOD1. Stimulated contraction in isolated myofibers did not affect DCF emissions in either group. These findings suggest the skeletal muscle dysfunction in the adult Ts65Dn mouse is not associated with skeletal muscle oxidative stress.

  9. Solid oxide electrolyser cell

    Energy Technology Data Exchange (ETDEWEB)

    Hoejgaard Jensen, S.

    2006-12-15

    Solid oxide fuel cells (SOFCs) produced at Riso National Laboratory was tested as steam electrolysers under various current densities, operating temperatures and steam partial pressures. At 950 deg. C and a cell voltage of 1.48V the current density was -3.6 A/cm{sup 2} with app. 30% H{sub 2} + 70% H{sub 2}O in the inlet gas and a H{sub 2}O utilization of app. 40%. The tested SOECs were also used for CO{sub 2} electrolysis. Economy studies of CO and H2 production show that especially H{sub 2} production can be competitive in areas with cheap electricity. Assuming the above described initial performance and a lifetime of 10 years it is possible to achieve a production price of 0.7 US dollar/kg H{sub 2} with an electricity price of 1.3 US cent/kWh. The cell voltage was measured as function of time. In test of about two month of duration a long-term degradation was observed. At 850 deg. C, -0.5 A/cm{sup 2} with 50 vol% H{sub 2} the degradation rate was app. 20 mV/1000h. It was shown that the degradation happens at Ni/YSZ-electrode. The long term degradation is probably caused by coarsening of the Ni-particles. After onset of electrolysis operation a transient passivation/reactivation phenomena with duration of several days was observed. It was shown that the phenomenon is attributed to the SiO{sub 2} contamination at the Ni/YSZ electrode-electrolyte interface. The SiO{sub 2} arises from the albite glass sealing (NaAlSi{sub 3}O{sub 8}) that surrounds the electrode. Si may enter the Ni/YSZ electrode via the reaction Si(OH){sub 4}(g) {r_reversible} SiO{sub 2}(l)+H{sub 2}O(g). At the active sites of the Ni/YSZ electrode steam is reduced via the reaction H{sub 2}O - 2e {yields} H{sub 2}+O{sup 2-} . This shifts the equilibrium of the first reaction to form SiO{sub 2}(l) at the active sites. After a certain time the sealing crystallizes and the SiO{sub 2}(l) evaporates from the active sites and the cell reactivates. The passivation is shown to relate to a build up of a

  10. A single iron site confined in a graphene matrix for the catalytic oxidation of benzene at room temperature.

    Science.gov (United States)

    Deng, Dehui; Chen, Xiaoqi; Yu, Liang; Wu, Xing; Liu, Qingfei; Liu, Yun; Yang, Huaixin; Tian, Huanfang; Hu, Yongfeng; Du, Peipei; Si, Rui; Wang, Junhu; Cui, Xiaoju; Li, Haobo; Xiao, Jianping; Xu, Tao; Deng, Jiao; Yang, Fan; Duchesne, Paul N; Zhang, Peng; Zhou, Jigang; Sun, Litao; Li, Jianqi; Pan, Xiulian; Bao, Xinhe

    2015-12-01

    Coordinatively unsaturated (CUS) iron sites are highly active in catalytic oxidation reactions; however, maintaining the CUS structure of iron during heterogeneous catalytic reactions is a great challenge. Here, we report a strategy to stabilize single-atom CUS iron sites by embedding highly dispersed FeN4 centers in the graphene matrix. The atomic structure of FeN4 centers in graphene was revealed for the first time by combining high-resolution transmission electron microscopy/high-angle annular dark-field scanning transmission electron microscopy with low-temperature scanning tunneling microscopy. These confined single-atom iron sites exhibit high performance in the direct catalytic oxidation of benzene to phenol at room temperature, with a conversion of 23.4% and a yield of 18.7%, and can even proceed efficiently at 0°C with a phenol yield of 8.3% after 24 hours. Both experimental measurements and density functional theory calculations indicate that the formation of the Fe═O intermediate structure is a key step to promoting the conversion of benzene to phenol. These findings could pave the way toward highly efficient nonprecious catalysts for low-temperature oxidation reactions in heterogeneous catalysis and electrocatalysis.

  11. Study of radiolytic effect on residual ethylene oxide in perfusion devices for single use by using gas chromatography

    International Nuclear Information System (INIS)

    Wang Mingsuo; Teng Weifang; Liu Keliang; Feng Jixin; Su Liaoyuan

    1993-01-01

    The efficiency of the 60 Co γ-rays irradiation induced elimination reaction of residual ethylene oxide (RETO) in the perfusion devices for single use conducted with RETO gas chromatography has been studied. The observations show: 1. the splinting reaction of RETO absorbed by the infusion sets after ethylene oxide (ETO) sterilization occurred accompanied with 4 kGy irradiation, therefore the relative elimination percentage (RELP) calculated from RETO is over 90%. 2. the optimum radiation conditions are as following irradiation dose 4 kGy, dose rate 8 Gy/min, irradiation temperature 20 degree C. 3. the RETO content within medical infusion sets at 2 weeks storing time after radiation was probably controlled under 2.0 ppm. 4. the radiation chemistry mechanism of the RETO elimination reaction is discussed in relation to the primary and secondary actions of elimination reaction

  12. Single photon sources in 4H-SiC metal-oxide-semiconductor field-effect transistors

    Science.gov (United States)

    Abe, Y.; Umeda, T.; Okamoto, M.; Kosugi, R.; Harada, S.; Haruyama, M.; Kada, W.; Hanaizumi, O.; Onoda, S.; Ohshima, T.

    2018-01-01

    We present single photon sources (SPSs) embedded in 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs). They are formed in the SiC/SiO2 interface regions of wet-oxidation C-face 4H-SiC MOSFETs and were not found in other C-face and Si-face MOSFETs. Their bright room-temperature photoluminescence (PL) was observed in the range from 550 to 750 nm and revealed variable multi-peak structures as well as variable peak shifts. We characterized a wide variety of their PL spectra as the inevitable variation of local atomic structures at the interface. Their polarization dependence indicates that they are formed at the SiC side of the interface. We also demonstrate that it is possible to switch on/off the SPSs by a bias voltage of the MOSFET.

  13. Oxidatively damaged DNA in rats exposed by oral gavage to C60 fullerenes and single-walled carbon nanotubes

    DEFF Research Database (Denmark)

    Folkmann, Janne K; Risom, Lotte; Jacobsen, Nicklas R

    2009-01-01

    BACKGROUND: C60 fullerenes and single-walled carbon nanotubes (SWCNT) are projected to be used in medicine and consumer products with potential human exposure. The hazardous effects of these particles are expected to involve oxidative stress with generation of oxidatively damaged DNA that might......, liver, and lung of rats after intragastric administration of pristine C60 fullerenes or SWCNT (0.064 or 0.64 mg/kg body weight) suspended in saline solution or corn oil. We investigated the regulation of DNA repair systems toward 8-oxodG in liver and lung tissue. RESULTS: Both doses of SWCNT increased...... of genotoxicity, whereas corn oil per se generated more genotoxicity than the particles. Although there was increased mRNA expression of 8-oxoguanine DNA glycosylase in the liver of C60 fullerene-treated rats, we found no significant increase in repair activity. CONCLUSIONS: Oral exposure to low doses of C60...

  14. Pt-Fe catalyst nanoparticles supported on single-wall carbon nanotubes: Direct synthesis and electrochemical performance for methanol oxidation

    Science.gov (United States)

    Ma, Xiaohui; Luo, Liqiang; Zhu, Limei; Yu, Liming; Sheng, Leimei; An, Kang; Ando, Yoshinori; Zhao, Xinluo

    2013-11-01

    Single-wall carbon nanotubes (SWCNTs) supported Pt-Fe nanoparticles have been prepared by one-step hydrogen arc discharge evaporation of carbon electrode containing both Pt and Fe metal elements. The formation of SWCNTs and Pt-Fe nanoparticles occur simultaneously during the evaporation process. High-temperature hydrogen treatment and hydrochloric acid soaking have been carried out to purify and activate those materials in order to obtain a new type of Pt-Fe/SWCNTs catalyst for methanol oxidation. The Pt-Fe/SWCNTs catalyst performs much higher electrocatalytic activity for methanol oxidation, better stability and better durability than a commercial Pt/C catalyst according to the electrochemical measurements, indicating that it has a great potential for applications in direct methanol fuel cells.

  15. Promoting mechanism of N-doped single-walled carbon nanotubes for O2 dissociation and SO2 oxidation

    Science.gov (United States)

    Chen, Yanqiu; Yin, Shi; Chen, Yang; Cen, Wanglai; Li, Jianjun; Yin, Huaqiang

    2018-03-01

    Although heteroatom doping in carbon based catalysts have recently received intensive attentions, the role of the intrinsically porous structure of practical carbon materials and their potential synergy with doping atoms are still unclear. To investigate the complex effects, a range of N-doped single-walled carbon nanotubes (SWCNTs) were used to investigate their potential use for O2 dissociation and the subsequent SO2 oxidation using density functional theory. It is found that graphite N doping can synergize with the outer surface of SWCNTs to facilitate the dissociation of O2. The barrier for the dissociation on dual graphite N-doped SWCNT-(8, 8) is as low as 0.3 eV, and the subsequent SO2 oxidation is thermodynamically favorable and kinetically feasible. These results spotlight on developing promising carboncatalyst via utilization of porous gemometry and heteroatom-doping of carbon materials simultaneously.

  16. Oxidative stress in patients with type 1 diabetes mellitus: is it affected by a single bout of prolonged exercise?

    Directory of Open Access Journals (Sweden)

    Maria Pia Francescato

    Full Text Available Presently, no clear-cut guidelines are available to suggest the more appropriate physical activity for patients with type 1 diabetes mellitus due to paucity of experimental data obtained under patients' usual life conditions. Accordingly, we explored the oxidative stress levels associated with a prolonged moderate intensity, but fatiguing, exercise performed under usual therapy in patients with type 1 diabetes mellitus and matched healthy controls. Eight patients (4 men, 4 women; 49±11 years; Body Mass Index 25.0±3.2 kg·m(-2; HbA1c 57±10 mmol·mol(-1 and 14 controls (8 men, 6 women; 47±11 years; Body Mass Index 24.3±3.3 kg·m(-2 performed a 3-h walk at 30% of their heart rate reserve. Venous blood samples were obtained before and at the end of the exercise for clinical chemistry analysis and antioxidant capacity. Capillary blood samples were taken at the start and thereafter every 30 min to determine lipid peroxidation. Patients showed higher oxidative stress values as compared to controls (95.9±9.7 vs. 74.1±12.2 mg·L(-1 H2O2; p<0.001. In both groups, oxidative stress remained constant throughout the exercise (p = NS, while oxidative defence increased significantly at the end of exercise (p<0.02 from 1.16±0.13 to 1.19±0.10 mmol·L(-1 Trolox in patients and from 1.09±0.21 to 1.22±0.14 mmol·L(-1 Trolox in controls, without any significant difference between the two groups. Oxidative stress was positively correlated to HbA1c (p<0.005 and negatively related with uric acid (p<0.005. In conclusion, we were the first to evaluate the oxidative stress in patients with type 1 diabetes exercising under their usual life conditions (i.e. usual therapy and diet. Specifically, we found that the oxidative stress was not exacerbated due to a single bout of prolonged moderate intensity aerobic exercise, a condition simulating several outdoor leisure time physical activities. Oxidative defence increased in both patients and controls, suggesting

  17. Oxidant-antioxidant status in Egyptian children with sickle cell anemia: a single center based study

    Directory of Open Access Journals (Sweden)

    Mona Kamal El-Ghamrawy

    2014-05-01

    Conclusion: children with sickle cell anemia have chronic oxidative stress that may result inincreased VOC, and decreased serum nitrite may be associated with increases in VOC frequency. A novel finding in this study is the decrease in PON level in these patients, which is an interesting subject for further research.

  18. Electrocatalytic detection of dopamine at single-walled carbon nanotubes–iron (III) oxide nanoparticles platform

    CSIR Research Space (South Africa)

    Adekunle, AS

    2010-06-01

    Full Text Available Electrochemical sensors using edge-plane pyrolytic graphite electrode (EPPGEs) modified with singlewall carbon nanotubes–iron (III) oxide (SWCNT/Fe2O3) nanoparticles for the sensitive detection of dopamine (DA) are described for the first time...

  19. Oxidized Single-Walled Carbon Nanotubes (SWCNs-COOH) as a ...

    African Journals Online (AJOL)

    Nano-materials are considered as suitable heterogeneous catalysts for many organic reactions. Herein oxidized carbon nanotube (SWCNTs-COOH) has been reported as a heterogeneous catalyst, for protection of carbonyl groups as hydrazones in EtOH at 80 °C. The reactions proceed smoothly with good to excellent ...

  20. Oxidized Base Damage and Single-Strand Break Repair in Mammalian Genomes: Role of Disordered Regions and Posttranslational Modifications in Early Enzymes

    OpenAIRE

    Hegde, Muralidhar L.; Izumi, Tadahide; Mitra, Sankar

    2012-01-01

    Oxidative genome damage induced by reactive oxygen species includes oxidized bases, abasic (AP) sites, and single-strand breaks, all of which are repaired via the evolutionarily conserved base excision repair/single-strand break repair (BER/SSBR) pathway. BER/SSBR in mammalian cells is complex, with preferred and backup sub-pathways, and is linked to genome replication and transcription. The early BER/SSBR enzymes, namely, DNA glycosylases (DGs) and the end-processing proteins such as abasic ...

  1. Quantum dot resonant tunneling diode single photon detector with aluminum oxide aperture defined tunneling area

    DEFF Research Database (Denmark)

    Li, H.W.; Kardynal, Beata; Ellis, D.J.P.

    2008-01-01

    Quantum dot resonant tunneling diode single photon detector with independently defined absorption and sensing areas is demonstrated. The device, in which the tunneling is constricted to an aperture in an insulating layer in the emitter, shows electrical characteristics typical of high quality...... resonant tunneling diodes. A single photon detection efficiency of 2.1%+/- 0.1% at 685 nm was measured corresponding to an internal quantum efficiency of 14%. The devices are simple to fabricate, robust, and show promise for large absorption area single photon detectors based on quantum dot structures....

  2. Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

    International Nuclear Information System (INIS)

    Wang, Jun-Hua; Wang, Jin; Lu, Yan; Du, Mao-Hua; Han, Fu-Zhu

    2015-01-01

    Highlights: • Single pulse energy remarkably influences the properties of ceramic coating prepared by MAO on Ti alloy. • The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. • The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. • Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. • The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle. - Abstract: The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti–6Al–4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO 2 , anatase TiO 2 , and a large amount of Al 2 TiO 5 . The effects of single pulse

  3. Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun-Hua [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Wang, Jin [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Beijing 100084 (China); Lu, Yan [School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Du, Mao-Hua [Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Han, Fu-Zhu, E-mail: hanfuzhu@mail.tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Beijing 100084 (China)

    2015-01-01

    Highlights: • Single pulse energy remarkably influences the properties of ceramic coating prepared by MAO on Ti alloy. • The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. • The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. • Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. • The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle. - Abstract: The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti–6Al–4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO{sub 2}, anatase TiO{sub 2}, and a large amount of Al{sub 2}TiO{sub 5}. The effects of

  4. Transient oxidative stress and inflammation after intraperitoneal administration of multiwalled carbon nanotubes functionalized with single strand DNA in rats

    Energy Technology Data Exchange (ETDEWEB)

    Clichici, Simona, E-mail: simonaclichici@yahoo.com [Department of Physiology, University of Medicine and Pharmacy, Cluj-Napoca (Romania); Biris, Alexandru Radu [National R and D Institute of Isotopic and Molecular Technologies, Cluj-Napoca (Romania); Tabaran, Flaviu [University of Agricultural Sciences and Veterinary Medicine, Cluj-Napoca (Romania); Filip, Adriana [Department of Physiology, University of Medicine and Pharmacy, Cluj-Napoca (Romania)

    2012-03-15

    Multi-walled carbon nanotubes (MWCNTs) are widely used for nanotechnology. Their impact on living organisms is, however, not entirely clarified. Oxidative stress and inflammation seem to be the key mechanisms involved in MWCNTs' cytotoxicity. Until present, pulmonary and skin models were the main tested experimental designs to assess carbon nanotubes' toxicity. The systemic administration of MWCNTs is essential, with respect for future medical applications. Our research is performed on Wistar rats and is focused on the dynamics of oxidative stress parameters in blood and liver and pro-inflammatory cytokines in liver, after single dose (270 mg l{sup −1}) ip administration of MWCNTs (exterior diameter 15–25 nm, interior diameter 10–15 nm, surface 88 m{sup 2} g{sup −1}) functionalized with single strand DNA (ss-DNA). The presence of MWCNTs in blood was assessed by Raman spectroscopy, while in liver histological examination and confocal microscopy were used. It was found that ss-DNA-MWCNTs induce oxidative stress in plasma and liver, with the return of the tested parameters to normal values, 6 h after ip injection of nanotubes, with the exception of reduced glutathione in plasma. The inflammatory cytokines (TNF-α, IL-1β) had a similar pattern of evolution. We also assessed the level of ERK1/2 and the phosphorylation of p65 subunit of NF-kB in liver that had a transient increase and returned to normal at the end of the tested period. Our results demonstrate that ss-DNA-MWCNTs produce oxidative stress and inflammation, but with a transient pattern. Given the fact that antioxidants modify the profile not only for oxidative stress, but also of inflammation, the dynamics of these alterations may be of practical importance for future protective strategies. -- Highlights: ► ss-DNA-MWCNTs ip administration induce oxidative stress in plasma and liver. ► ss-DNA-MWCNTs ip administration determine liver inflammation. ► ERK1/2 and p65 phosphorylated NF

  5. Study on the sweep gas effect on the surface of Li{sub 4}SiO{sub 4} by means of work function measurement

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Atsushi; Yamaguchi, Kenji; Yamawaki, Michio [Tokyo Univ. (Japan)

    1998-03-01

    In the establishment of fuel cycle of tritium, it is important to make research on how the sweep gas composition affects the surface properties of breeder materials and the release of tritium from the surface of them. In this study, the change of contact potential difference (CPD) between Li{sub 4}SiO{sub 4} and Pt was measured in various gas compositions with a high temperature Kelvin probe. The work function change of Li{sub 4}SiO{sub 4} was obtained from the measured CPD and the work function change of Pt which was estimated from blank tests. From the results, the effect of oxygen deficient layer near the surface of Li{sub 4}SiO{sub 4} was observed, and the effect of OH{sup -} at the surface of Li{sub 4}SiO{sub 4} was considered. (author)

  6. Surface Adsorption and Replacement of Acid-Oxidized Single-Walled Carbon Nanotubes and Poly(vinyl pyrrolidone Chains

    Directory of Open Access Journals (Sweden)

    Wei Chen

    2007-01-01

    Full Text Available Quartz crystal microbalance (QCM was used to investigate the adsorption of acid-oxidized single-walled carbon nanotubes (Ox-SWNTs and poly(vinyl pyrrolidone, PVP. It was found for the first time that Ox-SWNTs adsorbed onto the QCM electrode can be effectively replaced by PVP chains in an aqueous solution. This replacement process was also investigated by atomic force miscroscopic (AFM imaging, which shows good agreement with the QCM measurements. This study provides powerful tools for fundamental investigation of polymer-nanotube interactions and for controlled design/fabrication of functional polymer-nanotube surfaces for potential applications.

  7. Oxidative stress in patients with type 1 diabetes mellitus: is it affected by a single bout of prolonged exercise?

    Science.gov (United States)

    Francescato, Maria Pia; Stel, Giuliana; Geat, Mario; Cauci, Sabina

    2014-01-01

    Presently, no clear-cut guidelines are available to suggest the more appropriate physical activity for patients with type 1 diabetes mellitus due to paucity of experimental data obtained under patients' usual life conditions. Accordingly, we explored the oxidative stress levels associated with a prolonged moderate intensity, but fatiguing, exercise performed under usual therapy in patients with type 1 diabetes mellitus and matched healthy controls. Eight patients (4 men, 4 women; 49±11 years; Body Mass Index 25.0±3.2 kg·m(-2); HbA1c 57±10 mmol·mol(-1)) and 14 controls (8 men, 6 women; 47±11 years; Body Mass Index 24.3±3.3 kg·m(-2)) performed a 3-h walk at 30% of their heart rate reserve. Venous blood samples were obtained before and at the end of the exercise for clinical chemistry analysis and antioxidant capacity. Capillary blood samples were taken at the start and thereafter every 30 min to determine lipid peroxidation. Patients showed higher oxidative stress values as compared to controls (95.9±9.7 vs. 74.1±12.2 mg·L(-1) H2O2; pexercise (p = NS), while oxidative defence increased significantly at the end of exercise (pdiabetes exercising under their usual life conditions (i.e. usual therapy and diet). Specifically, we found that the oxidative stress was not exacerbated due to a single bout of prolonged moderate intensity aerobic exercise, a condition simulating several outdoor leisure time physical activities. Oxidative defence increased in both patients and controls, suggesting beneficial effects of prolonged aerobic fatiguing exercise.

  8. Nanoparticles of Pt and Ag supported in meso porous SiO{sub 2}: characterization and catalytic applications; Nanoparticulas de Pt y Ag soportadas en SiO{sub 2} mesoporosa: caracterizacion y aplicaciones cataliticas

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa, M.E.; Perez H, R.; Perez A, M.; Mondragon G, G. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Arenas A, J. [IFUNAM, A.P. 20-364, 01000 Mexico D.F. (Mexico)

    2004-07-01

    The surface properties of catalysts of Pt and Ag supported in conventional SiO{sub 2} hey have been studied through reduction reactions of N{sub 2}O with H{sub 2} which is a sensitive reaction to the structure. In our case it was used a meso porous ceramic support of SiO{sub 2} of great surface area (1100 m{sup 2}/gr), where it is caused a high dispersion of the metallic nanoparticles of Pt and Ag, the total charge of the active phase in the meso porous support was of 3% in weight. The catalysts show a variation in the percentages of conversion of N{sub 2}O depending on the size and dispersion of the metallic phases. (Author)

  9. Nano-structure formation of Fe-Pt perpendicular magnetic recording media co-deposited with MgO, Al{sub 2}O{sub 3} and SiO{sub 2} additives

    Energy Technology Data Exchange (ETDEWEB)

    Safran, G. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences 1121 Budapest, Konkoly-Thege ut 29-33 (Hungary)]. E-mail: safran@mfa.kfki.hu; Suzuki, T. [Akita Research Institute of Advanced Technology (AIT), 4-21 Sanuki, Araya, Akita 010-1623 (Japan); Ouchi, K. [Akita Research Institute of Advanced Technology (AIT), 4-21 Sanuki, Araya, Akita 010-1623 (Japan); Barna, P.B. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences 1121 Budapest, Konkoly-Thege ut 29-33 (Hungary); Radnoczi, G. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences 1121 Budapest, Konkoly-Thege ut 29-33 (Hungary)

    2006-02-21

    Perpendicular magnetic recording media samples were prepared by sputter deposition on sapphire with a layer sequence of MgO seed-layer/Cr under-layer/FeSi soft magnetic under-layer/MgO intermediate layer/FePt-oxide recording layer. The effects of MgO, Al{sub 2}O{sub 3} and SiO{sub 2} additives on the morphology and orientation of the FePt layer were investigated by transmission electron microscopy. The samples exhibited (001) orientation of the L1 FePt phase with the mutual orientations of sapphire substrate//MgO(100)[001]//Cr(100)[11-bar0]//FeSi(100)[11-bar0]//MgO(100) [001]//FePt(001)[100]. The morphology of the FePt films varied due to the co-deposited oxides: The FePt layers were continuous and segmented by stacking faults aligned at 54{sup o} to the surface. Films with SiO{sub 2} addition, beside the oriented columnar FePt grains, exhibited a fraction of misoriented crystallites due to random repeated nucleation. Al{sub 2}O{sub 3} addition resulted in a layered structure, i.e. an initial continuous epitaxial FePt layer covered by a secondary layer of FePt-Al{sub 2}O{sub 3} composite. Both components (FePt and MgO) of the MgO-added samples were grown epitaxially on the MgO intermediate layer, so that a nano-composite of intercalated (001) FePt and (001) MgO was formed. The revealed microstructures and formation mechanisms may facilitate the improvement of the structural and magnetic properties of the FePt-oxide composite perpendicular magnetic recording media.

  10. Fluidity evaluation of cell membrane model formed on graphene oxide with single particle tracking using quantum dot

    Science.gov (United States)

    Okamoto, Yoshiaki; Motegi, Toshinori; Iwasa, Seiji; Sandhu, Adarsh; Tero, Ryugo

    2015-04-01

    The lipid bilayer is the fundamental structure of plasma membranes, and artificial lipid bilayer membranes are used as model systems of cell membranes. Recently we reported the formation of a supported lipid bilayer (SLB) on graphene oxide (GO) by the vesicle fusion method. In this study, we conjugated a quantum dot (Qdot) on the SLB surface as a fluorescence probe brighter than dye-labeled lipid molecules, to qualitatively evaluate the fluidity of the SLB on GO by the single particle tracking method. We obtained the diffusion coefficient of the Qdot-conjugated lipids in the SLB on GO. We also performed the Qdot conjugation on the SLB containing a lipid conjugated with polyethylene glycol, to prevent the nonspecific adsorption of Qdots. The difference in the diffusion coefficients between the SLBs on the GO and the bare SiO2 regions was evaluated from the trajectory of single Qdot-conjugated lipid diffusing between the two regions.

  11. Investigation of distribution microhomogeneity of doped elements in oxide single crystals by means of LMA-AES

    International Nuclear Information System (INIS)

    Nikolova, L.; Krasnobaeva, N.; Manuilov, N.

    1989-01-01

    The distribution of V and Ti in oxide single crystals Al 2 O 3 :V 3+ , Y 3 Al 5 O 12 :V 3+ , Al 2 O 3 :Ti 3+ , Y 3 Al 5 O 12 :Ti 3+ is investigated by laser emission microspectral analysis with photographic registration of spectra. Single crystals have been grown by the method of vertical directed crystallization (method of Bridgman-Stockbarger). For evaluation of microhomogeneity of the investigated elements distribution the following statistical methods are applied: one-way variance analysis, two-way variance analysis, regression models and gradient method. A PC programme package is developed allowing to process photoregistration data, to choose the internal standard line by scatter diagrams, to perform all statistical analysis and to plot the distribution diagrams of the elements in the samples. 2 refs. (author)

  12. Transport and abatement of fluorescent silica nanoparticle (SiO{sub 2} NP) in granular filtration: effect of porous media and ionic strength

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Chao, E-mail: chaozeng@email.arizona.edu; Shadman, Farhang; Sierra-Alvarez, Reyes [University of Arizona, Department of Chemical and Environmental Engineering (United States)

    2017-03-15

    The extensive production and application of engineered silica nanoparticles (SiO{sub 2} NPs) will inevitably lead to their release into the environment. Granular media filtration, a widely used process in water and wastewater treatment plants, has the potential for NP abatement. In this work, laboratory-scale column experiments were performed to study the transport and retention of SiO{sub 2} NPs on three widely used porous materials, i.e., sand, anthracite, and granular activated carbon (GAC). Synthetic fluorescent core-shell SiO{sub 2} NPs (83 nm) were used to facilitate NP detection. Sand showed very low capacity for SiO{sub 2} filtration as this material had a surface with limited surface area and a high concentration of negative charge. Also, we found that the stability and transport of SiO{sub 2} NP were strongly dependent on the ionic strength of the solution. Increasing ionic strength led to NP agglomeration and facilitated SiO{sub 2} NP retention, while low ionic strength resulted in release of captured NPs from the sand bed. Compared to sand, anthracite and GAC showed higher affinity for SiO{sub 2} NP capture. The superior capacity of GAC was primarily due to its porous structure and high surface area. A process model was developed to simulate NP capture in the packed bed columns and determine fundamental filtration parameters. This model provided an excellent fit to the experimental data. Taken together, the results obtained indicate that GAC is an interesting material for SiO{sub 2} NP filtration.

  13. Linalool prevents oxidative stress activated protein kinases in single UVB-exposed human skin cells.

    Science.gov (United States)

    Gunaseelan, Srithar; Balupillai, Agilan; Govindasamy, Kanimozhi; Ramasamy, Karthikeyan; Muthusamy, Ganesan; Shanmugam, Mohana; Thangaiyan, Radhiga; Robert, Beaulah Mary; Prasad Nagarajan, Rajendra; Ponniresan, Veeramani Kandan; Rathinaraj, Pierson

    2017-01-01

    Ultraviolet-B radiation (285-320 nm) elicits a number of cellular signaling elements. We investigated the preventive effect of linalool, a natural monoterpene, against UVB-induced oxidative imbalance, activation of mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB) signaling in HDFa cells. We observed that linalool treatment (30 μM) prevented acute UVB-irradiation (20 mJ/cm2) mediated loss of activities of antioxidant enzymes in HDFa cells. The comet assay results illustrate that linalool significantly prevents UVB-mediated 8-deoxy guanosine formation (oxidative DNA damage) rather than UVB-induced cyclobutane pyrimidine (CPD) formation. This might be due to its ability to prevent UVB-induced ROS formation and to restore the oxidative imbalance of cells. This has been reflected in UVB-induced overexpression of MAPK and NF-κB signaling. We observed that linalool inhibited UVB-induced phosphorylation of ERK1, JNK and p38 proteins of MAPK family. Linalool inhibited UVB-induced activation of NF-κB/p65 by activating IκBa. We further observed that UVB-induced expression of TNF-α, IL6, IL-10, MMP-2 and MMP-9 was modulated by linalool treatment in HDFa cells. Thus, linalool protects the human skin cells from the oxidative damages of UVB radiation and modulates MAPK and NF-κB signaling in HDFa cells. The present findings substantiate that linalool may act as a photoprotective agent against UVB-induced skin damages.

  14. Effect of oxidation annealing on optical properties of YAG:Ce single crystals

    Czech Academy of Sciences Publication Activity Database

    Bok, Jan; Horodyský, P.; Krzyžánek, Vladislav

    2015-01-01

    Roč. 46, AUG 2015 (2015), s. 591-595 ISSN 0925- 3467 R&D Projects: GA TA ČR(CZ) TE01020118; GA ČR(CZ) GA14-20012S; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : scintillator * YAG:Ce * oxidation annealing * charge transfer * cathodoluminiscence Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.183, year: 2015

  15. MeV ion irradiation effects on the luminescence properties of Si-implanted SiO{sub 2}-thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chulapakorn, T.; Primetzhofer, D. [Uppsala University, Department of Physics and Astronomy, P.O. Box 516, 751 20 Uppsala (Sweden); Sychugov, I.; Suvanam, S.S.; Linnros, J.; Hallen, A. [Royal Institute of Technology (KTH), School of Information and Communication Technology, P.O. Box Electrum 229, 164 40 Kista (Sweden)

    2016-12-15

    The effects of MeV heavy ion irradiation at varying fluence and flux on excess Si, introduced in SiO{sub 2} by keV ion implantation, are investigated by photoluminescence (PL). From the PL peak wavelength (λ) and decay lifetime (τ), two PL sources are distinguished: (i) quasi-direct recombination of excitons of Si-nanoparticles (SiNPs), appearing after thermal annealing (λ > 720 nm, τ ∝ μs), and (ii) fast-decay PL, possibly due to oxide-related defects (λ ∝ 575-690 nm, τ ∝ ns). The fast-decay PL (ii) observed before and after ion irradiation is induced by ion implantation. It is found that this fast-decay luminescence decreases for higher irradiation fluence of MeV heavy ions. After thermal annealing (forming SiNPs), the SiNP PL is reduced for samples irradiated by MeV heavy ions but found to stabilize at higher level for higher irradiation flux; the (ii) band vanishes as a result of annealing. The results are discussed in terms of the influence of electronic and nuclear stopping powers. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Enhanced Au induced lateral crystallization in electron-irradiated amorphous Ge on SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sakiyama, Shin; Kaneko, Takahiro; Ootsubo, Takanobu; Sakai, Takatsugu; Nakashima, Kazutoshi; Moto, Kenta; Yoneoka, Masashi; Takakura, Kenichiro; Tsunoda, Isao, E-mail: isao_tsunoda@kumamoto-nct.ac.jp

    2014-04-30

    We have investigated the low temperature of Au induced lateral crystallization of electron irradiated amorphous Ge on SiO{sub 2}/Si substrate. The reduction of the critical annealing time to cause the Au induced lateral crystallization is realized by high energy electron irradiation. In addition, the lateral crystallization region of the sample with electron irradiation has high crystalline quality as well as the sample without electron irradiation. We have speculated that the Au induced lateral crystallization of amorphous Ge on SiO{sub 2}/Si substrate was enhanced by electron irradiation, due to the introduction of point defects into amorphous Ge able to diffuse easily of Au atoms. - Highlights: • Au induced lateral crystallization of electron irradiated Ge is investigated. • Crystallization annealing time is significantly reduced. • High crystalline quality of lateral region was not changed by electron irradiation.

  17. Pre-hydrolysed ethyl silicate as an alternative precursor for SiO{sub 2}-coated carbon nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Barrena, M.I., E-mail: ibarrena@quim.ucm.es [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Av. Complutense s/n, 28040 Madrid (Spain); Gomez de Salazar, J.M.; Soria, A.; Matesanz, L. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Av. Complutense s/n, 28040 Madrid (Spain)

    2011-11-15

    This work reported basically aims at understanding the extent of SiO{sub 2}-coated carbon nanofibers using two different sol-gel precursors for the silicate glass. The silicate precursors employed were tetraethoxysilane (TEOS) and pre-hydrolysed ethyl silicate. The first route consisted in an acid hydrolysis and polycondensation of the TEOS and the second one in a polycondensation of the pre-hydrolysed ethyl silicate. The techniques of Fourier Infra Red spectroscopy, thermogravimetric analysis, scanning electron microscopy and X-ray diffraction were used to characterize the materials obtained. Both kinds of SiO{sub 2} precursor can coat the CNF effectively. However, the use of pre-hydrolysed ethyl silicate (faster gelation times and higher surface areas) can be considered a low-cost and facile alternative with respect to the use of TEOS, to obtain industrially silica-coated carbon nanofibers.

  18. Thermally stable single atom Pt/m-Al2O3 for selective hydrogenation and CO oxidation

    KAUST Repository

    Zhang, Zailei

    2017-07-27

    Single-atom metal catalysts offer a promising way to utilize precious noble metal elements more effectively, provided that they are catalytically active and sufficiently stable. Herein, we report a synthetic strategy for Pt single-atom catalysts with outstanding stability in several reactions under demanding conditions. The Pt atoms are firmly anchored in the internal surface of mesoporous Al2O3, likely stabilized by coordinatively unsaturated pentahedral Al3+ centres. The catalyst keeps its structural integrity and excellent performance for the selective hydrogenation of 1,3-butadiene after exposure to a reductive atmosphere at 200 °C for 24 h. Compared to commercial Pt nanoparticle catalyst on Al2O3 and control samples, this system exhibits significantly enhanced stability and performance for n-hexane hydro-reforming at 550 °C for 48 h, although agglomeration of Pt single-atoms into clusters is observed after reaction. In CO oxidation, the Pt single-atom identity was fully maintained after 60 cycles between 100 and 400 °C over a one-month period.

  19. An in vivo evaluation of fit of zirconium-oxide based ceramic single crowns, generated with two CAD/CAM systems, in comparison to metal ceramic single crowns.

    Science.gov (United States)

    Biscaro, Leonello; Bonfiglioli, Roberto; Soattin, Massimo; Vigolo, Paolo

    2013-01-01

    The purpose of this study was to assess in vivo the marginal fit of single crowns produced using two CAD/CAM all-ceramic systems, in comparison to more traditional metal ceramic crowns. Thirty vital, caries-free, and previously untreated teeth were chosen in five patients who needed extraction for implant placement and therefore were included in this study. In the control group (C), 10 regular metal ceramic crowns with porcelain occlusal surfaces were fabricated. In the other two groups (Z and E), CAD/CAM technology was used for the fabrication of 20 zirconium-oxide-based ceramic single crowns with two systems. All zirconia crowns were cemented with glass-ionomer cement, always following the manufacturer's instructions. The same dentist carried out all clinical phases. The teeth were extracted 1 month later. Marginal gaps along vertical planes were measured for each crown, using a total of four landmarks for each tooth by means of a microscope at a magnification of 50×. On completion of microscopic evaluation, representative specimens from each group were prepared for ESEM evaluation. Mean and standard deviations of the four landmarks (mesial, distal, buccal, palatal) at each single crown were calculated for each group. Multivariate analysis of variance (MANOVA) was performed to determine whether the four landmarks, taken into consideration together, differed between groups. Two-way ANOVA was performed to study in detail, for each landmark, how the three systems used to produce the FPDs affected the gap measurements. Differences were considered to be significant at p compared to more traditional metal ceramic crowns. © 2012 by the American College of Prosthodontists.

  20. Synthesis of a molecularly defined single-active site heterogeneous catalyst for selective oxidation of N-heterocycles.

    Science.gov (United States)

    Zhang, Yujing; Pang, Shaofeng; Wei, Zhihong; Jiao, Haijun; Dai, Xingchao; Wang, Hongli; Shi, Feng

    2018-04-13

    Generally, a homogeneous catalyst exhibits good activity and defined active sites but it is difficult to recycle. Meanwhile, a heterogeneous catalyst can easily be reused but its active site is difficult to reveal. It is interesting to bridge the gap between homogeneous and heterogeneous catalysis via controllable construction of a heterogeneous catalyst containing defined active sites. Here, we report that a molecularly defined, single-active site heterogeneous catalyst has been designed and prepared via the oxidative polymerization of maleimide derivatives. These polymaleimide derivatives can be active catalysts for the selective oxidation of heterocyclic compounds to quinoline and indole via the recycling of -C=O and -C-OH groups, which was confirmed by tracing the reaction with GC-MS using maleimide as the catalyst and by FT-IR analysis with polymaleimide as the catalyst. These results might promote the development of heterogeneous catalysts with molecularly defined single active sites exhibiting a comparable activity to homogeneous catalysts.

  1. Synthesis and effect of copper incorporation on the thermoluminescence and structural properties of SiO{sub 2} particles

    Energy Technology Data Exchange (ETDEWEB)

    Burruel I, S. E.; Cruz V, C.; Salas J, Ch. J. [Universidad de Sonora, Departamento de Investigacion en Polimeros y Materiales, Apdo. Postal 130, 83000 Hermosillo, Sonora (Mexico); Bernal, R. [Universidad de Sonora, Centro de Investigacion en Fisica, Apdo. Postal 5-088, 83190 Hermosillo, Sonora (Mexico); Garcia H, A. R. [Universidad de Sonora, Departamento de Ciencias Quimico Biologicas, 83000 Hermosillo, Sonora (Mexico); Castano, V. M., E-mail: silvia@gimmunison.com [UNAM, Instituto de Fisica, Departamento de Fisica Aplicada y Tecnologia Avanzada, Apdo. Postal 1-1010, 76000 Queretaro, Qro. (Mexico)

    2015-10-15

    Full text: In this work, we evaluated the effect of Cu-dopant concentration in SiO{sub 2} particles on structural and thermoluminescence (Tl) properties, prepared by the sol-gel technique. Tl studies in silica samples containing Cu show an important enhancement of their Tl response when compared with pure silica samples. In the copper doped silica a prominent Tl peak is observed, the glow curve was observed between 70 and 450 degrees C after exposure to beta irradiation. The maximum temperature of the glow peak centered at around 140 degrees C shifts to higher values and the intensity enhancement with increasing Cu content, this glow curve is surely composed of several overlapped individual Tl peaks. Also, the particle size is affected by the concentration of Cu dopant. In the case SiO{sub 2}, only is observed a glow peak centered to 95 degrees C, which is interesting for non-Tl dosimetry of ionizing radiation, which is based in detecting the afterglow response following exposure to radiation. The dose response of SiO{sub 2}:Cu showed a linear behaviour in the interval studied with no saturation evidence until 6.4 kGy, which makes this material suitable and promising for medical, industrial and also space dosimetry applications. (Author)

  2. Observing the semiconducting band-gap alignment of MoS{sub 2} layers of different atomic thicknesses using a MoS{sub 2}/SiO{sub 2}/Si heterojunction tunnel diode

    Energy Technology Data Exchange (ETDEWEB)

    Nishiguchi, Katsuhiko, E-mail: nishiguchi.katsuhiko@lab.ntt.co.jp; Yamaguchi, Hiroshi; Fujiwara, Akira [NTT Basic Research Laboratories, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198 (Japan); Castellanos-Gomez, Andres; Zant, Herre S. J. van der; Steele, Gary A. [Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628CJ Delft (Netherlands)

    2015-08-03

    We demonstrate a tunnel diode composed of a vertical MoS{sub 2}/SiO{sub 2}/Si heterostructure. A MoS{sub 2} flake consisting four areas of different thicknesses functions as a gate terminal of a silicon field-effect transistor. A thin gate oxide allows tunneling current to flow between the n-type MoS{sub 2} layers and p-type Si channel. The tunneling-current characteristics show multiple negative differential resistance features, which we interpret as an indication of different conduction-band alignments of the MoS{sub 2} layers of different thicknesses. The presented tunnel device can be also used as a hybrid-heterostructure device combining the advantages of two-dimensional materials with those of silicon transistors.

  3. Switchable and tunable film bulk acoustic resonator fabricated using barium strontium titanate active layer and Ta{sub 2}O{sub 5}/SiO{sub 2} acoustic reflector

    Energy Technology Data Exchange (ETDEWEB)

    Sbrockey, N. M., E-mail: sbrockey@structuredmaterials.com; Tompa, G. S. [Structured Materials Industries, Inc., Piscataway, New Jersey 08854 (United States); Kalkur, T. S.; Mansour, A. [Department of Electrical and Computer Engineering, Colorado State University at Colorado Springs, Colorado Springs, Colorado 80933 (United States); Khassaf, H.; Yu, H.; Aindow, M.; Alpay, S. P. [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States)

    2016-08-01

    A solidly mounted acoustic resonator was fabricated using a Ba{sub 0.60}Sr{sub 0.40}TiO{sub 3} (BST) film deposited by metal organic chemical vapor deposition. The device was acoustically isolated from the substrate using a Bragg reflector consisting of three pairs of Ta{sub 2}O{sub 5}/SiO{sub 2} layers deposited by chemical solution deposition. Transmission electron microscopy verified that the Bragg reflector was not affected by the high temperatures and oxidizing conditions necessary to process high quality BST films. Electrical characterization of the resonator demonstrated a quality factor (Q) of 320 and an electromechanical coupling coefficient (K{sub t}{sup 2}) of 7.0% at 11 V.

  4. Oxidant-antioxidant status in Egyptian children with sickle cell anemia: a single center based study.

    Science.gov (United States)

    El-Ghamrawy, Mona Kamal; Hanna, Wagdi Maurice; Abdel-Salam, Amina; El-Sonbaty, Marwa M; Youness, Eman R; Adel, Ahmed

    2014-01-01

    the present study was conducted to investigate the oxidant-antioxidant status in Egyptian children with sickle cell anemia. the serum levels of total antioxidant capacity (TAO), paraoxonase (PON), vitamin E, nitrite, and malondialdehyde (MDA) were measured in 40 steady state children with homozygous sickle cell anemia (24 males and 16 females) and 20 apparently healthy age- and gender-matched controls. mean serum TAO, PON, vitamin E, and nitrite levels were significantly lower in the group with sickle cell anemia, whereas mean serum MDA was significantly higher in these children compared to controls. No significant differences in mean levels of TAO, PON, nitrite, vitamin E, and MDA were found in sickle cell anemia patients receiving hydroxyurea when compared with those not receiving hydroxyurea. A significant negative correlation between serum nitrite and the occurrence of vaso-occlusive crises (VOC) was observed (r=-0.3, p=0.04). PON level was found to be positively correlated with patients' weight and BMI (r=-0.4, p=0.01; r=-0.7, psickle cell anemia have chronic oxidative stress that may result in increased VOC, and decreased serum nitrite may be associated with increases in VOC frequency. A novel finding in this study is the decrease in PON level in these patients, which is an interesting subject for further research. Copyright © 2014 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  5. Effects of thermal oxidation duration on the structural and electrical properties of Nd{sub 2}O{sub 3}/Si system

    Energy Technology Data Exchange (ETDEWEB)

    Hetherin, Karuppiah; Ramesh, S.; Wong, Yew Hoong [University of Malaya, Department of Mechanical Engineering, Faculty of Engineering, Kuala Lumpur (Malaysia)

    2017-08-15

    A study on the growth, structure and electrical properties of Nd{sub 2}O{sub 3} was carried out experimentally on RF sputtered thin film on Si followed by thermal oxidation at 700 C at different oxidation durations (5, 10, 15 and 20 min). The structural and chemical properties were studied by X-ray diffraction analysis, Fourier transform infrared analysis, Raman analysis and high resolution transmission electron microscopy analysis. The formation of cubic-Nd{sub 2}O{sub 3}, orthorhombic-Nd{sub 2}Si{sub 2}O{sub 7}, monoclinic-SiO{sub 2}, tetragonal-SiO{sub 2} and hexagonal-SiO{sub 2} was detected. A single interfacial layer was detected for the sample oxidized at 15 min and double interfacial layers were detected for the samples oxidized at 5, 10 and 20 min. The sample oxidized at 15 min possessed the best electrical properties which were attributed by the highest Nd{sub 2}O{sub 3} intensity, largest SiO{sub 2} crystallite structure, thinnest interfacial and oxide layer, highest barrier height, lowest effective oxide charges, slow trap density and average interface trap density. (orig.)

  6. Fluorocarbon assisted atomic layer etching of SiO{sub 2} and Si using cyclic Ar/C{sub 4}F{sub 8} and Ar/CHF{sub 3} plasma

    Energy Technology Data Exchange (ETDEWEB)

    Metzler, Dominik; Oehrlein, Gottlieb S., E-mail: oehrlein@umd.edu [Department of Materials Science and Engineering, and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20740 (United States); Li, Chen [Department of Physics, and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20740 (United States); Engelmann, Sebastian; Bruce, Robert L.; Joseph, Eric A. [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States)

    2016-01-15

    The need for atomic layer etching (ALE) is steadily increasing as smaller critical dimensions and pitches are required in device patterning. A flux-control based cyclic Ar/C{sub 4}F{sub 8} ALE based on steady-state Ar plasma in conjunction with periodic, precise C{sub 4}F{sub 8} injection and synchronized plasma-based low energy Ar{sup +} ion bombardment has been established for SiO{sub 2} [Metzler et al., J. Vac. Sci. Technol. A 32, 020603 (2014)]. In this work, the cyclic process is further characterized and extended to ALE of silicon under similar process conditions. The use of CHF{sub 3} as a precursor is examined and compared to C{sub 4}F{sub 8}. CHF{sub 3} is shown to enable selective SiO{sub 2}/Si etching using a fluorocarbon (FC) film build up. Other critical process parameters investigated are the FC film thickness deposited per cycle, the ion energy, and the etch step length. Etching behavior and mechanisms are studied using in situ real time ellipsometry and x-ray photoelectron spectroscopy. Silicon ALE shows less self-limitation than silicon oxide due to higher physical sputtering rates for the maximum ion energies used in this work, ranged from 20 to 30 eV. The surface chemistry is found to contain fluorinated silicon oxide during the etching of silicon. Plasma parameters during ALE are studied using a Langmuir probe and establish the impact of precursor addition on plasma properties.

  7. Optical and Electrical Properties of Sn-Doped Zinc Oxide Single Crystals

    Science.gov (United States)

    Haseman, M. S.; Saadatkia, Pooneh; Warfield, J. T.; Lawrence, J.; Hernandez, A.; Jellison, G. E.; Boatner, L. A.; Selim, F. A.

    2018-02-01

    Sn dopant in ZnO may significantly improve the n-type conductivity of ZnO through a characteristic double effect. However, studies on bulk Sn-doped ZnO are rare, and the effect of Sn doping on the optoelectronic properties of bulk ZnO is not well understood. In this work, the effect of Sn doping on the optical and electrical properties of ZnO bulk single crystals was investigated through optical absorption spectroscopy, Hall-effect measurements, and thermoluminescence (TL) spectroscopy. Undoped and Sn-doped ZnO single crystals were grown by chemical vapor transport method and characterized by x-ray diffraction analysis. The Sn doping level in the crystals was evaluated by inductively coupled plasma mass spectroscopy measurements. Hall-effect measurements revealed an increase in conductivity and carrier concentration with increasing Sn doping, while TL measurements identified a few donor species in the crystals with donor ionization energy ranging from 35 meV to 118 meV. Increasing Sn doping was also associated with a color change of single crystals from colorless to dark blue.

