Synergetic catalysis of ceria and titania for selective reduction of NO

The promotional effect of the interaction between titania and ceria on the catalytic performance for selective reduction of NO was studied.The catalysts,CeO 2,TiO 2,CeO 2 /TiO 2 and Ti x Ce 1-x O 2,were synthesized and tested in NH 3-Selective catalytic reduction(SCR) of NO,and the samples were characterized by the Brunaller,Emmett and Teller(BET absorbed gas N 2),X-ray diffraction(XRD),high resolution transmission electron microscopy(HR-TEM),and temperature programmed desorption(TPD NH 3) techniques.The improvement mechanism of the interaction between the titania and ceria had been explored and discussed from two aspects of micro-structure and surface acidity.The interaction between the titania and ceria greatly improved the catalytic activity but had little effect on the active temperature.It was first reported that the acid amount determined the catalytic activity and the acid strength determined the active temperature for NH 3-SCR of NO.     

Magnetic properties and magnetic exchange interactions in Gd_(1–x)RE_x(RE=Pr,Nd) alloys

The effect of Pr,Nd addition on the magnetic properties and magnetic exchange interaction of gadolinium alloys was systematically studied.Curie temperature T_C and magnetic moment of Gd_(1–x)RE_x(RE=Pr,Nd)systems with x0.05 were investigated.When x0.05,Pr and Nd formed respectively with Gd continuous solid solution which has the crystalline structure HCP.Study on the magnetic behavior indicated that at near room temperature,the simple ferromagnetism prevailed in these two systems of alloy.The Curie temperature and magnetic moment of Gd_(1–x)RE_x alloy decreased with RE(RE= Pr,Nd)content x increasing.The de Gennes factor of Gd_(1–x)RE_x alloy which was associated with the exchange interaction between magnetic spin components also decreased with RE content increasing.The above results showed that the magnetic exchange interaction between magnetic atoms in gadolinium could be effectively changed by the Pr,Nd addition.     

Enrichment of lanthanides in aragonite

Using the constant addition technique,the coprecipitation of lanthanum,gadolinium,and lutetium with aragonite in seawater was experimentally investigated at 25 ℃.Their concentrations in aragonite overgrowths were determined by inductive coupled plasma mass spectrometer.All these lanthanides were strongly enriched in aragonite overgrowths.The amount of lanthanum,gadolinium,and lutetium incorporated into aragonite accounted for 57%-99%,50%-89%,and 40%-91% of their initial total amount,respectively.With the in...     

Corrosion of Refractory Alumina-Graphite and Alumina-Graphite-Zirconia in Slag Containing Titania

The corrosion of refractory alumina-graphite and alumina-graphite-zirconia in the slag containing titania was studied by immersion tests (quasi-static and dynamic tests). Combining direct observation with microscopic investigations, a mechanism for corrosion was proposed based on the oxidation of graphite and the dissolution of refractory components. During the corrosion process, there are some special phenomena and laws that can be explained by the relation between the corrosion rate and the TiO2 mass percent, the rotational refractory velocity and the morphology of the deteriorated layer.     

Increase in efficiency of dye-sensitized solar cells by porous TiO2 layer modification with gadolinium-containing thin layer

Modified with gadolinium-containing layer, nanoporous titania electrode and its application in dye-sensitized solar cells were reported. The electrode prepared was characterized with UV-Vis and X-ray diffraction (XRD) techniques. The amount of gadolinium was measured with inductively coupled plasma-optical emission spectrometry (ICP-OES) experiments. The modified electrode showed reduced N3 dye adsorption ability, but increased light conversion efficiency in comparison with the non-modified electrode. The overall conversion efficiencies, determined under 400 W/m2 irradiation with tungsten-halogen lamp at room temperature, were 0.55% for non-modified and 0.74% for modified electrodes.     

