Sample records for mg o2 l-1

  1. Theoretical Limiting Potentials in Mg/O2 Batteries

    Smith, Jeffrey G.; Naruse, Junichi; Hiramatsu, Hidehiko


    A rechargeable battery based on a multivalent Mg/O2 couple is an attractive chemistry due to its high theoretical energy density and potential for low cost. Nevertheless, metal-air batteries based on alkaline earth anodes have received limited attention and generally exhibit modest performance....... In addition, many fundamental aspects of this system remain poorly understood, such as the reaction mechanisms associated with discharge and charging. The present study aims to close this knowledge gap and thereby accelerate the development of Mg/O2 batteries by employing first-principles calculations...... by the presence of large thermodynamic overvoltages. In contrast, MgO2-based cells are predicted to be much more efficient: superoxide-terminated facets on MgO2 crystallites enable low overvoltages and round-trip efficiencies approaching 90%. These data suggest that the performance of Mg/O2 batteries can...

  2. The conduction bands of MgO, MgS and HfO2

    Boer, P.K. de; Groot, R.A. de


    Electronic structure calculations for MgO, MgS and HfO2 are reported. It is shown that the conduction bands of MgO and MgS have predominantly anion character, contrary to the common picture of the conduction band being derived from cation states. In transition metal oxides, unoccupied anion states a

  3. Porous Ceramic Composite ZrO2(MgO)-MgO for Osteoimplantology

    Buyakov, A. S.; Kulkov, S. N.


    Pore and crystalline structure, biocompatibility of ceramic composite ZrO2(MgO)-MgO were studied. The main mechanical characteristics were determined and it has been shown that compression strength directly depends on microstresses obtained from X-ray data. In-vitro studies of mesenchymal stromal stem cells (MMSC), cultivated on material surface are shown that cell proliferation and differentiation of MMSC goes throw osteogenic type.

  4. Intrinsic Conductivity in Magnesium-Oxygen Battery Discharge Products: MgO and MgO2

    Smith, Jeffrey G.; Naruse, Junichi; Hiramatsu, Hidehiko


    O, the equilibrium concentration of carriers in MgO2 is low, and moderate-to-poor mobility further limits conductivity. If equilibrium behavior is realized, then we conclude that (i) sluggish charge transport in MgO or MgO2 will limit battery performance when these compounds cover the cathode support and (ii) what...

  5. Effect of Fused MgO-ZrO2 Clinker Addition on Thermal Shock Resistance of MgO-ZrO2 Unfired Bricks


    MgO-ZrO2 unfired bricks with ZrO2 content up to 8% at the interval of 2% were prepared,using fused magnesia(mgo:97%)and fused MgO-ZrO2 clinker (ZrO2:14.33%) as starting materials and phenolic resin as binder.The effects of ZrO2 content on thermal shock resistance (TSR) and other properties such as cold and hot modulus of rupture have been investigated.Re-sidual cold modulus of rupture ratio after heating at 1 000 ℃ and quenching by air blowing was adopted to characterize TSR.Addition of the Mgo-ZrO2 clinker improves TSR,attributing to the microcrack toughening effect by thermal expansion mismatch between different phases.When ZrO2 content goes above 4%,the impro-ving effect tends to be moderate.The introduction of MgO-ZrO2 clinker can also improve the HMOR at 1 500 ℃,while the increased ZrO2 content reduces CMOR of the bricks prefired at 1 600 ℃.due to the thermal expansion mismatch effect.Compromising the overall properties,the optimal ZrO2 content for such magnesia based unfired brick is suggested to be 4%.

  6. Viscosities of FenO-MgO-SiO2 and FenO-MgO-CaO-SiO2 slags

    戴曦; 甘雪萍; 张传福


    The viscosities of molten Fen O-MgO-SiO2 and Fen O-MgO-CaO-SiO2 semi-synthetic slags for nickel flash smelting were mearured in the temperature range of 1 200-1 450℃ by use of a rotational viscometer.The mass ratio of Fe to SiO2 was fixed at 1.2,calcium oxide and magnesium oxide contents varied in the range of 2%-8% and 9%-12%(mass fraction),respectively.The results show that silicate anions become smaller by increasing CaO content,which results in the viscosity decrease of slag.In the case of addition of MgO the viscosity behaviour is complicated When MgO content is less than 11%,the viscosity increases with the increase of MgO at all temperatures tested .However,when the MgO content is more than 11%,the viscosity decreases slightly for Fen O-MgO-CaOSiO2 system.At higher MgO contents,low-viscosity slags can be obtained by adding CaO.As for a given composition,the viscosity decreased with increasing temperature.The higher the temperature,the more MgO can be added before saturation.The effect of Fe3 O4 on the viscosity is quite significant.The viscosity of slag increases to 300 mpa tions of temperature and composition.A comparison between Fen O-MgO-SiO2 and Fen O-MgO-CaO-SiO2 systems are also given.

  7. Bulk and surface properties of magnesium peroxide MgO2

    Esch, Tobit R.; Bredow, Thomas


    Magnesium peroxide has been identified in Mg/air batteries as an intermediate in the oxygen reduction reaction (ORR) [1]. It is assumed that MgO2 is involved in the solid-electrolyte interphase on the cathode surface. Therefore its structure and stability play a crucial role in the performance of Mg/air batteries. In this work we present a theoretical study of the bulk and low-index surface properties of MgO2. All methods give a good account of the experimental lattice parameters for MgO2 and MgO bulk. The reaction energies, enthalpies and free energies for MgO2 formation from MgO are compared among the different DFT methods and with the local MP2 method. A pronounced dependence from the applied functional is found. At variance with a previous theoretical study but in agreement with recent experiments we find that the MgO2 formation reaction is endothermic (HSE06-D3BJ: ΔH = 51.9 kJ/mol). The stability of low-index surfaces MgO2 (001) (Es = 0.96 J/m2) and (011) (Es = 1.98 J/m2) is calculated and compared to the surface energy of MgO (001). The formation energy of neutral oxygen vacancies in the topmost layer of the MgO2 (001) surface is calculated and compared with defect formation energies for MgO (001).

  8. Electric circuit model for MgO-doped ZrO2-TiO2 ceramic humidity sensor

    Jain, M. K.; Bhatnagar, M. C.; Sharma, G. L.


    The MgO-doped ZrO2-TiO2 ceramic pellets were studied for its humidity-sensitive electrical conduction. An equivalent circuit model has been proposed to define the humidity-sensitive electrical properties. This model is in agreement with the experimental findings. The electrical conduction is largely controlled by the intergranular impedance except at very high humidities. The impedance of the pellets showed inductive behavior in high-humidity region. This behavior can be attributed to the spherical paths adopted by charge carrier because conduction is mainly through the spherical grain surface.

  9. Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

    Sasani, Alireza; Baktash, Ardeshir; Mirabbaszadeh, Kavoos; Khoshnevisan, Bahram


    In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO2 anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO2 surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase JSC of the surface while slightly decreasing VOC compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

  10. Raman study of TiO2 role in SiO2-Al2O3-MgO-TiO2-ZnO glass crystallization.

    Furić, Kresimir; Stoch, Leszek; Dutkiewicz, Jan


    Tough glass-ceramic material of special mechanical properties with nanosize crystal phases formed by appropriately controlled crystallization was studied by Raman spectroscopy. It was obtained by TiO2 activated crystallization of Mg-aluminosilicate glass of SiO2-Al2O3-MgO-TiO2-ZnO composition. Crystallization was preceded by a change in the TiO2 structural position and state, which is manifested by a changed color of glass from yellow into blue shortly before the glass transformation (Tg) temperature. Raman spectroscopy was applied to explain the mechanism of this process and to establish the role of TiO2 in the early stage of glass crystallization that precedes a complete crystal phase formation. The starting glasses were found in almost complete disorder, since all bands were weak, broad and dominated by a Bose band at about 90 cm-1. After the sample annealing all bands turned out better resolved and the Bose band practically disappeared, both confirming the amorphous structure reorganization process. A multiplet observed in the vicinity of 150 cm-1 we assigned to the anatase and other titania structures that can be considered prime centers of crystallization. Finally, in the closest neighborhood of the Rayleigh line the low frequency mode characterizing nanoparticles was observed. According to this band theory, the mean size of initial titania crystallites is about 10nm for all samples, but the size distribution varies within factor two among them.

  11. Mg/O2 Battery Based on the Magnesium-Aluminum Chloride Complex (MACC) Electrolyte

    Vardar, Galin; Smith, Jeffrey G.; Thomson, Travis


    Mg/O2 cells employing a MgCl2/AlCl3/DME (MACC/DME) electrolyte are cycled and compared to cells with modified Grignard electrolytes, showing that performance of magnesium/oxygen batteries depends strongly on electrolyte composition. Discharge capacity is far greater for MACC/DME-based cells, while...... substantially and likely explains the poor rechargeability. An additional impedance rise consistent with film formation on the Mg negative electrode suggests the presence of detrimental O2 crossover. Minimizing O2 crossover and bypassing charge transfer through the discharge product would improve battery...

  12. Preparation and characterization of MgO nanorods coated with SnO2.

    Kim, Hyunsu; Jin, Changhyun; Kim, Hyoun Woo; Lee, Chongmu


    MgO nanorods have been grown by thermal evaporation of Mg3N2 powders on Si (100) substrates coated with gold (Au) thin films. The MgO nanorods grown on Al2O3 (0001) were 0.1-0.2 microm in diameter and up to a few tens of micrometers in length. MgO/SnO2 coaxial nanorods have also been prepared by atomic layer deposition (ALD) of SnO2 onto the nanorods. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis results indicate that the MgO-cores and the SnO2 shells of the annealed coaxial nanorods are of a single crystalline nature with cubic and orthorhombic structures, respectively. The photoluminescence (PL) spectroscopy analysis results show that SnO2 coating slightly increases the PL emission intensity of MgO nanorods. The PL emission of the SnO2-coated MgO nanorods is found to be considerably enhanced by thermal annealing and to strongly depend on the annealing atmosphere. The PL emission intensity of the MgO/SnO2 coaxial nanorods has been significantly increased by annealing in a reducing atmosphere. The origin of the PL enhancement by annealing in a reducing atmosphere is discussed on the basis of energy-dispersive X-ray spectroscopy analyses.

  13. Biomedical bandpass filter for fluorescence microscopy imaging based on TiO2/SiO2 and TiO2/MgF2 dielectric multilayers

    Butt, M. A.; Fomchenkov, S. A.; Ullah, A.; Verma, P.; Khonina, S. N.


    We report a design for creating a multilayer dielectric optical filters based on TiO2 and SiO2/MgF2 alternating layers. We have selected Titanium dioxide (TiO2) for high refractive index (2.5), Silicon dioxide (SiO2) and Magnesium fluoride (MgF2) as a low refractive index layer (1.45 & 1.37) respectively. Miniaturized visible spectrometers are useful for quick and mobile characterization of biological samples. Such devices can be fabricated by using Fabry-Perot (FP) filters consisting of two highly reflecting mirrors with a central cavity in between. Distributed Bragg Reflectors (DBRs) consisting of alternating high and low refractive index material pairs are the most commonly used mirrors in FP filters, due to their high reflectivity. However, DBRs have high reflectivity for a selected range of wavelengths known as the stopband of the DBR. This range is usually much smaller than the sensitivity range of the spectrometer range. Therefore a bandpass filters are required to restrict wavelength outside the stopband of the FP DBRs. The proposed filter shows a high quality with average transmission of 97.4% within the passbands and the transmission outside the passband is around 4%. Special attention has been given to keep the thickness of the filters within the economic limits. It can be suggested that these filters are exceptional choice for florescence imaging and Endoscope narrow band imaging.

  14. Photocatalytic Degradation of Dichlorvos in Visible Light by Mg2+-TiO2 Nanocatalyst

    T. Siva Rao


    Full Text Available Photocatalytic activity of TiO2 was studied by doping with magnesium (Mg2+-TiO2 with varying magnesium weight percentages ranging from 0.75–1.5 wt%. The doped and undoped samples were synthesized by sol-gel method and characterized by X-ray diffraction (XRD, N2 adsorption-desorption (BET, X-ray photoelectron spectroscopy (XPS, UV-visible diffuse reflectance spectroscopy (DRS, and scanning electron microscopy (SEM. The XRD data has shown that anatase crystalline phase in Mg2+-TiO2 catalysts, indicating that Mg2+ ions did not influence the crystal patterns of TiO2. The presence of magnesium ions in TiO2 matrix has been determined by XPS spectra. DRS spectra showed that there is a significant absorption shift towards the visible region for doped TiO2. The SEM images and BET results showed that doped catalyst has smaller particle size and highest surface area than undoped TiO2. The photocatalytic efficiency of the synthesized catalysts was investigated by the photocatalytic degradation of aqueous dichlorvos (DDVP under visible light irradiation, and it was found that the Mg2+-doped catalysts have better catalytic activity than undoped TiO2. This can be attributed that there is a more efficient electron-hole creation in Mg2+-TiO2 in visible light, contrary to undoped TiO2 which can be excited only in UV irradiation. The effect of dopant concentration, pH of solution, dosage of catalysts, and initial pesticide concentration has been studied.

  15. Effect of Additives on Properties of MgO—ZrO2—C Material

    TIAShouxin; LIUShanlin; 等


    The paper describes the effect of additives Al,Si,SiC and A4C on the expanson of MgO-ZrO2-C material after being coked.Theresults indicate that Al and Si were oxi-dized to form Al2O3 and SiO2 respectively,and then re-acted with CaZrO3 or stabilizer in c-ZrO2 to form calcium aluminate,spinel(MA),dicalcium silicate(C2S) and forsterite (M2S) ,Meznwhile,α-C2S ras transformed to γ-C2S and c-ZrO2 to m-ZrO2 when temperature changed.All the above reactions resulted in the decrease of the amount of Al4C3 and SiC and the increase in bulk volume,which caused the stucture of MgO-ZrO2-C material de-stroyed.Hence,contrary to the MgO-C material,when adding Al,and Si,the MgO-ZrO2-C material would be structurally deteriorated after heat-treatment and its strength and corrosion resistance decreased.

  16. Effect of Additives on Properties of MgO-ZrO2-C Material

    TIAN Shouxin; LIU Shanlin; XIE Mengqin


    The paper describes the effect of additives Al, Si,SiC and B4 C on the expansion of MgO-ZrO2-C material after being coked . The results indicate that Al and Si can not increase its hot and cold strength. Al and Si were oxidized to form Al2 O3 and SiO2 respectively, and then reacted with CaZrO3 or stabilizer in c-ZrO2 to form calcium aluminate , spinel ( MA ), dicalcium silicate ( C2 S ) and forsterite (M2S). Meanwhile, α-C2S was transformed to γ-C2S and c-ZrO2 to m-ZrO2 when temperature changed.All the above reactions resulted in the decrease of the amount of Al4 C3 and SiC and the increase in bulk volume ,which caused the structure of MgO-ZrO2-C material destroyed. Hence, contrary to the MgO-C material, when adding Al. and Si, the MgO-ZrO2-C material would be structurally deteriorated after heat-treatment and its strength and corrosion resistance decreased.

  17. Synthesis and lithium storage properties of Zn, Co and Mg doped SnO2 Nano materials

    Palaniyandy, Nithyadharseni


    Full Text Available In this paper, we show that magnesium and cobalt doped SnO2 (Mg-SnO2 and Co-SnO2) nanostructures have profound influence on the discharge capacity and coulombic efficiency of lithium ion batteries (LIBs) employing pure SnO2 and zinc doped SnO2 (Zn-Sn...

  18. Characterization of MgO-coated-LiCoO2 particles by analytical transmission electron microscopy

    Taguchi, Noboru; Akita, Tomoki; Tatsumi, Kuniaki; Sakaebe, Hikari


    The surfaces of LiCoO2 particles were modified to improve the charge-discharge cycling properties of Li-ion batteries containing LiCoO2 cathodes. The sol-gel technique was used to modify the surface of LiCoO2 particles with magnesium oxide. Capacity retention during cycling of the magnesium oxide-coated LiCoO2 cathode was superior to that of a cathode comprising pristine LiCoO2. Moreover, results obtained from TEM measurements indicate that the Li concentration was relatively homogeneous in the magnesium oxide-coated LiCoO2 particles after cycling tests. The crystallographic planes of the coating were found to be coherently oriented with those of the substrate, MgO(111)[1-10]//LiCoO2(003)[100]. Therefore, we believe that a thin cover of Mg on the surface of LiCoO2 stabilizes the surface, contributing to the homogeneity of charge and discharge reactions.

  19. Hydriding/dehydriding properties of NdMgNi alloy with catalyst CeO2

    李霞; 张羊换; 杨泰; 许剑轶; 赵栋梁


    Hydrogen storage composites Nd2Mg17-50 wt.%Ni-x wt.%CeO2 (x=0, 0.5, 1.0, 1.5, 2.0) were obtained by induction-ball milling method. The catalytic effect of CeO2 on hydriding kinetics of Nd2Mg17-50 wt.%Ni composite was investigated. X-ray diffrac-tion (XRD) and high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) analyses showed that Nd2Mg17-50 wt.%Ni alloy had a multiphase structure, consisting of NdMg12, NdMg2Ni, Mg2Ni and Ni phases and the addition of catalyst CeO2 prompted the composites to be partly transformed into amorphous strucutre. The CeO2 improved the maxi-mum hydrogen capacity of Nd2Mg17-50 wt.%Ni alloy from 3.192 wt.% to 3.376 wt.% (x=1.0). What’s more, the increment of diffu-sion coefficientD led to the faster hydriding kinetics, which was calculated by Avrami-Erofeev equation. The dehydrogenation tem-perature reduced from 515.54 to 504.72 K was mainly caused by the decrease of activation energy from 93.28 to 69.36 kJ/mol, which was proved by the Kissinger equation.

  20. Oxidation and reduction behaviors of a prototypic MgO-PuO2-x inert matrix fuel

    Miwa, Shuhei; Osaka, Masahiko


    Oxidation and reduction behaviors of prototypic MgO-based inert matrix fuels (IMFs) containing PuO2-x were experimentally investigated by means of thermogravimetry. The oxidation and reduction kinetics of the MgO-PuO2-x specimen were determined. The oxidation and reduction rates of the MgO-PuO2-x were found to be low compared with those of PuO2-x. It is note that the changes in O/Pu ratios of MgO-PuO2-x from stoichiometry were smaller than those of PuO2-x at high oxygen partial pressure.

  1. Hydrogen production from steam reforming of ethanol over Ni/MgO-CeO_2 catalyst at low temperature

    石秋杰; 刘承伟; 谌伟庆


    MgO,CeO2 and MgO-CeO2 with different mole ratio of Mg:Ce were prepared by solid-phase burning method.Catalysts Ni/MgO,Ni/CeO2 and Ni/MgO-CeO2 were prepared by impregnation method.The catalytic properties were evaluated in ethanol steam reforming(ESR) reaction.Specific surface areas of the supports were measured by nitrogen adsorption-desorption at 77 K,and the catalysts were characterized with X-ray diffraction(XRD),temperature programmed reduction(TPR) and thermogravimetric(TG).The results showed that well...

  2. Ti-Mg alloy powder synthesis via mechanochemical reduction of TiO 2 by elemental magnesium

    Mushove, T


    Full Text Available This paper reports the preliminary results of an investigation on the synthesis of a Ti-Mg alloy powder through mechanochemical processing of TiO 2 and Mg powders. TiO 2 was mixed with elemental Mg according to a nominal stoichiometric composition...

  3. Polar catastrophe at the MgO(100)/SnO2(110) interface

    Albar, Arwa


    First principles calculations, based on density functional theory, are used to investigate the structural and electronic properties of the epitaxial MgO(100)/SnO2(110) interface of wide band gap insulators. Depending on the interface termination, nonmagnetic metallic and half-metallic interface states are observed. The formation of these states is explained by a polar catastrophe model for nonpolar-polar interfaces. Strong lattice distortions and buckling develop in SnO2, which influence the interface properties as the charge discontinuity is partially screened. Already a single unit cell of SnO2 is sufficient to drive the polar catastrophe scenario. © 2016 The Royal Society of Chemistry.

  4. Fabrication of Mg2Si/AZ91D Composites from Mg-SiO2%Mg-SiO2体系制备Mg2Si/AZ91D复合材料的研究

    王军; 陈刚; 赵玉涛; 徐萌; 张道理; 黄康; 彭蕾


    采用原位合成技术制备了Mg2Si/AZ91D复合材料, 并通过光学显微镜(OM)、扫描电镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)等对添加碱土、稀土元素的影响进行了研究. 结果表明: AZ91D镁合金中加入SiO2(其中Si占合金质量的3%)后, 出现多边形状或树枝晶状的初生Mg2Si相, 以及汉字状的共晶Mg2Si相, 树枝晶状Mg2Si的平均尺寸约25~50 μm, 汉字状Mg2Si的平均尺寸约12~15 μm;Mg2Si对镁合金中的β-Mg17Al12相有细化作用. 添加Ca, Sr, Y对Mg2Si形貌、尺寸有明显的改善, 当添加0.9%Ca, 0.1%Sr, 0.5%RE(80%Y)变质处理后, Mg2Si形貌全部变为多边形状, 平均尺寸约0.8~5 μm.

  5. Synthesis, structural properties and catalytic activity of MgO-SnO2 nanocatalysts

    Perveen, Hina; Farrukh, Muhammad Akhyar; Khaleeq-ur-Rahman, Muhammad; Munir, Badar; Tahir, Muhammad Ashraf


    Surfactant controlled synthesis of magnesium oxide-tin oxide (MgO-SnO2) nanocatalysts was carried out via the hydrothermal method. Concentration of sodium dodecyl sulfate (SDS) was varied while all other reaction conditions were kept constant same for this purpose. Furthermore, MgO-SnO2 nanocatalysts were also prepared by changing the precursor's concentration. These precursors are magnesium nitrate Mg(NO3)2 · 6H2O and tin chloride (SnCl4 · 5H2O). The influence of these reaction parameters on the sizes and morphology of the nanocatalysts were studied by using Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy-Energy dispersive X-ray (SEM-EDX), Powder X-ray diffraction (XRD), Transmission electron microscopy and Thermo gravimetric analysis (TGA). The catalytic efficiency of MgO-SnO2 was checked against 2,4-dinitrophenylhydrazine (DNPH), which is an explosive compound. The nanocatalysts were found as a good catalyst to degrade the DNPH. Catalytic activity of nanocatalysts was observed up to 19.13% for the degradation DNPH by using UV-spectrophotometer.

  6. Making MgO/SiO2 Glasses By The Sol-Gel Process

    Bansal, Narottam P.


    Silicon dioxide glasses containing 15 mole percent magnesium oxide prepared by sol-gel process. Not made by conventional melting because ingredients immiscible liquids. Synthesis of MgO/SiO2 glass starts with mixing of magnesium nitrate hexahydrate with silicon tetraethoxide, both in alcohol. Water added, and transparent gel forms. Subsequent processing converts gel into glass. Besides producing glasses of new composition at lower processing temperatures, sol-gel method leads to improved homogeneity and higher purity.

  7. Auto-combustion synthesis and characterization of Mg doped CuAlO2 nanoparticles

    Agrawal, Shraddha; Parveen, Azra; Naqvi, A. H.


    The synthesis of pure and Mg doped Copper aluminumoxide CuAlO2nanoparticles, a promising p-type TCO (transparent conducting oxide) have been done bysol gel auto combustion method using NaOH as a fuel, calcinated at 600°C. The structural properties were examined by XRD and SEM techniques. The optical absorption spectra of CuAlO2 sample recorded by UV-VIS spectrophotometer in the range of 200 to 800 nm have been presented. The crystallite size was determined by powder X-ray diffraction technique. The electrical behavior of pure and Mg doped CuAlO2 has been studied over a wide range of frequencies by using complex impedance spectroscopy.The variation of a.c. conductivity has been studied as function of frequency and temperature. The data taken together conclude that doping causes decreases in the ac conductivity of the nanoparticles as compared with the pure nanoparticles. Mg doping affects the optical properties and band gap.

  8. Synthesis, Characterization and Photocatalytic Activity of Mg-Impregnated ZnO-SnO2 Coupled Nanoparticles.

    Behnajady, Mohammad A; Tohidi, Yasamin


    ZnO-SnO2 nanoparticles were prepared by coprecipitation method; then Mg, with different molar ratios and calcination temperatures, was loaded on the coupled nanoparticles by impregnation method. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), and Brunauer-Emmett-Teller (BET) techniques. Based on XRD results, the ZnO-SnO2 and Mg/ZnO-SnO2 nanoparticles were made of ZnO and SnO2 nanocrystallites. According to DRS spectra, the band gap energy value of 3.13 and 3.18 eV were obtained for ZnO-SnO2 and Mg/ZnO-SnO2 nanoparticles, respectively. BET analysis revealed a Type III isotherm with a microporous structure and surface area of 32.051 and 49.065 m(2)  g(-1) for ZnO-SnO2 and Mg/ZnO-SnO2 , respectively. Also, the spherical shape of nanocrystallites was deduced from TEM and FESEM images. The photocatalytic performance of pure ZnO-SnO2 and Mg/ZnO-SnO2 was analyzed in the photocatalytic removal of methyl orange (MO). The results indicated that Mg/ZnO-SnO2 exhibited superior photocatalytic activity to bare ZnO-SnO2 photocatalyst due to high surface area, increased MO adsorption and larger band gap energy. Maximum photocatalytic activity of Mg/ZnO-SnO2 nanoparticles was obtained with 0.8 mol% Mg and calcination temperature of 350°C.

  9. Integrated Mg/TiO2-ionic liquid system for deep desulfurization

    Yin, Yee Cia; Kait, Chong Fai; Fatimah, Hayyiratul; Wilfred, Cecilia


    A series of Mg/TiO2 photocatalysts were prepared using wet impregnation method followed by calcination at 300, 400 and 500°C for 1 h. The photocatalysts were characterized using Thermal Gravimetric Analysis, Fourier-Transform Infrared Spectroscopy, X-Ray Diffraction, and Field Emission Scanning Electron Microscopy. The performance for deep desulfurization was investigated using model oil with 100 ppm sulfur (in the form of dibenzothiophene). The integrated system involves photocatalytic oxidation followed by ionic liquid-extraction processes. The best performing photocatalyst was 0.25wt% Mg loaded on titania calcined at 400°C (0.25Mg400), giving 98.5% conversion of dibenzothiophene to dibenzothiophene sulfone. The highest extraction efficiency of 97.8% was displayed by 1,2-diethylimidazolium diethylphosphate. The overall total sulfur removal was 96.3%.

  10. Study on the Characteristics of SiO2 Distribution and Silicate Phases in MgO—ZrO2 Composites

    ZHUBoquan; GANFeifang; 等


    This work studied the characteristics of SiO2 distribution and structure of silicate phases in MgO-ZrO2 composites synthesizedby raw materials of light fired magnesite nd zircon,The results indicate that 30 wt%-40wt% SiO2 content in the system is existed in the form of crystalline of forsterite (M2S),the remaindering of SiO content (60wt%0-70wt%) is existed in the glass phase,The chemical composition of glass phase is well agreed with the chemical composition of monticellite(CMS).

  11. In vitro reactivity of Na2O MgO SiO2 glasses

    Roy, Debdas


    A variety of bioactive glasses have been investigated over the last two decades as substitute material for diseased or damaged tissues in a human body. In this investigation, three different melt derived bioactive glasses, each having 55% by mole SiO2 and ratio of MgO to Na2O varying from 1:8 to 8:1, were prepared by melting various oxides at temperature >1250 °C. After microstructure evolution, vitro reactivity of these glasses was examined by keeping them in simulated body fluid (trans buffered pH 7.25 at 25 cc). The surface reactivity of these glasses gradually increased with increasing Na2O/MgO ratio.

  12. Effect of TiO2 Concentration on Properties of MgO - TiO2 - Al2O3 Clinker%TiO2加入量对MgO - TiO2-Al2O3系熟料特性的影响

    高宏适; 全荣



  13. Mg3(VO4)2-MgO-ZrO2 nano-catalysts for oxidative dehydrogenation of n-butane.

    Lee, Jong Kwon; Seo, Hyun; Hong, Ung Gi; Yoo, Yeonshick; Cho, Young-Jin; Lee, Jinsuk; Park, Gle; Chang, Hosik; Song, In Kyu


    A series of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts with different vanadium content (X = 3.3, 5.3, 7.0, 10.2, and 13.4) were prepared by a single-step citric acid-derived sol-gel method for use in the oxidative dehydrogenation of n-butane to n-butene and 1,3-butadiene. The effect of vanadium content of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts on their physicochemical properties and catalytic activities in the oxidative dehydrogenation of n-butane was investigated. Successful formation of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts was confirmed by XRD, Raman spectroscopy, and ICP-AES analyses. The catalytic performance of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts strongly depended on vanadium content. All the X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts showed a stable catalytic performance without catalyst deactivation during the reaction. Among the catalysts tested, 7.0-Mg3(VO4)2-MgO-ZrO2 nano-catalyst showed the best catalytic performance in terms of yield for total dehydrogenation products (TDP, n-butene and 1,3-butadiene). TPRO (temperature-programmed reoxidation) experiments were carried out to measure the oxygen capacity of the catalyst. Experimental results revealed that oxygen capacity of the catalyst was closely related to the catalytic performance. Yield for TDP increased with increasing oxygen capacity of the catalyst.

  14. Design and preparation of binary-binary SnO2-ZnO:F/MgF2/SiO2 transparent conducting oxide coatings

    S Hadavi


    Full Text Available   In this study, we prepared the binary-binary TCO compounds of SnO2-ZnO by the spray pyrolysis technique. We also investigated the role of MgF2/SiO2 antireflection coatings in reducing optical reflectance in the visible region of TCO. Before preparation , we simulated the optical transmition of the films for optimizing the layer thicknesses. The results of this study showed increasing of optical transmittance in the visible region of TCO by adding antireflection coating layers.

  15. Property Research on MgO-CaO-ZrO2 Castable

    HU Sihai; ZHU Boquan; HONG Xueqin


    Studies were conducted on how the structure and property of magnesia castable was affected when the magnesia zirconia calcium composite was incorporated. The experimental result indicates that the component CaZrO3 is easily decomposed by reacting with silica fume to form a low melting point material CMS and CaZr4O9 in the silica fume bonded MgO castable, resulting in occurrence of microcracks, which will improve the thermal shock resistance and strength at moderate temperature. In a word, CaZrO3 improves slag infiltration resistance in spite of lowering the slag corrosion resistance, by absorbing and reacting with components in the slag like Al2O3, TiO2 and FeO.

  16. Sintering oxide ceramics based on AI2O3 and ZrO2, activated by MgO, TiO2 and SiO2 additives

    Matrenin, S. V.; Zenin, B. S.; Tayukin, R. V.


    The positive effect of the addition of MgO and TiO2 in an amount of no more than 1 wt. % on sintering and physico-mechanical properties of alumina ceramics is established. Addition of 5% of SiO2 to A12O3 provides the mechanism of liquid phase sintering of ceramics, which leads to increase in its density and strength up to 480 MPa. In ceramic system A12O3 - ZrO2 - Y2O3 highest level of physical and mechanical properties of the composition had a hypereutectic composition 16.6% A12O3 - 76% Z1O2 - 7.4% Y2O3. In this composition two mechanisms of hardening are realized simultaneously, such as transformational hardening by t- m - ZrO2 transition and dispersion strengthening with high-modulus particles of α- A12O3.

  17. ZrO2包覆CaO-MgO-SiO2陶瓷纤维的制备及其性能%Preparation and properties of ZrO2 coated CaO-MgO-SiO2 ceramic fiber

    刘浩; 王玺堂; 王周福; 张保国


    为了解决CaO-MgO-SiO2陶瓷纤维在使用过程中析晶、粉化的问题,采用非均相成核法在CaO-MgO-SiO2陶瓷纤维表面制备了ZrO2涂层.用场发射扫描电子显微镜观察ZrO2包覆层,用X射线衍射仪分析800和1 000℃热处理后原始纤维和ZrO2包覆纤维的晶相变化,并检测了二者在模拟肺液中的溶解性能.结果表明:包覆处理后,CaO-MgO-SiO2陶瓷纤维表面形成了一层ZrO2包覆层;ZrO2包覆层的存在可以显著抑制800℃时纤维的析晶,1000℃时只能抑制纤维中方石英的析出,对其他物相的析晶没有明显抑制作用;ZrO2包覆层的存在降低了纤维在模拟肺液中的早期溶解速率,但对纤维的长期生物可溶性影响不大.%In order to inhibit the crystallization and pulverization of CaO-MgO-SiO2 ceramic fiber at high temperatures,the ZrO2 coating on CaO-MgO-SiOj ceramic fiber was formed by heterogeneous-nucleation method. The crystal phase compositions of the original fiber and ZrO2 coated fiber fired at 800 °C and 1 000 °C were analyzed by X-ray diffractometer.and their solubility in Gamble solution was determined. The results show that; (1) a dense ZrO2 coating is formed on the surface of fiber; (2) the coating on fiber can inhibit the precipitation of crystals at 800 °C markedly and at 1 000 °C it only can inhibit the precipitation of cristobalite and has little effects on other crystal phases; (3) the coating decreases the initial dissolution rate of the fiber in Gamble solution and has little effect on long-term bio-solubility of fiber.

  18. Study on Mg-PSZ Ceramics Doped with Y2O3 and CeO2


    Mg-PSZ ceramics doped with Y2O3 and CeO2 was prepared using traditional processing method. The fine-grain PSZ ceramics(dc≤10 μm) sintered at low temperature(≤1550 ℃) was obtained by means of composition design. The effects of co-stabilization of Y2O3, CeO2 and annealing at 1100 ℃ on material composition, microstructure and mechanical properties were studied. The results show that Y2O3 and CeO2 during annealing at 1100 ℃ can inhibit subeutectoid decomposition reaction effectively, and optimize nucleation and growth of t-ZrO2 precipitates in c-ZrO2 matrix phase. The materials show transgranular and intergranular fracture characteristics, and exhibit better mechanical properties owing to the cooperative effect of stress-induced transformation toughening and microcrack toughening.

  19. Reforming of Ethanol to Produce Hydrogen over PtRuMg/ZrO2 Catalyst

    Josh Y. Z. Chiou


    Full Text Available A modified PtRu/ZrO2 catalyst with Mg is evaluated for the oxidative steam reforming of ethanol (OSRE and the steam reforming of ethanol (SRE. In order to understand the variation in the reaction mechanism on OSRE and SRE, further analysis of both fresh and used catalyst is concentrated on for TEM, TG, Raman, and TPR characterization. The results show that the OSRE reaction requires a higher temperature (∼390°C to achieve 100% ethanol conversion than the SRE reaction (∼2500°C. The distribution of CO is minor for both reactions (< 5% for OSRE, < 1% for SRE. This demonstrates that the water gas shift (WGS reaction is an important side-reaction in the reforming of ethanol to produce H2 and CO2. A comparison of the temperature of WGS (WGS shows it is lower for the SRE reaction (WGS∼250°C for SRE, ~340°C for OSRE.

  20. Effect of Pore Size Distribution on Humidity Sensing Properties of MgO doped ZrO2-TiO2 Ceramic

    Jain, M. K.; Bhatnagar, M. C.; Sharma, G. L.


    The MgO doped ZrO2-TiO2 composite is studied for its humidity sensing characteristics. Though dc electrical properties show very high sensitivity to humidity, it is not useful for practical applications because of the charging effect. The ac conductivity vs relative humidity characteristics of the pellet becomes linear with an increase in sintering temperature. The post treatment at high temperature and high humidity is found to accelerate initial ageing of the pellet and therefore, stabilizes the characteristics more quickly. A physical model has been proposed to correlate initial ageing, effect of sintering temperature and response time with pore size distribution. Pores below 300 Å radii are present in abundance near the ZrTiO4 phase formation temperature. These pores are responsible for higher sensitivity in low humidity region and linear characteristics.

  1. Slao corrosion resistance of MaO-MaAI2O4-ZrO2 series materials%MgO-MgAl2O4-ZrO2系材料的抗渣性研究

    高杰; 李友胜; 韩兵强; 李楠


    MgO-MgAl204 specimen,MgO-ZrO2 specimen,and MgO-MgAl204-ZrO2 specimen were prepared using magnesite powder (d50=6.62μm),m-ZrO2 micropowder (d50=3.99μm) and α-Al203 micropowder (d50=1.89 μm) as starting materials by semi-dry pressing and firing at 1 600 C for 3 h. The permanent linear change on heating, apparent porosity, bulk density, slag corrosion resistance, and slag penetration resistance of the specimens were determined. Slag resistance of specimens was analyzed using thermodynamic software Factsage6.1. The results show that: ( 1 ) MgO-ZrO2 material has better sintering ability than MgOMgAl2O4 material and MgO-MgAl2O4-ZrO2 material; (2) when adding ZrO2 into MgO-MgAl204 material ,the slag corrosion resistance is improved and the slag penetration resistance is poor ,which is mainly resulted from relatively loose microstructure of the specimens and the penetration of Fe3+ and Mg2+ in the slag;(3)experimental results are in good agreement with thermodynamic simulation results.%以菱镁矿粉(d=6.62 μm)、m-ZrO微粉(d=3.99μm)、α-AlO微粉(d=1.89μm)为原料,采用半干法成型,于1 600 ℃保温3 h烧成后制成MgO-MgAlO、MgO-ZrO和MgO-MgAlO-ZrO质试样,检测试样的加热永久线变化率、显气孔率、体积密度、抗渣侵蚀性、抗渣渗透性,并利用Factsage6.1热力学软件对试样的抗渣性进行了分析.结果表明:1.MgO-ZrO材料的烧结性能优于MgO-MgAlO材料及MgO-MgAlO-ZrO材料;2.在MgO-MgAIO材料中引入ZrO,有利于提高其抗渣侵蚀性,但抗渣渗透性较差,主要同试样的组织结构相对疏松及熔渣中的Fe和Mg的渗透有关;3)试验结果与热力学模拟结果吻合较好.

  2. Network structure of SiO2 and MgSiO3 in amorphous and liquid States

    Lan, Mai Thi; Thuy Duong, Tran; Viet Huy, Nguyen; Van Hong, Nguyen


    Network structure of SiO2 and MgSiO3 at 300 K and 3200 K is investigated by molecular dynamics simulation and visualization of simulation data. Structural organization of SiO2 and MgSiO3 is clarified via analysis the short range order (SRO) and intermediate range order (IRO). Network topology is determined via analyzing the bond between structural units, the cluster of structural units as well as spatial distribution of structural units. The polyamorphism as well as structural and dynamic heterogeneities are also discussed in this work.

  3. Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

    Sasani, Alireza [Department of Science, Karaj Islamic Azad University, Karaj, Alborz, P.O. Box 31485-313 (Iran, Islamic Republic of); Baktash, Ardeshir [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Mirabbaszadeh, Kavoos, E-mail: [Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, P. O. Box 15875-4413 (Iran, Islamic Republic of); Khoshnevisan, Bahram [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of)


    Highlights: • Formation energy of Mg and Mg-Nb co-doped TiO{sub 2} anatase surface (101) is studied. • Effect of Mg defect to the TiO{sub 2} anatase (101) surface and bond length distribution of the surface is studied and it is shown that Mg defects tend to stay far from each other. • Effect of Mg and Nb to the bond length distribution of the surface studied and it is shown that these defects tend to stay close to each other. • Effects of Mg and Mg-Nb defects on DSSCs using TiO{sub 2} anatase hosting these defects are studied. - Abstract: In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO{sub 2} anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO{sub 2} surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase J{sub SC} of the surface while slightly decreasing V{sub OC} compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

  4. Design and fabrication of SiO2/TiO2 and MgO/TiO2 based high selective optical filters for diffuse reflectance and fluorescence signals extraction.

    Pimenta, S; Cardoso, S; Miranda, A; De Beule, P; Castanheira, E M S; Minas, G


    This paper presents the design, optimization and fabrication of 16 MgO/TiO2 and SiO2/TiO2 based high selective narrow bandpass optical filters. Their performance to extract diffuse reflectance and fluorescence signals from gastrointestinal tissue phantoms was successfully evaluated. The obtained results prove their feasibility to correctly extract those spectroscopic signals, through a Spearman's rank correlation test (Spearman's correlation coefficient higher than 0.981) performed between the original spectra and the ones obtained using those 16 fabricated optical filters. These results are an important step for the implementation of a miniaturized, low-cost and minimal invasive microsystem that could help in the detection of gastrointestinal dysplasia.

  5. Synthesis of Y2O2S:Eu3+, Mg2+, Ti4+ hollow microspheres via homogeneous precipitation route

    Peng-Fei Ai, Ying-Liang Liu, Li-Yuan Xiao, Hou-Jin Wang and Jian-Xin Meng


    Full Text Available A phosphorescent material in the form of Y2O2S:Eu3+, Mg2+, Ti4+ hollow microspheres was prepared by homogeneous precipitation using monodispersed carbon spheres as hard templates. Y2O3:Eu3+ hollow microspheres were first synthesized to serve as the precursor. Y2O2S:Eu3+, Mg2+, Ti4+ powders were obtained by calcinating the precursor in a CS2 atmosphere. The crystal structure, morphology and optical properties of the composites were characterized. X-ray diffraction measurements confirmed the purity of the Y2O2S phase. Electron microscopy observations revealed that the Y2O2S:Eu3+, Mg2+, Ti4+ particles inherited the hollow spherical shape from the precursor after being calcined in a CS2 atmosphere and that they had a diameter of 350–450 nm and a wall thickness of about 50–80 nm. After ultraviolet radiation at 265 or 325 nm for 5 min, the particles emitted strong red long-lifetime phosphorescence originating from Eu3+ ions. This phosphorescence is associated with the trapping of charge carriers by Ti4+ and Mg2+ ions.

  6. Experimental constraints on melting temperatures in the MgO-SiO2 system at lower mantle pressures

    Baron, Marzena A.; Lord, Oliver T.; Myhill, Robert; Thomson, Andrew R.; Wang, Weiwei; Trønnes, Reidar G.; Walter, Michael J.


    Eutectic melting curves in the system MgO-SiO2 have been experimentally determined at lower mantle pressures using laser-heated diamond anvil cell (LH-DAC) techniques. We investigated eutectic melting of bridgmanite plus periclase in the MgO-MgSiO3 binary, and melting of bridgmanite plus stishovite in the MgSiO3-SiO2 binary, as analogues for natural peridotite and basalt, respectively. The melting curve of model basalt occurs at lower temperatures, has a shallower dT / dP slope and slightly less curvature than the model peridotitic melting curve. Overall, melting temperatures detected in this study are in good agreement with previous experiments and ab initio simulations at ∼25 GPa (Liebske and Frost, 2012; de Koker et al., 2013). However, at higher pressures the measured eutectic melting curves are systematically lower in temperature than curves extrapolated on the basis of thermodynamic modelling of low-pressure experimental data, and those calculated from atomistic simulations. We find that our data are inconsistent with previously computed melting temperatures and melt thermodynamic properties of the SiO2 endmember, and indicate a maximum in short-range ordering in MgO-SiO2 melts close to Mg2SiO4 composition. The curvature of the model peridotite eutectic relative to an MgSiO3 melt adiabat indicates that crystallization in a global magma ocean would begin at ∼100 GPa rather than at the bottom of the mantle, allowing for an early basal melt layer. The model peridotite melting curve lies ∼ 500 K above the mantle geotherm at the core-mantle boundary, indicating that it will not be molten unless the addition of other components reduces the solidus sufficiently. The model basalt melting curve intersects the geotherm at the base of the mantle, and partial melting of subducted oceanic crust is expected.

  7. Decaying shock studies of phase transitions in MgOSiO2 systems: implications for the Super-Earths interiors

    Bolis, R M; Vinci, T; Ravasio, A; Bambrink, E; Guarguaglini, M; Koenig, M; Musella, R; Remus, F; Bouchet, J; Ozaki, N; Miyanishi, K; Sekine, T; Sakawa, Y; Sano, T; Kodama, R; Guyot, F; Benuzzi-Mounaix, A


    We report an experimental study of the phase diagrams of periclase (MgO), enstatite (MgSiO3) and forsterite (Mg2SiO4) at high pressures. We investigated with laser driven decaying shocks the pressure/temperature curves of MgO, MgSiO3 and Mg2SiO4 between 0.2-1.2 TPa, 0.12-0.5 TPa and 0.2-0.85 TPa respectively. A melting signature has been observed in MgO at 0.47 TPa and 9860 K, while no phase changes were observed neither in MgSiO3 nor in Mg2SiO4. An increasing of reflectivity of MgO, MgSiO3 and Mg2SiO4 liquids have been detected at 0.55 TPa -12 760 K, 0.15 TPa - 7540 K, 0.2 TPa - 5800 K, respectively. In contrast to SiO2, melting and metallization of these compounds do not coincide implying the presence of poor electrically conducting liquids close to the melting lines. This has important implications for the generation of dynamos in Super-earths mantles.

  8. Synthesis and characterization of sodium cation-conducting Nax(MyL1-yO2 (M = Ni2+, Fe3+; L = Ti4+, Sb5+

    Marques, F. M. B.


    Full Text Available The Na+-conducting ceramics of layered Na0.8Ni0.4Ti0.6O2, Na0.8Fe0.8Ti0.2O2, Na0.8Ni0.6Sb0.4O2 (structural type O3 and Na0.68Ni0.34Ti0.66O2 (P2 type with density higher than 91% were prepared via the standard solid-state synthesis route and characterized by the impedance spectroscopy, thermal analysis, scanning electron microscopy, structure refinement using X-ray powder diffraction data, measurements of Na+ concentration cell e.m.f., and dilatometry. The conductivity of antimonate Na0.8Ni0.6Sb0.4O2, synthesized first time, was found lower than that of isostructural Na0.8Ni0.4Ti0.6O2 due to larger ion jump distance between Na+ sites. At temperatures above 420 K, transport properties of sodium cationconducting materials are essentially independent of partial water vapor pressure. In the low-temperature range, the conductivity reversibly increases with water vapor pressure varied in the range from approximately 0 (dry air up to 0.46 atm. The sensitivity to air humidity is influenced by the ceramic microstructure, being favored by increasing boundary area. The average thermal expansion coefficients of layered materials at 300-1173 K are in the range (13.7-16.0×10-6 K-1.Se han preparado cerámicas conductoras conteniendo Na+ de composición Na0.8Ni0.4Ti0.6O2, Na0.8Fe0.8Ti0.2O2, Na0.8Ni0.6Sb0.4O2 (tipo estructural O3 y Na0.68Ni0.34Ti0.66O2 (tipo P2 con densidad mayor del 91%. Las vía de preparación fu la ruta de estandard de síntesis en estado sólido. Las composiciones se caracterizaron mediante espectroscopía de impedancia, análisis térmico, microscopía electrónica de barrido, refinamiento de la estructura usando datos de difracción de rayos X en polvo, medidas de concentración de Na+, f.e.m. de la célula y dilatometría. La conductividad del antimoniate, sintetizado por primera vez, Na0.8Ni0.6Sb0.4O2, era menor que la del compuesto isoestructural Na0.8Ni0.4Ti0.6O2 debido a la mayor distancia de salto iónico entre las posiciones de Na

  9. Fabrication and Properties of 3Y-TZP/ZrO2 / Al2O3/MgO Ceramics


    Studies on the sintering, microstructure, mechanical properties and low temperature degradation behavior of yttria stabilized-tetragonal zirconia polycrystal (3Y-TZP) were carried out. The results show that the addition of Al2O3 and MgO improve the sintering at low temperatures, and cause exaggerated grain growth and the transformation of tetragonal-ZrO2 to monoclinic-ZrO2 with corresponding changes in the mechanical properties. The addition of the yttria-free monoclinic zirconia particles change the overall yttria distribution and induce an active transformation toughening mechanism. Furthermore, the dispersed yttria-free ZrO2 can inhibit the tetragonal zirconia transformarion, which is beneficial to the improvement of the low temperature degradation behavior of 3Y-TZP ceramics.

  10. Role of MgO in WO3/SiO2-catalyzed olefin metathesis reaction%MgO在WO3/SiO2催化烯烃歧化反应中的作用

    徐峰; 姜伟丽; 李沛东; 周广林; 周红军


    This paper reviews the progress of heterogeneous W-based catalysts used for olefin metathesis and introduces the research progress of olefin metathesis catalyst and metathesis reaction mechanism. This review focuses on the role of MgO aid in WO3/SiO2 catalytic propylene metathesis reaction,such as generating active gas-phase“excited species”,promoting double bond isomerization, adjusting acidity to reduce side effects and adsorbing poisons to purify the raw material,etc. In addition,this paper also presents the research trend of heterogeneous MgO-WO3/SiO2 metathesis catalysts to provide guidance and reference for development of highly active MgO-WO3/SiO2 catalytic systems.%综述了负载型钨基催化剂用于烯烃歧化领域的研究情况,简要介绍了烯烃歧化催化剂的研究进展以及歧化反应机理,着重介绍了 MgO 助剂在 WO3/SiO2催化的丙烯歧化反应中的作用,如生成活性的气相激发物种、促进1-丁烯异构成2-丁烯、调节酸性以减少副反应以及吸附毒物净化原料等,并对MgO在歧化体系中的作用机理问题进行了部分探讨。此外,还提出了共催化体系的研究趋势,希望能对以后开发高活性的 MgO-WO3/SiO2共催化体系提供有益的指导和参考依据。

  11. Fabrication and microstructure of nanostructured Mg-3Ni-2MnO_2 by ball milling in hydrogen atmosphere

    FANG Wen-bin; FANG Wa; SUN Hong-fei; YU Zhen-xing


    Nanostructured Mg-3Ni-2MnO_2 was synthesized by ball milling elemental powders of Mg, Ni and MnO_2 in hydrogen atmosphere. The microstructures of the powder prepared at different milling time were analyzed by X-ray diffractometry(XRD), scanning electron microscopy(SEM) and high resolution electron microscopy(HREM). The milling time is the most key parameter impacting on the grain size and the microstructure of material. With prolonging the milling time, particle size becomes smaller and smaller. But after the ball milling time reaches about 20 h, reduction of grain size becomes slowly. When the milling time is more than 50 h, nanocrystailine fully forms. When the milling time is more than 80 h, there are more amorphous phases in materials. The average particle diameter of material is about 1 μm and the grain size is 10-30 nm.

  12. Competition between insertion of Li+ and Mg2+: An example of TiO2-B nanowires for Mg rechargeable batteries and Li+/Mg2+ hybrid-ion batteries

    Meng, Yuan; Wang, Dashuai; Wei, Yingjin; Zhu, Kai; Zhao, Yingying; Bian, Xiaofei; Du, Fei; Liu, Bingbing; Gao, Yu; Chen, Gang


    Titanium dioxide bronze (TiO2-B) nanowires were prepared by the hydrothermal method and used as the positive electrode for Mg rechargeable batteries and Li+/Mg2+ hybrid-ion batteries. First-principles calculations showed that the diffusion barrier for Mg2+ (0.6 eV) in the TiO2-B lattice was more than twice of that for Li+ (0.3 eV). Electrochemical impedance spectroscopy showed that the charge transfer resistance of TiO2-B in the Mg2+ ion electrolyte was much larger than that in the Li+/Mg2+ hybrid electrolyte. For these reasons, the Mg rechargeable battery showed a small discharge capacity of 35 mAh g-1 resulting from an electrochemical double-layer capacitive process. In comparison, the TiO2-B nanowires exhibited a large capacity (242 mAh g-1 at the 20 mA g-1 current density), high rate capability (114 mAh g-1 at 1 A g-1), and excellent cycle stability in the Li+/Mg2+ hybrid-ion battery. The dominant reaction occurred in the TiO2-B electrode was intercalation of Li+ ions, of which about 74% of the total capacity was attributed to Li+ pseudo-capacitance.

  13. Role of chemical interaction between MgH2 and TiO2 additive on the hydrogen storage behavior of MgH2

    Pukazhselvan, D.; Nasani, Narendar; Sandhya, K. S.; Singh, Budhendra; Bdikin, Igor; Koga, Nobuaki; Fagg, Duncan Paul


    The present study explores how the additive titania chemically reacts with magnesium hydride and influences the dehydrogenation of MgH2. Quantitative X - ray diffraction study of ball milled MgH2 + xTiO2 (x = 0.25, 0.33, 0.5 and 1) suggests that Ti substituted MgO is the main reaction product in all the product powders. Convincing evidence is obtained to conclude that Ti dissolution in MgO makes a dramatic behavioral change to MgO; passive MgO turns as an active in-built catalyst. The analysis correlating the dehydrogenation kinetics, composition of in-situ catalyst and sample durability suggests that effectiveness of Ti substituted MgO (MgxTiyOx+y) as a catalyst for MgH2 depends on the concentration of Ti in MgxTiyOx+y rock salt. These observations are immensely helpful for understanding the hydrogen desorption mechanism of metal oxide additives loaded MgH2 system.

  14. Study of Optical Humidity Sensing Properties of Sol-Gel Processed TiO2 and MgO Films

    B. C. Yadav


    Full Text Available Paper reports a comparative study of humidity sensing properties of TiO2 and MgO films fabricated by Sol-gel technique using optical method. One sensing element of the optical humidity sensor presented here consists of rutile structured two-layered TiO2 thin film deposited on the base of an isosceles glass prism. The other sensing element consists of a film of MgO deposited by same technique on base of the prism. Light from He-Ne laser enters prism from one of refracting faces of the prism and gets reflected from the glass-film interface, before emerging out from its other isosceles face. This emergent beam is allowed to pass through an optical fiber. Light coming out from the optical fiber is measured with an optical power meter. Variations in the intensity of light caused by changes in humidity lying in the range 5%RH to 95%RH have been recorded. MgO film shows better sensitivity than TiO2 film.

  15. Influence of mechanical activation on synthesis and properties of the MgO-TiO2 system

    Petrović Vera V.


    Full Text Available Materials applied in electronics such as multilayer capacitors are an important field of ceramic materials. Magnesium titanate based dielectric materials are used for producing type-I capacitors. A common way of obtaining this material is a solid-state reaction during reaction sintering. The process of sintering can be enhanced if mechanical activation precedes. In this work starting powders of magnesium carbonate (MgCO3 and titanium dioxide (TiO2 with a rutile crystal modification were weighed to attain a 1:1 molar MgCO3:TiO2 ratio. Mechanical activation of the starting mixture was performed by high energy ball milling using ZrO balls and vessels with a ball to powder mass ratio of 40:1. The observed grinding times were 15, 30, 60 and 120 minutes. Powder characterization was conducted using X ray powder diffraction, DTA analysis up to 1000 o C and particle morphology changes were observed with Scanning Electron Microscopy. Isothermal sintering of compacted powders was conducted at 1100ºC during 30, 60 and 180 minutes. For specimens synthesized in such a manner, microwave dielectric properties were measured, quality factor Q, specific electrical resistivity (ρ and the dielectric constant (Єr. In this work we explain the influence of mechanical activation on the MgCO3-TiO2 system leading to titanate formation during sintering, as well as induced changes in microwave dielectric properties.

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

    Bansal, Narottam P.


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

  17. Synthesis of high-surface-area spinel-type MgAl$_2$O$_4$ nanoparticles by [Al(sal)$_2$(H$_2$O)$_2$]$_2$[Mg(dipic)$_2$] and [Mg(H$_2$O)$_6$][Al(ox)$_2$(H$_2$O)$_2$]$_2$·5H$_2$O: influence of inorganic precursor type


    Spinel-type MgAl$_2$O$_4$ nanoparticles with high surface area were synthesized by thermal decomposition of three different ion-pair complexes precursors, including [Mg(H$_2$O)$_6$][Al(dipic)$_2$]$_2$·6H$_2$O, [Al(sal)$_2$(H$_2$O)$_2$]$_2$[Mg(dipic)$_2$] and [Mg(H$_2$O)$_6$][Al(ox)$_2$(H$_2$O)$_2$]$_2$·5H$_2$O. Influence of the inorganic precursor was investigated on synthesis and textural properties of magnesium aluminate nanopowders. The precursors [Mg(H$_2$O)$_6$][Al(dipic)$_2$]$_2$·6H$_2$O and [Al(sal)$_2$(H$_2$O)$_2$]$_2$[Mg(dipic)$_2$] displayed pure spinel-type MgAl$_2$O$_4$, while the sample synthesized by [Mg(H$_2$O)$_6$][Al(ox)$_2$(H$_2$O)$_2$]$_2$·5H$_2$O precursor consisted of MgAl$_2$O$_4$ and MgO. The MgAl$_2$O$_4$ synthesizedvia [Al(sal)$_2$(H$_2$O)$_2$]$_2$[Mg(dipic)$_2$] precursor exhibited higher BET specific surface area (226.7 m$^2$ g$^{−1}$) and smaller particle size than those of the samples obtained from the two other precursors.

  18. Study of structure and antireflective properties of LaF3/HfO2/SiO2 and LaF3/HfO2/MgF2 trilayers for UV applications

    Marszalek, K.; Jaglarz, J.; Sahraoui, B.; Winkowski, P.; Kanak, J.


    The aim of this paper is to study antireflective properties of the tree-layer systems LaF3/HfO2/SiO2 and LaF3/HfO2/MgF2 deposited on heated optical glass substrates. The films were evaporated by the use two deposition techniques. In first method oxide films were prepared by means of e-gun evaporation in vacuum of 5 × 10-5 mbar in the presence of oxygen. The second was used for the deposition of fluoride films. They were obtained by means of thermal source evaporation. Simulation of reflectance was performed for 1M2H1L (Quarter Wavelength Optical Thickness) film stack on an optical quartz glass with the refractive index n = 1.46. The layer thickness was optimized to achieve the lowest light scattering from glass surface covered with dioxide and fluoride films. The values of the interface roughness were determined through atomic force microscopy measurements. The essence of performed calculation was to find minimum reflectance of light in wide ultraviolet region. The spectral dispersion of the refractive index needed for calculations was determined from ellipsometric measurements using the spectroscopic ellipsometer M2000. Additionally, the total reflectance measurements in integrating sphere coupled with Perkin Elmer 900 spectrophotometer were performed. These investigations allowed to determine the influence of such film features like surface and interface roughness on light scattering.

  19. TiO2加入量对替代铬的MgO-TiO2-Al2O3系熟料特性的影响




  20. A Gaseous Acrolein Sensor Based on Cataluminescence Using ZrO2 /MgO Composite.%复合ZrO2/MgO催化发光丙烯醛气体传感器

    刘永慧; 曹小安; 陈福高; 张润坤


    设计了基于在纳米ZrO2中掺杂Mg0的催化发光传感器,以快速检测丙烯醛气体.与纯ZrO2相比,MgO的掺杂量为5%时,丙烯醛的催化发光强度增大了1.8倍,干扰气体乙醛的催化发光强度降为原来的约1/7.传感器在波长425 nm,温度279 ℃,流速200 mL/min条件下,对丙烯醛具有高灵敏度和选择性,发光强度与丙烯醛浓度在5-5000 mL/m3 范围内呈线性关系(r= 0.9996),检出限为1.6 ML/m3,响应时间12 s.浓度均为1000 ML/m3 的10种干扰气体通过传感器时,乙醛、甲醇、苯、甲苯和二甲苯的发光强度分别相当于丙烯醛的6.1%,2.9%,2.5%,2.5%和3.0%,其它气体不产生明显信号.本方法可方便、快速测定空气中丙烯醛气体.%A new cataluminescence (CTL) sensor using nanosized ZrO2 doped with MgO was developed to monitor gaseous acrolein promptly. When the mass content of MgO was about 5%, acrolein CTL intensity over ZrO2/MgO was 1. 8 times higher than that of pure ZrO2, moreover, the CTL intensity of acetaldehyde, a main disturbing material was only about one 7th of pure ZrO2. The proposed sensor showed high sensitivity and selectivity to acrolein at optimal conditions of: tempera-ture at 279 °C , wavelength at 425 nm; and gas flow rate at 200 mL/min. Under the optimal condi-tion, the linear range of the CTL sensor versus acrolein concentration was 5 - 5000 mL/m3 , with a detection limit of 1. 65 mL/m3 and response time of 12 s. Among ten tested species under the concen-tration of 1000 mL/m3, the CTL intensity of acetaldehyde, methanol, benzene, toluene, dimethyl-benzene were only 6. 1%, 2. 9%, 2. 5%, 2. 5%, 3. 0% of acrolein, respectively, while no obvious signal was monitored for the others. The sensor can be applied to facilitate rapid detection of acrolein in the air.

  1. Effect of ZrO2 Additives on the Thermal Shock Resistance of MgO—MA Refractory

    YANGDaoyuan; SUNHongwei; 等


    The additirn of three kins ZrO2-bearing additives into MgO-MA refractory could all increase the latter's C.C.S.and the thermal shock resistance,XRD,polarizing microscope and electron probe analysis were used to analyze the mechanism to improve the thermal shock resistance of the material.The mechanism is that ZrO added into the material improves the microstructure,introduces asppropriate micro cracks into matrix ,enhances the matrix,and therefore increases the thermal shock resistance of ther refractory.

  2. Studies on bare and Mg-doped LiCoO2 as a cathode material for lithium ion batteries

    Reddy, MV


    Full Text Available at ScienceDirect Electrochimica Acta jo ur nal ho me p age: www.elsev ier .com/ locate /e lec tac ta Graphical Abstract Electrochimica Acta xxx (2013) xxx–xxx Studies on Bare and Mg-doped LiCoO2 as a cathode material for Lithium ion Batteries M.V. Reddy... for Lithium ion Batteries M.V. Reddy∗, Thor Wei Jie, Charl J. Jafta, Kenneth I. Ozoemena, Mkhulu K. Mathe, A. Sree Kumaran Nair, Soo Soon Peng, M. Sobri Idris, Geetha Balakrishna, Fabian I. Ezema, B.V.R. Chowdari • Layered compounds, Li...

  3. Harnessing Photovoltage: Effects of Film Thickness, TiO2 Nanoparticle Size, MgO and Surface Capping with DSCs.

    Cheema, Hammad; Delcamp, Jared H


    High photovoltage dye-sensitized solar cells (DSCs) offer an exceptional opportunity to power electrocatalysts for the production of hydrogen from water and the reduction of CO2 to usable fuels with a relatively cost-effective, low-toxicity solar cell. Competitive recombination pathways such as electron transfer from TiO2 films to the redox shuttle or oxidized dye must be minimized to achieve the maximum possible photovoltage (Voc) from DSC devices. A high Voc of 882 mV was achieved with the iodide/triiodide redox shuttle and a ruthenium NCS-ligated dye, HD-2-mono, by utilizing a combined approach of (1) modulating the TiO2 surface area through film thickness and nanoparticle size selection, (2) addition of a MgO insulating layer, and (3) capping available TiO2 film surface sites post film sensitization with an F-SAM (fluorinated self-assembled monolayer) treatment. The exceptional Voc of 882 mV observed is the highest achieved for the popular NCS containing ruthenium sensitizers with >5% PCE and compares favorably to the 769 mV value observed under common device preparation conditions.

  4. Phase equilibria in the systems Fe2O3-MgO-TiO2 and FeO-MgO-TiO2 between 1173 and 1473K, and Fe2+-Mg mixing properties of ilmenite, ferrous-pseudobrookite and ulvöspinel solid solutions

    Pownceby, Mark I.; Fisher-White, Michael J.

    Detailed phase relations have been determined within the systems Fe2O3-MgO-TiO2 and FeO-MgO-TiO2. Experiments were performed over the temperature interval 1173-1473K by equilibrating pelletized, fine-grained oxide mixtures in either inert calcia-stabilized zirconia pots (Fe2O3-MgO-TiO2 system) or evacuated silica tubes (FeO-MgO-TiO2 system). Equilibrium phase assemblages were determined by combined optical microscope, X-ray diffraction and EMP examination. Phase relations in the Fe2O3-MgO-TiO2 ternary are dominated by the instability of the M2O3 solid solution relative to the phase assemblage M3O4+M3O5. A miscibility gap along the M2O3 binary also gives rise to two, 3-phase fields (α-M2O3+M3O5+M3O4 and α'-M2O3+M3O5+M3O4) separated by the M3O4+M3O5 phase field. Phase relations in the FeO-MgO-TiO2 ternary were divided into two sub-systems. For the FeTiO3-MgTiO3-TiO2 sub-ternary, there is complete solid solution along the M2O3 and M3O5 binary joins at high temperature. At low temperatures (TTiO2. Increasing the concentration of MgO in M3O5 phase results in a decrease in the temperature at which M3O5 becomes unstable and compositional tie lines linking M2O3 and TiO2 fan out, before the appearance of a three-phase region where M2O3, M3O5, and TiO2 coexist. Within the expanded FeO-MgO-TiO2 system, at temperatures above 1273K there is a continuous solid solution along the M3O4 binary. At low temperatures (TTiO2 ternary. Assuming a regular solution mixing model for all phases, the M2O3 and M3O4 solid solutions were both found to exhibit moderate positive deviations from ideality ( 2600J/mol), whereas the data for the M3O5 binary suggest close to ideal behaviour.

  5. Mg掺杂TiO2光催化降解孔雀绿染料的研究%Photodegradation of malachite green dye by Mg-doped TiO2

    田菲; 董社英; 马彩莲; 黄廷林


    The treatment of water containing malachite green using Mg-doped TiO2 photocatalyst prepared by a sol-gel method was introduced. The effect of initial concentration of MG,catalyst amount on degradation were studied. The results indicated that Mg-doping remarkably improved the photocatalytic activity of TiO2 for malachite green degradation. The degradation rate of malachite green solution (30 mg/L) reached 84% over Mg-doped TiO2 (1.0 g/L) in 120 min under the irradiation of ultraviolet light, and the catalytic reaction mechanism was forecasted.%采用溶胶-凝胶法制备的Mg掺杂TiO2光催化剂降解孔雀石绿(MG)染料废水,考察了MG初始浓度、催化剂加入量等因素对其降解的影响.结果表明,Mg的掺杂显著提高了TiO2光催化降解孔雀石绿的活性,当催化剂用量为1.0 g/L,经120 min紫外光照射后,可使30 mg/L孔雀石绿溶液降解率达到84%,同时讨论了光催化机制.

  6. Experience melting through the Earth's lower mantle via LH-DAC experiments on MgO-SiO2 and CaO-MgO-SiO2 systems

    Baron, Marzena A.; Lord, Oliver T.; Walter, Michael J.; Trønnes, Reidar G.


    The large low shear-wave velocity provinces (LLSVPs) and ultra-low velocity zones (ULVZs) of the lowermost mantle [1] are likely characterized by distinct chemical compositions, combined with temperature anomalies. The heterogeneities may have originated by fractional crystallization of the magma ocean during the earliest history of the Earth [2,3] and/or the continued accretion at the CMB of subducted basaltic oceanic crust [4,5]. These structures and their properties control the distribution and magnitude of the heat flow at the CMB and therefore the convective dynamics and evolution of the whole Earth. To determine the properties of these structures and thus interpret the seismic results, a good understanding of the melting phase relations of relevant basaltic and peridotitic compositions are required throughout the mantle pressure range. The melting phase relations of lower mantle materials are only crudely known. Recent experiments on various natural peridotitic and basaltic compositions [6-8] have given wide ranges of solidus and liquidus temperatures at lower mantle pressures. The melting relations for MgO, MgSiO3 and compositions along the MgO-SiO2 join from ab initio theory [e.g. 9,10] is broadly consistent with a thermodynamic model for eutectic melt compositions through the lower mantle based on melting experiments in the MgO-SiO2 system at 16-26 GPa [3]. We have performed a systematic study of the melting phase relations of analogues for peridotitic mantle and subducted basaltic crust in simple binary and ternary systems that capture the major mineralogy of Earth's lower mantle, using the laser-heated diamond anvil cell (LH-DAC) technique at 25-100 GPa. We determined the eutectic melting temperatures involving the following liquidus mineral assemblages: 1. bridgmanite (bm) + periclase (pc) and bm + silica in the system MgO-SiO2 (MS), corresponding to model peridotite and basalt compositions 2. bm + pc + Ca-perovskite (cpv) and bm + silica + cpv in the

  7. Super-microporous solid base MgO-ZrO2 composite and their application in biodiesel production

    Su, Jiaojiao; Li, Yongfeng; Wang, Huigang; Yan, Xiaoliang; Pan, Dahai; Fan, Binbin; Li, Ruifeng


    The super-microporous microcrystalline MgO-ZrO2 nanomaterials (pore size 1-2 nm) was prepared successfully via a facile one-pot evaporation-induced self-assembly (EISA) method and employed in the transesterification of soybean oil and methanol. X-ray diffraction, transmission electron microscope, temperature programmed desorption of CO2, and N2 adsorption porosimetry were employed to characterize the nanocomposites. Nitrogen sorption isotherms revealed that these materials had large surface areas of more than 200 m2/g. Moreover, the sample with a Mg/Zr molar ratio of 0.5 and calcined at 400 °C showed high biodiesel yield (around 99% at 150 °C).

  8. Phase Relations In The System MgO-SiO2-H2O At Lower Mantle Conditions

    Walter, M. J.; Frost, J.; Kohn, S. C.; WANG, W.; Thomson, A. R.; Lord, O. T.


    Transport of water into the lower mantle within subducted slabs has important implications for understanding chemical mass transfer and dynamics in the deep mantle. Dehydration of the slab in the upper mantle strips the slab of much of its water cargo, however, a significant amount of water can be retained in nominally anhydrous phases such as olivine and its high-pressure polymorphs, and pyroxenes. These phases are not stable beyond the transition zone, and water may become bound in high-pressure, dense hydrous silicates, such as Phase D, and transported into the lower mantle. Here we report on experiments in the System MgO-SiO2-H2O made in the laser-heated diamond anvil cell in the pressure range of 25 to 60 GPa and at temperatures of ~1400 to 2000 K. Starting materials are synthesized as mixtures of MgSiO3 and SiO2 glasses plus brucite, have a range of water contents of ~ 5 to 30 mol% H2O, and include both MgO-rich (model peridotite) and SiO2-rich (model eclogite) bulk compositions. Experiments are made using multi-chambered (three or four laser-drilled 25 micron holes) Re gaskets. In order to avoid Al2O3 contamination, a ruby grain is inserted into only one of the chambers for initial pressure measurement. Post-heating pressures are measured in all chambers from the calibrated shift of the Raman singlet peak of diamond that is related to stress at the culet surface. Run products are analyzed using a combination of synchrotron X-ray diffraction and FEG-EPMA to identify synthesized phases and textural relations. Perturbations in the laser-power vs temperature function that correlate with visual movement of the sample and post-quench textural features are interpreted as the hydrous silicate solidus. We will discuss the implications of the following observations: (1) The hydrous silicate melting curve occurs at ~ 1750 to 1950 K for all compositions over the studied pressure range, (2) Phase D has a high-pressure stability limit that is only mildly dependent on

  9. Enhanced photocatalytic activity of TiO2-impregnated with MgZnAl mixed oxides obtained from layered double hydroxides for phenol degradation

    de Almeida, Marciano Fabiano; Bellato, Carlos Roberto; Mounteer, Ann Honor; Ferreira, Sukarno Olavo; Milagres, Jaderson Lopes; Miranda, Liany Divina Lima


    A series of TiO2/MgZnAl photocatalysts were successfully synthesized from ternary (Mg, Zn and Al) layered double hydroxides impregnated with TiO2 nanoparticles by the co-precipitation method at variable pH with different Zn2+/Mg2+ molar ratios. The composite photocatalysts were calcined at 500 °C resulting in the incorporation of oxide zinc, in the calcined MgZnAl LDH structure. Synergistic effect between ZnO and TiO2 lead to significant enhancement of TiO2/MgZnAl photocatalytic activity. Composite photocatalysts were characterized by ICP-MS, N2 adsorption-desorption, XRD, SEM, EDS, IR and UV-vis DRS. Phenol in aqueous solution (50 mg/L) was used as a model compound for evaluation of UV-vis (filter cut-off for λ > 300 nm) photocatalytic activity. The most efficient photocatalyst composite was obtained at a 5% Zn2+/Mg2+ molar ratio, in the catalyst identified as TiO2/MgZnAl-5. This composite catalyst had high photocatalytic activity, completely destroying phenol and removing 80% of total organic carbon in solution after 360 min. The TiO2/MgZnAl-5 catalyst remained relatively stable, presenting a 15% decrease in phenol degradation efficiency after five consecutive photocatalytic cycles.