  8. Integrated Planar Solid Oxide Fuel Cell: Steady-State Model of a Bundle and Validation through Single Tube Experimental Data

    Directory of Open Access Journals (Sweden)

    Paola Costamagna

    2015-11-01

    Full Text Available This work focuses on a steady-state model developed for an integrated planar solid oxide fuel cell (IP-SOFC bundle. In this geometry, several single IP-SOFCs are deposited on a tube and electrically connected in series through interconnections. Then, several tubes are coupled to one another to form a full-sized bundle. A previously-developed and validated electrochemical model is the basis for the development of the tube model, taking into account in detail the presence of active cells, interconnections and dead areas. Mass and energy balance equations are written for the IP-SOFC tube, in the classical form adopted for chemical reactors. Based on the single tube model, a bundle model is developed. Model validation is presented based on single tube current-voltage (I-V experimental data obtained in a wide range of experimental conditions, i.e., at different temperatures and for different H2/CO/CO2/CH4/H2O/N2 mixtures as the fuel feedstock. The error of the simulation results versus I-V experimental data is less than 1% in most cases, and it grows to a value of 8% only in one case, which is discussed in detail. Finally, we report model predictions of the current density distribution and temperature distribution in a bundle, the latter being a key aspect in view of the mechanical integrity of the IP-SOFC structure.

  9. Turbidimetric Measurement for On-line Monitoring of SiO{sub 2} Particles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Sook; Lim, H. B. [Dankook University, Seoul (Korea, Republic of); Kim, Yang Sun [Proteonik, Inc., Ansan (Korea, Republic of)

    2004-06-15

    In this work, the fundamental study of on-line monitoring of SiO{sub 2} particles in the size range of 40 nm to 725 nm was carried out using turbidimetry. The size of particle was measured using a field emission scanning electron microscope (FE-SEM). The factors affecting on the turbidity were discussed, for example, wavelength, size, and concentration. In order to observe the dependence of turbidity on the wavelength, a turbidimetric system equipped with charged coupled detector (CCD) was built. The shape of the transmitted peak was changed and the peak maximum was shifted to the red when the concentration of particle was increased. This result indicates that the turbidity is related to the wavelength, which corresponds to the characteristic of the Mie extinction coefficient, Q, that is a function of not only particle diameter and refractive index but also wavelength. It is clear that a linear calibration curve for each particle in different size can be obtained at an optimized wavelength.

  10. Photoluminescence induced from hot Ge implantation into SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Bregolin, F.L. [Instituto de Fisica Universidade Federal do Rio Grande do Sul, C.P. 15051, 91501-970 Porto Alegre (Brazil); Behar, M. [Instituto de Fisica Universidade Federal do Rio Grande do Sul, C.P. 15051, 91501-970 Porto Alegre (Brazil)], E-mail: behar@if.ufrgs.br; Sias, U.S. [Centro Federal de Educacao Tecnologica de Pelotas, 96015-370 RS (Brazil); Moreira, E.C. [Universidade Federal do Pampa - UNIPAMPA, Campus Bage, 96400-970 Bage, RS (Brazil)

    2009-05-01

    Up to the present, by using the ion implantation technique, photoluminescence (PL) from Ge nanocrystals (Ge NCs) was obtained by room temperature (RT) Ge implantation into a SiO{sub 2} matrix followed by a high temperature anneal. In this way two PL bands were observed, one at 310 nm and the second, with much higher yield at 390 nm. In the present work we have used another experimental approach. We have performed the Si implantation at high temperature (T{sub i}) and then, we have done a higher temperature anneal (T{sub a}) in order to nucleate the Ge NCs. With this aim we have changed T{sub i} between RT and 600 deg. C. By performing the implantation at T{sub i} = 350 deg. C we found a PL yield four times higher than the one obtained from the usual RT implantation at the same fluence. Moreover, by changing the implantation fluence between {phi} = 0.25 x 10{sup 16} and 2.2 x 10{sup 16} Ge/cm{sup 2} we observed that {phi} = 0.5 x 10{sup 16} Ge/cm{sup 2} induces a PL yield three times higher as compared to the usual RT implantation fluence. In conclusion, using a hot Ge implantation plus an optimal Ge atomic concentration, we were able to gain more than one order of magnitude in the 390 nm PL yield as compared with previous ion implantation results.

  11. Scratch resistance of SiO{sub 2} and SiO{sub 2} - ZrO{sub 2} sol-gel coatings on glass-ceramic obtained by sintering; Resistencia al desgaste de recubrimientos sol-gel de SiO{sub 2} y SiO{sub 2} - ZrO{sub 2} sobre materiales vitroceramicos obtenidos por sinterizacion

    Energy Technology Data Exchange (ETDEWEB)

    Soares, V. O.; Soares, P.; Peitl, O.; Zanotto, E. D.; Duran, A.; Castro, Y.

    2013-10-01

    The sol-gel process is widely used to obtain coatings on glass-ceramic substrates in order to improve the scratch and abrasion resistance, also providing a bright and homogeneous appearance of a glaze avoiding expensive final polishing treatments. This paper describes the preparation of silica and silica / zirconia coatings by sol-gel method on Li{sub 2}O-Al{sub 2}O3-SiO{sub 2} (LAS) glassceramic substrates produced by sintering. The coatings were deposited by dip-coating on LAS substrates and characterized by optical microscopy and spectral ellipsometry. On the other hand, hardness and elastic modulus, coefficient of friction and abrasion and scratch resistance of the coatings were determined and compared with the substrate properties. Coatings deposited on LAS glass-ceramic confere the substrate a bright and homogeneous aspect, similar to a glaze, improving the appearance and avoiding the final polishing. However these coatings do not increase the scratch resistance of the substrate only equaling the properties of the glass-ceramic. (Author)

  12. Oxidant-antioxidant status in Egyptian children with sickle cell anemia: a single center based study

    Directory of Open Access Journals (Sweden)

    Mona Kamal El-Ghamrawy

    2014-06-01

    Full Text Available OBJECTIVE: the present study was conducted to investigate the oxidant-antioxidant status in Egyptian children with sickle cell anemia. METHODS: the serum levels of total antioxidant capacity (TAO, paraoxonase (PON, vitamin E, nitrite, and malondialdehyde (MDA were measured in 40 steady state children with homozygous sickle cell anemia (24 males and 16 females and 20 apparently healthy age- and gender-matched controls. RESULTS: mean serum TAO, PON, vitamin E, and nitrite levels were significantly lower in the group with sickle cell anemia, whereas mean serum MDA was significantly higher in these children compared to controls. No significant differences in mean levels of TAO, PON, nitrite, vitamin E, and MDA were found in sickle cell anemia patients receiving hydroxyurea when compared with those not receiving hydroxyurea. A significant negative correlation between serum nitrite and the occurrence of vaso-occlusive crises (VOC was observed (r = -0.3, p = 0.04. PON level was found to be positively correlated with patients' weight and BMI (r = -0.4, p = 0.01; r = -0.7, p < 0.001, respectively, but not with frequency of VOC. The area under the curve of serum nitrite in predicting occurrence of VOC was 0.782, versus 0.701 for PON, and 0.650 for TAO (p = 0.006. Serum MDA was not correlated with nitrite, PON, TAO, or vitamin E levels. No significant correlations were detected between serum nitrite and hemoglobin or antioxidant enzymes. CONCLUSION: children with sickle cell anemia have chronic oxidative stress that may result in increased VOC, and decreased serum nitrite may be associated with increases in VOC frequency. A novel finding in this study is the decrease in PON level in these patients, which is an interesting subject for further research.

  13. Paired-pulse facilitation achieved in protonic/electronic hybrid indium gallium zinc oxide synaptic transistors

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Li Qiang, E-mail: guoliqiang@ujs.edu.cn; Ding, Jian Ning; Huang, Yu Kai [Micro/Nano Science & Technology Center, Jiangsu University, Zhenjiang, 212013 (China); Zhu, Li Qiang, E-mail: lqzhu@nimte.ac.cn [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2015-08-15

    Neuromorphic devices with paired pulse facilitation emulating that of biological synapses are the key to develop artificial neural networks. Here, phosphorus-doped nanogranular SiO{sub 2} electrolyte is used as gate dielectric for protonic/electronic hybrid indium gallium zinc oxide (IGZO) synaptic transistor. In such synaptic transistors, protons within the SiO{sub 2} electrolyte are deemed as neurotransmitters of biological synapses. Paired-pulse facilitation (PPF) behaviors for the analogous information were mimicked. The temperature dependent PPF behaviors were also investigated systematically. The results indicate that the protonic/electronic hybrid IGZO synaptic transistors would be promising candidates for inorganic synapses in artificial neural network applications.

  14. Electrochemical and Electron Paramagnetic Resonance Study of the Mechanism of Oxidation of Phenazine-di-N-oxide in the Presence of Isopropyl alcohol at Glassy Carbon and Single-Walled Carbon Nanotube Electrodes

    International Nuclear Information System (INIS)

    Kulakovskaya, S.I.; Kulikov, A.V.; Sviridova, L.N.; Stenina, E.V.

    2014-01-01

    Graphical abstract: - Highlights: • The mechanism of oxidation of phenazine-di-N-oxide in the presence of isopropyl alcohol was studied. • The results are explained in terms of the E 1 C 1 E 2 C 2 mechanism of the two-stage electrode process. • The total two-electron catalytic oxidation of i-PrOH in the complex with the phenazine-di-N-oxide radical cation was assumed to occur. - Abstract: The mechanism of oxidation of phenazine-di-N-oxide in the presence of isopropyl alcohol was studied by cyclic voltammetry at glassy carbon (GC) and single-walled carbon nanotubes (SWCNT) electrodes in 0.1 M LiClO 4 solutions in acetonitrile. The adsorption of phenazine-di-N-oxide at SWCNT electrode in 0.1 M LiClO 4 solution in acetonitrile was investigated by measurement of the dependence of the differential double layer capacitance of the electrode C on potential E. The effect of isopropyl alcohol on the shape of cyclic voltammograms (CVs) of phenazine-di-N-oxide and the intensity of Electron Paramagnetic Resonance (EPR) signal of its radical cation was investigated. The catalytic currents were recorded at the oxidation of phenazine-di-N-oxide at SWCNT and GC electrodes in the presence of isopropyl alcohol. The results were explained in terms of the E 1 C 1 E 2 C 2 mechanism of two-stage electrode process characterized by catalytic current recorded at the second electrode stage. The overall two-electron catalytic oxidation of isopropyl alcohol in complex with the phenazine-di-N-oxide radical cation was assumed to occur. It was shown that SWCNT electrodes can be used in the electrocatalytic oxidation of organic compounds in the presence of electrochemically generated phenazine-di-N-oxide radical cation

  15. Charge transferred doping of single layer graphene by mono-dispersed manganese-oxide nanoparticles adsorption

    Science.gov (United States)

    Phan, Thanh Luan; Kang, Myunggoo; Choi, Soo Ho; Kim, You Joong; Jung, Hyun; Yoon, Im Taek; Yang, Woochul

    2017-10-01

    We report an efficient and controllable method to introduce p-type doping in graphene by decoration with Mn3O4 nanoparticles (NPs) on mechanically exfoliated single layer graphene. A monolayer of Mn3O4 NPs, with a diameter in the range of 5-10 nm, was decorated on a graphene film using an ex-situ method, whereas by controlling the coverage of the NPs on the graphene surface, the carrier concentration could be continually adjusted. The p-type of the NP-decorated single layer graphene was confirmed by the Raman G-band. It was found that the carrier concentration could be gradually adjusted up to 26.09 × 1012 cm-2, with 90% coverage of Mn3O4 NPs. The Dirac point of the pristine graphene at the gate bias of 27 V shifted to 150 V for Mn3O4 NP decorated graphene. The p-type graphene doped with Mn3O4 NPs demonstrated significant high air-stability, even under an oxygen atmosphere for 60 days. This approach allows for the opportunity for simple, scalable, and highly stable doping of graphene for future high-performance electronic device applications.

  16. A simple single-step approach towards synthesis of nanofluids containing cuboctahedral cuprous oxide particles using glucose reduction

    Science.gov (United States)

    Shenoy, U. Sandhya; Shetty, A. Nityananda

    2018-01-01

    Enhancement of thermal properties of conventional heat transfer fluids has become one of the important technical challenges. Since nanofluids offer a promising help in this regard, development of simpler and hassle free routes for their synthesis is of utmost importance. Synthesis of nanofluids using a hassle free route with greener chemicals has been reported. The single-step chemical approach reported here overcomes the drawbacks of the two-step procedures in the synthesis of nanofluids. The resulting Newtonian nanofluids prepared contained cuboctahedral particles of cuprous oxide and exhibited a thermal conductivity of 2.852 W·m-1·K-1. Polyvinylpyrrolidone (PVP) used during the synthesis acted as a stabilizing agent rendering the nanofluid a stability of 9 weeks.

  17. A simple single-step approach towards synthesis of nanofluids containing cuboctahedral cuprous oxide particles using glucose reduction

    Science.gov (United States)

    Shenoy, U. Sandhya; Shetty, A. Nityananda

    2018-03-01

    Enhancement of thermal properties of conventional heat transfer fluids has become one of the important technical challenges. Since nanofluids offer a promising help in this regard, development of simpler and hassle free routes for their synthesis is of utmost importance. Synthesis of nanofluids using a hassle free route with greener chemicals has been reported. The single-step chemical approach reported here overcomes the drawbacks of the two-step procedures in the synthesis of nanofluids. The resulting Newtonian nanofluids prepared contained cuboctahedral particles of cuprous oxide and exhibited a thermal conductivity of 2.852 W·m-1·K-1. Polyvinylpyrrolidone (PVP) used during the synthesis acted as a stabilizing agent rendering the nanofluid a stability of 9 weeks.

  18. From oleic acid-capped iron oxide nanoparticles to polyethyleneimine-coated single-particle magnetofectins

    Energy Technology Data Exchange (ETDEWEB)

    Cruz-Acuña, Melissa [University of Florida, J. Crayton Pruitt Family Department of Biomedical Engineering (United States); Maldonado-Camargo, Lorena [University of Florida, Department of Chemical Engineering (United States); Dobson, Jon; Rinaldi, Carlos, E-mail: carlos.rinaldi@bme.ufl.edu [University of Florida, J. Crayton Pruitt Family Department of Biomedical Engineering (United States)

    2016-09-15

    Various inorganic nanoparticle designs have been developed and used as non-viral gene carriers. Magnetic gene carriers containing polyethyleneimine (PEI), a well-known transfection agent, have been shown to improve DNA transfection speed and efficiency in the presence of applied magnetic field gradients that promote particle–cell interactions. Here we report a method to prepare iron oxide nanoparticles conjugated with PEI that: preserves the narrow size distribution of the nanoparticles, conserves magnetic properties throughout the process, and results in efficient transfection. We demonstrate the ability of the particles to electrostatically bind with DNA and transfect human cervical cancer (HeLa) cells by the use of an oscillating magnet array. Their transfection efficiency is similar to that of Lipofectamine 2000™, a commercial transfection reagent. PEI-coated particles were subjected to acidification, and acidification in the presence of salts, before DNA binding. Results show that although these pre-treatments did not affect the ability of particles to bind DNA they did significantly enhanced transfection efficiency. Finally, we show that these magnetofectins (PEI-MNP/DNA) complexes have no effect on the viability of cells at the concentrations used in the study. The systematic preparation of magnetic vectors with uniform physical and magnetic properties is critical to progressing this non-viral transfection technology.

  19. From oleic acid-capped iron oxide nanoparticles to polyethyleneimine-coated single-particle magnetofectins

    International Nuclear Information System (INIS)

    Cruz-Acuña, Melissa; Maldonado-Camargo, Lorena; Dobson, Jon; Rinaldi, Carlos

    2016-01-01

    Various inorganic nanoparticle designs have been developed and used as non-viral gene carriers. Magnetic gene carriers containing polyethyleneimine (PEI), a well-known transfection agent, have been shown to improve DNA transfection speed and efficiency in the presence of applied magnetic field gradients that promote particle–cell interactions. Here we report a method to prepare iron oxide nanoparticles conjugated with PEI that: preserves the narrow size distribution of the nanoparticles, conserves magnetic properties throughout the process, and results in efficient transfection. We demonstrate the ability of the particles to electrostatically bind with DNA and transfect human cervical cancer (HeLa) cells by the use of an oscillating magnet array. Their transfection efficiency is similar to that of Lipofectamine 2000™, a commercial transfection reagent. PEI-coated particles were subjected to acidification, and acidification in the presence of salts, before DNA binding. Results show that although these pre-treatments did not affect the ability of particles to bind DNA they did significantly enhanced transfection efficiency. Finally, we show that these magnetofectins (PEI-MNP/DNA) complexes have no effect on the viability of cells at the concentrations used in the study. The systematic preparation of magnetic vectors with uniform physical and magnetic properties is critical to progressing this non-viral transfection technology.

  20. The mechanism of the nitric oxide-mediated enhancement of tert-butylhydroperoxide-induced DNA single strand breakage

    Science.gov (United States)

    Guidarelli, Andrea; Clementi, Emilio; Sciorati, Clara; Cantoni, Orazio

    1998-01-01

    Caffeine (Cf) enhances the DNA cleavage induced by tert-butylhydroperoxide (tB-OOH) in U937 cells via a mechanism involving Ca2+-dependent mitochondrial formation of DNA-damaging species (Guidarelli et al., 1997b). Nitric oxide (NO) is not involved in this process since U937 cells do not express the constitutive nitric oxide synthase (cNOS).Treatment with the NO donors S-nitroso-N-acetyl-penicillamine (SNAP, 10 μM), or S-nitrosoglutathione (GSNO, 300 μM), however, potentiated the DNA strand scission induced by 200 μM tB-OOH. The DNA lesions generated by tB-OOH alone, or combined with SNAP, were repaired with superimposable kinetics and were insensitive to anti-oxidants and peroxynitrite scavengers but suppressed by iron chelators.SNAP or GSNO did not cause mitochondrial Ca2+ accumulation but their enhancing effects on the tB-OOH-induced DNA strand scission were prevented by ruthenium red, an inhibitor of the calcium uniporter of mitochondria. Furthermore, the enhancing effects of both SNAP and GSNO were identical to and not additive with those promoted by the Ca2+-mobilizing agents Cf or ATP.The SNAP- or GSNO-mediated enhancement of the tB-OOH-induced DNA cleavage was abolished by the respiratory chain inhibitors rotenone and myxothiazol and was not apparent in respiration-deficient cells.It is concluded that, in cells which do not express the enzyme cNOS, exogenous NO enhances the accumulation of DNA single strand breaks induced by tB-OOH via a mechanism involving inhibition of complex III. PMID:9846647

  1. Self-Assembly of Single-Crystal Silver Microflakes on Reduced Graphene Oxide and their Use in Ultrasensitive Sensors

    KAUST Repository

    Chen, Ye

    2016-01-19

    Compared to 1D structures, 2D structures have higher specific and active surface, which drastically improves electron transfer and extensibility along 2D plane. Herein, 2D-single crystal silver microflakes (AgMFs) are prepared for the first time in situ on reduced graphene oxide (RGO) by solvothermal synthesis with thickness around 100 nm and length around 10 μm. The oriented attachment mechanism is hypothesized to control the silver crystal growth and self-assembly of reduced silver units to form single-crystal AgMF structure on RGO sheets. Employing it as an electrode to fabricate reliable and extremely sensitive pressure sensors verifies the applicability of this novel 2D structure. Contrary to nanowires, 2D microflakes can intercalate better within the polymer matrix to provide an enhanced network for electron movement. The designed sensor can retain more than 4.7 MPa-1 after 10 000 cycles. The design proves functional for monitoring various actions such as wrist movement, squatting, walking, and delicate finger touch with high durability. A highly sensitive and flexible pressure sensor is fabricated based on the self-assembly of silver microflakes on reduced graphene oxide. This sensor exhibits an excellent pressure sensitivity as it can retain more than 4.7 MPa-1 after 10 000 cycles. This system is successfully used to monitor wrist movement, walking, and squatting and can be applied in touch screen panels, robotic systems, and prosthetics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Enhanced Electrochemical Oxidation of p-Nitrophenol Using Single-Walled Carbon Nanotubes/Silver Nanowires Hybrids Modified Electrodes.

    Science.gov (United States)

    Jiang, Yunfang; Liu, Xinghua; Li, Jing; Zhou, Lei; Yang, Xiaoying; Huang, Yi

    2015-08-01

    The electrochemical oxidation of p-nitrophenol (p-Np) has been studied on glassy carbon electrode modified with the single-walled carbon nanotubes/silver nanowires hybrids (SWNTs-Ag) by using cyclic and differential pulse voltammetry. p-Np is irreversibly oxidized at +0.88 V (vs. the Ag/AgCl) in PBS solutions of pH 7.4. The modified electrodes display the detection sensitivity of 0.0212 µA/µM with an unusually wide linear response of 5-1700 µM (R2 = 0.998) and the detection limit of 1 µM. The current response of SWNTs-Ag modified electrode to p-Np is better than that of SWNTs or Ag nanowires modified electrode under the same concentration. Combining the adsorption ability of SWNTs and the conductivity of SWNTs and Ag nanowires, the detection performance of SWNTs-Ag modified electrode to p-Np was greatly improved.

  3. Single-Stroke Synthesis of Tin Sulphide/Oxide Nanocomposites Within Engineering Thermoplastic and Their Humidity Response.

    Science.gov (United States)

    Adkar, Dattatraya; Adhyapak, Parag; Mulik, Uttamrao; Jadkar, Sandesh; Vutova, Katia; Amalnerkar, Dinesh

    2018-05-01

    SnS nanostructured materials have attracted enormous interest due to their important properties and potential application in low cost solar energy conversion systems and optical devices. From the perspective of SnS based device fabrication, we offer single-stroke in-situ technique for the generation of Sn based sulphide and oxide nanostructures inside the polymer network via polymer-inorganic solid state reaction route. In this method, polyphenylene sulphide (PPS)-an engineering thermoplastic-acts as chalcogen source as well as stabilizing matrix for the resultant nano products. Typical solid state reaction was accomplished by simply heating the physical admixtures of the tin salts (viz. tin acetate/tin chloride) with PPS at the crystalline melting temperature (285 °C) of PPS in inert atmosphere. The synthesized products were characterized by using various physicochemical characterization techniques. The prima facie observations suggest the concurrent formation of nanocrystalline SnS with extraneous oxide phase. The TEM analysis revealed formation of nanosized particles of assorted morphological features with polydispersity confined to 5 to 50 nm. However, agglomerated particles of nano to submicron size were also observed. The humidity sensing characterization of these nanocomposites was also performed. The resistivity response with the level of humidity (20 to 85% RH) was compared for these nanocomposites. The linear response was obtained for both the products. Nevertheless, the nanocomposite product obtained from acetate precursor showed higher sensitivity towards the humidity than that of one prepared from chloride precursor.

  4. The single-strand DNA binding activity of human PC4 preventsmutagenesis and killing by oxidative DNA damage

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jen-Yeu; Sarker, Altaf Hossain; Cooper, Priscilla K.; Volkert, Michael R.

    2004-02-01

    Human positive cofactor 4 (PC4) is a transcriptional coactivator with a highly conserved single-strand DNA (ssDNA) binding domain of unknown function. We identified PC4 as a suppressor of the oxidative mutator phenotype of the Escherichia coli fpg mutY mutant and demonstrate that this suppression requires its ssDNA binding activity. Yeast mutants lacking their PC4 ortholog Sub1 are sensitive to hydrogen peroxide and exhibit spontaneous and peroxide induced hypermutability. PC4 expression suppresses the peroxide sensitivity of the yeast sub l{Delta} mutant, suggesting that the human protein has a similar function. A role for yeast and human proteins in DNA repair is suggested by the demonstration that Sub1 acts in a peroxide-resistance pathway involving Rad2 and by the physical interaction of PC4 with the human Rad2 homolog XPG. We show XPG recruits PC4 to a bubble-containing DNA substrate with resulting displacement of XPG and formation of a PC4-DNA complex. We discuss the possible requirement for PC4 in either global or transcription-coupled repair of oxidative DNA damage to mediate the release of XPG bound to its substrate.

  5. Microchannel-connected SU-8 honeycombs by single-step projection photolithography for positioning cells on silicon oxide nanopillar arrays

    International Nuclear Information System (INIS)

    Larramendy, Florian; Paul, Oliver; Blatche, Marie Charline; Mazenq, Laurent; Laborde, Adrian; Temple-Boyer, Pierre

    2015-01-01

    We report on the fabrication, functionalization and testing of SU-8 microstructures for cell culture and positioning over large areas. The microstructure consists of a honeycomb arrangement of cell containers interconnected by microchannels and centered on nanopillar arrays designed for promoting cell positioning. The containers have been dimensioned to trap single cells and, with a height of 50 µm, prevent cells from escaping. The structures are fabricated using a single ultraviolet photolithography exposure with focus depth in the lower part of the SU-8 resist. With optimized process parameters, microchannels of various aspect ratios are thus produced. The cell containers and microchannels serve for the organization of axonal growth between neurons. The roughly 2 µm-high and 500 nm-wide nanopillars are made of silicon oxide structured by deep reactive ion etching. In future work, beyond their cell positioning purpose, the nanopillars could be functionalized as sensors. The proof of concept of the novel microstructure for organized cell culture is given by the successful growth of interconnected PC12 cells. Promoted by the honeycomb geometry, a dense network of interconnections between the cells has formed and the intended intimate contact of cells with the nanopillar arrays was observed by scanning electron microscopy. This proves the potential of these new devices as tools for the controlled cell growth in an interconnected container system with well-defined 3D geometry. (paper)

  6. Graphite oxide incorporated crosslinked polyvinyl alcohol and sulfonated styrene nanocomposite membrane as separating barrier in single chambered microbial fuel cell

    Science.gov (United States)

    Rudra, Ruchira; Kumar, Vikash; Pramanik, Nilkamal; Kundu, Patit Paban

    2017-02-01

    Different membranes with varied molar concentrations of graphite oxide (GO), 'in situ' polymerized sulfonated polystyrene (SS) and glutaraldehyde (GA) cross linked polyvinyl alcohol (PVA), have been analyzed as an effective and low cost nanocomposite barrier in single chambered microbial fuel cells (MFCs). The synthesized composite membranes, namely GO0.2, GO0.4 and GO0.6 exhibited comparatively better results with reduced water uptake (WU) and swelling ratios (SR) over the native PVA. The variation in properties is illustrated with membrane analyses, where GO0.4 showed an increased proton conductivity (PC) and ion exchange capacity (IEC) of 0.128 S cm-1 and 0.33 meq g-1 amongst all of the used membranes. In comparison, reduced oxygen diffusivity with lower water uptake showed a two-fold decrease in GO0.4 over pure PVA membrane (∼2.09 × 10-4 cm s-1). A maximum power density of 193.6 mW m-2 (773.33 mW m-3) with a current density of 803.33 mA m-2 were observed with GO0.4 fitted MFC, where ∼81.89% of chemical oxygen demand (COD) was removed using mixed firmicutes, as biocatalyst, in 25 days operation. In effect, the efficacy of GO incorporated crosslinked PVA and SS nanocomposite membrane has been evaluated as a polymer electrolyte membrane for harnessing bio-energy from single chambered MFCs.

  7. Reversible conversion of valence-tautomeric copper metal-organic frameworks dependent single-crystal-to-single-crystal oxidation/reduction: a redox-switchable catalyst for C-H bonds activation reaction.

    Science.gov (United States)

    Huang, Chao; Wu, Jie; Song, Chuanjun; Ding, Ran; Qiao, Yan; Hou, Hongwei; Chang, Junbiao; Fan, Yaoting

    2015-06-28

    Upon single-crystal-to-single-crystal (SCSC) oxidation/reduction, reversible structural transformations take place between the anionic porous zeolite-like Cu(I) framework and a topologically equivalent neutral Cu(I)Cu(II) mixed-valent framework. The unique conversion behavior of the Cu(I) framework endowed it as a redox-switchable catalyst for the direct arylation of heterocycle C-H bonds.

  8. O-O bond formation in ruthenium-catalyzed water oxidation: single-site nucleophilic attack vs. O-O radical coupling.

    Science.gov (United States)

    Shaffer, David W; Xie, Yan; Concepcion, Javier J

    2017-10-16

    In this review we discuss at the mechanistic level the different steps involved in water oxidation catalysis with ruthenium-based molecular catalysts. We have chosen to focus on ruthenium-based catalysts to provide a more coherent discussion and because of the availability of detailed mechanistic studies for these systems but many of the aspects presented in this review are applicable to other systems as well. The water oxidation cycle has been divided in four major steps: water oxidative activation, O-O bond formation, oxidative activation of peroxide intermediates, and O 2 evolution. A significant portion of the review is dedicated to the O-O bond formation step as the key step in water oxidation catalysis. The two main pathways to accomplish this step, single-site water nucleophilic attack and O-O radical coupling, are discussed in detail and compared in terms of their potential use in photoelectrochemical cells for solar fuels generation.

  9. A Single Pot Approach for Synthesis of Phosphate Coated Iron Oxide Nanoparticles.

    Science.gov (United States)

    Muthukumaran, T; Philip, John

    2015-04-01

    Water dispersible Fe3O4 nanoparticles with a phosphate monolayer capping was synthesized by a single-step coprecipitation method using ferrous and ferric salt solutions, ammonia and orthophosphoric acid. The synthesized nanoparticles were characterized using thermogravimetric analyser with simultaneous differential scanning calorimetry (TGA-DSC), Fourier transform infra red spectroscopy (FTIR), X-ray diffraction (XRD), small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and dynamic light scattering (DLS). The FTIR result confirms the formation of protonated and nonprotonated monodentate complexes on nanoparticle surface. The surface coverage and the bridging of these complexes are found to be pH dependant. The DSC results confirm that the maghemite to hematite phase transition in these nanoparticles is enhanced by ~100 °C, which is attributed to the presence of flame retardant phosphocarbonaceous shell at the nanoparticle interface. These results show that the dynamic capping of phosphate on Fe3O4 particles during co-precipitation can control the nucleated particle size, without compromising magnetic properties and improve their thermal stability. The phosphate capped Fe3O4 nanoparticles showed excellent long term stability (> 2 years of shelf life) at biological pH that makes them ideal for biomedical applications.

  10. Single-layer tungsten oxide as intelligent photo-responsive nanoagents for permanent male sterilization.

    Science.gov (United States)

    Liu, Zhen; Liu, Xianjun; Ran, Xiang; Ju, Enguo; Ren, Jinsong; Qu, Xiaogang

    2015-11-01

    Permanent male sterilization has been recognized as useful tools for the development of neuter experimental animals and fattening livestock, as well as efficient control of pet overpopulation. Traditional routes such as surgical ways, chemical injections, and anti-fertility vaccines have addressed these crucial problems with idea outcomes. However, these routes usually bring out serious pain and infection towards animals, as well as induce long-term adverse reaction and immune suppression. Thus, a convenient, but non-surgical strategy for male sterilization under a mild manner is highly desirable. Here, for the first time, we demonstrate a novel platform for male sterilization by using single-layer WO2.72 nanosheets as smart photo-responsive sterilants. Upon a 980 nm irradiation, these nanoagents can possess intrinsic NIR-induced hyperthermia and sensitize the formation of singlet oxygen due to the cooperation of photothermal and photodynamic effects. Mechanism of cellular injury can be attributed to the denaturation of protein and apoptosis-related death. Moreover, long-term toxicity and possible metabolism route after testicular injection are discussed, indicating the neglectable systemic toxicity and high bio-compatibility of our nanoagents. Overall, our strategy can extremely overcome the shortcomings in various routine routes and suggest the new biological application of nanomaterials. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Fabrication and Characterization of Fe doped SiO{sub 2} Composite Membranes by a Reverse Micelle and Sol-Gel Processing

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Yeong; Son, Jeong Hun; Bae, Dong Sik [School of Nano and Advanced Materials Eng., Changwon National University, Changwon (Korea, Republic of); Hwang, Kyu Hong, E-mail: dsbae7@changwon.ac.kr [School of Nano and Advanced Material Eng., Gyeongsang National University, Jinju (Korea, Republic of)

    2011-10-29

    Fe doped SiO{sub 2} nano composites powders were synthesized by a reverse micelle and sol-gel process. The average particle size of the mixed sol was below 25 nm and well dispersed in the solution. TEM results show the microstructure of Fe doped SiO{sub 2} composite was homogeneous and Fe was below 5nm and Fe well dispersed in ceramic nano particles. Fe doped SiO{sub 2} composite membranes were fabricated by sol-gel process. It was observed that Fe doped SiO{sub 2} composite membranes showed a crack-free microstructure and narrow particle size distribution even after heat treatment up to 500 deg. C. The average particle size of the membrane was 30-40nm, and the pore size of Fe doped SiO{sub 2} nano composite membrane was below 10 nm. The particle size of Pt after heat treatment at 500 deg. C was below 8nm.

  12. An ultrasensitive electrochemical DNA biosensor based on a copper oxide nanowires/single-walled carbon nanotubes nanocomposite

    International Nuclear Information System (INIS)

    Chen, Mei; Hou, Changjun; Huo, Danqun; Yang, Mei; Fa, Huanbao

    2016-01-01

    Graphical abstract: A novel and sensitive electrochemical biosensor based on hybrid nanocomposite consisting of copper oxide nanowires (CuO NWs) and carboxyl-functionalized single-walled carbon nanotubes (SWCNTs-COOH) was first developed for the detection of the specific-sequence target DNA. This schematic represents the fabrication procedure of our DNA biosensor. - Highlights: • An ultrasensitive DNA electrochemical biosensor was developed. • CuO NWs entangled with the SWCNTs formed a mesh structure with good conductivity. • It is the first time use of CuONWs-SWCNTs hybrid nanocomposite for DNA detection. • The biosensor is simple, selective, stable, and sensitive. • The biosensor has great potential for use in analysis of real samples. - Abstract: Here, we developed a novel and sensitive electrochemical biosensor to detect specific-sequence target DNA. The biosensor was based on a hybrid nanocomposite consisting of copper oxide nanowires (CuO NWs) and carboxyl-functionalized single-walled carbon nanotubes (SWCNTs-COOH). The resulting CuO NWs/SWCNTs layers exhibited a good differential pulse voltammetry (DPV) current response for the target DNA sequences, which we attributed to the properties of CuO NWs and SWCNTs. CuO NWs and SWCNTs hybrid composites with highly conductive and biocompatible nanostructure were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and cyclic voltammetry (CV). Immobilization of the probe DNA on the electrode surface was largely improved due to the unique synergetic effect of CuO NWs and SWCNTs. DPV was applied to monitor the DNA hybridization event, using adriamycin as an electrochemical indicator. Under optimal conditions, the peak currents of adriamycin were linear with the logarithm of target DNA concentrations (ranging from 1.0 × 10 −14 to 1.0 × 10 −8 M), with a detection limit of 3.5 × 10 −15 M (signal/noise ratio of 3). The biosensor also showed high selectivity to

  13. An ultrasensitive electrochemical DNA biosensor based on a copper oxide nanowires/single-walled carbon nanotubes nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Mei [Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Hou, Changjun, E-mail: houcj@cqu.edu.cn [Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); National Key Laboratory of Fundamental Science of Micro/Nano-Device and System Technology, Chongqing University, Chongqing 400044 (China); Huo, Danqun [Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); National Key Laboratory of Fundamental Science of Micro/Nano-Device and System Technology, Chongqing University, Chongqing 400044 (China); Yang, Mei [Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Fa, Huanbao [College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China)

    2016-02-28

    Graphical abstract: A novel and sensitive electrochemical biosensor based on hybrid nanocomposite consisting of copper oxide nanowires (CuO NWs) and carboxyl-functionalized single-walled carbon nanotubes (SWCNTs-COOH) was first developed for the detection of the specific-sequence target DNA. This schematic represents the fabrication procedure of our DNA biosensor. - Highlights: • An ultrasensitive DNA electrochemical biosensor was developed. • CuO NWs entangled with the SWCNTs formed a mesh structure with good conductivity. • It is the first time use of CuONWs-SWCNTs hybrid nanocomposite for DNA detection. • The biosensor is simple, selective, stable, and sensitive. • The biosensor has great potential for use in analysis of real samples. - Abstract: Here, we developed a novel and sensitive electrochemical biosensor to detect specific-sequence target DNA. The biosensor was based on a hybrid nanocomposite consisting of copper oxide nanowires (CuO NWs) and carboxyl-functionalized single-walled carbon nanotubes (SWCNTs-COOH). The resulting CuO NWs/SWCNTs layers exhibited a good differential pulse voltammetry (DPV) current response for the target DNA sequences, which we attributed to the properties of CuO NWs and SWCNTs. CuO NWs and SWCNTs hybrid composites with highly conductive and biocompatible nanostructure were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and cyclic voltammetry (CV). Immobilization of the probe DNA on the electrode surface was largely improved due to the unique synergetic effect of CuO NWs and SWCNTs. DPV was applied to monitor the DNA hybridization event, using adriamycin as an electrochemical indicator. Under optimal conditions, the peak currents of adriamycin were linear with the logarithm of target DNA concentrations (ranging from 1.0 × 10{sup −14} to 1.0 × 10{sup −8} M), with a detection limit of 3.5 × 10{sup −15} M (signal/noise ratio of 3). The biosensor also showed high

  14. Influence of oxidation temperature on the interfacial properties of n-type 4H-SiC MOS capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Yifan; Lv, Hongliang [School of Microelectronics, Xidian University, Key Laboratory of Wide Band Gap Semiconductor Materials and Devices, Xi’an 710071 (China); Song, Qingwen, E-mail: qwsong@xidian.edu.cn [School of Microelectronics, Xidian University, Key Laboratory of Wide Band Gap Semiconductor Materials and Devices, Xi’an 710071 (China); School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071 (China); Tang, Xiaoyan, E-mail: xytang@xidian.edu.cn [School of Microelectronics, Xidian University, Key Laboratory of Wide Band Gap Semiconductor Materials and Devices, Xi’an 710071 (China); Xiao, Li; Wang, Liangyong; Tang, Guangming [Zhongxing Telecommunication Equipment Corporation, Shenzhen 518057 (China); Zhang, Yimen; Zhang, Yuming [School of Microelectronics, Xidian University, Key Laboratory of Wide Band Gap Semiconductor Materials and Devices, Xi’an 710071 (China)

    2017-03-01

    Highlights: • Effect of oxidation temperature on interfacial properties of SiO{sub 2}/SiC is investigated. • Raising the oxidation temperature effectively decreases the density of NITs and N{sub eff}. • The higher oxidation temperature reduces the surface RMS roughness of the grow SiO{sub 2}. • SIMS and XPS results reveal the improvement mechanism of high temperature oxidation. - Abstract: The effect of oxidation temperature on interfacial properties of n-type 4H-SiC metal-oxide-semiconductor capacitors has been systematically investigated. Thermal dry oxidation process with three different oxidation temperatures 1200 °C, 1300 °C and 1350 °C were employed to grow SiO{sub 2} dielectric, following by the standard post-oxidation annealing (POA) in NO ambience at 1175 °C for 2 h. The root mean square (RMS) roughness measured by Atomic Force Microscopy for the thermally grown SiO{sub 2} before POA process is reduced with increasing the oxidation temperature, obtaining an atomically flat surface with a RMS of 0.157 nm from the sample oxidized at 1350 °C. Several kinds of electrical measurements were used to evaluate the densities of near interface traps and effective fixed dielectric charge for the samples, exhibiting a trend reduced with increasing the oxidation temperature. The interface state density of 3 × 10{sup 11} cm{sup −2}eV{sup −1} at 0.2 eV from the conduction band edge was achieved from conductance method measurement for the sample oxidized at 1350 °C. The results from Secondary Ion Mass Spectroscopy and X-ray Photoelectron Spectroscopy demonstrate that high oxidation temperature can reduce the width of transition layer, the excess Si and silicon suboxide compositions near the interface, leading to effective improvement of the interfacial properties.

  15. Dynamic Evolution of Nitric Oxide Detoxifying Flavohemoglobins, a Family of Single-Protein Metabolic Modules in Bacteria and Eukaryotes.

    Science.gov (United States)

    Wisecaver, Jennifer H; Alexander, William G; King, Sean B; Hittinger, Chris Todd; Rokas, Antonis

    2016-08-01

    Due to their functional independence, proteins that comprise standalone metabolic units, which we name single-protein metabolic modules, may be particularly prone to gene duplication (GD) and horizontal gene transfer (HGT). Flavohemoglobins (flavoHbs) are prime examples of single-protein metabolic modules, detoxifying nitric oxide (NO), a ubiquitous toxin whose antimicrobial properties many life forms exploit, to nitrate, a common source of nitrogen for organisms. FlavoHbs appear widespread in bacteria and have been identified in a handful of microbial eukaryotes, but how the distribution of this ecologically and biomedically important protein family evolved remains unknown. Reconstruction of the evolutionary history of 3,318 flavoHb protein sequences covering the family's known diversity showed evidence of recurrent HGT at multiple evolutionary scales including intrabacterial HGT, as well as HGT from bacteria to eukaryotes. One of the most striking examples of HGT is the acquisition of a flavoHb by the dandruff- and eczema-causing fungus Malassezia from Corynebacterium Actinobacteria, a transfer that growth experiments show is capable of mediating NO resistance in fungi. Other flavoHbs arose via GD; for example, many filamentous fungi possess two flavoHbs that are differentially targeted to the cytosol and mitochondria, likely conferring protection against external and internal sources of NO, respectively. Because single-protein metabolic modules such as flavoHb function independently, readily undergo GD and HGT, and are frequently involved in organismal defense and competition, we suggest that they represent "plug-and-play" proteins for ecological arms races. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  16. The nitric-oxide reductase from Paracoccus denitrificans uses a single specific proton pathway.

    Science.gov (United States)

    ter Beek, Josy; Krause, Nils; Reimann, Joachim; Lachmann, Peter; Ädelroth, Pia

    2013-10-18

    The NO reductase from Paracoccus denitrificans reduces NO to N2O (2NO + 2H(+) + 2e(-) → N2O + H2O) with electrons donated by periplasmic cytochrome c (cytochrome c-dependent NO reductase; cNOR). cNORs are members of the heme-copper oxidase superfamily of integral membrane proteins, comprising the O2-reducing, proton-pumping respiratory enzymes. In contrast, although NO reduction is as exergonic as O2 reduction, there are no protons pumped in cNOR, and in addition, protons needed for NO reduction are derived from the periplasmic solution (no contribution to the electrochemical gradient is made). cNOR thus only needs to transport protons from the periplasm into the active site without the requirement to control the timing of opening and closing (gating) of proton pathways as is needed in a proton pump. Based on the crystal structure of a closely related cNOR and molecular dynamics simulations, several proton transfer pathways were suggested, and in principle, these could all be functional. In this work, we show that residues in one of the suggested pathways (denoted pathway 1) are sensitive to site-directed mutation, whereas residues in the other proposed pathways (pathways 2 and 3) could be exchanged without severe effects on turnover activity with either NO or O2. We further show that electron transfer during single-turnover reduction of O2 is limited by proton transfer and can thus be used to study alterations in proton transfer rates. The exchange of residues along pathway 1 showed specific slowing of this proton-coupled electron transfer as well as changes in its pH dependence. Our results indicate that only pathway 1 is used to transfer protons in cNOR.

  17. γ-Irradiation assisted synthesis of graphene oxide sheets supported Ag nanoparticles with single crystalline structure and parabolic distribution from interlamellar limitation

    Energy Technology Data Exchange (ETDEWEB)

    Yue, Yunhao; Zhou, Baoming; Shi, Jie; Chen, Cheng; Li, Nan; Xu, Zhiwei, E-mail: xuzhiwei@tjpu.edu.cn; Liu, Liangsen; Kuang, Liyun; Ma, Meijun; Fu, Hongjun

    2017-05-01

    Highlights: • Graphene oxide sheets supported Ag nanoparticles composites are successfully prepared via γ-irradiation without surfactant or functional agent. • Ag nanoparticles exhibit single crystalline structure and parabolic distribution on the surface of graphene oxide sheets. • Proposing a view that the growth of intercellular AgNPs can be limited by graphite oxide. - Abstract: This paper reported a method to fabricate graphene oxide sheets supported Ag nanoparticles (AgNPs/GOS) with single crystalline structure and parabolic distribution without surfactant or functional agent. We used imidazole silver nitrate as intercalation precursor into the layers of graphite oxide, and subsequently reduction and growth of interlamellar AgNPs were induced via γ-irradiation. The results illustrated that the synergism of interlamellar limitation of graphite oxide and fragmentation ability of γ-irradiation could prevent coalescent reaction of AgNPs with other oligomeric clusters, and the single crystalline and small-sized (below 13.9 nm) AgNPs were prepared. Moreover, the content and size of AgNPs exhibited parabolic distribution on GOS surface because the graphite oxide exfoliated to GOS from the edge to the central area of layers. In addition, complete exfoliation degree of GOS and large-sized AgNPs were obtained simultaneously under suitable silver ions concentration. Optimized composites exhibited outstanding surface-enhanced Raman scattering properties for crystal violet with enhancement factor of 1.3 × 10{sup 6} and detection limit of 1.0 × 10{sup −7} M, indicating that the AgNPs/GOS composites could be applied to trace detection of organic dyes molecules. Therefore, this study presented a strategy for developing GOS supported nanometal with single crystalline structure and parabolic distribution based on γ-irradiation.

  18. γ-Irradiation assisted synthesis of graphene oxide sheets supported Ag nanoparticles with single crystalline structure and parabolic distribution from interlamellar limitation

    International Nuclear Information System (INIS)

    Yue, Yunhao; Zhou, Baoming; Shi, Jie; Chen, Cheng; Li, Nan; Xu, Zhiwei; Liu, Liangsen; Kuang, Liyun; Ma, Meijun; Fu, Hongjun

    2017-01-01

    Highlights: • Graphene oxide sheets supported Ag nanoparticles composites are successfully prepared via γ-irradiation without surfactant or functional agent. • Ag nanoparticles exhibit single crystalline structure and parabolic distribution on the surface of graphene oxide sheets. • Proposing a view that the growth of intercellular AgNPs can be limited by graphite oxide. - Abstract: This paper reported a method to fabricate graphene oxide sheets supported Ag nanoparticles (AgNPs/GOS) with single crystalline structure and parabolic distribution without surfactant or functional agent. We used imidazole silver nitrate as intercalation precursor into the layers of graphite oxide, and subsequently reduction and growth of interlamellar AgNPs were induced via γ-irradiation. The results illustrated that the synergism of interlamellar limitation of graphite oxide and fragmentation ability of γ-irradiation could prevent coalescent reaction of AgNPs with other oligomeric clusters, and the single crystalline and small-sized (below 13.9 nm) AgNPs were prepared. Moreover, the content and size of AgNPs exhibited parabolic distribution on GOS surface because the graphite oxide exfoliated to GOS from the edge to the central area of layers. In addition, complete exfoliation degree of GOS and large-sized AgNPs were obtained simultaneously under suitable silver ions concentration. Optimized composites exhibited outstanding surface-enhanced Raman scattering properties for crystal violet with enhancement factor of 1.3 × 10 6 and detection limit of 1.0 × 10 −7 M, indicating that the AgNPs/GOS composites could be applied to trace detection of organic dyes molecules. Therefore, this study presented a strategy for developing GOS supported nanometal with single crystalline structure and parabolic distribution based on γ-irradiation.

  19. Compositional evolution of Pd-based nanoclusters under thermal annealing in ion implanted SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Mattei, G. E-mail: mattei@padova.infm.it; Battaglin, G.; Bello, V.; Cattaruzza, E.; De Julian, C.; De Marchi, G.; Maurizio, C.; Mazzoldi, P.; Parolin, M.; Sada, C

    2004-06-01

    Sequential ion implantation has been used to synthesize Pd-based alloy nanoclusters in SiO{sub 2}. Three systems have been investigated (PdCu, PdAg and PdFe) in terms of nanocluster formation and stability under thermal annealing. In particular, we focused on the role played by the annealing atmosphere. A comparison is made with similar alloy-based systems obtained by sequential ion implantation in silica of Au-Ag or Au-Cu followed by annealing under similar conditions. Strong similarities have been found in the compositional evolution of Pd-based and Au-based nanoclusters.