Dopamine-containing gadolinium complex as magnetic resonance imaging contrast agent

Gadolinium diethylenetriamine-pentaacetic bisdopamide (Gd-DTPA-2DA) was synthesized by the incorporation of dopamine to diethylenetriaminepentaacetic acid (DTPA) and further reaction with gadolinium chloride. In vitro and in vivo properties were also evaluated. Gadolinium complex Gd-DTPA-2DA possessed higher relaxation effectiveness and less cytotoxicity to HeLa cells than that of Gd-DTPA. Moreover, Gd-DTPA-2DA greatly enhanced the contrast of MR images of the brains, provided prolonged intravascular duration, and produced highly contrasted visualization of the brain.     

Impurities especially titanium in the rare earth metal gadolinium— before and after solid state electrotransport

Gadolinium was prepared by conventional procedures of fluorination, reduction, distillation and solid state electrotransport（SSE）. The electronegativities of the metals were found to have an important influence on the electrotransport process and result of the impurity element. Meanwhile, titanium particles in the distilled gadolinium as major metallic impurities were studied by high resolution transmission electron microscopy（HRTEM） before and after solid state electrotransport. The results showed that impurities especially titanium transported from anode to cathode during SSE. In the metal before SSE, there were impurities of titanium in strip shape or embedded round shape. After SSE processing, titanium particles in the metal smaller than 50 nm in the cathode, but existed 6 to 10 times bigger in the anode.     

Single step low temperature synthesis of gadolinium gallium garnet nanopowders

Solution combustion synthesis of single-phase gadolinium gallium oxide(Gd3Ga5O12,GGG)nanopowders,by a fuel mixture approach using urea and glycine at a low temperature of 500oC,was being reported for the first time.Based on the fact that urea and glycine are good fuels for gallium oxide and gadolinium oxide synthesis,the fuel mixture composition was obtained,which could lead to direct phase pure cubic Gd3Ga5O12 formation without any subsequent calcination step.Combustion was carried out in furnace pre-heated at 500oC.Thermogravimetric analysis(TGA)of combustion product showed negligible mass loss indicating direct formation of GGG powder.Fourier transform infrared(FTIR)spectrum of combusted product showed peak characteristic of GGG in case of mixed fuel.X-ray diffraction(XRD)confirmed formation of phase pure GGG at 500°C in preheated furnace.Very fine,well dispersed nanometric particles of size range of 50-100 nm were obtained,being uniform and close to spherical morphology as observed by transmission electron microscope(TEM).     

Preparation,luminescence and photofunctional performances of a hybrid layered gadolinium-europium hydroxide

The design and fabrication of rare earth ions incorporated into the inorganic/organic hybrid materials have attracted growing attention for seeking improved optical properties and photofunctional performances.In this paper,a novel hybrid composite based on the layered rare earth hydroxides was successfully prepared by the ion-exchange and intercalation chemical process.The rare earth elements in the composite contain gadolinium(Gd) and europium(Eu) and the molar ratio of Gd to Eu is kept constan...     

EFFECT OF STRUCTURE OF FUNCTIONAL POLYMER ACTIVE MATERIALS ON PROPERTIES OF GADOLINIUM ION SELECTIVE ELECTRODE

In this paper,the functional polymeric active materials were prepared by the grafting copolymerizationand their structure and properties were studied.The results show that the structure and properties of these ac-tive materials have the relative large effects on the properties of gadolinium ion selective electrodes.     

Effect of Preparation Process of Functional Polymer Active Materials on Properties of Gadolinium Ion Selective Electrode

Recently we have studied the rare earth ion-selective electrodes with active materials of the func-tional polymers and found that the process chosen for the functional polymers had an effect on the propertiesof gadolinium ion selective electrode besides the effects of their structures.1.Effect of preparation process of the grafted polymers on the properties ofgadolinium ion selective electrodesThe electrode membranes which consist of functional polymers as active materials were prepared by re-action of gadolinium chloride with the radiation grafted clmer of acrlic acid and polystyrene of which     

Study of erbium (Ⅲ) doped titanium dioxide nanoparticles by photoacoustic spectroscopy

Nanocrystalline titania as photocatalyst has attracted considerable attention for its potential use in environmental cleaning.Recently,lanthanide ions doped titania samples have been shown to increase the photocatalytic efficiency of selected reactions.In this work,TiO2 nanoparticles doped with Er3+ were prepared via an ultrasonic assisted sol-gel method.The optical properties of the samples were determined by photoacoustic(PA) spectroscopy.It was found that the absorption edge shifted to lower wavelength w...     