  10. TiO2/Mg(OH)2新型抗菌阻燃复合材料的研究%Research on New Antibacterial Flame Retardant TiO2/Mg(OH)2 Composite Material

    李雪; 李艳平; 杨鹏飞; 孟波; 刘云义


    采用氨气鼓泡法制备TiO2/Mg(OH)2多功能复合材料,其中以钛酸正丁酯为前躯体,硝酸铵和九水硝酸铁为氮、铁掺杂源,利用水热法制备了氮、铁共掺杂TiO2粉体.通过XRD、FE-SEM、FT-IR、TG等手段对所制备样品进行了表征,结果表明:75℃条件下,通氨时间为1h,产品粒度分散均匀,二次粒径为0.69μm;产品形貌为六方片状;其(001)面与(101)面特征衍射峰的强度比值I001/I101为0.71;在322 ~ 396℃的分解失重为24.9%,最高吸热温度为376.2℃,技术指标符合氢氧化镁阻燃剂的使用要求;对罗丹明b溶液的光降解率为56.3%.%A new TiO2/Mg(OH)2 multifunctional composite material was prepared by ammonia bubbling process. Nitrogen and iron codoped TiO2 powder were obtained by the hydrothermal method using titanium tetrabutoxide as precursor and ammonium nitrate and Iron( Ⅲ) nitrate nonahydrate as nitrogen and I-ron source. The composite material was characterized by XRD, FE-SEM, FT-IR and TG. The results indicate that at 75 ℃, the particle size distribute uniformly (D50 = 0. 69 μm) with ammonia feeding time for lh. SEM analysis shows that the flake-like hexagonal product is of good dispersibility. XRD analysis indicates that it'sI(001)/I(101) =0. 71. TG-DTA analysis indicates that the water loss was 24. 9% of the total weight between 322℃ and 396℃ with the highest endothermic temperature at 376. 2℃. The quality of samples could satisfy the demand of flame retardants. The photodegradation rate of the Rhodamine b is 56.3%.

  11. Evaluation of the photocatalytic ability of a sol-gel-derived MgO-ZrO2 oxide material

    Ciesielczyk Filip


    Full Text Available This paper deals with the synthesis and characterization of a novel group of potential photocatalysts, based on sol-gel-derived MgO-ZrO2 oxide material. The material was synthesized in a typical sol-gel system using organic precursors of magnesia and zirconia, ammonia as a promoter of hydrolysis and methanol as a solvent. All materials were thoroughly analyzed, including morphology and particle sizes, chemical composition, identification of characteristic functional groups, porous structure parameters and crystalline structure. The proposed methodology of synthesis resulted in obtaining pure MgO-ZrO2 oxide material with micrometric-sized particles and a relatively high surface area. The samples underwent an additional calcination process which led to the crystalline phase of zirconia being formed. The key element of the study was the evaluation of the effectiveness of decomposition of C.I. Basic Blue 9 dye. It was shown that the calcined materials exhibit both satisfactory adsorption and photocatalytic activity with respect to the decomposition of a selected model organic impurity. Total dye removal varied in the range of 50-70%, and was strongly dependent on process parameters such as quantity of photocatalyst, time of irradiation, and the addition of promoters.

  12. Magnesium cinnamate complex, [Mg(cinn)2(H2O)2]n; structural, spectroscopic, thermal, biological and pharmacokinetical characteristics

    Puszyńska-Tuszkanow, Mariola; Zierkiewicz, Wiktor; Grabowski, Tomasz; Daszkiewicz, Marek; Maciejewska, Gabriela; Adach, Anna; Kucharska-Ziembicka, Katarzyna; Wietrzyk, Joanna; Filip-Psurska, Beata; Cieślak-Golonka, Maria


    The composition and structure of the magnesium complex with cinnamic acid, [Mg(cinn)2(H2O)2]n(1), were determined using single crystal X-ray diffraction data, IR, NMR spectroscopies, thermal and mass spectrometry analysis. Magnesium cinnamate complex, like the isostructural cobalt(II) species reported in the literature, appears to belong to the group of coordination polymers forming layered solids with pseudooctahedral coordination around the metal centre and Osbnd Csbnd O bridging units. The vibrational assignments of the experimental spectra of the complex (1) were performed on the basis of the DFT results obtained for the [Mg(cinn)4(H2O)2]2- ion, serving as a model. The complex was found to exhibit a very low cytotoxicity against neoplastic: A549 (lung), MCF-7 (breast), P388 (murine leukemia) and normal BALB3T3 (mouse fibroblasts) cell lines. In silico pharmacokinetical parameter calculations for (1) and seven known magnesium complexes with carboxylic acids: lactic, malic, glutamic, hydroaspartic and aspartic allowed for comparison of their potential bioavailability. Magnesium cinnamate complex appeared to exhibit a superior lipophilic property that suggests an optimal pharmacokinetics profile.

  13. Effect of interfacial structures on spin dependent tunneling in epitaxial L1{sub 0}-FePt/MgO/FePt perpendicular magnetic tunnel junctions

    Yang, G.; Li, D. L.; Wang, S. G., E-mail:; Ma, Q. L.; Liang, S. H.; Wei, H. X.; Han, X. F. [State Key Laboratory of Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Hesjedal, T.; Ward, R. C. C. [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom); Kohn, A.; Elkayam, A.; Tal, N. [Department of Materials Engineering and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Zhang, X.-G. [Department of Physics and Quantum Theory Project, University of Florida, Gainesville, Florida 32611 (United States); Center for Nanophase Materials Sciences and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6493 (United States)


    Epitaxial FePt(001)/MgO/FePt magnetic tunnel junctions with L1{sub 0}-FePt electrodes showing perpendicular magnetic anisotropy were fabricated by molecular beam epitaxial growth. Tunnel magnetoresistance ratios of 21% and 53% were obtained at 300 K and 10 K, respectively. Our previous work, based on transmission electron microscopy, confirmed a semi-coherent interfacial structure with atomic steps (Kohn et al., APL 102, 062403 (2013)). Here, we show by x-ray photoemission spectroscopy and first-principles calculation that the bottom FePt/MgO interface is either Pt-terminated for regular growth or when an Fe layer is inserted at the interface, it is chemically bonded to O. Both these structures have a dominant role in spin dependent tunneling across the MgO barrier resulting in a decrease of the tunneling magnetoresistance ratio compared with previous predictions.

  14. Effect of ZrO2 (9mol% Y2O3) coating thickness on the electronic conductivity of Mg-PSZ oxygen sensors

    Changhe Gao; Hailei Zhao; Qingguo Liu; Weijiang Wu; Weihua Qiu


    The ZrO2 (9mol% Y2O3) coating was prepared evenly on the surface of MgO partially stabilized zirconia (Mg-PSZ) tube (oxygen sensor probe) by dipping the green Mg-PSZ tube in a ZrO2 (9mol% Y2O3) slurry and then co-firing at 1750℃ for 8 h. The double-cell method was employed to measure the electronic conductivity parameter and exam the reproducibility of the coated MgPSZ tube. The experimental results indicate that the good thermal shock resistance of the Mg-PSZ tube can be retained when the coating thickness is not more than 3.4 μm. The ZrO2 (9mol% Y2O3) coating reduces the electronic conductivity parameter remarka -bly, probably due to the lower electronic conductivity of Y2O3-stabilized ZrO2 than that of MgO-stabilized ZrO2. Moreover, the ZrO2 (9mol% Y2O3) coating can improve the reproducibility and accuracy of the Mg-PSZ tube significantly in the low oxygen measurement. The smooth surface feature and lower electronic conductivity of the coated Mg-PSZ tube should be responsible for this improvement.

  15. Nano SiO2 and MgO improve the properties of porous β-TCP scaffolds via advanced manufacturing technology.

    Gao, Chengde; Wei, Pingpin; Feng, Pei; Xiao, Tao; Shuai, Cijun; Peng, Shuping


    Nano SiO2 and MgO particles were incorporated into β-tricalcium phosphate (β-TCP) scaffolds to improve the mechanical and biological properties. The porous cylindrical β-TCP scaffolds doped with 0.5 wt % SiO2, 1.0 wt % MgO, 0.5 wt % SiO2 + 1.0 wt % MgO were fabricated via selective laser sintering respectively and undoped β-TCP scaffold was also prepared as control. The phase composition and mechanical strength of the scaffolds were evaluated. X-ray diffraction analysis indicated that the phase transformation from β-TCP to α-TCP was inhibited after the addition of MgO. The compressive strength of scaffold was improved from 3.12 ± 0.36 MPa (β-TCP) to 5.74 ± 0.62 MPa (β-TCP/SiO2), 9.02 ± 0.55 MPa (β-TCP/MgO) and 10.43 ± 0.28 MPa (β-TCP/SiO2/MgO), respectively. The weight loss and apatite-forming ability of the scaffolds were evaluated by soaking them in simulated body fluid. The results demonstrated that both SiO2 and MgO dopings slowed down the degradation rate and improved the bioactivity of β-TCP scaffolds. In vitro cell culture studies indicated that SiO2 and MgO dopings facilitated cell attachment and proliferation. Combined addition of SiO2 and MgO were found optimal in enhancing both the mechanical and biological properties of β-TCP scaffold.

  16. Nano SiO2 and MgO Improve the Properties of Porous β-TCP Scaffolds via Advanced Manufacturing Technology

    Chengde Gao


    Full Text Available Nano SiO2 and MgO particles were incorporated into β-tricalcium phosphate (β-TCP scaffolds to improve the mechanical and biological properties. The porous cylindrical β-TCP scaffolds doped with 0.5 wt % SiO2, 1.0 wt % MgO, 0.5 wt % SiO2 + 1.0 wt % MgO were fabricated via selective laser sintering respectively and undoped β-TCP scaffold was also prepared as control. The phase composition and mechanical strength of the scaffolds were evaluated. X-ray diffraction analysis indicated that the phase transformation from β-TCP to α-TCP was inhibited after the addition of MgO. The compressive strength of scaffold was improved from 3.12 ± 0.36 MPa (β-TCP to 5.74 ± 0.62 MPa (β-TCP/SiO2, 9.02 ± 0.55 MPa (β-TCP/MgO and 10.43 ± 0.28 MPa (β-TCP/SiO2/MgO, respectively. The weight loss and apatite-forming ability of the scaffolds were evaluated by soaking them in simulated body fluid. The results demonstrated that both SiO2 and MgO dopings slowed down the degradation rate and improved the bioactivity of β-TCP scaffolds. In vitro cell culture studies indicated that SiO2 and MgO dopings facilitated cell attachment and proliferation. Combined addition of SiO2 and MgO were found optimal in enhancing both the mechanical and biological properties of β-TCP scaffold.

  17. The influence of SiO2 Addition on 2MgO-Al2O3-3.3P2O5 Glass

    Larsen, P.H.; Poulsen, F.W.; Berg, Rolf W.


    2MgO-Al2O3-3.3P2O5 glasses with increasing amounts of SiO2 are considered for sealing applications in Solid Oxide Fuel Cells (SOFC). The change in chemical durability under SOFC anode conditions and the linear thermal expansion is measured as functions of the SiO2 concentration. Raman spectroscopy...

  18. TiO2 effect on crystallization mechanism and physical properties of nano glass-ceramics of MgO-Al2O3-SiO2 glass system.

    Jo, Sinae; Kang, Seunggu


    The effect of TiO2 on the degree of crystallization, thermal properties and microstructure for MgO-Al2O3-SiO2 glass-ceramics system containing 0-13 wt% TiO2 and 0-1.5 wt% B2O3 in which the cordierite is the main phase was studied. Using Kissinger and Augis-Bennett equations, the activation energy, 510 kJ/mol and Avrami constant, 1.8 were calculated showing the surface-oriented crystallization would be preferred. The alpha-cordierite phase was generated in the glass-ceramics of containing TiO2 of 0-5.6 wt%. However, for the glass-ceramics of TiO2 content above 7 wt%, an alpha-cordierite disappeared and micro-cordierite phase was formed. The glass-ceramics of no TiO2 added had spherical crystals of few tens nanometer size spread in the matrix. As TiO2 content increased up to 5.6 wt%, a lump of dendrite was formed. In the glass-ceramics containing TiO2 7-13 wt%, in which the main phase is micro-cordierite, the dendrite crystal disappeared and a few hundred nanometer sized crystal particles hold tightly each other were generated. The thermal conductivity of glass-ceramics of both a-cordierite and micro-cordierite base decreased with TiO2 contend added. The thermal conductivity of glass-ceramics of 1.5 wt% TiO2 added was 3.4 W/mK which is 36% higher than that of glass-ceramics of no TiO2 added. The sintering temperature for 1.5 wt% TiO2 glass-ceramics was 965 degrees C which could be concluded as to apply to LTCC process for LED packaging.

  19. Effect of MgO contents on the mechanical properties and biological performances of bioceramics in the MgO-CaO-SiO2 system.

    Chen, Xianchun; Ou, Jun; Wei, Yan; Huang, Zhongbing; Kang, Yunqing; Yin, Guangfu


    The aim of this research was to investigate the effect of the chemical composition on the mechanical properties, bioactivity, and cytocompatibility in vitro of bioceramics in the MgO-CaO-SiO(2) system. Three single-phase ceramics (merwinite, akermanite and monticellite ceramics) with different MgO contents were fabricated. The mechanical properties were tested by an electronic universal machine, while the bioactivity in vitro of the ceramics was detected by investigating the bone-like apatite-formation ability in simulated body fluid (SBF), and the cytocompatibility was evaluated through osteoblast proliferation and adhesion assay. The results showed that their mechanical properties were improved from merwinite to akermanite and monticellite ceramics with the increase of MgO contents, whereas the apatite-formation ability in SBF and cell proliferation decreased. Furthermore, osteoblasts could adhere, spread and proliferate on these ceramic wafers. Finally, the elongated appearance and minor filopodia of cells on merwinite ceramic were more obvious than the other two ceramics.

  20. Synthesis and characterization of Y_2O_2S:Eu~(3+),Mg~(2+),Ti~(4+) nanorods via a solvothermal routine

    李文宇; 刘应亮; 艾鹏飞; 陈小博


    Y2O2S:Eu3+,Mg2+,Ti4+ nanorods were prepared by a solvothermal procedure.Rod-like Y(OH)3 was firstly synthesized by hydrothermal method to serve as the precursor.Y2O2S:Eu3+,Mg2+,Ti4+ powders were obtained by calcinating the precursor at CS2 atmosphere.The Y2O2S:Eu3+,Mg2+,Ti4+ phosphor with diameters of 30-50 nm and lengths up to 200-400 nm inherited the rod-like shape from the precursor after calcined at CS2 atmosphere.The Y2O2S:Eu3+,Mg2+,Ti4+ nanorods showed hexagonal pure phase,good dispersion and exhibite...

  1. A Novel MgO-CaO-SiO2 System for Fabricating Bone Scaffolds with Improved Overall Performance

    Hang Sun


    Full Text Available Although forsterite (Mg2SiO4 possesses good biocompatibility and suitable mechanical properties, the insufficient bioactivity and degradability hinders its further application. In this study, a novel MgO-CaO-SiO2 system was developed by adding wollastonite (CaSiO3 into Mg2SiO4 to fabricate bone scaffolds via selective laser sintering (SLS. The apatite-forming ability and degradability of the scaffolds were enhanced because the degradation of CaSiO3 could form silanol groups, which could offer nucleation sites for apatite. Meanwhile, the mechanical properties of the scaffolds grew with increasing CaSiO3 to 20 wt %. It was explained that the liquid phase of CaSiO3 promoted the densification during sintering due to its low melting point. With the further increase in CaSiO3, the mechanical properties decreased due to the formation of the continuous filling phase. Furthermore, the scaffolds possessed a well-interconnected porous structure and exhibited an ability to support cell adhesion and proliferation.

  2. A Novel MgO-CaO-SiO2 System for Fabricating Bone Scaffolds with Improved Overall Performance

    Sun, Hang; He, Shiwei; Wu, Ping; Gao, Chengde; Feng, Pei; Xiao, Tao; Deng, Youwen; Shuai, Cijun


    Although forsterite (Mg2SiO4) possesses good biocompatibility and suitable mechanical properties, the insufficient bioactivity and degradability hinders its further application. In this study, a novel MgO-CaO-SiO2 system was developed by adding wollastonite (CaSiO3) into Mg2SiO4 to fabricate bone scaffolds via selective laser sintering (SLS). The apatite-forming ability and degradability of the scaffolds were enhanced because the degradation of CaSiO3 could form silanol groups, which could offer nucleation sites for apatite. Meanwhile, the mechanical properties of the scaffolds grew with increasing CaSiO3 to 20 wt %. It was explained that the liquid phase of CaSiO3 promoted the densification during sintering due to its low melting point. With the further increase in CaSiO3, the mechanical properties decreased due to the formation of the continuous filling phase. Furthermore, the scaffolds possessed a well-interconnected porous structure and exhibited an ability to support cell adhesion and proliferation. PMID:28773411

  3. MgO-Al2O3-ZrO2 Amorphous Ternary Composite: A Dense and Stable Optical Coating

    Shaoo, Naba K.; Shapiro, Alan P.


    The process-parameter-dependent optical and structural properties of MgO-Al2O3-ZrO2 ternary mixed-composite material were investigated. Optical properties were derived from spectrophotometric measurements. The surface morphology, grain size distributions, crystallographic phases, and process- dependent material composition of films were investigated through the use of atomic force microscopy, x-ray diffraction analysis, and energy-dispersive x-ray analysis. Energy-dispersive x-ray analysis made evident the correlation between the optical constants and the process-dependent compositions in the films. It is possible to achieve environmentally stable amorphous films with high packing density under certain optimized process conditions.

  4. Synthesis of Dimethyl Carbonate from Ethylene Carbonate and Methanol Over Nano-Catalysts Supported on CeO2-MgO.

    Jun, Jin Oh; Lee, Joongwon; Kang, Ki Hyuk; Song, In Kyu


    A series of CeO2(X)-MgO(1-X) (X = 0, 0.25, 0.5, 0.75, and 1.0) nano-catalysts were prepared by a co-precipitation method for use in the synthesis of dimethyl carbonate from ethylene carbonate and methanol. Among the CeO2(X)-MgO(1-X) catalysts, CeO2(0.25)-MgO(0.75) nano-catalyst showed the best catalytic performance. Alkali and alkaline earth metal oxides (MO = Li2O, K2O, Cs2O, SrO, and BaO) were then supported on CeO2(0.25)-MgO(0.75) by an incipient wetness impregnation method with an aim of improving the catalytic performance of CeO2(0.25)-MgO(0.75). Basicity of the catalysts was determined by CO2-TPD experiments in order to elucidate the effect of basicity on the catalytic performance. The correlation between catalytic performance and basicity showed that basicity played an important role in the reaction. Yield for dimethyl carbonate increased with increasing basicity of the catalysts. Among the catalysts tested, Li2O/CeO2(0.25)-MgO(0.75) nano-catalyst with the largest basicity showed the best catalytic performance in the synthesis of dimethyl carbonate.

  5. Synthesis and characterization of structural and optical properties of single crystalline a-TiO2 films on MgAl2O4(111) substrate

    Xu, Haisheng; Feng, Xianjin; Luan, Caina; Ma, Jin


    Anatase phase TiO2 (a-TiO2) films have been deposited on MgAl2O4(111) substrates by the metal organic chemical vapor deposition (MOCVD) method at the substrate temperatures of 500-650°C. The structural analyses showed that the films were highly (004) oriented with tetragonal anatase structure and the epitaxial relationship was given as a-TiO2(004)||MgAl2O4 (111). The sample prepared at 600°C exhibited the best crystallization with a single-crystalline epitaxial film. The average transmittance of every TiO2 film in the visible range exceeded 90% excluding the influence of the substrate. The morphology and composition of the TiO2 films have also been studied in detail.

  6. Interface role in the enhanced photocatalytic activity of TiO2-Na0.9Mg0.45Ti3.55O8 nanoheterojunction

    Ze-Qing Guo


    Full Text Available TiO2-Na0.9Mg0.45Ti3.55O8 (TiO2-NMTO nanocomposites were synthesized via a simple hydrothermal method. TiO2 nanoparticles were loaded on NMTO nanosheets with well matched lattices. The TiO2-NMTO nanoheterojunctions enjoyed high photodegradative ability for a RhB pollutant. The photoinduced electron-hole pairs were separated effectively by the TiO2-NMTO nanoheterojunctions, which were directly observed by surface potential measurements with a scanning Kelvin probe microscopy. The photogenerated electrons accumulate at interface due to the high density of interface states, and holes remain TiO2 and NMTO particles, other than they migrate from one part to another in heterojunctions by comparing the surface potentials under illumination with different wavelengths.

  7. Thermochemistry of MgCr2O4, MgAl2O4, MgFe2O4 spinels in SO2-O2-SO3 atmosphere

    Anna Gerle


    Full Text Available The present paper investigates high-temperature sulphate corrosion of basic refractory ceramics containing magnesium spinels (MgAl2O4, MgFe2O4, MgCr2O4 and their solid solutions widely used in metallurgy, chemical, ceramic and glass industry. This group of refractories are exposed to a number of destructive factors during a working campaign. One of such factors is gas corrosion caused by sulphur oxides. However, gas sulphate corrosion of basic refractory materials containing magnesium spinels, which has a great practical meaning for the corrosion resistance of the material main components, is not sufficiently examined. This work presents a thermodynamic analysis of (MgCr2O4, MgAl2O4, MgFe2O4−SO2−O2−SO3 system aimed to calculate: i the standard free enthalpy of chemical reactions, ii the equilibrium composition of the gas mixture initially containing SO2 and O2 and iii sulphates equilibrium dissociation pressure and equilibrium partial pressure for the reaction of SO3 with the spinels to predict the temperature range of corrosion products’ stability. A thermochemical calculation provides information about equilibrium state in the analysed system. In real conditions the state of equilibrium does not have to be achieved. For this reason, the results of calculations were compared with experimental data. The experiment results were consistent with the theoretical predictions.


    Göktuğ GÜNKAYA


    Full Text Available According to the relevant literature, the utilization of different kind of glass fibers in concrete introduces positive effect on the mechanical behavior, especially toughness. There are many glassfibers available to reinforce concretes. Glass fiber composition is so important because it may change the properties such as strength, elastic modulus and alkali resistance. Its most important property to be used in concrete is the alkali resistance. Some glasses of SrO–MgO–ZrO2–SiO2 (SMZS quaternary system, such as 26SrO, 20MgO, 14ZrO2, 40SiO2 (Zrn glass, have been found to be highly alkali resistant thanks to their high ZrO2 and MgO contents. Previous researches on these glasses with MnO and/or Fe2O3 partially replacing SrO have been made with the aim of improving the chemical resistance and decreasing the production cost.The main target of the present study, first of all, was to characterize commercially available alkali resistant glass fiber for concrete reinforcement and then to compare its alkali durability with those of the SrO-Mn2O3-Fe2O3-MgO-ZrO2-SiO2 (SMFMZS system glasses. For such purposes, XRF, Tg-DTA, alkali resistance tests and SEM analysis conducted with EDX were employed. According tothe alkali endurance test results it was revealed that some of the SMFMZS system glass powders are 10 times resistant to alkali environments than the commercial glass fibers used in this study.Therefore, they can be considered as alternative filling materials on the evolution of chemically resistant concrete structures.

  9. Vibrational properties of silica species in MgO-SiO2 glasses from ab initio molecular dynamics

    Spiekermann, G.; Steele-MacInnis, M.; Kowalski, P. M.; Schmidt, C.; Jahn, S.


    Glasses and melts in the system MgO-SiO2 are analogs for magmas of the Earth's mantle. Therefore knowledge of the structure of these glasses and melts is important for understanding numerous geological processes. Raman spectroscopy is useful for probing the atomic-scale structure of glasses and melts. However, correct assignment of observed vibrational bands to specific structural and modal origins is challenging. We present the mode-projection technique to calculate vibrational subspectra for specific modal vibrations of several fundamental silica structures in silicate glasses. Structural subunits that we have studied include Q0 to Q4 tetrahedra, Si-O-Si bridging oxygen atoms for any degree of polymerization of the adjacent tetrahedra, the ethane-like symmetry of the dimer, and three- and four-fold rings. We apply this technique to ab initio molecular dynamics (MD) trajectories of MgO-SiO2 glasses at 1000 K. We found the tetrahedral symmetric stretch at 863 cm-1 for Q0, 885 cm-1 for Q1, a double peak of 960 cm-1 and 1037 cm-1 for Q2, 1032 cm-1 for Q3 and 1080 cm-1 for Q4. The bridging oxygen asymmetric stretch is at about 980 cm-1 for Q1-Q1, and it shifts to about 1100 cm-1 with increasing polymerization. This analysis has applications especially for understanding the structure of silica-poor glasses. For instance, two contradicting Raman spectroscopy studies of Mg2SiO4 glasses reported the most polymerized SiO4 tetrahedra in the glass structure to be either Q0 [1] or Q3 [2]. Our results indicate that the degree of polymerization is overestimated, if the Si-O-Si stretching modes are not considered in the interpretation of the measured Raman spectra. [1] Nasikas, N. K. and Chrissanthopoulos, A. and Bouropoulos, N. and Sen, S. and Papatheodorou, G. N., 2011, Chemistry of Materials 23, 3692-3697. [2] Kalampounias, A. G. and Nasikas, N. K. and Papatheodorou, G. N., 2009, Journal of Chemical Physics 131, 114513.

  10. FTIR study of CO adsorption on Rh/MgO modified with Co, Ni, Fe, or CeO2 for the catalytic partial oxidation of methane.

    Li, Dalin; Sakai, Shigemasa; Nakagawa, Yoshinao; Tomishige, Keiichi


    The surface state of Rh/MgO catalysts modified with Co, Ni, Fe, or CeO(2) after the reduction and partial oxidation pretreatments as well as during the catalytic partial oxidation of methane has been investigated by FTIR of adsorbed CO. The results of CO adsorption on the reduced catalysts suggest the formation of Rh-M alloy on Rh-M/MgO (M = Co, Ni, Fe) and Rh particles partially covered with reduced ceria on Rh-CeO(2)/MgO. The strength of CO adsorption on Rh/MgO is weakened by the modification with Co, Ni, Fe, or CeO(2). Partial oxidation pretreatment of Rh/MgO leads to a significant decrease in the CO adsorption due to the oxidation of Rh. In contrast, on partially oxidized Rh-M/MgO (M = Co, Ni, Fe) and Rh-CeO(2)/MgO, the preferential oxidation of the surface M atoms or reduced ceria maintains the metallic Rh and preserves the CO adsorbed on the surface Rh atoms. The CO adsorption during the reaction of catalytic partial oxidation of methane on Rh/MgO and Rh-Ni/MgO is similar to that on the reduced catalysts. On the other hand, the CO adsorption during the reaction on Rh-Co/MgO, Rh-Fe/MgO, and Rh-CeO(2)/MgO is different from that on the reduced catalysts, and this is related to the structural change of these catalysts during the reaction.

  11. Wetting and reaction characteristics of crystalline and amorphous SiO2 derived rice-husk ash and SiO2/SiC substrates with Al-Si-Mg alloys

    Bahrami, A.; Pech-Canul, M. I.; Gutiérrez, C. A.; Soltani, N.


    A study of the wetting behavior of three substrate types (SiC, SiO2-derived RHA and SiC/SiO2-derived RHA) by two Al-Si-Mg alloys using the sessile drop method has been conducted, using amorphous and crystalline SiO2 in the experiment. Mostly, there is a transition from non-wetting to wetting contact angles, being the lowest θ values achieved with the alloy of high Mg content in contact with amorphous SiO2. The observed wetting behavior is attributed to the deposited Mg on the substrates. A strong diffusion of Si from the SiC/Amorphous RHA substrate into the metal drop explains the free Si segregated at the drop/substrate interface and drop surface. Although incorporation of both SiO2-derived RHA structures into the SiC powder compact substrates increases the contact angles in comparison with the SiC substrate alone, the still observed acute contact angles in RHA/SiC substrates make them promising for fabrication of composites with high volume fraction of reinforcement by the pressureless infiltration technique. The observed wetting characteristics, with decrease in surface tension and contact angles is explained by surface related phenomena. Based on contact angle changes, drop dimensions and surface tension values, as well as on the interfacial elemental mapping, and XRD analysis of substrates, some wetting and reaction pathways are proposed and discussed.

  12. (001)-textured growth of L1{sub 0}-FePt thin films on MgO and Cr seed layers

    Matthes, Patrick; Brombacher, Christoph; Daniel, Marcus; Beddies, Gunther; Albrecht, Manfred [Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz (Germany)


    Chemically ordered FePt has a high uniaxial anisotropy with the easy axis in (001)-direction. It has been shown that (001)-textured MgO and Cr [2] seed layers can be used to stabilize the (001)-texture of L1{sub 0}-chemically ordered FePt on amorphous substrates. In this study the growth of MgO and Cr seed layers was optimized by varying the process parameters (deposition temperature and rate as well as Ar pressure) and their influence on the magnetic properties of epitaxially grown FePt films have been analyzed. In addition, reference samples on MgO(100) single crystals were prepared. XRD measurements revealed a high degree of chemical order leading to a K{sub eff} of (8.5{+-}1.3) x 10{sup 6}erg/cm{sup 3} after FePt deposition at 350 C. The low deposition temperature results in a smooth film morphology and a reversal behaviour which is dominated by domain wall propagation.

  13. CaO+SiO2+Al2O3+MgO+FeO五元渣系中FeO活度的研究%Activities of FeO in CaO-SiO2-Al2O3-MgO-FeO slags

    吕庆; 赵丽树; 王成立; 张淑会; 李福民; 刘增勋


    Activities of FeO in CaO-SiO2-Al2O3-MgO-FeO slags were determined at 1673 K by electrochemical measurements of the solid electrolyte cell: Mo |Mo+MoO2[ZrO2(MgO)[Fe+(CaO-SiO2-Al2O3-MgO-FeO)+Ag|Fe. The influences of slag compositions and basicity on FeO activities were analyzed. The results reveal that, for slags of fixed (%CaO)/(%SiO2) ratio, MgO and Al2O3 content, there was an increase of FeO activities with increase of FeO content. For slags with constant {(%CaO)+ (%MgO)}/(%SiO2) ratio, fixed FeO and Al,2O3 content, FeO activities decreased when MgO content increased from 5% to 10%, and increased with the increase of MgO content when it was over 10%. The FeO activities increased when (%CaO)/(%SiO2) ratio changed from 1.03 to 1.30 in the slags of constant MgO, FeO and Al2O3 content.

  14. MgO含量对CaO-SiO2-Al2O3-MgO熔渣中液态相影响的模拟

    林腾昌; 朱荣; 王成杰; 李超; 李明钢



  15. Degradation of selected industrial dyes using Mg-doped TiO2 polyscales under natural sun light as an alternative driving energy

    Shivaraju, H. P.; Midhun, G.; Anil Kumar, K. M.; Pallavi, S.; Pallavi, N.; Behzad, Shahmoradi


    Designing photocatalytic materials with modified functionalities for the utilization of renewable energy sources as an alternative driving energy has attracted much attention in the area of sustainable wastewater treatment applications. Catalyst-assisted advanced oxidation process is an emerging treatment technology for organic pollutants and toxicants in industrial wastewater. Preparation of visible-light-responsive photocatalyst such as Mg-doped TiO2 polyscales was carried out under mild sol-gel technique. Mg-doped TiO2 polyscales were characterized by powder XRD, SEM, FTIR, and optical and photocatalytic activity techniques. The Mg-doped TiO2 showed a mixed phase of anatase and rutile with an excellent crystallinity, structural elucidations, polyscales morphology, consequent shifting of bandgap energy and adequate photocatalytic activities under visible range of light. Mg-doped TiO2 polyscales were investigated for their efficiencies in the degradation of most commonly used industrial dyes in the real-time textile wastewater. Mg-doped TiO2 polyscales showed excellent photocatalytic degradation efficiency in both model industrial dyes (65-95%) and textile wastewater (92%) under natural sunlight as an alternative and renewable driving energy.

  16. Wide band antireflective coatings Al2O3 / HfO2 / MgF2 for UV region

    Winkowski, P.; Marszałek, Konstanty W.


    Deposition technology of the three layers antireflective coatings consists of hafnium compound are presented in this paper. Oxide films were deposited by means of e-gun evaporation in vacuum of 5x10-5 mbar in presence of oxygen and fluoride films by thermal evaporation. Substrate temperature was 250°C. Coatings were deposited onto optical lenses made from quartz glass (Corning HPFS). Thickness and deposition rate were controlled by thickness measuring system Inficon XTC/2. Simulations leading to optimization of thickness and experimental results of optical measurements carried during and after deposition process were presented. Physical thickness measurements were made during deposition process and were equal to 43 nm/74 nm/51 nm for Al2O3 / HfO2 / MgF2 respectively. Optimization was carried out for ultraviolet region from 230nm to the beginning of visible region 400 nm. In this region the average reflectance of the antireflective coating was less than 0.5% in the whole range of application.

  17. Combustion Synthesis in a Mechanically Activated Mg-C-TiO2-H3BO3 System

    Aminikia, B.; Tayebifard, S. A.; Youzbashi, A. A.


    TiC-TiB2 nanocomposite was fabricated by self-propagating high-temperature synthesis (SHS) of mechanically milled powders. H3BO3, TiO2, Mg, and C as starting materials were milled for 0.5, 1, and 3 h then pressed to form pellets. Green compacts were placed in a tube furnace which had been preheated to three different temperatures of 900, 1000, and 1100 °C with argon atmosphere, for the synthesis. The prepared samples were studied by XRD, SEM, and TEM analytical technique. TiC and TiB2 were not formed during milling process. According to the XRD patterns of synthesized samples, ball milling for 0.5 h is the optimum time for mechanical activation of the mixed powders. Further investigation indicated that 900 °C is the best temperature for the synthesis of this mixture. By using Williamson-Hall method, the average crystallite sizes of TiB2 and TiC were calculated 40.7 and 75.6 nm, respectively, which were confirmed by TEM images.

  18. Effect of LiBF4 Salt Concentration on the Properties of Plasticized MG49-TiO2 Based Nanocomposite Polymer Electrolyte

    Ahmad, A.; M. Y. A. Rahman; S. P. Low; H. Hamzah


    A nanocomposite polymer electrolyte (NCPE) comprising of 49% poly(methyl methacrylate) grafted natural rubber (MG49) as polymer host, titanium dioxide (TiO2) as a ceramic filler, lithium tetrafluoroborate (LiBF4) as dopant salt, and ethylene carbonate (EC) as plasticizer was prepared by solution casting technique. The ceramic filler, TiO2, was synthesized in situ by a sol-gel process. The ionic conductivity, chemical interaction, structure, and surface morphology of nanocomposite polymer elec...

  19. Degradability of Treated Ethion Insecticide by TiO2 Photocatalysis.

    Hassarangsee, Siriporn; Uthaibutra, Jamnong; Nomura, Nakao; Whangchai, Kanda


    Ethion, an insecticide, is widely used with fruit and vegetable crops. This research studied the reduction and oxidative degradation of standard ethion by TiO2 photocatalysis. A standard ethion solution (1 mg L(-1)) was treated with different concentrations of TiO2 powder (5, 10, 20, 40 and 60 mg mL(-1)) for 0, 15, 30, 45 and 60 min. The amount of ethion residue was detected by gas chromatography with flame photometric detection (GC-FPD) and the concentration of anions produced as major degradation products was determined by Ion Chromatography (IC). The TiO2 photocatalysis efficiently reduced ethion concentrations, with the highest degradation rate occurring within the first 15 min of reaction. The reaction produced sulphate and phosphate anions. The TiO2photocatalysis reduced 1 mg L(-1) ethion to 0.18 mg L(-1) when treated with 60 mg mL(-1) TiO2 powder for 60 min. The lethal concentration (LC50) of standard ethion was also estimated and compared to the treated ethion. All treatments, especially 60 mg mL(-1) TiO2 powder, markedly detoxified ethion, as tested with brine shrimp (Artemia salina L.), with an LC50 value of 765.8 mg mL(-1), compared to the control of 1.01 mg mL(-1).

  20. The removal of formaldehyde from concentrated synthetic wastewater using O3/MgO/H2O2 process integrated with the biological treatment.

    Moussavi, Gholamreza; Yazdanbakhsh, Ahmadreza; Heidarizad, Mahdi


    The catalytic advanced oxidation process (CAOP) of O(3)/MgO/H(2)O(2) was integrated with a sequencing batch reactor (SBR) system to completely treat concentrated formaldehyde wastewater, demonstrating that this combination is an effective method for treating such wastewaters. The influence of several operational variables--including pH, MgO powder dosage, and the concentrations of H(2)O(2) and O(3)--was investigated for the O(3)/MgO/H(2)O(2) degradation of a 7000 mg/L formaldehyde wastewater. The optimum conditions were found to be a pH of 8, 5 g/L dose of MgO powder, 0.09 mole/L concentration of H(2)O(2), and 0.153 g/L min dose of O(3). The formaldehyde and COD concentrations were reduced 79% and 65.6%, respectively, in the CAOP for 120 min of reaction time under the optimum condition stated above. The remaining concentrations of formaldehyde and COD were 1500 mg/L and 3200 mg/L, respectively, in the effluent. The degradation of formaldehyde in CAOP was determined to be a first-order reaction with a constant of 0.015/min, and radical oxidation was the predominant degradation mechanism. This effluent was post-treated in SBR system for a total cycle time of 24h. The SBR completely removed the formaldehyde and removed 98% of the COD, reducing the COD concentration to lower than 60 mg/L. Therefore, the integrated O(3)/MgO/H(2)O(2) and SBR process is demonstrated as a promising technology for the complete treatment of wastewater with high concentrations of toxic and inhibitory compounds such as formaldehyde.

  1. Impact of Mg2+ ion incorporation on the phase development of ZrO2-type solid solutions and their application in the catalytic oxidation of carbon monoxide

    Nemec, Vinko; Kaper, Helena; Pétaud, Guillaume; Ivanda, Mile; Štefanić, Goran


    The precursors of ZrO2-MgO system covering the whole concentration range were prepared by co-precipitation of the corresponding nitrate salts. The obtained precursors were calcined in air at different temperatures up to 1000 °C and analyzed at room temperature using X-ray powder diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESM) and energy dispersive X-ray spectrometry (EDS). Maximum solubility of Mg2+ ions (∼32 mol%) was obtained in the amorphous precursor. After crystallization at 600 °C the solid solubility of Mg2+ ions decreases to ∼26 mol% of which ∼22 mol% was incorporated inside ZrO2-type lattice while the remaining part of Mg2+ ions was adsorbed on the surface of the particles. Further thermal treatment decreases solubility of Mg2+ ions to 18 mol% (800 °C) and finally to 9 mol% (1000 °C). On the other side of the concentration range, the solubility of Zr4+ ions in MgO lattice was 10 mol%) polymorphs. A precise determination of unit-cell parameters shows that the increase in the Mg2+ content causes a decrease in the parameter c of tetragonal ZrO2 lattice, which in a solid solution with a Mg2+ content ≥10 mol% becomes very close to the lattice parameter a (approaching cubic lattice). The results of FE-SEM analysis show that the addition of Mg2+ ions promotes sintering of samples. The influence of thermal treatment on the crystallization of the amorphous precursors to ZrO2-type lattice was examined by differential thermal analysis and thermogravimetric measurement. The obtained results show that the crystallization temperature increases with increasing Mg content, from 445 °C (0 mol% MgO) to 625 °C (∼50 mol% MgO). The ZrO2 doped with 3 mol% MgO was used as catalyst support for platinum nanoparticles and compared to commercially available 3% yttria-doped stabilized zirconia (3YSZ). The catalysts were used for catalytic CO oxidation and show slightly better performance of the ZrO2-MgO system, which

  2. Dynamic Wetting of CaO-Al2O3-SiO2-MgO Liquid Oxide on MgAl2O4 Spinel

    Abdeyazdan, Hamed; Dogan, Neslihan; Rhamdhani, M. Akbar; Chapman, Michael W.; Monaghan, Brian J.


    Inclusion type and content in steel is critical in steelmaking, affecting both productivity through clogging, and downstream physical properties of the steel. They are normally removed from steel by reacting with a slag (liquid oxide) phase. For efficient inclusion removal, the inclusions must attach/bond with this liquid phase. The strength of the attachment can be in part characterized by the wettability of the liquid oxide on the inclusions. In this study, the dynamic wetting of liquid oxides of the CaO-Al2O3-SiO2-MgO system on a solid spinel (MgAl2O4) substrate with low porosity of 1.9 pct was measured at 1773 K (1500 °C) using a modified sessile drop technique. The dynamic contact angle between the liquid and solid spinel was determined for different CaO/Al2O3 mass percent ratios ranging from 0.98 to 1.55. Characteristic curves of wettability ( θ) vs time showed a rapid decrease in wetting in the first 10 seconds tending to a plateau value at extended times. A mathematical model for spreading behavior of liquid oxides by Choi and Lee was adopted and shown to provide a reasonable representation of the spreading behavior with time. The chemical interaction at the interface between spinel (MgAl2O4) and slag was analyzed by carrying out detailed thermodynamic evaluation and characterization using scanning electron microscopy/energy dispersive spectroscopy. There is evidence of liquid penetrating the substrate via pores and along grain boundaries, forming a penetration layer in the substrate. The depth of the penetration layer was found to be a function of substrate porosity and sample cooling rate. It decreased from ~350 µm for 6.7 pct-porous substrate to ~190 µm for substrate with porosity of 1.9 pct and from ~190 µm to ~50 µm for a slow-cooled liquid oxide-spinel substrate sample in the furnace to a rapidly cooled liquid cooled-spinel substrate sample, respectively.

  3. Diamond formation in the deep lower mantle: a high-pressure reaction of MgCO3 and SiO2

    Maeda, Fumiya; Ohtani, Eiji; Kamada, Seiji; Sakamaki, Tatsuya; Hirao, Naohisa; Ohishi, Yasuo


    Diamond is an evidence for carbon existing in the deep Earth. Some diamonds are considered to have originated at various depth ranges from the mantle transition zone to the lower mantle. These diamonds are expected to carry significant information about the deep Earth. Here, we determined the phase relations in the MgCO3-SiO2 system up to 152 GPa and 3,100 K using a double sided laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction. MgCO3 transforms from magnesite to the high-pressure polymorph of MgCO3, phase II, above 80 GPa. A reaction between MgCO3 phase II and SiO2 (CaCl2-type SiO2 or seifertite) to form diamond and MgSiO3 (bridgmanite or post-perovsktite) was identified in the deep lower mantle conditions. These observations suggested that the reaction of the MgCO3 phase II with SiO2 causes formation of super-deep diamond in cold slabs descending into the deep lower mantle. PMID:28084421

  4. Oxidation of Flash-Anodized Al-Mg Alloy in Dry Atmospheres of N2, CO2, and O2 and Humid Atmosphere of Ar

    LaPointe, Kyle; Bao, Sarina; Kvithyld, Anne


    Production of anodized Al alloy is increasing with increased recycling of Al. To study recycling of anodized material, a flash-anodized 3000 series Al alloy containing 0.34 wt pct Mg was remelted in pure atmospheres of CO2, O2, and N2, and Ar with 5 mol pct H2O at 1073 K (800 °C). Hopefully, the results should be of general influence concerning dross formation and scrap remelting in the Al industry. Oxidation studies using a thermogravimetric analyser were performed. Following the treatment, the samples oxide layers were characterized. The highest oxidation rates were observed in atmospheres of O2 and CO2. However, the onset of a break-away oxidation period in O2 is delayed in comparison to CO2. Oxidation in CO2 showed substantially less MgO formation compared to O2. The main source of mass gain can be attributed to the reaction of Mg with oxygen to form MgO and MgAl x O y . Heating in N2 resulted in the lowest mass gain of all atmospheres. Experiments in humid (5 mol pct H2O) Ar atmospheres indicate that there is a minimum threshold of Mg activity to initiate oxidation via H2O. Oxidation kinetics (mechanisms) has been investigated.

  5. Performance enhancement of perovskite solar cells with Mg-doped TiO2 compact film as the hole-blocking layer

    Wang, Jing; Qin, Minchao; Tao, Hong; Ke, Weijun; Chen, Zhao; Wan, Jiawei; Qin, Pingli; Xiong, Liangbin; Lei, Hongwei; Yu, Huaqing; Fang, Guojia


    In this letter, we report perovskite solar cells with thin dense Mg-doped TiO2 as hole-blocking layers (HBLs), which outperform cells using TiO2 HBLs in several ways: higher open-circuit voltage (Voc) (1.08 V), power conversion efficiency (12.28%), short-circuit current, and fill factor. These properties improvements are attributed to the better properties of Mg-modulated TiO2 as compared to TiO2 such as better optical transmission properties, upshifted conduction band minimum (CBM) and downshifted valence band maximum (VBM), better hole-blocking effect, and higher electron life time. The higher-lying CBM due to the modulation with wider band gap MgO and the formation of magnesium oxide and magnesium hydroxides together resulted in an increment of Voc. In addition, the Mg-modulated TiO2 with lower VBM played a better role in the hole-blocking. The HBL with modulated band position provided better electron transport and hole blocking effects within the device.

  6. In vitro cytotoxicity of SiO2 or ZnO nanoparticles with different sizes and surface charges on U373MG human glioblastoma cells

    Kim JE


    Full Text Available Jung-Eun Kim,1,* Hyejin Kim,1,* Seong Soo A An,2 Eun Ho Maeng,3 Meyoung-Kon Kim,4 Yoon-Jae Song1 1Department of Life Science, 2Department of Bionano Technology, Gachon University, Seongnam-Si, South Korea; 3Korea Testing and Research Institute, Seoul, South Korea; 4Department of Biochemistry and Molecular Biology, Korea University Medical School and College, Seoul, South Korea *These authors contributed equally to this work Abstract: Silicon dioxide (SiO2 and zinc oxide (ZnO nanoparticles are widely used in various applications, raising issues regarding the possible adverse effects of these metal oxide nanoparticles on human cells. In this study, we determined the cytotoxic effects of differently charged SiO2 and ZnO nanoparticles, with mean sizes of either 100 or 20 nm, on the U373MG human glioblastoma cell line. The overall cytotoxicity of ZnO nanoparticles against U373MG cells was significantly higher than that of SiO2 nanoparticles. Neither the size nor the surface charge of the ZnO nanoparticles affected their cytotoxicity against U373MG cells. The 20 nm SiO2 nanoparticles were more toxic than the 100 nm nanoparticles against U373MG cells, but the surface charge had little or no effect on their cytotoxicity. Both SiO2 and ZnO nanoparticles activated caspase-3 and induced DNA fragmentation in U373MG cells, suggesting the induction of apoptosis. Thus, SiO2 and ZnO nanoparticles appear to exert cytotoxic effects against U373MG cells, possibly via apoptosis. Keyword: apoptosis

  7. Radiation-induced amorphization of Ce-doped Mg2Y8(SiO4)6O2 silicate apatite

    Zhou, Jianren; Yao, Tiankai; Lian, Jie; Shen, Yiqiang; Dong, Zhili; Lu, Fengyuan


    Ce-doped Mg2Y8(SiO4)6O2 silicate apatite (Ce = 0.05 and 0.5) were irradiated with 1 MeV Kr2+ ion beam irradiation at different temperatures and their radiation response and the cation composition dependence of the radiation-induced amorphization were studied by in situ TEM. The two Ce-doped Mg2Y8(SiO4)6O2 silicate apatites are sensitive to ion beam induced amorphization with a low critical dose (0.096 dpa) at room temperature, and exhibits significantly different radiation tolerance at elevated temperatures. Ce concentration at the apatite AI site plays a critical role in determining the radiation response of this silicate apatite, in which the Ce3+ rich Mg2Y7.5Ce0.5(SiO4)6O2 displays lower amorphization susceptibility than Mg2Y7.95Ce0.05(SiO4)6O2 with a lower Ce3+ occupancy at the AI sites. The critical temperature (Tc) and activation energy (Ea) change from 667.5 ± 33 K and 0.162 eV of Mg2Y7.5Ce0.5(SiO4)6O2 to 963.6 ± 64 K and 0.206 eV of Mg2Y7.95Ce0.05(SiO4)6O2. We demonstrate that the radiation tolerance can be controlled by varying the chemical composition, and enhanced radiation tolerance is achieved by increasing the Ce concentration at the AI site.

  8. Study on sulphide capacity of CaO-SiO2-Al2O3-MgO-FetO slags


    The sulphide capacity of CaO-SiO2-Al2O3-MgO-FetO slags was studied at 1773 K using gas-slag equilibrium techniques.Utilizing a Pt crucible, the slag was equilibrated with a mixture of gases, namely, CO, CO2, SO2 and N2 to provide the partial pressure of oxygen and sulphur. It was shown that at fixed FetO and Al2O3 contents and a fixed {(%CaO)+(%MgO)}/(%SiO2) ratio, the sulphide capacity decreases with increasing MgO content. At a constant (%CaO)/(%SiO2) ratio and constant MgO and Al2O3 contents, increasing the FetO content of the slags also results in an increase of the sulphide capacity. The rising basicity of (%CaO)/(%SiO2) from 1.0 to 1.4 at fixed MgO, FetO and Al2O3 contents significantly increases the sulphide capacity.

  9. Magnetic bioactive glass ceramic in the system CaO-P2O5-SiO2-MgO-CaF2-MnO2-Fe2O3 for hyperthermia treatment of bone tumor.

    Li, Guangda; Feng, Shuying; Zhou, Dali


    Magnetic bioactive glass ceramic (MG) in the system CaO-SiO(2)-P(2)O(5)-MgO-CaF(2)-MnO(2)-Fe(2)O(3) for hyperthermia treatment of bone tumor was synthesized. The phase composition was investigated by XRD. The magnetic property was measured by VSM. The in vitro bioactivity was investigated by simulated body fluid (SBF) soaking experiment. Cell growth on the surface of the material was evaluated by co-culturing osteoblast-like ROS17/2.8 cells with materials for 7 days. The results showed that MG contained CaSiO(3) and Ca(5)(PO(4))(3)F as the main phases, and MnFe(2)O(4) and Fe(3)O(4) as the magnetic phases. Under a magnetic field of 10,000 Oe, the saturation magnetization and coercive force of MG were 6.4 emu/g and 198 Oe, respectively. After soaking in SBF for 14 days, hydroxyapatite containing CO(3)(2-) was observed on the surface of MG. The experiment of co-culturing cells with material showed that cells could successfully attach and well proliferate on MG.

  10. Effect of ZrO(2) additions on the crystallization, mechanical and biological properties of MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) bioactive glass-ceramics.

    Li, H C; Wang, D G; Meng, X G; Chen, C Z


    A series of ZrO(2) doped MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) bioactive glass-ceramics were obtained by sintering method. The crystallization behavior, phase composition, morphology and structure of glass-ceramics were characterized. The bending strength, elastic modulus, fracture toughness, micro-hardness and thermal expansion coefficient (TEC) of glass-ceramics were investigated. The in vitro bioactivity and cytotoxicity tests were used to evaluate the bioactivity and biocompatibility of glass-ceramics. The sedimentation mechanism and growth process of apatites on sample surface were discussed. The results showed that the mainly crystalline phases of glass-ceramics were Ca(5)(PO4)3F (fluorapatite) and β-CaSiO(3). (β-wollastonite). m-ZrO(2) (monoclinic zirconia) declined the crystallization temperatures of glasses. t-ZrO(2) (tetragonal zirconia) increased the crystallization temperature of Ca(5)(PO4)(3)F and declined the crystallization temperature of β-CaSiO(3). t-ZrO(2) greatly increased the fracture toughness, bending strength and micro-hardness of glass-ceramics. The nanometer apatites were induced on the surface of glass-ceramic after soaking 28 days in SBF (simulated body fluid), indicating the glass-ceramic has good bioactivity. The in vitro cytotoxicity test demonstrated the glass-ceramic has no toxicity to cell.

  11. Local structure characterization and thermal properties of P2O5sbnd MgOsbnd Na2Osbnd Li2O glasses doped with SiO2

    Wu, Fengnian; Li, Sheng; Chang, Ziyuan; Liu, Hongting; Huang, Sanxi; Yue, Yunlong


    Pure and SiO2 doped P2O5sbnd MgOsbnd Na2Osbnd Li2O glass has been prepared by the traditional melt quenching and heat treatment techniques. Via X-ray diffraction (XRD) patterns, all the samples are proved to be amorphous. Field emission scanning electron microscopy (FESEM) and macroscopic observation show that all the samples are homogeneous glasses and no phase splitting phenomenon. Fourier transform infrared (FTIR) spectrum shows that the amount of non-bridging oxygen decreases and the polymerization degree of the glass network structure increases after introducing SiO2 into glasses. Meanwhile, density and molar volume gradually decline with the increasing of SiO2. The glass transition (Tg) and the first crystallization temperature (Tc) indicates thermal stability increases in SiO2 added glasses.

  12. Effect of CeO2, MgO and Y2O3 additions on the sinterability of a milled Si3N4 with 14.5 wt% SiO2

    Arias, A.


    The sinterability of alpha Si3N4 with 0-5.07 equivalent per cent of CeO2, MgO, or Y2O3 has been studied in the temperature range 1650-1820 C by density measurements and X-ray diffraction analysis. Maximum densities were obtained in the range 1765-1820 C and were 99.6% of theoretical with 2.5% CeO2; 98.5% of theoretical with 1.24 to 1.87% MgO, and 99.2% of theoretical with 2.5% Y2O3. Densities 94% or more of theoretical value were obtained with as little as 0.62 equivalent per cent additive.

  13. Optical Properties of MgF2 / MgF2 / Glass and MgF2 / TiO2 / Glass

    S. Ghahramani


    Full Text Available MgF2 thin films by thickness of 93 nm were deposited on MgF2 / glass and TiO2 / glass thin layers by resistance evaporation method under ultra-high vacuum (UHV conditions, rotating pre layer for sample one and normal deposition for second one. Optical properties were measured via spectrophotometer in spectral range of 300-1100 nm wave length. The optical constants such as, real part of refractive index (n, imaginary part of refractive index (k, real and imaginary parts of dielectric function ε1, ε2 respectively and absorption coefficient (, were obtained from Kramers-Kronig analysis of reflectivity curves. Band-gap energy was also estimated for these films.

  14. SiO2@MgO nanoparticles templated mesoporous carbon with rich electro-active oxygenic functionalities and enhanced supercapacitive performances

    Tian, Zhengfang; Duan, Shuyi; Shen, Yu; Xie, Mingjiang; Guo, Xuefeng


    As a member of carbon-based materials, ordered mesoporous carbon (OMC) still suffers from poor capacity for supercapacitive applications. Functionalization the skeleton with pseudocapacitive functionalities is an efficient way to enhance the capacity of OMCs. Herein, a designed SiO2@MgO nanoparticle with uniform diameters was employed as template towards the synthesis of pseudocapacitive oxygen functionalized OMC. The obtained carbons possess ordered mesoporous structure, large surface area, and rich pseudocapacitive oxygen species. As electrode for supercapacitor in 1.0 M H2SO4, the SiO2@MgO templated OMC achieves higher capacitance (257 F/g) than pure SiO2 templated OMC (180 F/g), surfactant templated OMC (152 F/g) and commercial activated carbon (110 F/g) owing to the high pseudocapacitive oxygen functionalities, providing more capacity by reversible Faradaic reaction.

  15. Synthesis, characterization and visible light photocatalytic activity of Mg2+ and Zr4+ co-doped TiO2 nanomaterial for degradation of methylene blue

    Desta Shumuye Meshesha


    Full Text Available Mg2+ and Zr4+ co-doped TiO2 was synthesized by sol–gel method. Catalysts were characterized by XRD, UV–vis DRS, SEM-EDX, TEM, BET, XPS and FT-IR to evaluate the crystal patterns and crystallite size (5.07–18.9 nm, bandgap energy, morphology, surface area, surface composition with oxidation states and incorporation of dopants into TiO2 lattice. Degradation of methylene blue was carried out under visible light irradiation by varying the reaction parameters such as initial dye concentration, catalyst loading and pH of the solution. 1.0 wt% Mg2+ and 0.25 wt% Zr4+ codoped TiO2 was found to be an efficient catalyst.

  16. Screening of MgO- and CeO2-Based Catalysts for Carbon Dioxide Oxidative Coupling of Methane to C2+ Hydrocarbons

    Istadi; Nor Aishah Saidina Amin


    The catalyst screening tests for carbon dioxide oxidative coupling of methane (CO2-OCM)have been investigated over ternary and binary metal oxide catalysts. The catalysts are prepared by doping MgO- and CeO2-based solids with oxides from alkali (Li2O), alkaline earth (CaO), and transition metal groups (WO3 or MnO). The presence of the peroxide (O22-) active sites on the Li2O2, revealed by Raman spectroscopy, may be the key factor in the enhanced performance of some of the Li2O/MgO catalysts.The high reducibility of the CeO2 catalyst, an important factor in the CO2-OCM catalyst activity, may be enhanced by the presence of manganese oxide species. The manganese oxide species increases oxygen mobility and oxygen vacancies in the CeO2 catalyst. Raman and Fourier Transform Infra Red (FT-IR) spectroscopies revealed the presence of lattice vibrations of metal-oxygen bondings and active sites in which the peaks corresponding to the bulk crystalline structures of Li2O, CaO, WO3 and MnO are detected. The performance of 5%MnO/15%CaO/CeO2 catalyst is the most potential among the CeO2-based catalysts,although lower than the 2%Li2O/MgO catalyst. The 2%Li2O/MgO catalyst showed the most promising C2+ hydrocarbons selectivity and yield at 98.0% and 5.7%, respectively.

  17. Prediction of a hexagonal SiO2 phase affecting stabilities of MgSiO3 and CaSiO3 at multimegabar pressures.

    Tsuchiya, Taku; Tsuchiya, Jun


    Ultrahigh-pressure phase relationship of SiO(2) silica in multimegabar pressure condition is still quite unclear. Here, we report a theoretical prediction on a previously uncharacterized stable structure of silica with an unexpected hexagonal Fe(2)P-type form. This phase, more stable than the cotunnite-type structure, a previously postulated postpyrite phase, was discovered to stabilize at 640 GPa through a careful structure search by means of ab initio density functional computations over various structure models. This is the first evidential result of the pressure-induced phase transition to the Fe(2)P-type structure among all dioxide compounds. The crystal structure consists of closely packed, fairly regular SiO(9) tricapped trigonal prisms with a significantly compact lattice. Additional investigation further elucidates large effects of this phase change in SiO(2) on the stability of MgSiO(3) and CaSiO(3) at multimegabar pressures. A postperovskite phase of MgSiO(3) breaks down at 1.04 TPa along an assumed adiabat of super-Earths and yields Fe(2)P-type SiO(2) and CsCl (B2)-type MgO. CaSiO(3) perovskite, on the other hand, directly dissociates into SiO(2) and metallic CaO, skipping a postperovskite polymorph. Predicted ultrahigh-pressure and temperature phase diagrams of SiO(2), MgSiO(3), and CaSiO(3) indicate that the Fe(2)P-type SiO(2) could be one of the dominant components in the deep mantles of terrestrial exoplanets and the cores of gas giants.

  18. Preparation and characterization of PEG–Mg(CH3COO)2–CeO2 composite polymer electrolytes for battery application

    Anji Reddy Polu; Ranveer Kumar


    Composite polymer electrolytes based on poly(ethylene glycol) (PEG), magnesium acetate [Mg(CH3COO)2], and wt% of cerium oxide (CeO2) ceramic fillers (where = 0, 5, 10, 15 and 20, respectively) have been prepared using solution casting technique. X-ray diffraction patterns of PEG–Mg(CH3COO)2 with CeO2 ceramic filler indicated the decrease in the degree of crystallinity with increasing concentration of the filler. DSC measurements of PEG–Mg(CH3COO)2-CeO2 composite polymer electrolyte system showed that the melting temperature is shifted towards the lower temperature with increase of the filler concentration. The conductivity results indicate that the incorporation of ceramic filler up to a certain concentration (i.e. 15 wt%) increases the ionic conductivity and upon further addition the conductivity decreases. The transference number data indicated the dominance of ion-type charge transport in these specimens. Using this (PEG–Mg(CH3COO)2-CeO2) (85-15-15) electrolyte, solid-state electrochemical cell was fabricated and their discharge profiles were studied under a constant load of 100 k.

  19. Influence of acid-base properties on the Lebedev ethanol-to-butadiene process catalyzed by SiO2-MgO materials

    Angelici, Carlo; Velthoen, Marjolein E. Z.; Weckhuysen, Bert M.; Bruijnincx, Pieter C. A.


    The Lebedev ethanol-to-butadiene process entails a complex chain of reactions that require catalysts to possess a subtle balance in the number and strength of acidic and basic sites. SiO2-MgO materials can be excellent Lebedev catalysts if properly prepared, as catalyst performance has been found to

  20. Effects of MgO and TiO2 on the viscous behaviors and phase compositions of titanium-bearing slag

    Cong Feng; Man-sheng Chu; Jue Tang; Jin Qin; Feng Li; Zheng-gen Liu


    The effects of MgO and TiO2 on the viscosity, activation energy for viscous flow, and break-point temperature of titanium-bearing slag were studied. The correlation between viscosity and slag structure was analyzed by Fourier transform infrared (FTIR) spectroscopy. Subsequently, main phases in the slag and their content changes were investigated by X-ray diffraction and Factsage 6.4 software package. The results show that the viscosity decreases when the MgO content increases from 10.00wt%to 14.00wt%. Moreover, the break-point tem-perature increases, and the activation energy for viscous flow initially increases and subsequently decreases. In addition, with increasing TiO2 content from 5.00wt%to 9.00wt%, the viscosity decreases, and the break-point temperature and activation energy for viscous flow initially decrease and subsequently increase. FTIR analyses reveal that the polymerization degree of complex viscous units in titanium-bearing slag decreases with increasing MgO and TiO2 contents. The mechanism of viscosity variation was elucidated. The basic phase in experimental slags is melilite. Besides, as the MgO content increases, the amount of magnesia–alumina spinel in the slag increases. Similarly, the sum of pyroxene and perovskite phases in the slag increases with increasing TiO2 content.

  1. Formation of CaO·TiO2-MgO·Al2O3 dual phase inclusion in Ti stabilized stainless steel


    The formation of CaO.TiO2-MgO.Al2O3 dual phase inclusion in 321 stainless steel was investigated in the laboratory. The result indicated that the condition for the formation of CaO.TiO2-MgO.Al2O3 in 321 steel is [Ca]>0.001wt%, [Ti]>0.1wt%, and[Al]>0.01wt%. The mechanism is the following: Al2O3 inclusion turns into CaO-Al2O3 after Ca-Si wire is fed into the molten steel;[Mg] is then obtained by reducing MgO in slag or crucible wall by [Al] and [Ti]; finally CaO-Al2O3 inclusion is changed into CaO.TiO2-MgO-Al2O3 by the reaction with [Mg], [Ti], and [O] in the molten steel simultaneously.

  2. Building of CoFe2/CoFe2O4/MgO architectures: Structure, magnetism and surface functionalized by TiO2

    Wang, M.; Ma, Y. Q.; Sun, X.; Geng, B. Q.; Wu, M. Z.; Zheng, G. H.; Dai, Z. X.


    Well-dispersed uniform CoFe2O4 nanoparticles were prepared and then coated by MgO through thermal decomposition of a metal-organic salt in organic solvent. Then CoFe2O4/MgO were reduced in a H2/N2 mixture gas and subsequently oxidized in an ambient atmosphere in order to build CoFe2/CoFe2O4/MgO architectures with high magnetization, good chemical stability and dispersivity, which are useful in some practical applications. MgO can be dissolved by the HCl solution. The surfaces of CoFe2O4, CoFe2/MgO, CoFe2 and CoFe2/CoFe2O4 magnetic particles were functionalized by TiO2 to prepare the magnetically separable photocatalysts. The rattle-type particles were obtained without the assistance of template and etchant. The photocatalytic activity of these photocatalysts in degradation of methylene blue and the magnetic separability were investigated: The nanosheet-shaped TiO2 and rattle-type particles exhibited good photocatalytic performance; The highest degradation efficiency reaches 93% for the CoFe2/TiO2 sample which has the highest magnetization value of 42 emu/g, beneficial for the recovery of catalyst after degradation.

  3. Decaying shock studies of phase transitions in MgO-SiO2 systems: Implications for the super-Earths' interiors

    Bolis, R. M.; Morard, G.; Vinci, T.; Ravasio, A.; Bambrink, E.; Guarguaglini, M.; Koenig, M.; Musella, R.; Remus, F.; Bouchet, J.; Ozaki, N.; Miyanishi, K.; Sekine, T.; Sakawa, Y.; Sano, T.; Kodama, R.; Guyot, F.; Benuzzi-Mounaix, A.


    We report an experimental study of the phase diagrams of MgO, MgSiO3, and Mg2SiO4 at high pressures. We measured the shock compression response, including pressure-temperature Hugoniot curves of MgO, MgSiO3, and Mg2SiO4 between 0.2-1.2 TPa, 0.12-0.5 TPa, and 0.2-0.85 TPa, respectively, using laser-driven decaying shocks. A melting signature has been observed in MgO at 0.47 ± 0.04 TPa and 9860 ± 810 K, while no such phase changes were observed either in MgSiO3 or in Mg2SiO4. Increases of reflectivity of MgO, MgSiO3, and Mg2SiO4 liquids have been detected above 0.55 TPa (12760 K), 0.15 TPa (7540 K), 0.2 TPa (5800 K), respectively. In contrast to SiO2, melting and metallization of these compounds do not coincide, implying the presence of poorly electrically conducting liquids close to the melting lines. This has important implications for the generation of dynamos in super-Earth's mantles.

  4. MgO-SiO2-ZrO2-C系复合材料显微结构及其抗蚀性研究%The Microstructure and Corrosion Resistant of Corbon-Bonded Forsterito-zirconia Materials


    The forsterite-zirconia material have been produced from the zircon and magnesia, adding graphite, to produce a Mg2SiOZrO2-C. The microstructure and Mineral composition have been studied by means of microscope, SFM,X-ray, diffractometer and DTA. It is a nice refractories that the brick have densed structure, thermal stability, good thermal conductivity and wear-resistance, and good resistance to the corrosion by iron-oxide slay.%以锆英砂和电熔镁砂为原料,合成ZrO2增韧的镁橄榄石材料,进而加入鳞片状石墨,得到Mg2SiO4(-ZrO2)-C复合材料。用扫描电镜、X射线衍射仪、差热、红外光谱等手段研究了该材料的显微结构和矿物组成。表明该材料具有优异的高温强度、抗侵蚀性和热震稳定性,是一种新型耐火材料。

  5. Study on the water durability of zinc boro-phosphate glasses doped with MgO, Fe2O3, and TiO2

    Hwang, Moon Kyung; Ryu, Bong Ki


    The water durability of zinc boro-phosphate (PZB) glasses with the composition 60P2O5-20ZnO-20B2O3- xMeO ( x = 0, 2, 4, 6 and MeO = MgO, Fe2O3, or TiO2) (mol%) was measured, and PZB glass was studied in terms of its thermal properties, density, and FTIR characteristics. The surface conditions and corrosion byproducts were analyzed using scanning electron microscopy. When MgO, Fe2O3, and TiO2 were doped into the PZB glass, Q2 was decreased and Q1 was increased in the phosphate structure, while the number of BO4 structures increased with increasing MeO content. The density of the PZB glass was increased by the addition of Fe2O3 and TiO2, while the glass transition temperature ( T g ) and dilatometric softening temperature ( T d ) were increased when additional MgO, Fe2O3, and TiO2 were added. From the weight loss analysis (95 ◦ C, 96 h), TiO2 doped glass showed the lowest weight loss (1.70 × 10 -3 g/cm2) while MgO doped glass showed the highest value (2.44 × 10 -3 g/cm2), compared with PZB glass (3.07 × 10 -3 g/cm2). These results were discussed in terms of the Me n+ ions in the glass structure, and their different coordination numbers and bonding strengths.

  6. Diagramas de equilibrio cuaternarios ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2). Una poderosa herramienta para el desarrollo de nuevos materiales por sinterización reactiva

    Moya, J. S.; Bartolomé, J. F.; Peña, P.


    En este articulo se exponen, discuten y evalúan los trabajos que sobre materiales de Mullita-Circona obtenidos por sinterización reactiva dirigió e inspiro Salvador de Aza sobre la base de los diagramas de equilibrio de fase multicomponentes ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2). Se analiza su impacto en distintas áreas de la ciencia y tecnología cerámicas tales como chamotas refractarias, industria del aluminio, etc. También se proponen posibles campos de aplicación futura como es el ...

  7. MgO-TiO2-Al2O3系原料在无铬耐火材料中的应用%The Application of MgO - TiO2 - Al2O3 Aggregates for Chrome Free Refractories

    高宏适; 全荣



  8. Synergy Effects of the Mixture of Bismuth Molybdate Catalysts with SnO2/ZrO2/MgO in Selective Propene Oxidation and the Connection between Conductivity and Catalytic Activity

    Le, Minh Thang; Do, Van Hung; Truong, Duc Duc


    Bismuth molybdate catalysts have been used for partial oxidation and ammoxidation of light hydrocarbons since the 1950s. In particular, there is the synergy effect (the enhancement of the catalytic activity in the catalysts mixed from different components) in different phases of bismuth molybdate...... catalysts which has been observed and studied since the 1980s; however, despite it being interpreted differently by different research groups, there is still no decisive conclusion on the origin of the synergy effect that has been obtained. The starting idea of this work is to find an answer...... for the question: does the electrical conductivity influence the catalytic activity (which has been previously proposed by some authors). In this work, highly conductive materials (SnO2, ZrO2) and nonconductive materials (MgO) are added to beta bismuth molybdates (beta-Bi2Mo2O9) using mechanical mixing...

  9. Synthesis and optical properties of SiO$_2$–Al$_2$O$_3$–MgO–K$_2$CO$_3$–CaO–MgF$_2$–La$_2$O$_3$ glasses



    A series of five glass compositions were prepared by using the conventional melt quenching technique in the system SiO$_2$–Al$_2$O$_3$–MgO–K$_2$CO$_3$–CaO–MgF$_2$–La$_2$O$_3$ with different contents of SiO$_2$, MgO, K$_2$CO$_3$, MgF$_2$ and La$_2$O$_3$. The effects on the optical and physical properties of these glasses due to the addition of La$_2$O$_3$ as well as variation of the various oxides have been investigated. X-ray diffraction analysis is used to confirm the amorphous nature of the prepared glasses. Structures of glasses were studied by using UV–Vis and Fourier transforms infrared spectroscopy. The drilling test was also performed on their glass ceramic samples to confirm the machinability.

  10. MgO-hybridized TiO2 interfacial layers assisting efficiency enhancement of solid-state dye-sensitized solar cells

    Sakai, Nobuya; Ikegami, Masashi; Miyasaka, Tsutomu


    Interfacial modification of a thin TiO2 compact layer (T-CL) by hybridization with MgO enhanced the quantum conversion efficiency of solid-state dye-sensitized solar cells (ssDSSCs) comprising a multilayer structure of transparent electrode/T-CL/dye-sensitized mesoporous TiO2/hole conductor/metal counter electrode. The Mg(CH3COO)2 treatment was employed to introduce a MgO-TiO2 CL (T/M-CL), which enhanced the physical connection and conduction between the CL and mesoporous semiconductor layer as a consecutive interface, owing to the dehydration reaction of Mg(CH3COO)2. The photocurrent density of ssDSSC was increased 33% by the T/M-CL compared with the T-CL, using an equivalent amount of adsorbed dye. The ssDSSC with the T/M-CL yielded the highest efficiency of 4.02% under irradiation at 100 mW cm-2. The electrical impedance spectroscopy showed that the charge-transfer resistance (Rct) of the photoelectrode with T/M-CL was reduced by 300 Ω from the reference non-treated T-CL electrode. Characterized by the intrinsically low Rct of the compact layer, the T/M-CL is capable of improving the photovoltaic performance of solid-state sensitized mesoscopic solar cells.

  11. Characterization of Y2O2S:Eu3+, Mg2+, Ti4+ Long-Lasting Phosphor Synthesized by Flux Method


    Long-lasting phosphor Y2O2S∶Eu3+, Mg2+, Ti4+ was synthesized by a flux method and their luminescence properties were investigated. The result indicates that the unit cell parameter c is linearly increased with the increase of Eu2O3 content in Y2O2S∶Eu3+x(0.01≤x≤0.10). On the other hand, the change of unit cell parameter a is not linear dependence. In the Y2O2S∶ Eu3+ crystal structure, Eu3+ ions only replaced Y3+ ions′ places in which it posited center position of c axis. With the increase of Eu2O3 content, the position of the strongest emission peak changed from 540 nm (5D1→7F2 transition) to 626 nm (5D0→7F2 transition), and the maximum intensity was obtained when x=0.09 in Y2O2S∶Eu3+x(0.01≤x≤0.10). This is due to the environment of trivalent europium in the crystal structure of Y2O2S. Doping with Mg2+ or Ti4+ ions alone cannot get the good long-lasting afterglow effect, whereas co-doping with Mg2+ and Ti4+ ions and excited with 365 nm ultraviolet light, a strong thermoluminesence peak appeared, red and orange long-lasting phosphorescence (LLP) was also observed and the phosphorescence lasted nearly 3 h in the light perception of the dark-adapted human eye (0.32 mcd*m-2). Thus the LLP mechanism was analyzed.