  20. Single-Nucleotide Polymorphisms of Genes Involved in Repair of Oxidative DNA Damage and the Risk of Recurrent Depressive Disorder

    Science.gov (United States)

    Czarny, Piotr; Kwiatkowski, Dominik; Toma, Monika; Gałecki, Piotr; Orzechowska, Agata; Bobińska, Kinga; Bielecka-Kowalska, Anna; Szemraj, Janusz; Berk, Michael; Anderson, George; Śliwiński, Tomasz

    2016-01-01

    Background Depressive disorder, including recurrent type (rDD), is accompanied by increased oxidative stress and activation of inflammatory pathways, which may induce DNA damage. This thesis is supported by the presence of increased levels of DNA damage in depressed patients. Such DNA damage is repaired by the base excision repair (BER) pathway. BER efficiency may be influenced by polymorphisms in BER-related genes. Therefore, we genotyped nine single-nucleotide polymorphisms (SNPs) in six genes encoding BER proteins. Material/Methods Using TaqMan, we selected and genotyped the following SNPs: c.-441G>A (rs174538) of FEN1, c.2285T>C (rs1136410) of PARP1, c.580C>T (rs1799782) and c.1196A>G (rs25487) of XRCC1, c.*83A>C (rs4796030) and c.*50C>T (rs1052536) of LIG3, c.-7C>T (rs20579) of LIG1, and c.-468T>G (rs1760944) and c.444T>G (rs1130409) of APEX1 in 599 samples (288 rDD patients and 311 controls). Results We found a strong correlation between rDD and both SNPs of LIG3, their haplotypes, as well as a weaker association with the c.-468T>G of APEXI which diminished after Nyholt correction. Polymorphisms of LIG3 were also associated with early onset versus late onset depression, whereas the c.-468T>G polymorphism showed the opposite association. Conclusions The SNPs of genes involved in the repair of oxidative DNA damage may modulate rDD risk. Since this is an exploratory study, the results should to be treated with caution and further work needs to be done to elucidate the exact involvement of DNA damage and repair mechanisms in the development of this disease. PMID:27866211

  1. ACr{sub 2}O{sub 4} /SiO{sub 2} (A = Zn, Cu, Cd) nanocomposites, their preparation and physical properties

    Energy Technology Data Exchange (ETDEWEB)

    Holec, Petr; Plocek, Jiri; Nemec, Ivan [Institute of Inorganic Chemistry, Academy of Sciences of the CR, 250 68 - Rez (Czech Republic); Vejpravova, Jana Poltierova [Charles University Prague, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Ke Karlovu 5, 121 16 - Prague 2 (Czech Republic); Kitazawa, Hideaki [National Institute for Material, Quantum Beam Center, Neutron Scattering Group, 1-2-2 Sengen, Tsukuba-shi, Ibaraki 305-0047 (Japan); Niznansky, Daniel, E-mail: holec@iic.cas.cz [Charles University Prague, Faculty of Sciences, Department of Inorganic Chemistry, Hlavova 2, 121 16 - Prague 2 (Czech Republic)

    2011-10-29

    This article presents preparation and characterization of zinc, copper and cadmium chromites nanocrystals embedded in a silica matrix. The ZnCr{sub 2}O{sub 4}/SiO{sub 2}, CuCr{sub 2}O{sub 4}/SiO{sub 2} and CdCr{sub 2}O{sub 4}/SiO{sub 2} samples were prepared by a conventional sol-gel method using HNO{sub 3} as an acid catalyst, formamide as a modifier, methanol as a solvent and TEOS. Final heat treatment of the nanocomposites was carried out at temperatures in the range of 900 - 1100 deg. C. The resulting samples were characterized by X-ray diffraction, High Resolution Transmission Electron Microscopy, and magnetic measurements.

  2. Opposite effects of nitric oxide donors on DNA single strand breakage and cytotoxicity caused by tert-butylhydroperoxide

    Science.gov (United States)

    Guidarelli, Andrea; Sestili, Piero; Cantoni, Orazio

    1998-01-01

    The effects of three different NO donors on tert-butylhydroperoxide (tB-OOH)-induced DNA cleavage and toxicity were investigated in U937 cells.Treatment with S-nitroso-N-acetyl-penicillamine (SNAP, 1–30 μM), while not in itself DNA-damaging, potentiated the DNA strand scission induced by 200 μM tB-OOH in a concentration-dependent fashion. The enhancing effects of SNAP were observed with two different techniques for the assessment of DNA damage. Decomposed SNAP was inactive. S-nitrosoglutathione (GSNO, 300 μM) and (Z)-1-[(2-aminoethyl)-N-(2-ammonioethyl) amino]diazen-1-ium-1,2-diolate (DETA-NO, 1 mM) also increased DNA cleavage generated by tB-OOH and these responses, as well as that mediated by SNAP, were prevented by the NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazolin-1-oxyl-3-oxide (PTIO).SNAP neither inhibited catalase activity nor increased the formation of DNA lesions in cells exposed to H2O2. Furthermore, SNAP did not affect the rate of rejoining of the DNA single strand breaks generated by tB-OOH.Under the conditions utilized in the DNA damage experiments, treatment with tB-OOH alone or associated with SNAP did not cause cell death. However, SNAP as well as GSNO markedly reduced the lethal response promoted by millimolar concentrations of tB-OOH and these effects were abolished by PTIO. Decomposed SNAP was inactive.It is concluded that low levels of NO donors, which probably release physiological concentrations of NO, enhance the accumulation of DNA single strand breaks in U937 cells exposed to tB-OOH. This NO-mediated effect appears to (a) not depend on inhibition of either DNA repair (which would increase the net accumulation of DNA lesions by preventing DNA single strand break removal) or catalase activity (which would also enhance the net accumulation of DNA lesions since H2O2 is one of the species mediating the tB-OOH-induced DNA cleavage) and (b) be caused by enforced formation of tB-OOH-derived DNA-damaging species. In contrast to

  3. A single exposure to iron oxide nanoparticles attenuates antigen-specific antibody production and T-cell reactivity in ovalbumin-sensitized BALB/c mice

    Directory of Open Access Journals (Sweden)

    Shen CC

    2011-06-01

    Full Text Available Chien-Chang Shen1, Chia-Chi Wang1, Mei-Hsiu Liao2, Tong-Rong Jan11Department and Graduate Institute of Veterinary Medicine, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan; 2Division of Isotope Application, Institute of Energy Research, Taoyuan, TaiwanBackground: Superparamagnetic iron oxide nanoparticles have been used in clinical applications as a diagnostic contrasting agent. Previous studies showed that iron oxide nanoparticles deposited in the liver and spleen after systemic administration. The present study investigated the effect of iron oxide nanoparticles on antigen-specific immune responses in mice sensitized with the T cell-dependent antigen ovalbumin (OVA.Methods: BALB/c mice were intravenously administered with a single dose of iron oxide nanoparticles (10-60 mg Fe/kg 1 hour prior to OVA sensitization, and the serum antibody production and splenocyte reactivity were examined 7 days later.Results: The serum levels of OVA-specific IgG1 and IgG2a were significantly attenuated by treatment with iron oxide nanoparticles. The production of interferon-γ and interleukin-4 by splenocytes re-stimulated with OVA in culture was robustly suppressed in mice administered with iron oxide nanoparticles. The viability of OVA-stimulated splenocytes was also attenuated. In contrast, treatment with iron oxide nanoparticles did not affect the viability of splenocytes stimulated with concanavalin A, a T-cell mitogen.Conclusion: Collectively, these data indicate that systemic exposure to a single dose of iron oxide nanoparticles compromises subsequent antigen-specific immune reactions, including the serum production of antigen-specific antibodies, and the functionality of T cells.Keywords: iron oxide nanoparticle, antigen-specific, immune, ovalbumin

  4. Characterizing uranium oxide reference particles for isotopic abundances and uranium mass by single particle isotope dilution mass spectrometry

    International Nuclear Information System (INIS)

    Kraiem, M.; Richter, S.; Erdmann, N.; Kühn, H.; Hedberg, M.; Aregbe, Y.

    2012-01-01

    Highlights: ► A method to quantify the U mass in single micron particles by ID-TIMS was developed. ► Well-characterized monodisperse U-oxide particles produced by an aerosol generator were used. ► A linear correlation between the mass of U and the volume of particle(s) was found. ► The method developed is suitable for determining the amount of U in a particulate reference material. - Abstract: Uranium and plutonium particulate test materials are becoming increasingly important as the reliability of measurement results has to be demonstrated to regulatory bodies responsible for maintaining effective nuclear safeguards. In order to address this issue, the Institute for Reference Materials and Measurements (IRMM) in collaboration with the Institute for Transuranium Elements (ITU) has initiated a study to investigate the feasibility of preparing and characterizing a uranium particle reference material for nuclear safeguards, which is finally certified for isotopic abundances and for the uranium mass per particle. Such control particles are specifically required to evaluate responses of instruments based on mass spectrometric detection (e.g. SIMS, TIMS, LA-ICPMS) and to help ensuring the reliability and comparability of measurement results worldwide. In this paper, a methodology is described which allows quantifying the uranium mass in single micron particles by isotope dilution thermal ionization mass spectrometry (ID-TIMS). This methodology is characterized by substantial improvements recently achieved at IRMM in terms of sensitivity and measurement accuracy in the field of uranium particle analysis by TIMS. The use of monodisperse uranium oxide particles prepared using an aerosol generation technique developed at ITU, which is capable of producing particles of well-characterized size and isotopic composition was exploited. The evidence of a straightforward correlation between the particle volume and the mass of uranium was demonstrated in this study

  5. Interface characteristics of spin-on-dielectric SiO{sub x}-buffered passivation layers for AlGaN/GaN high electron mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Pil-Seok; Park, Kyoung-Seok; Yoon, Yeo-Chang [Division of Electronics and Electrical Engineering, Dongguk University, 100-715 Seoul (Korea, Republic of); Sheen, Mi-Hyang [Department of Materials Science Engineering, Seoul National University, 151-742 Seoul (Korea, Republic of); Kim, Sam-Dong, E-mail: samdong@dongguk.edu [Division of Electronics and Electrical Engineering, Dongguk University, 100-715 Seoul (Korea, Republic of)

    2015-08-31

    To reveal the cause for significant enhancement of dc current performance of the AlGaN/GaN high electron mobility transistors (HEMTs) with the spin-on-dielectric (SOD) SiO{sub x}-buffered passivation structure compared to the conventional Si{sub 3}N{sub 4} passivation deposited by plasma-enhanced vapor deposition (PECVD), we characterized the passivation interfaces using the cross-sectional transmission electron microscopy, cathodoluminescence, capacitance–voltage (C–V) characterizations, and Hall-effect measurements. The interface state density of PECVD Si{sub 3}N{sub 4} passivation was in the range of 10{sup 12}–10{sup 13} cm{sup −2} eV{sup −1}, which is one-order higher than that of the SOD (10{sup 11}–10{sup 12} cm{sup −2} eV{sup −1}) as measured by C–V measurements from the metal–insulator–semiconductor capacitors. Higher density of effective oxide charge density (especially dominant contribution of ionic mobile charge) was also derived from the PECVD Si{sub 3}N{sub 4} passivation. A well-resolved reduction of the electron Hall mobility of the Si{sub 3}N{sub 4} passivation compared to that of the perhydropolysilazane SOD passivation, which can be due to the higher-density interface states and trap charges, can answer the relative dc current collapse of our HEMT devices. - Highlights: • Spin-on-dielectric (SOD)-buffered passivation for AlGaN/GaN HEMTs • Characterize the charge density and interface states using the C–V measurements • SOD-buffered passivation minimizes surface states at the interface. • DC performance of SOD-buffered structure is due to the interface characteristics.

  6. FEM for modelling 193 nm excimer laser treatment of SiO{sub 2}/Si/Si{sub (1-x)}Ge{sub x} heterostructures on SOI substrates

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C.; Chiussi, S.; Gontad, F.; Gonzalez, P. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, 36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas, Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, 36310 Vigo (Spain)

    2011-03-15

    Research on epitaxial crystalline silicon (c-Si) and silicon-germanium (Si{sub 1-x}Ge{sub x}) alloys growth and annealing for microelectronic purposes, such as Micro- or Nano-Electro-Mechanical Systems (MEMS or NEMS) and Silicon-On-Nothing (SON) devices is continuously in progress. Laser assisted annealing techniques using commercial ArF Excimer Laser sources are based on ultra-rapid heating and cooling cycles induced by the 193 nm pulses of 20 ns, which are absorbed in the near surface region of the heterostructures. During and after the absorption of these laser pulses, complex physical processes appear that strongly depend on sample structure and applied laser pulse energy densities. The control of the experimental parameters is therefore a key task for obtaining high quality alloys. The Finite ElementsMethod (FEM) is a powerful tool for the optimization of such treatments, because it provides the spatial and temporal temperature fields that are produced by the laser pulses. In this work, we have used a FEM commercial software, to predict the temperatures gradients induced by ArF excimer laser over a wide energy densities range, 0.1<{phi}<0.4 J/cm{sup 2}, on different SiO{sub 2}/Si/Si{sub (1-x)}Ge{sub (x)} thin films deposited on SOI substrate. These numerical results allow us to predict the threshold energies needed to reach the melting point (MP) of the Si and SiGe alloy without oxidation of the thin films system. Therefore, it is possible to optimize the conditions to achieve high quality epitaxy films. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. One single catalyst, Pd(OAc)2, for two sequential very different steps: allylic alcohol oxidation-Heck reaction. Access to functionalised alpha,beta-unsaturated ketones.

    Science.gov (United States)

    Batt, Frédéric; Gozzi, Christel; Fache, Fabienne

    2008-11-30

    A single addition of the catalyst, Pd(OAc)(2), was realised to mediate two transformations as different as allylic alcohol oxidation under O(2) and C-C bond formation of the Heck type, to give substituted alpha,beta-unsaturated ketones without intermediate purification.

  8. Activation of surface lattice oxygen in single-atom Pt/CeO 2 for low-temperature CO oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Nie, Lei; Mei, Donghai; Xiong, Haifeng; Peng, Bo; Ren, Zhibo; Pereira Hernandez, Xavier I.; DelaRiva, Andrew; Wang, Meng; Engelhard, Mark H.; Kovarik, Libor; Datye, Abhaya K.; Wang, Yong

    2017-12-14

    While single-atom catalysts can provide high catalytic activity and selectivity, application in industrial catalysts demands long term performance and the ability to regenerate the catalysts. We have investigated the factors that lead to improved catalytic activity of a Pt/CeO2 catalyst for low temperature CO oxidation. Single-atom Pt/CeO2 becomes active for CO oxidation under lean condition only at elevated temperatures, because CO is strongly bound to ionic Pt sites. Reducing the catalyst, even under mild conditions, leads to onset of CO oxidation activity even at room temperature. This high activity state involves the transformation of mononuclear Pt species to sub-nanometer sized Pt particles. Under oxidizing conditions, the Pt can be restored to its stable, single-atom state. The key to facile regeneration is the ability to create mobile Pt species and suitable trapping sites on the support, making this a prototypical catalyst system for industrial application of single-atom catalysis.

  9. A self-seeded, surfactant-directed hydrothermal growth of single crystalline lithium manganese oxide nanobelts from the commercial bulky particles.

    Science.gov (United States)

    Zhang, Lizhi; Yu, Jimmy C; Xu, An-Wu; Li, Quan; Kwong, Kwan Wai; Wu, Ling

    2003-12-07

    Single crystalline lithium manganese oxide nanobelts were obtained through a self-seeded, surfactant-directed growth process from the commercial bulky particles under hydrothermal treatment. A possible mechanism was proposed to explain the growth of the nanobelts. This new process could be extended to prepare other one-dimensional nanomaterials such as Se nanorods, Te nanotubes, and MnO2 nanowires.

  10. The electro-oxidation of the mixture of formaldehyde and 2-propanol on gold (100 and (111 single crystal planes in alkaline medium

    Directory of Open Access Journals (Sweden)

    BRANISLAV Z. NIKOLIC

    2000-12-01

    Full Text Available The effect of formaldehyde on the oxidation of 2-propanol and vice versa on gold single crystal planes (100 and 111 was studied. An activating effect in the reaction of the simultaneous oxidation of 2-propanol and formaldehyde was obtained on a gold (100 plane. In the case of a gold (111 electrode, the activation effect was not obtained. It was concluded that the adsorption of formaldehyde on the electrode surface prevents the adsorption of poisoning species formed during the electro-oxidation of 2-propanol on the Au(100 plane, while this is not the case on the Au(111 plane. The different behaviour is caused by the difference in the symmetry of the surface atoms of these two Au single-crystal planes.

  11. Pulmonary exposure to particles from diesel exhaust, urban dust or single-walled carbon nanotubes and oxidatively damaged DNA and vascular function in apoE(-/-)mice

    DEFF Research Database (Denmark)

    Vesterdal, Lise K; Jantzen, Kim; Sheykhzade, Majid

    2012-01-01

    Abstract This study compared the oxidative stress level and vasomotor dysfunction after exposure to urban dust, diesel exhaust particles (DEP) or single-walled carbon nanotubes (SWCNT). DEP and SWCNT increased the production of reactive oxygen species (ROS) in cultured endothelial cells and acell......Abstract This study compared the oxidative stress level and vasomotor dysfunction after exposure to urban dust, diesel exhaust particles (DEP) or single-walled carbon nanotubes (SWCNT). DEP and SWCNT increased the production of reactive oxygen species (ROS) in cultured endothelial cells...... and acellullarly, whereas the exposure to urban dust did not generate ROS. ApoE(-/-) mice, which were exposed twice to 0.5 mg/kg of the particles by intratracheal instillation, had unaltered acetylcholine-elicited vasorelaxation in aorta segments. There was unaltered pulmonary expression level of Vcam-1, Icam-1...... instillation of the same particles had no effect on biomarkers of pulmonary oxidative stress and dilatory dysfunction in the aorta....

  12. Single Nanoparticle Mass Spectrometry as a High Temperature Kinetics Tool: Sublimation, Oxidation, and Emission Spectra of Hot Carbon Nanoparticles.

    Science.gov (United States)

    Howder, Collin R; Long, Bryan A; Gerlich, Dieter; Alley, Rex N; Anderson, Scott L

    2015-12-17

    In single nanoparticle mass spectrometry, individual charged nanoparticles (NPs) are trapped in a quadrupole ion trap and detected optically, allowing their mass, charge, and optical properties to be monitored continuously. Previous experiments of this type probed NPs that were either fluorescent or large enough to detect by light scattering. Alternatively, small NPs can be heated to temperatures where thermally excited emission is strong enough to allow detection, and this approach should provide a new tool for measurements of sublimation and surface reaction kinetics of materials at high temperatures. As an initial test, we report a study of carbon NPs in the 20-50 nm range, heated by 10.6 μm, 532 nm, or 445 nm lasers. The kinetics for sublimation and oxidation of individual carbon NPs were studied, and a model is presented for the factors that control the NP temperature, including laser heating, and cooling by sublimation, buffer gas collisions, and radiation. The estimated NP temperatures were in the 1700-2000 K range, and the NP absorption cross sections ranged from ∼0.8 to 0.2% of the geometric cross sections for 532 nm and 10.6 μm excitation, respectively. Emission spectra of single NPs and small NP ensembles show a feature in the IR that appears to be the high energy tail of the thermal (blackbody-like) emission expected from hot particles but also a discrete feature peaking around 750 nm. Both the IR tail and 750 nm peak are observed for all particles and for both IR and visible laser excitation. No significant difference was observed between graphite and amorphous carbon NPs.

  13. Measurements of exhaled nitric oxide with the single-breath technique and positive expiratory pressure in infants.

    Science.gov (United States)

    Wildhaber, J H; Hall, G L; Stick, S M

    1999-01-01

    The aim of this study was to adapt the single-breath technique with positive expiratory pressure to measure exhaled nitric oxide (eNO) in infants. We hypothesized that exhaled eNO was greater in wheezy than in healthy infants. We studied 30 infants (16 wheezy and 14 healthy). The forced expiratory volume in 0.5 s (FEV0.5) was determined with the raised volume rapid thoracic compression technique, and eNO was measured during constant expiratory flow with a rapid-response chemiluminescence analyzer. After passive inflation to a preset pressure of 20 cm H2O, thoracic compression with an inflatable jacket caused forced expiration to occur through a face-mask with an expiratory flow resistor attached. During the forced expiration, the jacket pressure was increased to maintain a constant driving mouth pressure and hence a constant expiratory flow (50 ml/s). The mean level of eNO in the wheezy infants (31.8 ppb) was significantly higher than the level in healthy infants (18.8 ppb) (p = 0.03). A family history of atopy in parents was associated with increased eNO levels (p history of atopy.

  14. Charge transport and glassy dynamics of poly(ethylene oxide)-based single-ion conductors under geometrical confinement

    Science.gov (United States)

    Runt, James; Iacob, Ciprian

    2015-03-01

    Segmental and local dynamics as well as charge transport are investigated in a series of poly(ethylene oxide)-based single-ion conductors (ionomers) with varying counterions (Li +, Na +) confined in uni-directional nanoporous silica membranes. The dynamics are explored over a wide frequency and temperature range by broadband dielectric relaxation spectroscopy. Slowing of segmental dynamics and a decrease in dc conductivity (strongly coupled with segmental relaxation) of the confined ionomers are associated with surface effects - resulting from interfacial hydrogen bonding between the host nanoporous silica membrane and the guest ionomers. These effects are significantly reduced or eliminated upon pore surface modification through silanization. The primary transport properties for the confined ionomers decrease by about one decade compared to the bulk ionomer. A model assuming reduced mobility of an adsorbed layer at the pore wall/ionomer interface is shown to provide a quantitative explanation for the decrease in effective transport quantities in non-silanized porous silica membranes. Additionally, the effect of confinement on ion aggregation in ionomers by using X-ray scattering will also be discussed. Supported by the National Science Foundation, Polymers Program.

  15. A single step solid-phase extraction method for complete separation of sterol oxidation products in food lipids.

    Science.gov (United States)

    Azadmard-Damirchi, Sodeif; Dutta, Paresh C

    2009-01-02

    One of the crucial steps in determination of sterol oxidation products (SOPs) in foods is their enrichment and purifications by various preparative methods for further analysis by GC and GC-MS. Among the preparative methods, SPE of various adsorbents and solvent systems, are being used most widely. At present, no single step SPE method is suitable to completely separate the SOPs. In this study, a SPE (1g silica) method, suitable for both transesterified and cold saponified oil samples, was developed to separate completely SOPs from other lipid components. This method resulted in high recovery from rapeseed oil of added 5beta,6beta-epoxycholestan-3beta-ol (94-96%), cholest-5-en-3beta-ol-7-one(94%), cholestane-3beta,5alpha,6beta-triol (88-91%), cholest-5-en-3beta,7alpha-diol and 5alpha,6alpha-epoxycholestan-3beta-ol (88-90%). The method has a high sample capacity of up to 1g transesterified or cold-saponified oil sample. The method was tested and applied to different vegetable oils and to monitor the effects of refining processes on POPs in hazelnut oil.

  16. Fabrication of water-dispersible single-walled carbon nanotube powder using N-methylmorpholine N-oxide

    Science.gov (United States)

    Choi, Hyejun; Woo, Jong Seok; Tark Han, Joong; Park, Soo-Young

    2017-11-01

    Dispersion of nanocarbon materials in liquid media, via solution processing such as spraying, printing, spinning, etc. is one of the prerequisites for practical applications. Here we report that water-dispersible single-walled carbon nanotubes (SWCNTs) were prepared through successive treatments with chlorosulfuric acid (CSA)/H2O2 and N-methylmorpholine N-oxide (NMO) monohydrate. The powder of the CSA/H2O2- and NMO-treated SWCNTs (N-SWCNTs) could be readily redispersed in water in concentrations as high as 1 g l‑1 without requiring a dispersant. The mechanism responsible for the high dispersity of the N-SWCNT powder in polar solvents, including water, was elucidated based on the high polarity of the NMO molecule. In order to highlight the wide applicability of the N-SWCNTs, they were used successfully to prepare conducting thin films by spray-coating plastic substrates with an aqueous hybrid solution containing the N-SWCNTs and Ag nanowires (NWs). In addition, a flexible, large-area thin-film heater was prepared based on the N-SWCNT/AgNW hybrid film with a transmittance of 93% and sheet resistance of 30 Ω sq‑1.

  17. Comparative analysis on surface property in anodic oxidation polishing of reaction-sintered silicon carbide and single-crystal 4H silicon carbide

    Science.gov (United States)

    Shen, Xinmin; Tu, Qunzhang; Deng, Hui; Jiang, Guoliang; He, Xiaohui; Liu, Bin; Yamamura, Kazuya

    2016-04-01

    For effective machining of difficult-to-machine materials, such as reaction-sintered silicon carbide (RS-SiC) and single-crystal 4H silicon carbide (4H-SiC), a novel polishing technique named anodic oxidation polishing was proposed, which combined with the anodic oxidation of substrate and slurry polishing of oxide. By scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDX) observation and atomic force microscopy analysis, both the anodic oxidation behaviors of RS-SiC and 4H-SiC were investigated. Through comparison of the surfaces before and after hydrofluoric acid etching of the oxidized samples by the scanning white light interferometry (SWLI) measurement, the relationships between oxidation depth and oxidation time were obtained, and the calculated oxidation rate for RS-SiC was 5.3 nm/s and that for 4H-SiC was 5.8 nm/s based on the linear Deal-Grove model. Through anodic oxidation polishing of RS-SiC substrate and 4H-SiC substrate, respectively, the surface roughness rms obtained by SWLI was improved to 2.103 nm for RS-SiC and to 0.892 nm for 4H-SiC. Experimental results indicate that anodic oxidation polishing is an effective method for the machining of RS-SiC and 4H-SiC samples, which would improve the process level of SiC substrates and promote the application of SiC products in the fields of optics, ceramics, semiconductors, electronics, and so on.

  18. Synthesis of ceramic powders of La{sub 9,56} (SiO{sub 4}){sub 6}O{sub 2,34} and La{sub 9,8}Si{sub 5,7}Mg{sub O,3}O{sub 26,}4 by modified sol-gel process; Sintese de pos ceramicos de La{sub 9,56} (SiO{sub 4}){sub 6}O{sub 2,34} e La{sub 9,8}Si{sub 5,7}Mg{sub O,3}O{sub 26,}4 por processo sol-gel modificado

    Energy Technology Data Exchange (ETDEWEB)

    Lira, Sabrina Lopes; Paiva, Mayara Rafaela Soares; Misso, Agatha Matos; Elias, Daniel Ricco; Yamagata, Chieko, E-mail: yamagata@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais

    2012-07-01

    Lanthanum silicate oxyapatite materials are promising for application as electrolyte in solid oxide fuel cells because of high ionic conductivity at temperatures between 600 deg C and 800 deg C. In this work, oxyapatites with the composition La{sub 9,56}(SiO{sub 4}){sub 6}O{sub 2,34}, and La{sub 9,8}Si{sub 5,7}Mg{sub 0,3}O{sub 26,4} were synthesized by using the sol-gel method, followed by precipitation. Initially, the gel of silica was synthesized from sodium silicate solution, by acid catalysis using lanthanum and magnesium chloride solution. Then, the La and Mg hydroxides were precipitated with NaOH in the gel. The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and measurements of specific surface area. The crystalline oxyapatite phase of La{sub 9,56}(SiO{sub 4}){sub 6}O{sub 2,34}, and was La{sub 9,8}Si{sub 5,7}Mg{sub 0,3}O{sub 26,4} obtained by calcination at 900 deg C for 2 and 1h respectively (author)

  19. Mechanism of oxidation protection of the Si(001) surface by sub-monolayer Sr template

    Energy Technology Data Exchange (ETDEWEB)

    Fredrickson, Kurt D.; Seo, Hosung; Demkov, Alexander A., E-mail: demkov@physics.utexas.edu [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)

    2016-08-14

    We investigate theoretically the oxidation stability of the Si(001) (2 × 1) reconstructed surface passivated by Sr. Using density functional theory, we find that the Sr surface with ½ monolayer of Sr is protected against oxidation. The presence of Sr delays the oxidation of the surface dimer, and even when the dimer is oxidized, O does not react with the back-bond, preventing the unwanted vertical growth of SiO{sub 2}. We also show that ¼ monolayer of Sr protects the Si surface in a different way. In the presence of ¼ monolayer of Sr, O atoms are attracted to the Sr-Si dimer complexes, thus preventing the formation of SiO{sub 2}.

  20. Photocatalytic segmented nanowires and single-step iron oxide nanotube synthesis: Templated electrodeposition as all-round tool

    NARCIS (Netherlands)

    Maas, M.G.; Rodijk, E.J.B.; Maijenburg, A.W.; ten Elshof, Johan E.; Blank, David H.A.; Nielsch, K.; Fontcuberta i Morral, A.; Holt, J.K.; Thomson, C.V.

    2010-01-01

    Templated electrodeposition was used to synthesize silver-zinc oxide nanowires and iron oxide (Fe2O3) nanotubes in polycarbonate track etched (PCTE) membranes. Metal/oxide segmented nanowires were made to produce hydrogen gas from a water/methanol mixture under ultraviolet irradiation. It was

  1. Structural and magnetic studies of Fe{sub 2}O{sub 3}/SiO{sub 2} granular nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Pozo-Lopez, G., E-mail: gpozo@famaf.unc.edu.a [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, 5000 Cordoba (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Silvetti, S.P. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, 5000 Cordoba (Argentina); Cabrera, A.F. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de la Plata, 1900 La Plata (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Condo, A.M. [Centro Atomico Bariloche, Comision Nacional de Energia Atomica - Instituto Balseiro, Universidad Nacional de Cuyo, 8400 S.C. de Bariloche, Rio Negro (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina)

    2009-10-01

    Fe{sub 2}O{sub 3}/SiO{sub 2} nanocomposites were synthesized by mechanical alloying, using Fe and SiO{sub 2} powders as precursors. After 340 h milling, the sample essentially consists of hematite and amorphous silica. TEM images show hematite particles embedded in and surrounded by an amorphous silica matrix. A broad size distribution-5-50 nm-of hematite particles is found, and other group of very small-2-3 nm-unidentified particles are observed. Room temperature Moessbauer spectra show a paramagnetic doublet, which may correspond to a non-crystalline phase in the sample (probably the small unidentified particles), and a sextet corresponding to hematite. Magnetic properties were investigated by measuring hysteresis curves at different temperatures (5-300 K) and by zero-field-cooled (ZFC) and field-cooled (FC) magnetization curves (10 mT). The hysteresis loops were well fitted by a ferromagnetic contribution. No evidence of Morin transition is found down to 5 K.

  2. Low temperature deposition: Properties of SiO{sub 2} films from TEOS and ozone by APCVD system

    Energy Technology Data Exchange (ETDEWEB)

    Juarez, H; Diaz, T; Rosendo, E; Garcia, G; Mora, F; Escalante, G [Centro de Investigacion en Dispositivos Semiconductores, Universidad Autonoma de Puebla, 14 Sur and Av. San Claudio, San Manuel 72000, Puebla (Mexico); Pacio, M; GarcIa, A, E-mail: hjuarez@cs.buap.m [Ingenieria Electrica, Secciaan Electranica del Estado Salido, Centro de Investigacian y de Estudios Avanzados del I. P. N., Av. Instituto Politecnico Nacional 2508, San Pedro Zacatenco, 07360 Mexico, D. F. (Mexico)

    2009-05-01

    An Atmospheric Pressure Chemical Vapor Deposition (APCVD) system was implemented for SiO{sub 2} nanometric films deposition on silicon substrates. Tetraethoxysilane (TEOS) and ozone (O{sub 3}) were used and they were mixed into the APCVD system. The deposition temperatures were very low, from 125 to 250 {sup 0}C and the deposition time ranged from 1 to 15 minutes. The measured thicknesses from the deposited SiO{sub 2} films were between 5 and 300 nm. From the by Fourier-Transform Infrared (FTIR) spectra the typical absorption bands of the Si-O bond were observed and it was also observed a dependence on the vibrational modes corresponding to hydroxyl groups with the deposition temperature where the intensity of these vibrations can be related with the grade porosity grade of the films. Furthermore an analytical model has been evoked to determine the activation energy of the reactions in the surface and the gas phase in the deposit films process.

  3. Effect of SiO{sub 2} coating in bolometric Ge light detectors for rare event searches

    Energy Technology Data Exchange (ETDEWEB)

    Beeman, J.W. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Gentils, A. [Centre de Spectrométrie Nuclaire et de Spectrométrie de Masse, CNRS and Université Paris-Sud, F-91405 Orsay (France); Giuliani, A., E-mail: andrea.giuliani@csnsm.in2p3.fr [Centre de Spectrométrie Nuclaire et de Spectrométrie de Masse, CNRS and Université Paris-Sud, F-91405 Orsay (France); Università dell' Insubria, Dipartimento di Scienza e Alta Tecnologia, 22100 Como, Italy, (Italy); INFN, Sezione di Milano Bicocca, 20126 Milano (Italy); Mancuso, M. [Università dell' Insubria, Dipartimento di Scienza e Alta Tecnologia, 22100 Como, Italy, (Italy); INFN, Sezione di Milano Bicocca, 20126 Milano (Italy); Pessina, G. [Università di Milano-Bicocca, Dipartimento di Fisica, and INFN, Sezione di Milano Bicocca, 20126 Milano (Italy); Plantevin, O. [Centre de Spectrométrie Nuclaire et de Spectrométrie de Masse, CNRS and Université Paris-Sud, F-91405 Orsay (France); Rusconi, C. [Università dell' Insubria, Dipartimento di Scienza e Alta Tecnologia, 22100 Como, Italy, (Italy); INFN, Sezione di Milano Bicocca, 20126 Milano (Italy)

    2013-05-01

    In germanium-based light detectors for scintillating bolometers, a SiO{sub 2} anti-reflective coating is often applied on the side of the germanium wafer exposed to light with the aim to improve its light collection efficiency. In this paper, we report about a measurement, performed in the temperature range 25–35 mK, of the light-collection increase obtained thanks to this method, which resulted to be of the order of 20%. The procedure followed has been carefully selected in order to minimize systematic effects. The employed light sources have the same spectral features (peaking at ∼630nm wavelength) that will characterize future neutrinoless double beta decay experiments on the isotope {sup 82}Se and based on ZnSe crystals, such as LUCIFER. The coupling between source and light detector reproduces the configuration used in scintillating bolometers. The present measurement clarifies the role of SiO{sub 2} coating and describes a method and a set-up that can be extended to the study of other types of coatings and luminescent materials.

  4. Sealing materials for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, P.H.

    1999-02-01

    A major obstacle in the achievement of high electrical efficiency for planar solid oxide fuel cell stacks (SOFC) is the need for long term stable seals at the operational temperature between 850 and 1000 deg. C. In the present work the formation and properties of sealing materials for SOFC stacks that fulfil the necessary requirements were investigated. The work comprises analysis of sealing material properties independently, in simple systems as well as tests in real SOFC stacks. The analysed sealing materials were based on pure glasses or glass-ceramic composites having B{sub 2}O{sub 3}, P{sub 2}O{sub 5} or siO{sub 2} as glass formers, and the following four glass systems were investigated: MgO/caO/Cr{sub 2}O{sub 3}-Al{sub 2}O{sub 3}B{sub 2}O{sub 3}-P{sub 2}O{sub 5}, MgO-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5}, MgO-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5}-SiO{sub 2} and BaO/Na{sub 2}O-Al{sub 2}O{sub 3}-SiO{sub 2}. (au) 32 tabs., 106 ills., 107 refs.

  5. Barium oxide, calcium oxide, magnesia, and alkali oxide free glass

    Science.gov (United States)

    Lu, Peizhen Kathy; Mahapatra, Manoj Kumar

    2013-09-24

    A glass composition consisting essentially of about 10-45 mole percent of SrO; about 35-75 mole percent SiO.sub.2; one or more compounds from the group of compounds consisting of La.sub.2O.sub.3, Al.sub.2O.sub.3, B.sub.2O.sub.3, and Ni; the La.sub.2O.sub.3 less than about 20 mole percent; the Al.sub.2O.sub.3 less than about 25 mole percent; the B.sub.2O.sub.3 less than about 15 mole percent; and the Ni less than about 5 mole percent. Preferably, the glass is substantially free of barium oxide, calcium oxide, magnesia, and alkali oxide. Preferably, the glass is used as a seal in a solid oxide fuel/electrolyzer cell (SOFC) stack. The SOFC stack comprises a plurality of SOFCs connected by one or more interconnect and manifold materials and sealed by the glass. Preferably, each SOFC comprises an anode, a cathode, and a solid electrolyte.

  6. PEGylated single-walled carbon nanotubes activate neutrophils to increase production of hypochlorous acid, the oxidant capable of degrading nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Vlasova, Irina I., E-mail: irina.vlasova@yahoo.com [Research Institute for Physico-Chemical Medicine, Federal Medico-Biological Agency, Moscow (Russian Federation); Vakhrusheva, Tatyana V. [Research Institute for Physico-Chemical Medicine, Federal Medico-Biological Agency, Moscow (Russian Federation); Sokolov, Alexey V.; Kostevich, Valeria A. [Research Institute for Physico-Chemical Medicine, Federal Medico-Biological Agency, Moscow (Russian Federation); Research Institute for Experimental Medicine, Russian Academy of Medical Science, Saint Petersburg (Russian Federation); Gusev, Alexandr A.; Gusev, Sergey A. [Research Institute for Physico-Chemical Medicine, Federal Medico-Biological Agency, Moscow (Russian Federation); Melnikova, Viktoriya I. [Institute of Developmental Biology, Russian Academy of Science, Moscow (Russian Federation); Lobach, Anatolii S. [Institute of Problems of Chemical Physics, Russian Academy of Science, Chernogolovka (Russian Federation)

    2012-10-01

    Perspectives for the use of carbon nanotubes in biomedical applications depend largely on their ability to degrade in the body into products that can be easily cleared out. Carboxylated single-walled carbon nanotubes (c-SWCNTs) were shown to be degraded by oxidants generated by peroxidases in the presence of hydrogen peroxide. In the present study we demonstrated that conjugation of poly(ethylene glycol) (PEG) to c-SWCNTs does not interfere with their degradation by peroxidase/H{sub 2}O{sub 2} system or by hypochlorite. Comparison of different heme-containing proteins for their ability to degrade PEG-SWCNTs has led us to conclude that the myeloperoxidase (MPO) product hypochlorous acid (HOCl) is the major oxidant that may be responsible for biodegradation of PEG-SWCNTs in vivo. MPO is secreted mainly by neutrophils upon activation. We hypothesize that SWCNTs may enhance neutrophil activation and therefore stimulate their own biodegradation due to MPO-generated HOCl. PEG-SWCNTs at concentrations similar to those commonly used in in vivo studies were found to activate isolated human neutrophils to produce HOCl. Both PEG-SWCNTs and c-SWCNTs enhanced HOCl generation from isolated neutrophils upon serum-opsonized zymosan stimulation. Both types of nanotubes were also found to activate neutrophils in whole blood samples. Intraperitoneal injection of a low dose of PEG-SWCNTs into mice induced an increase in percentage of circulating neutrophils and activation of neutrophils and macrophages in the peritoneal cavity, suggesting the evolution of an inflammatory response. Activated neutrophils can produce high local concentrations of HOCl, thereby creating the conditions favorable for degradation of the nanotubes. -- Highlights: ► Myeloperoxidase (MPO) product hypochlorous acid is able to degrade CNTs. ► PEGylated SWCNTs stimulate isolated neutrophils to produce hypochlorous acid. ► SWCNTs are capable of activating neutrophils in blood samples. ► Activation of

  7. γ-Irradiation assisted synthesis of graphene oxide sheets supported Ag nanoparticles with single crystalline structure and parabolic distribution from interlamellar limitation

    Science.gov (United States)

    Yue, Yunhao; Zhou, Baoming; Shi, Jie; Chen, Cheng; Li, Nan; Xu, Zhiwei; Liu, Liangsen; Kuang, Liyun; Ma, Meijun; Fu, Hongjun

    2017-05-01

    This paper reported a method to fabricate graphene oxide sheets supported Ag nanoparticles (AgNPs/GOS) with single crystalline structure and parabolic distribution without surfactant or functional agent. We used imidazole silver nitrate as intercalation precursor into the layers of graphite oxide, and subsequently reduction and growth of interlamellar AgNPs were induced via γ-irradiation. The results illustrated that the synergism of interlamellar limitation of graphite oxide and fragmentation ability of γ-irradiation could prevent coalescent reaction of AgNPs with other oligomeric clusters, and the single crystalline and small-sized (below 13.9 nm) AgNPs were prepared. Moreover, the content and size of AgNPs exhibited parabolic distribution on GOS surface because the graphite oxide exfoliated to GOS from the edge to the central area of layers. In addition, complete exfoliation degree of GOS and large-sized AgNPs were obtained simultaneously under suitable silver ions concentration. Optimized composites exhibited outstanding surface-enhanced Raman scattering properties for crystal violet with enhancement factor of 1.3 × 106 and detection limit of 1.0 × 10-7 M, indicating that the AgNPs/GOS composites could be applied to trace detection of organic dyes molecules. Therefore, this study presented a strategy for developing GOS supported nanometal with single crystalline structure and parabolic distribution based on γ-irradiation.

  8. Synthesis and measurements of the optical bandgap of single crystalline complex metal oxide BaCuV2O7 nanowires by UV–VIS absorption

    International Nuclear Information System (INIS)

    Shakir, Imran; Shahid, Muhammad; Aboud, Mohamed F.A.

    2015-01-01

    Highlights: • Synthesis of single crystalline complex metal oxides BaCuV 2 O 7 nanowires. • Surfactant free, economically favorable chemical solution deposition method. • Complex metal oxides nanowires with controlled stoichiometry. • Simply controlling the temperature and thickness of the coated film, we can easily obtain high quality BaCuV 2 O 7 nanowires. - Abstract: The synthesis of single crystalline complex metal oxides BaCuV 2 O 7 nanowires were attained by using surfactant free, economically favorable chemical solution deposition method. A thin layer of BaCuV 2 O 7 nanocrystals is formed by the decomposition of complex metal oxide solution at 150 °C to provide nucleation sites for the growth of nanowires. The synthesized nanowires were typically 1–5 μm long with diameter from 50 to 150 nm. We showed that by simply controlling the temperature and thickness of the coated film, we can easily obtain high quality BaCuV 2 O 7 nanowires. The UV–VIS absorption spectra show indirect bandgap of 2.65 ± 0.05 eV of nanowires. The temperature-dependent resistances of BaCuV 2 O 7 nanowires agree with the exponential correlation, supporting that the conducting carriers are the quasi-free electrons. We believe that our methodology will provides a simple and convenient route for the synthesis of variety of complex metal oxides nanowires with controlled stoichiometry

  9. Influence of gadolinium content on the tetragonal to cubic phase transition in zirconia-silica binary oxides

    Energy Technology Data Exchange (ETDEWEB)

    Behera, Pallavi Suhasinee; Vasanthavel, S.; Ponnilavan, V.; Kannan, S., E-mail: para_kanna@yahoo.com

    2015-05-15

    The present study reports the effect of gadolinium (Gd{sup 3+}) in zirconia-silica (ZrO{sub 2}-SiO{sub 2}) binary oxides. The pure ZrO{sub 2}-SiO{sub 2} synthesized at 1100 °C was tetragonal. The addition of Gd{sup 3+} in the concentration range of 5%–10% resulted in the formation of t-ZrO{sub 2}, whereas higher contents of Gd{sup 3+} led to the formation of cubic ZrO{sub 2} (c-ZrO{sub 2}). The presence of Gd{sup 3+} also affected the lattice parameters of both t-ZrO{sub 2} and c-ZrO{sub 2}. Magnetic studies confirmed a steady increase in the paramagnetic behaviour with increasing content of Gd{sup 3+}. - Graphical abstract: t-ZrO{sub 2} to c-ZrO{sub 2} phase transition influenced by Gd{sup 3+} content. - Highlights: • Sol-gel synthesis of Gd{sup 3+} added SiO{sub 2}-ZrO{sub 2} binary oxides. • Significant role of Gd{sup 3+} content in the tetragonal and cubic stabilization of ZrO{sub 2}. • Phase stability of either tetragonal or cubic stabilization till 1100 °C. • Gd{sup 3+} additions ensured additional paramagnetic behaviour in SiO{sub 2}-ZrO{sub 2} binary oxide.

  10. Controlled reoxygenation during cardiopulmonary bypass decreases markers of organ damage, inflammation, and oxidative stress in single-ventricle patients undergoing pediatric heart surgery.

    Science.gov (United States)

    Caputo, Massimo; Mokhtari, Amir; Miceli, Antonio; Ghorbel, Mohamed T; Angelini, Gianni D; Parry, Andrew J; Suleiman, Saadeh M

    2014-09-01

    Single-ventricle patients undergoing pediatric heart surgery are a high-risk group owing to reoxygenation injury during cardiopulmonary bypass (CPB). The present study investigated the effects of controlled reoxygenation CPB on biomarkers of organ damage, inflammation, stress, and long-term functional outcomes in cyanotic patients with either a single or double ventricle during open heart surgery. Cyanotic patients with either a single (n = 32) or double (n = 47) ventricle undergoing surgical correction were randomized to receive CPB using either standard oxygen levels or controlled reoxygenation. The markers of cardiac injury, inflammation, stress, and cerebral and hepatic injury were measured preoperatively, at 10 and 30 minutes after starting CPB, and at 10 minutes and 4 and 24 hours after CPB. The data were analyzed using a mixed regression model. No difference was found in the pre- or intraoperative characteristics between the standard and controlled reoxygenation CPB groups for single- or double-ventricle patients. In the single-ventricle patients, controlled reoxygenation CPB significantly (P markers of organ damage, inflammation, stress, and oxidative stress. In contrast, the markers of inflammation and cardiac injury were not altered by controlled reoxygenation CPB in the double-ventricle patients. Controlled reoxygenation CPB decreased the markers of organ damage, stress, inflammation, and oxidative stress in single-ventricle patients undergoing cardiac surgery. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  11. Single-Crystal Thin Films of Cesium Lead Bromide Perovskite Epitaxially Grown on Metal Oxide Perovskite (SrTiO3).

    Science.gov (United States)

    Chen, Jie; Morrow, Darien J; Fu, Yongping; Zheng, Weihao; Zhao, Yuzhou; Dang, Lianna; Stolt, Matthew J; Kohler, Daniel D; Wang, Xiaoxia; Czech, Kyle J; Hautzinger, Matthew P; Shen, Shaohua; Guo, Liejin; Pan, Anlian; Wright, John C; Jin, Song

    2017-09-27

    High-quality metal halide perovskite single crystals have low defect densities and excellent photophysical properties, yet thin films are the most sought after material geometry for optoelectronic devices. Perovskite single-crystal thin films (SCTFs) would be highly desirable for high-performance devices, but their growth remains challenging, particularly for inorganic metal halide perovskites. Herein, we report the facile vapor-phase epitaxial growth of cesium lead bromide perovskite (CsPbBr 3 ) continuous SCTFs with controllable micrometer thickness, as well as nanoplate arrays, on traditional oxide perovskite SrTiO 3 (100) substrates. Heteroepitaxial single-crystal growth is enabled by the serendipitous incommensurate lattice match between these two perovskites, and overcoming the limitation of island-forming Volmer-Weber crystal growth is critical for growing large-area continuous thin films. Time-resolved photoluminescence, transient reflection spectroscopy, and electrical transport measurements show that the CsPbBr 3 epitaxial thin film has a slow charge carrier recombination rate, low surface recombination velocity (10 4 cm s -1 ), and low defect density of 10 12 cm -3 , which are comparable to those of CsPbBr 3 single crystals. This work suggests a general approach using oxide perovskites as substrates for heteroepitaxial growth of halide perovskites. The high-quality halide perovskite SCTFs epitaxially integrated with multifunctional oxide perovskites could open up opportunities for a variety of high-performance optoelectronics devices.

  12. Azide groups in higher oxidation state manganese cluster chemistry: from structural aesthetics to single-molecule magnets.