Separation of Iron Droplets From Titania Bearing Slag

Owing to smelting vanadium-titanium magnetite ore,the amount of iron entrainment in slag as droplets is far higher than that in conventional BF slag.However,the iron droplets can be easily settled by blowing air into the molten slag.The results show that more than 80% of iron droplets in titania bearing slag can be settled and separated after treatment.The temperature rise of molten slag during the oxidizing process and the decreased viscosity caused by the component change of slag as well as air stirring in slag both accelerate the iron droplets settling.The vanadium content in the settled iron droplets and the original iron droplets was obtained by chemical analysis.The possible reason for the increased vanadium in the settled iron droplets was discussed by thermodynamic principles.     

Local atomic structure evolution of liquid gadolinium and yttrium during solidification:An ab initio study

Local atomic structure evolution of pure gadolinium(Gd) and yttrium(Y) during solidification was investigated by using ab initio molecular dynamics(AIMD) simulation.The calculated results indicate that the local short-range order(SRO) in liquid Gd and Y is similar to some transitional metals with an asymmetric shape of the second peak in static structure factors.Moreover,the formation of icosahedral local motifs as a function of temperature decreases the diffusivity,which explains the connection...     

Development of a microfluidic-chip system based on parallel flow for intensified Gd(Ⅲ) extraction from nitrate media using cationic extractant

Microfluidic solvent extraction(micro SX) of gadolinium was conducted using a mono-and di-ester mixture(MDEHPA) as the cationic extractant. A microfluidic Y-Y channel was fabricated using CO_2-laser technique in a glass microchip used as the extraction system. Compared with batch extraction,extraction kinetic is found fast, and extraction equilibrium is attained within 15 s. Stoichiometry of the extracted complex is found to be Gd(NO_3)_3·3MDEHPA using log—log plot method. Additionally,the operating parameters and overall volumetric mass transfer coefficient(k_Lα) were investigated to determine the mass transfer performance. Optimal condition of microextraction for gadolinium using response surface methodology was determined(feed solutions 31 mg/L adjusted to pH value 2.5,extractant concentration 2.9 vol% and extraction time 13.5 s). In optimal condition, gadolinium extraction yield is obtained 95.5%. Findings of this study approve simplicity, portability, effectiveness, swiftness, and environmental friendliness microfluidic solvent extraction process and reveal that micro SX is useful in the field of extraction strategic metals present at low concentrations, which are otherwise not technically amenable or economically feasible to extract using current traditional methods.     

Electrochemical properties of gadolinium on liquid gallium electrode in LiClKCl eutectic

This work presents the electrochemical properties of gadolinium(Gd), a significant rare earth element in spent nuclear fuel(SNF), in the LiCl-KCl eutectic. To explore thermodynamic properties of Gd at the liquid gallium(Ga) electrode, experiments were performed both on the inert tungsten(W) and liquid gallium(Ga) electrode at different temperatures in a range from 723 to 823 K, which show that the Gd metal can be oxidized to Gd(Ⅲ) by exchanging of 3 electrons. Electrochemical techniques including cyclic voltammetry(CV), open circuit potential(OCP), potentiostatic electrolysis and galvanostatic electrolysis were utilized to detect the electrochemical behavior and evaluate standard apparent potential of the Gd(Ⅲ)/Gd couple,and E_(Gd(Ⅲ)/Gd)~*=-3.456 + 6.2×10~(-4)T(±0.046)( vs Cl_2/Cl~-) is obtained.In addition, electromotive force(EMF) and coulometric titration were employed to calculate the activity and activity coefficient of Gd in metal Ga. After calculation, the activity is 1.791×10~(-15) at 723 K and function of activity coefficient and temperature is lgγ = 3.485-10927/T(±0.0875).     