  12. Study on the coating of nano-scale SiO2 film on the surface of nanocrystalline Mg-Al layered double hydroxides

    ZHANG Zejiang; MEI Xiujuan; XU Chenghua; QIU Fali


    The coating process of a nano-scale SiO2 film on the nanocrystalline Mg-Al layered double hydroxides via a sol-gel process was investigated. The uniform and dense SiO2 film with a thickness of about 5 nm on the nano-LDHs particles was characterized by the solubility test in the dilute HNO3 or HCl acid, TEM and FT-IR, XRD, TG and DSC. The chemical shifts of binding energies of Al 2p, Mg 2p, Si 2s and O 1s on the coated particles indicate that the coating of the SiO2 nano-film on the surface of the nano-LDHs proceeds through the formation of Mg-O-Si and Al-O-Si bonds. The thermal analysis shows that both the SiO2-coated nano-LDHs and the nano-LDHs have a similar mass loss process, in which there are three obvious stages of mass loss in the temperature range of 40-700℃. Furthermore, the more the coated amount of SiO2 on the surface of the nano-LDHs is, the less the mass loss of the samples is at 700℃.The nano- LDHs have two obvious endothermic peaks at 244.67℃ and 430.13℃, whose corresponding heat absorption capacities are 412.28 J/g and 336.30 J/g, respectively. In contrast, the coated nano-LDHs have only one endothermic peak at 243.60℃ with a heat absorption capacity of 221.25 J/g.

  13. Thermodynamics Behavior of Germanium During Equilibrium Reactions between FeOx-CaO-SiO2-MgO Slag and Molten Copper

    Shuva, M. A. H.; Rhamdhani, M. A.; Brooks, G. A.; Masood, S.; Reuter, M. A.


    The distribution ratio of germanium (Ge), L_{{Ge}}^{s/m} during equilibrium reactions between magnesia-saturated FeOx-CaO-SiO2 (FCS) slag and molten copper has been measured under oxygen partial pressures from 10-10 to 10-7 atm and at temperatures 1473 to 1623 K (1200 to 1350 °C). It was observed that the Ge distribution ratio increases with increasing oxygen partial pressure, and with decreasing temperature. It was also observed that the distribution ratio is strongly dependent on slag basicity. The distribution ratio was observed to increase with increasing optical basicity. At fixed CaO concentration in the slag, the distribution ratio was found to increase with increasing Fe/SiO2 ratio, tending to a plateau at L_{{Ge}}^{s/m} = 0.8. This behavior is consistent with the assessment of ionic bond fraction carried out in this study, and suggested the acidic nature of germanium oxide (GeO2) in the slag system studied. The characterisation results of the quenched slag suggested that Ge is present in the FeOx-CaO-SiO2-MgO slag predominantly as GeO2. At 1573 K (1300 °C) and p_{{{{O}}2 }} = 10-8 atm, the activity coefficient of GeO2 in the slag was calculated to be in the range of 0.24 to 1.50. The results from the current study suggested that less-basic slag, high operating temperature, and low oxygen partial pressure promote a low Ge distribution ratio. These conditions are desired for maximizing Ge recovery, for example, during pyrometallurgical processing of Ge-containing e-waste through secondary copper smelting. Overall, the thermodynamics data generated from this study can be used for process modeling purposes for improving recovery of Ge in primary and secondary copper smelting processes.

  14. Combustion Synthesis of TiB2 Ceramics Powder from B2O3-TiO2-Mg System in Air Atmosphere

    HE Jinyun; WANG Weimin; FU Zhengyi; SUN Hui


    TiB2 ceramics powder was synthesized from B2O3-TiO2-Mg system. The effects of TiB2 addition as diluent on the combustion synthesis process were investigated. The results of thermodynamic calculation and experiments show that the increase of TiB2 content ranging from 0 to 20wt% can reduce the adiabatic temperature Tad from 3100 K to 2896 K and combustion temperature Tc from 2139 K to 1621 K respectively. The particle size and half width of the particle distribution are also increased with the addition of TiB2 increasing from 0 to 20wt%. The combustion product is a mixture of TiB2, MgO, and other intermediate phases. The leached product contains mainly TiB2, TiO2 and TiN, and its oxygen content is 7.77wt%.

  15. Low temperature biosynthesis of Li2O-MgO-P2O5-TiO2 nanocrystalline glass with mesoporous structure exhibiting fast lithium ion conduction.

    Du, Xiaoyong; He, Wen; Zhang, Xudong; Ma, Jinyun; Wang, Chonghai; Li, Chuanshan; Yue, Yuanzheng


    We demonstrate a biomimetic synthesis methodology that allows us to create Li2O-MgO-P2O5-TiO2 nanocrystalline glass with mesoporous structure at lower temperature. We design a 'nanocrystal-glass' configuration to build a nanoarchitecture by means of yeast cell templates self-assembly followed by the controlled in-situ biomineralization of materials on the cell wall. Electrochemically active nanocrystals are used as the lamellar building blocks of mesopores, and the semiconductive glass phase can act both as the 'glue' between nanocrystals and functionalized component. The Li2O-MgO-P2O5-TiO2 nanocrystalline glass exhibits outstanding thermal stability, high conductivity and wide potential window. This approach could be applied to many other multicomponent glass-ceramics to fabricate mesoporous conducting materials for solid-state lithium batteries.

  16. Diagramas de equilibrio cuaternarios ZrO2-Al2O 3-SiO 2- (CaO, MgO, TiO2. Una poderosa herramienta para el desarrollo de nuevos materiales por sinterización reactiva

    Pena, P.


    Full Text Available In this paper we set out, discuss and evaluate the work on Mullite-zirconia composites obtained by reaction sintering led and inspired by Salvador de Aza on the basis of ZrO2-Al2O3-SiO2(CaO, MgO, TiO2 multicomponent phase equilibrium diagrams. We analyze their impact on different areas of ceramic science and technology such as refractory grogs, aluminum industry, etc. The possible fields of future applications such as dental prosthesis replacing partially stabilized zirconia materials with rare earths are also reported.En este articulo se exponen, discuten y evalúan los trabajos que sobre materiales de Mullita-Circona obtenidos por sinterización reactiva dirigió e inspiro Salvador de Aza sobre la base de los diagramas de equilibrio de fase multicomponentes ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2. Se analiza su impacto en distintas áreas de la ciencia y tecnología cerámicas tales como chamotas refractarias, industria del aluminio, etc. También se proponen posibles campos de aplicación futura como es el caso de prótesis dentales sustituyendo a los materiales de circona parcialmente estabilizada con tierras raras.

  17. Effect of Rare Earth Oxides on the Microstructure and Microwave Dielectric Properties of CaO-MgO-Nb2O5-TiO2 System Ceramics

    WANG Hao; CHEN Wen; LIU Tao


    La2 O3 and SrO-doped CaO-MgO-Nb2 O5-TiO2 system ceramics were prepared by solid-state ceramic technique. The microstructure and microwave dielectric properties of CaO-MgO-Nb2 O5 -TiO2-La2 O3 ceramics can be adjusted by varying the amount of La3+ or Sr2+ ions respectively. The replacement of Ca2+ by La3+ at A-site of the ceramics increases the quality factor Q value ( at 7.6 GHz) as well as the temperature coefficient of resonant frequency τfand decreases the dielectric constant εr and the substitution of Sr2+ at A-site in this ceramics system exhibits opposite characteristics. The microwave properties of La3+ , Sr2+ -doped CaO-MgO-Nb2 O5 - TiO2 system ceramics depend on the degree of octahedral distortion inside materials .

  18. Understanding In Vivo Response and Mechanical Property Variation in MgO, SrO and SiO2 doped β-TCP

    Bose, Susmita; Tarafder, Solaiman; Banerjee, Shashwat S.; Davies, Neal M.; Bandyopadhyay, Amit


    The aim of this work is to evaluate the influence of MgO, SrO and SiO2 doping on mechanical and biological properties of β-tricalcium phosphate (β-TCP) to achieve controlled resorption kinetics of β-TCP system for maxillofacial and spinal fusion application. We prepared dense TCP compacts of four different compositions, i) pure β-TCP, ii) β-TCP with 1.0 wt. % MgO + 1.0 wt. % SrO, iii) β-TCP with 1.0 wt. % SrO + 0.5 wt. % SiO2, and iv) β-TCP with 1.0 wt. % MgO + 1.0 wt. % SrO + 0.5 wt. % SiO2, by uniaxial pressing and sintering at 1250 °C. β phase stability is observed at 1250 °C sintering temperature due to MgO doping in β-TCP. In vitro mineralization in simulated body fluid (SBF) for 16 weeks shows excellent apatite growth on undoped and doped samples. Strength degradation of TCP samples in SBF is significantly influenced by both dopant chemistry and amount of dopant. Compressive strengths for all samples show degradation in SBF over the 16 week time period with varying degradation kinetics. MgO/SrO/SiO2 doped sample shows no strength loss, while undoped TCP shows the maximum strength loss from 419 ±28 MPa to 158 ±28 MPa over the 16 week study. In case of MgO/SrO doped TCP, strength loss is slow and gradual. TCP doped with 1.0 wt. % MgO and 1.0 wt. % SrO shows excellent in vivo biocompatibility when tested in male Sprague-Dawley rats for 16 weeks. Histomorphology analysis reveals that MgO/SrO doped TCP promoted osteogenesis by excellent early stage bone remodeling as compared to undoped TCP. PMID:21419884

  19. Effects of SiO2, SrO, MgO and ZnO dopants in TCP on osteoblastic Runx2 expression

    Fielding, Gary A.; Smoot, Will; Bose, Susmita


    Calcium phosphate materials share a compositional similarity to natural bone which makes them excellent for use in orthopedic applications. Although these materials are osteoconductive, they lack strong osteoinductive capabilities and recent research has focused on the addition of biologics and pharmacologics with varying successes. In this study, trace elements that have been proven to play important roles in bone health and bone formation were incorporated into β-tricalcium phosphate compacts in their oxide forms (SiO2, ZnO, SrO, and MgO). Cell material interactions were characterized using human fetal preosteoblastic cells. An MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay was used to evaluate cellular proliferation. Cellular differentiation was evaluated using an enzymatic colorimetric alkaline phosphatase assay as well as immunohistochemistry for Runt-related transcription factor 2 (Runx2) expression. Results prove ZnO and MgO to be effective mitogenic factors and SiO2, ZnO and SrO to be capable of inducing rapid cellular differentiation. MgO was found to have little effect on the modulation of osteoblastic differentiation, likely due to more aggressive inherent cellular regulation of Mg2+. In addition to the results from the study, a signaling mechanism is proposed as to the action of the dopants for further consideration. PMID:23946240

  20. Effects of SiO2, SrO, MgO, and ZnO dopants in tricalcium phosphates on osteoblastic Runx2 expression.

    Fielding, Gary A; Smoot, Will; Bose, Susmita


    Calcium phosphate materials share a compositional similarity to natural bone, which makes them excellent for use in orthopedic applications. Although these materials are osteoconductive, they lack strong osteoinductive capabilities and recent research has focused on the addition of biologics and pharmacologics with varying successes. In this study, trace elements that have been proven to play important roles in bone health and bone formation were incorporated into β-tricalcium phosphate compacts in their oxide forms (SiO2, ZnO, SrO, and MgO). Cell material interactions were characterized using human fetal preosteoblastic cells. An MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay was used to evaluate cellular proliferation. Cellular differentiation was evaluated using an enzymatic colorimetric alkaline phosphatase assay as well as immunohistochemistry for Runt-related transcription factor 2 (Runx2) expression. Results prove ZnO and MgO to be effective mitogenic factors and SiO2, ZnO, and SrO to be capable of inducing rapid cellular differentiation. MgO was found to have little effect on the modulation of osteoblastic differentiation, likely due to more aggressive inherent cellular regulation of Mg(2+). In addition to the results from the study, a signaling mechanism is proposed as to the action of the dopants for further consideration. © 2013 Wiley Periodicals, Inc.

  1. Surface Crystallization of a MgO/Y2O3/SiO2/Al2O3/ZrO2 Glass: Growth of an Oriented β-Y2Si2O7 Layer and Epitaxial ZrO2

    Wisniewski, Wolfgang; Seidel, Sabrina; Patzig, Christian; Rüssel, Christian


    The crystallization behavior of a glass with the composition 54.7 SiO2·10.9 Al2O3·15.0 MgO·3.4 ZrO2·16.0 Y2O3 is studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) including electron backscatter diffraction (EBSD) and (scanning) transmission electron microscopy [(S)TEM] including energy-dispersive X-ray spectrometry (EDXS). This glass shows the sole surface crystallization of four different yttrium silicates of the composition Y2Si2O7 (YS). The almost simultaneous but independent nucleation of α-, β-, δ-, and ε-YS at the surface is followed by growth into the bulk, where ε-YS quickly dominates a first crystallized layer. An accumulation of Mg at the growth front probably triggers a secondary nucleation of β-YS, which forms a thin compact layer before fragmenting into a highly oriented layer of fine grained crystals occupying the remaining bulk. The residual glass between the YS growth structures allows the crystallization of indialite, yttrium stabilized ZrO2 (Y-ZrO2) and very probably μ-cordierite during cooling. Hence, this glass basically shows the inverted order of crystallization observed in other magnesium yttrium alumosilicate glasses containing less Y2O3. An epitaxial relationship between Y-ZrO2 and ε-YS is proven and multiple twinning relationships occur in the YS phases.

  2. 从相图讨论MgO-CaO-ZrO2耐火材料抗炉外精炼渣与水泥的侵蚀%Discussion on corrosion resistances of MgO -CaO -ZrO2 refractories to secondary refining slag and cement from phase diagrams




  3. The effect of CaF2 on thermodynamics of CaO-CaF2-SiO2(-MgO) slags

    Choi, Chul-Hwan; Jo, Sung-Koo; Kim, Seon-Hyo; Lee, Kwang-Ro; Kim, Jeong-Tae


    To address the role of CaF2 in the CaO-CaF2-SiO2(-MgO) slag system employed for the production of low-pressure rotor steels, the thermodynamic aspects of the slag were investigated by equilibrating it with liquid iron at 1873 K in CaO or MgO crucibles. Presaturation of slag with an oxide block piece of CaO or MgO in a Pt crucible and application of a carbon paste to the outside of an oxide crucible were designed to prevent crucible failure during the slag-metal experiments. The liquidus isotherm and phase boundary of the preceding slag system were investigated using the slag-metal equilibria. Also, the effect of CaF2 on the sulfide capacity and the activity coefficient of Fe t O were of particular interest in controlling the sulfur level and cleanliness of low-pressure rotor steels.

  4. Reduction of [Cp*Sb]4 with Subvalent Main-Group Metal Reductants: Syntheses and Structures of [(L(1) Mg)4 (Sb4 )] and [(L(2) Ga)2 (Sb4 )] Containing Edge-Missing Sb4 Units.

    Ganesamoorthy, Chelladurai; Krüger, Julia; Wölper, Christoph; Nizovtsev, Anton S; Schulz, Stephan


    [Cp*Sb]4 (Cp*=C5 Me5 ) reacts with [L(1) Mg]2 and L(2) Ga with formation of [(L(1) Mg)4 (μ4 ,η(1:2:2:2) -Sb4 )] (L(1) =iPr2 NC[N(2,6-iPr2 C6 H3 )]2 , 1) and [(L(2) Ga)2 (μ,η(2:2) -Sb4 )] (L(2) =HC[C(Me)N(2,6-iPr2 C6 H3 )]2 , 2). The cleavage of the Sb-Sb and Sb-C bonds in [Cp*Sb]4 are the crucial steps in both reactions. The formation of 1 occurred by elimination of the Cp* anion and formation of Cp*MgL(1) , while 2 was formed by reductive elimination of Cp*2 and oxidative addition of L(2) Ga to the Sb4 unit. 1 and 2 were characterized by heteronuclear NMR spectroscopy and single-crystal X-ray diffraction, and their bonding situation was studied by quantum chemical calculations.

  5. Chemically anchoring of TiO2 coating on OH-terminated Mg3(PO3)2 surface and its influence on the in vitro degradation resistance of Mg-Zn-Ca alloy

    Cao, Guoqin; Wang, Lijie; Fu, Zhenya; Hu, Junhua; Guan, Shaokang; Zhang, Caili; Wang, Liguo; Zhu, Shijie


    Surface treatment is of particular interest to slow down the in vitro degradation of Mg-based implants. In this work, micro arc oxidation (MAO) coating was fabricated on Mg-Zn-Ca alloy which has been developed by our group especially for the application of bio-implants. Evident improvement in corrosion resistance was obtained although the MAO coating was porous. In order to further diminish the contact with SBF, a composite coating was prepared by introducing a TiO2 layer by liquid phase deposition (LPD) method on the MAO pre-treated alloy. The coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results of the potentiodynamic polarization experiments showed that, compared with the bare alloy, the corrosion potential of TiO2/MAO/alloy increased from -1.771 to -1.607 V. At the same time, the corrosion current density decreased from 1.43 × 10-4 A cm-2 to 5.69 × 10-7 A cm-2. The improvement of degradation resistance in SBF was ascribed to both barrier effect and enhanced interface condition. The OH-terminated MAO layer surface can make the TiO2 layer anchor tightly on the MOA surface. The chemical bonding of composite layer induced by Mg2+ cations bridges was also analyzed.

  6. Agglomeration Control of Ultrafine Y2 O3-ZrO2 and (MgO, Y2 O3)-ZrO2 Powders Synthesized by Coprecipitation Process

    MA Yalu; ZHANG Yu; ZHENG Junping


    Chemical coprecipitation was used to produce ultrafine and easily sinterable Y2O3-stabilized and (Y2O3,MgO)-stabilized ZrO2 powders. Six precipitation processes for preparation of ZrO2-based ultrafine powders were designed separately, meanwhile different techniques used to control the agglomeration formation were proposed. By means of TEM, SEM, Raman spectroscopy and IR spectroscopy, the mechanisms of agglomeration control in the precipitation processes and post-precipitation and drying process were investigated. The experimental results show that adding appropriate anion surface active agents (such as PAA1460) or polymer (PEG1540 matching with PEG200) in aqueous solution systems during precipitation processes could reinforce charge effect and location effect for gel particles interface. Adding wetting agents to wet gels washing with distilled water during drying process could change interface structure of gel particles and decrease surface tension between gel particles. The agglomeration control in the precipitation, post-precipitation and drying processes had remarkable influence on the characteristics of powders. By adding various macromolecules in the processes, the agglomeration state could be controlled efficiently, and the characteristics of powders were improved.

  7. Towards scalable binderless electrodes: carbon coated silicon nanofiber paper via Mg reduction of electrospun SiO2 nanofibers.

    Favors, Zachary; Bay, Hamed Hosseini; Mutlu, Zafer; Ahmed, Kazi; Ionescu, Robert; Ye, Rachel; Ozkan, Mihrimah; Ozkan, Cengiz S


    The need for more energy dense and scalable Li-ion battery electrodes has become increasingly pressing with the ushering in of more powerful portable electronics and electric vehicles (EVs) requiring substantially longer range capabilities. Herein, we report on the first synthesis of nano-silicon paper electrodes synthesized via magnesiothermic reduction of electrospun SiO2 nanofiber paper produced by an in situ acid catalyzed polymerization of tetraethyl orthosilicate (TEOS) in-flight. Free-standing carbon-coated Si nanofiber binderless electrodes produce a capacity of 802 mAh g(-1) after 659 cycles with a Coulombic efficiency of 99.9%, which outperforms conventionally used slurry-prepared graphite anodes by over two times on an active material basis. Silicon nanofiber paper anodes offer a completely binder-free and Cu current collector-free approach to electrode fabrication with a silicon weight percent in excess of 80%. The absence of conductive powder additives, metallic current collectors, and polymer binders in addition to the high weight percent silicon all contribute to significantly increasing capacity at the cell level.

  8. Towards Scalable Binderless Electrodes: Carbon Coated Silicon Nanofiber Paper via Mg Reduction of Electrospun SiO2 Nanofibers

    Favors, Zachary; Bay, Hamed Hosseini; Mutlu, Zafer; Ahmed, Kazi; Ionescu, Robert; Ye, Rachel; Ozkan, Mihrimah; Ozkan, Cengiz S.


    The need for more energy dense and scalable Li-ion battery electrodes has become increasingly pressing with the ushering in of more powerful portable electronics and electric vehicles (EVs) requiring substantially longer range capabilities. Herein, we report on the first synthesis of nano-silicon paper electrodes synthesized via magnesiothermic reduction of electrospun SiO2 nanofiber paper produced by an in situ acid catalyzed polymerization of tetraethyl orthosilicate (TEOS) in-flight. Free-standing carbon-coated Si nanofiber binderless electrodes produce a capacity of 802 mAh g-1 after 659 cycles with a Coulombic efficiency of 99.9%, which outperforms conventionally used slurry-prepared graphite anodes by over two times on an active material basis. Silicon nanofiber paper anodes offer a completely binder-free and Cu current collector-free approach to electrode fabrication with a silicon weight percent in excess of 80%. The absence of conductive powder additives, metallic current collectors, and polymer binders in addition to the high weight percent silicon all contribute to significantly increasing capacity at the cell level.

  9. Properties of the ZrO2MgO/MgZrO3NiCr/NiCr triple-layer thermal barrier coating deposited by the atmospheric plasma spray process

    Mihailo R. Mrdak


    This paper presents the results of the examinations of TBC - ZrO2MgO / MgZrO3NiCr / NiCr thermal barrier layers deposited by the plasma spray process at the atmospheric pressure on substrates of Al alloys. In order to obtain the structural and mechanical properties of layers, which will provide a good heat and abrasion protection of the tail elevators of aircraft J-22 when firing '.Lightning' and 'Thunder' rockets, the deposition of three powder types was performed on 0.6 mm thick Al alloy su...

  10. Novel Flower-Like Ag-SiO2-MgO-Al2O3 Material: Preparation, Characterization and Catalytic Application in Methanol Dehydrogenation

    LI,Jing-Xia; REN,Li-Ping; DAI,Wei-Lin; CAO,Yong; FAN,Kang-Nian


    Catalytic direct dehydrogenation of methanol to formaldehyde was carried out over Ag-SiO2-MgO-Al2O3 catalysts prepared by sol-gel method.The optimal preparation mass fractions were determined as 8.3% MgO,16.5% Al2O3 and 20% silver loading.Using this optimum catalyst,excellent activity and selectivity were obtained.The conversion of methanol and the selectivity to formaldehyde both reached 100%,which were much higher than other previously reported silver supported catalysts.Based on combined characterizations,such as X-ray diffraction (XRD),scanning electronic microscopy (SEM),diffuse reflectance ultraviolet-visible spectroscopy (UV-Vis,DRS),nitrogen adsorption at low temperature,temperature programmed desorption of ammonia (NH3-TPD),desorption of CO2 (CO2-TPD),etc.,the correlation of the catalytic performance to the structural properties of the Ag-SiO2-MgO-Al2O3 catalyst was discussed in detail.This perfect catalytic performance in the direct dehydrogenation of methanol to formaldehyde without any side-products is attributed to its unique flower-like structure with a surface area less than 1 m2/g,and the strong interactions between neutralized support and the nano-sized Ag particles as active centers.

  11. The synergistic effect of catalysts on hydrogen desorption properties of MgH2–TiO2–NiO nanocomposite

    Farshad Rajabpour


    Full Text Available Abstract The high desorption temperature and slow desorption kinetics of MgH2 makes it less competitive for future mobile applications; using a catalyst accompanied by mechanical milling seems to be a good solution to overcome those problems. Therefore, the addition of TiO2 and NiO to MgH2 accompanied by 15 h of mechanical milling was considered in this study. The phase constituent and hydrogen desorption of the powder mixture were investigated using X-ray diffraction (XRD and a Sievert-type apparatus, respectively. XRD results showed that after milling, no binary or ternary compounds were formed, but hydrogen desorption time decreased and the desorbed hydrogen content increased. It seems that the increase in desorbed hydrogen was related to the simultaneous catalytic effect of TiO2 and NiO as well as mechanical milling. The results showed that the addition of both catalysts can improve the hydrogen desorption behavior of MgH2-based nanocomposite compared to the addition of only one catalyst of the same amount.

  12. Evolution of reduced Ti containing phase(s) in MgH2/TiO2 system and its effect on the hydrogen storage behavior of MgH2

    Pukazhselvan, D.; Nasani, Narendar; Correia, Pedro; Carbó-Argibay, Enrique; Otero-Irurueta, Gonzalo; Stroppa, Daniel G.; Fagg, Duncan Paul


    The present study aims to consolidate information regarding the catalytic reaction mechanism of MgH2/TiO2 hydrogen storage system. Reduction of titania, resulting to evolution of a monoxide rock salt nanocrystalline phase was identified by in-situ X-ray diffraction (XRD) study of a 3 mol% TiO2 additive mixed MgH2. Existence of homogeneously distributed Ti in a crystalline rock salt matrix was confirmed by combined analysis of X - ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and elemental chemical mapping techniques. Moreover, titanium in Ti3+ and Ti2+ valance states was confirmed by X - ray photoelectron spectroscopy (XPS). Differential scanning calorimetry (DSC) study proves that the reduced Ti oxide phases promote the low temperature dehydrogenation of MgH2. The present observations reiterate that the MgO rock salt layer existing in oxide additives loaded MgH2 is not necessarily a barrier layer that blocks the diffusion of hydrogen.

  13. [Effect of temperature on the structure of CaO-MgO-Al2O3-SiO2 nanocrystalline glass-ceramics studied by Raman spectroscopy].

    Li, Bao-Wei; Ouyang, Shun-Li; Zhang, Xue-Feng; Jia, Xiao-Lin; Deng, Lei-Bo; Liu, Fang


    In the present paper, nanocrystalline glass-ceramic of CaO-MgO-Al2O3-SiO2 system was produced by melting method. The CaO-MgO-Al2O3-SiO2 nanocrystalline glass-ceramic was measured by Raman spectroscopy in the temperature range from -190 to 310 degrees C in order to study the effect of temperature on the structure of this system nanocrystalline glass-ceramics. The results showed that different non-bridge oxygen bond silicon-oxygen tetrahedron structural unit changes are not consistent with rising temperature. Further analyses indicated that: the SiO4 tetrahedron with 2 non-bridged oxygen (Q2), the SiO4 tetrahedron with 3 non-bridged oxygen (Q(1)), which are situated at the edge of the 3-D SiO4 tetrahedrons network, and the SiO4 tetrahedron with 4 non-bridged oxygen (Q(0)), which is situated outside the 3-D network all suffered a significant influence by the temperature change, which has been expressed as: shifts towards the high wave-number, increased bond force constants, and shortened bond lengths. This paper studied the influence of temperature on CMAS system nanocrystalline glass-ceramics using variable temperature Raman technology. It provides experiment basis to the research on external environment influence on CMAS system nanocrystalline glass-ceramics materials in terms of structure and performance. In addition, the research provides experimental basis for controlling the expansion coefficient of nanocrystalline glass-ceramic of CaO-MgO-Al2O3-SiO2 system.

  14. Temperature dependence of the momentum distribution of positronium in MgF2, SiO2, and H2O

    Nagai, Y.; Kakimoto, M.; Hyodo, T.;


    Temperature dependence of the momentum distribution of delocalized Bloch-positronium in solids is studied. The momentum distribution of the positronium, which is proportional to the energy integration of the spectral function weighted with the Bose distribution, is expressed in terms...... of the effective mass and the deformation potential of the crystal for positronium. A simple formula for the shape of the positronium peak in the 1D-ACAR spectrum is derived and applied to the analysis of the experimental data for MgF2, SiO2, and H2O in wide temperature ranges. An extraordinary broadening...

  15. Performance of B-Mg Co-doped LiCoO2 for Li-ion Batteries%B-Mg共掺杂LiCoO2正极材料的性能研究

    曹景超; 肖可颂; 姜锋; 习小明; 何杜


    Cathode material of LiCo1-2yMgyByO2 was prepared at high temperature with Co3O4, Li2CO3, Mg(OH)2 and H3 BO3 as starting materials mixed at a stoichiometric ratio. The morphology, structure and Li+ diffusion coefficient were characterized by SEM, XRD and GITT, respectively. The electrochemical performance of the material assembled into CR2016 button cell was tested by using LAND tester. The results show that the LiCo0.98Mg0.01B0.01O2 cathode exhibits an initial discharge capacity of 190 mAh/g at 0.2C and 3.0~4.5 V and a retention of 88.6% after 100 cycles.%采用Co3 O4为钴源,Li2 CO3为锂源,Mg( OH)2和H3 BO3分别为镁源和硼源,按照化学计量比称取各原料并混合均匀后在高温条件下合成LiCo1-2y Mgy By O2正极材料。采用扫描电镜( SEM)、X射线衍射( XRD)和恒电流间歇滴定( GITT)分别表征了样品的形貌、结构和锂离子扩散系数。将材料组装成CR2016型扣式电池,采用LAND测试仪进行电化学性能测试,结果表明,当掺杂的摩尔总量为2.0%时,材料在3.0~4.5 V范围内以0.2C充放电首次放电比容量达到190 mAh/g,循环100次后容量保持率为88.6%。

  16. Electrocatalytic degradation of methylene blue on PbO2-ZrO2 nanocomposite electrodes prepared by pulse electrodeposition.

    Yao, Yingwu; Zhao, Chunmei; Zhao, Manman; Wang, Xiao


    PbO2-ZrO2 nanocomposite electrodes (P) were prepared by pulse electrodeposition and used for the electrocatalytic degradation of methylene blue (MB). The SEM and XRD tests show that PbO2-ZrO2 nanocomposite electrodes (P) possess more compact structure and finer grain size than PbO2-ZrO2 nanocomposite electrodes (D) prepared by direct electrodeposition. The electrochemical measurements show that PbO2-ZrO2 nanocomposite electrodes (P) have higher oxygen evolution overpotential and the oxidation regions of MB and water are significantly separated. The experimental parameters on electrocatalytic degradation of MB by PbO2-ZrO2 nanocomposite electrodes (P) were evaluated, such as initial MB concentration, current density, pH value and supporting electrolyte concentration. The results indicate that MB and COD removal efficiency of PbO2-ZrO2 nanocomposite electrodes (P) reach 100% and 72.7%, respectively, after 120 min electrolysis at initial 30 mg L(-1) MB concentration at current density of 50 mA cm(-2) in 0.2 mol L(-1) Na2SO4 supporting electrolyte solution, and the degradation of MB follows pseudo-first-order kinetics. Compared with PbO2-ZrO2 nanocomposite electrodes (D), PbO2-ZrO2 nanocomposite electrodes (P) show higher COD removal efficiency and instantaneous current efficiency with MB degradation. The experimental results demonstrate that PbO2-ZrO2 nanocomposite electrodes (P) possesses the excellent electrocatalytic properties and show great potential applications in refractory pollutants.

  17. Leonardsenite, MgAlF5(H2O)(2), a new mineral species from Eldfell Volcano, Heimaey Island, Iceland

    Mitolo, Donatella; Garavelli, Anna; Zunic, Tonci Balic


    is white and the luster is earthy. The calculated density is 2.31 g cm(-3). Leonardsenite is orthorhombic, space group Imma; the lattice parameters, obtained from Rietveld refinement of the XRPD data, are: a 7.055(1) A, b 10.117(2) angstrom, c 6.813(1) angstrom, V 486.3(1) angstrom(3), and Z = 4. The eight...... microscope produced a mean elemental composition as follows (wt.: Mg 14.66, Al 16.16, F 52.98, 0 15.88, H 1.78, total 101.46. The corresponding empirical formula, calculated on the basis of 2 cations pfu, is Mgi.00Ali 004.64(011)0.361E5.00(1420)1 29. On the basis of chemical analyses and X-ray diffraction...

  18. Formation Mechanism of CaO-SiO2-Al2O3-(MgO) Inclusions in Si-Mn-Killed Steel with Limited Aluminum Content During the Low Basicity Slag Refining

    Wang, Kunpeng; Jiang, Min; Wang, Xinhua; Wang, Ying; Zhao, Haoqian; Cao, Zhanmin


    Pilot trails were carried out to study the formation mechanism of CaO-SiO2-Al2O3-(MgO) inclusions in tire cord steel. 48 samples were taken from 8 heats of liquid steel during secondary refining, which were subsequently examined by an automatic scanning electron microscope with energy dispersive spectrometer (SEM-EDS). Characteristics of thousands of oxide inclusions at different refining stages were obtained, including their compositions, sizes, morphologies, etc. Based on the obtained information of inclusions, details during formation of CaO-SiO2-Al2O3-(MgO) inclusions were revealed and a new mechanism was proposed, including their origin, formation, and evolution during the refining process. It was found that CaO-SiO2-Al2O3-(MgO) inclusions were initially originated from the CaO-SiO2-MnO-(MgO) inclusions, which were formed during BOF tapping by the coalescence between MnO-SiO2 deoxidation products and the emulsified slag particles because of violent flow of steel. This can be well confirmed by the evaluation of the formation thermodynamics of CaO-SiO2-MnO-(MgO) inclusions, which was proved very difficult to be produced by intrinsic reactions inside liquid steel. Because of chemical reactions between CaO-SiO2-MnO-(MgO) inclusions and molten steel, they were mainly changed into CaO-SiO2-MnO-Al2O3-(MgO) and partially into CaO-SiO2-Al2O3-(MgO), which may be detrimental to the cold drawing ability of coils. Based on this finding, improvements were made in industrial production during BOF tapping and secondary refining. The results indicated that such (CaO-SiO2)-based inclusions existed in conventional process were effectively decreased after the improvements.

  19. An Investigation into the Corrosion Behavior of MgO/ZrO2 Nanocomposite Coatings Prepared by Plasma Electrolytic Oxidation on the AZ91 Magnesium Alloy

    Eslamzadeh, Nasrollah; Ebrahimi-Kahrizsangi, Reza; Karbasi, Saeed; Zarebidaki, Arman; Gharavi, Farhad


    Plasma electrolytic oxidation (PEO) of AZ91 Mg alloys was performed in ZrO2 nanoparticles containing Na2SiO3-based electrolytes. The phase composition and the microstructure of PEO coatings were analyzed by x-ray diffraction and scanning electron microscopy followed by energy dispersive spectroscopy. Pitting corrosion properties of the coatings were investigated using cyclic polarization and electrochemical impedance spectroscopy tests in a Ringer solution. The results showed the better pitting corrosion resistance of the composite coating, as compared to the oxide one, due to the thickened inner layer and the decrease in the surface defects of the composite coating. Also, the PEO process decreased the corrosion current density from 25.06 µA/cm2 in the Mg alloy to 2.7 µA/cm2 in the oxide coating and 0.47 µA/cm2 in the composite coating.

  20. Hydrous melting and partitioning in and above the mantle transition zone: Insights from water-rich MgO-SiO2-H2O experiments

    Myhill, R.; Frost, D. J.; Novella, D.


    Hydrous melting at high pressures affects the physical properties, dynamics and chemical differentiation of the Earth. However, probing the compositions of hydrous melts at the conditions of the deeper mantle such as the transition zone has traditionally been challenging. In this study, we conducted high pressure multianvil experiments at 13 GPa between 1200 and 1900 °C to investigate the liquidus in the system MgO-SiO2-H2O. Water-rich starting compositions were created using platinic acid (H2Pt(OH)6) as a novel water source. As MgO:SiO2 ratios decrease, the T -XH2O liquidus curve develops an increasingly pronounced concave-up topology. The melting point reduction of enstatite and stishovite at low water contents exceeds that predicted by simple ideal models of hydrogen speciation. We discuss the implications of these results with respect to the behaviour of melts in the deep upper mantle and transition zone, and present new models describing the partitioning of water between the olivine polymorphs and associated hydrous melts.

  1. Oxidative dehydrogenation of n-butane over vanadium magnesium oxide catalysts supported on nano-structured MgO and ZrO2: effect of oxygen capacity of the catalyst.

    Lee, Howon; Lee, Jong Kwon; Hong, Ung Gi; Song, In Kyu; Yoo, Yeonshick; Cho, Young-Jin; Lee, Jinsuk; Chang, Hosik; Jung, Ji Chul


    Vanadium-magnesium oxide catalysts supported on nano-structured MgO and ZrO2 (Mg3(VO4)2/MgO/ZrO2) were prepared by a wet impregnation method with a variation of Mg:Zr ratio (8:1, 4:1, 2:1, and 1:1). For comparison, Mg3(VO4)2/MgO and Mg3(VO4)2/ZrO2 catalysts were also prepared by a wet impregnation method. The prepared catalysts were applied to the oxidative dehydrogenation of n-butane in a continuous flow fixed-bed reactor. Mg3(VO4)2/MgO/ZrO2 (Mg:Zr = 4:1, 2:1, and 1:1) and Mg3(VO4)2/ZrO2 catalysts showed a stable catalytic activity during the whole reaction time, while Mg3(VO4)2/MgO/ZrO2 (8:1) and Mg3(VO4)2/MgO catalysts experienced a severe catalyst deactivation. Deactivation of Mg3(VO4)2/MgO/ZrO2 (8:1) and Mg3(VO4)2/MgO catalysts was due to their low oxygen mobility. Effect of oxygen capacity (the amount of oxygen in the catalyst involved in the reaction) of the supported Mg3(V04)2 catalysts on the catalytic performance in the oxidative dehydrogenation of n-butane was investigated. Experimental results revealed that oxygen capacity of the catalyst was closely related to the catalytic activity in the oxidative dehydrogenation of n-butane. A large oxygen capacity of the catalyst was favorable for obtaining a high catalytic activity in this reaction. Among the catalysts tested, Mg3(VO4)2/MgO/ZrO2 (4:1) catalyst with the largest oxygen capacity showed the best catalytic performance.

  2. Effects of basicity and MgO content on the viscosity of the SiO2-CaO-MgO-9wt%Al2O3 slag system

    Yun-ming Gao; Shao-bo Wang; Chuan Hong; Xiu-juan Ma; Fu Yang


    The effects of basicity and MgO content on the viscosity of SiO2-CaO-MgO-9wt%Al2O3 slags with basicity from 0.4 to 1.0 and MgO content from 13wt%to 19wt%were investigated using the rotating cylinder method. A correlation between the viscosity and the slag structure was determined by Fourier transform infrared (FTIR) spectroscopy. It is indicated that the complex network structure of the slag melt is depolymerized into simpler network units with increasing basicity or MgO content, resulting in a continuous decrease in viscosity of the slag. The viscosity is strongly dependent on the combined action of basic oxide components in the slag. Under the present experimental conditions, increasing the basicity is found to be more effective than increasing the MgO content in decreasing the viscosity of the slag. At higher temperatures, the increase of basicity or MgO content does not appreciably decrease the viscosity of the slag, as it does at lower tem-peratures. The calculated activation energy of viscous flow is between 154 and 200 kJ·mol-1, which decreases with an increase in basicity from 0.4 to 1.0 at a fixed MgO content in the range of 13wt%to 19wt%.

  3. Significant enhancement of yellow-green light emission of TiO2 thin films using Au localized surface plasmons: effect of dielectric MgO spacer layer thickness.

    Zhang, Cen; Liu, Weizhen; Xu, Haiyang; Ma, Jiangang; Liu, Yichun


    TiO2/MgO/Au composite thin films with different MgO spacer layer thicknesses (0-41 nm) were fabricated on c-sapphire substrates by sputtering and pulsed laser deposition. Through optimizing the thickness of MgO spacer layer, which can effectively prevent nonradiative Förster resonant energy transfer and charge transfer between Au and TiO2, defect-related yellow-green light emission of TiO2 thin film was greatly enhanced - 12 times. The enhancement mechanism is attributed to the efficient increase of luminescence efficiency of deep levels in TiO2 induced by resonant coupling between localized surface plasmons in Au nanoparticles and electron-hole pairs in defect-related levels of TiO2.

  4. Thermodynamic model of sulphide capacity in CaO-SiO2-MgO-Al2O3 ironmaking slags%CaO-SiO2-MgO-Al2O3炼铁渣系硫化物容量的热力学模型

    张盟; 郭汉杰; 丁汝才; 王效东; 史成斌; 杨学民


    基于炉渣离子-分子共存理论(IMCT)建立了CaO-SiO2-MgO-Al2O3炼铁渣系的硫化物容量预报模型,即IMCT-CS2-模型,比较了该渣系1773 K时实测的硫化物容量、IMCT-CS2-模型预报的硫化物容量及其他五种硫化物容量模型的计算结果.结果表明,由IMCT-CS2-模型预报的1773K时CaO-SiO2-MgO-Al2O3炼铁渣系的硫化物容量更精确.本文建立的IMCT-CS2-模型不仅可计算该渣系的总硫化物容量,而且可计算该渣系中自由CaO和MgO各自的硫化物容量.1 773 K时CaO-SiO2-MgO-Al2O3炼铁渣系中Al2O3质量分数由10%增加到17%,CaO质量分数由38%增加到44%,MgO质量分数由12%降低到4%可使自由CaO对该渣系的总硫化物容量贡献率由97%提高到99%,同时使自由MgO的贡献率由3%降低到1%.%A prediction model of sulphide capacity in CaO-SiO2-MgO-Al2O3 slag systems was developed based on the ion and molecule coexistence theory (IMCT) of slags, i. e. , IMCT-Cs2- model. The predicted sulphide capacity by the IMCT-Cs2- model was compared with the measured one from experiments and the predicted one by other five prediction models of sulphide capacity. The predicted sulphide capacity of CaO-SiO2-MgO-Al2O3 slags at 1 773 K by the developed IMCT-Cs2- model has a higher accuracy than the measured one as well as the predicted one by other sulphide capacity models. The developed IMCT-Cs2- model can calculate not only the total sulphide capacity of the slags but also the respective sulphide capacity of free CaO and MgO in the slags. Increasing the A12 03 content from 10% to 17% , increasing the CaO content from 38 % to 44 % and decreasing the MgO content from 12% to 4% can improve the contribution ratio of free CaO from 97% to 99 % and decrease the contribution ratio of free MgO from 3% to about 1% to the total sulphide capacity of CaO-SiO2-MgO-Al2O3 slags.

  5. A study on microstructure and corrosion resistance of ZrO2-containing PEO coatings formed on AZ31 Mg alloy in phosphate-based electrolyte

    Zhuang, J. J.; Guo, Y. Q.; Xiang, N.; Xiong, Y.; Hu, Q.; Song, R. G.


    ZrO2-containing ceramic coatings formed on the AZ31 Mg alloy were fabricated in an alkaline electrolyte containing sodium phosphate and potassium fluorozirconate (K2ZrF6) by plasma electrolytic oxidation (PEO). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) techniques were used to study the phase structure and composition of the coatings. It is indicated that the coatings formed in the K2ZrF6-containing electrolyte were composed of MgO, MgF2 and t-ZrO2. Morphological investigation carried out by scanning electron microscopy (SEM) and stereoscopic microscopy, revealed that the uniformity of coatings increased and roughness of coatings decreased after the addition of K2ZrF6. Electrochemical investigation was achieved by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) test. The results showed that the PEO coating formed in K2ZrF6-containing electrolyte exhibited an improved corrosion resistance than that of the coating formed in K2ZrF6-free electrolyte. In addition, the polarization and EIS tests results both showed that the suitable concentration (2.5 g/l) of K2ZrF6 is of significant ability to improve the corrosion resistance of coatings. However, 5 g/l and 10 g/l K2ZrF6 has a negative effect on improving the corrosion resistance of PEO coatings compared with the coating formed in 2.5 g/l K2ZrF6-containing electrolyte.


    李建朝; 齐素慈; 许继芳; 张捷宇; 李竹



  7. Research on Properties of Low Fluorine CaF2-CaO-Al2O3-MgO-SiO2 Refining Slag%低氟CaF2-CaO-Al2O3-MgO-SiO2系精炼渣的性能

    史冠勇; 张廷安; 牛丽萍; 豆志河


    设计了精炼铜-铬合金用低氟CaF2-CaO-Al2O3-MgO-SiO2五元渣系,并研究了其粘度、密度、表面张力及熔化温度等性能.结果表明,该渣系的熔化温度在1336~1402℃之间;高温F该渣系的密度和表面张力均随温度升高而减小,且随CaF2含量和MgO含量增加逐渐降低;增加CaF2添加量可降低渣系粘度;CaF2含量较低时,MgO含量增加也可降低渣系粘度,CaF2含量较高时,渣粘度在MgO含量为6%时最小,MgO含量续增加到9%时粘度反而上升.该渣系粘度较低,表面张力较小,具有良好的精炼效果.%Low fluorine CaF2-CaO-Al2O3-MgO-SiO2 slag system was used as refining slag for preparation of Cu-Cr alloy. Its viscosity, density, surface tension and melting temperature were studied. The results indicated that the melting temperature of the slag was between 1336-1402'C. The density and surface tension of CaF2-CaO-Al2O3-MgO-SiO2 slag decreased with increasing of temperature, adding of CaF2 and MgO could decrease its density and surface tension. Its viscosity decreased with increasing of MgO and CaF2 content, and achieved the minimum value when MgO content was 6%, and increased when MgO content up to 9% with 10% and 15% CaF2 content. The slag had lower surface tension and better fluidity, so the refining efficiency with it was very good.

  8. Titanium-bearing phases in the Earth's mantle (evidence from experiments in the MgO-SiO2-TiO2 ±Al2O3 system at 10-24 GPa)

    Sirotkina, Ekaterina; Bobrov, Andrey; Bindi, Luca; Irifune, Tetsuo


    Introduction Despite significant interest of experimentalists to the study of geophysically important phase equilibria in the Earth's mantle and a huge experimental database on a number of the model and multicomponent systems, incorporation of minor elements in mantle phases was mostly studied on a qualitative level. The influence of such elements on structural peculiarities of high-pressure phases is poorly investigated, although incorporation of even small portions of them may have a certain impact on the PT-parameters of phase transformations. Titanium is one of such elements with the low bulk concentrations in the Earth's mantle (0.2 wt % TiO2) [1]; however, Ti-rich lithologies may occur in the mantle as a result of oceanic crust subduction. Thus, the titanium content is 0.6 wt% in Global Oceanic Subducted Sediments (GLOSS) [2], and 1.5 wt% TiO2, in MORB [3]. In this regard, accumulation of titanium in the Earth's mantle is related to crust-mantle interaction during the subduction of crustal material at different depths of the mantle. Experimental methods At 10-24 GPa and 1600°C, we studied the full range of the starting materials in the MgSiO3 (En) - MgTiO3 (Gkl) system in increments of 10-20 mol% Gkl and 1-3 GPa, which allowed us to plot the phase PX diagram for the system MgSiO3-MgTiO3 and synthesize titanium-bearing phases with a wide compositional range. The experiments were performed using a 2000-t Kawai-type multi-anvil high-pressure apparatus at the Geodynamics Research Center, Ehime University (Japan). The quenched samples were examined by single-crystal X-ray diffractometer, and the composition of phases was analyzed using SEM-EDS. Results The main phases obtained in experiments were rutile, wadsleyite, MgSiO3-enstatite, MgTiO3-ilmenite, MgTiSi2O7 with the weberite structure type (Web), Mg(Si,Ti)O3 and MgSiO3 with perovskite-type structure. At a pressure of 13 GPa for Ti-poor bulk compositions, an association of En+Wad+Rt is replaced by the


    Seyed Mehdi Sajjadi


    Full Text Available Ni-Co/Al2O3-MgO-ZrO2 nanocatalyst with utilization of two different zirconia precursors, namely, zirconyl nitrate hydrate (ZNH and zirconyl nitrate solution (ZNS, was synthesized via the sol-gel method. The physiochemical properties of nanocatalysts were characterized by XRD, FESEM, EDX, BET and FTIR analyses and employed for syngas production from CO2-reforming of CH4. XRD patterns, exhibiting proper crystalline structure and homogeneous dispersion of active phase for the nanocatalyst ZNS precursor employed (NCAMZ-ZNS. FESEM and BET results of NCAMZ-ZNS presented more uniform morphology and smaller particle size and consequently higher surface areas. In addition, average particle size of NCAMZ-ZNS was 15.7 nm, which is close to the critical size for Ni-Co catalysts to avoid carbon formation. Moreover, FESEM analysis indicated both prepared samples were nanoscale. EDX analysis confirmed the existence of various elements used and also supported the statements made in the XRD and FESEM analyses regarding dispersion. Based on the excellent physiochemical properties, NCAMZ-ZNS exhibited the best reactant conversion across all of the evaluated temperatures, e.g. CH4 and CO2 conversions were 97.2 and 99% at 850 ºC, respectively. Furthermore, NCAMZ-ZNS demonstrated a stable yield with H2/CO close to unit value during the 1440 min stability test.

  10. Influence of heat treatments upon the mechanical properties and in vitro bioactivity of ZrO2-toughened MgO-CaO-SiO2-P2O5-CaF2 glass-ceramics.

    Li, Huan-Cai; Wang, Dian-Gang; Meng, Xiang-Guo; Chen, Chuan-Zhong


    Zirconia-toughened MgO-CaO-SiO2-P2O5-CaF2 glass-ceramics are prepared using sintering techniques, and a series of heat treatment procedures are designed to obtain a glass-ceramic with improved properties. The crystallization behavior, phase composition, and morphology of the glass-ceramics are characterized. The bending strength, elastic modulus, fracture toughness, and microhardness of the glass-ceramics are investigated, and the effect mechanism of heat treatments upon the mechanical properties is discussed. The bioactivity of glass-ceramics is then evaluated using the in vitro simulated body fluid (SBF) soaking test, and the mechanism whereby apatite forms on the glass-ceramic surfaces in the SBF solution is discussed. The results indicate that the main crystal phase of the G-24 sample undergoing two heat treatment procedures is Ca5(PO4)3F (fluorapatite), and those of the G-2444 sample undergoing four heat treatment procedures are Ca5(PO4)3F and β-CaSiO3 (β-wollastonite). The heat treatment procedures are found to greatly influence the mechanical properties of the glass-ceramic, and an apatite layer is induced on the glass-ceramic surface after soaking in the SBF solution.

  11. FeO2/MgO(1 0 0) supported cluster: Computational pursual for a low-cost and low-temperature CO nanocatalyst

    Zamora, A. Y.; Reveles, J. U.; Mejia-Olvera, R.; Baruah, T.; Zope, R. R.


    We study the electronic and catalytic properties of FeO2 adsorbed on a MgO(1 0 0) surface which shows potential as a novel low-cost and low-temperature CO nanocatalyst in an overall exothermic reaction. The CO oxidation may be separated into two steps, namely (1) oxidation of CO by the metal oxide leaving a reduced metal oxide and (2) oxidation of the reduced metal by oxygen to regenerate the active metal oxide. It is found that CO and O2 adsorption energies are the driving force for the CO oxidation by providing the energy required to surmount the activation energies along the reaction path. A low CO chemisorption binding energy (of the order of 0.4 eV) that avoids the blocking of the active metal sites (CO poisoning) for processes following the LH reaction mechanism, and Low energy barriers (around 0.6 eV) along the reaction path that enable the reaction to occur at low temperatures (∼100 °C). Examples of catalyst formulations that fulfill the above requirements and remain stable under moisture, are Aux nanoparticles adsorbed on base transition metal oxides [21], and Co3O4 nanorods [13]. In a recent report, Li et al. [22] proposed Fe-anchored graphene oxide as a low-cost CO catalyst. Having found that the LH mechanism presents a large energy barrier of 2 eV, Li et al. proposed an Eley-Rideal mechanism, in which CO reacted with an adsorbed and activated O2 molecule to form a carbonate-like intermediate with an energy barrier of only 0.6 eV. Martynova et al. [23] studied the low-temperature CO oxidation of Ruthenium oxide films, finding that the reaction sets in only when the oxygen coverage exceeded 1 monolayer (1 ML) and presents a low energy barrier of 0.6 eV in the range of 127-197 °C. Xie. et al. [13] experimentally studied the low-temperature oxidation of CO catalyzed by Co3O4 nanorods. It was found that the nanorods preferentially exposed the {1 1 0} planes, favoring the presence of active Co3+ species at the surface and with an activating energy toward

  12. Structural and thermal characterization of CaO-MgO-SiO2-P2O5-CaF2 glasses

    Kansal, Ishu; Goel, Ashutosh; Tulyaganov, Dilshat U.; Rajagopal, Raghu R.; Ferreira, Jose M.


    The paper presents the influence of varying CaO/MgO ratio on the structure and thermal properties of CaO-MgO-SiO2-P2O5-CaF2 glasses. A series of eight glass compositions in the glass forming region of diopside (CaMgSi2O6) - fluorapatite [Ca5(PO4)3F] - wollastonite (CaSiO3) ternary system have been designed and synthesized by varying diopside/wollastonite ratio in glasses. The as prepared melt-quenched glasses have been characterized for their structure by infrared spectroscopy (FTIR) and magic angle spinning (MAS)-nuclear magnetic resonance (NMR) spectroscopy. Silicon is predominantly present as Q2 (Si) species, while phosphorus tends to coordinate in orthophosphate environment in all the investigated glasses. The change in CaO/MgO ratio had an insignificant affect on the structure of glasses. The thermal sintering and crystallization parameters for the studied glasses have been obtained from differential thermal analysis (DTA) while crystalline phase fractions in the sintered glass-ceramics have been analyzed by X-ray diffraction adjoined with Rietveld refinement. Diopside, fluorapatite, wollastonite and pseudowollastonite have crystallized as the main crystalline phases in all the glass-ceramics with their content varying with respect to variation in CaO/MgO ratio in glasses. Scanning electron microscopy (SEM) has been used to shed light on the microstructure of glass-ceramics. The possible implications of structure and sintering behaviour of glasses on their bioactivity have been discussed.

  13. Thermochemistry of CaO-MgO-Al2O3-SiO2 (CMAS) and Advanced Thermal and Environmental Barrier Coating Systems

    Costa, Gustavo C. C.; Zhu, Dongming


    CaO-MgO-Al2O3-SiO2 (CMAS) oxides are constituents in a broad number of materials and minerals which have recently inferred to discussions in materials science, planetary science, geochemistry and cosmochemistry communities. In materials science, there is increasing interest in the degradation studies of thermal (TBC) and environmental (EBC) barrier coatings of gas turbines by molten CMAS. These coatings have been explored to be applied on silicon-based ceramics and composites which are lighter and more temperature capable hot-section materials of gas turbines than the current Ni-based superalloys. The degradation of the coatings occurs when CMAS minerals carried by the intake air into gas turbines, e.g. in aircraft engines, reacts at high temperatures (1000C) with the coating materials. This causes premature failure of the static and rotating components of the turbine engines. We discuss some preliminary results of the reactions between CMAS and Rare-Earth (RE Y, Yb and Gd) oxide stabilized ZrO2 systems, and stability of the resulting oxides and silicates.

  14. Sol-gel-derived bioactive glass containing SiO2-MgO-CaO-P2O5 as an antibacterial scaffold.

    Fooladi, Abbas Ali Imani; Hosseini, Hamideh Mahmoodzadeh; Hafezi, Forough; Hosseinnejad, Fatemeh; Nourani, Mohammad Reza


    Bioactive glass (BG) composites with a base of SiO2-Na2O-CaO-P2O5 are biocompatible biomaterials. The assessment of their abilities for medical applications has interested researchers. We produced a BG-containing SiO2-MgO-CaO-P2O5 by the sol-gel method. To determine the antibacterial effects, we analyzed the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) properties of this product on three microorganisms, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, known causative agents for biofilm formation on implant surfaces. In addition, we performed the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay to study the cytotoxic effects of our composite on animal cells. Our results demonstrated that our BG product inhibited the growth of bacteria in a concentration-dependent manner without any cytotoxic effects. Therefore, our BG product can be utilized as an appropriate implant for treating bone and tooth defects.

  15. Viscosity and structure evolution of the SiO2-MgO-FeO-CaO-Al2O3 slag in ferronickel smelting process from laterite

    Lv X.M.


    Full Text Available The SiO2 fractions in laterite-nickel ores are quite high, thus certain amount of lime should be used as fluxing material to achieve good fluidity and desulfurization capacity in industrial smelting process. However, this operation leads to an additional cost of lime. In addition, the increase of slag volume decreases the effective furnace volume. To avoid such problem, partial reduction of FeO has been suggested. Therefore, the high SiO2, low MgO and FeO and very little CaO slag is formed, which was less studied in the previous literature. Therefore, the viscosity and slag structure are investigated in the present study through FT-IR and Raman analysis methods. Experimental results show that the slag is a mixture of liquid and solid phases under the experimental temperature. The FT-IR and Raman spectra show that the fractions of the complex polymerization structure decrease significantly with the increase of FeO content and slag basicity, resulting in the decrease of apparent viscosity.

  16. Characterization of Ni porous electrode covered by a thin film of LiMg 0.05Co 0.95O 2

    Simonetti, E.; Presti, R. Lo

    A porous electrode of nickel covered by a thin film of lithium cobaltite doped with magnesium (LiMg 0.05Co 0.95O 2) was prepared in order to protect nickel cathode against dissolution into the molten carbonate. A sol impregnation technique was used to deposit gel precursors on the porous surface of the substrate; the covered substrate was submitted to thermal treatments, which produced a lithium cobaltite layer. The cathode was characterized by the following measurements: biaxial bending test, SEM/EDX analysis, which demonstrated the uniformity of the lithium cobaltite layer and the presence of cobalt homogeneously distributed over the nickel particles, electrical conductivity. To test the cathodic performance of the material under study a cell was assembled and tested in a 10 cm × 10 cm electrodes area plant. The cell performance during the time was studied carrying out polarization curves for many hours (more than 1000 h). To determine the influence of the cathodic gas composition on the electrode performance the atmosphere was changed maintaining alternatively at a constant value the partial pressure of CO 2 and O 2. In such a way the kinetic effect of the single gas was studied. By the technique of IR interruption the internal resistance of the cell was measured.

  17. Synthesis of pigments of Fe2O3·SiO2 system, with Ca, Mg, or Co oxide additions

    Dimitrov, T.; Kozhukharov, S.; Velinov, N.


    The present research work is based on the comparative evaluation of the Ca, Mg, and Co dopant impact on the properties of new ceramic pigments from the system Fe2O3·SiO2 obtained via classical ceramic technology. This approach enabled determination of the optimal temperature for the synthesis and the most appropriate mineralizer. The obtained specimens were submitted to systematical analysis, including X-ray Diffraction (XRD) spectroscopy, Electron Paramagnetic Resonance (EPR) analysis and Mössbauer spectroscopy for crystalline phase determination. The color characteristics are quantified by spectrophotometric measurements. The pigments particle size has been determined by Scanning Electron Microscopy (SEM), combined by Energy Dispersion X-ray spectroscopy (EDX). The obtained results enabled to determine the correlation between the calcination temperature and the phase compositions of the obtained pigments. In addition, some interesting magnetic properties were detected for the Co-doped composition. (Author)

  18. Solubilities of Chlorine in CaO-SiO2-Al2O3-MgO Slags: Correlation Between Sulfide and Chloride Capacities

    Okeda, M.; Hasegawa, M.; Iwase, M.


    To derive a correlation between sulfide and chloride capacities through our own systematic experimental studies by using a gas equilibrium technique involving Ar-H2-H2O-HCl gas mixtures, the solubilities of chlorine were determined for CaO-SiO2-MgO-Al2O3 slags at temperatures between 1673 K and 1823 K (1400 °C and 1550 °C). As a formula to correlate sulfide and chloride capacities, the following equation that is the function of temperature only was obtainable; 2log C_{{Cl}} - log C_{{S}} = - 64.4 + {82,890/{T({{K})}}} ± 0.75 whereas chloride capacities were formulated as the function of temperature and optical basicity in the following equation: 2log C_{{Cl}} = ( {43.6 - {54,600/{T({{K})}}}} )Uplambda + ( { - 39.2 + {60,200/{T({{K})}}}} ) ± 0.5{.}

  19. Sulfide Capacities of CaO-MgO-Al2O3-SiO2-CrO x Slags

    Wang, Lijun; Wang, Yaxian; Chou, Kuo-chih; Seetharaman, Seshadri


    The sulfide capacities of CaO-MgO-Al2O3-SiO2-CrO x slags were measured by gas-slag equilibration method in the temperature range of 1823 K to 1898 K (1550 °C to 1625 °C) to reveal the effect of CrO x on the sulfide capacities of slags. Both higher basicity and temperature enhanced sulfide capacities. The CrO x additions in the range of 0 to 5 mass pct increased the sulfide capacity, but, further increase of CrO x contents to 7 pct was found to lower the sulfide capacity. Utilizing the relationship for estimating the ratio of Cr(II)/Cr(III) put forward by the present authors, the influence of Cr(II) on the sulfide capacities of the slags studied is discussed.

  20. Preparation and characterization on nano-hybrid composite solid polymer electrolyte of PVdF-HFP /MG49-ZrO2 for battery application

    Lee T., K.; Ahmad, A.; Hasyareeda, N.


    Initial study on nano composite polymer electrolyte of PVdF-HFP/MG49-ZrO2 has been done. The zirconium was synthesis via in-situ sol-gel method in a dissolved polymer blends. The effects of different concentrations of zirconium and pH values have been investigated on nano composite polymer (NCP). Analysis impedance show that only at 6 wt. % of zirconium for all pH values show a semi-circle arc which have lowest value of bulk resistance. No ionic conductivity value is obtain due to the absent of ion charge carriers. Analysis of XRD revealed that crystallinity phase of the nano composite polymer was affect by different pH values. However, no significant changes have been observed in IR bands. This could well indicate that different pH medium did not affect the chemical bonding in the structure.

  1. Effect of calcium fluoride on sintering behaviour of SiO2-CaO-Na2O-MgO glass-ceramic system

    Bahman Mirhadi


    Full Text Available The crystallization characteristics of glasses based on the SiO2-CaO-Na2O-MgO (SCNM system containing calcium fluoride (CaF2 have been investigated by differential thermal analysis (DTA, X-ray diffraction (XRD and scanning electron microscopy (SEM. The partial replacement of CaO by CaF2 in the studied glass-ceramics led to the development of different crystalline phase assemblages, including wollastonite and diopside using various heat-treatment processes. With the increase of CaF2 content, the crystallization temperature of the glass and the strength of the crystallization peak temperature decreases. Addition of CaF2 up to 6.0 mol%, as expected, improved the sinterability. This sample reached to maximum density by sintering at 950 °C.

  2. Modelling Equilibrium and Fractional Crystallization in the System MgO-FeO-CaO-Al2O3-SiO2

    Herbert, F.


    A mathematical modelling technique for use in petrogenesis calculations in the system MgO-FeO-CaO-Al2O3-SiO2 is reported. Semiempirical phase boundary and elemental distribution information was combined with mass balance to compute approximate equilibrium crystallization paths for arbitrary system compositions. The calculation is applicable to a range of system compositions and fractionation calculations are possible. The goal of the calculation is the computation of the composition and quantity of each phase present as a function of the degree of solidification. The degree of solidification is parameterized by the heat released by the solidifying phases. The mathematical requirement for the solution of this problem is: (1) An equation constraining the composition of the magma for each solid phase in equilibrium with the liquidus phase, and (2) an equation for each solid phase and each component giving the distribution of that element between that phase and the magma.

  3. Effect of crystallization of CaO-P2O5-SiO2-MgO-F glass-ceramics on its mechanical properties


    The microstructure of CaO-P2O5-SiO2-MgO-F glass-ceramics during crystallization were investigated and the crystallized phases wereidentified with DTA (Differential Thermal Analysis), SEM (Scanning Electron Microscope) and XRD (X- ray Diffraction) techniques. The mechanical properties such as bending strength and fracture toughness, as well as their changes with advancing crystallization were determined. The results show that the changes of the mechanical properties are correlated with the microstructures. The sample heated up to 810℃ and soaked for 4 h has smaller crystalline size and less volum fraction of fluorophlogopite, so it has higher bending strength (about 190 MPa), and higher crack toughness (about 2.63 MPa·m1/2).

  4. Process-Parameter-Dependent Optical and Structural Properties of ZrO2MgO Mixed-Composite Films Evaporated from the solid Solution

    Sahoo, N. K.; Shapiro, A. P.


    The process-parameter-dependent optical and structural properties of ZrO2MgO mixed-composite material have been investigated. Optical properties were derived from spectrophotometric measurements. By use of atomic force microscopy, x-ray diffraction analysis, and energy-dispersive x-ray (EDX) analysis, the surface morphology, grain size distributions, crystallographic phases, and process-dependent material composition of films have been investigated. EDX analysis made evident the correlation between the oxygen enrichment in the films prepared at a high level of oxygen pressure and the very low refractive index. Since oxygen pressure can be dynamically varied during a deposition process, coatings constructed of suitable mixed-composite thin films can benefit from continuous modulation of the index of refraction. A step modulation approach is used to develop various multilayer-equivalent thin-film devices.

  5. Biological effects of TiO2 and CeO2 nanoparticles on the growth, photosynthetic activity, and cellular components of a marine diatom Phaeodactylum tricornutum.

    Deng, Xiang-Yuan; Cheng, Jie; Hu, Xiao-Li; Wang, Ling; Li, Da; Gao, Kun


    It is very important to have a good understanding of the biological effects of nanoparticles (NPs) on marine diatoms. In this study, the physiological and biochemical responses of a marine diatom Phaeodactylum tricornutum to titanium dioxide NPs (nano-TiO2) and cerium oxide NPs (nano-CeO2) were compared and evaluated using 96h growth tests in a batch-culture system. At 96h of exposure, the growth inhibition rate (IR, %) of P. tricornutum increased from 5.46 to 27.31% with increasing nano-TiO2 concentrations from 2.5 to 40mgL(-1). The maximum IR of 49.59% occurred in 40mgL(-1) nano-TiO2 treatments at 48h of exposure. Growth of the diatom was increased in low nano-CeO2 treatments (≤5mgL(-1)), but was inhibited in high nano-CeO2 treatments (≥10mgL(-1)). Large aggregates of NPs were attached to the cells of P. tricornutum in 20 and 40mgL(-1) nano-TiO2 and nano-CeO2 treatments. In addition, the effective quantum yields (ΦPSII) of P. tricornutum in 40mgL(-1) nano-TiO2 and nano-CeO2 treatments were 83.33 and 71.13% of that in the controls at 96h of exposure, respectively. Compared with that of the controls at 96h of exposure, chlorophyll a content, soluble sugar content, malondialdehyde (MDA) content, SOD and POD activities of P. tricornutum in 40mgL(-1) nano-TiO2 and nano-CeO2 treatments increased by 57.56, 142.97, 373.25, 698.76, 204.85% and 21.43, 89.41, 194.97, 340.05, 502.86%, while soluble protein content decreased by 70.38 and 28.64%, respectively. These findings will be helpful to understand the effect mechanisms of NPs on marine organisms.

  6. UV/TiO2 and UV/TiO2/chemical oxidant processes for the removal of humic acid, Cr and Cu in aqueous TiO2 suspensions.

    Jung, J-T; Choi, J-Y; Chung, J; Lee, Y-W; Kim, J-O


    The objective of this study was to investigate the treatment efficiency of UV/TiO2 and UV/TiO2/chemical oxidant processes for the removal of humic acid and hazardous heavy metals in aqueous TiO2 suspensions. The reaction rate (k) of humic acid and hazardous heavy metals by UV/TiO2 was higher than that of UV illumination alone or TiO2 alone. The removal efficiency for humic acid and Cr(VI) at acid or neutral pH values was higher than that at basic pH values. However, the removal efficiency for Cu(II) at acid pH values was smaller compared with that at neutral or basic pH values. The reaction rate (k) of humic acid and hazardous heavy metals in the TiO2 concentration range of 0.1-0.3 g l(-1) increased with increasing TiO2 dosage. However, amounts higher than a TiO2 dosage of 0.3 g l(-1) reduced the removal efficiency for humic acid and hazardous heavy metals because of the shielding effect on the UV light penetration in the aqueous solution caused by the presence of excessive amounts of TiO2. The addition of oxidants to the UV/TiO2 system showed an increase in degradation efficiency for the treatment of humic acid and hazardous heavy metals. The optimal concentration of oxidants was: H2O2 50 mg l(-1), O3 20 g m(-3) and K2S2O8 50 mg l(-1), respectively. The degradation efficiency of UV/TiO2/oxidant systems for the removal of humic acid and hazardous heavy metals was much greater when H2O2 was used as the oxidant.

  7. Degradation of pesticides chlorpyrifos, cypermethrin and chlorothalonil in aqueous solution by TiO2 photocatalysis.

    Affam, Augustine Chioma; Chaudhuri, Malay


    Degradation of pesticides chlorpyrifos, cypermethrin and chlorothalonil in aqueous solution by TiO2 photocatalysis under UVA (365 nm) irradiation was examined. Enhancement of degradation and improvement in biodegradability index (BOD5/COD ratio) by H2O2 addition were also evaluated. UVA irradiation per se produced insignificant degradation of the pesticides. In UV/TiO2 photocatalysis (TiO2 1.5 g L(-1), pH 6 and 300 min irradiation), COD and TOC removal were 25.95 and 8.45%, respectively. In UV/TiO2/H2O2 photocatalysis (TiO2 1.5 g L(-1), H2O2 100 mg L(-1), pH 6 and 300 min irradiation), COD and TOC removal were 53.62 and 21.54%, respectively and biodegradability index improved to 0.26. Ammonia-nitrogen (NH3-N) decreased from 22 to 7.8 mg L(-1) and nitrate-nitrogen (NO3(-)-N) increased from 0.7 to 13.8 mg L(-1) in 300 min, indicating mineralization. Photocatalytic degradation followed pseudo-first order kinetics with rate constant (k) of 0.0025 and 0.0008 min(-1) for COD and TOC removal, respectively. FTIR spectra indicated degradation of the organic bonds of the pesticides. UV/TiO2/H2O2 photocatalysis is effective in degradation of pesticides chlorpyrifos, cypermethrin and chlorothalonil in aqueous solution. UV/TiO2/H2O2 photocatalysis may be applied as pretreatment of a chlorpyrifos, cypermethrin and chlorothalonil pesticide wastewater at pH 6, for biological treatment.

  8. Effect of ZrO2 Doping on the Microwave Dielectric Properties of Ba(Mg1/3Nb2/3)O3 Ceramics

    Peng, Sen; Luo, Gaofeng; Wu, Mengqiang; Yu, Shengquan; Xu, Jianming; Huang, Tongcheng; Zhou, Jianhua


    The microwave dielectric properties of Ba(Mg1/3Nb2/3)O3 ceramics with x ( x = 0-10) wt.% ZrO2 (BMZN) were investigated by the solid-state reaction technique. X-ray diffraction (XRD) analysis suggested that there were two phases: the main crystalline phase Ba(Mg1/3Nb2/3)O3(BMN) and a secondary phase Ba5Nb4O15. Meanwhile, the Zr ions entered the B site of BMN and disturbed the 1:2 ordering. Scanning electron microscopy (SEM) analysis demonstrated that Zr4+ could promote the grain growth obviously. The addition of Zr4+ had a huge and positive influence on the Q × f value, for example, the sample with x = 8 had the highest Q × f value of 106,410 GHz. The BMZN ceramics with x = 8 sintered at 1400°C for 5 h had excellent microwave dielectric properties: ɛ r = 32.9, Q × f = 106,410 GHz ( f = 8 GHz) and τf = +0.7 ppm/°C.

  9. Fast reactor irradiation effects on fracture toughness of Si3N4 in comparison with MgAl2O4 and yttria stabilized ZrO2

    Tada, K.; Watanabe, M.; Tachi, Y.; Kurishita, H.; Nagata, S.; Shikama, T.


    Fracture toughness of silicon nitride (Si3N4), magnesia-alumina spinel (MgAl2O4) and yttria stabilized zirconia (8 mol%Y2O3-ZrO2) was evaluated by the Vickers-indentation technique after the fast reactor irradiation up to 55 dpa (displacement per atom) at about 700 °C in the Joyo. The change of the fracture toughness by the irradiation was correlated with nanostructural evolution by the irradiation, which was examined by transmission electron microscopy. The observed degradation of fracture toughness in Si3N4 is thought to be due to the relatively high density of small-sized of the irradiation induced defects, which should be resulted from a large amount of transmutation gases of hydrogen and helium. Observed improvement of fracture toughness in MgAl2O4 was due to the blocking of crack propagation by the antiphase boundaries. The radiation effects affected the fracture toughness of yttria stabilized zirconia at 55 dpa, suggesting that the generated high density voids would affect the propagation of cracks.