    Science.gov (United States)

    Stamatatos, Theocharis C; Christou, George

    2009-04-20

    This Forum Article overviews the recent amalgamation of two long-established areas, manganese/oxo coordination cluster chemistry involving the higher Mn(II)/Mn(IV) oxidation states and transition-metal azide (N(3)(-)) chemistry. The combination of azide and alkoxide- or carboxylate-containing ligands in Mn chemistry has led to a variety of new polynuclear clusters, high-spin molecules, and single-molecule magnets, with metal nuclearities ranging from Mn(4) to Mn(32) and with ground-state spin values as large as S = 83/2. The organic bridging/chelating ligands are discussed separately as follows: (i) pyridyl alkoxides [the anions of 2-(hydroxymethyl)pyridine (hmpH), 2,6-pyridinedimethanol (pdmH(2)), and the gem-diol form of di-2-pyridyl ketone (dpkdH(2))]; (ii) non-pyridyl alkoxides [the anions of 1,1,1-tris(hydroxymethyl)ethane (thmeH(3)), triethanolamine (teaH(3)), and N-methyldiethanolamine (mdaH(2))]; (iii) other alcohols [the anions of 2,6-dihydroxymethyl-4-methylphenol (LH(3)) and Schiff bases]; (iv) pyridyl monoximes/dioximes [the anions of methyl-2-pyridyl ketone oxime (mpkoH), phenyl-2-pyridyl ketone oxime (ppkoH), and 2,6-diacetylpyridine dioxime (dapdoH(2))]; (v) non-pyridyl oximes [the anions of salicylaldoxime (saoH(2)) and its derivatives R-saoH(2)]. The large structural diversity of the resulting complexes stems from the combined ability of the azide and organic ligands to adopt a variety of ligation and bridging modes. The combined work demonstrates the synthetic novelty that arises when azide is used in conjunction with alcohol-based chelates, the aesthetic beauty of the resulting molecules, and the often fascinating magnetic properties that these compounds possess. This continues to emphasize the extensive and remarkable ability of Mn chemistry to satisfy a variety of different tastes.

  13. A green approach for single-pot synthesis of graphene oxide and its composite with Mn3O4

    Science.gov (United States)

    Rathour, Rishi Karan Singh; Bhattacharya, Jayanta

    2018-04-01

    Development of simple, environment friendly and effective approaches for the synthesis of graphene oxide (GO) is highly demanded because of its widespread applications. The present study focuses on synthesis of GO coupled with simultaneous conversion of waste byproduct as novel products, which was further used to synthesize Mn3O4 nanoparticle (Mn3O4NP), composite of GO with Mn3O4NP (rGO-Mn3O4NC) and high purity K2SO4 crystal. The characterization of GO, Mn3O4NP, and rGOMn3O4NC demonstrates the formation of single layer ∼2 μm lateral GO, ∼15 nm sized Mn3O4NP, and thermally stable rGO-Mn3O4NC. The experimental yields of GO, Mn3O4NP, and K2SO4 were 1.72, 2.04, and 87.0 g from 1.0, 4.0g, and 25.0mL of graphite, KMnO4, and H2SO4. The specific surface area of GO, Mn3O4NP, and rGO-Mn3O4NC were found to be 152.5, 233, and 27.6 m2/g, respectively. The adsorptive removal of lead (Pb2+) and methylene blue (MB) from aqueous solution by GO, Mn3O4NP, and rGO-Mn3O4NC shows an adsorption capacity of 42.3, 219, and 105 mg/g, for Pb2+ and 366, 7.5, and 17.5 mg/g, for MB, respectively. The cost analysis reveals that the proposed synthesis route is comparatively quite competitive.

  14. Enhancement of carrier mobility in pentacene thin-film transistor on SiO{sub 2} by controlling the initial film growth modes

    Energy Technology Data Exchange (ETDEWEB)

    Qi Qiong; Yu Aifang; Jiang Peng [National Center for Nanoscience and Technology, No.11, Beiyitiao Zhongguancun, Beijing 100190 (China); Jiang Chao, E-mail: jiangch@nanoctr.cn [National Center for Nanoscience and Technology, No.11, Beiyitiao Zhongguancun, Beijing 100190 (China)

    2009-02-15

    Pentacene thin-film transistors (TFTs) were fabricated on thermally grown SiO{sub 2} gate insulator under the conditions of various pre-cleaning treatments. Initial nucleation and growth of the material films on treated substrates were observed by atomic force microscope. The performance of fabricated TFT devices with different surface cleaning approaches was found to be highly related to the initial film morphologies. In contrast to the three-dimensional island-like growth mode on SiO{sub 2} under an organic cleaning process, a layer-by-layer initial growth occurred on the SiO{sub 2} insulator cleaned with ammonia solution, which was believed to be the origination of the excellent electrical properties of the TFT device. Field effect mobility of the TFT device could achieve as high as 1.0 cm{sup 2}/Vs on the bared SiO{sub 2}/Si substrate and the on/off ratio was over 10{sup 6}.

  15. Surface anisotropy change of CoFe{sub 2}O{sub 4} nanoparticles depending on thickness of coated SiO{sub 2} shell

    Energy Technology Data Exchange (ETDEWEB)

    Coskun, Mustafa [Hacettepe University, Department of Physics Engineering (Turkey); Can, Musa Mutlu, E-mail: musamutlucan@gmail.com [Nanotechnology Research and Application Center, Sabanc Latin-Small-Letter-Dotless-I University, Faculty of Engineering and Natural Sciences (Turkey); Coskun, Oezlem Duyar; Korkmaz, Mustafa; F Latin-Small-Letter-Dotless-I rat, Tezer [Hacettepe University, Department of Physics Engineering (Turkey)

    2012-10-15

    We systematically investigated the effective surface anisotropy of CoFe{sub 2}O{sub 4} nanoparticles dependant on the thickness of SiO{sub 2} shell. XRD (X-ray powder diffraction) patterns and TEM (transmission electron microscopy) micrographs were used to investigate the structure of particles and thickness of SiO{sub 2} shell, respectively. The thicknesses of SiO{sub 2} shell with 5.41 nm on CoFe{sub 2}O{sub 4} nanoparticles were increased up to 14.04 {+-} 0.05 nm by changing the amount of added TEOS by, 0.10, 0.25, 0.50, 1.00, 1.50, and 2.50 mL. The increase of the SiO{sub 2} thickness shell decreased the effective anisotropy due to decline the effectiveness of the dipolar magnetostatic interactions, determined from Vogel-Fulcher equation, between the particles. The declines in the Keff values stabled at around 3.76 {+-} 0.11 Multiplication-Sign 10{sup 5} J/m{sup 3} for TEOS amount higher than 1.5 mL.

  16. Pharmacokinetics of Roflumilast and Its Active Metabolite Roflumilast N-Oxide in Healthy Chinese Subjects After Single and Multiple Oral Doses.

    Science.gov (United States)

    Li, Qian; Wang, Yiya; Liu, Lingye; Ma, Pengcheng; Ding, Li

    2017-06-01

    Roflumilast is a selective, oral phosphodiesterase 4 inhibitor approved for the treatment of severe chronic obstructive pulmonary disease. The aim of this study was to evaluate the pharmacokinetics of roflumilast and roflumilast N-oxide in healthy Chinese subjects, and the effects of gender and food on their respective pharmacokinetic profiles. 36 healthy Chinese subjects were recruited in a randomized, single-center, open-label, parallel group study and assigned to 0.25-, 0.375-, and 0.5-mg dose groups. The single-dose pharmacokinetic studies in fasting condition were carried out in all groups. Moreover, the food effect study and multiple-dose study were conducted in 0.375-mg dose group. Serial blood samples were collected over 168 h after dosing, and plasma concentrations of roflumilast and roflumilast N-oxide were determined using a validated LC-MS/MS method. After oral administration of single doses of 0.25, 0.375 and 0.5 mg of roflumilast under fasting condition, the mean AUC 0-72h for roflumilast was 21.7 ± 8.3, 29.8 ± 8.3 and 54.2 ± 21.3 ng·h/mL, respectively. Meanwhile the mean AUC 0-168h for roflumilast N-oxide was 290 ± 103, 385 ± 107 and 673 ± 245 ng·h/mL, respectively. In the steady state after the multi-dose administration, the exposure to roflumilast in the subjects increased 20-40 %, and the exposure to roflumilast N-oxide increased about 169 %, compared to the single-dose administration. No statistically significant effect of gender on the disposition of roflumilast and roflumilast N-oxide was observed. Food had no effect on systemic exposure to roflumilast and roflumilast N-oxide in the subjects, but delayed the T max of roflumilast by 0.9 h and reduced the C max of roflumilast by approximately 20 %. Based upon between-study comparison, peak and systemic exposure of roflumilast and roflumilast N-oxide were higher in Chinese than that in Caucasian subjects after oral administration of the same dose (i.e., 0.25 and 0.5

  17. Pt atoms stabilized on hexagonal boron nitride as efficient single-atom catalysts for CO oxidation: A first-principles investigation

    KAUST Repository

    Liu, Xin

    2015-01-01

    Taking CO oxidation as a probe, we investigated the electronic structure and reactivity of Pt atoms stabilized by vacancy defects on hexagonal boron nitride (h-BN) by first-principles-based calculations. As a joint effect of the high reactivity of both a single Pt atom and a boron vacancy defect (PtBV), the Pt-N interaction is -4.40 eV and is already strong enough to prohibit the diffusion and aggregation of the stabilized Pt atom. Facilitated by the upshifted Pt-d states originated from the Pt-N interaction, the barriers for CO oxidation through the Langmuir-Hinshelwood mechanism for formation and dissociation of peroxide-like intermediate and the regeneration are as low as 0.38, 0.10 and 0.04 eV, respectively, suggesting the superiority of PtBV as a catalyst for low temperature CO oxidation.

  18. Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H@PPy@Au spheres: Fabrication, characterization and application in SERS

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Guohong; Shang, Mengying; Zou, Hanzhi; Wang, Wenqin, E-mail: wangwenqin@nbu.edu.cn

    2016-04-15

    In this work, the sulfonic acid (–SO{sub 3}H) group terminated Fe{sub 3}O{sub 4}@SiO{sub 2} magnetic spheres were prepared. Polypyrrole (PPy) was in-situ polymerized on Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H spheres due to the dual roles of the –SO{sub 3}H groups: acting as both “anchoring sites” for adsorbing of pyrrole monomer and dopant agent in PPy. By adsorbing gold nanoseeds on the as-prepared Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H@PPy spheres followed the seed-mediated growth method, the multifunctional Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H@PPy@Au spheres were obtained. The application of Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H@PPy@Au spheres in surface-enhanced Raman scattering (SERS) was investigated, and the results exhibited the enhancement in the order of 10{sup 4} using 4-aminothiophenol as the probe molecule. - Highlights: • The sulfonic acid-terminated Fe{sub 3}O{sub 4}@SiO{sub 2} (Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H) spheres were prepared. • The –SO{sub 3}H groups of Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H spheres played dual roles in adsorbing pyrrole and protonating polypyrrole. • Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H@PPy core/gold shell composites can act as SERS substrate for detecting 4-ATP molecule.

  19. A single source precursor route to group 13 homo- and heterometallic oxides as highly active supports for gold-catalyzed aerobic epoxidation of trans-stilbene

    KAUST Repository

    Mishra, Shashank K.

    2012-12-14

    A new Mitsubishi-type of star-shaped homoleptic derivative of indium(III), In4(mdea)6 (2, mdeaH2 = N-methyldiethanolamine) , was synthesized by the chloro-aminoalkoxo exchange reaction of a heteroleptic complex In6Cl6(mdea)6 (1) and used as a facile single source molecular precursor for the sol-gel preparation of high surface area indium oxide. Successful deposition of gold nanoparticles (1 wt.-%) of average size 3.3 nm on the above metal oxide by using HAuCl4· 3H2O afforded a highly efficient Au/In2O3 catalyst for the aerobic epoxidation of trans-stilbene at low temperature. The above single source precursor approach was further extended to obtain other group 13 homo- and heterometallic oxides, namely, α-Ga2O 3, β-Ga2O3 and Al4Ga 2O9, as highly active supports for gold catalysts. The obtained Au/M2O3 (M = Ga, In) and Au/Al4Ga 2O9 catalysts were thoroughly characterized by using several physicochemical techniques such as XRD, high resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray (EDX) spectroscopy, and X-ray photoelectron spectroscopy (XPS). A comparative study of the above catalysts for the model aerobic oxidation of stilbene in methylcyclohexane was undertaken. Highly efficient catalysts for aerobic oxidation reactions were obtained by depositing gold nanoparticles on group 13 mono- or mixed metal oxides prepared from the hydrolysis of well-characterized homo- and heterometallic N-methyldiethanolaminate derivatives. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Investigation of a Spinel-forming Cu-Mn Foam as an Oxygen Electrode Contact Material in a Solid Oxide Cell Single Repeating Unit

    DEFF Research Database (Denmark)

    Zielke, Philipp; Wulff, Anders Christian; Sun, Xiufu

    2017-01-01

    and steels. The consequence is a low layer and interface strength. A metallic copper manganese foam, which is oxidized under operation conditions into a conductive Cu1+xMn2–xO4 spinel, is presented in this work as a viable contact solution. The foam has been electrochemically tested in a single repeating...... and moderate degradation rates, the CuMn foam presented itself as an interesting cathode contact solution....

  1. Single-stage oxidative dehydrogenation of n-butaneand isopentane in adiabatic sectional reactors with supply of oxygene and water steam

    International Nuclear Information System (INIS)

    Azizov, A.G; Gadji-Kasumov, V.S

    2000-01-01

    Full text: The advanced technique of single-stage dehydrogenation of n-butane and iso-pentane in adiabatic sectional with separate supply of oxygen on every section is offered. The substance of the novel method consist in water metering for every section. Such technological technique considerably cut the specific energy expenses on high temperature water steam production, increase the yield and selectivity of main products formation at the expense of more complete partial oxidation of the correspondend olefins.

  2. A Theoretical Investigation on CO Oxidation by Single-Atom Catalysts M1/γ-Al2O3(M=Pd, Fe, Co, and Ni).

    Science.gov (United States)

    Yang, Tao; Fukuda, Ryoichi; Hosokawa, Saburo; Tanaka, Tsunehiro; Sakaki, Shigeyoshi; Ehara, Masahiro

    2017-04-07

    Single-atom catalysts have attracted much interest recently because of their excellent stability, high catalytic activity, and remarkable atom efficiency. Inspired by the recent experimental discovery of a highly efficient single-atom catalyst Pd 1 /γ-Al 2 O 3 , we conducted a comprehensive DFT study on geometries, stabilities and CO oxidation catalytic activities of M 1 /γ-Al 2 O 3 (M=Pd, Fe, Co, and Ni) by using slab-model. One of the most important results here is that Ni 1 /Al 2 O 3 catalyst exhibits higher activity in CO oxidation than Pd 1 /Al 2 O 3 . The CO oxidation occurs through the Mars van Krevelen mechanism, the rate-determining step of which is the generation of CO 2 from CO through abstraction of surface oxygen. The projected density of states (PDOS) of 2 p orbitals of the surface O, the structure of CO-adsorbed surface, charge polarization of CO and charge transfer from CO to surface are important factors for these catalysts. Although the binding energies of Fe and Co with Al 2 O 3 are very large, those of Pd and Ni are small, indicating that the neighboring O atom is not strongly bound to Pd and Ni, which leads to an enhancement of the reactivity of the O atom toward CO. The metal oxidation state is suggested to be one of the crucial factors for the observed catalytic activity.

  3. MEIS, TEM and GISAXS investigation of buried Pb nanoislands in SiO{sub 2}/Si interface

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, D.F., E-mail: dario.f.sanchez@gmail.com [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre (Brazil); Rodrigues, F.; Luce, F.P.; Fabrim, Z.E. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre (Brazil); Azevedo, G. de M [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre (Brazil); Departamento de Física, Universidade Federal do Paraná, Curitiba (Brazil); Department of Metallurgy, Engineering School, UFRGS, Porto Alegre (Brazil); Kellermann, G. [Departamento de Física, Universidade Federal do Paraná, Curitiba (Brazil); Baptista, D.L.; Grande, P.L. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre (Brazil); Fichtner, P.F.P. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre (Brazil); Department of Metallurgy, Engineering School, UFRGS, Porto Alegre (Brazil)

    2014-12-01

    Highlights: • Microstructural, morphological and compositional investigation of buried nanoparticles. • Importance of the combined MEIS, GISAXS and TEM analysis is demonstrated. • The bimodal nanoparticles’ shape nature of this system has been revealed. • The potentiality of MEIS on the study of buried nanostructures in a solid matrix is shown. - Abstract: A combination of medium energy ion scattering (MEIS), grazing incidence small angle X-ray scattering and transmission electron microscopy techniques was used to investigate a planar set of Pb nanoparticles (NPs) located at the SiO{sub 2}/Si interface synthesized by ion implantation, and the bimodal NPs’ shape nature of this system was revealed. The present results help to improve the understanding of the use of MEIS on the investigation of the microstructural and morphological properties of buried nanostructured systems and show the importance of the combination with appropriate complementary techniques.

  4. An In Vivo Evaluation of the Fit of Zirconium-Oxide Based, Ceramic Single Crowns with Vertical and Horizontal Finish Line Preparations.

    Science.gov (United States)

    Vigolo, Paolo; Mutinelli, Sabrina; Biscaro, Leonello; Stellini, Edoardo

    2015-12-01

    Different types of tooth preparations influence the marginal precision of zirconium-oxide based ceramic single crowns. In this in vivo study, the marginal fits of zirconium-oxide based ceramic single crowns with vertical and horizontal finish lines were compared. Forty-six teeth were chosen in eight patients indicated for extraction for implant placement. CAD/CAM technology was used for the production of 46 zirconium-oxide-based ceramic single crowns: 23 teeth were prepared with vertical finishing lines, 23 with horizontal finishing lines. One operator accomplished all clinical procedures. The zirconia crowns were cemented with glass ionomer cement. The teeth were extracted 1 month later. Marginal gaps along vertical planes were measured for each crown, using a total of four landmarks for each tooth by means of a microscope at 50× magnification. On conclusion of microscopic assessment, ESEM evaluation was completed on all specimens. The comparison of the gap between the two types of preparation was performed with a nonparametric test (two-sample Wilcoxon rank-sum test) with a level of significance fixed at p crowns with vertical and horizontal finish line preparations were not different. © 2015 by the American College of Prosthodontists.

  5. A novel pre-sintering technique for the growth of Y-Ba-Cu-O superconducting single grains from raw metal oxides

    Science.gov (United States)

    Li, Jiawei; Shi, Yun-Hua; Dennis, Anthony R.; Namburi, Devendra Kumar; Durrell, John H.; Yang, Wanmin; Cardwell, David A.

    2017-09-01

    Most established top seeded melt growth (TSMG) processes of bulk, single grain Y-Ba-Cu-O (YBCO) superconductors are performed using a mixture of pre-reacted precursor powders. Here we report the successful growth of large, single grain YBCO samples by TSMG with good superconducting properties from a simple precursor composition consisting of a sintered mixture of the raw oxides. The elimination of the requirement to synthesize precursor powders in a separate process prior to melt processing has the potential to reduce significantly the cost of bulk superconductors, which is essential for their commercial exploitation. The growth morphology, microstructure, trapped magnetic field and critical current density, J c, at different positions within the sample and maximum levitation force of the YBCO single grains fabricated by this process are reported. Measurements of the superconducting properties show that the trapped filed can reach 0.45 T and that a zero field J c of 2.5 × 104 A cm-2 can be achieved in these samples. These values are comparable to those observed in samples fabricated using pre-reacted, high purity commercial oxide precursor powders. The experimental results are discussed and the possibility of further improving the melt process using raw oxides is outlined.

  6. X-Ray Spectroscopy of Ultra-Thin Oxide/Oxide Heteroepitaxial Films: A Case Study of Single-Nanometer VO2/TiO2

    Directory of Open Access Journals (Sweden)

    Nicholas F. Quackenbush

    2015-08-01

    Full Text Available Epitaxial ultra-thin oxide films can support large percent level strains well beyond their bulk counterparts, thereby enabling strain-engineering in oxides that can tailor various phenomena. At these reduced dimensions (typically < 10 nm, contributions from the substrate can dwarf the signal from the epilayer, making it difficult to distinguish the properties of the epilayer from the bulk. This is especially true for oxide on oxide systems. Here, we have employed a combination of hard X-ray photoelectron spectroscopy (HAXPES and angular soft X-ray absorption spectroscopy (XAS to study epitaxial VO2/TiO2 (100 films ranging from 7.5 to 1 nm. We observe a low-temperature (300 K insulating phase with evidence of vanadium-vanadium (V-V dimers and a high-temperature (400 K metallic phase absent of V-V dimers irrespective of film thickness. Our results confirm that the metal insulator transition can exist at atomic dimensions and that biaxial strain can still be used to control the temperature of its transition when the interfaces are atomically sharp. More generally, our case study highlights the benefits of using non-destructive XAS and HAXPES to extract out information regarding the interfacial quality of the epilayers and spectroscopic signatures associated with exotic phenomena at these dimensions.

  7. SiO{sub 2} on silicon: behavior under heavy ion irradiation; SiO{sub 2} sur silicium: comportement sous irradiation avec des ions lourds

    Energy Technology Data Exchange (ETDEWEB)

    Rotaru, C

    2004-03-15

    Heavy ion irradiation was performed on a-SiO{sub 2} layers deposited on Si. Damage of the surface was studied by means of Atomic Force Microscopy. Hillocks appear for an electronic stopping power higher than 16 keV/nm. The height of the hillocks decreases with the thickness of the oxide layer. Infrared Spectroscopy studies show that the damage threshold for a-SiO{sub 2} is at an electronic stopping power of 2 keV/nm. Therefore it is probable that the origin of the hillocks comes from the silicon layer. This could be explain within the frame of thermal spike model. The theoretical thresholds are 8 keV/nm and 1.8 keV/nm for silicon and a-SiO{sub 2} respectively. Chemical etching after irradiation gives a technical possibility to create nano-pits, whose size and shape can be controlled. Additionally, these structures allowed to determine the AFM tip radius. (author)

  8. Tungsten-doped vanadium oxides prepared by direct liquid injection MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Vernardou, D.; Pemble, M.E.; Sheel, D.W. [Institute for Materials Research, University of Salford, Cockroft Building, Salford, Manchester (United Kingdom)

    2007-04-15

    This paper examines the effect of doping on vanadium(IV) oxide (VO{sub 2} (M)) coatings on glass, using atmospheric-pressure, direct liquid injection metal-organic (DLI-MO)CVD, which potentially may find application as part of smart glazing units. It is found that tungsten-doped VO{sub 2} (M) deposited on commercial SiO{sub 2}-precoated glass using a 0.1 M solution of vanadyl(IV) acetylacetonate (VO(acac){sub 2}) and tungsten (VI) ethoxide (W(OC{sub 2}H{sub 5}){sub 5}) in methanol shows a reduction in thermochromic transition temperature (T{sub c}) from 60 C in VO{sub 2} (M) to 35 C in V{sub 0.98}W{sub 0.02}O{sub 2}. This finding is discussed in terms of various atomic percentages of tungsten and oxygen flow rates. The crystallinity, composition, morphology, optical properties, uniformity, and oxidation phase of the films are evaluated by X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), scanning electron microscopy (SEM), IR reflectance-transmittance, and Raman spectroscopy, respectively. The relationship between dopant concentration and T{sub c} in the most applicable range for solar window coatings is refined by formation of a single-phase film and precise determination of these parameters. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  9. Structural and Electronic Properties of Transition-Metal Oxides Attached to a Single-Walled CNT as a Lithium-Ion Battery Electrode: A First-Principles Study.

    Science.gov (United States)

    Tack, Liew Weng; Azam, Mohd Asyadi; Seman, Raja Noor Amalina Raja

    2017-04-06

    Single-walled carbon nanotubes (SWCNTs) and metal oxides (MOs), such as manganese(IV) oxide (MnO 2 ), cobalt(II, III) oxide (Co 3 O 4 ), and nickel(II) oxide (NiO) hybrid structures, have received great attention because of their promising application in lithium-ion batteries (LIBs). As electrode materials for LIBs, the structure of SWCNT/MOs provides high power density, good electrical conductivity, and excellent cyclic stability. In this work, first-principles calculations were used to investigate the structural and electronic properties of MOs attached to (5, 5) SWCNT and Li-ion adsorption to SWCNT/metal oxide composites as electrode materials in LIBs. Emphasis was placed on the synergistic effects of the composite on the electrochemical performance of LIBs in terms of adsorption capabilities and charge transfer of Li-ions attached to (5, 5) SWCNT and metal oxides. Also, Li adsorption energy on SWCNTs and three different metal oxides (NiO, MnO 2 , and Co 3 O 4 ) and the accompanying changes in the electronic properties, such as band structure, density of states and charge distribution as a function of Li adsorption were calculated. On the basis of the calculation results, the top C atom was found to be the most stable position for the NiO and MnO 2 attachment to SWCNT, while the Co 3 O 4 molecule, the Co 2+ , was found to be the most stable attachment on SWCNT. The obtained results show that the addition of MOs to the SWCNT electrode enables an increase in specific surface area and improves the electronic conductivity and charge transfer of an LIB.

  10. Lability and Basicity of Bipyridine-Carboxylate-Phosphonate Ligand Accelerate Single-Site Water Oxidation by Ruthenium-Based Molecular Catalysts.

    Science.gov (United States)

    Shaffer, David W; Xie, Yan; Szalda, David J; Concepcion, Javier J

    2017-11-01

    A critical step in creating an artificial photosynthesis system for energy storage is designing catalysts that can thrive in an assembled device. Single-site catalysts have an advantage over bimolecular catalysts because they remain effective when immobilized. Hybrid water oxidation catalysts described here, combining the features of single-site bis-phosphonate catalysts and fast bimolecular bis-carboxylate catalysts, have reached turnover frequencies over 100 s -1 , faster than both related catalysts under identical conditions. The new [(bpHc)Ru(L) 2 ] (bpH 2 cH = 2,2'-bipyridine-6-phosphonic acid-6'-carboxylic acid, L = 4-picoline or isoquinoline) catalysts proceed through a single-site water nucleophilic attack pathway. The pendant phosphonate base mediates O-O bond formation via intramolecular atom-proton transfer with a calculated barrier of only 9.1 kcal/mol. Additionally, the labile carboxylate group allows water to bind early in the catalytic cycle, allowing intramolecular proton-coupled electron transfer to lower the potentials for oxidation steps and catalysis. That a single-site catalyst can be this fast lends credence to the possibility that the oxygen evolving complex adopts a similar mechanism.

  11. Lability and Basicity of Bipyridine-Carboxylate-Phosphonate Ligand Accelerate Single-Site Water Oxidation by Ruthenium-Based Molecular Catalysts

    International Nuclear Information System (INIS)

    Shaffer, David W.; Xie, Yan; Szalda, David J.; Concepcion, Javier J.

    2017-01-01

    Here, a critical step in creating an artificial photosynthesis system for energy storage is designing catalysts that can thrive in an assembled device. Single-site catalysts have an advantage over bimolecular catalysts because they remain effective when immobilized. Hybrid water oxidation catalysts described here, combining the features of single-site bis-phosphonate catalysts and fast bimolecular bis-carboxylate catalysts, have reached turnover frequencies over 100 s –1 , faster than both related catalysts under identical conditions. The new [(bpHc)Ru(L) 2 ] (bpH 2 cH = 2,2'-bipyridine-6-phosphonic acid-6'-carboxylic acid, L = 4-picoline or isoquinoline) catalysts proceed through a single-site water nucleophilic attack pathway. The pendant phosphonate base mediates O–O bond formation via intramolecular atom-proton transfer with a calculated barrier of only 9.1 kcal/mol. Additionally, the labile carboxylate group allows water to bind early in the catalytic cycle, allowing intramolecular proton-coupled electron transfer to lower the potentials for oxidation steps and catalysis. That a single-site catalyst can be this fast lends credence to the possibility that the oxygen evolving complex adopts a similar mechanism.

  12. Oxide and proton conductivity in aluminum-doped tricalcium oxy-silicate

    Energy Technology Data Exchange (ETDEWEB)

    Porras-Vazquez, J.M.; De la Torre, A.G.; Losilla, E.R.; Aranda, M.A.G. [Dept. Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, Campus Teatinos, 29071-Malaga (Spain)

    2007-06-15

    Aluminum doping in tricalcium silicate, Ca{sub 3}(SiO{sub 4})O, has been studied by high-resolution laboratory X-ray powder diffraction and the Rietveld method. Two nominal series have been designed and studied. Oxygen-fixed Ca{sub 3-x/2}Al{sub x/2}(Si{sub 1-x/2}Al{sub x/2}O{sub 4})O series has been prepared as single-phase up to x = 0.03. However, oxygen-variable Ca{sub 3}(Si{sub 1-x}Al{sub x}O{sub 4})O{sub 1-x/2}{open_square}{sub x/2} series has not been stabilized for any composition. The samples show oxide anion conductivity with a small p-type electronic contribution under oxidizing conditions. Typical total conductivities for these solids are 10{sup -} {sup 5}-10{sup -} {sup 4}S cm{sup -} {sup 1} at 1100 K. The oxide ion transference numbers are very high, {proportional_to} 0.98, under reducing conditions, i.e. dry 5%H{sub 2}-N{sub 2}/air gradient. The oxide ion transference numbers are slightly lower, {proportional_to} 0.91 under oxidizing conditions, i.e. dry O{sub 2}/air gradient. These compounds display a very important proton contribution to the overall conductivities under humidified atmospheres. The proton transference number ranges between 0.72 and 0.55 at 873 and 1023 K, respectively. (author)

  13. Influences of MCrAlY coatings on oxidation resistance of single crystal superalloy DD98M and their inter-diffusion behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Long [School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China); Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Xin, Li, E-mail: xli@imr.ac.cn [Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, Xinyue; Wang, Xiaolan; Wei, Hua; Zhu, Shenglong; Wang, Fuhui [Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2015-11-15

    Oxidation and interdiffusion behaviors of Ni-based single crystal superalloy DD98M with nominal compositions Ni–5.0Co–6.0Cr–6.3Al–6.0W–2.0Mo–6.0Ta–1.0Ti (in wt.%) and two types of MCrAlY coatings at 1000 °C and 1050 °C were investigated. Complex oxides formed on the surface of DD98M alloy when oxidized at 1000 °C and 1050 °C, which stratified, cracked and spalled. The faceted-like AlN and the particle-like and strip-like TiN formed in the alloy. The application of the NiCrAlY and NiCoCrAlYHfSi coatings greatly improved the oxidation resistance of DD98M alloy. After 500 h oxidation, α-Al{sub 2}O{sub 3} was still the dominate phase in the oxide scales formed on the coated specimens. The adhesion of the oxide scale on the NiCoCrAlYHfSi coating was much better than that on the NiCrAlY coating. Interdiffusion occurred between the coatings and the substrate, which led to the formation of the IDZ and SRZ. The IDZ of the NiCrAlY coated specimen was composed of γ phase and Al- and Ta-rich γ′ phase. The γ′ phase in the IDZ accommodated most of the inward diffusing aluminum, so the SRZ formation was suppressed when oxidized at 1050 °C. However the formation of SRZ with μ-TCP still occurred when oxidized at 1000 °C probably due to the low solubility and slow diffusion rate of the alloying elements at lower temperature. The IDZ of the NiCoCrAlYHfSi coated specimen was a single γ phase. A large amount of μ-TCP precipitated in the SRZ of the NiCoCrAlYHfSi coated specimen when oxidized at 1000 °C and 1050 °C. It can be concluded coating composition has a significant effect on the development of the IDZ and SRZ. Thermal exposure temperature also has influences on the formation of the SRZ. The mechanism of SRZ formation and TCP precipitation are discussed. - Graphical abstract: The TEM micrograph of the IDZ and SRZ of the NiCoCrAlYHfSi-coated specimen oxidized at 1050 °C for 100 h and the respective diffraction patterns of the needle-like and the

  14. Effects of Single and Combined Losartan and Tempol Treatments on Oxidative Stress, Kidney Structure and Function in Spontaneously Hypertensive Rats with Early Course of Proteinuric Nephropathy.

    Directory of Open Access Journals (Sweden)

    Danijela Karanovic

    Full Text Available Oxidative stress has been widely implicated in both hypertension and chronic kidney disease (CKD. Hypertension is a major risk factor for CKD progression. In the present study we have investigated the effects of chronic single tempol (membrane-permeable radical scavenger or losartan (angiotensin II type 1 receptor blocker treatment, and their combination on systemic oxidative status (plasma thiobarbituric acid-reactive substances (pTBARS production, plasma antioxidant capacity (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid, pABTS, erythrocyte antioxidant enzymes activities and kidney oxidative stress (kTBARS, kABTS, kidney antioxidant enzymes activities, kidney function and structure in spontaneously hypertensive rats (SHR with the early course of adriamycin-induced nephropathy. Adult SHR were divided into five groups. The control group received vehicle, while the other groups received adriamycin (2 mg/kg, i.v. twice in a 21-day interval, followed by vehicle, losartan (L,10 mg/kg/day, tempol (T,100 mg/kg/day or combined T+L treatment (by gavage during a six-week period. Adriamycin significantly increased proteinuria, plasma lipid peroxidation, kidney protein oxidation, nitrite excretion, matrix metalloproteinase-1 (MMP-1 protein expression and nestin immunostaining in the kidney. Also, it decreased kidney antioxidant defense, kidney NADPH oxidase 4 (kNox4 protein expression and abolished anti-inflammatory response due to significant reduction of kidney NADPH oxidase 2 (kNox2 protein expression in SHR. All treatments reduced protein-to-creatinine ratio (marker of proteinuria, pTBARS production, kidney protein carbonylation, nitrite excretion, increased antioxidant capacity and restored kidney nestin expression similar to control. Both single treatments significantly improved systemic and kidney antioxidant defense, bioavailability of renal nitric oxide, reduced kMMP-1 protein expression and renal injury, thus retarded CKD progression

  15. Effects of Single and Combined Losartan and Tempol Treatments on Oxidative Stress, Kidney Structure and Function in Spontaneously Hypertensive Rats with Early Course of Proteinuric Nephropathy

    Science.gov (United States)

    Grujic-Milanovic, Jelica; Miloradovic, Zoran; Ivanov, Milan; Jovovic, Djurdjica; Vajic, Una-Jovana; Zivotic, Maja; Markovic-Lipkovski, Jasmina; Mihailovic-Stanojevic, Nevena

    2016-01-01

    Oxidative stress has been widely implicated in both hypertension and chronic kidney disease (CKD). Hypertension is a major risk factor for CKD progression. In the present study we have investigated the effects of chronic single tempol (membrane-permeable radical scavenger) or losartan (angiotensin II type 1 receptor blocker) treatment, and their combination on systemic oxidative status (plasma thiobarbituric acid-reactive substances (pTBARS) production, plasma antioxidant capacity (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid, pABTS), erythrocyte antioxidant enzymes activities) and kidney oxidative stress (kTBARS, kABTS, kidney antioxidant enzymes activities), kidney function and structure in spontaneously hypertensive rats (SHR) with the early course of adriamycin-induced nephropathy. Adult SHR were divided into five groups. The control group received vehicle, while the other groups received adriamycin (2 mg/kg, i.v.) twice in a 21-day interval, followed by vehicle, losartan (L,10 mg/kg/day), tempol (T,100 mg/kg/day) or combined T+L treatment (by gavage) during a six-week period. Adriamycin significantly increased proteinuria, plasma lipid peroxidation, kidney protein oxidation, nitrite excretion, matrix metalloproteinase-1 (MMP-1) protein expression and nestin immunostaining in the kidney. Also, it decreased kidney antioxidant defense, kidney NADPH oxidase 4 (kNox4) protein expression and abolished anti-inflammatory response due to significant reduction of kidney NADPH oxidase 2 (kNox2) protein expression in SHR. All treatments reduced protein-to-creatinine ratio (marker of proteinuria), pTBARS production, kidney protein carbonylation, nitrite excretion, increased antioxidant capacity and restored kidney nestin expression similar to control. Both single treatments significantly improved systemic and kidney antioxidant defense, bioavailability of renal nitric oxide, reduced kMMP-1 protein expression and renal injury, thus retarded CKD progression

  16. CO oxidation mechanism on the γ-Al{sub 2}O{sub 3} supported single Pt atom: First principle study

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Hongwei, E-mail: gaohongw369@ms.xjb.ac.cn

    2016-08-30

    Highlights: • DFT studied on CO oxidation mechanism on Pt/γ-Al{sub 2}O{sub 3} catalyst. • DFT studied on the adsorption properties of single Pt on Pt/γ-Al{sub 2}O{sub 3} catalyst. • Pt adsorptions on the Al-terminated surface are more favorable than the ones on the O-terminated surface. • The reactive O*−O−C*=O intermediate mechanism is the dominant reaction pathway for CO oxidation on Pt/γ-Al{sub 2}O{sub 3}. - Abstract: Understanding the role of metal-support interaction for the supported single-atom catalysts is very important in heterogeneous catalysis. Here, Three different CO oxidation mechanisms on Pt/γ-Al{sub 2}O{sub 3} catalyst were probed by periodic density functional theory (DFT) calculations in detail, namely the reactive O*−O−C*=O intermediate mechanism, the reactive CO{sub 3} intermediate mechanism and the Pt-Al{sup 3+} double sites mechanism. According to the calculated results analysis, we concluded that the dominant reaction pathway at the low temperatures is the reactive O*−O−C*=O intermediate mechanism. Our results are in very good agreement with the experimental evidence for O*−O−C*=O coverage on Pt/γ-Al{sub 2}O{sub 3} at room temperature by an in situ diffuse reflectance infrared detector.

  17. The effect of defects on the catalytic activity of single Au atom supported carbon nanotubes and reaction mechanism for CO oxidation.

    Science.gov (United States)

    Ali, Sajjad; Fu Liu, Tian; Lian, Zan; Li, Bo; Sheng Su, Dang

    2017-08-23

    The mechanism of CO oxidation by O 2 on a single Au atom supported on pristine, mono atom vacancy (m), di atom vacancy (di) and the Stone Wales defect (SW) on single walled carbon nanotube (SWCNT) surface is systematically investigated theoretically using density functional theory. We determine that single Au atoms can be trapped effectively by the defects on SWCNTs. The defects on SWCNTs can enhance both the binding strength and catalytic activity of the supported single Au atom. Fundamental aspects such as adsorption energy and charge transfer are elucidated to analyze the adsorption properties of CO and O 2 and co-adsorption of CO and O 2 molecules. It is found that CO binds stronger than O 2 on Au supported SWCNT. We clearly demonstrate that the defected SWCNT surface promotes electron transfer from the supported single Au atom to O 2 molecules. On the other hand, this effect is weaker for pristine SWCNTs. It is observed that the high density of spin-polarized states are localized in the region of the Fermi level due to the strong interactions between Au (5d orbital) and the adjacent carbon (2p orbital) atoms, which influence the catalytic performance. In addition, we elucidate both the Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms of CO oxidation by O 2 . For the LH pathway, the barriers of the rate-limiting step are calculated to be 0.02 eV and 0.05 eV for Au/m-SWCNT and Au/di-SWCNT, respectively. To regenerate the active sites, an ER-like reaction occurs to form a second CO 2 molecule. The ER pathway is observed on Au/m-SWCNT, Au/SW-SWCNT and Au/SWCNT in which the Au/m-SWCNT has a smaller barrier. The comparison with a previous study (Lu et al., J. Phys. Chem. C, 2009, 113, 20156-20160.) indicates that the curvature effect of SWCNTs is important for the catalytic property of the supported single Au. Overall, Au/m-SWCNT is identified as the most active catalyst for CO oxidation compared to pristine SWCNT, SW-SWCNT and di-SWCNT. Our findings give a

  18. Studies on plant cell toxicity of luminescent silica nanoparticles (Cs{sub 2}[Mo{sub 6}Br{sub 14}]@SiO{sub 2}) and its constitutive components

    Energy Technology Data Exchange (ETDEWEB)

    Cabello-Hurtado, Francisco, E-mail: francisco.cabello@univ-rennes1.fr; Lozano-Baena, María Dolores [University of Rennes 1, UMR UR1-CNRS 6553 ECOBIO, Mechanisms at the Origin of Biodiversity Team (France); Neaime, Chrystelle [University of Rennes 1, Solid State Chemistry and Materials Group, UMR UR1-CNRS 6226 Institut des Sciences Chimiques de Rennes (France); Burel, Agnès [University of Rennes 1, Electronic Microscopy Department (France); Jeanne, Sylvie; Pellen-Mussi, Pascal; Cordier, Stéphane; Grasset, Fabien [University of Rennes 1, Solid State Chemistry and Materials Group, UMR UR1-CNRS 6226 Institut des Sciences Chimiques de Rennes (France)

    2016-03-15

    As part of the risk evaluation before potential applications of nanomaterials, phytotoxicity of newly designed multifunctional silica nanoparticles (CMB@SiO{sub 2}, average diameter of 47 nm) and their components, i.e., molybdenum octahedral cluster bromide units (CMB, 1 nm) and SiO{sub 2} nanoparticles (nSiO{sub 2}, 29 nm), has been studied using photosynthetic Arabidopsis thaliana cell suspension cultures. CMB clusters presented toxic effects on plant cells, inhibiting cell growth and negatively affecting cell viability and photosynthetic efficiency. Nevertheless, we showed that neither nSiO{sub 2} nor CMB@SiO{sub 2} have any significant effect on cell growth and viability or photosynthetic efficiency. At least, part of the harmful impact of CMB clusters could be ascribed to their capacity to generate an oxidative stress since lipid peroxidation greatly increased after CMB exposure, which was not the case for nSiO{sub 2} or CMB@SiO{sub 2} treatments. Exposure of cells to CMB clusters also leads to the induction of several enzymatic antioxidant activities (i.e., superoxide dismutase, guaiacol peroxidase, glutathione peroxidase, glutathione reductase, and glutathione S-transferase activities) compared to control and the other treatments. Finally, using electron microscopy, we showed that Arabidopsis cells internalize CMB clusters and both silica nanoparticles, the latter through, most likely, endocytosis-like pathway as nanoparticles were mainly found incorporated into vesicles.Graphical Abstract.

  19. Synthesis of alpha-aluminum oxide and hafnium-doped beta-nickel aluminide coatings on single crystal nickel-based superalloy by chemical vapor deposition

    Science.gov (United States)

    He, Limin

    Thermal barrier coatings (TBCs) are widely used for air-cooled turbine components in advanced aircraft engines and power generation systems. The dominant failure mode observed in TBCs is progressive fracture of the metal-oxide interface upon oxidation and thermal cycling. Two potential coating methods for improving TBC performance were studied: (1) preparing a high-quality alpha-Al 2O3 coating layer on the surface of a single crystal Ni-based superalloy (Rene N5) to extend the oxidative stability of the interface and (2) doping beta-NiAl bond coating with a small amount of Hf to improve the adhesion of thermally grown oxide (TGO) at the interface. In the first coating method, a novel chemical vapor deposition (CVD) procedure was developed using AlCl3, CO2 and H 2 as precursors. A critical part of this procedure was a short-time pre-oxidation step (1 min) with CO2 and H2 in the CVD chamber, prior to introducing the AlCl3, vapor. Without this pre-oxidation step, extensive whisker formation was observed on the alloy surface. Characterization results showed that the pre-oxidation step resulted in the formation of a continuous oxide layer (˜50 nm) on the alloy surface. The outer part of this layer (˜20 nm) appeared to contain mixed oxides whereas the inner part (˜30 nm) consisted of alpha-Al2O3 as a dominant major phase and theta-Al2O3 as a minor phase. It appeared that the preferential nucleation of beta-Al2O3 in the pre-oxidized layer was promoted by: (1) rapid heating (˜10 sec) of the alloy surface to the temperature region, where alpha-Al 2O3 was expected to nucleate instead of metastable Al 2O3 phases, (2) the low oxygen pressure environment of the pre-oxidation step which kept the rate of oxidation low, and (3) contamination of the CVD chamber with HfCl4. It appeared that the role of HfCl 4 was to enhance the preferential nucleation of alpha-Al2O 3 in the pre-oxidized layer. In our second coating method, we utilized the dynamic versatility of CVD as an avenue

  20. Single-electron effects in non-overlapped multiple-gate silicon-on-insulator metal-oxide-semiconductor field-effect transistors.

    Science.gov (United States)

    Lee, W; Su, P

    2009-02-11

    This paper systematically presents controlled single-electron effects in multiple-gate silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFETs) with various gate lengths, fin widths, gate bias and temperature. Our study indicates that using the non-overlapped gate to source/drain structure as an approach to the single-electron transistor (SET) in MOSFETs is promising. Combining the advantage of gate control and the constriction of high source/drain resistances, single-electron effects are further enhanced using the multiple-gate architecture. From the presented results, downsizing multiple-gate SOI MOSFETs is needed for future room-temperature SET applications. Besides, the tunnel barriers and access resistances may need to be further optimized. Since the Coulomb blockade oscillation can be achieved in state-of-the-art complementary metal-oxide-semiconductor (CMOS) devices, it is beneficial to build SETs in low-power CMOS circuits for ultra-high-density purposes.

  1. Size dependent structural, vibrational and magnetic properties of BiFeO{sub 3} and core-shell structured BiFeO{sub 3}@SiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Sunil, E-mail: sunilchauhanjiit@gmail.com; Kumar, Manoj, E-mail: sunilchauhanjiit@gmail.com; Chhoker, Sandeep, E-mail: sunilchauhanjiit@gmail.com; Katyal, S. C., E-mail: sunilchauhanjiit@gmail.com [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, Noida- 201307 (India)

    2014-04-24

    Bulk BiFeO{sub 3}, BiFeO{sub 3} nanoparticles and core-shell structured BiFeO{sub 3}@SiO{sub 2} nanoparticles were synthesized by solid state reaction method, sol-gel and Stöber process (SiO{sub 2} shell) respectively. Transmission electron microscopy image confirmed the core-shell structure of BiFeO{sub 3}@SiO{sub 2} nanoparticles with BiFeO3 core ∼50-90 nm and SiO{sub 2} shell ∼16 nm. X-ray diffraction and FTIR spectroscopy results showed the presence of distorted rhombohedral structure with R3c space group in all three samples. The magnetic measurement indicated the existence of room-temperature weak ferromagnetism in core-shell BiFeO{sub 3}@SiO{sub 2} nanoparticles and BiFeO3 nanoparticles, whereas bulk BiFeO{sub 3} showed antiferromagnteic nature. Electron Spin Resonance results confirmed the enhancement in magnetic properties of coreshell structured BiFeO{sub 3}@SiO{sub 2} nanoparticles in comparison with BiFeO{sub 3} nanoparticles and bulk BiFeO{sub 3}.

  2. Oxidation behaviour and mechanism of a cobalt based superalloy between 1050 and 1250 °C

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Longfei [State Key Lab of Materials Processing and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Wu, Shusen, E-mail: ssw636@hust.edu.cn [State Key Lab of Materials Processing and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Yu, Guangming [Wuhan Iron and Steel Corporation (WISCO), Wuhan 430083 (China); Chen, Yang [State Key Lab of Materials Processing and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2013-10-15

    A new Co-base superalloy 22Co–21Ni–23Fe–29Cr–2.2Nb (Co22 for short) was developed, and the influence of a trace amount of rare earth (RE) on the oxidation resistance was investigated. Isothermal oxidation behaviour of this Co-base superalloy was investigated at 1050–1250 °C in air, analyzed with scanning electronic microscopy and X-ray diffraction. The results show that oxidation mass gain of the samples with or without RE elements obeyed secondary parabolic law, and the effect of 0.03 wt.% RE on oxidation resistance is small. The oxidation rate constant of the 0.03 wt.% RE added Co22 alloy decreases by about 6.1% to 9.0% compared to that of the Co22 alloy without RE. Oxidation at 1050–1250 °C for 100 h results in the formation of MnCr{sub 2}O{sub 4}, Cr{sub 2}O{sub 3} and SiO{sub 2}. A continuous and protective MnCr{sub 2}O{sub 4} spinel layer forms as outer layer. The continuous middle oxide layer is confirmed to be Cr{sub 2}O{sub 3}, and the innermost layer consists of discontinuous SiO{sub 2}. The outer and middle layers strongly improve oxidation resistance and oxide layer adhesion because of their continuity and compactness, and the innermost SiO{sub 2} layer forms a diffusion barrier to prevent further oxidation. Formation and growth mechanisms of oxide layers were also discussed.