Preparation of high performance YGdBCO films by low fluorine TFA-MOD process

YBCO films doped with different contents of gadolinium(Gd) were prepared by the low-fluorine(low-F)trifluoroacetate metal-organic deposition(MOD) method.The effects of flow rate and holding time of the firing(crystallization) stage on the superconducting properties of Y_xGd_(1-x)Ba_2 Cu_3 O_(7-δ)(YGdBCO) films were investigated.The phase formation and texture were characterized by the X-ray diffraction(XRD),which indicate that severe degradation of the microstructure will be induced with the inappropriate flow rate.The surface morphology and element distribution were investigated by the scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS).The results show that increasing the holding time of the firing stage is effective for the further decomposition of residual impurity phase on the surface.The mechanisms of the phase and surface evolution are also discussed.Finally,a high critical current density(J_c) value of 5.4 MA/cm~2 was achieved in the Y_(0.9)Gd_(0.1)BCO film fabricated by the cooperative control of the flow rate and holding time of the firing stage,which are contributed to the formation of excellent texture,homogeneous microstructure and dense surface of the YGdBCO films.     

Self-polymerization and co-polymerization kinetics of gadolinium methacrylate

Gadolinium methacrylate(Gd(MAA)_3) was synthesized by using gadolinium oxide and methacrylic acid as the starting materials and its self-polymerization kinetic was studied based on non-isothermal and isothermal analysis. Moreover, the monomer reactivity ratios of methyl methacrylate(MMA) and Gd(MAA)_3 were evaluated by using Kelen-Tiidos method. The thermal neutron shielding properties of PMMA and poly(MMA-co-Gd(MAA)3) were calculated by MCNP program. The results show that the selfpolymerization of Gd(MAA)3 can be initiated by thermal and free radical and its activation energy is103.35 kJ/mol or 58.55 kJ/mol correspondingly in the solid state or aqueous solution. The polymerization rate,R_p,under low conversion at 65 ℃ is expressed as R_p = K[M]~(1.05)[I]~(0.60). The reactivity ratios of r_1(MMA) and r_2(Gd(MAA)_3) are 0.225 and 1.340, respectively. The ability of thermal neutron shielding of poly(MMA-co-Gd(MAA)_3) is increased by gadolinium contents and is far better than PMMA.     

Orientation gradient on surface of non-oriented electrical steel annealed by γ → α transformation

The microstructures and textures of the non-oriented electrical steel sheets under various annealing conditions were investigated.The orientation gradient in the interior of grains appeared on the surface of steel sheets after α→γ→α transformation in various atmospheres.The orientation gradient that appeared on the surface was inherited into the center of the steel sheet in H2 atmosphere,while that appeared only in the grains of the surface layer during γ→α transformation with N2 atmosphere.The thin oxide scale was generated in various atmospheres containing traces of O2 and H2O.The formation mechanism of orientation gradient is related to the thermal stress caused by the difference of thermal expansion coefficients between the oxide scale and the thin ferrite on the surface.The combined effect of phase transformation stress and thermal stress caused the plastic deformation of the thin ferrite grains on the surface in the initial stage of γ→α transformation,and then the orientations of the thin ferrite grains gradually rotated and caused the orientation gradient in the interior of grains.     

Optimal Design of Bobbinless Rotary Magnetorheological Material Based Brake

The paper presents a novel configuration in order to improve the compactness and manufacturing cost of magneto-rheological material(or fluid)based brakes(MRB in short).In conventional configurations of MRBs,the coil is normally wound on a nonmagnetic bobbin which is placed on the housing.This causes difficulties in manufacturing of the brake and the bottle-neck problem of magnetic circuit.In the proposed configuration,the coil is wound directly on the inner cylinder of the housing.In this case,the inner cylinder of the housing should be designed in a special shape that maximizes the magnetic flux across the MR fluid(MRF)duct.After proposing of the new configuration of the MRBs,the modeling of the MRBs is performed based on Bingham rheological model of the MRF.An optimal design of the proposed MRBs and conventional MRBs is then performed based on finite element analysis results of magnetic circuit of the MRBs.A comparative work between the optimal parameters of the proposed MRBs and conventional MRBs is conducted and the advanced performance characteristics of the proposed MRBs are investigated.