  10. Synthesis and spectral properties of Nd-doped glass-ceramics in SiO2-CaO-MgO system prepared by sol-gel method

    Masoud Eslami; Zohreh Hamnabard; Ali Nemati


    SiO2-CaO-MgO glass and glass-ceramic powder doped with Nd3+ were synthesized with sol-gel method.Tetraethylorthosilicate (TEOS),Ca(NO3)2·4H2O,Mg(NO3)2·6H2O,Nd(NO3)3·6H2O,ethanol,distilled water,and HNO3 were used as starting materials.The synthesized powder's properties were examined with simultaneous thermal analysis (STA),X-ray diffraction (XRD),photoluminescence (PL) and scanning electron microscopy (SEM) analysis.The STA curves showed that the softening point and crystallization temperatures were shifted to higher temperatures with increasing dopant content.Regarding XRD pattems of glass samples,Nd was found to act as an intermediate oxide in glass matrix.The XRD patterns of glass-ceramic samples indicated that bredigite and akermanite crystallized in the glass matrix after heat treating at 900 ℃.The ()luorescence spectra showed that glass-ceramics emitted much stronger irradiation than glasses with the same dopant content.The SEM images illustrated uniform and homogeneous distribution of applied oxides in glass and glass-ceramic compositions.

  11. Microwave energy-assisted formation of bioactive CaO–MgO–SiO$_2$ ternary glass from bio-wastes



    Regeneration technique is extensively being sought after as a means of achieving bone repair without adverse immunological response. Silicate-based bioactive glasses containing Mg are gaining increasing attention for their biocompatibility. The current work has been focused on designing a facile and economic route using bio-wastes for synthesizing bioactive glasses in the CaO–MgO–SiO$_2$ system. Rice husk ash (RHA) obtained from burning ricehusk was used as silica source, while Ca was extracted from eggshells for preparing the glass through a modified sol–gel approach. The gel formed was irradiated in microwave before sintering at 950$^{\\circ}$C for 3 h. Thereafter, bioactivity test was conducted on the samples in simulated body fluid (SBF) at physiological conditions for a maximum of 14 days. Characterization of samples were performed before and after immersion in SBF to evaluate thecomposition, morphology and phases present in the glass using energy-dispersive X-ray analysis, scanning electron microscopy and X-ray diffraction. Apatite formation was confirmed using Fourier transform infrared spectroscopy.Results obtained showed the presence of diopside, wollastonite and pseudo-wollastonite as major bioactive phases. Hydroxyapatite formed on the material within 3 days in SBF, indicating good bioactivity.

  12. Effect of ZrO2 Doping on the Microwave Dielectric Properties of Ba(Mg1/3Nb2/3)O3 Ceramics

    Peng, Sen; Luo, Gaofeng; Wu, Mengqiang; Yu, Shengquan; Xu, Jianming; Huang, Tongcheng; Zhou, Jianhua


    The microwave dielectric properties of Ba(Mg1/3Nb2/3)O3 ceramics with x (x = 0-10) wt.% ZrO2 (BMZN) were investigated by the solid-state reaction technique. X-ray diffraction (XRD) analysis suggested that there were two phases: the main crystalline phase Ba(Mg1/3Nb2/3)O3(BMN) and a secondary phase Ba5Nb4O15. Meanwhile, the Zr ions entered the B site of BMN and disturbed the 1:2 ordering. Scanning electron microscopy (SEM) analysis demonstrated that Zr4+ could promote the grain growth obviously. The addition of Zr4+ had a huge and positive influence on the Q × f value, for example, the sample with x = 8 had the highest Q × f value of 106,410 GHz. The BMZN ceramics with x = 8 sintered at 1400°C for 5 h had excellent microwave dielectric properties: ɛ r = 32.9, Q × f = 106,410 GHz (f = 8 GHz) and τf = +0.7 ppm/°C.

  13. Thermodynamic simulation on mineralogical composition of CaO-SiO2-Al2O3-MgO quaternary slag system.

    Liu, Chao; Zhang, Yu-Zhu; Li, Jie; Li, Jun-Guo; Kang, Yue


    It is necessary to elucidate the crystallization thermodynamic of mineralogical phases during the cooling process of the molten BFS with different chemical composition, because the high-melting point mineral phase maybe crystallized during the fiber forming and thereafter cooling process. Thermodynamic calculation software FactSage6.4 and the hot remelting experiments were performed to explore the influence of basicity, Al2O3 content and MgO content on the crystallization of mineralogical components and their transformation. The results showed that the main mineralography of the CaO-SiO2-Al2O3-MgO quaternary slag system was melilite, and a certain amount of anorthite and calcium metasilicate. The crystallographic temperature of melilite is increased with the increasing of basicity, MgO and Al2O3 content, which has a significant impact on the utilization performance of the mineral wool prepared with the hot blast furnace slag directly. With the increasing of basicity, there was a tendency that crystallographic amount of melilite increased to the summit and then declined, while the amount of anorthite and calcium metasilicate decreased consistently. Finally, these two mineralogical components could be replaced by magnesium rhodonite and spinel with the increasing of basicity. When the basicity and MgO content were 1.0 and 9 %, the crystallographic mass ratio of melilite and anorthite increased, while that of calcium silicate declined, and replaced by spinel finally with the increasing of Al2O3 content. When the basicity and Al2O3 content were 1.0 and 13 %, the crystallographic mass ratio of melilite increased, while that of anorthite and calcium silicate declined, and replaced by pyroxene and spinel with the increasing of MgO content. To decline fiberization temperature of the melt BFS, the basicity, MgO and Al2O3 content should be decreased during the modification process of chemical composition, because the crystallization temperature of the primary crystalline

  14. Calculating models on surface tension of RE2O3-MgO-SiO2 (RE=La, Nd, Sm, Gd and Y) melts%RE2O3-MgO-SiO2(RE=La,Nd,Sm,Gd和Y)熔体表面张力的计算模型

    吴铖川; 成国光


    基于熔体组元离子半径和Butler方程,建立RE2O3−MgO−SiO2(RE=La,Nd,Sm,Gd和Y)熔体表面张力热力学计算模型。本模型利用纯组元的表面张力和摩尔体积以及熔体中各组元阳离子和阴离子半径可以获得E2O3−MgO−SiO2熔体表面张力随熔渣成分和温度的变化规律。计算1873 K La2O3−MgO−SiO2熔体等表面张力线并研究熔体成分对表面张力的影响。1873 K的纯组元La2O3,Gd2O3,Nd2O3和Y2O3的表面张力通过本模型计算分别为686、677、664和541 mN/m。除了Y2O3外,纯稀土氧化物的表面张力随其阳离子磁场强度增加而呈线性减小,而Y2O3的表面张力相对减小更多。表面张力的计算结果与文献数据一致,1873 K本模型平均偏差为1.05%。%A thermodynamic model was developed for determining the surface tension of RE2O3−MgO−SiO2 (RE=La, Nd, Sm, Gd and Y) melts considering the ionic radii of the components and Butler’s equation. The temperature and composition dependence of the surface tensions in molten RE2O3−MgO−SiO2 slag systems was reproduced by the present model using surface tensions and molar volumes of pure oxides, as well as the anionic and cationic radii of the melt components. The iso-surface tension lines of La2O3−MgO−SiO2 slag melt at 1873 K were calculated and the effects of slag composition on the surface tension were also investigated. The surface tensions of La2O3, Gd2O3, Nd2O3 and Y2O3 at 1873 K were evaluated as 686, 677, 664 and 541 mN/m, respectively. The surface tension of pure rare earth oxide melts linearly decreases with increasing cationic field strength, except for Y2O3 oxide, while Y2O3 has a much weaker surface tension. The evaluated results of the surface tension show good agreements with literature data, and the mean deviation of the present model is found to be 1.05% at 1873 K.

  15. Quantificação da segregação de MgO em pós nanométricos de SnO2 preparados por método químico Quantification of MgO surface segregation on SnO2 nanopowders prepared by chemical method

    D. Gouvêa


    Full Text Available Um dos maiores desafios na síntese de nanopartículas é a instabilidade da estrutura relativa ao aumento de energia advindo da grande área de superfície específica desta classe de materiais. O conhecimento dos mecanismos pelos quais a estabilidade pode ser alcançada é de fundamental importância para o controle de seu crescimento e para potenciais aplicações. Fenômenos de segregação superficial em sistemas bi-componentes envolvem diminuição de energia do sistema devido ao excesso de superfície - conhecido como fenômeno de tensoatividade. Apesar de muito bem conhecidos em tecnologias de emulsões e em fenômenos que envolvem molhabilidade, o uso destes conceitos para estabilização da superfície sólido-vapor e controle de nanopartículas é menos expressivo. Embora a segregação seja conhecida para vários sistemas de óxidos nanoparticulados, sua quantificação visando o controle é limitada pela dificuldade de obtenção de resultados confiáveis. Neste trabalho foi realizada a quantificação da segregação de MgO na superfície de nanopartículas de SnO2 através da análise química dos pós antes e após lavagem em meio ácido para lixiviação do MgO superficial. Foi demonstrado que a solubilidade do MgO no bulk do SnO2 é preferencial em concentrações inferiores a 5% em mol de MgO, existindo, no entanto, uma distribuição do MgO ao longo da superfície e do bulk, gerando um efeito tenso-ativo e restringindo o crescimento das partículas de SnO2. Para concentrações maiores que 5% em mol, a maior parte do MgO foi detectada na superfície das nanopartículas de SnO2, sendo o controle tenso-ativo mais expressivo. Apesar dos resultados serem restritos para o sistema SnO2-MgO, esta técnica pode ser extrapolada para o controle de quaisquer sistemas onde o elemento segregado é solúvel em condições específicas.Particle size stability is a fundamental requirement in the synthesis and application of nanoparticles

  16. Efeito da segregação e solubilização do MgO na morfologia de pós de ZrO2 durante a síntese pelo método Pechini Effect of MgO segregation and solubilization on the morphology of ZrO2 powders during synthesis by the Pechini's method

    P. J. B. Marcos


    Full Text Available Trabalhos realizados em vários sistemas de óxidos cerâmicos têm demonstrado que a segregação dos íons durante a síntese de materiais cerâmicos pelo método Pechini tem conseqüências muito importantes tanto para a morfologia dos pós como para a sinterização. Este trabalho tem como objetivo estabelecer a influência da segregação/solubilização do MgO na morfologia e na sinterização de pós à base de ZrO2. O estudo foi realizado em pós preparados por síntese química derivada do método Pechini a 500 °C por 15 h. Observa-se que para concentrações de MgO até o limite de solubilidade no ZrO2 ocorre o crescimento de partículas e uma diminuição da área de superfície específica por causa da solubilização e do aumento do coeficiente de difusão pela geração de vacâncias de oxigênio. Contudo, após o limite de solubilidade, ocorre um aumento gradual da área de superfície específica devido à segregação dos íons na superfície dos pós e à diminuição da energia de superfície. Concentrações de MgO até 60 % molar foram utilizadas e áreas de superfície específica tão elevadas quanto 120 m²/g foram obtidas, mas as fases cristalinas formadas foram exclusivamente da zircônia solução sólida sem a presença de fases cristalinas de MgO.Studies carried out in several ceramic oxide systems have shown that segregation of ions during synthesis of ceramic materials by the Pechini's method has important morphology consequences for the powder. The aim of this paper is to establish the influence of the MgO segregation/solubilization on the morphology of ZrO2 powders. The study was performed in powders prepared by chemical synthesis derived from the Pechini's method at 500 ºC for 15 h. It is observed that MgO concentrations up to the solubility limit promote ZrO2 particle coarsening and a reduction of specific surface area by increasing the diffusion coefficient. However, MgO amounts higher than the solubility

  17. Surface tension investigation and model forecasting of SiO2--Al2 O3--CaO--MgO quaternary mineral wool slag%SiO2--Al2 O3--CaO--MgO四元矿渣棉体系的表面张力测定与模型预报

    彭犇; 唐续龙; 勾立争; 胡一文; 郭敏; 张梅


    Surface tension is one of the major parameters for mineral wool production, and it may influence burdening and processing parameter selection. The surface tension of melts for mineral wool production using blast furnace slag as a major material was systematically investigated by experiment measurements and model forecasting. Firstly, a series of surface tension values of SiO2 (40%-- 60%)--Al2 O3 (5%--20%)--CaO(20%--30%)--MgO(5%) quaternary systems were measured, and they showed in the range of 350 to 500 mN·m-1 . Then in combination with data from reports in literature, an artificial neural network (ANN) model was constructed to calculate the surface tension of melts in an extension system of SiO2 (35%--60%)--Al2 O3 (5%--20%)--CaO(20%--45%)--MgO(0-- 10%). The average error of the developed model is 9. 32%, proving a higher accuracy for predicting the surface tension of those melts in the extension system.%表面张力是矿物棉生产的重要参数,直接影响到配料和工艺参数的选择.通过实验测量并建立模型预报系统研究了以高炉渣为主要原料制备矿物棉时熔体的表面张力.首先测量了SiO2(40%~60%)- Al2 O3(5%~20%)- CaO(20%~30%)-MgO(5%)四元系的表面张力,其值处于350~500 mN·m-1之间;然后结合文献报道的表面张力数据,利用人工神经网络技术建立了SiO2(35%~60%)-Al2 O3(5%~20%)-CaO(20%~45%)-MgO(0~10%)四元渣系的表面张力预报模型.该模型对成分范围内的表面张力预报平均误差为9.32%,预报精度较高,可以预报矿物棉熔体成分范围内的表面张力.

  18. Sintering behavior of mullite with addition of SiO2-MgO-Y2O3-SrCO3

    Lim, Chang-Bin; Yeo, Dong-Hun; Shin, Hyo-Soon


    As the size of semiconducting silicon (Si) wafers increases, that of the ceramic substrate, which is main part of a semiconductor probing system, has also increased. The increased number of layers due to high integrity of Si wafers and the narrow pattern linewidths for impedance matching require the use of Cu-Mo conducting paste, rather than conventional Mo paste, for low electrical resistivity. For co-firing of a Cu-Mo electrode with a ceramic substrate, a green ceramic substrate with a printed pattern must be sintered at a temperature below 1400 °C. To obtain a mullite composition that can be co-fired with a Cu-Mo electrode at a temperature below 1400 °C, we added 1.0 wt% of SiO2, 1.0 wt% of MgO, 1.5 wt% of Y2O3, and 7.0 wt% of SrCO3 to a commercial mullite composition, and we sintered the specimen with that composition at 1350 °C in a reducing atmosphere to obtain a density of 3.20 g/cm3. The sintered specimen's coefficient of thermal expansion at temperatures from room temperature to 200 °C was 4.53 ppm/°C, which is acceptable for a semiconductor probing system.

  19. Carbonate apatite formation on novel multiphase CaO-SiO2-P2O5-MgO glass-ceramics in TRIS-HCl buffer

    Lachezar Radev


    Full Text Available The main purpose of the presented article is the preparation of novel glass-ceramics in CaO-SiO2-P2O5-MgO system and evaluation of carbonate apatite formation after soaking in TRIS-HCl buffer solution for 14 days. The investigated samples were prepared via sol-gel method and structure of the obtained samples was studied using XRD, FTIR, SEM, XPS and ICP-AES. XRD of the thermally treated samples showed that the presence of some crystalline phases is depended on the gel composition. FTIR revealed the existence of all characteristic bands for the observed crystalline phases. SEM monitored the presence of particles with different morphology. After soaking in TRIS-HCl solution, FTIR confirmed that carbonate apatite was formed on the soaked surface. The obtained data are in a good agreement with XPS analysis. The change of ions concentrations in TRIS-HCl buffer solution after immersion of the prepared glass-ceramics was recorded by ICP-AES measurements.

  20. Direct Measuring Methods of Water Vapor Content and Air Velocity at High Temperature using ZrO2-MgO Gas Chemisorption Type Ceramic Body

    Nomura, Tomohiro; Nishimura, Nobuya; Shiba, Tooru; Hyodo, Tsutomu

    The control of humidity or air velocity as well as temperature is imperative for industrial process equipment such as air conditioners, dryers. At present, much about humidity sensors has been reported, and recently, ceramic sensors have been used with improved results. However, the effective operating temperature of these sensors for a direct measurement of the humidity is about 423 K at the highest. From the various ceramic sensors so far investigated, the authors selected composite ceramics ZrO2-MgO with porous structure and n-type semiconductor for humidity sensing at high temperature. This is because, when the working temperature of the ceramic sensor is between 673 and 973K, the sensor detects the presence of water vapor and gas velocity by the variations in the electronic condition caused by the reversible of the water vapor. From the test, the sensor that use a single sensing ceramic element can detect directly both the water vapor content in a mixed gas of air and superheated vapor in the temperature range 373-773 K and the air velocity(O.5-4m/s) in the range 373-573K.

  1. Phase diagrams, thermodynamic properties and sound velocities derived from a multiple Einstein method using vibrational densities of states: an application to MgO-SiO2

    Jacobs, Michael H. G.; Schmid-Fetzer, Rainer; van den Berg, Arie P.


    In a previous paper, we showed a technique that simplifies Kieffer's lattice vibrational method by representing the vibrational density of states with multiple Einstein frequencies. Here, we show that this technique can be applied to construct a thermodynamic database that accurately represents thermodynamic properties and phase diagrams for substances in the system MgO-SiO2. We extended our technique to derive shear moduli of the relevant phases in this system in pressure-temperature space. For the construction of the database, we used recently measured calorimetric and volumetric data. We show that incorporating vibrational densities of states predicted from ab initio methods into our models enables discrimination between different experimental data sets for heat capacity. We show a general technique to optimize the number of Einstein frequencies in the VDoS, such that thermodynamic properties are affected insignificantly. This technique allows constructing clones of databases from which we demonstrate that the VDoS has a significant effect on heat capacity and entropy, and an insignificant effect on volume properties.

  2. Kinetics of Reduction of CaO-FeO x -MgO-PbO-SiO2 Slags by CO-CO2 Gas Mixtures

    Jahanshahi, Sharif; Wright, Steven


    Kinetics of the reaction of lead slags (PbO-CaO-SiO2-FeO x -MgO) with CO-CO2 gas mixtures was studied by monitoring the changes in the slag composition when a stream of CO-CO2 gas mixture was blown on the surface of thin layers of slags (3 to 10 mm) at temperatures in the range of 1453 K to 1593 K (1180 °C to 1320 °C). These measurements were carried out under conditions where mass transfer in the gas phase was not the rate-limiting step and the reduction rates were insensitive to factors affecting mass transfer in the slag phase. The results show simultaneous reduction of PbO and Fe2O3 in the slag. The measured specific rate of oxygen removal from the melts varied from about 1 × 10-6 to 4 × 10-5 mol O cm-2 s-1 and was strongly dependent on the slag chemistry and its oxidation state, partial pressure of CO in the reaction gas mixture, and temperature. The deduced apparent first-order rate constant increased with increasing iron oxide content, oxidation state of the slag, and temperature. The results indicate that under the employed experimental conditions, the rate of formation of CO2 at the gas-slag interface is likely to be the rate-limiting step.

  3. Interfacial Tension in the CaO-Al2O3-SiO2-(MgO) Liquid Slag-Solid Oxide Systems

    Abdeyazdan, Hamed; Monaghan, Brian J.; Longbottom, Raymond J.; Rhamdhani, M. Akbar; Dogan, Neslihan; Chapman, Michael W.


    Interfacial phenomenon is critical in metal processing and refining. While it is known to be important, there are little data available for key oxide systems in the literature. In this study, the interfacial tension ( σ LS) of liquid slag on solid oxides (alumina, spinel, and calcium aluminate), for a range of slags in the CaO-Al2O3-SiO2-(MgO) system at 1773 K (1500 °C), has been evaluated. The results show that basic ladle-type slags exhibit lower σ LS with oxide phases examined compared to that of acid tundish-type slags. Also, within the slag types (acid and base), σ LS was observed to decrease with increasing slag basicity. A correlation between σ LS and slag structure was observed, i.e., σ LS was found to decrease linearly with increasing of slag optical basicity (Λ) and decrease logarithmically with decreasing of slag viscosity from acid to base slags. This indicated a higher σ LS as the ions in the slag become larger and more complex. Through a work of adhesion ( W) analysis, it was shown that basic ladle slags with lower σ LS result in a greater W, i.e., form a stronger bond with the solid oxide phases examined. This indicates that all other factors being equal, the efficiency of inclusion removal from steel of inclusions of similar phase to these solid oxides would be greater.

  4. Melting features and viscosity of SiO2-CaO-MgO-Al2O3-FeO nickel slag in laterite metallurgy

    Pan C.


    Full Text Available Physic-chemical properties of slag at high temperature were very important for the production of ferronickel alloy by pyrometallurgical process. It determines the operation efficiency, metal recovery ratio, energy consumption and the distribution of elements (like S and P between the slag and metal. In the present work, the effect of slag basicity on melting features and viscosity of the slag was investigated. The basicity of the SiO2-CaO-MgO-Al2O3-FeO quinary slag system varied from 0.76 to 0.99. The results showed that: 1 all the slag samples began to soften at the same temperature; 2 the softening temperature, melting temperature and flowing temperature decreased with the increase of basicity from 0.76 to 0.92, after that, the temperatures would increase sharply. 3 the inflection point temperature of viscosity-temperature curve became larger and larger with the increase of basicity within 0.76 ~ 0.99.

  5. Study of the productivity of MWCNT over Fe and Fe–Co catalysts supported on SiO2, Al2O3 and MgO

    S.A. Shokry


    Full Text Available In the present study, multi-walled carbon nanotubes (MWCNT were prepared in good quality and quantity, MWCNT were produced using the catalytic chemical vapor deposition (CCVD technique and the carbon source was acetylene. Different catalysts were synthesized based on iron and a mixture of iron and cobalt metal supported on SiO2, Al2O3 or MgO. The effect of parameters such as iron concentration, support type, bimetallic catalyst and the method of catalyst preparation has been investigated in the production of MWCNT. The quality of as-made nanotubes was investigated by the high-resolution transmission electron microscopy (HRTEM and thermogravimetric analysis (TGA. The best yield of MWCNT was 30 times of the amount of the used catalyst. The high yield of MWCNT was gained by 40 wt.% Fe on alumina support which was prepared by the sol–gel method. TEM analysis was done for the carbon deposit, which revealed that the walls of the MWCNT were graphitized, with regular inner channel and uniform diameter. It reflected a reasonable degree of purity. The TGA showed that MWCNT was decomposed at 635 °C by a small rate indicating a high thermal stability and well crystalline formation of the produced MWCNT.


    吴铖川; 成国光; 马琦琦



  7. Ce2O3掺杂SrO-MgO-SiO2微晶玻璃结构与发光性能研究%Preparation and Luminescent Properties of Ce3 + Doped SrO-MgO-SiO2 Glass Ceramics

    何峰; 吴成龙; 刘庭伟; 谢峻林; 张文涛; 刘佳


    制备了一种新型的以黄长石为主晶相的Ce离子激活发光微晶玻璃,采用X射线衍射仪和荧光光谱仪研究了热处理温度对微晶玻璃的结构及发光性能的影响.结果表明:Ce3+掺杂SrO-MgO-SiO2微晶玻璃,激发光谱激发峰位在475 nm处,发射光谱发射峰位在715 nm处,Ce3+离子的发光属于5d-4f跃迁.热处理温度的升高不会改变Ce3+掺杂SrO-MgO-SiO2微晶玻璃荧光光谱的峰位,随着热处理温度的升高,荧光光谱强度呈现增强的趋势.掺杂Ce3+离子浓度的增加能增强荧光光谱的强度.

  8. Influence of ZrO2-Y2O3 and ZrO2-CaO coatings on microstructural and mechanical properties on Mg-1,3Ca- 5,5Zr biodegradable alloy

    Istrate, B.; Munteanu, C.; Matei, MN; Oprisan, B.; Chicet, D.; Earar, K.


    Zirconia (ZrO2) as a ceramic biomaterial facilitates the osteoconductivity in new bone formation around implant. In order to improve the degradation and the surface properties, it is necessary to apply a surface film to satisfy multiple clinical requirements such as mechanical strength, biocompatibility, and degradation rate. Therefore, surface changing to form a tenacious, biocompatible and corrosion resistant modified layer has become a necessary study in biodegradable materials. The aim of the study is to observe the morphology, structural and scratch analysis for some coatings of ZrO2-CaO and ZrO2-Y2O3 having similar thickness deposited with an atmospheric plasma spraying facility, Sulzer Metco 9MCE, using scanning electron microscopy and X-Ray diffraction. Some mechanical aspects were highlighted during the scratch test. Comparative scratch tests were carried out to study the bonding properties between the coatings and the substrates.

  9. Effect of CeO2 and CaO Promoters on Ignition Performance for Partial Oxidation of Methane over Ni/MgO-Al2O3 Catalyst

    Yejun Qiu; Jixiang Chen; Jiyan Zhang


    The effect of CeO2 and CaO promoters on the ignition performance over Ni/MgO-Al2O3 catalyst for the partial oxidation of methane (POM) to synthesis gas was investigated. It was found that the POM reaction could not be ignited over 1wt%Ni/MgO-Al2O3 catalyst without the promoters in the temperature range from 773 K to 1073 K. CeO2 and CaO promoters enhanced the ignition performance and the POM reactivity of 1wt%Ni/MgO-Al2O3 catalyst remarkably. Moreover, the improving effect became greater with the increase of the promoter content under the investigated reactionconditions. The modification effects of CeO2 and CaO promoters were closely related to the concentration and reducibility of the surface and bulk oxygen species.

  10. Evaluation of Existing Viscosity Data and Models and Developments of New Viscosity Model for Fully Liquid Slag in the SiO2-Al2O3-CaO-MgO System

    Han, Chen; Chen, Mao; Zhang, Weidong; Zhao, Zhixing; Evans, Tim; Zhao, Baojun


    Metallurgical properties of slag are determined to a great extent by its viscosity. High-temperature viscosity measurements are time-consuming and expensive. It is necessary to develop an accurate viscosity model for blast furnace slag in the SiO2-Al2O3-CaO-MgO system using reliable viscosity data. This paper describes a systemic evaluation procedure to determine the viscosity data to be used for model development. 1780 viscosity data from 10 to 65 wt pct SiO2, 3.5 to 40 wt pct Al2O3, 2 to 60 wt pct CaO, and 2 to 38 wt pct MgO in the SiO2-Al2O3-CaO-MgO system have been accepted for model evaluation after critical reviews. The existing 14 viscosity models in SiO2-Al2O3-CaO-MgO system is also reviewed and evaluated. Based on the structure of alumina-silicate slag and evaluated viscosity data, a new viscosity model has been proposed for the system SiO2-Al2O3-CaO-MgO. A new term "probability," based on the basic oxide and electronegativity, is introduced to calculate the integral activation energy of slag. The model has been evaluated and compared with existing viscosity models in three different composition ranges in SiO2-Al2O3-CaO-MgO system for different applications. The new model reports an outstanding agreement between predictions and experimental data. The industrial implications of the new model have also been discussed in ironmaking and steelmaking processes.

  11. Optical and scintillation properties of Ce:(Gd8AE2)(SiO4)6O2 (AE = Mg, Ca, Sr and Ba) crystals

    Igashira, Takuya; Mori, Masaki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki


    1% Ce-doped and non-doped (Gd8AE2)(SiO4)6O2 (AE = Mg, Ca, Sr and Ba) (denoted as GMS, GCS, GSrS and GBS, respectively) single crystals were grown by the Floating Zone (FZ) method to evaluate their optical and scintillation properties. The Ce:GCS and Ce:GSrS samples exhibited scintillation and photoluminescence (PL) around 400 nm due to the 5d-4f transitions of Ce3+. On the other hand, Ce:GMS and Ce:GBS showed much weaker emissions in the wavelength range of 500-650 nm, in which the origin was associated with the host matrices. The PL decay curves were approximated by a double exponential decay function for all the Ce-doped samples. The decay times ranged around 10-30 and 40-90 ns, and faster components coincided with those of the non-doped samples. The scintillation decay curves of Ce-doped samples, on the other hand, were approximated by single exponential functions with slower decay constants than those of PL decay. These constants were very similar to those of non-doped samples. In the X-ray induced afterglow measurements, Ce:GCS exhibited the lowest afterglow level. The pulse height spectrum of these samples showed a full-energy peak under 241Am 5.5 MeV α-ray irradiation. Among these samples, Ce:GSrS exhibited the highest light yield which was around 600 ph/5.5 MeV-α.

  12. Synthesis of nanocrystalline TiB$_2$ powder from TiO$_2$, B$_2$O$_3$ and Mg reactants through microwave-assisted self-propagating high-temperature synthesis method



    In this research work, microwave-assisted self-propagating high-temperature synthesis (SHS) process was employed for the fabrication of titanium diboride (TiB$_2$) compound from TiO$_2$–B$_2$O$_3$–Mg mixtures. Thermodynamicevaluations of this system and its relevant subsystems revealed that TiB$_2$–MgO composite powder can be easily produced by a SHS reaction. However, experimental results of a TiO$_2$ : B$_2$O$_3$ : 5 Mg mixture heated in a domestic oven showed the formation of some intermediate compounds such as Mg3B2O6, presumably due to some degree of Mg loss. The optimum amount of Mg in TiO$_2$ : B$_2$O$_3$ : xMg mixtures, yielding the highest amount of TiB$_2$ phase, was found to be around 7 mol, i.e., 40 mol% more than the stoichiometric amount. Experimental results revealed thata pure TiB$_2$ compound could be obtained by leaching the unwanted by-products in an HCl acid solution. Scanning electron microscopic observations and Scherrer calculations showed that the produced TiB$_2$ contains sub-micron (150–200 nm) particles, where each particle consists of a number of nanosized (32 nm) crystallites.

  13. 二甲醚催化氧化制下游化学品(Ⅱ)V/Mn改性的SnO2/MgO催化氧化制碳氢化合物%Catalytic oxidation of dimethyl ether to downstream products (Ⅱ) Over V or Mn modified SnO2/MgO catalysts

    吕逵弟; 余林; 向杰; 孙明; 郝志峰; 余倩; 许洁瑜; 王雪涛


    考察了SnO2/MgO催化剂和添加助剂V、Mn对二甲醚(DME)催化氧化制取乙二醇二甲醚(DMET)和其他碳氢化合物的催化性能.结果表明,锡镁催化剂对DME在275~325 ℃有良好的催化活性;添加VOx能较大提高DME转化率和产物DMET的选择性,DME转化率可达23%,DMET选择性可达44%,在300℃收率达9%以上.

  14. 复合精炼球团中SiO2、CaO、MgO等7组分的测定%Determination of the SiO2, CaO, MgO, TAl, P, MAl and Al2O3 in Composite Refining Pellet

    王俊秀; 傅士刚; 张小燕; 魏新晖; 李龙霞


      试样用混合熔剂熔融,稀盐酸浸取,定容,移取部分试液,通过控制各元素的酸度,分别用光度法测定SiO2和P;EG-TA滴定法测定CaO,EDTA滴定法测定MgO;强碱沉淀分离氟盐置换、EDTA滴定法测定TAl.另称取1份试样用三氯化铁溶解,加入过量的氢氧化钠,滤液在pH值4.5的乙酸—乙酸铵缓冲介质中,加入过量的EDTA标准溶液,在煮沸条件下与MAl络合后,以PAN为指示剂,用铜标准溶液返滴定过量的EDTA;加氟化物取代,铜标准溶液二次返滴定,计算MAl量,再换算为 Al2O3量.实验确定三氯化铁浓度为8%、用量50 mL 及用振荡器或摇动的最佳时间为60 min.该方法测定 SiO2、CaO、MgO、P、Al2O3及MAl的相对偏差分别小于0.718%、2.819%、1.171%、7.143%、0.178%和1.013%,完全满足快速分析的需要.%  The sample melted with mixed flux, leaching with dilute hydrochloric acid, constant volume, removing a part of solution, through the control of the acidity of each element, respectively the SiO2 and P were determined by photometric method; the CaO was determined by EGTA titration method and the MgO was determined by EDTA titration method; the TAl was determined by alkali precipitation separation of fluoride salt replacement and EDTA titration method. The other a sample with ferric chloride dissolving, excess sodium hydroxide was added. The filtrate in acetic acid-ammonium acetate buffer solution at pH 4.5 was added excessive EDTA standard solution and made complexation with the MAl in the boiling condition. Making PAN as indicator, using copper standard solution back titration of excess EDTA, adding fluoride to replace copper standard solution, two times back titration, the mass fraction of the MAl was calculated and the mass fraction of the Al2O3 was converted. The concentration and dosage of the ferric chloride determined by test are 8% and 50 mL and the best shake time or by an oscillator is 60 min. The RSDs of SiO2, CaO, Mg

  15. Co-hydrothermal synthesis of LiMn23/24Mg1/24PO4·LiAlO2/C nano-hybrid cathode material with enhanced electrochemical performance for lithium-ion batteries

    Zhang, Jun; Luo, Shaohua; Chang, Longjiao; Hao, Aimin; Wang, Zhiyuan; Liu, Yanguo; Xu, Qian; Wang, Qing; Zhang, Yahui


    LiMn23/24Mg1/24PO4·LiAlO2/C is synthesized by a co-hydrothermal method in water/PEG system using Li2CO3, AAO and Mn1-xMgxPO4 as raw material. The electronic structure and micromorphology of multi-component compound LiMn1-xMgxPO4/C (x = 0, 1/24, 1/12, 1/6) and nano-hybrid LiMn23/24Mg1/24PO4·LiAlO2/C cathode materials are studied by first-principles calculation and experimental research including XRD, SEM, TEM. The calculated band gap of LiMn23/24Mg1/24PO4/C is 2.296 eV, which is lower than other percentages Mg2+ doping samples. Electrochemical tests exhibit LiMn23/24Mg1/24PO4/C has better cycling performance and rate capability than other contents Mg2+ doping samples with the discharge capacity of 143.5 mAh/g, 141.5 mAh/g, 139.2 mAh/g and 136.3 mAh/g at 0.05C, 0.1C, 0.5C and 1C in order. After compositing and preparation of LiMn23/24Mg1/24PO4·LiAlO2/C composite material by co-hydrothermal route, the initial discharge capacity reaches up to 151.8 mAh/g, which suggests that co-modified with Mg2+ doping and LiAlO2 compositing material can improve the electronic conductivity of LiMnPO4/C by facilitating the lithium ion diffusion rate in the interior of the materials.

  16. Thermodynamic Assessment of MnO and FeO Activities in FeO–MnO–MgO–P2O5–SiO2(–CaO) Molten Slag

    Kim, Sun-Joong; Takekawa, Jun; Shibata, Hiroyuki; Kitamura, Shin-ya; Yamaguchi, Katsunori; Kang, Youn-Bae


    The activity coefficients of MnO and FeO in an FeO–MnO–MgO–P2O5–SiO2(–CaO) slag system were measured on the basis of the equilibrium between Ag and molten slag at 1673 K under a controlled atmosphere...

  17. Fabrication of a dye-sensitized solar cell containing a Mg-doped TiO2 electrode and a Br3(-)/Br- redox mediator with a high open-circuit photovoltage of 1.21 V.

    Kakiage, Kenji; Tokutome, Toru; Iwamoto, Shinji; Kyomen, Toru; Hanaya, Minoru


    A dye-sensitized solar cell (DSSC) fabricated by using a Mg(2+)-doped anatase-TiO(2) electrode with an alkoxysilyl dye and a Br(3)(-)/Br(-) electrolyte solution exhibited successfully a remarkably high open-circuit photovoltage over 1.2 V, demonstrating a new possibility of DSSCs as practical photovoltaic devices.

  18. Low temperature biosynthesis of Li2O–MgO–P2O5–TiO2 nanocrystalline glass with mesoporous structure exhibiting fast lithium ion conduction

    Du, X.Y.; He, W.; Zhang, X.D.


    We demonstrate a biomimetic synthesis methodology that allows us to create Li2O–MgO–P2O5–TiO2 nanocrystalline glass with mesoporous structure at lower temperature. We design a ‘nanocrystal-glass’ configuration to build a nanoarchitecture by means of yeast cell templates self-assembly followed by ...

  19. Dissolution Behavior of Alumina-Based Inclusions in CaF2-Al2O3-CaO-MgO-SiO2 Slag Used for the Electroslag Metallurgy Process

    Yanwu Dong


    Full Text Available Removal of non-metallic inclusions to CaF2-based slag is one of the most important functions of electroslag remelting. In this work, the dissolution behavior for alumina-based inclusions in CaF2-Al2O3-CaO-MgO-SiO2 slag has been investigated. Results indicate that the diffusion or permeability capacity of slag components into alumina particles is F−, Ca2+, Si4+, Mg2+, from strongest to weakest, for CaF2-Al2O3-CaO-MgO-SiO2 slag. Alumina inclusions react with F− in liquid slag at first and then react with CaO to form xCaO-yAl2O3 system. Subsequently, MgO substitutes for CaO to form a MgO-Al2O3 system layer surrounding the other product and reactant, and then enters the liquid slag. CaF2 can improve the dissolution capacity of slag to alumina inclusions. A complex region was formed between alumina-based particles and the slag, with different areas dominated by CaF2, CaO-Al2O3, CaO-SiO2 and MgO-Al2O3. The dissolution process of alumina particles in slag is different from the formation of compound inclusions originated from the Al-O deoxidization reaction.

  20. 复合添加Al和TiO2对低碳镁碳砖基质物相组成及性能的影响%Effect of additives Al and TiO2 on the matrix phase composition and properties of low carbon MgO-C bricks

    夏忠锋; 王周福; 王玺堂; 刘浩


    Low carbon MgO-C bricks were prepared with fused magnesia and fine flake graphite as the raw materials, thermosetting phenol-formaldehyde resin as the binder, added with Al and TiO2. The effect of additives Al and TiO2 on the matrix phase composition and properties of low carbon MgO-C bricks were investigated. The matrix phase composition' was analyzed by XRD, and the microstruc-ture was characterized by SEM and EDS. The results show that the formation of MgAl2O4 and TiN or Ti(C,N) from the reaction of additives with the matrix can significantly improve the oxidation resistance and cold crush strength of low carbon MgO-C bricks. In addition, the addition of Al and TiO2 can avoid the formation of Al4C3 and prevent the bricks from hydration.%以电熔镁砂、超细鳞片石墨为主要原料,以热固性酚醛树脂为结合剂,添加Al和TiO2制备低碳镁碳砖,研究复合引入Al粉和TiO2对低碳镁碳砖基质物相组成及性能的影响.结果表明,埋炭热处理后,添加剂与基质反应生成新相MgAl2O4和TiN或Ti(C,N),使低碳镁碳砖的抗氧化性能明显提高,材料的强度显著增加;此外,添加剂的复合引入有利于改善单独引入Al粉时镁碳砖埋炭处理后易水化的问题.

  1. A Comparison Study of New TiO2/PEG Immobilized Techniques Under Normal and Visible Light Irradiations

    Zaharudin R.; Ain S. K.; Bakar F.; Azami M. S.; Nawawi W. I.


    Novel photocatalysts of TiO2 and TiO2/PEG were immobilized using new technique which is double sided adhesive tape (DSAT) as a thin layer binder onto glass plate. The photocatalytic activity study of immobilized/TiO2 and immobilized/TiO2/PEG were carried out by irradiating of 36 mg L-1 MB dye in the presence of normal and visible light with rate of decolourization was estimated from aliquot concentration spectrophotometrically. The high photocatalytic activity from immobilized/TiO2/PEG was ob...

  2. [Experimental Research of Hg (II) Removal from Aqueous Solutions of HgCl2 with Nano-TiO2].

    Zhou, Xiong; Zhang, Jin-yang; Wang, Ding-yong; Qin, Cai-qing; Xu, Feng; Luo Cheng-zhong; Yang, Xi


    Mercury removal from aqueous solutions of HgCl2 was studied by indoor simulation experiments, and the effects of three different diameter of particles of Nano-TiO2 ( Nano-Titanium Dioxide) at different dosage, pH, adsorption time and the initial concentration of Hg2+ on the mercury adsorption from simulated wastewater were investigated. The single factor experiments showed that the optimal conditions were: 7.5 g x L(-1) of 5 nm TiO2 or 2.0 g x L(-1) of 100 nm TiO2, pH 8.0, initial concentration of Hg2+ 15 x mg x L(-1) adsorption time 5 min, and under these conditions the adsorption rates reached 99.5% and 99.3%, relatively. When the content of 25 nm TiO2 was 10 g x L(-1), and the other conditions were pH 8.0, initial concentration of Hg2+ 15 mg x L(-1), adsorption time 60 min, the adsorption rate was 62.8%. The Hg(II) removal effects of the TiO2 particles with different diameters followed the order of 100 nm TiO2 > 5 nm TiO2 > 25 nm TiO2. Component adsorption results showed that the 5 nm TiO2 component adsorption effect was superior to its single adsorption effect, while there was little difference between 100 nm TiO2 component adsorption effect and its single adsorption effect. The results of orthogonal experiments indicated that the influencing factors of the adsorption rate followed the order of pH > the initial concentration of Hg2+ > time > dosage. The optimal experiment scheme was: pH 8.0, a dosage of 100 nm Nano-TiO2 of 2.0 g x L(-1) an initial Hg2+ concentration of 25 mg x L(-1) and adsorption time of 10 min. Under the experimental conditions, the maximum adsorption rate reached 99.9%, at the same time, the equilibrium concentration of Hg(II) was 0.033 mg x L(-1) adsorptive capacity was 26.95 mg x g(-1). The adsorption isotherm was in line with the Langmuir isotherm equation, indicating that the Hg(II) uptake by 100 nm Nano-TiO2 was typical monolayer adsorption.

  3. Structure and Fluorescence Quenching of Li2O-MgO-Al2O3-SiO2 Glasses Doped with Trivalent Cerium%Ce3+掺杂Li2O-MgO-Al2O3-SiO2玻璃的结构与荧光猝灭现象

    陈艳平; 罗德礼; 徐钦英; 杨锁龙; 唐涛; 王小英


    20Li2O-5MgO-20Al2O3-55SiO2glass doped with different concentrations ofCe3+ions was synthesized by using melt-quenching method. The glass density as a function of Ce3+ ions doping concentration was tested by Ar-chimedes’ method. The structural characteristics of Ce3+-doped 20Li2O-5MgO-20Al2O3-55SiO2were detected by using X-rays diffraction (XRD), high resolution transmission electron microscope (HRTEM) techniques. The photolumines-cence excitation (PLE) and emission (PL) spectra were recorded in a spectrofluorimeter by photon counting techniques. Results showed that 5d energy level of Ce3+ ion was splitted to five components under the strong crystal filed sur-rounding Ce3+ ions. The higher the doping concentration of Ce3+ ions, the higher the degree of non-crystalline con-figuration of lithium magnesium aluminosilicate glass was. With the increase of the degree of non-crystalline configu-ration, the splitting width of 5d energy level increased, resulting in the redshift of excitation and emission spectra ap-parently. The PL emission intensity first increased, and then decreased with the increase of Ce3+ ions doping concen-tration. The concentration quenching processes were found to be the key reason for the reduction of the PL emission efficiency.%采用熔融淬冷法制备了不同浓度 Ce3+离子掺杂的20Li2O-5MgO-20Al2O3-55SiO2玻璃闪烁材料。采用 X 射线衍射(XRD)、高分辨透射电镜(HRTEM)技术、密度检测等方法研究了玻璃的微观结构随 Ce3+离子掺杂浓度的变化规律,采用荧光分光技术检测了玻璃的紫外光致激发光谱(PLE)、发射光谱(PE)。研究结果表明:在不对称的晶体场作用下, Ce3+离子5d能级被劈裂为5个组分;随着玻璃基质内Ce3+离子掺杂浓度增大,玻璃的非晶化程度加深;5d能级的劈裂宽度随之增大,由此导致激发带向低能量端展宽、发射光谱明显红移; Ce3+离子的荧光发射强度随Ce3+离子掺杂浓度先升高、

  4. Technology in L1

    Elf, Nikolaj Frydensbjerg; Hanghøj, Thorkild; Skaar, Håvard


    In recent decades, several Scandinavian research projects have had an explicit focus on how technology intervenes in L1 (or so-called Mother Tongue Education) practices in Swedish, Norwegian and Danish educational contexts, and how this may impact on understanding of the subject. There is currently......-of-school literacy practices. A final find-ing is the emphasis on teacher uncertainty regarding how and why to integrate technology within exist-ing paradigms of the subject. This calls for further research on how technology may be justified in L1 practice, including various forms of teacher education....... no systematic overview of the documented possibilities and challenges related to the use of technology in L1. At the same time, there is terminological confusion in use of ‘technology’ and related concepts in L1. Finally, there is a general lack of critical reflection on the relation between technological...

  5. Technology in L1

    Elf, Nikolaj Frydensbjerg; Hanghøj, Thorkild; Skaar, Håvard


    of empirical studies, what characterizes the research field?; and 3) for discussion, which broader implications does the review suggest for a rethinking of L1 in terms of practice and research? Introducing the notion of educational boundary objects, a theoretical framework is developed, which suggests four...... metaphors for understanding technology within L1: as a tool, as media, as socialization, and as literacy practices. These are found useful for analyzing and comparing both theoretical perspectives and empirical research on L1. A key finding of the study is that, although the included research......In recent decades, several Scandinavian research projects have had an explicit focus on how technology intervenes in L1 (or so-called Mother Tongue Education) practices in Swedish, Norwegian and Danish educational contexts, and how this may impact on understanding of the subject. There is currently...

  6. CaO-SiO2-MgO-CaF2熔渣对氧化锆的侵蚀行为%Corrosion behaviors of zirconia refractory by CaO-SiO2-MgO-CaF2 slag



    本文研究了在1 873K的温度下,随着CaF2含量的变化CaO-SiO2-MgO-CaF2系熔渣对氧化锆(部分氧化镁-稳定氧化锆)耐火材料的侵蚀行为.通过测试高温下此熔渣的熔点和汽化行为表征其侵蚀机理.采用HM(加热显微镜)进行侵蚀实验和熔点测定,并利用TG-DSC(微量差热分析和示差扫描量热法)研究其汽化现象,然后使用扫描电子显微镜能谱仪和电子探针分析熔渣对氧化锆的侵蚀界面.结果表明随着CaF2的增加,在熔渣和氧化锆耐火材料表面形成了3个不同的层,并且发现随着能促进中间氧化物分解的CaF2,的增加,氧化锆耐火材料的侵蚀行为不断地加重.另一方面随着CaF2含量的增加,CaO-SiO2-MgO-CaF2熔渣的熔点并没有持续降低.同时,在HM试验中发现CaF2含量过高会导致大量氟化物气体出现,这将会引起熔渣成分的逐渐改变并产生环境污染.这些研究结果表明,为了避免熔渣对氧化锆基耐火材料的严重损坏,可以添加适量的CaF2以提高熔渣的精炼能力.

  7. AZ91D镁合金表面原位合成TiO2陶瓷层及其性能的研究%Surface Modification of AZ91D Mg Alloy with TiO2 Coatingsand Improvement of Mechanical Properties

    孙永花; 王波; 王若云; 姚晓红; 张翔宇; 王振霞


    The AZ91 D Mg alloy was surface-modified with TiO2 coatings,deposited bymicro-arc oxidation and magnetron sputter ion plating.The impact of the micro-arc oxidation time on the microstructures,phase-structures, corrosion /wear resistance was investigated with scanning electron microscopy,X-ray diffraction electrochemical a-nalysis.The results show that depending on the micro-arc oxidation time,the TiO2 coatings significantly improved the microstructures,corrosion resistance and tribological behavior of the Mg-alloy.For example,as the micro-arc oxida-tion time increased,the thickness of TiO2 coatings increased to about 5 μm,consisting mainly of rutile /anatase-phased TiO2 and Mg2 SiO4 ,accompanied by increased pore-size and decreased pore-density.Oxidized for 1 2 min,the porous TiO2 layers were found to cover the inner compact TiO2 layer.The free corrosion potential of the TiO2 coat-ings increases by 299 mV and its free corrosion current decreases by two-order of magnitude.Besides,the corrosion and wear resistance were markedly improved.%采用磁控溅射-微弧氧化复合处理技术,在AZ91 D镁合金表面原位合成TiO2陶瓷层。利用扫描电镜、X射线衍射的方法分析了陶瓷层的形貌特征及物相构成。通过电化学测试、摩擦磨损实验分别研究了陶瓷层的耐蚀性能和耐磨性能。结果表明:陶瓷层表面分布着微米级的微孔,随着氧化时间的延长,微孔的孔径逐渐增大而数量逐渐减少。从截面形貌上可以看出,纯钛膜层的厚度大约为5μm,TiO2陶瓷层由内层致密层和外层疏松层组成,并且厚度随着氧化时间的延长而增加。陶瓷层主要有金红石型 TiO2相、锐钛矿型 TiO2相及 Mg2 SiO4相构成。TiO2陶瓷层的自腐蚀电位比基体提高了299 mv,腐蚀电流降低了2个数量级。此外,陶瓷层表现出了一定的减摩作用,综合性能显著提高。

  8. First-principles study of fission product (Xe, Cs, Sr) incorporation and segregation in alkaline earth metal oxides, HfO2, and MgO-HfO2 interface

    Liu, Xiang-yang [Los Alamos National Laboratory; Uberuaga, Blas P [Los Alamos National Laboratory; Sickafus, Kurt E [Los Alamos National Laboratory


    In order to close the nuclear fuel cycle, advanced concepts for separating out fission products are necessary. One approach is to use a dispersion fuel form in which a fissile core is surrounded by an inert matrix that captures and immobilizes the fission products from the core. If this inert matrix can be easily separated from the fuel, via e.g. solution chemistry, the fission products can be separated from the fissile material. We examine a surrogate dispersion fuel composition, in which hafnia (HfO{sub 2}) is a surrogate for the fissile core and alkaline earth metal oxides are used as the inert matrix. The questions of fission product incorporation in these oxides and possible segregation behavior at interfaces are considered. Density functional theory based calculations for fission product elements (Xe, Sr, and Cs) in these oxides are carried out. We find smaller incorporation energy in hafnia than in MgO for Cs and Sr, and Xe if variation of charge state is allowed. We also find that this trend is reversed or reduced for alkaline earth metal oxides with large cation sizes. Model interfacial calculations show a strong tendency of segregation from bulk MgO to MgO-HfO{sub 2} interfaces.

  9. Synthesis and Characterization of Mg_3(PO_4)_2-coated Li_(1.05)Ni_(1/3)Mn_(1/3)Co_(1/3)O_2 Cathode Material for Li-ion Battery

    CHEN Yuhong; TANG Zhiyuan; ZHANG Guoqing; ZHANG Xuemei; CHEN Ruizhen; LIU Yuangang; LIU Qiang


    Mg_3(PO_4)_2-coated Li_(1.05)Ni_(1/3)Mn_(1/3)Co_(1/3)O_2 cathode materials were synthesized via co-precipitation method.The morphology,structure,electrochemical performance and thermal stability were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS),charge/discharge cycling and differential scanning calorimeter(DSC).SEM analysis shows that Mg_3(PO_4)_2-coating changes the morphologies of their particles and increases the grains size.XRD and CV results show that Mg_3(PO_4)_2-coating powder is homogeneous and has better layered structure than the bare one. Mg_3(PO_4)_2-coating improved high rate discharge capacity and cycle-life performance.The reason why the cycling performance of Mg_3(PO_4)_2-coated sample at 55℃was better than that of room temperature was the increasing of lithium-ion diffusion rate and charge transfer rate with temperature rising. Mg_3(PO_4)_2-coating improved the cathode thermal stability,and the result was consistent with thermal abuse tests using Li-ion cells:the Mg_3(PO_4)_2 coated Li_(1.05)Ni_(1/3)Mn_(1/3)Co_(1/3)O_2 cathode did not exhibit thermal runaway with smoke and explosion,in contrast to the cells containing the bare Li_(1.05)Ni_(1/3)Mn_(1/3)Co_(1/3)O_2.

  10. Sulfide Capacity Model and Its Application in CaO-SiO2-MgO-Al2O3-FetO Slag System%硫容量模型和在五元渣系CaO-SiO2-MgO-Al2O3-FetO中的应用

    李京社; 唐海燕; 孙开明; 温德松



  11. Thermal measurements and computational simulations of three-phase (CeO2-MgAl2O4-CeMgAl11O19) and four-phase (3Y-TZP-Al2O3-MgAl2O4-LaPO4) composites as surrogate inert matrix nuclear fuel

    Angle, Jesse P.; Nelson, Andrew T.; Men, Danju; Mecartney, Martha L.


    This study investigates the temperature dependent thermal conductivity of multiphase ceramic composites for simulated inert matrix nuclear fuel. Fine grained composites were made of CeO2-MgAl2O4-CeMgAl11O19 or 3Y-TZP-Al2O3-MgAl2O4-LaPO4. CeO2 and 3Y-TZP are used as UO2 surrogates due to their similar structures and low thermal conductivities. Laser flash analysis from room temperature to 1273 K (1000 °C) was used to determine the temperature dependent thermal conductivity. A computational approach using Object Oriented Finite Element Analysis Version 2 (OOF2) was employed to simulate the composite thermal conductivity based on the microstructure. Observed discrepancies between experimental and simulated thermal conductivities at low temperature may be due to Kapitza resistance; however, there is less than 3% deviation between models and experiments above 673 K (400 °C) for both compositions. When the surrogate phase was replaced with UO2 in the computational model for the four-phase composite, a 12-16% increase in thermal conductivity resulted compared to single phase UO2, in the range of 673-1273 K (400-1000 °C). This computational approach may be potentially viable for the high-throughput evaluation of composite systems and the strategic selection of inert phases without extensive sample fabrication during the initial development stages of composite nuclear fuel design.

  12. ATG16L1

    Salem, Mohammad; Ammitzboell, Mette; Nys, Kris;


    Genetic variations in the autophagic pathway influence genetic predispositions to Crohn disease. Autophagy, the major lysosomal pathway for degrading and recycling cytoplasmic material, constitutes an important homeostatic cellular process. Of interest, single-nucleotide polymorphisms in ATG16L1...... (autophagy-related 16-like 1 [S. cerevisiae]), a key component in the autophagic response to invading pathogens, have been associated with an increased risk of developing Crohn disease. The most common and well-studied genetic variant of ATG16L1 (rs2241880; leading to a T300A conversion) exhibits a strong...

  13. Phase Equilibrium Studies of CaO-SiO2-MgO-Al2O3 System with Binary Basicity of 1.5 Related to Blast Furnace Slag

    Kou, Mingyin; Wu, Shengli; Ma, Xiaodong; Wang, Laixin; Chen, Mao; Cai, Qingwu; Zhao, Baojun


    Slags play an important role in blast furnace operation, and their compositions are based on the CaO-SiO2-MgO-Al2O3 quaternary system in many steel companies. The binary basicity (CaO/SiO2 weight ratio) of blast furnace slags, especially primary slag and bosh slag, can be as high as 1.5 or higher. Phase equilibria and liquidus temperatures in the CaO-SiO2-MgO-Al2O3 system with binary basicity of 1.50 are experimentally determined for temperatures in the range 1723 K to 1823 K (1450 °C to 1550 °C). High temperature equilibration, quenching, and electron probe X-ray microanalysis techniques have been used in the present study. The isotherms are obtained in the primary phase fields of Ca2SiO4, melilite, spinel, periclase, and merwinite related to blast furnace slags. Effects of Al2O3, MgO, and binary basicity on liquidus temperatures have been discussed. In addition, extensive solid solutions have been measured for different primary phases and will be used for development and optimization of the thermodynamic database.

  14. Development of MgO-CaO-ZrO2 Refractories in Cement Rotary Kiln%水泥窑用镁钙锆质耐火材料的发展

    田晓利; 薛崇勃; 薛群虎; 闫振华


    The development process of cement rotary kiln refractories in cement rotary kiln and the research status of MgO-CaO-ZrO2 refractories in home and abroad were introduced. The MgO-CaO-ZrO2 composite material had advantages of magnesia materials, and its mineral composition contained a certain amount calcium silicate phase. Thus, it had a good thermal shock resistance, a high softening temperature under load, an excellent erosion resistance and suitable mechanical properties, which had important significance and high practical value.%介绍了水泥回转窑用耐火材料的发展历程以及国内外镁钙锆质耐火材料的研究现状,指出MgO-CaO-ZrO2复相材料既具有镁质材料的优点,矿物相组成中又包含一定数量的钙硅酸盐相,从而具有良好的抗热震性、较高的荷重软化温度及优异的抗硅酸盐水泥熟料的侵蚀性能、适宜的力学强度等,具有较高的实用价值.

  15. Materiales vitrocerámicos del sistema MgO-Al2O3-SiO2 a partir de ceniza de cáscara de arroz

    Romero, M.


    Full Text Available This wok shows the results of a valorisation study to use rice husk ash as raw material to develop glass-ceramic materials. An original glass has been formulated in the base system MgO-Al2O3-SiO2 with addition of B2O3 and Na2O to facilitate the melting and poring processes. Glass characterization was carried out by determining its chemical composition. Sintering behaviour has been examined by Hot Stage Microscopy (HSM. Thermal stability and crystallization mechanism have been studied by Differential Thermal Analysis (DTA. Mineralogy analyses of the glass-ceramic materials were carried out using X-ray Diffraction (XRD. Results show that it is possible to use ash rice husk to produce glass-ceramic materials by a sintercrystallization process, with nepheline (Na2O·Al2O3 · SiO2 as major crystalline phase in the temperature interval 700-950ºC and forsterite (2MgO·SiO2 at temperatures above 950ºC.En este trabajo se muestran los resultados de un estudio de valorización de la ceniza de cáscara de arroz como materia prima en la obtención de materiales vitrocerámicos. Se ha formulado un vidrio en el sistema base MgO-Al2O3-SiO2 incorporando B2O3 y Na2O para facilitar los procesos de fusión y colado del vidrio. El vidrio se ha caracterizado mediante la determinación de su composición química. Su comportamiento frente a la sinterización se ha llevado a cabo mediante Microscopía de Calefacción (MC. La estabilidad térmica de las muestras y el mecanismo de cristalización preferente se ha estudiado mediante Análisis Térmico Diferencial (ATD. La mineralogía de los materiales vitrocerámicos se ha llevado a cabo por Difracción de rayos-X (DRX. Los resultados obtenidos muestran que es posible utilizar ceniza de cáscara de arroz para producir materiales vitrocerámicos mediante un proceso de sinterización seguido de cristalización, con nefelina (Na2O·Al2O3·2SiO2 como fase cristalina mayoritaria en el intervalo de temperatura 700º-950ºC y

  16. The Influence of Sintering Temperature on the Microwave Dielectric Properties of Mg2SiO4 Ceramics with CaO-B2O3-SiO2 Addition

    Yang, Hongyu; Li, Enzhu; Sun, Chengli; Duan, Shuxin; Yuan, Ying; Tang, Bin


    Conventional solid-state methods were used to synthesize Mg2SiO4 ceramic at relatively low sintering temperatures with the assistance of CaO-B2O3-SiO2 (CBS) glass. The effects of the CBS additions on the sintering behavior, crystal structures, microstructures, and microwave dielectric properties of Mg2SiO4 ceramic have been investigated in detail. The results indicate that the addition of CBS glass lowered the sintering temperature of Mg2SiO4 ceramic significantly. The Mg2SiO4 ceramic with 7 wt.% CBS addition sintered at 1325°C for 4 h shows excellent microwave dielectric properties: ɛ r = 6.47, Q × f = 16,552 GHz, τ f = -23.34 ppm/°C.

  17. Role of basicity and tetrahedral speciation in controlling the thermodynamic properties of silicate liquids, part 1: the system CaO-MgO-Al 2O 3-SiO 2

    Beckett, John R.


    Activity coefficients of oxide components in the system CaO-MgO-Al 2O 3-SiO 2 (CMAS) were calculated with the model of Berman (Berman R. G., "A thermodynamic model for multicomponent melts with application to the system CaO-MgO-Al 2O 3-SiO 2," Ph.D. dissertation, University of British Columbia, 1983) and used to explore large-scale relationships among these variables and between them and the liquid composition. On the basis of Berman's model, the natural logarithm of the activity coefficient of MgO, ln(γ MgOLiq), and ln(γ MgOLiq/γ SiO 2Liq) are nearly linear functions of ln(γ CaOLiq). All three of these variables are simple functions of the optical basicity Λ with which they display minima near Λ ˜ 0.54 that are generated by liquids with low ratios of nonbridging to tetrahedral oxygens (NBO/T) (factor in determining the thermodynamic properties of aluminosilicate liquids. For a constant NBO/T, ln(γ CaOLiq/γ Al 2O 3Liq) and ln(γ MgOLiqγ Al 2O 3Liq) form curves in terms of X SiO 2Liq/X Al 2O 3Liq. The same liquids that generate minima in the Λ plots are also associated with minima in ln(γ CaOLiqγ Al 2O 3Liq) and ln(γ MgOLiqγ Al 2O 3Liq) as a function of X SiO 2Liq/X Al 2O 3Liq. In addition, there are maxima or sharp changes in slope for NBO/T > 0.3, which occur for X SiO 2Liq/X Al 2O 3Liq ranging from ˜0 to ˜6 and increase with increasing NBO/T. The systematic variations in activity coefficients as a function of composition and optical basicity reflect underlying shifts in speciation as the composition of the liquid is changed. On the basis of correlations among the activity coefficients, it is likely that the use of CaO, an exchange component such as SiMg -1 and two of MgO, CaAl 2O 4, or MgAl 2O 4 would yield significant savings in the number of parameters required to model the excess free energy surface of liquids over large portions of CMAS relative to the use of oxide end members. Systematic behavior of thermodynamic properties extends to small

  18. Improved Performance of Dye-Sensitized Solar Cells Fabricated from a Coumarin NKX-2700 Dye-Sensitized TiO2/MgO Core-Shell Photoanode with an HfO2 Blocking Layer and a Quasi-Solid-State Electrolyte

    Maheswari, D.; Venkatachalam, P.


    Dye sensitized solar cells (DSSC) were fabricated from a coumarin NKX-2700 dye-sensitized core-shell photoanode and a quasi-solid-state electrolyte, sandwiched together, with a cobalt sulfide-coated counter electrode. The core-shell photoanode consisted of a composite mixture of 90% TiO2 nanoparticles and 10% TiO2 nanowires (TNPW) as core layer and MgO nanoparticles (MNP) as shell layer. Hafnium oxide (HfO2) was applied to the core-shell photoanode film as a blocking layer. TiO2 nanoparticles, TiO2 nanowires, and TNPW/MNP were characterized by x-ray diffractometry, scanning electron microscopy, and transmission electron microscopy. It was apparent from the UV-visible spectrum of the sensitizing dye coumarin NKX-2700 that its absorption was maximum at 525 nm. Power conversion efficiency (PCE) was greater for DSSC-1, fabricated with a core-shell TNPW/MNP/HfO2 photoanode, than for the other DSSC; its photovoltaic properties were: short circuit photocurrent J sc = 19 mA/cm2, open circuit voltage ( V oc) = 720 mV, fill factor ( FF) = 66%, and PCE ( η) = 9.02%. The charge-transport and charge-recombination behavior of the DSSC were investigated by electrochemical impedance spectroscopy; the results showed that the composite core-shell film resulted in the lowest charge-transfer resistance ( R CE) and the longest electron lifetime ( τ eff). Hence, the improved performance of DSSC-1 could be ascribed to the core-shell photoanode with blocking layer, which increased electron transport and suppressed recombination of charge carriers at the photoanode/dye/electrolyte interface.

  19. Microwave dielectric properties of (A2+(1/3)B5+(2/3))0.5Ti0(0.5)O2 (A2+ = Zn, Mg, B5+ = Nb, Ta) ceramics.

    Kim, E S; Kang, D H


    Dielectric properties of (A(2+)(1/3)B(5+)(2/3))(0.5)Ti0(0.5)O(2) (A(2+) = Zn, Mg, B(5+) = Nb, Ta) ceramics were investigated at microwave frequencies. A single phase with tetragonal rutile structure was obtained through the entire compositions. Dielectric properties were strongly dependent on the structural characteristics. The specimens with B(5+) = Nb showed a larger dielectric constant than those with B(5+) = Ta due to the decrease of bond valence. Quality factors (Qf) of the specimens with B(5+) = Ta were larger than those with B(5+) = Nb. Temperature coefficient of the resonant frequencies (TCF) of (Zn(1/3)Nb(2/3) )0(0.5)Ti0(0.5)O(2) was larger than that of (Mg(1/3)Ta(2/3))0(0.5)Ti0(0.5)O(2). These results could be attributed to the changes of the temperature coefficient of dielectric constant and the degree of oxygen octahedral distortion.

  20. A Sulfide Capacity Prediction Model of CaO-SiO2-MgO-FeO-MnO-Al2O3 Slags during the LF Refining Process Based on the Ion and Molecule Coexistence Theory

    Yang, Xue-Min; Zhang, Meng; Shi, Cheng-Bin; Chai, Guo-Ming; Zhang, Jian


    A sulfide capacity prediction model of CaO-SiO2-MgO-FeO-MnO-Al2O3 ladle furnace (LF) refining slags has been developed based on the ion and molecule coexistence theory (IMCT). The predicted sulfide capacity of the LF refining slags has better accuracy than the measured sulfide capacity of the slags at the middle and final stages during the LF refining process. Increasing slag binary basicity, optical basicity, and the Mannesmann index can lead to an increase of the predicted sulfide capacity for the LF refining slags as well as to an increase of the sulfur distribution ratio between the slags and molten steel at the middle and final stages during the LF refining process. The calculated equilibrium mole numbers, mass action concentrations of structural units or ion couples, rather than mass percentages of components, are recommended to represent the slag composition for correlating with the sulfide capacity of the slags. The developed sulfide capacity IMCT model can calculate not only the total sulfide capacity of the slags but also the respective sulfide capacity of free CaO, MgO, FeO, and MnO in the slags. The comprehensive contribution of the combined ion couples (Ca2+ + O2-) and (Mn2+ + O2-) on the desulfurization reactions accounts for 96.23 pct; meanwhile, the average contribution of the ion couple (Fe2+ + O2-) and (Mg2+ + O2-) only has a negligible contribution as 3.13 pct and 0.25 pct during the LF refining process, respectively. The oxygen activity of bulk molten steel in LF is controlled by the [Al]-[O] equilibrium, and the oxygen activity of molten steel at the slag-metal interface is controlled by the (FeO)-[O] equilibrium. The ratio of the oxygen activity of molten steel at the slag-metal interface to the oxygen activity of bulk molten steel will decrease from 37 to 5 at the initial stage, and further decrease from 28 to 4 at the middle stage, but will maintain at a reliable constant as 5 to 14 at the final stage during the LF refining process. The

  1. Effect of Al2O3, MgO, and CuOx on the dissolution behavior of rhodium in the Na2O-SiO2 slags

    Wiraseranee C.


    Full Text Available Aiming to optimize rhodium recovery in the high temperature recycling process by minimizing rhodium loss into slags in an oxidizing atmosphere by controlling slag composition, the effects of representative slag components, such as Al2O3, MgO, and CuOx, on the dissolution behavior of rhodium into the Na2O-SiO2 slags was investigated. The solubility of rhodium was measured by equilibrating the sodium silicate based slags with pure solid rhodium at 1473 K in air. Considering that rhodium dissolved into slags as RhO1.5, the effect of the oxide addition on the activity coefficient of RhO1.5 in slags was determined. The dissolution of rhodium in slags was suppressed by the addition of Al2O3 and MgO, where Al2O3 behaved as an acidic oxide and MgO behaved as a diluent of slag basicity at a fixed Na2O/SiO2 ratio of 0.97. The content of copper in solid rhodium equilibrated with the CuOx bearing slags slightly increased with increasing content of CuOx, and CuOx was found to slightly enhance the dissolution of rhodium. Rhodate capacity of all slag systems increased with increasing optical basicity, suggesting that the correlation between rhodate capacity and the optical basicity enables the estimation of the content of rhodium in slags of which thermodynamic properties of rhodium are not clarified.

  2. Effect of Mg-doping on the structural and magnetic properties of CoFe_2O_4/SiO_2 nanocomposite films%掺杂Mg对纳米CoFe_2O_4/SiO_2复合薄膜结构和磁性的影响

    刘宇; 李季; 张玉梅; 华杰; 刘梅; 李海波


    采用溶胶-凝胶旋涂法制备了纳米Co1-xMgxFe2O4/SiO2(x=0,0.2,0.4,0.6,0.8)复合薄膜。利用XRD、SEM、原子力显微镜、振动样品磁强计对薄膜的结构、形貌和磁性进行了分析,研究了Mg2+含量对样品结构和磁性的影响。结果表明,样品中Co1-xMgxFe2O4具有尖晶石结构,晶粒尺寸在38~46nm之间。随着Mg2+含量的增加,Co1-xMgxFe2O4的晶格常数减小,样品的饱和磁化强度减小,矫顽力先增大后减小。样品Co0.4Mg0.6Fe2O4/SiO2垂直和平行膜面的矫顽力分别为350.7kA.m-1和279.4kA.m-1,剩磁比分别为67.2%和53.9%,Co1-xMgxFe2O4/SiO2复合薄膜具有较明显的垂直磁各向异性。%Co1-xMgxFe2O4/SiO2(x=0,0.2,0.4,0.6,0.8) nanocomposite films were prepared by the sol-gel spin-coating process.The effect of the addition of Mg2+ with various content on the structure and magnetic properties of the samples was investigated.The structure,morphology and magnetic properties of the films had been studied through XRD,SEM,atomic force microscopy(AFM) and vibrating sample magnetometer(VSM).The results show that the Co1-xMgxFe2O4 presents spinel structure in composite films with the grain size of about 38~46 nm.As the content of Mg increases,the lattice constant of Co1-xMgxFe2O4 decreases,the saturation magnetization of sample films also decreases,while the coercivity first increases and then decreases.The value of coercivity and remanence ratio in the direction of parallel to the plane for Co0.4Mg0.6Fe2O4/SiO2 sample film is 279.4 kA·m-1 and 53.9%,respectively,while the corresponding value in the direction of perpendicular to the plane is 350.7 kA·m-1 and 67.2%.The Co1-xMgxFe2O4/SiO2 nanocomposite films display distinct perpendicular magnetic anisotropy.

  3. 钠离子电池正极材料Na(Mn0.4Fe0.2Ni0.35Mg0.05)O2的制备及电化学性能研究%Synthesis and electrochemical performance of Na (Mn0.4Fe0.2Ni0.35Mg0.05)O2 as cathode materials for sodium ion batteries

    阮艳莉; 郑斌; 刘萍


    采用溶胶-凝胶法合成钠离子电池正极材料Na(Mn0.4Fe0.2Ni0.4)O2,并对其进行Mg元素掺杂合成Na(Mn0.4Fe0.2Ni0.35Mg0.05)O2材料,分别对2种材料的表面形貌、结构以及电化学性能进行了研究.结果表明:掺杂合成的样品Na(Mn0.4Fe0.2Ni0.35Mg0.05)O2同样具有O3型层状结构,虽然首次放电比容量降低至125.6 mAh/g,但是其循环性能和倍率性能却明显优于原始样品.在循环50次之后,其放电比容量仍可达114.7 mAh/g,对应的容量保持率为91.3%.在1C倍率下,仍能释放出90.1 mAh/g的可逆容量.此外,交流阻抗结果表明,该材料具有更小的电荷转移阻抗.%Na(Mn0.4Fe0.2Ni0.4)O2 and Na (Mn0.4Fe0.2Ni0.35Mg0.05)O2 are synthesized by a sol-gel method and used as cathode materials for sodium ion batteries.The morphology,structure and electrochemical performances of the samples are investigated by scanning electron microscope,X-ray diffraction and charge-discharge test.The results manifeste that the O3-type structure remains unchanged after substitution.The magnesium-substituted sample,Na(Mn0.4 Fe0.2Ni0.35Mg0.05)O2,exhibits improved capacity retention and rate performance at the price of the initial reversible capacity.The initial discharge capacity is 125.6 mAh/g and the capacity retention is 91.3% after 50 cycles at the current density of 10 mA/g.Even at a high discharge rate of 1 C,it still delivers a discharge capacity of 90.1 mAh/g.Electrochemical Impedance Spectroscopy (EIS) measurements demonstrate that the charge transfer resistance of Na (Mn0.4Fe0.2Ni0.35Mg0.05) O2 is smaller than the pristine sample.

  4. The MgO-Al2O3-SiO2 system - Free energy of pyrope and Al2O3-enstatite. [in earth mantle formation

    Saxena, S. K.


    The model of fictive ideal components is used to determine Gibbs free energies of formation of pyrope and Al2O3-enstatite from the experimental data on coexisting garnet and orthopyroxene and orthopyroxene and spinel in the temperature range 1200-1600 K. It is noted that Al2O3 forms an ideal solution with MgSiO3. These thermochemical data are found to be consistent with the Al2O3 isopleths that could be drawn using most recent experimental data and with the reversed experimental data on the garnet-spinel field boundary.

  5. Studies in the system MgO-SiO2-CO2-H2O(I): The activity-product constant of chrysotile

    Hostetler, P.B.; Christ, C.L.


    Chrysotile dissolves congruently in water according to the reaction: Mg3Si2O6(OH)4c + 5H2Ol = 3Mgaq2+ + 6OHaq- + 2H4SiO4aq. Experimental determination of the activity-product constant of chrysotile, Kchr = [Mg2+]3[OH-]6[H4SiO4aq]2, at 90??C, yields the value of Kchr = 10-49.2 ?? 100.5. A synthetic sample and a natural sample from New Idria, California, were used in the determination. Values of Kchr were calculated for temperatures ranging from 0??C to 200??C, using the thermochemical data of King et al. (1967) for chrysotile and antigorite, various solubility data for silica, and ionic partial molal heat capacities estimated by the method of criss and Cobble (1964a). Kchr is 10-54.1 at 0??C, rises to a maximum value of 10-48.5 at approximately 135??C, and is 10-49.1 at 200??C (all values for the three-phase system, chrysotile plus solution plus vapor). The calculated 90??C value is 10-49.1, in excellent agreement with the experimental value; for 25??C, the calculated value is 10-50.8. ?? 1968.

  6. Advanced oxidation removal of hypophosphite by O3/H2O2 combined with sequential Fe(II) catalytic process.

    Zhao, Zilong; Dong, Wenyi; Wang, Hongjie; Chen, Guanhan; Wang, Wei; Liu, Zekun; Gao, Yaguang; Zhou, Beili


    Elimination of hypophosphite (HP) was studied as an example of nickel plating effluents treatment by O3/H2O2 and sequential Fe(II) catalytic oxidation process. Performance assessment performed with artificial HP solution by varying initial pH and employing various oxidation processes clearly showed that the O3/H2O2─Fe(II) two-step oxidation process possessed the highest removal efficiency when operating under the same conditions. The effects of O3 dosing, H2O2 concentration, Fe(II) addition and Fe(II) feeding time on the removal efficiency of HP were further evaluated in terms of apparent kinetic rate constant. Under improved conditions (initial HP concentration of 50 mg L(-1), 75 mg L(-1) O3, 1 mL L(-1) H2O2, 150 mg L(-1) Fe(II) and pH 7.0), standard discharge (oxidation treatment favored the improvement of phosphorus removal due to the formation of more metal hydroxides. Moreover, as a comparison with lab-scale Fenton approach, the O3/H2O2─Fe(II) oxidation process had more competitive advantages with respect to applicable pH range, removal efficiency, sludge production as well as economic costs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Interaction of SiO2 Nanoparticles with Seed Prechilling on Germination and Early Seedling Growth of Tall Wheatgrass (Agropyron Elongatum L.

    Azimi Reyhane


    Full Text Available The effect of six SiO2 nanosized concentrations (0, 5, 20, 40, 60 and 80 mg L-1 and three seed prechilling treatments (control, seed prechilling before nano SiO2 treatments, treatments of seed with nano SiO2 before prechilling on germination and seedling growth of tall wheatgrass (Agropyron elongatum L. were studied. Results indicated that application of SiO2 nanoparticles significantly increased seed germination of tall wheatgrass from 58 percent in control group to 86.3 and 85.7 percent in 40 and 60 mg L-1, respectively. Applying SiO2 nanoparticles increased dry weight of shoot, root and seedling of tall wheatgrass. Increasing concentration of nanoparticle from 0 up to 40 mg L-1 increased seedling weight around 49 percent compared to the control, nevertheless decreased under 60 and 80 mg L-1 treatments. In conclusion, seed prechilling in combination with SiO2 nanoparticles largely broke the seed dormancy for A. elongatum.

  8. Synthesis of MgO-CaO-Al2O3-SiO2 nanocomposite powder by polymeric complex method as a novel sintering additive of AlN ceramics

    Lee, Hwa-Jun; Cho, Woo-Seok; Kim, Hyeong Jun; Pan, Wei; Shahid, Mohammad; Ryu, Sung-Soo


    A MgO-CaO-Al2O3-SiO2 (MCAS) nanocomposite powder with a particle size of 50 nm and a specific surface area of 40.6 m2/g was successfully synthesized via heat-treatment of polymeric precursors containing Mg, Ca, Al and Si in air at 700 °C for 5 h. It was characterized as a novel sintering additive for the densification AlN ceramics at a low temperature below 1600 °C. It was found that the nanosized MCAS powder was suitable for the densification of AlN ceramics. In particular, full densification could be achieved when only 1.0 wt% MCAS additive-doped AlN powder compact was sintered for 1 h at 1600 °C, and a thermal conductivity of 84 W/m·K was attained.

  9. Thermodynamic Behavior of Manganese and Phosphorus between Liquid Iron and CaO-MgO-SiO2-Al2O3-FetO-MnO-P2O5 Slags


    The thermodynamic behavior of manganese and phosphorus betwe en liquid iron and CaO-MgO-SiO2-Al2O3-FetO-MnO-P2O5 ladle slag system was addressed by investigating the thermodynamic equilibria between li quid iron containing Mn and P and the ladle slag at 1873K. The Mn dist ribution ratio LMn increases with increasing FetO content and decreasi ng the basicity ((%CaO + %MgO)/ +%Al2O3+%P2O5)) in slag, while the P d istribution ratio LP seems to be increased as FetO content and the bas icity increases. The values of LMn and LP decrease by the addition of Al2O3 into slag. The expression of the dependence of LMn and LP on the basicity and content in slag was obtained.

  10. The Effect of Water on the Growth of Multi-layered Polycrystalline Reaction rims in the System CaO-MgO-SiO2

    Wohlers, A.; Joachim, B.; Koch-Mueller, M.; Schade, U.


    The effect of traces of water is of paramount importance for kinetics in natural rocks. Experimental results show that traces of water released at a reaction front have a major effect on the growth rates and phase sequence of the reaction rim. Experiments on polished synthetic, single crystals of OH-doped periclase (MgO) and wollastonite (dry) (CaSiO3) were reacted in an Internally Heated Pressure device at 0.5 GPa and 1200°C, 21.5hr to 96hr. Water-doped periclase as starting material allows to control the water initiation to the experiments on the ppm level. Homogenous OH distribution of the periclase starting material was analyzed with FTIR spectroscopy. In the absence of an periclase-specific calibration, the quantification of hydrogen concentration expressed as H2O-equivalent was done after [1] and gives 3.5 wt ppm H2O at ambient P/T. Raman spectroscopy, which shows OH-defect related bands at identical wavenumbers yields an H2O equivalent concentration of about 9 wt ppm quantified after [2]. A complex multi-layered rim consisting of the phases forsterite, monticellite, merwinite and akermanite grows between periclase and wollastonite at the P/T conditions mentioned above. Rim thickness of individual rim phases are between 3 to 20 μm. Conventional and synchrotron IR radiation was used at Bessy II (Berlin, Germany) with a spatial resolution down to 5 x 5 μm to analyze how water prevails in the starting material and reaction rims. A series of FTIR spectra were recorded in a line scan over the periclase toward the rim sequence. The periclase spectra show typical absorption bands at 3297 and 3310.5 cm-1 which are interpreted as OH stretching vibrations [3]. In addition an absorption band at 3697 cm-1 is observed, which is associated to Mg(OH)2 precipitate [4], which develops during quenching. In general the initial OH-doped periclase partially dehydrated during the rim growth experiments. We observe a gradient towards the reaction rim: water concentration

  11. Synthesis, characterization and evaluation of bioactivity and antibacterial activity of quinary glass system (SiO2–CaO–P2O5–MgO–ZnO): In vitro study

    Fatemeh Baghbani; Fathollah Moztarzadeh; Leila Hajibaki; Masoud Mozafari


    Bioactive glasses in the systems SiO2–CaO–P2O5–MgO (BGZn0) and SiO2–CaO–P2O5–MgO–ZnO (BGZn5), were prepared by sol–gel method and then characterized. Surface reactivity was studied in simulated body fluid (SBF) to determine the effect of zinc (Zn) addition as a trace element. The effect of Zn addition to the glass matrix on the formation of apatite layer on the glass surface was investigated through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT–IR) and scanning electron microscopy (SEM). Also, inductively coupled plasma–optical emission spectroscopy (ICP–OES) was used to determine the concentrations of released ions in SBF solution after different time intervals in SBF solution. The antibacterial activity of Zn containing glass against Pseudomonas aeruginosa was measured by the halo zone test. The presence of Zn in glass composition improved chemical durability, slowed down the formation rate of Ca–P layer and decreased the size of crystalline apatite particles. Zn containing glass exhibited an excellent antibacterial activity against P. aeruginosa which could demonstrate its ability to treat bone infection.

  12. Effects of Al2O3 and MgO on Softening, Melting, and Permeation Properties of CaO-FeO-SiO2 on a Coke Bed

    Ueda, Shigeru; Kon, Tatsuya; Miki, Takahiro; Kim, Sun-Joong; Nogami, Hiroshi


    In ironmaking, maintaining gas permeability in blast furnace with low coke rate operation is essential to reduce carbon emissions. The high pressure loss in the cohesive zone decreases the gas permeability and affects the productivity of blast furnace. In order to increase the gas permeability in the cohesive zone, the thickness of the cohesive layer should be decreased. For this purpose, increasing softening temperature and decreasing dripping temperature of the iron ore are desired. In this study, softening, melting, and permeation of SiO2-FeO-CaO-Al2O3-MgO on a coke bed were investigated. The oxide sample in a tablet form was heated under CO/CO2 atmosphere, and the shape of the tablet was observed. The softening and melting temperatures of the SiO2-FeO-CaO system changed with the addition of Al2O3 and MgO. Oxide tablets with and without Al2O3 softened below and above the solidus temperature, respectively. The melting temperatures varied with the ratio of CO/CO2 in the gas. The permeation temperature was independent of the melting temperature, but dependent on the wettability.

  13. Effect of Al2O3 on the Viscosity and Structure of CaO-SiO2-MgO-Al2O3-FetO Slags

    Wang, Zhanjun; Sun, Yongqi; Sridhar, Seetharaman; Zhang, Mei; Guo, Min; Zhang, Zuotai


    The present paper provided a fundamental investigation on the effect of Al2O3 on the viscosity and structure of CaO-SiO2-MgO-Al2O3-FetO slags for the purpose of efficiently recycling the valuable elements from the steelmaking slags. The results show that the viscosity of CaO-SiO2-Al2O3-MgO-FetO slags slightly increases with increasing Al2O3 content. The degree of the polymerization (DOP) of quenched slags, determined from Raman spectra and magic angle spinning-nuclear magnetic resonance, is also found to increase with increasing Al2O3 content. It can be deduced that the increasing DOP can promote the formation of gehlenite phase (Ca2Al2SiO7), thus facilitating the formation of higher phosphorous (or vanadium) contained solid solution ( n'Ca2SiO4·Ca3((P or V)O4)2). As Al2O3 content increases up to a specific value, the charge compensating ions which present near [AlO4]-tetrahedra and [FeO4]-tetrahedra are not fully supplied due to the scarcity of Ca2+. In this case, the existing Fe3+ in the melt cannot completely form [FeO4]-tetrahedra and part of Fe3+ would form [FeO6]-octahedra to substitute Ca2+ to modify the slags.

  14. Effect of La2O3-Dopant on Microstructure and Microwave Dielectric Properties of CaO-MgO-Nb2O5-TiO2 System Ceramics

    Wang Hao; Chen Wen; Liu Tao


    La2O3-doped CaO-MgO-Nb2O5-TiO2 system ceramics were prepared by solid-state ceramic technique. The microstructure and microwave dielectric properties of CaO-MgO-Nb2O5-TiO2-La2O3 ceramics can be adjusted by varying the amount of La3+ ions. The results show that the replacement of Ca2+ by La3+ at A-site of the ceramics can increase the quality factor Q*f value as well as the temperature coefficient of resonant frequency τf and decrease the dielectric constant εr. With increase of La3+ contents, the dielectric constant decreases from 57 to 35 and Q*f value increases from 33400 GHz to 35000 GHz (at 7.6 GHz). Meanwhile, the temperature coefficient of resonant frequency is improved towards near zero. The dielectric properties of these compounds are related to octahedra tilting due to deficient vacancies at A-site.

  15. Shear viscosities of CaO-Al 2O 3-SiO 2 and MgO-Al 2O 3-SiO 2 liquids: Implications for the structural role of aluminium and the degree of polymerisation of synthetic and natural aluminosilicate melts

    Toplis, Michael J.; Dingwell, Donald B.


    The shear viscosity of 66 liquids in the systems CaO-Al 2O 3-SiO 2 (CAS) and MgO-Al 2O 3-SiO 2 (MAS) have been measured in the ranges 1-10 4 Pa s and 10 8-10 12 Pa s. Liquids belong to series, nominally at 50, 67, and 75 mol.% SiO 2, with atomic M 2+/(M 2++ 2Al) typically in the range 0.60 to 0.40 for each isopleth. In the system CAS at 1600°C, viscosity passes through a maximum at all silica contents. The maxima are clearly centered in the peraluminous field, but the exact composition at which viscosity is a maximum is poorly defined. Similar features are observed at 900°C. In contrast, data for the system MAS at 1600°C show that viscosity decreases with decreasing Mg/(Mg + 2Al) at all silica contents, but that a maximum in viscosity must occur in the field where Mg/2Al >1. On the other hand, the viscosity at 850°C increases with decreasing Mg/(Mg + 2Al) and shows no sign of reaching a maximum, even for the most peraluminous composition studied. The data from both systems at 1600°C have been analysed assuming that shear viscosity is proportional to average bond strength and considering the equilibrium: Al-(⇔(-NBO+Al where Al [4]-(Mg,Ca) 0.5 represents a charge-balanced tetrahedrally coordinated Al; (Mg, Ca) 0.5-NBO represents a nonbridging oxygen (NBO) associated with Ca or Mg, and Al XS represents any structural role of Al that does not require a charge-balancing cation. The viscosity data were fitted using two adjustable variables: i) the equilibrium constant of the above reaction, and ii) the relative bond strength of Al XS. The values of these parameters in the system CAS suggest that Al XS remains in tetrahedral coordination, its charge deficit being satisfied by association with a three-coordinate oxygen in a structure called a tricluster. In contrast, fits to the MAS data at 1600°C infer the presence of high-coordinate Al. These interpretations are found to be consistent with independent spectroscopic and theoretical data. Furthermore, the fitted

  16. 退火温度对纳米Co0.8Mg0.2Fe2O4/SiO2复合薄膜结构和磁性的影响%Effects of Annealing Temperature on Structure and Magnetic Properties of Co0.8Mg0.2Fe2O4/SiO2 Nanocomposite Films

    刘宇; 刘梅; 张玉梅; 李季; 李海波


    Co0.8Mg0.2Fe2O4/SiO2 nanocomposite films were prepared by the sol-gel method. Structure, morphology and magnetic properties of the nanocomposite films were characterized by the X-ray diffraction, atomic force microscopy and vibrating sample magnetometry (VSM), and effects of annealing temperature on structure and magnetic properties of the nanocomposite films were studied. Results show that the sample exhibits a Co0.8Mg0.2Fe2O4 spinel structure after being annealed at 800 ℃. With the increasing of the annealing temperature, the grain size of Co0.8Mg0.2Fe2O4 in the nanocomposite films increases, while the lattice constant decreases. The VSM results show that magnetization and remanence ratio (Mr/M5) increases with the increasing of the grain size of Co0.8Mg0.2Fe2O4, while the coercivity of samples tends to increase first, and then decrease. Perpendicular coercivity of the sample annealed at 1 100 ℃ reaches 296.1 kA/m. The films possess an obvious perpendicular magnetic anisotropy.%采用溶胶-凝胶旋涂法制备纳米Co0.8Mg0.2Fe2O4/SiO2复合薄膜.用X射线衍射仪、原子力显微镜及振动样品磁强计分析复合薄膜的结构、表面形貌和磁性,研究退火温度对复合薄膜结构和磁性的影响.结果表明:经800℃退火处理的样品中已形成Co0.8Mg0.2Fe2O4晶相;随着退火温度的提高,Co0.8Mg0.2Fe2O4晶粒尺寸变大,晶格常数减小:随着Co0.8Mg0.2Fe2O4晶粒尺寸的增大,样品的磁化强度和剩磁比变大,矫顽力先增大后减小,经1 100℃退火处理样品的垂直膜面矫顽力达到296.1 kA/m:样品存在较明显的垂直磁各向异性.

  17. CaF2-CaO-Al2O3-SiO2-MgO五元渣的表面张力及其在镍基合金电渣重熔的应用%Surface Tension of Pentary Slag CaF2-CaO-Al2O3-SiO2-MgO and Its Application in Nickel Base Alloy Electro-Slag Remelting

    刘立; 赵俊学; 李献民; 丁五洲; 陈峰; 李小孟


    试验研究了五元渣(/%:50~65CaF2,6~15CaO,18~30Al2O3,4~10SiO2,1~7MgO)的组元含量、熔渣温度(1 330 ~1 463℃)对表面张力的影响.结果表明,随熔渣温度升高,其表面张力下降,1 463℃五元渣的表面张力为0.372~0.418 N/m.60CaF2-15CaO-6SiO2-18Al2 O3-5MgO具有较低的表面张力(0.375 N/m),较好的流动性和低粘度值.3t电渣炉熔炼镍基合金Inconel600和625的工业应用结果表明,电渣锭成分均匀,[O]≤20×10-6,[N]≤50 ×10-6,平均电耗从原ANF-6渣重熔的1 933 kWh/t降至1 326 kWh/t.

  18. Evidence of phytotoxicity and genotoxicity in Hordeum vulgare L. exposed to CeO2 and TiO2 nanoparticles

    Alessandro eMattiello


    Full Text Available Engineered nanoscale materials (ENMs are considered emerging contaminants since they are perceived as a potential threat to the environment and the human health. The reactions of living organisms when exposed to metal nanoparticles (NPs or NPs of different size are not well known. Very few studies on NPs-plant interactions have been published, so far. For this reason there is also great concern regarding the potential NPs impact to food safety. Early genotoxic and phytotoxic effects of cerium oxide nanoparticles (nCeO2 and titanium dioxide nanoparticles (nTiO2 were investigated in seedlings of Hordeum vulgare L.Caryopses were exposed to an aqueous dispersion of nCeO2 and nTiO2 at respectively 0, 500, 1000 and 2000 mg l-1 for 7 days. Genotoxicity was studied by Randomly Amplified Polymorphism DNA (RAPDs and mitotic index on root tip cells. Differences between treated and control plants were observed in RAPD banding patterns as well as at the chromosomal level with a reduction of cell divisions. At cellular level we monitored the oxidative stress of treated plants in terms of reactive oxygen species (ROS generation and ATP content. Again nCeO2 influenced clearly these two physiological parameters, while nTiO2 were ineffective. In particular, the dose 500 mg l-1 showed the highest increase regarding both ROS generation and ATP content; the phenomenon were detectable, at different extent, both at root and shoot level. Total Ce and Ti concentration in seedlings was detected by ICP-OES. TEM EDSX microanalysis demonstrated the presence of aggregates of nCeO2 and nTiO2 within root cells of barley. nCeO2 induced modifications in the chromatin aggregation mode in the nuclei of both root and shoot cells.

  19. Atomistic origins of pressure-induced changes in the O K -edge x-ray Raman scattering features of Si O2 and MgSi O3 polymorphs: Insights from ab initio calculations

    Yi, Yoo Soo; Lee, Sung Keun


    Despite its fundamental importance in condensed matter physics and geophysical implications, establishing the systematic and direct link between the pressure-induced structural changes in crystalline and noncrystalline low-z oxides and their corresponding evolution in O K -edge core-electron excitation features under extreme compression has been challenging. Here we calculated the site-resolved partial density of states and O K -edge x-ray Raman scattering (XRS) spectra for two of the important oxide phases in the Earth's lower mantle, MgSi O3 bridgmanite and post-bridgmanite, up to 120 GPa using ab initio calculations, revealing the electronic origins of the O K -edge features for oxides under compression. The absorption threshold (EA) and band gap increase linearly with a decrease in the O-O distance in diverse Si O2 and MgSi O3 high-pressure phases [EA(eV ) ≈-10.9 dO-O(Å ) +34.4 ] , providing a predictive relationship between the EA and the O-O distances in the oxide at high pressure. Despite densification, upon isobaric phase transition from bridgmanite to post-bridgmanite at 120 GPa, a decrease in band gap results in a decrease in edge energy because of an increase in O-O distance. The oxygen proximity is a useful structural proxy of oxide densification upon compression, as it explains the pressure-induced changes in O K -edge XRS features of crystalline and amorphous Si O2 and MgSi O3 at high pressures. These results can be applied to studies of the pressure-bonding transitions in a wide range of oxides under extreme compression.

  20. Space group and hydrogen positions of single crystal delta-AlOOH, (Al0.84Mg0.07Si0.09)H0.98O2 and its relation to stishovite and brucite

    Kudoh, Y.; Kuribayashi, T.; Suzuki, A.; Ohtani, E.; Kamada, T.


    A single crystal of δ-AlOOH synthesized by Suzuki et al. (2000) at conditions of 1000^oC and 21 GPa was used in this study. A set of X-ray diffraction intensities up to sinθ/λ=0.80 Å-1 were measured with a single crystal of 83×35×24 μm using MoKα radiation (50 kV, 40 mA). Al:Mg:Si ratio 0.84:0.07:0.09 measured by EDS with the same crystal used in the X-ray diffraction intensity measurement yielded the chemical formula (Al0.84Mg0.07Si0.09)H0.98O_2. Suzuki et al. (2000) reported the space group P2_1nm from powder X-ray data but the systematic absence of reflections observed in this study indicated another space group Pnn2. The systematic absence of reflections observed in the present work were h+l odd for h0l and k+l odd for 0kl, indicating possible space group Pnn2 or Pnnm. The N(Z) test for a center of symmetry indicated an acentric space group. The non-centrosymmetric space group Pnn2 was therefore employed and was confirmed by the structural refinement. The agreement factors for 109 independent reflections (Io>= 3.0σ Io) were R=3.6% with anisotropic temperature factors. The difference Fourier synthesis was calculated and two significant Fourier peaks H1 and H2 for the possible hydrogen sites were found. The H1 site locates around two-fold rotation axis with H1-H1 distance of 0.55 Å. The H1 site is considered to be for symmetrical statistical distribution of hydrogen atoms. The H2-H2 are separated with H2-H2 distance 2.12 Å which is larger than the sum of van der Waals radii of hydrogen atoms. The partial occupancy of Mg and Si atoms at Al site suggests the possibility of limited solid solution among δ-AlOOH, stishovite SiO_2 and hypothetical rutile-structured Mg(OH)_2. The H1 site is considered to be for AlOOH and the H_2 site for Mg(OH)_2.

  1. Cristalización de Cordierita en vidrios derivados del sistema cuaternario CaO-MgO-Al2O3-SiO2. Influencia de la composición del vidrio

    Alarcón, J.


    Full Text Available It has been studied the calcium effect on the crystallization of cordierite for obtaining a glassceramic material into the CaOáMgOáAl2O3áSiO2 quaternary system. With this propose it has been selected six compositions into de cordierite primary field of crystallization and obtained the original glasses. The obtained samples have been analysed after a thermal treatment in three steps (glass transformation, nucleation and growth by X-ray diffraction (XRD. The composition of phases in microstructures have been analysed by scanning electron microscopy (SEM. The microstructures have been related with the crystalline phases by energy dispersive X-ray microanalysis (EDX. The amount of CaO in glasses is directly related with the anorthite crystallization, suggesting that the great amount of crystallized anorthite in relation with the low amount of CaO in the original glasses is due to the formation of one anorthite-diopside solid solution, what was tested by EDX. At growth temperature almost every samples partly crystallized, as primary or secondary cordierite phase. The anorthite microstructure was very particulated in spherulites forms of radius near to 250 nm, while the cordierite phase showed different morphologies, from almost-spherulitic crystallization nucleus ("rosettes" of μ-cordierite for direct crystallization from glass, to dense dendrites coming from μ transformation. Finally it can be found homogeneous blocks of α-cordierite with dimension of 10 x 10 μm2.Se ha estudiado el efecto del calcio en la cristalización de cordierita para la obtención de un material vitrocerámico dentro del sistema cuaternario CaO-MgO-Al2O3-SiO2. Con este objetivo se han seleccionado seis composiciones dentro del campo primario de cristalización de la cordierita y se han obtenido por fusión sus correspondientes vidrios. Se han analizado las muestras obtenidas tras un tratamiento térmico en tres etapas (transformación vítrea, nucleación y crecimiento

  2. Cosmetic wastewater treatment using the Fenton, Photo-Fenton and H2O2/UV processes.

    Marcinowski, Piotr P; Bogacki, Jan P; Naumczyk, Jeremi H


    Advanced Oxidation Processes (AOPs), such as the Fenton, photo-Fenton and H2O2/UV processes, have been investigated for the treatment of cosmetic wastewaters that were previously coagulated by FeCl3. The Photo-Fenton process at pH 3.0 with 1000/100 mg L(-1) H2O2/Fe(2+) was the most effective (74.0% Chemical Oxygen Demand (COD) removal). The Fenton process with 1200/500 mg L(-1) H2O2/Fe(2+) achieved a COD removal of 72.0%, and the H2O2/UV process achieved a COD removal of 47.0%. Spreading the H2O2 doses over time to obtain optimal conditions did not improve COD removal. The kinetics of the Fenton and photo-Fenton processes may be described by the following equation: d[COD]/dt = -a[COD] t(m) (t represents time and a and m are constants). The rate of COD removal by the H2O2/UV process may be described by a second-order reaction equation. Head Space, Solid-Phase MicroExtraction, Gas Chromatography and Mass Spectrometry (HS-SPME-GC-MS) were used to identify 48 substances in precoagulated wastewater. Among these substances, 26 were fragrances. Under optimal AOP conditions, over 99% of the identified substances were removed in 120 min.

  3. [Kinetics and Reactive Species Analysis of Dimetridazole Degradation by TiO2].

    Chen, Dong-mei; Yu, Ze-bin; Sun, Lei; Huang, Jun; Gao, Li-hong; Li, Ming-jie


    Dimetridazole is considered as an emerging pollutant in waterbodies, which can potentially impact ecosystem and human health. Heterogeneous photocatalytic decomposition of dimetridazole by TiO2 was investigated under 365 nm UV light and effects of initial pH, TiO2 content and dimetridazole concentration on photocatalytic process were discussed. The results indicated that the optimized experiment condition is that the TiO2 content of 1 g x L(-1), dimetridazole concentration of 40 mg x L (-1), pH of 11, dimetridazole can be removed 90%. The photocatalytic degradation kinetics of dimetridazole could be fitted to the quasi-first-order equation. Photocatalytic degradation of dimetridazole can take place via two pathways: oxidation by *OH and reduction by e -.

  4. A comparison of electrodeposited Ti/β-PbO2 and Ti-Pt/β-PbO2 anodes in the electrochemical degradation of the direct yellow 86 dye

    José M. Aquino


    Full Text Available The electrochemical performance of electrodeposited Ti/β-PbO2 and Ti-Pt/β-PbO2 anodes was galvanostatically evaluated (batch mode, 50 mA cm-2 to degrade the Direct Yellow 86 dye (100 or 200 mg L-1 in 0.1 mol L-1 Na2SO4 + 1.5 g L-1 NaCl, investigating the effect of pH and temperature. Similar results were obtained for both electrodes and the best conditions for removal of color and chemical oxygen demand are pH 7 and 40 °C, when 90% decolorization is attained by passing a charge of only ~0.13 A h L-1 and total mineralization is achieved with expenditure of ~5 kW h m-3.

  5. Fe掺杂PTFE-PbO2/TiO2-NTs/Ti电极的制备、表征及电催化性能%Preparation, characterization and electro-catalytic properties of Fe doped PTFE-PbO2/TiO2-NTs/Ti

    缪虹; 孙亚兵; 冯景伟; 王瑾瑜; 徐建华


    采用电沉积法制备了Fe掺杂PTFE-PbO2/TiO2-NTs/Ti、PbO2/TiO2-NTs/Ti、PbO2/Ti 3种电极,运用扫描电镜、X射线衍射仪观察表面形貌与形态,通过线性扫描伏安法在0.1 mol·L-1的H2SO4中测定电极的析氧极化曲线.以对硝基酚(p-NP)为目标污染物,考察了电极的电催化活性,在20电流密度下降解100 mg·L-1 p-NP,120 min时表观速率常数分别为0.0370 min-1、0.0265 min-1和0.0180 min-1,COD去除率分别为77.38%、74.07%、66.18%,研究发现在相同的条件下Fe掺杂PTFE-PbO2/TiO2-NTs/Ti性能更佳,矿化更完全.%Fe-doped PTFE-PbO2/TiO2-NTs/Ti, PbO2/TiO2-NTs/Ti and PbO2/Ti were prepared by anodic electrodeposition technique. The microstructure and morphology were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). Polarization curves of oxygen evolution of the three electrodes were studied by linear sweep voltammetry in 0. 1 mol-L-1 H2 SO4 aqueous solution. The electro-catalysis of the fabricated electrodes was also investigated using p-nitrophenol (p-NP) as a model pollutant, p-Nitrophenol with 100 mg" L-1 concentration was treated under the current density of 20 mA . cm-2 for 120 min. The apparent rate constant was 0. 0370 min-1 , 0. 0265 min-1 and 0. 0180 min -1 , COD removal efficiency was 77.38% ,74. 07% and 66.18%, respectively. Compared with the other two electrodes, the Fe-doped PTFE- PbO2/TiOE-NTs/Ti had a better performance and the mineralization was greater.

  6. Sonocatalytic degradation of ciprofloxacin using synthesized TiO2 nanoparticles on montmorillonite.

    Hassani, Aydin; Khataee, Alireza; Karaca, Semra; Karaca, Canan; Gholami, Peyman


    TiO2/Montmorillonite (TiO2/MMT) nanocomposite as sonocatalyst was produced by immobilizing synthesized TiO2 on the surface of montmorillonite. The characteristics of produced nanocomposite were investigated using XRD, XRF, FTIR, TEM, SEM, EDX, UV-vis DRS and nitrogen adsorption-desorption analyses. The synthesized TiO2 and TiO2/MMT samples were applied as catalysts for sonocatalytic degradation of ciprofloxacin (CIP). The performance of the TiO2/MMT was greater than pure TiO2 sample in treatment of CIP solution. The degradation efficiency of the CIP by sonocatalytic process was affected by solution pH, catalyst dosage, initial CIP concentrations and ultrasonic power. Degradation efficiency of 65.01% was obtained at the pH of 6, catalyst dosage of 0.2gL(-1), initial CIP concentration of 10mgL(-1) and ultrasonic power of 650WL(-1). It was observed that the presence of inorganic and organic scavengers suppressed the performance of sonocatalytic process. The stability of the nanocomposite was studied in several successive experiments, and the degradation efficiency declined only 61.48% after 4 repeated experiments. The main degradation by-products were recognized by GC-MS method to propose the possible sonocatalytic mechanism for the degradation of CIP. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Active MgO-SiO2 hybrid material for organic dye removal: A mechanism and interaction study of the adsorption of C.I. Acid Blue 29 and C.I. Basic Blue 9.

    Ciesielczyk, Filip; Bartczak, Przemysław; Zdarta, Jakub; Jesionowski, Teofil


    A comparative analysis was performed concerning the removal of two different organic dyes from model aqueous solution using an inorganic oxide adsorbent. The key element of the study concerns evaluation of the influence of the dyes' structure and their acid-base character on the efficiency of the adsorption process. The selection of sorbent material for this research - an MgO-SiO2 oxide system synthesized via a modified sol-gel route - is also not without significance. The relatively high porous structure parameters of this material (ABET = 642 m(2)/g, Vp = 1.11 mL and Sp = 9.8 nm) are a result of the proposed methodology for its synthesis. Both organic dyes (C.I. Acid Blue 29 and C.I. Basic Blue 9) were subjected to typical batch adsorption tests, including investigation of such process parameters as time, initial adsorbate concentration, adsorbent dose, pH and temperature. An attempt was also made to estimate the sorption capacity of the oxide material with respect to the analyzed organic dyes. To achieve the objectives of the research - determine the efficiency of adsorption - it was important to perform a thorough physicochemical analysis of the adsorbents (e.g. FTIR, elemental analysis and porous structure parameters). The results confirmed the significantly higher affinity of the basic dye to the oxide adsorbents compared with the acidic dye. The regeneration tests, which indirectly determine the nature of the adsorbent/adsorbate interactions, provide further evidence for this finding. On this basis, a probable mechanism of dyes adsorption on the MgO-SiO2 oxide adsorbent was proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Histopathological effects following short-term coexposure of Cyprinus carpio to nanoparticles of TiO2 and CuO.

    Mansouri, Borhan; Maleki, Afshin; Davari, Behroz; Johari, Seyed Ali; Shahmoradi, Behzad; Mohammadi, Ebrahim; Shahsavari, Siros


    The aim of this research was to investigate the coexposure of nanoparticles of titanium dioxide (TiO2) and copper oxide (CuO) on the alterations of the gill, intestine, kidney, and liver tissues of carps (Cyprinus carpio). In this study, carps (length 23 ± 1.5 cm; weight 13 ± 1.3 g) were divided into six groups of 15 each and exposed to 2.5 and 5.0 mg L(-1) of CuO nanoparticles (NPs), 10.0 mg L(-1) of TiO2 NPs, and 2.5 and 5.0 mg L(-1) of CuO NPs + 10.0 mg L(-1) of TiO2 NP mixture. Fish were sampled for histopathological studies after hematoxylin-eosin staining. Results indicated that the more kinds of histopathology anomalies observed with CuO NP and TiO2 NP mixture were broadly of the same type as CuO NPs and TiO2 NPs alone, but the severity or incidence of injuries of gill, intestine, liver, and kidney of carps in the mixture of CuO NPs + TiO2 NPs was higher than that of each NP alone. Moreover, behavioral changes in carps exposed to CuO NP and TiO2 NP mixture such as hyperactivity, loss of balance, and convulsions were higher than those to CuO NPs and TiO2 NPs alone. In conclusion, the presence of TiO2 NPs enhanced the effects of NPs of copper oxide in terms of histopathological changes in carps.

  9. Effects of M2+ (M = Ca, Sr, and Ba Addition on Crystallization and Microstructure of SiO2-MgO-Al2O3-B2O3-K2O-F Glass

    Mrinmoy Garai


    Full Text Available In understanding the effect of K+ substitution by M2+ (M = Ca, Sr, and Ba on crystallization and microstructural properties of boroaluminosilicate glass system, the SiO2-MgO-Al2O3-B2O3-MgF2-K2O-Li2O-AlPO4 glasses were prepared by single-step melt-quenching at 1500°C. Density of base glass (2.64 g·cm−3 is found to be decreased in presence of CaO and SrO. Tg is increased by 5–10°C and Td decreased by 13–20°C on addition of M2+. The variation of Tg, Td and decrease of thermal expansion (CTE from 7.55 to 6.67–6.97 (×10−6/K, at 50–500°C in substituting K+ by M2+ are attributed to the higher field-strength of Ca2+, Sr2+, and Ba2+. Opaque mica glass-ceramics were derived from the transparent boroaluminosilicate glasses by controlled heat treatment at 1050°C (duration = 4 h; and the predominant crystalline phase was identified as fluorophlogopite (KMg3AlSi3O10F2 by XRD and FTIR study. Glass-ceramic microstructure reveals that the platelike mica flake crystals predominate in presence of K2O and CaO but restructured to smaller droplet like spherical shaped mica on addition of SrO and BaO. Wide range of CTE values (9.54–13.38 × 10−6/K at 50–800°C are obtained for such glass-ceramics. Having higher CTE value after crystallization, the CaO containing SiO2-MgO-Al2O3-B2O3-MgF2-K2O-Li2O-AlPO4 glass can be useful as SOFC sealing material.

  10. Effect of B2O3 on Crystallization Behavior, Structure, and Heat Transfer of CaO-SiO2-B2O3-Na2O-TiO2-Al2O3-MgO-Li2O Mold Fluxes

    Yang, Jian; Zhang, Jianqiang; Sasaki, Yasushi; Ostrovski, Oleg; Zhang, Chen; Cai, Dexiang; Kashiwaya, Yoshiaki


    The effect of B2O3 on crystallization behavior, structure, and heat transfer of CaO-SiO2-Na2O-B2O3-TiO2-Al2O3-MgO-Li2O fluorine-free mold fluxes was investigated using hot thermocouple technique (HTT), Raman spectroscopy, and infrared emitter technique (IET), respectively. The critical cooling rate in continuous cooling experiments decreased and the incubation time determined in isothermal experiments increased with increasing B2O3 content, both implying a decreasing crystallization tendency. The major phases of mold fluxes determined using X-ray diffraction changed from Ca2MgSi2O7 and Ca11Si4B2O22 to CaSiO3 with the increasing amount of B2O3. B2O3 increased the degree of polymerization in silicate network, forming 3D borate structures. Addition of B2O3 decreased the flux melting temperature which has a significant impeding effect on the crystal nucleation and growth. The heat flux of mold fluxes measured using IET showed that the increase of B2O3 from 4.7 to 6.8 mass pct impeded the heat flux; while a further increase of B2O3 from 6.8 to 10.4 mass pct promoted the heat transfer. This phenomenon was attributed to the variation of crystallization behavior and crystal morphology with different B2O3 content in the mold fluxes.

  11. Arsenic removal from water employing heterogeneous photocatalysis with TiO2 immobilized in PET bottles.

    Fostier, Anne Hélène; Pereira, Maria do Socorro Silva; Rath, Susanne; Guimarães, José Roberto


    Arsenic oxidation (As(III) to As(V)) and As(V) removal from water were assessed by using TiO2 immobilized in PET (polyethylene terephthalate) bottles in the presence of natural sunlight and iron salts. The effect of many parameters was sequentially studied: TiO2 concentration of the coating solution, Fe(II) concentration, pH, solar irradiation time; dissolved organic carbon concentration. The final conditions (TiO2 concentration of the coating solution: 10%; Fe(II): 7.0 mg l(-1); solar exposure time: 120 min) were applied to natural water samples spiked with 500 microg l(-1) As(III) in order to verify the influence of natural water matrix. After treatment, As(III) and total As concentrations were lower than the limit of quantitation (2 microg l(-1)) of the voltammetric method used, showing a removal over 99%, and giving evidence that As(III) was effectively oxidized to As(V). The results obtained demonstrated that TiO2 can be easily immobilized on a PET surface in order to perform As(III) oxidation in water and that this TiO2 immobilization, combined with coprecipitation of arsenic on Fe(III) hydroxides(oxides) could be an efficient way for inorganic arsenic removal from groundwaters.

  12. Structure and Electrical Conductivity of Compositely Doped Oxide Solid Electrolyte La0.8Sr0.2Ga0.8Mg0.12Co0.08O2.8

    Ma Xu; Zhao Jie; Wang Zhiqi; Bao Juncheng; Li Jianping; Sun Jiashu


    (La, Sr) (Ga, Mg) O3-δ, (LSGM) perovskite compositions doped with transition metal Co on the B-site were prepared by solid state reaction. The effect of partial substitution of Ga for Co, La0.8Sr0.2Ga0.8Mg0.12Co0.08O2.8 (LSGMC2008) on the electrical conductivity was discussed. The results showed the compacted samples sintered at 1350℃ possesses increased electrical conductivity at low temperatures. The XRD patterns of the title materials indicated that LSGMC2008 possessed orthorhombic perovskite-type structure. The grains distributed relatively uniform from SEM photo. The Arrhenius plots of ionic conductivity in air of the LSGMC2008 exhibited differing slopes in the low-and high-temperature regions, and the corresponding Ea values were much lower than that of LSGM2020. All of these suggested that even at low sintering temperature, proper amount Co doped was beneficial to improve ionic conductivity of LSGM.

  13. Study of a Mixed Alkaline–Earth Effect on Some Properties of Glasses of the CaO-MgO-Al2O3-SiO2 System

    Valle-Fuentes, J. F.


    Full Text Available In the present work, we studied a “Mixed Alkaline–Earth Effect”, i.e. the non-linear behaviour showed by the glass transition temperature as well as by the compressive strength of glasses of the CaO-MgO-Al2O3-SiO2 system, when a part of the CaO contained in them was substituted by a BaO/SrO mixture, in variable molar proportions. An important factor for the occurrence of this phenomenon was the difference in atomic weight, ionic radii and field strength of the Ba2+ and Sr2+ ions in comparison with those corresponding to the Ca2+ ion. Another factor considered was the likely occurrence of a microphase separation caused by the addition of BaO and/or SrO, together with the presence of F- and Mg2+ in the glasses. Other glass properties studied as a function of the CaO substitution level were density, glass molar volume, oxygen molar volume, packing fraction, and chemical resistance in neutral, basic and acidic aqueous media. In general, the structural reinforcement of the glass network caused by the partial substitution of CaO by a BaO/SrO mixture was accompanied by an improvement in the alkaline resistance of the materials, which were found to be suitable for applications in corrosive environments, especially in basic media. Keywords: Mixed alkaline–earth effect; CaO-MgO-Al2O3-SiO2 system; glass properties.En el presente trabajo, se estudia el comportamiento no lineal mostrado por la temperatura de transición vítrea y por la resistencia a la compresión de vidrios del sistema CaO-MgO-Al2O3-SiO2, cuando una parte del CaO contenido en los mismos es sustituido por una mezcla de BaO/SrO, en relación molar variable. Factores importantes para que se de este comportamiento son la diferencia entre pesos atómicos, radios iónicos e intensidad de campo de los iones Ba2+ y Sr2+ y los del propio ión Ca2+. Otro factor considerado ha sido la probable existencia de una separación de microfases originada por la adición de BaO y/o SrO, junto con la

  14. Effects and implications of trophic transfer and accumulation of CeO2 nanoparticles in a marine mussel.

    Conway, Jon R; Hanna, Shannon K; Lenihan, Hunter S; Keller, Arturo A


    Bivalves are hypothesized to be key organisms in the fate and transport of engineered nanomaterials (ENMs) in aquatic environments due to their ability to filter and concentrate particles from water, but how different exposure pathways influence their interactions with ENMs is not well understood. In a five-week experiment, we tested how interactions between CeO2 ENMs and a marine mussel, Mytilus galloprovincialis, are affected through two exposure methods, direct and through sorption to phytoplankton. We found that phytoplankton sorbed ENMs in CeO2 was captured and excreted in pseudofeces and average pseudofeces mass doubled in response to CeO2 exposure. Final mean dry tissue Ce concentration (±SE) for treatments exposed to 3 mg L(-1) CeO2 directly was 33 ± 9 μg g(-1) Ce, and 0 ± 0, 19 ± 4, 21 ± 3, and 28 ± 5 μg g(-1) for treatments exposed to 0, 1, 2, and 3 mg L(-1) CeO2 sorbed to phytoplankton. Clearance rates increased with CeO2 concentration but decreased over time in groups exposed to CeO2 directly, indicating stress. These results show the feedback between ENM toxicity and transport and the likelihood of biological mediation in the fate and transport of ENMs in aquatic environments.

  15. [Removal of triclosan with the method of UV/ClO2 and its degradation products].

    Li, Yu-Ying; He, Wen-Long; Li, Qing-Song; Jin, Wei-Wei; Chen, Guo-Yuan; Li, Guo-Xin


    The UV/ClO2 process for triclosan ( TCS) removal was studied. The influences of several factors such as the initial pH, dose of ClO2, initial concentration of TCS and humic acid( HA) on TCS degradation in the UV/ClO2 combined process were discussed. The results showed that the UV/ClO2 process could effectively remove TCS and had a synergistic effect. When the light intensity was 6.5 μW x Cm(-2), the dose of ClO2 was 0. 5 mg x L(-1) and the concentration of TCS was 300 μg x L(-1), when UV and ClO2 were applied alone, the TCS removal rates within 1 min were only 5.23% and 84.93% respectively. The removal rate reached up to 99.13% after 1 min degradation using the UV/ClO2 combined process. In test conditions ( pH 6-9), the removal rate increased from 99.4% to 99. 63% with the increase of pH. Increasing dose of CIO2 could promote TCS removal. When the dose of ClO2 was 0.5-1.5 mg x L(-1), the removal rate was increased from 98.1% to 99.89%. The initial concentration of TCS was negatively correlated with the removal rate. When the initial concentration increased from 100 - 500 μg x L(-1), the removal rate of TCS was decreased from 99.98% to 94.39%. Low concentration of humic acid was beneficial to the removal of TCS, and high concentration of it had the opposite effect. Degradation products of TCS were investigated by GC/MS. Degradation of TCS by the processes of UV, ClO2 and UV/ClO2 also indicated that the main degradation products of the TCS were 2, 4-dichlorophenol (2,4-DCP), 2,7-dichlorodibenzo-p-dioxin (2,7-DCDD), etc.

  16. Long-term exposure of bacterial and protozoan communities to TiO2 nanoparticles in an aerobic-sequencing batch reactor

    Supha, Chitpisud; Boonto, Yuphada; Jindakaraked, Manee; Ananpattarachai, Jirapat; Kajitvichyanukul, Puangrat


    Titanium dioxide (TiO2) nanopowders at different concentrations (0-50 mg L-1) were injected into an aerobic-sequencing batch reactor (SBR) to investigate the effects of long-term exposure to nanoparticles on bacterial and protozoan communities. The detection of nanoparticles in the bioflocs was analyzed by scanning electron microscopy, transmission electron microscopy, and energy-dispersive x-ray spectroscopy. The SBR wastewater experiments were conducted under the influence of ultraviolet light with photocatalytic TiO2. The intrusion of TiO2 nanoparticles was found both on the surface and inside of the bioflocs. The change of microbial population in terms of mixed liquor-suspended solids and the sludge volume index was monitored. The TiO2 nanoparticles tentatively exerted an adverse effect on the microbial population, causing the reduction of microorganisms (both bacteria and protozoa) in the SBR. The respiration inhibition rate of the bacteria was increased, and the viability of the microbial population was reduced at the high concentration (50 mg L-1) of TiO2. The decreasing number of protozoa in the presence of TiO2 nanoparticles during 20 days of treatment with 0.5 and 1.0 mg L-1 TiO2 is clearly demonstrated. The measured chemical oxygen demand (COD) in the effluent tends to increase with a long-term operation. The increase of COD in the system suggests a decrease in the efficiency of the wastewater treatment plant. However, the SBR can effectively remove the TiO2 nanoparticles (up to 50 mg L-1) from the effluent.

  17. Orientation of FePt nanoparticles on top of a-SiO2/Si(001), MgO(001) and sapphire(0001): effect of thermal treatments and influence of substrate and particle size.

    Schilling, Martin; Ziemann, Paul; Zhang, Zaoli; Biskupek, Johannes; Kaiser, Ute; Wiedwald, Ulf


    Texture formation and epitaxy of thin metal films and oriented growth of nanoparticles (NPs) on single crystal supports are of general interest for improved physical and chemical properties especially of anisotropic materials. In the case of FePt, the main focus lies on its highly anisotropic magnetic behavior and its catalytic activity, both due to the chemically ordered face-centered tetragonal (fct) L10 phase. If the c-axis of the tetragonal system can be aligned normal to the substrate plane, perpendicular magnetic recording could be achieved. Here, we study the orientation of FePt NPs and films on a-SiO2/Si(001), i.e., Si(001) with an amorphous (a-) native oxide layer on top, on MgO(001), and on sapphire(0001) substrates. For the NPs of an approximately equiatomic composition, two different sizes were chosen: "small" NPs with diameters in the range of 2-3 nm and "large" ones in the range of 5-8 nm. The 3 nm thick FePt films, deposited by pulsed laser deposition (PLD), served as reference samples. The structural properties were probed in situ, particularly texture formation and epitaxy of the specimens by reflection high-energy electron diffraction (RHEED) and, in case of 3 nm nanoparticles, additionally by high-resolution transmission electron microscopy (HRTEM) after different annealing steps between 200 and 650 °C. The L10 phase is obtained at annealing temperatures above 550 °C for films and 600 °C for nanoparticles in accordance with previous reports. On the amorphous surface of a-SiO2/Si substrates we find no preferential orientation neither for FePt films nor nanoparticles even after annealing at 630 °C. On sapphire(0001) supports, however, FePt nanoparticles exhibit a clearly preferred (111) orientation even in the as-prepared state, which can be slightly improved by annealing at 600-650 °C. This improvement depends on the size of NPs: Only the smaller NPs approach a fully developed (111) orientation. On top of MgO(001) the effect of annealing on

  18. Effective photocatalytic decolorization of indigo carmine dye in Moroccan natural phosphate-TiO2 aqueous suspensions

    Naciri, Nouâma; Farahi, Abdelfettah; Rafqah, Salah; Nasrellah, Hamid; El Mhammedi, Moulay Abderrahim; Lançar, IbnToumaret; Bakasse, Mina


    Heterogeneous photocatalysis is a significant green technology for application in water purification. In this study, the photocatalytic activity of NP-TiO2 based on Moroccan natural phosphate (NP) doped by titanium dioxide TiO2 was evaluated by photocatalytic decolorization of indigo carmine (IC) dye in aqueous solution as a model pollutant under UV light. The NP-TiO2 catalyst was characterized by XRD, FTIR and surface area. The effect of the calcination temperature of NP-TiO2, catalyst concentration, initial concentration of the IC, initial pH, initial hydrogen peroxide H2O2 concentration and coexisting ions on the photocatalytic decolorization of IC was investigated. The NP-TiO2 showed a significantly higher rate of degradation of IC, when compared to TiO2. After 125 min of irradiation using a low intensity of UV-lamp (15 W ∗ 3 lamps = 45 W), 99% of IC solution (20 mg L-1) was decolorized with 0.5 g L-1 of the NP-TiO2 calcined at 600 °C at pH = 11. Therefore, this process can be developed as an economically feasible and environmentally friendly method to decolorize or treat dye wastewater using sunlight.

  19. Degradation of 4-nitrophenol (4-NP) using Fe-TiO2 as a heterogeneous photo-Fenton catalyst.

    Zhao, Binxia; Mele, Giuseppe; Pio, Iolanda; Li, Jun; Palmisano, Leonardo; Vasapollo, Giuseppe


    Photocatalytic degradation of 4-nitrophenol was investigated using Fe-doped (1, 3, 5 and 8 wt.% Fe) TiO(2) catalysts under UV light irradiation in aqueous dispersions in the presence of H(2)O(2). Photocatalysts with the lowest Fe content (1%) showed a considerably better behavior with respect to the unloaded TiO(2) and the catalysts with higher Fe contents. Photocatalytic degradation was studied under different conditions such as amounts of 1% Fe-TiO(2) catalyst, H(2)O(2) dose and initial pH of 4-NP solution. The results indicated that about 67.53% total organic carbon of a solution containing 20 mg L(-1) 4-NP was removed at pH 6.17 by using 4.9 mM of H(2)O(2) and 0.4 g L(-1) of the catalyst in a 2-L batch photo-reactor, the complete degradation of 4-NP occurring after 60 min. It was also observed that catalytic behavior could be reproduced in consecutive experiments without a considerable decrease of the UV/Fe-TiO(2)/H(2)O(2) process efficiency. 2009 Elsevier B.V. All rights reserved.

  20. Dramatic enhancement of solar disinfection (SODIS) of wild Salmonella sp. in PET bottles by H2O2 addition on natural water of Burkina Faso containing dissolved iron.

    Sciacca, Frédéric; Rengifo-Herrera, Juliàn A; Wéthé, Joseph; Pulgarin, César


    Disinfection of surface water containing dissolved iron (0.3 mg L(-1)) at natural neutral pH ( approximately 7.5) was carried out via solar disinfection (SODIS) treatment in PET bottles with H(2)O(2) (10 mg L(-1)). Wild coliforms and Salmonella sp. were monitored for 6 h of sunlight irradiation and 72 h of dark post-treatment period. In our conditions, SODIS treatment could not avoid Salmonella sp. re-growth during dark storage, meanwhile the addition of 10 mg L(-1) of H(2)O(2) showed a strong enhancement of the inactivation rate without any re-growth of both bacteria. Finally, total coliforms (Escherichia coli included) demonstrated to be an inappropriate indicator for monitoring bacterial contamination in water during solar disinfection processes.

  1. Superiority of solar Fenton oxidation over TiO2 photocatalysis for the degradation of trimethoprim in secondary treated effluents.

    Michael, I; Hapeshi, E; Michael, C; Fatta-Kassinos, D


    The overall aim of this work was to examine the degradation of trimethoprim (TMP), which is an antibacterial agent, during the application of two advanced oxidation process (AOP) systems in secondary treated domestic effluents. The homogeneous solar Fenton process (hv/Fe(2+)/H2O2) and heterogeneous photocatalysis with titanium dioxide (TiO2) suspensions were tested. It was found that the degradation of TMP depends on several parameters such as the amount of iron salt and H2O2, concentration of TiO2, pH of solution, solar irradiation, temperature and initial substrate concentration. The optimum dosages of Fe(2+) and H2O2 for homogeneous ([Fe(2+)] = 5 mg L(-1), [H2O2] = 3.062 mmol L(-1)) and TiO2 ([TiO2] = 3 g L(-1)) for heterogeneous photocatalysis were established. The study indicated that the degradation of TMP during the solar Fenton process is described by a pseudo-first-order reaction and the substrate degradation during the heterogeneous photocatalysis by the Langmuir-Hinshelwood kinetics. The toxicity of the treated samples was evaluated using a Daphnia magna bioassay and was finally decreased by both processes. The results indicated that solar Fenton is more effective than the solar TiO2 process, yielding complete degradation of the examined substrate within 30 min of illumination and dissolved organic carbon (DOC) reduction of about 44% whereas the respective values for the TiO2 process were ∼70% degradation of TMP within 120 min of treatment and 13% DOC removal.

  2. 硅藻土基纳米TiO2降解甲醛的实验研究%Experimental study on the formaldehyde degradation by nano,TiO2 immobilized on diatomite

    俞成林; 权红恩; 康勇


    The characteristics of the diatomite powder and the nano-TiO2 immobilized on diatomite for formaldehyde adsorption were compared. The formaldehyde degradation of the nano-TiO2 immobilized on diatomite by the dosage of 62.5 g·m -2 was studied under the condition of varying original formaldehyde concentration, reaction temperature, light intensity and relative atmosphere humidity in the reactor, The results showed that the diatomite powder can only adsorb formaldehyde but the nano-TiO2 immobilized on diatomite can adsorb and degrade formaldehyde continuously. The degradation time was long for high formaldehyde original concentration. The degradation time of formaldehyde with original concentration of 6.0 × 10 -3 mg·L^-1 were 150 h, whereas only 14 h and 32 h for the original concentration of 2.0 × 10- 3 mg-L^-1 and 4.0 ×10 ^-3 mg·L^-1 respectively when the degradation ratio above 99%. The higher reaction temperature was, the shorter time of degrading formaldehyde. 50 h was needed for the complete photocatalyst oxidation of formaldehyde with original concentration 2.0 × 10 -3 mg· L-1 under reaction temperature 15 ℃, but only 12 h under 45 ℃. Light was the key driving power of the nano-TiO2 immobilized on diatomite degrading formaldehyde. The degradation time of formaldehyde of 2.0× 10-3 mg. L-1 was 14 h when the light intensity was 8100 Ix, but formaldehyde could hardly be degraded when the light intensity was 0 lm m -2. The rate of formaldehyde degradation by the photocatalyst was also enhanced by the relative humidity in the reactor. The formaldehyde degradation time from 2.0 × 10 - 3 mg. L- 1 to 3.72× 10 -5 mg.L-1 was 14 h under the relative humidity of 50% , but to 1.0 × 10 -5 mg.L-1 under the relative humidity of 80%.%对比研究了硅藻土和硅藻土基纳米二氧化钛光催化剂对甲醛的吸附降解特点.通过改变反应器内甲醛的初始浓度、反应温度、光照强度和相对湿度,研究了涂覆量为62.5g·m-2的硅藻土基纳米TiO

  3. Synthesis of pure powder of La0.9Sr0.1Ga0.8Mg0.2O2.825 by microwave-induced solution combustion method

    翟玉玲; 叶畅; 肖建中


    The method of microwave-induced solution combustion was used to prepare the powder of La0.9Sr0.1Ga0.8Mg0.2O2.825(LS0.1GM0.2). For the more homogenous heating manner without thermal gradients in the microwave oven, the homogenous pure powder of LS0.1GM0.2 after calcination at 1 400 ℃ for 9 h was obtained. The calcination behavior of the precursor powder was studied in the temperature range of500 ~ 1 400 ℃. By this method, the desired perovskite phase with little secondary phases was existed before calcination. The grain size of the powder of LS0.1GM0.2 after calcination at 1 400 ℃ for 9 h was about 2 ~ 3 μm.However, the density of the pellet was 5.43 g/cm3, lower than other reports for the mechanism of the combustion method itself.

  4. In vitro mineralization of a glass-ceramic of the MgO-3CaO x P2O5-SiO2 system: wettability studies.

    Serro, A P; Fernandes, A C; Saramago, B; Fernandes, M H V


    The calcium phosphate deposition on the surface of a bioactive glass-ceramic of the MgO-3CaO. P(2)O(5)-SiO(2) system during a 1-week immersion in biological model fluids, was investigated through wettability studies. Two model fluids with chemical composition similar to the human blood plasma were tested: Hanks' balanced salt solution (HBSS) and a simulated body fluid (SBF) with a higher calcium content. The effect of the presence of albumin, both in solution or previously adsorbed to the surface, was assessed. The behavior observed using two SBF solutions prepared with and without TRIS buffer was compared. The surface free energy of the glass-ceramic samples was determined, before and after immersion, and dynamic contact angle analysis was performed using the biological model fluids as scanning liquids. Scanning electron microscope observations and x-ray photoelectron spectroscopy (XPS) analysis were performed to complement the wettability studies. The experimental results led to the conclusion that the precipitation of a calcium phosphate film in HBSS occurred mainly when the immersion solution was renewed daily or in the presence of adsorbed albumin. In SBF, the addition of TRIS buffer seemed to inhibit the formation of the calcium phosphate film.

  5. Compare Removal of Reactive Red195 and Blue19 by Nano TiO2-ZnO

    Z. Pournuroz


    Full Text Available In this study, TiO2-ZnO particles were synthesized by the sol-gel method. XRD, SEM, EDX and UV-vis techniques were used to characterize optimize doped TiO2-ZnO sample Aim of this research is investigation of possibility of mixture TiO2-ZnO in degradation reactive dye. In addition, Influence of effective parameters on photodegradation reaction such as TiO2-ZnO concentration and initial concentration of dyes on the removal were investigated. Results showed that removal efficiency of dyes by increasing of TiO2-ZnO concentration was increased. In addition, the best dye removal for both dyes were obtained 11mg.L-1.


    David Medved


    Full Text Available The interactions of magnesia-chromite refractory brick with Cu-Na2O.2SiO2 and CuO-Na2O.2SiO2 melts are studied and the chemical durability of corrosion products in water is evaluated. The corrosion tests confirm intensive infiltration of the slag melts into the tested refractory bricks and formation of Cr(6+ compounds. The molten copper partially oxidizes during corrosion test by air and penetrates into bricks. Interactions among periclase (MgO and chromite (FeCr2O4 grains with the melt Na2O.2SiO2 and copper oxides makes possible to form several compounds (e.g. Cu2MgO3, CuCrO4, CaCrO4, Na2CrO4, MgCrO4. Just the marked yellow spots, which were observed on the corroded brick surface after 30 days of free storage, suggest hydration of the high-temperature corrosion products. The yellow color of spots points out to chromates as Na2CrO4 and MgCrO4, which are well soluble in water. The leaching of corroded bricks in water (batch leaching test of a ratio of S (solid : W (water = 0.1 taking up to 28 days confirmed the Cr, Na, Mg and Ca ions leach-out. The pH value of solution increased up to 9 during leaching mainly as a consequence of elevated Na+ ion concentration. The Cr ion concentration rises in the solution up to 1 mmol.l-1. The observed moderate decrease of Cr ion concentration in the solution with the length of leaching indicates super-saturation of the solution and precipitation of the products.

  7. Orientation of FePt nanoparticles on top of a-SiO2/Si(001, MgO(001 and sapphire(0001: effect of thermal treatments and influence of substrate and particle size

    Martin Schilling


    Full Text Available Texture formation and epitaxy of thin metal films and oriented growth of nanoparticles (NPs on single crystal supports are of general interest for improved physical and chemical properties especially of anisotropic materials. In the case of FePt, the main focus lies on its highly anisotropic magnetic behavior and its catalytic activity, both due to the chemically ordered face-centered tetragonal (fct L10 phase. If the c-axis of the tetragonal system can be aligned normal to the substrate plane, perpendicular magnetic recording could be achieved. Here, we study the orientation of FePt NPs and films on a-SiO2/Si(001, i.e., Si(001 with an amorphous (a- native oxide layer on top, on MgO(001, and on sapphire(0001 substrates. For the NPs of an approximately equiatomic composition, two different sizes were chosen: “small” NPs with diameters in the range of 2–3 nm and “large” ones in the range of 5–8 nm. The 3 nm thick FePt films, deposited by pulsed laser deposition (PLD, served as reference samples. The structural properties were probed in situ, particularly texture formation and epitaxy of the specimens by reflection high-energy electron diffraction (RHEED and, in case of 3 nm nanoparticles, additionally by high-resolution transmission electron microscopy (HRTEM after different annealing steps between 200 and 650 °C. The L10 phase is obtained at annealing temperatures above 550 °C for films and 600 °C for nanoparticles in accordance with previous reports. On the amorphous surface of a-SiO2/Si substrates we find no preferential orientation neither for FePt films nor nanoparticles even after annealing at 630 °C. On sapphire(0001 supports, however, FePt nanoparticles exhibit a clearly preferred (111 orientation even in the as-prepared state, which can be slightly improved by annealing at 600–650 °C. This improvement depends on the size of NPs: Only the smaller NPs approach a fully developed (111 orientation. On top of MgO(001 the

  8. Remediation of 17-α-ethinylestradiol aqueous solution by photocatalysis and electrochemically-assisted photocatalysis using TiO2 and TiO2/WO3 electrodes irradiated by a solar simulator.

    Oliveira, Haroldo G; Ferreira, Leticia H; Bertazzoli, Rodnei; Longo, Claudia


    TiO2 and TiO2/WO3 electrodes, irradiated by a solar simulator in configurations for heterogeneous photocatalysis (HP) and electrochemically-assisted HP (EHP), were used to remediate aqueous solutions containing 10 mg L(-1) (34 μmol L(-1)) of 17-α-ethinylestradiol (EE2), active component of most oral contraceptives. The photocatalysts consisted of 4.5 μm thick porous films of TiO2 and TiO2/WO3 (molar ratio W/Ti of 12%) deposited on transparent electrodes from aqueous suspensions of TiO2 particles and WO3 precursors, followed by thermal treatment at 450 (°)C. First, an energy diagram was organized with photoelectrochemical and UV-Vis absorption spectroscopy data and revealed that EE2 could be directly oxidized by the photogenerated holes at the semiconductor surfaces, considering the relative HOMO level for EE2 and the semiconductor valence band edges. Also, for the irradiated hybrid photocatalyst, electrons in TiO2 should be transferred to WO3 conduction band, while holes move toward TiO2 valence band, improving charge separation. The remediated EE2 solutions were analyzed by fluorescence, HPLC and total organic carbon measurements. As expected from the energy diagram, both photocatalysts promoted the EE2 oxidation in HP configuration; after 4 h, the EE2 concentration decayed to 6.2 mg L(-1) (35% of EE2 removal) with irradiated TiO2 while TiO2/WO3 electrode resulted in 45% EE2 removal. A higher performance was achieved in EHP systems, when a Pt wire was introduced as a counter-electrode and the photoelectrodes were biased at +0.7 V; then, the EE2 removal corresponded to 48 and 54% for the TiO2 and TiO2/WO3, respectively. The hybrid TiO2/WO3, when compared to TiO2 electrode, exhibited enhanced sunlight harvesting and improved separation of photogenerated charge carriers, resulting in higher performance for removing this contaminant of emerging concern from aqueous solution.

  9. Influence of strontium on structure, sintering and biodegradation behaviour of CaO-MgO-SrO-SiO2-P2O5-CaF2 glasses

    Goel, Ashutosh; Rajagopal, Raghu R.; Ferreira, Jose M.


    The present study investigates the influence of SrO on structure, apatite forming ability, physico-chemical degradation and sintering behaviour of melt-quenched bioactive glasses with composition: mol.% (36.07 – x) CaO – x SrO - 19.24 MgO – 5.61 P2O5 – 38.49 SiO2 – 0.59 CaF2, where x varies between 0 – 10. The detailed structural analysis of glasses has been made by infra red spectroscopy (FTIR) and magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR). Silicon was predominantly present as Q2 (Si) species while phosphorus was found in orthophosphate type environment in all the investigated glasses. The apatite forming ability of glasses was investigated by immersion of glass powders in simulated body fluid (SBF) for time durations varying between 1 h – 7 days. While increasing Sr2+/Ca2+ ratio in glasses did not affect the structure of glasses significantly, their apatite forming ability was decreased considerably. Further, physico-chemical degradation of glasses has been studied in accordance with ISO 10993-14 “Biological evaluation of medical devices – Part 14: Identification and quantification of degradation products from ceramics” in Tris HCl and citric acid buffer and the possible implications of ion release profile from glasses in different solutions has been discussed. The addition of strontium in glasses led to a 7-fold decrease in chemical degradation of glasses in Tris-HCl. The sintering of glass powders rendered glass-ceramics (GCs) with varying degree of crystallinity and good flexural strength (98-131 MPa) where the mechanical properties depend on the nature and amount of crystalline phases present in GCs.

  10. Influence of strontium on structure, sintering and biodegradation behaviour of CaO-MgO-SrO-SiO(2)-P(2)O(5)-CaF(2) glasses.

    Goel, Ashutosh; Rajagopal, Raghu Raman; Ferreira, José M F


    The present study investigates the influence of SrO on structure, apatite-forming ability, physico-chemical degradation and sintering behaviour of melt-quenched bioactive glasses with the composition (mol.%): (36.07 - x) CaO-xSrO-19.24MgO-5.61P(2)O(5)-38.49SiO(2)-0.59CaF(2), where x varies between 0 and 10. The detailed structural analysis of the glasses is made by infrared spectroscopy and magic angle spinning-nuclear magnetic resonance spectroscopy. Silicon is predominantly present as Q(2) (Si) species, while phosphorus is found as orthophosphate in all the investigated glasses. The apatite-forming ability of glasses is investigated by immersion of glass powders in simulated body fluid for time durations varying between 1 h and 7 days. While increasing the Sr(2+)/Ca(2+) ratio in the glasses does not affect their structure significantly, their apatite-forming ability is decreased considerably. Further, physico-chemical degradation of glasses is studied in accordance with ISO 10993-14 "Biological evaluation of medical devices - Part 14: Identification and quantification of degradation products from ceramics" in Tris-HCl and citric acid buffer, and the possible implications of the ion release profiles from the glasses in different solutions are discussed. The addition of strontium to the glasses leads to a sevenfold decrease in chemical degradation of glasses in Tris-HCl. The sintering of glass powders renders glass ceramics (GCs) with varying degrees of crystallinity and good flexural strength (98-131 MPa), where the mechanical properties depend on the nature and amount of crystalline phases present in the GCs. Published by Elsevier Ltd.

  11. Effect of One-methylcyclopropene (1-MCP) and chlorine dioxide (ClO2) on preservation of green walnut fruit and kernel traits.

    Jiang, Liuqing; Feng, Wenyu; Li, Fang; Xu, Jingying; Ma, Yanping; Ma, Huiling


    The effect of the ethylene receptor competitor 1-methylcyclopropene (1-MCP) and the legally approved disinfectant chlorine dioxide (ClO2) on preservation of the green walnut fruit during storage was investigated. Green Chinese walnut fruit cv. Xilin No.2 was harvested on commercial maturity and stored at 0-1 °C after the fruit was treated by water (control), 80 mg L(-1)ClO2 (ClO2), 0.5 μL L(-1)1-MCP (1-MCP), or combination treatment of 80 mg L(-1) ClO2 with either 0.1 μL L(-1) 1-MCP (0.1 1-MCP+ ClO2) or 0.5 μL L(-1) 1-MCP (0.5 1-MCP+ ClO2). During storage, respiration, ethylene production, phenolics content, antioxidative activity, weight changes, decay of the fruit and kernel traits of acid value, peroxide value,free fatty were measured. All treatments decreased postharvest respiration intensity in different degrees and inhibited ethylene production peak. ClO2 increased the total phenol and flavonoid content of the green fruit compared with other treatments and the control (P < 0.05), but not did the total antioxidant activity for this treatment. After 42-day storage, ClO2 remained higher fresh weight and lower decay index than control, while 1-MCP increased the fruit decay index. Final acid values of kernel from ClO2, control and 0.1 1-MCP+ ClO2 were not different from their initial values, which from 0.5 1-MCP increased. Final peroxide value for kernel from ClO2 showed no change during storage but increased at least 1.0-fold for other treatments. ClO2 preserved 99.9 % of initial free fatty acid, similar to that for the control (99.8 %), whereas 0.5 1-MCP preserved only 95.7 %. ClO2 is of potential in decay retardation and kernel traits maintenance of green walnut fruit, whereas the 1-MCP has a negative effect for decay control on walnut.

  12. Advanced oxidation of five contaminants in water by UV/TiO2: Reaction kinetics and byproducts identification.

    Alvarez-Corena, Jose R; Bergendahl, John A; Hart, Fred L


    The extent and kinetics of degradation of 1,4 dioxane, n-nitrosodimethylamine (NDMA), tris-2-chloroethyl phosphate (TCEP), gemfibrozil, and 17β estradiol in a prepared aqueous matrix by means of UV/TiO2 (ultraviolet light/titanium dioxide) oxidation was evaluated. Degussa P25 TiO2 was employed as a photocatalyst excited by UV light in a 1 L water-jacketed batch photoreactor. The rate of degradation was modeled using a pseudo-first order rate model and the Langmuir-Hinshelwood rate model with a high correlation. Degradation rate constants were found to be maximum at pH 5.0 and 1.5 g L(-)(1) TiO2 dose. For these conditions first order rate constants, values were as follows: 0.29 min(-1) for 1,4 dioxane, 0.50 min(-1) for NDMA, 0.12 min(-1) for TCEP, 0.61 min(-1) for gemfibrozil, and 0.53 min(-1) for 17β estradiol. While for the Langmuir-Hinshelwood rate model, the following constants were found: 0.11 Lmg(-1) and 2.81 mgL(-1) min(-1) for 1,4 dioxane, 0.12 Lmg(-1) and 4.35 mgL(-1) min(-1) for NDMA, 0.06 Lmg(-1) and 1.79 mgL(-1) min(-1) for TCEP, 0.21 Lmg(-1) and 3.27 mgL(-1) min(-1) for gemfibrozil, and 0.15 Lmg(-1) and 3.43 mgL(-1) min(-1) for 17β estradiol. In addition, specific byproducts of degradation were identified using GC/MS analysis. The results obtained from the kinetics analysis showed that UV/TiO2 oxidation is a promising process for treating trace organic contaminants in water, but further research is needed to better understand how to incorporate these findings into pilot and full-scale designs. The toxicity of oxidation byproducts, and their potential for interacting with other compounds should be considered in the treatment of contaminated waters using the UV/TiO2 oxidation process.

  13. Sparse Recovery via l1 and L1 Optimization


    Sparse Recovery via `1 and L1 Optimization Stanley Osher and Wotao Yin Department of Mathematics , UCLA and 1...WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) University of California, Los Angeles,Department of Mathematics ,Los Angeles...ϕi, ϕj〉 = δjk, for i, j = 1, . . . , N . We get densely supported ϕj , (think of sines and cosines when V = 0). Physicists and chemists want short

  14. Effect of Sintering Aid CuO-MnO2 on Dielectric Proper-ties of 0.5Ba(Mg1/3Nb2/3)O3-0.5Ba(Ni1/3Nb2/3)O3 Ceramics

    TIAN Zhongqing; ZHANG Chunyan; WANG Hao; HUANG Weijiu; LIN Lin


    Microstructures and microwave dielectric properties of 0.5Ba(Mg1/3Nb2/3)O3-0.5Ba(Ni1/3Nb2/3)O3 ceramics with x wt% CuO-x wt% MnO2 additions (x=0.25-1) prepared by conventional solid-state route were investigated. It is found that low level-doping of CuO-MnO2 can significantly improve the density of the specimens and their microwave dielectric properties. The relative density of 0.5Ba(Mg1/3Nb2/3)O3-0.5Ba(Ni1/3Nb2/3)O3 ceramics can be increased by 95% sintering at 1 330 ℃due to the liquid phase effect. The second phase is not observed in ceramics with CuO-MnO2 addition.The parameterεr increases with increasing sintering temperature, and Qf is effectively promoted by CuO-MnO2 addition. Higher CuO-MnO2 content would make τf value more positive. Meanwhile, εr value of 30.5, Qf value of 63 200 GHz and τf value of 0.5 ppm/ ℃ were obtained for 0.5Ba(Mg1/3Nb2/3)O3-0.5Ba(Ni1/3Nb2/3)O3 ceramics with 0.5 wt% CuO-0.5 wt% MnO2 addition sin-tered at 1 330 ℃ for 4 h.

  15. Ultrasonic Spray-Coating of Large-Scale TiO2 Compact Layer for Efficient Flexible Perovskite Solar Cells

    Peng Zhou


    Full Text Available Flexible electronics have attracted great interest in applications for the wearable devices. Flexible solar cells can be integrated into the flexible electronics as the power source for the wearable devices. In this work, an ultrasonic spray-coating method was employed to deposit TiO2 nanoparticles on polymer substrates for the fabrication of flexible perovskite solar cells (PSCs. Pre-synthesized TiO2 nanoparticles were first dispersed in ethanol to prepare the precursor solutions with different concentrations (0.5 mg/mL, 1.0 mg/mL, 2.0 mg/mL and then sprayed onto the conductive substrates to produce compact TiO2 films with different thicknesses (from 30 nm to 150 nm. The effect of the different drying processes on the quality of the compact TiO2 film was studied. In order to further improve the film quality, titanium diisopropoxide bis(acetylacetonate (TAA was added into the TiO2-ethanol solution at a mole ratio of 1.0 mol % with respect to the TiO2 content. The final prepared PSC devices showed a power conversion efficiency (PCE of 14.32% based on the indium doped tin oxide coated glass (ITO-glass substrate and 10.87% on the indium doped tin oxide coated polyethylene naphthalate (ITO-PEN flexible substrate.

  16. Decalactone production by Yarrowia lipolytica under increased O2 transfer rates.

    Aguedo, M; Gomes, N; Garcia, E Escamilla; Waché, Y; Mota, M; Teixeira, J A; Belo, I


    Yarrowia lipolytica converts methyl ricinoleate to gamma-decalactone, a high-value fruity aroma compound. The highest amount of 3-hydroxy-gamma-decalactone produced by the yeast (263 mg l(-1)) occurred by increasing the k(L)a up to 120 h(-1) at atmospheric pressure; above it, its concentration decreased, suggesting a predominance of the activity of 3-hydroxyacyl-CoA dehydrogenase. Cultures were grown under high-pressure, i.e., under increased O(2) solubility, but, although growth was accelerated, gamma-decalactone production decreased. However, by applying 0.5 MPa during growth and biotransformation gave increased concentrations of dec-2-en-4-olide and dec-3-en-4-olide (70 mg l(-1)).

  17. Estudo da degradação de ranitidina via H2O2 eletrogerado/Fenton em um reator eletroquímico com eletrodos de difusão gasosa

    André A. G. F. Beati; Rocha, Robson S.; Joaquim G. Oliveira; Lanza, Marcos R. V.


    The study of the electrochemical degradation of the ranitidine was developed using an electrochemical reactor with a gas diffusion electrode (GDE) as cathode. The electrolysis experiments was performed at constant current (1 4 A. The process reached a production of 630 mg L-1 of the H2O2 at 7 A. The...

  18. Toxicity of TiO2 nanoparticles to Escherichia coli: effects of particle size, crystal phase and water chemistry.

    Xiuchun Lin

    Full Text Available Controversial and inconsistent results on the eco-toxicity of TiO2 nanoparticles (NPs are commonly found in recorded studies and more experimental works are therefore warranted to elucidate the nanotoxicity and its underlying precise mechanisms. Toxicities of five types of TiO2 NPs with different particle sizes (10∼50 nm and crystal phases were investigated using Escherichia coli as a test organism. The effect of water chemistry on the nanotoxicity was also examined. The antibacterial effects of TiO2 NPs as revealed by dose-effect experiments decreased with increasing particle size and rutile content of the TiO2 NPs. More bacteria could survive at higher solution pH (5.0-10.0 and ionic strength (50-200 mg L(-1 NaCl as affected by the anatase TiO2 NPs. The TiO2 NPs with anatase crystal structure and smaller particle size produced higher content of intracellular reactive oxygen species and malondialdehyde, in line with their greater antibacterial effect. Transmission electron microscopic observations showed the concentration buildup of the anatase TiO2 NPs especially those with smaller particle sizes on the cell surfaces, leading to membrane damage and internalization. These research results will shed new light on the understanding of ecological effects of TiO2 NPs.

  19. Toxicity of TiO2 nanoparticles to Escherichia coli: effects of particle size, crystal phase and water chemistry.

    Lin, Xiuchun; Li, Jingyi; Ma, Si; Liu, Gesheng; Yang, Kun; Tong, Meiping; Lin, Daohui


    Controversial and inconsistent results on the eco-toxicity of TiO2 nanoparticles (NPs) are commonly found in recorded studies and more experimental works are therefore warranted to elucidate the nanotoxicity and its underlying precise mechanisms. Toxicities of five types of TiO2 NPs with different particle sizes (10∼50 nm) and crystal phases were investigated using Escherichia coli as a test organism. The effect of water chemistry on the nanotoxicity was also examined. The antibacterial effects of TiO2 NPs as revealed by dose-effect experiments decreased with increasing particle size and rutile content of the TiO2 NPs. More bacteria could survive at higher solution pH (5.0-10.0) and ionic strength (50-200 mg L(-1) NaCl) as affected by the anatase TiO2 NPs. The TiO2 NPs with anatase crystal structure and smaller particle size produced higher content of intracellular reactive oxygen species and malondialdehyde, in line with their greater antibacterial effect. Transmission electron microscopic observations showed the concentration buildup of the anatase TiO2 NPs especially those with smaller particle sizes on the cell surfaces, leading to membrane damage and internalization. These research results will shed new light on the understanding of ecological effects of TiO2 NPs.

  20. Removal of aqueous Pb(II) by adsorption on Al2O3-pillared layered MnO2

    Zhang, Haipeng; Gu, Liqin; Zhang, Ling; Zheng, Shourong; Wan, Haiqin; Sun, Jingya; Zhu, Dongqiang; Xu, Zhaoyi


    In the present study, Al2O3-pillared layered MnO2 (p-MnO2) was synthesized using δ-MnO2 as precursor and Pb(II) adsorption on p-MnO2 and δ-MnO2 was investigated. To clarify the adsorption mechanism, Al2O3 was also prepared as an additional sorbent. The adsorbents were characterized by X-ray fluorescence analysis, powder X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and N2 adsorption-desorption. Results showed that in comparison with pristine δ-MnO2, Al2O3 pillaring led to increased BET surface area of 166.3 m2 g-1 and enlarged basal spacing of 0.85 nm. Accordingly, p-MnO2 exhibited a higher adsorption capacity of Pb(II) than δ-MnO2. The adsorption isotherms of Pb(II) on δ-MnO2 and Al2O3 pillar fitted well to the Freundlich model, while the adsorption isotherm of Pb(II) on p-MnO2 could be well described using a dual-adsorption model, attributed to Pb(II) adsorption on both δ-MnO2 and Al2O3. Additionally, Pb(II) adsorption on δ-MnO2 and p-MnO2 followed the pseudo second-order kinetics, and a lower adsorption rate was observed on p-MnO2 than δ-MnO2. The Pb(II) adsorption capacity of p-MnO2 increased with solution pH and co-existing cation concentration, and the presence of dissolved humic acid (10.2 mg L-1) did not markedly impact Pb(II) adsorption. p-MnO2 also displayed good adsorption capacities for aqueous Cu(II) and Cd(II). Findings in this study indicate that p-MnO2 could be used as a highly effective adsorbent for heavy metal ions removal in water.

  1. Main: L1DCPAL1 [PLACE

    Full Text Available L1DCPAL1 S000504 15-September-2006 (last modified) kehi L1 element, found in PAL1 p...romoter in carrot (Daucus carota), is a protoplastization (dilution) responsive element; L1 contains Box L-l...ike sequence (ACCTACCC); see also S000492 (BOXL CORE of DC PAL1); L1 Daucus carota (carrot) ATTCACCTACCC ...

  2. Synthesis, characterization, and ecotoxicity of CeO2 nanoparticles with differing properties

    Alam, Bushra; Philippe, Allan; Rosenfeldt, Ricki R.; Seitz, Frank; Dey, Sonal; Bundschuh, Mirco; Schaumann, Gabriele E.; Brenner, Sara A.


    CeO2 nanoparticles with various characteristics find an increasing number of applications in the electronic, medical, and other industries and are therefore likely released in the environment. This calls for investigations linking the physicochemical properties of these particles with their potential environmental impacts. In this study, CeO2 nanoparticle powders were prepared using three different precursors [Ce(NO3)3, CeCl3, and Ce(CH3COO)3] and annealing temperatures (300, 500, and 700 °C). This procedure resulted in nine different types of nanoparticles with differing size (5-90 nm), morphology, surface Ce3+/Ce4+ ratio, and slightly different crystal structures as characterized using transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy, and X-ray diffraction measurements with Rietveld refinement. These CeO2 nanoparticles underwent toxicity testing at concentrations up to 64 mg L-1 using Daphnia magna. Toxic effects were observed for three particle types with EC50 values between 5 and 64 mg L-1. No clear correlation was observed between the physicochemical properties (size, shape, oxygen occupancy, Ce3+/Ce4+ ratio) of the nanoparticles and their toxicity. However, toxicity was correlated with the amount of Ce remaining suspended in the test medium after 24 h. This indicated that toxic effects may depend on the colloidal stability of CeO2 nanoparticles during the first day of exposure. Therefore, being readily suspended and remaining stable for several days in the aquatic media increases the likelihood that CeO2 nanoparticles will cause unwanted adverse effects.

  3. Electrodegradation of the Acid Green 28 dye using Ti/β-PbO2 and Ti-Pt/β-PbO2 anodes.

    Irikura, Kallyni; Bocchi, Nerilso; Rocha-Filho, Romeu C; Biaggio, Sonia R; Iniesta, Jesús; Montiel, Vicente


    The statistical Response Surface Methodology (RSM) is applied to investigate the effect of different parameters (current density, j, NaCl concentration, [NaCl], pH, and temperature, θ) and their interactions on the electrochemical degradation of the Acid Green (AG) 28 dye using a Ti/β-PbO2 or Ti-Pt/β-PbO2 anode in a filter-press reactor. LC/MS is employed to identify intermediate compounds. For both anodes, the best experimental conditions are j = 50 mA cm(-2), [NaCl] = 1.5 g L(-1), pH = 5, and θ = 25 °C. After 3 h of electrolysis, a dye solution treated under these conditions presents the following parameters: electric charge per unit volume of the electrolyzed solution required for 90% decolorization (Q(90)) of 0.34-0.37 A h L(-1), %COD removal of ∼100%, specific energy consumption of 18-20 kW h m(-3), and %TOC removal of 32-33%. No loss of the β-PbO2 film is observed during all the experiments. The β-PbO2 films present excellent stability for solutions with pH ≥ 5 ([Pb(2+)] < 0.5 mg L(-1)). Chloroform is the only volatile organic halo compound present in the treated solution under those optimized conditions. Hydroxylated anthraquinone derivatives, aromatic chloramines, and naphthoquinones are formed during the electrolyses. The Ti/β-PbO2 and Ti-Pt/β-PbO2 anodes show significantly better performance than a commercial DSA anode for the electrochemical degradation of the AG 28 dye. The Ti/β-PbO2 anode, prepared as described in this work, is an excellent option for the treatment of textile effluents because of its low cost of fabrication and good performance.

  4. Toxicity of CeO2 nanoparticles at different trophic levels--effects on diatoms, chironomids and amphibians.

    Bour, Agathe; Mouchet, Florence; Verneuil, Laurent; Evariste, Lauris; Silvestre, Jérôme; Pinelli, Eric; Gauthier, Laury


    The aim of the present work is to provide wider information on the toxicity of cerium dioxide nanoparticles (CeO2 NPs) in aquatic environments, by studying the toxicity of two types of CeO2 NPs for four species (diatoms Nitzschia palea, the sediment-dwelling invertebrate Chironomus riparius, and the amphibian larvae Xenopus laevis and Pleurodeles waltl.). The two types of CeO2 NPs have different intrinsic properties: some of them are small citrate-coated spheres (2-5 nm), and the others are larger uncoated plates (20-60 nm). Acute toxicity (mortality at 48 or 96 h, depending on the test-organism) was assessed for the four species, from 0.1 to 100 mg L(-1) of NPs. Sub-lethal effects were assessed on chironomids exposed between 0.01 and 1 mg L(-1) of NPs. Mortality, growth inhibition and genotoxic effects were evaluated on amphibian larvae from 0.1 to 10 mg L(-1). Results reveal that no acute toxicity occurs on any species after short exposures, even at the highest concentrations. Mortality (35%) is observed on Xenopus larvae after 12d of exposure at the highest concentration of one type of NPs. No significant effects were observed on chironomids during chronic exposure. Xenopus larvae growth was inhibited from 1 mg L(-1) of both NPs while growth inhibition is observed on Pleurodeles only at the highest concentration of one type of NPs. No genotoxicity was observed on Xenopus but Pleurodeles exhibited dose-dependent genotoxic effects when exposed to one type of NPs. Observed differences in toxicity are discussed focusing on the studied compartment, routes of exposure, species and NPs.

  5. Heterogeneous UV/Fenton degradation of bisphenol A catalyzed by synergistic effects of FeCo2O4/TiO2/GO.

    Bai, Xue; Lyu, Lingling; Ma, Wenqiang; Ye, Zhengfang


    A new method for bisphenol A (BPA) degradation in aqueous solution was developed. The characteristics of BPA degradation in a heterogeneous ultraviolet (UV)/Fenton reaction catalyzed by FeCo2O4/TiO2/graphite oxide (GO) were studied. The properties of the synthesized catalysts were characterized using scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometry. FeCo2O4 and TiO2 were grown as spherical shape, rough surface, and relatively uniform on the surface of GO (FeCo2O4/TiO2/GO). Batch tests were conducted to evaluate the effects of the initial pH, FeCo2O4/TiO2/GO dosage, and H2O2 concentration on BPA degradation. In a system with 0.5 g L(-1) of FeCo2O4/TiO2/GO and 10 mmol L(-1) of H2O2, approximately 90 % of BPA (20 mg L(-1)) was degraded within 240 min of UV irradiation at pH 6.0. The reused FeCo2O4/TiO2/GO catalyst retained its activity after three cycles, which indicates that it is stable and reusable. The heterogeneous UV/Fenton reaction catalyzed by FeCo2O4/TiO2/GO is a promising advanced oxidation technology for treating wastewater that contains BPA.

  6. Influencia de la síntesis y del grado de dopaje en las propiedades morfológicas, estructurales y electroquímicas de óxidos LiCo1‑xMxO2 (M = Ni, Al, Mg

    Castro‑Couceiro, A.


    Full Text Available In this work we have prepared, by a sol‑gel method, LiCo1‑ xMxO2 compounds (M= Ni, Al and Mg, in order to study the doping effect in their electrochemical behaviour as cathodes in lithium‑batteries. We have studied the influence of the synthesis conditions (using various chelating agents for the formation of the gel on their morphologic, structural and electrochemical properties. We have obtained monophasic materials: LiCo1‑xNixO2 (0≤x≤0.8, LiCo1‑xMgxO2 (0≤x≤0.05, LiCo1‑xAlxO2 (0≤x≤0.3 and LiCo0.5Ni0.5‑xAlxO2 (0≤x≤0.3. In general, the samples obtained with succinic acid have better ordered lithium layers than malic samples.The capacity of the Li//LiCo1‑ xMxO2 batteries decrease upon doping. However, more stable charge‑discharge cycling performances have been obtained as compared to those displayed by the native oxides. In LiCo1‑xMgxO2, small amounts of MgO appear as secondary phases for 0.05 En este trabajo preparamos, mediante un método sol‑gel, óxidos LiCo1‑xMxO2 dopando LiCoO2 con Ni, Al y Mg, con el fin de comprobar la influencia del catión dopante y del grado de dopaje en su comportamiento electroquímico como cátodos de baterías de litio. Estudiamos la influencia de las condiciones de síntesis (utilizando diferentes agentes quelatantes para la formación del gel en las propiedades morfológicas y estructurales de los materiales obtenidos, que condicionan, a su vez, su comportamiento electroquímico. Se obtuvieron muestras monofásicas para distintos grados de dopaje: LiCo1‑xNixO2 (0≤x≤0.8, LiCo1‑xMgxO2 (0≤x≤0.05, LiCo1‑xAlxO2 (0≤x≤0.3 y LiCo0.5Ni0.5‑xAlxO2 (0≤x≤0.3. En general, se logra un mejor orden catiónico en la estructura utilizando ácido succínico como agente quelatante que utilizando ácido málico. Los estudios electroquímicos muestran que los tres dopantes (Ni, Mg y Al provocan una disminución de la capacidad de las baterías, pero contribuyen a mantener

  7. Photocatalytic oxidation of 5-fluorouracil and cyclophosphamide via UV/TiO2 in an aqueous environment.

    Lin, Hank Hui-Hsiang; Lin, Angela Yu-Chen


    Cytostatic drugs are a class of pharmaceuticals that are increasingly used in cancer therapies; 5-fluorouracil is one of the most commonly used cytostatic (antineoplastic) drugs in the world. This study applied photocatalytic oxidation to remove 5-fluorouracil. Degussa P25 showed a higher photocatalytic degradation efficiency for 5-fluorouracil removal than Aldrich TiO2 and ZnO. Under optimal conditions (20 mg L(-1) TiO2 at pH 5.8), 200 μg L(-1) 5-fluorouracil can be removed within 2 h (k = 0.0375 min(-1)). 5-fluorouracil was found to be decomposed by near-surface OH free radicals produced from valence holes (hvb(+)). At a relatively high concentration, 5-fluorouracil (27.6 mg L(-1)) is >99.9% removed within 4 h by 300 mg L(-1) Degussa P25, while 24 h is required to reach complete mineralization with 96.7% fluoride recovery. Cyclophosphamide is another widely used cancer drug that follows a similar decomposition pathway. Cyclophosphamide (27.6 mg L(-1)) was also >99.9% eliminated within 4 h, but dechlorination and mineralization reached only 79.9% and 55.1%, respectively, after 16 h of irradiation. Together with the results for Microtox(®), it is suggested that the oxidation products of cyclophosphamide are even more recalcitrant and toxic. For engineering practices, despite the fact that photocatalytic oxidation can rapidly remove target antineoplastic, it is also important to further evaluate the treatment efficiency of the photoproducts.

  8. Influence of SiO2 Particles on Microstructures and Properties of Ni-W-P-CeO2-SiO2 Nano-Composite Coatings

    Xu Ruidong; Wang Junli; Guo Zhongcheng; Wang Hua


    Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on the carbon steel surface by pulse co-deposition of nickel, tungsten, phosphorus, nano-CeO2 and nano-SiO2 particles. The influence of nano-SiO2 particles concentrations in electrolyte on microstructures and properties of the nano-composite coatings were researched, and the characteristics were assessed by chemical compositions, element distribution, deposition rate, microhardness and microstructures. The results indicate that when nano-SiO2 particles concentrations in electrolyte are controlled at 20g·L-1, the deposition rate with 27.07μm·h-1 and the microhardness with 666 Hv of the nano-composite coatings are highest, element line scanning and area scanning analyses show that the average contents of elements W, P, Si and Ce in the nano-composite coatings are close. displaying that the distribution of every element within the nano-composite coatings is even. An increase in nano-SiO2 particles concentrations in electrolyte (when lower than 20g·L-1) leads to refinement in grain structure of nano-composite coatings, but when it improved to 30g·L-1, the crystallite sizes increase again and in the meantime there are a lot of small boss with nodulation shape appearing on the surface of nano-composite coatings.

  9. Corrosion behavior of MgO -C based refractory in slag containing TiO2%含钛熔渣对镁炭质耐火材料的侵蚀

    刘清才; 许原; 陈登福



  10. Air Plasma-Sprayed La2Zr2O7-SrZrO3 Composite Thermal Barrier Coating Subjected to CaO-MgO-Al2O3-SiO2 (CMAS)

    Cai, Lili; Ma, Wen; Ma, Bole; Guo, Feng; Chen, Weidong; Dong, Hongying; Shuang, Yingchai


    La2Zr2O7-SrZrO3 composite thermal barrier coatings (TBCs) were prepared by air plasma spray (APS). The La2Zr2O7-SrZrO3 composite TBCs covered with calcium-magnesium-aluminum-silicate (CMAS) powder, as well as the powder mixture of CMAS and spray-dried La2Zr2O7-SrZrO3 composite powder, were heat-treated at 1250 °C in air for 1, 4, 8, and 12 h. The phase constituents and microstructures of the reaction products were characterized by x-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. Experimental results showed that the La2Zr2O7-SrZrO3 composite TBCs had higher CMAS resistance than 8YSZ coating. A dense new layer developed between CMAS and La2Zr2O7-SrZrO3 composite TBCs during interaction, and this new layer consisted mostly of apatite (Ca2La8(SiO4)6O2) and c-ZrO2. The newly developed layer effectively protected the La2Zr2O7-SrZrO3 composite TBCs from further CMAS attack.

  11. A novel combined solar pasteurizer/TiO2 continuous-flow reactor for decontamination and disinfection of drinking water.

    Monteagudo, José María; Durán, Antonio; Martín, Israel San; Acevedo, Alba María


    A new combined solar plant including an annular continuous-flow compound parabolic collector (CPC) reactor and a pasteurization system was designed, built, and tested for simultaneous drinking water disinfection and chemical decontamination. The plant did not use pumps and had no electricity costs. First, water continuously flowed through the CPC reactor and then entered the pasteurizer. The temperature and water flow from the plant effluent were controlled by a thermostatic valve located at the pasteurizer outlet that opened at 80 °C. The pasteurization process was simulated by studying the effect of heat treatment on the death kinetic parameters (D and z values) of Escherichia coli K12 (CECT 4624). 99.1% bacteria photo-inactivation was reached in the TiO2-CPC system (0.60 mg cm(-2) TiO2), and chemical decontamination in terms of antipyrine degradation increased with increasing residence time in the TiO2-CPC system, reaching 70% degradation. The generation of hydroxyl radicals (between 100 and 400 nmol L(-1)) was a key factor in the CPC system efficiency. Total thermal bacteria inactivation was attained after pasteurization in all cases. Chemical degradation and bacterial photo-inactivation in the TiO2-CPC system were improved with the addition of 150 mg L(-1) of H2O2, which generated approximately 2000-2300 nmol L(-1) of HO(●) radicals. Finally, chemical degradation and bacterial photo-inactivation kinetic modelling in the annular CPC photoreactor were evaluated. The effect of the superficial liquid velocity on the overall rate constant was also studied. Both antipyrine degradation and E. coli photo-inactivation were found to be controlled by the catalyst surface reaction rate.

  12. Preparation and photocatalytic properties of N-doped nano-TiO2/muscovite composites

    Zhou, S.; Lv, J.; Guo, L. K.; Xu, G. Q.; Wang, D. M.; Zheng, Z. X.; Wu, Y. C.


    Using muscovite as the carrier, TiCl4 as the source of titanium, urea as the neutralizer, nano-TiO2/muscovite composites (TiO2/M) were prepared by the method of hydrolysis-precipitation. Then N-doped TiO2/M composites were prepared by using urea as dopant after calcination at 500 °C for 2 h. The samples were characterized by XRD, SEM, EDS, XPS and DUV methods. The photocatalytic activity of samples was evaluated by degradation of methyl orange under visible light irradiation (halogen lamp, 250 W). The results showed that the surfaces of muscovite were uniformly coated by nano-TiO2, which combined with the muscovite surface via the Sisbnd Osbnd Ti and Osbnd Tisbnd N bonds. The grain growth of TiO2 and the phase transformation from anatase to rutile were restrained by the doping of nitrogen. Meanwhile, the absorption edge of samples after doping exhibited red-shift from 390 nm to 430 nm, showing obvious response to visible light. The degradation rate of methyl orange (20 mg L-1) reached 67.15% after irradiation of 250 W halogen lamp for 1 h (doping ratio was 1:3), while the degradation rate of un-doped sample was just 8%.

  13. Fabrication and Property Investigation of the Highly Ordered TiO2 Nanotube Arrays%高度有序TiO2纳米管阵列的制备及其光催化性能研究

    兰宇卫; 周立亚; 童张法; 庞起; 冷利民; 韩建鹏; 王凡


    室温下在NH4F、乙二醇的混合溶液中采用阳极氧化法在纯Ti片表面得到一层结构高度有序、分布均匀、垂直取向TiO2纳米管阵列,通过调整阳极氧化工艺条件可实现对其结构参数(如管径、管壁厚度、管长等)的有效控制:对TiO2纳米管阵列进行扫描电子显微镜(SEM)、X-射线衍射(XRD)检测;测试了TiO2纳米管降解甲基橙的光催化性能.结果表明:在优化条件下制备得到了高密度排列的TiO2纳米管阵列;在500W高压汞灯照射40min后,初始摩尔浓度为20 mg·L-1的甲基橙在pH=2.0时,降解率达到99.4%,溶液中加入H2O2可以提高TiO2纳米管光降解催化活性.%The highly ordered and uniform TiO2 nanotube arrays were fabricated by anodic oxidation of titanium foil in ethylene glycol solution containing NH4 F. The diameter, density, length and wall thickness of the prepared nanotube arrays can be controlled effectively by varying the anodization parameters. The microstructures and morphologies of the fabricated TiO2 nanotube were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD), and its photocatalytic properties were investigated via the degradation of methyl orange. The results show that the highly ordered and uniform TiO2 nanotube arrays could be grown under the conditions optimized by authors. Using the prepared TiO2 nanotube arrays as photocatalyst and after 40 min illumination of the high voltage mercury lamp (500 W), the degradation ratio of methyl orange in its aqueous solution with concentratin of 20 mg.L-1 can reach 99.4% when the solution pH value is 2.0. And it was found that the photoeatalysis of TiO2 nanotube can be improved by adding H202 into the solution.

  14. Solar CPC pilot plant photocatalytic degradation of bisphenol A in waters and wastewaters using suspended and supported-TiO2. Influence of photogenerated species.

    Saggioro, Enrico Mendes; Oliveira, Anabela Sousa; Pavesi, Thelma; Tototzintle, Margarita Jiménez; Maldonado, Manuel Ignacio; Correia, Fábio Verissimo; Moreira, Josino Costa


    Photocatalytic degradation of bisphenol A (BPA) in waters and wastewaters in the presence of titanium dioxide (TiO2) was performed under different conditions. Suspensions of the TiO2 were used to compare the degradation efficiency of BPA (20 mg L(-1)) in batch and compound parabolic collector (CPC) reactors. A TiO2 catalyst supported on glass spheres was prepared (sol-gel method) and used in a CPC solar pilot plant for the photodegradation of BPA (100 μg L(-1)). The influence of OH·, O2 (·-), and h (+) on the BPA degradation were evaluated. The radicals OH· and O2 (·-) were proved to be the main species involved on BPA photodegradation. Total organic carbon (TOC) and carboxylic acids were determined to evaluate the BPA mineralization during the photodegradation process. Some toxicological effects of BPA and its photoproducts on Eisenia andrei earthworms were evaluated. The results show that the optimal concentration of suspended TiO2 to degrade BPA in batch or CPC reactors was 0.1 g L(-1). According to biological tests, the BPA LC50 in 24 h for E. andrei was of 1.7 × 10(-2) mg cm(-2). The photocatalytic degradation of BPA mediated by TiO2 supported on glass spheres suffered strong influence of the water matrix. On real municipal wastewater treatment plant (MWWTP) secondary effluent, 30 % of BPA remains in solution; nevertheless, the method has the enormous advantage since it eliminates the need of catalyst removal step, reducing the cost of treatment.

  15. 水质对UV/H2O2降解LAS的影响及机理%Effect and Mechanism of Water Quality on Degradation of LAS by UV/H2O2 Combination Process

    潘晶; 于龙; 张阳; 王艳


    研究了UV/H2O2工艺对LAS的去除效果以及水的pH、浊度对LAS降解的影响和机理. 结果表明: UV/H2O2工艺可以有效的去除水中LAS, 光降解过程符合一级反应动力学模型;在H2O2投加量为8 mg·L-1,14 W低压汞灯照射下, LAS在蒸馏水中光降解速率常数为0.018 1 min-1;在酸性条件下,有利于LAS光降解;浊度大于6NTU时,光降解速率常数迅速下降.

  16. Main: L1BOXATPDF1 [PLACE

    Full Text Available L1BOXATPDF1 S000386 05-November-2005 (last modified) kehi L1 box found in promoter ...of Arabidopsis thaliana (A.t.) PROTODERMAL FACTOR1 (PDF1) gene; Located between -134 and -127; Involved in L...ding motif (Wang et al., 2004); HDZip IV; See also S000371; PDF1; L1 box; L1 layer-specific expression; Shoo

  17. Photochemical degradation of typical halogenated herbicide 2,4-D in drinking water with UV/H2O2/micro-aeration


    UV/H2O2/micro-aeration is a newly developed process based on UV/H2O2. Halogenated pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) photochemical degradation in aqueous solution was studied under various solution conditions. The UV intensity,initial 2,4-D concentrations and solution temperature varied from 183.6 to 1048.7 μW·cm-2,from 59.2 to 300.0 μg·L-1 and from 15 to 30℃,respectively. The concentration of hydrogen peroxide (H2O2) and pH ranged from 0 to 50 mg·L-1 and 5 to 9,and different water quality solutions (tap water,distilled water and deionized water) were examined in this study. With initial concentration of about 100 μg·L-1,more than 95.6% of 2,4-D can be removed in 90 min at intensity of UV radiation of 843.9 μW·cm-2,H2O2 dosage of 20 mg·L-1,pH 7 and room temperature. The removal efficiency of 2,4-D by UV/H2O2/micro-aeration process is better than UV/H2O2 process. The photodecomposition of 2,4-D in aqueous solution follows pseudo-first-order kinetics. 2,4-D is greatly affected by UV irradation intensity,H2O2 dosage,initial 2,4-D concentration and water quality solutions,but it appears to be slightly influenced by pH and temperature. There is a linear relationship between rate constant k and UV intensity and initial H2O2 concentration,which indicates that higher removal capacity can be achieved by the improvement of these factors. Finally,a preliminary cost analysis reveals that UV/H2O2/micro-aeration process is more cost-effective than the UV/H2O2 process in the removal of 2,4-D from drinking water.

  18. Electrochemical degradation of pyridine by Ti/SnO2-Sb tubular porous electrode.

    Li, Duo; Tang, Jingyan; Zhou, Xiezhen; Li, Jiansheng; Sun, Xiuyun; Shen, Jinyou; Wang, Lianjun; Han, Weiqing


    Diffusion in electrochemistry is a critical issue for water purification. Electrocatalytic reactor system in improving water quality is a useful way to induce convection to enhance diffusion. This study focuses on the preparation and the characterization of Ti/SnO2-Sb tubular porous electrode for degrading pyridine wastewater. The electrode as an anode in reactor system is prepared by coating SnO2-Sb as an electro-catalyst via Pechini method on the tubular porous Ti. Scanning Electron Microscopy, Energy Dispersive Spectrum, X-ray Diffraction and Pore Distribution are employed to evaluate the structure and morphology of the electrodes coatings, and Linear Sweep Voltammetry and Cyclic Voltammetry are used to illustrate the electrochemical properties of the electrodes coatings. Furthermore, the electrochemical oxidation performance of Ti/SnO2-Sb tubular porous electrode is characterized by degrading pyridine wastewater. The effects of flow and static pattern, initial pyridine concentration, supporting electrolyte concentration, current density and pH on the performance of the reactor were investigated in the electrocatalytic reactor system. The results indicated that the removal ratio of pyridine reaches maximum which is 98% under the optimal operation conditions, that are 100 mg L(-1) initial pyridine concentration, 10 g L(-1) supporting electrolyte concentration, 30 mA cm(-2) current density and pH 3. Transition state calculation based on the density function theory was combined with High Performance Liquid Chromatography, Gas Chromatography and Ionic Chromatography results to describe the pathway of pyridine degradation.

  19. Photocatalytic degradation of carbofuran by TiO2-coated activated carbon: Model for kinetic, electrical energy per order and economic analysis.

    Vishnuganth, M A; Remya, Neelancherry; Kumar, Mathava; Selvaraju, N


    The photocatalytic removal of carbofuran (CBF) from aqueous solution in the presence of granular activated carbon supported TiO2 (GAC-TiO2) catalyst was investigated under batch-mode experiments. The presence of GAC enhanced the photocatalytic efficiency of the TiO2 catalyst. Experiments were conducted at different concentrations of CBF to clarify the dependence of apparent rate constant (kapp) in the pseudo first-order kinetics on CBF photodegradation. The general relationship between the adsorption equilibrium constant (K) and reaction rate constant (kr) were explained by using the modified Langmuir-Hinshelwood (L-H) model. From the observed kinetics, it was observed that the surface reaction was the rate limiting step in the GAC-TiO2 catalyzed photodegradation of CBF. The values of K and kr for this pseudo first-order reaction were found to be 0.1942 L  mg(-1) and 1.51 mg L(-1) min(-1), respectively. In addition, the dependence of kapp on the half-life time was determined by calculating the electrical energy per order experimentally (EEO experimental) and also by modeling (EEO model). The batch-mode experimental outcomes revealed the possibility of 100% CBF removal (under optimized conditions and at an initial concentration of 50 mg L(-1) and 100 mg L(-1)) at a contact time of 90 min and 120 min, respectively. Both L-H kinetic model and EEO model fitted well with the batch-mode experimental data and also elucidated successfully the phenomena of photocatalytic degradation in the presence of GAC-TiO2 catalyst. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Factors Influencing Photocatalytic Degradation of Trichlorfon by TiO2 and ZnO%TiO2和ZnO光催化降解敌百虫的影响因素研究

    李雪银; 朱丽珺; 张海洋; 石燕军; 陈燕


    采用溶胶-凝胶法和水热法制备了TiO2和ZnO,并运用紫外-可见光谱、X射线衍射、扫描电子显微镜和红外光谱对光催化剂进行表征。用制备所得的TiO2和ZnO作为光催化剂,降解敌百虫有机磷农药,使用气质联用仪对降解结果进行分析,探究农药初始浓度、农药初始pH值、光催化剂投加量、光照时间及不同光源对敌百虫降解率的影响。光催化降解反应表明,敌百虫的降解率随着初始浓度的增加明显降低,随着光照时间的延长先增加后趋于平缓,碱性条件和汞灯照射有利于敌百虫的光催化降解。TiO2和ZnO的最佳投加量均为100~150 mg·L-1,以ZnO为光催化剂,投加量在0~100 mg·L-1时降解率的增幅明显高于投加量在100~200 mg·L-1时,且实验结果表明,5个影响因素条件下,TiO2的光催化降解活性均低于ZnO。%Photocatalytic degradation of pollutants has attracted increasing attentions recently. Due to their stability, wide band gap and high photosensitivity, photocatalysts TiO2 and ZnO have been widely applied in the degradation of various organic pollutants. In this research, TiO2 and ZnO were prepared by sol-gel and hydrothermal synthesis method. The band gaps of their nanoparticles were estimated by UV ab-sorption spectra(UV-vis). Their crystalline phases were confirmed by X-ray diffraction(XRD)and Fourier infrared spectroscopy(FT-IR), and their morphology were observed by scanning electron microscopy(SEM). The photocatalytic degradation of trichlorfon was investigated under different initial trichlorfon concentrations, operating pH, photocatalyst rates, irradiation time and light sources. Results showed that the degradation rate of trichlorfon decreased with increasing initial concentrations of trichlorfon, but it increased with prolonging irradiation time while slowed down at longer time. Alkaline condition and mercury lamp irradiation both enhanced the degradation rates of

  1. Assessment of solar driven TiO2-assisted photocatalysis efficiency on amoxicillin degradation.

    Pereira, João H O S; Reis, Ana C; Nunes, Olga C; Borges, Maria T; Vilar, Vítor J P; Boaventura, Rui A R


    The objective of this work was to evaluate the efficiency of a solar TiO2-assisted photocatalytic process on amoxicillin (AMX) degradation, an antibiotic widely used in human and veterinary medicine. Firstly, solar photolysis of AMX was compared with solar photocatalysis in a compound parabolic collectors pilot scale photoreactor to assess the amount of accumulated UV energy in the system (Q UV) necessary to remove 20 mg L(-1) AMX from aqueous solution and mineralize the intermediary by-products. Another experiment was also carried out to accurately follow the antibacterial activity against Escherichia coli DSM 1103 and Staphylococcus aureus DSM 1104 and mineralization of AMX by tracing the contents of dissolved organic carbon (DOC), low molecular weight carboxylate anions, and inorganic anions. Finally, the influence of individual inorganic ions on AMX photocatalytic degradation efficiency and the involvement of some reactive oxygen species were also assessed. Photolysis was shown to be completely ineffective, while only 3.1 kJUV L(-1) was sufficient to fully degrade 20 mg L(-1) AMX and remove 61% of initial DOC content in the presence of the photocatalyst and sunlight. In the experiment with an initial AMX concentration of 40 mg L(-1), antibacterial activity of the solution was considerably reduced after elimination of AMX to levels below the respective detection limit. After 11.7 kJUV L(-1), DOC decreased by 71%; 30% of the AMX nitrogen was converted into ammonium and all sulfur compounds were converted into sulfate. A large percentage of the remaining DOC was in the form of low molecular weight carboxylic acids. Presence of phosphate ions promoted the removal of AMX from solution, while no sizeable effects on the kinetics were found for other inorganic ions. Although the AMX degradation was mainly attributed to hydroxyl radicals, singlet oxygen also plays an important role in AMX self-photosensitization under UV/visible solar light.

  2. PD-L1-specific T cells

    Ahmad, Shamaila Munir; Borch, Troels Holz; Hansen, Morten


    -specific T cells that recognize both PD-L1-expressing immune cells and malignant cells. Thus, PD-L1-specific T cells have the ability to modulate adaptive immune reactions by reacting to regulatory cells. Thus, utilization of PD-L1-derived T cell epitopes may represent an attractive vaccination strategy...... for targeting the tumor microenvironment and for boosting the clinical effects of additional anticancer immunotherapy. This review summarizes present information about PD-L1 as a T cell antigen, depicts the initial findings about the function of PD-L1-specific T cells in the adjustment of immune responses...

  3. Ultrasonic-assisted sol-gel synthesis of samarium, cerium co-doped TiO2 nanoparticles with enhanced sonocatalytic efficiency.

    Eskandarloo, Hamed; Badiei, Alireza; Behnajady, Mohammad A; Ziarani, Ghodsi Mohammadi


    In this work, pure TiO2 and samarium, cerium mono-doped and co-doped TiO2 catalysts were synthesized by an ultrasonic-assisted sol-gel method and their sonocatalytic efficiency studied toward removal of Methyl Orange as a model organic pollutant from the textile industry. The relationship of structure and sonocatalytic performance of catalysts was established by using various techniques, such as XRD, TEM, SEM, EDX, DRS, and PL. A comparison on the removal efficiency of sonolysis alone and sonocatalytic processes was performed. The results showed that the samarium, cerium co-doped TiO2 catalyst with narrower band gap energy and smaller particle size leads to a rapid removal of pollutant. It was believed that Sm(3+) and Ce(4+) ions can serve as superficial trapping for electrons at conduction band of TiO2 and prolonged the lifetime of electron-hole pairs. Finally, the effect of synthesis and operational variables on the sonocatalytic activity of co-doped TiO2 catalyst was studied and optimized using response surface methodology as a statistical technique. The results showed that the maximum removal efficiency (96.33%) was achieved at the optimum conditions: samarium content of 0.6 wt%, cerium content of 0.82 wt%, initial pollutant concentration of 4.31 mg L(-1), catalyst dosage of 0.84 mg L(-1), ultrasonic irradiation power of 700 W, and irradiation time of 50 min.

  4. Experimental Study on UV/Mn2+-Fe3+/H2O2 for Wastewater Treatment%UV/Mn2+-Fe3+/H2O2处理染料废水的实验研究



    研究了常温常压下UV/Mn2+-Fe3+/H2O2光催化非均相反应体系处理偶氮染料模拟废水的特性,并与UV-Mn2+/H2O2、UV/Fe2+/H2O2等体系处理染料废水的效果进行了对比;考察了Mn2+、Fe2+、Fe3+、H2O2投加量对UV/Mn2+-Fe3+/H2O2反应体系处理染料废水的影响.结果表明,UV/Mn2+-Fe3+/H2O2反应体系具有良好的催化氧化作用,在20 w紫外光照射下,100 mg·L-1的直接大红D-GLN在反应20 min时,降解效率高达到90%以上.

  5. Fe(O)/H2O2协同降解亚甲基蓝的研究%Degradation of Methylene Blue by Fe(0)/H2O2

    廖琳; 黄宏星; 叶俊炜; 唐小燕; 尹光彩; 侯梅芳


    Degradation of methylene blue by Fe(0)-based Fenton process with H2O2 in dark was investigated. The effects of H2O2 dose, Fe(0) dose, initial concentration of methylene blue and initial pH value on the degradation of methylene blue were examined. The results showed that the degradation of methylene blue occurred with low dose of H2O2 and Fe(0). The removal of MB can be over 90% at pH 4.5 with 2.0 g·L-1 Fe(0) and 3.0 mmolL-1 H2O2. The degradation rate of MB by Fe(0)-based Fenton process with H2O2 increased with the increasing of Fe(0) dose and H2O2 dose, but decreased with the increasing of initial concentration of MB. The optimum pH value for the degradation of MB by Fe(0)/H2O2 is near neutral. The change of UV-vis spectra of MB during reaction suggested some small molecular intermediates produced during reaction.%进行了Fe(0)和H2O2协同催化降解亚甲基蓝的研究,分析了Fe(0)投加量、H2O2投加量、溶液初始pH值和染料初始质量浓度等因素的影响.研究表明:Fe(0)和H2O2协同可有效催化降解亚甲基蓝;在pH为4.5,Fe(0)用量为2.0 g·L-1,H2O2用量为3.0 mmol·L-1时对10 mg·L-1亚甲基蓝的去除率在60 min内达到90%以上.MB的降解去除率随着Fe(0)投加量与H2O2用量的增加而增加,但随着其初始质量浓度的增大而降低.研究结果还表明,Fe(0)和H2O2可在接近中性条件下有效协同催化降解亚甲基蓝.UV-Vis光谱在反应过程的变化说明亚甲基蓝降解生成了一些小分子物质.

  6. [Catalytic hydrodechlorination of 2,4-dichlorophenol over Pd/TiO2].

    Zhang, Yin; Shao, Yun; Chen, Huan; Wan, Hai-Qin; Wan, Yu-Qiu; Zheng, Shou-Rong


    Pd/TiO2 catalysts were prepared by the deposition-precipitation and impregnation methods, and were further characterized by TEM, XRD and ICP-AES. The liquid catalytic hydrodechlorination of 2,4-dichlorophenol over the catalysts was investigated. It is demonstrated that despite catalyst prepared by deposition-precipitation method exhibits higher activity than that synthesized from impregnation method, both catalysts show good performance in hydrodechlorination process. When initial concentration of the reactant was 3.11 mmol x L(-1), pH was 12 and amount of catalyst used was 50 mg, hydrodechlorination of 2,4-dichlorophenol was completed within 45 min. Acidic condition facilitates hydrodechlorination process. The initial activity was not significantly influenced when the amount of catalyst used varied between 15-80 mg, which proves that mass transport limitation exerts little impact on hydrodechlorination reaction. Finally, the initial activity sharply enhanced with the increase of initial concentration of 2,4-dichlorophenol when the concentration was in the range of 0.62-3.11 mmo x L(-1) while it almost remained constant with further increasing the initial concentration. Therefore, the catalytic hydrodechlorination of 2,4-dichlorophenol over Pd/TiO2-DP follows the Langumuir-Hinshelwood model, indicating that the catalytic hydrodechlorination is controlled by 2,4-dichlorophenol adsorption.

  7. Aplicação de Fenton, foto-Fenton e UV/H2O2 no tratamento de efluente têxtil sintético contendo o corante Preto Biozol UC Application of Fenton, photo-Fenton and UV/H2O2 in treating synthetic textile wastewater containing the dye Black Biozol UC

    Leonardo Madeira Martins


    Full Text Available Os efluentes têxteis, geralmente, são carregados de corantes não biodegradáveis, o que dificulta o seu tratamento. Dentre as novas alternativas de tratamento estudadas, estão os Processos Oxidativos Avançados (POA. Os mesmos são processos com potencial de produzir radicais hidroxila (•OH, espécies altamente oxidantes, capazes de mineralizar a matéria orgânica. Assim, o objetivo deste trabalho foi estudar a aplicação dos POA (Fenton, foto-Fenton e UV/H2O2 no tratamento de efluente têxtil sintético contendo o corante Preto Biozol UC. Dentre os processos estudados, o mais eficiente foi o foto-Fenton (H2O2 = 1.500 mg.L-1 e Fe2+ = 75 mg.L-1, em pH = 3, que obteve 95,4% e 73,0% para as remoções de cor e demanda química de oxigênio (DQO, respectivamente.The textile wastewater is usually loaded with non-biodegradable dyes, which hinder its treatment. Advanced Oxidation Processes (AOP are among new treatment alternatives. They are processes with potential to produce hydroxyl radicals (•OH, highly oxidizing species, capable of mineralizing the organic matter. Thus, the aim of this work was to study the application of the AOP (Fenton, photo-Fenton and UV/H2O2 in the treatment of synthetic textile wastewater containing the Black Biozol UC dye. Among the studied processes, the most efficient was photo-Fenton (H2O2 = 1,500 mg.L-1 and Fe 2+ = 75 mg.L-1, at pH = 3, for color and chemical oxygen demand (COD removals of 95.4% and 73.0%, respectively.

  8. Estudo da degradação de ranitidina via H2O2 eletrogerado/Fenton em um reator eletroquímico com eletrodos de difusão gasosa Study of the ranitidine degradation by H2O2 electrogenerated/Fenton in a electrochemical reactor with gas diffusion electrode

    André A. G. F. Beati


    Full Text Available The study of the electrochemical degradation of the ranitidine was developed using an electrochemical reactor with a gas diffusion electrode (GDE as cathode. The electrolysis experiments was performed at constant current (1 4 A. The process reached a production of 630 mg L-1 of the H2O2 at 7 A. The ranitidine concentrations was reduced in 99.9% (HPLC and chemical oxygen demand (COD was reduced in 86.7% by electro-Fenton.

  9. Influence of operational key parameters on the photocatalytic decolorization of Rhodamine B dye using Fe2+/H2O2/Nb2O5/UV system.

    Hashemzadeh, Fatemeh; Rahimi, Rahmatollah; Gaffarinejad, Ali


    The present research deals with the development of a new heterogeneous photocatalysis and Fenton hybrid system for the removal of color from textile dyeing wastewater as Rhodamine B (RhB) solutions by using Fe(2+)/H2O2/Nb2O5 as a photocatalytic system. The application of this photocatalytic system for the decolorization of dye contaminants is not reported in the literature yet. Different parameters like dye concentration, Nb2O5/Fe(2+) catalyst amount, pH, and H2O2 concentration have been studied. The optimum conditions for the decolorization of the dye were initial concentration of 10 mg L(-1) of dye, pH 4, and Nb2O5/Fe(2+) catalyst concentration of 0.5 g L(-1)/50 mg L(-1). The optimum value of H2O2 concentration for the conditions used in this study was 700 mg L(-1). Moreover, the efficiency of the Nb2O5/photo-Fenton hybrid process in comparison to photo-Fenton alone and a dark Fenton process as a control experiment to decolorize the RhB solution has been investigated. The combination of photo-Fenton and Nb2O5 catalysts has been proved to be the most effective for the treatment of such type of wastewaters. The results revealed that the RhB dye was decolorized in a higher percent (78 %) by the Nb2O5/photo-Fenton hybrid process (Fe(2+)/H2O2/Nb2O5/UV) than by the photo-Fenton process alone (37 %) and dark Fenton process (14 %) after 120 min of treatment. Moreover, the Nb2O5 catalyst as a heterogeneous part of the photocatalytic system was demonstrated to have good stability and reusability.

  10. A comparative study on removal of trace nitrobenzene in water by UV/H2O2 and UV/TiO2/H2O2%UV/H2O2和UV/TiO2/H2O2去除水中微量硝基苯的比较研究

    尹菁菁; 张彭义; 孙莉


    研究比较了UV/H2O2和UV/TiO2/H2O2对水中微量硝基苯的降解效果,并考察了水中常见HCO-3和腐殖酸对硝基苯降解的影响.结果表明,薄膜状TiO2的存在对UV/H2O2降解硝基苯有显著的促进作用,在最佳H2O2投加量2.1 mg/L时,UV/TiO2/H2O2的反应速率常数比UV/H2O2高32.8%;2 min内UV/TiO2/H2O2对硝基苯的去除率达到80%以上.HCO-3和腐殖酸对硝基苯降解有很强的抑制作用,HCO-3和腐殖酸浓度分别为2 mmol/L和3.2 mg/L时,UV/TiO2/H2O2对硝基苯的反应速率常数分别下降84.6%和92.2%.

  11. The electrochemical behaviors of Mg-8Li-3Al-0.5Zn and Mg-8Li-3Al-1.0Zn in sodium chloride solution

    Lv, Yanzhuo; Liu, Min; Xu, Yan; Cao, Dianxue; Feng, Jing


    The electrochemical oxidation behaviors of Mg-8Li-3Al-0.5Zn and Mg-8Li-3Al-1.0Zn electrodes in 0.7 mol L-1 NaCl solution are investigated by methods of potentiodynamic polarization, potentiostatic oxidation, electrochemical impedance spectroscopy and scanning electron microscopy. The phase composition of Mg-8Li-3Al-0.5Zn and Mg-8Li-3Al-1.0Zn alloys is analyzed conducted by X-ray diffraction. The performances of Mg-8Li-3Al-0.5Zn and Mg-8Li-3Al-1.0Zn as the anode of Mg-H2O2 semi fuel cells are determined. The effect of Zn content on the corrosion resistant of these Mg-Li-based alloys is studied. It is found that the Mg-8Li-3Al-0.5Zn electrode has higher discharge activity and less corrosion resistance than that of Mg-8Li-3Al-1.0Zn electrode in 0.7 mol L-1 NaCl solution. The Mg-H2O2 semi fuel cell with Mg-8Li-3Al-0.5Zn anode presents a maximum power density of 100 mW cm-2 at room temperature, which is higher than that of Mg-8Li-3Al-1.0Zn anode (80 mW cm-2). The performance of semi fuel cell with the Mg-8Li-3Al-0.5Zn electrode is better than that with Mg-8Li-3Al-1.0Zn electrode, especially at higher current density (>30 mA cm-2).

  12. Evaluación de matrices vítreas del sistema SiO2-Al2O3-CaO-MgO para fundentes aglomerados a través la basicidad óptica y criterios estructuro-químicos Vitreous matrices evaluation of the SiO2-Al2O3-CaO-MgO system for agglomerate fluxes across the optic basicity and structural-chemical criteria

    Rafael Quintana-Puchol


    Full Text Available La constitución estructural y la naturaleza iónica o molecular de las matrices aluminosilicáticas vítreas en estado líquido están gobernadas fundamentalmente por la relación molar O:(Si+Al, que durante el proceso de soldadura repercuten en sus propiedades termodinámicas, químicas y físicas, así como en sus interacciones con la gota metálica y el baño de soldadura. En fusiones aluminosilicáticas, las interacciones del ión O2-con otras sustancias de la matriz del fundente no aleado y con los metales de aporte y base son de considerable importancia durante la constitución del metal depositado mediante el proceso soldadura automática bajo fundente (SAW. En el presente trabajo, se valora la correspondencia entre los índices de basicidad clásicos y varios índices de basicidad óptica acorde a los criterios Zhang (BO Zh, Duffy e Ingram (BO D y el propuesto en este trabajo por los autores (BO P, así como también entre BO P y la relación molar O:(Si+Al de cada matriz. Todo esto brinda criterios estructuro-químicos de las matrices y de su actividad metalúrgica. A partir de un análisis termodinámico se determina la posible cantidad oxígeno en el metal depositado, con lo cual se estima las posibles propiedades físico-mecánicas del mismo.The structural constitution and ionic or molecular nature of the glassy matrix in liquid aluminosilicates are governed mainly by the molar ratio O: (Si + Al, and during the welding process affect its thermodynamic, chemical and physical properties as well as in their interactions with the metal droplet and the weld pool. In aluminosilicate fusion, O2-ion interactions with other substances from the unalloyed flux matrix and filler metals and base are of considerable importance during the formation of the weld metal by submerged arc welding process (SAW. In this study, assessing the relation between the classical basicity index and several optical basicity indices using criteria according to Zhang

  13. Synthesization of SnO2-modified carbon nanotubes and their application in microbial fuel cell

    Wang, Zi-Bo; Xiong, Shi-Chang; Guan, Yu-Jiang; Zhu, Xue-Qiang


    The aim of this work was to study the synthesization of SnO2-modified carbon nanotubes and their application in microbial fuel cell. With the chemical vapor deposition technique, carbon nanotubes growing in situ on a carbon felt are obtained. A SnO2 sol was applied to the carbon felt to prepare a SnO2-modified carbon nanotubes. X-ray diffraction and energy-dispersive X-ray analysis confirmed that SnO2 existed in the prepared samples. Using the prepared samples as anode electrodes, flexible graphite as cathode, and glucose solution as substrate in microbial fuel cell, the effects of the temperature, substrate concentration, and electrodes on removal rates for chemical oxygen demand and the performance of microbial fuel cell have been analyzed. With substrate concentration of 1500 mg L-1, the microbial fuel cell had an optimal output voltage of 563 mV and a removal rate of 78 % for chemical oxygen demand at 311 K. The composite electrodes are stable and reusable.

  14. [Photocatalytic Oxidation of p-arsanilic Acid by TiO2].

    Xu, Wen-ze; Yang, Chun-feng; Li, Jing; Li, Jian-fei; Liu, Hui-fang; Hu, Cheng-zhi


    The p-arsanilic acid (ASA) is an important organoarsenical compound and its removal is more difficult compared to inorganic arsenic, however, little attention has been paid to the removal of ASA in aqueous environment. The influence of P25 on the adsorption of ASA, effect of P25 dosage, pH and illumination intensity on the photo-catalysis, the production analysis and main mechanism of photo-degradation were investigated in this study. The results showed that in the P25 catalysis process, simulated natural light could degrade ASA into As (V) by oxidation. The total As was reduced to about 0.34 mg x L(-1) within 0.5 h under the following condition: the initial concentration of ASA was 2 mg x L(-1) and the dosage of TiO2 was 1 g x L(-1). The result showed that the removal rate of ASA in acidic conditions was much higher than that in alkaline conditions. The optimal strength of light was 68.5 mW x Cm(-2). Hydroxide radical played a major role in photocatalytic oxidation of ASA by P25.

  15. Solubility of BaS in BaO-BaF2 slag and the Influence of FeOx, SiO2, Cr2O3, BaCI2, CaO, and MgO on the sulfide capacity of this system

    Rachev, Ivan P.; Tsukihashi, Fumitaka; Sano, Nobuo


    The influence of SiO2, FeOx, Cr2O3, BaCl2, CaO, and MgO on the sulfide capacity of the BaO-BaF2 system was measured at 1473 K, using a gas-slag-metal equilibration technique. It was found that the substitution of BaF2 by SiO2, FeOx, Cr2O3, and BaCl2 decreases the sulfide capacity of the BaO-BaF2 system. Similar results were obtained for the carbonate capacity. The CaO-saturated BaO-BaF2 flux, however, was found to have slightly higher sulfide and carbonate capacities than the pure BaO-BaF2 flux. The solubility of CaO increased with increasing BaF2 content and was 18 mol pet in BaF2 at 1473 K. The solubility of MgO in the BaO-BaF2 system at the same temperature is very low, and it has no effect on the sulfide and carbonate capacities. The solubility of BaS in the BaO-BaF2 system was also measured at 1473 K and had its maximum for the slag containing 40 mass pet BaO. The activity of BaO in the system was calculated from those data.

  16. Azul de metileno imobilizado na celulose/TiO2 e SiO2/TiO2: propriedades eletroquímicas e planejamento fatorial

    Scotti Rodrigo


    Full Text Available The electrochemical properties of methylene blue immobilized on cellulose/TiO2 and mixed oxide SiO2/TiO2 matrices were investigated by means of cyclic voltammetry. The electron mediator property of the methylene blue was optimized using a factorial design, consisting of four factors in two levels. The experimental observations and data analyses on the system indicate that the lowest peak separation occurs for Sil/TiOAM, 1.0 mol L-1 KCl solution and 20 mV s-1 scan rate, while values of current ratio closest to unity were found for Cel/TiOAM independent of electrolyte concentration, 0.2 or 1.0 mol L-1, and scan rate, 20 mV s-1 or 60 mV s-1.

  17. Effects of fly ash and boric acid on Y2O3-stabilized tetragonal ZrO2 dispersed with MgAl2O4: An experimental study on rat subcutaneous tissue.

    Ergun, Gulfem; Guru, Metin; Egilmez, Ferhan; Cekic-Nagas, Isil; Yilmaz, Dervis


    The aim of this study was to evaluate the subcutaneous tissue reaction around zirconia-based materials. Forty-eight male Wistar Albino rats were used in this study. Disk-shaped (1mm height and 5mm diameter) samples composed of 67% spinel (MgAl2O4), 27% tetragonal zirconia polycrystal, 4% (m/m) fly ash and 2% (m/m) boric acid were inserted into dorsal muscles of rats. After 1, 4, 8 and 16 weeks, the animals were sacrificed and zirconia materials were removed with the surrounding tissue. Tissue sections were made with a microtome and then stained with hematoxylin and eosin. Sections were evaluated for the intensity of inflammation. Additionally, the somatic and visceral lymph nodes were evaluated. Data were submitted to one-way analysis of variance (ANOVA) and Tukey HSD tests at a significant level of p < 0.05. There were statistically significant differences between mean inflammatory scores in different experimental periods (p <0.05). In addition, the inflammatory reaction decreased over time. The tested materials had no damaging effect on the rat lymph nodes and did not have a toxic action on the internal organs. Therefore, zirconia polycrystal tested in the present study may offer a promising treatment alternative after further mechanical and biological studies are performed. Copyright © 2014 Elsevier GmbH. All rights reserved.

  18. Selective Crystallization Behavior of CaO-SiO2-Al2O3-MgO-FetO-P2O5 Steelmaking Slags Modified through P2O5 and Al2O3

    Wang, Zhanjun; Sun, Yongqi; Sridhar, Seetharaman; Zhang, Mei; Guo, Min; Zhang, Zuotai


    In this study, the selective crystallization behavior of synthetic FetO-rich steelmaking slags modified by P2O5 and Al2O3 additions was explored using non-isothermal differential scanning calorimetry, X-ray diffraction, and field emission scanning electron microscopy techniques. Continuous cooling transformation diagrams of Fe-enriched and P-enriched phases were constructed. It was found that P2O5 addition can suppress the crystallization due to the increasing viscosity caused by increasing degree of polymerization; however, an increase of Al2O3 content accelerated the precipitation of dystectic MgFeAlO4, copolymerized by [AlO4]-tetrahedra and [FeO4]-tetrahedra units. It was also noted that the content of phosphorus in P-enriched phase can reach a high value as 28.71 wt pct for the slags modified by 15.17 wt pct Al2O3. The non-isothermal crystallization kinetics derived from activation energy and the structure of the slags explained by Raman spectra were further analyzed, which was well in accordance with the above analysis.

  19. Removal of aqueous chromate [Cr(VI)] through photocatalysis by using TiO2-coated silica granules.

    Saeki, Kazutoshi; Kadono, Mayumi; Nabeshima, Akiko


    The aim of this study was to determine the optimal conditions for the treatment of chromate [Cr(VI)]- contaminated water by UV photocatalysis using synthesized TiO(2)-coated silica granules (phi 1.7-4.0 mm) containing 12.4% of TiO(2) in a batch method. The effect of the volume of the solution on Cr(VI) removal was investigated in the photocatalysis process by using 10 g of TiO(2)-coated silica granules in water samples with a constant initial Cr(VI) concentration of 5 mg L(-1). In a 10-mL solution, Cr(VI) concentrations were observed to decrease below the detection limit (photocatalysis process to remove Cr(VI) using 10 g of TiO(2)-coated granules did not fluctuate with the solution volume for samples with a constant initial Cr(VI) concentration. The lower the initial pH of the solution, the greater was the amount of Cr(VI) removed from the solution. The addition of chloride ions to the solutions accelerated the removal of Cr(VI) by UV photocatalysis. Ten grams of TiO(2)-coated silica granules were repeatedly used to the 300-min treatment of the Cr(VI) solution (10 mL, 6 mg L(-1)) till seven cycles. After four cycles of UV photocatalysis, Cr(VI) was completely removed from all the solutions. After the fifth cycle, the Cr(VI) removal capacity of the UV photocatalysis process decreased with the repeated use of the catalyst.

  20. Voice and Narrative in L1 Writing

    Krogh, Ellen; Piekut, Anke


    This paper investigates issues of voice and narrative in L1 writing. Three branches of research are initial-ly discussed: research on narratives as resources for identity work, research on writer identity and voice as an essential aspect of identity, and research on Bildung in L1 writing....... Subsequently, two empirical investigations of L1 writing in a Danish upper secondary school are presented. The first study is based on longitudinal interview data and analyses one student’s experience as an L1 writer in the transition from lower secondary to upper secondary school. A high-achieving student...... in lower secondary L1, she found that her previous writing strategies were not rewarded in upper secondary school. In the second empiri-cal study, two upper-secondary exam papers are investigated, with a focus on their approaches to exam genres and their use of narrative resources to address issues...

  1. One-Time Addition of Nano-TiO2 Triggers Short-Term Responses in Benthic Bacterial Communities in Artificial Streams.

    Ozaki, Alexandra; Adams, Erin; Binh, Chu Thi Thanh; Tong, Tiezheng; Gaillard, Jean-François; Gray, Kimberly A; Kelly, John J


    Nano-TiO2 is an engineered nanomaterial whose production and use are increasing rapidly. Hence, aquatic habitats are at risk for nano-TiO2 contamination due to potential inputs from urban and suburban runoff and domestic wastewater. Nano-TiO2 has been shown to be toxic to a wide range of aquatic organisms, but little is known about the effects of nano-TiO2 on benthic microbial communities. This study used artificial stream mesocosms to assess the effects of a single addition of nano-TiO2 (P25 at a final concentration of 1 mg l(-1)) on the abundance, activity, and community composition of sediment-associated bacterial communities. The addition of nano-TiO2 resulted in a rapid (within 1 day) decrease in bacterial abundance in artificial stream sediments, but bacterial abundance returned to control levels within 3 weeks. Pyrosequencing of partial 16S rRNA genes did not indicate any significant changes in the relative abundance of any bacterial taxa with nano-TiO2 treatment, indicating that nano-TiO2 was toxic to a broad range of bacterial taxa and that recovery of the bacterial communities was not driven by changes in community composition. Addition of nano-TiO2 also resulted in short-term increases in respiration rates and denitrification enzyme activity, with both returning to control levels within 3 weeks. The results of this study demonstrate that single-pulse additions of nano-TiO2 to aquatic habitats have the potential to significantly affect the abundance and activity of benthic microbial communities and suggest that interactions of TiO2 nanoparticles with environmental matrices may limit the duration of their toxicity.

  2. [Study on UV and H2O2 combined inactivation of E. coli in drinking water].

    Zhang, Yi-Qing; Zhou, Ling-Ling; Zhang, Yong-Ji


    The inactivation effect of E. coli with both UV irradiation and hydrogen peroxide disinfection individually and in different combination modes was investigated. The results showed that hydrogen peroxide alone caused hardly any inactivation of E. coli. Only 0.02 lg inactivation was achieved by hydrogen peroxide with concentration of 20 mg x L(-1) and contact time of 30 min. UV irradiation was able to inactivate E. coli to a certain extent. The inactivation reached 4.51 lg at a UV dose of 10 mJ x cm(-2). The combination of UV and H2O2 could significantly improve the inactivation effect and the different combination modes affected the inactivation effect. The inactivation effect of UV-H2O2 was better than that of H2O2 -UV. The inactivation was increased by 0.09, 0.35, 0.38, 0.68 lg and 0.01, 0.07, 0.14, 0.53 lg when compared to the treatment with solely UV irradiation, respectively, at UV dose of 5 mJ x cm(-2) with hydrogen peroxide at contact time of 2.5, 5, 10, 20 minutes. UV/H2O2 achieved better results than sequential disinfection. The inactivation was enhanced by 0.43 lg and 0.58 lg when compared to UV-H2O2 and H2O2-UV, respectively, at UV dose of 5 mJ x cm(-2) with hydrogen peroxide at contact time of 20 minutes. The inactivation of E. coli increased with the enhancement of UV radiation intensity.

  3. [Photocatalytic Degradation of Perfluorooctanoic Acid by Pd-TiO2 Photocatalyst].

    Liu, Qing; Yu, Ze-bin; Zhang, Rui-han; Li, Ming-jie; Chen, Ying; Wang, Li; Kuang, Yu; Zhang, Bo; Zhu, You-hui


    Perfluorooctanoic acid (PFOA) is a new persistent organic pollutant which has got global concern for its wide distribution, high bioaccumulation and strong biological toxicity. In present study, the photocatalytic degradation of PFOA using palladium doped TiO2 (Pd-TiO2) prepared by chemical reduction method was investigated. The photocatalysts were characterized by XRD, FESEM and UV-vis DRS and were used for PFOA degradation under 365 nm UV irradiation. The results indicated that the grain size of TiO2 was smaller while the specific surface area increased and the absorption of ultraviolet light also enhanced after using chemical reduction method, but all these changes had no influence on PFOA degradation. However, the degradation was significantly enhanced because of the deposition of Pd, the fluoride concentration of PFOA was 6.62 mg x L(-1) after 7 h irradiation which was 7.3 times higher than that of TiO2 (P25). Experiments with the addition of trapping agent and nitrogen indicated that *OH played an important role in PFOA degradation while the presence of O2 accelerated the degradation. The main intermediate products of photocatalytic degradation of PFOA were authenticated by an ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry systems (UPLC-QTOF-MS). The probable photocatalytic degradation mechanism involves h+ attacking the carboxyl of PFOA and resulting in decarboxylation. The produced *CnF(2n +1) was oxidized by *OH underwent defluorinetion to form shorter-chain perfluorinated carboxylic acids. The significant enhancement of PFOA degradation can be ascribed to the palladium deposits, acting as electron traps on the Pd-TiO2 surface, which facilitated the transfer of photogenerated electrons and retarded the accumulation of electrons.

  4. Effectiveness evaluation of glyphosate oxidation employing the H(2)O(2)/UVC process: toxicity assays with Vibrio fischeri and Rhinella arenarum tadpoles.

    Junges, Celina M; Vidal, Eduardo E; Attademo, Andrés M; Mariani, Melisa L; Cardell, Leandro; Negro, Antonio C; Cassano, Alberto; Peltzer, Paola M; Lajmanovich, Rafael C; Zalazar, Cristina S


    The H(2)O(2)/UVC process was applied to the photodegradation of a commercial formulation of glyphosate in water. Two organisms (Vibrio fischeri bacteria and Rhinella arenarum tadpoles) were used to investigate the toxicity of glyphosate in samples M(1,) M(2), and M(3) following different photodegradation reaction times (120, 240 and 360 min, respectively) that had differing amounts of residual H(2)O(2). Subsamples of M(1), M(2), and M(3) were then used to create samples M(1,E), M(2,E) and M(3,E) in which the H(2)O(2) had been removed. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities were measured in tadpoles to determine possible sub-lethal effects. In V. fischeri, M(1,E), which was collected early in the photodegradation process, caused 52% inhibition, while M(3,E), which was collected at the end of the photodegradation process, caused only 17% inhibition. Survival of tadpoles was 100% in samples M(2), M(3), and in M(1,E), M(2,E) and M(3,E). The lowest percentages of enzymatic inhibition were observed in samples without removal of H(2)O(2): 13.96% (AChE) and 16% (BChE) for M(2), and 24.12% (AChE) and 13.83% (BChE) for M(3). These results show the efficiency of the H(2)O(2)/UVC process in reducing the toxicity of water or wastewater polluted by commercial formulations of glyphosate. According to the ecotoxicity assays, the conditions corresponding to M(2) (11 ± 1 mg a.e. L(-1) glyphosate and 11 ± 1 mg L(-1) H(2)O(2)) could be used as a final point for glyphosate treatment with the H(2)O(2)/UV process.

  5. Synergetic adsorption and photocatalytic degradation of pollutants over 3D TiO2-graphene aerogel composites synthesized via a facile one-pot route.

    Zhang, Jing-Jie; Wu, Yu-Hui; Mei, Jin-Ya; Zheng, Guang-Ping; Yan, Ting-Ting; Zheng, Xiu-Cheng; Liu, Pu; Guan, Xin-Xin


    A series of composites consisting of anatase TiO2 nanocrystals and three-dimensional (3D) graphene aerogel (TiO2-GA) were self-assembled directly from tetrabutyl titanate and graphene oxides via a one-pot hydrothermal process. TiO2 was found to uniformly distribute inside the 3D network of GA in the resulting composites with large surface areas (SBET > 125 m(2) g(-1)) and high pore volumes (Vp > 0.22 cm(3) g(-1)). In comparison with GA and TiO2, the composites possessed much higher adsorption capacities and visible light photocatalytic activity in the degradation of rhodamine B (RhB). With an initial concentration of 20.0 mg L(-1) of RhB, the adsorptive decolourization of RhB was as high as 95.1% and the total decolourization value reached up to 98.7% under visible light irradiation over 5.0 mg of the resulting composites. It was elucidated that the physical and chemical properties of the TiO2-GA composites could be ascribed to their unique 3D nanoporous structure with high surface areas and the synergetic activities of graphene nanosheets and TiO2 nanoparticles.

  6. Antibody fragments directed against different portions of the human neural cell adhesion molecule L1 act as inhibitors or activators of L1 function.

    Yan Wang

    Full Text Available The neural cell adhesion molecule L1 plays important roles in neuronal migration and survival, neuritogenesis and synaptogenesis. L1 has also been found in tumors of different origins, with levels of L1 expression correlating positively with the metastatic potential of tumors. To select antibodies targeting the varied functions of L1, we screened the Tomlinson library of recombinant human antibody fragments to identify antibodies binding to recombinant human L1 protein comprising the entire extracellular domain of human L1. We obtained four L1 binding single-chain variable fragment antibodies (scFvs, named I4, I6, I13, and I27 and showed by enzyme-linked immunosorbent assay (ELISA that scFvs I4 and I6 have high affinity to the immunoglobulin-like (Ig domains 1-4 of L1, while scFvs I13 and I27 bind strongly to the fibronectin type III homologous (Fn domains 1-3 of L1. Application of scFvs I4 and I6 to human SK-N-SH neuroblastoma cells reduced proliferation and transmigration of these cells. Treatment of SK-N-SH cells with scFvs I13 and I27 enhanced cell proliferation and migration, neurite outgrowth, and protected against the toxic effects of H(2O(2 by increasing the ratio of Bcl-2/Bax. In addition, scFvs I4 and I6 inhibited and scFvs I13 and I27 promoted phosphorylation of src and Erk. Our findings indicate that scFvs reacting with the immunoglobulin-like domains 1-4 inhibit L1 functions, whereas scFvs interacting with the fibronectin type III domains 1-3 trigger L1 functions of cultured neuroblastoma cells.

  7. Avaliação do molhamento da matriz de um concreto refratário (Al2O3-SiC-SiO2-C por escórias sintéticas contendo distintos teores de MgO Wetting evaluation of a refractory castable matrix (Al2O3-SiC-SiO2-C by synthetic slags containing different amounts of MgO

    A. P. Luz


    Full Text Available O comportamento de espalhamento de quatro escórias sintéticas foi investigado pelo método da gota séssil, quando em contato com a matriz de um concreto refratário contendo alto teor de carbono e carbeto de boro como agente antioxidante. A evolução do molhamento do sólido foi monitorada a 1450, 1550 e 1650 ºC por 1800 s. Além disso, simulações termodinâmicas foram efetuadas, usando o programa FactSage®, visando promover um maior entendimento das reações químicas que podem ocorrer na interface dos materiais avaliados. Foi observado que a composição química do líquido afetou diretamente o espalhamento deste e quanto maior o teor de MgO na composição da escória, maiores foram os valores do ângulo de contato entre líquido e sólido. No entanto, em altas temperaturas e tempos prolongados, foram verificadas a formação de bolhas na superfície do líquido e a infiltração das escórias nos poros do refratário. Estes fatores afetaram negativamente e tornaram menos conclusivos os dados coletados nos ensaios propostos, apontando que ainda são necessários aperfeiçoamentos da técnica de molhabilidade para a avaliação de materiais complexos, tais como os concretos refratários.The wetting behavior of four synthetic slags was investigated by the sessile drop technique, when in contact with the matrix of a high carbon containing refractory castable. The wetting evolution was monitored at 1450, 1550 and 1650 ºC during 1800 s. Besides that, thermodynamic simulations were carried out using the FactSage® software aiming to attain a better understanding of the chemical reactions at the materials interface. It was observed that the chemical composition of the liquid directly affected its spreading and the higher the MgO content in the slag composition, the higher contact angles values were attained. However, the formation of bubbles on the liquid surface and the slags infiltration in the refractory pores at high temperatures and

  8. UV-H2O2 based AOP and its integration with biological activated carbon treatment for DBP reduction in drinking water.

    Toor, Ramn; Mohseni, Madjid


    The presence of disinfection byproducts (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs) in drinking water is of great concern due to their adverse effects on human health. Emerging regulation limiting the concentration of DBPs in drinking water has increased demands for technologies and processes which reduce the formation of DBPs in drinking water. In this study, UV-H2O2 based advance oxidation process (AOP) was used to treat raw surface water. Experiments were conducted using low pressure mercury vapor UV lamps in collimated beam and flow-through annular photoreactors. The effect of UV fluence (0-3500 mJ cm(-2)) and hydrogen peroxide concentration (0-23 mg l(-1)) in reducing the concentration of THMs and HAAs was examined. The UV-H2O2 AOP was then coupled with a downstream biological activated carbon (BAC) treatment to assess the synergetic benefits of combining the two treatments. It was observed that UV-H2O2 AOP was only effective at reducing DBPs at UV fluences of more than 1000 mJ cm(-2) and initial H2O2 concentrations of about or greater than 23 mg l(-1). However, the combined AOP-BAC treatment showed significant reductions of 43%, 52%, and 59% relative to untreated raw water for DBPs, TOC, and UV254, respectively.

  9. Mixed ZnO-TiO2 Suspended Solution as an Efficient Photocatalyst for Decolonization of a Textile Dye from Waste Water

    Mohammad Ali Mooji


    Full Text Available Introduction: Textile industries produce large volume of colored dye effluents which are toxic and removal of dyes from wastewater is a significant environmental issue. Advanced oxidation process (AOPs is alternative method for the complete degradation many organic pollutants. ZnO and TiO2 are important photocatalysts with high catalytic activity that have attracted much research attention. Material and Methods: Mixed ZnO/TiO2 was prepared with mixing of ZnO and TiO2 (20, 40, 60, 80 % (w/w. 20 mL of dye solution (80 mgL-1 for DB71 containing the appropriate quantity of photocatalyst was magnetically stirred under UV irradiation. Photocatalytic study was carried out to evaluate the effect of UV (400 W, ZnO/TiO2 weight percent (20, 40, 60, 80 % (w/w, pH (2.3 – 9.2, irradiation time of (10 – 70 min, initial dye concentration of (10, 40, 80 mg/L and ZnO/TiO2 dosage of (0.2 – 1.6 g/L on removal of dye. Dye concentration was monitored spectrophotometrically by measuring the dye absorbance at 285 nm. Results: In comparison with TiO2 or ZnO as photocatalyst, mixed photocatalyst (ZnO/TiO2 is more efficient catalyst for degradation of dye under UV irradiation Results show that approximately 90 % of Direct Blue 71 has been eliminated after 70 minutes and optimized condition ((pH = 6.4, ZnO/TiO2 (50% w/w, 1.25 g/L. Experiments showed, the noticeable decolorization of dye solution can be done without any oxidation agent with mixed ZnO/TiO2 photocatalyst.

  10. Selective adsorption of thiophenic compounds from fuel over TiO2/SiO2 under UV-irradiation.

    Miao, Guang; Ye, Feiyan; Wu, Luoming; Ren, Xiaoling; Xiao, Jing; Li, Zhong; Wang, Haihui


    This study investigates selective adsorption of thiophenic compounds from fuel over TiO2/SiO2 under UV-irradiation. The TiO2/SiO2 adsorbents were prepared and then characterized by N2 adsorption, X-ray diffraction and X-ray photoelectron spectroscopy. Adsorption isotherms, selectivity and kinetics of TiO2/SiO2 were measured in a UV built-in batch reactor. It was concluded that (a) with the employment of UV-irradiation, high organosulfur uptake of 5.12 mg/g was achieved on the optimized 0.3TiO2/0.7SiO2 adsorbent at low sulfur concentration of 15 ppmw-S, and its adsorption selectivity over naphthalene was up to 325.5; (b) highly dispersed TiO2 served as the photocatalytic sites for DBT oxidation, while SiO2 acted as the selective adsorption sites for the corresponding oxidized DBT using TiO2 as a promoter, the two types of active sites worked cooperatively to achieve the high adsorption selectivity of TiO2/SiO2; (c) The kinetic rate-determining step for the UV photocatalysis-assisted adsorptive desulfurization (PADS) over TiO2/SiO2 was DBT oxidation; (d) consecutive adsorption-regeneration cycles suggested that the 0.3TiO2/0.7SiO2 adsorbent can be regenerated by acetonitrile washing followed with oxidative air treatment. This work demonstrated an effective PADS approach to greatly enhance adsorption capacity and selectivity of thiophenic compounds at low concentrations for deep desulfurization under ambient conditions.

  11. Influence of electrical parameters on H2O2 generation in DBD non-thermal reactor with water mist

    Xu, Di; Xiao, Zehua; Hao, Chunjing; Qiu, Jian; Liu, Kefu


    A dielectric barrier discharge (DBD) reactor is introduced to generate H2O2 by non-thermal plasma with a mixture of oxygen and water mist produced by an ultrasonic atomizer. The results of our experiment show that the energy yield and concentration of the generated H2O2 in the pulsed discharge are much higher than that in AC discharge, due to its high energy efficiency and low heating effect. Micron-sized liquid droplets produced by an ultrasonic atomizer in water mist have large specific surface area, which greatly reduces mass transfer resistance between hydroxyl radicals and water liquids, leading to higher energy yield and H2O2 concentration than in our previous research. The influence of applied voltage, discharge frequency, and environmental temperature on the generated H2O2 is discussed in detail from the viewpoint of the DBD mechanism. The H2O2 concentration of 30 mg l-1, with the energy yield of 2 g kW-1h-1 is obtained by pulsed discharge in our research.

  12. Influence of two types of organic matter on interaction of CeO2 nanoparticles with plants in hydroponic culture.

    Schwabe, Franziska; Schulin, Rainer; Limbach, Ludwig K; Stark, Wendelin; Bürge, Diane; Nowack, Bernd


    An important aspect in risk assessment of nanoparticles (NPs) is to understand their environmental interactions. We used hydroponic plant cultures to study nanoparticle-plant-root interaction and translocation and exposed wheat and pumpkin to suspensions of uncoated CeO2-NP for 8d (primary particle size 17-100 nm, 100 mg L(-1)) in the absence and presence of fulvic acid (FA) and gum arabic (GA) as representatives of different types of natural organic matter. The behavior of CeO2-NPs in the hydroponic solution was monitored regarding agglomeration, sedimentation, particle size distribution, surface charge, amounts of root association, and translocation into shoots. NP-dispersions were stable over 8d in the presence of FA or GA, but with growing plants, changes in pH, particle agglomeration rate, and hydrodynamic diameter were observed. None of the plants exhibited reduced growth or any toxic response during the experiment. We found that CeO2-NPs translocated into pumpkin shoots, whereas this did not occur in wheat plants. The presence of FA and GA affected the amount of CeO2 associated with roots (pure>FA>GA) but did not affect the translocation factor. Additionally, we could confirm via TEM and SEM that CeO2-NPs adhered strongly to root surfaces of both plant species. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Highly efficient electrochemical degradation of perfluorooctanoic acid (PFOA) by F-doped Ti/SnO2 electrode.

    Yang, Bo; Jiang, Chaojin; Yu, Gang; Zhuo, Qiongfang; Deng, Shubo; Wu, Jinhua; Zhang, Hong


    The novel F-doped Ti/SnO2 electrode prepared by SnF4 as the single-source precursor was used for electrochemical degradation of aqueous perfluorooctanoic acid (PFOA). Higher oxidation reactivity and significantly longer service life were achieved for Ti/SnO2-F electrode than Ti/SnO2-X (X=Cl, Br, I, or Sb) electrode, which could decomposed over 99% of PFOA (50 mL of 100 mg L(-1)) within 30-min electrolysis. The property of Ti/SnO2-F electrode and its electrooxidation mechanism were investigated by XRD, SEM-EDX, EIS, LSV, and interfacial resistance measurements. We propose that the similar ionic radii of F and O as well as strong electronegativity of F caused its electrochemical stability with high oxygen evolution potential (OEP) and smooth surface to generate weakly adsorbed OH. The preparation conditions of electrode were also optimized including F doping amount, calcination temperature, and dip coating times, which revealed the formation process of electrode. Additionally, the major mineralization product, F(-), and low concentration of shorter chain perfluorocarboxylic acids (PFCAs) were detected in solution. So the reaction pathway of PFOA electrooxidation was proposed by intermediate analysis. These results demonstrate that Ti/SnO2-F electrode is promising for highly efficient treatment of PFOA in wastewater.

  14. L1-norm minimization for quaternion signals

    Wu, Jiasong; Wang, Xiaoqing; Senhadji, Lotfi; Shu, Huazhong


    The l1-norm minimization problem plays an important role in the compressed sensing (CS) theory. We present in this letter an algorithm for solving the problem of l1-norm minimization for quaternion signals by converting it to second-order cone programming. An application example of the proposed algorithm is also given for practical guidelines of perfect recovery of quaternion signals. The proposed algorithm may find its potential application when CS theory meets the quaternion signal processing.

  15. Fotocatálise heterogênea com TiO2 para oxidação de arsênio e sua remoção de águas por coprecipitação com sulfato férrico Heterogeneous photocatalysis with TiO2 for the oxidation of arsenic and its removal from water by coprecipitation with ferric sulfate

    Gisele Mendes


    Full Text Available The oxidation of arsenic (As(III to As(V in water samples was performed by heterogeneous photocatalysis using a TiO2 film immobilized inside a photochemical reactor. After oxidation, As(V was removed from the water samples by coprecipitation with ferric sulfate. The final conditions of oxidation and arsenic removal (TiO2 film prepared with a suspension: 10% (w/v; pH: 7.0; oxidation time: 30 min and Fe3+ concentration: 50 mg L-1 were applied in natural water samples which were supplemented with 1.0 mg L-1 of As(III to verify the influence of the matrix. After treatment, more than 99% of arsenic was removed from the water.

  16. Heat treatment effects on the characteristics and sonocatalytic performance of TiO2 in the degradation of organic dyes in aqueous solution.

    Abdullah, Ahmad Zuhairi; Ling, Pang Yean


    The ambient sonocatalytic degradation of congo red, methyl orange, and methylene blue by titanium dioxide (TiO(2)) catalyst at initial concentrations between 10 and 50mg/L, catalyst loadings between 1.0 and 3.0mg/L and hydrogen peroxide (H(2)O(2)) concentrations up to 600 mg/L is reported. A 20 kHz ultrasonic processor at 50 W was used to accelerate the reaction. The catalysts were exposed to heat treatments between 400 and 1000 degrees C for up to 4h to induce phase change. Sonocatalysts with small amount of rutile phase showed better sonocatalytic activity but excessive rutile phase should be avoided. TiO(2) heated to 800 degrees C for 2h showed the highest sonocatalytic activity and the degradation of dyes was influenced by their chemical structures, chemical phases and characteristics of the catalysts. Congo red exhibited the highest degradation rate, attributed to multiple labile azo bonds to cause highest reactivity with the free radicals generated. An initial concentration of 10mg/L, 1.5 g/L of catalyst loading and 450 ppm of H(2)O(2) gave the best congo red removal efficiency of above 80% in 180 min. Rate coefficients for the sonocatalytic process was successfully established and the reused catalyst showed an activity drop by merely 10%.

  17. Kinetics and Reactive Species Analysis of Dimetridazole Degradation by TiO2%TiO2降解迪美唑的动力学及活性物质分析

    陈冬梅; 喻泽斌; 孙蕾; 黄俊; 高丽红; 李明洁


    兽类抗生素迪美唑是一种新兴的污染物质,对环境和人类健康具有潜在危害.以紫外光为光源,以TiO2为催化剂,对其进行光催化降解,考察了溶液pH值、TiO2投加量、溶液的初始浓度等影响因素对迪美唑降解效果的影响.结果表明,在TiO2投加量为1g·L-1,迪美唑初始浓度为40 mg·L-1,溶液pH为11的最优条件下反应90 min后,迪美唑的去除率为90%,反应速率为0.025 7 min-.反应符合伪一级动力学模型.光催化降解迪美唑有两个途径:一是·OH氧化过程,二是e-还原过程.

  18. Catalytic wet air oxidation of phenol over CeO2-TiO2 catalyst in the batch reactor and the packed-bed reactor.

    Yang, Shaoxia; Zhu, Wanpeng; Wang, Jianbing; Chen, Zhengxiong


    CeO2-TiO2 catalysts are prepared by coprecipitation method, and the activity and stability in the catalytic wet air oxidation (CWAO) of phenol are investigated in a batch reactor and packed-bed reactor. CeO2-TiO2 mixed oxides show the higher activity than pure CeO2 and TiO2, and CeO2-TiO2 1/1 catalyst displays the highest activity in the CWAO of phenol. In a batch reactor, COD and TOC removals are about 100% and 77% after 120 min in the CWAO of phenol over CeO2-TiO2 1/1 catalyst at reaction temperature of 150 degrees C, the total pressure of 3 MPa, phenol concentration of 1000 mg/L, and catalyst dosage of 4 g/L. In a packed-bed reactor using CeO2-TiO2 1/1 particle catalyst, over 91% COD and 80% TOC removals are obtained at the reaction temperature of 140 degrees C, the air total pressure of 3.5 MPa, the phenol concentration of 1000 mg/L for 100 h continue reaction. Leaching of metal ions of CeO2-TiO2 1/1 particle catalyst is very low during the continuous reaction. CeO2-TiO2 1/1 catalyst exhibits the excellent activity and stability in the CWAO of phenol.

  19. Optical performance study of Sr2ZnSi2O7:Eu2+,Dy3+, SrAl2O4:Eu2+,Dy3+and Y2O2S:Eu3+,Mg2+,Ti4+ ternary luminous fiber

    晋阳; 龙啸云; 朱亚楠; 葛明桥


    In this study, down-conversion fluorescent powder of Sr2ZnSi2O7:Eu2+,Dy3+, SrAl2O4:Eu2+,Dy3+ and Y2O2S:Eu3+,Mg2+,Ti4+, which were the common three primary colors materials with long afterglow, were synthesized by high temperature solid state method. The blends of rare earth (RE) luminescent materials have been of interest to reinvest the luminescent characteristics of polyethylene terephtahalate (PET) luminous fiber. The scanning electron microscopy (SEM) and an inversion fluorescence microscope were used to characterize the surface morphology and the dispersion of inclusion. Through analysis of microcosmic morphology, three typical dispersions of luminescent particles were summarized. The X-ray diffraction indicated that the phase structure of fiber samples and crystal structure of luminescence materials kept complete after prilling and spinning. From the fluorescence spectra and CIE 1931 co-ordinates, it could be found that different combinations of luminous fibers were desired to obtain divers colors emission luminous fi-ber. And the fiber samples were a light sensation which could induct different excitation wavelengths and convert it down to different colors. The afterglow decay curve and its differential curve were summarized indicating the three decay stages. The decay curve and decay rate curve showed that the contents of Sr2ZnSi2O7:Eu2+,Dy3+, SrAl2O4:Eu2+,Dy3+ and Y2O2S:Eu3+,Mg2+,Ti4+ had obvious in-fluence on the afterglow of fiber samples.

  20. Degradation of methylene blue with H2O2 activated by peroxidase-like Fe3O4 magnetic nanoparticles.

    Jiang, Jizhou; Zou, Jing; Zhu, Lihua; Huang, Lei; Jiang, Haipeng; Zhang, Yuanxiao


    Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) were successfully prepared through an advanced reverse co-precipitation method under the assistance of ultrasound irradiation. The structure and size distribution were characterized by X-ray powder diffraction (XRD), laser particle size analyzer (LPSA), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. The magnetic properties of Fe3O4 nanoparticles were measured by the vibrating sample magnetometer (VSM). Such Fe3O4 MNPs were used as a peroxidase mimetic to remove the dye pollutant methylene blue (MB) in the presence of H2O2. Some important reaction parameters were optimized to improve the degradation of MB. It was observed that the degradation efficiency of 10 mg L(-1) MB was above 96% over 0.62 g L(-1) Fe3O4 MNPs within 0.30 mmol L(-1) H2O2 at pH 4.85 and temperature 25 degrees C in 15 min, being superior to the previous reports.

  1. 电气石对TiO2光催化活性的影响研究%On Influence of Tourmaline on TiO2 Photo- catalytic Activity

    林朋; 顾声音; 何登良; 程紫璇


    采用电气石负载TiO2可见响应光催化功能材料,以甲基橙为降解脱色对象,考查了不同电气石加入量、催化剂质量、pH以及甲基橙浓度对光催化活性的影响。实验结果表明:电气石的加入有利于TiO2光催化活性的提高,其中电气石掺杂量为1%为最佳比例;催化剂加入量的增加有助于甲基橙的降解;在催化剂质量为0.2 g的条件下,甲基橙浓度为40 mg·L^-1光催化降解甲基橙的效果最好。%This paper is to introduce an experiment of influences of different amounts of tourmalines, qualities of catalyzers, pH and methyl orange on photo -catalytic activity, by employing photochemical catalysis materials of TiO2 toumaline and methyl orange as target of degrading decolorizafion. The results show that tourmaline is helpful for TiO2 photo -catalysts to improve photo -catalytic activity, for which 1% tourmaline doping ratio is the best; the increase of catalyst will promote the degradation of methyl orange. Photo - catalytic degradation of methyl orange as the effect of the catalyst under conditions of 0.2 g methyl orange concentration of 40 mg· L^-1 is the best.

  2. 二氧化氯/TiO2光催化氧化降解碱性品红模拟废水及反应机理%Investigation of Chlorine Dioxide/TiO2 Photocatalytic Oxidative Degradation of Simulated Wastewater Containing Fuchsine and Its Reaction Mechanism

    施来顺; 王晓美


    The photocatalyst TiO2 was prepared by dipping-calcination method using silica gel as catalyst support.The chlorine dioxide/TiO2 photocatalyst was used for the photocatalytic oxidation of simulated fuchsine wastewater.The degradation effect of fuchsine by the combination of chlorine dioxide,TiO2 photocatalyst and UV irradiation was confirmed by comparison test.The optimum treatment conditions were as follows:the volume of wastewater containing 150 mg·L-1 fuchsine was 50 mL;ClO2 concentration was 6.14 mg·L-1,pH value was 5.0;the distance between UV lamp and flask was 20 cm;UV irradiation time was 13 min;and photocatalyst dosage was 10 g·L-1.The removal efficiency of fuchsine could reach 80%,compared with 46% of chlorine dioxide chemical oxidation.With UV-vis and FT IR analysis technique,the intermediates in the degradation process were obtained.Fuchsine was degradated into quinone and carboxylic acid,and finally changed into carbon dioxide and water during the photocatalytic oxidation.The degradation reaction mechanism of fuchsine by chlorine dioxide/TiO2 photocatalytic oxidation was proposed.%以硅胶为载体,采用浸渍-焙烧法制备了TiO2光催化剂,并将其用于二氧化氯/TiO2光催化氧化降解碱性品红模拟废水.经对比实验验证了ClO2/TiO2光催化剂/UV照射对碱性品红的氧化降解作用.50 mL质量浓度为150 mg.L-1的碱性品红模拟废水,在pH值为5.0,二氧化氯质量浓度6.14 mg.L-1和10 g.L-1光催化剂条件下,紫外照射距离20 cm,紫外照射时间13 min,碱性品红的去除率可达80%,远远高于二氧化氯化学氧化处理碱性品红的去除率46%.在废水处理过程中,采用紫外可见光谱和红外光谱分析降解产物,碱性品红被氧化降解为醌和羧酸,并进一步降解为二氧化碳和水,提出了二氧化氯/TiO2光催化氧化降解碱性品红废水的反应机理.

  3. Canonical Sets of Best L1-Approximation

    Dimiter Dryanov


    Full Text Available In mathematics, the term approximation usually means either interpolation on a point set or approximation with respect to a given distance. There is a concept, which joins the two approaches together, and this is the concept of characterization of the best approximants via interpolation. It turns out that for some large classes of functions the best approximants with respect to a certain distance can be constructed by interpolation on a point set that does not depend on the choice of the function to be approximated. Such point sets are called canonical sets of best approximation. The present paper summarizes results on canonical sets of best L1-approximation with emphasis on multivariate interpolation and best L1-approximation by blending functions. The best L1-approximants are characterized as transfinite interpolants on canonical sets. The notion of a Haar-Chebyshev system in the multivariate case is discussed also. In this context, it is shown that some multivariate interpolation spaces share properties of univariate Haar-Chebyshev systems. We study also the problem of best one-sided multivariate L1-approximation by sums of univariate functions. Explicit constructions of best one-sided L1-approximants give rise to well-known and new inequalities.

  4. Validation of ATLAS L1 Topological Triggers

    Praderio, Marco


    The Topological trigger (L1Topo) is a new component of the ATLAS L1 (Level-1) trigger. Its purpose is that of reducing the otherwise too high rate of data collection from the LHC by rejecting those events considered “uninteresting” (meaning that they have already been studied). This event rate reduction is achieved by applying topological requirements to the physical objects present in each event. It is very important to make sure that this trigger does not reject any “interesting” event. Therefore we need to verify its correct functioning. The goal of this summer student project is to study the response of two L1Topo algorithms (concerning ∆R and invariant mass). To do so I will compare the trigger decisions produced by the L1Topo hardware with the ones produced by the “official” L1Topo simulation. This way I will be able to identify events that could be incorrectly rejected. Simultaneously I will produce an emulation of these triggers that will help me understand the cause of disagreements bet...

  5. [Optimized expression of the L1 protein of human papillomavirus in Hansenula polymorpha].

    Li, Weiwei; He, Xiuping; Guo, Xuena; Zhang, Zhenying; Zhang, Borun


    The heterologously expressed L1 protein of human papilomavirus 16 can assembly into virus-like particles (VLPs), which has been used as prophylactic vaccine for cervical carcinoma. To express L1 protein in Hansenula polymorpha, we analyzed the codon usage of the native gene of L1 protein and redesigned the encoding sequence according to the codon bias of H. polymorpha. We used assembly PCR to synthesize the native gene HPV16L1-N and the codon optimized gene HPV16L1. The synthesized genes were cloned into pMOXZa-A vector to generate plasmids pMOXZ-HPV16N and pMOXZ-HPV16. The expression cassettes MOXp-HPV16L1(N)-AOXTT were cloned into YEp352 vector and transferred into H. polymorpha. After methanol inducement, the expression of L1 protein in H. polymorpha was detected from the codon optimized gene HPV16L1 rather than the native gene HPVI6L1-N. The parameters for induced cultivation for strain HP-U-16L with HPV16L1 were investigated in shaking flask cultures. After induced cultivation in YPM (pH 7.0) medium supplemented with methanol to a final concentration of 1.0% every 12 h at 37 degrees C for 72 h, the recombinant produced 78.6 mg/L of L1 protein. This work offers the possibility for the production of prophylactic vaccine for cervical carcinoma by H. polymorpha.

  6. Surface assembly of graphene oxide nanosheets on SiO2 particles for the selective isolation of hemoglobin.

    Liu, Jia-Wei; Zhang, Qian; Chen, Xu-Wei; Wang, Jian-Hua


    Graphene oxide (GO) nanosheets have been immobilized onto SiO(2) particles through electrostatic interactions by surface assembly. The surface-assembled composite material was characterized by means of SEM and FTIR and UV/Vis spectroscopy to reveal an assembling ratio of 2.3% (w/w, GO/SiO(2)). The GO/SiO(2) composites were subsequently used, for the first time, as adsorbents for the adsorption/isolation of proteins. Selective isolation of proteins of interest, namely, hemoglobin (Hb) in this case, from complex sample matrices, for example, human whole blood, could be obtained by carefully manipulating the adsorption/desorption process. At pH 7, an adsorption of 85% was achieved for Hb (70 mg L(-1)) in sample solution (1.0 mL) by the GO/SiO(2) composites (3.0 mg). The adsorption behavior was consistent with the Langmuir adsorption model, corresponding to a theoretical adsorption capacity of 50.5 mg g(-1) for Hb. The retained Hb could be readily recovered by using a Tris-HCl buffer at pH 8.9 to give a recovery of 80%. Circular dichroism and specific activity investigations indicated that the GO/SiO(2) composites exhibited favorable biocompatibility, characterized by virtually no effect on the conformation and activity of Hb after adsorption/desorption. The composites were used for the selective isolation of Hb from human whole blood and achieved satisfactory results by assaying with sodium dodecyl sulfate polyacrylamide gel electrophoresis.

  7. Face recognition with L1-norm subspaces

    Maritato, Federica; Liu, Ying; Colonnese, Stefania; Pados, Dimitris A.


    We consider the problem of representing individual faces by maximum L1-norm projection subspaces calculated from available face-image ensembles. In contrast to conventional L2-norm subspaces, L1-norm subspaces are seen to offer significant robustness to image variations, disturbances, and rank selection. Face recognition becomes then the problem of associating a new unknown face image to the "closest," in some sense, L1 subspace in the database. In this work, we also introduce the concept of adaptively allocating the available number of principal components to different face image classes, subject to a given total number/budget of principal components. Experimental studies included in this paper illustrate and support the theoretical developments.

  8. Solar photocatalytic degradation of 2,6-dinitro-p-cresol (DNPC) using multi-walled carbon nanotubes (MWCNTs)-TiO(2) composite photocatalysts.

    Wang, Hui; Wang, Hui-Long; Jiang, Wen-Feng


    Multi-walled carbon nanotubes (MWCNTs)-TiO(2) composite photocatalysts with excellent activity were prepared by sol-gel method in order to investigate its photocatalytic activity under solar irradiation for the degradation of 2,6-dinitro-p-cresol (DNPC) in aqueous solution. The prepared composite were analyzed by XRD, FTIR, SEM, TEM, TG-DTA and UV-vis absorption spectra techniques. The results showed that the composite can cause an obvious red shift of UV-vis spectra compared with pure TiO(2). The degradation of DNPC by MWCNTs-TiO(2) composite photocatalysts under solar irradiation was systematically studied by varying the experimental parameters such as pH value, irradiation time, the initial substrate concentration, reaction temperature, catalyst concentration, etc. The optimal conditions were a DNPC concentration of 33.4 mgL(-1) at pH 6.0 with MWCNTs-TiO(2) concentration of 6.0gL(-1) under solar irradiation for the illumination of 150 min. The presence of MWCNTs can enhance the photoefficiency of TiO(2). The highest efficiency on photodegradation of DNPC can be achieved with an optimal MWCNTs/TiO(2) mass ratio of 0.05%. The photocatalytic degradation of DNPC obeys a pseudo-first-order behavior according to the Langmuir-Hinshelwood model, and possible decomposing mechanisms are also discussed. The photocatalyst was used for five cycles with photocatalytic degradation efficiency still higher than 96%. The results of the study showed the feasible and potential use of MWCNTs-TiO(2) composite in degradation of toxic organic pollutants.

  9. Tolfenamic acid degradation by direct photolysis and the UV-ABC/H2O2 process: factorial design, kinetics, identification of intermediates, and toxicity evaluation.

    de Melo da Silva, Lucas; Pereira Cavalcante, Rodrigo; Fabbro Cunha, Rebeca; Gozzi, Fábio; Falcao Dantas, Renato; de Oliveira, Silvio Cesar; Machulek, Amilcar


    This study employed direct UV-ABC photolysis and the UV-ABC/H2O2 process to investigate the degradation of tolfenamic acid (TA), a common anti-inflammatory drug used in both human and veterinary medicine. A 2(3) factorial design with added center point was used to evaluate the effect of three independent variables-namely, H2O2 concentration ([H2O2]), TA concentration ([TA]), and experiment time (time)-on TA degradation and H2O2 photolysis during UV-ABC/H2O2 treatment using a high-pressure mercury vapor lamp (photon flux of 2.6307 × 10(4) J s(-1)) as the UV irradiation source. The responses yielded similar values, revealing a linear behavior, with correlation coefficients R = 0.9968 and Radj = 0.9921 for TA degradation and R = 0.9828 and Radj = 0.9570 for H2O2 photolysis. The most efficient combination of variables was [H2O2] = 255 mg L(-1) and [TA] = 25 mg L(-1), resulting in 100% TA degradation and 98.87% H2O2 photolysis by 90 min of treatment. Additionally, the second-order kinetic constant of the reaction between TA and HO(●) was determined using a competitive kinetic model, employing 2,4-dichlorophenoxyacetic acid (2,4D) as the reference compound. The kinetic constant was 1.9 × 10(10) M(-1) s(-1) in alkaline medium. TA degradation by direct photolysis generated quinone imines as by-products, responsible for the formation of a dark red "internal filter" that increased the value of acute toxicity to Artemia salina. The UV-ABC/H2O2 process did not promote formation of quinone imines by 90 min of treatment and therefore did not increase acute toxicity values. Several by-products generated during TA degradation were identified and possible degradation pathways for the UV-ABC and UV-ABC/H2O2 processes were proposed. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Effect of blood haemoglobin concentration on V(O2,max) and cardiovascular function in lowlanders acclimatised to 5260 m

    Calbet, J A L; Rådegran, G; Boushel, Robert Christopher


    +/- 5 to 185 +/- 5 g l(-1) (P delivery was reduced...... and maximal V(O(2)) was thus maintained by higher O(2) extraction. While CO increased linearly with work rate irrespective of [Hb] or inspired oxygen fraction (F(I,O(2))), both LBF and leg vascular conductance were systematically higher when [Hb] was low. Close and significant relationships were seen between...

  11. Photocatalytic removal of C.I. Basic Red 46 on immobilized TiO2 nanoparticles: artificial neural network modelling.

    Khataee, A R


    C.I. Basic Red 46, commonly used as a textile dye, was photocatalytically removed using supported TiO2 nanoparticles irradiated by a 30 W UV-C lamp in a batch reactor. The investigated photocatalyst was industrial Degussa P25 (crystallite mean size 21 nm) immobilized on glass beads by a heat attachment method. The catalyst was characterized by XRD, SEM, TEM and BET techniques. The process of the dye decolorization in the presence of TiO2 nanoparticles was experimentally studied through changing the initial dye concentration, UV light intensity and initial pH. The influence of inorganic anions such as chloride, sulphate, bicarbonate, carbonate and phosphate on the photocatalytic decolorization of BR46 was investigated. The decolorization of BR46 follows the pseudo-first-order kinetic according to the Langmuir-Hinshelwood model (k1 = 0.273 mg L(-1) min(-1), 2 = 0.313 (mg L(-1))(-1)). The efficiency parameters such as apparent quantum yield and electrical energy per order (EEO) were estimated. An artificial neural network model (ANN) was developed to predict the photocatalytic decolorization of BR46 solution. The findings indicated that the ANN provided reasonable predictive performance (R2 = 0.96). The influence of each parameter on the variable studied was assessed: initial concentration of the dye being the most significant factor, followed by the initial pH and reaction time.

  12. Competitive Contribution of Catalyst and Adsorption Roles of TiO2 on the Degradation of AO7 Dye During Plasma Treatment

    Nabila, Haddou; Mouffok Redounae, Ghezzar; Fatiha, Abdelmalek; Stephanie, Ognier; Ahmed, Addou


    In order to investigate the role of TiO2 during plasma treatment, the degradation of the dye AO7 has been studied by gliding arc discharge in the presence of a TiO2 catalyst (CGAD). The results revealed that the adsorption of the dye on TiO2 is a physical adsorption in accordance with Langmuir isotherm, with a constant of adsorption KL = 0.52 mg/L and a maximum adsorption capacity b = 18.1 mg/g. The temperature variation of the reaction medium made it possible to consider thermodynamic parameters. Indeed, the adsorption is exothermic (enthalpy: ΔH < 0), and spontaneous (free enthalpy: ΔG < 0). The negative entropy (ΔS < 0) confirms the affinity of the dye molecules for TiO2. 20 min of CGAD treatment in the presence of an optimal quantity of TiO2 (2 g/L enabled us to bleach the solution of AO7 (100 μM) completely. The discoloration rate with and without the addition of TiO2 was 100% and 28%, respectively. 40 additional minutes of treatment allowed a total abatement of the chemical oxygen demand. The elimination of AO7 molecules during the plasma-catalytic treatment follows Langmuir-Hinshelwood (L-H) model kinetics. According to this model, the speed constant is kr = 14.97 mg · L-1 · min-1 and the adsorption coefficient is KL—H = 0.010 L/mg. The latter being negligible compared to kr, adsorption is therefore weakly performed during the plasma treatment.

  13. Reference: L1DCPAL1 [PLACE

    Full Text Available L1DCPAL1 Takeda J, Ito Y, Maeda K, Ozeki Y. Assignment of UVB-responsive cis-elemen...anine ammonia-lyase gene (gDcPAL1). Photochem Photobiol. 76:232-238 (2002). PubMed: 12194222 ...

  14. Voice and Narrative in L1 Writing

    Krogh, Ellen; Piekut, Anke


    in lower secondary L1, she found that her previous writing strategies were not rewarded in upper secondary school. In the second empiri-cal study, two upper-secondary exam papers are investigated, with a focus on their approaches to exam genres and their use of narrative resources to address issues...

  15. Synthesis and Photocatalytie Property of the ZrO2/TiO2Pillared Laponite

    LIN Yingguang; PI Pihui; YANG Zhuoru; WANG Lianshi


    The ZrO2/TiO2 pillared laponite (Ti-Zr-lap) photocatalysts were prepared with intercalation reaction by supercritical fluid drying (SCFD),and characterized by XRD,TEM,SEM and BET surface area analysis,and the photocatalytic properties of Ti-Zr-lap were investigated by degradation of azo dye acid red B (ARB).The results showed that the ZrO2/TiO2 pillared structures in laponite could be formed,with the mass fraction of (Zr+++Ti4+)/laponite (Xm) increasing,the basal spacing and the BET surface area of Ti-Zr-lap significantly increased.The Ti-Zr-lap used as photocatalyst had the advantages of stable and porous layered structure,large surface area with the anatase type TiO2+ Compared with the Ti-Zr-lap dried by air drying,the TiZr-lap dried by SCFD showed better photocatalytic property which was very close to that of P25 TiO2.Using the Ti-Zr-lap as photocatalyst with the optimum Xm of 0.16 and the calcination temperature of 500 ℃,under the conditions of the initial concentration of ARB 20 mg/L,photocatalyst concentration of 1.5 g/L and irradiation time 60 min,the decoloring rate of ARB could achieve 98.3%,indicating that the Ti-Zr-lap had excellent photocatalytic property.

  16. Avaliação da degradação do diclofenaco sódico utilizando H2O2/fenton em reator eletroquímico Evaluation of the degradation of sodium diclofenac using H2O2/fenton in electrochemical reactor

    Robson S. Rocha


    Full Text Available This paper describes a degradation study of the anti-inflammatory sodium diclofenac in aqueous medium using an electro-chemical flow reactor with a gas diffusion electrode as cathode. Two degradation processes were compared: by H2O2 electro-generated and H2O2 electro-generated/Fe(II. Concentration of sodium diclofenac was determined during the experiments by HPLC. The changes in chemical oxigen demand (COD were also evaluated. Under the specific reaction conditions, 350 mg L-1 of H2O2 was electro-generated and 99.2% of sodium diclofenac was degradated, with 27.4% COD reduction. At the same conditions, but using Fe(II, drug degradation was 99.4% and the COD reduction was 63.2%.

  17. Photocatalytic Degradation of Atrazine with TiO2 Fixed on Granular Activated Carbon (GAC)%固定在颗粒活性炭中的TiO2光催化降解阿特拉津

    何亚明; 单建国; 朱元春; 曲强


    利用30 W低压汞灯作光源,采用固定颗粒活性炭中的TiO2(TiO2/GAC)作光催化剂,在浅盘反应器中考察了阿特拉津溶液的光催化降解.结果表明,在平均光强为4.38 mW·cm-2,光催化剂投加量为7.0 g·L-1,阿特拉津初始浓度为2 1.9 mg·L,3wt%H2O2用量为30μL·15mL-1,投加方式为1次·2h-1,光照时间为6~10 h时,去除率可达92.7%~94.7%,TOC去除率可达67.1%~78.3%.光催化剂增至10 g·L-1,H2O2用量一次性加60μL,光照时间为3~4 h时,去除率可达91.6%~93.7%,TOC去除率可达65.9%~73.9%.通过组合实验和紫外光谱图分析,估计了体系中影响去除率的光催化、吸附、光降解、H2O2的作用性质和大小,并估计了降解途径,认为同时存在侧链脱烷基反应和OH取代Cl的反应,在有H2O2存在时,使前反应较强.TOC值测定表明阿特拉津已从8个碳降至含2~3个碳的物质.

  18. Macroporous graphene capped Fe3O4 for amplified electrochemiluminescence immunosensing of carcinoembryonic antigen detection based on CeO2@TiO2.

    Yang, Lei; Zhu, Wenjuan; Ren, Xiang; Khan, Malik Saddam; Zhang, Yong; Du, Bin; Wei, Qin


    A novel electrochemiluminescence (ECL) signal-amplified immunosensing strategy was proposed by using gold nanoparticles (Au NPs) functionalized reduced graphene oxide (rGO) capped Fe3O4 (Au-FrGO). In this work, CeO2@TiO2 was prepared by a sol-gel method to wrap CeO2 with TiO2. In the presence of CeO2, CeO2@TiO2 exhibited better ECL activity than TiO2 with peroxydisulfate as coreactant. In addition, FrGO with macroporous structure was synthesized by self-assembly of rGO sheets capped cationic Fe3O4 nanoparticles, exhibiting larger specific surface area than rGO. Due to the low toxicity and magnetism of Fe3O4, FrGO owned more favorable biocompatibility and the application of magnetic-separation simplified the preparation procedure. After hybridizing with Au NPs, FrGO exhibited more excellent electrical conductivity and could immobilize more CeO2@TiO2 and antibodies. Therefore, a novel label-free ECL immunosensor based on Au-FrGO-CeO2@TiO2 was constructed which generated higher ECL response. To investigate the performance of the immunosensor, carcinoembryonic antigen (CEA) was chosen as a model target analyte. Under optimal conditions, the immunosensor had sensitive response to CEA in a wide linear range of 0.01pgmL(-1) to 10ngmL(-1) with a detection limit of 3.28 fg mL(-1). The proposed ECL immunosensor exhibited excellent stability, repeatability and selectivity, which opened another promising avenue for CEA determination in real serum samples.

  19. SnO2 nanoparticle-loaded activated carbon for simultaneous removal of Acid Yellow 41 and Sunset Yellow; derivative spectrophotometric, artificial neural network and optimization approach.

    Hajati, S; Ghaedi, M; Mahmoudi, Z; Sahraei, R


    The simultaneous adsorption of Acid Yellow 41 (AY41) and Sunset Yellow (SY) onto SnO2 nanoparticle-loaded activated carbon (SnO2-NP-AC with very high BET surface area of 1278.71 m(2) g(-1)) was investigated. To overcome the severe dyes spectral overlapping, derivative spectrophotometric method and principal component analysis-artificial neural network (PCA-ANN) were successfully applied for the simultaneous determination of AY41 and SY in their binary solutions. By using central composite design (CCD) under response surface methodology, the effects of variables such as contact time, adsorbent dosage, pH, AY41 concentration and SY concentration on responses such as binary dyes removal percentages were examined. Optimal values were found to be 17.9 min, 0.024 g, 3.1, and 15.9 mg L(-1) and 18.7 mg L(-1), respectively. In binary solutions, the best fit to modified-extended Langmuir isotherm was obtained for the whole concentration range. In binary solutions, a synergism was observed for the AY41 and SY dyes adsorption onto SnO2-NP-AC. The adsorption rates at various times were analyzed. It indicated a pseudo-second-order kinetic model for the adsorption of both dyes.

  20. Preparation of Cu/n-TiO2/PBO composite fibers%Cu/n-TiO2/PBO复合纤维的制备

    刘雪峰; 隋守军; 谢建新


    以PBO纤维为基体,采用浸渍涂覆法在PBO纤维表面包覆纳米TiO2膜,采用化学镀法将Cu沉积到纳米TiO2膜表面,制备了Cu/n-TiO2/PBO复合纤维,研究了影响纳米TiO2沉积速率和Cu沉积速率的主要因素.结果表明,纳米TiO2与偶联剂的浓度配比是影响纳米TiO2包膜形成的主要因素,当纳米TiO2与偶联剂浓度配比为1:1.2时,制备的n-TiO2/PBO复合纤维界面结合力较好,且纳米TiO2包覆层比较均匀.影响化学镀铜的主要因素有镀液成分、反应时间和反应温度.在镀液成分的浓度配比为CuSO4·5H2O 12 g·L-1、KNaC4 H4O68 g·L-1、HCHO 6 mL·L-1和NaOH 10 g·L-1,反应温度50℃,镀铜时间20 min的条件下,制备了负载均匀,界面结合力较好的Cu/n-TiO2/PBO复合纤维.

  1. Treatment of olive mill wastewater by photooxidation with ZrO2-doped TiO2 nanocomposite and its reuse capability.

    Sponza, Delia Teresa; Oztekin, Rukiye


    Zirconium dioxide (zirconia, ZrO2)-doped TiO2 (TiO2/ZrO2) nanocomposite was used for the photocatalytic oxidation of pollutant parameters [COD components (CODtotal, CODdissolved and CODinert)], polyphenols (catechol, 3-hydroxybenzoic acid, tyrosol and 4-hydroxybenzoic acid) and total polyaromatic amines [aniline, 4-nitroaniline, o-toluidine and o-anisidine] from the olive mill effluent wastewaters at different operational conditions such as at different mass ratios of ZrO2 (50, 25, 14, 10 and 5 wt%) in the TiO2/ZrO2 nanocomposite, at different TiO2/ZrO2 photocatalyst concentrations (1, 4, 15 and 50 mg/L) and pH values (4.0-7.0-10.0) under 300 W UV irradiations, respectively. Under the optimized conditions (pH = 4.6, 15 mg/L ZrO2/TiO2 nanocomposite with a ZrO2 mass ratio of 14 wt%, 300 W UV light, after 60 min photooxidation time, at 21°C), the maximum CODdissolved, total phenol and total aromatic amines photooxidation yields were 99%, 89% and 95%, respectively. High pollutant removal (89%) yields after sequential five times utilization of ZrO2/TiO2 nanocomposite show that this catalyst can be effectively used commercially in the treatment of olive mill effluent.

  2. The Papillomavirus Major Capsid Protein L1

    Buck, Christopher B.; Day, Patricia M.; Trus, Benes L.


    The elegant icosahedral surface of the papillomavirus virion is formed by a single protein called L1. Recombinant L1 proteins can spontaneously self-assemble into a highly immunogenic structure that closely mimics the natural surface of native papillomavirus virions. This has served as the basis for two highly successful vaccines against cancer-causing human papillomaviruses (HPVs). During the viral life cycle, the capsid must undergo a variety of conformational changes, allowing key functions including the encapsidation of the ~8 kb viral genomic DNA, maturation into a more stable state to survive transit between hosts, mediating attachment to new host cells, and finally releasing the viral DNA into the newly infected host cell. This brief review focuses on conserved sequence and structural features that underlie the functions of this remarkable protein. PMID:23800545

  3. Generalized L1 penalized matrix factorization

    Rasmussen, Morten Arendt


    for constraining models to obey certain structural properties, including parameter sparsity and sparsity on pairwise differences between parameter estimates. The utility of this framework is used to modify principal component analysis, partial least squares, canonical correlation analysis, and multivariate......Traditionally, chemometric models consists of parameters found by solving a least squares criterion. However, these models can suffer from overfitting, as well as being hard to interpret because of the large number of active parameters. This work proposes the use of a generalized L1 norm penalty...... analysis of variance type of models applied to synthetic and chemical data. This work argues that L1 norm penalized models offers parsimony, robustness and predictive performance, and reveals a path for modifying unconstrained chemometric models through convex penalties....

  4. Estudo da aplicação de foto-Fenton (Fe2+/H2O2 solar no pré-tratamento do chorume

    Alessandro Sampaio Cavalcanti


    Full Text Available O chorume em estudo é proveniente da cidade de Cachoeira Paulista no interior do estado de São Paulo apresenta as concentrações dos parâmetros COT (368.6 mg C L-1, DQO (3552.2 mg O2 L-1 e DBO (397.4 mg O2 L-1 que mostram a baixa razão de        biodegradabilidade (DBO/DQO = 0.11. Neste contexto, os processos oxidativos avançados surgem como alternativa para o seu pré-tratamento. O objetivo desse trabalho é utilizar a fotocatálise homogênea, empregando foto-Fenton (H2O2 + Fe2+ Solar num reator aberto com volume constante do efluente (3 L para verificar a eficiência e a avaliação econômica de remoção da carga orgânica. O reator possui um suporte de madeira que está direcionado ao Equador com um ângulo de inclinação de 23º, com uma placa metálica sem pigmentação denominada branco, numa vazão constante (13 L . min-1. Ao mesmo tempo, o volume do reagente de Fe2+ (0.82 mol L-1 foi adicionado totalmente no início da reação e o H2O2 (30 %  m/ m durante 60 min do tempo total de 2 h, sendo a radiação solar medida através de um radiômetro portátil. O processo foi otimizado por um planejamento fatorial fracionado (24-1, e os fatores estudados foram: pH, intervalo da radiação solar, quantidades de H2O2 (g e Fe2+ (g. A maior redução percentual de COT (Carbono Orgânico Total foi 82.12%, com um aumento de sua biodegradabilidade para 0.41 aliado ao custo otimizado de US$ 0.188 / 3 L. Desta forma, o processo fotocatalítico proposto mostrou grande viabilidade técnico-econômico em relação à degradação da carga orgânica do chorume.

  5. L1-norm packings from function fields

    LI Hongli


    In this paper, we study some packings in a cube, namely, how to pack n points in a cube so as to maximize the minimal distance. The distance is induced by the L1-norm which is analogous to the Hamming distance in coding theory. Two constructions with reasonable parameters are obtained, by using some results from a function field including divisor class group, narrow ray class group, and so on. We also present some asymptotic results of the two packings.

  6. Properties of the ZrO2MgO/MgZrO3NiCr/NiCr triple-layer thermal barrier coating deposited by the atmospheric plasma spray process / Характеристики трехслойных термобарьерных покрытий ZrO2MgO/ MgZrO3NiCr/ NiCr, нанесенных воздушно-плазменным напылением / Svojstva troslojne termo barijerne prevlake ZrO2MgO/ MgZrO3NiCr/ NiCr deponovane atmosferskim plazma sprej procesom

    Mihailo R. Mrdak


    Full Text Available This paper presents the results of the examinations of TBC - ZrO2MgO / MgZrO3NiCr / NiCr thermal barrier layers deposited by the plasma spray process at the atmospheric pressure on substrates of Al alloys. In order to obtain the structural and mechanical properties of layers, which will provide a good heat and abrasion protection of the tail elevators of aircraft J-22 when firing '.Lightning' and 'Thunder' rockets, the deposition of three powder types was performed on 0.6 mm thick Al alloy substrates. This study describes a procedure of using triple-layer TBC coatings as a good combination among many available ones, which gives a good compromise between thermal protection and resistance to abrasion for protecting aircraft tail elevators. The study is mainly based on the experimental approach. The evaluation of the mechanical properties of layers was done by the examination of microhardness by method HV0.3 and bond strength on the tensile machine. The structure of layers was examined by the method of light microscopy while the surface of ZrO2MgO ceramic layers was examined by the method of scanning electron microscopy (SEM.The thermal protection of TBC layers and resistance to abrasion were tested in the tunnel of the Military Technical Institute, Zarkovo. The obtained characteristics of the surface layers and the rocket firing simulations have proven the triple-layer system of TBC coatings reliable. / В данной статье представлены результаты испытаний термобарьерных покрытий ТБС ZrO2MgO/MgZrO3NiCr/NiCr, нанесенных воздушно-плазменным напылением при атмосферном давлении на субстраты сплавов Al. Испытания проводились с целью получения структурных и механических характеристик слоев, обеспечивающих ка

  7. Comparative effect of simulated solar light, UV, UV/H2O2 and photo-Fenton treatment (UV-Vis/H2O2/Fe2+,3+) in the Escherichia coli inactivation in artificial seawater.

    Rubio, D; Nebot, E; Casanueva, J F; Pulgarin, C


    Innovative disinfection technologies are being studied for seawater, seeking a viable alternative to chlorination. This study proposes the use of H2O2/UV254 and photo-Fenton as disinfection treatment in seawater. The irradiations were carried out using a sunlight simulator (Suntest) and a cylindrical UV reactor. The efficiency of the treatment was compared for Milli-Q water, Leman Lake water and artificial seawater. The presence of bicarbonates and organic matter was investigated in order to evaluate possible effects on the photo-Fenton disinfection treatment. The photo-Fenton treatment, employing 1 mg L(-1) Fe(2+) and 10 mg L(-1) of H2O2, led to the fastest bacterial inactivation kinetics. Using H2O2/UV254 high disinfection rates were obtained similar to those obtained with photo-Fenton under UV254 light. In Milli-Q water, the rate of inactivation for Escherichia coli was higher than in Leman Lake water and seawater due to the lack of inorganic ions affecting negatively bacteria inactivation. The presence of bicarbonate showed scavenging of the OH(•) radicals generated in the treatment of photo-Fenton and H2O2/UV254. Despite the negative effect of inorganic ions, especially HCO3(-), the disinfection treatments with AOPs in lake water and seawater improved significantly the disinfection compared to light alone (simulated sunlight and UV254). In the treatment of photo-Fenton with simulated sunlight, dissolved organic matter had a beneficial effect by increasing the rate of inactivation. This is associated with the formation of Fe(3+)-organo photosensitive complexes leading to the formation of ROS able to inactivate bacteria. This effect was not observed in the photo-Fenton with UV254. Growth of E. coli surviving in seawater was observed 24 and 48 h after treatment with UV light. However, growth of surviving bacteria was not detected after photo-Fenton with UV254 and H2O2/UV254 treatments. This study suggests H2O2/UV254 and photo-Fenton treatments for the


    刘丰良; 刘淑君; 薛志超; 王了一


    以Fe(Ⅲ)改性金红石TiO_2(r-TiO_2)制备Fe/r-TiO_2,研究了Fe/r-TiO_2可见光催化H_2O_2降解阿特拉津的各种影响因素.结果表明,Fe/r-TiO_2在H_2O_2及波长不低于400mm的可见光协同作用下,控制反应体系的pH为3,H_2O_2的浓度为1 mmol·L~(-1),催化剂质量浓度为1 g·L~(-1),经1 h后,阿特拉津的降解率可达95%.

  9. O2 store management in diving emperor penguins.

    Ponganis, P J; Stockard, T K; Meir, J U; Williams, C L; Ponganis, K V; Howard, R


    In order to further define O(2) store utilization during dives and understand the physiological basis of the aerobic dive limit (ADL, dive duration associated with the onset of post-dive blood lactate accumulation), emperor penguins (Aptenodytes forsteri) were equipped with either a blood partial pressure of oxygen (P(O(2))) recorder or a blood sampler while they were diving at an isolated dive hole in the sea ice of McMurdo Sound, Antarctica. Arterial P(O(2)) profiles (57 dives) revealed that (a) pre-dive P(O(2)) was greater than that at rest, (b) P(O(2)) transiently increased during descent and (c) post-dive P(O(2)) reached that at rest in 1.92+/-1.89 min (N=53). Venous P(O(2)) profiles (130 dives) revealed that (a) pre-dive venous P(O(2)) was greater than that at rest prior to 61% of dives, (b) in 90% of dives venous P(O(2)) transiently increased with a mean maximum P(O(2)) of 53+/-18 mmHg and a mean increase in P(O(2)) of 11+/-12 mmHg, (c) in 78% of dives, this peak venous P(O(2)) occurred within the first 3 min, and (d) post-dive venous P(O(2)) reached that at rest within 2.23+/-2.64 min (N=84). Arterial and venous P(O(2)) values in blood samples collected 1-3 min into dives were greater than or near to the respective values at rest. Blood lactate concentration was less than 2 mmol l(-1) as far as 10.5 min into dives, well beyond the known ADL of 5.6 min. Mean arterial and venous P(N(2)) of samples collected at 20-37 m depth were 2.5 times those at the surface, both being 2.1+/-0.7 atmospheres absolute (ATA; N=3 each), and were not significantly different. These findings are consistent with the maintenance of gas exchange during dives (elevated arterial and venous P(O(2)) and P(N(2)) during dives), muscle ischemia during dives (elevated venous P(O(2)), lack of lactate washout into blood during dives), and arterio-venous shunting of blood both during the surface period (venous P(O(2)) greater than that at rest) and during dives (arterialized venous P(O(2

  10. Electrochemical mineralization of pentachlorophenol (PCP) by Ti/SnO2-Sb electrodes.

    Niu, Junfeng; Bao, Yueping; Li, Yang; Chai, Zhen


    Electrochemical degradation of pentachlorophenol (PCP) in aqueous solution was investigated over Ti/SnO2-Sb electrodes prepared by sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements were used to characterize the physicochemical properties of the electrodes. The electrochemical degradation of PCP followed pseudo-first-order kinetics. The main influencing factors, including the types of supporting electrolyte (i.e., NaClO4, Na2SO4, Na2SO3, NaNO3, and NaNO2), initial concentrations of PCP (5-1000mgL(-1)), pH values (3.0-11.0), and current densities (5-40mAcm(-2)) were evaluated. The degradation and mineralization ratios of 100mgL(-1) of PCP achieved >99.8% and 83.0% after 30min electrolysis with a 10mmolL(-1) Na2SO4 at a current density of 10mAcm(-2), respectively. The corresponding half-life time (t1/2) was 3.94min. The degradation pathways that were involved in dechlorination, protons generation, and mineralization processes were proposed based on the determination of total organic carbon, chloride, and intermediate products (i.e., low chlorinated phenol and some organic acids). The toxicity of PCP and its intermediates could be reduced effectively by electrolysis. These results showed that electrochemical technique could achieve a significant mineralization rate in a short time (PCP elimination from wastewater. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Scavenging of H2O2 by mouse brain mitochondria.

    Starkov, Anatoly A; Andreyev, Alexander Yu; Zhang, Steven F; Starkova, Natalia N; Korneeva, Maria; Syromyatnikov, Mikhail; Popov, Vasily N


    Mitochondrial reactive oxygen species (ROS) metabolism is unique in that mitochondria both generate and scavenge ROS. Recent estimates of ROS scavenging capacity of brain mitochondria are surprisingly high, ca. 9-12 nmol H2O2/min/mg, which is ~100 times higher than the rate of ROS generation. This raises a question whether brain mitochondria are a source or a sink of ROS. We studied the interaction between ROS generation and scavenging in mouse brain mitochondria by measuring the rate of removal of H2O2 added at a concentration of 0.4 μM, which is close to the reported physiological H2O2 concentrations in tissues, under conditions of low and high levels of mitochondrial H2O2 generation. With NAD-linked substrates, the rate of H2O2 generation by mitochondria was ~50-70 pmol/min/mg. The H2O2 scavenging dynamics was best approximated by the first order reaction equation. H2O2 scavenging was not affected by the uncoupling of mitochondria, phosphorylation of added ADP, or the genetic ablation of glutathione peroxidase 1, but decreased in the absence of respiratory substrates, in the presence of thioredoxin reductase inhibitor auranofin, or in partially disrupted mitochondria. With succinate, the rate of H2O2 generation was ~2,200-2,900 pmol/min/mg; the scavenging of added H2O2 was masked by a significant accumulation of generated H2O2 in the assay medium. The obtained data were fitted into a simple model that reasonably well described the interaction between H2O2 scavenging and production. It showed that mitochondria are neither a sink nor a source of H2O2, but can function as both at the same time, efficiently stabilizing exogenous H2O2 concentration at a level directly proportional to the ratio of the H2O2 generation rate to the rate constant of the first order scavenging reaction.

  12. Ag@SiO2-entrapped hydrogel microarray: a new platform for a metal-enhanced fluorescence-based protein assay.

    Jang, Eunji; Kim, Minsu; Koh, Won-Gun


    We developed a novel protein-based bioassay platform utilizing metal-enhanced fluorescence (MEF), which is a hydrogel microarray entrapping silica-coated silver nanoparticles (Ag@SiO2). As a model system, different concentrations of glucose were detected using a fluorescence method by sequential bienzymatic reaction of hydrogel-entrapped glucose oxidase (GOX) and peroxidase (POD) inside a hydrogel microarray. Microarrays based on poly(ethylene glycol)(PEG) hydrogels were prepared by photopatterning a solution containing PEG diacrylate (PEG-DA), photoinitiator, enzymes, and Ag@SiO2. The resulting hydrogel microarrays were able to entrap both enzymes and Ag@SiO2 without leaching and deactivation problems. The presence of Ag@SiO2 within the hydrogel microarray enhanced the fluorescence signal, and the extent of the enhancement was dependent on the thickness of silica shells and the amount of Ag@SiO2. Optimal MEF effects were achieved when the thickness of the silica shell was 17.5 nm, and 0.5 mg mL(-1) of Ag@SiO2 was incorporated into the assay systems. Compared with the standard hydrogel microarray-based assay performed without Ag@SiO2, more than a 4-fold fluorescence enhancement was observed in a glucose concentration range between 10(-3) mM and 10.0 mM using hydrogel microarray entrapping Ag@SiO2, which led to significant improvements in the sensitivity and the limit of detection (LOD). The hydrogel microarray system presented in this study could be successfully combined with a microfluidic device as an initial step to create an MEF-based micro-total-analysis-system (μ-TAS).

  13. Three cases with L1 syndrome and two novel mutations in the L1CAM gene.

    Marín, Rosario; Ley-Martos, Miriam; Gutiérrez, Gema; Rodríguez-Sánchez, Felicidad; Arroyo, Diego; Mora-López, Francisco


    Mutations in the L1CAM gene have been identified in the following various X-linked neurological disorders: congenital hydrocephalus; mental retardation, aphasia, shuffling gait, and adducted thumbs (MASA) syndrome; spastic paraplegia; and agenesis of the corpus callosum. These conditions are currently considered different phenotypes of a single entity known as L1 syndrome. We present three families with L1 syndrome. Sequencing of the L1CAM gene allowed the identification of the following mutations involved: a known splicing mutation (c.3531-12G>A) and two novel ones: a missense mutation (c.1754A>C; p.Asp585Ala) and a nonsense mutation (c.3478C>T; p.Gln1160Stop). The number of affected males and carrier females identified in a relatively small population suggests that L1 syndrome may be under-diagnosed. L1 syndrome should be considered in the differential diagnosis of intellectual disability or mental retardation in children, especially when other signs such as hydrocephalus or adducted thumbs are present.


    姜聚慧; 王慧; 朱琳芳; 王林浩


    Ag(1%)-ZnO-TiO2(20%) photocatalyst was prepared by Sol-Gel method. The effects of operation parameters such as initial pH, intensity of illumination, catalyst loading and initial dye concentration on kinetics of photocatalytic degradation are studied. The results show that all the parameters have apparent efficiency on degradation of reactive brilliant blue KN-R except initial pH, and the experimental conditions are pH is 9.30, 300 W, 3.0 g·L-1;the degradation rate of the reactive brilliant blue KN-R can reach 99.9% when the illumination time is 60 min, solution initial concentration is 84 mg·L-1.Furthermore, when the initial concentration was under a specific amounts, the photocatalytic degradation process obvious followed the first- order reaction.%采用溶胶-凝胶法制备了Ag和TiO2的质量分数分别为1%和20%的Ag-TiO2-ZnO光催化剂,研究了溶液初始pH、光源功率、催化剂投加量及染料初始质量浓度对降解活性艳兰KN-R动力学的影响.结果表明,光源功率和催化剂投加量对染料降解影响较大,pH的影响较小,其最佳反应条件分别为紫外汞灯300W、催化剂投加量3.0 g·L-1和pH=9.30;对初始质量浓度为84 mg·L-1的活性艳兰KN-R光照30 min时,降解率可达99.9%,且在一定初始质量浓度下,光催化降解过程表现为1级反应.

  15. Hyperspectral IASI L1C Data Compression

    Joaquín García-Sobrino


    Full Text Available The Infrared Atmospheric Sounding Interferometer (IASI, implemented on the MetOp satellite series, represents a significant step forward in atmospheric forecast and weather understanding. The instrument provides infrared soundings of unprecedented accuracy and spectral resolution to derive humidity and atmospheric temperature profiles, as well as some of the chemical components playing a key role in climate monitoring. IASI collects rich spectral information, which results in large amounts of data (about 16 Gigabytes per day. Efficient compression techniques are requested for both transmission and storage of such huge data. This study reviews the performance of several state of the art coding standards and techniques for IASI L1C data compression. Discussion embraces lossless, near-lossless and lossy compression. Several spectral transforms, essential to achieve improved coding performance due to the high spectral redundancy inherent to IASI products, are also discussed. Illustrative results are reported for a set of 96 IASI L1C orbits acquired over a full year (4 orbits per month for each IASI-A and IASI-B from July 2013 to June 2014 . Further, this survey provides organized data and facts to assist future research and the atmospheric scientific community.

  16. Titamium oxide (TiO2) assisted photocatalytic degradation of methylene blue.

    Madhu, G M; Raj, M A Lourdu Antony; Pai, K Vasantha Kumar


    The aqueous solution of methylene blue (MB) has been subjected to Photocatalytic degradation by UV radiation in presence of TiO2 photo-catalyst containing different concentrations of H2O2. The experiments conducted at different dye concentrations (12 and 20 ppm), catalyst loading, pH and H2O2 dosage (1-10 ml l(-1)), revealed that the degradation rate is strongly influenced by respective experimental parameters. However the influence of catalyst alone is not predominant in degradation. The decolorization of dye proceed to near completeness when H2O2 is used. The best degradation results are observed at 0.1 wt% of catalyst loading at pH 2 for TiO2/UV system. It has been found that the optimum concentration of H2O2 for 12 ppm and 20 ppm amount of the dye was 2 ml l(-1) for UV/H2O2 system. The kinetic of degradation of the dye followed the pseudo first order rate. The degradation studies using TiO2/UV/H2O2 system, indicates enhancement in the degradation rate of the dye compared to that of UV/H2O2 system alone.

  17. High-efficiency and mechano-/photo- bi-catalysis of piezoelectric-ZnO@ photoelectric-TiO2 core-shell nanofibers for dye decomposition.

    You, Huilin; Wu, Zheng; Jia, Yanmin; Xu, Xiaoli; Xia, Yuntao; Han, Zichen; Wang, Yu


    A mechano-/photo- bi-catalyst of piezoelectric-ZnO@photoelectric-TiO2 core-shell nanofibers was hydrothermally synthesized for Methyl Orange (10 mg L(-1)) decomposition. The mechano-/photo- bi-catalysis in ZnO@TiO2 is superior to mechano- or photo-catalysis in decomposing Methyl Orange, which is mainly attributed to the synergy effect of the piezoelectric-ZnO core's mechano-catalysis and the thin photoelectric TiO2 shell's photo-catalysis. The heterostructure of the piezoelectric-ZnO@photoelectric-TiO2 core-shell interface, being helpful to reduce electron-hole pair recombination and to separate the piezoelectrically-/photoelectric ally- induced electrons and holes, may also make a great contribution to the enhanced catalysis performance. The mechano-/photo-bi-catalysis in ZnO@TiO2 core-shell nanofibers possesses the advantages of high efficiency, non-toxicity and tractability and is potential in utilizing mechanical/solar energy to deal with dye wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Catalysis by Using TiO2 Nanoparticles and Nanotubes

    Chien Shu-Hua; Kuo Ming-Chih; Liou Yuh-Cherng


    TiO2 has attracted considerable attention due to its stability, non-toxicity, low cost, and great potential for use as a photocatalyst in environmental applications. Since strong metal-support interaction (SMSI) of titania-supported noble metals was first reported in 1978, titania supported catalyst has been intensively studied in heterogeneous catalysis. However, the effective catalytic activity was restricted due to the low surface area of TiO2. Recently, TiO2-based nanotubes were extensively investigated because of their potentials in many areas such as highly efficient photocatalysis and hydrogen sensor.In the present study, formation of titanium oxide (TiO2) nanotubes was carried out by hydrothermal method, with TiO2 nanoparticle-powders immersed in concentrated NaOH solution in an autoclave at 110 ℃. Preparation of nano-size Pt on TiO2-nanoparticles or TiO2-nanotubes was performed by photochemical deposition method with UV irradiation on an aqueous solution containing TiO2 and hexachloroplatinic acid or tetrachloroauric acid. The TEM micrographs show that TiO2-nanotubes exhibit ~300 nm in length with an inner diameter of ~ 6 nm and the wall thickness of ~ 2 nm, and homogeneous nanosize Pt particles (~ 2 nm) were well-dispersed on both nanoparticle- and nanotube- titania supports. It also shows the nanotube morphology was retained up2o n Pt-immobilization. Nitrogen adsorption isotherm at 77K resulted a high surface area (~ 200m/g) of TiO2-nanotubes, which is about 40 times greater than that of "mother" TiO2 nanoparticles (~5 m/g). All the spectroscopic results exhibited that the nanotube structure was not significantly affected by the immobilized Pt particles. Ti K-edge XANES spectra of TiO2 nanotube and Pt/TiO2-nanotube represent that most titanium are in a tetrahedral coordination with few retained in the octahedral structure.In the in-situ FT-IR experiments, an IR cell was evacuated to a pressure of 10-5 torr at room temperature as soon as the

  19. Degradation of alizarin red solution by TiO2 supported on CNTs%CNTs负载TiO2对茜素红溶液的降解研究

    付文; 王丽


    Using tetrabutyl titanate as the precursor and acetic acid as the depressor,TiO2/CNTs composite catalyst was prepared by sol-gel method. The photo-degradation activity of TiO2/CNTs composite catalyst for photocatalytic degradation of alizarin red solution with different concentrations was investigated,and its photocatalytic degradation kinetics was also studied. The results showed that the optimal preparation condition of composite catalyst was as follows:CNTs loading mass fraction 7 . 5%,calcination temperature 450 ℃and calcination time 3. 5 h,and the photocatalytic activity of TiO2/CNTs composite catalyst was improved. Under the same condition,the final degradation rate of alizarin red solution with the concentration of 150 mg·L-1 over TiO2/CNTs catalyst reached 67%,while the final degradation rate of alizarin red solu-tion over TiO2 only was 56%. The reason for photocatalytic activity improvement of composite catalyst was that it could generate more active hydroxyl under UV irradiation when TiO2 was loaded on CNTs. The photocatalytic degradation kinetics of the composite catalyst complied Langmuir-Hinshelwood equation. The catalyst surface adsorption to pollutants was the bottleneck of reaction,and the reaction order of kinetics decreased from one order to zero level with the increase of pollutant concentrations.%以钛酸四丁酯为前驱体,冰醋酸为水解抑制剂,采用溶胶-凝胶法制备纳米TiO2/CNTs复合催化剂。测定复合催化剂对不同浓度茜素红溶液的光降解活性,并对光催化降解动力学进行研究。结果表明,在CNTs负载质量分数7.5%、焙烧温度450℃和焙烧时间3.5 h 条件下制备的TiO2/CNTs复合催化剂光催化活性得到提升。相同条件下,TiO2/CNTs对150 mg·L-1茜素红溶液的最终降解率达67%,而TiO2的最终降解率只有56%。复合催化剂光催化活性提升的原因是CNTs负载后光催化粒子在紫外光照射下生成更多的氢氧根活性自由基

  20. Efficient drug delivery using SiO2-layered double hydroxide nanocomposites.

    Li, Li; Gu, Zi; Gu, Wenyi; Liu, Jian; Xu, Zhi Ping


    MgAl-layered double hydroxide (MgAl-LDH) nanoparticles have great potentials in drug and siRNA delivery. In this work, we used a nanodot-coating strategy to prepare SiO2 dot-coated layered double hydroxide (SiO2@MgAl-LDH) nanocomposites with good dispersibility and controllable size for drug delivery. The optimal SiO2@MgAl-LDH nanocomposite was obtained by adjusting synthetic parameters including the mass ratio of MgAl-LDH to SiO2, the mixing temperature and time. The optimal SiO2@MgAl-LDH nanocomposite was shown to have SiO2 nanodots (10-15nm in diameter) evenly deposited on the surface of MgAl-LDHs (110nm in diameter) with the plate-like morphology and the average hydrodynamic diameter of 170nm. We further employed SiO2@MgAl-LDH nanocomposite as a nanocarrier to deliver methotrexate (MTX), a chemotherapy drug, to the human osteosarcoma cell (U2OS) and found that MTX delivered by SiO2@MgAl-LDH nanocomposite apparently inhibited the U2OS cell growth.

  1. H2O2O2协同引发的TiO2/Fe3+光催化降解苯酚%H2O2 and O2 combined-leading photo-catalytic degradation of phenol with TiO2/Fe3+ 

    王西峰; 彭党聪; 胡晓莲


    Class fiber used as carrier, TiO2/Fe3+ has been loaded to its surfacee,forming the space glass fiber reactor. Using high pressure mercury lamp as its light source,so as to carry out the experimental research on the degradation of phenol in water. The influences of the synergistic effect of H2O2 and O2 on photo-catalysis oxidation are investigated emphatically. It is found through experiments that adding H2O2 has remarkable initiation effect on the production of HO? ,and oxygenizing to the solution can obviously improve the efficiency of photo-catalysis and reduce H2O2 dosage. The results show that the phenol mineralization rate can reach about 83% ,when the power of UV365 high pressure mercury lamp is 250 W,pH 3-5,O2 inlet quantity 1.0 L/(min?L),H2O2 dosage 0.1 mmol/L, rising flow rate in the reactor 0.7 m/min, initial mass concentration of phenol wastewater 30 mg/L,and photo-catalystic reaction time 120 min.%以玻璃纤维为载体,将TiO2/Fe3+负载到其表面制成了空间玻璃纤维反应器.利用该反应器以高压汞灯为光源进行了光催化降解水中苯酚的试验研究,重点考察了H2O2O2的协同作用对光催化氧化的影响.试验发现,H2O2的加入对HO·的产生有显著的引发作用,同时向溶液中充入O2可明显提高光催化效率,降低H2O2用量.试验结果表明,以UV365-250W光源照射,在初始pH为3~5,O2通入量为1.0L/(min·L),上升流速为0.7 m/min,H2O2浓度为0.1mmol/L等试验条件下,初始质量浓度为30mgL的苯酚废水经120 min光催化反应后,其矿化率可达83%左右.

  2. Extended Lagrange interpolation in L1 spaces

    Occorsio, Donatella; Russo, Maria Grazia


    Let w (x )=e-xβxα , w ¯(x )=x w (x ) and denote by {pm(w)}m,{pn(w¯)}n the corresponding sequences of orthonormal polynomials. The zeros of the polynomial Q2 m +1=pm +1(w )pm(w ¯) are simple and are sufficiently far among them. Therefore it is possible to construct an interpolation process essentially based on the zeros of Q2m+1, which is called "Extended Lagrange Interpolation". Here we study the convergence of this interpolation process in suitable weighted L1 spaces. This study completes the results given by the authors in previous papers in weighted Lup((0 ,+∞ )) , for 1≤p≤∞. Moreover an application of the proposed interpolation process in order to construct an e cient product quadrature scheme for weakly singular integrals is given.

  3. Contribution of L1 in EFL Teaching

    Wahjuningsih Usadiati


    Full Text Available This study is conducted in a classroom action research to improve the students’ achievement in writing English sentences in Present Perfect Tense in Structure 1 lessons. The subject consisted of 20 Semester II students who took Structure I lessons in English Education Department of Palangka Raya University, Central Kalimantan, Indonesia. The data were taken from the results of pre test and post test after the action was done. The results show that in cycle 1, in which the explanations were fully in English, only 40% of the students got a good achievement; 5-7 out of 20 test items were correct. After cycle 2 was done using L1 interchangeably with English in the explanations, the students’ achievement of writing English sentences in Present Perfect Tense increased to 75%, in which 15-18 out 20 test items were correct.

  4. Extremely fast dark adsorption rate of carbon and nitrogen co-doped TiO2 prepared by a relatively fast, facile and low-cost microwave method

    Du, Chun; Zhou, Jiangshan; Li, Fangzhou; Li, Wei; Wang, Yinzhen; He, Qinyu


    A facile and low-cost microwave method was used to prepare C and N co-doped TiO2 in just 8 min. The prepared samples were thoroughly characterized and were found to have favourable features such as surface adsorption of pollutants and photocatalysis. The rapid decomposition of CH5N3HCl under microwave irradiation led to mesopores and surface roughness in the as-prepared particles, resulting in large surface adsorption of pollutant and good photodegradation. The best sample is the one with the ratio of TiO2/CH2N3HCl at 3:1, which adsorbed 86.3 % of a methylene orange (MO) solution (20 mg L-1) in 10 min.

  5. Photoelectrocatalytic degradation of acid dye using Ni-TiO2 with the energy supplied by solar cell: mechanism and economical studies.

    Olya, Mohammad Ebrahim; Pirkarami, Azam; Soleimani, Majid; Bahmaei, Manochehr


    This paper reports an investigation into the effect of a number of operating factors on the removal of Acid Red 88 from an aqueous solution through photoelectrocatalysis: photocatalyst dose, dye concentration, pH, bias potential, and electrolyte concentration. The photocatalyst was Ni-TiO2 applied in suspension to the solution to achieve a larger catalyst surface area. The optimum values for photocatalyst dose, dye concentration, and electrolyte concentration turned out to be 0.6 mg L(-1), 50 mg L(-1), and 5 mg L(-1), respectively. Also, the best pH was found to be 7, and bias potential proved to be best at 1.6 V. The aqueous solution was characterized for its COD and TOC. Photocatalyst efficiency was evaluated using SEM and XRD techniques. The characterization of the post-treatment product using FT-IR, HPLC, and GC-MS studies revealed intermediate compounds. A pathway was proposed for the degradation of the dye. The energy required by the experiment was supplied by solar cells, meaning the money that would have otherwise been spent on electricity was saved. Cost analysis was also done for the treatment process. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. [Effects and mechanisms of inorganic anions in water on degradation of LAS by UV/H2 O2 combination process].

    Pan, Jing; Sun, Tie-Heng; Li, Hai-Bo


    Experiments are carried out to study the effects and mechanisms of inorganic anions in water on the degradation of linear alkyl benzene sulfonate (LAS) in UV/H2 O2 process. The results show that UV/H2 O2 process could remove LAS effectively, and the rate of photodegradation follows first-order reaction kinetics model. Under the condition that H2 O2 concentration was 8 mg x L(-1) and a 14 W low pressure mercury vapor discharge lamp irradiated samples, the first-order photodegradation rate constant of LAS in distilled water and tap water were 0.018 0 min(-1) and 0.012 2 min(-1) respectively. NO3-, Cl-, SO4(2-) and HCO3- have inhibitory action on LAS photodegradation. The higher inorganic anions concentration was, the stronger inhibitory action. When their concentrations were 5, 10 and 15 mmol x L(-1) respectively, their inhibitory action order was HCO3- > NO3- > Cl- > SO4(2-) all the time. It was anions synthetical effect that caused photodegradation rate constant of LAS in tap water lower than distilled water.

  7. Photocatalytic degradation of methyl orange: influence of H2O2 in the TiO2-based system.

    Andronic, Luminita; Manolache, Simona; Duta, Anca


    The purpose of this study was to investigate the photocatalytic oxidation of a reactive azo dye. The photocatalytic activity of the TiO2 was studied using a reactor equipped with UV-A sources, with maximum emission at 365 nm. The photocatalytic activity of the TiO2 powder (99.9% anatase) and thin films has been measured through the decomposition of methyl orange solutions. The thin film was prepared by doctor blade and spray pyrolysis deposition (SPD). The TiO2 suspensions were prepared at 1 g/L concentration, and the initial methyl orange concentration was fixed at 7.8125 mg/L. The influence of the TiO2 (powder or thin films) and/or O2 and H2O2 on the photobleaching rate, was tested under different experiments, at pH = 5. Thin films (doctor blade) of TiO2 formed of mezo-sized aggregates formed of nanosized anatase crystallites show better photobleaching efficiency than thin film (SPD) due to their large internal surface. The rate is even higher in H2O2 compared to oxygen environment.

  8. The pilot test on the treatment of refined cotton wastewater by A/O2 + adification-catalytic oxidation process%A/O2+酸析-催化氧化工艺处理精制棉废水的中试研究

    同帜; 邹坦胜; 陈超产


    精制棉废水属于难处理的工业废水之一,本文采用A/O2+酸析-催化氧化工艺对其进行处理,并取得了良好的中试效果.生化部分的COD去除率达82%以上,色度去除率高于50%.实验结果表明,酸析过程中调节pH约为2 5,催化氧化过程中H2O2及FeSO4的投药量分别为0.8mg·L-1与160mg·L-1时,后处理的主要出水控制指标COD降至135mg · L-1以下,色度降至150倍以下.此外,通过观察发现脱氢酶活性较高,生物相中能反应水质良好的固着性纤毛虫和钟虫占优势.%A/O2 + adification-catalytic oxidation process is adopted to deal with the refined cotton wastewater which is one of the most intractable industrial wastewater, and there is a good result in the pilot test. In biological part, the removal rate of COD and color is respectively over 82% and 50%. When the pH in edification is about 2. 5, and the reagent dose of H2O2 and FeSO4 is respectively 0.8 mg/L and 160 mg/L, the main index COD of water after treatment drops below 135mg/L, and the color degree is less than 150 times. In addition, according to the observation, the dehydroenase's activity is higher, and the rotifer and vorticella are the dominant microbes in biological phase.

  9. Analysis list: Tcf7l1 [Chip-atlas[Archive

    Full Text Available Tcf7l1 Embryonic fibroblast + mm9

  10. Functionalization of Fe3O4/SiO2 with N-(2-Aminoethyl-3-aminopropyl for Sorption of [AuCl4]-

    Nuryono Nuryono


    Full Text Available Synthesis of Fe3O4/SiO2 modified with N-(2-aminoethyl-3-aminopropyl group (Fe3O4/SiO2/ED via coating method and its application for adsorption-desorption of anionic gold in aqueous solution have been conducted. The synthesized product was characterized with an X-ray diffractometer (XRD, a Fourier transform infrared (FT-IR spectrophotometer and a transmission electron microscopy (TEM. Adsorption of Au(III was conducted in a batch system and the variables included pH, contact time, and initial concentration were investigated. Results showed that magnetite/silica has been successfully functionalized with N-(2-aminoethyl-3-aminopropyl in a homogeneous system. Kinetics study showed that adsorption of Au(III followed the pseudo-second order model with rate constant of 0.710 g mmol L-1min-1. Furthermore, the experimental data fitted well with the Langmuir isotherm model with the maximum adsorption capacity for Au(III of 142.9 mg g-1 and the energy of 25.0 kJ mol-1. Gold loaded on the Fe3O4/SiO2/ED could be easily desorbed with 0.2 mol L-1 HCl containing 2 wt.% of thiourea with recovery of 99.8%. Fe3O4/SiO2/ED was reusable and stable in 5 cycles of adsorption-desorption with recovery more than 90%. Fe3O4/SiO2/ED showed high selectivity towards Au(III in the multimetal system Au(III/Cu(II/Cr(VI with the coefficient selectivity for αAu-Cu of 227.5and for αAu-Cr of 12.3.

  11. Degradation of organic contaminants in effluents-synthetic and from the textile industry-by Fenton, photocatalysis, and H2O2 photolysis.

    de Lima, L B; Pereira, L O; de Moura, S G; Magalhães, F


    In this study, the oxidation of the dye rhodamine B (RhB), present in a synthetic effluent, and the degradation of organic matter present in a textile effluent, were assessed by photolysis (H2O2, UV), homogeneous Fenton (Fe(2+), H2O2), and photocatalysis (TiO2, UV). The results showed that photolysis and Fenton had an efficiency of 100 % and photocatalysis, 96 %, to discoloration 10 mg L(-1) RhB, present in the synthetic effluent. The best experimental conditions determined for these reactions showed that the one performed with 51 mg L(-1) H2O2 and UV light had the best results, where 100 % of RhB was discolored in only 6 min of reaction. The optimum conditions determined in the first part of this study for the RhB oxidation did not show satisfactory results for the degradation of organic matter present in the textile effluent sample, and it was necessary to increase the amount of reagents in the three processes. After resizing the concentration of the reagents for the reactions with the textile effluent, the following reductions of color, total organic carbon (TOC), and total soluble solids (SS) were obtained: photocatalysis 29, 25, and 32 %; photolysis 85, 69, and 35 %; Fenton 98, 90, and 23 %; and biological (followed by physicochemical) treatment carried out by the textile industry 96, 48, and 9 %. It is observed that the Fenton reaction showed the best result, followed by photolysis reaction, a treatment carried out by industry and, at last, photocatalysis.

  12. UV-visible light-activated Ag-decorated, monodisperse TiO2 aggregates for treatment of the pharmaceutical oxytetracycline.

    Han, Changseok; Likodimos, Vlassis; Khan, Javed Ali; Nadagouda, Mallikarjuna N; Andersen, Joel; Falaras, Polycarpos; Rosales-Lombardi, Pablo; Dionysiou, Dionysios D


    Noble metal Ag-decorated, monodisperse TiO2 aggregates were successfully synthesized by an ionic strength-assisted, simple sol-gel method and were used for the photocatalytic degradation of the antibiotic oxytetracycline (OTC) under both UV and visible light (UV-visible light) irradiation. The synthesized samples were characterized by X-ray diffraction analysis (XRD); UV-vis diffuse reflectance spectroscopy; environmental scanning electron microscopy (ESEM); transmission electron microscopy (TEM); high-resolution TEM (HR-TEM); micro-Raman, energy-dispersive X-ray spectroscopy (EDS); and inductively coupled plasma optical emission spectrometry (ICP-OES). The results showed that the uniformity of TiO2 aggregates was finely tuned by the sol-gel method, and Ag was well decorated on the monodisperse TiO2 aggregates. The absorption of the samples in the visible light region increased with increasing Ag loading that was proportional to the amount of Ag precursor added in the solution over the tested concentration range. The Brunauer, Emmett, and Teller (The BET) surface area slightly decreased with increasing Ag loading on the TiO2 aggregates. Ag-decorated TiO2 samples demonstrated enhanced photocatalytic activity for the degradation of OTC under UV-visible light illumination compared to that of pure TiO2. The sample containing 1.9 wt% Ag showed the highest photocatalytic activity for the degradation of OTC under both UV-visible light and visible light illumination. During the experiments, the detected Ag leaching for the best TiO2-Ag photocatalyst was much lower than the National Secondary Drinking Water Regulation for Ag limit (0.1 mg L(-1)) issued by the US Environmental Protection Agency.

  13. The vulnerability of gender on determiners in L1, 2L1 and L2 acquisition

    van der Linden, E.; Hulk, A.


    The acquisition of gender has been reported to be problematic for some groups of learners acquiring Germanic or Romance languages. It has been shown that L1 learners do better in gender acquisition than others, like bilingual children, child L2 learners and adult L2 learners. The reason for these di

  14. The vulnerability of gender on determiners in L1, 2L1 and L2 acquisition

    van der Linden, E.; Hulk, A.


    The acquisition of gender has been reported to be problematic for some groups of learners acquiring Germanic or Romance languages. It has been shown that L1 learners do better in gender acquisition than others, like bilingual children, child L2 learners and adult L2 learners. The reason for these

  15. Organic micropollutants (OMPs) in natural waters: Oxidation by UV/H2O2 treatment and toxicity assessment.

    Rozas, Oscar; Vidal, Cristiane; Baeza, Carolina; Jardim, Wilson F; Rossner, Alfred; Mansilla, Héctor D


    Organic micropollutants (OMPs) are ubiquitous in natural waters even in places where the human activity is limited. The presence of OMPs in natural water sources for human consumption encourages the evaluation of different water purification technologies to ensure water quality. In this study, the Biobío river (Chile) was selected since the watershed includes urban settlements and economic activities (i.e. agriculture, forestry) that incorporate a variety of OMPs into the aquatic environment, such as pesticides, pharmaceuticals and personal care products. Atrazine (herbicide), caffeine (psychotropic), diclofenac (anti-inflammatory) and triclosan (antimicrobial) in Biobío river water and in different stages of a drinking and two wastewater treatment plants downstream Biobío river were determined using solid phase extraction (SPE) and liquid chromatography/tandem mass spectrometry (LC-MS/MS) and electrospray ionization (ESI). Quantification of these four compounds showed concentrations in the range of 8 ± 2 to 55 ± 10 ng L(-1) in Biobío river water, 11 ± 2 to 74 ± 21 ng L(-1) in the drinking water treatment plant, and 60 ± 10 to 15,000 ± 1300 ng L(-1) in the wastewater treatment plants. Caffeine was used as an indicator of wastewater discharges. Because conventional water treatment technologies are not designed to eliminate some emerging organic pollutants, alternative treatment processes, UV and UV/H2O2, were employed. The transformation of atrazine, carbamazepine (antiepileptic), diclofenac and triclosan was investigated at laboratory scale. Both processes were tested at different UV doses and the Biobío river water matrix effects were evaluated. Initial H2O2 concentration used was 10 mg L(-1). Results showed that, the transformation profile obtained using UV/H2O2 at UV doses up to 900 mJ cm(-2), followed the trend of diclofenac > triclosan > atrazine > carbamazepine. Furthermore acute toxicity tests with Daphnia magna were carried

  16. Preparation and photocatalytic activity of ternary composite catalyst:Ce-SiO2-TiO2%Ce-SiO2-TiO2三元复合催化剂的制备及其光催化降解性能

    刘涛; 隋国哲; 甄德帅; 李金龙; 佟白


    采用溶胶-凝胶法制备了Ce-SiO2-TiO2三元复合纳米催化剂,用TG-DTA、FT-IR、XRD和UV-Vis等对样品的结构进行了表征,并以罗丹明B(RhB)作为探针反应,分别在紫外光和可见光照下评价了其光催化性能.与TiO2一元纳米催化剂和Ce-TiO2、SiO2-TiO2二元纳米催化剂进行对比,Ce-SiO2-TiO2三元复合纳米催化剂对罗丹明B溶液(5 mg/L)表现出更高的光催化降解性能,可见光下的降解率达到98.5%.%The ternary composite nano photocatalysts of Ce-SiO2-TiO2 were prepared by sol-gel meth-od, which were characterized by TG-DTA, FT-IR, XRD and UV-Vis. The photocatalytic activities of Ce-SiO2-TiO2 nanocomposites were investigated for the degradation of Rhodamine B (RhB) as a probe under the il umina-tion of UV and visible light. Compared with the photocatalytic activities of TiO2, Ce-TiO2 and SiO2-TiO2, the ter-nary composite nano photocatalyst of Ce-SiO2-TiO2 showed the highest photodegradation, and the photodeg-radation rate of RhB (5 mg/L) could reach above 98.5%under visible light.

  17. Electrochemical oxidation of cyanide on 3D Ti-RuO2 anode using a filter-press electrolyzer.

    Pérez, Tzayam; López, Rosa L; Nava, José L; Lázaro, Isabel; Velasco, Guillermo; Cruz, Roel; Rodríguez, Israel


    The novelty of this communication lies in the use of a Ti-RuO2 anode which has not been tested for the oxidation of free cyanide in alkaline media at concentrations similar to those found in wastewater from the Merrill Crowe process (100 mg L(-1) KCN and pH 11), which is typically used for the recovery of gold and silver. The anode was prepared by the Pechini method and characterized by SEM. Linear sweep voltammetries on a Ti-RuO2 rotating disk electrode (RDE) confirmed that cyanide is oxidized at 0.45 < E < 1.0 V vs SHE, while significant oxygen evolution reaction (OER) occurred. Bulk oxidation of free cyanide was investigated on Ti-RuO2 meshes fitted into a filter-press electrolyzer. Bulk electrolyzes were performed at constant potentials of 0.85 V and 0.95 V and at different mean linear flow rates ranging between 1.2 and 4.9 cm s(-1). The bulk anodic oxidation of cyanide at 0.85 V and 3.7 cm s(-1) achieved a degradation of 94%, with current efficiencies of 38% and an energy consumption of 24.6 kWh m(-3). Moreover, the degradation sequence of cyanide was also examined by HPLC. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Determination of TiO2 and AgTiO2 Nanoparticles in Artemia salina: Toxicity, Morphological Changes, Uptake and Depuration.

    Ozkan, Yesim; Altinok, Ilhan; Ilhan, Hasan; Sokmen, Munevver


    In this study, aquatic stability and toxic effects of TiO2 and AgTiO2 nanoparticles (NPs) were investigated on Artemia salina nauplii. AgTiO2 was found to be more toxic to nauplii compared to TiO2. The mortality rate in nauplii increased significantly with increasing concentrations and duration of exposure. TiO2 eliminations ranged between 27.8% and 96.5% at 50 and 1 mg/L TiO2 exposed to nauplii, respectively. Accumulation and elimination of Ag in AgTiO2 exposed nauplii were similar except at 1 mg/L AgTiO2. When NPs were mixed with water, the hydrodynamic dimensions of NPs significantly increased because of aggregation in saltwater but NP size decreased over time. NPs-exposed nauplii showed changes in eye formation, enlargement of the intestine, malformations in the outer shell and antennae loss were also observed. Since accumulation and toxicity of AgTiO2 NPs was higher than TiO2 alone, inevitably release of AgTiO2 into aqueous environments can cause ecological risks.

  19. O2 reduction and denitrification rates in shallow aquifers

    Tesoriero, Anthony J.; Puckett, Larry J.


    O2 reduction and denitrification rates were determined in shallow aquifers of 12 study areas representing a wide range in sedimentary environments and climatic conditions. Zero- and first-order rates were determined by relating reactant or product concentrations to apparent groundwater age. O2 reduction rates varied widely within and between sites, with zero-order rates ranging from 100 μmol N L-1 yr-1; >0.36 yr-1) occur when changes in lithology result in a sharp increase in the supply of electron donors. Denitrification lag times (i.e., groundwater travel times prior to the onset of denitrification) ranged from 80 yr. The availability of electron donors is indicated as the primary factor affecting O2 reduction rates. Concentrations of dissolved organic carbon (DOC) and/or sulfate (an indicator of sulfide oxidation) were positively correlated with groundwater age at sites with high O2 reduction rates and negatively correlated at sites with lower rates. Furthermore, electron donors from recharging DOC are not sufficient to account for appreciable O2 and nitrate reduction. These relations suggest that lithologic sources of DOC and sulfides are important sources of electrons at these sites but surface-derived sources of DOC are not. A review of published rates suggests that denitrification tends to occur more quickly when linked with sulfide oxidation than with carbon oxidation.

  20. Potential of BAC combined with UVC/H2O2 for reducing organic matter from highly saline reverse osmosis concentrate produced from municipal wastewater reclamation.

    Lu, Jie; Fan, Linhua; Roddick, Felicity A


    The organic matter present in the concentrate streams generated from reverse osmosis (RO) based municipal wastewater reclamation processes poses environmental and health risks on its disposal to the receiving environment (e.g., estuaries, bays). The potential of a biological activated carbon (BAC) process combined with pre-oxidation using a UVC/H2O2 advanced oxidation process for treating a high salinity (TDS~10000 mg L(-1)) municipal wastewater RO concentrate (ROC) was evaluated at lab scale during 90 d of operation. The combined treatment reduced the UVA254 and colour of the ROC to below those for the influent of the RO process (i.e., biologically treated secondary effluent), and the reductions in DOC and COD were approximately 60% and 50%, respectively. UVC/H2O2 was demonstrated to be an effective means of converting the recalcitrant organic compounds in the ROC into biodegradable substances which were readily removed by the BAC process, leading to a synergistic effect of the combined treatment in degrading the organic matter. The tests using various BAC feed concentrations suggested that the biological treatment was robust and consistent for treating the high salinity ROC. Using Microtox analysis no toxicity was detected for the ROC after the combined treatment, and the trihalomethane formation potential was reduced from 3.5 to 2.8 mg L(-1). Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Chemical Oxidation Degradation of Thiamethoxam in Fe2+/S2O2-8/S2O2-3 Aqueous Solution%Fe2+/S2O2-8/S2O2-3体系下噻虫嗪的降解研究

    阳海; 庞怀林; 谭小军; 胡志斌; 张文强; 彭嘉运; 易兵


    Thiamethoxam, one of neonicotinoid insecticides, is characterized with low soil sorption and high water solubility, making it a po-tential contaminant of surface and underground water. Here we examined the chemical oxidation degradation of thiamethoxam in Fe2+/S2O2-8/S2O2-3 aqueous solution. The results showed that the degradation efficiency of thiamethoxam was 99.9%after 240 min reaction. The oxidizing ability of Fe2+/S2O2-8/S2O2-3 was significantly affected by the concentrations of Fe2+, S2O2-8 and S2O2-3 . Three ion interactions experiment by the central composite design(CCD)showed that the optimum ratios for Fe2+/S2O2-8/S2O2-3 system were 0.69 mmol·L-1 Fe2+, 0.69 mmol·L-1 S2O2-3 and 3.29 mmol·L-1 S2O2-8 . Higher degradation efficiency was observed at pH=9.0. Thiamethoxam degradation was reduced by higher concen-trations of substrate and presence of reactive oxidative species scavengers.%为探讨噻虫嗪在Fe2+/S2O2-8/S2O2-3体系下降解情况,首先通过单因素实验研究了不同Fe2+、S2O2-8和S2O2-3浓度对噻虫嗪降解率的影响,然后通过中心复合实验,研究各单因素之间的相互影响,得出了Fe2+/S2O2-8/S2O2-3体系下Fe2+、S2O2-8和S2O2-3三种离子的最佳配比,建立了噻虫嗪化学氧化降解模型,并确定其最佳降解条件为:Fe2+浓度为0.69 mmol·L-1,S2O2-3为0.69 mmol·L-1,S2O2-8为3.29 mmol·L-1。最后在三种离子最佳配比条件下探究了不同溶液初始pH值、不同底物浓度及其活性氧物种淬灭剂对噻虫嗪的降解情况影响。研究结果表明,噻虫嗪在pH=9.0时降解率较好,噻虫嗪的降解率随着底物浓度的增加而减小,活性氧物种淬灭剂会降低噻虫嗪的降解率。

  2. 铁酸锌-二氧化钛/氧化镧纳米复合物的制备及降解溴甲酚绿的研究%Photocatalytic Degradation of Bromocresol Green under Solar Light Irradiation Combined with ZnFe2O4/TiO2-La2O3 Composites

    丁永萍; 郭玉玮


    采用共沉淀法制备了ZnFe2O4和超声分散法制备了ZnFe2O4/TiO2-La2O3、ZnFe2O4/TiO2和TiO2-La2O3复合物,同时用扫描电镜(SEM)对ZnFe2O4/TiO2-La2O3、ZnFe2O4/TiO2和TiO2进行检验分析,考查了溴甲酚绿的光催化降解,评价了光催化活性,并与ZnFe2 O4/TiO2-La2O3、ZnFe2O4/TiO2、TiO2-LaO3和纯TiO2的光催化性能进行了比较.并且考察了催化剂的量、焙烧温度、焙烧时间、光照时间、初始浓度等对溴甲酚绿降解率的影响.结果表明,在500℃条件下煅烧60 min时,ZnFe2O4/TiO2-La2O3具有更好的光催化性能.当催化剂浓度为1.00g·L-1,溴甲酚绿溶液浓度为10 mg·L-1,反应时间为150 min时,ZnFe2O4/TiO2-La2O3、ZnFe2O4/TiO2、TiO2-La2O3和TiO2降解率分别为87.53%、62.67%、56.13%和39.42%.

  3. Rendezvous missions with minimoons from L1

    Chyba, M.; Haberkorn, T.; Patterson, G.


    We propose to present asteroid capture missions with the so-called minimoons. Minimoons are small asteroids that are temporarily captured objects on orbits in the Earth-Moon system. It has been suggested that, despite their small capture probability, at any time there are one or two meter diameter minimoons, and progressively greater numbers at smaller diameters. The minimoons orbits differ significantly from elliptical orbits which renders a rendezvous mission more challenging, however they offer many advantages for such missions that overcome this fact. First, they are already on geocentric orbits which results in short duration missions with low Delta-v, this translates in cost efficiency and low-risk targets. Second, beside their close proximity to Earth, an advantage is their small size since it provides us with the luxury to retrieve the entire asteroid and not only a sample of material. Accessing the interior structure of a near-Earth satellite in its morphological context is crucial to an in-depth analysis of the structure of the asteroid. Historically, 2006 RH120 is the only minimoon that has been detected but work is ongoing to determine which modifications to current observation facilities is necessary to provide detection algorithm capabilities. In the event that detection is successful, an efficient algorithm to produce a space mission to rendezvous with the detected minimoon is highly desirable to take advantage of this opportunity. This is the main focus of our work. For the design of the mission we propose the following. The spacecraft is first placed in hibernation on a Lissajoux orbit around the liberation point L1 of the Earth-Moon system. We focus on eight-shaped Lissajoux orbits to take advantage of the stability properties of their invariant manifolds for our transfers since the cost to minimize is the spacecraft fuel consumption. Once a minimoon has been detected we must choose a point on its orbit to rendezvous (in position and velocities

  4. Aplicação de processo oxidativo avançado baseado em fotocatálise heterogênea (TiO2/UVsolar para o pré-tratamento de afluente lácteo

    Rodrigo Fernando Santos Salazar


    Full Text Available The aim of this work was to evaluate a pretreatment system for dairy wastewater based on an advanced oxidative process (AOP. An AOP treatment based on photocatalysis was applied to reduce the organic load in dairy effluents obtained from the dairy process, such as cream, yoghurt and pasteurized milk. Titanium dioxide was used as a semiconductor. It was finely distributed and fixed with poliuretanic ink on a flat metallic plate where the effluent was circulated on its catalytic bed fixed at a 23º angle. This AOP process was exposed to direct solar radiation. Some process factors were analyzed: pH influence (5 or 7, reaction time (120 or 180 min, TiO2 photocatalytic activity (anatase or rutile and initial organic load in the effluent (In natura or 1:1 v/v of effluent water. The best conditions for AOP process were determined through an experimental design (24-1. Process efficiency was obtained through chemical oxygen demand (COD tests. The best conditions for AOP were: reaction time of 180 min; TiO2 anatase; pH 5 and In nature effluent with percentage removed COD (%CODrem above 54.77 ± 1.66 %, representing a COD reduction from 3782.5 ± 37.6 mg.L-1 to 1710.4 ± 0.3 mg.L-1 and the reduction of total organic carbon of 983.6 ± 37.6 mg.L-1 in 606.8 ± 2.0 mg.L-1.

  5. VUV-Photocatalytic Degradation of Bezafibrate by Hydrothermally Synthesized Enhanced {001} Facets TiO2/Ti Film.

    Sayed, Murtaza; Fu, Pingfeng; Shah, Luqman Ali; Khan, Hasan M; Nisar, Jan; Ismail, M; Zhang, Pengyi


    In the present study, a novel TiO2/Ti film with enhanced {001} facets was synthesized by the hydrothermal technique followed by calcination for studying the removal of bezafibrate (BZF), from an aqueous environment. The synthesized photocatalyst was characterized by FE-SEM, XRD, HR-TEM, and PL-technique. The second-order rate constant of (•)OH with BZF was found to be 5.66 × 10(9) M(-1) s(-1). The steady state [(•)OH] was measured as 1.16 × 10(-11) M, on the basis of oxidation of terephthalic acid. The photocatalytic degradation of BZF followed pseudo-first-order kinetics according to the Langmuir-Hinshelwood model (k1 = 2.617 mg L(-1) min(-1) and k2 = 0.0796 (mg L(-1))(-1)). The effects of concentration and the nature of various additives including inorganic anions (NO3(-), NO2(-), HCO3(-), CO3(2-), Cl(-)) and organic species (fulvic acid) and initial solution pHs (2, 4, 6, 9) on photocatalytic degradation of BZF were investigated. It was found that the nature and concentration of studied additives significantly affected the photocatalytic degradation of BZF. The efficiency of the photocatalytic degradation process in terms of electrical energy per order was estimated. Degradation schemes were proposed on the basis of the identified degradation byproducts by ultraperformance liquid chromatography.

  6. Photocatalytic antibacterial performance of TiO2 and Ag-doped TiO2 against S. aureus. P. aeruginosa and E. coli.

    Gupta, Kiran; Singh, R P; Pandey, Ashutosh; Pandey, Anjana


    This paper reports the structural and optical properties and comparative photocatalytic activity of TiO2 and Ag-doped TiO2 nanoparticles against different bacterial strains under visible-light irradiation. The TiO2 and Ag-doped TiO2 photocatalysts were synthesized by acid catalyzed sol-gel technique and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis spectroscopy and photoluminescence (PL). The XRD pattern revealed that the annealed sample of TiO2 has both anatase and rutile phases while only an anatase phase was found in Ag-doped TiO2 nanoparticles. The decreased band-gap energy of Ag-doped TiO2 nanoparticles in comparison to TiO2 nanoparticles was investigated by UV-vis spectroscopy. The rate of recombination and transfer behaviour of the photoexcited electron-hole pairs in the semiconductors was recorded by photoluminescence. The antimicrobial activity of TiO2 and Ag-doped TiO2 nanoparticles (3% and 7%) was investigated against both gram positive (Staphylococcus aureus) and gram negative (Pseudomonas aeruginosa, Escherichia coli) bacteria. As a result, the viability of all three microorganisms was reduced to zero at 60 mg/30 mL culture in the case of both (3% and 7% doping) concentrations of Ag-doped TiO2 nanoparticles. Annealed TiO2 showed zero viability at 80 mg/30 mL whereas doped Ag-TiO2 7% showed zero viability at 40 mg/30 mL culture in the case of P. aeruginosa only.

  7. Photocatalytic antibacterial performance of TiO2 and Ag-doped TiO2 against S. aureus. P. aeruginosa and E. coli

    Kiran Gupta


    Full Text Available This paper reports the structural and optical properties and comparative photocatalytic activity of TiO2 and Ag-doped TiO2 nanoparticles against different bacterial strains under visible-light irradiation. The TiO2 and Ag-doped TiO2 photocatalysts were synthesized by acid catalyzed sol–gel technique and characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, UV–vis spectroscopy and photoluminescence (PL. The XRD pattern revealed that the annealed sample of TiO2 has both anatase and rutile phases while only an anatase phase was found in Ag-doped TiO2 nanoparticles. The decreased band-gap energy of Ag-doped TiO2 nanoparticles in comparison to TiO2 nanoparticles was investigated by UV–vis spectroscopy. The rate of recombination and transfer behaviour of the photoexcited electron–hole pairs in the semiconductors was recorded by photoluminescence. The antimicrobial activity of TiO2 and Ag-doped TiO2 nanoparticles (3% and 7% was investigated against both gram positive (Staphylococcus aureus and gram negative (Pseudomonas aeruginosa, Escherichia coli bacteria. As a result, the viability of all three microorganisms was reduced to zero at 60 mg/30 mL culture in the case of both (3% and 7% doping concentrations of Ag-doped TiO2 nanoparticles. Annealed TiO2 showed zero viability at 80 mg/30 mL whereas doped Ag-TiO2 7% showed zero viability at 40 mg/30 mL culture in the case of P. aeruginosa only.

  8. Degradation of Pentachlorophenol in Aqueous Solution by the UV/ZrO 2 /H 2 O 2 Photocatalytic Process

    Mohammad Reza Samarghandi


    Full Text Available Pentachlorophenol (PCP, which is one of the resistant phenolic compounds, has been classified in the category of EPA’s priority pollutants due to its high toxicity and carcinogenic potential. Therefore, its removal from water and wastewater is very important. Various methods have been studied for removing the compound, among which advanced oxidation processes (AOPs have attracted much attention because of ease of application and high efficiency. Thus the aim of this study was to investigate the efficiency of the UV/ZrO2/H2O2 process, as an AOP, for PCP removal from aquatic environments. The effects of several parameters such as ultraviolet (UV exposure time, initial PCP concentration, pH, concentration of zirconium dioxide (ZrO2 nanoparticles, and H2O2 concentration were studied. Kinetics of the reaction was also detected. The concentration of the stated materials in the samples was determined using a spectrophotometer at 500 nm. The results showed that the highest efficiency (approximately 100% was reached at optimized conditions of pH 6, contact time of 30 minutes, initial PCP concentration of 20 mg/L, the nanoparticles concentration of 0.1 g/L and H2O2 concentration of 14.7 mM/L. Also, the process followed the first order kinetics reaction. The obtained results illustrated that the UV/ZrO2/H2O2 process has a high ability in removing PCP.

  9. Structural characterization of nanosized CeO(2)-SiO(2), CeO(2)-TiO(2), and CeO(2)-ZrO(2) catalysts by XRD, Raman, and HREM techniques.

    Reddy, Benjaram M; Khan, Ataullah; Lakshmanan, Pandian; Aouine, Mimoun; Loridant, Stéphane; Volta, Jean-Claude


    Structural characteristics of nanosized ceria-silica, ceria-titania, and ceria-zirconia mixed oxide catalysts have been investigated using X-ray diffraction (XRD), Raman spectroscopy, BET surface area, thermogravimetry, and high-resolution transmission electron microscopy (HREM). The effect of support oxides on the crystal modification of ceria cubic lattice was mainly focused. The investigated oxides were obtained by soft chemical routes with ultrahighly dilute solutions and were subjected to thermal treatments from 773 to 1073 K. The XRD results suggest that the CeO(2)-SiO(2) sample primarily consists of nanocrystalline CeO(2) on the amorphous SiO(2) surface. Both crystalline CeO(2) and TiO(2) anatase phases were noted in the case of CeO(2)-TiO(2) sample. Formation of cubic Ce(0.75)Zr(0.25)O(2) and Ce(0.6)Zr(0.4)O(2) (at 1073 K) were observed in the case of the CeO(2)-ZrO(2) sample. Raman measurements disclose the fluorite structure of ceria and the presence of oxygen vacancies/Ce(3+). The HREM results reveal well-dispersed CeO(2) nanocrystals over the amorphous SiO(2) matrix in the cases of CeO(2)-SiO(2), isolated CeO(2), and TiO(2) (anatase) nanocrystals, some overlapping regions in the case of CeO(2)-TiO(2), and nanosized CeO(2) and Ce-Zr oxides in the case of CeO(2)-ZrO(2) sample. The exact structural features of these crystals as determined by digital diffraction analysis of HREM experimental images reveal that the CeO(2) is mainly in cubic fluorite geometry. The oxygen storage capacity (OSC) as determined by thermogravimetry reveals that the OSC of the mixed oxide systems is more than that of pure CeO(2) and is system dependent.

  10. Comparative study of diethyl phthalate degradation by UV/H2O2 and UV/TiO2: kinetics, mechanism, and effects of operational parameters.

    Song, Chengjie; Wang, Liping; Ren, Jie; Lv, Bo; Sun, Zhonghao; Yan, Jing; Li, Xinying; Liu, Jingjing


    The photodegradation of diethyl phthalate (DEP) by UV/H2O2 and UV/TiO2 is studied. The DEP degradation kinetics and multiple crucial factors effecting the clearance of DEP are investigated, including initial DEP concentration ([DEP]0), initial pH values (pH0), UV light intensity, anions (Cl(-), NO(3-), SO4 (2-), HCO3 (-), and CO3 (2-)), cations (Mg(2+), Ca(2+), Mn(2+), and Fe(3+)), and humic acid (HA). Total organic carbon (TOC) removal is tested by two treatments. And, cytotoxicity evolution of DEP degradation intermediates is detected. The relationship between molar ratio ([H2O2]/[DEP] or [TiO2]/[DEP]) and degradation kinetic constant (K) is also studied. And, the cytotoxicity tests of DEP and its degradation intermediates in UV/H2O2 and UV/TiO2 treatments are researched. The DEP removal efficiency of UV/H2O2 treatment is higher than UV/TiO2 treatment. The DEP degradation fitted a pseudo-first-order kinetic pattern under experimental conditions. The K linearly related with molar ratio in UV/H2O2 treatment while nature exponential relationship is observed in the case of UV/TiO2. However, K fitted corresponding trends better in H2O2 treatment than in TiO2 treatment. The Cl(-) is in favor of the DEP degradation in UV/H2O2 treatment; in contrast, it is disadvantageous to the DEP degradation in UV/TiO2 treatment. Other anions are all disadvantageous to the DEP degradation in two treatments. Fe(3+) promotes the degradation rates significantly. And, all other cations in question inhibit the degradation of DEP. HA hinders DEP degradation in two treatments. The intermediates of DEP degradation in UV/TiO2 treatment are less toxic to biological cell than that in UV/H2O2 treatment.

  11. Effects of TiO2 NPs on Silkworm Growth and Feed Efficiency.

    Li, YangYang; Ni, Min; Li, FanChi; Zhang, Hua; Xu, KaiZun; Zhao, XiaoMing; Tian, JiangHai; Hu, JingSheng; Wang, BinBin; Shen, WeiDe; Li, Bing


    Silkworm (Bombyx mori) (B. mori) is an economically important insect and a model species for Lepidoptera. It has been reported that feeding of low concentrations of titanium dioxide nanoparticles (TiO2 NPs) can improve feed efficiency and increase cocoon mass, cocoon shell mass, and the ratio of cocoon shell. However, high concentrations of TiO2 NPs are toxic. In this study, we fed B. mori with different concentrations of TiO2 NPs (5, 10, 20, 40, 80, and 160 mg/L) and investigated B. mori growth, feed efficiency, and cocoon quality. We found that low concentrations of TiO2 NPs (5 and 10 mg/L) were more effective for weight gains, with significant weight gain being obtained at 72 h (P TiO2 NPs at 20 mg/L or higher had certain inhibitory effects, with significant inhibition to B. mori growth being observed at 48 h. The feed efficiency was significantly improved at low concentrations of 5 and 10 mg/L for 14.6 and 13.1 %, respectively (P TiO2 NPs showed increased cocoon mass and cocoon shell mass; at 5 and 10 mg/L TiO2 NPs, cocoon mass was significantly increased by 8.29 and 9.39 %, respectively (P TiO2 NPs promoted B. mori growth and development, improved feed efficiency, and increased cocoon production, while high concentrations (20 mg/L or higher) of TiO2 NPs showed inhibitory effect to the B. mori. Consecutive feeding of high concentrations of TiO2 NPs led to some degrees of adaptability. This study provides a reference for the research on TiO2 NPs toxicity and the basis for the development of TiO2 NPs as a feed additive for B. mori.



    Composite TiO2-montmorillonite (Ti-MMT) has been synthesized with the aim to improve the ability of TiO2 photocatalysts degrade methyl orange. Synthesis of composite made by mixing TiO2 and montmorillonite in ethanol solution, then heated using the furnace at a temperature of 450 °C for 5 hours. TiO2-MMT composites were characterized by FT-IR, XRD and SAA. Test photodegradation activity of TiO2-MMT composites made to dye Methyl Orange 8 mg / L with UV light irradiation time variation and mass...

  13. Hydrophilic property of SiO2-TiO2 overlayer films and TiO2/SiO2 mixing films

    关凯书; 徐宏; 吕宝君


    The photo-induced hydrophilicity of SiO2 overlayer on TiO2 films prepared by sol-gel method was investigated by means of soak angle measurement, XPS, UV-VIS and FTIR spectra. The results show that, compared with the TiO2 film without SiO2 overlayer, when the TiO2 film is thoroughly covered by SiO2 overlayer, the hydrophilicity and the sustained effect are enhanced. It is found that the significant growth of the OH group occurs in the surface of SiO2 overlayer. The different mechanism of enhanced hydrophilicity between SiO2 overlayer on TiO2 films and TiO2/SiO2 mixing films was analyzed. The result suggests that the photo-generated electrons created in the interface between TiO2 and SiO2 tend to reduce the Ti(Ⅳ) cation to the Ti(Ⅲ) state, and the photogenerated holes transmit through the SiO2 layer to uppermost surface efficiently. Once the holes go up to the surface, they tend to make the surface hydrophilic. The stable hydrophilicity of SiO2 overlayer which adsorbs more stable OH groups, enhances the sustained effect, i.e. the super-hydrophilic state can be maintained for a long time in dark place.

  14. Analysis list: Whsc1l1 [Chip-atlas[Archive

    Full Text Available Whsc1l1 Blood + mm9 ...

  15. Effect of L2 phonetic learning on L1 vowels

    Jiang, Haisheng


    This research examines the effect of L2 phonetic learning on L1 vowel production. Mandarin-English bilinguals differing in amount of L1 use produced Mandarin and English vowels. An acoustic analysis showed that both the Mandarin-English bilinguals of high L1 use and those of low L1 use deviated from the norm of Mandarin vowel /i/. The Mandarin-English bilinguals of low L1 use who successfully acquired English vowel /aj/ deviated from the norm of Mandarin vowel /aj/, indicating a carry-over ef...

  16. Preparation of Nd3+-doped ZnO/TiO2 composite catalyst and its photocatalytic activity%Nd3+掺杂ZnO/TiO2催化剂制备及光催化活性

    王丹军; 郭莉; 付锋; 高利锋; 张理平


    以ZnSO4·7H2O和Ti(SO5)2为原料,体积分数40%的乙醇作溶剂,用共沉淀法制备ZnO/TiO2和Nd3+-ZnO/TiO2[n(zn):n(Ti)=3:10]催化剂.采用XRD和UV-Vis等技术进行表征,考察氨水浓度、Nd3+掺杂量和催化剂用量对罗丹明B光催化降解的影响.XRD分析表明,稀土掺杂使催化剂中纳米TiO2晶粒细化;UV-Vis吸收光谱表明,稀土元素掺杂后,催化剂在紫外光吸收有所加强;光催化降解实验表明,氨水浓度较低时,所得催化剂活性较高;掺杂适量Nd3+能有效提高ZnO/TiO2的光催化活性.当催化剂用量1000 mg·L-1、Nd3+掺杂质量分数0.70%和浓氨水稀释10倍时,太阳光连续光照4 h,催化剂的光催化活性较高,废水CODcr去除率达90.1%.

  17. [Mechanism and kinetics of phenol degradation by TiO2 photocatalytic combined technologies].

    Zhang, Yi; Huang, Ruo-Nan; Wang, Xiao-Min; Wang, Qi; Cong, Yan-Qing


    The combination H2O2, or electrical catalytic (EC) system with TiO2 photbcatalytic system for phenol degradation was investigated. The catalytic systems of TiO2/UV, H2O2/UV, TiO2/UV/H2O2 and TiO2/UV/EC were compared to investigate the phenol degradation mechanism and kinetic model. The degradation of phenol in TiO2/UV/H2O2 and TiO2/UV/EC system is more effective than that in TiO2/UV system. With the solution pH of 6, TiO, concentration of 0.2 g.L-1, UV illumination of 2 h, the photocatalysis removal efficiency of phenol reaches to 86%, if the current density of 12 is added, the removal efficiency of phenol could reach to 100%. The energy utilization in different catalytic systems was also compared. When phenol is degraded in 15 min, in TiO2/UV/EC system the energy utilization is the highest of 0.0306 g.(kW. h)-1 with the energy consumption of 0.0640 kW.h-1. It indicates that much more energy is used in TiO2/UV/EC system for phenol degradation. During the analysis of intermediate products in different catalysis systems, the first-order kinetic model of phenol degradation and intermediate products such as hydroquinone, catechol and benzoquinone formation were established. The kinetic model is validated the phenol degradation pathway in different catalysis systems, and also indicates the TiO2/UV/EC system could enhance phenol and intermediate products degradation.

  18. PD-L1 Expression in Lung Cancer

    Yu, Hui; Boyle, Theresa A.; Zhou, Caicun; Rimm, David L.; Hirsch, Fred R.


    Immunotherapies targeted against programmed death ligand 1 (PD-L1) and its receptor (PD-1) have improved survival in a subset of patients with advanced lung cancer. PD-L1 protein expression has emerged as a biomarker that predicts which patients are more likely to respond to immunotherapy. The understanding of PD-L1 as a biomarker is complicated by the history of use of different immunohistochemistry platforms with different PD-L1 antibodies, scoring systems, and positivity cut-offs for immunotherapy clinical trials with different anti-PD-L1 and anti-PD-1 drugs. Herein, we summarize the brief history of PD-L1 as a biomarker and describe the challenges remaining to harmonize PD-L1 detection and interpretation for best patient care. PMID:27117833

  19. Valence electron structure and properties of stabilized ZrO2

    LI JinPing; HAN JieOai; MENG SongHe; ZHANG XingHong


    To reveal the properties of stabilizers in ZrO2 on nanoscopic levels,the valence elec-tron structures of four stable ZrO2 phases and c-ZrO2 were analyzed on the basis of the empirical electron theory of solids and molecules.The results showed that the hybridization levels of Zr atoms in c-ZrO2 doped with Ca and Mg dropped from B17 to B13,the hybridization levels of Zr atoms in c-ZrO2 doped with Y and Ce dropped from B17 to B15,and that the four stabilizing atoms all made the hybridization levels of O atoms drop from level 4 to level 2.The numbers of covalent electrons in the strongest covalent bond in the descending order are c-ZrO2>ZrCeO2>ZrYOZrMgO>ZrCaO.The bond energies of the strongest covalent bond and the melting points of the solid solutions in the descending order are ZrCeO2>c-ZrO2>ZrYO>ZrMgO>ZrCaO.The percent-ages of the total number of covalent electrons in the descending order arec-ZrO2>ZrYO> ZrCeO2>ZrMgO> ZrCaO.From the above analysis,it can be concluded that the stabilizing degrees of the four stabilizers in the descending order are CaO> MgO>Y2O3>CeO2.

  20. The aporphine alkaloid boldine induces adiponectin expression and regulation in 3T3-L1 cells.

    Yu, Bangning; Cook, Carla; Santanam, Nalini


    Adiponectin is an adipokine secreted by differentiated adipocytes. Clinical studies suggest a negative correlation between oxidative stress and adiponectin levels in patients with metabolic syndrome or cardiovascular disease. Natural compounds that can prevent oxidative stress mediated inhibition of adiponectin may be potentially therapeutic. Boldine, an aporphine alkaloid abundant in the medicinal plant Peumus boldus, is a powerful antioxidant. The current study demonstrates the effects of boldine on the expression of adiponectin and its regulators, CCAAT/enhancer binding protein-alpha (C/EBPalpha) and peroxisome proliferator-activated receptor (PPAR)-gamma, in 3T3-L1 cells. Differentiated 3T3-L1 adipocytes were exposed to either hydrogen peroxide (H(2)O(2)) (100 microM) or tumor necrosis factor-alpha (TNFalpha) (1 ng/mL) for 24 hours in the presence or absence of increasing concentrations of boldine (5-100 microM). Quantitative polymerase chain reaction showed that both the oxidants decreased the mRNA levels of adiponectin, PPARgamma, and C/EBPalpha to half of the control levels. Boldine, at all concentrations, counteracted the inhibitory effect of H(2)O(2) or TNFalpha and increased the expression of adiponectin and its regulators. The effect of boldine on adiponectin expression was biphasic, with the lower concentrations (5-25 microM) having a larger inductive effect compared to higher concentrations (50-100 microM). Boldine treatment alone in the absence of H(2)O(2) or TNFalpha was also able to induce adiponectin at the inductive phase of adipogenesis. Peroxisome proliferator response element-luciferase promoter transactivity analysis showed that boldine interacts with the PPAR response element and could potentially modulate PPAR responsive genes. Our results indicate that boldine is able to modulate the expression of adiponectin and its regulators in 3T3-L1 cells and has the potential to be beneficial in obesity-related cardiovascular disease.

  1. Photocatalytic inactivation of Flavobacterium and E. coli in water by a continuous stirred tank reactor (CSTR) fed with suspended/immobilised TiO2 medium.

    Cohen-Yaniv, Vered; Narkis, Nava; Armon, Robert


    A photocatalytic continuous stirred tank reactor (CSTR) was built at laboratory scale to inactivate two environmental bacteria strains (Flavobacterium and E. coli) in tap water. Several parameters were found to impact reactor efficiency. Bacterial initial concentration is an important factor in inactivation rate. After 30 minutes of irradiation at 10(8)-10(9) CFU mL(-1) starting concentration, a >5 log reduction was achieved while at 10(4)-10(6) CFU mL(-1) only a 2 log reduction was observed. Water hardness and pH have an important influence on the photocatalytic inactivation process. Soft water, with low Ca(+2) and Mg(+2) at low pH approximately 5.3 resulted in increased inactivation of Flavobacterium reaching >6 orders of magnitude reduction. E. coli and Flavobacterium at pH 5 were inactivated by 3 logs more as compared to pH 7 under similar conditions. pH below TiO2 isoelectric point (approximately 5.6) supports better contact between bacteria and anatase particles resulting in superior inactivation. TiO2 powder suspension was compared with immobilised powder in sol-gel coated glass beads in order to exclude the need for particles separation from the treated water. TiO2 suspension was more effective by 3 orders of magnitude when compared to coated glass beads. An interesting observation was found between the two bacterial strains based on their hydrophobicity/hydrophilicity balance. The more hydrophobic Flavobacterium compared to E. coli was inactivated photocatalytically by >3 logs more then E. coli in the first 30 minutes of irradiation interval. The results indicate the importance of the parameters involved in the contact between TiO2 particles and microorganisms that govern the successful inactivation rate in CSTR.

  2. The vulnerability of gender on determiners in L1, 2L1 and L2 acquisition

    Elisabeth van der Linden


    Full Text Available The acquisition of gender has been reported to be problematic for some groups of learners acquiring Germanic or Romance languages. It has been shown that L1 learners do better in gender acquisition than others, like bilingual children, child L2 learners and adult L2 learners. The reason for these differences is however not always clear. In this paper, we study the acquisition of gender on determiners by different groups of learners. We concentrate on the acquisition of French, Italian, Spanish and Dutch. The picture from a literature survey shows that contradictory results have been found. We suggest that the ‘vulnerability’ of this particular domain of grammar has to do with interacting factors in the acquisition. Among them are the specific characteristics of the language or languages involved, like the semantic and morphophonological characteristics of the nouns in each language, but also the quantity and quality of input, and the cross-linguistic influence exercised by one language on the other in a 2L1 or L2 setting. Instruction also seems to play a role.

  3. Photocatalytic decomposition of gaseous formaldehyde using TiO2, SiO2−TiO2 and Pt−TiO2

    Byung-Yong Lee; Sung-Wook Kim; Sung-Chul Lee; Hyun-Ho Lee; Suk-Jin Choung


    In this study, in order to improve the photocatalytic decomposition activities of formaldehyde, TiO2 catalyst modified with SiO2 substitution and metal (Pt, Cu and Fe) impregnation, were tested. In case of TiO2 substituted by SiO2, the optimal catalytic activity was found at the mole ration of 2 : 8. Among the metal impregnated TiO2, the Pt impregnated TiO2 showed the best activity even better than that of P-25 which is widely used in commercial application. However, Cu and Fe impregnated TiO...

  4. Ubiquitin C-Terminal Hydrolase L1 in Tumorigenesis

    Jennifer Hurst-Kennedy


    Full Text Available Ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1, aka PGP9.5 is an abundant, neuronal deubiquitinating enzyme that has also been suggested to possess E3 ubiquitin-protein ligase activity and/or stabilize ubiquitin monomers in vivo. Recent evidence implicates dysregulation of UCH-L1 in the pathogenesis and progression of human cancers. Although typically only expressed in neurons, high levels of UCH-L1 have been found in many nonneuronal tumors, including breast, colorectal, and pancreatic carcinomas. UCH-L1 has also been implicated in the regulation of metastasis and cell growth during the progression of nonsmall cell lung carcinoma, colorectal cancer, and lymphoma. Together these studies suggest UCH-L1 has a potent oncogenic role and drives tumor development. Conversely, others have observed promoter methylation-mediated silencing of UCH-L1 in certain tumor subtypes, suggesting a potential tumor suppressor role for UCH-L1. In this paper, we provide an overview of the evidence supporting the involvement of UCH-L1 in tumor development and discuss the potential mechanisms of action of UCH-L1 in oncogenesis.

  5. Effects of H2O2 on Oxygen Supply in the Process of DCA Fermentation

    黄英明; 焦鹏; 李书良; 华玉涛; 曹竹安


    Long chain dicarboxylic acid (DCA) produced by Candida tropicalis is produced in an aerobic viscous fermentation system. The gas-liquid transport resistance can be overcome and the oxygen supply can be increased by adding hydrogen peroxide (H2O2) to the fermentation system. This paper shows that H2O2 can not only enhance the oxygen supply but also change the metabolism by inducing cytochrome P450, the key enzyme of α, ω-oxidation. When C. tropicalis was cultivated in a 3-liter bioreactor using the combination of aeration and hydrogen peroxide feeding, the DCA yield increased about 10% except at the beginning of H2O2 feeding. The experiments showed that the maximum activities of P450 could be induced at 2 mmol*L-1 H2O2. By adding H2O2, the DCA yield in a 22-liter bioreactor was increased 25.3% to 153.9 g/L.

  6. Degradation Mechanisms of Dimethyl Phthalate in the UV-H2O2 System%邻苯二甲酸二甲酯的紫外光-H2O2降解机制研究

    刘青; 陈成; 陈泓哲; 杨绍贵; 何欢; 孙成


    为研究邻苯二甲酸二甲酯(DMP)在紫外光(UV)-H2O2体系下的光降解机制,利用质谱仪鉴定了目标化合物的降解产物,并借此推测其可能的降解途径.结果表明,在UV-H2O2的体系中,10 mg·L-1的DMP在90 min内的降解率达到92.3%,溶液pH值由初始的6.50降至4.98.通过GC/MS、LC/MS分析,DMP在UV-H2O2降解过程中的产物有六类,并且推断出DMP的两条侧链同时发生水解作用,生成的邻苯二甲酸可以异构为更加稳定的对苯二甲酸.此外,DMP还可以发生苯环取代、侧链缩合成环等反应,最后,在·OH的作用下,DMP及其芳香族中间产物发生开环反应,苯环被破坏,生成多种小分子有机酸,并进一步矿化为CO2和水.%To investigate the photodegradation process of dimethyl phthalate (DMP) in the ultraviolet light (UV)-H2O2 system,mass spectrometer was used to identify degradation products and further more,to speculate the possible mechanisms of degradation process.Experimental results showed that the degradation efficiency of 10 mg· L-1 DMP reached 92.3 % in 90minutes in the UV-H2O2 system,and the more H2O2 was added,the faster DMP decomposed.The pH of DMP solution decreased from the initial 6.5 to 4.98,because of the generating of organic phenolic acids and small acid molecules generated by the degradation of DMP.By the GC/MS as well as LC/MS analysis,degradation products of the DMP in the UV-H2O2 system were thought to comprise six categories,from which we could infer that hydrolysis occurs simultaneously on the two side chains of the DMP,generating phthalic acid that can quickly change to the more stable terephthalic acid.In addition,DMP could also occur benzene ring replacement as well as the ring condensed of the side chains.Finally,by the role of · OH,DMP and its aromatic intermediates occurred ring-opening reaction,and benzene ring was destroyed and generated organic acids of small molecular,which was further mineralized to CO2 and water.

  7. Sm doped mesoporous CeO2 nanocrystals: aqueous solution-based surfactant assisted low temperature synthesis, characterization and their improved autocatalytic activity.

    Mandal, Bappaditya; Mondal, Aparna; Ray, Sirsendu Sekhar; Kundu, Amar


    Mesoporous Sm(3+) doped CeO2 (Ce-Sm) with a nanocrystalline framework, a high content of Ce(3+) and surface area (184 m(2) g(-1)), have been synthesized through a facile aqueous solution-based surfactant assisted route by using inorganic precursors and sodium dodecyl sulphate as a template. The XRD results indicate that the calcined Ce-Sm and even the as-prepared material have a cubic fluorite structure of CeO2 with no crystalline impurity phase. XRD studies along with HRTEM results confirmed the formation of mesoporous nanocrystalline CeO2 at a lower temperature as low as 100 °C. A detailed analysis revealed that Sm(3+) doping in CeO2 has increased the lattice volume, surface area, mesopore volume and engineered the surface defects. Higher concentrations of Ce(3+) and oxygen vacancies of Ce-Sm resulted in lowering of the band gap. It is evident from the H2-TPR results that Sm(3+) doping in CeO2 strongly modified the reduction behavior of CeO2 by shifting the bulk reduction at a much lower temperature, indicating increased oxygen mobility in the sample which enables enhanced oxygen diffusion at lower temperatures, thus promoting reducibility, i.e., the process of Ce(4+)→ Ce(3+). UV-visible transmission studies revealed improved autocatalytic performance due to easier Ce(4+)/Ce(3+) recycling in the Sm(3+) doped CeO2 nanoparticles. From the in vitro cytotoxicity of both pure CeO2 and Sm(3+) doped CeO2 calcined at 500 °C in a concentration as high as 100 μg mL(-1) (even after 120 h) on MG-63 cells, no obvious decrease in cell viability is observed, confirming their excellent biocompatibility. The presence of an increased amount of surface hydroxyl groups, mesoporosity, and surface defects have contributed towards an improved autocatalytic activity of mesoporous Ce-Sm, which appear to be a potential candidate for biomedical (antioxidant) applications.

  8. The Facilitating Role of L1 in ESL Classes

    Çağrı Tuğrul Mart


    Full Text Available It has been widely advocated that insistence on English-only policy and the complete prohibition of L1 would maximize the effect of learning L2 but recent studies demonstrate that the appropriate use of L1 has a facilitating role in L2 classroom. This study attempts to demonstrate that the use of L1 in ESL classes does not hinder foreign language learning.

  9. Partial oxidation of methanol catalyzed with Au/TiO2, Au/ZrO2 and Au/ZrO2-TiO2 catalysts

    Hernández-Ramírez, E.; Wang, J. A.; Chen, L. F.; Valenzuela, M. A.; Dalai, A. K.


    Mesoporous TiO2, ZrO2 and ZrO2-TiO2 mixed oxides were synthesized by the sol-gel method and the Au/TiO2, Au/ZrO2 and Au/ZrO2-TiO2 catalysts were prepared by deposition-precipitation method using urea solution as a precipitating agent. These materials were characterized by UV-vis spectroscopy, X-ray diffraction (XRD), N2 adsorption-desorption isotherms, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and in situ FTIR-pyridine (FTIR-Py) adsorption. XRD patterns of the samples confirmed the formation of ZrTiO4 phase in the ZrO2-TiO2 mixed oxides. TEM micrographs showed that nanosized gold particles on the catalyst had an average diameter smaller than 5 nm. Metallic gold (Au0) and oxidized Au species (Aunδ+) on the surface of the catalysts were evidenced by UV-vis and XPS characterization. In the partial oxidation of methanol (POM) reaction, among the six catalysts, the high metallic Au0/Au+ ratio and low surface acidity in the Au/ZrO2 catalysts are chiefly responsible for the highest hydrogen production rate in the whole temperature range between 210 and 300 °C. Methanol decomposition as secondary reaction was favored on TiO2-based catalysts at higher temperature, producing a large amount of CO. Formation of ZrO2-TiO2 solid solution resulted in generation of both Brønsted and Lewis acid sites; as a result, dehydrogenation and oxidative dehydrogenation of methanol was allowed over Au/ZrO2-TiO2 catalysts.

  10. Stress response and tolerance of Zea mays to CeO2 nanoparticles: cross talk among H2O2, heat shock protein, and lipid peroxidation.

    Zhao, Lijuan; Peng, Bo; Hernandez-Viezcas, Jose A; Rico, Cyren; Sun, Youping; Peralta-Videa, Jose R; Tang, Xiaolei; Niu, Genhua; Jin, Lixin; Varela-Ramirez, Armando; Zhang, Jian-ying; Gardea-Torresdey, Jorge L


    The rapid development of nanotechnology will inevitably release nanoparticles (NPs) into the environment with unidentified consequences. In addition, the potential toxicity of CeO(2) NPs to plants and the possible transfer into the food chain are still unknown. Corn plants (Zea mays) were germinated and grown in soil treated with CeO(2) NPs at 400 or 800 mg/kg. Stress-related parameters, such as H(2)O(2), catalase (CAT), and ascorbate peroxidase (APX) activity, heat shock protein 70 (HSP70), lipid peroxidation, cell death, and leaf gas exchange were analyzed at 10, 15, and 20 days post-germination. Confocal laser scanning microscopy was used to image H(2)O(2) distribution in corn leaves. Results showed that the CeO(2) NP treatments increased accumulation of H(2)O(2), up to day 15, in phloem, xylem, bundle sheath cells and epidermal cells of shoots. The CAT and APX activities were also increased in the corn shoot, concomitant with the H(2)O(2) levels. Both 400 and 800 mg/kg CeO(2) NPs triggered the up-regulation of the HSP70 in roots, indicating a systemic stress response. None of the CeO(2) NPs increased the level of thiobarbituric acid reacting substances, indicating that no lipid peroxidation occurred. CeO(2) NPs, at both concentrations, did not induce ion leakage in either roots or shoots, suggesting that membrane integrity was not compromised. Leaf net photosynthetic rate, transpiration, and stomatal conductance were not affected by CeO(2) NPs. Our results suggest that the CAT, APX, and HSP70 might help the plants defend against CeO(2) NP-induced oxidative injury and survive NP exposure.

  11. On L1-convergence of Walsh-Fourier series

    C. W. Onneweer


    Full Text Available Let G denote the dyadic group, which has as its dual group the Walsh(-Paley functions. In this paper we formulate a condition for functions in L1(G which implies that their Walsh-Fourier series converges in L1(G-norm. As a corollary we obtain a Dini-Lipschitz-type theorem for L1(G convergence and we prove that the assumption on the L1(G modulus of continuity in this theorem cannot be weakened. Similar results also hold for functions on the circle group T and their (trigonometric Fourier series.

  12. L1TV Computes the Flat Norm for Boundaries

    Simon P. Morgan


    Full Text Available We show that the recently introduced L1TV functional can be used to explicitly compute the flat norm for codimension one boundaries. Furthermore, using L1TV, we also obtain the flat norm decomposition. Conversely, using the flat norm as the precise generalization of L1TV functional, we obtain a method for denoising nonboundary or higher codimension sets. The flat norm decomposition of differences can made to depend on scale using the flat norm with scale which we define in direct analogy to the L1TV functional. We illustrate the results and implications with examples and figures.

  13. The L1-norm best-fit hyperplane problem.

    Brooks, J P; Dulá, J H


    We formalize an algorithm for solving the L(1)-norm best-fit hyperplane problem derived using first principles and geometric insights about L(1) projection and L(1) regression. The procedure follows from a new proof of global optimality and relies on the solution of a small number of linear programs. The procedure is implemented for validation and testing. This analysis of the L(1)-norm best-fit hyperplane problem makes the procedure accessible to applications in areas such as location theory, computer vision, and multivariate statistics.

  14. Preparation and characterization of Fe2O3-TiO2-MnO2/Al2O3 catalysts%Fe2O3-TiO2-MnO2/Al2O3催化臭氧化催化剂的制备及表征

    张耀辉; 涂勇; 唐敏; 徐军; 刘伟京; 武倩; 陈勇; 李军


    以Al2O3为载体,采用浸渍-焙烧法制备了Fe2O3-TiO2-MnO2/Al2O3催化剂,使用SEM、EDX、BET和XRD方法对其进行了表征.以化工园区污水处理厂二级出水为目标降解物,考察了该催化剂在臭氧催化氧化过程中的催化活性.结果表明,浸渍液中Ti4+、Mn2+、Fe3+的摩尔比为2:2:1、焙烧时间为4h 和焙烧温度为500℃下制备出的催化剂对化工园区废水有较好的催化性能,在臭氧投加量为50mg/L,催化剂填充率为50%的条件下,反应60min后废水COD的去除率达到52.2%.三维荧光谱图显示,废水经臭氧催化氧化后,水中可见腐殖质类和UV腐殖质类物质可完全降解,同时有少量类富里酸生成.%The Fe2O3-TiO2-MnO2/Al2O3 oxide catalyst was prepared by the dipping-calcination method using A12O3 as a carrier. SEM, EDX, BET and XRD techniques were performed to characterize the catalyst. The catalytic activity of the prepared catalyst was investigated by catalytic ozonation of the effluent in sewage plant of chemical industry park at room temperature and atmospheric pressure. The results showed that the optimal preparation parameters were as follow: the molar ratio of Ti4+, Mn2+and Fe3+in the dipping solution was 2:2:1, calcination time and temperature 4h and 500℃ respectively. Furthermore, the degradation performance obtained for COD in wastewater showed that the catalytic activity of Fe2O3-TiO2-MnO2/Al2O3 catalyst was good when amount of ozone was 50mg·L-1 and filling ratio of catalyst was 50%, it could be removed 52.2% of COD after 60min oxidation. Three-dimensional fluorescence spectra showed that visible humus and UV humus in the wastewater were completely degraded after catalytic ozonation, and a small amount of fulvic was generated.

  15. Study on Properties of Composite Oxides TiO2/SiO2

    ZHOUYasong; JIANGGuowei


    The nanometer particles of TiO2 and TiO2/SiO2 oxides were prepared by sol-gel and supercritical fluid drying method.The properties of TiO2 and TiO2/SiO2 were characterized by means of BET(Brunner-Emmett-Teller method), TEM(transmission electron microscopy), SEM(Scanning electron microscopy), XRD(X-ray differaction) and FTIR(Fourier transform-infrared) techniques.The effects of different preparation route,prehydrolysis and non-prehydrolysis,on the properties of TiO2/SiO2 oxide were also examined.Experimental results show that the termal stability of pure TiO2 is improved greatly when it is mixed with SiO2 in nanometer level.The composite TiO2/SiO2 oxides form Ti-O-Si chemical bonds,which creates new Broensted acidity stes.The acidity character is related to TiO2/SiO2 chemical composition and preparation methods.The acidity of TiO2/SiO2 oxides by prehydrolysis is greater than that of by non-prehydrolysis.Ti atom is rich on the surface of TiO2/SiO2.




    Full Text Available Advanced oxidation processes (AOPs are the most attractive methods to degrade diferent organic pollutants. The AOPs have grown extensively because water quality control and regulations have become very strict in many countries. Optimizing the photocatalytic degradation of azo dye (Reactive Red 120 was our goal of research for applying the experimental design methodology. pH (X1, concentration of dye (X2 and TiO2-ZnO-Co nanoparticles volume (X3 in reactions were described mathematically as the function of parameters and were designed by using response surface methodology (RSM. Results were in agreement with empirical values and the sensitivity analysis showed above parameters as the most efficient variables in decolorization efficiency. Analysis of variance (ANOVA revealed highly determination coefficient value (R2 = 0.9996 and adjusted-R2 = 0.999 and satisfactory prediction second-order regression model. The desirable quantities were obtained at the pH = 7, TiO2-ZnO-Co concentration = 0.1 g·L-1, and the initial Reactive Red 120 (RR 120 concentration = 16.4 mg·L-1. Finally, kinetics reaction of degradtion RR 120 was carried in the optimum conditions.

  17. Mineralization of C.I. Acid Red 14 azo dye by UV/Fe-ZSM5/H2O2, process.

    Kasiri, Masoud B; Aleboyeh, Hamid; Aleboyeh, Azam


    The zeolite Fe-ZSM5 was applied as a heterogeneous catalyst in the photo-Fenton process for mineralization of azo dye Acid Red 14 (AR14). Under optimal conditions (20 mM of H2O2 0.25 g L(-1) of catalyst and initial natural pH of the solution) 76% of total organic carbon (TOC) of a solution containing 40 mg L(-1) of the dye could be removed after 120 min in a 1.0 L tubular, closed-circulation batch photoreactor. Leaching tests and comparative experiments indicated that the application of the heterogeneous catalyst could increase the photo-Fenton process efficiency. A kinetic model was developed for this process and showed that the dye mineralization rate obeyed the pseudo-first order kinetic when the initial concentration of the dye was low. It was also observed that the catalytic behaviour of Fe-ZSM5 could be reproduced in consecutive experiments without a considerable drop in the process efficiency. Estimation of electrical energy consumption (EE/O) of the process as a function of mineralization efficiency revealed that the UV/Fe-ZSM5/H2O2 process not only increased the mineralization efficiency of the process, but also decreased the cost of electrical energy consumed by the process.

  18. Post-treatment of refinery wastewater effluent using a combination of AOPs (H2O2 photolysis and catalytic wet peroxide oxidation) for possible water reuse. Comparison of low and medium pressure lamp performance.

    Rueda-Márquez, J J; Levchuk, I; Salcedo, I; Acevedo-Merino, A; Manzano, M A


    The main aim of this work was to study the feasibility of multi-barrier treatment (MBT) consisting of filtration, hydrogen peroxide photolysis (H2O2/UVC) and catalytic wet peroxide oxidation (CWPO) for post-treatment of petroleum refinery effluent. Also the possibility of water reuse or safe discharge was considered. The performance of MBT using medium (MP) and low (LP) pressure lamps was compared as well as operation and maintenance (O&M) cost. Decomposition of organic compounds was followed by means of gas chromatography-mass spectrometry (GC-MS), total organic carbon (TOC) and chemical oxygen demand (COD) analysis. After filtration step (25 μm) turbidity and concentration of suspended solids decreased by 92% and 80%, respectively. During H2O2/UVC process with LP lamp at optimal conditions (H2O2:TOC ratio 8 and UVC dose received by water 5.28 WUVC s cm(-2)) removal of phenolic compounds, TOC and COD was 100%, 52.3% and 84.3%, respectively. Complete elimination of phenolic compounds, 47.6% of TOC and 91% of COD was achieved during H2O2/UVC process with MP lamp at optimal conditions (H2O2:TOC ratio 5, UVC dose received by water 6.57 WUVC s cm(-2)). In order to compare performance of H2O2/UVC treatment with different experimental set up, the UVC dose required for removal of mg L(-1) of COD was suggested as a parameter and successfully applied. The hydrophilicity of H2O2/UVC effluent significantly increased which in turn enhanced the oxidation of organic compounds during CWPO step. After H2O2/UVC treatment with LP and MP lamps residual H2O2 concentration was 160 mg L(-1) and 96.5 mg L(-1), respectively. Remaining H2O2 was fully consumed during subsequent CWPO step (6 and 3.5 min of contact time for LP and MP, respectively). Total TOC and COD removal after MBT was 94.7% and 92.2% (using LP lamp) and 89.6% and 95%, (using MP lamp), respectively. The O&M cost for MBT with LP lamp was estimated to be 0.44 € m(-3) while with MP lamp it was nearly five

  19. 氧化苦参碱对H2O2诱导L02细胞损伤的抑制作用及其机制的研究%Protective effects of oxymatrine against H2O2-induced damage in L02 cells

    韩延忠; 周永峰; 桑秀秀; 刘慧敏; 崔鹤蓉; 孟雅坤; 李光全; 贺兰芝; 尹萍


    该文研究氧化苦参碱(oxymatrine,OMT)抑制H2O2诱导的L02细胞损伤的作用及其机制.以人正常肝实质细胞L02为研究对象,采用H2O2诱导氧化应激建立肝损伤模型进行实验,通过CCK-8检测OMT对L02细胞活性的影响;CSFE荧光实验检测OMT对L02细胞增殖的影响;流式细胞术检测OMT对H2O2诱导的L02细胞凋亡率的影响;DCFH-DA荧光探针检测OMT对H2O2诱导的L02细胞内ROS含量;微板比色法检测OMT对GSH-PX和SOD活性的影响.结果显示,OMT在6.25~100 mg·L-1通过诱导NADPH的产生,增强L02细胞内GSH-PX酶和SOD酶的活性,进而促进GSH介导的活性氧ROS的清除,从而抑制H2O2诱导的L02细胞凋亡的发生,达到抑制H2O2诱导L02细胞损伤的作用.

  20. Synthesis of Hydroxide-TiO2 Compounds with Photocatalytic Activity for Degradation of Phenol

    Contreras-Ruiz, J. C.; Martínez-Gallegos, S.; Ordoñez, E.; González-Juárez, J. C.; García-Rivas, J. L.


    Photocatalytic degradation of phenol using titanium dioxide (TiO2), either alone or in combination with other materials, has been tested. Mg/Al hydrotalcites prepared by two methods using inorganic (HC) or organic (HS) chemical reagents, along with mixed oxides produced by calcination of these products (HCC and HSC), were mixed with titanium isopropoxide to obtain hydroxide-TiO2 compounds (HCC-TiO2 and HSC-TiO2) and their photocatalytic activity tested in solutions of 10 mg/L phenol at 120 min under illumination at λ UV = 254 nm with power of 4 W or 8 W. The obtained materials were characterized by various techniques, revealing that TiO2 was incorporated into the mixed oxides of the calcined hydrotalcite to form the above-mentioned compounds. The photocatalytic test results indicate that the activity of HCC-TiO2 can be attributed to increased phenol adsorption by hydrotalcite for transfer to the active photocatalytic phase of the impregnated TiO2 particles, while the better results obtained for HSC-TiO2 are due to greater catalyst impregnation on the surface of the calcined hydrotalcite, reducing the screening phenomenon and achieving HSC-TiO2 degradation of up to 21.0% at 8 W. Reuse of both compounds indicated tight combination of HCC or HSC with TiO2, since in four successive separation cycles there was little reduction of activity, being associated primarily with material loss during recovery.