  3. Application of Genetically Encoded Fluorescent Nitric Oxide (NO•) Probes, the geNOps, for Real-time Imaging of NO• Signals in Single Cells.

    Science.gov (United States)

    Eroglu, Emrah; Rost, Rene; Bischof, Helmut; Blass, Sandra; Schreilechner, Anna; Gottschalk, Benjamin; Depaoli, Maria R; Klec, Christiane; Charoensin, Suphachai; Madreiter-Sokolowski, Corina T; Ramadani, Jeta; Waldeck-Weiermair, Markus; Graier, Wolfgang F; Malli, Roland

    2017-03-16

    Nitric Oxide (NO•) is a small radical, which mediates multiple important cellular functions in mammals, bacteria and plants. Despite the existence of a large number of methods for detecting NO• in vivo and in vitro, the real-time monitoring of NO• at the single-cell level is very challenging. The physiological or pathological effects of NO• are determined by the actual concentration and dwell time of this radical. Accordingly, methods that allow the single-cell detection of NO• are highly desirable. Recently, we expanded the pallet of NO• indicators by introducing single fluorescent protein-based genetically encoded nitric oxide (NO•) probes (geNOps) that directly respond to cellular NO• fluctuations and, hence, addresses this need. Here we demonstrate the usage of geNOps to assess intracellular NO• signals in response to two different chemical NO•-liberating molecules. Our results also confirm that freshly prepared 3-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-propanamine (NOC-7) has a much higher potential to evoke change in intracellular NO• levels as compared with the inorganic NO• donor sodium nitroprusside (SNP). Furthermore, dual-color live-cell imaging using the green geNOps (G-geNOp) and the chemical Ca 2+ indicator fura-2 was performed to visualize the tight regulation of Ca 2+ -dependent NO• formation in single endothelial cells. These representative experiments demonstrate that geNOps are suitable tools to investigate the real-time generation and degradation of single-cell NO• signals in diverse experimental setups.

  4. Microporous SiO{sub 2}-based solid electrolyte with improved polarization response for 0.8 V transparent thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Sun Jia; Jiang Jie; Lu Aixia; Wan Qing, E-mail: wanqing7686@hotmail.co [Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, and State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China)

    2010-07-28

    The polarization mechanism of a microporous SiO{sub 2}-based solid electrolyte is developed and three polarizations (electric double layer formation, ionic relaxation and dipole relaxation) are identified. The polarization response of the microporous SiO{sub 2}-based solid electrolyte is optimized by tuning the deposition temperature and the improved specific capacitance is 1 {mu}F cm{sup -2} at 1 kHz and remains above 0.6 {mu}F cm{sup -2} even at 10 kHz. Ultralow-voltage transparent In-Zn-O thin-film transistors (TFTs) gated by such dielectrics are fabricated at low temperatures. The field-effect mobility, current on/off ratio and subthreshold swing are estimated to be 46.2 cm{sup 2} V{sup -1} s{sup -1}, {approx}10{sup 6} and 69 mV/decade, respectively. Such TFTs hold promise for portable electronic applications.

  5. Creation of giant two-dimensional crystal of zinc oxide nanodisk by method of single-particle layer of organo-modified inorganic fine particles.

    Science.gov (United States)

    Meng, Qi; Honda, Nanami; Uchida, Saki; Hashimoto, Kazuaki; Shibata, Hirobumi; Fujimori, Atsuhiro

    2015-09-01

    In this study, the formation and structure of a single-particle layer of organo-zinc oxide are investigated using surface-pressure-area (π-A) isotherms, out-of-plane X-ray diffraction (XRD) analysis, and atomic force microscopy (AFM). Further, techniques for achieving the solubilization of inorganic fine particles in general solvents have been proposed, and a single-particle layer has been formed using such an inorganic solution as a "spreading solution" for an interfacial film. Surface modification of ZnO is performed using a long-chain carboxylic acid. Accordingly, a regular arrangement of ZnO can be easily achieved in order to overcome the relatively weak van der Walls interactions between inorganic materials. A condensed Langmuir monolayer of these particles is also formed. A multiparticle layered structure is constructed by the Langmuir-Blodgett (LB) technique. Out-of-plane XRD measurement results for a single-particle layer of organo-ZnO clearly show a sharp peak at 42 Å. This peak is attributed to the distance between ZnO layers. The AFM image of this single-particle layer of organo-ZnO shows a particle assembly with a uniform height of 60 nm. These aggregated particles form large two-dimensional crystals. In other words, a regular periodic structure along the c-axis and a condensed single-particle layer had been fabricated using Langmuir and LB techniques. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. A Single Zidovudine (AZT Administration Delays Hepatic Cell Proliferation by Altering Oxidative State in the Regenerating Rat Liver

    Directory of Open Access Journals (Sweden)

    Armando Butanda-Ochoa

    2017-01-01

    Full Text Available The 3′-azido-3′-deoxythymidine or Zidovudine (AZT was the first antiretroviral drug used in the treatment of HIV patients, which has good effectiveness but also hepatotoxic side effects that include cell cycle arrest and oxidative/nitrative mitochondrial damage. Whether such an oxidative damage may affect the proliferative-regenerative capacity of liver remains to be clearly specified at doses commonly used in the clinical practice. In this study, we described the oxidative-proliferative effect of AZT administered at a common clinical dose in rat liver submitted to 70% partial hepatectomy (PH. The results indicate that AZT significantly decreased DNA synthesis and the number of mitosis in liver subjected to PH in a synchronized way with the promotion of organelle-selective lipid peroxidation events (especially those observed in plasma membrane and cytosolic fractions and with liver enzyme release to the bloodstream. Then at the dose used in clinical practice AZT decreased liver regeneration but stimulates oxidative events involved during the proliferation process in a way that each membrane system inside the cell preserves its integrity in order to maintain the cell proliferative process. Here, the induction of large amounts of free ammonia in the systemic circulation could become a factor capable of mediating the deleterious effects of AZT on PH-induced rat liver regeneration.

  7. Effect of Single or Combined Climatic and Hygienic Stress in Four Layer Lines: 2. Endocrine and Oxidative Stress Responses

    NARCIS (Netherlands)

    Star, L.; Decuypere, E.; Parmentier, H.K.; Kemp, B.

    2008-01-01

    Effects of long-term climatic stress (heat exposure), short-term hygienic stress [lipopolysaccharide (LPS)], or combined exposure to these stressors on endocrine and oxidative stress parameters of 4 layer lines (B1, WA, WB, and WF) were investigated. The lines were earlier characterized for natural

  8. Acceptor-Substituted Ferrocenium Salts as Strong, Single-Electron Oxidants: Synthesis, Electrochemistry, Theoretical Investigations, and Initial Synthetic Application

    Czech Academy of Sciences Publication Activity Database

    Khobragade, Dushant; Mahamulkar, Shraddha G.; Pospíšil, Lubomír; Císařová, I.; Rulíšek, Lubomír; Jahn, Ullrich

    2012-01-01

    Roč. 18, č. 39 (2012), s. 12267-12277 ISSN 0947-6539 R&D Projects: GA ČR GA203/09/0705 Institutional support: RVO:61388963 Keywords : metallocenes * cyclic voltammetry * lactones * oxidation * redox chemistry Subject RIV: CC - Organic Chemistry Impact factor: 5.831, year: 2012

  9. Modulation of the thermoluminescence glow curve of sol-gel synthesized SiO{sub 2} and Si O-2:Eu through thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Salas J, Ch. J.; Cruz V, C. [Universidad de Sonora, Departamento de Investigacion en Polimeros y Materiales, Apdo. Postal 130, 83000 Hermosillo, Sonora (Mexico); Bernal, R. [Universidad de Sonora, Departamento de Investigacion en Fisica, Apdo. Postal 5-088, 83190 Hermosillo, Sonora (Mexico); Castano, V. M., E-mail: salasjuarez@gimmunison.com [UNAM, Centro de Fisica Aplicada y Tecnologia Avanzada, Apdo. Postal 1-1010, 76000 Queretaro, Qro. (Mexico)

    2015-10-15

    Full text: Due to the increasing use of ionizing radiations, is necessary to monitor the radiation fields and exposure doses in facilities in which they are used. Different facilities or applications involve the use of different radiation and doses, and the sort of needed dosimetry also varies. Sometimes a conventional thermoluminescence (Tl) dosimetry satisfy the requirements since the record of the accumulated dose in a time interval is enough, but other cases could require for real-time measurement of a radiation field, being required a non-Tl dosimetric technique. On the other hand, different applications involve the use of different dose ranges, and so dosimeters with different sensitivities are needed. To solve the diverse needs of radiation detectors and dosimeters, a lot of phosphors materials has been characterized concerning their dosimetric capabilities. For medical application, biocompatible materials are desirable. In this work, we present experimental evidence that Sol-Gel synthesized SiO{sub 2} and SiO{sub 2}:Eu phosphors exhibit Tl glow curves composed by the superposition of several individual glow peaks each located at different temperature ranging from values below 100 up to temperatures greater than 400 degrees C, whose relative sensitivities can be modified by subjecting the phosphors to different thermal annealing. By modulating the relative intensities of the individual Tl peaks, glow curves with different shapes are obtained in such a way that SiO{sub 2} and SiO{sub 2}:Eu can be used to develop dosimeters useful for different dose ranges, and for both, conventional thermoluminescence dosimetry and non-thermoluminescence afterglow-based) dosimetry. (Author)

  10. Microstructural evolution of the system Ni-ZrO{sub 2}-SiO{sub 2} synthesized by the sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Murillo, A., E-mail: angarciam@ipn.m [Instituto Politecnico Nacional, CICATA Unidad Altamira, Km. 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamaulipas (Mexico); Instituto Politecnico Nacional, CIITEC, Cerrada CECATI S/N Col. Sta. Catarina, Del. Azcapotzalco, Mexico D.F. 02250 (Mexico); Carrillo Romo, F. de J. [Instituto Politecnico Nacional, CICATA Unidad Altamira, Km. 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamaulipas (Mexico); Instituto Politecnico Nacional, CIITEC, Cerrada CECATI S/N Col. Sta. Catarina, Del. Azcapotzalco, Mexico D.F. 02250 (Mexico); Torres Huerta, A.M.; Dominguez Crespo, M.A.; Ramirez Meneses, E. [Instituto Politecnico Nacional, CICATA Unidad Altamira, Km. 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamaulipas (Mexico); Terrones, H. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San Jose 2055. Colonia Lomas 4 seccion S.L.P. (Mexico); Flores Vela, A. [Instituto Politecnico Nacional, CICATA Unidad Altamira, Km. 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamaulipas (Mexico)

    2010-04-16

    The analysis of the structural changes corresponding with composition and temperature is fundamental for understanding the applications of ceramic glass. In particular, the system ZrO{sub 2}-SiO{sub 2} is commonly used in the ceramic industry due to the high chemical stability and superior resistance for dissolution during firing in glazes. This work is focused on the synthesis of Ni doped ZrO{sub 2}-SiO{sub 2} powders with different Zr:Si molar ratios (20:80, 50:50 and 70:30) by sol-gel process. For purposes of comparison, un-doped ZrO{sub 2}-SiO{sub 2} systems were also prepared. TEOS, zirconium propoxide and nickel chloride hexahydrate were used as precursors of the SiO{sub 2}, ZrO{sub 2} and ion dopant, respectively. The obtained xerogels were thermally treated from 300 to 1300 {sup o}C in order to follow their structural evolution. FT-IR results show the corresponding bands of the M-O bonds related to the formation of zircon at high temperatures, while XRD analyses display t-ZrO{sub 2} with traces of m-ZrO{sub 2} at the evaluated temperatures; also, between 1200 and 1300 {sup o}C, the zircon compound (ZrSiO{sub 4}) was detected. It was observed that inserting nickel as a dopant has a significant effect on the structural and morphological characteristics. From the comparison of the doped and un-doped specimens, we hypothesize that the presence of Ni and the heat treatment promote the stabilization and crystallization of the zircon phase at molar ratios higher than 50Zr:50Si, or Ni is incorporating into the ZrO{sub 2} phase, provoking oxygen vacancies and leading to tetragonal phase stabilization.

  11. Synthesis of mesoporous SiO{sub 2}-ZnO nanocapsules: encapsulation of small biomolecules for drugs and 'SiOZO-plex' for gene delivery

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vijay Bhooshan [School of Engineering Sciences and Technology, University of Hyderabad (India); Annamanedi, Madhavi [School of Life Sciences, University of Hyderabad, Department of Animal Sciences (India); Prashad, Muvva Durga [University of Hyderabad, Centre for Nanoscience and Nanotechnology (India); Arunasree, Kalle M. [School of Life Sciences, University of Hyderabad, Department of Animal Sciences (India); Mastai, Yitzhak; Gedanken, Aharon, E-mail: gedanken@mail.biu.ac.il [Bar-Ilan University, Department of Chemistry, Institute for Nanotechnology and Advanced Materials (Israel); Paik, Pradip, E-mail: ppse@uohyd.ernet.in [School of Engineering Sciences and Technology, University of Hyderabad (India)

    2013-09-15

    This work presents a new synthesis of mesoporous SiO{sub 2}-ZnO composite nanocapsules with sizes of 90-150 nm and represents their applications in encapsulation of small biomolecules (fluorescent molecules, drugs, and DNA) for uses in medical biotechnology (e.g., drug and gene delivery) for the first time. The nanocapsule size and morphology have been confirmed through the HRSEM and HRTEM. The mesoporous structure of the novel materials has been confirmed through both BET and HRTEM, and the pore diameter observed to be ca. 2-8 nm with an average diameter of 5.1 nm. The BET surface area of mesoporous SiO{sub 2}-ZnO was found to be {approx}230 m{sup 2} g{sup -1}. Three different types of pores were detected through HRTEM: type-I, normal pores in silica matrix, pore with ZnO nanoparticles at the boundary (type-II) and type-III, the pores with tiny ZnO nanoparticles ({approx}5-7 nm) inside them. To demonstrate the biocompatibility and cell viability of the nanocapsules, normal and cancerous lymphocyte cells have been chosen and investigated in a systematic way. Fluorescent dye (Rhodamine 6G), anticancer drug e.g., Doxorubicin (DOX) were loaded in all types of pores, and EtBr-labeled DNA molecules were loaded efficiently into the mesopores of second and third types of the composite nanocapsules to manifest the characteristic of mesoporous, and to find out its loading efficacy. The release kinetics of Rhodamine 6G and DOX were studied. The results highlight the potential of novel functional mesoporous SiO{sub 2}-ZnO nanoparticles for using as the carrier of drugs and formation of 'SiOZO-plex', a complex of mesoporous SiO{sub 2}-ZnO with DNA for gene delivery applications.Graphical Abstract.

  12. Hydrophilic and mesoporous SiO{sub 2}-TiO{sub 2}-SO{sub 3}H system for fuel cell membrane applications

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Lan-Young [Department of Fine Chemical Engineering and Chemistry, Chungnam National University, 220 Kung-dong, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Oh, Song-Yul [Department of Materials Science, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan); Matsuda, Atsunori, E-mail: matsuda@ee.tut.ac.j [Department of Materials Science, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan); Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan); Lee, Chang-Soo [Department of Chemical Engineering, Chungnam National University, 220 Kung-dong, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Kim, Dong-Pyo, E-mail: dpkim@cnu.ac.k [Department of Fine Chemical Engineering and Chemistry, Chungnam National University, 220 Kung-dong, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Graduate School of Analytical Science and Technology, Chungnam National University, 220 Kung-dong, Yuseong-gu, Daejeon 305-764 (Korea, Republic of)

    2011-03-30

    Graphical abstract: The composite films containing SiO{sub 2}-TiO{sub 2}-SO{sub 3}H resin additives, with strong water retention capabilities, showed superior proton conductivity, even at 120 {sup o}C and 25% RH, as well as a slightly improved current density at 30% RH and 70 {sup o}C, when compared to costly Nafion film. Display Omitted Research highlights: The hydrophilic and mesoporous SiO{sub 2}-TiO{sub 2}-SO{sub 3}H resins have a potential to be used as alternative membrane source materials in PEFCs. The sulfonation for hydrophilicity is conducted via simple chelating chemistry between catecholic groups and surface Ti ions. The proton conductivity of SiO{sub 2}-TiO{sub 2}-SO{sub 3}H composite films is superior to the commercial Nafion film. - Abstract: Hydrophilic and mesoporous sulfonated SiO{sub 2}-TiO{sub 2}-SO{sub 3}H systems as new additives for fuel cell electrolyte membranes are directly synthesized by the binary sol-gel reaction of TEOS-TiCl{sub 4} and consecutive sulfonation with a hydrophilic generator, dihydroxy-m-benzenedisulfonic acid disodium salt. The sulfonation approach makes use of the simple chelating chemistry between the catecholic groups (dihydroxy benzene) and surface Ti ions of the inorganic ordered mesoporous SBA-15 structure. The system is successfully employed in fuel cell membrane applications with a composite Nafion membrane mixed with a mesoporous hydrophilic resin additive, and reveals an obvious enhancement of the proton conductivity at low humidity and elevated temperatures. This improvement was attributed to the excellent water retention capability of the hydrophilic mesoporous resin.

  13. One step process of decomposition and polymerization to fabricate SiO{sub 2} hollow spheres/polyimide composite for foldable OLEDs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Kyu [SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Dong Won; Moon, Soo Hyun [School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Shin, Dong-Wook [SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); College of Engineering, Mathematics and Physical Sciences, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Oh, Tae Sik [School of Mechanical and ICT Convergence Engineering, Sunmoon University, Asan 336-708 (Korea, Republic of); Yoo, Ji Beom, E-mail: jbyoo@skku.edu [SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2017-03-15

    Graphical abstract: The SiO{sub 2} hollow spheres and polyimide hybrid synthesized using one step process, simultaneous occurrence of decomposition and polymerization (SODP) is useful with a ultra-low dielectric constant and high thermal stability for flexible OLED. - Highlights: • We fabricated hybrid films of SHS/PI by using a one step process with SODP. • The film has ultralow dielectric constant (50 vol% at k = 1.67). • There is no collapse of SiO{sub 2} hollow spheres in the PI matrix after bending test for 50,000 cycles. - Abstract: The fabrication of interlayer dielectrics (ILDs) in flexible organic light-emitting diodes (OLEDs) requires flexible materials with a low dielectric constant as well as materials with excellent electrical, thermal, and mechanical properties for optimal device performance. Hybrid films of SiO{sub 2} hollow spheres (SHS)/polyimide (PI) were prepared using a one-step process, with simultaneous occurrence of decomposition (polystyrene, PS) and polymerization (PI) (SODP). No collapse of SiO{sub 2} hollow spheres in PI was observed from 10 vol% to 60 vol% SHS in hybrid films. The dielectric constant of hybrid films was reduced from 3.45 to 1.67 and was saturated at above 50 vol% of SHS due to the maximum fill factor of SHS in the PI matrix. The thermal stability was excellent up to 500 °C due to the inherent thermal property of PI. After a bending test for 50,000 cycles at a bending radius of 1 mm, the SHS/PI hybrid films retained their dielectric constant and current density. These results indicate the hybrid film to be the most promising candidate for flexible ILDs with a low dielectric constant and high thermal stability for foldable OLEDs.

  14. Influence of the polymer amount on bioactivity and biocompatibility of SiO{sub 2}/PEG hybrid materials synthesized by sol–gel technique

    Energy Technology Data Exchange (ETDEWEB)

    Catauro, M., E-mail: michelina.catauro@unina2.it [Department of Industrial and Information Engineering, Second University of Naples, Via Roma 29, 81031 Aversa (Italy); Bollino, F.; Papale, F. [Department of Industrial and Information Engineering, Second University of Naples, Via Roma 29, 81031 Aversa (Italy); Gallicchio, M.; Pacifico, S. [Department of Environmental Biological and Pharmaceutical Sciences and Technologies, Second University of Naples, Via Vivaldi 43, 81100 Caserta (Italy)

    2015-03-01

    SiO{sub 2}/PEG organic–inorganic hybrid materials, which differ in polyethylene glycol (PEG) content, were synthesized by sol–gel technique and the characterization of their structure and biological properties was carried out in order to evaluate the possible use in biomedical field. FT-IR spectroscopy detected that the two components of the hybrids (SiO{sub 2} and PEG) are linked by hydrogen bonds between the Si–OH groups of the inorganic phase and the terminal alcoholic groups and/or the ethereal oxygen atoms in the repeating units of polymer. X-ray diffraction analysis ascertained the amorphous nature of the gels and the observation of their morphology by SEM microscopy confirmed that the interpenetration of the two phases (organic and inorganic) occurs on nanometric scale. The biological characterization was carried out as a function of the polymer amount to study its influence on material behavior. The results showed that the synthesized materials were bioactive and biocompatible. The formation of a hydroxyapatite layer, indeed, was observed on their surface by SEM/EDX analysis after soaking in simulated body fluid. Moreover, the biocompatibility of SiO{sub 2}/PEG hybrids was assessed performing MTT and SRB cytotoxicity tests on fibroblast cell NIH 3T3 after 24 and 48 h of exposure, as well as Trypan Blue dye exclusion test. The response to the presence of the investigated materials was positive. The cell growth and proliferation showed dependence on polymer amount and time of exposure to the material extracts. Therefore, the obtained results are encouraging for the use of the obtained hybrids in dental or orthopedic applications. - Highlights: • SiO{sub 2}/PEG hybrid biomaterials synthesized by sol–gel method at various PEG percentages • Chemical and morphological characterization of hybrid materials • Chemical interactions between inorganic and organic components • Biological characterizations with MTT and SRB cytotoxicity tests

  15. Surface morphology of amorphous germanium thin films following thermal outgassing of SiO{sub 2}/Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Valladares, L. de los Santos, E-mail: ld301@cam.ac.uk [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J. Thomson Ave., Cambridge CB3 0HE (United Kingdom); Dominguez, A. Bustamante [Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Apartado Postal 14-0149, Lima (Peru); Llandro, J.; Holmes, S. [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J. Thomson Ave., Cambridge CB3 0HE (United Kingdom); Quispe, O. Avalos [Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Apartado Postal 14-0149, Lima (Peru); Langford, R. [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J. Thomson Ave., Cambridge CB3 0HE (United Kingdom); Aguiar, J. Albino [Laboratório de Supercondutividade e Materiais Avançados, Departamento de Física, Universidade Federal de Pernambuco, 50670-901, Recife (Brazil); Barnes, C.H.W. [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J. Thomson Ave., Cambridge CB3 0HE (United Kingdom)

    2014-10-15

    Highlights: • Annealing promotes outgassing of SiO{sub 2}/Si wafers. • Outgassing species embed in the a-Ge film forming bubbles. • The density of bubbles obtained by slow annealing is smaller than by rapid annealing. • The bubbles explode after annealing the samples at 800 °C. • Surface migration at higher temperatures forms polycrystalline GeO{sub 2} islands. - Abstract: In this work we report the surface morphology of amorphous germanium (a-Ge) thin films (140 nm thickness) following thermal outgassing of SiO{sub 2}/Si substrates. The thermal outgassing was performed by annealing the samples in air at different temperatures from 400 to 900 °C. Annealing at 400 °C in slow (2 °C/min) and fast (10 °C/min) modes promotes the formation of bubbles on the surface. A cross sectional view by transmission electron microscope taken of the sample slow annealed at 400 °C reveals traces of gas species embedded in the a-Ge film, allowing us to propose a possible mechanism for the formation of the bubbles. The calculated internal pressure and number of gas molecules for this sample are 30 MPa and 38 × 10{sup 8}, respectively. Over an area of 22 × 10{sup −3} cm{sup 2} the density of bubbles obtained at slow annealing (9 × 10{sup 3} cm{sup −2}) is smaller than that at rapid annealing (6.4 × 10{sup 4} cm{sup −2}), indicating that the amount of liberated gas in both cases is only a fraction of the total gas contained in the substrate. After increasing the annealing temperature in the slow mode, bubbles of different diameters (from tens of nanometers up to tens of micrometers) randomly distribute over the Ge film and they grow with temperature. Vertical diffusion of the outgas species through the film dominates the annealing temperature interval 400–600 °C, whereas coalescence of bubbles caused by lateral diffusion is detected after annealing at 700 °C. The bubbles explode after annealing the samples at 800 °C. Annealing at higher temperatures, such as

  16. Photoluminescence and structural studies of Tb and Eu implanted at high temperatures into SiO{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Bregolin, F.L. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, 91501-970, Porto Alegre-RS (Brazil); Sias, U.S., E-mail: uilson.sias@gmail.com [Instituto Federal Sul-rio-grandense, Campus Pelotas, Praca 20 de Setembro 455, 96015-360, Pelotas-RS (Brazil); Behar, M. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, 91501-970, Porto Alegre-RS (Brazil)

    2013-03-15

    The present work deals with the photoluminescence (PL) emitted from Eu and Tb ions implanted at room temperature (RT) up to 350 Degree-Sign C in a SiO{sub 2} matrix, followed by a further anneal process. The ions were implanted with energy of 100 keV and a fluence of 3 Multiplication-Sign 10{sup 15} ions/cm Superscript-Two . Further anneals were performed in atmospheres of N{sub 2} or O{sub 2} with temperatures ranging from 500 up to 800 Degree-Sign C. PL measurements were performed at RT and structural measurements were done via transmission electron microscopy (TEM). In addition, the Rutherford backscattering technique (RBS) was used to investigate the corresponding ion depth profiles. For Tb, the optimal implantation temperature was 200 Degree-Sign C, and the anneal one was of 500 Degree-Sign C. Under these conditions, the PL yield of the sharp band centered at 550 nm was significatively higher than the one obtained with RT implants. The PL spectra corresponding to the Eu ions show two bands, one narrow centered around 650 nm and a second broad one in the blue-green region. The implantation temperature plays a small influence on the PL shape and yield. However, the annealing atmosphere has a strong influence on it. Samples annealed in N{sub 2} present a broad PL band, ranging from 370 up to 840 nm. On the other hand, the O{sub 2} anneal conserves the original as-implanted spectrum, that is: a broad PL band in the blue-green region together with sharp PL band in the red one. For both ions, Tb and Eu, the TEM analyses indicate the formation of nanoclusters in the hot as-implanted samples. - Highlights: Black-Right-Pointing-Pointer Eu and Tb nanoparticles were obtained by hot ion implantation into SiO{sub 2} matrix. Black-Right-Pointing-Pointer TEM results indicate the formation of nanoclusters in the hot as-implanted samples. Black-Right-Pointing-Pointer Samples annealed in N{sub 2} presented a broad PL band (from 370 up to 840 nm). Black-Right-Pointing-Pointer O

  17. A New Analytical Subthreshold Behavior Model for Single-Halo, Dual-Material Gate Silicon-on-Insulator Metal Oxide Semiconductor Field Effect Transistor

    Science.gov (United States)

    Chiang, Te-Kuang

    2008-11-01

    On the basis of the exact solution of the two-dimensional Poisson equation, a new analytical subthreshold behavior model consisting of the two-dimensional potential, threshold voltage, and subthreshold current for the single-halo, dual-material gate (SHDMG) silicon-on-insulator (SOI) metal oxide semiconductor field effect transistor (MOSFET) is developed. The model is verified by the good agreement with a numerical simulation using the device simulator MEDICI. The model not only offers a physical insight into device physics but is also an efficient device model for the circuit simulation.

  18. The effect of 3-aminopropyltrimethoxysilane on the formation of NiFe{sub 2}O{sub 4}/SiO{sub 2} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hongxia [Department of Applied Physics, Center for Condensed Matter Science and Technology, Harbin Institute of Technology, Harbin 150001 (China); Department of Chemistry, Harbin Normal University, Harbin 150025 (China); Zhang Wei; Zhang Faling [Department of Applied Physics, Center for Condensed Matter Science and Technology, Harbin Institute of Technology, Harbin 150001 (China); Cao Yuan [Department of Chemistry, Harbin Normal University, Harbin 150025 (China); Su Wenhui [Department of Applied Physics, Center for Condensed Matter Science and Technology, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: hsdzkx@163.com

    2008-07-15

    NiFe{sub 2}O{sub 4}/SiO{sub 2} nanocomposites were prepared using a sol-gel method with the addition of 3-aminopropyltrimethoxysilane (APS). Different phases and morphologies of NiFe{sub 2}O{sub 4}/SiO{sub 2} nanocomposites were obtained when different amounts of APS were used. The structural properties of the products were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Sheet-like morphology was observed at higher molar ratio of APS to NiFe{sub 2}O{sub 4}, while spherical NiFe{sub 2}O{sub 4}/SiO{sub 2} nanoparticles separated from each other were formed at lower molar ratio of APS to NiFe{sub 2}O{sub 4}. The magnetic properties of the nanocomposites were also investigated, indicating that the interparticle interactions exhibit strong dependence on the molar ratio of APS to NiFe{sub 2}O{sub 4}.

  19. Single photon detection and signal analysis for high sensitivity dosimetry based on optically stimulated luminescence with beryllium oxide

    Science.gov (United States)

    Radtke, J.; Sponner, J.; Jakobi, C.; Schneider, J.; Sommer, M.; Teichmann, T.; Ullrich, W.; Henniger, J.; Kormoll, T.

    2018-01-01

    Single photon detection applied to optically stimulated luminescence (OSL) dosimetry is a promising approach due to the low level of luminescence light and the known statistical behavior of single photon events. Time resolved detection allows to apply a variety of different and independent data analysis methods. Furthermore, using amplitude modulated stimulation impresses time- and frequency information into the OSL light and therefore allows for additional means of analysis. Considering the impressed frequency information, data analysis by using Fourier transform algorithms or other digital filters can be used for separating the OSL signal from unwanted light or events generated by other phenomena. This potentially lowers the detection limits of low dose measurements and might improve the reproducibility and stability of obtained data. In this work, an OSL system based on a single photon detector, a fast and accurate stimulation unit and an FPGA is presented. Different analysis algorithms which are applied to the single photon data are discussed.

  20. Electrocatalytic oxidation of diethylaminoethanethiol and hydrazine at single-walled carbon nanotubes modified with prussian blue nanoparticles

    CSIR Research Space (South Africa)

    Adekunle, AS

    2010-11-01

    Full Text Available In this work, edged plane pyrolytic graphite electrode EPPGE was modified with functionalised single-walled carbon nanotubes and Prussian blue nanoparticles (PB). The modified electrode was characterised by techniques such as TEM, FTIR, XPS, EDX...

  1. Single-step immobilization of cell adhesive peptides on a variety of biomaterial substrates via tyrosine oxidation with copper catalyst and hydrogen peroxide.

    Science.gov (United States)

    Kakinoki, Sachiro; Yamaoka, Tetsuji

    2015-04-15

    Immobilization of biologically active peptides which were isolated from extracellular matrix proteins is a powerful strategy for the design and functionalization of biomaterial substrates. However, the method of peptide immobilization was restricted, that is, peptide is often immobilized through the reactive groups inherent in substrates with multistep reactions. Here, we report a single-step immobilization of fibronectin-derived cell adhesive peptide (Arg-Glu-Asp-Val; REDV) onto polymer materials by use of tyrosine oxidation with copper catalyst and hydrogen peroxide. REDV peptide was successfully immobilized on tissue culture polystyrene, poly(ethylene terephthalate), poly(vinyl chloride), expanded-poly(tetrafluoroethylene), and poly(l-lactic acid), resulting in enhanced adhesion of human umbilical vein endothelial cells. This method is a single-step reaction under very mild conditions and is available for the biological functionalization of various medical devices.

  2. Single carrier trapping and de-trapping in scaled silicon complementary metal-oxide-semiconductor field-effect transistors at low temperatures

    Science.gov (United States)

    Li, Zuo; Khaled Husain, Muhammad; Yoshimoto, Hiroyuki; Tani, Kazuki; Sasago, Yoshitaka; Hisamoto, Digh; Fletcher, Jonathan David; Kataoka, Masaya; Tsuchiya, Yoshishige; Saito, Shinichi

    2017-07-01

    The scaling of Silicon (Si) technology is approaching the physical limit, where various quantum effects such as direct tunnelling and quantum confinement are observed, even at room temperatures. We have measured standard complementary metal-oxide-semiconductor field-effect-transistors (CMOSFETs) with wide and short channels at low temperatures to observe single electron/hole characteristics due to local structural disturbances such as roughness and defects. In fact, we observed Coulomb blockades in sub-threshold regimes of both p-type and n-type Si CMOSFETs, showing the presence of quantum dots in the channels. The stability diagrams for the Coulomb blockade were explained by the potential minima due to poly-Si grains. We have also observed sharp current peaks at narrow bias windows at the edges of the Coulomb diamonds, showing resonant tunnelling of single carriers through charge traps.

  3. Thermal behavior and phase transformation of ZrO{sub 2}–10%SiO{sub 2} precursor powder prepared by a co-precipitation route without adding stability agent

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Hsueh-Liang [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Hwang, Weng-Sing [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Institute of Nanotechnology and Microsystems Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Wang, Cheng-Li [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Lee, Kuen-Chan [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Huang, Hong-Hsin [Department of Electrical Engineering, Cheng Shiu University, 840 Cheng Ching Road, Niaosong, Kaohsiung 83347, Taiwan (China); Lee, Huey-Er, E-mail: huerle@kmu.edu.tw [School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Department of Dentistry, Kaohsiung Medical University, 100 Tzyou 1st Road, Kaohsiung 807, Taiwan (China)

    2014-12-15

    Highlights: • The precursor powders contained about 68.3 wt% ZrO{sub 2}, which corresponds to ZrO{sub 2}·1/8 H{sub 2}O. • The exothermic peak temperature of tetragonal ZrO{sub 2} formation occurred at 1014 K. • The activation energy of ZrO{sub 2}–10%SiO{sub 2} precursors crystallization is 993.7 kJ/mol. • Only the tetragonal ZrO{sub 2} formed when the precursor calcined at 1173–1373 K for 2 h. • As calcined at 1473 K for 2 h, tetragonal ZrO{sub 2} fully converted to monoclinic ZrO{sub 2}. - Abstract: Thermal behavior and phase transformation of ZrO{sub 2}–10%SiO{sub 2} precursor powder prepared by a co-precipitation route without adding stability agent has been studied using different thermal analysis/thermogravimetry (DTA/TG), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), nano beam electron diffraction (NBED), high-resolution TEM (HRTEM) and energy-dispersive X-ray spectrometer (EDS). The TG results show that four weight loss regions were from 298 to 443 K, 443 to 743 K, 743 to 793 K and 793 to 1400 K. The DTA result shows that the ZrO{sub 2} freeze-dried precursor powders crystallization at 1014 K. The activation energy of 993.7 kJ/mol was obtained for tetragonal ZrO{sub 2} crystallization using a non-isothermal process. The XRD result shows that only a single phase of tetragonal ZrO{sub 2} appears when the freeze-dried precursor powders after calcination between 1173 and 1373 K for 2 h. Moreover, when calcined at 1473 K for 2 h, the phase transformation from tetragonal ZrO{sub 2} fully converted to monoclinic ZrO{sub 2} occurred.

  4. Investigation of superior electro-optical properties of SnO{sub 2}/SiO{sub 2} nanocomposite over its individual counterpart SnO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Naveen Kumar, P.; Sahaya Selva Mary, J.; Chandrakala, V.; Jothi Jeyarani, W.; Merline Shyla, J., E-mail: jmshyla@gmail.com

    2017-06-01

    A comparative investigation of SnO{sub 2}/SiO{sub 2} nanocomposite with SnO{sub 2} nanoparticles has been conducted in the present study with the intent of learning the probable enhancement of the properties of the nanocomposite over those of the bare nanoparticles which has not been widely reported before. SnO{sub 2} nanoparticles and SnO{sub 2}/SiO{sub 2} nanocomposite have been synthesized via the facile and versatile sol-gel method. The samples were characterized with X-Ray Diffraction (XRD), High Resolution Scanning Electron Microscopy (HRSEM), Brunauer Emmett Teller (BET) studies, Fourier Transform Infra-Red spectroscopy (FT-IR), UV–Visible (UV–Vis) spectroscopy and Field-dependent photo conductivity technique for the evaluation of their crystallite size, structure & morphology, surface, chemical, optical and electrical properties respectively. Scherrer’s equation was used to determine the crystallite size of the as-synthesized samples from the XRD data. The particle size of SnO{sub 2}/SiO{sub 2} nanocomposite as observed through HRSEM was found to be reduced when compared with the bare SnO{sub 2} nanoparticles suggesting a possible increase in the optical band gap of the former which has been further confirmed in the optical studies. The surface area of SnO{sub 2}/SiO{sub 2} nanocomposite revealed a remarkable enrichment by approximately 5 folds in comparison with that of SnO{sub 2} nanoparticles which suggests an enhancement in its corresponding optical and electrical properties. The SnO{sub 2}/SiO{sub 2} nanocomposite recorded appreciated values of field-dependent photo and dark currents with several folds of augmentation thereby qualifying as an efficient photoconducting material. Attributed with an improved surface area and increased photoconducting nature, the SnO{sub 2}/SiO{sub 2} nanocomposite could be presented as an excellent photoanode material for nanomaterials based Dye Sensitized Solar Cells (DSSCs). - Highlights: • SnO{sub 2}/SiO{sub 2

  5. Graphene oxide and shape-controlled silver nanoparticle hybrids for ultrasensitive single-particle surface-enhanced Raman scattering (SERS) sensing.

    Science.gov (United States)

    Fan, Wei; Lee, Yih Hong; Pedireddy, Srikanth; Zhang, Qi; Liu, Tianxi; Ling, Xing Yi

    2014-05-07

    Graphene oxide (GO) is an emerging material for surface-enhanced Raman scattering (SERS) due to its strong chemical enhancement. Studying the SERS performance of plasmonic nanoparticle/GO hybrid materials at the single particle level is crucial for direct probing of the chemical effect of GO on plasmonic nanoparticles. In this work, we integrate GO and shape-controlled Ag nanoparticles to create hybrid nanomaterials, and the chemical enhancement arising from GO is investigated using single-particle SERS measurements. Ag nanoparticle@GO hybrid nanostructures are prepared by assembling Ag nanoparticles, including spheres, cubes and octahedra with GO sheets. The SERS behaviors of the hybrid nanostructures are characterized, and 2-3 times enhanced SERS intensities are detected from the Ag nanoparticle@GO hybrid nanostructures as compared to pure Ag nanoparticles. Furthermore, we probe the mechanism of SERS enhancement in the hybrid nanostructures by changing the surface coverage of GO on Ag octahedra, by using reduced GO in place of GO as well as by using probe molecules of different electronegativities. This hybrid system is an excellent candidate for single-particle SERS sensors. Sub-nanomolar levels of aromatic molecules are detected using a single Ag/GO hybrid nanomaterial. This as-prepared GO and shape-controlled Ag nanoparticle hybrid is capable of serving as a high performance SERS platform, providing new opportunities for efficient chemical and biological sensing applications.

  6. Communication: Hole localization in Al-doped quartz SiO{sub 2} within ab initio hybrid-functional DFT

    Energy Technology Data Exchange (ETDEWEB)

    Gerosa, Matteo [Department of Energy, Politecnico di Milano, via Ponzio 34/3, 20133 Milano (Italy); Di Valentin, Cristiana; Pacchioni, Gianfranco [Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via R. Cozzi 55, 20125 Milan (Italy); Bottani, Carlo Enrico, E-mail: carlo.bottani@polimi.it [Department of Energy, Politecnico di Milano, via Ponzio 34/3, 20133 Milano (Italy); Center for Nano Science and Technology @Polimi, Istituto Italiano di Tecnologia, via Pascoli 70/3, 20133 Milano (Italy); Onida, Giovanni [Dipartimento di Fisica dell’ Universita’ degli Studi di Milano and European Theoretical Spectroscopy Facility (ETSF), Via Celoria 16, 20133 Milan (Italy)

    2015-09-21

    We investigate the long-standing problem of hole localization at the Al impurity in quartz SiO{sub 2}, using a relatively recent DFT hybrid-functional method in which the exchange fraction is obtained ab initio, based on an analogy with the static many-body COHSEX approximation to the electron self-energy. As the amount of the admixed exact exchange in hybrid functionals has been shown to be determinant for properly capturing the hole localization, this problem constitutes a prototypical benchmark for the accuracy of the method, allowing one to assess to what extent self-interaction effects are avoided. We obtain good results in terms of description of the charge localization and structural distortion around the Al center, improving with respect to the more popular B3LYP hybrid-functional approach. We also discuss the accuracy of computed hyperfine parameters, by comparison with previous calculations based on other self-interaction-free methods, as well as experimental values. We discuss and rationalize the limitations of our approach in computing defect-related excitation energies in low-dielectric-constant insulators.

  7. Atomic-scale finishing of carbon face of single crystal SiC by combination of thermal oxidation pretreatment and slurry polishing

    Science.gov (United States)

    Deng, Hui; Liu, Nian; Endo, Katsuyoshi; Yamamura, Kazuya

    2018-03-01

    Single-crystal silicon carbide (4H-SiC) has a range of useful physical, mechanical and electronic properties that make it a promising material for fabrication of next-generation semiconductor devices. In this work, we report a hybrid polishing process combining thermal oxidation pretreatment and soft abrasive polishing to realize the damage-free and atomic-scale smooth finishing of the carbon face of 4H-SiC. By thermal oxidation pretreatment, the hardness of the carbon face has been reduced from 4.6 GPa to 1.7 GPa, which enables highly efficient polishing using CeO2 slurry. For conventional CeO2 slurry polishing without pretreatment, scratches still existed after a long polishing duration for 16 h. The probable scratch removal mechanism in CeO2 slurry polishing has been proposed based on surface morphology changes during polishing. Whereas a scratch-free surface with well-ordered SiC atomic steps was obtained within a short polishing duration of only 3 h when polishing was conducted on a thermally oxidized surface. Our results demonstrate that hybrid polishing combining surface pretreatment and soft abrasive polishing is a promising approach to realize the damage-free and atomic-scale smooth finishing of the carbon face of 4H-SiC.

  8. Cytotoxicity study of iron oxide nanoparticles, single-wall carbon nanotubes and their complexes applied to MCF7 breast cancer cells

    Science.gov (United States)

    Mege, Karine

    Reactive Oxygen Species (ROS) are radicals of great concern to biologists. Their role in several diseases---such as neurodegenerative disease, diabetes, premature aging and cancer---has been intensively investigated during the last decade. Since a major focus in cancer research is to better understand how it is induced and therefore how it can be cured, the study of the cytotoxic effects of ROS production within cancer cells is vital. Nanotechnology is an emerging field of science that promises great improvements in a number of disciplines. Nano medicine is one of its daughter fields. Various nanomaterials are used for diagnosis and disease detection, therapy and medical imaging, and many are already being used in oncology medicine. The two most frequently used nanomaterials in cancer research are Carbon nanotubes (CNTs) and iron oxide nanoparticles (IONPs). They have been proven to play a significant role in the ROS production of various cancer cells. In this context, this thesis emphasizes the need to study the impact of nanoparticles, such as single-walled carbon nanotubes (SWCNTs), iron oxide nanoparticles (IONPs) and their complexes, on a human breast cancer cell line (MCF-7). To date, there have been very few studies assessing the effect on the oxidative stress activity of this cell line using these nanoparticles and their complexes.

  9. Miniaturized and green method for determination of chemical oxygen demand using UV-induced oxidation with hydrogen peroxide and single drop microextraction

    International Nuclear Information System (INIS)

    Akhoundzadeh, Jeyran; Chamsaz, Mahmoud; Costas, Marta; Lavilla, Isela; Bendicho, Carlos

    2013-01-01

    We report on a green method for the determination of low levels of chemical oxygen demand. It is based on the combination of (a) UV-induced oxidation with hydrogen peroxide, (b) headspace single-drop microextraction with in-drop precipitation, and (c) micro-turbidimetry. The generation of CO 2 after photolytic oxidation followed by its sequestration onto a microdrop of barium hydroxide gives rise to a precipitate of barium carbonate which is quantified by turbidimetry. UV-light induced oxidation was studied in the absence and presence of H 2 O 2 , ultrasound, and ferrous ion. Determinations of chemical oxygen demand were performed using potassium hydrogen phthalate as a model compound. The optimized method gives a calibration curve that is linear between 3.4 and 20 mg L −1 oxygen. The detection limit was 1.2 mg L −1 of oxygen, and the repeatability (as relative standard deviation) was around 5 %. The method was successfully applied to the determination of chemical oxygen demand in different natural waters and a synthetic wastewater. (author)

  10. Oxidized base damage and single-strand break repair in mammalian genomes: role of disordered regions and posttranslational modifications in early enzymes.

    Science.gov (United States)

    Hegde, Muralidhar L; Izumi, Tadahide; Mitra, Sankar

    2012-01-01

    Oxidative genome damage induced by reactive oxygen species includes oxidized bases, abasic (AP) sites, and single-strand breaks, all of which are repaired via the evolutionarily conserved base excision repair/single-strand break repair (BER/SSBR) pathway. BER/SSBR in mammalian cells is complex, with preferred and backup sub-pathways, and is linked to genome replication and transcription. The early BER/SSBR enzymes, namely, DNA glycosylases (DGs) and the end-processing proteins such as abasic endonuclease 1 (APE1), form complexes with downstream repair (and other noncanonical) proteins via pairwise interactions. Furthermore, a unique feature of mammalian early BER/SSBR enzymes is the presence of a disordered terminal extension that is absent in their Escherichia coli prototypes. These nonconserved segments usually contain organelle-targeting signals, common interaction interfaces, and sites of posttranslational modifications that may be involved in regulating their repair function including lesion scanning. Finally, the linkage of BER/SSBR deficiency to cancer, aging, and human neurodegenerative diseases, and therapeutic targeting of BER/SSBR are discussed. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. Xanthine Oxidase Activity Is Associated with Risk Factors for Cardiovascular Disease and Inflammatory and Oxidative Status Markers in Metabolic Syndrome: Effects of a Single Exercise Session

    Directory of Open Access Journals (Sweden)

    Ana Maria Pandolfo Feoli

    2014-01-01

    Full Text Available Objective. The main goal of the present study was to investigate the xanthine oxidase (XO activity in metabolic syndrome in subjects submitted to a single exercise session. We also investigated parameters of oxidative and inflammatory status. Materials/Methods. A case-control study (9 healthy and 8 MS volunteers was performed to measure XO, superoxide dismutase (SOD, glutathione peroxidase activities, lipid peroxidation, high-sensitivity C-reactive protein (hsCRP content, glucose levels, and lipid profile. Body mass indices, abdominal circumference, systolic and diastolic blood pressure, and TG levels were also determined. The exercise session consisted of 3 minutes of stretching, 3 minutes of warm-up, 30 minutes at a constant dynamic workload at a moderate intensity, and 3 minutes at a low speed. The blood samples were collected before and 15 minutes after the exercise session. Results. Serum XO activity was higher in MS group compared to control group. SOD activity was lower in MS subjects. XO activity was correlated with SOD, abdominal circumference, body mass indices, and hsCRP. The single exercise session reduced the SOD activity in the control group. Conclusions. Our data support the association between oxidative stress and risk factors for cardiovascular diseases and suggest XO is present in the pathogenesis of metabolic syndrome.

  12. Oxide ceramics

    International Nuclear Information System (INIS)

    Ryshkewitch, E.; Richerson, D.W.

    1985-01-01

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

  13. Improving the drug delivery characteristics of graphene oxide based polymer nanocomposites through the “one-pot” synthetic approach of single-electron-transfer living radical polymerization

    International Nuclear Information System (INIS)

    Gao, Peng; Liu, Meiying; Tian, Jianwen; Deng, Fengjie; Wang, Ke; Xu, Dazhuang; Liu, Liangji; Zhang, Xiaoyong; Wei, Yen

    2016-01-01

    Graphical abstract: The PEGylated graphene oxides with high water dispersibility, good biocompatibility as well as high drug loading capability were fabricated via “one-pot” SET-LRP. - Highlights: • Surface modification of graphene oxide with polymers. • One-pot single-electron-transfer living radical polymerization. • Improving drug delivery characteristics. • The synthetic approach is rather simple, universal and effective. - Abstract: Graphene oxide (GO) based polymer nanocomposites have attracted extensive research interest recently for their outstanding physicochemical properties and potential applications. However, surface modification of GO with synthetic polymers has demonstrated to be trouble for most polymerization procedures are occurred under non-aqueous solution, which will in turn lead to the restacking of GO. In this work, a facile and efficient “one-pot” strategy has been developed for surface modification of GO with synthetic polymers through single-electron-transfer living radical polymerization (SET-LRP). The GO based polymer nanocomposites were obtained via SET-LRP in aqueous solution using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as the monomer and 11-bromoundecanoic acid as the initiator, which could be effectively adsorbed on GO through hydrophobic interaction. The successful preparation of GO based polymer nanocomposites was confirmed by a series of characterization techniques such as 1 H nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. The resultant products exhibit high water disperisibility, excellent biocompatibility and high efficient drug loading capability, making these PEGylated GO nanocomposites promising candidates for biomedical applications.

  14. Combining in situ chemical oxidation, stabilization, and anaerobic bioremediation in a single application to reduce contaminant mass and leachability in soil

    Energy Technology Data Exchange (ETDEWEB)

    Cassidy, Daniel P., E-mail: daniel.cassidy@wmich.edu [Department of Geosciences, Western Michigan University, Kalamazoo, MI 49008 (United States); Srivastava, Vipul J., E-mail: vipul.srivastava@ch2m.com [CH2M HILL, 125S Wacker, Ste 3000, Chicago, IL 60606 (United States); Dombrowski, Frank J., E-mail: frank.dombrowski@we-energies.com [We Energies, 333W Everett St., A231, Milwaukee, WI 53203 (United States); Lingle, James W., E-mail: jlingle@epri.com [Electric Power Research Institute (EPRI), 4927W Willow Road, Brown Deer, WI 53223 (United States)

    2015-10-30

    Highlights: • Portland cement and lime activated persulfate by increasing pH and temperature. • Chemical oxidation achieved BTEX and PAH removal ranging from 55% to 75%. • Activating persulfate with ISS amendments reduced leachability more than NaOH. • Native sulfate-reducing bacteria degraded PAHs within weeks after ISCO finished. • ISCO, ISS, and anaerobic bioremediation were combined in a single application. - Abstract: Laboratory batch reactors were maintained for 32 weeks to test the potential for an in situ remedy that combines chemical oxidation, stabilization, and anaerobic bioremediation in a single application to treat soil from a manufactured gas plant, contaminated with polycyclic aromatic hydrocarbons (PAH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). Portland cement and slaked lime were used to activate the persulfate and to stabilize/encapsulate the contaminants that were not chemically oxidized. Native sulfate-reducing bacteria degraded residual contaminants using the sulfate left after persulfate activation. The ability of the combined remedy to reduce contaminant mass and leachability was compared with NaOH-activated persulfate, stabilization, and sulfate-reducing bioremediation as stand-alone technologies. The stabilization amendments increased pH and temperature sufficiently to activate the persulfate within 1 week. Activation with both stabilization amendments and NaOH removed between 55% and 70% of PAH and BTEX. However, combined persulfate and stabilization significantly reduced the leachability of residual BTEX and PAH compared with NaOH activation. Sulfide, 2-naphthoic acid, and the abundance of subunit A of the dissimilatory sulfite reductase gene (dsrA) were used to monitor native sulfate-reducing bacteria, which were negatively impacted by activated persulfate, but recovered completely within weeks.

  15. Improving the drug delivery characteristics of graphene oxide based polymer nanocomposites through the “one-pot” synthetic approach of single-electron-transfer living radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Peng; Liu, Meiying; Tian, Jianwen; Deng, Fengjie [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wang, Ke [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing 100084 (China); Xu, Dazhuang [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Liu, Liangji [Affiliated Hospital of Jiangxi University of Traditional Chinese Medicine, Nanchang 330006 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wei, Yen, E-mail: weiyen@tsinghua.edu.cn [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing 100084 (China)

    2016-08-15

    Graphical abstract: The PEGylated graphene oxides with high water dispersibility, good biocompatibility as well as high drug loading capability were fabricated via “one-pot” SET-LRP. - Highlights: • Surface modification of graphene oxide with polymers. • One-pot single-electron-transfer living radical polymerization. • Improving drug delivery characteristics. • The synthetic approach is rather simple, universal and effective. - Abstract: Graphene oxide (GO) based polymer nanocomposites have attracted extensive research interest recently for their outstanding physicochemical properties and potential applications. However, surface modification of GO with synthetic polymers has demonstrated to be trouble for most polymerization procedures are occurred under non-aqueous solution, which will in turn lead to the restacking of GO. In this work, a facile and efficient “one-pot” strategy has been developed for surface modification of GO with synthetic polymers through single-electron-transfer living radical polymerization (SET-LRP). The GO based polymer nanocomposites were obtained via SET-LRP in aqueous solution using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as the monomer and 11-bromoundecanoic acid as the initiator, which could be effectively adsorbed on GO through hydrophobic interaction. The successful preparation of GO based polymer nanocomposites was confirmed by a series of characterization techniques such as {sup 1}H nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. The resultant products exhibit high water disperisibility, excellent biocompatibility and high efficient drug loading capability, making these PEGylated GO nanocomposites promising candidates for biomedical applications.

  16. Comparative hazard identification by a single dose lung exposure of zinc oxide and silver nanomaterials in mice

    DEFF Research Database (Denmark)

    Gosens, Ilse; Kermanizadeh, Ali; Jacobsen, Nicklas Raun

    2015-01-01

    O) and a triethoxycaprylylsilane functionalised ZnO NM suspended in water with 2% mouse serum were examined 24 hours following a single intratracheal instillation (I.T.). An acute pulmonary inflammation was noted (marked by a polymorphonuclear neutrophil influx) with cell damage (LDH and total protein) in broncho-alveolar lavage...

  17. Expression and purification of single cysteine-containing mutant variants of the mouse prion protein by oxidative refolding.

    Science.gov (United States)

    Sengupta, Ishita; Udgaonkar, Jayant B

    2017-12-01

    The folding and aggregation of proteins has been studied extensively, using multiple probes. To facilitate such experiments, introduction of spectroscopically-active moieties in to the protein of interest is often necessary. This is commonly achieved by specifically labelling cysteine residues in the protein, which are either present naturally or introduced artificially by site-directed mutagenesis. In the case of the recombinant prion protein, which is normally expressed in inclusion bodies, the presence of the native disulfide bond complicates the correct refolding of single cysteine-containing mutant variants of the protein. To overcome this major bottleneck, a simple purification strategy for single tryptophan, single cysteine-containing mutant variants of the mouse prion protein is presented, with yields comparable to that of the wild type protein. The protein(s) obtained by this method are correctly folded, with a single reduced cysteine, and the native disulfide bond between residues C178 and C213 intact. The β-sheet rich oligomers formed from these mutant variant protein(s) are identical to the wild type protein oligomer. The current strategy facilitates sample preparation for a number of high resolution spectroscopic measurements for the prion protein, which specifically require thiol labelling. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Low-temperature positron lifetime and Doppler-broadening measurements for single-crystal nickel oxide containing cation vacancies

    International Nuclear Information System (INIS)

    Waber, J.T.; Snead, C.L. Jr.; Lynn, K.G.

    1985-01-01

    Lifetime and Doppler-broadening measurements for positron annihilation in substoichiometric nickelous oxide have been made concomitantly from liquid-helium to room temperature. The concentration of cation vacancies is readily controlled by altering the ambient oxygen pressure while annealing the crystals at 1673 0 K. It was found that neither of the three lifetimes observed or their relative intensities varied significantly with the oxygen pressure, and the bulk rate only increased slightly when the specimen was cooled from room to liquid-helium temperatures. These results are interpreted as indicating that some of the positrons are trapped by the existing cation vacancies and a smaller fraction by vacancy clusters

  19. A new strategy for the synthesis of iron-oxide nanocrystals by using a single-spinneret electrospinning technique.

    Science.gov (United States)

    Xu, Guo-Rong; Wang, Jiao-Na; Li, Cong-Ju

    2013-10-01

    Iron-oxide nanocrystals (IONCs) have been widely researched, owing to their unique physical and chemical properties. Herein, a new strategy that involves an electrospinning technique with the addition of a surfactant is reported as an effective method for the fabrication of shaped IONCs. With the same precursor compositions, only iron-oxide nanoparticles were obtained by using a sol-gel method without electrospinning. However, when the electrospinning technique was introduced, IONCs with special geometrical shapes (e.g., octahedral) were obtained. Characterization data indicated that the IONCs were composed of magnetite (Fe3O4) and maghemite (γ-Fe2O3), the ratio of which could be tuned by changing the concentration of the surfactants in the precursor solutions. A mechanism for the formation of IONCs is also proposed. The effect of surfactant on the decomposition of the iron complex is the main motivation for the formation of IONCs. In the sol-gel method without electrospinning, this effect is completely inhibited by the disturbance of long molecular chains. However, in the electrospinning strategy, such disturbance can be completely or partially diminished by the electrical force field during the electrospinning process and by the spatial effect of the nanofibers, thus leading to the formation of IONCs. Finally, the magnetic properties of the obtained IONCs were investigated. This strategy is versatile and environmentally friendly and it will be applicable to the synthesis of many other functional inorganic materials. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Isothermal and cyclic oxidation resistance of pack siliconized Mo–Si–B alloy

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, Sanjib, E-mail: sanjib@barc.gov.in

    2017-08-31

    Highlights: • Pack-siliconizing of Mo–Si–B alloy improves its oxidation resistance at 750, 900 and 1400 °C. • A marginal weight change of the coated alloy is detected in isothermal and cyclic oxidation tests. • Kinetics of growth of protective SiO{sub 2} scale is much faster at 1400 °C. • Self-healing SiO{sub 2} is developed at the cracks formed in MoSi{sub 2} layer during cyclic oxidation tests. - Abstract: Oxidation behaviour of MoSi{sub 2} coated Mo–9Si–8B–0.75Y (at.%) alloy has been investigated at three critical temperatures including 750, 900 and 1400 °C in static air. Thermogravimetric analysis (TGA) data indicates a remarkable improvement in the oxidation resistance of the silicide coated alloy in both isothermal and cyclic oxidation tests. The cross-sectional scanning electron microscopy and energy dispersive spectroscopic analysis reveal the occurrence of internal oxidation particularly at the crack fronts formed in the outer MoSi{sub 2} layer during thermal cycling. The dominant oxidation mechanisms at 750–900 °C and 1400 °C are identified. Development of MoB inner layer further improves the oxidation resistance of the silicide coated alloy.

  1. Activation and control of visible single defects in 4H-, 6H-, and 3C-SiC by oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Lohrmann, A.; Klein, J. R.; Prawer, S.; McCallum, J. C. [School of Physics, The University of Melbourne, Victoria 3010 (Australia); Castelletto, S. [School of Engineering, RMIT University, Melbourne, Victoria 3001 (Australia); Ohshima, T. [SemiConductor Analysis and Radiation Effects Group, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Bosi, M.; Negri, M. [IMEM-CNR Institute, Parco Area delle Scienze 37/A, 43124 Parma (Italy); Lau, D. W. M.; Gibson, B. C. [ARC Centre of Excellence for Nanoscale BioPhotonics, School of Science, RMIT University, Melbourne, Victoria 3001 (Australia); Johnson, B. C. [ARC Centre of Excellence for Quantum Computing and Communication Technology, School of Physics, University of Melbourne, Victoria 3010 (Australia)

    2016-01-11

    In this work, we present the creation and characterisation of single photon emitters at the surface of 4H- and 6H-SiC, and of 3C-SiC epitaxially grown on silicon. These emitters can be created by annealing in an oxygen atmosphere at temperatures above 550 °C. By using standard confocal microscopy techniques, we find characteristic spectral signatures in the visible region. The excited state lifetimes are found to be in the nanosecond regime in all three polytypes, and the emission dipoles are aligned with the lattice. HF-etching is shown to effectively annihilate the defects and to restore an optically clean surface. The defects described in this work have ideal characteristics for broadband single photon generation in the visible spectral region at room temperature and for integration into nanophotonic devices.

  2. Electric and magnetic properties of titanium-cobalt-oxide single crystals produced by floating zone melting with light heating

    Science.gov (United States)

    Balbashov, A. M.; Mukhin, A. A.; Ivanov, V. Yu.; Iskhakova, L. D.; Voronchikhina, M. E.

    2017-08-01

    Single crystals of spinel Co2TiO4, CoTiO3 of ilmenite structure and pseudobrookite CoTi2O5 were grown by means of zone melting equipment URN-2-ZM. The growth processes were performed in an air atmosphere with a speed ˜10 mm/h and a final annealing of the crystal at temperature of 1250 °C. Co2TiO4 and CoTi2O5 crystals were obtained with a diameter of 12-15 mm and length up to 60 mm, being free of any other phase inclusions and cracks. However, in the CoTiO3 crystals some controversial features were found: x-ray Laue analysis indicated high-structure perfection while an electronic microscopy revealed small amount of second phase inclusions in contradiction to known phase diagram of this system. Electrical and magnetic properties of grown Co2TiO4 and CoTiO3 single crystals were studied. Semiconducting behavior of the Co2TiO4 was established with the energy gap of ˜1.3 eV. No magnetic anisotropy was found in the cubic Co2TiO4 single crystals showing a magnetic behavior similar to polycrystals. The rhombohedral CoTiO3 crystals revealed a magnetic behavior of an easy plane antiferromagnet with a significant anisotropy of the transverse magnetic susceptibilities along and perpendicular to the trigonal c axis.

  3. Source identification of nitrous oxide emission pathways from a single-stage nitritation-anammox granular reactor

    KAUST Repository

    Ali, Muhammad

    2016-06-16

    Nitrous oxide (N2O) production pathway in a signal-stage nitritation-anammox sequencing batch reactor (SBR) was investigated based on a multilateral approach including real-time N2O monitoring, N2O isotopic composition analysis, and in-situ analyses of spatial distribution of N2O production rate and microbial populations in granular biomass. N2O emission rate was high in the initial phase of the operation cycle and gradually decreased with decreasing NH4+ concentration. The average emission of N2O was 0.98 ± 0.42% and 1.35 ± 0.72% of the incoming nitrogen load and removed nitrogen, respectively. The N2O isotopic composition analysis revealed that N2O was produced via NH2OH oxidation and NO2− reduction pathways equally, although there is an unknown influence from N2O reduction and/or anammox N2O production. However, the N2O isotopomer analysis could not discriminate the relative contribution of nitrifier denitrification and heterotrophic denitrification in the NO2− reduction pathway. Various in-situ techniques (e.g. microsensor measurements and FISH (fluorescent in-situ hybridization) analysis) were therefore applied to further identify N2O producers. Microsensor measurements revealed that approximately 70% of N2O was produced in the oxic surface zone, where nitrifiers were predominantly localized. Thus, NH2OH oxidation and NO2 reduction by nitrifiers (nitrifier-denitrification) could be responsible for the N2O production in the oxic zone. The rest of N2O (ca. 30%) was produced in the anammox bacteria-dominated anoxic zone, probably suggesting that NO2− reduction by coexisting putative heterotrophic denitrifiers and some other unknown pathway(s) including the possibility of anammox process account for the anaerobic N2O production. Further study is required to identify the anaerobic N2O production pathways. Our multilateral approach can be useful to quantitatively examine the relative contributions of N2O production pathways. Good understanding of the key N2O

  4. Performance of a solid oxide fuel cell CHP system coupled with a hot water storage tank for single household

    DEFF Research Database (Denmark)

    Liso, Vincenzo; Zhao, Yingru; Yang, Wenyuan

    2014-01-01

    of heat used for thermal loads of the residence. Two fuels are considered, namely syngas and natural gas. The tank model considers the temperature gradients over the tank height. The results of the numerical simulation is used to size the SOFC system and storage heat tank to provide energy for a small...... of delivering hot water for the household and returning the coldest fluid back to SOFC heat recovery heat-exchanger. A model of the SOFC system is developed to determine the energy required to meet the hourly average electric load of the residence. The model evaluates the amount of heat generated and the amount......In this paper a solid oxide fuel cell (SOFC) system for cogeneration of heat and power integrated with a stratified heat storage tank is studied. Thermal stratification in the tank increases the heat recovery performance as it allows existence of a temperature gradient with the benefit...

  5. Aerobic Oxidation of Cyclohexane on Catalysts Based on Twinned and Single-Crystal Au75Pd25 Bimetallic Nanocrystals.

    Science.gov (United States)

    Wang, Liangbing; Zhao, Songtao; Liu, Chenxuan; Li, Chen; Li, Xu; Li, Hongliang; Wang, Youcheng; Ma, Chao; Li, Zhenyu; Zeng, Jie

    2015-05-13

    Bimetallic Au75Pd25 nanocrystals with shapes of icosahedron and octahedron were synthesized by adding different amounts of iodide ions, and were employed as catalysts for solvent-free aerobic oxidation of cyclohexane. Although both icosahedrons and octahedrons were bounded by {111} facets, the turnover frequency number of Au75Pd25 icosahedrons reached 15,106 h(-1), almost three times as high as that of Au75Pd25 octahedrons. The conversion of cyclohexane reached 28.1% after 48 h using Au75Pd25 icosahedrons, with the selectivity of 84.3% to cyclohexanone. Density functional theory calculations along with X-ray photoelectron spectroscopy examinations reveal that the excellent catalytic performance of AuPd icosahedrons could be ascribed to twin-induced strain and highly negative charge density of Au atoms on the surface.

  6. Analysis of oxidative stress-related markers in critically ill polytrauma patients: An observational prospective single-center study

    Directory of Open Access Journals (Sweden)

    Mihai Sandesc

    2018-01-01

    Full Text Available Critically ill polytrauma patients have increased production of free radicals (FRs and consequent alterations in biochemical pathways, as well as disruption of cellular integrity, due to increased lipid peroxidation. The aim of this study was to investigate several biomarkers associated with increased oxidative stress in critically ill polytrauma patients, and to evaluate the effect of antioxidant treatment on the clinical outcome in these patients. A total of 67 polytrauma patients from an intensive care unit met the selection criteria. Antiox group included 35/67 patients who received antioxidant therapy, while 32/67 patients without antioxidant treatment were considered as control group. Antioxidant therapy consisted of simultaneous administration of Vitamin C (sodium ascorbate and N-acetylcysteine, through continuous intravenous infusion. Clinical and paraclinical evaluation of the patients was performed daily until discharge or death. At admission, laboratory parameters did not differ significantly between two groups. At discharge/upon death, statistically significant differences in favor of Antiox group were observed in the following parameters: thrombocytes, activated partial thromboplastin time, prothrombin time, total bilirubin, total cholesterol, high-density lipoproteins, low-density lipoproteins, erythrocyte sedimentation rate, interleukin 6 (all p = 0.0001, total protein (p = 0.0005, serum albumin (p = 0.0004, lactate dehydrogenase (p = 0.0006, and C-reactive protein (p = 0.0014. Starting from day 5, the APACHE II score was significantly decreased in Antiox versus control group (p < 0.05. Finally, the sepsis incidence and mortality rate were significantly lower in Antiox group (p < 0.05. Decreasing the level of oxidative stress by antioxidant substances significantly correlated with a better prognosis and outcome in our patients. Further studies should elucidate more clearly the mechanism of action of antioxidants in critically ill

  7. Graphene oxide as a multi-functional p-dopant of transparent single-walled carbon nanotube films for optoelectronic devices

    Science.gov (United States)

    Han, Joong Tark; Kim, Jun Suk; Jo, Sae Byeok; Kim, Sung Hun; Kim, Jong Soo; Kang, Boseok; Jeong, Hee Jin; Jeong, Seung Yol; Lee, Geon-Woong; Cho, Kilwon

    2012-11-01

    Modulation of electronic structures and surface properties of transparent carbon nanotube films is a challenging issue for their application in optoelectronic devices. Here, we report, for the first time, that graphene oxide (GO) nanosheets play the role of a p-doping agent and surface energy modifier of single-walled carbon nanotube (SWCNT)-based transparent conducting electrodes (TCEs). The deposition of highly oxidized, small-sized (i.e., diameter of less than 500 nm) GO nanosheets onto a SWCNT network film reduces the sheet resistance of the pristine film to 60% of its original value by p-doping. The modified TCEs exhibit an outstanding optoelectronic feature of high conductivity with high transparency. Moreover, the wettability of the electrode surface was also noticeably increased, which is advantageous for the solution-based processing of organic electronics. Furthermore, the organic photovoltaic (OPV) cells with the GO-doped SWCNT anodes on flexible substrates were successfully demonstrated. In stark contrast to a power conversion efficiency of 0.44% for pristine SWCNT anodes, GO-doped SWCNT anodes show a drastically enhanced power conversion efficiency of 2.7%.Modulation of electronic structures and surface properties of transparent carbon nanotube films is a challenging issue for their application in optoelectronic devices. Here, we report, for the first time, that graphene oxide (GO) nanosheets play the role of a p-doping agent and surface energy modifier of single-walled carbon nanotube (SWCNT)-based transparent conducting electrodes (TCEs). The deposition of highly oxidized, small-sized (i.e., diameter of less than 500 nm) GO nanosheets onto a SWCNT network film reduces the sheet resistance of the pristine film to 60% of its original value by p-doping. The modified TCEs exhibit an outstanding optoelectronic feature of high conductivity with high transparency. Moreover, the wettability of the electrode surface was also noticeably increased, which is

  8. Single-ion triblock copolymer electrolytes based on poly(ethylene oxide) and methacrylic sulfonamide blocks for lithium metal batteries

    Science.gov (United States)

    Porcarelli, Luca; Aboudzadeh, M. Ali; Rubatat, Laurent; Nair, Jijeesh R.; Shaplov, Alexander S.; Gerbaldi, Claudio; Mecerreyes, David

    2017-10-01

    Single-ion conducting polymer electrolytes represent the ideal solution to reduce concentration polarization in lithium metal batteries (LMBs). This paper reports on the synthesis and characterization of single-ion ABA triblock copolymer electrolytes comprising PEO and poly(lithium 1-[3-(methacryloyloxy)propylsulfonyl]-1-(trifluoromethylsulfonyl)imide) blocks, poly(LiMTFSI). Block copolymers are prepared by reversible addition-fragmentation chain transfer polymerization, showing low glass transition temperature (-55 to 7 °C) and degree of crystallinity (51-0%). Comparatively high values of ionic conductivity are obtained (up to ≈ 10-4 S cm-1 at 70 °C), combined with a lithium-ion transference number close to unity (tLi+ ≈ 0.91) and a 4 V electrochemical stability window. In addition to these promising features, solid polymer electrolytes are successfully tested in lithium metal cells at 70 °C providing long lifetime up to 300 cycles, and stable charge/discharge cycling at C/2 (≈100 mAh g-1).

  9. Alternative perovskite materials as a cathode component for intermediate temperature single-chamber solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Gaudillere, Cyril; Olivier, Louis; Vernoux, Philippe; Farrusseng, David [Universite Lyon 1, CNRS, UMR 5256, IRCELYON, Institut de recherches sur la catalyse et l' environnement de Lyon, 2 avenue Albert Einstein, F-69626 Villeurbanne (France); Zhang, Chunming; Shao, Zongping [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, No 5 Xin Mofan Road, Nanjing 210009 (China)

    2010-08-01

    This paper exploits the suitability of three perovskite materials Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSCF), GdBaCo{sub 2}O{sub 5+{delta}} (GBC) and Ba{sub 0.5}Sr{sub 0.5}Mn{sub 0.7}Fe{sub 0.3}O{sub 3-{delta}} (BSMF) as SOFC cathodes in the single-chamber configuration operating at the intermediate temperature range. TG analysis showed high thermal stability depending on the crystalline phases of the materials. The catalytic activity of these three materials for hydrocarbon conversion was investigated under a realistic feed, i.e. with hydrocarbon, oxygen, water and carbon dioxide. Electrochemical impedance spectroscopy of the various cathodes tested in symmetric cell configuration revealed a B-site dependence of the electrode catalytic activity for oxygen reduction. High temperature (1000 C) powder reactivity tests over a gadolinium doped-ceria (CGO) and perovskite cathode revealed excellent chemical compatibility of BSMF and CGO. Catalytic tests associated with thermal and structural characterization attest to the suitability of these materials in the single-chamber configuration. (author)

  10. Alternative perovskite materials as a cathode component for intermediate temperature single-chamber solid oxide fuel cell

    Science.gov (United States)

    Gaudillère, Cyril; Olivier, Louis; Vernoux, Philippe; Zhang, Chunming; Shao, Zongping; Farrusseng, David

    This paper exploits the suitability of three perovskite materials Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3- δ (BSCF), GdBaCo 2O 5+ δ (GBC) and Ba 0.5Sr 0.5Mn 0.7Fe 0.3O 3- δ (BSMF) as SOFC cathodes in the single-chamber configuration operating at the intermediate temperature range. TG analysis showed high thermal stability depending on the crystalline phases of the materials. The catalytic activity of these three materials for hydrocarbon conversion was investigated under a realistic feed, i.e. with hydrocarbon, oxygen, water and carbon dioxide. Electrochemical impedance spectroscopy of the various cathodes tested in symmetric cell configuration revealed a B-site dependence of the electrode catalytic activity for oxygen reduction. High temperature (1000 °C) powder reactivity tests over a gadolinium doped-ceria (CGO) and perovskite cathode revealed excellent chemical compatibility of BSMF and CGO. Catalytic tests associated with thermal and structural characterization attest to the suitability of these materials in the single-chamber configuration.

  11. Nitric oxide augments single Ca(2+) channel currents via cGMP-dependent protein kinase in Kenyon cells isolated from the mushroom body of the cricket brain.

    Science.gov (United States)

    Kosakai, Kumiko; Tsujiuchi, Yuuki; Yoshino, Masami

    2015-07-01

    Behavioral and pharmacological studies in insects have suggested that the nitric oxide (NO)/cyclic GMP (cGMP) signaling pathway is involved in the formation of long-term memory (LTM) associated with olfactory learning. However, the target molecules of NO and the downstream signaling pathway are still not known. In this study, we investigated the action of NO on single voltage-dependent Ca(2+) channels in the intrinsic neurons known as Kenyon cells within the mushroom body of the cricket brain, using the cell-attached configuration of the patch-clamp technique. Application of the NO donor S-nitrosoglutathione (GSNO) increased the open probability (NPO) of single Ca(2+) channel currents. This GSNO-induced increase was blocked by ODQ, a soluble guanylate cyclase (sGC) inhibitor, suggesting that the NO generated by GSNO acts via sGC to raise cGMP levels. The membrane-permeable cGMP analog 8-Bro-cGMP also increased the NPO of single Ca(2+) channel currents. Pretreatment of cells with KT5823, a protein kinase G blocker, abolished the excitatory effect of GSNO. These results suggest that NO augments the activity of single Ca(2+) channels via the cGMP/PKG signaling pathway. To gain insight into the physiological role of NO, we examined the effect of GSNO on action potentials of Kenyon cells under current-clamp conditions. Application of GSNO increased the frequency of action potentials elicited by depolarizing current injections, indicating that NO acts as a modulator resulting in a stimulatory signal in Kenyon cells. We discuss the increased Ca(2+) influx through these Ca(2+) channels via the NO/cGMP signaling cascade in relation to the formation of olfactory LTM. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Practical limitations of single particle ICP-MS in the determination of nanoparticle size distributions and dissolution: case of rare earth oxides.

    Science.gov (United States)

    Fréchette-Viens, Laurie; Hadioui, Madjid; Wilkinson, Kevin J

    2017-01-15

    The applicability of single particle ICP-MS (SP-ICP-MS) for the analysis of nanoparticle size distributions and the determination of particle numbers was evaluated using the rare earth oxide, La 2 O 3 , as a model particle. The composition of the storage containers, as well as the ICP-MS sample introduction system were found to significantly impact SP-ICP-MS analysis. While La 2 O 3 nanoparticles (La 2 O 3 NP) did not appear to interact strongly with sample containers, adsorptive losses of La 3+ (over 24h) were substantial (>72%) for fluorinated ethylene propylene bottles as opposed to polypropylene (ICP-MS may nonetheless be appropriate for NP analysis in environmental matrices. Coupling of an ion-exchange resin to the SP-ICP-MS led to more accurate determinations of the La 2 O 3 NP size distributions. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Potential oscillations and S-shaped polarization curve in the continuous electro-oxidation of CO on platinum single-crystal electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Koper, Marc T.M.; Schmidt, Thomas J.; Markovic, Nenad M.; Ross, Philip N.

    2001-03-01

    The occurrence of an S-shaped polarization curve in a simple model for the continuous electrochemical oxidation of CO on a platinum electrode is discussed. In the model, the S-shaped polarization curve is caused by the competitive Langmuir-Hinshelwood mechanism between surface-bonded CO and OH. The reaction is studied experimentally on single-crystal platinum rotating disk electrodes in perchloric and sulfuric acid solution, and it is shown that the voltammetry is in good agreement with the model predictions. When studied under current-controlled conditions, a fast galvanodynamic scan indeed suggests the existence of the S-shaped polarization curve. At lower scan rates, however, irregularities and small-amplitude irregular fluctuations or oscillations in potential are observed. Very regular potential oscillations under current-controlled conditions are observed only on Pt(111) in sulfuric acid. The possible origin of these irregularities and oscillations is discussed in relation to the existing theories of electrochemical instabilities.

  14. Metal-organic chemical vapour deposition of lithium manganese oxide thin films via single solid source precursor

    Directory of Open Access Journals (Sweden)

    Oyedotun K.O.

    2015-12-01

    Full Text Available Lithium manganese oxide thin films were deposited on sodalime glass substrates by metal organic chemical vapour deposition (MOCVD technique. The films were prepared by pyrolysis of lithium manganese acetylacetonate precursor at a temperature of 420 °C with a flow rate of 2.5 dm3/min for two-hour deposition period. Rutherford backscattering spectroscopy (RBS, UV-Vis spectrophotometry, X-ray diffraction (XRD spectroscopy, atomic force microscopy (AFM and van der Pauw four point probe method were used for characterizations of the film samples. RBS studies of the films revealed fair thickness of 1112.311 (1015 atoms/cm2 and effective stoichiometric relationship of Li0.47Mn0.27O0.26. The films exhibited relatively high transmission (50 % T in the visible and NIR range, with the bandgap energy of 2.55 eV. Broad and diffused X-ray diffraction patterns obtained showed that the film was amorphous in nature, while microstructural studies indicated dense and uniformly distributed layer across the substrate. Resistivity value of 4.9 Ω·cm was obtained for the thin film. Compared with Mn0.2O0.8 thin film, a significant lattice absorption edge shift was observed in the Li0.47Mn0.27O0.26 film.

  15. Single-electron regime and Pauli spin blockade in a silicon metal-oxide-semiconductor double quantum dot

    Science.gov (United States)

    Rochette, Sophie; Ten Eyck, Gregory A.; Pluym, Tammy; Lilly, Michael P.; Carroll, Malcolm S.; Pioro-Ladrière, Michel

    2015-03-01

    Silicon quantum dots are promising candidates for quantum information processing as spin qubits with long coherence time. We present electrical transport measurements on a silicon metal-oxide-semiconductor (MOS) double quantum dot (DQD). First, Coulomb diamonds measurements demonstrate the one-electron regime at a relatively high temperature of 1.5 K. Then, the 8 mK stability diagram shows Pauli spin blockade with a large singlet-triplet separation of approximatively 0.40 meV, pointing towards a strong lifting of the valley degeneracy. Finally, numerical simulations indicate that by integrating a micro-magnet to those devices, we could achieve fast spin rotations of the order of 30 ns. Those results are part of the recent body of work demonstrating the potential of Si MOS DQD as reliable and long-lived spin qubits that could be ultimately integrated into modern electronic facilities. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  16. Optimal design of solid oxide fuel cell, ammonia-water single effect absorption cycle and Rankine steam cycle hybrid system

    Science.gov (United States)

    Mehrpooya, Mehdi; Dehghani, Hossein; Ali Moosavian, S. M.

    2016-02-01

    A combined system containing solid oxide fuel cell-gas turbine power plant, Rankine steam cycle and ammonia-water absorption refrigeration system is introduced and analyzed. In this process, power, heat and cooling are produced. Energy and exergy analyses along with the economic factors are used to distinguish optimum operating point of the system. The developed electrochemical model of the fuel cell is validated with experimental results. Thermodynamic package and main parameters of the absorption refrigeration system are validated. The power output of the system is 500 kW. An optimization problem is defined in order to finding the optimal operating point. Decision variables are current density, temperature of the exhaust gases from the boiler, steam turbine pressure (high and medium), generator temperature and consumed cooling water. Results indicate that electrical efficiency of the combined system is 62.4% (LHV). Produced refrigeration (at -10 °C) and heat recovery are 101 kW and 22.1 kW respectively. Investment cost for the combined system (without absorption cycle) is about 2917 kW-1.

  17. In situ observation of Ag-Cu-Ti liquid alloy/solid oxide interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Durov, O.V. [Frantsevich Institute for Problems of Materials Science of NASU, 3 Krzhyzhanovsky Street, Kiev 142, 03680 (Ukraine)], E-mail: avdu@ukr.net; Krasovskyy, V.P. [Frantsevich Institute for Problems of Materials Science of NASU, 3 Krzhyzhanovsky Street, Kiev 142, 03680 (Ukraine)

    2008-11-15

    In situ investigation methods are a very interesting means for understanding high-temperature interface processes. A method of direct observation of the interactions between transparent materials (Al{sub 2}O{sub 3}, SiO{sub 2}, CaF{sub 2}) and metal melts was elaborated. For the Ag-36.65 at.%Cu-8.15 at.%Ti/sapphire system, the formation of a dark compound at the interface was observed to occur at high temperature. This result does not confirm the conclusion of a neutron spectroscopy study which indicated that titanium oxides form at the interface only during solidification of the alloy. Interactions of the same alloy with SiO{sub 2} and CaF{sub 2} were also considered.

  18. Combining in situ chemical oxidation, stabilization, and anaerobic bioremediation in a single application to reduce contaminant mass and leachability in soil.

    Science.gov (United States)

    Cassidy, Daniel P; Srivastava, Vipul J; Dombrowski, Frank J; Lingle, James W

    2015-10-30

    Laboratory batch reactors were maintained for 32 weeks to test the potential for an in situ remedy that combines chemical oxidation, stabilization, and anaerobic bioremediation in a single application to treat soil from a manufactured gas plant, contaminated with polycyclic aromatic hydrocarbons (PAH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). Portland cement and slaked lime were used to activate the persulfate and to stabilize/encapsulate the contaminants that were not chemically oxidized. Native sulfate-reducing bacteria degraded residual contaminants using the sulfate left after persulfate activation. The ability of the combined remedy to reduce contaminant mass and leachability was compared with NaOH-activated persulfate, stabilization, and sulfate-reducing bioremediation as stand-alone technologies. The stabilization amendments increased pH and temperature sufficiently to activate the persulfate within 1 week. Activation with both stabilization amendments and NaOH removed between 55% and 70% of PAH and BTEX. However, combined persulfate and stabilization significantly reduced the leachability of residual BTEX and PAH compared with NaOH activation. Sulfide, 2-naphthoic acid, and the abundance of subunit A of the dissimilatory sulfite reductase gene (dsrA) were used to monitor native sulfate-reducing bacteria, which were negatively impacted by activated persulfate, but recovered completely within weeks. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. The Effect of Submaximal Exercise Preceded by Single Whole-Body Cryotherapy on the Markers of Oxidative Stress and Inflammation in Blood of Volleyball Players

    Directory of Open Access Journals (Sweden)

    Celestyna Mila-Kierzenkowska

    2013-01-01

    Full Text Available The aim of the study was to determine the effect of single whole-body cryotherapy (WBC session applied prior to submaximal exercise on the activity of antioxidant enzymes, the concentration of lipid peroxidation products, total oxidative status, and the level of cytokines in blood of volleyball players. The study group consisted of 18 male professional volleyball players, who were subjected to extremely cold air (−130∘C prior to exercise performed on cycloergometer. Blood samples were taken five times: before WBC, after WBC procedure, after exercise preceded by cryotherapy (WBC exercise, and before and after exercise without WBC (control exercise. The activity of catalase statistically significantly increased after control exercise. Moreover, the activity of catalase and superoxide dismutase was lower after WBC exercise than after control exercise (P<0.001. After WBC exercise, the level of IL-6 and IL-1β was also lower (P<0.001 than after control exercise. The obtained results may suggest that cryotherapy prior to exercise may have some antioxidant and anti-inflammatory properties. The relations between the level of studied oxidative stress and inflammatory markers may testify to the contribution of reactive oxygen species in cytokines release into the blood system in response to exercise and WBC.

  20. The Effect of Submaximal Exercise Preceded by Single Whole-Body Cryotherapy on the Markers of Oxidative Stress and Inflammation in Blood of Volleyball Players

    Science.gov (United States)

    Mila-Kierzenkowska, Celestyna; Szpinda, Michał; Augustyńska, Beata; Woźniak, Bartosz

    2013-01-01

    The aim of the study was to determine the effect of single whole-body cryotherapy (WBC) session applied prior to submaximal exercise on the activity of antioxidant enzymes, the concentration of lipid peroxidation products, total oxidative status, and the level of cytokines in blood of volleyball players. The study group consisted of 18 male professional volleyball players, who were subjected to extremely cold air (−130°C) prior to exercise performed on cycloergometer. Blood samples were taken five times: before WBC, after WBC procedure, after exercise preceded by cryotherapy (WBC exercise), and before and after exercise without WBC (control exercise). The activity of catalase statistically significantly increased after control exercise. Moreover, the activity of catalase and superoxide dismutase was lower after WBC exercise than after control exercise (P cryotherapy prior to exercise may have some antioxidant and anti-inflammatory properties. The relations between the level of studied oxidative stress and inflammatory markers may testify to the contribution of reactive oxygen species in cytokines release into the blood system in response to exercise and WBC. PMID:24489985

  1. Initialization of a methane-fueled single-chamber solid-oxide fuel cell with NiO + SDC anode and BSCF + SDC cathode

    Science.gov (United States)

    Zhang, Chunming; Zheng, Yao; Ran, Ran; Shao, Zongping; Jin, Wanqin; Xu, Nanping; Ahn, Jeongmin

    2008-05-01

    The initialization of an anode-supported single-chamber solid-oxide fuel cell, with NiO + Sm0.2Ce0.8O1.9 anode and Ba0.5Sr0.5Co0.8Fe0.2O3-δ + Sm0.2Ce0.8O1.9 cathode, was investigated. The initialization process had significant impact on the observed performance of the fuel cell. The in situ reduction of the anode by a methane-air mixture failed. Although pure methane did reduce the nickel oxide, it also resulted in severe carbon coking over the anode and serious distortion of the fuel cell. In situ initialization by hydrogen led to simultaneous reduction of both the anode and cathode; however, the cell still delivered a maximum power density of ∼350 mW cm-2, attributed to the re-formation of the BSCF phase under the methane-air atmosphere at high temperatures. The ex situ reduction method appeared to be the most promising. The activated fuel cell showed a peak power density of ∼570 mW cm-2 at a furnace temperature of 600 °C, with the main polarization resistance contributed from the electrolyte.

  2. p-wave triggered superconductivity in single-layer graphene on an electron-doped oxide superconductor.

    Science.gov (United States)

    Di Bernardo, A; Millo, O; Barbone, M; Alpern, H; Kalcheim, Y; Sassi, U; Ott, A K; De Fazio, D; Yoon, D; Amado, M; Ferrari, A C; Linder, J; Robinson, J W A

    2017-01-19

    Electron pairing in the vast majority of superconductors follows the Bardeen-Cooper-Schrieffer theory of superconductivity, which describes the condensation of electrons into pairs with antiparallel spins in a singlet state with an s-wave symmetry. Unconventional superconductivity was predicted in single-layer graphene (SLG), with the electrons pairing with a p-wave or chiral d-wave symmetry, depending on the position of the Fermi energy with respect to the Dirac point. By placing SLG on an electron-doped (non-chiral) d-wave superconductor and performing local scanning tunnelling microscopy and spectroscopy, here we show evidence for a p-wave triggered superconducting density of states in SLG. The realization of unconventional superconductivity in SLG offers an exciting new route for the development of p-wave superconductivity using two-dimensional materials with transition temperatures above 4.2 K.

  3. Ion-implanted Si-nanostructures buried in a SiO{sub 2} substrate studied with soft-x-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Williams, R.; Rubensson, J.E.; Eisebitt, S. [Forschungszentrum Juelich (Germany)] [and others

    1997-04-01

    In recent years silicon nanostructures have gained great interest because of their optical luminescence, which immediately suggests several applications, e.g., in optoelectronic devices. Nanostructures are also investigated because of the fundamental physics involved in the underlying luminescence mechanism, especially attention has been drawn to the influence of the reduced dimensions on the electronic structure. The forming of stable and well-defined nanostructured materials is one goal of cluster physics. For silicon nanostructures this goal has so far not been reached, but various indirect methods have been established, all having the problem of producing less well defined and/or unstable nanostructures. Ion implantation and subsequent annealing is a promising new technique to overcome some of these difficulties. In this experiment the authors investigate the electronic structure of ion-implanted silicon nanoparticles buried in a stabilizing SiO{sub 2} substrate. Soft X-ray emission (SXE) spectroscopy features the appropriate information depth to investigate such buried structures. SXE spectra to a good approximation map the local partial density of occupied states (LPDOS) in broad band materials like Si. The use of monochromatized synchrotron radiation (MSR) allows for selective excitation of silicon atoms in different chemical environments. Thus, the emission from Si atom sites in the buried structure can be separated from contributions from the SiO{sub 2} substrate. In this preliminary study strong size dependent effects are found, and the electronic structure of the ion-implanted nanoparticles is shown to be qualitatively different from porous silicon. The results can be interpreted in terms of quantum confinement and chemical shifts due to neighboring oxygen atoms at the interface to SiO{sub 2}.

  4. Synthesis of surface molecular imprinting polymer on SiO{sub 2}-coated CdTe quantum dots as sensor for selective detection of sulfadimidine

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Zhiping; Ying, Haiqin; Liu, Yanyan [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Xu, Wanzhen, E-mail: xwz09@ujs.edu.cn [School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013 (China); Yang, Yanfei; Luan, Yu [Zhenjiang Institute for Drug Control of Jiangsu Province, Zhenjiang 212003 (China); Lu, Yi; Liu, Tianshu [Zhenjiang Entry-Exit Inspection Quarantine Bureau, Zhenjiang 212008 (China); Yu, Shui [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Yang, Wenming, E-mail: ywm@ujs.edu.cn [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2017-05-15

    Highlights: • Surface molecular imprinting technology and SiO{sub 2}-coated CdTe QDs were combined to prepare a novel fluorescent sensor for selective detection of sulfadimidine. • The relative fluorescent intensity weakened in a linear way with the increasing concentration of sulfadimidine in the range of 10–60 μmol L{sup −1}. • The practical application of the fluorescent MIP sensor was evaluated by means of analyzing sulfadimidine in the real milk samples. The recoveries were at the range of 90.3–99.6% and the relative standard deviation ranged from 1.9 to 3.1%. - Abstract: This paper demonstrates a facile method to synthesize surface molecular imprinting polymer (MIP) on SiO{sub 2}-coated CdTe QDs for selective detection of sulfadimidine (SM{sub 2}). The fluorescent MIP sensor was prepared using cadmium telluride quantum dots (CdTe QDs) as the material of fluorescent signal readout, sulfadimidine as template molecule, 3-aminopropyltriethoxysilane (APTES) as functional monomer and tetraethyloxysilane (TEOS) as cross-linking agent. The CdTe cores were embed in the silicon shells by a sol-gel reaction and then the molecular imprinting layers were immobilized on the surface of the SiO{sub 2}-coated CdTe QDs. Under the optimized conditions, the relative fluorescent intensity weakened in a linear way with the increasing concentration of sulfadimidine in the range of 10–60 μmol L{sup −1}. The practical application of the fluorescent MIP sensor was evaluated by means of analyzing sulfadimidine in the real milk samples. The recoveries were at the range of 90.3–99.6% and the relative standard deviation (RSD) ranged from 1.9 to 3.1%, which indicates the successful synthesis of the fluorescent MIP sensor. This sensor provides an alternative solution for selective determination of sulfadimidine from real milk samples.

  5. Sol-gel synthesis of TiO{sub 2}-SiO{sub 2} photocatalyst for {beta}-naphthol photodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Qourzal, S., E-mail: samir_qourzal@yahoo.fr [Equipe de Materiaux Photocatalyse et Environnement, Departement de Chimie, Faculte des Sciences, Universite Ibn Zohr, B. P. 8106 Cite Dakhla, Agadir (Morocco); Barka, N.; Tamimi, M.; Assabbane, A. [Equipe de Materiaux Photocatalyse et Environnement, Departement de Chimie, Faculte des Sciences, Universite Ibn Zohr, B. P. 8106 Cite Dakhla, Agadir (Morocco); Nounah, A. [Ecole Superieure de Technologie, Avenue Prince Heritier Sidi Mohamed, B. P. 227, Sale-Medina (Morocco); Ihlal, A. [Laboratoire de Physique des Semi-conducteurs et Energie Solaire, Departement de Physique, Faculte, des Sciences, Universite Ibn Zohr, B. P. 8106 Cite Dakhla, Agadir (Morocco); Ait-Ichou, Y. [Equipe de Materiaux Photocatalyse et Environnement, Departement de Chimie, Faculte des Sciences, Universite Ibn Zohr, B. P. 8106 Cite Dakhla, Agadir (Morocco)

    2009-06-01

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

  6. GaAs radiovoltaic cell enhanced by Y{sub 2}SiO{sub 5} crystal for the development of new gamma microbatteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zheng-Rong [Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, 29 General Road, Jiangning District, Nanjing 211106 (China); Tang, Xiao-Bin, E-mail: tangxiaobin@nuaa.edu.cn [Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, 29 General Road, Jiangning District, Nanjing 211106 (China); Jiangsu Key Laboratory of Material and Technology for Energy Conversion, Nanjing 211106 (China); Liu, Yun-Peng [Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, 29 General Road, Jiangning District, Nanjing 211106 (China); Jiangsu Key Laboratory of Material and Technology for Energy Conversion, Nanjing 211106 (China); Xu, Zhi-Heng; Yuan, Zi-Cheng; Liu, Kai; Chen, Wang [Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, 29 General Road, Jiangning District, Nanjing 211106 (China)

    2017-05-01

    Highlights: • A new gamma/GaAs multi-level structure radiovoltaic microbattery is proposed. • The properties of the new GaAs/YSO radiovoltaic cell was discussed. • The cell with Y{sub 2}SiO{sub 5} crystal can provide higher power and current output. • The irradiation resistance of Y{sub 2}SiO{sub 5} crystal under X-ray excitation was studied. - Abstract: The design of a new gamma/GaAs multi-level structure radiovoltaic microbattery enhanced by an Y{sub 2}SiO{sub 5} (YSO) crystal is proposed. By introducing the YSO crystal in the GaAs radiovoltaic cell, the output power from the cell was significantly improved. We focus on the enhancement mechanisms of performance output in one level of a multi-level structure. The radioluminescence spectra of the YSO crystal revealed its fluorescence in the wavelength range of approximately 300–700 nm. Light at the exact wavelength would normally be totally absorbed by the GaAs photovoltaic material. The radiovoltaic cells were tested using an X-ray tube to simulate the gamma rays emitted by a gamma-radioactive source. Experimental investigation showed that the YSO crystal can increase the cell output power. The output power of the new GaAs/YSO radiovoltaic cell was enhanced by more than four times compared to that of the conventional GaAs radiovoltaic cell. In addition, considering the importance of the YSO crystal in the new GaAs/YSO radiovoltaic cell, the irradiation resistance of the YSO crystal under X-ray excitation was also analysed.

  7. Effects of hollow Zn{sub 2}SiO{sub 4} particles addition on dielectric properties of isotactic polypropylene-HW composites

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Susumu [Graduate School of Science and Technology, Meijo University, Nagoya 468-8502 (Japan); Imai, Yusuke [National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560 (Japan); Kan, Akinori, E-mail: akan@mejio-u.ac.jp [Graduate School of Science and Technology, Meijo University, Nagoya 468-8502 (Japan); Hotta, Yuji [National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560 (Japan); Ogawa, Hirotaka [Graduate School of Science and Technology, Meijo University, Nagoya 468-8502 (Japan)

    2016-07-15

    Highlights: • Dielectric and thermal properties of hollow Zn{sub 2}SiO{sub 4}/iPP composites were investigated. • The lower ε{sub r} of composites is obtained by addition of hollow-structured filler. • The dielectric loss of composites is on the order of 10{sup −4} for all weight fraction. • The CTE and TCε of composites are improved by addition of HW filler. - Abstract: Hollow willemite (Zn{sub 2}SiO{sub 4}) filler particles (HW) were synthesized via a spray pyrolysis method and used to make composites with isotactic polypropylene (iPP). The dielectric constant (ε{sub r}) of iPP/HW composites exhibited slight variations with the addition of the filler having the high crystallinity, while the dielectric loss (tan δ) value decreased significantly, from 20.1 × 10{sup −4} to 1.78 × 10{sup −4}. As the weight fraction of the HW filler was increased, though the tan δ values of the composites slightly increased but these values maintained on the order of 10{sup −4} because of the highly crystalline filler. The measured ε{sub r} values of the composites were lower than those predicted by the Bruggeman model when using ε{sub f} = 6.6 (Zn{sub 2}SiO{sub 4}) and ε{sub m} = 2.4 (iPP). However, the data could be made to fit the Bruggeman model when ε{sub f} was assumed to be 4.8, suggesting that the air included in the HW filler suppressed the ε{sub r} of the composite. It was also established that the coefficients of thermal expansion and temperature coefficients of dielectric constant of the iPP/HW composites were significantly improved with increasing HW filler concentrations.

  8. Detection of zinc oxide and cerium dioxide nanoparticles during drinking water treatment by rapid single particle ICP-MS methods.

    Science.gov (United States)

    Donovan, Ariel R; Adams, Craig D; Ma, Yinfa; Stephan, Chady; Eichholz, Todd; Shi, Honglan

    2016-07-01

    Nanoparticles (NPs) entering water systems are an emerging concern as NPs are more frequently manufactured and used. Single particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) methods were validated to detect Zn- and Ce-containing NPs in surface and drinking water using a short dwell time of 0.1 ms or lower, ensuring precision in single particle detection while eliminating the need for sample preparation. Using this technique, information regarding NP size, size distribution, particle concentration, and dissolved ion concentrations was obtained simultaneously. The fates of Zn- and Ce-NPs, including those found in river water and added engineered NPs, were evaluated by simulating a typical drinking water treatment process. Lime softening, alum coagulation, powdered activated carbon sorption, and disinfection by free chlorine were simulated sequentially using river water. Lime softening removed 38-53 % of Zn-containing and ZnO NPs and >99 % of Ce-containing and CeO2 NPs. Zn-containing and ZnO NP removal increased to 61-74 % and 77-79 % after alum coagulation and disinfection, respectively. Source and drinking water samples were collected from three large drinking water treatment facilities and analyzed for Zn- and Ce-containing NPs. Each facility had these types of NPs present. In all cases, particle concentrations were reduced by a minimum of 60 % and most were reduced by >95 % from source water to finished drinking water. This study concludes that uncoated ZnO and CeO2 NPs may be effectively removed by conventional drinking water treatments including lime softening and alum coagulation.

  9. Preparation of Ag/TiO{sub 2}/SiO{sub 2} films via photo-assisted deposition and adsorptive self-assembly for catalytic bactericidal application

    Energy Technology Data Exchange (ETDEWEB)

    Xi, Baojuan, E-mail: baojuanxi@gmail.com [Department of Electrical and Computer Engineering, 10 Kent Ridge Crescent, Singapore 119260 (Singapore); Chu, Xiaona; Hu, Jiangyong [Department of Civil and Environmental Engineering, 10 Kent Ridge Crescent, Singapore 119260 (Singapore); Bhatia, Charanjit Singh; Danner, Aaron James; Yang, Hyunsoo [Department of Electrical and Computer Engineering, 10 Kent Ridge Crescent, Singapore 119260 (Singapore)

    2014-08-30

    Highlights: • We prepared controlledly the silver nanoparticles on TiO{sub 2}/SiO{sub 2} film by the facile photoreduction under the aid of structure-directing agents. • We studied the effect of silver loading on the antibactierial behavior of TiO{sub 2} film and optimized the content of silver. • We extended the route to fabricate other metals on substrates. - Abstract: The deterioration of water supply quality due to the waterborne bacteria is an environmental problem requiring the urgent attention. Due to the excellent and synergic antimicrobial capability, Ag-loaded TiO{sub 2} photocatalyst emerges as a feasible measure to guard the water. In our work, Ag nanoparticles have been prepared by the photoassisted reduction of AgNO{sub 3} on the TiO{sub 2} film fabricated by solution-based adsorptive self-assembly approach. The role of surfactant on the growth rate and size controlling of particles is also studied. In this connection, different kinds of surfactants, such as PVP, Tween-20, Tween-40 and so on, are applied in the system to investigate the formation of Ag nanoparticles. The surface profile and elemental analysis of Ag/TiO{sub 2}/SiO{sub 2} films are examined by scanning electron microscopy and attached energy-dispersive X-ray spectroscopy, respectively. In the anti-bacteria detection, Ag nanoparticles are found to enhance the bactericidal efficiency strongly comparing with the pure TiO{sub 2} film under the same condition. In addition, by comparison with Ag/TiO{sub 2}/SiO{sub 2} film in the dark environment as the reference experiment, UV–visible light plays a vital role in the improved bactericidal behavior, demonstrating the more efficient charge separation induced by metal silver. Because of the versatility of the method, the present photoreductive route is also exploited for the synthesis of Au nanoparticles on TiO{sub 2}/SiO{sub 2} films. The corresponding photocatalytical detection results demonstrate the loading of Au nanoparticles can

  10. Mg{sub 2}SiO{sub 4}:Tb{sup 3+} nanophosphor: Auto ignition route and near UV excited photoluminescence properties for WLEDs

    Energy Technology Data Exchange (ETDEWEB)

    Naik, Ramachandra [Department of Physics, New Horizon College of Engineering, Bangalore 560103 (India); Research and Development Center, Bharathiar University, Coimbatore 641046 (India); Prashantha, S.C., E-mail: scphysics@gmail.com [Research and Development Center, Bharathiar University, Coimbatore 641046 (India); Research Center, Department of Science, East West Institute of Technology, Bangalore 560091 (India); Nagabhushana, H., E-mail: bhushanvlc@gmail.com [Prof. CNR Rao Center for Advanced Materials, Tumkur University, Tumkur 572103 (India); Nagaswarupa, H.P.; Anantharaju, K.S. [Research Center, Department of Science, East West Institute of Technology, Bangalore 560091 (India); Sharma, S.C. [Chhattisgarh Swami Vivekananda Technical University, Bhilai (CG) 493441 (India); Nagabhushana, B.M. [Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560054 (India); Premkumar, H.B. [Department of Physics, Acharya Institute of Technology, Bangalore 560107 (India); Girish, K.M. [Department of Physics, Dayanand Sagar Academy of Technology and Management, Bangalore 560082 (India)

    2014-12-25

    Graphical abstract: PL Emission and CIE diagram of Mg{sub 2}SiO{sub 4}:Tb{sup 3+} nanophosphor. - Highlights: • Mg{sub 2}SiO{sub 4}:Tb{sup 3+} - prepared by combustion technique at very low temperature (350 °C). • Characteristic emission peaks of Tb{sup 3+} ion in the range 430–650 nm are recorded. • CIE co-ordinate values located in the green region. • Present phosphor was quite useful for display applications. - Abstract: For the first time nanoparticles of Tb{sup 3+} doped (1–11 mol%) Mg{sub 2}SiO{sub 4} have been prepared using low temperature (350 °C) solution combustion technique with magnesium nitrate as precursor and oxalyl di-hydrazide (ODH) as fuel. The Powder X-ray diffraction (PXRD) patterns of the sample revealed orthorhombic structure with α-phase. The average crystallite size using Scherer’s formula, W–H plot and Size–strain plot is found to be 28 nm and the same is confirmed by Transmission electron microscopy (TEM) studies. Scanning electron microscopy (SEM) pictures show a porous structure and the crystallites were agglomerated. The effect of Tb{sup 3+} cations on luminescence characteristics of Mg{sub 2}SiO{sub 4} is studied and the results are discussed in detail. The phosphors exhibit bright green emission upon near ultra violet (NUV) 377 nm excitation. The characteristic photoluminescence emission peaks at 417, 436, 458 nm in blue region due to {sup 5}D{sub 3} → {sup 7}F{sub J} (J = 5, 4, 3) of Tb{sup 3+} ions and the emission peaks at 486, 541, 584 and 621 nm in green region corresponds to {sup 5}D{sub 4} → {sup 7}F{sub J} (J = 6, 5, 4, 3) transitions of Tb{sup 3+} ions owing to f–f transitions of Tb{sup 3+} cations in the given host lattice and are due to dipole–quadropole interactions. The CIE chromaticity co-ordinates are calculated from emission spectra and falls in green region. Therefore the present phosphor is highly useful for mercury free solid state lighting (SSL) and also for display applications.

  11. Performance improvement inpolymer-based thin film transistor using modified bottom-contact structures with etched SiO{sub 2} layers

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jeong Woo [R and D Center, Samsung Corning Precision Materials Co., Ltd, Asan (Korea, Republic of); You, Young Jun; Shim, Jae Won [Dept. of Electronics and Electrical Engineering, Dongguk University-Seoul, Seoul (Korea, Republic of)

    2017-02-15

    Polymer-based thin film transistors (TFTs) with a modified bottom-contact structure and etched SiO{sub 2} layer were developed and investigated. An increase in the field-effect mobility in the developed TFTs compared to TFTs with a normal bottom-contact structure was ascertained. A bottom-contact structure and the photolithographic processing method were used to ensure that the developed TFTs were suitable for commercial applications. Increased mobility of the modified bottom-contact structure was attributed to direct contact of the Au electrode with the active polymer layer.

  12. Effect of different oxidants on polyaniline/single walled carbon nanotubes composites synthesized via ultrasonically initiated in-situ chemical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Gull, Nafisa, E-mail: gullchemist@gmail.com [Department of Polymer Engineering and Technology, University of the Punjab, Lahore, 54590 (Pakistan); Khan, Shahzad Maqsood, E-mail: shahzadkhan81@hotmail.com [Department of Polymer Engineering and Technology, University of the Punjab, Lahore, 54590 (Pakistan); Islam, Atif; Zia, Saba; Shafiq, Muhammad; Sabir, Aneela; Munawar, Muhammad Azeem [Department of Polymer Engineering and Technology, University of the Punjab, Lahore, 54590 (Pakistan); Butt, Muhammad Taqi Zahid [College of Engineering and Emerging Technologies, University of the Punjab, Lahore, 54590 (Pakistan); Jamil, Tahir [Department of Polymer Engineering and Technology, University of the Punjab, Lahore, 54590 (Pakistan)

    2016-04-01

    This study is aimed at investigating the effect of different oxidants on properties of polyaniline/single walled carbon nanotubes (PANI/SWCNT) composites and scrutinizing a suitable oxidant to improve the properties of composites. PANI/SWCNT composites were fabricated via ultrasonically initiated in-situ chemical polymerization technique using four different oxidants; hydrogen peroxide (H{sub 2}O{sub 2}), ammonium peroxidisulphate ((NH{sub 4}){sub 2}S{sub 2}O{sub 8}), potassium dichromate (K{sub 2}Cr{sub 2}O{sub 7}) and potassium iodate (KIO{sub 3}). Percent yield (97%), molecular weight (45532 g mol{sup −1}) and electrical conductivity (0.835 S cm{sup −1}) were found maximum for composite prepared in the presence of H{sub 2}O{sub 2}. Structural confirmation of PANI and charge transfer complex formation between PANI and SWCNT were confirmed by fourier transform infrared spectroscopy, UV–visible spectroscopy and X-ray diffraction spectroscopy. Thermogravimetric analysis verified that the PANI/SWCNT composite synthesized using H{sub 2}O{sub 2} had maximum thermal stability with least thermal degradation (∼28%). Minimal thermal transitions of the composite were also observed for same composite by differential scanning calorimetry. Scanning electron microscopic images of PANI/SWCNT composites revealed that SWCNT were properly dispersed in PANI matrix when H{sub 2}O{sub 2} was used. Above results provide the valuable suggestion that; H{sub 2}O{sub 2} is a promising oxidant to enhance structural, thermal, electrical and microscopic properties of composites. - Highlights: • Ultrasonically initiated in-situ chemical polymerization protocol was devised for synthesis of PANI/SWCNT composites. • SEM micrographs of PANI/SWCNT-1 showed uniform dispersed structure. • Better thermal stability and conductivity was evidenced for H{sub 2}O{sub 2} based PANI/SWCNT composite. • π–π interaction between PANI and SWCNT is confirmed by FTIR and UV

  13. Density-functional theory study of dimethyl carbonate synthesis by methanol oxidative carbonylation on single-atom Cu1/graphene catalyst

    Science.gov (United States)

    Sun, Wei; Shi, Ruina; Wang, Xuhui; Liu, Shusen; Han, Xiaoxia; Zhao, Chaofan; Li, Zhong; Ren, Jun

    2017-12-01

    The mechanism for dimethyl carbonate (DMC) synthesis by oxidation carbonylation of methanol on a single-atom Cu1/graphene catalyst was investigated by density-functional theory calculations. Carbon vacancies in graphene can significantly enhance the interaction between Cu atoms and graphene supports, and provide an increased transfer of electrons from Cu atoms to the graphene sheet. Compared with Cu-doped divacancy graphene (Cu/DG), Cu-doped monovacancy graphene (Cu/MG) provides a stronger interaction between adsorbents and the catalyst surface. Among the reaction processes over Cu1/graphene catalysts, CO insertion into methoxide was more favorable than dimethoxide. The rate-limiting step on the Cu/DG surface is the carbomethoxide reaction with methoxide, which is exothermic by 164.6 kJ mol-1 and has an activation barrier of 190.9 kJ mol-1 energy. Compared with that on the Cu crystal surface, Cu4 and Cu3Rh clusters, and the Cu2O(111) surface, the rate-determining step for DMC formation on Cu/MG, which is CO insertion into methoxide, needs to overcome the lowest barrier of 73.5 kJ mol-1 and is exothermic by 44.6 kJ mol-1. Therefore, Cu/MG was beneficial to the formation of DMC as a single-atom catalyst.

  14. Periodic density functional theory study of structural and electronic properties of single-walled zinc oxide and carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Marana, Naiara L. [Modeling and Molecular Simulations Group, São Paulo State University, UNESP, 17033-360 Bauru, SP (Brazil); Albuquerque, Anderson R. [Federal Institute of Education, Science and Technology of Sertão Pernambucano, 56400-000 Floresta, PE (Brazil); La Porta, Felipe A. [Chemistry Department, Federal Technological University of Paraná, 86036-370 Londrina, PR (Brazil); Longo, Elson [São Paulo State University, Chemistry Institute, UNESP, 14801-907 Araraquara, SP (Brazil); Sambrano, Julio R. [Modeling and Molecular Simulations Group, São Paulo State University, UNESP, 17033-360 Bauru, SP (Brazil)

    2016-05-15

    Periodic density functional theory calculations with the B3LYP hybrid functional and all-electron Gaussian basis set were performed to simulate the structural and electronic properties as well as the strain and formation energies of single-walled ZnO nanotubes (SWZnONTs) and Carbon nanotubes (SWCNTs) with different chiralities as functions of their diameters. For all SWZnONTs, the band gap, strain energy, and formation energy converge to ~4.5 eV, 0.0 eV/atom, and 0.40 eV/atom, respectively. This result suggests that the nanotubes are formed more easily from the surface than from the bulk. For SWCNTs, the strain energy is always positive, while the formation energy is negative for armchair and zigzag nanotubes, therefore suggesting that these types of nanotubes can be preferentially formed from the bulk. The electronic properties of SWCNTs depend on the chirality; all armchair nanotubes are metallic, while zigzag and chiral nanotubes can be metallic or semiconducting, depending on the n and m vectors. - Graphical abstract: DFT/B3LYP were performed to simulate the structural and electronic properties as well as the strain and formation energies of SWZnONTs and SWCNTs with different chiralities as functions of their diameters. - Highlights: • The energies of SWZnONTs converge for chirality with diameters up 20 Å. • SWCNTs electronic properties depend on the chirality. • The properties of SWZnONTs are very similar to those of monolayer surface.

  15. Global DNA methylation and oxidative stress biomarkers in workers exposed to metal oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Liou, Saou-Hsing; Wu, Wei-Te; Liao, Hui-Yi [National Institute of Environmental Health Sciences, National Health Research Institutes, Zhunan, Miaoli County, Taiwan (China); Chen, Chao-Yu; Tsai, Cheng-Yen; Jung, Wei-Ting [Department of Chemistry, Fu Jen Catholic University, New Taipei City, Taiwan (China); Lee, Hui-Ling, E-mail: huilinglee3573@gmail.com [Department of Chemistry, Fu Jen Catholic University, New Taipei City, Taiwan (China)

    2017-06-05

    Highlights: • Global methylation and oxidative DNA damage levels in nanomaterial handling workers were assessed. • 8-isoprostane in exhaled breath condensate of workers exposed to nanoparticles was higher. • 8-OHdG was negatively correlated with global methylation. • Exposure to metal oxide nanoparticles may lead to global methylation and DNA oxidative damage. - Abstract: This is the first study to assess global methylation, oxidative DNA damage, and lipid peroxidation in workers with occupational exposure to metal oxide nanomaterials (NMs). Urinary and white blood cell (WBC) 8-hydroxydeoxyguanosine (8-OHdG), and exhaled breath condensate (EBC) 8-isoprostane were measured as oxidative stress biomarkers. WBC global methylation was measured as an epigenetic alteration. Exposure to TiO{sub 2}, SiO{sub 2,} and indium tin oxide (ITO) resulted in significantly higher oxidative biomarkers such as urinary 8-OHdG and EBC 8-isoprostane. However, significantly higher WBC 8-OHdG and lower global methylation were only observed in ITO handling workers. Significant positive correlations were noted between WBC and urinary 8-OHdG (Spearman correlation r = 0.256, p = 0.003). Furthermore, a significant negative correlation was found between WBC 8-OHdG and global methylation (r = −0.272, p = 0.002). These results suggest that exposure to metal oxide NMs may lead to global methylation, DNA oxidative damage, and lipid peroxidation.

  16. Effect of SiO{sub 2} addition on photocatalytic activity, water contact angle and mechanical stability of visible light activated TiO{sub 2} thin films applied on stainless steel by a sol gel method

    Energy Technology Data Exchange (ETDEWEB)

    Momeni, Mansour [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Saghafian, Hasan, E-mail: Saghafian@iust.ac.ir [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Center of Excellence for High Strength Alloys Technology (CEHSAT), Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Golestani-Fard, Farhad [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Center of Excellence for Advanced Materials, Iran University of Science and Technology, P.O. Box 16845-195, Tehran (Iran, Islamic Republic of); Barati, Nastaran; Khanahmadi, Amirhossein [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

    2017-01-15

    Highlights: • Adding SiO{sub 2} to N doped TiO{sub 2} films increased the band gap energy of the films. • SiO{sub 2} addition encouraged crack formation in N doped TiO{sub 2} thin films. • Addition of SiO{sub 2} weakened visible light activity and hydrophilicity of TiO{sub 2} films. • All films passed nanoscratch testing without detachment from the substrates. • Results propose using non-silica films on steel for application in visible light. - Abstract: Nanostructured N doped TiO{sub 2}/20%SiO{sub 2} thin films were developed on steel surface via sol gel method using a painting airbrush. Thin films then were calcined at various temperatures in a range of 400–600 °C. The effect of SiO{sub 2} addition on phase composition and microstructural evolution of N doped TiO{sub 2} films were studied using XRD and FESEM. Optical properties, visible light photocatalytic activity, hydrophilic behavior, and mechanical behavior of the films were also investigated by DRS, methylene blue degradation, water contact angle measurements, and nanoscratch testing. Results indicated that the band gap energy of N doped TiO{sub 2}/SiO{sub 2} was increased from 2.93 to 3.09 eV. Crack formation during calcination was also significantly promoted in the composite films. All composite films demonstrated weaker visible light photocatalytic activities and lower mechanical stability in comparison with N doped TiO{sub 2} films. Moreover, the N doped TiO{sub 2}/SiO{sub 2} film calcined at 600 °C showed undesirable hydrophilic behavior with a water contact angle of 57° after 31 h of visible light irradiation. Outcomes of the present study reveal some different results to previous reports on TiO{sub 2}/SiO{sub 2} films. In general, we believe the differences in substrate material as well as application in visible light are the main reasons for the above mentioned contradiction.

  17. Size characterization of airborne SiO{sub 2} nanoparticles with on-line and off-line measurement techniques: an interlaboratory comparison study

    Energy Technology Data Exchange (ETDEWEB)

    Motzkus, C., E-mail: charles.motzkus@lne.fr; Mace, T.; Gaie-Levrel, F.; Ducourtieux, S.; Delvallee, A. [Laboratoire National de Metrologie et d' Essais (LNE) (France); Dirscherl, K. [Danish Fundamental Metrology (DFM) (Denmark); Hodoroaba, V.-D. [BAM Federal Institute for Materials Research and Testing (Germany); Popov, I. [The Hebrew University of Jerusalem, Unit for Nanocharacterization (Israel); Popov, O.; Kuselman, I. [National Physical Laboratory of Israel (INPL) (Israel); Takahata, K.; Ehara, K. [National Institute of Advanced Industrial Science and Technology (AIST), National Metrology Institute of Japan (NMIJ) (Japan); Ausset, P.; Maille, M. [Universite Paris-Est Creteil et Universite Paris-Diderot, Laboratoire Interuniversitaire des Systemes Atmospheriques (LISA), UMR CNRS 7583 (France); Michielsen, N.; Bondiguel, S.; Gensdarmes, F. [Institut de Radioprotection et de Surete Nucleaire (IRSN), PSN-RES, SCA, LPMA (France); Morawska, L.; Johnson, G. R.; Faghihi, E. M. [Queensland University of Technology (QUT), International Laboratory for Air Quality and Health (ILAQH) (Australia); and others

    2013-10-15

    Results of an interlaboratory comparison on size characterization of SiO{sub 2} airborne nanoparticles using on-line and off-line measurement techniques are discussed. This study was performed in the framework of Technical Working Area (TWA) 34-'Properties of Nanoparticle Populations' of the Versailles Project on Advanced Materials and Standards (VAMAS) in the project no. 3 'Techniques for characterizing size distribution of airborne nanoparticles'. Two types of nano-aerosols, consisting of (1) one population of nanoparticles with a mean diameter between 30.3 and 39.0 nm and (2) two populations of non-agglomerated nanoparticles with mean diameters between, respectively, 36.2-46.6 nm and 80.2-89.8 nm, were generated for characterization measurements. Scanning mobility particle size spectrometers (SMPS) were used for on-line measurements of size distributions of the produced nano-aerosols. Transmission electron microscopy, scanning electron microscopy, and atomic force microscopy were used as off-line measurement techniques for nanoparticles characterization. Samples were deposited on appropriate supports such as grids, filters, and mica plates by electrostatic precipitation and a filtration technique using SMPS controlled generation upstream. The results of the main size distribution parameters (mean and mode diameters), obtained from several laboratories, were compared based on metrological approaches including metrological traceability, calibration, and evaluation of the measurement uncertainty. Internationally harmonized measurement procedures for airborne SiO{sub 2} nanoparticles characterization are proposed.

  18. Using compound SiO{sub 2}(62-68)-MgO+CaO(29-39) in the protections of ceramics of steel company to replace the CaO-Al{sub 2}O{sub 3}-SiO{sub 2} compound; Utilizacao do composto SiO{sub 2}(62-68)-MgO+CaO(29-39) nas protecoes ceramicas de empresa siderurgica em substituicao ao composto CaO-Al{sub 2}O{sub 3}-SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Anderson Carvalho; Silva, Paula Cipriano da; Vernilli Junior, Fernando; Santos, Claudinei dos; Magnago, Roberto de Oliveira [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Lima, Leonardo Moreira de [Universidade de Sao Paulo (USP), Lorena, SP (Brazil)

    2014-12-15

    This article describes the use of protective ceramic composed of SiO{sub 2}(62-68)-MgO + CaO(29-39) in the frontal region of the machines that inject mass refractory to stop racing pig iron and slag liquid in blast furnaces. The new protection model (prototype) showed a annual saving of approximately R$ 32,000.00 compared to the compound previously used CaO-Al{sub 2}O{sub 3}-SiO{sub 2}. Also had a lower toxicity, as it has in its morphology least amount of fiber. These fibers when inhaled cause damage to internal tissues of the lungs is harmful to health. There maintenance rates of production, since in all samples tested the new ceramic protection, the front part was preserved allowing the refractory mass injection quantity and pressure required for reconstitution of the length of the bore which removes iron and slag inside the high oven, allowing for a larger internal volume to produce more. The protection models were produced by Morganite-Brazil. The morphology and crystallographic characterization were characterized by Scanning Electron Microscopy and X-ray diffraction, respectively. (author)

  19. Electrical, photoelectrical and morphological properties of ZnO nanofiber networks grown on SiO{sub 2} and on Si nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Vega, Nadia Celeste; Comedi, David [Universidad Nacional de Tucuman (FACET/UNT), (Argentina). Facultad de Ciencias Exactas y Tecnologia. Dept. de Fisica. Lab. de Fisica del Solido; Audebert, Fernando [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Tirado, Monica, E-mail: mtirado@herrera.unt.edu.ar [Universidad Nacional de Tucuman (FACET/UNT), (Argentina). Facultad de Ciencias Exactas y Tecnologia. Dept. de Fisica. Lab. de Nanomateriales y de Propiedades Dielectricas; Rodriguez, Andres; Rodriguez, Tomas [Universidad Politecnica de Madrid (ETSIT/UPM), Madrid (Spain). Escuela Tecnica Superior de Ingenieros de Telecomucacion. Tecnologia Electronica; Hughes, Gareth M.; Grovenor, Chris R.M. [University of Oxford, Parks Road, OX (United Kingdom). Dept. of Materials

    2013-11-01

    ZnO nanofibre networks (NFNs) were grown by vapour transport method on Si-based substrates. One type of substrate was SiO{sub 2} thermally grown on Si and another consisted of a Si wafer onto which Si nanowires (NWs) had been grown having Au nanoparticles catalysts. The ZnO-NFN morphology was observed by scanning electron microscopy on samples grown at 600 Degree-Sign C and 720 Degree-Sign C substrate temperature, while an focused ion beam was used to study the ZnO NFN/Si NWs/Si and ZnO NFN/SiO{sub 2} interfaces. Photoluminescence, electrical conductance and photo conductance of ZnO-NFN was studied for the sample grown on SiO{sub 2}. The photoluminescence spectra show strong peaks due to exciton recombination and lattice defects. The ZnO-NFN presents quasi-persistent photoconductivity effects and ohmic I-V characteristics which become nonlinear and hysteretic as the applied voltage is increased. The electrical conductance as a function of temperature can be described by a modified three dimensional variable hopping model with nanometer-ranged typical hopping distances. (author)

  20. Sensitized luminescence through nanoscopic effects of ZnO encapsulated in SiO{sub 2}:Tb{sup 3+} sol gel derived phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Dhlamini, M.S., E-mail: mdhlamini@csir.co.z [National Center for Nanostructured Materials (NCNSM), CSIR (South Africa); Physics Department, University of the Free State, PO Box 339, Bloemfontein ZA9300 (South Africa); Ntwaeaborwa, O.M., E-mail: ntwaeab.sci@ufs.ac.z [Physics Department, University of the Free State, PO Box 339, Bloemfontein ZA9300 (South Africa); Swart, H.C. [Physics Department, University of the Free State, PO Box 339, Bloemfontein ZA9300 (South Africa); Ngaruiya, J.M. [Physics Department, University of the Free State, PO Box 339, Bloemfontein ZA9300 (South Africa); Department of Physics, Jomo Kenyatta Uniiversity of Agriculture and Technology, PO Box 62000, 00200 Nairobi (Kenya); Hillie, K.T. [National Center for Nanostructured Materials (NCNSM), CSIR (South Africa); Physics Department, University of the Free State, PO Box 339, Bloemfontein ZA9300 (South Africa)

    2009-12-01

    Terbium (1 mol%) doped ZnO-SiO{sub 2} binary system was prepared by a sol-gel process. Nanoscopic effects of ZnO on the photoluminescence (PL) and the cathodoluminescence (CL) properties were studied. Defects emission from ZnO nanoparticles was measured at 560 nm and the line emission from Tb{sup 3+} ions in SiO{sub 2}:Tb{sup 3+} and ZnO-SiO{sub 2}:Tb{sup 3+} with a major peak at 542 nm was measured. The PL excitation wavelength for 542 nm Tb{sup 3+} emission was measured at approx320 nm in both SiO{sub 2}:Tb{sup 3+} and ZnO-SiO{sub 2}:Tb{sup 3+}. The CL data showed quenched luminescence of the ZnO nanoparticles at 560 nm from a composite of ZnO-SiO{sub 2}:Tb{sup 3+} and a subsequent increase in 542 nm emission from the Tb{sup 3+} ions. This suggests that energy was transferred from the ZnO nanoparticles to enhance the green emission of the Tb{sup 3+} ions. The PL and CL properties of ZnO-SiO{sub 2}:Tb{sup 3+} binary system and possible mechanism for energy transfer from the ZnO nanoparticles to Tb{sup 3+} ions are discussed.

  1. Oxidation and crystallization behavior of calcium europium silicon nitride thin films during rapid thermal processing

    Energy Technology Data Exchange (ETDEWEB)

    Jong, M. de, E-mail: m.dejong-1@tudelft.nl [Faculty of Applied Science, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands); Enter, V.E. van, E-mail: vvanenter@gmail.com [Faculty of Applied Science, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands); Schuring, E.W., E-mail: schuring@ecn.nl [Energy Center of the Netherlands, Westerduinweg 3, 1755LE Petten (Netherlands); Kolk, E. van der, E-mail: e.vanderkolk@tudelft.nl [Faculty of Applied Science, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands)

    2016-03-31

    Luminescent thin films were fabricated on silicon wafers using reactive magnetron sputtering of Ca, Si and Eu in Ar/N{sub 2} atmosphere. In order to activate the luminescence, the as-deposited nitride films were heated to 1100 °C by a rapid thermal processing treatment. X-ray diffraction measurements reveal the crystal phases that form during thermal treatment. By recording scanning electron microscopy images of the surface and the cross-section of the film at different radial locations, the formation of different layers with a thickness depending on the radial position is revealed. Energy dispersive x-ray spectroscopy analysis of these cross-sections reveals the formation of an oxide top layer and a nitride bottom layer. The thickness of the top layer increases as a function of radial position on the substrate and the thickness of the bottom layer decreases accordingly. The observation of different 4f{sup 6}5d{sup 1} → 4f{sup 7} Eu{sup 2+} luminescence emission bands at different radial positions correspond to divalent Eu doped Ca{sub 3}Si{sub 2}O{sub 4}N{sub 2}, Ca{sub 2}SiO{sub 4} and CaSiO{sub 3}, which is in agreement with the phases identified by X-ray diffraction analysis. A mechanism for the observed oxidation process of the nitride films is proposed that consists of a stepwise oxidation from the as-deposited amorphous nitride state to crystalline Ca{sub 3}Si{sub 2}O{sub 4}N{sub 2}, to Ca{sub 2}SiO{sub 4} and finally CaSiO{sub 3}. The oxidation rate and final state of oxidation show a strong temperature–time dependency during anneal treatment. - Highlights: • A thin film of nitridated Ca, Si and Eu was deposited using magnetron sputtering. • Rapid thermal processing (RTP) results in Eu{sup 2+} doped Ca{sub 3}Si{sub 2}O{sub 4}N{sub 2}, Ca{sub 2}SiO{sub 4}, and CaSiO{sub 3}. • Oxidation rate differs with radial position due to a temperature gradient during RTP. • Cross-section SEM–EDX shows how the oxidation progresses in lateral direction.

  2. INVESTIGATION OF DNA REPAIR BY SISTER CHROMATID EXCHANGE (SCE) ANALYSIS AND THE ALKALINE SINGLE CELL GEL ASSAY (SCG) IN MAMMALIAN GO-LYMPHOCYTES AFTER IN VITRO EXPOSURE TO ETHYLENE OXIDE (EO)

    Science.gov (United States)

    Investigation ofDNA Repair by Sister Chromatid Exchange (SCE) Analysis and the Alkaline Single Cell Gel Assay (SCG) in Mammalian Go-Lymphocytes after In Vitro Exposure to Ethylene Oxide (EO). EO is a large volume chemical used primarily as an intermediate in manufacturing...

  3. Vibrational spectroscopy characterization of magnetron sputtered silicon oxide and silicon oxynitride films

    Energy Technology Data Exchange (ETDEWEB)

    Godinho, V., E-mail: godinho@icmse.csic.es [Instituto de Ciencia de Materiales de Sevilla-CSIC/US, Avda. Americo Vespucio no 49, 41092 Seville (Spain); Universite Libre de Bruxelles, Avenue F.D. Roosevelt 50, B 1050 Bruxelles (Belgium); Denisov, V.N.; Mavrin, B.N.; Novikova, N.N.; Vinogradov, E.A.; Yakovlev, V.A. [Institute for Spectroscopy - Russian Academy of Sciences, 142190, Troitsk, Moscow reg. (Russian Federation); Fernandez-Ramos, C. [Instituto de Ciencia de Materiales de Sevilla-CSIC/US, Avda. Americo Vespucio no 49, 41092 Seville (Spain); Institute for Prospective and Technological Studies-JRC European Commission, C/Inca Garcilaso s/n, 41092 Seville (Spain); Jimenez de Haro, M.C.; Fernandez, A. [Instituto de Ciencia de Materiales de Sevilla-CSIC/US, Avda. Americo Vespucio no 49, 41092 Seville (Spain)

    2009-10-15

    Vibrational (infrared and Raman) spectroscopy has been used to characterize SiO{sub x}N{sub y} and SiO{sub x} films prepared by magnetron sputtering on steel and silicon substrates. Interference bands in the infrared reflectivity measurements provided the film thickness and the dielectric function of the films. Vibrational modes bands were obtained both from infrared and Raman spectra providing useful information on the bonding structure and the microstructure (formation of nano-voids in some coatings) for these amorphous (or nanocrystalline) coatings. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis have also been carried out to determine the composition and texture of the films, and to correlate these data with the vibrational spectroscopy studies. The angular dependence of the reflectivity spectra provides the dispersion of vibrational and interference polaritons modes, what allows to separate these two types of bands especially in the frequency regions where overlaps/resonances occurred. Finally the attenuated total reflection Fourier transform infrared measurements have been also carried out demonstrating the feasibility and high sensitivity of the technique. Comparison of the spectra of the SiO{sub x}N{sub y} films prepared in various conditions demonstrates how films can be prepared from pure silicon oxide to silicon oxynitride with reduced oxygen content.

  4. Improving the drug delivery characteristics of graphene oxide based polymer nanocomposites through the "one-pot" synthetic approach of single-electron-transfer living radical polymerization

    Science.gov (United States)

    Gao, Peng; Liu, Meiying; Tian, Jianwen; Deng, Fengjie; Wang, Ke; Xu, Dazhuang; Liu, Liangji; Zhang, Xiaoyong; Wei, Yen

    2016-08-01

    Graphene oxide (GO) based polymer nanocomposites have attracted extensive research interest recently for their outstanding physicochemical properties and potential applications. However, surface modification of GO with synthetic polymers has demonstrated to be trouble for most polymerization procedures are occurred under non-aqueous solution, which will in turn lead to the restacking of GO. In this work, a facile and efficient ;one-pot; strategy has been developed for surface modification of GO with synthetic polymers through single-electron-transfer living radical polymerization (SET-LRP). The GO based polymer nanocomposites were obtained via SET-LRP in aqueous solution using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as the monomer and 11-bromoundecanoic acid as the initiator, which could be effectively adsorbed on GO through hydrophobic interaction. The successful preparation of GO based polymer nanocomposites was confirmed by a series of characterization techniques such as 1H nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. The resultant products exhibit high water disperisibility, excellent biocompatibility and high efficient drug loading capability, making these PEGylated GO nanocomposites promising candidates for biomedical applications.

  5. One-pot synthesis of uniform hollow cuprous oxide spheres fabricated by single-crystalline particles via a simple solvothermal route

    International Nuclear Information System (INIS)

    Li Shikuo; Li Chuanhao; Huang Fangzhi; Wang Yang; Shen Yuhua; Xie Anjian; Wu Qiong

    2011-01-01

    Uniform Cu 2 O hollow spheres fabricated by single-crystalline particles (smaller than 20 nm) are facile synthesized in ethylene glycol (EG) solution by a simple solvothermal route without using pre-fabricated templates and reductive agents. EG in this protocol is not only used as a solvent, complexing agent, and reducing agent, but also served as a structure-directing agent for the formation of hollow structure. By control of reaction conditions, such as reaction time, temperature, and the anions, the morphology and structure of the hollow spheres can be tuned. A coordination adsorption and oriented attachment and Ostwald ripening mechanism is proposed for explaining the formation process of hollow Cu 2 O spheres in EG solution; and importantly, the hollow Cu 2 O spheres exhibit an excellent property for the electro-catalytic oxidization of ascorbic acid in acetic acid buffer solution. Moreover, the hollow spherical Cu 2 O particles could be potentially applied in catalysis, sensor, and as model for fundamental research.

  6. Capacitance characteristics of metal-oxide-semiconductor capacitors with a single layer of embedded nickel nanoparticles for the application of nonvolatile memory

    International Nuclear Information System (INIS)

    Wei, Li; Ling, Xu; Wei-Ming, Zhao; Hong-Lin, Ding; Zhong-Yuan, Ma; Jun, Xu; Kun-Ji, Chen

    2010-01-01

    This paper reports that metal-oxide-semiconductor (MOS) capacitors with a single layer of Ni nanoparticles were successfully fabricated by using electron-beam evaporation and rapid thermal annealing for application to nonvolatile memory. Experimental scanning electron microscopy images showed that Ni nanoparticles of about 5 nm in diameter were clearly embedded in the SiO 2 layer on p-type Si (100). Capacitance–voltage measurements of the MOS capacitor show large flat-band voltage shifts of 1.8 V, which indicate the presence of charge storage in the nickel nanoparticles. In addition, the charge-retention characteristics of MOS capacitors with Ni nanoparticles were investigated by using capacitance–time measurements. The results showed that there was a decay of the capacitance embedded with Ni nanoparticles for an electron charge after 10 4 s. But only a slight decay of the capacitance originating from hole charging was observed. The present results indicate that this technique is promising for the efficient formation or insertion of metal nanoparticles inside MOS structures. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  7. Ultrasensitive electrochemical detection of microRNA-21 combining layered nanostructure of oxidized single-walled carbon nanotubes and nanodiamonds by hybridization chain reaction.

    Science.gov (United States)

    Liu, Lingzhi; Song, Chao; Zhang, Zhang; Yang, Juan; Zhou, Lili; Zhang, Xing; Xie, Guoming

    2015-08-15

    Measurement of microRNA (miRNA) levels in body fluids is a crucial tool for the early diagnosis and prognosis of cancers. In this study, we developed an electrochemical assay to detect miRNA-21 by fabricating the electrode with layer-by-layer assembly of oxidized single-walled carbon nanotubes and nanodiamonds. Tetrahedron-structured probes with free-standing probe on the top served as receptors to hybridize with target miRNA directly. The probes were immobilized on the deposited gold nanoparticles through a well-established strong Au-S bond. The electrochemical signal was mainly derived from an ultrasensitive pattern by combining hybridization chain reaction with DNA-functionalized AuNPs, which provided DNAzyme to catalyze H2O2 reduction. Differential pulse voltammetry was applied to record the electrochemical signals, which was increased linearly with the target miRNA-21, and the linear detection range was 10 fM to 1.0 nM. The limit of detection reached 1.95 fM (S/N=3), and the proposed biosensor exhibited good reproducibility and stability, as well as high sensitivity. Hence, this biosensor has a promising potential in clinical application. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Selective oxidations on vanadiumoxide containing amorphous mixed oxides (AMM-V) with tert.-butylhydroperoxide

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Y.; Hunnius, M.; Storck, S.; Maier, W.F. [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany)

    1998-12-31

    The catalytic oxygen transfer properties of vanadium containing zeolites and vanadium based sol-gel catalysts with hydrogen peroxides are well known. The severe problem of vanadium leaching caused by the presence of the by-product water has been addressed. To avoid any interference with homogeneously catalyzed reactions, our study focusses on selective oxidations in a moisture-free medium with tert.-butylhydroperoxide. We have investigated the catalytic properties of amorphous microporous materials based on SiO{sub 2}, TiO{sub 2}, ZrO{sub 2} and Al{sub 2}O{sub 3} as matrix material and studied the effects of surface polarity on the oxidation of 1-octene and cyclohexane. (orig.)

  9. Influence of promoters and oxidants on propane dehydrogenation over chromium-oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.L.; Agafonov, Yu.A.; Shaporeva, N.Yu.; Trushin, D.V.; Gaidai, N.A.; Nekrasov, N.V. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Inst. of Organic Chemistry

    2010-12-30

    Possibilities for increasing the efficiency of supported on SiO{sub 2} chromium-oxide catalysts in propane oxidative dehydrogenation in CO{sub 2} presence are investigated: the introduction of Li, Na, K, Ca in catalysts and the addition of O{sub 2} in the reaction mixture. It was been found that the positive role of K - the increase of the selectivity to propene and stability of catalysts at long-duration tests - appeared at the relation of Cr:K=20. It was shown that the presence of little amount of O{sub 2} (2%) in the reaction mixtures of propane and carbon dioxide resulted in the increase of propene yield and catalyst stability. (orig.)

  10. Electrical and Optical Characterization of Sputtered Silicon Dioxide, Indium Tin Oxide, and Silicon Dioxide/Indium Tin Oxide Antireflection Coating on Single-Junction GaAs Solar Cells

    Directory of Open Access Journals (Sweden)

    Wen-Jeng Ho

    2017-06-01

    Full Text Available This study characterized the electrical and optical properties of single-junction GaAs solar cells coated with antireflective layers of silicon dioxide (SiO2, indium tin oxide (ITO, and a hybrid layer of SiO2/ITO applied using Radio frequency (RF sputtering. The conductivity and transparency of the ITO film were characterized prior to application on GaAs cells. Reverse saturation-current and ideality factor were used to evaluate the passivation performance of the various coatings on GaAs solar cells. Optical reflectance and external quantum efficiency response were used to evaluate the antireflective performance of the coatings. Photovoltaic current-voltage measurements were used to confirm the efficiency enhancement obtained by the presence of the anti-reflective coatings. The conversion efficiency of the GaAs cells with an ITO antireflective coating (23.52% exceeded that of cells with a SiO2 antireflective coating (21.92%. Due to lower series resistance and higher short-circuit current-density, the carrier collection of the GaAs cell with ITO coating exceeded that of the cell with a SiO2/ITO coating.

  11. Synthesize and characterization of a novel anticorrosive cobalt ferrite nanoparticles dispersed in silica matrix (CoFe{sub 2}O{sub 4}-SiO{sub 2}) to improve the corrosion protection performance of epoxy coating

    Energy Technology Data Exchange (ETDEWEB)

    Gharagozlou, M., E-mail: Gharagozlou@icrc.ac.ir [Department of Nanomaterials and Nanocoatings, Institute for Color Science and Technology, P.O. Box 16765-654, Tehran (Iran, Islamic Republic of); Ramezanzadeh, B., E-mail: Rramezanzadeh-bh@icrc.ac.ir [Department of Surface Coatings and Corrosion, Institute for Color Science and Technology (ICST), PO 16765-654, Tehran (Iran, Islamic Republic of); Baradaran, Z. [Department of Nanomaterials and Nanocoatings, Institute for Color Science and Technology, P.O. Box 16765-654, Tehran (Iran, Islamic Republic of)

    2016-07-30

    Highlights: • An anticorrosive cobalt ferrite nanopigment dispersed in silica matrix was synthesized. • The nanopigment showed proper inhibition performance in solution study. • The nanopigment significantly improved the corrosion resistance of the epoxy coating. - Abstract: This study aimed at studying the effect of an anticorrosive nickel ferrite nanoparticle dispersed in silica matrix (NiFe{sub 2}O{sub 4}-SiO{sub 2}) on the corrosion protection properties of steel substrate. NiFe{sub 2}O{sub 4} and NiFe{sub 2}O{sub 4}-SiO{sub 2} nanopigments were synthesized and then characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscope (TEM). Then, 1 wt.% of nanopigments was dispersed in an epoxy coating and the resultant nanocomposites were applied on the steel substrates. The corrosion inhibition effects of nanopigments were tested by an electrochemical impedance spectroscopy (EIS) and salt spray test. Results revealed that dispersing nickel ferrite nanoparticles in a silica matrix (NiFe{sub 2}O{sub 4}-SiO{sub 2}) resulted in the enhancement of the nanopigment dispersion in the epoxy coating matrix. Inclusion of 1 wt.% of NiFe{sub 2}O{sub 4}-SiO{sub 2} nanopigment into the epoxy coating enhanced its corrosion protection properties before and after scratching.

  12. Electrical evaluation of crack generation in SiN{sub x} and SiO{sub x}N{sub y} thin-film encapsulation layers for OLED displays

    Energy Technology Data Exchange (ETDEWEB)

    Park, Eun Kil [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Display Research Center, Samsung Display Co., Ltd., Yongin-City, Gyeonggi-Do 446-711 (Korea, Republic of); Kim, Sungmin [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Heo, Jaeyeong, E-mail: jheo@jnu.ac.kr [Department of Materials Science and Engineering, and the Optoelectronics Convergence Research Center, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Kim, Hyeong Joon, E-mail: thinfilm@snu.ac.kr [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)

    2016-05-01

    Highlights: • Crack generation in encapsulation layers were detected by leakage current. • Atomic concentration of SiO{sub x}N{sub y} films affected the bending reliability. • The shapes of the crack tips were affected by the stoichiometry of the SiO{sub x}N{sub y} films. - Abstract: By measuring leakage current density, we detected crack generation in silicon nitride (SiN{sub x}) and silicon oxynitride (SiO{sub x}N{sub y}) thin-film encapsulation layers, and correlated with the films’ water vapor permeability characteristics. After repeated bending cycles, both the changes in water vapor transmission rate and leakage current density were directly proportional to the crack density. Thick SiN{sub x} films had better water vapor barrier characteristics in their pristine state, but cyclic loading led to fast failure. Varying the atomic concentration of the SiO{sub x}N{sub y} films affected their bending reliability. We attribute these differences to changes in the shape of the crack tip as the oxygen content varies.

  13. Intense violet-blue emitting (CaCl{sub 2}/SiO{sub 2}) : Eu{sup 2+} phosphor powders for applications in UV-LED based phototherapy illuminators

    Energy Technology Data Exchange (ETDEWEB)

    Hao Zhendong; Zhang Jiahua; Zhang Xia; Ren Xinguang; Luo Yongshi; Lu Shaozhe; Wang Xiaojun [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), Chinese Academy of Sciences, 16 Eastern South Lake Road, Changchun 130033 (China)], E-mail: zhangjh@ciomp.ac.cn

    2008-09-21

    An intense violet-blue emitting (CaCl{sub 2}/SiO{sub 2}) : Eu{sup 2+} phosphor with a composition of 25% CaCl{sub 2} and 75% SiO{sub 2} is prepared by a solid state reaction. The phosphor emits at 427 nm with a narrow bandwidth of 21 nm. The photoluminescence (PL) intensities and fluorescence lifetimes are studied as a function of Eu{sup 2+} concentrations. It is observed that the PL intensity of (CaCl{sub 2}/SiO{sub 2}) : Eu{sup 2+} can be 30% higher than that of commercial Sr{sub 2}P{sub 2}O{sub 7} : Eu{sup 2+} phosphor under 395 nm excitation. (CaCl{sub 2}/SiO{sub 2}) : Eu{sup 2+} would be a promising new phosphor for converting near-ultraviolet radiation to violet-blue emission for a novel phototherapy illuminator using a near-ultraviolet ({approx}395 nm) light emitting diode as the excitation source. (fast track communication)

  14. Intrinsic SiO{sub x}-based unipolar resistive switching memory. II. Thermal effects on charge transport and characterization of multilevel programing

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yao-Feng, E-mail: yfchang@utexas.edu; Chen, Ying-Chen; Chen, Yen-Ting; Wang, Yanzhen; Xue, Fei; Zhou, Fei; Lee, Jack C. [Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758 (United States); Fowler, Burt [PrivaTran, LLC, 1250 Capital of Texas Highway South, Bldg 3, Ste 400, Austin, Texas 78746 (United States)

    2014-07-28

    Multilevel programing and charge transport characteristics of intrinsic SiO{sub x}-based resistive switching memory are investigated using TaN/SiO{sub x}/n{sup ++}Si (MIS) and TiW/SiO{sub x}/TiW (MIM) device structures. Current transport characteristics of high- and low-resistance states (HRS and LRS) are studied in both device structures during multilevel operation. Analysis of device thermal response demonstrates that the effective electron energy barrier is strongly dependent on the resistance of the programed state, with estimates of 0.1 eV in the LRS and 0.6 eV in the HRS. Linear data fitting and conductance analyses indicate Poole-Frenkel emission or hopping conductance in the low-voltage region, whereas Fowler-Nordheim (F-N) or trap-assisted tunneling (TAT) is indicated at moderate voltage. Characterizations using hopping transport lead to hopping distance estimates of ∼1 nm in the LRS for both device structures. Relative permittivity values (ε{sub r}) were extracted using the Poole-Frenkel formulism and estimates of local filament temperature, where ε{sub r} values were ∼80 in the LRS and ∼4 in the HRS, suggesting a strongly polarized medium in the LRS. The onset of F-N tunneling or TAT corresponds to an observed “overshoot” in the I-V response with an estimated threshold of 1.6 ± 0.2 V, in good agreement with reported electro-luminescence results for LRS devices. Resistive switching is discussed in terms of electrochemical reactions between common SiO{sub 2} defects, and specific defect energy levels are assigned to the dominant transitions in the I-V response. The overshoot response in the LRS is consistent with TAT through either the Eγ' oxygen vacancy or the hydrogen bridge defect, both of which are reported to have an effective bandgap of 1.7 eV. The SET threshold at ∼2.5 V is modeled as hydrogen release from the (Si-H){sub 2} defect to generate the hydrogen bridge, and the RESET transition is modeled as an

  15. Sol–gel hybrid membranes loaded with meso/macroporous SiO{sub 2}, TiO{sub 2}–P{sub 2}O{sub 5} and SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5} materials with high proton conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Yolanda, E-mail: castro@icv.csic.es [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Mosa, Jadra, E-mail: jmosa@icv.csic.es [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Aparicio, Mario [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Pérez-Carrillo, Lourdes A.; Vílchez, Susana; Esquena, Jordi [Instituto de Química Avanzada de Cataluña, Consejo Superior de Investigaciones Científicas (IQAC-CSIC), CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Jordi Girona 18-26, 08034 Barcelona (Spain); Durán, Alicia [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain)

    2015-01-15

    In this work, highly conductive hybrid organic–inorganic membranes loaded with SiO{sub 2}, TiO{sub 2}–P{sub 2}O{sub 5} and SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5} meso/macroporous particles were prepared via a sol–gel process. Meso/macroporous particles were incorporated to hybrid membranes, for improving water retention and enhancing electrochemical performance. These particles with a polymodal pore size distribution were prepared by templating in highly concentrated emulsions, the particles showed a specific surface area between 50 m{sup 2}/g (TiO{sub 2}–P{sub 2}O{sub 5}) and 300 m{sup 2}/g (SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5}). The particles were dispersed in a hybrid silica sol and further sprayed onto glass paper. The films were polymerized and sintered; those loaded with meso/macroporous particles had a homogenous distribution. High temperature proton conductivity measurements confirmed a high water retention. Conductivity of these materials is higher than that of Nafion{sup ®} at higher temperatures (120 °C) (2·10{sup −2} S/cm). This study provides processing guideline to achieve hybrid electrolytes for efficient conduction of protons due to their high surface area and porous structure. - Highlights: • Hybrid electrolyte with meso/macroporous particles were synthesized by sol–gel. • Depositions of hybrid solutions by spraying onto glass substrates were performed. • Proton conductivity was evaluated as a function of composition and porous structure.

  16. Magnetic core–shell Fe{sub 3}O{sub 4}@SiO{sub 2}/MWCNT nanocomposite modified carbon paste electrode for amplified electrochemical sensing of uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Arvand, Majid, E-mail: arvand@guilan.ac.ir; Hassannezhad, Morassa

    2014-03-01

    A new type of nanocomposite based on multi-walled carbon nanotubes decorated with magnetic core–shell Fe{sub 3}O{sub 4}@SiO{sub 2} nanoparticles (Fe{sub 3}O{sub 4}@SiO{sub 2}/MWCNTs) was prepared and used to fabricate a modified carbon paste electrode (CPE). The nanocomposite was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FT-IR) techniques. Electrochemical behavior of uric acid (UA) was investigated on Fe{sub 3}O{sub 4}@SiO{sub 2}/MWCNTs-CPE by cyclic voltammetry (CV) and square wave voltammetry (SWV) in phosphate buffer solution (pH 6.0). Under the optimized conditions, the peak currents increased linearly with the concentration of UA in the range from 0.60 to 100.0 μM, with a detection limit of 0.13 μM. The proposed sensor was successfully applied for the determination of UA in biological fluids. - Highlights: • A simple and rapid sensor for determination of UA in human blood serum and urine was prepared. • The Fe{sub 3}O{sub 4}@SiO{sub 2}/MWCNTs-CPE showed an obvious increase in surface area and sensitivity. • The presence of Fe{sub 3}O{sub 4}@SiO{sub 2} nanoparticles showed good ability to distinguish the response of UA.

  17. Differential uptake and oxidative stress response in zebrafish fed a single dose of the principal copper and zinc enriched sub-cellular fractions of Gammarus pulex

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Farhan R., E-mail: f.khan@nhm.ac.uk [Nutritional Sciences Division, King' s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH (United Kingdom); Bury, Nicolas R.; Hogstrand, Christer [Nutritional Sciences Division, King' s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH (United Kingdom)

    2010-09-15

    The sub-cellular compartmentalisation of trace metals and its effect on trophic transfer and toxicity in the aquatic food chain has been a subject of growing interest. In the present study, the crustacean Gammarus pulex was exposed to either 11 {mu}g Cu l{sup -1}, added solely as the enriched stable isotope {sup 65}Cu, or 660 {mu}g Zn l{sup -1}, radiolabeled with 2MBq {sup 65}Zn, for 16 days. Post-exposure the heat stable cytosol containing metallothionein-like proteins (MTLP) and a combined granular and exoskeletal (MRG + exo) fractions were isolated by differential centrifugation, incorporated into gelatin and fed to zebrafish as a single meal. Assimilation efficiency (AE) and intestinal lipid peroxidation, as malondialdehyde (MDA) were measured. There was a significant difference (p < 0.05) between the retention of the MTLP-Zn (39.0 {+-} 6.4%) and MRG + exo-Zn (17.2 {+-} 3.7%) and of this zinc retained by the zebrafish a significantly greater proportion of the MTLP-Zn feed had been transported away from the site of uptake. For {sup 65}Cu, although the results pointed towards greater bioavailability of the MTLP fraction compared to MRG + exo during the slow elimination phase (24-72 h) these results were not significant (p = 0.155). Neither zinc feed provoked a lipid peroxidation response in the intestinal tissue of zebrafish compared to control fish (gelatin fed), but both {sup 65}Cu labeled feeds did. The greater effect was exerted by the MRG + exo (2.96 {+-} 0.29 nmol MDA mg protein{sup -1}) feed which three-fold greater than control (p < 0.01) and almost twice the MDA concentration of the MTLP feed (1.76 {+-} 0.21 nmol MDA mg protein{sup -1}, p < 0.05). The oxidative stress response produced by Zn and Cu is in keeping with their respective redox potentials; Zn being oxidatively inert and Cu being redox active. These results are similar, in terms of bioavailability and stress response of each feed, to those in our previous study in which {sup 109}Cd labeled G

  18. Bipolar resistive switching and charge transport in silicon oxide memristor

    Energy Technology Data Exchange (ETDEWEB)

    Mikhaylov, Alexey N., E-mail: mian@nifti.unn.ru [Lobachevsky State University of Nizhni Novgorod, 23/3 Gagarin Prospect, Nizhni Novgorod 603950 (Russian Federation); Belov, Alexey I.; Guseinov, Davud V.; Korolev, Dmitry S.; Antonov, Ivan N.; Efimovykh, Denis V.; Tikhov, Stanislav V.; Kasatkin, Alexander P.; Gorshkov, Oleg N.; Tetelbaum, David I.; Bobrov, Alexander I.; Malekhonova, Natalia V.; Pavlov, Dmitry A. [Lobachevsky State University of Nizhni Novgorod, 23/3 Gagarin Prospect, Nizhni Novgorod 603950 (Russian Federation); Gryaznov, Evgeny G. [Lobachevsky State University of Nizhni Novgorod, 23/3 Gagarin Prospect, Nizhni Novgorod 603950 (Russian Federation); Sedakov Scientific-Research Institute, GSP-486, Nizhny Novgorod 603950 (Russian Federation); Yatmanov, Alexander P. [Sedakov Scientific-Research Institute, GSP-486, Nizhny Novgorod 603950 (Russian Federation)

    2015-04-15

    Graphical abstract: - Highlights: • Si-based thin-film memristor structure was fabricated by magnetron sputtering. • We study bipolar resistive switching and charge transport mechanisms. • Resistive switching parameters are determined by a balance between redox reactions. - Abstract: Reproducible bipolar resistive switching has been studied in SiO{sub x}-based thin-film memristor structures deposited by magnetron sputtering technique on the TiN/Ti metalized SiO{sub 2}/Si substrates. It is established that, after electroforming, the structure can be switched between the quasi-ohmic low-resistance state related to silicon chains (conducting filaments) and the high-resistance state with semiconductor-like hopping mechanism of charge transport through the defects in silicon oxide. The switching parameters are determined by a balance between the reduction and oxidation processes that, in turn, are driven by the value and polarity of voltage bias, current, temperature and device environment. The results can be used for the development of silicon-based nonvolatile memory and memristive systems as a key component of future electronics.

  19. Protective effects of pulmonary epithelial lining fluid on oxidative stress and DNA single-strand breaks caused by ultrafine carbon black, ferrous sulphate and organic extract of diesel exhaust particles

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, Hsiao-Chi [School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan (China); Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan (China); Cheng, Yi-Ling; Lei, Yu-Chen [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Chang, Hui-Hsien [Institute of Environmental Health, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Cheng, Tsun-Jen, E-mail: tcheng@ntu.edu.tw [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Department of Public Health, College of Public Health, National Taiwan University, Taipei, Taiwan (China)

    2013-02-01

    Pulmonary epithelial lining fluid (ELF) is the first substance to make contact with inhaled particulate matter (PM) and interacts chemically with PM components. The objective of this study was to determine the role of ELF in oxidative stress, DNA damage and the production of proinflammatory cytokines following physicochemical exposure to PM. Ultrafine carbon black (ufCB, 15 nm; a model carbonaceous core), ferrous sulphate (FeSO{sub 4}; a model transition metal) and a diesel exhaust particle (DEP) extract (a model organic compound) were used to examine the acellular oxidative potential of synthetic ELF and non-ELF systems. We compared the effects of exposure to ufCB, FeSO{sub 4} and DEP extract on human alveolar epithelial Type II (A549) cells to determine the levels of oxidative stress, DNA single-strand breaks and interleukin-8 (IL-8) production in ELF and non-ELF systems. The effects of ufCB and FeSO{sub 4} on the acellular oxidative potential, cellular oxidative stress and DNA single-strand breakage were mitigated significantly by the addition of ELF, whereas there was no decrease following treatment with the DEP extract. There was no significant effect on IL-8 production following exposure to samples that were suspended in ELF/non-ELF systems. The results of the present study indicate that ELF plays an important role in the initial defence against PM in the pulmonary environment. Experimental components, such as ufCB and FeSO{sub 4}, induced the production of oxidative stress and led to DNA single-strand breaks, which were moderately prevented by the addition of ELF. These findings suggest that ELF plays a protective role against PM-driven oxidative stress and DNA damage. -- Highlights: ► To determine the role of ELF in ROS, DNA damage and IL-8 after exposure to PM. ► ufCB, FeSO{sub 4} and DEP extract were used to examine the protective effects of ELF. ► PM-driven oxidative stress and DNA single-strand breakage were mitigated by ELF. ► The findings

  20. Ion induced intermixing and consequent effects on the leakage currents in HfO{sub 2}/SiO{sub 2}/Si systems

    Energy Technology Data Exchange (ETDEWEB)

    Manikanthababu, N.; Saikiran, V.; Pathak, A.P.; Rao, S.V.S.N. [University of Hyderabad, School of Physics, Hyderabad (India); Chan, T.K.; Vajandar, S.; Osipowicz, T. [National University of Singapore, Department of Physics, Centre for Ion Beam Applications (CIBA), Singapore (Singapore)

    2017-05-15

    Atomic layer deposited (ALD) samples with layer stacks of HfO{sub 2} (3 nm)/SiO{sub 2} (0.7 nm)/Si were subjected to 120 MeV Au ion irradiation at different fluences to study intermixing effects across the HfO{sub 2}/SiO{sub 2} interface. High-resolution Rutherford backscattering spectrometry (HRBS) and X-ray reflectivity (XRR) measurements confirm an increase in the interlayer thickness as a result of SHI induced intermixing effects. Current-voltage (I-V) measurements reveal an order of magnitude difference in the leakage current density between the pristine and irradiated samples. This can be explained by considering the increased physical thickness of interlayer (HfSiO). Furthermore, the samples were subjected to rapid thermal annealing (RTA) process to analyze annealing kinetics. (orig.)

  1. Fe{sub 3}Si nanodots epitaxially grown on Si(111) substrates using ultrathin SiO{sub 2} film technique

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Yoshiaki, E-mail: nakamura@ee.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Fukuda, Kenjiro; Amari, Shogo; Ichikawa, Masakazu [Department of Applied Physics, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2011-10-03

    Ultrahigh density (> 10{sup 12} cm{sup -2}) Fe{sub 3}Si nanodots (NDs) are epitaxially grown on Si(111) substrates by codeposition of Fe and Si on the ultrathin SiO{sub 2} films with ultrahigh density nanovoids. We used two kinds of methods for epitaxial growth: molecular beam epitaxy (MBE) and solid phase epitaxy. For MBE, low temperature (< 300 deg. C) growth of the Fe{sub 3}Si NDs is needed to suppress the interdiffusion between Fe atoms deposited on the surfaces and Si atoms in the substrate. These epitaxial NDs exhibited the ferromagnetism at low temperatures, which were expected in terms of the application to the magnetic memory device materials.

  2. Large-scale preparation of strawberry-like, AgNP-doped SiO{sub 2} microspheres using the electrospraying method

    Energy Technology Data Exchange (ETDEWEB)

    Ma Zhijun; Tan Dezhi; Teng Yu; Zhou Jiajia; Guan Miaojia; Qiu Jianrong [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Ji Huijiao; Zhang Ming [College of Life Science, Zhejiang University, Hangzhou 310058 (China); Dong Guoping, E-mail: qjr@zju.edu.cn, E-mail: zhangming201201@126.com [Key Laboratory of Specially Functional Materials of Ministry of Education and Institute of Optical Communication Materials, South China University of Technology, Guangzhou, Guangdong 510640 (China)

    2011-07-29

    In this paper, we report on a novel strategy for the preparation of silver nanoparticle-doped SiO{sub 2} microspheres (Ag-SMSs) with an interesting strawberry-like morphology using a simple and efficient electrospraying method. SEM (scanning electron microscopy), TEM (transmission electron microscopy), XRD (x-ray diffraction), EDS (energy-dispersive spectroscopy) and UV-vis spectra (ultraviolet-visible spectra) were applied to investigate the morphology, structure, composition and optical properties of the hybrid microspheres, and E. coli (Escherichia coli) was used as a model microbe to evaluate their antibacterial ability. The results showed that the Ag-SMSs were environmentally stable and washing resistant. The Ag-SMSs exhibited effective inhibition against proliferation of E. coli, and their antibacterial ability could be well preserved for a long time. The environmental stability, washing resistance, efficient antibacterial ability and simple but productive preparation method endowed the Ag-SMSs with great potential for practical biomedical applications.

  3. X-ray photoelectron spectroscopy of Er{sup 3+}-activated SiO{sub 2}-HfO{sub 2} glass-ceramic waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Minati, L; Speranza, G; Micheli, V [FBK via Sommarive 18, Povo, 38100 Trento (Italy); Ferrari, M; Jestin, Y [CNR-IFN, Istituto di Fotonica e Nanotecnologie, CSMFO Lab., Via alla Cascata, 56/C, Povo, 38100 Trento (Italy)], E-mail: luminati@fbk.eu

    2009-01-07

    xHfO{sub 2}-(100 - x) SiO{sub 2} (x = 10, 20, 30 mol%) glass-ceramic planar waveguides doped with 0.3 mol% Er{sup 3+} ions, prepared by the sol-gel route and heat treated at 1000 deg. C to nucleate HfO{sub 2} crystals, were analysed by x-ray photoelectron spectroscopy, x-ray diffraction, high resolution transmission electron microscopy and photoluminescence spectroscopy. Formation of tetragonal HfO{sub 2} nanocrystals has been evidenced in all the samples. Spectroscopic parameters concerning the {sup 4}I{sub 13/2} metastable state of Er{sup 3+}ion are revisited as a function of XPS analysis.

  4. In-vitro study of copper doped SiO{sub 2}-CaO-P{sub 2}O{sub 5} system for bioactivity and antimicrobial properties

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Kulwinder; Singh, K. J., E-mail: kanwarjitsingh@yahoo.com; Anand, Vikas [Department of Physics, Guru Nanak Dev University, Amritsar-143005 (India); Kaur, Harpreet; Arora, Daljit Singh [Department of Microbiology, Guru Nanak Dev University, Amritsar-143005 (India)

    2015-08-28

    Samples of the xCuO-(45-x)CaO-10P{sub 2}O{sub 5}-45SiO{sub 2} system (x varies from 0 to 4 mole%) have been synthesized for application as biomaterials to slow or inhibit the growth of living organisms (fungi and other pathogenic microorganisms) by the combination of sol-gel and co-precipitation processes. Prepared samples have been characterized by X-Ray Diffraction, Fourier Transform Infra-Red and Field Emission Scanning Electron Microscopy techniques before and after immersion in simulated body fluid. Antimicrobial activity of samples has been investigated against Staphylococcus aureus. Releasing of Cu{sup 2+}and other ions in the simulated body fluid has been determined by Atomic Absorption Spectroscopy to ensure the use of prepared material as biomaterial with good antibacterial properties.

  5. Structural changes and conductance thresholds in metal-free intrinsic SiO{sub x} resistive random access memory

    Energy Technology Data Exchange (ETDEWEB)

    Mehonic, Adnan, E-mail: a.mehonic@ee.ucl.ac.uk, E-mail: t.kenyon@ucl.ac.uk; Buckwell, Mark; Montesi, Luca; Garnett, Leon; Hudziak, Stephen; Kenyon, Anthony J., E-mail: a.mehonic@ee.ucl.ac.uk, E-mail: t.kenyon@ucl.ac.uk [Department of Electronic and Electrical Engineering, UCL, Torrington Place, London WC1E 7JE (United Kingdom); Fearn, Sarah; Chater, Richard; McPhail, David [Department of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom)

    2015-03-28

    We present an investigation of structural changes in silicon-rich silicon oxide metal-insulator-metal resistive RAM devices. The observed unipolar switching, which is intrinsic to the bulk oxide material and does not involve movement of metal ions, correlates with changes in the structure of the oxide. We use atomic force microscopy, conductive atomic force microscopy, x-ray photoelectron spectroscopy, and secondary ion mass spectroscopy to examine the structural changes occurring as a result of switching. We confirm that protrusions formed at the surface of samples during switching are bubbles, which are likely to be related to the outdiffusion of oxygen. This supports existing models for valence-change based resistive switching in oxides. In addition, we describe parallel linear and nonlinear conduction pathways and suggest that the conductance quantum, G{sub 0}, is a natural boundary between the high and low resistance states of our devices.

  6. Design and fabrication of UV band-pass filters based on SiO{sub 2}/Si{sub 3}N{sub 4} dielectric distributed bragg reflectors

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Jiangping; Gao, Wang; Liu, Bin, E-mail: bliu@nju.edu.cn; Cao, Xianlei; Tao, Tao; Xie, Zili; Zhao, Hong; Chen, Dunjun; Ping, Han; Zhang, Rong

    2016-02-28

    Graphical abstract: - Highlights: • Tandem dielectric distributed Bragg reflectors were fabricated as UV band-pass filters. • Varied center wavelengths and passband widths of filters were achieved successfully. • Transition layer between sub-layers can be proved by XPS analysis clearly. • The optical performance degradation was discussed by FDTD simulation in detail. - Abstract: We have designed one kind of optical filters based on double stacks of 13.5-pairs SiO{sub 2}/Si{sub 3}N{sub 4} dielectric distributed Bragg reflector (DDBR) structures, to realize the passband with different central wavelengths in ultraviolet (UV) range. These SiO{sub 2}/Si{sub 3}N{sub 4} multi-layers have been successfully fabricated on (0001) sapphire substrates by plasma-enhanced chemical vapor deposition (PECVD). The reflectance spectra measured by the UV–visible spectrometer manifest that a series of band-pass filters with fixed passband width of ∼30 nm and central passband varied from 310 nm to 370 nm have been obtained successfully. Besides, the other series of filters with passband width varied from 30 nm to 45 nm can be achieved. With good control of PECVD deposition parameters, all samples exhibit smooth surface with root mean square roughness less than 4.5 nm. Moreover, cross-section scanning electron microscope (SEM) images show these DDBR structures have good periodicity in accordance with the design, indicating that these band-pass filter structures are suitable for wavelength-window-selection UV photodetectors.

  7. Ge{sup 4+}, Eu{sup 3+}-codoped Y{sub 2}SiO{sub 5} as a novel red phosphor for white LED applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan; Dong, Yuanyuan [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China); Wei, Bo [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu 215500 (China); Xu, Jiayue

    2017-05-15

    The phosphors Y{sub 2}SiO{sub 5}: Ge{sup 4+}, Eu{sup 3+} were synthesized by solid state reaction method assisted by flux, and have been characterized by X-ray powder diffraction and fluorescence spectrometer. The results showed that the phosphors can be effectively excited by near-UV (394 nm), and the major peak is located at 611 nm ascribed to the electric-dipole {sup 5}D{sub 0} → {sup 7}F{sub 2} transition of Eu{sup 3+}, the critical quenching concentration of Eu{sup 3+} in the phosphor is determined to be 15 mol% and the critical transfer distance is calculated as 8.90 Aa. Co-doping Y{sub 2}SiO{sub 5}: Eu{sup 3+} with Ge{sup 4+} helps to improve the luminescence intensity and color purity. The red emission of the phosphor under 394 nm excitation shows a good chromaticity index (0.652, 0.347) compared to commercial red phosphors Y{sub 2}O{sub 2}S: Eu{sup 3+} (0.631, 0.350). The quantum efficiency of the Y{sub 2}Si{sub 0.97}O{sub 5}: 0.03Ge{sup 4+}, 0.15Eu{sup 3+}phosphor under 394 nm excitation is estimated to be 45.24%. It can be concluded that efficient red light emitting diodes were fabricated using Ge{sup 4+}, Eu{sup 3+} co-doped phosphor based on near ultraviolet(NUV) excited LED lights. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Acute administration of single oral dose of grape seed polyphenols restores blood pressure in a rat model of metabolic syndrome: role of nitric oxide and prostacyclin.

    Science.gov (United States)

    Pons, Zara; Margalef, Maria; Bravo, Francisca I; Arola-Arnal, Anna; Muguerza, Begoña

    2016-03-01

    The aims of this study were to evaluate the antihypertensive effectiveness of different doses of grape seed polyphenols in cafeteria diet-fed hypertensive rats (CHRs) and to establish the mechanism involved in the blood pressure (BP) lowering effect of these compounds in this experimental model of metabolic syndrome (MS). Male 8-week-old Wistar rats were fed cafeteria or standard (ST) diet for 10 weeks. After this, the antihypertensive effect of a single oral administration of a polyphenol grape seed extract (GSPE) was tested at different doses (250, 375 and 500 mg/kg) in CHRs. BP was recorded before and 2, 4, 6, 8, 24 and 48 h post-administration. The hypotensive effect of GSPE was also proved in ST diet-fed rats. Additionally, in other experiment, CHRs were orally administered 375 mg/kg GSPE. Four hours post-administration, the rats were intraperitoneally administrated 30 mg/kg NG-nitro-L-arginine methyl ester (L-NAME) or 5 mg/kg indomethacin [inhibitors of nitric oxide (NO) and prostacyclin synthesis, respectively]. BP was recorded initially and 6 h post-administration. GSPE produced a decrease in SBP and DBP, the most effective dose (375 mg/kg) showing an antihypertensive effect in CHRs similar to the drug captopril, and did not affect BP of ST diet-fed rats. The antihypertensive effect was completely abolished by L-NAME and partially inhibited by indomethacin. GSPE acts as an antihypertensive agent in a rat model of hypertension associated with MS. The change in endothelium-derived NO availability is one of the mechanisms involved in the antihypertensive effect of GSPE in CHRs. Additionally, endothelial prostacyclin contributes to the effect of GSPE on arterial BP.

  9. Fundamental and harmonic soliton mode-locked erbium-doped fiber laser using single-walled carbon nanotubes embedded in poly (ethylene oxide) film saturable absorber

    Science.gov (United States)

    Rosdin, R. Z. R. R.; Zarei, A.; Ali, N. M.; Arof, H.; Ahmad, H.; Harun, S. W.

    2015-01-01

    This paper presents a simple, compact and low cost mode-locked Erbium-doped fiber laser (EDFL) using a single-walled carbon nanotubes (SWCNTs) embedded in poly(ethylene oxide) (PEO) film as a passive saturable absorber. The film was fabricated using a prepared homogeneous SWCNT solution, which was mixed with a diluted PEO solution and casted onto a glass petri dish to form a thin film by evaporation technique. The film, with a thickness of 50 μm, is sandwiched between two fiber connectors to construct a saturable absorber, which is then integrated in an EDFL cavity to generate a self-started stable soliton pulses operating at 1560.8 nm. The soliton pulse starts to lase at 1480 nm pup power threshold of 12.3 mW to produce pulse train with repetition rate of 11.21 MHz, pulse width of 1.02 ps, average output power of 0.65 mW and pulse energy of 57.98 pJ. Then, we observed the 4th, 7th and 15th harmonic of fundamental cavity frequency start to occur when the pump powers are further increased to 14.9, 17.5 and 20.1 mW, respectively. The 4th harmonic pulses are characterized in detail with a repetition rate of 44.84 MHz, a transform-limited pulse width of 1.19 ps, side-mode suppression ratio of larger than 20 dB and pulse energy of 9.14 pJ.

  10. Comparative assessment of the area of sealer voids in single cone obturation done with mineral trioxide aggregate, epoxy resin, and zinc-oxide eugenol based sealers

    Directory of Open Access Journals (Sweden)

    Anisha Kumar

    2016-01-01

    Full Text Available Introduction: Voids in the sealer mass have the potential to allow leakage through obturation. They are more critical in single cone (SC obturation as the volume of sealer used in this obturation is larger when compared to other obturations. Aim: To compare the area of voids in mineral trioxide aggregate (MTA-based, resin-based, and zinc oxide-eugenol-based sealers when employed with SC obturation technique. Materials and Methods: Fifteen teeth were cleaned and shaped and divided into three groups for SC obturation using MTA Fillapex, AH26, and Pulpdent sealers, respectively. The obturated teeth were sectioned at apical, middle, and coronal third, and area of voids in the sealer was assessed using a stereomicroscope and digital images and image software. The results were statistically analyzed using SPSS software and Kruskal-Wallis and Mann-Whitney tests. Results: The three tested sealers showed voids in all the sections except MTA Fillapex, which was void free in apical and middle sections. There were significant differences between these sealers regarding their section wise area of voids (P < 0.05. Similarly, there were significant differences in their overall area of voids (P < 0.05 with MTA Fillapex showing significantly least area of voids followed by AH26. Conclusions: SC obturation with MTA Fillapex sealer, which showed void free apical and middle third sections, had significantly least area of voids in the sealer followed by the one with AH26 sealer, whereas SC obturation with Pulpdent sealer had significantly most area of voids.

  11. Single-dose rosuvastatin ameliorates lung ischemia-reperfusion injury via upregulation of endothelial nitric oxide synthase and inhibition of macrophage infiltration in rats with pulmonary hypertension.

    Science.gov (United States)

    Matsuo, Satoshi; Saiki, Yuriko; Adachi, Osamu; Kawamoto, Shunsuke; Fukushige, Shinichi; Horii, Akira; Saiki, Yoshikatsu

    2015-03-01

    Lung ischemia-reperfusion (IR) injury during cardiopulmonary surgery is associated with postoperative morbidity and mortality, particularly in patients with pulmonary hypertension (PH). Using a rat model for monocrotaline-induced PH, we investigated the protective effect of rosuvastatin against IR injury in lungs affected by PH and attempted to elucidate its mechanism of action. Male Sprague-Dawley monocrotaline-treated rats were divided into 4 groups (n = 8-9): sham, control + IR, statin + IR, and statin + mevalonolactone + IR. Lung ischemia was induced by left pulmonary artery occlusion (1 hour), followed by reperfusion (4 hours). Rosuvastatin (2 mg/kg) was injected 18 hours before reperfusion and mevalonolactone (1 mg/kg) was injected immediately before reperfusion. The arterial oxygen tension/inspired oxygen fraction ratio was used as a measure of lung oxygenation. Left lung tissue was analyzed for the wet-to-dry lung weight ratio and protein expression of endothelial nitric oxide synthase (eNOS) and phospho-eNOS. Macrophage recruitment was assessed by CD68 immunostaining. Our results showed that rosuvastatin decreased IR lung injury (control + IR vs statin + IR) in terms of the arterial oxygen tension/inspired oxygen fraction ratio (272 ± 43 vs 442 ± 13), wet-to-dry ratio (5.7 ± 0.7 vs 4.8 ± 0.6), and macrophage infiltration (8.0 ± 0.6/field vs 4.0 ± 0.5/field) (P < .05 for all). eNOS and phospho-eNOS were downregulated by IR, which was blocked by rosuvastatin. Effects of rosuvastatin were blunted by mevalonolactone. Single-dose rosuvastatin decreased IR injury in lungs affected by PH via 2 anti-inflammatory mechanisms: preserving eNOS function and inhibiting macrophage infiltration. Copyright © 2015 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

  12. Bending strength of glass-ceramics based on 3CaO.P{sub 2}O{sub 5}-SiO{sub 2}-MgO glass system; Resistencia a fratura de vitroceramicos do sistema 3CaO.P{sub 2}O{sub 5}-SiO{sub 2}-MgO

    Energy Technology Data Exchange (ETDEWEB)

    Daguano, J.K.M.F.; Suzuki, P.A.; Santos, C. [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia de Lorena. Dept. de Engenharia de Materiais; Fernandes, M.H.V. [Universidade de Aveiro (UAveiro/CECICO), Aveiro (Portugal). Centro de Investigacao em Materiais Ceramicos e Compositos. Dept. de Engenharia Ceramica e do Vidro; Elias, C.N. [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Lab. de Biomateriais

    2009-07-01

    In this work, the Modulus of Rupture of bioactive glass-ceramic based on 3CaO.P{sub 2}O{sub 5}-SiO{sub 2}-MgO system was investigated, aiming its use in bone-restorations. The mechanical property was correlated with microstructural and crystallographic features of this material. High-purity starting-powders, CaCO{sub 3}, SiO{sub 2}, MgO, Ca (H{sub 2}PO{sub 4}).H{sub 2}O, were used in this study. The powders were mixed in a stoichiometric ratio, using planetary ball-mill. The suspensions were dried, sieved and melted at 1600 deg C, for 4h. The casting ones were cooled quickly until annealing temperature 700 deg C, in which remained for 2h, with controlled cooling-rate until ambient temperature. Bulks of glass were heat-treated with temperatures varying between 700 deg C and 1100 deg C, for 4h, being after that, cooled at 3 deg C/min. Bioactive glass and glass-ceramic were characterized by HRXRD (high resolution X-ray diffraction), where whitlockite was main phase. The microstructure was analyzed by scanning electronic microscopy. Modulus of Rupture was determined by four-point bending testing using specimens of 1.5 x 2 x 25 mm and glasses presented strength near to 70MPa, while glass ceramics treated at 975 deg C-4h, presented bending strength of 120MPa. (author)

  13. Surface crystallization in a Li{sub 2}O-ZrO{sub 2}-SiO{sub 2}-Al{sub 2}O{sub 3} glass; Cristalizacao de superficie em vidro do sistema Li{sub 2}O-ZrO{sub 2}-SiO{sub 2}-Al{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Antonio Pedro Novaes de; Teixeira, Alexandre Henrique Bortolotto; Venturelli, Hugo Henrique, E-mail: bortolotto_teixeira@yahoo.com.br, E-mail: venturellihugo@gmail.com, E-mail: antonio.pedro@ufsc.br [Universidade Federal de Santa Catarina (VITROCER/PGMAT/UFSC), Florianopolis, SC (Brazil). Laboratorio de Materiais Vitroceramicos; Montedo, Oscar Rubem Klegues, E-mail: oscar.rkm@gmail.com [Universidade do Extremo Sul Catarinense (CERTEC/PPGCEM/UNESC), Criciuma, SC (Brazil). Grupo de Pesquisa em Ceramica Tecnica

    2017-04-15

    Growth kinetics of crystallized surface layer in a LZSA glass composition, 11.7Li{sub 2}O·12.6ZrO{sub 2}·68.6SiO{sub 2}·7.1Al{sub 2}O{sub 3} (wt%), was studied. For the production of the LZSA glass, it was used commercial raw materials (Li{sub 2}CO{sub 3}, ZrSiO{sub 4}, SiO{sub 2}, Al{sub 2}O{sub 3}) which were mixed and melted at 1550 °C for 120 min and then poured into a metallic mold. Samples of the obtained glass were cut and subjected to heat treatments at different temperatures (825 - 925 °C) and times (30 - 150 min) for formation and growth of crystalline layer. Cross-sections of the heat-treated samples were ground and polished such that images of the formed crystallized layers could be visualized and measured by microscopy. Results showed that it is possible to obtain LZSA glasses with crystallized layers formed by β-spodumene, zircon and lithium silicate, which present thicknesses between 13 and 665 μ and grow at rates varying from 0.4 to 4.8 μm/min in the studied temperature range. (author)

  14. Features of carrier tunneling between the silicon valence band and metal in devices based on the Al/high-K oxide/SiO{sub 2}/Si structure

    Energy Technology Data Exchange (ETDEWEB)

    Vexler, M. I., E-mail: shulekin@mail.ioffe.ru; Grekhov, I. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2016-05-15

    The features of electron tunneling from or into the silicon valence band in a metal–insulator–semiconductor system with the HfO{sub 2}(ZrO{sub 2})/SiO{sub 2} double-layer insulator are theoretically analyzed for different modes. It is demonstrated that the valence-band current plays a less important role in structures with HfO{sub 2}(ZrO{sub 2})/SiO{sub 2} than in structures containing only silicon dioxide. In the case of a very wide-gap high-K oxide ZrO{sub 2}, nonmonotonic behavior related to tunneling through the upper barrier is predicted for the valence-band–metal current component. The use of an insulator stack can offer certain advantages for some devices, including diodes, bipolar tunnel-emitter transistors, and resonant-tunneling diodes, along with the traditional use of high-K insulators in a field-effect transistor.

  15. Raman and XPS characterization of vanadium oxide thin films with temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ureña-Begara, Ferran, E-mail: ferran.urena@uclouvain.be [Université catholique de Louvain, Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Louvain-la-Neuve (Belgium); Crunteanu, Aurelian [XLIM Research Institute, UMR 7252, CNRS/Université de Limoges, Limoges (France); Raskin, Jean-Pierre [Université catholique de Louvain, Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Louvain-la-Neuve (Belgium)

    2017-05-01

    Highlights: • Comprehensive study of the oxidation of VO{sub 2} thin films from R.T. up to 550 °C. • Phase changes and mixed-valence vanadium oxides formed during the oxidation process. • Reported Raman and XPS signatures for each vanadium oxide. • Monitoring of the current and resistance evolution at the surface of the films. • Oxidation model describing the evolution of the vanadium oxides and phase changes. - Abstract: The oxidation mechanisms and the numerous phase transitions undergone by VO{sub 2} thin films deposited on SiO{sub 2}/Si and Al{sub 2}O{sub 3} substrates when heated from room temperature (R.T.) up to 550 °C in air are investigated by Raman and X-ray photoelectron spectroscopy. The results show that the films undergo several intermediate phase transitions between the initial VO{sub 2} monoclinic phase at R.T. and the final V{sub 2}O{sub 5} phase at 550 °C. The information about these intermediate phase transitions is scarce and their identification is important since they are often found during the synthesis of vanadium dioxide films. Significant changes in the film conductivity have also been observed to occur associated to the phase transitions. In this work, current and resistance measurements performed on the surface of the films are implemented in parallel with the Raman measurements to correlate the different phases with the conductivity of the films. A model to explain the oxidation mechanisms and phenomena occurring during the oxidation of the films is proposed. Peak frequencies, full-width half-maxima, binding energies and oxidation states from the Raman and X-ray photoelectron spectroscopy experiments are reported and analyzed for all the phases encountered in VO{sub 2} films prepared on SiO{sub 2}/Si and Al{sub 2}O{sub 3} substrates.

  16. Low temperature atmospheric pressure chemical vapor deposition of group 14 oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, D.M. [Houston Univ., TX (United States); Atagi, L.M. [Houston Univ., TX (United States)]|[Los Alamos National Lab., NM (United States); Chu, Wei-Kan; Liu, Jia-Rui; Zheng, Zongshuang [Houston Univ., TX (United States); Rubiano, R.R. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Springer, R.W.; Smith, D.C. [Los Alamos National Lab., NM (United States)

    1994-06-01

    Depositions of high quality SiO{sub 2} and SnO{sub 2} films from the reaction of homoleptic amido precursors M(NMe{sub 2})4 (M = Si,Sn) and oxygen were carried out in an atmospheric pressure chemical vapor deposition r. The films were deposited on silicon, glass and quartz substrates at temperatures of 250 to 450C. The silicon dioxide films are stoichiometric (O/Si = 2.0) with less than 0.2 atom % C and 0.3 atom % N and have hydrogen contents of 9 {plus_minus} 5 atom %. They are deposited with growth rates from 380 to 900 {angstrom}/min. The refractive indexes of the SiO{sub 2} films are 1.46, and infrared spectra show a possible Si-OH peak at 950 cm{sup {minus}1}. X-Ray diffraction studies reveal that the SiO{sub 2} film deposited at 350C is amorphous. The tin oxide films are stoichiometric (O/Sn = 2.0) and contain less than 0.8 atom % carbon, and 0.3 atom % N. No hydrogen was detected by elastic recoil spectroscopy. The band gap for the SnO{sub 2} films, as estimated from transmission spectra, is 3.9 eV. The resistivities of the tin oxide films are in the range 10{sup {minus}2} to 10{sup {minus}3} {Omega}cm and do not vary significantly with deposition temperature. The tin oxide film deposited at 350C is cassitterite with some (101) orientation.

  17. In vitro and in vivo comparative study of the phototherapy anticancer activity of hyaluronic acid-modified single-walled carbon nanotubes, graphene oxide, and fullerene

    Science.gov (United States)

    Hou, Lin; Yuan, Yujie; Ren, Junxiao; Zhang, Yinling; Wang, Yongchao; Shan, Xiaoning; Liu, Qi; Zhang, Zhenzhong

    2017-08-01

    In this work, carbon nanomaterials, single-walled carbon nanotubes (SWNT), graphene oxide (GO), and fullerene (C60) were modified by hyaluronic acid (HA) to obtain water-soluble and biocompatible nanomaterials with high tumor-targeting capacity and then the comparative study of these hyaluronic acid-modified carbon nanomaterials was made in vitro and in vivo. The conjugates of hyaluronic acid and carbon nanomaterials, namely, HA-SWNT, HA-GO, HA-C60, were confirmed by UV/Vis spectrum, Fourier transform infrared spectroscopy (FTIR), and a transmission electron microscope (TEM). After HA modification, the sizes of HA-SWNT, HA-GO, and HA-C60 were in a range of 70 to 300 nm, and all the three HA-modified materials were at negative potential, demonstrating that HA modification was in favor of extravasation of carbon materials into a tumor site due to enhanced permeability and retention effect of tumor. Photothermal conversion in vitro test demonstrated excellent photothermal sensitivity of HA-SWNT and HA-GO. But the reactive oxygen yield of HA-C60 was the highest compared with the others under visible light irradiation, which proved the good photodynamic therapy effect of HA-C60. In addition, cytotoxicity experiments exhibited that the inhibitory efficacy of HA-SWNT was the lowest, the second was HA-C60, and the highest was HA-GO, which was consistent with the uptake degree of them. While under the laser irradiation, the cell inhibition of the HA-SWNT was the highest, the second was HA-GO, and the last was HA-C60. In vivo evaluation of the three targeting carbon nanomaterials was consistent with the cytotoxicity assay results. Taken together, the results demonstrated that HA-SWNT and HA-GO were suited for photothermal therapy (PTT) agents for their good photothermal property, while HA-C60 was used as a kind of photodynamic therapy (PDT) agent for its photodynamic effect.

  18. General and Efficient a-Oxygenation of Carbonyl Compounds by TEMPO Induced by Single-Electron-Transfer Oxidation of Their Enolates

    Czech Academy of Sciences Publication Activity Database

    Dinca, E.; Hartmann, P.; Smrček, Jakub; Dix, I.; Jones, P. G.; Jahn, Ullrich

    -, č. 24 (2012), s. 4461-4482 ISSN 1434-193X Institutional support: RVO:61388963 Keywords : carbonyl compounds * oxidation * radicals * electron transfer * enolates Subject RIV: CC - Organic Chemistry Impact factor: 3.344, year: 2012

  19. On a two-layer Si{sub 3}N{sub 4}/SiO{sub 2} dielectric mask for low-resistance ohmic contacts to AlGaN/GaN HEMTs

    Energy Technology Data Exchange (ETDEWEB)

    Arutyunyan, S. S., E-mail: spartakmain@gmail.com; Pavlov, A. Yu.; Pavlov, B. Yu.; Tomosh, K. N.; Fedorov, Yu. V. [Russian Academy of Sciences, Institute of Ultrahigh Frequency Semiconductor Electronics (Russian Federation)

    2016-08-15

    The fabrication of a two-layer Si{sub 3}N{sub 4}/SiO{sub 2} dielectric mask and features of its application in the technology of non-fired epitaxially grown ohmic contacts for high-power HEMTs on AlGaN/GaN heterostructures are described. The proposed Si{sub 3}N{sub 4}/SiO{sub 2} mask allows the selective epitaxial growth of heavily doped ohmic contacts by nitride molecular-beam epitaxy and the fabrication of non-fired ohmic contacts with a resistance of 0.15–0.2 Ω mm and a smooth surface and edge morphology.

  20. Imprinted sol-gel electrochemical sensor for the determination of benzylpenicillin based on Fe{sub 3}O{sub 4}/SiO{sub 2} multi-walled carbon nanotubes-chitosans nanocomposite film modified carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Hu Yufang [College of Chemistry and Chemical Engineering, Jishou University, Hunan 416000 (China); Li Jiaxing [College of Chemistry and Chemical Engineering, Jishou University, Hunan 416000 (China); Central South University of Forestry and Technology, Hunan 410004 (China); Zhang Zhaohui, E-mail: zhaohuizhang77@163.com [College of Chemistry and Chemical Engineering, Jishou University, Hunan 416000 (China) and State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan 410082 (China); Zhang Huabin; Luo Lijuan [College of Chemistry and Chemical Engineering, Jishou University, Hunan 416000 (China); Yao Shouzhuo [State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan 410082 (China)

    2011-07-18

    Graphical abstract: A novel imprinted sol-gel electrochemical sensor based on Fe{sub 3}O{sub 4}/SiO{sub 2}-MWNTs-CTS nanocomposite film and a thin MIP film has been developed on a carbon electrode. Highlights: {yields} A novel imprinted sol-gel electrochemical sensor based on Fe{sub 3}O{sub 4}/SiO{sub 2}-MWNTs-CTS nanocomposites has been developed. {yields} Fe{sub 3}O{sub 4}/SiO{sub 2}-MWNTs-CTS nanocomposites act as 'electronic wires' to enhance the electron transfer. {yields} The inherent specificity of the MIPs brings about highly selectivity. The imprinted sensor detects benzylpenicillin in real samples successfully. - Abstract: Herein, a novel imprinted sol-gel electrochemical sensor based on multi-walled carbon nanotubes (MWNTs) doped with chitosan film on a carbon electrode has been developed. Prior to doped, the MWNTs have been decorated with Fe{sub 3}O{sub 4} nanoparticles which have been coated uniformly with SiO{sub 2} layer. The characterization of imprinted sensor has been carried out by X-ray diffraction and scanning electron microscopy. The performance of the proposed imprinted sensor has been investigated using cyclic voltammetry and differential pulse voltammetry. The imprinted sensor offers a fast response and sensitive benzylpenicillin quantification. The fabricated benzylpenicillin imprinted sensor exhibits a linear response from 5.0 x 10{sup -8} to 1.0 x 10{sup -3} mol L{sup -1} with a detection limit of 1.5 x 10{sup -9} mol L{sup -1}. For samples analysis, perfect recoveries of the imprinted sensor for benzylpenicillin indicated that the imprinted sensor was able to detect benzylpenicillin in real samples successfully.

  1. In vivo behaviors of Ca(OH){sub 2} activated nano SiO{sub 2} (n{sub Ca}/n{sub Si} = 3) cement in rabbit model

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Qing, E-mail: lnqing@yahoo.com [School of Material Engineering, Jinling Institute of Technology, Nanjing 211169 (China); Zhang, Xiaojuan [School of Material Engineering, Jinling Institute of Technology, Nanjing 211169 (China); Lu, Chunhua; Lan, Xianghui [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009 (China); Hou, Guihua [Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Yancheng 224051 (China); Xu, Zhongzi [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009 (China)

    2016-01-01

    In vivo behaviors of Ca(OH){sub 2} activated nano SiO{sub 2} (n{sub Ca}/n{sub Si} = 3, TCS) cement were investigated in the rabbit femoral defects using the poly(methyl methacrylate) (PMMA) as control. The deposited apatite and CaCO{sub 3} layers round TCS paste surfaces were completely used to construct the new bone tissue. TCS paste could stimulate the formation of new bone tissue in marrow tissue. The osteostimulation was mainly attributed to the proliferation and differentiation effects of Ca and Si ions released from TCS paste on the osteoprogenitor cells. However, Calcium–Silicate–Hydrate (C–S–H) gel in TCS paste was harder to degradate than Ca(OH){sub 2}. TCS paste kept the original shape during implantation, and could not provide the pores or spaces for further formation of bone tissue. Osteolytic defects induced by wear particles from TCS paste surface could not be completely avoided, because of the interfacial strain and the extensive micromotion between TCS paste surface and new bone tissue. Overall, our results indicated that Ca(OH){sub 2} activated nano SiO{sub 2} cement was bioactivity and osteostimulation. The further improvements of Ca(OH){sub 2} activated nano SiO{sub 2} cement should be done by achieving a balance between biological properties and mechanical performances. - Highlights: • Ca(OH){sub 2} activated nano SiO{sub 2} (n{sub Ca}/n{sub Si} = 3, TCS) cement was in vivo bioactivity. • Deposited apatite and CaCO{sub 3} particles round TCS paste were utilized to restructure new bone tissue. • TCS paste was able to induce osteogenesis in marrow tissue. • Wear particle could induced osteolytic defect between TCS paste and bone tissue.

  2. Crystallization behavior of (1 - x)Li{sub 2}O.xNa{sub 2}O.Al{sub 2}O{sub 3}.4SiO{sub 2} glasses

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Moo-Chin [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Cheng, Chih-Wei; Chang, Kuo-Ming [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwa