Sample records for relative o2 pulse

  1. Developmental patterns of O2 consumption, heart rate and O2 pulse in unturned eggs.

    Pearson, J T; Haque, M A; Hou, P C; Tazawa, H


    The effects of failure to turn eggs on the developmental patterns of oxygen consumption (MO2), heart rate (fH) and O2 pulse during the second half of incubation of individual chicken eggs were examined. The MO2 of unturned eggs increased at a significantly lower rate than the control toward the end of prenatal incubation, and the plateau MO2 between day 17 and 19 was significantly lower than the control. Lack of turning also resulted in significant changes in the developmental patterns of fH and O2 pulse. It is suggested that the effects of lack of egg-turning on the developmental patterns of MO2 may be attributable to lower embryonic growth rate in addition to impairment of gas exchange through the chorioallantoic gas exchanger.

  2. 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.

  3. ZrO2 and ZrO2-Y2O3 coatings deposited by double pulsed plasma arc


    A novel surface technique has been developed to produce ZrO2 and ZrO2-Y2O3 coatings on the surface of alloys by using double pulsed plasma arc to react with a solution film containing nano-oxide particles. These coatings exhibit smooth surface and excellent adhesion with substrate. The morphologies of the ceramic coatings and phases were analyzed. It was shown that the oxidation resistance of l8-8 stainless steel was markedly improved by applying ZrO2 and ZrO2-Y2O3 coatings.

  4. 11. Bactericidal Activity of Photocatalytic TiO2 Excited by Low Intensity Pulsed Ultrasound (LIPUS): An In Vitro Study.

    Noguchi, Chieko; Koseki, Hironobu


    Photocatalysis with anatase-type titanium dioxide (TiO2) under ultraviolet has a well-recognized bactericidal effect. The purpose of the present study was to evaluate the photocatalytic bactericidal effects of TiO2 on Staphylococcus epidermidis (ATCC35984) caused by Low Intensity Pulsed Ultrasound (LIPUS) associated with bio-implant-related infections. The photocatalytic properties of the TiO2 films were confirmed by the degradation of an aqueous solution of methylene blue. The disks were seeded with cultured Staphylococcus epidermidis and irradiated by LIPUS. The bactericidal effect of the TiO2 films was evaluated by counting the surviving colonies. The viability of the bacteria on the photocatalytic TiO2 film coated titanium was suppressed significantly to 63% after 2 hours of LIPUS treatment (P TiO2 under LIPUS is useful for sterilizing the contaminated and infected surfaces of metal bio-implants.

  5. Low temperature synthesis of hierarchical TiO2 nanostructures for high performance perovskite solar cells by pulsed laser deposition.

    Yang, Bin; Mahjouri-Samani, Masoud; Rouleau, Christopher M; Geohegan, David B; Xiao, Kai


    A promising way to advance perovskite solar cells is to improve the quality of the electron transport material -e.g., titanium dioxide (TiO2) - in a direction that increases electron transport and extraction. Although dense TiO2 films are easily grown in solution, efficient electron extraction suffers due to a lack of interfacial contact area with the perovskites. Conversely, mesoporous films do offer high surface-area-to-volume ratios, thereby promoting efficient electron extraction, but their morphology is relatively difficult to control via conventional solution synthesis methods. Here, a pulsed laser deposition method was used to assemble TiO2 nanoparticles into TiO2 hierarchical architectures exhibiting an anatase crystal structure, and prototype solar cells employing these structures yielded power conversion efficiencies of ∼14%. Our approach demonstrates a way to grow high aspect-ratio TiO2 nanostructures for improved interfacial contact between TiO2 and perovskite materials, leading to high electron-hole pair separation and electron extraction efficiencies for superior photovoltaic performance. Compared to previous pulsed laser deposition-synthesized TiO2 mesoporous crystalline networks that needed post-thermal annealing at 500 °C to form mesoporous crystalline networks, our relatively low temperature (300 °C) TiO2 processing method may promote reduced energy-consumption during device fabrication, as well as enable compatibility with flexible polymer substrates such as polyimide.

  6. Synergistic Decolouration of Azo Dye by Pulsed Streamer Discharge Immobilized TiO2 Photocatalysis

    LI Jie; WANG Huijuan; LI Guofeng; WU Yan; QUAN Xie; LIU Zhigang


    Photocatalyst was prepared by immobilizing TiO2 on glass beads using the traditional sol-gel method.Ultraviolet light(UV)produced by pulsed streamer discharge Was then used to induce photocatalytic activity of TiO2 photocatalyst.Decolouration efficiency of the representative azo dye(acid orange 7,AO7)was investigated using the synergistic system of pulsed streamer discharge plasma and TiO2 photocatalysis.The obtained results showed that the decolouration rate of AO7 could be increased by 16.7% under the condition of adding supported TiO2 in the pulsed streamer discharge system,compared to that in the sole pulsed streamer discharge plasma system,due to the synergistic effect of pulsed streamer discharge and TiO2 photocatalysis induced by pulsed streamer discharge.The synergistic system of pulsed streamer discharge and TiO2 photocatalyst Was found to have more reactive radicals for degradation of organic compounds in Water.

  7. Pulsed electric field assisted sol-gel preparation of TiO2 nanoparticles

    Mani, Rajaboopathi; Han, Bing; Louhi-Kultanen, Marjatta


    This work studies the effect of a pulsed electric field (PEF) on the precipitation and properties of TiO2 nanoparticles. TiO2 nanoparticles were prepared using pulsed DC electric field assisted sol-gel method. The duration of the PEF treatment was varied to investigate its effect on the particle size of TiO2 nanoparticles. The nanoparticles were characterized by X-ray powder diffraction (XRD), Raman spectroscopy, UV diffuse reflectance spectroscopy (UV-DRS) and transmission electron microscopy (TEM). It was found that TiO2 particles prepared with pulsed electric field assisted sol-gel method had enhanced average crystallite size due to the effect of the pulsed electric field on primary nucleation. The effect of electric field on nanoparticle preparation is interesting which can be used to control the grain and crystallite size of nanoparticle.

  8. Annealing of SnO2 thin films by ultra-short laser pulses

    Scorticati, D.; Illiberi, A.; Bor, Teunis Cornelis; Eijt, S.W.H.; Schut, H.; Römer, Gerardus Richardus, Bernardus, Engelina; de Lange, D.F.; Huis in 't Veld, Bert


    Post-deposition annealing by ultra-short laser pulses can modify the optical properties of SnO2 thin films by means of thermal processing. Industrial grade SnO2 films exhibited improved optical properties after picosecond laser irradiation, at the expense of a slightly increased sheet resistance

  9. Annealing of SnO2 thin films by ultra-short laser pulses

    Scorticati, D.; Illiberi, A.; Bor, T.; Eijt, S.W.H.; Schut, H.; Römer, G.R.B.E.; Lange, D.F. de; Huis In't Veld, A.J.


    Post-deposition annealing by ultra-short laser pulses can modify the optical properties of SnO2 thin films by means of thermal processing. Industrial grade SnO2 films exhibited improved optical properties after picosecond laser irradiation, at the expense of a slightly increased sheet resistance [Pr

  10. Laminated CeO2/HfO2 High-K Gate Dielectrics Grown by Pulsed Laser Deposition in Reducing Ambient

    Karakaya, K.; Barcones, B.; Zinine, A.; Rittersma, Z.M.; Graat, P.; Berkum, van J.G.M.; Verheijen, M.A.; Rijnders, G.; Blank, D.H.A.


    CeO2 and HfO2 dielectric layers were deposited in an Ar+(5%)H2 gas mixture by Pulsed Laser Deposition (PLD) on Si (100). A CeO2-Ce2O3 transformation is achieved by deposition in reducing ambient. It is also shown that in-situ post deposition anneal efficiently oxidizes Ce2O3 layers to CeO2. The prop

  11. In situ spectroelectrochemical behaviour of nanocrystalline TiO2 thin films electrode fabricated by pulsed laser deposition

    傅正文; 孔继烈; 秦启宗; 田中群


    Nanocrystalline titanium oxide thin films have been successfully deposited on ITO coated glass by pulsed laser ablation of metallic Ti target in O3/O2 ambient gases. The intercalation of Li ions in the anatase TiO2 film electrode is examined by cyclic vohammetry. The electrochromic behaviour of TiO2 electrode is investigated by in-situ visible transmittance measurement, and two absorption bands at 420 and 650 nm are observed. The absorption falling and rising in color changing with excellent revisibility is relative to the insertion and deintercalation processes of Li ion. These resuits suggest that nanocrystalline titanium oxide films fabricated by pulsed laser deposition exhibit excellent spectroelectrochemical property.

  12. The role of high Rydberg states in enhanced O- formation in a pulsed O2 discharge

    Ding, W. X.; Pinnaduwage, L. A.; Tav, C.; McCorkle, D. L.


    Formation of O- ions in a pulsed discharge of O2 was investigated in a Langmuir-probe-assisted photodetachment experiment. A large enhancement of negative ion formation was observed in the afterglow. Experimental results are consistent with O- formation via electron attachment to high Rydberg states of O2 that survive into the afterglow. Such excited states can be produced by high-energy electron impact during the discharge. The lifetime of high-Rydberg molecules is estimated to be longer than 10 microseconds. The efficient production of O- ion by electron attachment to high-Rydberg O2 molecules was further confirmed in a laser excitation experiment. The O- ions and O atoms produced via enhanced dissociative electron attachment to excited states of O2 may be important for the chemical processes that occur in pulsed plasma remediation of contaminated air.

  13. Pulse Electrodeposition and Nanoindentation Test of ZrO2/Ni Nanocomposite


    ZrO2/Ni nanocomposite was produced via pulse electrodeposition using a nickel sulfmate bath. The effects of main factors including pH value, temperature T, current density Dk and ZrO2 content p on the electrodeposit were dealt with by the Taguchi method. Experimental results show that the current density and ZrO2 content affect the electrodepositing process significantly. Nanocomposite with an average grain size of about 50 nm and ZrO2 content of up to 0.4 wt% was produced under the optimal condition. The Young's modulus of the achieved composite is similar to that of polycrystalline Ni. The microhardness is much higher than that of common pure Ni, primarily due to the ultrafine grains of Ni matrix by the Hall-Petch mechanism. The homogeneous dispersion of stiff ZrO2 particles in the Ni matrix acting as dislocation pinning and microcrack pinning also results in the strengthening effect.

  14. Characterization and Electrical Properties of TiO2 Thin Films Deposited by Pulsed Laser Deposition

    Badar, Nurhanna; Kamarulzaman, Norlida


    Thin film technology is very important in today's high-tech industry. TiO2 is a high-k dielectric material. Problems with thin film deposition arise when the thickness of the thin layers approaches a few hundred nm to less than 100 nm. High quality thin films within these dimensions are difficult to obtain. Issues of adhesion, crystal mismatch, crystal orientation, surface roughness, densification, etc. are problems that need to be addressed if good quality thin films for devices are to be fabricated. These factors have a relation with the thin film technique used. As an example, spin coating technique may be a cheaper technique but may not result in dense and very smooth surfaces. Pulsed LASER deposition (PLD) is a relatively newer method used in thin film fabrication. The advantages of PLD are, capability of very thin films being deposited on different types of substrates (up to monolayers), control of crystal orientation, capability of depositing materials with complex stoichiometry and ease of methodology with high throughput. This has industrial implications as a good method for thin film preparation. This work involves the deposition of TiO2 thin films using different deposition parameters and chamber environments.

  15. THz pulse generation using a contact grating device composed of TiO2/SiO2 thin films on LiNbO3 crystal

    Yoshida, Fumiko; Nagashima, Keisuke; Tsubouchi, Masaaki; Maruyama, Momoko; Ochi, Yoshihiro


    We developed a new contact grating device for terahertz (THz) pulse generation by optical rectification. The device was made from polycrystalline rutile TiO2 thin film in the grating region and an amorphous SiO2 layer deposited on a Mg-doped LiNbO3 crystal. Our calculations indicated that the TiO2 grating on the SiO2 layer would yield an increase in diffraction efficiency of up to 0.69. The prepared TiO2 thin film had a sufficient laser induced damage threshold (140 GW/cm2) to enable effective THz pulse generation. Using a prototype device, we demonstrated THz pulse generation and investigated the phase-matching conditions experimentally.

  16. Experimental research of pulsed discharge plasma and TiO2/Zeolite coupling technology for formaldehyde removal

    Dong, Bingyan; Lan, Shuirong


    The pulsed discharge plasma combining with catalyst to remove formaldehyde is a novel type of advanced oxidation technology. In the present work, taking wire-tube pulsed discharge plasma and TiO2/Zeolite coupling technology for formaldehyde removal. The studies have investigated the wire-tube reactor with zeolite, TiO2, TiO2/Zeolite for formaldehyde removal respectively. Results show that in the optimal experimental conditions and the baking time is 120 min, the baking temperature is 450 °C, that TiO2/Zeolite catalyst which made by sol-gel shows higher photocatalytic activity and efficiency. The pulsed discharge with TiO2/Zeolite catalyst for formaldehyde removal has higher removal efficiency than pulsed discharge with zeolite or TiO2. Therefore, pulsed discharge plasma with TiO2/Zeolite for the removal of formaldehyde can greatly increase the removal efficiency.

  17. Raman study of TiO2 coatings modified by UV pulsed laser

    Belka, Radosław; Keczkowska, Justyna; Sek, Piotr


    The TiO2 coatings were prepared by simple sol-gel method and modified by UV pulsed laser. TiO2, also know as titania, is a ceramic compound, existing in numerous polymorphic forms, mainly as tetragonal rutile and anatase, and rhomboidal brookite. Rutile is the most stable form of titanium dioxide, whereas anatase is a metastable form, created in lower temperatures than rutile. Anatase is marked with higher specific surface area, porosity and a higher number of surface hydroxyl groups as compared to rutile. The unique optical and electronic properties of TiO2 results in its use as semiconductors dielectric mirrors, sunscreen and UV-blocking pigments and especially as photocatalyst. In this paper, the tetraisopropoxide was used as Ti precursor according to sol-gel method. An organic base was applied during sol preparation. Prepared gel was coated on glass substrates and calcined in low temperature to obtain amorphous phase of titania. Prepared coatings were modified by UV picosecond pulse laser with different pulse repetition rate and pulse power. Physical modification of the coatings using laser pulses was intended in order change the phase content of the produced material. Raman spectroscopy (RS) method was applied to studies of modified coatings as it is one of the basic analytical techniques, supporting the identification of compounds and obtaining information about the structure. Especially, RS is a useful method for distinguishing the anatase and rutile phases. In these studies, anatase to rutile transformation was observed, depending on laser parameters.

  18. Mystery of porous SnO 2 thin film formation by pulsed delivery

    Chen, Z. W.; Lai, J. K. L.; Shek, C. H.


    We report a new kind of experimental realization of a porous SnO 2 thin film, which is based on a pulsed delivery process at room temperature. Microstructural analysis shows that the as-prepared thin film consists of a continuous network of interconnected crystalline SnO 2 nanoparticles (rutile structure). As a result, this porous SnO 2 thin film possesses a high surface area and continuous porosity, which is especially desirable for gas sensor design. The optical measurement shows that the porous SnO 2 thin film presents the surface characteristics that generate a red emission band that may be exploited in gas sensors or other optoelectronic devices.

  19. Modification of stearic acid in Ar and Ar-O2 pulsed DC discharge

    Euclides Alexandre Bernardelli


    Full Text Available Stearic acid (CH3(CH216COOH was treated with Ar and Ar-O2 (10% pulsed DC discharges created by a cathode-anode confined system to elucidate the role of oxygen in plasma cleaning. The treatment time (5 to 120 minutes and plasma gas mixture (Ar and Ar-O2 were varied, and the results showed that the mass variation of stearic acid after Ar-O2 plasma exposure was greater than that of pure Ar plasma treatment. Thus, compared to Ar*, active oxygen species (O and O2, in all states enhance the etching process, regardless of their concentration. During the treatments, a liquid phase developed at the melting temperature of stearic acid, and differential thermal analyses showed that the formation of a liquid phase was associated with the breakage of bonds due to treatment with an Ar or Ar-O2 plasma. After treatment with Ar and Ar-O2 plasmas, the sample surface was significantly modified, especially when Ar-O2 was utilized. The role of oxygen in the treatment process is to break carbonaceous chains by forming oxidized products and/or to act as a barrier again ramification, which accelerates the etching of stearic acid.

  20. Electrodeposition and characterization of Ni-ZrO2 nanocomposites by direct and pulse current methods.

    Kumar, K Arunsunai; Mohan, P; Kalaignan, G Paruthimal; Muralidharan, V S


    Direct Current (DC) and Pulse current (PC) methods were used to get nanocrystalline Ni-ZrO2 composites from tri-ammonium citrate bath. In the electrocomposite formation, the ZrO2 particles were transported to the surface by mechanical action and got entrapped in the nickel matrix. Incorporation of ZrO2 in the nickel matrix was found to increase with current densities when DC was employed. Beyond 2 A/dm2, their incorporation became saturated when PC was used. PC method offered better electrocomposites than DC method producing finer grains and uniform surface. Scanning electron micrographs (SEM) reveals that smaller grains and uniform distribution of Zirconia particles in the nickel matrix. The increased hardness of Ni-ZrO2 electrocomposite coatings is due to incorporation of ZrO2 particles in the nickel matrix and also changes in grain size. Incorporation of ZrO2 particles in Ni-matrix favoured the enhanced microhardness and corrosion resistance of the deposit.

  1. Formation of light-emitting Si nanostructures in SiO(2) by pulsed anneals.

    Kachurin, G A; Cherkova, S G; Marin, D V; Yankov, R A; Deutschmann, M


    Intense excimer laser pulses, flash lamp annealing and rapid thermal annealing were used to form Si nanocrystals in thin SiO(2) layers implanted with high doses of Si ions. The pulse durations were 20 ns, 20 ms and 1 s, respectively. Laser annealing produced light sources luminescing in the wavelength range of 400-600 nm. They were attributed to the Si clusters formed as a result of the fast segregation of Si atoms from the SiO(2) network. There were no indications of nanocrystal formation in the as-implanted layers after 20 ns laser pulses; however, nanocrystals formed when, before the laser annealing, the amorphous Si nanoprecipitates were prepared in the oxide layers. Evaluations show that the crystallization may proceed via melting. A photoluminescence band near 800 nm, typical of Si nanocrystals, was found after 20 ms and 1 s anneals. Calculations revealed that the annealing times in both cases were too short to provide the diffusion-limited crystal growth if one uses the values of stationary Si diffusivity in SiO(2). This points toward the existence of a transient rapid growth process at the very beginning of the anneals.

  2. Formation of light-emitting Si nanostructures in SiO2 by pulsed anneals

    Kachurin, G. A.; Cherkova, S. G.; Marin, D. V.; Yankov, R. A.; Deutschmann, M.


    Intense excimer laser pulses, flash lamp annealing and rapid thermal annealing were used to form Si nanocrystals in thin SiO2 layers implanted with high doses of Si ions. The pulse durations were 20 ns, 20 ms and 1 s, respectively. Laser annealing produced light sources luminescing in the wavelength range of 400-600 nm. They were attributed to the Si clusters formed as a result of the fast segregation of Si atoms from the SiO2 network. There were no indications of nanocrystal formation in the as-implanted layers after 20 ns laser pulses; however, nanocrystals formed when, before the laser annealing, the amorphous Si nanoprecipitates were prepared in the oxide layers. Evaluations show that the crystallization may proceed via melting. A photoluminescence band near 800 nm, typical of Si nanocrystals, was found after 20 ms and 1 s anneals. Calculations revealed that the annealing times in both cases were too short to provide the diffusion-limited crystal growth if one uses the values of stationary Si diffusivity in SiO2. This points toward the existence of a transient rapid growth process at the very beginning of the anneals.

  3. Damage on HfO2/SiO2 high-reflecting coatings under single and multiple Nd:YAG laser pulse irradiation

    Weidong Gao; Tao Wang; Yuanan Zhao; Jianda Shao


    The single- and multi-shot damage behaviors of HfO2/SiO2 high-reflecting (HR) coatings under Nd:YAG laser exposure were investigated. Fundamental aspects of multi-shot laser damage, such as the instability due to pulse-to-pulse accumulation of absorption defect and structural defect effect, and the mechanism of laser induced defect generation, are considered. It was found in multi-shot damage, the main factors influencing laser-induced damage threshold (LIDT) are accumulation of irreversible changes of structural defects and thermal stress that induced by thermal density fluctuations.

  4. Resonant infrared matrix-assisted pulsed laser evaporation of TiO2 nanoparticle films

    Mayo, Daniel C.; Paul, Omari; Airuoyo, Idemudia J.; Pan, Zhengda; Schriver, Kenneth E.; Avanesyan, Sergey M.; Park, Hee K.; Mu, Richard R.; Haglund, Richard F.


    The successful development of flexible, high performance thin films that are competitive with silicon-based technology will likely require fabricating films of hybrid materials that incorporate nanomaterials, glasses, ceramics, polymers, and thin films. Resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) is an ideal method for depositing organic materials and nanoparticles with minimal photochemical or photothermal damage to the deposited material. Furthermore, there are many nonhazardous solvents containing chemical functional groups with infrared absorption bands that are accessible using IR lasers. We report here results of recent work in which RIR-MAPLE has been employed successfully to deposit thin films of TiO2 nanoparticles on Si substrates. Using an Er:YAG laser ( λ=2.94 μm), we investigated a variety of MAPLE matrices containing -OH moieties, including water and all four isomers of butyl alcohol. The alcohol isomers are shown to provide effective and relatively nontoxic solvents for use in the RIR-MAPLE process. In addition, we examine the effects of varying concentration and laser fluence on film roughness and surface coverage.

  5. Nucleation mechanism and microstructural assessment of SnO2 nanowires prepared by pulsed laser deposition

    Chen, Z. W.; Lai, J. K. L.; Shek, C. H.


    Tin dioxide, SnO2, nanowires have been successfully synthesized by a pulsed laser deposition process based on a sintered cassiterite SnO2 target, being deposited on Si (100) substrates at room temperature. Transmission electron microscopy shows that nanowires are structurally perfect and uniform, and diameters range from 10 nm to 30 nm, and lengths of several hundreds nanometers to a few micrometers. X-ray diffraction and energy dispersive X-ray spectroscopy analysis indicate that the nanowires have the same crystal structure and chemical composition found in the tetragonal rutile form of SnO2. Selected area electron diffraction and high-resolution transmission electron microscopy reveal that the nanowires grow along the [110] growth direction. In addition to the fundamental Raman scattering peaks, the other two Raman scattering peaks are also observed. We discussed the possible reasons for the appearance of Raman scattering peaks at 518.7 and 701.8 cm-1. The growth process of the SnO2 nanowires is suggested to follow a vapor solid mechanism.

  6. Reduction of TiO2 with hydrogen cold plasma in DC pulsed glow discharge

    ZHANG Yu-wen; DING Wei-zhong; LU Xiong-gang; GUO Shu-qiang; XU Kuang-di


    The reduction of TiO2 to Ti2O3 with hydrogen cold plasma generated by a DC pulsed glow discharge was realized under 2 500 Pa at 1 233 K. Only a little of Ti10O19 and Ti9O17 was detected for using molecular hydrogen.Enhancement effects of hydrogen cold plasma on the reduction were discussed in terms of thermodynamic coupling,kinetics and plasma sheath. The exited hydrogen species are considered more effective reducing agents. It is instructive to reduce refractory oxides with plasma hydrogen at the reduced temperature.

  7. Study on the Structures and Properties of Ni-W-B-CeO2 Composite Coatings Prepared by Pulse Electrodeposition

    Xu Ruidong; Wang Junli; Guo Zhongcheng; Wang Hua


    The aim of this research is to pulse co-deposit nano-CeO2 particles into Ni-W-B alloy coatings in order to improve the surface properties. The influence of pulse frequency and duty circle on deposition rate, microhardness and microstructures, and the influence of heat treatment temperature on phase structures, microhardness and abrasivity of Ni-W-B-CeO2 composite coatings were investigated. The results indicated that the pulse co-deposition of nickel, tungsten, boron and nano-CeO2 particle from the bath which nano-CeO2 particle was suspended by high speed mechanical stirring led to the Ni-W-B-CeO2 composite coatings, possessing better microhardness and abrasion resistance when heat-treated at 400℃ for 1h. The microhardness as-deposited with 636Hz and the deposition rate with 0.0281mm·h-1 was the highest at pulse frequency with 1000Hz and pulse duty circle with 10%. Microstructures analysis displays that decreasing pulse duty cycle leads to refinement in grain structures and the improvement of microstructures. X-ray diffraction shows that the composite coating as-deposited was mainly in the amorphous state and partially crystallized, but when heat treated at 400℃, the crystallization trend was strenthened further.

  8. Effect of Embedded RF Pulsing for Selective Etching of SiO2 in the Dual-Frequency Capacitive Coupled Plasmas.

    Kim, Nam Hun; Jeon, Min Hwan; Kim, Tae Hyung; Yeom, Geun Young


    The characteristics of embedded pulse plasma using 60 MHz radio frequency as the source power and 2 MHz radio frequency as the bias power were investigated for the etching of SiO2 masked with an amorphous carbon layer (ACL) using an Ar/C4F8/O2 gas mixture. Especially, the effects of the different pulse duty ratio of the embedded dual-frequency pulsing between source power and bias power on the characteristics on the plasma and SiO2 etching were investigated. The experiment was conducted by varying the source duty percentage from 90 to 30% while bias duty percentage was fixed at 50%. Among the different duty ratios, the source duty percentage of 60% with the bias duty percentage of 50% exhibited the best results in terms of etch profile and etch selectivity. The change of the etch characteristics by varying the duty ratios between the source power and bias power was believed to be related to the different characteristics of gas dissociation, fluorocarbon passivation, and ion bombardment observed during the different source/bias pulse on/off combinations. In addition, the instantaneous high electron temperature peak observed during each initiation of the source pulse-on period appeared to affect the etch characteristics by significant gas dissociation. The optimum point for the SiO2 etching with the source/bias pulsed dual-frequency capacitively coupled plasma system was obtained by avoiding this instant high electron temperature peak while both the source power and bias power were pulsed almost together, therefore, by an embedded RF pulsing.

  9. High speed pulsed laser cutting of LiCoO2 Li-ion battery electrodes

    Lutey, Adrian H. A.; Fortunato, Alessandro; Carmignato, Simone; Fiorini, Maurizio


    Laser cutting of Li-ion battery electrodes represents an alternative to mechanical blanking that avoids complications associated with tool wear and allows assembly of different cell geometries with a single device. In this study, laser cutting of LiCoO2 Li-ion battery electrodes is performed at up to 5m /s with a 1064nm wavelength nanosecond pulsed fiber laser with a maximum average power of 500W and a repetition rate of up to 2MHz . Minimum average cutting power for cathode and anode multi-layer films is established for 12 parameter groups with velocities over the range 1 - 5m /s , varying laser pulse fluence and overlap. Within the tested parameter range, minimum energy per unit cut length is found to decrease with increasing repetition rate and velocity. SEM analysis of the resulting cut edges reveals visible clearance widths in the range 20 - 50 μm , with cut quality found to improve with velocity due to a reduction in lateral heat conduction losses. Raman line map spectra reveal changes in the cathode at 60 μm from the cut edge, where bands at 486cm-1 and 595cm-1 , corresponding to the Eg and A1g modes of LiCoO2 , are replaced with a single wide band centered at 544cm-1 , and evidence of carbon black is no longer present. No changes in Raman spectra are observed in the anode. The obtained results suggest that further improvements in cutting efficiency and quality could be achieved by increasing the repetition rate above 2MHz , thereby improving ablation efficiency of the metallic conductor layers. The laser source utilized in the present study nonetheless represents an immediately available solution for repeatability and throughput that are superior to mechanical blanking.

  10. Spectroscopic study of 50 Hz pulsed Ar-O2 mixture plasma

    Imran, M.; Rehman, N. U.; Khan, A. W.; Zaka-ul-Islam, M.; Shafiq, M.; Zakaullah, M.


    Plasma sterilization is widely used to disinfect the heat sensitive materials. In this study, we have investigated 50 Hz pulsed capacitively coupled plasma (CCP) system operated in Ar-O2 mixture. Optical emission spectroscopy (OES) is used to identify the optimum conditions suitable for plasma based sterilization. Explicitly, excitation temperature of Ar-I lines, atomic oxygen density, dissociation fraction and UV radiation intensity are measured as a function of discharge parameters. The excitation temperature is calculated using Boltzmann plot method whereas OES has also been employed to evaluate the ground state atomic oxygen density and dissociation fraction. Similarly the normalized UV radiation intensity is determined from UV spectrum in 200-400 nm range. The results show that the total UV emission has optimum value at 20% oxygen, 2 mbar pressure and 2.68 mA/cm2 current density in the mixture. While excitation temperature, atomic oxygen density and dissociation fraction increase with the current density. A comparison with the literature suggests 50 Hz CCP system operated in Ar-O2 mixture has the potential of a cheap and reliable system for plasma sterilization.

  11. Quantum dot formation and dynamic scaling behavior of SnO2 nanocrystals induced by pulsed delivery

    Chen, Z. W.; Lai, J. K. L.; Shek, C. H.


    Quantum dot formation and dynamic scaling behavior of SnO2 nanocrystals in coalescence regime for growth by pulsed-laser deposition is explored experimentally and theoretically, and the same is compared with that for continuous vapor deposition such as molecular-beam epitaxy. Using high-resolution transmission electron microscopy, unusual quantum dots of SnO2 nanocrystals are studied. We present kinetic Monte-Carlo simulations for pulsed-laser deposition in the submonolayer regime and give a description of the island distance versus pulse intensity. We found that the scaling exponent for pulsed-laser deposition is 1.28±0.03, which is significantly lower as compared to that for molecular-beam epitaxy (1.62±0.03). Theoretical simulations reveal that this attractive difference can be pursued to the large fraction of multiple droplet coalescence under pulsed vapor delivery.

  12. Temperature effects on Microalgal Photosynthesis-Light responses measured by O2 production, Pulse-Amplitude-Modulated Fluorescence, and 14C assimilation

    Hancke, Kasper; Hancke, Torunn; Olsen, Lasse M.


    photosynthetic rate (PCmax) was strongly stimulated by temperature, reached an optimum for Pro. minimum only (20oC–25oC), and showed a similar relative temperature response for the three applied methods, with Q10 ranging from 1.7 to 3.5. The maximum light utilization coefficient (alfaC) was insensitive......Short-term temperature effects on photosynthesis were investigated by measuring O2 production, PSII-fluorescence kinetics, and 14C-incorporation rates in monocultures of the marine phytoplankton species Prorocentrum minimum (Pavill.) J. Schiller (Dinophyceae), Prymnesium parvum f. patelliferum ( J...... or decreased slightly with increasing temperature. Absolute rates of O2 production were calculated from pulse-amplitude-modulated (PAM) fluorometry measurements in combination with biooptical determination of absorbed quanta in PSII. The relationship between PAM-based O2 production and measured O2 production...

  13. Reactions of H2O3 in the pulse-irradiated Fe(II)-O2 system

    Sehested, Knud; Bjergbakke, Erling; Lang Rasmussen, O.;


    G(Fe(III)] is measured in pulse-irradiated O2-saturated solutions of 20 to 160 μMFe(II), at the p H's 0.46, 1.51, and 2.74 H2SO4 and HClO4 and with dose rates between 1 and 8 krad/1 μsec pulse. Based on homogeneous kinetics, the results are interpreted by a system of 18 reactions. The formation...

  14. Effect of plasma dissociation on fluorocarbon layers formed under C4F8/Ar pulsed plasma for SiO2 etching

    Matsui, Miyako; Usui, Tatehito; Ono, Tetsuo


    We investigated the effects of gas pressure on the dissociation of C4F8/Ar plasma and the formations of fluorocarbon layers on etched materials by SiO2 etching using pulsed-microwave electron-cyclotron-resonance plasma. Dissociated radicals and molecules of C x F y and CF x species generated from C4F8/Ar plasma were measured by ion attachment mass spectrometry, which is a fragment-free method. The thickness and chemical state of the fluorocarbon layers formed on the etched materials were analyzed by X-ray photoelectron spectroscopy. Higher selective etching of SiO2 relative to Si3N4 was possible at 2.0 Pa but not at 0.5 Pa. Thick fluorocarbon layers, which protect etched materials from ion bombardment, formed on both SiO2 and Si3N4 surfaces; thus, both the SiO2 and Si3N4 etching rates were reduced at a high pressure. However, the CF2 flux ratio increased while the flux ratio of C2F2 decreased as the pressure increased. The increased flux of CF2 enhanced SiO2 etching because CF2 is the main etchant of SiO2. This CF2-rich plasma formed CF2-rich fluorocarbon layers, enhancing the SiO2 etching reaction.

  15. Stability of relative oxygen pulse curve during repeated maximal cardiopulmonary testing in professional soccer players

    R.R. Perim


    Full Text Available During cardiopulmonary exercise testing (CPET, stroke volume can be indirectly assessed by O2 pulse profile. However, for a valid interpretation, the stability of this variable over time should be known. The objective was to analyze the stability of the O2 pulse curve relative to body mass in elite athletes. VO2, heart rate (HR, and relative O2 pulse were compared at every 10% of the running time in two maximal CPETs, from 2005 to 2010, of 49 soccer players. Maximal values of VO2 (63.4 ± 0.9 vs 63.5 ± 0.9 mL O2•kg-1•min-1, HR (190 ± 1 vs188 ± 1 bpm and relative O2 pulse (32.9 ± 0.6 vs 32.6 ± 0.6 mL O2•beat-1•kg-1 were similar for the two CPETs (P > 0.05, while the final treadmill velocity increased from 18.5 ± 0.9 to 18.9 ± 1.0 km/h (P < 0.01. Relative O2 pulse increased linearly and similarly in both evaluations (r² = 0.64 and 0.63 up to 90% of the running time. Between 90 and 100% of the running time, the values were less stable, with up to 50% of the players showing a tendency to a plateau in the relative O2 pulse. In young healthy men in good to excellent aerobic condition, the morphology of the relative O2 pulse curve is consistent up to close to the peak effort for a CPET repeated within a 1-year period. No increase in relative O2pulse at peak effort could represent a physiologic stroke volume limitation in these athletes.

  16. Studies on the Surface Morphology and Orientation of CeO2 Films Deposited by Pulsed Laser Ablation

    Develos, Katherine; Kusunoki, Masanobu; Ohshima, Shigetoshi


    We studied the surface morphology and orientation of CeO2 films grown by pulsed laser ablation (PLA) on r-cut (1\\=102) Al2O3 substrates and evaluated the effects of predeposition annealing conditions of Al2O3 and film thickness of CeO2. The annealing of Al2O3 substrates improves the smoothness of the surface and performing this in high vacuum leads to better crystallinity and orientation of deposited CeO2 films compared to those annealed in oxygen. A critical value of the film thickness was found beyond which the surface roughness increases abruptly. Atomic force microscopy (AFM) study showed that the surface of CeO2 films is characterized by a mazelike pattern. Increasing the film thickness leads to the formation of larger islands which cause the increase in the surface roughness of the films. The areal density and height of these islands increased with film thickness.

  17. Photocatalytic Property of TiO2 Films Deposited by Pulsed DC Magnetron Sputtering

    Wenjie ZHANG; Shenglong ZHU; Ying LI; Fuhui WANG


    TiO2 thin films were prepared by DC magnetron sputtering with the oxygen flow rate higher than the threshold. The film deposited for 5 h was of anatase phase with a preferred orientation along the direction, but the films deposited for 2 and 3 h were amorphous. The transmittance and photocatalytic activity of the TiO2 films increased constantly with increasing film thickness. When the annealing temperature was lower than 700℃, only anatase grew in the TiO2 film. TiO2 phase changed from anatase to rutile when the annealing temperature was above 800℃. The photocatalytic activity decreased with increasing annealing temperature.

  18. Can pulse oximetric saturation (SpO2)/fraction of inspired oxygen (FiO2) ratio surrogate PaO2/ FiO2 ratio in diagnosing acute respiratory failure?

    R, Mehta T; T, Shah C


    Introduction : The condition of acute respiratory failure is one of the most common as well as serious condition that is encountered in the ICU. Diagnosis and immediate management can increase the rate of survival among these patients. Aiming to attain this goal and to ensure that no invasive procedure is tried on the patient several studies have tried to substitute the use of PaO2/FiO2 which is an invasive procedure and risky for patients who have severe blood loss or are anaemic by other re...

  19. Enhancing the photoelectrochemical response of TiO2 nanotubes through their nanodecoration by pulsed-laser-deposited Ag nanoparticles

    Trabelsi, K.; Hajjaji, A.; Gaidi, M.; Bessais, B.; El Khakani, M. A.


    We report on the pulsed laser deposition (PLD) based nanodecoration of titanium dioxide (TiO2) nanotube arrays (NTAs) by Ag nanoparticles (NPs). We focus here on the investigation of the effect of the number of laser ablation pulses (NLP) of the silver target on both the average size of the Ag-NPs and the photoelectrochemical conversion efficiency of the Ag-NP decorated TiO2-NT based photoanodes. By varying the NLP, we were able to not only control the size of the PLD-deposited Ag nanoparticles from 20 to ˜50 nm, but also to increase concomitantly the surface coverage of the TiO2 NTAs by Ag-NPs. The red-shifting of the surface plasmon resonance peak of the PLD-deposited Ag-NPs deposited onto quartz substrates confirmed the increase of their size as the NLP is increased from 500 to 10 000. By investigating the photo-electrochemical properties of Ag-NP decorated TiO2-NTAs, by means of linear sweep cyclic voltammetry under UV-Vis illumination, we found that the generated photocurrent is sensitive to the size of the Ag-NPs and reaches a maximum value at NLP =500 (i.e.,; Ag-NP size of ˜20 nm). For NLP = 500, the photoconversion efficiency of the Ag-NP decorated TiO2-NTAs is shown to reach a maximum of 4.5% (at 0.5 V vs Ag/AgCl). The photocurrent enhancement of Ag-NP decorated TiO2-NTAs is believed to result from the additional light harvesting enabled by the ability of Ag-NPs to absorb visible irradiation caused by various localized surface plasmon resonances, which in turn depend on the size and interdistance of the Ag nanoparticles.

  20. Research on ZrO2 Thermal Barrier Coatings Modified by High-Intensity Pulsed Ion Beam

    WV Di; LIU Chen; ZHU Xiao-Peng; LEI Ming-Kai


    @@ We report a modification method for ZrO2 thermal barrier coatings (TBCs) by high-intensity pulsed ion beam (HIPIB) irradiation. Based on the temporal and spatial distribution models of the ion beam density detected by Faraday cup in the chamber and the ions accelerating voltage, the energy deposition of the beam ions in ZrO2 is calculated by Monte Carlo method. Taking this time-dependent nonlinear deposited energy as the source term of two-dimensional thermal conduction equation, we obtain the temporal and spatial ablation process of ZrO2 thermal barrier coatings during a pulse time. The top-layer TBC material in thickness of about 0.2μm is ablated by vaporization and the coating in thickness of 1 μm is melted after one shot at the ion current density of 200 A/cm2. This calculation is in reasonable agreement with those measured by HIPIB irradiation experiments.The melted top coat becoming a dense modification layer due to HIPIB irradiation seals the gaps among ZrO2crystal clusters, and hence barrels the direct tunnel of oxygen.

  1. Effects of Bias Pulsing on Etching of SiO2 Pattern in Capacitively-Coupled Plasmas for Nano-Scale Patterning of Multi-Level Hard Masks.

    Kim, Sechan; Choi, Gyuhyun; Chae, Heeyeop; Lee, Nae-Eung


    In order to study the effects of bias pulsing on the etching characteristics of a silicon dioxide (SiO2) layer using multi-level hard mask (MLHM) structures of ArF photoresist/bottom anti-reflected coating/SiO2/amorphous carbon layer (ACL)/SiO2, the effects of bias pulsing conditions on the etch characteristics of a SiO2 layer with an ACL mask pattern in C4F8/CH2F2/O2/Ar etch chemistries were investigated in a dual-frequency capacitively-coupled plasma (CCP) etcher. The effects of the pulse frequency, duty ratio, and pulse-bias power in the 2 MHz low-frequency (LF) power source were investigated in plasmas generated by a 27.12 MHz high-frequency (HF) power source. The etch rates of ACL and SiO2 decreased, but the etch selectivity of SiO2/ACL increased with decreasing duty ratio. When the ACL and SiO2 layers were etched with increasing pulse frequency, no significant change was observed in the etch rates and etch selectivity. With increasing LF pulse-bias power, the etch rate of ACL and SiO2 slightly increased, but the etch selectivity of SiO2/ACL decreased. Also, the precise control of the critical dimension (CD) values with decreasing duty ratio can be explained by the protection of sidewall etching of SiO2 by increased passivation. Pulse-biased etching was successfully applied to the patterning of the nano-scale line and space of SiO2 using an ACL pattern.

  2. O2 uptake kinetics and the O2 deficit as related to exercise intensity and blood lactate.

    Barstow, T J; Casaburi, R; Wasserman, K


    The dynamic responses of O2 uptake (VO2) to a range of constant power output levels were related to exercise intensity [as percent maximal VO2 and as below vs. above lactic acid threshold (LAT)] and to the associated end-exercise lactate in three groups of subjects: group I, untrained subjects performing leg cycle ergometer exercise; group II, the same subjects performing arm cycle exercise; and group III, trained cyclists performing leg cycle ergometer exercise. Responses were described by a double-exponential equation, with each component having an independent time delay, which reduced to a monoexponential description for moderate (below-LAT) exercise. When a second exponential component to the VO2 response was present, it did not become evident until approximately 80-100 s into exercise. An overall time constant (tau T, determined as O2 deficit for the total response divided by net end-exercise VO2) and a primary time constant (tau P, determined from the O2 deficit and the amplitude for the early primary VO2 response) were compared. The tau T rose with power output and end-exercise lactate levels, but tau P was virtually invariant, even at high end-exercise lactate levels. Moreover the gain of the primary exponential component (as delta VO2/delta W) was constant across power outputs and blood lactate levels, suggesting that the primary VO2 response reflects a linear system, even at higher power outputs. These results suggest that elevated end-exercise lactate is not associated with any discernible slowing of the primary rise in VO2.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Nanocrystallization of LiCoO2 Cathodes for Thin Film Batteries Utilizing Pulse Thermal Processing



    This factsheet describes a study whose focus is on the nanocrystallization of the LiCoO2 cathode thin films on polyimide substrates and evaluate the microstructural evolution and resistance as a function of PTP processing conditions.

  4. Pulsed laser deposition of HfO2 thin films on indium zinc oxide: Band offsets measurements

    Craciun, D.; Craciun, V.


    One of the most used dielectric films for amorphous indium zinc oxide (IZO) based thin films transistor is HfO2. The estimation of the valence band discontinuity (ΔEV) of HfO2/IZO heterostructure grown using the pulsed laser deposition technique, with In/(In + Zn) = 0.79, was obtained from X-ray photoelectron spectroscopy (XPS) measurements. The binding energies of Hf 4d5, Zn 2p3 and In 3d5 core levels and valence band maxima were measured for thick pure films and for a very thin HfO2 film deposited on a thick IZO film. A value of ΔEV = 1.75 ± 0.05 eV was estimated for the heterostructure. Taking into account the measured HfO2 and IZO optical bandgap values of 5.50 eV and 3.10 eV, respectively, a conduction band offset ΔEC = 0.65 ± 0.05 eV in HfO2/IZO heterostructure was then obtained.

  5. Time-resolved electron temperature and electron density measurements in a nanosecond pulse filament discharge in H2-He and O2-He mixtures

    Roettgen, A.; Shkurenkov, I.; Simeni Simeni, M.; Adamovich, I. V.; Lempert, W. R.


    Time evolution of electron density and electron temperature in a nanosecond pulse, diffuse filament electric discharge in H2-He and O2-He mixtures at a pressure of 100 Torr is studied by Thomson/pure rotational Raman scattering and kinetic modeling. The discharge is sustained between two spherical electrodes separated by a 1 cm gap and powered by high voltage pulses ~150 ns duration. Discharge energy coupled to the plasma filament 2-3 mm in diameter is 4-5 mJ/pulse, with specific energy loading of up to ~0.3 eV/molecule. At all experimental conditions, a rapid initial rise of electron temperature and electron density during the discharge pulse is observed, followed by the decay in the afterglow, over ~100 ns-1 µs. Electron density in the afterglow decays more rapidly as H2 or O2 fraction in the mixture is increased. In He/H2 mixtures, this is likely due to more rapid recombination of electrons in collisions with \\text{H}2+ and \\text{H}3+ ions, compared to recombination with \\text{He}2+ ions. In O2/He mixtures, electron density decay in the afterglow is affected by recombination with \\text{O}2+ and \\text{O}4+ ions, while the effect of three-body attachment is relatively minor. Peak electron number densities and electron temperatures are n e  =  (1.7-3.1) · 1014 cm-3 and T e  =  2.9-5.5 eV, depending on gas mixture composition. Electron temperature in the afterglow decays to approximately T e  ≈  0.3 eV, considerably higher compared to the gas temperature of T  =  300-380 K, inferred from O2 pure rotational Raman scattering spectra, due to superelastic collisions. The experimental results in helium and O2-He mixtures are compared with kinetic modeling predictions, showing good agreement.

  6. Unifying soil respiration pulses, inhibition, and temperature hysteresis through dynamics of labile soil carbon and O2

    Oikawa, P. Y.; Grantz, D. A.; Chatterjee, A.; Eberwein, J. E.; Allsman, L. A.; Jenerette, G. D.


    Event-driven and diel dynamics of soil respiration (Rs) strongly influence terrestrial carbon (C) emissions and are difficult to predict. Wetting events may cause a large pulse or strong inhibition of Rs. Complex diel dynamics include hysteresis in the relationship between Rs and soil temperature. The mechanistic basis for these dynamics is not well understood, resulting in large discrepancies between predicted and observed Rs. We present a unifying approach for interpreting these phenomena in a hot arid agricultural environment. We performed a whole ecosystem wetting experiment with continuous measurement of Rs to study pulse responses to wetting in a heterotrophic system. We also investigated Rs during cultivation of Sorghum bicolor to evaluate the role of photosynthetic C in the regulation of diel variation in Rs. Finally, we adapted a Rs model with sensitivity to soil O2 and water content by incorporating two soil C pools differing in lability. We observed a large wetting-induced pulse of Rs from the fallow field and were able to accurately simulate the pulse via release of labile soil C. During the exponential phase of plant growth, Rs was inhibited in response to wetting, which was accurately simulated through depletion of soil O2. Without plants, hysteresis was not observed; however, with growing plants, an increasingly significant counterclockwise hysteresis developed. Hysteresis was simulated via a dynamic photosynthetic C pool and was not likely controlled by physical processes. These results help characterize the complex regulation of Rs and improve understanding of these phenomena under warmer and more variable conditions.

  7. Application of immobilized TiO2 photocatalysis to improve the inactivation of Heterosigma akashiwo in ballast water by intense pulsed light.

    Feng, Daolun; Xu, Shihong; Liu, Gang


    Ballast water exotic discharge has been identified as a leading vector for marine species invasion. Here immobilized TiO2 photocatalysis is introduced to improve the performance of intense pulsed light. For intense pulsed light/TiO2 photocatalysis, a typical inactivation of 99.89±0.46% can be achieved under treatment condition of 1.78 L min(-1) flow rate, 300 V pulse peak voltage, 15 Hz pulse frequency and 5 ms pulse width. Moreover, within tested 220-260 V peak voltage, 18.37-40.51% elevation in inactivation is observed in comparison with intense pulsed light treatment alone. The rough energy consumption of the tested intense pulsed light/TiO2 treatment system is about 1.51-2.51 times higher than that of the typical commercial UV ballast water treatment system. The stability of the photocatalytic reactivity and intactness of loaded TiO2 film is proved within 20-d's test, while local erosion on stainless steel support is observed after 30-d's test. The results indicate that intense pulsed light/TiO2 photocatalysis is likely to be a competitive ballast water treatment technique, while further measures is needed to reduce the energy consumption and ensure the performance of TiO2 film in a long run.

  8. TiO 2 photocatalysis and related surface phenomena

    Fujishima, Akira; Zhang, Xintong; Tryk, Donald A.


    The field of photocatalysis can be traced back more than 80 years to early observations of the chalking of titania-based paints and to studies of the darkening of metal oxides in contact with organic compounds in sunlight. During the past 20 years, it has become an extremely well researched field due to practical interest in air and water remediation, self-cleaning surfaces, and self-sterilizing surfaces. During the same period, there has also been a strong effort to use photocatalysis for light-assisted production of hydrogen. The fundamental aspects of photocatalysis on the most studied photocatalyst, titania, are still being actively researched and have recently become quite well understood. The mechanisms by which certain types of organic compounds are decomposed completely to carbon dioxide and water, for example, have been delineated. However, certain aspects, such as the photo-induced wetting phenomenon, remain controversial, with some groups maintaining that the effect is a simple one in which organic contaminants are decomposed, while other groups maintain that there are additional effects in which the intrinsic surface properties are modified by light. During the past several years, powerful tools such as surface spectroscopic techniques and scanning probe techniques performed on single crystals in ultra-high vacuum, and ultrafast pulsed laser spectroscopic techniques have been brought to bear on these problems, and new insights have become possible. Quantum chemical calculations have also provided new insights. New materials have recently been developed based on titania, and the sensitivity to visible light has improved. The new information available is staggering, but we hope to offer an overview of some of the recent highlights, as well as to review some of the origins and indicate some possible new directions.

  9. A study on the wake-up effect of ferroelectric Hf0.5Zr0.5O2 films by pulse-switching measurement

    Kim, Han Joon; Park, Min Hyuk; Kim, Yu Jin; Lee, Young Hwan; Moon, Taehwan; Kim, Keum Do; Hyun, Seung Dam; Hwang, Cheol Seong


    The appearance of ferroelectric (FE) and anti-ferroelectric (AFE) properties in HfO2-based thin films is highly intriguing in terms of both the scientific context and practical application in various electronic and energy-related devices. Interestingly, these materials showed a ``wake-up effect'', which refers to the increase in remanent polarization with increasing electric field cycling number before the occurrence of the fatigue effect. In this work, the wake-up effect from Hf0.5Zr0.5O2 was carefully examined by the pulse-switching experiment. In the pristine state, the Hf0.5Zr0.5O2 film mostly showed FE-like behavior with a small contribution from AFE-like distortion, which could be ascribed to the involvement of the AFE phase. The field cycling of only 100 cycles almost completely transformed the AFE phase into the FE phase by depinning the pinned domains. The influence of field cycling on the interfacial layer was also examined through the pulse-switching experiments.

  10. Extended-area nanostructuring of TiO2 with femtosecond laser pulses at 400 nm using a line focus.

    Das, Susanta Kumar; Dasari, Kiran; Rosenfeld, Arkadi; Grunwald, Ruediger


    An efficient way to generate nanoscale laser-induced periodic surface structures (LIPSS) in rutile-type TiO(2) with frequency-converted femtosecond laser pulses at wavelengths around 400 nm is reported. Extended-area structuring on fixed and moving substrates was obtained by exploiting the line focus of a cylindrical lens. Under defined conditions with respect to pulse number, pulse energy and scanning velocity, two types of ripple-like LIPSS with high and low spatial frequencies (HSFL, LSFL) with periods in the range of 90 nm and 340 nm, respectively, were formed. In particular, lower numbers of high energetic pulses favour the generation of LSFL whereas higher numbers of lower energetic pulses enable the preferential creation of HSFL. Theoretical calculations on the basis of the Drude model support the assumption that refractive index changes by photo-excited carriers are a major mechanism responsible for LSFL. Furthermore, the appearance of random substructures as small as 30 nm superimposing low spatial frequency ripples is demonstrated and their possible origin is discussed.

  11. Multifractal spectra of scanning electron microscope images of SnO2 thin films prepared by pulsed laser deposition

    Chen, Z. W.; Lai, J. K. L.; Shek, C. H.


    The concept of fractal geometry has proved useful in describing structures and processes in experimental systems. In this Letter, the surface topographies of SnO2 thin films prepared by pulsed laser deposition for various substrate temperatures were measured by scanning electron microscope (SEM). Multifractal spectra f(α) show that the higher the substrate temperature, the wider the spectrum, and the larger the Δf(Δf=f(α)-f(α)). It is apparent that the nonuniformity of the height distribution increases with the increasing substrate temperature, and the liquid droplets of SnO2 thin films are formed on previous thin films. These results show that the SEM images can be characterized by the multifractal spectra.

  12. Generation Control of ZnO Nanoparticles Using a Coaxial Gas-Flow Pulse Plasma Ar/O2 Plasma

    Hiroki Shirahata


    Full Text Available Generation of ZnO nanoparticles was investigated using a coaxial gas-flow pulse plasma. We studied how zinc atoms, sputtered from a zinc target, reacted with oxygen in a plasma and/or on a substrate to form ZnO nanoparticles when the discharge parameters, such as applied pulse voltage and gas flow rate, were controlled in an O2/Ar plasma. The formation processes were estimated by SEM, TEM, and EDX. We observed many ZnO nanoparticles deposited on Si substrate. The particle yield and size were found to be controlled by changing the experimental parameters. The diameter of the particles was typically 50–200 nm.

  13. Photocatalytic activity of nanostructured TiO2 thin films prepared by pulsed spray pyrolysis

    López, Alcides; Acosta, Dwight; Martínez, Arturo


    Nano-structured TiO2 thin films were deposited onto soda lime glass by the pneumatic spray pyrolysis method from a peroxo-titanium complex solution. Samples were prepared spraying 10 s the complex solution followed by an interruption of 20 s in order to avoid inadequate substrate cooling, the substrate temperature was varied from 230 to 430 °C in 50 °C steps. Amorphous as-deposited films crystallized to the anatase phase after an annealing process at 500 °C for 3 h. The photocatalytic activit...

  14. Ozone generation in a kHz-pulsed He-O2 capillary dielectric barrier discharge operated in ambient air

    Sands, Brian L.; Ganguly, Biswa N.


    The generation of reactive oxygen species using nonequilibrium atmospheric pressure plasma jet devices has been a subject of recent interest due to their ability to generate localized concentrations from a compact source. To date, such studies with plasma jet devices have primarily utilized radio-frequency excitation. In this work, we characterize ozone generation in a kHz-pulsed capillary dielectric barrier discharge configuration comprised of an active discharge plasma jet operating in ambient air that is externally grounded. The plasma jet flow gas was composed of helium with an admixture of up to 5% oxygen. A unipolar voltage pulse train with a 20 ns pulse risetime was used to drive the discharge at repetition rates between 2-25 kHz. Using UVLED absorption spectroscopy centered at 255 nm near the Hartley-band absorption peak, ozone was detected over 1 cm from the capillary axis. We observed roughly linear scaling of ozone production with increasing pulse repetition rate up to a "turnover frequency," beyond which ozone production steadily dropped and discharge current and 777 nm O(5P→5S°) emission sharply increased. The turnover in ozone production occurred at higher pulse frequencies with increasing flow rate and decreasing applied voltage with a common energy density of 55 mJ/cm3 supplied to the discharge. The limiting energy density and peak ozone production both increased with increasing O2 admixture. The power dissipated in the discharge was obtained from circuit current and voltage measurements using a modified parallel plate dielectric barrier discharge circuit model and the volume-averaged ozone concentration was derived from a 2D ozone absorption measurement. From these measurements, the volume-averaged efficiency of ozone production was calculated to be 23 g/kWh at conditions for peak ozone production of 41 mg/h at 11 kV applied voltage, 3% O2, 2 l/min flow rate, and 13 kHz pulse repetition rate, with 1.79 W dissipated in the discharge.


    Hancke, Kasper; Hancke, Torunn B; Olsen, Lasse M; Johnsen, Geir; Glud, Ronnie N


    Short-term temperature effects on photosynthesis were investigated by measuring O2 production, PSII-fluorescence kinetics, and (14) C-incorporation rates in monocultures of the marine phytoplankton species Prorocentrum minimum (Pavill.) J. Schiller (Dinophyceae), Prymnesium parvum f. patelliferum (J. C. Green, D. J. Hibberd et Pienaar) A. Larsen (Coccolithophyceae), and Phaeodactylum tricornutum Bohlin (Bacillariophyceae), grown at 15°C and 80 μmol photons · m(-2)  · s(-1) . Photosynthesis versus irradiance curves were measured at seven temperatures (0°C-30°C) by all three approaches. The maximum photosynthetic rate (P(C) max ) was strongly stimulated by temperature, reached an optimum for Pro. minimum only (20°C-25°C), and showed a similar relative temperature response for the three applied methods, with Q10 ranging from 1.7 to 3.5. The maximum light utilization coefficient (α(C) ) was insensitive or decreased slightly with increasing temperature. Absolute rates of O2 production were calculated from pulse-amplitude-modulated (PAM) fluorometry measurements in combination with biooptical determination of absorbed quanta in PSII. The relationship between PAM-based O2 production and measured O2 production and (14) C assimilation showed a species-specific correlation, with 1.2-3.3 times higher absolute values of P(C) max and α(C) when calculated from PAM data for Pry. parvum and Ph. tricornutum but equivalent for Pro. minimum. The offset seemed to be temperature insensitive and could be explained by a lower quantum yield for O2 production than the theoretical maximum (due to Mehler-type reactions). Conclusively, the PAM technique can be used to study temperature responses of photosynthesis in microalgae when paying attention to the absorption properties in PSII.

  16. Novel Nanostructured MnO2 Prepared by Pulse Electrodeposition: Characterization and Electrokinetics

    H.Adelkhani; M. Ghaemi; S.M. Jafari


    Pulse current technique was applied for the preparation of novel electroactive manganese dioxide and possible influences of different electrokinetic phenomena on material characteristics were discussed.The characteriza-tions of pulse deposited sample (pcMD) were carried out by different techniques: Fourier transform infrared spectroscopy (FTIR),scanning electron microscopy (SEM),X-ray diffraction (XRD),Brunauer-Emmett-Teller (BET) method,Raman spectroscopy,and atomic force microscopy (AFM).SEM image revealed that pulse current could improve the current distribution.This was confirmed by AFM images showing a decrease in surface roughness of pcMDs in comparison to amorphous samples,which were deposited by direct current (dcMD).Higher distortion of MnO6 octahedral environment of dcMD was detected by FTIR and Raman spectroscopy.Cyclic voltammetric (CV) measurements showed a generally higher energy level drained from the second electron discharge of pcMD.This is mainly attributed to a higher surface area and a lower diffusion pass of electrons and protons arisen via a rather unique nanostructural arrangement of pcMD grains.Results indicate a higher surface area available for the non homogenous second electron discharge of pcMD grains.

  17. [Study on cine view of relative enhancement ratio map in O2-enhanced MRI].

    Fujii, Keita; Watanabe, Yasushi; Hanaoka, Shouhei; Motoyoshi, Kouichi; Goto, Masami; Amemiya, Shiori; Ino, Kenji; Akahane, Masaaki; Yano, Keiichi; Ohtomo, Kuni


    Magnetic resonance imaging (MRI) enables the evaluation of organ structure and function. Oxygen-enhanced MRI (O2-enhanced MRI) is a method for evaluating the pulmonary ventilation function using oxygen as a contrast agent. We created the Cine View of Relative Enhancement Ratio Map (Cine RER map) in O2-enhanced MRI to easily observe the contrast effect for clinical use. Relative enhancement ratio (RER) was determined as the pixel values of the Cine RER map. Moreover, six healthy volunteers underwent O2-enhanced MRI to determine the appropriate scale width of the Cine RER map. We calculated each RER and set 0 to 1.27 as the scale width of the Cine RER map based on the results. The Cine RER map made it possible to observe the contrast effect over time and thus is a convenient tool for evaluating the pulmonary ventilation function in O2-enhanced MRI.

  18. Tailoring single-cycle electromagnetic pulses in the 2-9 THz frequency range using DAST/SiO2 multilayer structures pumped at Ti:sapphire wavelength

    Stepanov, Andrei G; Bonacina, Luigi; Wolf, Jean-Pierre; Hauri, Christoph P


    We present a numerical parametric study of single-cycle electromagnetic pulse generation in a DAST/SiO2 multilayer structure via collinear optical rectification of 800 nm femtosecond laser pulses. It is shown that modifications of the thicknesses of the DAST and SiO2 layers allow tuning of the average frequency of the generated THz pulses in the frequency range from 3 to 6 THz. The laser-to-THz energy conversion efficiency in the proposed structures is compared with that in a bulk DAST crystal and a quasi-phase-matching periodically poled DAST crystal and shows significant enhancement.

  19. Study on characteristics of Ni-W-B composites containing CeO2 nano-particles prepared by pulse electrodeposition

    WANG Junli; XU Ruidong; ZHANG Yuzhi


    Ni-W-B composites containing CeO2 nano-particles on the surface of 45 steel were prepared by pulse electrodeposition,and the influence of pulse frequency,pulse duty circle and heat treatment temperature on the structures and properties were investigated.The results indicated that the pulse co-deposition of Ni,W,B and CeO2 nano-particles led to Ni-W-B/CeO2 composites possessing higher microhardness and better wear resistance when heat-treated at 400 ℃ for 1 h.The microhardness of 636 HV and the deposition rate of 0.0281 mm/h of the as-deposited alloy were the highest at pulse frequency of 1000 Hz,pulse duty circle of 10% and pulse average current density of 10 A/dm2.The composites were mainly in the amorphous state and were partially crystallized as-deposited,and the crystallization trend was strengthened when heat-treated at 400 ℃.Decreasing pulse duty cycle from 75% to 10% was favorable to the refinement in grain strctures and improvement ofmicrostructures.The crystal sizes of the composites were smaller by means of pulse electrodeposition.

  20. Smooth YBa2Cu3O7-x thin films prepared by pulsed laser deposition in O2/Ar atmosphere

    Kyhle, Anders; Skov, Johannes; Hjorth, Søren


    We report on pulsed laser deposition of YBa2Cu3O7-x in a diluted O2/Ar gas resulting in thin epitaxial films which are almost outgrowth-free. Films were deposited on SrTiO3 or MgO substrates around 800-degrees-C at a total chamber pressure of 1.0 mbar, varying the argon partial pressure from 0 to 0.......6 mbar. The density of boulders and outgrowths usual for laser deposited films varies strongly with Ar pressure: the outgrowth density is reduced from 1.4 x 10(7) to 4.5 x 10(5) cm-2 with increasing Ar partial pressure, maintaining a critical temperature T(c,zero) almost-equal-to 90 K and a transport...... critical current density J(c)(77 K) greater-than-or-equal-to 10(6) A/cm2 by extended oxygenation time during cool down....

  1. The Electronic Structure of Lanthanide Impurities in TiO2, ZnO, SnO2, and Related Compounds

    Dorenbos, P.


    The vacuum referred binding energy of electrons in the 4fn levels for all divalent and trivalent lanthanide impurity states in TiO2, ZnO, SnO2, and related compounds MTiO3 and MSnO3 (M = Ca2 +, Sr2 +, Ba2 +) and Ca2SnO4 are presented. They are obtained by collecting data from the literature on the s

  2. Internal structure control of the TiO2 nanotubes and polysiloxane nanocomposites by nanosecond pulsed electric field

    Ji-Won Lee


    Full Text Available A facile technique has been introduced for incorporating TiO2 nanotubes (TNTs in amorphous polysiloxane-based nanocomposite films and for linear and dense assembling of these TNTs (LATNTs under application of nanosecond pulse electric field. The use of a nanosecond electrical pulse enables the application of high electric power without causing dielectric breakdown, which occurs when DC/AC electric field is used, and the formation of LATNTs which anchor the resulting composite film planes. The properties of the nanocomposites were investigated using X-ray micro CT scanning, digital micrographs, UV–vis spectroscopy and electrical resistivity measurements. More than 5.5-fold UV–vis transmittance improvement was obtained by the polymer composite containing LATNTs (TNT 5.0 wt%. Such a composite exhibited a decreased electric resistivity of 3.08 × 107 Ω m compared to the case for randomly distributed TNTs (3.25 × 108 Ω m.

  3. 脉冲放电等离子体协同Mn/TiO2-分子筛、Fe/TiO2-分子筛、Cu/TiO2-分子筛催化剂降解甲醛%Research of pulse discharge plasma combined with Mn/TiO2-molecular、Fe/TiO2-molecular、Cu/TiO2-molecular sieve catalysts decomposition of formaldehyde

    董冰岩; 施志勇; 何俊文; 王晖; 周海金; 张鹏; 聂亚林


    In order to further improve formaldehyde removal efficiency,increase carbon dioxide selectivity,and decrease the generation concentration of ozone in pulse discharge plasma,a method of discharge plasma combined with catalysts was adopted in this research. Molecular sieve was used as carrier,then three catalysts were prepared,i.e. Mn/TiO2-molecular sieve,Fe/TiO2-molecular sieve and Cu/TiO2-molecular sieve catalysts,which were characterized by XRD,SEM,EDS and FT-IR. Decomposition of formaldehyde in pulse discharge plasma combined with three catalysts was studied. Effects of plasma combined with different catalysts on formaldehyde removal efficiency,carbon dioxide selectivity and generation concentration of ozone were compared. The results showed that catalysts have synergistic effects on pulse discharge plasma. It could improve formaldehyde removal efficiency,increase carbon dioxide selectivity,and decrease generation concentration of ozone efficiently. Mn/TiO2-molecular sieve catalyst has the best synergistic effect with the impulse voltage of 20kV,the frequency of 40Hz and the gas flow rate of 0.5L/min,i.e. its formaldehyde removal efficiency achieved 94.4% and carbon dioxide selectivity achieved 42.2%. Characterization results showed that Mn/TiO2-molecular sieve catalyst uniform dispersion of active ingredients is as well as the existence of anatase TiO2,and microcrystalline state MnOx increased the oxidation of formaldehyde decomposition. Meanwhile,the mechanism of degrading formaldehyde in discharge plasma combined with Mn/TiO2-molecular sieve catalyst was also discussed.%为进一步提高脉冲放电等离子降解甲醛的效率,增加CO2选择性,降低O3产生量,研究采用放电等离子体和催化剂协同技术.实验以分子筛为载体,分别制备了Mn/TiO2-分子筛、Fe/TiO2-分子筛和Cu/TiO2-分子筛3种催化剂,并利用 XRD、SEM、EDS、FT-IR 方法对催化剂进行表征分析.进行了脉冲放电等离子体协同 3 种催化剂降

  4. Production of simplex RNS and ROS by nanosecond pulse N2/O2 plasma jets with homogeneous shielding gas for inducing myeloma cell apoptosis

    Liu, Zhijie; Xu, Dehui; Liu, Dingxin; Cui, Qingjie; Cai, Haifeng; Li, Qiaosong; Chen, Hailan; Kong, Michael G.


    In this paper, atmospheric pressure N2/O2 plasma jets with homogeneous shielding gas excited by nanosecond pulse are obtained to generate simplex reactive nitrogen species (RNS) and reactive oxygen species (ROS), respectively, for the purpose of studying the simplex RNS and ROS to induce the myeloma cell apoptosis with the same discharge power. The results reveal that the cell death rate by the N2 plasma jet with N2 shielding gas is about two times that of the O2 plasma jet with O2 shielding gas for the equivalent treatment time. By diagnosing the reactive species of ONOO-, H2O2, OH and \\text{O}2- in medium, our findings suggest the cell death rate after plasma jets treatment has a positive correlation with the concentration of ONOO-. Therefore, the ONOO- in medium is thought to play an important role in the process of inducing myeloma cell apoptosis.

  5. Identification of surface oxygen vacancy-related phonon-plasmon coupling in TiO2 single crystal

    Guo, Jun-Hong; Li, Ting-Hui; Hu, Fang-Ren; Liu, Li-Zhe


    Oxygen vacancies (OVs) play a critical role in the physical properties and applications of titanium dioxide nanostructures, which are widely used in electrochemistry and photo catalysis nowadays. In this work, OVs were artificially introduced in the surface of a pure TiO2 single crystal by pulsed laser irradiation. Raman spectra showed that the intensity of Eg mode was enhanced. Theoretical calculations disclose that this was caused by the strong coupling effect between the phonon vibration and plasmon induced by the OVs-related surface deformation, and good agreement was achieved between the experiments and theory. Project supported by the National Natural Science Foundation of China (Grant Nos. 61574080, 11404162, 61505085, and 61264008) and the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20130549).

  6. Factors controlling the microstructure of Ce0.9Gd0.1O2-δ films in pulsed laser deposition process

    Rodrigo, Katarzyna Agnieszka; Heiroth, S.; Döbeli, M.;

    Films of Ce0.9Gd0.1O2-δ(CGO10) are prepared at a range of conditions by pulsed laser deposition (PLD) on a single crystal Si (100) and MgO (100), and on a polycrystalline Pt/MgO (100) substrate. The relationship between the film microstructure, crystallography, chemical composition and PLD...

  7. Hetero-epitaxial growth of the cubic single crystalline HfO 2 film as high k materials by pulsed laser ablation

    Zhang, Xinqiang; Tu, Hailing; Wang, Xiaona; Xiong, Yuhua; Yang, Mengmeng; Wang, Lei; Du, Jun


    We report a hetero-epitaxial growth of cubic single crystalline HfO 2 film on Si substrates as high k materials by pulse laser ablation (PLA) at 820 °C. To eliminate the interfacial defects, the HfO 2 film has then been annealed at 900 °C for 5 min in N 2. Reflection high-energy electron diffraction (RHEED) results indicate orientation of the HfO 2 film on Si substrates corresponding to (∥( and [∥[. An interface layer has been revealed by high-resolution transmission electron microscope (HRTEM). Through capacitance-voltage ( C- V) and current-voltage ( I- V), it has been obtained that the leakage current of the HfO 2 gate insulator with dielectric constant of 26 is 5×10 -6 A/cm 2 at -1 V.

  8. Interfacial reaction and electrical properties of HfO2 film gate dielectric prepared by pulsed laser deposition in nitrogen: role of rapid thermal annealing and gate electrode.

    Wang, Yi; Wang, Hao; Ye, Cong; Zhang, Jun; Wang, Hanbin; Jiang, Yong


    The high-k dielectric HfO(2) thin films were deposited by pulsed laser deposition in nitrogen atmosphere. Rapid thermal annealing effect on film surface roughness, structure and electrical properties of HfO(2) film was investigated. The mechanism of interfacial reaction and the annealing atmosphere effect on the interfacial layer thickness were discussed. The sample annealed in nitrogen shows an amorphous dominated structure and the lowest leakage current density. Capacitors with high-k HfO(2) film as gate dielectric were fabricated, using Pt, Au, and Ti as the top gate electrode whereas Pt constitutes the bottom side electrode. At the gate injection case, the Pt- and Au-gated metal oxide semiconductor devices present a lower leakage current than that of the Ti-gated device, as well as similar leakage current conduction mechanism and interfacial properties at the metal/HfO(2) interface, because of their close work function and chemical properties.

  9. Alleviation of drought stress by mycorrhizas is related to increased root H2O2 efflux in trifoliate orange

    Huang, Yong-Ming; Zou, Ying-Ning; Wu, Qiang-Sheng


    The Non-invasive Micro-test Technique (NMT) is used to measure dynamic changes of specific ions/molecules non-invasively, but information about hydrogen peroxide (H2O2) fluxes in different classes of roots by mycorrhiza is scarce in terms of NMT. Effects of Funneliformis mosseae on plant growth, H2O2, superoxide radical (O2·−), malondialdehyde (MDA) concentrations, and H2O2 fluxes in the taproot (TR) and lateral roots (LRs) of trifoliate orange seedlings under well-watered (WW) and drought stress (DS) conditions were studied. DS strongly inhibited mycorrhizal colonization in the TR and LRs, whereas mycorrhizal inoculation significantly promoted plant growth and biomass production. H2O2, O2·−, and MDA concentrations in leaves and roots were dramatically lower in mycorrhizal seedlings than in non-mycorrhizal seedlings under DS. Compared with non-mycorrhizal seedlings, mycorrhizal seedlings had relatively higher net root H2O2 effluxes in the TR and LRs especially under WW, as well as significantly higher total root H2O2 effluxes in the TR and LRs under WW and DS. Total root H2O2 effluxes were significantly positively correlated with root colonization but negatively with root H2O2 and MDA concentrations. It suggested that mycorrhizas induces more H2O2 effluxes of the TR and LRs, thus, alleviating oxidative damage of DS in the host plant. PMID:28176859

  10. Improved dielectric properties of CaCu3Ti4O12 films with a CaTiO3 interlayer on Pt/TiO2/SiO2/Si substrates prepared by pulsed laser deposition

    Lee, Sung-Yun; Kim, Hui Eun; Jo, William; Kim, Young-Hwan; Yoo, Sang-Im


    We report the greatly improved dielectric properties of CaCu3Ti4O12 (CCTO) films with a 60 nm-thick CaTiO3 (CTO) interlayer on Pt/TiO2/SiO2/Si substrates. Both CCTO films and CTO interlayers were prepared by pulsed laser deposition (PLD). With increasing the thickness of CCTO from 200 nm to 1.3 μm, the dielectric constants ( ɛ r ) at 10 kHz in both CCTO single-layered and CCTO/CTO double-layered films increased from ˜260 to ˜6000 and from ˜630 to ˜3700, respectively. Compared with CCTO single-layered films, CCTO/CTO double-layered films irrespective of CCTO film thickness exhibited a remarkable decrease in their dielectric losses ( tanδ) (Poole-Frenkel conduction model. [Figure not available: see fulltext.

  11. Surface reactive species on MnOx(0.4)-CeO2 catalysts towards soot oxidation assisted with pulse dielectric barrier discharge

    付名利; 林俊敏; 朱文波; 吴军良; 陈礼敏; 黄碧纯; 叶代启


    MnOx(0.4)-CeO2 was investigated for soot oxidation assisted with a pulse dielectric barrier discharge (DBD). The catalysts were evaluated and characterized with TPO (temperature programmed oxidation), X-ray diffraction (XRD), Raman and X-ray photo-electron spectroscopy (XPS). The ignition temperature Ti for soot oxidation decreased from 240.8 to 216.4 ºC with the increase of the pulse DBD frequencies from 50 to 400 Hz, lower than that of the case without pulse DBD present (253.4 ºC). The results of XRD, Raman and XPS agreed well with the TPO activities of MnOx(0.4)-CeO2 towards soot oxidation. More solid solution of ceria and manganese, and surface reactive species including O2-, O-and Mn4+were responsible for the enhancement of soot oxidation due to pulse DBD injection in the present study. For solid solution favors to the activation and transformation of those species, which are be-lieved to be involved in the soot oxidation in a hybrid catalysis-plasma.

  12. Growth of anatase and rutile phase TiO2 nanoparticles using pulsed laser ablation in liquid: Influence of surfactant addition and ablation time variation

    Chaturvedi, Amita; Joshi, M. P.; Mondal, P.; Sinha, A. K.; Srivastava, A. K.


    Titanium dioxide (TiO2) nanoparticles were grown using nanosecond pulsed laser ablation of Ti target in DI water and in 0.001 M sodium dodecyl sulfate (SDS) surfactant aqueous solution. Growth was carried out with varying ablation times i. e. 30 min, 60 min and 90 min. The objective of our study was to investigate the influence of variations in liquid ambience conditions on the growth of the nanoparticles in a pulsed laser ablation in liquid (PLAL) process. Size, composition and optical properties of the grown TiO2 nanoparticles were investigated using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), optical absorption, photoluminescence (PL) spectroscopy and X-ray diffraction (XRD) studies. The obtained nanoparticles of TiO2 were found almost spherical in shape and polycrystalline in nature in both the liquid mediums i.e. DI water and aqueous solution of surfactant. Nanoparticles number density was also found to increase with increasing ablation time in both the liquid mediums. However crystalline phase of the grown TiO2 nanoparticles differs with the change in liquid ambience conditions. Selected area electron diffraction (SAED), PL and XRD studies suggest that DI water ambience is favorable for the growth of anatase phase TiO2 nanoparticles for all ablation times. While Surfactant added water ambience is favorable for the growth of rutile phase TiO2 nanoparticles but for shorter ablation times of 30 min and 60 min only, for longer ablation time of 90 min anatase phase was also observed along with the rutile phase TiO2 nanoparticles. The formation of anatase phase in DI water and rutile and anatase phase in aqueous solution of surfactant is explained on the basis of varying thermodynamic conditions with the two different liquid ambiences and different ablation times.

  13. High-resolution transmission electron microscopy investigation of nanostructures in SnO 2 thin films prepared by pulsed laser deposition

    Chen, Z. W.; Lai, J. K. L.; Shek, C. H.


    Pulsed laser deposition (PLD) was used to grow nanocrystalline SnO 2 thin films onto glass substrates. The nanocrystallites and microstructures in SnO 2 thin films grown by PLD techniques have been investigated in detail by using X-ray diffraction and high-resolution transmission electron microscopy (HRTEM). The PLD process was carried out at room temperature under a working pressure of about 2×10 -6 mbar. Experimental results indicate that thin films are composed of a polycrystalline SnO 2 and an amorphous SnO phase. In particular, the presence of such an amorphous SnO phase in the thin films greatly limits their practical use as gas-sensing devices. HRTEM observations revealed that SnO 2 nanocrystallites with tetragonal rutile structure embed in an amorphous SnO matrix, which are approximatively equiaxed. These approximatively equiaxed SnO 2 nanocrystallites contain a high density of defects, such as twin boundaries and edge dislocations. The grain growth of SnO 2 thin films may be discussed in terms of the coalescent particle growth mechanism.

  14. Phase Relations at 1500°C in the Ternary System ZrO 2-Gd 2O 3-TiO 2

    Feighery, A. J.; Irvine, J. T. S.; Zheng, C.


    Phase relations at 1500°C in the ternary system ZrO2-Gd2O3-TiO2 have been determined by the powder X-ray diffraction of samples prepared by standard solid state reaction. A large area of this ternary oxide system centered on the Gd2Ti2O7-Gd2Zr2O7 join was shown to exhibit the pyrochlore and defect fluorite structures. The pyrochlore structure was observed for stoichiometries as far from the ideal M4O7 as M4O6.7 and M4O7.4, although the degree of disorder seemed much higher at these stoichiometries. On further deviation from the ideal M4O7 stoichiometry a smooth transition to fluorite average structure was observed for Zr-rich compositions. None of the other binary phases were observed to show significant extent of solid solution into the ternary region.

  15. Optical and electrical properties of SnO2 thin films after ultra-short pulsed laser annealing

    Scorticati, D.; Illiberi, A.; Römer, G.R.B.E.; Bor, T.C.; Ogieglo, W.; Klein Gunnewiek, M.; Lenferink, A.; Otto, C.; Skolski, J.Z.P.; Grob, F.; Lange, de D.F.; Huis in 't Veld, A.J.; Reutzel, Edward W.


    Ultra-short pulsed laser sources, with pulse durations in the ps and fs regime, are commonly exploited for cold ablation. However, operating ultra-short pulsed laser sources at fluence levels well below the ablation threshold allows for fast and selective thermal processing. The latter is especially

  16. Optical and electrical properties of SnO2 thin films after ultra-short pulsed laser annealing

    Scorticati, D.; Illiberi, A.; Römer, G.R.B.E.; Bor, T.; Ogieglo, W.; Klein Gunnewiek, M.; Lenferink, A.; Otto, C.; Skolski, J.Z.P.; Grob, F.; de Lange, D.F.; Huis in 't Veld, A.J.; Reutzel, Edward W.


    Ultra-short pulsed laser sources, with pulse durations in the ps and fs regime, are commonly exploited for cold ablation. However, operating ultra-short pulsed laser sources at fluence levels well below the ablation threshold allows for fast and selective thermal processing. The latter is especially

  17. Epitaxial single-crystal thin films of MnxTi1-xO2-δ grown on (rutile)TiO2 substrates with pulsed laser deposition: Experiment and theory

    Ilton, Eugene S.; Droubay, Timothy C.; Chaka, Anne M.; Kovarik, Libor; Varga, Tamas; Arey, Bruce W.; Kerisit, Sebastien N.


    Epitaxial rutile-structured single-crystal MnxTi1-xO2-δ films were synthesized on rutile- (110) and -(001) substrates using pulsed laser deposition. The films were characterized by reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and aberration-corrected transmission electron microscopy (ACTEM). Under the present conditions, 400oC and PO2 = 20 mTorr, single crystal epitaxial thin films were grown for x = 0.13, where x is the nominal average mole fraction of Mn. In fact, arbitrarily thick films could be grown with near invariant Mn/Ti concentration profiles from the substrate/film interface to the film surface. In contrast, at x = 0.25, Mn became enriched towards the surface and a secondary nano-scale phase formed which appeared to maintain the basic rutile structure but with enhanced z-contrast in the tunnels, or tetrahedral interstitial sites. Ab initio thermodynamic calculations provided quantitative estimates for the destabilizing effect of expanding the β-MnO2 lattice parameters to those of TiO2-rutile, the stabilizing effect of diluting Mn with increasing Ti concentration, and competing reaction pathways.

  18. Optimisation of anatase TiO2 thin film growth on LaAlO3(0 0 1) using pulsed laser deposition

    Krupski, K.; Sanchez, A. M.; Krupski, A.; McConville, C. F.


    Optimisation of epitaxial anatase TiO2 thin films grown on LaAlO3(0 0 1) substrates was performed using ultra-high vacuum based pulsed laser deposition (PLD) and studied by in-situ reflection high-energy electron diffraction (RHEED). In addition, ex-situ X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning transmission electron microscopy (STEM) were performed to characterise the bulk properties of these thin films. The deposited TiO2 thin film is demonstrated to have anatase phase and bonded directly to the LaAlO3(0 0 1) substrate. In a separate ultra-high vacuum system low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) measurements were performed and a well-ordered two-domain (1 × 4) and (4 × 1) reconstruction of anatase surface was observed. Analysis of the STM measurements indicates the coexistence of atomic steps of both 2.5 Å and 5.0 Å, confirming the existence of two TiO2 domains. The atomic resolution STEM images reveal that the TiO2/LaAlO3 interface to be terminated with LaO layer and that the anatase-TiO2 reconstruction was found to be stable during the film growth.

  19. High-rate low-temperature dc pulsed magnetron sputtering of photocatalytic TiO2films: the effect of repetition frequency

    Strýhal Z


    Full Text Available AbstractThe article reports on low-temperature high-rate sputtering of hydrophilic transparent TiO2thin films using dc dual magnetron (DM sputtering in Ar + O2mixture on unheated glass substrates. The DM was operated in a bipolar asymmetric mode and was equipped with Ti(99.5 targets of 50 mm in diameter. The substrate surface temperature Tsurfmeasured by a thermostrip was less than 180 °C for all experiments. The effect of the repetition frequency frwas investigated in detail. It was found that the increase of frfrom 100 to 350 kHz leads to (a an improvement of the efficiency of the deposition process that results in a significant increase of the deposition rate aDof sputtered TiO2films and (b a decrease of peak pulse voltage and sustaining of the magnetron discharge at higher target power densities. It was demonstrated that several hundreds nm thick hydrophilic TiO2films can be sputtered on unheated glass substrates at aD = 80 nm/min, Tsurf < 180 °C when high value of fr = 350 kHz was used. Properties of a thin hydrophilic TiO2film deposited on a polycarbonate substrate are given.

  20. Pleomorphic structural imperfections caused by pulsed Bi-implantation in the bulk and thin-film morphologies of TiO2

    Zatsepin, D. A.; Boukhvalov, D. W.; Kurmaev, E. Z.; Gavrilov, N. V.; Kim, S. S.; Zhidkov, I. S.


    The results of combined experimental and theoretical study of pleomorphic substitutional and clustering effects in Bi-doped TiO2 hosts (bulk and thin-film morphologies) are presented. Bi-doping of the bulk and thin-film titanium dioxide was made with help of pulsed ion-implantation (EBi+ = 30 keV, D = 1 × 1017 cm-2) without posterior tempering. The X-ray photoelectron spectroscopy (XPS) qualification (core-levels and valence bands) and Density-Functional Theory (DFT) calculations were employed in order to study the electronic structure of Bi-ion implanted TiO2 samples. According to XPS data obtained and DFT calculations, the Bi → Ti cation substitution occurs in Bi-implanted bulk TiO2, whereas in the thin-film morphology of TiO2:Bi the Bi-atoms have metal-like clusters segregation tendency. Based on the combined XPS and DFT considerations the possible reasons and mechanism for the observed effects are discussed. It is believed that established peculiarities of bismuth embedding into employed TiO2 hosts are mostly the sequence of pleomorphic origin for the formed "bismuth-oxygen" chemical bonding.

  1. Influence of O2 Flux on Compositions and Properties of ITO Films Deposited at Room Temperature by Direct-Current Pulse Magnetron Sputtering

    WANG Hua-Lin; DING Wan-Yu; LIU Chao-Qian; CHAI Wei-Ping


    @@ Indium tin oxide(ITO)films were deposited on glass substrates at room temperature by dc pulse magnetron sputtering.Varying O2 flux,ITO films with different properties are obtained.Both x-ray diffractometer and x-ray photoelectron spectrometer are used to study the change of crystalline structures and bonding structures of ITO films,respectively.Electrical properties are measured by four-point probe measurements.The results indicate that the chemical structures and compositions of ITO films strongly depend on the O2 flux.With increasing O2flux,ITO films display better crystallization,which could decrease the resistivity of films.On the contrary,ITO films contain less O vacancies with increasing O2 flux,which could worsen the conductive properties of films.Without any heat treatment onto the samples,the resistivity of the ITO film could reach 6.0 × 10-4Ω·cm,with the optimai deposition parameter of 0.2 sccm O2 flux.

  2. Effect of relative humidity on the deposition and coagulation of aerosolized SiO2 nanoparticles

    Wang, Youfeng; Chen, Lan; Chen, Rui; Tian, Guolan; Li, Dexing; Chen, Chunying; Ge, Xiujie; Ge, Guanglu


    The temporal evolution of aerosolized SiO2 nanoparticles (NPs) released into an environmental test chamber has been investigated to interrogate the effect of relative humidity (RH) on the deposition and coagulation of the nanoparticles. The size-resolved deposition rate and Brownian coagulation coefficient for the particles at RH of 10%, 27%, 40%, 54%, and 64% are estimated. The results show that the effect of RH on the deposition rate is size-dependent; for particle diameter (Dp) 70 nm, it grows as the RH rises. Generally, both low and high RH tends to enhance the deposition rate, and the minimum rate appears at moderate RH ( 54%). Electrostatic repulsion is probable for the inter-particles interaction at the low RH while the surface roughness due to water molecular adsorption is a main reason for the particle-wall interaction at higher RH. The increasing coagulation coefficient at high humidity correlates to the strong inter-particle adhesion, which may be caused by the water molecular adsorption on the hydrophilic surfaces of the SiO2 NPs due to the formation of nanometer-thick water film. This study suggests that air humidity plays unignorable roles in particle deposition and coagulation.

  3. Efficiency enhancement of TiO2 (active material) solar cell by inserting copper particles grown with pulse voltage electroplating method

    Rokhmat, Mamat; Sutisna; Wibowo, Edy; Khairurrijal; Abdullah, Mikrajuddin


    Here, we report the manufacture of a solar cell using TiO2 nanoparticles as photon absorbers and copper bridges inserted between the TiO2 particles. The copper bridges were synthesized by the pulse voltage electroplating method, and the effect of the pulse duty cycle was explored. The amount of copper deposited between TiO2 particles can be controlled by varying the duty cycles and the deposition time. We found that the cell fabricated by the deposition of copper at duty cycles of 60% and a deposition time of 30 s exhibited the highest efficiency (2.21%). Efficiency was improved to 3.5% following the post-treatment of the cell with NaOH. We also proposed a simple mathematical model to explain the dependence of the efficiency on the amount of copper. Efficiencies of more than 3% for solar cells made by a simple method and using inexpensive materials make these solar cells promising competition for the current commercial solar cells.

  4. Two-dimensional fluid simulation on transient behavior and plasma uniformity in pulsed RF CCP sustained in SiH4 /N2/O2

    Jia, Wen-Zhu; Wang, Xi-Feng; Song, Yuan-Hong; Wang, You-Nian


    Improving plasma uniformity during plasma processing in the microelectronics industry is of critical importance to the quality of etching or deposition. Compared to continuous wave (CW) plasmas, pulsed plasmas have drawn much attention with the introduction of additional pulse parameters, which would be helpful to improve the plasma properties. In this paper, a two-dimensional fluid model is developed to investigate a pulsed radio-frequency capacitively coupled plasma (CCP) sustained in SiH4/N2/O2 mixture at fixed operating conditions of 70V rf power, 300 mTorr (40 Pa) gas pressure and an SiH4/N2/O2 gas ratio of 2.5/92.5/5. First, we study the temporal dynamics of densities of the electron, positive ion and negative ion, at different positions in the pulsed CCP. Under the operation conditions, charged particles, instead of neutral particles, may basically respond to the applied modulated power. The electron density in the bulk could approach a quasi-steady value by the end of the activeglow. However, the achievement of a quasi-steady state of plasma like that in the CW condition not only depends on enough activeglow time of the pulse discharge but also relies on the observed position in the discharge. In addition, we investigate the impact of pulse parameters on plasma characteristics, showing that the radial inhomogeneity of plasma caused by the edge effect can be effectively suppressed by controlling the duty cycle (DC) rather than the pulse repetition frequency (PRF). Improvement of the plasma uniformity in pulsed discharge is due to the competition between the edge effects during the activeglow and diffusion of charged species during the afterglow. Moreover, the electron density undergoes a local minimum value in the temporal profile before it rises sharply beyond that of CW discharge, since production of electrons is less than loss by the spatial movement at the very beginning of one pulse. Also, there appears to be a peak value of ion bombardment energy at

  5. Oxygen partial pressure induced effects on the microstructure and the luminescence properties of pulsed laser deposited TiO2 thin films

    A. K. Kunti


    Full Text Available In this work, the influence of oxygen partial pressure on structural, morphological, and optical properties of TiO2 thin films grown on fused quartz substrate at different oxygen partial pressure by pulsed laser deposition were examined. X-Ray diffraction (XRD patterns show the formation of TiO2 anatase phase deposited at high oxygen pressure. Atomic Force Microscopy (AFM reveals that surface roughness of the films increases with oxygen pressure. Variation of surface morphology of films with increasing oxygen partial pressure was studied by AFM. It is observed that energy band gap of the films increases from 3.27 eV to 3.52 eV with the increase of oxygen pressure and is attributed to the decrease of oxygen defects. TiO2 thin films exhibited blue emission under the excitation of 320 nm wavelength. De-convoluted photoluminescence (PL peaks showed that defect states are responsible for visible emission in TiO2 thin films. The intensity of PL emission associated with oxygen vacancies decreases with increasing oxygen pressure. Photometric characteristic analysis shows that the films deposited 1x10-4 mbar oxygen pressure exhibited intense blue emission with high luminescence efficacy of radiation.

  6. Formation of tin-tin oxide core-shell nanoparticles in the composite SnO2-x/nitrogen-doped carbon nanotubes by pulsed ion beam irradiation

    Korusenko, P. M.; Nesov, S. N.; Bolotov, V. V.; Povoroznyuk, S. N.; Pushkarev, A. I.; Ivlev, K. E.; Smirnov, D. A.


    The complex methods of transmission electron microscopy, energy dispersive X-ray analysis, and X-ray photoelectron spectroscopy were used to investigate the changes in the morphology, phase composition, and electronic structure of the composite SnO2-x/nitrogen-doped multiwalled carbon nanotubes (SnO2-x/N-MWCNTs) irradiated with the pulsed ion beam of nanosecond duration. The irradiation of the composite SnO2-x/N-MWCNTs leads to the formation of nanoparticles with the core-shell structure on the surface of CNTs with a sharp interfacial boundary. It has been established that the "core" is a metal tin (Sn0) with a typical size of 5-35 nm, and the "shell" is a thin amorphous layer (2-6 nm) consisting of nonstoichiometric tin oxide with a low oxygen content. The "core-shell" structure Snsbnd SnOx is formed due to the process of heating and evaporation of SnO2-x under the effect of the ion beam, followed by vapor deposition on the surface of carbon nanotubes.

  7. Influence of pulse electrodeposition parameters on microhardness, grain size and surface morphology of Ni–Co/SiO$_2$ nanocomposite coating



    Ni–Co/SiO$_2$ nanocomposite coatings and Ni–Co alloy coatings were prepared on steel substrate using direct and pulse electrodeposition methods. X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), X-raymap and energy dispersive X-ray spectroscopy (EDX) were employed to investigate the phase structure, surface morphology, and elemental analysis of coatings, respectively. In high discharge rates, the surface morphology was rough, disordered and gross globular; on the contrary, in the low rates, it was smoother, more ordered and fine globular. Also, effect of electrodeposition parameters such as average current density, pulse frequency and duty cycle on the microhardness and grain size of nanocomposite coatings that produced through the pulse current electrodeposition method have been investigated. By amplifying both duty cycles up to 50% and average currentdensity from 2 to 6 A dm$^{−2}$, microhardness increased, while the grain size decreased. But when duty cycle mounted on more than 50% and the average current density went up to 8 A dm$^{−2}$, microhardness lessened, while the grain size rose. The optimum value for pulse frequency was about 25 Hz. Results showed that microhardness of nanocomposite coatings which were produced by pulse current method was higher than that of produced by direct currentmethod.

  8. Fabrication and photoluminescence of Er-doped ZnO thin films on SiO2/Si substrate by pulsed laser deposition

    GU Xiuquan; ZHU Liping; YE Zhizhen; HE Haiping; ZHAO Binghui


    Er doped ZnO thin films were grown on Si substrates using SiO2 buffer layer by pulsed laser deposition (PLD) method.The obtained films crystallize well and show high c-axis orientation.The Er content was evidently detected by the energy dispersive X-ray spectroscopy (EDS).Upon annealing in O2 ambience at different temperatures, the films show different photoluminescence properties at 1.54 μm.The samples annealed at 700 and 850 ℃ show intense photoluminescence peaks which enhance with the annealing temperature, while no obvious luminescence peaks are observed for the as-grown samples or annealed at 500 ℃.The possible mechanism was discussed.

  9. Factors controlling the microstructure of Ce0.9Gd0.1O2-δ films in pulsed laser deposition process

    Rodrigo, Katarzyna Agnieszka; Heiroth, S.; Döbeli, M.;


    Films of Ce0.9Gd0.1O2-delta (CGO10) are prepared at a range of conditions by pulsed laser deposition (PLD) on a single crystal Si (100) and MgO (100), and on a polycrystalline Pt/MgO (100) substrate. The relationship between the film microstructure, crystallography, chemical composition and PLD...... processing parameters is studied. It is found that the laser fluence has no significant impact on the film density, whereas the substrate temperature and the oxygen pressure are of essential importance for the film microstructure development. The reduction of deposition temperature, down to 250 oC, together...

  10. Quantum confinement and its related effects on the critical size of GeO2 nanoparticles anodes for lithium batteries.

    Son, Yoonkook; Park, Mihee; Son, Yeonguk; Lee, Jung-Soo; Jang, Ji-Hyun; Kim, Youngsik; Cho, Jaephil


    This work has been performed to determine the critical size of the GeO2 nanoparticle for lithium battery anode applications and identify its quantum confinement and its related effects on the electrochemical performance. GeO2 nanoparticles with different sizes of ∼ 2, ∼ 6, ∼ 10, and ∼ 35 nm were prepared by adjusting the reaction rate, controlling the reaction temperature and reactant concentration, and using different solvents. Among the different sizes of the GeO2 nanoparticles, the ∼ 6 nm sized GeO2 showed the best electrochemical performance. Unexpectedly smaller particles of the ∼ 2 nm sized GeO2 showed the inferior electrochemical performances compared to those of the ∼ 6 nm sized one. This was due to the low electrical conductivity of the ∼ 2 nm sized GeO2 caused by its quantum confinement effect, which is also related to the increase in the charge transfer resistance. Those characteristics of the smaller nanoparticles led to poor electrochemical performances, and their relationships were discussed.

  11. Elucidating Protactinium Hydrolysis: The Relative Stabilities of PaO2(H2O)(+) and PaO(OH)2(+).

    Dau, Phuong D; Wilson, Richard E; Gibson, John K


    It is demonstrated that the gas-phase oxo-exchange of PaO2(+) with water is substantially faster than that of UO2(+), indicating that the Pa-O bonds are more susceptible to activation and formation of the bis-hydroxide intermediate, PaO(OH)2(+). To elucidate the nature of the water adduct of PaO2(+), hydration of PaO2(+) and UO2(+), as well as collision induced dissociation (CID) and ligand-exchange of the water adducts of PaO2(+) and UO2(+), was studied. The results indicate that, in contrast to UO2(H2O)(+), the protactinium oxo bis-hydroxide isomer, PaO(OH)2(+), is produced as a gas-phase species close in energy to the hydrate isomer, PaO2(H2O)(+). CID behavior similar to that of Th(OH)3(+) supports the assignment as PaO(OH)2(+). The gas-phase results are consistent with the spontaneous hydrolysis of PaO2(+) in aqueous solution, this in contrast to later AnO2(+) (An = U, Np, Pu), which forms stable hydrates in both solution and gas phase. In view of the known propensity for Th(IV) to hydrolyze, and previous gas-phase studies of other AnO2(+), it is concluded that the stabilities of oxo-hydroxides relative to oxide hydrates decreases in the order: Th(IV) > Pa(V) > U(V) > Np(V) > Pu(V). This trend suggests increasing covalency and decreasing ionicity of An-O bonds upon proceeding across the actinide series.

  12. [Outcome measures in perinatal medicine--pO2 and SO2. With remarks on pulse oximetry].

    Roemer, V M


    Due to the outstanding pioneer work of Ronald E. Myers (Bethesda, Maryland) using term rhesus monkey fetuses we know for sure that hypoxia is the leading cause for brain damage and death when exposure occurs perinatally. He defined threshold values for oxygen content and time variables leading to death or cerebral injury. Years later pulsoximetry was developed for measuring fetal oxygen saturation (%) continuously. In this context the obstetrician wants to know: 1) what is the diagnostic potential of pO(2) (mmHg), SO(2) (%) and oxygen content (vol%) in umbilical blood? and 2) using these data could we ascertain fetal pulsoximetry which in addition uses the factor time. In a sample of 7814 term fetuses, delivered in cephalic presentation by the vaginal route, actual blood gases and the variables of the fetal acid-base balance were determined in umbilical blood using equipments (BMS up to ABL 3) from RADIOMETER, Copenhagen. Measurements were done immediately post-partum by trained medical personal. Fetal oxygen saturation (%) for HbF was computed using the algorithm of Ruiz et al. Oxygen content (vol%) was determined according to Severinghaus using Hb values (g%) in each case. The median pO(2) in blood of the umbilical artery (UA) was 17.9 (mean: 18.8 +/- 8.3) mm Hg and in the umbilical vein (UV) 28.5 (mean: 29.3 +/- 9.2) mmHg, respectively. The median oxygen saturation (%) amounted to 24.8 (UA) and 60.9 (UV) using pO(2), pH and pCO(2) for computation in each case. The oxygen variable pO(2) showed no clinically important correlation neither with actual pH (r = 0.032, P = 0.005) nor with base excess (r = 0.047, P values of 6.9 are associated with 10 % oxygen saturation only in UA. P (50) values change dramatically with lowering pH values, i. e., acidosis. Oxygen content (vol %) offers no diagnostic advantages over oxygen saturation. Separation of the whole sample (N = 7814) according to the boundary of 30 % saturation in UA/UV blood leads necessarily to a big

  13. Completely oriented anatase TiO2 nanoarrays: topotactic growth and orientation-related efficient photocatalysis

    Yang, Jingling; Wu, Qili; He, Shiman; Yan, Jing; Shi, Jianying; Chen, Jian; Wu, Mingmei; Yang, Xianfeng


    A TiO2 film has been facilely grown on a Ti foil via a general and simple acid vapor oxidation (AVO) strategy. Based on detailed characterization by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), we found that the TiO2 film was composed of anatase nanoarrays highly oriented along their direction, resulting in a large exposed {001} top surface on the film. The growth mechanism based on a topotactic transformation was proposed according to a careful study of time-dependent experimental results. Resulting from the evaluation of photocatalytic performance compared with a commercial TiO2 photocatalyst (Degussa P25), the as-prepared oriented anatase TiO2 film showed higher efficiency for degradation of atrazine and acid orange II (AOII). The performance of photocatalysis is highly relevant to the preferential orientation. The efficient photocatalysis could be attributed to the highly reactive {001} facets on the anatase nanoarrays with super-hydrophilicity.A TiO2 film has been facilely grown on a Ti foil via a general and simple acid vapor oxidation (AVO) strategy. Based on detailed characterization by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), we found that the TiO2 film was composed of anatase nanoarrays highly oriented along their direction, resulting in a large exposed {001} top surface on the film. The growth mechanism based on a topotactic transformation was proposed according to a careful study of time-dependent experimental results. Resulting from the evaluation of photocatalytic performance compared with a commercial TiO2 photocatalyst (Degussa P25), the as-prepared oriented anatase TiO2 film showed higher efficiency for degradation of atrazine and acid orange II (AOII). The performance of photocatalysis is highly relevant to the preferential orientation. The efficient photocatalysis could be attributed to the highly reactive {001

  14. Antibacterial activity of kaolinite/nanoTiO2 composites in relation to irradiation time.

    Dědková, Kateřina; Matějová, Kateřina; Lang, Jaroslav; Peikertová, Pavlína; Kutláková, Kateřina Mamulová; Neuwirthová, Lucie; Frydrýšek, Karel; Kukutschová, Jana


    The paper addresses laboratory preparation and antibacterial activity testing of kaolinite/nanoTiO2 composite in respect of the daylight irradiation time. Kaolinite/nanoTiO2 composites with 20 and 40 wt% of TiO2 were laboratory prepared, dried at 105 °C and calcined at 600 °C. The calcination caused transformation of kaolinite to metakaolinite and origination of the metakaolinite/nanoTiO2 composite. X-ray powder diffraction, Raman and FTIR spectroscopic methods revealed titanium dioxide only in the form of anatase in all evaluated samples (non-calcined and calcined) and also transformation of kaolinite to metakaolinite after the calcination treatment. Scanning electron microscopy was used as a method for characterization of morphology and elemental composition of the studied samples. A standard microdilution test was used to determine the antibacterial activity using four human pathogenic bacterial strains (Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa). A lamp with a wide spectrum bulb simulating daylight was used for induction of photocatalysis. The antibacterial assays found all the KATI samples to have antibacterial potency with different onset of the activity when calcined samples exhibited antibacterial activity earlier than the non-calcined. Significant difference in antibacterial activity of KATI samples for different bacterial strains was not observed. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Completely oriented anatase TiO2 nanoarrays: topotactic growth and orientation-related efficient photocatalysis.

    Yang, Jingling; Wu, Qili; He, Shiman; Yan, Jing; Shi, Jianying; Chen, Jian; Wu, Mingmei; Yang, Xianfeng


    A TiO2 film has been facilely grown on a Ti foil via a general and simple acid vapor oxidation (AVO) strategy. Based on detailed characterization by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), we found that the TiO2 film was composed of anatase nanoarrays highly oriented along their direction, resulting in a large exposed {001} top surface on the film. The growth mechanism based on a topotactic transformation was proposed according to a careful study of time-dependent experimental results. Resulting from the evaluation of photocatalytic performance compared with a commercial TiO2 photocatalyst (Degussa P25), the as-prepared oriented anatase TiO2 film showed higher efficiency for degradation of atrazine and acid orange II (AOII). The performance of photocatalysis is highly relevant to the preferential orientation. The efficient photocatalysis could be attributed to the highly reactive {001} facets on the anatase nanoarrays with super-hydrophilicity.

  16. One-Dimensional Fluid Model of Pulse Modulated Radio-Frequency SiH4/N2/O2 Discharge

    王燕; 刘相梅; 宋远红; 王友年


    Driven by pulse modulated radio-frequency plasma in capacitively coupled discharge are studied by source, the behavior of SiH4/N2/02 using a one-dimensional fluid model. Totally, 48 different species (electrons, ions, neutrals, radicals and excited species) are involved in this simulation. Time evolution of the particle densities and electron temperature with different duty cycles are obtained, as well as the electronegativity nsiH-3 /ne of the main negative ion (Sill3 ). The results show that, by reducing the duty cycle, higher electron temperature and particle density can be achieved for the same average dissipated power, and the ion energy can also be effectively reduced, which will offer evident improvement in plasma deposition processes compared with the case of continuous wave discharge.

  17. Numerical study on the thermo-stress of ZrO_2 thermal barrier coatings by high-intensity pulsed ion beam irradiation

    Wu Di; Liu Chen; Zhu Xiao Peng; Lei Ming Kai


    This paper studies numerically the thermo-mechanical effects of ZrO_2 thermal barrier coatings (TBCs) irradiated by a high-intensity pulsed ion beam in consideration of the surface structure. Taking the deposited energy of ion beams in TBCs as the source term in the thermal conduction equation, the distribution of temperature in TBCs was simulated. Then, based on the distribution, the evolution of thermal stress was calculated by the finite element method. The results show that tensile radial stress formed at the valley of TBC surfaces after irradiation by HIPIB. Therefore, if cracks happen, they must be at valleys instead of peaks. As for the stress waves, no matter whether through peak or valley position, tensile and compressive stresses are present alternately inside TBCs along the depth direction, and the strength of stress decreases with time.

  18. Photon management properties of rare-earth (Nd,Yb,Sm)-doped CeO2 films prepared by pulsed laser deposition.

    Balestrieri, Matteo; Colis, Silviu; Gallart, Mathieu; Schmerber, Guy; Bazylewski, Paul; Chang, Gap Soo; Ziegler, Marc; Gilliot, Pierre; Slaoui, Abdelilah; Dinia, Aziz


    CeO2 is a promising material for applications in optoelectronics and photovoltaics due to its large band gap and values of the refractive index and lattice parameters, which are suitable for silicon-based devices. In this study, we show that trivalent Sm, Nd and Yb ions can be successfully inserted and optically activated in CeO2 films grown at a relatively low deposition temperature (400 °C), which is compatible with inorganic photovoltaics. CeO2 thin films can therefore be efficiently functionalized with photon-management properties by doping with trivalent rare earth (RE) ions. Structural and optical analyses provide details of the electronic level structure of the films and of their energy transfer mechanisms. In particular, we give evidence of the existence of an absorption band centered at 350 nm from which energy transfer to rare earth ions occurs. The transfer mechanisms can be completely explained only by considering the spontaneous migration of Ce(3+) ions in CeO2 at a short distance from the RE(3+) ions. The strong absorption cross section of the f-d transitions in Ce(3+) ions efficiently intercepts the UV photons of the solar spectrum and therefore strongly increases the potential of these layers as downshifters and downconverters.

  19. Analysis of the properties of functional titanium dioxide thin films deposited by pulsed DC magnetron sputtering with various O2:Ar ratios

    Mazur, Michal


    For the purpose of thin film preparation, pulsed DC magnetron sputtering process was performed and various O2:Ar gas ratios were applied during deposition. Structural properties of thin films deposited with various sputtering atmospheres were determined based on the results of the x-ray diffraction method and Raman spectroscopy, which revealed that all coatings were nanocrystalline and had anatase or rutile structure. The surface morphology of the coatings were investigated with the aid of a scanning electron microscopy and atomic force microscopy. Surface properties were evaluated by x-ray photoelectron spectroscopy and wettability measurements. It was revealed that an increase of Ar amount in the sputtering gas atmosphere caused as a result an increase of thin film water contact angle and enhanced ability of the surface to adsorb water molecules and hydroxyl radicals. Optical properties evaluated on the basis of transmission and reflection measurements showed that all coatings were transparent in the visible wavelength range, but had different refractive index, porosity and packing density. The mechanical properties of the obtained coatings were determined on the basis of nanoindentation tests. Prepared TiO2 thin films had different surface, optical and mechanical properties depending on the gas atmosphere during deposition.

  20. Visible light activity of pulsed layer deposited BiVO4/MnO2 films decorated with gold nanoparticles: The evidence for hydroxyl radicals formation

    Trzciński, Konrad; Szkoda, Mariusz; Sawczak, Mirosław; Karczewski, Jakub; Lisowska-Oleksiak, Anna


    Thin films containing BiVO4 and MnO2 deposited on FTO and modified by Au nanoparticles were studied towards their photoelectrochemical and photocatalytical activities in an aqueous electrolyte. Electrodes were prepared by the pulsed laser deposition (PLD) method. The surfactant-free ablation process was used for preparation of the gold nanoparticles (GNP) water suspension. Obtained layers of varied thicknesses (27-115 nm) were characterized using Raman spectroscopy, UV-vis spectroscopy and scanning electron microscopy. Electrochemical methods such as electrochemical impedance spectroscopy, linear voltammetry and chronoamperometry under visible light illumination and in the dark were applied to characterize layers as photoanodes. Simple modification of the BiVO4 + MnO2 layer by drop-casting of small amount of colloidal gold (1.5 × 10-14 mol of GNP on 1 cm2) leads to enhancement of the generated photocurrent recorded at E = 0.5 V vs. Ag/AgCl (0.1 M KCl) from 63 μA/cm2 to 280 μA/cm2. Photocatalytical studies were also exploited towards decomposition of methylene blue (MB). A possible mechanism of MB photodegradation was proposed. The formation of hydroxyl radicals was detected by photoluminescence spectra using terephthalic acid as the probe molecule.

  1. Pulsed laser deposition of CuInS2 quantum dots on one-dimensional TiO2 nanorod arrays and their photoelectrochemical characteristics

    Han, Minmin; Chen, Wenyuan; Guo, Hongjian; Yu, Limin; Li, Bo; Jia, Junhong


    In the typical solution-based synthesis of colloidal quantum dots (QDs), it always resorts to some surface treatment, ligand exchange processing or post-synthesis processing, which might involve some toxic chemical regents injurious to the performance of QD sensitized solar cells. In this work, the CuInS2 QDs are deposited on the surface of one-dimensional TiO2 nanorod arrays by the pulsed laser deposition (PLD) technique. The CuInS2 QDs are coated on TiO2 nanorods without any ligand engineering, and the performance of the obtained CuInS2 QD sensitized solar cells is optimized by adjusting the laser energy. An energy conversion efficiency of 3.95% is achieved under one sun illumination (AM 1.5, 100 mW cm-2). The improved performance is attributed to enhanced absorption in the longer wavelength region, quick interfacial charge transfer and few chance of carrier recombination with holes for CuInS2 QD-sensitized solar cells. Moreover, the photovoltaic device exhibits high stability in air without any specific encapsulation. Thus, the PLD technique could be further applied for the fabrication of QDs or other absorption materials.

  2. A Study of Parameters Related to the Etch Rate for a Dry Etch Process Using NF3/O2 and SF6/O2

    Seon-Geun Oh


    Full Text Available The characteristics of the dry etching of SiNx:H thin films for display devices using SF6/O2 and NF3/O2 were investigated using a dual-frequency capacitively coupled plasma reactive ion etching (CCP-RIE system. The investigation was carried out by varying the RF power ratio (13.56 MHz/2 MHz, pressure, and gas flow ratio. For the SiNx:H film, the etch rates obtained using NF3/O2 were higher than those obtained using SF6/O2 under various process conditions. The relationships between the etch rates and the usual monitoring parameters—the optical emission spectroscopy (OES intensity of atomic fluorine (685.1 nm and 702.89 nm and the voltages VH and VL—were investigated. The OES intensity data indicated a correlation between the bulk plasma density and the atomic fluorine density. The etch rate was proportional to the product of the OES intensity of atomic fluorine (I(F and the square root of the voltages (Vh+Vl on the assumption that the velocity of the reactive fluorine was proportional to the square root of the voltages.

  3. 甲烷氧化偶联W-Mn/SiO2催化剂上O2-脉冲频率效应(PFE)的研究%A novel phenomenon of O2-Pulses Frequency Effect on Na-W-Mn/SiO2 catalyst

    张兵; 赵军; 牛建中; 丑凌军; 王嘉欣; 李树本


    采用频率脉冲反应方法,以Mn-Na2WO4/SiO2催化剂上甲烷氧化偶联为探针反应,通过实时、原位的四极质谱检测手段,研究氧物种对甲烷C-H键选择性活化的微观历程. 首次发现了Mn-Na2WO4/SiO2催化剂上O2-脉冲频率效应,即脉冲反应产物量随氧脉冲注入频率的增加而增加. 研究结果表明,在反应条件下,Mn-Na2WO4/SiO2催化剂上有两种活化甲烷的氧物种同时存在,它们活化甲烷的方式不同.

  4. Optimization on TNT Liquid Waste Processing with UV/TiO2 and Pulsed Current%UV/TiO2协同交变脉冲电流对梯恩梯废液处理的优化研究

    张怀智; 姬文苏; 黄鹏波; 许玉秋; 李惠明


    以猛炸药TNT为最终目标降解物,采用响应曲面分析方法(RSM ),探讨紫外光光照时间、电解电流、溶液 pH 三者交互作用对 TNT 废液降解处理效果的影响,并对工艺参数进行优化。结果表明:试验因子与评价指标之间的关系符合二次方程模型;UV/TiO2协同交变脉冲电流对 TNT 废液处理最优工艺条件是:紫外光光照时间2.5 h(波长366~380 nm ,催化剂为 TiO2)、电解电流75 A(脉冲峰值电流)、溶液 pH 3.7,在此工艺条件下,TNT 废液的 COD 去除率可达81.34%。%Regarding TNT as the final degradation target ,the response surface methodology (RSM) is applied to discuss the effects of UV illumination time ,electrolytic current and pH on TNT liquid waste degradation processing and the parameters are optimized .The results show the relation between variables and evaluation indexes accords with the quadratic model ;when treating TNT liquid waste with UV /TiO2 and pulsed current ,the optimum conditions should be :UV illumination time of 2 .5 h ,electrolytic current of 75 A and pH = 3 .7 and under this condition ,the removal rate of TNT can reach 81 .34% .

  5. Intraoperative PaO2 is not related to the development of surgical site infections after major cardiac surgery

    Fierro Inma


    Full Text Available Abstract Background The perioperative use of high inspired oxygen fraction (FIO2 for preventing surgical site infections (SSIs has demonstrated a reduction in their incidence in some types of surgery however there exist some discrepancies in this respect. The aim of this study was to analyze the relationship between PaO2 values and SSIs in cardiac patients. Methods We designed a prospective study in which 1,024 patients undergoing cardiac surgery were analyzed. Results SSIs were observed in 5.3% of patients. There was not significant difference in mortality at 30 days between patients with and without SSIs. In the uni and multivariate analysis no differences in function of the inspired oxygen fraction administrated were observed. Conclusions We observed that the PaO2 in adult cardiac surgery patients was not related to SSI rate.

  6. Pulsed electric field improves the bioprotective capacity of purées for different coloured carrot cultivars against H2O2-induced oxidative damage.

    Leong, Sze Ying; Oey, Indrawati; Burritt, David John


    This research aimed to study the effect of pulsed electric field (PEF) processing on the bioprotective capacity of carrot purée for White Belgian, Yellow Solar, Nantes, Nutri Red and Purple Haze cultivars against H2O2-induced oxidative damage. The bioprotective capacity was determined using cell viability, membrane integrity and nitric oxide (NO) production in a human Caco-2 cell culture assay. Total carotenoids, total anthocyanins, total vitamin C and total phenolics were also evaluated. Compared to the untreated purée, Purple Haze and Nutri Red processed at 303 kJ/kg completely increased Caco-2 cells resistance towards oxidative damage by recovering the cell viability and inhibiting NO production. For cultivar with low carotenoid levels, i.e. Yellow Solar, the application of 0.8 kV/cm resulted in a higher total carotenoid content in the purée than its untreated counterpart, leading to an improved bioprotective effect. This study clearly shows that PEF could add value to carrots by maximising bioprotective effects.


    Crichton, Georgina E.; Elias, Merrrill F.; Dore, Gregory A.; Abhayaratna, Walter P.; Robbins, Michael A.


    Modifiable risk factors, such as diet, are becomingly increasingly important in the management of cardiovascular disease, one of the greatest major causes of death and disease burden. Few studies have examined the role of diet as a possible means of reducing arterial stiffness, as measured by pulse wave velocity, an independent predictor of cardiovascular events and all-cause mortality. The aim of this study was to investigate whether dairy food intake is associated with measures of arterial stiffness including carotid-femoral pulse wave velocity and pulse pressure. A cross-sectional analysis of a subset of the Maine Syracuse Longitudinal Study sample was performed. A linear decrease in pulse wave velocity was observed across increasing intakes of dairy food consumption (ranging from never/rarely to daily dairy food intake). The negative linear relationship between pulse wave velocity and intake of dairy food was independent of demographic variables, other cardiovascular disease risk factors and nutrition variables. The pattern of results was very similar for pulse pressure, while no association between dairy food intake and lipid levels was found. Further intervention studies are needed to ascertain whether dairy food intake may be an appropriate dietary intervention for the attenuation of age-related arterial stiffening and reduction of cardiovascular disease risk. PMID:22431583

  8. Simulation study of HEMT structures with HfO2 cap layer for mitigating inverse piezoelectric effect related device failures

    Deepthi Nagulapally


    Full Text Available The Inverse Piezoelectric Effect (IPE is thought to contribute to possible device failure of GaN High Electron Mobility Transistors (HEMTs. Here we focus on a simulation study to probe the possible mitigation of the IPE by reducing the internal electric fields and related elastic energy through the use of high-k materials. Inclusion of a HfO2 “cap layer” above the AlGaN barrier particularly with a partial mesa structure is shown to have potential advantages. Simulations reveal even greater reductions in the internal electric fields by using “field plates” in concert with high-k oxides.

  9. Cu2O/Ag co-deposited TiO2 nanotube array film prepared by pulse-reversing voltage and photocatalytic properties

    Ding, Qi; Chen, Suiyuan; Shang, Fanmin; Liang, Jing; Liu, Changsheng


    In this experiment, Cu2O/Ag co-deposition TiO2 nanotube array (Cu2O-Ag-TNT) film was prepared on pure Ti substrate with the method of combining anodic oxidation and electrodeposition by pulse-reversing voltage power supply in the electrolyte of NH4F, ethylene glycol, CuNO3 · 3H2O and AgNO3. The morphology, phase, chemical composition, photocatalytic property and mechanism of the nanotube array film were studied by means of scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy, UV-vis diffuse reflectance spectra, photoluminescence and photocatalytic degradation under visible light. The results showed that the depositional Cu2O and Ag existed in two forms, being the small-particle dispersion and large-particle sedimentary phase in the nanotube arrays: Cu2O-Ag-TNTs for different doping amounts of Ag could be prepared by adjusting the concentration of AgNO3 and the reverse voltages; with changing of the doping amount of Ag, the band gap and photo-generated electron-hole pair recombination rate also changed, and under the conditions of annealing and the optimized process parameter, the band gap of the nanotube arrays narrowed 0.49 eV and the rate of electron and pair recombination decreased noticeably; the nanotube array film for the concentration of 0.5 cm2 ml-1 degraded the methylene blue of 8 mg L-1, and the degradation rate reached above 98%. The co-deposition Cu2O-Ag-TNT film prepared by the one-step method performed well in the field of photocatalysis under visible light.

  10. Correlation of Photocatalysis and Photoluminescence Effect in Relation to the Surface Properties of TiO2:Tb Thin Films

    Damian Wojcieszak; Danuta Kaczmarek; Jaroslaw Domaradzki; Michal Mazur


    In this paper structural, optical, photoluminescence, and photocatalytic properties of TiO2 and TiO2:(2.6 at. % Tb) thin films have been compared. Thin films were prepared by high-energy reactive magnetron sputtering process, which enables obtaining highly nanocrystalline rutile structure of deposited films. Crystallites sizes were 8.7 nm and 6.6 nm for TiO2 and TiO2:Tb, respectively. Surface of prepared thin films was homogenous with small roughness of ca. 7.2 and 2.1 nm in case of TiO2 and ...

  11. Density relative change and interface zone mutual diffusion of BiFeO3 films prepared on Si (1 0 0), SiO2 and SiO2/Si (1 0 0)

    Xiao, RenZheng; Wang, ZeSong; Yuan, XianBao; Zhou, JianJun; Mao, ZhangLiang; Su, HuaShan; Li, Bo; Fu, DeJun


    The mutual diffusion taken place in the interface zone between BiFeO3 (BFO) films and substrates (Si (1 0 0), SiO2 and SiO2/Si (1 0 0)) has been revealed by energy dispersive X-ray spectroscopy (EDS) and Rutherford Backscattering Spectrometry (RBS). RBS spectra provide the relative atomic concentrations of Bi, Fe, Si, and O elements changed with the samples' depth as analyzed by RBS spectra fitting SIMNRA software. A certain width of the intermixing layer is probably formed between BFO films and individual substrate which is attributed to mutual diffusion in the interface zone during annealing process. The mechanism of concerted exchange component can explain the interface zone mutual diffusion phenomenon between BFO films and substrates. The width of the interface zone between BFO film and Si (1 0 0), SiO2, and SiO2/Si (1 0 0) substrate is about 1.94 × 1017, 2.01 × 1017 and 3.05 × 1017 atoms/cm2, respectively, which are equivalent to 30.9, 36.7, and 52.9 nm, respectively. It has been declared that the effect on density relative to BFO film is loosen or attenuation is presented in the interface zone, which can be interpreted as a migration or diffusion of various atoms during the annealing. This can also provide an evidence of atomic dynamics and defect engineering on interface diffusion.

  12. Synthesis of green TiO2/ZnO/CdS hybrid nano-catalyst for efficient light harvesting using an elegant pulsed laser ablation in liquids method

    Gondal, M. A.; Ilyas, A. M.; Fasasi, T. A.; Dastageer, M. A.; Seddigi, Z. S.; Qahtan, T. F.; Faiz, M.; Khattak, G. D.


    The main limitation on the applications of TiO2 as a photocatalyst is its large band gap (3.2 eV) which limits its absorption only to the ultraviolet region of the solar spectrum. To overcome this problem, a facile strategy for clean synthesis of a nanocomposite green catalyst of zinc oxide (ZnO), titanium dioxide (TiO2) and cadmium sulphide (CdS) was developed using pulsed laser ablation in liquids (PLAL) technique for the first time to the best of our knowledge. The main aim of addition of ZnO is to reduce the electron-hole recombination in the TiO2 while CdS is used to increase the light harvesting efficiency of TiO2 in the visible spectral region. The absorption spectrum of the TiO2/ZnO/CdS composite obtained from the UV-vis spectrophotometer exhibits strong absorption in the visible region as compared to the pure TiO2 whose absorption band lies around 380 nm which is in the UV-region. The morphology of the composite quantum dots was also investigated using high resolution TEM technique which shows that the synthesized composite size ranges between 10 and 40 nm. These nanocomposites have demosntarted noticible improvement in the carriers transport in the visible region which could enhance its efficiency for many applications in the visible region especially for energy harvesting using solar radiations.

  13. SiC/C composites prepared from wood-based carbons by pulse current sintering with SiO2 : Electrical and thermal properties

    Fujisawa, M; Hata, T; Bronsveld, P; Castro, [No Value; Tanaka, F; Kikuchi, H; Furuno, T; Imamura, Y


    A powder mix of wood charcoal and SiO2 was sintered into a SiC/C composite. The heat treatment temperatures were 1400-1800 degreesC, the SiO2 concentration 0, 10, 30 and 50 wt.% with respect to the dry weight of wood charcoal. The microstructure, electrical resistance and thermal conductivity were s

  14. Correlation of Photocatalysis and Photoluminescence Effect in Relation to the Surface Properties of TiO2:Tb Thin Films

    Damian Wojcieszak


    Full Text Available In this paper structural, optical, photoluminescence, and photocatalytic properties of TiO2 and TiO2:(2.6 at. % Tb thin films have been compared. Thin films were prepared by high-energy reactive magnetron sputtering process, which enables obtaining highly nanocrystalline rutile structure of deposited films. Crystallites sizes were 8.7 nm and 6.6 nm for TiO2 and TiO2:Tb, respectively. Surface of prepared thin films was homogenous with small roughness of ca. 7.2 and 2.1 nm in case of TiO2 and TiO2:Tb samples, respectively. Optical properties measurements have shown that the incorporation of Tb into TiO2 matrix has not changed significantly the thin films transparency. It also enables obtaining photoluminescence effect in wide range from 350 to 800 nm, what is unique phenomenon in case of TiO2 with rutile structure. Moreover, it has been found that the incorporation of 2.6 at. % of Tb has increased the photocatalytic activity more than two times as compared to undoped TiO2. Additionally, for the first time in the current state of the art, the relationship between photoluminescence effect, photocatalytic activity, and surface properties of TiO2:Tb thin films has been theoretically explained.

  15. 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

  16. Fractionated breath condensate sampling: H2O2 concentrations of the alveolar fraction may be related to asthma control in children

    Trischler Jordis


    Full Text Available Abstract Background Asthma is a chronic inflammatory disease of the airways but recent studies have shown that alveoli are also subject to pathophysiological changes. This study was undertaken to compare hydrogen peroxide (H2O2 concentrations in different parts of the lung using a new technique of fractioned breath condensate sampling. Methods In 52 children (9-17 years, 32 asthmatic patients, 20 controls measurements of exhaled nitric oxide (FENO, lung function, H2O2 in exhaled breath condensate (EBC and the asthma control test (ACT were performed. Exhaled breath condensate was collected in two different fractions, representing mainly either the airways or the alveoli. H2O2 was analysed in the airway and alveolar fractions and compared to clinical parameters. Results The exhaled H2O2 concentration was significantly higher in the airway fraction than in the alveolar fraction comparing each single pair (p = 0.003, 0.032 and 0.040 for the whole study group, the asthmatic group and the control group, respectively. Asthma control, measured by the asthma control test (ACT, correlated significantly with the H2O2 concentrations in the alveolar fraction (r = 0.606, p = 0.004 but not with those in the airway fraction in the group of children above 12 years. FENO values and lung function parameters did not correlate to the H2O2 concentrations of each fraction. Conclusion The new technique of fractionated H2O2 measurement may differentiate H2O2 concentrations in different parts of the lung in asthmatic and control children. H2O2 concentrations of the alveolar fraction may be related to the asthma control test in children.

  17. Evaluation of a ZrO2 composite membrane in PEM fuel operating at high temperature and low relativity humidity

    Guzman, C.; Alvarez, A.; Godinez, Luis A.; Herrera, O.E.; Merida, W.; Ledesma-Garcia, J.; Arriaga, L.G.


    Using proton exchange fuel cells (PEMFC's) is a sustainable way to generate electrical power. High temperature PEMFC's (HT - PEMFC's) have enhanced electrode kinetics, increased CO tolerance and simplified water management that these operation conditions imply. Unfortunately, Nafion and other perfluorosulfonic acid membranes (PFSA) are characterized by a decreased proton conductivity at high temperatures (above 100 degree C) due to dehydration which also causes shrinkage and increases the contact resistance between the membrane and the electrode. For these reasons, fuel cell research aims to create new membranes capable of working at high temperatures and low relative humidity conditions. The inclusion of inorganic materials into the Nafion matrix are employed to improve the mechanical properties of the membrane and enhance the membrane's hydration. In this study, the composite membrane ZrO2 showed better performance at high temperature and low relative humidity than commercial Nafion membrane. The performance results confirmed that composite membranes retain water and help retain the membrane hydration.

  18. Effects of High Frequency Pulse Power Parameters of Fe-ZrO2 Composite Electrodeposition Coating Surface Nano Content%高频脉冲电源参数对Fe-ZrO2复合电沉积镀层纳米含量的影响

    闫帅; 王元刚; 宁智; 赵子云; 吴蒙华


    为改善低温镀铁工艺镀层的耐磨损耐腐蚀性能,提高镀层表面硬度,以GKDM系列高频脉冲电镀电源为实验复合电沉积工艺电源并配合超声-机械搅拌制备纳米Fe-ZrO2镀层。研究了高频脉冲电源参数:峰值电流导通(TON)、关闭(TOFF)时间;一组正脉冲(TF)负脉冲(TR)的工作时间对镀层表面纳米含量的影响。结果表明当GKDM系列高频脉冲电源TON=200.1 ms,TOFF=800.1 ms时,纳米沉积分布均匀致密,质量分数高。%In order to improve the corrosion and wear of low-temperature iron plating coatings and improve the surface hardness of the coating, GKDM series high-frequency pulse plating power as the experimental composite electrodeposition process power, and with ultrasound - mechanical stirring Nano Fe-ZrO2 coating was made. the parameters of High-frequency pulse power were studied: peak current conduction (TON) closing (TOFF) time; a positive pulse of working (TF) time, a negative pulse of working time impacting on the content of the coating surface nano. The results showed that when TON of the GKDM series high frequency pulse power was 200.1 ms, TOFF was 800.1 ms, Nano Deposition evenly distributed and dense, quality scores was high.

  19. Relating n-pentane isomerization activity to the tungsten surface density of WO(x)/ZrO2.

    Soultanidis, Nikolaos; Zhou, Wu; Psarras, Antonis C; Gonzalez, Alejandro J; Iliopoulou, Eleni F; Kiely, Christopher J; Wachs, Israel E; Wong, Michael S


    Zirconia-supported tungsten oxide (WO(x)/ZrO(2)) is considered an important supported metal oxide model acid catalyst, for which structure-property relationships have been studied for numerous acid-catalyzed reactions. The catalytic activity for xylene isomerization, alcohol dehydration, and aromatic acylation follows a volcano-shape dependence on tungsten surface density. However, WO(x)/ZrO(2) has not been studied for more acid-demanding reactions, like n-pentane isomerization, with regard to surface density dependence. In this work, WO(x)/ZrO(2) was synthesized using commercially available amorphous ZrO(x)(OH)(4-2x) and model crystalline ZrO(2) as support precursors. They were analyzed for n-pentane isomerization activity and selectivity as a function of tungsten surface density, catalyst support type, and calcination temperature. Amorphous ZrO(x)(OH)(4-2x) led to WO(x)/ZrO(2) (WZrOH) that exhibited maximum isomerization activity at ∼5.2 W·nm(-2), and the crystalline ZrO(2) led to a material (WZrO(2)) nearly inactive at all surface densities. Increasing the calcination temperature from 773 to 973 K increased the formation of 0.8-1 nm Zr-WO(x) clusters detected through direct imaging on an aberration-corrected high-resolution scanning transmission electron microscope (STEM). Calcination temperature further increased catalytic activity by at least two times. Brønsted acidity was not affected but Lewis acidity decreased in number, as quantified via pyridine adsorption infrared spectroscopy. WO(x)/ZrO(2) exhibited isomerization activity that peaked within the first 2 h time-on-stream, which may be due to Zr-WO(x) clusters undergoing an activation process.

  20. Pulsed Laser Ablation-Induced Green Synthesis of TiO2 Nanoparticles and Application of Novel Small Angle X-Ray Scattering Technique for Nanoparticle Size and Size Distribution Analysis

    Singh, Amandeep; Vihinen, Jorma; Frankberg, Erkka; Hyvärinen, Leo; Honkanen, Mari; Levänen, Erkki


    This paper aims to introduce small angle X-ray scattering (SAXS) as a promising technique for measuring size and size distribution of TiO2 nanoparticles. In this manuscript, pulsed laser ablation in liquids (PLAL) has been demonstrated as a quick and simple technique for synthesizing TiO2 nanoparticles directly into deionized water as a suspension from titanium targets. Spherical TiO2 nanoparticles with diameters in the range 4-35 nm were observed with transmission electron microscopy (TEM). X-ray diffraction (XRD) showed highly crystalline nanoparticles that comprised of two main photoactive phases of TiO2: anatase and rutile. However, presence of minor amounts of brookite was also reported. The traditional methods for nanoparticle size and size distribution analysis such as electron microscopy-based methods are time-consuming. In this study, we have proposed and validated SAXS as a promising method for characterization of laser-ablated TiO2 nanoparticles for their size and size distribution by comparing SAXS- and TEM-measured nanoparticle size and size distribution. SAXS- and TEM-measured size distributions closely followed each other for each sample, and size distributions in both showed maxima at the same nanoparticle size. The SAXS-measured nanoparticle diameters were slightly larger than the respective diameters measured by TEM. This was because SAXS measures an agglomerate consisting of several particles as one big particle which slightly increased the mean diameter. TEM- and SAXS-measured mean diameters when plotted together showed similar trend in the variation in the size as the laser power was changed which along with extremely similar size distributions for TEM and SAXS validated the application of SAXS for size distribution measurement of the synthesized TiO2 nanoparticles.

  1. Pulsed Laser Ablation-Induced Green Synthesis of TiO2 Nanoparticles and Application of Novel Small Angle X-Ray Scattering Technique for Nanoparticle Size and Size Distribution Analysis.

    Singh, Amandeep; Vihinen, Jorma; Frankberg, Erkka; Hyvärinen, Leo; Honkanen, Mari; Levänen, Erkki


    This paper aims to introduce small angle X-ray scattering (SAXS) as a promising technique for measuring size and size distribution of TiO2 nanoparticles. In this manuscript, pulsed laser ablation in liquids (PLAL) has been demonstrated as a quick and simple technique for synthesizing TiO2 nanoparticles directly into deionized water as a suspension from titanium targets. Spherical TiO2 nanoparticles with diameters in the range 4-35 nm were observed with transmission electron microscopy (TEM). X-ray diffraction (XRD) showed highly crystalline nanoparticles that comprised of two main photoactive phases of TiO2: anatase and rutile. However, presence of minor amounts of brookite was also reported. The traditional methods for nanoparticle size and size distribution analysis such as electron microscopy-based methods are time-consuming. In this study, we have proposed and validated SAXS as a promising method for characterization of laser-ablated TiO2 nanoparticles for their size and size distribution by comparing SAXS- and TEM-measured nanoparticle size and size distribution. SAXS- and TEM-measured size distributions closely followed each other for each sample, and size distributions in both showed maxima at the same nanoparticle size. The SAXS-measured nanoparticle diameters were slightly larger than the respective diameters measured by TEM. This was because SAXS measures an agglomerate consisting of several particles as one big particle which slightly increased the mean diameter. TEM- and SAXS-measured mean diameters when plotted together showed similar trend in the variation in the size as the laser power was changed which along with extremely similar size distributions for TEM and SAXS validated the application of SAXS for size distribution measurement of the synthesized TiO2 nanoparticles.

  2. Pulse

    ... resting for at least 10 minutes. Take the exercise heart rate while you are exercising. ... pulse rate can help determine if the person's heart is pumping. Pulse ... rate gives information about your fitness level and health.

  3. Independent component analysis applied to pulse oximetry in the estimation of the arterial oxygen saturation (SpO2) - a comparative study

    Jensen, Thomas; Duun, Sune Bro; Larsen, Jan


    ), and Mean Field ICA (ICAMF). The signal processing includes pre-processing bandpass filtering to eliminate noise, and post-processing by calculating the SpO2. The algorithms are compared to the commercial state-of-the-art algorithm Discrete Saturation Transform (DST) by Masimo Corporation...

  4. Activation of stress-related signalling pathway in human cells upon SiO2 nanoparticles exposure as an early indicator of cytotoxicity

    Mohamed, Bashir M


    Abstract Background Nanomaterials such as SiO2 nanoparticles (SiO2NP) are finding increasing applications in the biomedical and biotechnological fields such as disease diagnostics, imaging, drug delivery, food, cosmetics and biosensors development. Thus, a mechanistic and systematic evaluation of the potential biological and toxic effects of SiO2NP becomes crucial in order to assess their complete safe applicability limits. Results In this study, human monocytic leukemia cell line THP-1 and human alveolar epithelial cell line A549 were exposed to a range of amorphous SiO2NP of various sizes and concentrations (0.01, 0.1 and 0.5 mg\\/ml). Key biological indicators of cellular functions including cell population density, cellular morphology, membrane permeability, lysosomal mass\\/pH and activation of transcription factor-2 (ATF-2) were evaluated utilizing quantitative high content screening (HCS) approach and biochemical techniques. Despite the use of extremely high nanoparticle concentrations, our findings showed a low degree of cytotoxicity within the panel of SiO2NP investigated. However, at these concentrations, we observed the onset of stress-related cellular response induced by SiO2NP. Interestingly, cells exposed to alumina-coated SiO2NP showed low level, and in some cases complete absence, of stress response and this was consistent up to the highest dose of 0.5 mg\\/ml. Conclusions The present study demonstrates and highlights the importance of subtle biological changes downstream of primary membrane and endocytosis-associated phenomena resulting from high dose SiO2NP exposure. Increased activation of transcription factors, such as ATF-2, was quantitatively assessed as a function of i) human cell line specific stress-response, ii) SiO2NP size and iii) concentration. Despite the low level of cytotoxicity detected for the amorphous SiO2NP investigated, these findings prompt an in-depth focus for future SiO2NP-cell\\/tissue investigations based on the combined

  5. Optimization of Injection Molding Parameters for HDPE/TiO2 Nanocomposites Fabrication with Multiple Performance Characteristics Using the Taguchi Method and Grey Relational Analysis

    Hifsa Pervez


    Full Text Available The current study presents an investigation on the optimization of injection molding parameters of HDPE/TiO2 nanocomposites using grey relational analysis with the Taguchi method. Four control factors, including filler concentration (i.e., TiO2, barrel temperature, residence time and holding time, were chosen at three different levels of each. Mechanical properties, such as yield strength, Young’s modulus and elongation, were selected as the performance targets. Nine experimental runs were carried out based on the Taguchi L9 orthogonal array, and the data were processed according to the grey relational steps. The optimal process parameters were found based on the average responses of the grey relational grades, and the ideal operating conditions were found to be a filler concentration of 5 wt % TiO2, a barrel temperature of 225 °C, a residence time of 30 min and a holding time of 20 s. Moreover, analysis of variance (ANOVA has also been applied to identify the most significant factor, and the percentage of TiO2 nanoparticles was found to have the most significant effect on the properties of the HDPE/TiO2 nanocomposites fabricated through the injection molding process.

  6. Enhanced conductivity in pulsed laser deposited Ce0.9Gd0.1O2−δ/SrTiO3 heterostructures

    Kant, K. Mohan; Esposito, Vincenzo; Pryds, Nini


    Significant enhancement in the electrical conductivity of Ce0.9Gd0.1O2−δ (CGO) thin films (250 and 500 nm) deposited on MgO(001) substrate is observed by introducing ∼ 50 nm thin SrTiO3 buffer layer film. Introduction of the buffer layer is found to form epitaxial films, leading to minimal grain...

  7. Time-resolved imaging of positive pulsed corona-induced surface streamers on TiO2 and γ-Al2O3-supported Ag catalysts

    Kim, Hyun-Ha; Teramoto, Yoshiyuki; Ogata, Atsushi


    We report the first instance of time-resolved imaging of surface streamers in air propagating on the surface of titanium dioxide (TiO2) and alumina (γ-Al2O3) beads at ambient temperature and atmospheric pressure. The propagation velocity of primary streamers was found to be dependent primarily on the applied voltage and the type of catalyst. The presence of Ag nanoparticles enhanced the propagation velocity of primary streamers in both TiO2 and γ-Al2O3. Some of the primary streamers passed through a partial discharge, which resulted in enhanced discharge intensity. Through successive steps, the partial discharge served as a staging point for primary streamers, and promoted their propagation toward the next catalyst bead. For a given configuration and catalyst, the velocity of the primary streamer was largely influenced by applied voltage and catalyst type. For a mesh-to-mesh reactor with Ag/ TiO2 catalyst, the primary streamer reached about 660 km s-1. Secondary streamers occurred with much slower velocities after the primary streamer had disappeared. In contrast to primary streamers, secondary streamer velocities were almost completely independent of the applied voltage on both TiO2 (150  ±  50 km s-1) and γ-Al2O3 (70  ±  10 km s-1). Detailed time-resolved imaging data on surface streamers can provide important insight into understanding and modeling plasma-catalysis, which can accelerate the progress of research and development in this area.

  8. Electronic structure of Co2+ ions in anatase Co:TiO2 in relation to heterogeneity and structural defects

    Lee, Y. J.; de Jong, M. P.; van der Wiel, W. G.


    We have studied the electronic structure of Co ions in semiconducting anatase Co:TiO2(1.4 at.% Co) with x-ray-absorption spectroscopy. The density of structural defects is varied by (i) the oxygen vacancy concentration depending on the oxygen background pressure during growth, and (ii) the film thic

  9. Improved properties of pulsed laser deposited YBaCuO on NdGaO3 using CeO2 template layers

    Blank, Dave H.A.; Rijnders, A.J.H.M.; Roesthuis, F.J.G.; Ouden, den G.; Rogalla, H.


    NdGaO3 (NGO) is, due to its low loss characteristics, a favourite substrate for high frequency applications [1]. However, problems occur when trying to deposit high quality YBaCuO layers on top of it. The optimum deposition temperature during pulsed laser deposition to obtain high Tc, high critical

  10. Influence of environmental temperature and relative humidity on photocatalytic oxidation of toluene on activated carbon fibers coated TiO2


    TiO2 supported on active carbon fiber (TiO2/ACF),an absorbable photocatalyst,is a new kind of material applied in air purification.In this paper,the influence of environmental temperature (T) and relative humidity (RH)on the gas-solid adsorption of toluene and the photocatalyric oxidation (PCO) efficiency of adsorbed toluene on TiO2/ACF were studied,and then,the purification capabil ity of TiO2/ACF was estimated.PCO results showed that although the PCO efficiency increased under high RH and T levels,the amount of adsorption of toluene decreased.Moreover,quantitative analysis results of intermediates indicated that more environmental risk emerged when PCO of toluene was carried out at higher environmental T and RH levels because more toxic intermediates would be accumulated on the TiO2/ACF.So,it is significant to control the environmental T and RH conditions in the application of the PCO technique.T = 25℃ and RH = 30% is the optimal condition for purifying toluene in our experimental system.

  11. Thickness and photocatalytic activity relation in TiO$_2$:N films grown by atomic layer deposition with methylene-blue and E. coli bacteria



    This study presents an analysis of the photocatalytic efficiency in TiO$_2$:N thin films grown by atomic layer deposition related to the film thickness. The nitriding process was carried out with nitrogen plasma by molecular nitrogen decomposition after TiO$_2$ deposition. The study was performed using the time-dependent degradation of colour units for methylene-blue solutions and inactivation percentages for Escherichia coli bacteria, for potential applications in sewage purification. To determine the optoelectronic properties of the films, the optical, structural, surface and thickness characterizations were carried out by photoluminescence, Raman spectroscopy, atomic force microscopy and scanning electron microscopy, respectively.

  12. The development of a model to describe the influence of temperature and relative humidity on respiration rate of prickly pear cactus stems in reduced O2 conditions

    Yahia, E.M.; Guevara, J.C.; Beaudry, R.M.; Tijskens, L.M.M.; Cedeno, L.


    Respiration rate (RO2) of prickly pear cactus stems (Opuntia spp.) was measured as a function of 4 temperature (T) and 6 relative humidity (RH) combinations for O2 partial pressures between 15 and 0.8 kPa, which were considered to support aerobic respiration. The rate of respiration (RO2) was determ

  13. Photocatalytic Activity in CH3CN Related to the Surface Properties of TiO2 Powders Prepared by Sol-Gel Method

    Marta Bettoni


    Full Text Available Some TiO2 powders, prepared from titanium(IVtetraisopropoxide by the sol-gel method and thermally treated between 100 and 1000∘C, have been characterized by X-ray powder diffraction and by nitrogen adsorption and desorption at 77 K to calculate the BET-specific surface area, from which the micropore volume and the external surface area can be derived. The photocatalytic activity (ka of the above powders has been evaluated considering the TiO2-sensitized photo-oxidation of 4-methoxybenzyl alcohol in CH3CN as the test reaction. The decrease of ka have been related to the decrease of the BET surface area, the micropore volume, and the external surface area of the TiO2 powders, but a satisfactory linear correlation is observed only for the last superficial parameter.

  14. Electronic structure and relative stability of 1:1 Cu-O2 adducts from difference-dedicated configuration interaction calculations.

    Zapata-Rivera, Jhon; Caballol, Rosa; Calzado, Carmen J


    A computational strategy to analyze Cu-O(2) adducts based on the use of difference-dedicated configuration interaction (DDCI) calculations is presented. The electronic structure, vertical gaps and nature of the metal-O(2) interaction, and the extension of the charge transfer between both fragments have been investigated. Relative stabilities between isomers are determined from triplet states CCSD(T) calculations. The key point of the here proposed strategy rests on the use of a rationally designed active space, containing only those orbitals, which optimize the interaction pathways between LCu and O(2) fragments. The procedure has been tested on a broad set of model and synthetic biomimetic systems, the results compared with previous theoretical evaluations and/or available experimental data. Our study indicates that this strategy can be considered as an alternative approach to multireference second-order perturbation theory methods to deal with this type of systems with remarkable biradical nature.

  15. Passivation of Al2O3 / TiO2 on monocrystalline Si with relatively low reflectance

    Lu, Chun-Ti; Huang, Yu-Shiang; Liu, C. W.


    Al2O3/TiO2 stack layers deposited by the plasma-enhanced atomic layer deposition enhance photoluminescence intensity by reducing effective surface recombination velocities on both n-type and p-type monocrystalline Si. The field effect of negative oxide charges in the dielectrics is responsible for the low effective surface recombination velocity. The dependence of the effective surface recombination velocity on the photoluminescence intensity is investigated by the 2D numerical simulation. The bilayer stacks without texture also reduce the AM1.5-weighted front side reflectance to 11.8%. The field-effect passivation of Al2O3/TiO2 films is further improved by a forming gas annealing due to the additional increase of the negative oxide charge density.

  16. Reduction of interface traps between poly-Si and SiO2 layers through the dielectric recovery effect during delayed pulse bias stress

    Lee, Dong Uk; Pak, Sangwoo; Lee, Daemyoung; Kim, Yihun; Yang, Haechang; Hong, Sanghoo; Lee, Seungjun; Kim, Eun Kyu


    We investigate the interface trap behavior between tunneling oxide and poly-Si channel layer post erase/write cycling with a delayed pulse by using deep level transient spectroscopy. For comparison of the defect states depending on the stress pulses, a Schottky and a metal-oxide semiconductor device were fabricated. A defect state at about E c -0.51 eV in the Schottky device was measured before the annealing process. Three-hole trap states with activation energies of E v +0.28 eV, E v +0.53 eV, and E v +0.76 eV appeared after the post-annealing process. The electron trap was about E c -0.15 eV after erase/write 3000 cycling was applied at ±10 V for 100 ms at 25 °C and 85 °C. These defect states may have an effect on the charge loss behavior of the electrons localized in the charge trap layer at the retention mode of three-dimensional non-volatile memory devices. Dramatically, after the endurance stress was applied with a delayed pulse of 300 cycling at 85 °C for 50.4 h, no interface traps of the deep level transient spectroscopy spectra appeared. Dielectric recovery can decrease the density of the interface trap and improve the retention properties. This may have been caused by the passivation effect on the dangling bond of the interface traps.

  17. Detailing the relation between renal T2* and renal tissue pO2 using an integrated approach of parametric magnetic resonance imaging and invasive physiological measurements.

    Pohlmann, Andreas; Arakelyan, Karen; Hentschel, Jan; Cantow, Kathleen; Flemming, Bert; Ladwig, Mechthild; Waiczies, Sonia; Seeliger, Erdmann; Niendorf, Thoralf


    This study was designed to detail the relation between renal T2* and renal tissue pO2 using an integrated approach that combines parametric magnetic resonance imaging (MRI) and quantitative physiological measurements (MR-PHYSIOL). Experiments were performed in 21 male Wistar rats. In vivo modulation of renal hemodynamics and oxygenation was achieved by brief periods of aortic occlusion, hypoxia, and hyperoxia. Renal perfusion pressure (RPP), renal blood flow (RBF), local cortical and medullary tissue pO2, and blood flux were simultaneously recorded together with T2*, T2 mapping, and magnetic resonance-based kidney size measurements (MR-PHYSIOL). Magnetic resonance imaging was carried out on a 9.4-T small-animal magnetic resonance system. Relative changes in the invasive quantitative parameters were correlated with relative changes in the parameters derived from MRI using Spearman analysis and Pearson analysis. Changes in T2* qualitatively reflected tissue pO2 changes induced by the interventions. T2* versus pO2 Spearman rank correlations were significant for all interventions, yet quantitative translation of T2*/pO2 correlations obtained for one intervention to another intervention proved not appropriate. The closest T2*/pO2 correlation was found for hypoxia and recovery. The interlayer comparison revealed closest T2*/pO2 correlations for the outer medulla and showed that extrapolation of results obtained for one renal layer to other renal layers must be made with due caution. For T2* to RBF relation, significant Spearman correlations were deduced for all renal layers and for all interventions. T2*/RBF correlations for the cortex and outer medulla were even superior to those between T2* and tissue pO2. The closest T2*/RBF correlation occurred during hypoxia and recovery. Close correlations were observed between T2* and kidney size during hypoxia and recovery and for occlusion and recovery. In both cases, kidney size correlated well with renal vascular conductance

  18. Angiotensin II inhibits ADH-stimulated cAMP: role on O2- and transport-related oxygen consumption in the loop of Henle.

    Silva, G B; Juncos, L I; Baigorria, S T; Garcia, N H


    Dehydration and acute reductions of blood pressure increases ADH and Ang II levels. These hormones increase transport along the distal nephron. In the thick ascending limb (TAL) ADH increases transport via cAMP, while Ang II acts via superoxide (O2-). However, the mechanism of interaction of these hormones in this segment remains unclear. The aim of this study was to explore ADH/Ang II interactions on TAL transport. For this, we measured the effects of ADH/Ang II, added sequentially to TAL suspensions from Wistar rats, on oxygen consumption (QO2) -as a transport index-, cAMP and O2-. Basal QO2 was 112+-5 nmol O2/min/mg protein. Addition of ADH (1nM) increased QO2 by 227 percent. In the presence of ADH, Ang II (1nM) elicited a QO2 transient response. During an initial 3.1+-0.7 minutes after adding Ang II, QO2 decreased 58 percent (p less than 0.03 initial vs. ADH) and then rose by 188 percent (p less than 0.03 late vs initial Ang II). We found that Losartan blocked the initial effects of Ang II and the latter blocked ADH and forskolin-stimulated cAMP. The NOS inhibitor L-NAME or the AT2 receptor antagonist PD123319 showed no effect on transported related oxygen consumption. Then, we assessed the late period after adding Ang II. The O2- scavenger tempol blocked the late Ang II effects on QO2, while Ang II increased O2- production during this period. We conclude that 1) Ang II has a transient effect on ADH-stimulated transport; 2) this effect is mediated by AT1 receptors; 3) the initial period is mediated by decreased cAMP and 4) the late period is mediated by O2-.

  19. Pulsed-Light Inactivation of Food-Related Microorganisms

    N.J. Rowan; MacGregor, S. J.; Anderson, J. G.; Fouracre, R. A.; McIlvaney, L.; Farish, O.


    The effects of high-intensity pulsed-light emissions of high or low UV content on the survival of predetermined populations of Listeria monocytogenes, Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa, Bacillus cereus, and Staphylococcus aureus were investigated. Bacterial cultures were seeded separately on the surface of tryptone soya-yeast extract agar and were reduced by up to 2 or 6 log10 orders with 200 light pulses (pulse duration, ∼100 ns) of low or high UV content, resp...

  20. Electrical and structural characterization of PLD grown CeO2–HfO2 laminated high-k gate dielectrics

    Karakaya, K.; Barcones, B.; Rittersma, Z.M.; Berkum, van J.G.M.; Verheijen, M.A.; Rijnders, G.; Blank, D.H.A.


    The electrical and physical properties of CeO2–HfO2 nanolaminates deposited by pulsed laser deposition (PLD) are investigated. The properties of the nanolaminates are compared with binary CeO2 and HfO2 thin films. Layers were deposited using CeO2 and HfO2 targets at substrate temperatures between 22

  1. Luminosity-peak energy relation in the decay phases of gamma-ray burst pulses


    Using time-resolved spectral data for a sample of 30 pulses in 27 bright GRBs detected with CGRO/BATSE, we investigate the luminosity-peak energy relation (L-E p relation) in the decay phases of these pulses. A tight L-E p relation is found for most of the pulses, but its power law index is various among pulses, which is normally distributed at 1.84±0.60(1σ) for the pulses in our sample, roughly consistent with the L-E p relation within a GRB and the isotropic gamma-ray energy-E p relation among GRBs. The large scatter of the power law index cannot be explained with both the statistical or observational effects and it may be an intrinsic feature, indicating that no universal L-E p relation would be expected among GRBs/pulses. This may strongly weaken the cosmological use of this relation.

  2. Benchmarking NMR experiments: a relational database of protein pulse sequences.

    Senthamarai, Russell R P; Kuprov, Ilya; Pervushin, Konstantin


    Systematic benchmarking of multi-dimensional protein NMR experiments is a critical prerequisite for optimal allocation of NMR resources for structural analysis of challenging proteins, e.g. large proteins with limited solubility or proteins prone to aggregation. We propose a set of benchmarking parameters for essential protein NMR experiments organized into a lightweight (single XML file) relational database (RDB), which includes all the necessary auxiliaries (waveforms, decoupling sequences, calibration tables, setup algorithms and an RDB management system). The database is interfaced to the Spinach library (, which enables accurate simulation and benchmarking of NMR experiments on large spin systems. A key feature is the ability to use a single user-specified spin system to simulate the majority of deposited solution state NMR experiments, thus providing the (hitherto unavailable) unified framework for pulse sequence evaluation. This development enables predicting relative sensitivity of deposited implementations of NMR experiments, thus providing a basis for comparison, optimization and, eventually, automation of NMR analysis. The benchmarking is demonstrated with two proteins, of 170 amino acids I domain of alphaXbeta2 Integrin and 440 amino acids NS3 helicase.

  3. Histogrammatic Method for Determining Relative Abundance of Input Gas Pulse

    Mandrake, Lukas; Bornstein, Benjamin J.; Madzunkov, Stojan; MacAskill, John A.


    To satisfy the Major Constituents Analysis (MCA) requirements for the Vehicle Cabin Atmosphere Monitor (VCAM), this software analyzes the relative abundance ratios for N2, O2, Ar, and CO2 as a function of time and constructs their best-estimate mean. A histogram is first built of all abundance ratios for each of the species vs time. The abundance peaks corresponding to the intended measurement and any obfuscating background are then separated via standard peak-finding techniques in histogram space. A voting scheme is then used to include/exclude this particular time sample in the final average based on its membership to the intended measurement or the background population. This results in a robust and reasonable estimate of the abundance of trace components such as CO2 and Ar even in the presence of obfuscating backgrounds internal to the VCAM device. VCAM can provide a means for monitoring the air within the enclosed environments, such as the ISS (International Space Station), Crew Exploration Vehicle (CEV), a Lunar Habitat, or another vehicle traveling to Mars. Its miniature pre-concentrator, gas chromatograph (GC), and mass spectrometer can provide unbiased detection of a large number of organic species as well as MCA analysis. VCAM s software can identify the concentration of trace chemicals and whether the chemicals are on a targeted list of hazardous compounds. This innovation s performance and reliability on orbit, along with the ground team s assessment of its raw data and analysis results, will validate its technology for future use and development.

  4. Pulsed-light inactivation of food-related microorganisms.

    Rowan, N J; MacGregor, S J; Anderson, J G; Fouracre, R A; McIlvaney, L; Farish, O


    The effects of high-intensity pulsed-light emissions of high or low UV content on the survival of predetermined populations of Listeria monocytogenes, Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa, Bacillus cereus, and Staphylococcus aureus were investigated. Bacterial cultures were seeded separately on the surface of tryptone soya-yeast extract agar and were reduced by up to 2 or 6 log10 orders with 200 light pulses (pulse duration, approximately 100 ns) of low or high UV content, respectively (P < 0.001).

  5. The Relation Between Aortic Pulse Pressure and Coronary Artery Disease

    Ali Metin Esen


    Full Text Available Objective: Pulse pressure (PP is a significant marker of cardiovascular morbidity.We investigated the relation between aortic PP and the presence and extent of coronary artery disease (CAD in patients undergoing diagnostic coronary angiography (CAG.Patients and Method: The study group consisted of 550 patients (363 men, 187 women.We evaluated patients in two different groups, PP < 60 mmHg and ≥ 60 mmHg.Results: In univariate analysis gender and presence of hyperlipidemia showed no statistically significant differences between both groups. However, the ratio of patients having diabetes mellitus, hypertension or smoking were significantly higher in ≥ 60 mmHg PP group. The mean age was 55.2 ±11.9 in < 60 mmHg PP group and 61.3±9.3 in the other group (p<0.01. Although systolic blood pressure level was higher in ≥ 60 mmHg PP group (160.4±21.1 vs. 126.4±13.5, p< 0.001, diastolic blood pressure level showed no significant differences between both groups (78.3±13.5 vs. 80.3±10.2, p= 0.32. In the <60 mmHg PP group, the ratio of normal CAG was significantly higher, and also, the critically CAD rate was lower than the other group. In multivariate analysis, smoking [odds ratios (OR 2.344, 95% confidence intervals (CI, 1.416-3.879], male gender (OR 5.858, 95% CI, 3.425-10.019 and PP ≥60 mmHg (OR 25.788, 95% CI, 14.001-47.498 were evaluated as an independent indicators of CAD.Conclusions: In our study, we demonstrate that, aortic PP ≥60 mmHg is related to the risk of critically CAD as an independent factor.

  6. Pulsed supercritical synthesis of anatase TiO2 nanoparticles in a water-isopropanol mixture studied by in situ powder X-ray diffraction

    Eltzholtz, Jakob Rostgaard; Tyrsted, Christoffer; Jensen, Kirsten Marie Ørnsbjerg; Bremholm, Martin; Christensen, Mogens; Becker-Christensen, Jacob; Iversen, Bo Brummerstedt


    A new step in supercritical nanoparticle synthesis, the pulsed supercritical synthesis reactor, is investigated in situ using synchrotron powder X-ray diffraction (PXRD) to understand the formation of nanoparticles in real time. This eliminates the common problem of transferring information gained during in situ studies to subsequent laboratory reactor conditions. As a proof of principle, anatase titania nanoparticles were synthesized in a 50/50 mixture of water and isopropanol near and above the critical point of water (P = 250 bar, T = 300, 350, 400, 450, 500 and 550 °C). The evolution of the reaction product was followed by sequentially recording PXRD patterns with a time resolution of less than two seconds. The crystallite size of titania is found to depend on both temperature and residence time, and increasing either parameter leads to larger crystallites. A simple adjustment of either temperature or residence time provides a direct method for gram scale production of anatase nanoparticles of average crystallite sizes between 7 and 35 nm, thus giving the option of synthesizing tailor-made nanoparticles. Modeling of the in situ growth curves using an Avrami growth model gave an activation energy of 66(19) kJ mol-1 for the initial crystallization. The in situ PXRD data also provide direct information about the size dependent macrostrain in the nanoparticles and with decreasing crystallite size the unit cell contracts, especially along the c-direction. This agrees well with previous ex situ results obtained for hydrothermal synthesis of titania nanoparticles.A new step in supercritical nanoparticle synthesis, the pulsed supercritical synthesis reactor, is investigated in situ using synchrotron powder X-ray diffraction (PXRD) to understand the formation of nanoparticles in real time. This eliminates the common problem of transferring information gained during in situ studies to subsequent laboratory reactor conditions. As a proof of principle, anatase titania

  7. Ultrafast molecular photoionization by two-color orthogonally polarized ultraviolet laser pulses: Effects of relative pulse phases

    Yuan, Kai-Jun; Chelkowski, Szczepan; Bandrauk, André D.


    We present molecular photoionization by two-color 2ω1 =ω2 orthogonally polarized ultraviolet laser pulses. Simulations are performed on aligned H+ by numerically solving time-dependent Schrödinger equations. Two ionization processes with one ω2 photon interfering with two ω1 photon absorption are studied at different molecular alignments. Molecular frame photoelectron momentum and angular distributions exhibit asymmetries which are functions of the relative pulse phase. For resonant excitation processes by the ω1 pulse, symmetric distributions are obtained. An attosecond ionization model is adopted to describe the ultrafast ionization dynamics. The dependence of the ionization asymmetry on the molecular alignment allows to further monitor interference effects on orbital symmetry.

  8. Carcinogenesis related to intense pulsed light and UV exposure

    Hedelund, L; Lerche, C; Wulf, H C;


    This study examines whether intense pulsed light (IPL) treatment has a carcinogenic potential itself or may influence ultraviolet (UV)-induced carcinogenesis. Secondly, it evaluates whether UV exposure may influence IPL-induced side effects. Hairless, lightly pigmented mice (n=144) received three...

  9. Performance of a precooled 4 K Stirling type high frequency pulse tube cryocooler with Gd2O2S%采用Gd2O2S回热填料的带预冷4 K斯特林型高频脉管制冷机性能研究

    Zhuo-pei LI; Yan-long JIANG; Zhi-hua GAN; Li-min QIU; Jie CHEN


    重要结论:采用孔隙率较小的新型磁性回热填料Gd2O2S可显著改善第一级回热器内压力波与质量流的相位关系,从而减小该级回热损失。减小平均压力可以降低制冷机无负荷制冷温度并减小第二级预冷量,但制冷工质氦的体积比热容会急剧增大,从而使低温级回热器的换热对频率非常敏感。此外,频率对高温级回热器的回热特性影响不明显。该方法可以为三级斯特林型4K多级脉管制冷机提供设计依据。%The efficiency of 4 K Stirling type pulse tube cryocoolers (SPTCs) is rather low due to significant regenerator losses associated with the unique properties of helium around 4 K and the high operating frequencies. In this paper, regenerator per-formance at liquid helium temperature regions under high frequencies is investigated based on a single-stage SPTC precooled by a two-stage Gifford-McMahon type pulse tube cryocooler (GMPTC). The 4 K SPTC used a 10 K cold inertance tube as phase shifters for better phase relationship between pressure and mass flow. The effect of the operating parameters, including frequency and average pressure on the performance of the 4 K SPTC, was investigated and the first and second precooling powers provided by the GMPTC were obtained. To reduce the regenerator heat transfer losses, a multi-layer regenerator matrix, including Gd2O2S (GOS) and HoCu2, was used instead of a single-layer HoCu2 around 4 K. A theoretical and experimental comparison between the two types of regenerator materials was made and the precooling requirements for a regenerator operating at high frequencies to reach liquid helium temperatures were given, which provided guidance for the design of a three-stage SPTC.

  10. Mycorrhiza-induced lower oxidative burst is related with higher antioxidant enzyme activities, net H2O2 effluxes, and Ca2+ influxes in trifoliate orange roots under drought stress.

    Zou, Ying-Ning; Huang, Yong-Ming; Wu, Qiang-Sheng; He, Xin-Hua


    Mechanisms of arbuscular mycorrhiza (AM)-induced lower oxidative burst of host plants under drought stress (DS) are not elucidated. A noninvasive microtest technology (NMT) was used to investigate the effects of Funneliformis mosseae on net fluxes of root hydrogen peroxide (H2O2) and calcium ions (Ca2+) in 5-month-old Poncirus trifoliata, in combination with catalase (CAT) and superoxide dismutase (SOD) activities as well as tissue superoxide radical (O2•-) and H2O2 concentrations under DS and well-watered (WW) conditions. A 2-month DS (55% maximum water holding capacity of growth substrates) significantly inhibited AM fungal root colonization, while AM symbiosis significantly increased plant biomass production, irrespective of water status. F. mosseae inoculation generally increased SOD and CAT activity but decreased O2•- and H2O2 concentrations in leaves and roots under WW and DS. Compared with non-AM seedlings, roots of AM seedlings had significantly higher net H2O2 effluxes and net Ca2+ influxes, especially in the meristem zone, but lower net H2O2 efflux in the elongation zone. Net Ca2+ influxes into roots were significantly positively correlated with root net H2O2 effluxes but negatively with root H2O2 concentrations. Results from this study suggest that AM-induced lower oxidative burst is related with higher antioxidant enzyme activities, root net H2O2 effluxes, and Ca2+ influxes under WW and DS.

  11. 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.

  12. H_2O_2对水稻白叶枯病菌过氧化氢酶相关基因crg表达的诱导作用%Induction of bacterial catalase-related gene expression by H_2O_2 produced during interaction of rice suspension-cultured cells with Xanthomonas oryzae pv. oryzae or applied exogenously

    周建波; 吴茂森; 胡俊; 何晨阳


    为了阐明H_2O_2对水稻白叶枯病菌(Xanthomonas oryzae pv.oryzae,Xoo)过氧化氢酶(CAT)相关基因(crg)表达的诱导作用,本研究定量分析了在水稻细胞-Xoo互作体系及其加入H_2O_2清除剂CAT后H_2O_2产量和crg表达;外源添加H_2O_2后的病菌生长和crg表达.结果表明:在互作条件下,H_2O_2含量稳定增加,10 h可达到峰值;在互作6 h时crg显著地被诱导表达;加入 CAT显著地降低了H_2O_2含量和crg表达;在外源H_2O_2胁迫条件下,H_2O_2以浓度效应的方式影响病菌增殖,显著地诱导了catB和srpA表达.因此,Xoo-水稻互作导致了H_2O_2的发生.无论是互作产生的还是外源的H_2O_2均显著地诱导了Xoo crg表达,从而活化了H_2O_2降解途径.%To elucidate the role of hydrogen peroxide (H_2O_2) produced during the interaction of rice suspension-cultured cells with Xanthomonas oryzae pv. oryzae (Xoo) or applied exogenously in inducing expression of bacterial catalase-related gene (crg), H_2O_2 production and crg expression during the rice-Xoo interaction, in which catalase (CAT) was exogenously added or not, were quantitatively analyzed. In vitro growth and crg expression of Xoo exposed to exogenously-applied H_2O_2 were quantitatively examined as well. Significant increase in H_2O_2 content and crg expression was observed during the interaction, while reduction in H_2O_2 concentration and crg expression was obviously found when CAT was exogenously added to the rice-Xoo interacting system. Growth in vitro was inhibited by exogenously-applied H_2O_2 in a dosage manner, which strongly induced the expression of catB and srpA. Therefore, H_2O_2 production was resulted from the rice-Xoo interaction, and crg expression was significantly induced by H_2O_2 either produced during the interaction or added exogenously.

  13. Mild activation of CeO2-supported gold nanoclusters and insight into the catalytic behavior in CO oxidation.

    Li, Weili; Ge, Qingjie; Ma, Xiangang; Chen, Yuxiang; Zhu, Manzhou; Xu, Hengyong; Jin, Rongchao


    We report a new activation method and insight into the catalytic behavior of a CeO2-supported, atomically precise Au144(SR)60 nanocluster catalyst (where thiolate -SR = -SCH2CH2Ph) for CO oxidation. An important finding is that the activation of the catalyst is closely related to the production of active oxygen species on CeO2, rather than ligand removal of the Au144(SR)60 clusters. A mild O2 pretreatment (at 80 °C) can activate the catalyst, and the addition of reductive gases (CO or H2) can enhance the activation effects of O2 pretreatment via a redox cycle in which CO could reduce the surface of CeO2 to produce oxygen vacancies-which then adsorb and activate O2 to produce more active oxygen species. The CO/O2 pulse experiments confirm that CO is adsorbed on the cluster catalyst even with ligands on, and active oxygen species present on the surface of the pretreated catalyst reacts with CO pulses to generate CO2. The Au144(SR)60/CeO2 exhibits high CO oxidation activity at 80 °C without the removal of thiolate ligands. The surface lattice-oxygen of the support CeO2 possibly participates in the oxidation of CO over the Au144(SR)60/CeO2 catalyst.

  14. Carcinogenesis related to intense pulsed light and UV exposure

    Hedelund, L; Lerche, C; Wulf, H C;


    This study examines whether intense pulsed light (IPL) treatment has a carcinogenic potential itself or may influence ultraviolet (UV)-induced carcinogenesis. Secondly, it evaluates whether UV exposure may influence IPL-induced side effects. Hairless, lightly pigmented mice (n=144) received three...... observation period. Side effects were evaluated clinically. No tumors appeared in untreated control mice or in just IPL-treated mice. Skin tumors developed in UV-exposed mice independently of IPL treatments. The time it took for 50% of the mice to first develop skin tumor ranged from 47 to 49 weeks...

  15. Ultraviolet Photoelectric Effect in ZrO2 Single Crystals

    XING Jie; WANG Xu; ZHAO Kun; LI Jie; JIN Kui-Juan; HE Meng; ZHENG Dong-Ning; L(U) Hui-Bin


    Nanosecond photoelectric effect is observed in a ZrO2 single crystal at ambient temperature for the first time.The rise time is 20ns and the full width at half maximum is about 30ns for the photovoltaic pulse when the wafer surface of the ZrO2 single crystal is irradiated by 248nm KrF laser pulses. The experimental results show that ZrO2 single crystals may be a potential candidate in UV photodetectors.

  16. Time-resolved detection of relative intensity squeezed nanosecond pulses in a 87Rb vapor

    Agha, Imad H; Messin, Gaetan; Grangier, Philippe


    We present experimental studies on the generation and detection of pulsed, relative-intensity squeezed light in a warm rubidium vapor. The noise correlations between a pulsed probe beam and its conjugate -generated through nearly-degenerate four-wave mixing in a double-lambda system- are studied via time-resolved balanced detection. We observe -0.96 dB of time-resolved relative intensity squeezing with 50 nanosecond pulses at 1 MHz repetition rate. (-1.34 dB corrected for loss).

  17. Time-resolved detection of relative intensity squeezed nanosecond pulses in a Rb87 vapor

    Agha, Imad H; Glorieux, Quentin; Coudreau, Thomas; Grangier, Philippe; Messin, Gaetan


    We present theoretical and experimental results on the generation and detection of pulsed, relative-intensity squeezed light in a hot Rb87 vapor. The intensity noise correlations between a pulsed probe beam and its conjugate, generated through nearly-degenerate four-wave mixing in a double-lambda system, are studied numerically and measured experimentally via time-resolved balanced detection. We predict and observe about -1 dB of time-resolved relative intensity squeezing with 50 nanosecond pulses at 1 MHz repetition rate. (-1.34 dB corrected for loss).

  18. Study of Pt-Rh/CeO2-ZrO2-MxOy (M = Y, La)/Al2O3 three-way catalysts

    Jiaxiu, Guo; Zhonghua, Shi; Dongdong, Wu; Huaqiang, Yin; Maochu, Gong; Yaoqiang, Chen


    CeO2-ZrO2-MxOy (M = Y; La) mixed oxides, prepared by co-precipitation method and characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Raman spectra (RM) and oxygen pulse reaction, were comparatively investigated to elucidate the combinational effects of Y and/or La oxide promoters on the catalytic activity and anti-aging performance of monolithic cordierite honeycomb catalysts with low Pt and Rh content. The catalytic activities, water-gas shift (WGS) and steam reforming reaction (SR) were studied under a simulated gas mixture. The catalysts were also characterized by H2-temperature-programmed reduction (H2-TPR) and O2-temperature-programmed desorption (O2-TPD). The results showed that the prepared CeO2-ZrO2-MxOy oxides have a face-centered cubic fluorite structure and are nanosize. La3+ ions can significantly improve thermal stability and efficiently retard CeO2-ZrO2 crystal sintering and growth. Doped CeO2-ZrO2 with Y3+ and La3+ has 105 and 60 m2/g surface area and 460 and 390 μmol/g OSC before and after aging. The T50 of fresh Pt-Rh/CZYL/LA is 170 °C for CO, 222 °C for C3H8 and 189 °C for NO, and shift to 205, 262 and 228 °C after hydrothermal aging, which are better than those of Pt-Rh/CZY/LA or Pt-Rh/CZL/LA. WGS and SR are relate to the OSC of oxygen storage materials and absorbed oxygen species on the catalyst surface and affect the three-way catalytic activities of catalysts. The reductive property of noble metals and the dissociatively adsorbed O2 on the surface of catalysts are closely related to the catalytic activities.

  19. Pulse on Pulse

    Schmidt, Ulrik; Carlson, Merete


    Pulse on Pulse” investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006-) by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy...... and pulsating ‘room’. Hence, the visitors in Pulse Room are invited into a complex scenario that continuously oscillates between various aspects of signification (the light bulbs representing individual lives; the pulse itself as the symbolic ‘rhythm of life’) and instants of pure material processuality...... a multilayered sense of time and space that is central to the sensory experience of Pulse Room as a whole. Pulse Room is, at the very same time, an anthropomorfized archive of a past intimacy and an all-encompassing immersive environment modulating continuously in real space-time....

  20. Phase Relations of the CaO-SiO2-Nd2O3 System and the Implication for Rare Earths Recycling

    Le, Thu Hoai; Malfliet, Annelies; Blanpain, Bart; Guo, Muxing


    CaO-SiO2-Nd2O3 slags were equilibrated at 1773 K and 1873 K (1500 °C and 1600 °C) for 24 hours in Ar, and quenched in water to determine the operative phase relations. The composition and crystallinity of the phases in equilibrium were determined by EPMA-WDS and EBSD, respectively. Based on these analyses, the liquid stability region was accurately determined, and a large part of the isothermal section of the phase diagram was constructed. Data resulting from this work can be used to generate a thermodynamic database for rare-earth oxide-containing systems and to support further investigation on separation of rare earths from metallurgical slags or other residues through high-temperature processing.

  1. Study of the picosecond laser damage in HfO2/SiO2-based thin-film coatings in vacuum

    Kozlov, A. A.; Papernov, S.; Oliver, J. B.; Rigatti, A.; Taylor, B.; Charles, B.; Smith, C.


    The laser damage thresholds of various HfO2/SiO2-based thin film coatings, including multilayer dielectric (MLD) gratings and high reflectors of different designs, prepared by E-beam and Plasma Ion Assisted Deposition (PIAD) methods, were investigated in vacuum, dry nitrogen, and after air-vacuum cycling. Single and multiple-pulse damage thresholds and their pulse-length scaling in the range of 0.6 to 100 ps were measured using a vacuum damage test station operated at 1053nm. The E-beam deposited high reflectors showed higher damage thresholds with square-root pulse-length scaling, as compared to PIAD coatings, which typically show slower power scaling. The former coatings appeared to be not affected by air/vacuum cycling, contrary to PIAD mirrors and MLD gratings. The relation between 1-on-1 and N-on-1 damage thresholds was found dependent on coating design and deposition methods.

  2. Purification of O2-sensitive metalloproteins.

    Echavarri-Erasun, Carlos; Arragain, Simon; Rubio, Luis M


    The most dependable factor to perform successful biochemical experiments in an O2-free environment is the experience required to set up an efficient laboratory, to properly manipulate samples, to anticipate potential O2-related problems, and to maintain the complex laboratory setup operative. There is a long list of O2-related issues that may ruin your experiments. We provide here a guide to minimize these risks.

  3. Electrocatalytic Properties of Pt-TiO2 Nanotubes Electrode Prepared by Pulse Electrodeposition Method%脉冲电沉积法制备Pt-TiO2纳米管电极及其电催化性能

    孟祥龙; 李洪义; 王金淑


    Platinum (Pt) nanoflower structure was electrodeposited on the surface of the aligned TiO2 nano-tube, which was fabricated by anodic oxidation on titanium samples. The obtained electrode was characterized by XRD and SEM. The experiment results show that Pt is dispersed on the TiO2 nanotubes in the shape of nanoflowers, particle size is 25. 6 nm based on the calculations of XRD. Compared with pure Pt and clean TiO2 nanotube arrays, the hybrid electrodes' electrocatalytic activity for methanol oxidation has been greatly improved. The oxidation current densities on Pt-TiO2 nanotubes electrode are 40 times higher than that of pure platinum electrode. The hybrid electrode shows promising applications in many fields, such as direct methanol fuel cell, treatment of polluted water and so on.%采用阳极氧化法在高纯钛片上原位组装TiO2纳米管阵列,然后用脉冲电沉积方法将Pt沉积到TiO2纳米管阵列上,制备出Pt-TiO2纳米管电极.利用XRD和SEM对所获电极的微观结构和形貌进行表征,结果表明,Pt纳米颗粒以花簇状分散在TiO2纳米管上,晶粒大小约为25.6 nm.对甲醇的电催化性能的研究结果表明,脉冲电沉积制得的Pt-TiO2纳米管电极比TiO2纳米管电极和纯Pt片电极具有更高的电催化活性,是Pt电极的40多倍.

  4. PLD prepared nanostructured Pt-CeO2 thin films containing ionic platinum

    Vorokhta, M.; Khalakhan, I.; Matolínová, I.; Nováková, J.; Haviar, S.; Lančok, J.; Novotný, M.; Yoshikawa, H.; Matolín, V.


    The composition of nanostructured Pt-CeO2 films on graphite substrates prepared by pulsed laser deposition has been investigated by means of hard X-ray photoelectron spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, and atomic force microscopy. The influence of morphology of the graphite substrates was investigated with respect to the relative concentrations of ionic and metallic Pt species in the films. It was found that the degree of Pt2+ enrichment is directly related to the surface morphology of graphite substrates. In particular, the deposition of Pt-CeO2 films on rough graphite substrate etched in oxygen plasma yielded nanostructured Pt-CeO2 catalyst films with high surface area and high Pt2+/Pt0 ratio. The presented results demonstrate that PLD is a suitable method for the preparation of thin Pt-CeO2 catalyst films for fuel cell applications.

  5. Measuring a 10,000-fold enhancement of singlet molecular oxygen (1O2*) concentration on illuminated ice relative to the corresponding liquid solution

    Bower, Jonathan P.; Anastasio, Cort


    Much attention has focused on the highly reactive hydroxyl radical in the oxidation of trace organic compounds on snow and ice (and subsequent release of volatile organics to the atmospheric boundary layer) but other oxidants are likely also important in this processing. Here we examine the ice chemistry of singlet molecular oxygen (1O2*), which can be significant in atmospheric water drops but has not been examined in ice or snow. To examine 1O2* on ice we illuminate laboratory ices containing Rose Bengal (RB) as the source of 1O2*, furfuryl alcohol (FFA) as the probe, and Na2SO4 to control the total solute concentration. We find that the 1O2*-mediated loss of FFA (and, thus, the 1O2* concentration) is up to 11,000 times greater on ice than in the equivalent liquid sample at the same photon flux. We attribute this large increase in the 1O2* steady-state concentration to the freeze-concentration of solutes into liquid-like regions (LLRs) in/on ice: compared to the initial solution, in the LLRs of ice the sources for 1O2* are highly concentrated, while the concentration of the dominant sink for 1O2* (i.e., water) remains largely unchanged. Similar to results expected in liquid solution, rates of FFA loss in ice depend on both the initial sensitizer concentration and temperature, providing evidence that these reactions occur in LLRs. However, we find that the enhancement in 1O2* concentrations on ice does not follow predictions from freezing-point depression, likely because experiments were conducted below the eutectic temperature for sodium sulfate, where all of the salt should have precipitated. We also explore a method for separating 1O2* and rad OH contributions to FFA oxidation in laboratory ices and show its application to two natural snow samples. We find that 1O2* concentrations in these snows are approximately 100 times higher than observed in polluted, mid-latitude fog waters, showing that the enhancement of 1O2* on ice is environmentally relevant and that

  6. Characterization of TiO2–MnO2 composite electrodes synthesized using spark plasma sintering technique

    Tshephe, TS


    Full Text Available and electrochemical stability of the resulting materials were investigated. Relative densities of 99.33% and 98.49% were obtained for 90TiO2–10MnO2 and 80TiO2–10MnO2 when ball was incorporated. The 90TiO2–10MnO2 powder mixed with balls had its Vickers hardness value...

  7. On the importance of the phase distribution and acidity of VOx-ZrO2-SO4-sepiolite catalysts for the NH3-SCR process in relation to biomass fueled power plants

    Due-Hansen, Johannes; Rasmussen, Søren Birk; Riisager, Anders

    A series of V2O5-ZrO2-SO42- - sepiolite mixtures were extruded, calcined and characterized. NH3-SCR activity was related to the phase distribution of the agglomerant and active VOX-ZrO2-SO42- phase, as well as the acidity of the composite material. Electrophoretic migration results showed...... that the addition of sepiolite to zirconia had effect on the quantity of zirconia present at the support’s surface, both strongly decreasing the molar fraction of zirconia at the surface, and altering the electrophoretic properties of the mixtures. Addition of extra ammonia sulfate eliminate both effects, and thus...... facilitate the production of a sepiolite-based conformed catalyst based on VOx-ZrO2-SO42-, which has been shown to be more resistant to the industrially implemented V2O5-WO3/TiO2 catalyst....

  8. Effect of exogenous H2O2 on antioxidant enzymes of Brassica juncea L. seedlings in relation to 24-epibrassinolide under chilling stress.

    Kumar, Manish; Sirhindi, Geetika; Bhardwaj, Renu; Kumar, Sandeep; Jain, Gagandeep


    Hydrogen peroxide is most stable molecule among reactive oxygen species, which play a vital role in growth and development of plant as signaling molecule at low concentration in response to various abiotic and biotic stresses. Exogenous application of H2O2 is known to induce chilling tolerance in plants. Brassinosteroids are plant steroid hormones known for their anti-stress properties. In this study, effect of exogenous H2O2 on antioxidant defense system of Brassica juncea L. seedlings was investigated in 24-epibrassinolide (24-EBL) treated and untreated seedlings under chilling stress. The surface sterilized seeds of B. juncea L. were germinated in petriplates containing different concentrations of H2O2 alone and in combination with 10(-8) M 24-EBL. Chilling treatment (4 degrees C) was given to 10-days old seedlings grown in different treatments for 6 h daily up to 3 days. 24 h recovery period was given to chilling treated seedlings by placing at 25 degrees C + 2 degrees C and harvested for antioxidant enzymes on 14th day after sowing (DAS). Treatment of 24-EBL in combination with H2O2 (15 and 20 mM) helped in reducing the toxicity of seed and seedlings due to H2O2 exposure on their germination rate, shoot and root length respectively. 24-EBL treatment at seed and seedling stage helped in alleviating the toxic effect of H2O2 through antioxidant defense system by increasing the activities of various enzymes involved in antioxidant defense system such as catalase (CAT, E.C., ascorbate peroxidase (APOX, E.C., and superoxide dismutase (SOD, E.C. In conclusion, exogenous pretreatment of H2O2 to seeds of B. juncea L. adapted the seedlings to tolerate chilling stress, which was further ameliorated in combination of H2O2 with 24-EBL.

  9. Altered susceptibility to the bactericidal effect of photocatalytic oxidation by TiO2 is related to colistin resistance development in Acinetobacter baumannii.

    Tseng, Chun-Chieh; Tsai, Yun-Hsuan; Hu, Anren; Liou, Je-Wen; Chang, Kai-Chih; Chang, Hsin-Hou


    Multidrug-resistant Acinetobacter baumannii is a well-documented pathogen associated with hospital-acquired infections. In addition to multidrug resistance, A. baumannii can also become resistant to colistin, the antibiotic treatment of last resort, by the loss of the lipopolysaccharide from its outer membrane. Here, we demonstrate that the development of colistin resistance also increases the resistance of A. baumannii to titanium dioxide (TiO2) photocatalysis. Both colistin-sensitive A. baumannii (CSAB) and colistin-resistant A. baumannii (CRAB) were inactivated by TiO2 when irradiated by ultraviolet A (UV-A). The resistance of CRAB to TiO2 photocatalysis was 1.5 times higher than that of CSAB, as determined by either culture assay or quantification of leaked proteins after photocatalysis (p resistance of CRAB may be associated with a lack of sensitive targets and oxidative enzymes. This hypothesis was confirmed by antimicrobial assays with 25 mM hydrogen peroxide (H2O2) and 1.07 mM sodium hypochlorite (NaClO). CRAB was significantly more resistant to H2O2 and NaClO treatment than CSAB (p experiment. Therefore, the antibiotic resistance profiles of bacterial strains should be considered before the use of strains as indicators to represent sanitary quality after TiO2 photocatalysis.

  10. Plasma surface modified TiO2 nanoparticles: improved photocatalytic oxidation of gaseous m-xylene.

    Sumitsawan, Sulak; Cho, Jai; Sattler, Melanie L; Timmons, Richard B


    Titanium dioxide (TiO(2)) is a preferred catalyst for photocatalytic oxidation of many air pollutants. In an effort to enhance its photocatalytic activity, TiO(2) was modified by pulsed plasma treatment. In this work, TiO(2) nanoparticles, coated on a glass plate, were treated with a plasma discharge of hexafluoropropylene oxide (HFPO) gas. By appropriate adjustment of discharge conditions, it was discovered that the TiO(2) particles can be either directly fluorinated (Ti-F) or coated with thin perfluorocarbon films (C-F). Specifically, under relatively high power input, the plasma deposition process favored direct surface fluorination. The extent of Ti-F formation increased with increasing power input. In contrast, at lower average power inputs, perfluorocarbon films are deposited on the surface of the TiO(2) particles. The plasma surface modified TiO(2) nanoparticles were subsequently employed as catalysts in the photocatalytic oxidation of m-xylene in air, as carried out inside a batch reactor with closed loop constant gas circulation. Both types of modified TiO(2) were significantly more catalytically active than that of the unmodified particles. For example, the rate constant of m-xylene degradation was increased from 0.012 min(-1) with untreated TiO(2) to 0.074 min(-1) with fluorinated TiO(2). Although it is not possible to provide unequivocal reasons for this increased photocatalytic activity, it is noted that the plasma surface treatment converted the TiO(2) from hydrophilic to highly hydrophobic, which would provide more facile catalyst adsorption of the xylene from the flowing air. Also, based on literature reports, the use of fluorinated TiO(2) reduces electron-hole recombination rates, thus increasing the photocatalytic activity.

  11. Pulse on Pulse

    Schmidt, Ulrik; Carlson, Merete


    and pulsating ‘room’. Hence, the visitors in Pulse Room are invited into a complex scenario that continuously oscillates between various aspects of signification (the light bulbs representing individual lives; the pulse itself as the symbolic ‘rhythm of life’) and instants of pure material processuality......“Pulse on Pulse” investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006-) by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy...... of the visitor’s beating heart to the blink of a fragile light bulb, thereby transforming each light bulb into a register of individual life. But at the same time the blinking light bulbs together produce a chaotically flickering light environment composed by various layers of repetitive rhythms, a vibrant...

  12. Effect of ambient oxygen pressure on structural, optical and electrical properties of SnO2 thin films

    ZHAO Songqing; ZHOU Yueliang; WANG Shufang; ZHAO Kun; HAN Peng


    Polycrystalline SnO2 thin films were deposited on sapphire substrates at 450℃ under different ambient oxygen pressures by pulsed laser deposition technique. The effect of ambient oxygen pressure on the structural, optical and electrical properties of SnO2 thin films was studied. X-ray diffraction and Hall measurements show that increasing the ambient oxygen pressure can improve crystallization of the films and decrease resistivity of the films. A violet emission peak centered at 409 nm was observed from photoluminescence measurements for SnO2 films under deposition ambient oxygen pressure above 5 Pa, which is related to the improvement of crystalline of the films.

  13. Study on Properties of Composite Oxides TiO2/SiO2%复合氧化物TiO2/SiO2性质研究

    周亚松; 姜国伟


    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-EmmettTeller method), TEM(transmission electron microscopy), SEM(scanning electron microscopy), XRD(X-ray diffraction) 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 thermal 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 BrSnsted acidity sites. 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.

  14. A novel composite of SiO2-coated graphene oxide and molecularly imprinted polymers for electrochemical sensing dopamine.

    Zeng, Yanbo; Zhou, Ying; Kong, Lei; Zhou, Tianshu; Shi, Guoyue


    A novel imprinting route based on graphene oxide (GO) was proposed for preparing a composite of SiO2-coated GO and molecularly imprinted polymers (GO/SiO2-MIPs). In this route, SiO2-coated GO sheets were synthesized in a water-alcohol mixture with sol-gel technique. Prior to polymerization, the vinyl groups were introduced onto the surface of GO/SiO2 through chemical modification with γ-methacryloxypropyl trimethoxysilane (γ-MAPS), which can direct the selective polymerization on the GO/SiO2 surface. Then a novel composite of GO/SiO2-MIPs was successfully obtained by the copolymerization in presence of vinyl groups functionalized GO/SiO2, dopamine (DA), methacrylic acid and ethylene glycol dimethacrylate. The GO/SiO2-MIPs composite was characterized by FTIR, TGA, Raman spectroscopy, SEM and AFM. The properties such as special binding, adsorption dynamics and selective recognition ability using differential pulse voltammetry (DPV) were evaluated. The DPV current response of GO/SiO2-MIPs sensor was nearly 3.2 times that of the non-imprinted polymers (NIPs). In addition, the GO/SiO2-MIPs sensor could recognize DA from its relatively similar molecules of norepinephrine and epinephrine, while the sensors based on GO/SiO2-NIPs and vinyl groups functionalized GO/SiO2 did not have the ability. The GO/SiO2-MIPs sensor had a wide linear range over DA concentration from 5.0 × 10(-8) to 1.6 × 10(-4)M with a detection limit of 3.0 × 10(-8)M (S/N=3). The sensor based on this novel imprinted composite was applied to the determination of DA in injections and human urine samples with satisfactory results.

  15. Relative Phase Dependence of Double Ionization in a Synthesized Laser Pulse

    WANG Yuan-Sheng; XIA Chang-Long; GUO Jing; LIU Xue-Shen


    @@ We investigate the double ionization process of a three-dimensional model atom interacting with a synthesized laser pulse and explore the mechanism of non-sequential double ionization varying with the value of relative phase.The result shows that the recollision probability decreases when the value of the relative phase increases.The momentum spectra of electrons in the sequential ionization region are also illustrated.

  16. Diurnal O2 and carbohydrate levels in wheat kernels during embryony.

    Carman, John G; Bishop, Deborah L


    In vitro zygotic and somatic embryogenesis procedures for wheat have been improved by simulating in ovulo nutritional, hormonal and dissolved oxygen (dO2) conditions. However, diurnal fluctuations in these conditions during early embryony are not well characterized. In this study, dO2 and water-soluble carbohydrate Levels in wheat kernels were determined after 8 h of light and 8 h of dark at approximately 6, 12 and 18 day post anthesis (DPA). Clark style O2 microelectrodes, having a tip diameter of approximately 115 microm, were inserted into intact kernels immediately distil to the developing embryo, and dO2 levels were recorded at 50 microm intervals into the center of kernels. High-performance anion exchange chromatography with pulsed amperometric detection was used to quantify carbohydrate levels in endosperm sap. dO2 levels in the chlorophyllous layer of the pericarp reached 190 mmoLm(-3) during the day, which probably represents, because of photosynthesis, a supersaturated O2 condition relative to the external environment (21% O2). At the embryo surface, dO2 levels at 6 DPA ranged from 135 to 170 mmolm(-3). At 12 and 18 DPA, dO2 levels at the embryo axis ranged from 100 to 150mmolm(-3). At all three stages, dO2 levels in the center of the endosperm were below 13 mmolm(-3). Extreme fluctuations in carbohydrate levels were observed diurnally during rapid seed fill (12DPA). Levels of sucrose and short-chain fructans were much higher during the day than during the night. In contrast, fructose, glucose, and myo-inositol levels were much higher during the night than during the day. By 18DPA (hard dough stage), carbohydrate levels tended to be similar during the day and night. These dynamic fluctuations may assist in regulating embryony in ovulo, and their simulation might improve the development of somatic and zygotic embryos in vitro.

  17. Vitrified bottom ash slag from municipal solid waste incinerators - Phase relations of CaO-SiO2-Na20 oxide system

    Zhang, Z.; Xiao, Y.; Yang, Y.; Boom, R.; Voncken, J.H.L.


    Vitrification is considered to be an attractive technology for bottom ash treatment because it destroys the hazardous organics, contributes to immobilization of the heavy metals, and additionally it reduces drastically the volume. The main components of the vitrified bottom ash slag are SiO2 , CaO,

  18. Vitrified bottom ash slag from municipal solid waste incinerators - Phase relations of CaO-SiO2-Na20 oxide system

    Zhang, Z.; Xiao, Y.; Yang, Y.; Boom, R.; Voncken, J.H.L.


    Vitrification is considered to be an attractive technology for bottom ash treatment because it destroys the hazardous organics, contributes to immobilization of the heavy metals, and additionally it reduces drastically the volume. The main components of the vitrified bottom ash slag are SiO2 , CaO,

  19. SiO2 and TiO2 nanoparticles synergistically trigger macrophage inflammatory responses.

    Tsugita, Misato; Morimoto, Nobuyuki; Nakayama, Masafumi


    Silicon dioxide (SiO2) nanoparticles (NPs) and titanium dioxide (TiO2) NPs are the most widely used inorganic nanomaterials. Although the individual toxicities of SiO2 and TiO2 NPs have been extensively studied, the combined toxicity of these NPs is much less understood. In this study, we observed unexpected and drastic activation of the caspase-1 inflammasome and production of IL-1β in mouse bone marrow-derived macrophages stimulated simultaneously with SiO2 and TiO2 NPs at concentrations at which these NPs individually do not cause macrophage activation. Consistent with this, marked lung inflammation was observed in mice treated intratracheally with both SiO2 and TiO2 NPs. In macrophages, SiO2 NPs localized in lysosomes and TiO2 NPs did not; while only TiO2 NPs produced ROS, suggesting that these NPs induce distinct cellular damage leading to caspase-1 inflammasome activation. Intriguingly, dynamic light scattering measurements revealed that, although individual SiO2 and TiO2 NPs immediately aggregated to be micrometer size, the mixture of these NPs formed a stable and relatively monodisperse complex with a size of ~250 nm in the presence of divalent cations. Taken together, these results suggest that SiO2 and TiO2 NPs synergistically induce macrophage inflammatory responses and subsequent lung inflammation. Thus, we propose that it is important to assess the synergistic toxicity of various combinations of nanomaterials.

  20. Low temperature complete combustion of dilute propane over Mn-doped ZrO2 (cubic) catalysts

    Vasant R Choudhary; Subhabrata Banerjee; Suryakant G Pataskar


    Combustion of dilute propane (0.9 mol %) over Mn-doped ZrO2 catalysts prepared using different precipitating agents (viz. TMAOH, TEAOH, TPAOH, TBAOH and NH4OH), having different Mn/Zr ratios (0.05 - 0.67) and calcined at different temperatures (500-800°C), has been thoroughly investigated at different temperatures (300-500°C) and space velocities (25,000-100,000 cm3 g-1 h-1) for controlling propane emissions from LPG-fuelled vehicles. Mn-doped ZrO2 catalyst shows high propane combustion activity, particularly when its ZrO2 is in the cubic form, when its Mn/Zr ratio is close to 0.2 and when it is prepared using TMAOH as a precipitating agent and calcined at 500-600°C. Pulse reaction of propane in the absence of free-O2 over Mn-doped ZrO2 (cubic) and Mn-impregnated ZrO2 (monoclinic) catalysts has also been investigated for studying the relative reactivity and mobility of the lattice oxygen of the two catalysts. Both reactivity and mobility of the lattice oxygen of Mn-doped ZrO2 are found to be much higher than that of Mnimpregnated ZrO2. Propane combustion over Mn-doped ZrO2 catalyst involves a redox mechanism.

  1. Nanocrystalline TiO2/SnO2 heterostructures for gas sensing.

    Lyson-Sypien, Barbara; Kusior, Anna; Rekas, Mieczylaw; Zukrowski, Jan; Gajewska, Marta; Michalow-Mauke, Katarzyna; Graule, Thomas; Radecka, Marta; Zakrzewska, Katarzyna


    The aim of this research is to study the role of nanocrystalline TiO2/SnO2 n-n heterojunctions for hydrogen sensing. Nanopowders of pure SnO2, 90 mol % SnO2/10 mol % TiO2, 10 mol % SnO2/90 mol % TiO2 and pure TiO2 have been obtained using flame spray synthesis (FSS). The samples have been characterized by BET, XRD, SEM, HR-TEM, Mössbauer effect and impedance spectroscopy. Gas-sensing experiments have been performed for H2 concentrations of 1-3000 ppm at 200-400 °C. The nanomaterials are well-crystallized, anatase TiO2, rutile TiO2 and cassiterite SnO2 polymorphic forms are present depending on the chemical composition of the powders. The crystallite sizes from XRD peak analysis are within the range of 3-27 nm. Tin exhibits only the oxidation state 4+. The H2 detection threshold for the studied TiO2/SnO2 heterostructures is lower than 1 ppm especially in the case of SnO2-rich samples. The recovery time of SnO2-based heterostructures, despite their large responses over the whole measuring range, is much longer than that of TiO2-rich samples at higher H2 flows. TiO2/SnO2 heterostructures can be intentionally modified for the improved H2 detection within both the small (1-50 ppm) and the large (50-3000 ppm) concentration range. The temperature Tmax at which the semiconducting behavior begins to prevail upon water desorption/oxygen adsorption depends on the TiO2/SnO2 composition. The electrical resistance of sensing materials exhibits a power-law dependence on the H2 partial pressure. This allows us to draw a conclusion about the first step in the gas sensing mechanism related to the adsorption of oxygen ions at the surface of nanomaterials.

  2. Nanocrystalline TiO2/SnO2 heterostructures for gas sensing

    Kusior, Anna; Rekas, Mieczylaw; Zukrowski, Jan; Gajewska, Marta; Michalow-Mauke, Katarzyna; Graule, Thomas; Radecka, Marta; Zakrzewska, Katarzyna


    The aim of this research is to study the role of nanocrystalline TiO2/SnO2 n–n heterojunctions for hydrogen sensing. Nanopowders of pure SnO2, 90 mol % SnO2/10 mol % TiO2, 10 mol % SnO2/90 mol % TiO2 and pure TiO2 have been obtained using flame spray synthesis (FSS). The samples have been characterized by BET, XRD, SEM, HR-TEM, Mössbauer effect and impedance spectroscopy. Gas-sensing experiments have been performed for H2 concentrations of 1–3000 ppm at 200–400 °C. The nanomaterials are well-crystallized, anatase TiO2, rutile TiO2 and cassiterite SnO2 polymorphic forms are present depending on the chemical composition of the powders. The crystallite sizes from XRD peak analysis are within the range of 3–27 nm. Tin exhibits only the oxidation state 4+. The H2 detection threshold for the studied TiO2/SnO2 heterostructures is lower than 1 ppm especially in the case of SnO2-rich samples. The recovery time of SnO2-based heterostructures, despite their large responses over the whole measuring range, is much longer than that of TiO2-rich samples at higher H2 flows. TiO2/SnO2 heterostructures can be intentionally modified for the improved H2 detection within both the small (1–50 ppm) and the large (50–3000 ppm) concentration range. The temperature T max at which the semiconducting behavior begins to prevail upon water desorption/oxygen adsorption depends on the TiO2/SnO2 composition. The electrical resistance of sensing materials exhibits a power-law dependence on the H2 partial pressure. This allows us to draw a conclusion about the first step in the gas sensing mechanism related to the adsorption of oxygen ions at the surface of nanomaterials. PMID:28144570

  3. Relatively Selective Production of the Simplest Criegee Intermediate in a CH4/O2 Electric Discharge: Kinetic Analysis of a Plausible Mechanism.

    Nguyen, Thanh Lam; McCarthy, Michael C; Stanton, John F


    High -accuracy coupled cluster methods in combination with microcanonical semiclassical transition state theory are used to investigate a plausible formation mechanism of the simplest Criegee intermediate in a CH4/O2 discharge experiment. Our results suggest that the Criegee intermediate is produced in a three-step process: (i) production of methyl radical by cleavage of a C-H bond of CH4; (ii) association of methyl radical with molecular oxygen to form a vibrationally excited methyl peroxy, which is in a rapid microequilibrium with the reactants; and finally, (iii) H-abstraction of CH3OO by O2, which results in the formation of cool CH2OO, which has insufficient internal energy to rearrange to dioxirane.

  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. Nano-regime Length Scales Extracted from the First Sharp Diffraction Peak in Non-crystalline SiO2 and Related Materials: Device Applications

    Phillips James


    Full Text Available Abstract This paper distinguishes between two different scales of medium range order, MRO, in non-crystalline SiO2: (1 the first is ~0.4 to 0.5 nm and is obtained from the position of the first sharp diffraction peak, FSDP, in the X-ray diffraction structure factor, S(Q, and (2 the second is ~1 nm and is calculated from the FSDP full-width-at-half-maximum FWHM. Many-electron calculations yield Si–O third- and O–O fourth-nearest-neighbor bonding distances in the same 0.4–0.5 nm MRO regime. These derive from the availability of empty Si dπ orbitals for back-donation from occupied O pπ orbitals yielding narrow symmetry determined distributions of third neighbor Si–O, and fourth neighbor O–O distances. These are segments of six member rings contributing to connected six-member rings with ~1 nm length scale within the MRO regime. The unique properties of non-crystalline SiO2 are explained by the encapsulation of six-member ring clusters by five- and seven-member rings on average in a compliant hard-soft nano-scaled inhomogeneous network. This network structure minimizes macroscopic strain, reducing intrinsic bonding defects as well as defect precursors. This inhomogeneous CRN is enabling for applications including thermally grown ~1.5 nm SiO2 layers for Si field effect transistor devices to optical components with centimeter dimensions. There are qualitatively similar length scales in nano-crystalline HfO2 and phase separated Hf silicates based on the primitive unit cell, rather than a ring structure. Hf oxide dielectrics have recently been used as replacement dielectrics for a new generation of Si and Si/Ge devices heralding a transition into nano-scale circuits and systems on a Si chip.

  6. Effects of biased irradiation on charge trapping in HfO2 dielectric thin films

    Mu, Yifei; Zhao, Ce Zhou; Lu, Qifeng; Zhao, Chun; Qi, Yanfei; Lam, Sang; Mitrovic, Ivona Z.; Taylor, Stephen; Chalker, Paul R.


    This paper reports the low-dose-rate radiation response of Al-HfO2/SiO2-Si MOS devices, in which the gate dielectric was formed by atomic layer deposition (ALD) with 5-nm equivalent oxide thickness. The degradation of the devices was characterized by a pulse capacitance-voltage (CV) and on-site radiation response technique under continuous gamma (γ) ray exposure at a relatively low dose rate of 0.116 rad (HfO2)/s. Compared with conventional CV measurements, the proposed measurements extract significant variations of flat-band voltage shift of the hafnium based MOS devices. The large flat-band voltage shift is mainly attributed to the radiation-induced oxide trapped charges, which are not readily compensated by bias-induced charges produced over the measurement timescales (for timescales less than 5 ms). A negative flat-band voltage shift up to -1.02 V was observed under a positive biased irradiation with the total dose up to 40 krad (HfO2) and with the electric field of 0.5 MV/cm. This is attributed to net positive charge generation in the HfO2 oxide layer. The generated charges are transported towards the HfO2/SiO2 interface, and then form effective trapped holes in the HfO2. Similarly, a positive flat-band voltage shift up to 1.1 V was observed from irradiation under negative bias with an electric field of -0.5 MV/cm. The positive shift is mainly due to the accumulation of trapped electrons. Analyses of the experimental results suggest that both hole and electron trapping can dominate the radiation response performance of the HfO2-based MOS devices depending upon the applied bias. It was also found there was no distinct border traps with irradiation in all cases.

  7. Thermoelectric Properties of Self Assemble TiO2/SnO2 Nanocomposites

    Dynys, Fred; Sayir, Ali; Sehirlioglu, Alp


    Recent advances in improving efficiency of thermoelectric materials are linked to nanotechnology. Thermodynamically driven spinodal decomposition was utilized to synthesize bulk nanocomposites. TiO2/SnO2 system exhibits a large spinodal region, ranging from 15 to 85 mole % TiO2. The phase separated microstructures are stable up to 1400 C. Semiconducting TiO2/SnO2 powders were synthesized by solid state reaction between TiO2 and SnO2. High density samples were fabricated by pressureless sintering. Self assemble nanocomposites were achieved by annealing at 1000 to 1350 C. X-ray diffraction reveal phase separation of (Ti(x)Sn(1-x))O2 type phases. The TiO2/SnO2 nanocomposites exhibit n-type behavior; a power factor of 70 (mu)W/m sq K at 1000 C has been achieved with penta-valent doping. Seebeck, thermal conductivity, electrical resistivity and microstructure will be discussed in relation to composition and doping.

  8. Thermoelectric Properties of Self Assembled TiO2/SnO2 Nanocomposites

    Dynys, Fred; Sayir, Ali; Sehirlioglu, Alp


    Recent advances in improving efficiency of thermoelectric materials are linked to nanotechnology. Thermodynamically driven spinodal decomposition was utilized to synthesize bulk nanocomposites. TiO2/SnO2 system exhibits a large spinodal region, ranging from 15 to 85 mole % TiO2. The phase separated microstructures are stable up to 1400 C. Semiconducting TiO2/SnO2 powders were synthesized by solid state reaction between TiO2 and SnO2. High density samples were fabricated by pressureless sintering. Self assemble nanocomposites were achieved by annealing at 1000 to 1350 C. X-ray diffraction reveal phase separation of (Ti(x)Sn(1-x))O2 type phases. The TiO2/SnO2 nanocomposites exhibit n-type behavior; a power factor of 70 W/mK2 at 1000 C has been achieved with penta-valent doping. Seebeck, thermal conductivity, electrical resistivity and microstructure will be discussed in relation to composition and doping.

  9. Ultrathin Hf0.5Zr0.5O2 Ferroelectric Films on Si.

    Chernikova, Anna; Kozodaev, Maksim; Markeev, Andrei; Negrov, Dmitrii; Spiridonov, Maksim; Zarubin, Sergei; Bak, Ohheum; Buragohain, Pratyush; Lu, Haidong; Suvorova, Elena; Gruverman, Alexei; Zenkevich, Andrei


    Because of their immense scalability and manufacturability potential, the HfO2-based ferroelectric films attract significant attention as strong candidates for application in ferroelectric memories and related electronic devices. Here, we report the ferroelectric behavior of ultrathin Hf0.5Zr0.5O2 films, with the thickness of just 2.5 nm, which makes them suitable for use in ferroelectric tunnel junctions, thereby further expanding the area of their practical application. Transmission electron microscopy and electron diffraction analysis of the films grown on highly doped Si substrates confirms formation of the fully crystalline non-centrosymmetric orthorhombic phase responsible for ferroelectricity in Hf0.5Zr0.5O2. Piezoresponse force microscopy and pulsed switching testing performed on the deposited top TiN electrodes provide further evidence of the ferroelectric behavior of the Hf0.5Zr0.5O2 films. The electronic band lineup at the top TiN/Hf0.5Zr0.5O2 interface and band bending at the adjacent n(+)-Si bottom layer attributed to the polarization charges in Hf0.5Zr0.5O2 have been determined using in situ X-ray photoelectron spectroscopy analysis. The obtained results represent a significant step toward the experimental implementation of Si-based ferroelectric tunnel junctions.

  10. Nano Au/TiO2 hollow microsphere membranes for the improved sensitivity of detecting specific DNA sequences related to transgenes in transgenic plants


    Gold nanoparticles (nano Au)/titanium dioxide (TiO2) hollow microsphere membranes were prepared on the carbon paste electrode (CPE) for enhancing the sensitivity of DNA hybridization detection. The immobilization of nano Au and TiO2 microsphere was investigated with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The hybridization events were monitored with EIS us-ing [Fe(CN)6]3-/4- as indicator. The sequence-specific DNA of the 35S promoter from cauliflower mosaic virus (CaMV35S) gene was detected with this DNA electrochemical sensor. The dynamic detection range was from 1.0×10-12 to 1.0×10-8 mol/L DNA and a detection limit of 2.3×10-13 mol/L could be ob-tained. The polymerase chain reaction (PCR) amplification of the terminator of nopaline synthase (NOS) gene from the real sample of a kind of transgenic soybean was also satisfactorily detected.

  11. An XRD and Electron Diffraction Study of Cristobalite-Related Phases in the NaAlO 2-NaAlSiO 4System

    Thompson, John G.; Melnitchenko, Alexandra; Palethorpe, Stephen R.; Withers, Ray L.


    A detailed study of the sodium aluminate-carnegieite system (Na2-xAl2-xSixO4, 0≤x≤1) at temperatures between 800 and 1300°C has revealed five previously unreported phases. All of the new phases can be described as modulated variants of an underlyingβ-cristobalite parent structure. Atx≈0.05 theγ-NaAlO2-type structure (P41212,a=1/2ap,c=cp) (p=parent) is stabilized to room-temperature; atx≈0.2-0.45 an orthorhombic (Pbca,a=2ap,b=2bp,c=1/2cp) KGaO2-type structure is obtained, except atx≈0.35 where a new tetragonal (P41212,a=2ap,c=cp) phase is observed; atx≈0.5-0.6 a new cubic (P213,a=2ap) phase is obtained; atx≈0.7-0.9 a new orthorhombic (Pc21b,a=2ap,b=2bp,c=2cp) phase is obtained. XRD and electron diffraction data, refined unit cell dimensions, and the phase relationships at 1300°C are presented. The proposed space group symmetries are based on observed extinction conditions and constraints provided by a modulated structure description of the new phases. The materials are prepared by gel synthesis followed by solid state reaction in air.

  12. Plasma plume effects on the conductivity of amorphous-LaAlO3/SrTiO3 interfaces grown by pulsed laser deposition in O2 and Ar

    Sambri, A.; Christensen, Dennis; Trier, Felix


    Amorphous-LaAlO3/SrTiO3 interfaces exhibit metallic conductivity similar to those found for the extensively studied crystalline-LaAlO3/SrTiO3 interfaces. Here, we investigate the conductivity of the amorphous-LaAlO3/SrTiO3 interfaces grown in different pressures of O2 and Ar background gases....... During the deposition, the LaAlO3 ablation plume is also studied, in situ, by fast photography and space-resolved optical emission spectroscopy. An interesting correlation between interfacial conductivity and kinetic energy of the Al atoms in the plume is observed: to assure conducting interfaces...

  13. Time-resolved detection of relative-intensity squeezed nanosecond pulses in an {sup 87}Rb vapor

    Agha, Imad H; Giarmatzi, Christina; Grangier, Philippe; Messin, Gaetan [Laboratoire Charles Fabry, Institut d' Optique, CNRS, Universite Paris-Sud, Campus Polytechnique, 91127 Palaiseau Cedex (France); Glorieux, Quentin; Coudreau, Thomas, E-mail: [Laboratoire Materiaux et Phenomenes Quantiques, UMR 7162, Universite Paris-Diderot CNRS, 10, rue A Domon et L Duquet, 75013 Paris (France)


    We present theoretical and experimental results on the generation and detection of pulsed, relative-intensity squeezed light in a hot {sup 87}Rb vapor. The intensity noise correlations between a pulsed probe beam and its conjugate, generated through nearly degenerate four-wave mixing in a double-lambda system, are studied numerically and measured experimentally via time-resolved balanced detection. We predict and observe approximately - 1 dB of time-resolved relative-intensity squeezing with 50 ns pulses at 1 MHz repetition rate. (- 1.34 dB corrected for loss).

  14. Effect of standing-wave field distribution on femosecond laser-induced damage of HfO2/SiO2 mirror coating

    Shunli Chen; Yuan'an Zhao; Hongbo He; Manda Shao


    Single-pulse and multi-pulse damage behaviors of "standard" (with A/4 stack structure) and "modified" (with reduced standing-wave field) HfO2/SiO2 mirror coatings are investigated using a commercial 50-fs, 800-nm Tksapphire laser system. Precise morphologies of damaged sites display strikingly different features when the samples are subjected to various number of incident pulses, which are explained reasonably by the standing-wave field distribution within the coatings. Meanwhile, the single-pulse laser-induced damage threshold of the "standard" mirror is improved by about 14% while suppressing the normalized electric field intensity at the outmost interface of the HfO2 and SiO2 layers by 37%. To discuss the damage mechanism, a theoretical model based on photoionization, avalanche ionization, and decays of electrons is adopted to simulate the evolution curves of the conduction-band electron density during pulse duration.%@@ Single-pulse and multi-pulse damage behaviors of "standard"(with λ/4 stack structure) and "modified"(with reduced standing-wave field) HfO2/SiO2 mirror coatings are investigated using a commercial 50-fs,800-nm Thsapphire laser system.以Precise morphologies of damaged sites display strikingly different features when the samples are subjected to various number of incident pulses, which are explained reasonably by the standing-wave field distribution within the coatings .

  15. Thermoelectric Properties in the TiO2/SnO2 System

    Dynys, F.; Sayir, A.; Sehirlioglu, A.; Berger, M.


    Nanotechnology has provided a new interest in thermoelectric technology. A thermodynamically driven process is one approach in achieving nanostructures in bulk materials. TiO2/SnO2 system exhibits a large spinodal region with exceptional stable phase separated microstructures up to 1400 C. Fabricated TiO2/SnO2 nanocomposites exhibit n-type behavior with Seebeck coefficients greater than -300 .V/K. Composites exhibit good thermal conductance in the range of 7 to 1 W/mK. Dopant additions have not achieved high electrical conductivity (<1000 S/m). Formation of oxygen deficient composites, TixSn1-xO2-y, can change the electrical conductivity by four orders of magnitude. Achieving higher thermoelectric ZT by oxygen deficiency is being explored. Seebeck coeffcient, thermal conductivity, electrical conductance and microstructure will be discussed in relation to composition and doping.

  16. Photoelectrochemical characterization and photocatalytic properties of mesoporous TiO 2 / ZrO 2 films


    Full Text Available Optically transparent, crack-free mesoporous titania and zirconia-doped titania thin film photocatalysts were fabricated by sol-gel technique, using nonionic amphiphilic block copolymer Pluronic P123 as template. The structural and optical properties of these films were characterized using SEM, low-angle XRD, and UV/Vis spectroscopy, hexane adsorption investigation. Band gap energy and the position of flatband potentials were estimated by photoelectrochemical measurements. Enhancing of photocatalytic activity of zirconia-doped films relative to pure TiO 2 originates from an anodic shift of the valence band edge potential. Catalytic activity of mesoporous TiO 2 and TiO 2 / ZrO 2 ( 5 –50% of ZrO 2 films in the processes of Cr VI to Cr III photoreduction and 2,4-dinitroaniline photooxidation correlates with crystalline size and growth with increasing of specific surface area of the samples.

  17. Estimating exercise stroke volume from asymptotic oxygen pulse in humans.

    Whipp, B J; Higgenbotham, M B; Cobb, F C


    Noninvasive techniques have been devised to estimate cardiac output (Q) during exercise to obviate vascular cannulation. However, although these techniques are noninvasive, they are commonly not nonintrusive to subjects' spontaneous ventilation and gas-exchange responses. We hypothesized that the exercise stroke volume (SV) and, hence, Q might be accurately estimated simply from the response pattern of two standardly determined variables: O2 uptake (VO2) and heart rate (HR). Central to the theory is the demonstration that the product of Q and mixed venous O2 content is virtually constant (k) during steady-state exercise. Thus from the Fick equation, VO2 = Q.CaCO2-k, where CaCO2 is the arterial CO2 content, the O2 pulse (O2-P) equals SV.CaCO2-(k/HR). Because the arterial O2 content (CaO2) is usually relatively constant in normal subjects during exercise, O2-P should change hyperbolically with HR, asymptoting at SV.CaO2. In addition, because the asymptotic O2-P equals the slope (S) of the linear O2-HR relationship, exercise SV may be predicted as S/CaO2. We tested this prediction in 23 normal subjects who underwent a 3-min incremental cycle-ergometer test with direct determination of CaO2 and mixed venous O2 content from indwelling catheters. The predicted SV closely reflected the measured value (r = 0.80). We therefore conclude that, in normal subjects, exercise SV may be estimated simply as five times S of the linear VO2-HR relationship (where 5 is approximately 1/CaO2).

  18. Cytotoxicity Property of Nano-TiO2 Sol and Nano-TiO2 Powder

    Pingting He


    Full Text Available A homogeneous and transparent titania (TiO2 sol with nanosized anatase TiO2 particles was prepared by hydrothermal synthesis method. The transmission electron microscope and X-ray diffraction were used to characterize the structure and morphology of particulates in the TiO2 sol and purchased TiO2 powder. The results show that the homogeneous anatase crystalline phase was formed and the size of the spindle-like particle in sol was about 20 nm in width and 150 nm in average length, and the particulates of the purchased powder were globular-like about 50 nm in diameter. In addition, a consistent set of in vitro experimental protocols was used to study the effects of nano-TiO2 sol as prepared and nano-TiO2 powder on mouse peritoneal macrophage. The cytotoxicity tests in vitro indicate that, with the increasing of TiO2 sol concentration contaminated with the cells, the relative proliferation rate of macrophage cells was improved slightly after the cells contaminated for 24 h, but it reduced rapidly after contaminated for 48 h. The purchased nano-TiO2 powder inhibited the growth of the cells obviously as cultivating with macrophage both for 24 h and 48 h.

  19. Epitaxial Thin Films of Y doped HfO2

    Serrao, Claudy; Khan, Asif; Ramamoorthy, Ramesh; Salahuddin, Sayeef

    Hafnium oxide (HfO2) is one of a few metal oxides that is thermodynamically stable on silicon and silicon oxide. There has been renewed interest in HfO2 due to the recent discovery of ferroelectricity and antiferroelectricity in doped HfO2. Typical ferroelectrics - such as strontium bismuth tantalate (SBT) and lead zirconium titanate (PZT) - contain elements that easily react with silicon and silicon oxide at elevated temperatures; therefore, such ferroelectrics are not suited for device applications. Meanwhile, ferroelectric HfO2 offers promise regarding integration with silicon. The stable phase of HfO2 at room temperature is monoclinic, but HfO2 can be stabilized in the tetragonal, orthorhombic or even cubic phase by suitable doping. We stabilized Y-doped HfO2 thin films using pulsed laser deposition. The strain state can be controlled using various perovskite substrates and controlled growth conditions. We report on Y-doped HfO2 domain structures from piezo-response force microscopy (PFM) and structural parameters via X-ray reciprocal space maps (RSM). We hope this work spurs further interest in strain-tuned ferroelectricity in doped HfO2.

  20. Synthesis of an efficient heteroatom-doped carbon electro-catalyst for oxygen reduction reaction by pyrolysis of protein-rich pulse flour cooked with SiO2 nanoparticles.

    Gokhale, Rohan; Unni, Sreekuttan M; Puthusseri, Dhanya; Kurungot, Sreekumar; Ogale, Satishchandra


    Development of a highly durable, fuel-tolerant, metal-free electro-catalyst for oxygen reduction reaction (ORR) is essential for robust and cost-effective Anion Exchange Membrane Fuel Cells (AEMFCs). Herein, we report the development of a nitrogen-doped (N-doped) hierarchically porous carbon-based efficient ORR electrocatalyst from protein-rich pulses. The process involves 3D silica nanoparticle templating of the pulse flour(s) followed by their double pyrolysis. The detailed experiments are performed on gram flour (derived from chickpeas) without any in situ/ex situ addition of dopants. The N-doped porous carbon thus generated shows remarkable electrocatalytic activity towards ORR in the alkaline medium. The oxygen reduction on this material follows the desired 4-electron transfer mechanism involving the direct reduction pathway. Additionally, the synthesized carbon catalyst also exhibits good electrochemical stability and fuel tolerance. The results are also obtained and compared with the case of soybean flour having higher nitrogen content to highlight the significance of different parameters in the ORR catalyst performance.

  1. 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.

  2. Resistive switching in Ag-TiO2 contacts

    Ghenzi, N.; Stoliar, P.; Fuertes, M. C.; Marlasca, F. G.; Levy, P.


    We study the electric pulse induced resistance switching of TiO2-Ag contacts at room temperature, exploring both unipolar and bipolar switching modes. Initially we observed unipolar response. After hundred pulsing cycles the unipolar switching response vanishes but the device can still be operated in bipolar switching regime. The underlying mechanism for resistance switching is modeled in terms of formation and rupture of filament, and movement of oxygen vacancies.

  3. Understanding molecular harmonic emission at relatively long intense laser pulses: Beyond the Born-Oppenheimer approximation

    Ahmadi, H; Maghari, A


    The underlying physics behind the molecular harmonic emission in relatively long sin$^2$-like laser pulses is investigated. We numerically solved the full-dimensional electronic time-dependent Schr\\"{o}dinger equation beyond the Born-Oppenheimer approximation for simple molecular ion H$_2^+$. The occurrence and the effect of electron localization, non-adiabatic redshift and spatially asymmetric emission are evaluated to understand better complex patterns appearing in the high-order harmonic generation (HHG) spectrum. Results show that the complex patterns in the HHG spectrum originate mainly from a non-adiabatic response of the molecule to the rapidly changing laser field and also from a spatially asymmetric emission along the polarization direction. The effect of electron localization on the HHG spectrum was not observed as opposed to what is reported in the literature.

  4. Spray deposited CeO2–TiO2 counter electrode for electrochromic devices

    A K Bhosale; S R Kulal; V M Gurame; P S Patil


    * = 40.32, * = −1.16, * = −5.65) with steady decrease in relative lightness. Yxy and *** coordinates signify CeO2–TiO2 films and it also exhibits the application as counter electrode in electrochromic smart windows in which they are able to retain their transparency under charge insertion/extraction.

  5. 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.

  6. Upper ocean O2 trends: 1958-2015

    Ito, Takamitsu; Minobe, Shoshiro; Long, Matthew C.; Deutsch, Curtis


    Historic observations of dissolved oxygen (O2) in the ocean are analyzed to quantify multidecadal trends and variability from 1958 to 2015. Additional quality control is applied, and the resultant oxygen anomaly field is used to quantify upper ocean O2 trends at global and hemispheric scales. A widespread negative O2 trend is beginning to emerge from the envelope of interannual variability. Ocean reanalysis data are used to evaluate relationships with changes in ocean heat content (OHC) and oxygen solubility (O2,sat). Global O2 decline is evident after the 1980s, accompanied by an increase in global OHC. The global upper ocean O2 inventory (0-1000 m) changed at the rate of -243 ± 124 T mol O2 per decade. Further, the O2 inventory is negatively correlated with the OHC (r = -0.86; 0-1000 m) and the regression coefficient of O2 to OHC is approximately -8.2 ± 0.66 nmol O2 J-1, on the same order of magnitude as the simulated O2-heat relationship typically found in ocean climate models. Variability and trends in the observed upper ocean O2 concentration are dominated by the apparent oxygen utilization component with relatively small contributions from O2,sat. This indicates that changing ocean circulation, mixing, and/or biochemical processes, rather than the direct thermally induced solubility effects, are the primary drivers for the observed O2 changes. The spatial patterns of the multidecadal trend include regions of enhanced ocean deoxygenation including the subpolar North Pacific, eastern boundary upwelling systems, and tropical oxygen minimum zones. Further studies are warranted to understand and attribute the global O2 trends and their regional expressions.

  7. Effective nitrogen doping into TiO2 (N-TiO2) for visible light response photocatalysis.

    Yoshida, Tomoko; Niimi, Satoshi; Yamamoto, Muneaki; Nomoto, Toyokazu; Yagi, Shinya


    The thickness-controlled TiO2 thin films are fabricated by the pulsed laser deposition (PLD) method. These samples function as photocatalysts under UV light irradiation and the reaction rate depends on the TiO2 thickness, i.e., with an increase of thickness, it increases to the maximum, followed by decreasing to be constant. Such variation of the reaction rate is fundamentally explained by the competitive production and annihilation processes of photogenerated electrons and holes in TiO2 films, and the optimum TiO2 thickness is estimated to be ca. 10nm. We also tried to dope nitrogen into the effective depth region (ca. 10nm) of TiO2 by an ion implantation technique. The nitrogen doped TiO2 enhanced photocatalytic activity under visible-light irradiation. XANES and XPS analyses indicated two types of chemical state of nitrogen, one photo-catalytically active N substituting the O sites and the other inactive NOx (1⩽x⩽2) species. In the valence band XPS spectrum of the high active sample, the additional electronic states were observed just above the valence band edge of a TiO2. The electronic state would be originated from the substituting nitrogen and be responsible for the band gap narrowing, i.e., visible light response of TiO2 photocatalysts.

  8. The use of pulse oximetry as a screening assessment for paediatric neurogenic dysphagia.

    Morgan, A T; Omahoney, R; Francis, H


    Early screening and intervention for dysphagia is crucial to offset potential outcomes such as compromised nutrition or reduced respiratory function. Current paediatric dysphagia screening tests are subjective with poor sensitivity and specificity. The present study examined whether an objective method, pulse oximetry (measuring oxygen saturation (SpO2) levels), could differentiate between children with and without dysphagia, in relation to (1) Average pre-feeding baseline SpO2 levels; (2) Average feeding SpO2 levels; (3) Average post-feeding SpO2 levels; and (4) The number of events of oxygen desaturation pre-, during and after feeding. Nine participants with chronic neurological disability (CND) (7 F, 2 M) (9; 7-15; 11 years) and nine control participants matched for age (9; 5-16; 0 years) and sex were assessed using a clinical bedside evaluation (CBE) and pulse oximetry. A statistically significant difference was found in SpO2 levels between the two groups (p dysphagia experienced 'events' of SpO2 desaturation during feeding. Pulse oximetry may provide a useful adjunct to the CBE for dysphagia screening, with average SpO2 levels during feeding predicting those with and without dysphagia with moderate levels of sensitivity and specificity. The finding of individual variation in desaturation 'events', however, warrants the provision of further data on large homogenous populations to provide definitive criterion for pathological SpO2 levels associated with dysphagia during oral feeding.

  9. Distribution of electron traps in SiO2/HfO2 nMOSFET

    Xiao-Hui, Hou; Xue-Feng, Zheng; Ao-Chen, Wang; Ying-Zhe, Wang; Hao-Yu, Wen; Zhi-Jing, Liu; Xiao-Wei, Li; Yin-He, Wu


    In this paper, the principle of discharge-based pulsed I-V technique is introduced. By using it, the energy and spatial distributions of electron traps within the 4-nm HfO2 layer have been extracted. Two peaks are observed, which are located at ΔE ˜ -1.0 eV and -1.43 eV, respectively. It is found that the former one is close to the SiO2/HfO2 interface and the latter one is close to the gate electrode. It is also observed that the maximum discharge time has little effect on the energy distribution. Finally, the impact of electrical stress on the HfO2 layer is also studied. During stress, no new electron traps and interface states are generated. Meanwhile, the electrical stress also has no impact on the energy and spatial distribution of as-grown traps. The results provide valuable information for theoretical modeling establishment, material assessment, and reliability improvement for advanced semiconductor devices. Project supported by the National Natural Science Foundation of China (Grant Nos. 61334002, 61106106, and 61474091), the New Experiment Development Funds for Xidian University, China (Grant No. SY1434), and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, China (Grant No. JY0600132501).

  10. Identification of slow relaxing spin components by pulse EPR techniques in graphene-related materials

    Antonio Barbon


    Full Text Available Electron Paramagnetic Resonance (EPR is a powerful technique that is suitable to study graphene-related materials. The challenging ability requested to the spectroscopy is its capability to resolve the variety of structures, relatively similar, that are obtained in materials produced through different methods, but that also coexist inside a single sample. In general, because of the intrinsic inhomogeneity of the samples, the EPR spectra are therefore a superposition of spectra coming from different structures. We show that by pulse EPR techniques (echo-detected EPR, ESEEM and Mims ENDOR we can identify and characterize species with slow spin relaxing properties. These species are generally called molecular states, and are likely small pieces of graphenic structures of limited dimensions, thus conveniently described by a molecular approach. We have studied commercial reduced graphene oxide and chemically exfoliated graphite, which are characterized by different EPR spectra. Hyperfine spectroscopies enabled us to characterize the molecular components of the different materials, especially in terms of the interaction of the unpaired electrons with protons (number of protons and hyperfine coupling constants. We also obtained useful precious information about extent of delocalization of the molecular states.

  11. Effects of Synchronization between Cardiac and Locomotor Rhythms on Oxygen Pulse during Walking

    Shinta Takeuchi


    Full Text Available The oObjective of the study was to investigate whether the occurrence of cardiac–locomotor synchronization (CLS affects oxygen pulse (O2 pulse, mL/beat during walking. Twelve healthy men were studied under two treadmill protocols. The CLS protocol involved subjects walking at a frequency of their heart rate (HR to induce CLS. The free protocol (reference involved subjects walking at a self-selected cadence. The treadmill load was equal between the two protocols and was adjusted so that the subject’s HR was maintained at approximately 120 bpm. Electrocardiographic signals, foot switch signals, and oxygen consumption (VO2 were measured continuously for 10 min after the heart rate reached a steady state. VO2, O2 pulse, and mean HR were calculated. VO2 and O2 pulse were significantly higher in subjects in the CLS protocol compared to those in the free protocol. However, mean HR was not different between the two groups. The synchronization strength was significantly related to the increase in O2 pulse in subjects in the CLS protocol compared with those in the free protocol. These results suggest that the occurrence of CLS enhances O2 pulse by increasing the strength of CLS during walking.

  12. Preparation of transparent fluorocarbon/TiO2-SiO2 composite coating with improved self-cleaning performance and anti-aging property

    Zhou, Jianping; Tan, Zhongyuan; Liu, Zhilei; Jing, Mengmeng; Liu, Wenjie; Fu, Wanli


    This work reports a facile method to fabricate transparent self-cleaning fluorocarbon coatings filled by semicrystalline colloidal particles of TiO2-SiO2 composite oxide presenting a particle size ranging from 6 to 10 nm. Anatase-TiO2 crystallites were successfully obtained after microwave heating treatment of the TiO2-SiO2 colloidal particles as confirmed by XRD, TEM and FTIR measurements. The fluorocarbon/TiO2-SiO2 composite coatings exhibited a superior hydrophilicity and an improved photocatalytic activity in contrast to the TiO2-filled coatings. In particular, a water contact angle (WCA) value of 4.5° and a decolorization ratio relative to methyl orange as high as 96.0% were achieved for the composite coatings containing 1.5 wt% of TiO2-SiO2 colloidal particles. The results of the anti-soiling experiments indicated that the fluorocarbon/TiO2-SiO2 composite coatings exhibited a prominent self-cleaning performance, while the accelerated aging experiments revealed that the fluorocarbon/TiO2-SiO2 composite coatings were highly stable toward UV irradiation when compared to the TiO2-filled fluorocarbon coatings. These findings indicated that the fluorocarbon/TiO2-SiO2 composite coatings could be a very attractive solution for many practical areas, especially for outdoor applications.

  13. Upper limits for the rate constants of the reactions of CF3O2 and CF3O radicals with ozone at 295 K

    Nielsen, O.J.; Sehested, J.


    Using the pulse radiolysis UV absorption technique and subsequent simulations of experimental absorption transients at 254 and 276 nm, upper limits of the rate constants for the reactions of CF3O2 and CF3O radicals with ozone were determined at 295 K, CF3O2+O3-->CF3O+2O2 (4), CF3O+O3-->CF3O2+O2 (......). The upper limits were derived as k4 ozone depletion by hydrofluorocarbons.......Using the pulse radiolysis UV absorption technique and subsequent simulations of experimental absorption transients at 254 and 276 nm, upper limits of the rate constants for the reactions of CF3O2 and CF3O radicals with ozone were determined at 295 K, CF3O2+O3-->CF3O+2O2 (4), CF3O+O3-->CF3O2+O2 (5...

  14. Onset of leptin resistance shows temporal differences related to dose or pulsed treatment.

    Strehler, Kevin Y E; Matheny, Michael; Kirichenko, Nataliya; Sakarya, Yasemin; Bruce, Erin; Toklu, Hale Zerrin; Carter, Christy S; Morgan, Drake; Tümer, Nihal; Scarpace, Philip J


    Leptin administration results in leptin resistance presenting a significant barrier to therapeutic use of leptin. Consequently, we examined two hypotheses. The first examined the relationship between leptin dose and development of physiological and biochemical signs of leptin resistance. We hypothesized lower doses of leptin would produce proportional reductions in body weight without the adverse leptin-induced leptin resistance. The second compared pulsed central leptin infusion to continuous leptin infusion. We hypothesized that pulsed infusion at specific times of the day would evoke favorable body weight reductions while tempering the development of leptin-induced leptin resistance. The first experiment examined leptin responsiveness, including food intake, body weight and hypothalamic STAT3 phosphorylation to increasing doses of viral gene delivery of leptin. Varying the dose proved inconsequential with respect to long-term therapy and demonstrated proportional development of leptin resistance. The second experiment examined leptin responsiveness to pulsed central leptin infusion, comparing pulsed versus constant infusion of 3μg/day leptin or a 2h morning versus a 2h evening pulsed leptin infusion. Pulsed delivery of the supramaximal dose of 3μg/day was not different than constant delivery. Morning pulsed infusion of the submaximal dose of 0.25μg reduces food intake only over subsequent immediate meal period and was associated with body weight reductions, but results in cellular leptin resistance. Evening pulsed infusion did not decrease food intake but reduces body weight and maintains full leptin signaling. The positive benefit for pulsed delivery remains speculative, yet potentially may provide an alternative mode of leptin therapy.

  15. TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: A comparative study of photo catalysis on acid red 88

    Balachandran, K.; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P.


    A novel, simple, less time-consuming and cost-effective wet chemical technique was used to synthesis TiO2 nanoparticles and TiO2-SiO2 nanocomposites using Titanium tetra isopropoxide (TTIP) as a precursor relatively at low temperature in acidic pH. Titania sol was prepared by hydrolysis of TTIP and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6 h and dried at room temperature. The resulting powders were characterized by UV-Visible spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM). The grain size of the particles was calculated by X-ray diffraction, surface morphology and chemical composition was determined from scanning electron microscopy-energy dispersive spectroscopy, metal oxide stretching was confirmed from FT-IR spectroscopy, band gap was calculated using UV-Visible spectroscopy. Surface area of the composite as calculated by BET analyzer and it was found to be 65 and 75 m2/g for TiO2 and TiO2-SiO2 respectively. The photocatalytic experiments were performed with aqueous solution of acid red 88 with TiO2 and TiO2-SiO2 batch studies for 4 h irradiation, direct photolysis of TiO2 and TiO2-SiO2 contributed 94.2% and 96.5% decomposition in solar radiation for the optimized concentration of acid red 88.

  16. Photocatalysis of gaseous trichloroethylene (TCE) over TiO2: the effect of oxygen and relative humidity on the generation of dichloroacetyl chloride (DCAC) and phosgene.

    Ou, Hsin-Hung; Lo, Shang-Lien


    Batch photocatalytic degradation of 80+/-2.5 ppm V trichloroethylene (TCE) was conducted to investigate the effect of the oxygen and relative humidity (RH) on the formation of the dichloroacetyl chloride (DCAC) and phosgene. Based on the simultaneous ordinary differential equations (ODEs), the reaction rate constants of TCE ((2.31+/-0.28) approximately (9.41+/-0.63)x10(-2) min(-1)) are generally larger than that of DCAC ((0.94+/-1.25) approximately (9.35+/-1.71)x10(-3) min(-1)) by approximate one order. The phenomenon indicates the degradation potential of TCE is superior to that of DCAC. DCAC appreciably delivers the same degradation behavior with TCE that means there exists an optimum RH and oxygen concentration for photocatalysis of TCE and DCAC. At the time the peak yield of DCAC appears, the conversion ratio based on the carbon atom from TCE to DCAC is within the range of 30-83% suggesting that the DCAC generation is significantly attributed to TCE degradation. Regarding the phosgene formation, the increasing oxygen amount leads to the inhibitory effect on the phosgene yield which fall within the range of 5-15%. The formation mechanism of phosgene was also inferred that the Cl atoms attacking the C-C bond of DCAC results to the generation of phosgene rather than directly from the TCE destruction.

  17. Review on modified TiO2 photocatalysis under UV/visible light: selected results and related mechanisms on interfacial charge carrier transfer dynamics.

    Kumar, S Girish; Devi, L Gomathi


    Titania is one of the most widely used benchmark standard photocatalysts in the field of environmental applications. However, the large band gap of titania and massive recombination of photogenerated charge carriers limit its overall photocatalytic efficiency. The former can be overcome by modifying the electronic band structure of titania including various strategies like coupling with a narrow band gap semiconductor, metal ion/nonmetal ion doping, codoping with two or more foreign ions, surface sensitization by organic dyes or metal complexes, and noble metal deposition. The latter can be corrected by changing the surface properties of titania by fluorination or sulfation or by the addition of suitable electron acceptors besides molecular oxygen in the reaction medium. This review encompasses several advancements made in these aspects, and also some of the new physical insights related to the charge transfer events like charge carrier generation, trapping, detrapping, and their transfer to surface are discussed for each strategy of the modified titania to support the conclusions derived. The synergistic effects in the mixed polymorphs of titania and also the theories proposed for their enhanced activity are reported. A recent venture on the synthesis and applications of anatase titania with a large percentage of reactive {001} facets and their band gap extension to the visible region via nonmetal ion doping which is a current hot topic is briefly outlined.

  18. [Spectral diagnosis of hydroxyl radical in multiphase pulsed discharge system].

    Wang, Hui-juan; Li, Jie; Quan, Xie; Wu, Yan; Li, Guo-feng


    A gas-liquid hybrid pulsed discharge system with a multi-needle-to-plate electrode geometry was used in the present study. A multiphase (gas-liquid-solid) pulsed discharge system was then formed by adding glasses beads immobilized with TiO2 photocatalyst into the discharge system. In the present paper, ultraviolet light produced during the pulsed discharge process was used as the lamp-house to induce the photocatalytic activity of the TiO2 photocatalyst. The synergistic effect of pulsed discharge and TiO2 photocatalysis was reviewed by the spectral diagnosis of hydroxyl radical ( *OH) in the pulsed discharge system. The obtained results showed that the emission spectrum of *OH could be observed at 306 nm (A2Sigma+-->X2II), 309 mn (A2Sigma+ (v' = 0) --> X2II (v" = 0)) and 313 nm (A2Sigma+ (v' = 1) --> X2II (v" = 1) transition). The relative emission intensity of *OH at 313 nm in the discharge system was the strongest among the three characteristic spectra. The relative emission intensity of *OH at 313 nm was stronger by adding TiO2 photocatalyst into the pulsed discharge system than that in the sole pulsed discharge system. In the case of experiments that changing the gas bubbling varieties and initial solution pH values, the results revealed that the relative emission intensity of *OH at 313 nm in the synergistic system was stronger when Ar was used as bubbling gas compared with that when air and oxygen were bubbled into the reaction system. Furthermore, the acidic solution system was favorable for producing more *OH, and therefore the corresponding emission intensity of *OH at 313 nm was stronger than that in the neutral and basic solution.

  19. The flux-E_p relation within GRB060218 in comparison with typical GRB pulses


    The prompt gamma-ray/X-ray emission of gamma-ray burst(GRB) 060218 was simultaneously observed by the Burst Alert Telescope(BAT) and X-ray Telescope(XRT) onboard Swift.Its peak energy of the joint νfν spectrum(Ep) clearly evolves with time from tens of keV to-1 keV,crossing both the BAT and XRT bands.The best fit yields log Ep=(4.61± 0.23)+(-1.29±0.08) log t,with a correlation coefficient of 0.98 and a chance probability of p<10-4.We derive its bolometric flux(F)in the 0.01-10 4 keV band,and find that its F-Ep relation,with a power-law index of 0.37,is much shallower than that observed in typical GRB pulses.Discussion of this shallowness is presented.

  20. 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.

  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. [Accuracy of a pulse oximeter during hypoxia].

    Tachibana, C; Fukada, T; Hasegawa, R; Satoh, K; Furuya, Y; Ohe, Y


    The accuracy of the pulse oximeter was examined in hypoxic patients. We studied 11 cyanotic congenital heart disease patients during surgery, and compared the arterial oxygen saturation determined by both the simultaneous blood gas analysis (CIBA-CORNING 288 BLOOD GAS SYSTEM, SaO2) and by the pulse oximeter (DATEX SATELITE, with finger probe, SpO2). Ninty sets of data on SpO2 and SaO2 were obtained. The bias (SpO2-SaO2) was 1.7 +/- 6.9 (mean +/- SD) %. In cyanotic congenital heart disease patients, SpO2 values were significantly higher than SaO2. Although the reason is unknown, in constantly hypoxic patients, SpO2 values are possibly over-estimated. In particular, pulse oximetry at low levels of saturation (SaO2 below 80%) was not as accurate as at a higher saturation level (SaO2 over 80%). There was a positive correlation between SpO2 and SaO2 (linear regression analysis yields the equation y = 0.68x + 26.0, r = 0.93). In conclusion, the pulse oximeter is useful to monitor oxygen saturation in constantly hypoxic patients, but the values thus obtained should be compared with the values measured directly when hypoxemia is severe.

  3. Global Remote Sensing of Precipitating Electron Energies: A Comparison of Substorms and Pressure Pulse Related Intensifications

    Chua, D.; Parks, G. K.; Brittnacher, M. J.; Germany, G. A.; Spann, J. F.


    The Polar Ultraviolet Imager (UVI) observes aurora responses to incident solar wind pressure pulses and interplanetary shocks such its those associated with coronal mass ejections. Previous observations have demonstrated that the arrival of it pressure pulse at the front of the magnetosphere results in highly disturbed geomagnetic conditions and a substantial increase in both dayside and nightside aurora precipitations. Our observations show it simultaneous brightening over bread areas of the dayside and nightside auroral in response to a pressure pulse, indicating that more magnetospheric regions participate as sources for auroral precipitation than during isolate substorm. We estimate the characteristic energies of incident auroral electrons using Polar UVI images and compare the precipitation energies during pressure pulse associated event to those during isolated substorms. We estimate the characteristic energies of incident auroral electrons using Polar UVI images and compare the precipitation energies during pressure pulse associated events to those during isolated auroral substorms. Electron precipitation during substorms has characteristic energies greater than 10 KeV and is structured both in local time and in magnetic latitude. For auroral intensifications following the arrival of'a pressure pulse or interplanetary shock. Electron precipitation is less spatially structured and has greater flux of lower characteristic energy electrons (Echar less than 7 KeV) than during isolated substorm onsets. These observations quantify the differences between global and local auroral precipitation processes and will provide a valuable experimental check for models of sudden storm commencements and magnetospheric response to perturbations in the solar wind.

  4. Multifunctional Roles of TiO 2 Nanoparticles for Architecture of Complex Core−Shells and Hollow Spheres of SiO 2 −TiO 2 −Polyaniline System

    Wang, Dan Ping


    Nanoparticles are often used as seeds to grow one-dimensional nanomaterials or as core materials to prepare core-shell nanostructures. On the other hand, the presynthesized inorganic nanoparticles can also be used as starting building blocks to prepare inorganic-polymer nanocomposites. In this work, we explore the roles of metal-oxide nanoparticles (anatase TiO2) in the area of constructional synthesis of highly complex core-shell and hollow sphere nanostructures comprising SiO2, TiO2, and polyaniline (PAN). In particular, multifunctional roles of oleate-surfactant-protected TiO2 nanoparticles have been revealed in this study: they provide starting sites for polymerization of aniline on the surface of SiO2 mesospheres; they land on the inner surface of polyaniline shell to form a secondary material phase; they work as initial crystalline seeds for homogeneous growth of interior TiO2 shell; and they serve as primary nanobuilding blocks to form exterior TiO2 shell on the polyaniline via self-assembly. With the assistance of the TiO2 nanoparticles, a total of six complex core-shell and hollow sphere nanocomposites (SiO 2/TiO2, SiO2/TiO2/PAN, SiO 2/TiO2/PAN/TiO2, TiO2/PAN, TiO 2/PAN/TiO2, and TiO2/TiO2) have been made in this work through controlled self-assembly, templating growth, polymerization, and homogeneous seeded growth. Applicability of these nanostructures in photocatalytic applications has also been demonstrated by our preliminary investigations. The easy separation of used catalysts after reaction seems to be advantageous because of relatively large external diameters of the lightweight nanocomposites. © 2009 American Chemical Society.

  5. Growth of pulsed electric field exposed Escherichia coli in relation to inactivation and environmental factors.

    Aronsson, Kristina; Borch, Elisabeth; Stenlöf, Bo; Rönner, Ulf


    Pulsed electric fields (PEF) have been proven to inactivate microorganisms during nonthermal conditions and have the potential to replace thermal processing as a method for food preservation. However, there is a need to understand the recovery and growth of survivors and potentially injured microorganisms following PEF processing. The purpose of this investigation was to study the growth of Escherichia coli at 10 degrees C following exposure to electrical field strengths (15, 22.5 and 30 kV/cm) in relation to inactivation and the amount of potentially sublethally injured cells. One medium was used as both a treatment medium and an incubation medium, to study the influence of environmental factors on the inactivation and the growth of the surviving population. The pH (5.0, 6.0 and 7.0) and water activity (1.00, 0.985 and 0.97) of the medium was varied by adding HCl and glycerol, respectively. Growth was followed continuously by measuring the optical density. The time-to-detection (td) and the maximum specific growth rate (micromax) were calculated from these data. Results showed that the PEF process did not cause any obvious sublethal injury to the E. coli cells. The number of survivors was a consequence of the combination of electrical field strength and environmental factors, with pH being the most prominent. Interestingly, the micromax of subsequent growth was influenced by the applied electrical field strength during the process, with an increased micromax at more intense electrical field strengths. In addition, the micromax was also influenced by the pH and water activity. The td, which could theoretically be considered as an increase in shelf life, was found to depend on a complex correlation between electrical field strength, pH and water activity. That could be explained by the fact that the td is a combination of the number of survivors, the recovery of sublethal injured cells and the growth rate of the survivors.

  6. Light inactivation of food-related pathogenic bacteria using a pulsed power source.

    MacGregor, S J; Rowan, N J; Mcllvaney, L; Anderson, J G; Fouracre, R A; Farish, O


    The effects of high intensity light emissions, produced by a novel pulsed power energization technique (PPET), on the survival of bacterial populations of verocytotoxigenic Escherichia coli (serotype 0157:H7) and Listeria monocytogenes (serotype 4b) were investigated. Using this PPET approach, many megawatts (MW) of peak electrical power were dissipated in the light source in an extremely short energization time (about 1 microsecond). The light source was subjected to electric field levels greater than could be achieved under conventional continuous operation, which led to a greater production of the shorter bacteriocidal wavelengths of light. In the exposure experiments, pre-determined bacterial populations were spread onto the surface of Trypone Soya Yeast Extract Agar and were then treated to a series of light pulses (spectral range of 200-530 nm) with an exposure time ranging from 1 to 512 microseconds. While results showed that as few as 64 light pulses of 1 microsecond duration were required to reduce E. coli 0157:H7 populations by 99.9% and Listeria populations by 99%, the greater the number of light pulses the larger the reduction in cell numbers (P pulsed light emissions can significantly reduce populations of E. coli 0157:H7 and L. monocytogenes on exposed surfaces with exposure times which are 4-6 orders of magnitude lower than those required using continuous u.v. light sources.

  7. Identification of dislocation-related luminescence participating levels in silicon by DLTS and Pulsed-CL profiling

    Bondarenko, Anton; Vyvenko, Oleg; Isakov, Ivan


    We present a study of the dislocation network that occurs in the space charge region of a Schottky diode, by means of DLTS and our recently developed cathodoluminescent (CL) technique called Pulsed-CL. The details of the Pulsed-CL technique are provided. We establish a correspondence between the CL spectra of dislocation-related luminescence in silicon in the vicinity of the so-called D1 band and levels determined from DLTS measurements. The centres responsible for the 815 meV CL component are related to dislocations cores while the centres responsible for the 795 meV CL component are related to some defects outside of the dislocation cores.

  8. Protective Effect of Salvianolic Acid B on H9c2 Cells Injury Induced by H2O2 and Its Possible Target-related Proteins%丹酚酸B对H2O2引起H9c2细胞氧化损伤的保护作用及可能靶点蛋白寻找

    景春杰; 陈晓辉; 毕开顺; 刘璇; 果德安


    观察丹酚酸B对H2O2引起H9c2细胞氧化损伤的影响,在分子水平上探讨丹酚酸B对H2O2诱导氧化损伤保护作用的可能机制.用H2O2刺激H9c2建市体外心肌细胞氧化损伤模型,MTT测定心肌细胞的存活率,Hochest33342染色观察细胞凋亡,并用蛋白质组学技术寻找丹酚酸B在心肌细胞中的可能蛋白质靶点.丹酚酸B可以提高心肌细胞在H2O2处理下的存活率,减少H2O2导致的细胞凋亡,丹酚酸B预处理组与单用H2O2组相比有8个差异表达蛋白,其中Heat shock 27 kua protein蛋白下调,cytochrome C oxidase、myo-sin light polypeptide 6、myosin、myosin regulatory light chain 2、myosin regulatory light chain 9、tropomyosin和secreted acidic cysteine rich glycoprotein蛋白上调,差异表达的蛋白可能在丹酚酸B的保护机制中发挥重要作用.

  9. The novel triterpenoid RTA 408 protects human retinal pigment epithelial cells against H2O2-induced cell injury via NF-E2-related factor 2 (Nrf2 activation

    Xiaobin Liu


    Full Text Available Oxidative stress-induced retinal pigment epithelial (RPE cell damage is an important factor in the pathogenesis of age-related macular degeneration (AMD. Previous studies have shown that RTA 408, a synthetic triterpenoid compound, potently activates Nrf2. This study aimed to investigate the protective effects of RTA 408 in cultured RPE cells during oxidative stress and to determine the effects of RTA 408 on Nrf2 and its downstream target genes. Primary human RPE cells were pretreated with RTA 408 and then incubated in 200 μM H2O2 for 6 h. Cell viability was measured with the WST-8 assay. Apoptosis was quantitatively measured by annexin V/propidium iodide (PI double staining and Hoechst 33342 fluorescent staining. Reduced (GSH and oxidized glutathione (GSSG were measured using colorimetric assays. Nrf2 activation and its downstream effects on phase II enzymes were examined by Western blot. Treatment of RPE cells with nanomolar ranges (10 and 100 nM of RTA 408 markedly attenuated H2O2-induced viability loss and apoptosis. RTA 408 pretreatment significantly protected cells from oxidative stress-induced GSH loss, GSSG formation and decreased ROS production. RTA 408 activated Nrf2 and increased the expression of its downstream genes, such as HO-1, NQO1, SOD2, catalase, Grx1, and Trx1. Consequently, the enzyme activities of NQO1, Grx1, and Trx1 were fully protected by RTA 408 pretreatment under oxidative stress. Moreover, knockdown of Nrf2 by siRNA significantly reduced the cytoprotective effects of RTA 408. In conclusion, our data suggest that RTA 408 protect primary human RPE cells from oxidative stress-induced damage by activating Nrf2 and its downstream genes.

  10. Investigation of critical inter-related factors affecting the efficacy of pulsed light for inactivating clinically relevant bacterial pathogens.

    Farrell, H P; Garvey, M; Cormican, M; Laffey, J G; Rowan, N J


    To investigate critical electrical and biological factors governing the efficacy of pulsed light (PL) for the in vitro inactivation of bacteria isolated from the clinical environment. Development of this alternative PL decontamination approach is timely, as the incidence of health care-related infections remains unacceptably high. Predetermined cell numbers of clinically relevant Gram-positive and Gram-negative bacteria were inoculated separately on agar plates and were flashed with pulses of broad-spectrum light under varying operating conditions, and their inactivation measured. Significant differences in inactivation largely occurred depending on the level of the applied lamp discharge energy (range 3.2-20 J per pulse), the amount of pulsing applied (range 0-60 pulses) and the distance between light source and treatment surface (range 8-20 cm) used. Greater decontamination levels were achieved using a combination of higher lamp discharge energies, increased number of pulses and shorter distances between treatment surface and the xenon light source. Levels of microbial sensitivity also varied depending on the population type, size and age of cultures treated. Production of pigment pyocynanin and alginate slime in mucoid strains of Pseudomonas aeruginosa afforded some protection against lethal action of PL; however, this was evident only by using a combination of reduced amount of pulsing at the lower lamp discharge energies tested. A clear pattern was observed where Gram-positive bacterial pathogens were more resistant to cidal effects of PL compared to Gram negatives. While negligible photoreactivation of PL-treated bacterial strains occurred after full pulsing regimes at the different lamp discharge energies tested, some repair was evident when using a combination of reduced pulsing at the lower lamp discharge energies. Strains harbouring genes for multiple resistances to antibiotics were not significantly more resistant to PL treatments. Slight temperature

  11. Electrorheological Effects of Cerium-Doped TiO2

    尹剑波; 赵晓鹏


    It is found that the doping of cerium ion into anatase TiO2 can improve the electrorheological (ER) effects of TiO2 and broaden the operational temperature range. Especially, the substitution of 7-11 mol% of the cerium dopant for Ti can obtain a relatively high shear stress, t-7.4kPa (at 4kV/mm), which is ten times larger than that of pure TiO2 ER fluid. Also, the typical Ce-doped TiO2 ER fluid shows the highest shear stress at 80℃, but 40℃ for pure TiO2 ER fluid. The dielectric loss and dielectric constant at a low frequency of TiO2 is improved by the doping of cerium, and the temperature dependence of the dielectric properties shows an obvious differnce between pure and doped TiO2 ER fluids. These can well explain the ER behaviour of doped TiO2. Furthermore, the change of rheological and dielectric properties is discussed on the basis of the lattice distortion and defects in TiO2 arising from the doping of cerium.

  12. Atomic layer deposition of Ru from CpRu(CO)(2)Et using O-2 gas and O-2 plasma

    Leick, N.; Verkuijlen, R. O. F.; Lamagna, L.; Langereis, E.; Rushworth, S.; Roozeboom, F.; M. C. M. van de Sanden,; Kessels, W. M. M.


    The metalorganic precursor cyclopentadienylethyl(dicarbonyl)ruthenium (CpRu(CO)(2)Et) was used to develop an atomic layer deposition (ALD) process for ruthenium. O-2 gas and O-2 plasma were employed as reactants. For both processes, thermal and plasma-assisted ALD, a relatively high growth-per-cycle

  13. TiO2-TiO2 composite resistive humidity sensor: ethanol crosssensitivity

    Ghalamboran, Milad; Saedi, Yasin


    The fabrication method and characterization results of a TiO2-TiO2 composite bead used for humidity sensing along with its negative cross-sensitivity to ethanol vapor are reported. The bead shaped resistive sample sensors are fabricated by the drop-casting of a TiO2 slurry on two Pt wire segments. The dried bead is pre-fired at 750°C and subsequently impregnated with a Ti-based sol. The sample is ready for characterization after a thermal annealing at 600°C in air. Structurally, the bead is a composite of the micron-sized TiO2 crystallites embedded in a matrix of nanometric TiO2 particle aggregates. The performance of the beads as resistive humidity sensors is recorded at room temperature in standard humidity level chambers. Results evince the wide dynamic range of the sensors fabricated in the low relative humidity range. While the sensor conductance is not sensitive to ethanol vapor in dry air, in humid air, sensor's responses are negatively affected by the contaminant.

  14. Acute changes in pulse pressure in relation to constituents of particulate air pollution in elderly persons

    Jacobs, Lotte [Occupational and Environmental Medicine, Unit of Lung Toxicology, K.U.Leuven, Leuven (Belgium); Buczynska, Anna [Departement of Chemistry, UA, Wilrijk (Belgium); Walgraeve, Christophe [Research group EnVOC, Department of Sustainable Organic Chemistry and Technology, UGent, Gent (Belgium); Delcloo, Andy [Royal Meteorological Institute, Brussels (Belgium); Potgieter-Vermaak, Sanja [Departement of Chemistry, UA, Wilrijk (Belgium); Molecular Science Institute, School of Chemistry, University of Witwatersrand, Johannesburg (South Africa); Division of Chemistry and Environmental Science, Manchester Metropolitan University, Manchester (United Kingdom); Van Grieken, Rene [Departement of Chemistry, UA, Wilrijk (Belgium); Demeestere, Kristof; Dewulf, Jo; Van Langenhove, Herman [Research group EnVOC, Department of Sustainable Organic Chemistry and Technology, UGent, Gent (Belgium); De Backer, Hugo [Royal Meteorological Institute, Brussels (Belgium); Nemery, Benoit, E-mail: [Occupational and Environmental Medicine, Unit of Lung Toxicology, K.U.Leuven, Leuven (Belgium); Nawrot, Tim S. [Occupational and Environmental Medicine, Unit of Lung Toxicology, K.U.Leuven, Leuven (Belgium); Centre for Environmental Sciences, Hasselt University, Diepenbeek (Belgium)


    An increased pulse pressure (difference between systolic and diastolic blood pressure) suggests aortic stiffening. The objective of this study was to examine the acute effects of both particulate matter (PM) mass and composition on blood pressure, among elderly persons. We carried out a panel study in persons living in elderly homes in Antwerp, Belgium. We recruited 88 non-smoking persons, 70% women with a mean age of 83 years (standard deviation: 5.2). Blood pressure was measured and a blood sample was collected on two time points, which were chosen so that there was an exposure contrast in ambient PM exposure. The elemental content of the collected indoor and outdoor PM{sub 2.5} (particulate matter with an aerodynamic diameter <2.5 {mu}m) mass concentration was measured. Oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) on outdoor PM{sub 10} (particulate matter with an aerodynamic diameter <10 {mu}m) were measured. Each interquartile range increase of 20.8 {mu}g/m Superscript-Three in 24-h mean outdoor PM{sub 2.5} was associated with an increase in pulse pressure of 4.0 mmHg (95% confidence interval: 1.8-6.2), in persons taking antihypertensive medication (n=57), but not in persons not using antihypertensive medication (n=31) (p for interaction: 0.02). Vanadium, iron and nickel contents of PM{sub 2.5} were significantly associated with systolic blood pressure and pulse pressure, among persons on antihypertensive medication. Similar results were found for indoor concentrations. Of the oxy-PAHs, chrysene-5,6-dione and benzo[a]pyrene-3,6-dione were significantly associated with increases in systolic blood pressure and pulse pressure. In elderly, pulse pressure was positively associated with acute increases in outdoor and indoor air pollution, among persons taking antihypertensive medication. These results might form a mechanistic pathway linking air pollution as a trigger of cardiovascular events.

  15. Relative Responses of Noble Gases Using a Pulsed Discharge Helium Photoionization Detector:Theoretical Calculation and Experimental Determination

    ZHANG Hai-tao; WU Di; ZHANG Li-xing


    The relative response factors(RRFs) for noble gas(Ng) were determined on a pulsed discharge helium photoionization detector,Using ab initio method,the atomic orbitals of noble gas were calculated and used to determine the number of ionizable electrons on the basis of the continuous emission of He2,The molar responses of noble gases is well correlated with the number of ionizable electrons.

  16. Characterization and antibacterial functions of Ag-TiO2 and W-TiO2 nanostructured thin films prepared by sol-gel/laser-induced technique

    Joya, Y. F.; Liu, Z.; Wang, T.


    A novel sol-gel/laser-induced technique (SGLIT) has been developed to form nanocrystalline titanium dioxide (TiO2) based thin films with an improved antibacterial performance. TiO2 precursor films loaded with W+6 and Ag+2 ions (W-TiO2, Ag-TiO2) were prepared separately by sol-gel method and spin-coated on microscopic glass slides. As-dried films were subjected to KrF excimer laser pulses at optimized parameters to generate mesoporous anatase and rutile phases at room temperature. The anatase phase was obtained after irradiation with 10 laser pulses only at 75-85 mJ/cm2 fluence in W-TiO2 films. However, higher number of laser pulses and higher W+6 content favored the formation of rutile. Whereas Ag-TiO2 films exhibited anatase up to 200 laser pulses at the same fluence. The films were characterized by using XRD, FEG-SEM, TEM and UV-Vis spectrophotometer to investigate the crystallographic structure, phase transformation, surface morphology, film thickness and the optical properties. A crystallite size of approximately 20 nm was achieved from the anatase prepared by SGLIT. The films exhibited an enhanced antibacterial function against E-Coli cells under the UV excitation.

  17. 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.

  18. Urinary (1)H Nuclear Magnetic Resonance Metabolomic Fingerprinting Reveals Biomarkers of Pulse Consumption Related to Energy-Metabolism Modulation in a Subcohort from the PREDIMED study.

    Madrid-Gambin, Francisco; Llorach, Rafael; Vázquez-Fresno, Rosa; Urpi-Sarda, Mireia; Almanza-Aguilera, Enrique; Garcia-Aloy, Mar; Estruch, Ramon; Corella, Dolores; Andres-Lacueva, Cristina


    Little is known about the metabolome fingerprint of pulse consumption. The study of robust and accurate biomarkers for pulse dietary assessment has great value for nutritional epidemiology regarding health benefits and their mechanisms. To characterize the fingerprinting of dietary pulses (chickpeas, lentils, and beans), spot urine samples from a subcohort from the PREDIMED study were stratified using a validated food frequency questionnaire. Urine samples of nonpulse consumers (≤4 g/day of pulse intake) and habitual pulse consumers (≥25 g/day of pulse intake) were analyzed using a (1)H nuclear magnetic resonance (NMR) metabolomics approach combined with multi- and univariate data analysis. Pulse consumption showed differences through 16 metabolites coming from (i) choline metabolism, (ii) protein-related compounds, and (iii) energy metabolism (including lower urinary glucose). Stepwise logistic regression analysis was applied to design a combined model of pulse exposure, which resulted in glutamine, dimethylamine, and 3-methylhistidine. This model was evaluated by a receiver operating characteristic curve (AUC > 90% in both training and validation sets). The application of NMR-based metabolomics to reported pulse exposure highlighted new candidates for biomarkers of pulse consumption and the impact on energy metabolism, generating new hypotheses on energy modulation. Further intervention studies will confirm these findings.

  19. Strong-field-induced attosecond dynamics in SiO2

    Kienberger R.


    Full Text Available Striking field-induced changes in the absorption near the Si L-edge of SiO2 exposed to a near-infrared laser field of several V/Å delivered by a few-cycle pulse are observed with sub-100 attosecond extreme ultraviolet pulses by means of attosecond transient absorption.

  20. Laser-induced damage of TiO2/SiO2 high reflector at 1064 nm

    Yao, Jianke; Ma, Jianyong; Xiu, Cheng; Fan, Zhengxiu; Jin, Yunxia; Zhao, Yuanan; He, Hongbo; Shao, Jianda; Huang, Huolin; Zhang, Feng; Wu, Zhengyun


    A high laser-induced damage threshold (LIDT) TiO2/SiO2 high reflector (HR) at 1064nm is deposited by e-beam evaporation. The HR is characterized by optical properties, surface, and cross section structure. LIDT is tested at 1064nm with a 12ns laser pulse in the one-on-one mode. Raman technique and scanning electron Microscope are used to analyze the laser-induced modification of HR. The possible damage mechanism is discussed. It is found that the LIDT of HR is influenced by the nanometer precursor in the surface, the intrinsic absorption of film material, the compactness of the cross section and surface structure, and the homogeneity of TiO2 layer. Three typical damage morphologies such as flat-bottom pit, delamination, and plasma scald determine well the nanometer defect initiation mechanism. The laser-induced crystallization consists well with the thermal damage nature of HR.

  1. Photocatalytic TiO2 nanoparticles enhanced polymer antimicrobial coating

    Wei, Xiaojin; Yang, Zhendi; Tay, See Leng; Gao, Wei


    Copper (Cu) containing coatings can provide sustainable protection against microbial contamination. However, metallic Cu coatings have not been widely used due to the relatively high cost, poor corrosion resistance, and low compatibility with non-metal substrates. Titanium dioxide (TiO2) possesses antibacterial functions by its photocatalytic properties which can destroy bacteria or suppress their reproduction. TiO2 also has the function of improving the mechanical properties through particle dispersion strengthening. We have recently developed an innovative polymer based coating system containing fine particles of Cu and TiO2 nanoparticles. These polymer based coatings simultaneously display excellent antimicrobial and good mechanical properties. The results showed that the addition of TiO2 has improved the antimicrobial property under sunlight, which provides extended applications in outdoor environment. The elimination of 106 bacterial by contacting the coatings without TiO2 needs 5 h, while contacting with the Cu/TiO2- 1 wt.% TiO2 took only 2 h to kill the same amount of bacteria. The coatings also presented enhanced hardness and wear resistance after adding TiO2. The width of wear track decreased from 270 μm of the Cu-polymer coating to 206 μm of Cu/TiO2-polymer coatings with 10 wt.% TiO2. Synchrotron Infrared Microscopy was used to in-situ and in-vivo study the bacteria killing process at the molecular level. The real-time chemical images of bacterial activities showed that the bacterial cell membranes were damaged by the Cu and TiO2 containing coatings

  2. Time-evolution of Peak Energy and Luminosity Relation within Pulses for GRB 061007: Probing Fireball Dynamics

    Ohno, Masanori; Yamaoka, Kazutaka; Tashiro, Makoto; Fukazawa, Yasushi; Nakagawa, Yujin E


    We perform a time-resolved spectral analysis of bright, long Gamma-ray burst GRB 061007 using Suzaku/WAM and Swift/BAT. Thanks to the large effective area of the WAM, we can investigate the time evolution of the spectral peak energy, Et_peak and the luminosity Lt_iso with 1-sec time resolution, and we find that luminosity Lt_iso with 1-sec time resolution, and we find that the time-resolved pulses also satisfy the Epeak-Liso relation, which was found for the time-averaged spectra of other bursts, suggesting the same physical conditions in each pulse. Furthermore, the initial rising phase of each pulse could be an outlier of this relation with higher Et_peak value by about factor 2. This difference could suggest that the fireball radius expands by a factor of 2-4 and/or bulk Lorentz factor of the fireball is decelerated by a factor of 4 during the initial phase, providing a new probe of the fireball dynamics in real time.

  3. Effects of Synchronization between Cardiac and Locomotor Rhythms on Oxygen Pulse during Walking.

    Takeuchi, Shinta; Nishida, Yusuke; Mizushima, Takashi


    The oObjective of the study was to investigate whether the occurrence of cardiac-locomotor synchronization (CLS) affects oxygen pulse (O2 pulse, mL/beat) during walking. Twelve healthy men were studied under two treadmill protocols. The CLS protocol involved subjects walking at a frequency of their heart rate (HR) to induce CLS. The free protocol (reference) involved subjects walking at a self-selected cadence. The treadmill load was equal between the two protocols and was adjusted so that the subject's HR was maintained at approximately 120 bpm. Electrocardiographic signals, foot switch signals, and oxygen consumption (VO2) were measured continuously for 10 min after the heart rate reached a steady state. VO2, O2 pulse, and mean HR were calculated. VO2 and O2 pulse were significantly higher in subjects in the CLS protocol compared to those in the free protocol. However, mean HR was not different between the two groups. The synchronization strength was significantly related to the increase in O2 pulse in subjects in the CLS protocol compared with those in the free protocol. These results suggest that the occurrence of CLS enhances O2 pulse by increasing the strength of CLS during walking. Key PointsTwelve healthy men walked at a frequency of their heart rate (CLS protocol) and at a self-selected cadence (free protocol).Walking at the frequency of heart rate would induce the CLS by entrainment.Oxygen pulse was significantly higher in subjects in the CLS protocol compared to those in the free protocol.The occurrence of CLS enhances oxygen pulse by increasing the strength of CLS during walking.

  4. Synthesis, characterization, single crystal X-ray structure, EPR and theoretical studies of a new hybrid inorganic-organic compound [Cu(Hdien)2(H2O)2](pnb)4·4H2O and its structural comparison with related [Cu(en)2(H2O)2](pnb)2

    Kumar, Santosh; Sharma, Raj Pal; Venugopalan, Paloth; Witwicki, Maciej; Ferretti, Valeria


    A new hybrid inorganic-organic compound [Cu(Hdien)2(H2O)2](pnb)4·4H2O (1) (where pnb = p-nitrobenzoate), in which the tridentate ligand diethylenetriamine (dien) shows an unusual coordination behavior acting as a bidentate ligand when present in its monoprotonated form (Hdien+) has been synthesized by the reaction of copper(II) p-nitrobenzoate and slight excess of dien in methanol-water mixture (4:1v/v). Re-crystallization of the violet precipitated product from hot water gave single crystals suitable for X-ray diffraction studies. The newly synthesized compound 1 has been characterized by spectroscopic techniques (UV-Vis, FT-IR, EPR), and theoretical methods (DFT and MRCI/SORCI). Single crystal X-ray structure determination revealed the existence of the cationic species [Cu(Hdien)2(H2O)2]4+, four p-nitrobenzoate as counter anions and four water molecules are present as solvent of crystallization. Packing analyses of title compound as well as of the structurally similar [Cu(en)2(H2O)2](pnb)2,2 has shown similarities in the crystalline architecture that both hybrid inorganic-organic compounds is stabilized by various non-covalent interactions such as N-H⋯O, C-H⋯O, O-H⋯O etc.

  5. Black TiO2 for solar hydrogen conversion

    Bin Wang


    Full Text Available Titanium dioxide (TiO2 has been widely investigated for photocatalytic H2 evolution and photoelectrochemical (PEC water splitting since 1972. However, its wide bandgap (3.0–3.2 eV limits the optical absorption of TiO2 for sufficient utilization of solar energy. Blackening TiO2 has been proposed as an effective strategy to enhance its solar absorption and thus the photocatalytic and PEC activities, and aroused widespread research interest. In this article, we reviewed the recent progress of black TiO2 for photocatalytic H2 evolution and PEC water splitting, along with detailed introduction to its unique structural features, optical property, charge carrier transfer property and related theoretical calculations. As summarized in this review article, black TiO2 could be a promising candidate for photoelectrocatalytic hydrogen generation via water splitting, and continuous efforts are deserved for improving its solar hydrogen efficiency.

  6. 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.

  7. Catalysis by Using TiO2 Nanoparticles and Nanotubes

    Chien Shu-Hua; Kuo Ming-Chih; Liou Yuh-Cherng


    catalyst-pellet, Pt/TiO2 or Pt/TiO2-nanotube, was placed inside the cell.Then, 60 torr of hydrogen was introduced into the cell and subsequently the temperature was programmed to increase from room temperature to 300℃ at a constant heating rate of 5℃/min.For Pt/TiO2, an IR peak at 2083 em-1 started to appear at 200℃ with a maximum intensity at 250℃ and then decreasing as temperature increased. The 2083 em-1 IR peak corresponds to the linearly adsorption of CO on the well-dispersed Pt sites. Simultaneously, the IR bands of gaseous methane at 3016 em-1 started to appear at 225℃ and the peak intensity increased with temperature. The results reveal that Pt/TiO2 can adsorb gaseous CO2 and further catalyzes the reduction of CO2 by H2 through the intermediate CO, which further produces gaseous methane. While for the Pt/TiO2-nanotube catalyst, methane was produced at relatively low temperature, 100℃, and it catalyzed the direct conversion of CO2 to CH4. The absence of intermediate CO-adsorption signals durinng the temperature programmed process indicates that the prepared TiO2 nanotube-supported nanosize Pt possesses a potent capability for CO2 adsorption and highly catalytic activity in the hydrogenation of CO2, and was superior to the conventional Pt/TiO2 catalyst. The catalytic activity of Pt/TiO2-nanotube was indeed significantly enhanced by the high surface area of TiO2-nanotubes.Details will be discussed.

  8. Morphological and humidity sensing characteristics of SnO2–CuO, SnO2–Fe2O3 and SnO2–SbO2 nanocooxides

    B C Yadav; Preeti Sharma; P K Khanna


    This paper reports the synthesis of SnO2–CuO, SnO2–Fe2O3 and SnO2–SbO2 composites of nano oxides and comparative study of humidity sensing on their electrical resistances. CuO, Fe2O3 and SbO2 were added within base material SnO2 in the ratio 1 : 0.25, 1 : 0.50 and 1 : 1. Characterizations of materials were done using SEM and XRD. SEM images show the surface morphology and X-ray diffraction reveals the nanostructure of sensing materials. The pellets were annealed at 200, 400 and 600°C respectively for 3 h and after each step of annealing, observations were carried out. It was observed that as relative humidity (%RH) increases, there was decrease in the resistance of pellet for the entire range of RH. Results were found reproducible. SnO2–SbO2 shows maximum sensitivity for humidity (12 M/%RH) among other composites.

  9. Ferroelectricity-modulated resistive switching in Pt/Si:HfO2/HfO2-x /Pt memory

    Ran, Jiang; Xianghao, Du; Zuyin, Han


    It is investigated for the effect of a ferroelectric Si:HfO2 thin film on the resistive switching in a stacked Pt/Si:HfO2/highly-oxygen-deficient HfO2-x /Pt structure. Improved resistance performance was observed. It was concluded that the observed resistive switching behavior was related to the modulation of the width and height of a depletion barrier in the HfO2-x layer, which was caused by the Si:HfO2 ferroelectric polarization field effect. Reliable switching reproducibility and long data retention were observed in these memory cells, suggesting their great potential in non-volatile memories applications with full compatibility and simplicity. Project supported by the National Natural Science Foundation of China (No. 11374182), the Natural Science Foundation of Shandong Province (No. ZR2012FQ012), and the Jinan Independent Innovation Projects of Universities (No. 201303019).

  10. Graphene oxide-MnO2 nanocomposite for supercapacitor application

    Muhammed Shafi, P.; Vishal, Jose K.; Chandra Bose, A.


    Increased depletion of fossil fuels along with global warming and climate change made the society to think about alternate green and sustainable energy sources and better energy storage devices. Extensive research has been performed on the development of solar cells, fuel cells, Lithium- ion battery and supercapacitors to combat the green house effect and its consequences, and to meet the increased energy crisis. Supercapacitors, also known as electrochemical capacitors are gained a great attention because of their pulse power supply, long cycle life (>100,000), simple principle and high dynamic of charge propagation. Its greater power density than lithium- ion battery and much larger energy density than conventional capacitors brought super capacitors to a promising energy storage device to meet the increased energy demands. Here we demonstrate supercapacitor electrode materials with graphene oxide (electric double layer capacitor) and α-MnO2 nanomaterial (pseudo-capacitor), as well as composite of these materials, which means that the bulk of the material undergoes a fast redox reaction to provide the capacitive response and they exhibit superior specific energies in addition to the carbon-based supercapacitors (double-layer capacitors). A simple soft chemical route is utilized to synthesize graphene oxide, α-MnO2 and graphene oxide-MnO2 composite. The phase and the structure of the synthesized materials are studied using X-ray diffractometry (XRD). The functional group and the presence of impurities are understood from Fourier transform infrared (FTIR) spectra. The capacitive properties of the graphene oxide, graphene oxide - MnO2 nanocomposite and α-MnO2 are tested with the help of cyclic voltammetry (CV) and galvanostatic charge - discharge techniques using 1 M Na2SO4 in aqueous solution as electrolyte. It was found that graphene oxide - MnO2 nanocomposite shows better electrochemical behaviour compared to individual graphene oxide and α-MnO2 nanomaterial.

  11. Preparation of a Waveguide Array in Flame Hydrolysis Deposited GeO2-SiO2 Glasses by Excimer Laser Irradiation

    吴远大; 邢华; 张乐天; 李爱武; 于永森; 张玉书


    SiO2 glass films doped with GeO2 were prepared by the flame hydrolysis deposition method, then annealed at 1200. C. After exposure to high pressure hydrogen, the as-deposited films were irradiated with excimer laser pulses operated at 248nm. The induced refractive index change (the growth of index change was 0.33%) was measured by a spectroscopic ellipsometer. A waveguide array has been written in the film by irradiation through a phase mask.

  12. Detection of pulpal blood flow in vivo with pulse oximetry in dogs

    Jessica eRiehl


    Full Text Available Objective: The aim of the present study was to investigate the ability of pulse oximetry to detect blood flow within the canine tooth of dogs. Materials and methods: Dogs aged 18-138 months presenting for oral treatment and meeting the inclusion criteria underwent pulse oximetry evaluation of at least one canine tooth. Oxygen saturation (SpO2 and pulse rate values were acquired from vital canine teeth of 38 clinical patients (representing 40 total teeth with a hand-held pulse oximeter and compared to a control area. SpO2 values from the tooth and control area were recorded every 5 seconds for three 60-second intervals. The sensors were repositioned after each 60-second interval. Results: The vital teeth consistently recorded SpO2 values significantly lower than the control area. The mean vital tooth SpO2 was 85.9% (median = 87%; SD = 8.6 and the mean control area SpO2 was 97.7% (median = 98%; SD = 1.8. An age-related significant difference was noted in vital tooth SpO2 values.Conclusions: In conclusion, the present data supports the possible use of pulse oximetry to detect blood flow in canine teeth. However, there was no significant correlation between SpO2 values in the vital tooth and in the control areas. Additionally, the results were not definitive and validation of the modality with additional studies of non-vital canine teeth is needed before clinical use can be recommended.

  13. Mechanical Properties of ZrO2 Ceramic Stabilized by Y2O3 and CeO2


    ZrO2 ceramic was made from evenly dispersed (Y,Ce)-ZrO2 powder with different compositions,which was prepared by the chemical coprecipitation, and stabilized by compound additions through appropriate techniques.And its mechanical property that is related to the phase content and its microstructure was studied by X-ray diffraction(XRD),scan electron microscope(SEM).The results show that Y2O3 has stronger inhibition to the growth of ZrO2 crystal than CeO2 has.Therefore,within an appropriate composition range of Y2O3 and CeO2,the higher the content of Y2O3,the lower the content of CeO2,the smaller ZrO2 crystal.Combining this feature and the stabilization technique with complex additions instead of simple addition,ZrO2 ceramic with high density and excellent mechanical properties can be made under normal conditions. It is concluded that the improvement of mechanical properties originates from the toughening of microcrack,phase transformation and the effect of grain evulsions.

  14. A promising electrode material modified by Nb-doped TiO2 nanotubes for electrochemical degradation of AR 73.

    Xu, Li; Liang, Gaorui; Yin, Ming


    A distinctive SnO2Sb electrode with highly ordered Nb doped TiO2 nanotubes sheet as a new substrate, obtained by NbTi alloy anodization, is prepared by pulse electrochemical deposition for the first time as electrocatalytic oxidation anode for wastewater treatment. The novel electrode has a larger surface area and smaller crystallite particles than conventional SnO2Sb electrodes as obtained from the analysis of scanning electron microscopy and X-ray diffraction. Compared with Ti/SnO2Sb and Ti/TiO2-NTs/SnO2Sb prepared by pulse electrochemical deposition, the electrode modified by NbTiO2-NTs has the higher oxygen evolution potential of 2.29 V (vs. Ag/AgCl), and the lower charge transfer resistance, which decreased by 65% and 79%. The service lifetime of NbTi/NbTiO2-NTs/SnO2Sb is 4.9 times longer than that of Ti/SnO2Sb and 1.9 times longer than that of Ti/TiO2-NTs/SnO2Sb. The new electrode is proved to have an excellent electrochemical oxidation and degradation ability using Acid Red 73 as a target organic pollutant. The AR 73 removal, chemical oxygen demand removal and kinetic rate constant are increased obviously due to the introduction of NbTiO2-NTs. Besides, the energy consumption reduces 37.2% and 31.4% in contrast with Ti/SnO2Sb and Ti/TiO2-NTs/SnO2Sb. Hence, the Ti/SnO2Sb modified by NbTiO2-NTs is a very promising anode material for the electrochemical treatment of dye wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. 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...

  16. Pulsed Cathodoluminescence Spectra of Solid Oxides with Low Concentrations of Optically-Active Impurities

    Kozlov, V A; Pestovskii, N V; Petrov, A A; Savinov, S Yu; Zavartsev, Yu D; Zavertyaev, M V; Zagumenniy, A I


    Pulsed cathodoluminescence (PCL) spectra of ultra-pure SiO2, GeO2, SnO2, TiO2, La2O3, Y2O3, Sc2O3, CaCO3 powders and {\\alpha}-quartz, Ca:YVO4, LiNbO3 and Sc:LiNbO3 crystals were studied under the same experimental conditions. It was found that PCL spectra of SiO2, SnO2, GeO2, TiO2, La2O3 and CaCO3 powders contain a common band with maximum intensity at 500 nm, PCL spectra of samples Y2O3, Sc2O3, PbWO4 and Ca:YVO4 contain a common band at 490 nm and PCL spectra of LiNbO3 and Sc:LiNbO3 crystals contain a common band at 507 nm. It was found that the average intensity of the PCL spectra and position of the maximum intensity of these common bands depend on the type of a band gap transition of the material. We suppose that these common bands have the same origin in PCL spectra of all the materials studied and are related to recombination of O2--O-oxygen complexes. These complexes appear in the vicinities of anionic and cationic vacancies, where the geometry and orientation of coordination polyhedrons are violated d...

  17. Electrical Conductivity of TiO2 Nanotubes

    Tighineanu, Alexei


    Nanostructured TiO2 is a material with high potential in a wide range of applications (water splitting, solar cells, biomedical applications as implant coatings and drug-delivery, batteries, sensors, electro-chromic devices and membranes). Nano-TiO2 is a material which properties depend mostly on surface-related processes. Therefore, detailed analysis of electronic properties of such material is of crucial importance for most of applications of nano-TiO2. At the beginning of the study, a ...

  18. Toxicity assessment of textile effluents treated by advanced oxidative process (UV/TiO2 and UV/TiO2/H2O2) in the species Artemia salina L.

    Garcia, Juliana Carla; de Souza Freitas, Thábata Karoliny Formicoly; Palácio, Soraya Moreno; Ambrósio, Elizangela; Souza, Maísa Tatiane Ferreira; Santos, Lídia Brizola; de Cinque Almeida, Vitor; de Souza, Nilson Evelázio


    Textile industry wastes raise a great concern due to their strong coloration and toxicity. The objective of the present work was to characterize the degradation and mineralization of textile effluents by advanced oxidative processes using either TiO(2) or TiO(2)/H(2)O(2) and to monitor the toxicity of the products formed during 6-h irradiation in relation to that of the in natura effluent. The results demonstrated that the TiO(2)/H(2)O(2) association was more efficient in the mineralization of textile effluents than TiO(2), with high mineralized ion concentrations (NH (4) (+) , NO (3) (-) , and SO (4) (2-) ) and significantly decreased organic matter ratios (represented by the chemical oxygen demand and total organic carbon). The toxicity of the degradation products after 4-h irradiation to Artemia salina L. was not significant (below 10 %). However, the TiO(2)/H(2)O(2) association produced more toxicity under irradiation than the TiO(2) system, which was attributed to the increased presence of oxidants in the first group. Comparatively, the photogenerated products of both TiO(2) and the TiO(2)/H(2)O(2) association were less toxic than the in natura effluent.

  19. Electrochemical Behavior of TiO2 Nanoparticle Doped WO3 Thin Films

    Suvarna R. Bathe


    Full Text Available Nanoparticle TiO2 doped WO3 thin films by pulsed spray pyrolysis technique have been studied on fluorine tin doped (FTO and glass substrate. XRD shows amorphous nature for undoped and anatase phase of TiO2 having (101 plane for nanoparticle TiO2 doped WO3 thin film. SEM shows microfibrous reticulated porous network for WO3 with 600 nm fiber diameter and nanocrystalline having size 40 nm for TiO2 nanoparticle doped WO3 thin film. TiO2 nanoparticle doped WO3 thin film shows ~95% reversibility due to may be attributed to nanocrystalline nature of the film, which helpful for charge insertion and deinsertion process. The diffusion coefficient for TiO2 nanoparticle doped WO3 film is less than undoped WO3.

  20. Bipolar Resistive Switching Characteristics of HfO2/TiO2/HfO2 Trilayer-Structure RRAM Devices on Pt and TiN-Coated Substrates Fabricated by Atomic Layer Deposition

    Zhang, Wei; Kong, Ji-Zhou; Cao, Zheng-Yi; Li, Ai-Dong; Wang, Lai-Guo; Zhu, Lin; Li, Xin; Cao, Yan-Qiang; Wu, Di


    The HfO2/TiO2/HfO2 trilayer-structure resistive random access memory (RRAM) devices have been fabricated on Pt- and TiN-coated Si substrates with Pt top electrodes by atomic layer deposition (ALD). The effect of the bottom electrodes of Pt and TiN on the resistive switching properties of trilayer-structure units has been investigated. Both Pt/HfO2/TiO2/HfO2/Pt and Pt/HfO2/TiO2/HfO2/TiN exhibit typical bipolar resistive switching behavior. The dominant conduction mechanisms in low and high resistance states (LRS and HRS) of both memory cells are Ohmic behavior and space-charge-limited current, respectively. It is found that the bottom electrodes of Pt and TiN have great influence on the electroforming polarity preference, ratio of high and low resistance, and dispersion of the operating voltages of trilayer-structure memory cells. Compared to using symmetric Pt top/bottom electrodes, the RRAM cells using asymmetric Pt top/TiN bottom electrodes show smaller negative forming voltage of -3.7 V, relatively narrow distribution of the set/reset voltages and lower ratio of high and low resistances of 102. The electrode-dependent electroforming polarity can be interpreted by considering electrodes' chemical activity with oxygen, the related reactions at anode, and the nonuniform distribution of oxygen vacancy concentration in trilayer-structure of HfO2/TiO2/HfO2 on Pt- and TiN-coated Si. Moreover, for Pt/HfO2/TiO2/HfO2/TiN devices, the TiN electrode as oxygen reservoir plays an important role in reducing forming voltage and improving uniformity of resistive switching parameters.

  1. High-P behavior of anorthite composition and some phase relations of the CaO-Al2O3-SiO2 system to the lower mantle of the Earth, and their geophysical implications

    Liu, Xi; Ohfuji, Hiroaki; Nishiyama, Norimasa; He, Qiang; Sanehira, Takeshi; Irifune, Tetsuo


    Multianvil experiments with long experimental durations have been made with the anorthite composition CaAl2Si2O8at pressure-temperature (P-T) conditions of 14-25 GPa and 1400-2400°C. At subsolidus conditions, these experiments demonstrated three phase assemblages, grossular (Gr) + kyanite (Ky) + stishovite (St) at ˜14 GPa, Gr + calcium-alumino-silicate phase (CAS) + St at ˜18 GPa, and CAS + CaSiO3-perovskite (CaPv) + St at above ˜20 GPa, which are related by the reactions Gr + Ky = CAS + St and Gr + St = CAS + CaPv. Following the method of Schreinemakers, we combined our data with the literature data to deduce aP-Tphase diagram for a portion of the CaO-Al2O3-SiO2system at subsolidus conditions, which subsequently helped to solve some long-lasting discrepancies in the high-Pbehavior of the compositions of anorthite and grossular. The crystal chemistry of the CAS and CaPv solid solutions was examined, and new substitution mechanisms were firmly established. Along the solidus, the melting reaction at ˜14 GPa is peritectic while that at ˜22 GPa is eutectic. For both pressures, St is the first phase to melt out and the melt is generally andesitic. For the An composition, its density starts to be significantly higher than the density of pyrolite at ˜2.5 GPa, a much lower pressure than that for the Or, Ab or Qtz composition (˜7.5-10 GPa), so that the An-enriched continental crust material should readily plunge into the upper mantle.

  2. 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.

  3. The luminescent carbon nanoparticles with controllable oxygen-related functional groups prepared by pulsed laser ablation in water

    Zhang, Jun; Gan, Zhixing; Hu, Guang; Tang, Yalu; Zhou, Lei; Jiang, Qingsong; Cui, Yu


    Fluorescent carbon nanoparticles (CNPs) are obtained via pulsed laser ablation (PLA) of a carbon target immersed in deionized water. By tuning the laser power for PLA, the density of oxygen-related functional groups at the surfaces is controllable. While the crystallinities, sizes, morphologies and defects are nearly retained, the prepared CNPs show blue fluorescence under UV exposure and the photoluminescence (PL) intensities of the C-dots are dependent on the oxygen contents. Accordingly, the PL is attributed to the transition of electronic states caused by oxygen-related functional groups. This work sheds new light on the PL mechanism of CNPs and proposes an efficient way to prepare CNPs with controllable oxygen-related functional groups.


    Is Fatimah


    Full Text Available Catalytic conversion of citronellal to isopulegol over TiO2/SiO2-montmorillonite catalyst was studied for citronellal isolated from Cymbopogon leaf oil. The role of physico-chemical characteristics of montmorillonite and SiO2-montmorillonit catalyst on total conversion, activity and selectivity to produce isopulegol was studied. Activity test was conducted for citronellal cyclication for 4 hour. The total conversion, catalyst activity and catalyst selectivity to produce isopulegol were evaluated based on product composition obtained by GC-MS analysis. The experimental result showed that TiO2/SiO2-montmorillonite plays role in the increase of total conversion significantly from 87.80% over SiO2-montmorillonit and 85.38% over natural montmorillonite become 95.53%. Total conversion and selectivity of the catalyst to produce isopulegol increase could be related to Lewis acidity of TiO2/SiO2-montmorillonite, and also specific surface area enhancement. However, in the range of 1:1.25 to 1:5.0 catalyst to citronellal mass ratio, there was no influence on total conversion and selectivity to produce isopulegol. This may be caused by dominant influence of Lewis acidity compared to other physico-chemical characteristic of material. Kinetics study of the reaction showed that TiO2 dispersion on SiO2-montmorillonite almost doubles the reaction rate constant with the factor of 1.955. Konversi katalitik sitronelal menjadi isopulegol menggunakan katalis TiO2/SiO2-montmorillonit dipelajari terhadap sitronelal hasil isolasi minyak daun sereh. Peranan karakter fisikokimiawi material katalis montmorillonit alam dan SiO2-montmorillonit terhadap konversi total, aktivitas dan selektivitas dalam pembentukan isopulegol dipelajari. Uji aktivitas katalis dilakukan pada reaksi siklisasi sitronelal selama 4 jam. Konversi total, aktivitas katalis dan selektivitas terhadap isopulegol dihitung berdasar perubahan komposisi hasil reaksi yang ditentukan menggunakan GC-MS. Hasil

  5. SrO-Gd2O3-TiO2体系的相关系与电性质%Phase Relations and Electrical Properties in the System SrO-Gd2O3-TiO2

    郑朝贵; 王双艳; 杨华铨


    @@氧化物陶瓷材料有一系列特殊性质,愈来愈引起人们的重视,作为系列寻找与研究多组份氧化物陶瓷新材料工作之一,我们测定了SrO-Gd2O3-TiO2体系的相关系与电性质,该体系未见文献报道。 寻找多元陶瓷新材料的方法,一般说来有两种:一种是尝试法(或筛选法);另一种是利用相图测定它们的相关系,系统地合成与寻找新的陶瓷相(或固溶体),并测定它们的性质(如电性质),当获得较好性质的相后,可以进一步添加少量其它元素以改性。 相关二元体系的相关系文献已有报道。TiO2-SrO体系Cocco[1]已有报道,作者[2]曾重新考察在1200℃时只存在SrTiO3、Sr3Ti2O7和Sr2TiO4三个化合物;Waring[3]报道Gd2O3-TiO2体系内只存在2个化合物Gd2TiO5和Gd2Ti2O7,本文考察结果与文献一致;SrO-Gd2O3体系相图未见文献报道,但Barry等[4]报道有两个化合物SrGd2O4和SrGd4O7,本文在1200G系统考察二元体系的相关系后,发现仅存在SrGd2O4相。

  6. Nutritional approaches and health-related properties of plant foods processed by high pressure and pulsed electric fields.

    Sánchez-Moreno, Concepción; de Ancos, Begoña; Plaza, Lucía; Elez-Martínez, Pedro; Cano, M Pilar


    Consumers are more and more concerned about the nutritional and health-related characteristics of fruits and vegetables, as well as the safety of the food they eat. The processing of foods is becoming more sophisticated and diverse in response to the growing demand for quality foods. Consumers today expect food products to provide fresh-like appearance, convenience, variety, appropriate shelf-life and caloric content, reasonable cost, environmental soundness, high nutritional and functional quality. Nonthermal processing of fruit and vegetable has been revealed as a useful tool to extend their shelf-life and quality as well as to preserve their nutritional and functional characteristics. In the last ten years, there has been an increasing interest in nonthermal technologies as high pressure processing (HPP) and pulsed electric fields (PEF) to preserve fruit and vegetable products without the quality and nutritional damage caused by heat treatments. This review will contribute to inform many of the studies conducted to obtain a better understanding on the effects of some of these nonthermal processing technologies (high hydrostatic pressure and pulsed electric fields) applied to vegetable foods on their nutritional value and bioactive compounds related to health, including the results on micronutrient bioavailability studies and oxidative stress and inflammation biomarkers. These studies could contribute to select the most appropriate processing parameters to obtain safe, high-quality, nutritional, and functional vegetable food.

  7. Superplastic forming of Ti6Al4V alloy using ZrO_2-TiO_2 ceramic die with adjustable linear thermal expansion coefficient

    JIANG Shao-song; ZHANG Kai-feng


    Firstly, the relation between the coefficient of thermal expansion(CTE) and the volume fraction of TiO_2 was investigated, and also the influence of relative density of ceramic on the CTE was studied. The results show that the volume fraction, of TiO_2 and the relative density both make influence on the CTE of ZrO_2-TiO_2 ceramic. According to the results, the ZrO_2-TiO_2(volume fraction of TiO_2 is 27%) ceramic die with the similar CTE (8.92×10~(-6)℃~(-1)) to Ti6Al4V was fabricated. Secondly, to evaluate the dimensional accuracy of the workpiece superplastically formed, the Ti6Al4V impression experiment was performed. The result shows that the dimensional inaccuracy of workpieee is 0.003. Thirdly, in order to evaluate the practicability, the experiment of superplastic forming Ti6Al4V using ZrO_2-TiO_2 cylinder ceramic die was carried out. The Ti6Al4V cylinder shows good shape retention and surface quality, and high dimensional accuracy. The ceramic dies seem to be adequate for superplastic forming the high accuracy Ti6Al4V,and the trials have confirmed the potential of the ZrO2-TiO2 ceramic die.

  8. 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.

  9. Exploring the structural and magnetic properties of TiO2/SnO2 core/shell nanocomposite: An experimental and density functional study

    Chetri, Pawan; Basyach, Priyanka; Choudhury, Amarjyoti


    TiO2/SnO2 core/shell nanocomposite is prepared via a simple sol-gel method and the properties are compared with the individual TiO2 (core) and SnO2 (shell). The corresponding characterizations are carried out in terms of structural and magnetic properties of TiO2/SnO2, TiO2 and SnO2 nanosystems. Structural properties are studied via XRD, TEM, Raman spectroscopy, FTIR and XPS. Magnetic characterization is performed by measuring Moment vs. Applied Field for all the samples and Moment vs. Temperature for TiO2/SnO2 core/shell nanocomposite. We also went for a better insight with the help of theoretical measures. First principle calculations have been executed using “Density Functional Theory” (DFT)-based MedeA VASP package to compare the results of TiO2/SnO2 with TiO2 (1 1 0) and SnO2 (1 1 0) surface calculations and its effect on the magnetic nature of the specific nanoparticles. XRD, RAMAN and FTIR gave indirect evidence of formation of core shell nanostructure while TEM micrographs provide the direct evidence of formation of core shell nanostructure. The magnetic study shows a higher saturation magnetization for the core/shell nanostructure compared to pristine TiO2 and SnO2. In this report, we have attempted to relate this experimental observation with the results of the first principle calculations.

  10. The accuracy of pulse oximetry in emergency department patients with severe sepsis and septic shock: a retrospective cohort study

    Lord Jason A


    Full Text Available Abstract Background Pulse oximetry is routinely used to continuously and noninvasively monitor arterial oxygen saturation (SaO2 in critically ill patients. Although pulse oximeter oxygen saturation (SpO2 has been studied in several patient populations, including the critically ill, its accuracy has never been studied in emergency department (ED patients with severe sepsis and septic shock. Sepsis results in characteristic microcirculatory derangements that could theoretically affect pulse oximeter accuracy. The purposes of the present study were twofold: 1 to determine the accuracy of pulse oximetry relative to SaO2 obtained from ABG in ED patients with severe sepsis and septic shock, and 2 to assess the impact of specific physiologic factors on this accuracy. Methods This analysis consisted of a retrospective cohort of 88 consecutive ED patients with severe sepsis who had a simultaneous arterial blood gas and an SpO2 value recorded. Adult ICU patients that were admitted from any Calgary Health Region adult ED with a pre-specified, sepsis-related admission diagnosis between October 1, 2005 and September 30, 2006, were identified. Accuracy (SpO2 - SaO2 was analyzed by the method of Bland and Altman. The effects of hypoxemia, acidosis, hyperlactatemia, anemia, and the use of vasoactive drugs on bias were determined. Results The cohort consisted of 88 subjects, with a mean age of 57 years (19 - 89. The mean difference (SpO2 - SaO2 was 2.75% and the standard deviation of the differences was 3.1%. Subgroup analysis demonstrated that hypoxemia (SaO2 2 was in the 90-93% range the SaO2 was Conclusions Pulse oximetry overestimates ABG-determined SaO2 by a mean of 2.75% in emergency department patients with severe sepsis and septic shock. This overestimation is exacerbated by the presence of hypoxemia. When SaO2 needs to be determined with a high degree of accuracy arterial blood gases are recommended.

  11. Treatment of Remazol Brilliant Blue Dye Effluent by Advanced Photo Oxidation Process in TiO2/UV and H2O2/UV reactors

    M. Verma


    Full Text Available Advanced oxidation processes involving TiO2/UV and H2O2/UV were evaluated for their potential use in decolorization of textile dye effluents. A coil photo reactor, consisting of UV radiation source and a spiral coil coated with TiO2, was used to treat synthetic effluent of Remazol Brilliant Blue dye. The TiO2 coating was performed using the sol-gel technique. The effects of UV radiation, TiO2 coatings and dye concentration were studied and the results were compared to dye treatment involving H2O2. The maximum dye removal efficiencies were 7.3, 12.2 and 12.5 % for uncoated, single coat and dual coat of TiO2, respectively. The decolorization efficiency was inversely related to dye concentration of the effluent. The treatments with UV only, TiO2 only, UV+TiO2, H2O2 only and UV+H2O2 resulted in color reduction of 7.6, 2.3, 12.5, 4.1 and 99.9 % respectively. The maximum decolorization occurred in ≤ 100 min in all cases. The temperature varied from 29.2 to 54.7°C for UV+TiO2 treatment and no change in reactor temperature was observed when UV was not used.

  12. Ultrafast Multiphoton Pump-probe Photoemission Excitation Pathways in Rutile TiO2(110)

    Argondizzo, Adam; Cui, Xuefeng; Wang, Cong; Sun, Huijuan; Shang, Honghui; Zhao, Jin; Petek, Hrvoje


    We investigate the spectroscopy and photoinduced electron dynamics within the conduction band of reduced rutile TiO2(110) surface by multiphoton photoemission (mPP) spectroscopy with wavelength tunable ultrafast (!20 fs) laser pulse excitation. Tuning the mPP photon excitation energy between 2.9 and 4.6 eV reveals a nearly degenerate pair of new unoccupied states located at 2.73 ± 0.05 and 2.85 ± 0.05 eV above the Fermi level, which can be analyzed through the polarization and sample azimuthal orientation dependence of the mPP spectra. Based on the calculated electronic structure and optical transition moments, as well as related spectroscopic evidence, we assign these resonances to transitions between Ti 3d bands of nominally t2g and eg symmetry, which are split by crystal field. The initial states for the optical transition are the reduced Ti3+ states of t2g symmetry populated by formation oxygen vacancy defects, which exist within the band gap of TiO2. Furthermore,we studied the electron dynamics within the conduction band of TiO2 by three-dimensional time-resolved pump-probe interferometric mPP measurements. The spectroscopic and time-resolved studies reveal competition between 2PP and 3PP processes where the t2g-eg transitions in the 2PP process saturate, and are overtaken by the 3PP process initiated by the band-gap excitation from the valence band of TiO2.

  13. Relations between diabetes, blood pressure and aortic pulse wave velocity in haemodialysis patients

    Peters, Christian Daugaard; Kjærgaard, Krista Dybtved; Dzeko, Mirela;

    Diabetes (DM) is common in haemodialysis (HD) patients and affects both blood pressure (BP) and arterial stiffness. Carotid femoral pulse wave velocity (PWV) reflects the stiffness of the aorta and is regarded as a strong risk factor for cardiovascular (CV) mortality in HD patients. However, PWV...... is highly influenced by the BP-level. Higher PWV-values among HD patients with DM could reflect a higher BP-level rather than increased arterial stiffness. The aim of this study was to investigate the effect of DM on BP and PWV in a group of HD patients. BP and PWV were measured in 66 HD patients without DM...... (HD) and 32 HD patients with DM (HD+DM). The SphygmoCor system was used for estimation of PWV. HD-duration, age, gender and BP medication were similar in the two groups. Mean DM-duration was 23±11 years and 25(78%) had type 2 DM. HD+DM had higher BMI (26±5 vs. 29±5 kg/m2, p=0.02), systolic BP (142...

  14. Oxidation of core–shell MoO2–MoS2 nanoflakes in different O2 ambience

    Kumar, Prabhat; Singh, Megha; Reddy, G. B.


    Oxidation of MoO2/MoS2 core–shell nanoflakes (NFs) has been investigated in different oxidation ambients i.e. oxygen (O2) gas and its plasma. Core–shell nanoflakes are oxidized at temperatures varying from 150 °C to 450 °C and the effect of oxidation temperature on the structural and morphological changes of nanoflakes are investigated systematically. High-resolution transmission electron microscopy (TEM) images show that shell of nanoflake is oxidized with varying thicknesses and strongly depending upon the temperature and ambience. X-ray diffraction (XRD) and Raman analysis revealed the formation of MoO3 at low temperature (⩽150 °C) in O2 plasma. Whereas, in O2 gas at a relatively higher temperature (⩾350 °C). Scanning electron microscopy (SEM) results show noticeable changes in the morphology as deformation of nanoflakes after oxidation. X-ray photoelectron spectroscopy (XPS) revealed, oxidizing in O2-plasma led to multiple oxidation states of Mo (4+, 5+, and 6+) and S (2‑, 6+). It is evident that the extent of oxidation of MoS2 shell is higher in plasma due to reactive species of oxygen (O+, \\text{O}2+ , O*, etc), as compared to O2 gas.

  15. Structure of glassy GeO2.

    Salmon, Philip S; Barnes, Adrian C; Martin, Richard A; Cuello, Gabriel J


    The full set of partial structure factors for glassy germania, or GeO2, were accurately measured by using the method of isotopic substitution in neutron diffraction in order to elucidate the nature of the pair correlations for this archetypal strong glass former. The results show that the basic tetrahedral Ge(O1/2)4 building blocks share corners with a mean inter-tetrahedral Ge-Ô-Ge bond angle of 132(2)°. The topological and chemical ordering in the resultant network displays two characteristic length scales at distances greater than the nearest neighbour. One of these describes the intermediate range order, and manifests itself by the appearance of a first sharp diffraction peak in the measured diffraction patterns at a scattering vector kFSDP≈1.53 Å(-1), while the other describes so-called extended range order, and is associated with the principal peak at kPP = 2.66(1) Å(-1). We find that there is an interplay between the relative importance of the ordering on these length scales for tetrahedral network forming glasses that is dominated by the extended range ordering with increasing glass fragility. The measured partial structure factors for glassy GeO2 are used to reproduce the total structure factor measured by using high energy x-ray diffraction and the experimental results are also compared to those obtained by using classical and first principles molecular dynamics simulations.

  16. Study on the thermal stability and electrical properties of the high-k dielectrics (ZrO2)x(SiO2)1-x


    (ZrO2)x(SiO2)1-x (Zr-Si-O) films with different compositions were deposited on p-Si(100) substrates by using pulsed laser deposition technique. X-ray photoelectron spectra (XPS) showed that these films remained amorphous after annealing at 800℃ with RTA process in N2 for 60 s. The XPS spectra indi- cated that Zr-Si-O films with x=0.5 suffered no obvious phase separation after annealing at 800℃, and no interface layer was formed between Zr-Si-O film and Si substrate. While Zr-Si-O films with x >0.5 suffered phase separation to precipitate ZrO2 after annealing under the same condition, and SiO2 was formed at the interface. To get a good interface between Zr-Si-O films and Si substrate, Zr-Si-O films with bi-layer structure (ZrO2)0.7(SiO2)0.3/(ZrO2)0.5(SiO2)0.5/Si was deposited. The electrical properties showed that the bi-layer Zr-Si-O film is of the lowest equivalent oxide thickness and good interface with Si substrate.

  17. Mass-Analyzed Threshold Ionization of LaO2

    Wu, Lu; Zhang, Changhua; Krasnokutski, Sergiy; Yang, Dong-Sheng


    Lanthanum oxide, LaO2, is produced in a pulsed laser-vaporization metal-cluster source and studied by mass-analyzed threshold ionization (MATI) spectroscopy. From the MATI spectrum, the adiabatic ionization energy of LaO2 is determined to be 40134 (5) Cm-1 or 4.976 (6) eV, and La+-O stretching and O-La+-O bending frequencies are measured as 656 and 120 Cm-1. The measured ionization energy is about 3.0 eV lower than the value predicted by recent high-level ab initio calculations. In this talk, we will discuss the discrepancy between the experiment and theory and the electronic transition observed in our experiment. T. K. Todorova, I. Infante, L. Gagliardi, and J. M. Dyke, J. Phys. Chem. A 112, 7825 (2008).

  18. Photodegradation of Pollutants in Air: Enhanced Properties of Nano-TiO2Prepared by Ultrasound

    Gialanella Stefano


    Full Text Available Abstract Nanocrystalline TiO2samples were prepared by promoting the growth of a sol–gel precursor, in the presence of water, under continuous (CW, or pulsed (PW ultrasound. All the samples turned out to be made of both anatase and brookite polymorphs. Pulsed US treatments determine an increase in the sample surface area and a decrease of the crystallite size, that is also accompanied by a more ordered crystalline structure and the samples appear to be more regular and can be considered to contain a relatively low concentration of lattice defects. These features result in a lower recombination rate between electrons and holes and, therefore, in a good photocatalytic performance toward the degradation of NO x in air. The continuous mode induces, instead, the formation of surface defects (two components are present in XPS Ti 2p3/2region and consequently yields the best photocatalyst. The analysis of all the characterization data seems to suggest that the relevant parameter imposing the final features of the oxides is the ultrasound total energypervolume (E tot/V and not the acoustic intensity or the pulsed/continuous mode.

  19. Characterization of RuO2+SnO2/Ti anodes with high SnO2-concentrations

    王欣; 唐电; 周敬恩


    Two SnO2 + RuO2/Ti anodes with high SnO2-concentrations were prepared by painting, sintering and annealing through a sol-gel technique. The microstructure, morphology and grain size of coatings and the electrochemical properties of the anodes were investigated by XRD, DTA, SEM, TEM and CV. It is demonstrated that the anodic coatings consist of solid solution (Sn, X)O2 (X represents Ru or Ti) phases. The average grain size of the coatings is about less than 30 nm. When the annealing temperature increases from 450 ℃ to 600 ℃, the solid solutions decompose. The crystal of the coating is equiaxial. The morphology of TiO2 + SnO2/Ti coatings is a mixture of mud-flat cracking with a kind of agglomerated structure.

  20. Composite Electrode SnO2/TiO2 for Dye-Sensitized Solar Cells

    Jiang Bin XIA; Fu You LI; Shu Ming YANG; Chun Hui HUANG


    Composite nanoporous electrode SnO2/TiO2 was fabricated for the dye sensitized solar cell (DSSC) with N3 (Cis-Ru). After introducing of TiO2, the open-circuit photovoltage (Voc) was higher than that of the pure SnO2 electrode, while short-circuit photocurrent (Isc) was varied with the ratio of the TiO2. Appropriate content of the TiO2 can be beneficial to the efficiency of the solar cell, and it gives negative impact on the composite electrode when the content of TiO2 is higher.

  1. α-PbO2-type high-pressure polymorph of GeO2

    Prakapenka, Vitali B.; Dubrovinsky, Leonid S.; Shen, Guoyin; Rivers, Mark L.; Sutton, Stephen R.; Dmitriev, V.; Weber, H.-P.; Le Bihan, T.


    We have studied the high pressure polymorphism of GeO2 at pressures up to 60 GPa and temperatures to ˜1800 K in a laser-heated diamond anvil cell. We have synthesized an α-PbO2-type (space group Pbcn) phase of GeO2 and demonstrated that it is the stable post-CaCl2-type (space group Pnnm) polymorph at pressures above 44 GPa. The α-PbO2-structured GeO2, with a bulk modulus of 256(5) GPa, is denser than CaCl2 type by 1.6% at 60 GPa. Our study shows that group-IV element dioxides (SiO2, GeO2, SnO2, and PbO2) have a common sequence of high-pressure structural transformations: rutile-type⇒CaCl2-type⇒α-PbO2-type.

  2. Investigation of response of high-temperature superconducting Bi sub 2 Sr sub 2 CaCu sub 2 O sub y bolometer at hard substrate on infrared laser pulses of permanent power and variable relative pulse duration

    Antonenko, S V; Korotkov, D P; Maltsev, S N


    A method for studying bolometric response of superconducting films to effect of a sequence of IR pulses of identical power and variable relative pulse duration using an optical rod was developed. A semiconductor laser was used as radiation source. Using the method suggested experiments on studying characteristics of a superconducting bolometer on the basis of Bi sub 2 Sr sub 2 CaCu sub 2 O sub y film on a MgO substrate were conducted. It was found that increase in pulse repetition frequency of IR laser in the range of 1-7 kHz brought about a decrease (by a factor of 2.5) of variable component of the bolometer response amplitude

  3. Effect of surface modification of low cost mesoporous SiO2 carriers on the properties of immobilized lipase.

    Zou, Bin; Hu, Yi; Cui, Fengjie; Jiang, Ling; Yu, Dinghua; Huang, He


    To investigate the surface effects of low cost mesoporous SiO2 on the properties of lipase, a series of modified mesoporous SiO2 was synthesized through various alkoxysilanes reacted with hydroxyl of SiO2 (C1-SiO2, C8-SiO2, C16-SiO2, SH-SiO2, Ph-SiO2, NH2-SiO2). Particularly, ionic liquids as novel alkoxysilane were synthesized and subjected to modify the low cost mesoporous SiO2 (CH3IL-SiO2 and COOHIL-SiO2). The porcine pancreas lipase (PPL) was immobilized on the prepared materials. The activity assay indicated that the activation of enzymatic activity site was benefit from the longer alkyl chain of alkoxysilane because of the growing hydrophobic nature. Nevertheless, the loading of lipase decreased from 69% for PPL-C1-SiO2 to 59% for PPL-C16-SiO2, reflecting the growing hydrophobic property limited the immobilization yield. The characteristic of alkoxysilane group (SH-SiO2, Ph-SiO2, NH2-SiO2) was another important factor to influence immobilization efficiency and enzymatic performance besides the alkyl chain length. The immobilization efficiency of PPL-SH-SiO2, PPL-Ph-SiO2 and PPL-NH2-SiO2 maintained at least 93%. Compared with conventional alkoxysilane, the activity of PPL-CH3IL-SiO2 improved to 2.60 folds of PPL-SiO2. The immobilization efficiency of PPL-COOHIL-SiO2 was up to 97% and the relative activity was above 62% after five recycles.

  4. Effects of water vapor in high vacuum chamber on the properties of HfO2 films

    Bo Ling; Hongbo He; Jianda Shao


    The influence of water vapor content in high vacuum chamber during the coating process on physical properties of HfO2 films was investigated. Coatings were deposited on BK7 substrates by electron beam evaporation and photoelectric maximum control method. An in situ residual gas analyzer (RGA) was used to monitor the residual gas composition in the vacuum chamber. The optical properties, microstructure,absorption and laser-induced damage threshold (LIDT) of the samples were characterized by Lambda 900 spectrophotometer, X-ray diffraction (XRD), surface thermal lensing (STL) technique and 1064-nm Qswitched pulsed laser at a pulse duration of 12 ns respectively. It was found that a cold trap is an effective equipment to suppress water vapor in the vacuum chamber during the pumping process, and the coatings deposited in the vacuum atmosphere with relatively low water vapor composition show higher refractive index and smaller grain size. Meanwhile, the higher LIDT value is corresponding to lower absorbance.

  5. Melting behavior of (Th,U)O2 and (Th,Pu)O2 mixed oxides

    Ghosh, P. S.; Kuganathan, N.; Galvin, C. O. T.; Arya, A.; Dey, G. K.; Dutta, B. K.; Grimes, R. W.


    The melting behaviors of pure ThO2, UO2 and PuO2 as well as (Th,U)O2 and (Th,Pu)O2 mixed oxides (MOX) have been studied using molecular dynamics (MD) simulations. The MD calculated melting temperatures (MT) of ThO2, UO2 and PuO2 using two-phase simulations, lie between 3650-3675 K, 3050-3075 K and 2800-2825 K, respectively, which match well with experiments. Variation of enthalpy increments and density with temperature, for solid and liquid phases of ThO2, PuO2 as well as the ThO2 rich part of (Th,U)O2 and (Th,Pu)O2 MOX are also reported. The MD calculated MT of (Th,U)O2 and (Th,Pu)O2 MOX show good agreement with the ideal solidus line in the high thoria section of the phase diagram, and evidence for a minima is identified around 5 atom% of ThO2 in the phase diagram of (Th,Pu)O2 MOX.

  6. WO3/CeO2/TiO2 Catalysts for Selective Catalytic Reduction of NO(x) by NH3: Effect of the Synthesis Method.

    Michalow-Mauke, Katarzyna A; Lu, Ye; Ferri, Davide; Graule, Thomas; Kowalski, Kazimierz; Elsener, Martin; Kröcher, Oliver


    WO3/CeO2/TiO2, CeO2/TiO2 and WO3/TiO2 catalysts were prepared by wet impregnation. CeO2/TiO2 and WO3/TiO2 showed activity towards the selective catalytic reduction (SCR) of NO(x) by NH3, which was significantly improved by subsequent impregnation of CeO/TiO2 with WO3. Catalytic performance, NH3 oxidation and NH3 temperature programmed desorption of wet-impregnated WO3/CeO2/TiO2 were compared to those of a flame-made counterpart. The flame-made catalyst exhibits a peculiar arrangement of W-Ce-Ti-oxides that makes it very active for NH3-SCR. Catalysts prepared by wet impregnation with the aim to mimic the structure of the flame-made catalyst were not able to fully reproduce its activity. The differences in the catalytic performance between the investigated catalysts were related to their structural properties and the different interaction of the catalyst components.

  7. Preparation and characterization of Pt-CeO2/C and Pt-TiO2/C electrocatalysts with improved electrocatalytic activity for methanol oxidation

    Hameed, R. M. Abdel; Amin, R. S.; El-Khatib, K. M.; Fetohi, Amani E.


    Pt-TiO2/C and Pt-CeO2/C electrocatalysts were synthesized by solid state reaction of TiO2/C and CeO2/C powders using intermittent microwave heating, followed by chemical reduction of platinum ions using mixed reducing agents of ethylene glycol and sodium borohydride. The crystal structure, surface morphology and chemical composition of prepared electrocatalysts were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The phase angle values of different Pt diffraction planes in Pt-TiO2/C and Pt-CeO2/C were shifted in the positive direction relative to those in Pt/C. Pt particles with diameter values of 3.06 and 2.78 nm were formed in Pt-TiO2/C and Pt-CeO2/C, respectively. The electrochemical performance of prepared electrocatalysts was examined using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Pt-CeO2/C showed an enhanced oxidation current density when compared to Pt/C. Long time oxidation test at Pt-TiO2/C and Pt-CeO2/C revealed their improved stability. Lower charge transfer resistance values were estimated at Pt-metal oxide/C electrocatalysts.

  8. The new methods of treatment for age-related macular degeneration using the ultra-short pulsed laser

    Iwamoto, Yumiko; Awazu, Kunio; Suzuki, Sachiko; Ohshima, Tetsuro; Sawa, Miki; Sakaguchi, Hirokazu; Tano, Yasuo; Ohji, Masahito


    The non-invasive methods of treatments have been studying for the improvement of quality of life (QOL) of patients undergoing treatment. A photodynamic therapy (PDT) is one of the non-invasive treatments. PDT is the methods of treatment using combination of a laser and a photosensitizer. PDT has few risks for patients. Furthermore, PDT enables function preservation of a disease part. PDT has been used for early cancer till now, but in late years it is applied for age-related macular degeneration (AMD). AMD is one of the causes of vision loss in older people. However, PDT for AMD does not produce the best improvement in visual acuity. The skin photosensivity by an absorption characteristic of a photosensitizer is avoided. We examined new PDT using combination of an ultra-short pulsed laser and indocyanine green (ICG).

  9. Arterial line for monitoring SpO2 in patients with ischemic peripheries.

    Umesh, Goneppanavar; Jasvinder, Kaur; Nanda, Shetty; Ranjan, Shetty


    Monitoring the oxygenation status of patients with poor peripheral perfusion or ischemic peripheries is challenging in view of unreliable or unrecordable pulse oximeter data. In this article we describe a very simple and innovative technique of using the arterial line for reliable recording of arterial oxygen saturation (SpO(2)) in such patients. We conclude that the arterial line can be used as an extension of the artery and SpO(2) may be reliably measured using the arterial line in such patients as long as the blood in the arterial tubing is pulsatile and a good contact is ensured between the arterial tubing and the sensor of the pulse oximeter.

  10. Energetics of nanocrystalline TiO2

    Ranade, M. R.; Navrotsky, A.; Zhang, H. Z.; Banfield, J. F.; Elder, S. H.; Zaban, A.; Borse, P. H.; Kulkarni, S. K.; Doran, G. S.; Whitfield, H. J.


    The energetics of the TiO2 polymorphs (rutile, anatase, and brookite) were studied by high temperature oxide melt drop solution calorimetry. Relative to bulk rutile, bulk brookite is 0.71 ± 0.38 kJ/mol (6) and bulk anatase is 2.61 ± 0.41 kJ/mol higher in enthalpy. The surface enthalpies of rutile, brookite, and anatase are 2.2 ± 0.2 J/m2, 1.0 ± 0.2 J/m2, and 0.4 ± 0.1 J/m2, respectively. The closely balanced energetics directly confirm the crossover in stability of nanophase polymorphs inferred by Zhang and Banfield (7). An amorphous sample with surface area of 34,600 m2/mol is 24.25 ± 0.88 kJ/mol higher in enthalpy than bulk rutile. PMID:11880610

  11. Research on CeO2 cap layer for YBCO-coated conductor

    Shi Dong-Qi; Ma Ping; Ko Rock-Kil; Kim Ho-Sup; Chung Jun-Ki; Song Kyu-Jeong; Park Chan


    Two groups of coated conductor samples with different thicknesses of CeO2 cap layers deposited by pulsed laser deposition (PLD) under the same conditions have been studied. Of them, one group is of CeO2 films, which are deposited on stainless steel (SS) tapes coated by IBAD-YSZ (IBAD-YSZ/SS), and the other group is of CeO2/YSZ/Y2O3 multilayers, which are deposited on NiW substrates by PLD for the fabrication of YBCO-coated conductor through the RABiTS approach. YBCO film is then deposited on the tops of both types of buffer layers by PLD. The effects of the thickness of the CeO2 film on the texture of the CeO2 film and the critical current density (Jc) of the YBCO film are analysed. For the case of CeO2 film on IBAD-YSZ/SS, there appears a self-epitaxy effect with increasing thickness of the CeO2 film. For CeO2/YSZ/Y2O3/NiW, in which the buffer layers are deposited by PLD, there occurs no self-epitaxy effect, and the optimal thickness of CeO2 is about 50nm. The surface morphologies of the two groups of samples are examined by SEM.

  12. Studies on Photocatalytic Hydrogen Production Relating to the Surface Functional Groups' Modulation of Polymer-modified Pt/ZnS-CdS/SiO2%高分子修饰Pt/ZnS-CdS/SiO2催化剂表面官能团调变与光催化制氢活性关系的研究

    周鹏; 赵成坚; 董文平; 吕功煊


    用丙烯酸酯和环氧树脂将亲水性的-OH和芳香性的苯环修饰到Pt/ZnS-CdS/SiO2催化剂表面,在不同气氛下进行热处理,得到了表面修饰并热处理后的Pt/ZnS-CdS/SiO2光催化剂,考察催化剂的可见光催化分解水产氢活性.结果表明修饰并热处理后催化剂活性不同程度的下降.XRD结果表明,修饰前后ZnS和CdS的特征衍射峰没有改变,但空气热处理致使催化剂晶型由立方晶型的CdS和六方晶型的ZnS向六方晶型的CdS和α-ZnS的转变,氢气气氛热处理致使催化剂的晶型向六方结构的固溶体Zn0.5Cd0.5S转变,未修饰的催化剂在空气和氢气中热处理后晶型发生了同样的转变.HRTEM结果表明表面修饰后催化剂平均粒径由18 nm减小为6 nm,仍以ZnS为外层,CdS为内层的核壳结构形态存在.紫外可见漫反射(UV-Vis DRS)结果表明,经修饰和热处理后的光催化剂在450~800 nm区间的光吸收增加,在空气中773 K煅烧后的催化剂的吸收限由480 nm红移至520 nm,而在氢气中于773 K煅烧后吸收限则由480 nm蓝移至420 nm.修饰后催化剂的羟基吸收强度增大,出现了苯环的特征吸收峰,这些官能团经热处理后发生了显著变化.红外光谱(IR)结果表明空气热处理导致部分含氧官能团发生了脱离,羟基吸收增强;氢气热处理导致C—O和C—O—C的吸收峰增强,同时催化剂表面发生碳化.热重差热分析(TG-DTA)与红外结果均证实了这种变化.产氢活性下降可能归结为表面羟基减少导致的在反应体系中的分散性和光生电荷的分离效率降低;催化剂表面的含氧官能团占据了催化活性位并且降低了颗粒在水溶液中的分散性.%The hydrophilic-OH group and aromatic benzene ring were modified to the surface of Pt/ZnS-CdS/SiO2 photocatalyst using acrylate and epoxy resin.Then the particles were calcined in the atmosphere and in the hydrogen at different temperatures

  13. High Frequency Anodising of Aluminium-TiO2 Surface Composites

    Gudla, Visweswara Chakravarthy; Bordo, Kirill; Jensen, Flemming


    High frequency anodising of Al–TiO2 surface composites using pulse reverse pulse technique was investigated with an aim to understand the effect of the anodising parameters on the optical appearance, microstructure, hardness and growth rate of the anodic layer. Friction stir processing was employed...... to prepare the Al–TiO2 surface composites, which were anodised in a 20 wt.% sulphuric acid bath at 10 °C as a function of pulse frequency, pulse duty cycle, and anodic cycle voltage amplitudes. The optical appearance of the films was characterized and quantified using an integrating sphere-spectrometer setup...... was also measured as a function of various anodising parameters. Anodic film growth, hardness, and total reflectance of the surface were found to be highly dependent on the anodising frequency and the anodic cycle potential. Longer exposure times to the anodising electrolyte at lower growth rates resulted...

  14. Non-UV germicidal activity of fresh TiO2 and Ag/TiO2

    LIU Lifen; John Barford; YEUNG King Lun


    Fresh TiO2 was found to possess a strong germicidal activity even without UV irradiation. Live Yeast (Saccharomyces cerevisiae) cells in contact with fresh TiO2 were found deformed and dead after 15 min contact. The cause of germicidal activity was discussed from the observed cell deformation, lysis and increased absorption at 1680 cm-1 in FT-IR spectra of the affected cells, which proved the oxidizing effect of fresh TiO2 to cells. The deformation caused by the stretching of cell wall and pressure built-up inside the cell, led to cell burst and release of intracellular materials. The degree of cell deformation was found positively related with the wetting property of TiO2. Cells are negatively charged, for Gram-negative cell (thinner cell wall), a higher germicidal effect was observed than Gram-positive cells. The germicidal effect of TiO2 gradually decreases after exposure to air at room temperature, as the wetting property decreases. This kind of germicidal activity was more effective compared to other germicidal process such as UVA/TiO2 or Ag+. This shed light on designing new germicidal material either maintained by visible light irradiation, or by oxidation effect generated by reactive oxygen species.

  15. Effects of CeO2 Support Facets on VOx/CeO2 Catalysts in Oxidative Dehydrogenation of Methanol

    Li, Yan; Wei, Zhehao; Gao, Feng; Kovarik, Libor; Peden, Charles HF; Wang, Yong


    CeO2 supports with dominating facets, i.e., low index (100), (110) and (111) facets, are prepared. The facet effects on the structure and catalytic performance of supported vanadium oxide catalysts are investigated using oxidative dehydrogenation of methanol as a model reaction. In the presence of mixed facets, Infrared and Raman characterizations demonstrate that surface vanadia species preferentially deposit on CeO2 (100) facets, presumably because of its higher surface energy. At the same surface vanadium densities, VOx species on (100) facets show better dispersion, followed by (110) and (111) facets. The VOx species on CeO2 nanorods with (110) and (100) facets display higher activity and lower apparent activation energies compared to that on CeO2 nanopolyhedras with dominating (111) facets and CeO2 nanocubes with dominating (100) facets. The higher activity for VOx/CeO2(110) might be related to the more abundant oxygen vacancies present on the (110) facets, evidenced from Raman spectroscopic measurements.

  16. Preparation and characterization of SO42-/TiO2 and S2O82-/TiO2 catalysts

    MA Xuedan; GUO Daishi; JIANG Qizhong; MA Zifeng; MA Zhengfei; YE Weidong; LI Chunbo


    Nanosizedsolid superacidsSO42-/TiO2and S2O82-/TiO2,as well as MCM-41-supported SO42-/ZrO2,were prepared.Their structures,acidities,and catalytic activities were investigated and compared using XRD,N2 adsorptiondesorption,and in situ FTIR-pyridine adsorption,as well as an evaluation reaction with pseudoionone cyclization.The results showed that SO42-/TIO2 and S2Os2-/TiO2 possess not only nanosized particles with diameters < 7.0 nm,a BET surface greater than 140 cm2/g and relatively regular mesostructures with pores around 4.0 nm,but also a pure anatase phase and strong acidity.Different from the Lewis acid nature of SO42-/ZrO2/MCM-41,SO42-/TIO2 and S2O8Z-/TiO2 exhibit mainly Bronsted acidities.The strongest Bronsted acid sites were produced on SO42-/TIO2 promoted with H2804,while Lewis acid sites on S2082-/TIO2 even stronger than those on SO42-/ZrO2/MCM-41 were generated when persulfate solution was used as sulfating agent.Because of their distinct acid natures,SO42-/TIO2 and $2082-/TIO2 exhibited catalytic activities for the cyclization ofpseudoionone that were much higher than that of SO42-/ZrO2/MCM-41.It can be concluded that the existence of more Bronsted acid sites was favorable for proton participation in the cyclization reaction.

  17. Catalytic combustion of toluene on Pd/CeO2-TiO2 catalysts.

    Chen, Yu-Wen; Lee, Der-Shing


    Pd/TiO2 and Pd/CeO2 were reported to be very active to destruct toluene. Combination of TiO2 and CeO2 is an interesting candidate to achieve a catalyst with higher activity. In this study, a series of Pd/CeO2-TiO2 catalysts with various Pd loadings were prepared. CeO2-TiO2 was prepared by impregnation of aqueous solution of cerium nitrate into TiO2 support. It was then calcined at 400 degrees C. Pd was loaded by incipient-wetness impregnation method. The Pd loadings in all samples were fixed at 0.5 wt.%. The catalysts were characterized by powder X-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy, temperature-programmed reduction of hydrogen, and X-ray photoelectron spectroscopy. The catalysts were tested for total oxidation of toluene. The feed concentration of toluene was 8.564 g/m3 (2085 ppm), with GHSV = 10,000 h(-1). Pd particle sizes were 3-5 nm and well-dispersed on the support. CeO2 on TiO2 was easier to reduce than the bulk CeO2, therefore it could enhance the activity of VOC destruction. Pd/CeO2-TiO2 was more active than Pd/CeO2 and Pd/TiO2. Pd/CeO2-TiO2 with Ce/Ti ratio of 2/8 was very active for toluene destruction, due to its lower oxygen reduction temperature of ceria and higher concentration of Pd(0).

  18. Water pulse migration through semi-infinite vertical unsaturated porous column with special relative-permeability functions: Exact solutions

    Hayek, Mohamed


    The paper presents certain exact solutions describing the vertical movement of a water pulse through a semi-infinite unsaturated porous column. The saturation-based form of the Richards' equation is used with special power law relative-permeability functions. Both capillary and gravity effects are taken into account. Three exact solutions are derived corresponding to three relative-permeability functions, linear, quadratic and cubic. The Richards' equation is nonlinear for the three cases. The solutions are obtained by applying a general similarity transformation. They are explicit in space and time variables and do not contain any approximation. They describe the evolution of the water saturation in the vertical column and they can be used to predict the post-infiltration movement of a finite quantity of water. Exact expressions of the masses of water leaving a given depth are also derived for the three cases. We analyze the effect of relative-permeability and capillary pressure. The proposed solutions are also useful for checking numerical schemes. One of the exact solutions is used to validate numerical solution obtained from an arbitrary initial condition. Results show that the numerical solution converges to the exact solution for large times.

  19. Effects of rare earth 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 common carbon steel surface by pulse electrodeposition of nickel, tungsten, phosphorus, rare earth (nano-CeO2) and silicon carbide (nano-SiO2) particles. The effects of nano-CeO2 concentrations in electrolyte on microstructures and properties of nano-composite coatings were studied. The samples were characterized with chemical compositions, elements distributions, microhardness and microstructures. The results indicated that when nano-CeO2 concentration was controlled at 10 g/L, the nano-composite coatings possessed higher microhardness and compact microstructures with clear outline of spherical matrix metal crystallites, fine crystallite sizes and uniform distribution of elements W, P, Ce and Si within the Ni-W-P matrix metal. Increasing the nano-CeO2 particles concentrations from 4 to 10 g/L led to refinement in grain structure and improvement of microstructures, while when increased to 14 g/L, the crystallite sizes began to increase again and there were a lot of small boss with nodulation shape appearing on the nano-composite coatings surface.

  20. Analytical model of Europa's O2 exosphere

    Milillo, Anna; Plainaki, Christina; De Angelis, Elisabetta; Mangano, Valeria; Massetti, Stefano; Mura, Alessandro; Orsini, Stefano; Rispoli, Rosanna


    The origin of the exosphere of Europa is its water ice surface. The existing exosphere models, assuming either a collisionless environment (simple Monte Carlo techniques) or a kinetic approach (Direct Monte Carlo Method) both predict that the major constituent of the exosphere is molecular oxygen. Specifically, O2 is generated at the surface through radiolysis and chemical interactions of the water dissociation products. The non-escaping O2 molecules circulate around the moon impacting the surface several times, due to their long lifetime and due to their non- sticking, suffering thermalization to the surface temperature after each impact. In fact, the HST observations of the O emission lines proved the presence of an asymmetric atomic Oxygen distribution, related to a thin asymmetric molecular Oxygen atmosphere. The existing Monte Carlo models are not easily applicable as input of simulations devoted to the study of the plasma interactions with the moon. On the other hand, the simple exponential density profiles cannot well depict the higher temperature/higher altitudes component originating by radiolysis. It would thus be important to have a suitable and user-friendly model able to describe the major exospheric characteristics to use as a tool. This study presents an analytical 3D model that is able to describe the molecular Oxygen exosphere by reproducing the two-component profiles and the asymmetries due to diverse configurations among Europa, Jupiter and the Sun. This model is obtained by a non-linear fit procedure of the EGEON Monte Carlo model (Plainaki et al. 2013) to a Chamberlain density profile. Different parameters of the model are able to describe various exosphere properties thus allowing a detailed investigation of the exospheric characteristics. As an example a discussion on the exospheric temperatures in different configurations and space regions is given.

  1. 大规模生产TiO2薄膜的方法%Approach for Producing TiO2 Thin Films in Large Scale

    汪洋; 彭晓光; 陈樱


    @@ Introduction Metal oxides are in use as catalysts in industrial processes. The surfaces of titanium dioxide (TiO2)has been of great interest because of its capability of heterogeneous catalysis and photocatalysis, and the adsorption of small molecules on TiO2 has received considerable attention in relation to the elimination of atmospheric pollutants. So that It is important to produce TiO2 thin films in large scale.

  2. On the orthorhombic phase in ZrO2-based alloys

    Heuer, A. H.; Lanteri, V.; Chaim, R.; Lee, R.-R.; Farmer, S. C.


    During TEM observation, a tetragonal (t) to orthorhombic (o) phase transformation often occurs in thin portions of ZrO2-containing foils. This transformation is stress-induced and in some senses artifactual, in that the reaction product is actually a high-pressure phase, relative to monoclinic (m) ZrO2, that can form from metastable t-ZrO2 in the TEM because its density is intermediate between t- and m-ZrO2. Examples of the formation of o-ZrO2 in a number of different systems are given.

  3. Relative reactivity of dihydropyridine derivatives to electrogenerated superoxide ion in DMSO solutions: a voltammetric approach.

    Oriz, María Eugenia; Núñez-Vergara, Luis Joaquin; Squella, Juan Arturo


    To evaluate the reaction of a large series of pharmacologically significant 1,4-dihydropyridine (1,4-DHP) compounds with superoxide (O2.-) in dimethylsulfoxide using differential pulse voltammetry and controlled potential electrolysis. Differential pulse voltammetry was used to track the consumption of O2.-, and controlled potential electrolysis was used to electrogenerate O2.-. With the addition of 1,4-DHP, the oxidation peak current of O2.- decreased concentration dependently, suggesting that 1,4-DHP reacts with O2.-, that is, 1,4-DHP scavenges O2.- in dimethylsulfoxide. very easy and direct voltammetric procedure to study the relative reactivity of different 1,4-DHP with O2.- is proposed. Using the proposed method we have found that all commercial 1,4-DHP reacts with O2.-. The following order of rates was obtained: felodipine > or = vitamin E > isradipine > nimodipine > furnidipine > nitrendipine > nisoldipine > nifedipine. Furthermore, it was demonstrated that the hydrogen at the N-position of 1,4-DHP compounds could be released as a proton in the presence of O2.-, thus the electrogenerated O2.- worked as a proton acceptor to 1,4-DHP.

  4. Herschel Search for O2 Toward the Orion Bar

    Melnick, Gary J; Goldsmith, Paul F; Kaufman, Michael J; Hollenbach, David J; Black, John H; Encrenaz, Pierre; Falgarone, Edith; Gerin, Maryvonne; Hjalmarson, Åke; Li, Di; Lis, Dariusz C; Liseau, René; Neufeld, David A; Pagani, Laurent; Snell, Ronald L; van der Tak, Floris; van Dishoeck, Ewine F


    We report the results of a search for molecular oxygen (O2) toward the Orion Bar, a prominent photodissociation region at the southern edge of the HII region created by the luminous Trapezium stars. We observed the spectral region around the frequency of the O2 N_J = 3_3 - 1_2 transition at 487 GHz and the 5_4 - 3_4 transition at 774 GHz using the Heterodyne Instrument for the Far Infrared on the Herschel Space Observatory. Neither line was detected, but the 3sigma upper limits established here translate to a total line-of-sight O2 column density < 1.5 10^16 cm^-2 for an emitting region whose temperature is between 30K and 250 K, or < 1 10^16 cm^-2 if the O2 emitting region is primarily at a temperature of ~< 100 K. Because the Orion Bar is oriented nearly edge-on relative to our line of sight, the observed column density is enhanced by a factor estimated to be between 4 and 20 relative to the face-on value. Our upper limits imply that the face-on O2 column density is less than 4 10^15 cm^-2, a value...

  5. 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.

  6. Preparation and photocatalytic activity of Cu2+-doped TiO2/SiO2

    Ru-fen Chen; Cui-xuan Zhang; Juan Deng; Guo-qiang Song


    Cu2+-doped nanostructured TiO2-coated SiO2. (TiO2./SiO2) particles were prepared by the layer-by-layer assembly technique and their photocatalytic property was studied. TiO2 colloids were synthesized by the sol-gel method using TiOSO4 as a precursor. The experimental results showed that TiO2 nanopowders on the surface of SiO2 particles were well distributed and compact. The amount of TiO2 increased with the increase in coating layers. The shell structure appeared to be composed of anatase titania nanocrystals at 550℃. The 2-layer coated TiO2 particles on the surface showed a higher degradation rate compared with all the dif-ferent-layer samples. The photocatalytic activity of Cu2+-doped TiO2/SiO2 was higher than that of undoped TiO2/SiO2. The optimum dopant content was about 0.10wt%.

  7. Photoelectrochemical Properties of CuS-GeO2-TiO2 Composite Coating Electrode

    Wen, Xinyu; Zhang, Huawei


    The ITO (indium tin oxide) conductive glass-matrix CuS-GeO2-TiO2 composite coating was generated via EPD (electrophoretic deposition) and followed by a sintering treatment at 450°C for 40 minutes. Characterizations of the CuS-GeO2-TiO2 composite coating were taken by SEM (scanning electron microscope), XRD (X-ray diffraction), EDX (energy dispersive X-ray), UV-Vis DRS (ultraviolet-visible diffuse reflection spectrum), and FT-IR (Fourier transform infrared spectroscopy). Results showed that CuS and GeO2 had dispersed in this CuS-GeO2-TiO2 composite coating (mass percentages for CuS and GeO2 were 1.23% and 2.79%, respectively). The electrochemical studies (cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel polarization) of this CuS-GeO2-TiO2 composite coating electrode were performed in pH = 9.51 Na2CO3-NaHCO3 buffer solution containing 0.50 mol/L CH3OH under the conditions of visible light, ultraviolet light (λ = 365 nm), and dark (without light irradiation as control), respectively. Electrochemical studies indicated that this CuS-GeO2-TiO2 composite coating electrode had better photoelectrocatalytic activity than the pure TiO2 electrode in the electrocatalysis of methanol under visible light. PMID:27055277

  8. Comparison of SpO2 values from different fingers of the hands.

    Basaranoglu, Gokcen; Bakan, Mefkur; Umutoglu, Tarik; Zengin, Seniyye Ulgen; Idin, Kadir; Salihoglu, Ziya


    Pulse oximetry is a frequently used tool in anesthesia practice. Gives valuable information about arterial oxygen content, tissue perfusion and heart beat rate. In this study we aimed to provide the comparison of peripheral capillary hemoglobin oxygen saturation (SpO2) values among every finger of the two hands. Thirty-seven healthy volunteers from operative room stuffs between the ages of 18-30 years were enrolled in the study. They were monitored after 5 min of rest. After their non invasive blood pressure, heart rate, fasting time and body temperature were measured, SpO2 values were obtained from every finger and each of two hands fingers with the same pulse oximetry. All the SpO2 values were obtained after at least 1 min of measurement period. A total of 370 SpO2 measurements from 37 volunteers were obtained. The highest average SpO2 value was measured from right middle finger (98.2 % ± 1.2) and it was statistically significant when compared with right little finger and left middle finger. The second highest average SpO2 value was measured from right thumb and it was statistically significant only when compared with left middle finger (the finger with the lowest average SpO2 value) (p < 0.05). SpO2 measurement from the fingers of the both hands with the pulse oximetry, the right middle finger and right thumb have statistically significant higher value when compared with left middle finger in right-hand dominant volunteers. We assume that right middle finger and right thumb have the most accurate value that reflects the arterial oxygen saturation.

  9. Photoactivity and hydrophilic property of SiO2 and SnO2 co-doped TiO2 nano-composite thin films

    Lek Sikong


    Full Text Available SiO2 and SnO2 co-doped TiO2 nano-composite thin films were prepared by sol-gel method. The effects of film thicknessand amount of SiO2 and SnO2 co-doping into TiO2 nano-composite films on phase presence, crystallite size, photocatalyticreaction and hydrophilicity were investigated. Thickness of 3-coating layers (238 nm seems to provide the highest photocatalyticactivity. The crystallinity of anatase phases, crystallite sizes and photocatalytic reactions of SiO2 and SnO2 co-dopedTiO2 films decrease with an increase in SiO2 content. It was found that more amount of SiO2 addition seems to inhibit graingrowth and the formation of anatase phase; especially when it was synthesized at temperature less than 600°C. The photocatalyticreaction seems to decrease with an increase in SiO2 doping when the concentrations of SnO2 in the composite films are fixed. It was apparent that 1SiO2/1SnO2/TiO2 composite film exhibits the highest photoactivity. Suitable amounts of SiO2and SnO2 doping into the TiO2 composite films tend to enhance the hydrophilic property of the films. It was also apparentthat the 3SiO2/3SnO2/TiO2, 5SiO2/5SnO2/TiO2 and 10SiO2/3SnO2/TiO2 composite films exhibit super hydrophilic characteristicsunder UV irradiation for 30 min.

  10. Pulsed electromagnetic field therapy for management of osteoarthritis-related pain, stiffness and physical function: clinical experience in the elderly

    Iannitti T


    Full Text Available Tommaso Iannitti,1,2 Gregorio Fistetto,2 Anna Esposito,2 Valentina Rottigni,2,3 Beniamino Palmieri2,3 1Department of Physiology, University of Kentucky Medical Center, Lexington, KY, USA; 2Poliambulatorio del Secondo Parere, Modena, Italy; 3Department of General Surgery and Surgical Specialties, University of Modena and Reggio Emilia Medical School, Surgical Clinic, Modena, Italy Background: Pulsed electromagnetic field (PEMF therapy has shown promising therapeutic effectiveness on bone- and cartilage-related pathologies, being also safe for management of knee osteoarthritis. Aim: The aim of this study was to investigate the clinical efficacy of a PEMF device for management of knee osteoarthritis in elderly patients. Materials and methods: A total of 33 patients were screened, and 28 patients, aged between 60 and 83 and affected by bilateral knee osteoarthritis, were enrolled in this study. They received PEMF therapy on the right leg for a total of three 30-minute sessions per week for a period of 6 weeks, while the left leg did not receive any treatment and served as control. An intravenous drip containing ketoprofen, sodium clodronate, glucosamine sulfate, calcitonin, and ascorbic acid, for a total volume of 500 mL, was administered during PEMF therapy. At baseline and 3 months post-PEMF therapy, Visual Analog Scale (VAS was used to assess knee pain and Western Ontario McMaster Universities Osteoarthritis Index (WOMAC was used to measure knee pain, stiffness and physical function. Results: Changes in VAS and WOMAC scores were calculated for both knees as baseline minus post-treatment. A two sample Student’s t-test, comparing change in knee-related VAS pain for PEMF-treated leg (49.8 ± 2.03 vs control leg (11 ± 1.1, showed a significant difference in favor of PEMF therapy (P < 0.001. A two sample Student’s t-test comparing change in knee-related WOMAC pain, stiffness, and physical function for PEMF-treated leg (8.5 ± 0.4, 3.5 ± 0.2, 38

  11. Electrocatalysis of Oxygen Evolution Reaction on Ti/SnO2+ RuO2+ MnO2/MnO2 Electrode in Sulfuric Acid Solution


    The Ti-Supported MnO2 electrode was modified by introducing SnO2 +RuO2 +MnO2 as an intermediate layer into the Ti/MnO2 interface. The anodic polarization curves were measured at various temperatures ranging from 30 to 80 ℃ and the activation energy for the oxygen evolution reaction was evaluated. The experimental activation energy increased linearly with increasing the overpotential. The activation energy at the equilibrium potential was linearly correlated with the difference between the crystal field stabilization energies of Mn4+ at initial state and Mn4+ at transition state. The electrocatalysis characteristics of the anode were discussed by means of themechanism of the substitution reaction of the ligand(SN 1 and SN2) and molecular orbital theory.The results show that the anode has better electrocatalystic characteristics.

  12. Relationships among growth mechanism, structure and morphology of PEALD TiO2 films: the influence of O2 plasma power, precursor chemistry and plasma exposure mode

    Chiappim, W.; Testoni, G. E.; Doria, A. C. O. C.; Pessoa, R. S.; Fraga, M. A.; Galvão, N. K. A. M.; Grigorov, K. G.; Vieira, L.; Maciel, H. S.


    Titanium dioxide (TiO2) thin films have generated considerable interest over recent years, because they are functional materials suitable for a wide range of applications. The efficient use of the outstanding functional properties of these films relies strongly on their basic characteristics, such as structure and morphology, which are affected by deposition parameters. Here, we report on the influence of plasma power and precursor chemistry on the growth kinetics, structure and morphology of TiO2 thin films grown on Si(100) by plasma-enhanced atomic layer deposition (PEALD). For this, remote capacitively coupled 13.56 MHz oxygen plasma was used to act as a co-reactant during the ALD process using two different metal precursors: titanium tetrachloride (TiCl4) and titanium tetraisopropoxide (TTIP). Furthermore, we investigate the effect of direct plasma exposure during the co-reactant pulse on the aforementioned material properties. The extensive characterization of TiO2 films using Rutherford backscattering spectroscopy, ellipsometry, x-ray diffraction (XRD), field-emission scanning electron microscopy, and atomic force microscopy (AFM) have revealed how the investigated process parameters affect their growth per cycle (GPC), crystallization and morphology. The GPC tends to increase with plasma power for both precursors, however, for the TTIP precursor, it starts decreasing when the plasma power is greater than 100 W. From XRD analysis, we found a good correlation between film crystallinity and GPC behavior, mainly for the TTIP process. The AFM images indicated the formation of films with grain size higher than film thickness (grain size/film thickness ratio ≈20) for both precursors, and plasma power analysis allows us to infer that this phenomenon can be directly related to the increase of the flux of energetic oxygen species on the substrate/growing film surface. Finally, the effect of direct plasma exposure on film structure and morphology was evidenced

  13. Analysis of color-center-related contribution to Bragg grating formation in Ge:SiO 2 fiber based on a local Kramers -Kronig transformation of excess loss spectra.

    Leconte, B; Xie, W X; Douay, M; Bernage, P; Niay, P; Bayon, J F; Delevaque, E; Poignant, H


    UV-induced excess losses have been measured at various pulse energy densities and exposure times in germanosilicate optical fiber preform cores. The corresponding refractive-index changes have been determined through a Kramers -Kronig analysis. Because of the nonlinear behavior of the excess losses as a function of both exposure time and fluence per pulse, one should be careful when comparing the refractive-index modulation deduced from such measurements with that obtained from Bragg grating reflectivity. Indeed nonlinear effects such as saturation imply that it is necessary to take into account the local character of the change in absorption to calculate the evolution of the refractive-index modulation accurately as a function of the exposure time. Implications of these results are discussed.

  14. Sandwich structure of Pd doped nanostructure TiO2 film as O2 sensor.

    Wang, Hairong; Sun, Quantao; Chen, Lei; Zhao, Yulong


    In this paper, we investigated the sensing properties of sandwich structure of TiO2/Pd/TiO2 thin films at various operating temperatures and oxygen partial pressures. The nanostructure TiO2 thin films were prepared by the sol-gel method. Various thickness of Pd buried layer was deposited by magnetron sputtering of a pure Pd target. The films were characterized using X-ray diffraction analysis and SEM. It was found that TiO2/Pd/TiO2 thin films have the p-type behavior while the pure TiO2 thin film is n-type semiconductor materials. We found that the structure of TiO2/Pd/TiO2 thin films with 10 s sputtering Pd layer has a better stability at 240 °C.

  15. Synthesis and characterization of TiO2 and Ag/TiO2 nanostructure

    Gahlot, Swati; Thakur, Amit Kumar; Kulshrestha, Vaibhav; Shahi, V. K.


    Single phase anatase TiO2 nanoparticles were prepared using Titanium tertachloride (TiCl4) as precursor through an inexpensive method. Well dispersed nanocomposites of silver at TiO2 were synthesized successfully by photochemical route. Both TiO2 and Ag/TiO2 were characterized using X-Ray Diffraction (XRD) and transmission electron microscopy (TEM). The particle size of TiO2 is found to be ˜ 11 nm and ˜ 22 nm for Ag/TiO2, by XRD and confirmed by TEM. TEM micrographs also show the single phase crystal of TiO2 and confirm the deposition of silver among TiO2.

  16. SnO2/TiO2 bilayer thin films exhibiting superhydrophilic properties

    Talinungsang, Nibedita Paul; Purkayastha, Debarun Dhar


    Nanostructured thin films of TiO2, SnO2, and SnO2/TiO2 have been deposited by sol-gel method. The films are characterized by X-ray diffraction, wettability and optical properties. In the present work, we have achieved a way of converting hydrophilic to super-hydrophilic state by incorporating TiO2 buffer layer in between substrate and SnO2 film, which has its utility in anti-fogging surfaces. The decrease in contact angle of water over SnO2/TiO2 bilayer is attributed to the increase in roughness of the film as well as surface energy of the substrate.

  17. Experimental study of gradual/abrupt dynamics of HfO2-based memristive devices

    Brivio, S.; Covi, E.; Serb, A.; Prodromakis, T.; Fanciulli, M.; Spiga, S.


    The resistance switching dynamics of TiN/HfO2/Pt devices is analyzed in this paper. When biased with a voltage ramp of appropriate polarity, the devices experience SET transitions from high to low resistance states in an abrupt manner, which allows identifying a threshold voltage. However, we find that the stimulation with trains of identical pulses at voltages near the threshold results in a gradual SET transition, whereby the resistive state visits a continuum of intermediate levels as it approaches some low resistance state limit. On the contrary, RESET transitions from low to high resistance states proceed in a gradual way under voltage ramp stimulation, while gradual resistance changes driven by trains of identical spikes cover only a limited resistance window. The results are discussed in terms of the relations among the thermo-electrochemical effects of Joule heating, ion mobility, and resistance change, which provide positive and negative closed loop processes in SET and RESET, respectively. Furthermore, the effect of the competition between opposite tendencies of filament dissolution and formation at opposite metal/HfO2 interfaces is discussed as an additional ingredient affecting the switching dynamics.

  18. High-reflectivity HfO2/SiO2 ultraviolet mirrors.

    Torchio, Philippe; Gatto, Alexandre; Alvisi, Marco; Albrand, Gérard; Kaiser, Norbert; Amra, Claude


    High-reflectivity dense multilayer coatings were produced for the ultraviolet spectral region. Thin-film single layers and UV mirrors were deposited by ion plating and plasma ion-assisted deposition high-energetic technologies. Optical characterizations of HfO2 and SiO2 single layers are made. The optical constants obtained for these two materials are presented. HfO2 and SiO2 mirrors with a reflectance of approximately 99% near 250 nm are reported.

  19. Antibacterial properties of nanostructured Cu-TiO2 surfaces for dental implants.

    Rosenbaum, Jonathan; Versace, Davy Louis; Abbad-Andallousi, Samir; Pires, Remi; Azevedo, Christophe; Cénédese, Pierre; Dubot, Pierre


    The influence of copper derived TiO2 surfaces (nCu-nT-TiO2) on the death of nosocomial Staphylococcus aureus (Sa) and Escherichia coli (Ec), was investigated. TiO2 nanotube (nT-TiO2) arrays were fabricated by anodic oxidation of pure titanium sheets in fluorhydric solutions, leading to surface nanostructuration and creation of specific reactive sites. Copper nanocubes with a mean size of 20 nm have been synthesized and deposited on the nT-TiO2 surface by pulsed electrodeposition from a copper sulphate solution. Scanning Electron Microscopy (SEM) reveals that Cu nanocubes are both inserted into the TiO2 nanotubes and on the nanotube edges. X-ray Photoemission Spectroscopy (XPS) and SEM-EDX confirm the metallic nature of copper nanoparticles, covered with a thin mixed CuO-Cu2O thin layer. As the adsorption of proteins is one of the early stages of biomaterial surface interactions with body fluids before bacterial colonization, Infrared Spectroscopy (IR) in reflection-absorption mode, SEM and XPS have been used to follow the evolution of nCu-nT-TiO2 surfaces when exposed to a simulated plasma solution containing Bovine Serum Albumin (BSA). Finally bacterial tests have revealed a high biocide potential of the nCu-nT-TiO2 surface, which leads to the entire death of SA and EC.

  20. Doped-TiO2 Photocatalysts and Synthesis Methods to Prepare TiO2 Films

    Ying CUI; Hao DU; Lishi WEN


    TiO2 is a promising photocatalyst. However, the low photocatalytic efficiency calls for the modification of TiO2. Metal- and nonmetal-doping of TiO2 have been proved to be effective ways to enhance photocatalytic properties. This review provides a deep insight into the understanding of the metal- and nonmetal-doped TiO2 photocatalysts. This article begins with the introduction of the crystal structures of TiO2 and applications of TiO2 materials. We then reviewed the doped-TiO2 system in two categories: (1) metal-doped TiO2photocatalysts system, and (2) nonmetal-doped TiO2 photocatalysts system. Both experimental results and theoretical analyses are elaborated in this section. In the following part, for the advantages of TiO2 thin films over particles, various preparation methods to obtain TiO2 thin films are briefly discussed. Finally, this review ends with a concise conclusion and outlook of new trends in the development of TiO2-based photocatalysts.

  1. Hazards of TiO2 and amorphous SiO2 nanoparticles

    Reijnders, L.; Kahn, H.A.; Arif, I.A.


    TiO2 and amorphous SiO2 nanoparticles have been described as ‘safe’, ‘non-toxic’ and ‘environment friendly’ in scientific literature. However, though toxicity data are far from complete, there is evidence that these nanoparticles are hazardous. TiO2 nanoparticles have been found hazardous to humans

  2. Enhanced photocatalytic performances of CeO2/TiO2 nanobelt heterostructures.

    Tian, Jian; Sang, Yuanhua; Zhao, Zhenhuan; Zhou, Weijia; Wang, Dongzhou; Kang, Xueliang; Liu, Hong; Wang, Jiyang; Chen, Shaowei; Cai, Huaqiang; Huang, Hui


    CeO2 /TiO2 nanobelt heterostructures are synthesized via a cost-effective hydrothermal method. The as-prepared nanocomposites consist of CeO2 nanoparticles assembled on the rough surface of TiO2 nanobelts. In comparison with P25 TiO2 colloids, surface-coarsened TiO2 nanobelts, and CeO2 nanoparticles, the CeO2 /TiO2 nanobelt heterostructures exhibit a markedly enhanced photocatalytic activity in the degradation of organic pollutants such as methyl orange (MO) under either UV or visible light irradiation. The enhanced photocatalytic performance is attributed to a novel capture-photodegradation-release mechanism. During the photocatalytic process, MO molecules are captured by CeO2 nanoparticles, degraded by photogenerated free radicals, and then released to the solution. With its high degradation efficiency, broad active light wavelength, and good stability, the CeO2 /TiO2 nanobelt heterostructures represent a new effective photocatalyst that is low-cost, recyclable, and will have wide application in photodegradation of various organic pollutants. The new capture-photodegradation-release mechanism for improved photocatalysis properties is of importance in the rational design and synthesis of new photocatalysts.

  3. Hazards of TiO2 and amorphous SiO2 nanoparticles

    Reijnders, L.; Kahn, H.A.; Arif, I.A.


    TiO2 and amorphous SiO2 nanoparticles have been described as ‘safe’, ‘non-toxic’ and ‘environment friendly’ in scientific literature. However, though toxicity data are far from complete, there is evidence that these nanoparticles are hazardous. TiO2 nanoparticles have been found hazardous to humans

  4. Lithium insertion in nanostructured TiO(2)(B) architectures.

    Dylla, Anthony G; Henkelman, Graeme; Stevenson, Keith J


    Electric vehicles and grid storage devices have potentialto become feasible alternatives to current technology, but only if scientists can develop energy storage materials that offer high capacity and high rate capabilities. Chemists have studied anatase, rutile, brookite and TiO2(B) (bronze) in both bulk and nanostructured forms as potential Li-ion battery anodes. In most cases, the specific capacity and rate of lithiation and delithiation increases as the materials are nanostructured. Scientists have explained these enhancements in terms of higher surface areas, shorter Li(+) diffusion paths and different surface energies for nanostructured materials allowing for more facile lithiation and delithiation. Of the most studied polymorphs, nanostructured TiO2(B) has the highest capacity with promising high rate capabilities. TiO2(B) is able to accommodate 1 Li(+) per Ti, giving a capacity of 335 mAh/g for nanotubular and nanoparticulate TiO2(B). The TiO2(B) polymorph, discovered in 1980 by Marchand and co-workers, has been the focus of many recent studies regarding high power and high capacity anode materials with potential applications for electric vehicles and grid storage. This is due to the material's stability over multiple cycles, safer lithiation potential relative to graphite, reasonable capacity, high rate capability, nontoxicity, and low cost (Bruce, P. G.; Scrosati, B.; Tarascon, J.-M. Nanomaterials for Rechargeable Lithium Batteries. Angew. Chem., Int. Ed.2008, 47, 2930-2946). One of the most interesting properties of TiO2(B) is that both bulk and nanostructured forms lithiate and delithiate through a surface redox or pseudocapacitive charging mechanism, giving rise to stable high rate charge/discharge capabilities in the case of nanostructured TiO2(B). When other polymorphs of TiO2 are nanostructured, they still mainly intercalate lithium through a bulk diffusion-controlled mechanism. TiO2(B) has a unique open crystal structure and low energy Li

  5. Interface engineered HfO2-based 3D vertical ReRAM

    Hudec, Boris; Wang, I.-Ting; Lai, Wei-Li; Chang, Che-Chia; Jančovič, Peter; Fröhlich, Karol; Mičušík, Matej; Omastová, Mária; Hou, Tuo-Hung


    We demonstrate a double-layer 3D vertical resistive random access memory (ReRAM) stack implementing a Pt/HfO2/TiN memory cell. The HfO2 switching layer is grown by atomic layer deposition on the sidewall of a SiO2/TiN/SiO2/TiN/SiO2 multilayer pillar. A steep vertical profile was achieved using CMOS-compatible TiN dry etching. We employ in situ TiN bottom interface engineering by ozone, which results in (a) significant forming voltage reduction which allows for forming-free operation in AC pulsed mode, and (b) non-linearity tuning of low resistance state by current compliance during Set operation. The vertical ReRAM shows excellent read and write disturb immunity between vertically stacked cells, retention over 104 s and excellent switching stability at 400 K. Endurance of 107 write cycles was achieved using 100 ns wide AC pulses while fast switching speed using pulses of only 10 ns width is also demonstrated. The active switching region was evaluated to be located closer to the bottom interface which allows for the observed high endurance.

  6. TiO2 ve ZrO2/TiO2 Kompozit Mikrokürecik Sentezi ve Metilen Mavisinin Degradasyonunda Fotokatalitik Aktiviteleri

    Vaizoğulları, Ali İmran; Balcı, Ahmet; Uğurlu, Mehmet; KARAOĞLU, Muhammet Hamdi


    TiO2 and ZrO2/TiO2 composite microsphere particles were synthesized using the sol‐gel method. Photoactivity of TiO2 and ZrO2/TiO2 were compared.  Particles were characterized using X‐ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM) of X‐ray (EDAX), and transmission electron microscopy (TEM). The study revealed that TiO2 particles were microspheres.    The decorating of ZrO2 particles on TiO2 surface was successfully carried out that was pr...

  7. Synthesis of TiO2 and ZrO2/TiO2 Composite Microspheres and Their Photo‐Catalytic Degradation of Methylene Blue

    Vaizoğulları, Ali İmran; Balcı, Ahmet; UĞURLU, Mehmet; Karaoğlu, Muhammet Hamdi


    TiO2 and ZrO2/TiO2 composite microsphere particles were synthesized using the sol‐gel method. Photoactivity of TiO2 and ZrO2/TiO2 were compared.  Particles were characterized using X‐ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM) of X‐ray (EDAX), and transmission electron microscopy (TEM). The study revealed that TiO2 particles were microspheres.    The decorating of ZrO2 particles on TiO2 surface was successfully carried out that was pr...

  8. Photodecomposition of methylene blue by amorphous TiO2, CdS and TiO2-CdS films

    F.G. Nieto-Caballero; E. Sánchez-Mora; J. M. Gracia-Jiménez; N.R. Silva-González; A.G. Rodríguez


    TiO2is one of the most widely studied oxide materials for applications related to photocatalytic processes. It has been reported that TiO2combined with CdS produces an improvement in the photocatalytic efficiency. This work focuses on the obtainment of TiO2, CdS and TiO2-CdSin situthin films by the sol-gel/dip coating method. After deposition on glass, each film was calcined at 300oC in an argon atmospherefor 30 min. The films were characterized by SEM, UV-Vis, XRD and micro-Raman. The TiO...

  9. High Photocatalytic Activity of Fe3O4-SiO2-TiO2 Functional Particles with Core-Shell Structure

    Chenyang Xue


    Full Text Available This paper describes a novel method of synthesizing Fe3O4-SiO2-TiO2 functional nanoparticles with the core-shell structure. The Fe3O4 cores which were mainly superparamagnetic were synthesized through a novel carbon reduction method. The Fe3O4 cores were then modified with SiO2 and finally encapsulated with TiO2 by the sol-gel method. The results of characterizations showed that the encapsulated 700 nm Fe3O4-SiO2-TiO2 particles have a relatively uniform size distribution, an anatase TiO2 shell, and suitable magnetic properties for allowing collection in a magnetic field. These magnetic properties, large area, relative high saturation intensity, and low retentive magnetism make the particles have high dispersibility in suspension and yet enable them to be recovered well using magnetic fields. The functionality of these particles was tested by measuring the photocatalytic activity of the decolouring of methyl orange (MO and methylene blue (MB under ultraviolet light and sunlight. The results showed that the introduction of the Fe3O4-SiO2-TiO2 functional nanoparticles significantly increased the decoloration rate so that an MO solution at a concentration of 10 mg/L could be decoloured completely within 180 minutes. The particles were recovered after utilization, washing, and drying and the primary recovery ratio was 87.5%.

  10. Femtosecond Nonlinear Birefringence and Dichroism in Au:TiO_2 Composite Films


    Au:TiO2 nanocomposite film was fabricated by rf-sputtering. Both real and imaginary parts of x(3) were investigated by optical Kerr effect and pump-probe methods with femtosecond pulse with values of about 10-8 esu.


    王寅观; 杨海涛; 孙庆德; 蒋勇; 钟斐晖


    In this paper,an on-line ultrasonic H2O2 concentration meteroperating according to the relationship between the concentration,temperature and ultrasonic velocity in H2O2 solution is introduced. The ultrasonic velocities in H2O2 solution are measured at different concentrations and temperatures.The velocity-concentration coefficients and velocity-temperature coefficients of H2O2 solution are calculated. In the on-line ultrasonic H2O2 concentration meter,the ultrasonic transducer installed outside the H2O2 solution pipeline generates an ultrasonic wave pulse. The ultrasonic wave travels through the pipeline of H2O2 solution. The computer transfers the ultrasonic travel time into ultrasonic velocity. The platinum resister is installed inside the H2O2 solution pipeline. The resistor variation caused by temperature is sent to the computer through the interface. The computer calculates the ultrasonic velocity and H2O2 temperature by means of velocity-concentration coefficients and velocity-temperature coefficients. It displays and prints the value of the instant H2O2 solution concentration,and meantime displays the 8 hour curve for H2O2 solution concentration variation in the screen. It also can give alarm and output a 4—20 mA analogue signal for automatic control in the production process.

  12. Pulsed laser deposition: metal versus oxide ablation

    Doeswijk, L.M.; Rijnders, G.; Blank, D.H.A.


    We present experimental results of pulsed laser interaction with metal (Ni, Fe, Nb) and oxide (TiO2, SrTiO3, BaTiO3) targets. The influence of the laser fluence and the number of laser pulses on the resulting target morphology are discussed. Although different responses for metal and oxide targets t

  13. Impedance characteristics of nanoparticle-LiCoO2+PVDF

    Panjaitan, Elman; Kartini, Evvy; Honggowiranto, Wagiyo


    The impendance of np-LiCoO2+xPVDF, as a cathode material candidate for lithium-ion battery (LIB), has been characterized using impedance spectroscopy for x = 0, 5, 10, 15 and 20 volume percentage (%v/v) and for frequencies in the 42 Hz to 5 MHz range. Both real and imaginary components of the impedance were found to be frequency dependent, and both tend to increase for increasing PVDF (polyvinyilidene fluoride) concentration, except that for 10% PVDF both real and imaginary components of impedance are smaller than for 5%. The mechanism for relaxation time for each addition of PVDF was analyzed using Cole-Cole plots. The analysis showed that the relaxation times of the nanostructured LiCoO2 with PVDF additive is relatively constant. Further, PVDF addition increases the bulk resistance and decreases the bulk capacitance of the nanostructured LiCoO2.

  14. Promoting solution phase discharge in Li-O2 batteries containing weakly solvating electrolyte solutions

    Gao, Xiangwen; Chen, Yuhui; Johnson, Lee; Bruce, Peter G.


    On discharge, the Li-O2 battery can form a Li2O2 film on the cathode surface, leading to low capacities, low rates and early cell death, or it can form Li2O2 particles in solution, leading to high capacities at relatively high rates and avoiding early cell death. Achieving discharge in solution is important and may be encouraged by the use of high donor or acceptor number solvents or salts that dissolve the LiO2 intermediate involved in the formation of Li2O2. However, the characteristics that make high donor or acceptor number solvents good (for example, high polarity) result in them being unstable towards LiO2 or Li2O2. Here we demonstrate that introduction of the additive 2,5-di-tert-butyl-1,4-benzoquinone (DBBQ) promotes solution phase formation of Li2O2 in low-polarity and weakly solvating electrolyte solutions. Importantly, it does so while simultaneously suppressing direct reduction to Li2O2 on the cathode surface, which would otherwise lead to Li2O2 film growth and premature cell death. It also halves the overpotential during discharge, increases the capacity 80- to 100-fold and enables rates >1 mA cmareal-2 for cathodes with capacities of >4 mAh cmareal-2. The DBBQ additive operates by a new mechanism that avoids the reactive LiO2 intermediate in solution.

  15. High photoactive TiO2/SnO2 nanocomposites prepared by laser pyrolysis

    Scarisoreanu, Monica; Fleaca, Claudiu; Morjan, Ion; Niculescu, Ana-Maria; Luculescu, Catalin; Dutu, Elena; Ilie, Alina; Morjan, Iuliana; Florescu, Lavinia Gavrila; Vasile, Eugeniu; Fort, Carmen Ioana


    TiO2/SnO2 nanocomposites have been prepared by laser pyrolysis of volatile TiCl4 and SnCl4 precursors introduced together or separately in the reaction zone in the presence of air as oxidant and ethylene as sensitizer. Prior to the obtaining of TiO2/SnO2 nanocomposites with the different Sn concentrations (1.1-4.8 at.%), the best experimental conditions were identified for preparing pure anatase phase TiO2 samples considered as photoactive reference sample. The TiO2/SnO2 composites were characterized using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and UV-vis diffuse reflectance spectroscopy (DRS) techniques. The structural results show the presence of both TiO2 main phases: anatase (65-82% - the majority one) and rutile, as well as of small amounts of SnO2 tetragonal phase, all those with mean crystallite dimensions in the 8-22 nm range. Laser synthesized TiO2/SnO2 samples have a lower band gap energy and some of them (containing 1.8 or 4.8 at.% Sn) show higher photoactivity in the process of Methyl Orange solutions UV discoloration when compared with the P25 Degussa commercial sample.

  16. Electrochemical degradation of nitrobenzene by anodic oxidation on the constructed TiO2-NTs/SnO2-Sb/PbO2 electrode.

    Chen, Yong; Li, Hongyi; Liu, Weijing; Tu, Yong; Zhang, Yaohui; Han, Weiqing; Wang, Lianjun


    The interlayer of Sb-doped SnO2 (SnO2-Sb) and TiO2 nanotubes (TiO2-NTs) on Ti has been introduced into the PbO2 electrode system with the aim to reveal the mechanism of enhanced electrochemical performance of TiO2-NTs/SnO2-Sb/PbO2 electrode. In contrast with the traditional Ti/SnO2-Sb/PbO2 electrode, the constructed PbO2 electrode has a more regular and compact morphology with better oriented crystals of lower size. The TiO2-NTs/SnO2-Sb interlayer prepared by electrodeposition process improves PbO2 coating structure effectively, and enhances the electrochemical performance of PbO2 electrode. Kinetic analyses indicated that the electrochemical oxidation of nitrobenzene on the PbO2 electrodes followed pseudo-first-order reaction, and mass transport was enhanced at the constructed electrode. The accumulation of nitrocompounds of degradation intermediates on constructed electrode was lower, and almost all of the nitro groups were eliminated from aromatic rings after 6h of electrolysis. Higher combustion efficiency was obtained on the constructed TiO2-NTs/SnO2-Sb/PbO2 electrode. The intermediates of nitrobenzene oxidation were confirmed by IC and GC/MS.

  17. Effects of TiO2 coating dosage and operational parameters on a TiO2/Ag photocatalysis system for decolorizing Procion red MX-5B.

    Lin, Yu-Chih; Lee, Ho-Shan


    In this study, titanium dioxide (TiO(2)) powder was coated onto the surface of a dendritic silver (Ag) carrier to synthesize TiO(2)/Ag for decolorizing Procion red MX-5B (MX-5B), and related operation factors were also studied. The results showed that even without ultraviolet-A (UVA) irradiation, the Ag carrier from the TiO(2)/Ag catalyst had oxidizing ability, which could effectively degrade MX-5B color, but TiO(2) was ineffective. In addition, TiO(2) from TiO(2)/Ag demonstrated photocatalysis performance when irradiated, and the Ag carrier further showed an electron-scavenging ability to mitigate electron-hole pair recombination, which can improve the photocatalytic efficacy. With the oxidization and electron-scavenging ability of Ag and the photocatalysis ability of TiO(2), TiO(2)/Ag can decolor MX-5B more efficiently than TiO(2). The heavier Ag carrier also improves the solid-liquid separation of nano-TiO(2), making TiO(2)/Ag more suitable for application in slurry systems of photocatalytic water treatment. When the TiO(2)/Ag coating ratio was 50% by weight, there was a sufficient amount of TiO(2) on Ag's surface with a good distribution, and it exhibited a good photocatalysis decolorizing effect. In a study of how operational factors impact the decolorizing of MX-5B in the TiO(2)/Ag photocatalysis system with UVA irradiation (UVA-TiO(2)/Ag), the decolorization efficiency was optimal when the solution was maintained at pH 6.35. The addition of 0.01 M hydrogen peroxide (H(2)O(2)) aided the photocatalysis decolorization efficiency, although excessive H(2)O(2) reacted with hydroxyl free radicals and decreased the active groups in the system, thereby reducing the photocatalysis activity. An operating temperature of 40 degrees C was conducive to MX-5B decolorization, which was better than operating at room temperature.

  18. Synthesis of TiO2-doped SiO2 composite films and its applications

    Xiaojun Zhang; Huagui Zheng


    The TiO2-doped SiO2 composite films were prepared by two-step sol–gel method and then it was applied in the degradation of methylene red (MR) as photocatalysts. In XRD, FT–IR, and TEM investigations of these TiO2-doped SiO2 composite films, the titanium oxide species are highly dispersed in the SiO2 matrixes and exist in a tetrahedral form. And special attention has been focused on the relationship between the local structure of the titanium oxide species in the TiO2-doped SiO2 composite films and the photocatalytic reactivity in order to provide vital information for the design and application of such highly efficient photocatalytic systems in the degradation of toxic compounds diluted in a liquid phase.

  19. Structural and dielectric properties of amorphous ZrO2 and HfO2

    Ceresoli, Davide; Vanderbilt, David


    Zirconia (ZrO2) and hafnia (HfO2) are leading candidates for replacing SiO2 as the gate insulator in complementary metal-oxide semiconductor technology. Amorphous versions of these materials ( a-ZrO2 and a-HfO2 ) can be grown as metastable phases on top of a silicon buffer; while they tend to recrystallize during subsequent annealing steps, they would otherwise be of considerable interest because of the promise they hold for improved uniformity and electrical passivity. In this work, we report our theoretical studies of a-ZrO2 and a-HfO2 by first-principles density-functional methods. We construct realistic amorphous models using the “activation-relaxation” technique of Barkema and Mousseau. The structural, vibrational, and dielectric properties of the resulting models are analyzed in detail. The overall average dielectric constant is computed and found to be comparable to that of the monoclinic phase.

  20. TiO2 thin film photocatalyst

    YU Jiaguo


    It is well known that the photocatalytic activity of TiO2 thin films strongly depends on the preparing methods and post-treatment conditions, since they have a decisive influence on the chemical and physical properties of TiO2 thin films.Therefore, it is necessary to elucidate the influence of the preparation process and post-treatment conditions on the photocatalytic activity and surface microstructures of the films. This review deals with the preparation of TiO2 thin film photocatalysts by wet-chemical methods (such as sol-gel, reverse micellar and liquid phase deposition) and the comparison of various preparation methods as well as their advantage and disadvantage. Furthermore, it is discussed that the advancement of photocatalytic activity, super-hydrophilicity and bactericidal activity of TiO2 thin film photocatalyst in recent years.

  1. Electrosynthesis of nanocomposite PbO2-TiO2 and PbO2-ZrO2 materials for electrochemical systems

    Velichenkoa, A.B.; Knysha, V.A.; Luk' yanenko, T.V. [Ukrainian State Chemical Technology Univ., Dnepropetrovsk (Ukraine). Dept. of Physical Chemistry; Devilliers, D. [Pierre et Marie Curie Univ., Paris (France). Lab. de Electrolytes et Electrochimie


    This paper reported on a study that examined the electrodeposition of nanocomposite materials based on lead dioxide from suspension electrolytes with TiO2 or ZrO2 particles as a dispersed phase. The study was conducted in response to the growing interest in improving lead dioxide as an electrode material for use in lead-acid batteries with high electrocatalytic activity. The presence of foreign oxides in the suspension electrolytes caused only a quantitative difference in the PbO2 electrodeposition process without apparently changing the qualitative relationships. In the suspension, electrolyte nanocomposite PbO2 based materials were formed. It was shown that the content of foreign oxides in the composite can be changed by modifying the composition of the electrolyte as well as the conditions of electrodeposition. 10 refs., 2 figs.

  2. Hydrothermal synthesis, structure and photocatalytic property of nano-TiO2-MnO2

    DING; Shiwen(丁士文); WANG; Liyong(王利勇); ZHANG; Shaoyan(张绍岩); ZHOU; Qiuxiang(周秋香); DING; Yu(丁宇); LIU; Shujuan(刘淑娟); LIU; Yanchao(刘燕朝); KANG; Quanying(康全影)


    TiCl4 and MnSO4·H2O as raw materials are hydrolyzed stiochiometrically, following the intermediate of oxide hydrating reacts at 150℃, 0.5 Mpa in high-pressure reactor, after filtering, washing and drying, nanometric TiO2-MnO2 (Ti1-xMnxO2) is prepared. The effects of the reaction temperature and time on nanometric TiO2-MnO2 are also discussed. XRD shows that the product is TiO2-MnO2 with amorphous phase. After being sintered at above 780℃, it transfers into Ti1-xMnxO2 with a rutile structure. TEM shows that TiO2-MnO2 is the spherical particle. And the average diameter of the particles is 20 nm. The optical absorbance was determined by UV-265 spectrophotometer after dispersing the sample in the mixture of water and glycerol with the ratio of 1︰1 equably. It is found that the nano-material possesses the advantages of both nano-TiO2 and nano-MnO2, and it has strong absorption in the UV and visible region. Photodegradation of dyes in an aqueous solution is investigated using nanometricTiO2-MnO2 as a photocatalyst. The results show that after 60 min illumination, the decolorization rate of the acidic red B and acidic black 234 dye can be as high as 100%.

  3. 含二氧化锆陶瓷的热力学%Thermodynamics of some ZrO2-containing ceramics


    Thermodynamic assessment in the ternary systems ZrO2-CeO2-Y2O3 ,ZrO2-CeO2-Ce2O3 and the limiting binaries ZrO2-Y2O3,ZrO2-CeO2 ,CeO2-Y2O3, ZrO2-Ce2O3, CeO2-Ce2O3 as well as the modeling for oxides are reviewed comprehensively. Based on the recent estimations on the YO1.5 -CeO2, ZrO2 -CeO2 and ZrO2-YO1.5 systems, isothermal sections at 1 273 and 1 973 K of the ternary CeO2-ZrO2-YO1.5 system are calculated. In the system of ZrO2-CeO2-Ce2O3, the complex relation between the nonstoichiometry (y) in CeO2- y, the composition of the ZrO2-CeO2 solid solution and the oxygen partial pressure ( Po2 ) for different ZrO2 containing solid solutions Cez Zr1 - z O2 - x are evaluated from 1 473 to 1 773 K. The relation between the degree of Ce+ 4 reduction to Ce + 3 under different Po2 in the fluorite CeO2 - y and Cez Zr1- z O2 x solid solutions at different temperatures can be used as a guide in the development of functional ceramics.

  4. Pulsed electromagnetic field therapy for management of osteoarthritis-related pain, stiffness and physical function: clinical experience in the elderly.

    Iannitti, Tommaso; Fistetto, Gregorio; Esposito, Anna; Rottigni, Valentina; Palmieri, Beniamino


    Pulsed electromagnetic field (PEMF) therapy has shown promising therapeutic effectiveness on bone- and cartilage-related pathologies, being also safe for management of knee osteoarthritis. The aim of this study was to investigate the clinical efficacy of a PEMF device for management of knee osteoarthritis in elderly patients. A total of 33 patients were screened, and 28 patients, aged between 60 and 83 and affected by bilateral knee osteoarthritis, were enrolled in this study. They received PEMF therapy on the right leg for a total of three 30-minute sessions per week for a period of 6 weeks, while the left leg did not receive any treatment and served as control. An intravenous drip containing ketoprofen, sodium clodronate, glucosamine sulfate, calcitonin, and ascorbic acid, for a total volume of 500 mL, was administered during PEMF therapy. At baseline and 3 months post-PEMF therapy, Visual Analog Scale (VAS) was used to assess knee pain and Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) was used to measure knee pain, stiffness and physical function. Changes in VAS and WOMAC scores were calculated for both knees as baseline minus post-treatment. A two sample Student's t-test, comparing change in knee-related VAS pain for PEMF-treated leg (49.8 ± 2.03) vs control leg (11 ± 1.1), showed a significant difference in favor of PEMF therapy (P physical function for PEMF-treated leg (8.5 ± 0.4, 3.5 ± 0.2, 38.5 ± 2.08, respectively) vs control leg (2.6 ± 0.2; 1.6 ± 0.1; 4.5 ± 0.5 respectively), also showed a significant difference in favor of PEMF therapy (P therapy were observed. The present study shows that PEMF therapy improves pain, stiffness and physical function in elderly patients affected by knee osteoarthritis.

  5. Relative Humidity of 40% Inhibiting the Increase of Pulse Rate, Body Temperature, and Blood Lactic Acid During Exercise

    Nengah Sandi


    Full Text Available Background: Excessive sweating of the body is a reaction to decrease the heat caused by prolonged exercise at high relative humidity (RH. This situation may cause an increase in pulse rate (PR, body temperature (BT, and blood lactic acid (BLA workout. Objective: This study aimed to prove that a RH of 40% better than a RH of 50% and 60% RH in inhibiting the increase of PR, BT, and BLA during exercise. Methods: The study was conducted on 54 samples randomly selected from the IKIP PGRI Bali students. The samples were divided into three groups, and each group was given cycling exercise with a load of 80 Watt for 2 x 30 minutes with rest between sets for five minutes. Group-1 of cycling at 40% of RH, Group-2 at a RH of 50%, and the Group-3 at a RH of 60%. Data PR, BT, and BLA taken before and during exercise. The mean difference between groups before and during exercise were analyzed by One-way Anova and a further test used Least Significant Difference (LSD. Significance used was α = 0.05. Results: The mean of PR during exercise was significantly different between groups with p = 0.045, the mean of BT during exercises was significantly different between groups with p = 0.006, and the mean of BLA during exercises was significantly different between groups with p = 0.005 (p <0.05. Also found that PR, BT, and BLA during exercise at 40% RH was lower than 50% RH and 60% RH (p <0.05. Conclusion: Thus, the RH of 40% was better than RH of 50% and 60 % in inhibiting the increase of PR, BT, and BLA during exercise. Therefore, when practiced in a closed room is expected at 40% relative humidity.

  6. 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.

  7. Synthesis and Characterization of CeO2-SiO2 Nanoparticles by Microwave-Assisted Irradiation Method for Photocatalytic Oxidation of Methylene Blue Dye

    R. M. Mohamed


    Full Text Available CeO2-SiO2 nanoparticles were synthesized for the first time by a facile microwave-assisted irradiation process. The effect of irradiation time of microwave was studied. The materials were characterized by N2 adsorption, XRD, UV-vis/DR, and TEM. All solids showed mesoporous textures with high surface areas, relatively small pore size diameters, and large pore volume. The X-ray diffraction results indicated that the as-synthesized nanoparticles exhibited cubic CeO2 without impurities and amorphous silica. The transmission electron microscopy (TEM images revealed that the particle size of CeO2-SiO2 nanoparticles, which were prepared by microwave method for 30 min irradiation times, was around 8 nm. The photocatalytic activities were evaluated by the decomposition of methylene blue dye under UV light irradiations. The results showed that the irradiation under the microwave produced CeO2-SiO2 nanoparticles, which have the best crystallinity under a shorter irradiation time. This indicates that the introduction of the microwave really can save energy and time with faster kinetics of crystallization. The sample prepared by 30 min microwave irradiation time exhibited the highest photocatalytic activity. The photocatalytic activity of CeO2-SiO2 nanoparticles, which were prepared by 30 min irradiation times was found to have better performance than commercial reference P25.

  8. Effects of CeO2 Nanoparticles on Terrestrial Isopod Porcellio scaber: Comparison of CeO2 Biological Potential with Other Nanoparticles.

    Malev, Olga; Trebše, Polonca; Piecha, Małgorzata; Novak, Sara; Budič, Bojan; Dramićanin, Miroslav D; Drobne, Damjana


    Nano-sized cerium dioxide (CeO2) particles are emerging as an environmental issue due to their extensive use in automobile industries as fuel additives. Limited information is available on the potential toxicity of CeO2 nanoparticles (NPs) on terrestrial invertebrates through dietary exposure. In the present study, the toxic effects of CeO2 NPs on the model soil organism Porcellio scaber were evaluated. Nanotoxicity was assessed by monitoring the lipid peroxidation (LP) level and feeding rate after 14-days exposure to food amended with nano CeO2. The exposure concentration of 1000 μg of CeO2 NPs g(-1) dry weight food for 14 days significantly increased both the feeding rate and LP. Thus, this exposure dose is considered the lowest observed effect dose. At higher exposure doses of 2000 and 5000 μg of CeO2 NPs g(-1) dry weight food, NPs significantly decreased the feeding rate and increased the LP level. Comparative studies showed that CeO2 NPs are more biologically potent than TiO2 NPs, ZnO NPs, CuO NPs, CoFe2O4 NPs, and Ag NPs based on feeding rate using the same model organism and experimental setup. Based on comparative metal oxide NPs toxicities, the present results contribute to the knowledge related to the ecotoxicological effects of CeO2 NPs in terrestrial invertebrates exposed through feeding.

  9. Study of concentration-dependent cobalt ion doping of TiO2 and TiO(2-x)Nx at the nanoscale.

    Gole, James L; Prokes, Sharka M; Glembocki, O J; Wang, Junwei; Qiu, Xiaofeng; Burda, Clemens


    Experiments with a porous sol-gel generated TiO(2) nanocolloid and its corresponding oxynitride TiO(2-x)N(x) are carried out to evaluate those transformations which accompany additional doping with transition metals. In this study, doping with cobalt (Co(ii)) ions is evaluated using a combination of core level and VB-photoelectron and optical spectroscopy, complementing data obtained from Raman spectroscopy. Raman spectroscopy suggests that cobalt doping of porous sol-gel generated anatase TiO(2) and nitridated TiO(2-x)N(x) introduces a spinel-like structure into the TiO(2) and TiO(2-x)N(x) lattices. TEM and XPS data complemented by valence band-photoelectron spectra demonstrate that metallic cobalt clusters are not formed even at high doping levels. As evidenced by Raman spectroscopy, the creation of a spinel-like structure is commensurate with the room temperature conversion of the oxide and its oxynitride from the anatase to the rutile form. The onset of this kinetically driven process correlates with the formation of spinel sites within the TiO(2) and TiO(2-x)N(x) particles. Despite their visible light absorption, the photocatalytic activity of these cobalt seeded systems is diminished relative to the oxynitride TiO(2-x)N(x).

  10. 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.

  11. Graphene/SnO2 nanocomposite-modified electrode for electrochemical detection of dopamine

    R. Nurzulaikha


    Full Text Available A graphene-tin oxide (G-SnO2 nanocomposite was prepared via a facile hydrothermal route using graphene oxide and Sn precursor solution without addition of any surfactant. The hydrothermally synthesized G-SnO2 nanocomposite was characterized using a field emission scanning electron microscope (FESEM, high resolution transmission electron microscope (HRTEM, X-ray diffraction (XRD, and energy dispersive spectroscopy (EDS. A homogeneous deposition of SnO2 nanoparticles with an average particle size of 10 nm on the graphene was observed in the FESEM and HRTEM images. The G-SnO2 nanocomposite was used to fabricate a modified electrode for the electrochemical detection of dopamine (DA in the presence of ascorbic acid (AA. Differential pulse voltammetry (DPV showed a limit of detection (LoD of 1 μM (S/N = 3 in the presence of ascorbic acid (AA.

  12. Facile strategy and mechanism for orthorhombic SnO2 thin films

    Chen, Zhiwen; Lai, Joseph K. L.; Shek, Chan-Hung


    Orthorhombic phase SnO2 is a material with unknown optical, electrical, and gas-sensing properties. It was found previously only at high pressures and temperatures. A facile strategy for the synthesis of orthorhombic SnO2 is of fundamental importance. Using pulsed-laser deposition, the authors report a kind of experimental realization of a pure orthorhombic SnO2 thin film under low pressure and temperature that are much lower than those of traditional methods. The optical properties of an orthorhombic SnO2 thin film were measured by spectrophotometric transmittance. The oxygen exchange reaction mechanism at the grain interfaces was proposed to explain the formation and optical properties of this orthorhombic phase.

  13. Nonlinear optical properties and optical limiting measurements of graphene oxide - Ag@TiO2 compounds

    Ebrahimi, M.; Zakery, A.; Karimipour, M.; Molaei, M.


    In this work Graphene Oxide (GO), Ag@TiO2 core-shells and GO-Ag@TiO2 compounds were prepared and experimentally verified. Using a low power laser diode with 532 nm wavelength, the magnitude and the sign of the nonlinear refractive index and nonlinear absorption were determined by the Z-scan technique. It was observed that the nonlinear absorption of GO-Ag@TiO2 mixture was higher than pure GO. The optical limiting effect of these samples was also investigated using the 2nd harmonics of a pulsed Nd-YAG laser at 532 nm. Our results showed that the sole Ag@TiO2 didn't show any appreciable optical limiting effect, however after just mixing with graphene oxide the threshold of optical limiting was increased and the compound showed an enhancement of optical limiting behavior compared to GO itself. The presented results are discussed and compared with other literature reports.

  14. Carbon dioxide and water adsorption on highly epitaxial Delafossite CuFeO2 thin film

    Rojas, S.; Joshi, T.; Borisov, P.; Sarabia, M.; Lederman, D.; Cabrera, A. L.


    Thermal programmed desorption (TPD) of CO2 and H2O from a 200 nm thick CuFeO2 Delafossite surface was performed in a standard UHV chamber, The CuFeO2 thin film grown using Pulsed Laser Deposition (PLD) over an Al2O3 (0001) substrate with controlled O2 atmosphere resulted with highly epitaxial crystal structure. The adsorption/desorption of CO2 and H2O process was also monitored with X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). Our results revealed that carbon dioxide interacts with CuFeO2 forming Fe carbonates compounds on its surface. Hydroxides were also formed on the surface due to water presence. Using TPD data, Arrhenius plots for CO2 and water desorption were done and activation energy for desorption was obtained. Funds FONDECyT 1130372; Thanks to P. Ferrari.

  15. Resistive Switching Characteristics in TiO2/LaAlO3 Heterostructures Sandwiched in Pt Electrodes

    Yuyuan Cao


    Full Text Available TiO2/LaAlO3 (TiO2/LAO heterostructures have been deposited on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition. Resistive switching characteristics of Pt/TiO2/LAO/Pt have been studied and discussed in comparison with those of Pt/TiO2/Pt. It is observed that the switching uniformity and the ON/OFF resistance ratio can be greatly improved by introducing the LAO layer. The observed resistive switching characteristics are discussed as a function of LAO thickness and explained by the preferential formation and rupture of conductive filaments, composed of oxygen vacancies, in the LAO layer.

  16. The impact of left ventricular preload reduction on cardiac pulsed doppler indices during hemodialysis and its relation to intra-dialysis hypotension: A pulsed doppler study

    Alarrayed Sameer


    Full Text Available Fluid status in the body plays an important role on left ventricular (LV filling in patients with end-stage renal disease (ESRD on regular hemodialysis (HD, and plays a role in intra-dialysis hemo-dynamic derangement. Fifty-two patients with ESRD on regular HD, including 34 males with a mean age of 45.5 ± 13 years (range 18-72 years, were studied. All patients underwent Echo-pulsed Doppler study before and immediately after a HD session. The Echo Doppler indices noted were: LV cavity dimension and wall thickness, LV ejection fraction (LVEF%, trans-mitral early diastolic filling velocity (E wave, atrial filling diastolic velocity (A wave, E/A ratio, Deceleration Time (DT of E wave, Isovolumic relaxation time (IVRT, Aortic Velocity Integral (AVI and Inferior Vena Cava Diameter (VCD at expiration. Patients were divided into two groups according to the amount of net ultra filtrate loss after HD. Group I comprised of 25 patients with fluid loss of < 2 liters, and Group II had 27 patients with fluid loss > 2 liters. During the HD session, each patient was observed for the development of acute clinical events such as arterial hypotension (systolic BP less than 90 mmHg, chest pain and arrhythmias. There was a significant difference between the two groups in the mean values, pre- and post- HD, of reduction of E wave velocity (p< 0.01, the reduction of E/A ratio (p< 0.05, the increment in DT of E wave (p< 0.05, the reduction in AVI (p< 0.01 and the reduction of VCD (p< 0.05. There was no significant difference between the groups in the reduction of A wave velocity and the reduction of IVRT. Among the study patients, 11 (21% developed systolic hypo-tension during HD. The pre-dialysis mean values of E/A ratio and DT of E wave in patients who developed hypotension compared to those who did not was 0.7 ± 0.2 vs 1.1 ± 0.2.1 (p< 0.001 and 246 ± 40 vs 224 ± 34 msec (p< 0.05, respectively. Our study suggests that preload reduction in patients with ESRD on

  17. Preparation of TiO2 Nanoparticles by Hydrothermal Method and its Application for Photoelectrochemical Cell%水热法合成纳米TiO2及其在Gr?tzel电池中的应用

    高恩勤; 张莉; 杨迈之; 蔡生民


    By varying the hydrolysis and hydrothermal processing parameters in preparing TiO2 nanoparticles different sizes of TiO2 nanoparticles are obtained.(1) At higher autoclaving temperature,lower pH and longer autoclaving period,larger sizes of TiO2 nanoparticles are prepared.(2) The nanoporous electrodes made from sintering smaller TiO2 nanoparticles show relatively poor IPCE and low absorption in UV-Vis spectrum,(3) Higher IPCE can be achieved with TiO2 nanoporous electrodes made from sintering larger TiO2 nanoparticles.These electrodes are suitable for studying behavior of the photoelectrochemistry of dye sensitized nanoporous electrodes.

  18. Design of a finger base-type pulse oximeter

    Lin, Bor-Shyh; Huang, Cheng-Yang; Chen, Chien-Yue; Lin, Jiun-Hung


    A pulse oximeter is a common medical instrument used for noninvasively monitoring arterial oxygen saturation (SpO2). Currently, the fingertip-type pulse oximeter is the prevalent type of pulse oximeter used. However, it is inconvenient for long-term monitoring, such as that under motion. In this study, a wearable and wireless finger base-type pulse oximeter was designed and implemented using the tissue optical simulation technique and the Monte Carlo method. The results revealed that a design involving placing the light source at 135°-165° and placing the detector at 75°-90° or 90°-105° yields the optimal conditions for measuring SpO2. Finally, the wearable and wireless finger base-type pulse oximeter was implemented and compared with the commercial fingertip-type pulse oximeter. The experimental results showed that the proposed optimal finger base-type pulse oximeter design can facilitate precise SpO2 measurement.

  19. O2 solubility in aqueous media determined by a kinetic method.

    Reynafarje, B; Costa, L E; Lehninger, A L


    A kinetic method for the determination of O2 solubility in air-saturated aqueous solutions of widely varying composition and temperature is described. It is based on the precise molar stoichiometry between the rates of uptake of H+ and O2, measured with response-matched electrodes, in the reaction NADH + H+ + 1/2O2----NAD+ + H2O, catalyzed by an NADH oxidase preparation. To the initially anaerobic test system, which contains an excess of NADH and NADH oxidase in a buffered medium, an aliquot of the O2-containing solution to be tested is added and the rates of both O2 uptake and H+ uptake are recorded; the H+ electrode is calibrated against standard HCl. From these data the amount of O2 in the aliquot is calculated. Some representative values for O2 solubility at 25 degrees C and 760 mm in air-saturated systems are (i) distilled H2O, 516 nmol O/ml, (ii) 0.15 M KCl, 480 nmol O/ml, and (iii) 0.25 M sucrose, 458 nmol O/ml. Data and equations are also given for the solubility of O2 at 760 mm in air-saturated and lightly buffered 0.15 M KCl and 0.25 M sucrose over the range 5 to 40 degrees C. In the method described the rates of O2 and H+ uptake are precisely linear and stoichiometric when NADH is present in large excess over O2. However, when O2 is in excess and small additions of 340-nm-standardized NADH are made, as in earlier methods based on NADH oxidation, the endpoint is approached very gradually and tends to overestimate O2 solubility, owing to (i) the higher Km for NADH than for O2, (ii) the relatively slow response of the Clark O2 electrode, and (iii) the incomplete oxidation of NADH in the presence of 340-nm-absorbing inhibitory substances.

  20. Pulse oximetry: fundamentals and technology update

    Nitzan M


    Full Text Available Meir Nitzan,1 Ayal Romem,2 Robert Koppel31Department of Physics/Electro-Optics, Jerusalem College of Technology, Jerusalem, Israel; 2Pulmonary Institute, Shaare Zedek Medical Center, Jerusalem, Israel; 3Neonatal/Perinatal Medicine, Cohen Children's Medical Center of New York/North Shore-LIJ Health System, New Hyde Park, NY, United StatesAbstract: Oxygen saturation in the arterial blood (SaO2 provides information on the adequacy of respiratory function. SaO2 can be assessed noninvasively by pulse oximetry, which is based on photoplethysmographic pulses in two wavelengths, generally in the red and infrared regions. The calibration of the measured photoplethysmographic signals is performed empirically for each type of commercial pulse-oximeter sensor, utilizing in vitro measurement of SaO2 in extracted arterial blood by means of co-oximetry. Due to the discrepancy between the measurement of SaO2 by pulse oximetry and the invasive technique, the former is denoted as SpO2. Manufacturers of pulse oximeters generally claim an accuracy of 2%, evaluated by the standard deviation (SD of the differences between SpO2 and SaO2, measured simultaneously in healthy subjects. However, an SD of 2% reflects an expected error of 4% (two SDs or more in 5% of the examinations, which is in accordance with an error of 3%–4%, reported in clinical studies. This level of accuracy is sufficient for the detection of a significant decline in respiratory function in patients, and pulse oximetry has been accepted as a reliable technique for that purpose. The accuracy of SpO2 measurement is insufficient in several situations, such as critically ill patients receiving supplemental oxygen, and can be hazardous if it leads to elevated values of oxygen partial pressure in blood. In particular, preterm newborns are vulnerable to retinopathy of prematurity induced by high oxygen concentration in the blood. The low accuracy of SpO2 measurement in critically ill patients and newborns

  1. Nanoimprint lithography using TiO2-SiO2 ultraviolet curable materials

    Takei, Satoshi


    Ultraviolet nanoimprint lithography has great potential for commercial device applications that are closest to production such as optical gratings, planar waveguides, photonic crystals, semiconductor, displays, solar cell panel, sensors, highbrightness LEDs, OLEDs, and optical data storage. I report and demonstrate the newly TiO2-SiO2 ultraviolet curable materials with 20-25 wt% ratio of high titanium for CF4/O2 etch selectivity using nanoimprint lithography process. The multiple structured three-dimensional micro- and nanolines patterns were observed to be successfully patterned over the large areas. The effect of titanium concentration on CF4/O2 etch selectivity with pattern transferring carbon layer imprinting time was investigated. CF4/O2 etching rate of the TiO2-SiO2 ultraviolet curable material was approximately 3.8 times lower than that of the referenced SiO2 sol-gel ultraviolet curable material. The TiO2-SiO2 ultraviolet curable material with high titanium concentration has been proved to be versatile in advanced nanofabrication.

  2. Lasing effects in new Nd3+-doped TeO2-Nb2O5-WO3 bulk glasses

    Carreaud, J.; Labruyère, A.; Dardar, H.; Moisy, F.; Duclère, J.-R.; Couderc, V.; Bertrand, A.; Dutreilh-Colas, M.; Delaizir, G.; Hayakawa, T.; Crunteanu, A.; Thomas, P.


    This paper demonstrates for the first time continuous wave (cw) and pulsed lasing effects in a 75TeO2-20NbO2.5-5WO3 glass doped with 1 mol.% in Nd3+. It is divided into two parts: The first part treats all the aspects related to the elaboration and the characterization of the materials. Thus, glasses elaborated within the TeO2-Nb2O5-WO3 ternary system show a rather high glass transition temperature Tg ∼ 375 °C, with an excellent thermal stability of ∼160 °C. Compared to glasses synthesized in either TeO2-Nb2O5 or TeO2-WO3 binary systems, glasses fabricated within such system show improved mechanical performances, with larger Young's modulus values. The structural characteristics of the samples, studied by Raman spectroscopy, are also presented. Linear optical properties (refractive index and extinction coefficient) are accessed by spectroscopic ellipsometry. As well, the optical transmission of the various bulk glasses is measured, in the case of both uncoated and coated glasses. In particular, specific anti-reflective coatings at 808 nm (laser diode pump wavelength) and 1064 nm (laser emission wavelength) are respectively deposited on the two surfaces of the sample in order to minimize the losses due to Fresnel reflections at the two glass/air interfaces. In addition, another specific surface treatment (Rmax at 1064 nm) was employed to serve as the back mirror of the laser cavity. The optical transmission data testified to the real efficiency of all these coatings. Finally, the photoluminescence properties (emission and excitation spectra, and luminescence decay curve) of the Nd3+-doped glasses, measured at room temperature for bulk samples, and as a function of temperature for powder glasses, are discussed. The second part is focused on evidencing (cw) and pulsed lasing effects in such coated bulk lasers. Cylindric samples of only a few millimeters in height and in diameter were tested and led to a laser emission around 1064 nm, characterized by a very low

  3. Kinetics of HO2 + HO2 -> H2O2 + O2: Implications for Stratospheric H2O2

    Christensen, L. E.; Okumura, M.; Sander, S. P.; Salawitch, R. J.; Toon, G. C.; Sen, B.; Blavier, J.-F.; Jucks, K. W.


    The reaction HO2 + HO2 -> H2O2 + O2refid="df01" type="formula">(1) has been studied at 100 Torr and 222 K to 295 K. Experiments employing photolysis of Cl2/CH3OH/O2/N2 and F2/H2/O2/N2 gas mixtures to produce HO2 confirmed that methanol enhanced the observed reaction rate. At 100 Torr, zero methanol, k1 = (8.8 +/- 0.9) 10-13 × exp[(210 +/- 26)/T] cm3 molecule-1 s-1 (2σ uncertainties), which agrees with current recommendations at 295 K but is nearly 2 times slower at 231 K. The general expression for k1, which includes the dependence on bath gas density, is k1 = (1.5 +/- 0.2) × 10-12 × exp[(19 +/- 31)/T] + 1.7 × 10-33 × [M] × exp[1000/T], where the second term is taken from the JPL00-3 recommendation. The revised rate largely accounts for a discrepancy between modeled and measured [H2O2] in the lower to middle stratosphere.

  4. Preparation and Characterization of Nanocrystalline CeO2 by Precipitation Method

    董相廷; 李明; 张伟; 刘桂霞; 洪广言


    CeO2 nanocrystalline particulates with different sizes were prepared by precipitation method using ethanol as dispersive and protective reagent. XRD spectra show that the synthesized CeO2 has cubic crystalline structure of space group O5H-FM3M, when calcination temperature is in the range of 250~800 ℃. TEM images reveal that CeO2 particles are spherical in shape. The average size of the particles increases with the increase of calcination temperature. Thermogravimetric analysis indicates that the weight loss of precursor mainly depends on the calcination temperature, and little depends on the calcination time. Measurements of CeO2 relative density show that the relative density of CeO2 nanocrystalline powders increases with increasing CeO2 particle size.

  5. Study of the role of oxygen vacancies as active sites in reduced graphene oxide-modified TiO2.

    Zhang, Yanhui; Dai, Rongying; Hu, Shirong


    In recent years, substantial efforts have been devoted to exploring reduced graphene oxide/TiO2 (RGO/TiO2) composite materials; however, there is still a paucity of reports on the construction of reduced graphene oxide/TiO2 with oxygen vacancies (RGO/TiO2-OV) via a facile two-step wet chemistry approach. In this work, we show a proof-of-concept study follow RGO introduced into TiO2 with oxygen vacancies, the role of oxygen vacancies as active sites in reduced graphene oxide-modified TiO2. The photocatalytic performance and related properties of blank-TiO2, blank-TiO2 with oxygen vacancies (blank-TiO2-OV), RGO/TiO2, and RGO/TiO2-OV were comparatively studied. It was found that due to the incorporation of RGO, RGO/TiO2 and RGO/TiO2-OV exhibit a higher photocatalytic performance under simulated solar light irradiation than their counterparts without rGO. More importantly, it was found that blank-TiO2 has a higher photocatalytic activity than blank-TiO2-OV under simulated solar light irradiation. However, RGO/TiO2 shows a lower photocatalytic activity than rGO/TiO2-OV. By a series of combined techniques, we found that the introduction of a component, such as RGO, with the matched energy band to TiO2 could lead to the formation of a long-lived electron-transfer state, thus prolonging the lifetime of the photogenerated charge carriers. Furthermore, during the photocatalytic process, RGO could tune the role of oxygen vacancies in TiO2 from recombination centers to active sites. These findings are of great significance for the design of effective photocatalytic materials in the field of solar energy conversion.

  6. -AgCoO2/-ZnO heterojunction diode grown by rf magnetron sputtering

    K A Vanaja; Umananda M Bhatta; R S Ajimsha; S Jayalekshmi; M K Jayaraj


    -type transparent semiconducting AgCoO2 thin films were deposited by rf magnetron sputtering of sintered AgCoO2 target. The AgCoO2 films grown by rf sputtering were highly -axis oriented showing only (001) reflections in the X-ray diffraction pattern unlike in the case of amorphous films grown by pulsed laser deposition (PLD). The bulk powder of AgCoO2 was synthesized by hydrothermal process. The optical bandgap was estimated as 4.15 eV and has a transmission of about 50% in the visible region. The temperature dependence of conductivity shows a semiconducting behaviour. The positive sign of Seebeck coefficient (+220 VK–1) indicates -type conductivity. Transparent – heterojunction on glass substrate was fabricated by rf magnetron sputtering of -AgCoO2 and -type ZnO : Al thin films. The structure of the diode was glass/ITO/-ZnO/-AgCoO2. The junction between -AgCoO2 and -ZnO was found to be rectifying.

  7. High pulse pressure is related to risk of type 2 diabetes mellitus in Chinese middle-aged females.

    Zhang, Lu; Wang, Bingyuan; Wang, Chongjian; Li, Linlin; Ren, Yongcheng; Zhang, Hongyan; Yang, Xiangyu; Zhao, Yang; Han, Chengyi; Zhou, Junmei; Luo, Xinping; Hu, Dongsheng


    To examine the association of risk of incident type 2 diabetes mellitus (T2DM) with high pulse pressure (PP) by sex. We performed a prospective cohort study of 12,272 eligible participants (4664 males and 7608 females) without diabetes at baseline. Participants were classified as having normal PP (20-60mmHg) and high PP (>60mmHg) at baseline. The analysis was further stratified by sex, quartiles of age and high PP categories. During 6years of follow-up, T2DM developed in 775 participants and the incidence was 10.57/1000person-years. With PP 70 to 76mmHg, the multivariable adjusted hazard ratio (HR) (95% confidence interval) for incident T2DM in females was 1.722 (1.093-2.714) after adjustment for baseline age, smoking, alcohol intake, physical activity level and family history of T2DM, and 1.634 (1.037-2.575) after adjustment for the above factors and body mass index, waist circumference, blood lipid levels and fasting plasma glucose (FPG) category. After stratification by quartiles of age, for females aged 52 to 59, the multivariable adjusted HRs (95% CI) for high PP as compared to normal PP were 2.263 (1.517-3.377) and 2.140 (1.426-3.210) in different models. During follow-up, levels of FPG, fasting plasma insulin and homeostatic model assessment of insulin resistance index (HOMA-IR) were higher in females with higher than normal PP group, but β-cell function was impaired in the high PP group (PHigh PP may be related to incident T2DM among female in China, especially women 52 to 59years old. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  8. An Experimental Exploration on the Characterization of TiO2 Using Sol-Gel

    Suman Malik


    Full Text Available TiO2 is defined as the photo catalyst and the poor adsorption so that the improvement of TiO2 decomposition is performed for the purification of the organic pollutants in water and air. In this paper, the TiO2 is defined and explored under the structure analysis. It also includes the deposition optimization using sol-gel approach. The works also include the relative experimentation for the purification process.:

  9. Growth Enhancement of Radish Sprouts Induced by Low Pressure O2 Radio Frequency Discharge Plasma Irradiation

    Kitazaki, Satoshi; Koga, Kazunori; Shiratani, Masaharu; Hayashi, Nobuya


    We studied growth enhancement of radish sprouts (Raphanus sativus L.) induced by low pressure O2 radio frequency (RF) discharge plasma irradiation. The average length of radish sprouts cultivated for 7 days after O2 plasma irradiation is 30-60% greater than that without irradiation. O2 plasma irradiation does not affect seed germination. The experimental results reveal that oxygen related radicals strongly enhance growth, whereas ions and photons do not.

  10. The fluxes of H2O2 and O2 can be used to evaluate seed germination and vigor of Caragana korshinskii.

    Li, Jiaguo; Wang, Yu; Pritchard, Hugh W; Wang, Xiaofeng


    Seed deterioration is detrimental to plant germplasm conservation, and predicting seed germination and vigor with reliability and sensitivity means is urgently needed for practical problems. We investigated the link between hydrogen peroxide (H2O2) flux, oxygen influx and seed vigor of Caragana korshinskii by the non-invasive micro-test technique (NMT). Some related physiological and biochemical changes in seeds were also determined to further explain the changes in the molecular fluxes. The results showed that there was a good linear relationship between germination and H2O2 flux, and that O2 influx was more suitable for assessing seed vigor. H2O2 flux changed relatively little initially, mainly affected by antioxidants (APX, CAT and GSH) and H2O2 content; afterward, the efflux increased more and more rapidly due to high membrane permeability. With the damage of mitochondrial respiration and membrane integrity, O2 influx was gradually reduced. We propose that monitoring H2O2 and O2 fluxes by NMT may be a reliable and sensitive method to evaluate seed germination and vigor.

  11. Core-Shell MnO2-SiO2 Nanorods for Catalyzing the Removal of Dyes from Water

    Wei Gong; Xianling Meng; Xiaohong Tang; Peijun Ji


    This work presented a novel core-shell MnO2@m-SiO2 for catalyzing the removal of dyes from wastewater. MnO2 nanorods were sequentially coated with polydopamine (PDA) and polyethyleneimine (PEI) forming MnO2@PDA-PEI. By taking advantage of the positively charged amine groups, MnO2@PDA-PEI was further silicificated, forming MnO2@PDA-PEI-SiO2. After calcination, the composite MnO2@m-SiO2 was finally obtained. MnO2 nanorod is the core and mesoporous SiO2 (m-SiO2) is the shell. MnO2@m-SiO2 has bee...

  12. Synthesis, Characterization, and Relative Study on the Catalytic Activity of Zinc Oxide Nanoparticles Doped MnCO3, –MnO2, and –Mn2O3 Nanocomposites for Aerial Oxidation of Alcohols

    Mohamed E. Assal


    Full Text Available Zinc oxide nanoparticles doped manganese carbonate catalysts [X% ZnOx–MnCO3] (where X = 0–7 were prepared via a facile and straightforward coprecipitation procedure, which upon different calcination treatments yields different manganese oxides, that is, [X% ZnOx–MnO2] and [X% ZnOx–Mn2O3]. A comparative catalytic study was conducted to evaluate the catalytic efficiency between carbonates and oxides for the selective oxidation of secondary alcohols to corresponding ketones using molecular oxygen as a green oxidizing agent without using any additives or bases. The prepared catalysts were characterized by different techniques such as SEM, EDX, XRD, TEM, TGA, BET, and FTIR spectroscopy. The 1% ZnOx–MnCO3 calcined at 300°C exhibited the best catalytic performance and possessed highest surface area, suggesting that the calcination temperature and surface area play a significant role in the alcohol oxidation. The 1% ZnOx–MnCO3 catalyst exhibited superior catalytic performance and selectivity in the aerial oxidation of 1-phenylethanol, where 100% alcohol conversion and more than 99% product selectivity were obtained in only 5 min with superior specific activity (48 mmol·g−1·h−1 and 390.6 turnover frequency (TOF. The specific activity obtained is the highest so far (to the best of our knowledge compared to the catalysts already reported in the literatures used for the oxidation of 1-phenylethanol. It was found that ZnOx nanoparticles play an essential role in enhancing the catalytic efficiency for the selective oxidation of alcohols. The scope of the oxidation process is extended to different types of alcohols. A variety of primary, benzylic, aliphatic, allylic, and heteroaromatic alcohols were selectively oxidized into their corresponding carbonyls with 100% convertibility without overoxidation to the carboxylic acids under base-free conditions.

  13. Synthesis and Modification of Zn-doped TiO2 Nanoparticles for the Photocatalytic Degradation of Tetracycline.

    Pang, Shuo; Huang, Ji-Guo; Su, Yun; Geng, Bo; Lei, Su-Yuan; Huang, Yu-Ting; Lyu, Cong; Liu, Xing-Juan


    The synthesis of Zn-doped TiO2 nanoparticles by solgel method was investigated in this study, as well as its modification by H2 O2 . The catalyst was characterized by transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller, UV-visible reflectance spectra and X-ray photoelectron spectroscopy (XPS). The results indicated that doping Zn into TiO2 nanoparticles could inhibit the transformation from anatase phase to rutile phase. Zn existed as the second valence oxidation state in the Zn-doped TiO2 . Zn-doped TiO2 that was synthesized by 5% Zn doping at 450°C exhibited the best photocatalytic activity. Then, the H2 O2 modification further enhanced the photocatalytic activity. Zn doping and H2 O2 modifying narrowed the band gap and efficiently increased the optical absorption in visible region. The optimal degradation rate of tetracycline by Zn-doped TiO2 and H2 O2 modified Zn-doped TiO2 was 85.27% and 88.14%. Peroxide groups were detected in XPS analysis of H2 O2 modified Zn-doped TiO2 , favoring the adsorption of visible light. Furthermore, Zn-doped TiO2 modified by H2 O2 had relatively good reusability, exhibiting a potential practical application for tetracycline's photocatalytic degradation.

  14. AMPK alpha1 activation is required for stimulation of glucose uptake by twitch contraction, but not by H2O2, in mouse skeletal muscle

    Jensen, Thomas Elbenhardt; Schjerling, Peter; Viollet, Benoit


    BACKGROUND: AMPK is a promising pharmacological target in relation to metabolic disorders partly due to its non-insulin dependent glucose uptake promoting role in skeletal muscle. Of the 2 catalytic alpha-AMPK isoforms, alpha(2) AMPK is clearly required for stimulation of glucose transport......, in wildtype and alpha-AMPK transgenic mouse muscles, this study aimed to define conditions where alpha(1) AMPK is required to increase muscle glucose uptake. METHODOLOGY/PRINCIPAL FINDINGS: Following stimulation with H(2)O(2) (3 mM, 20 min) or twitch-contraction (0.1 ms pulse, 2 Hz, 2 min), signaling and 2...

  15. A History of Mild Traumatic Brain Injury affects Peripheral Pulse Oximetry during Normobaric Hypoxia

    Leonard Temme


    Full Text Available Introduction: Physiological and emotional stressors increase symptoms of concussion in recently injured individuals and both forms of stress induce symptoms in people recovering from mild traumatic brain injury (mTBI but who are asymptomatic when not stressed or are at rest. Methods: Healthy asymptomatic adults (25.0 ± 5.1 years with a history of mTBI (n = 36 and matched healthy controls (n = 36 with no mTBI history were exposed to three levels of normobaric hypoxic stress generated with the Reduced Oxygen Breathing Device (ROBD (Environics, Inc., Tollande, CT, which reduced the percent oxygen by mixing sea level air with nitrogen. The ROBD reduced the percent oxygen in the breathable air from the normal 21% to 15.5% O2, 14% O2, and 13% O2. Under these conditions: (a a standard pulse oximeter recorded peripheral oxygen saturation (SpO2 and pulse rate (beats per minute, and (b the FIT (PMI, Inc., Rockville, MD recorded saccadic velocity and pupillary response dynamics to a brief light flash. Results: For all three hypoxic stress conditions the mTBI group had significantly higher SpO2 during the final minute of exposure than did the controls F(2.17,151.8 = 5.29, p < .001, η2 = .852 and the rate of SpO2 change over time was significantly shallower for the mTBI than for the controls F(2.3,161.3 = 2.863, p < .001, η2 = .569, Greenhouse-Geisser corrected. Overall, mTBI had lower pulse rate but the difference was only significant for the 14% O2 condition. FIT oculomotor measures were not sensitive to group differences. When exposed to mild or moderate normobaric hypoxic stress (15% O2: (1 SpO2 differences emerged between the mTBI and matched healthy controls, (2 heart rate trended lower in the mTBI group, and (3 FIT measures were not sensitive to group differences. Conclusion: A relatively minor hypoxic challenge can reveal measurable differences in SpO2 and heart rate in otherwise asymptomatic individuals with a history of mTBI.

  16. Carbon-Pt nanoparticles modified TiO2 nanotubes for simultaneous detection of dopamine and uric acid.

    Mahshid, Sara; Luo, Shenglian; Yang, Lixia; Mahshid, Sahar Sadat; Askari, Masoud; Dolati, Abolghasem; Cai, Qingyun


    The present work describes sensing application of modified TiO2 nanotubes having carbon-Pt nanoparticles for simultaneous detection of dopamine and uric acid. The TiO2 nanotubes electrode was prepared using anodizing method, followed by electrodeposition of Pt nanoparticles onto the tubes. Carbon was deposited by decomposition of polyethylene glycol in a tube furnace to improve the conductivity. The C-Pt-TiO2 nanotubes modified electrode was characterized by cyclic voltammetry and differential pulse voltammetry methods. The modified electrode displayed high sensitivity towards the oxidation of dopamine and uric acid in a phosphate buffer solution (pH 7.00). The electro-oxidation currents of dopamine and uric acid were linearly related to the concentration over a wide range of 3.5 x 10(-8) M to 1 x 10(-5) M and 1 x 10(-7) M to 3 x 10(-5) M respectively. The limit of detection was determined as 2 x 10(-10) M for dopamine at signal-to-noise ratio of 3. The interference of uric acid was also investigated. Electro-oxidation currents of dopamine in the presence of fix amount of uric acid represented a linear behaviour towards successive addition of dopamine in range of 1 x 10(-7) M to 1 x 10(-5) M. Furthermore, in a solution containing dopamine, uric acid and ascorbic acid the overlapped oxidation peaks of dopamine and ascorbic acid could be easily separated by using C-Pt-TiO2 nanotubes modified electrode.

  17. Differential absorption lidar measurements of H2O and O2 using a coherent white light continuum

    Somekawa, T.; Manago, N.; Kuze, H.; Fujita, M.


    We applied a broadband and coherent white light continuum to differential absorption lidar (DIAL) detection of H2O and O2 profiles in the troposphere. The white light continuum can be generated by focusing high intensity femtosecond laser pulses at 800 nm into a Kr gas cell covering a broad spectral range from UV to mid-IR. Thus, the use of white light continuum potentially enables the DIAL measurement of several greenhouse and/or pollutant gases simultaneously while minimizing the lead time for developing a tunable light source. In order to demonstrate such capability, here we report the lidar measurements of H2O and O2. These molecular species exhibit absorption lines in the near IR region where relatively high intensity of the white light continuum is available. The white light continuum was transmitted through the atmosphere collinearly to the axis of a receiver telescope. Backscattered light was passed through bandpass filters (H2O On: 725 and 730 nm, H2O Off: 750 nm, O2 On: 760 nm, O2 Off: 780 nm), and was detected by a photomultiplier tube. The detection wavelengths were selected consecutively by rotating the filter wheels that contain five bandpass filters with an interval of 1 minute. In addition, we propose a method for retrieving vertical profiles of H2O by considering wavelength dependence of the aerosol extinction coefficient α and backscatter coefficient β. These results show that for achieving precise retrieval of H2O distribution, one needs to reduce the effect of aerosol temporal variations by means of long-time accumulation or simultaneous detection of the On- and Off-wavelength signals.

  18. TaN interface properties and electric field cycling effects on ferroelectric Si-doped HfO2 thin films

    Lomenzo, Patrick D.; Takmeel, Qanit; Zhou, Chuanzhen; Fancher, Chris M.; Lambers, Eric; Rudawski, Nicholas G.; Jones, Jacob L.; Moghaddam, Saeed; Nishida, Toshikazu


    Ferroelectric HfO2-based thin films, which can exhibit ferroelectric properties down to sub-10 nm thicknesses, are a promising candidate for emerging high density memory technologies. As the ferroelectric thickness continues to shrink, the electrode-ferroelectric interface properties play an increasingly important role. We investigate the TaN interface properties on 10 nm thick Si-doped HfO2 thin films fabricated in a TaN metal-ferroelectric-metal stack which exhibit highly asymmetric ferroelectric characteristics. To understand the asymmetric behavior of the ferroelectric characteristics of the Si-doped HfO2 thin films, the chemical interface properties of sputtered TaN bottom and top electrodes are probed with x-ray photoelectron spectroscopy. Ta-O bonds at the bottom electrode interface and a significant presence of Hf-N bonds at both electrode interfaces are identified. It is shown that the chemical heterogeneity of the bottom and top electrode interfaces gives rise to an internal electric field, which causes the as-grown ferroelectric domains to preferentially polarize to screen positively charged oxygen vacancies aggregated at the oxidized bottom electrode interface. Electric field cycling is shown to reduce the internal electric field with a concomitant increase in remanent polarization and decrease in relative permittivity. Through an analysis of pulsed transient switching currents, back-switching is observed in Si-doped HfO2 thin films with pinched hysteresis loops and is shown to be influenced by the internal electric field.

  19. The Propagation and Backscattering of Soliton-Like Pulses in a Chain of Quartz Beads and Related Problems. (II). Backscattering

    Manciu, M; Sen, S


    We demonstrate that the propagation of solitons, soliton-like excitations and acoustic pulses discussed in the preceding article can be used to detect buried impurities in a chain of elastic grains with Hertzkur contacts. We also present preliminary data for 3D granular beds, where soliton-like objects can form and can be used to probe for buried impurities, thus suggesting that soliton-pulse spectroscopy has the potential to become a valuable tool for probing the structural properties of granular assemblies. The effects of restitution are briefly discussed. We refer to available experiments which support our contention.

  20. Hydrogen production from methane steam reforming over Ni on high surface area CeO2 and CeO2-ZrO supports synthesized by surfactant-assisted method

    Sumittra Charojrochkul


    Full Text Available Methane steam reforming performances of Ni on high surface area (HSA CeO2 and CeO2-ZrO2 supports have been studied under solid oxide fuel cell (SOFC operating conditions. Their performances were compared to general Ni/CeO2, Ni/CeO2-ZrO2, and Ni/Al2O3. It was firstly observed that Ni/CeO2-ZrO2 (HSA with the Ce/Zr ratio of 3/1 showed the best performance in terms of activity and stability toward the methane steam reforming among those with the Ce/Zr ratios of 1/1, 1/3, and 3/1. Both Ni/CeO2-ZrO2 (HSA and Ni/CeO2 (HSA presented better resistance toward carbon formation than the general Ni/CeO2, Ni/CeO2- ZrO2, and Ni/Al2O3 at the same operating conditions. These benefits are related to the high oxygen storage capacity (OSC of CeO2-ZrO2. During the steam reforming process, in addition to the reactions on Ni surface (*, the redox reactions between the gaseous components presented in the system and the lattice oxygen (Ox on CeO2-ZrO2 surface also take place. Among these reactions, the redox reactions between the high carbon formation potential compounds (CH4, CHx-*n and CO and the lattice oxygen (Ox can prevent the formation of carbon species from the methane decomposition and Boudard reactions at the inlet H2O/CH4 ratio of 3.0/1.0.

  1. Effects of lower fluence pulsed dye laser irradiation on production of collagen and the mRNA expression of collagen relative gene in cultured fibroblasts in vitro

    YU Hai-yan; CHEN Da-fang; WANG Qi; CHENG Hao


    Background Lower fluence of 585-nm flashlamp-pumped pulsed dye laser has been successfully used as a nonablative technique in the treatment of wrinkles. The objective of this study was to evaluate the effect of the pulsed dye laser (585 nm) on the production of collagen and the mRNA expression of collagen related gene in fibroblasts in vitro.Methods Cultured fibroblasts were treated with a 585-nm flashlamp-pumped pulsed dye laser ( fluence 3 J/cm2,4 J/cm2, spot size 7 mm, pulse duration 450 μs). The production of collagen and the mRNA expression of transforming growth factor (TGF)-β1, SMAD2, SMAD3, SMAD4, SMAD7 and type I procollagen α1, α2 in fibroblasts were investigated by colorimetry or real time polymerase chain reaction.Results The production of collagen was significantly up-regulated after treatment with a 585-nm flashlamp-pumped pulsed dye laser with a fluence of 3 J/cm2 (P <0.001). The mRNA expression of TGF- β1,SMAD2, SMAD3, SMAD4, SMAD7 and procollagen I was significantly up-regulated after treatment with a 585-nm flashlamp-pumped pulsed dye laser with a fluence of 3 J/cm2 (P <0.001). No significant difference of mRNA expression of SMAD2, SMAD3, SMAD4, SMAD7 and type I procollagen was found between controls and fibroblasts treated with pulsed dye laser with a fluence of 4 J/cm2 (P >0.05).Conclusions Lower fluence (3 J/cm2) pulsed dye laser increased the collagen production in fibroblasts by up-regulating TGF-β1, SMAD2, SMAD3, SMAD4, SMAD7 and type I procollagen mRNA expression. These may be the reason it can be effectively used in the treatment of wrinkles.

  2. Template Reproduction of GRB Pulse Light Curves

    Hakkila, Jon E.; Preece, R. D.; Loredo, T. J.; Wolpert, R. L.; Broadbent, M. E.


    A study of well-isolated pulses in gamma ray burst light curves indicates that simple models having smooth and monotonic pulse rises and decays are inadequate. Departures from the Norris et al. (2005) pulse shape are in the form of a wave-like pre-peak residual that is mirrored and stretched following the peak. Pulse shape departures are present in GRB pulses of all durations, but placement of the departures relative to pulse peaks correlates with asymmetry. This establishes an additional link between temporal structure and spectral evolution, as pulse asymmetry is related to initial hardness while pulse duration indicates the rate of hard-to-soft pulse evolution.

  3. Improving the sampling technique of arterialized capillary samples to obtain more accurate PaO2 measurements.

    Wimpress, S; Vara, D D; Brightling, C E


    Arterialized earlobe capillary blood samples (ELCS) have been used as a measurement of blood gas status for over 20 years. There is general acceptance that there is a strong correlation and limits of agreement between arterial and arterialized blood samples with respect to pH and PaCO2. Although the correlation between the arterial and arterialized PaO2 is good, the limits of agreement poor. Our aim was to improve the accuracy of this technique in the measurement of PaO2 by simultaneously monitoring the oxygen saturation by pulse oximetry whilst taking an ELCS. We hypothesize that significant discrepancies between the SaO2 and SpO2 highlight either a poorly arterialized sample or an over aerated sample from air bubbles. We compared the SpO2 with the SaO2 of an arterial sample from 27 inpatients. We used the limits of agreement between these samples to define the degree of discordance we would accept between SaO2 and SpO2 before repeat ELCS. Subsequently, 252 consecutive patients attending our respiratory physiology unit over a six-month period had an ELCS and simultaneous SpO2. If there was a discrepancy between SaO2 and SpO2 of > 2% the ELCS was repeated. There was a good correlation and limits of agreement between the SpO2 and arterial SaO2 (r = 0.97, mean difference +/- 95% limits of agreement: 0.34 +/- 2.68). A difference of more than 2% between arterialized SaO2 and SpO2 was identified in 21 patients out of 252 (8.3%) with SaO2 higher in two and lower in 19 (r = 0.96, mean difference +/- 95% limits of agreement: 0.66 +/- 3.1). Repeat ELCS of these 21 samples reduced this discrepancy improving the concordance of the measurements (r = 0.98, mean difference +/- 95% limits of agreement: 0.47 +/- 1.0). In one case a difference of 3% remained between the saturations. We conclude that the addition of simultaneous pulse oximetry with ELCS will identify rogue measurements in about 8% of cases highlighting the need for repeat samples and thus increasing the accuracy of

  4. Catalytic efficiency of Pd/TiO_2-SnO_2 in reduction of nitrate and control of the reaction%Pd/TiO2-SnO2催化还原硝酸盐效能及反应调控

    郭燕妮; 胡勇有; 程建华


    采用共沉淀法制备了掺杂TiO2的复合载体TiO2-SnO2;浸渍法制备了单金属负载型催化剂Pd/TiO2-SnO2.用X射线衍射(XRD)、X射线光电子能谱(XPS)、比表面仪(BET)和透射电镜(TEM)表征表明Pd和TiO2在SnO2上成单层或亚单层分散,增加了反应活性位.催化剂分散性良好,比表面积为100.8m.2g-1,是平均粒径为9.1nm的纳米颗粒.常压下考察了甲酸-Pd/TiO2-SnO2-硝酸盐催化还原反应体系的主要影响因素.结果表明,Pd/TiO2-SnO2催化活性与负载比、甲酸量正相关%The monometallic catalyst Pd/TiO2-SnO2 was prepared by impregnating Pd on the surface of a composite support of TiO2-SnO2,which was prepared by coprecipitation.The prepared sample was characterized by X-ray diffraction(XRD),specific surface area analysis(BET) and transmission electron microscopy(TEM) as nano-sized particles with average size of 9.1 nm and specific surface area of 100.08 m2·g-1.The Pd and TiO2 were dispersed on the surface of the SnO2 support in one monolayer,resulting in an increase of catalytic active sites.The catalytic performance of the Pd /TiO2-SnO2 catalyst for reduction of nitrate was investigated under normal atmosphere,with formic acid used as reducing agent.The results showed that the catalytic activity of the Pd/TiO2-SnO2 was positively related to load ratio and initial formic acid concentration but fluctuated with the temperature over the range of 15~45℃.With the temperature increasing,the catalytic activity initially increased then decreased.Increasing the amount of catalyst accelerated the reaction rate.The selectivity of Pd/TiO2-SnO2 was positively related to catalyst amount,but negatively related to load ratio,initial formic acid concentration and temperature.Strategies for control of the catalytic reduction of nitrate based on the formic acid-Pd/TiO2-SnO2 system are as follows:① To maintain high catalytic selectivity,the catalyst amount should be more than 0

  5. H(2)O(2)-sensitized TiO(2)/SiO(2) composites with high photocatalytic activity under visible irradiation.

    Zou, Jian; Gao, Jiacheng


    TiO(2)/SiO(2) composite photocatalysts were prepared by depositing of TiO(2) onto nano-SiO(2) particles. X-ray diffraction (XRD), transmission electron micrograph (TEM), Raman spectrometer, UV-Vis diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy (FT-IR) were employed to characterize the properties of the synthesized TiO(2)/SiO(2) composites. These results indicated that the products without calcination were amorphous, and calcination could enhance the crystallinity of TiO(2). Increases in the amount of TiO(2) would decrease the dispersion in the composites. H(2)O(2)-sensitized TiO(2)/SiO(2) composite photocatalysts could absorb visible light at wavelength below 550 nm. The photocatalytic activity of as-prepared catalysts was characterized by methyl-orange degradation. The results showed the uncalcined composite photocatalysts with amorphous TiO(2) exhibited higher photocatalytic activity under visible light, and the activity of catalysts with TiO(2) content over 30% decreased with increasing of TiO(2) content. Increases in the calcination temperature and TiO(2) content promote the formation of bulk TiO(2) and result in a decrease in activity.

  6. Core-Shell MnO2-SiO2 Nanorods for Catalyzing the Removal of Dyes from Water

    Wei Gong


    Full Text Available This work presented a novel core-shell MnO2@m-SiO2 for catalyzing the removal of dyes from wastewater. MnO2 nanorods were sequentially coated with polydopamine (PDA and polyethyleneimine (PEI forming MnO2@PDA-PEI. By taking advantage of the positively charged amine groups, MnO2@PDA-PEI was further silicificated, forming MnO2@PDA-PEI-SiO2. After calcination, the composite MnO2@m-SiO2 was finally obtained. MnO2 nanorod is the core and mesoporous SiO2 (m-SiO2 is the shell. MnO2@m-SiO2 has been used to degrade a model dye Rhodamine B (RhB. The shell m-SiO2 functioned to adsorb/enrich and transfer RhB, and the core MnO2 nanorods oxidized RhB. Thus, MnO2@m-SiO2 combines multiple functions together. Experimental results demonstrated that MnO2@m-SiO2 exhibited a much higher efficiency for degradation of RhB than MnO2. The RhB decoloration and degradation efficiencies were 98.7% and 84.9%, respectively. Consecutive use of MnO2@m-SiO2 has demonstrated that MnO2@m-SiO2 can be used to catalyze multiple cycles of RhB degradation. After six cycles of reuse of MnO2@m-SiO2, the RhB decoloration and degradation efficiencies were 98.2% and 71.1%, respectively.

  7. Nanocompósitos semicondutores ZnO/TiO2: testes fotocatalíticos ZnO/TiO2 semiconductor nanocomposites: photocatalytic tests

    Shirley Santana Silva


    Full Text Available Titanium dioxide is an efficient photocatalist, being possible to improve its efficiency with better charge separation which occurs when it is coupled with other semiconductors. Nanometric particles of ZnO were used to impregnate TiO2 P25 in order to optimize its photocatalytic properties. ZnO/TiO2 composites were obtained at different proportions and were characterized by X-ray diffraction (XRD, micro-Raman and diffuse reflectance spectroscopies, measurement of surface area (BET and scanning electron microscopy (SEM. Raman spectroscopy data revealed a change on the TiO2 surface due the presence of ZnO which was observed by an enlargement of TiO2 peaks and a change on the relation rate between anatase and rutile phases of the composites. The photodegradation of azo-dye Drimaren red revealed better efficiency for ZnO/TiO2 3% nanocomposite and for ZnO pure.

  8. Instability of Hydrogenated TiO2

    Nandasiri, Manjula I.; Shutthanandan, V.; Manandhar, Sandeep; Schwarz, Ashleigh M.; Oxenford, Lucas S.; Kennedy, John V.; Thevuthasan, Suntharampillai; Henderson, Michael A.


    Hydrogenated TiO2 (H-TiO2) is toted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). Protons (40 keV) implanted at a ~2 atom % level within a ~120 nm wide profile of rutile TiO2(110) were situated ~300 nm below the surface. NRA revealed that this H-profile broadened preferentially toward the surface after annealing at 373 K, dissipated out of the crystal into vacuum at 473 K, and was absent within the beam sampling depth (~800 nm) at 523 K. Photoemission showed that the surface was reduced in concert with these changes. Similar anneals had no effect on pristine TiO2(110). The facile bulk diffusivity of H in rutile, as well as its activity toward interfacial reduction, significantly limits the utilization of H-TiO2 as a photocatalyst. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. The research was performed using the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  9. Evaluation of the Nano-TiO2 as a Novel Deswelling Material.

    Chu, Ming; Hou, Yue-Long; Xu, Lan; Chu, Zheng-Yun; Zhang, Ming-Bo; Wang, Yue-Dan


    Nano-TiO2 is widely applied in the automobile exhaust hose reels as a catalyst to reduce oxynitride emissions, including nitric oxide (NO). In the biomedicine field, NO plays an important role in vasodilation and edema formation in human bodies. However, the deswelling activity of nano-TiO2 has not been reported. Here, we demonstrated that nano-TiO2 can significantly degrade the production of NO in LPS-induced RAW264.7 mouse macrophages. Further study indicated that nano-TiO2 exhibited an effect on vascular permeability inhibition, and prevented carrageenan-induced footpad edema. Therefore, we prepared a nano-TiO2 ointment and observed similar deswelling effects. In conclusion, nano-TiO2 might act as a novel deswelling agent related with its degradation of NO, which will aid in our ability to design effective interventions for edema involved diseases.

  10. Reduced graphene oxide decorated with Fe doped SnO2 nanoparticles for humidity sensor

    Toloman, D.; Popa, A.; Stan, M.; Socaci, C.; Biris, A. R.; Katona, G.; Tudorache, F.; Petrila, I.; Iacomi, F.


    Reduced graphene oxide (rGO) decorated with Fe doped SnO2 nanoparticles were fabricated via the electrostatic interaction between positively charged modified Fe-doped SnO2 oxide and negatively charged graphene oxide (GO) in the presence of poly(allylamine) hydrochloride (PAH). The decoration of rGO layers with SnO2:Fe nanoparticles was highlited by TEM microsopy. For composite sample the diffraction patterns coincide well with those of SnO2:Fe nanoparticles. The reduction of graphene oxide was evidenced using XRD and FT-IR spectroscopy. The formation of SnO2:Fe-PAH-graphene composites was confirmed by FT-IR, Raman and EPR spectroscopy. Sensitivity tests for relative humidity (RH) measurements were carried out at five different concentrations of humid air at room temperature. The prepared composite sensor exhibited a higher sensing response as compared with Fe:SnO2 nanoparticles.

  11. Humidity effect on electrochemical performance of Li-O2 batteries

    Guo, Ziyang; Dong, Xiaoli; Yuan, Shouyi; Wang, Yonggang; Xia, Yongyao


    In this work, we compare the performance of Li-O2 batteries in pure/dry O2, pure O2 with a relative humidity (RH) of 15% and ambient air with an RH of 50%, and analyze the ambient humidity effect on the reactions in the carbon-based catalytic electrode. Electrochemical investigation indicates that discharge capacities of Li-O2 batteries increased with growth of RH value, but cyclic ability and rate performance are influenced in an opposite way. Ex-situ X-ray diffraction (XRD), Fourier transform-infrared spectrophotometer (FT-IR) and scanning electron microscope (SEM) investigations suggest that ambient humidity affects not only the Li2O2/O2 conversion, LiCO3/CO2 conversion and LiOH formation but also the morphology of discharge products in porous catalytic electrode over charge/discharge cycle. These results may be important for developing Li-air battery.

  12. Electrical and optical studies in polyaniline nanofibre–SnO2 nanocomposites

    Smritimala Sarmah; A Kumar


    Polyaniline nanofibre–tin oxide (PAni-SnO2) nanocomposites are synthesized and mixed with polyvinyl alcohol (PVA) as stabilizer to cast free-standing films. Composite films are characterized by X-ray diffraction studies (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence spectroscopy (PL) and UV-visible spectroscopy. XRD confirms the formation of PAni nanofibre–SnO2 nanocomposite. From TEM images, diameter of the polyaniline nanofibre and SnO2 nanoparticles in the PAni-SnO2 nanocomposite are found to be 20–60 nm. SEM results show fibrous morphology of the PAni nanofibre and spherical morphology of polyaniline-SnO2 composites. The nanocomposites exhibit high relative photoluminescence intensity in violet as well as green–yellow region of visible spectrum. From electrical conductivity measurement, it is confirmed that PAni nanofibre–SnO2 nanocomposite follows Mott’s one-dimensional variable range hopping (VRH) model.

  13. A comparison study on Raman scattering properties of alpha- and beta-MnO2

    Gao, Tao; Fjellväg, Helmer; Norby, Poul


    In this comment to a recent paper [Anal. Chim. Acta 585 (2007) 241–245], we report a comparison study on Mn oxide-related compounds with different crystallographic forms, which distinguish between β-MnO2 and α-MnO2 type materials via Raman scattering (RS) spectroscopy. The tetragonal rutile-type β-Mn......O2 is characterized by a RS band at 667 cm−1 of symmetry A1g, whereas the α-MnO2 type materials feature two main RS contributions at about 574 and 634 cm−1, belonging to Ag spectroscopic species of a tetragonal hollandite-type framework. These data represent a clear signature for identifying β-MnO2...... and α-MnO2 type materials via RS spectroscopy....

  14. Evaluation of the Nano-TiO2 as a Novel Deswelling Material

    Ming Chu


    Full Text Available Nano-TiO2 is widely applied in the automobile exhaust hose reels as a catalyst to reduce oxynitride emissions, including nitric oxide (NO. In the biomedicine field, NO plays an important role in vasodilation and edema formation in human bodies. However, the deswelling activity of nano-TiO2 has not been reported. Here, we demonstrated that nano-TiO2 can significantly degrade the production of NO in LPS-induced RAW264.7 mouse macrophages. Further study indicated that nano-TiO2 exhibited an effect on vascular permeability inhibition, and prevented carrageenan-induced footpad edema. Therefore, we prepared a nano-TiO2 ointment and observed similar deswelling effects. In conclusion, nano-TiO2 might act as a novel deswelling agent related with its degradation of NO, which will aid in our ability to design effective interventions for edema involved diseases.

  15. Ozone Treatment Improved the Resistive Switching Uniformity of HfAlO2 Based RRAM Devices

    Lifeng Liu


    Full Text Available HfAlO2 based resistive random access memory (RRAM devices were fabricated using atomic layer deposition by modulating deposition cycles for HfO2 and Al2O3. Effect of ozone treatment on the resistive switching uniformity of HfAlO2 based RRAM devices was investigated. Compared to the as-fabricated devices, the resistive switching uniformity of HfAlO2 based RRAM devices with the ozone treatment is significantly improved. The uniformity improvement of HfAlO2 based RRAM devices is related to changes in compositional and structural properties of the HfAlO2 resistive switching film with the ozone treatment.

  16. Accumulation effect of SiO2 protective layer on multi-shot laser-induced damage in high-reflectivity HfO2 /SiO2 coatings

    Ying Wang; Hongbo He; Yuan'an Zhao; Yongguang Shan; Chaoyang Wei


    The accumulation effects in high-reflectivity (HR) HfO2/SiO2 coatings under laser irradiation are investigated. The HR HfO2/SiO2 coatings are prepared by electron beam evaporation at 1064 nm. The laser-induced damage threshold (LIDT) are measured at 1064 nm and at a pulse duration of 12 ns, in 1-on-l and S-on-1 modes. Multi-shot LIDT is lower than single-shot LIDT. The laser-induced and native defects play an important role in the multi-shot mode. A correlative theory model based on critical conduction band electron density is constructed to elucidate the experimental phenomena.%The accumulation effects in high-reflectivity (HR) HfO2/SiO2 coatings under laser irradiation are investigated.The HR HfO2/SiO2 coatings are prepared by electron beam evaporation at 1 064 nm.The laser-induced damage threshold (LIDT) are measured at 1 064 nm and at a pulse duration of 12 ns,in 1-on-1 and S-on-1 modes.Multi-shot LIDT is lower than single-shot LIDT.The laser-induced and native defects play an important role in the multi-shot mode.A correlative theory model based on critical conduction band electron density is constructed to elucidate the experimental phenomena.In recent years,many laboratories have investigated multi-shot laser-induced damage in optical materials,such as fused silica[1] and KTP crystals[2].The multishot laser-induced damage threshold (LIDT) is often lower than single-shot LIDT because of the accumulation effects in most optical materials[1,3-5].As a result,investigations on multi-shot laser-induced damage in optical coatings are of high practical importance for high-power laser applications[5,6].The mechanism for single-shot laser damage includes avalanche ionization (AI)[7],multiphoton ionization (MPI) [8],impurity breakdown[9],etc.

  17. The effect of pulse stimulation on biota - Research in relation to ICES advice - progress report with preliminary results

    Marlen, van B.; Vis, van de J.W.; Haan, de D.; Burggraaf, D.; Heul, van der J.W.; Terlouw, A.


    In response to questions asked by ICES on the effects of pulse stimulation in commercial beam trawling on components of the marine ecosystem a number of preliminary studies were undertaken in the period between 31 May and 5 October 2007. These activities involved: 1. Measurements on the detailed sti

  18. The Pulsed-Field Multiport Antenna System Reciprocity Relation and Its Applications: A Time-Domain Approach

    De Hoop, A.T.; Lager, I.E.; Tomassetti, V.


    A novel time-domain approach to the derivation of the pulsed electromagnetic field multiport antenna system reciprocity theorem is presented. The theorem interrelates the field and system properties in two states: the transmitting state and the receiving state. General time-domain Thevenin (voltage-

  19. TiO2 controlling photoluminescence of AWO4 (A =Ca,Sr,Ba) nanofilms

    Jia, Runping; Zhang, Guoxin; Wu, Qingsheng; Ding, Yaping


    AWO4 (A =Ca,Sr,Ba) nanofilms are prepared by a self-inventive technique using collodion to disperse nanoparticles and form film, and their photoluminescence (PL) properties are controlled by a nano-TiO2 doping method. This cannot only reach the results of uniform film and PL enhancement, but also realize a PL increase/decrease shift effect. The PL behaviors of AWO4 nanofilms doped by TiO2 are in good agreement with Gaussion function relation. In addition, there is a positive correlation between the critical concentrations of TiO2 in AWO4-TiO2 nanofilm series and A's ionic potential.

  20. Electrical transport properties of graphene on SiO2 with specific surface structures

    Nagashio, K.; Yamashita, T; Nishimura, T.; K. Kita; Toriumi, A.


    The mobility of graphene transferred on a SiO2/Si substrate is limited to ~10,000 cm2/Vs. Without understanding the graphene/SiO2 interaction, it is difficult to improve the electrical transport properties. Although surface structures on SiO2 such as silanol and siloxane groups are recognized, the relation between the surface treatment of SiO2 and graphene characteristics has not yet been elucidated. This paper discusses the electrical transport properties of graphene on specific surface stru...

  1. Ciprofloxacin@SiO2: Fluorescent nanobubbles

    M J Rosemary; V Suryanarayanan; P Ganapati Reddy; Ian Maclaren; S Baskaran; T Pradeep


    We report a new nanomaterial in which ciprofloxacin molecules are incorporated inside silica nanobubbles, denoted as ciprofloxacin@SiO2. The material has been characterised using UV/Vis absorption spectroscopy, transmission electron microscopy, cyclic voltammetry, and emission spectroscopy. The material is stable and the freestanding particles can be precipitated and redispersed in several solvents. Confinement of the molecule is complete as leaching through the shell is minimal. The material behaves like free ciprofloxacin in solution; however, effects of confinement are manifested. Energy transfer reaction between ciprofloxacin@SiO2 and Tb3+ was monitored by emission spectroscopy. The emission intensity decreased with metal ion exposure indicating selective electronic interaction.

  2. Returning on empty: extreme blood O2 depletion underlies dive capacity of emperor penguins.

    Ponganis, P J; Stockard, T K; Meir, J U; Williams, C L; Ponganis, K V; van Dam, R P; Howard, R


    Blood gas analyses from emperor penguins (Aptenodytes forsteri) at rest, and intravascular P(O(2)) profiles from free-diving birds were obtained in order to examine hypoxemic tolerance and utilization of the blood O(2) store during dives. Analysis of blood samples from penguins at rest revealed arterial P(O(2))s and O(2) contents of 68+/-7 mmHg (1 mmHg= 133.3 Pa) and 22.5+/-1.3 ml O(2) dl(-1) (N=3) and venous values of 41+/-10 mmHg and 17.4+/-2.9 ml O(2) dl(-1) (N=9). Corresponding arterial and venous Hb saturations for a hemoglobin (Hb) concentration of 18 g dl(-1) were >91% and 70%, respectively. Analysis of P(O(2)) profiles obtained from birds equipped with intravascular P(O(2)) electrodes and backpack recorders during dives revealed that (1) the decline of the final blood P(O(2)) of a dive in relation to dive duration was variable, (2) final venous P(O(2)) values spanned a 40-mmHg range at the previously measured aerobic dive limit (ADL; dive duration associated with onset of post-dive blood lactate accumulation), (3) final arterial, venous and previously measured air sac P(O(2)) values were indistinguishable in longer dives, and (4) final venous P(O(2)) values of longer dives were as low as 1-6 mmHg during dives. Although blood O(2) is not depleted at the ADL, nearly complete depletion of the blood O(2) store occurs in longer dives. This extreme hypoxemic tolerance, which would be catastrophic in many birds and mammals, necessitates biochemical and molecular adaptations, including a shift in the O(2)-Hb dissociation curve of the emperor penguin in comparison to those of most birds. A relatively higher-affinity Hb is consistent with blood P(O(2)) values and O(2) contents of penguins at rest.

  3. Dissolution and diffusion of TiO2 in the CaO-Al2O3-SiO2 slag

    Zhong-shan Ren; Xiao-jun Hu; Xin-mei Hou; Xiang-xin Xue; Kuo-chih Chou


    The dissolution of TiO2 in the CaO-Al2O3-SiO2 slag under static conditions was studied in the temperature range from 1643 K to 1703 K. After TiO2 dissolved, the microstructure of the interface between TiO2 and the slag was observed by scanning electron microscopy, and the concentration profiles of Ti4+and other ions across the TiO2/slag interfaces were analyzed by energy-dispersive X-ray spectroscopy. On the basis of these results, the dissolution behavior of TiO2 was evaluated, and the diffusivity of Ti4+in the bulk slag was estimated. Ac-cording to the Stokes-Einstein relation, the viscosity calculated by a previously reported model gave a diffusivity of Ti4+ions greater than that estimated by the concentration profiles of Ti4+ions. The mechanism of TiO2 dissolution in the CaO-Al2O3-SiO2 slag is discussed in de-tail.

  4. Visible light catalysis of rhodamine B using nanostructured Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) thin films.

    Mahadik, M A; Shinde, S S; Mohite, V S; Kumbhar, S S; Moholkar, A V; Rajpure, K Y; Ganesan, V; Nayak, J; Barman, S R; Bhosale, C H


    The Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) composite films are deposited using spray pyrolysis method onto glass and FTO coated substrates. The structural, morphological, optical and photocatalytic properties of Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) thin films are studied. XRD analysis confirms that films are polycrystalline with rhombohedral and tetragonal crystal structures for Fe2O3 and TiO(2) respectively. The photocatalytic activity was tested for the degradation of Rhrodamine B (Rh B) in aqueous medium. The rate constant (-k) was evaluated as a function of the initial concentration of species. Substantial reduction in concentrations of organic species was observed from COD and TOC analysis. Photocatalytic degradation effect is relatively higher in case of the TiO(2)/Fe(2)O(3) than TiO(2) and Fe(2)O(3) thin film photoelectrodes in the degradation of Rh B and 98% removal efficiency of Rh B is obtained after 20min. The photocatalytic experimental results indicate that TiO(2)/α-Fe(2)O(3) photoelectrode is promising material for removing of water pollutants.

  5. Hyperfine Field in Fe Doped SnO2 Investigated by ab intio Calculation

    ZHANG; Qiao-li; YUAN; Da-qing; FAN; Ping; ZUO; Yi; ZHENG; Yong-nan; ZHANG; Huan-qiao; ZHU; Sheng-yun


    <正>Transition-metal doped SnO2 is one of the promising candidates for high temperature ferromagnetic diluted magnetic semiconductors (DMS) with potential applications in spintronics. Coey, et al. and Fitzgerald, et al. have investigated the Sn1 xFexO2 thin films grown by pulsed-laser deposition with x=0.05 by M ssbauer spectroscopy. For a deep understanding of the ferromagnetic mechanism, it is necessary to know the microscopic electronic structure of this kind of novel materials.

  6. Attempts to improve the H2S sensitivity of TiO2 films

    Jagadale, T. C.; Nagmani, Ramgir, N. S.; Prajapat, C. L.; Debnath, A. K.; Aswal, D. K.; Gupta, S. K.


    We report the pulsed laser deposited titanium oxide thin film for H2S gas sensing. The surface and bulk electronic structure is revealed using XPS technique. These TiO2 films showed very good selectivity to H2S with response of around ~ 60% at 200°C operating temperature. In order to improve the sensor response so as to realize the technological application, we hereby attempted bi-directional efforts as (i) Nb-doping and (ii) defects engineering in the TiO2 film. It is revealed that Nb-doping reduces response however defect engineering improves the same.

  7. O-2 Substituted pyranosyl oxacarbenium ions are C-2-O-2 2-fold rotors with a strong syn preference.

    Ionescu, Andrei R; Whitfield, Dennis M; Zgierski, Marek Z


    The substituent at O-2 of glycopyranosides is known to have a pronounced effect on both the formation and the cleavage of glycosides at C-1. This is primarily attributed to stereoelectronic effects on the formation and stability of the related glycopyranosyl oxacarbenium ions. Previous QM studies of 2-O-methyl substituted manno and gluco configured pyranosyl oxacarbenium ions found a preference for the methyl carbon to be syn to the CH-2 methine. This study examines the conformational preference of variously substituted O-2 tetrahydropyranosyl oxacarbenium ions and confirms this syn preference. Neutral analogues are shown to have the expected 3-fold rotation whereas the charged species exhibit 2-fold rotation about C-2-O-2. Natural bond order (NBO) calculations suggest that the dominant stabilizing interaction is a unimodal O-2 lone pair to C-1-O-5 pi-bond hyperconjugative interaction. This syn conformational preference has important implications for mimics of glycopyranosyl oxacarbenium ion transition states. It also suggests a conformational based mechanism that can be exploited to tune the reactivity of glycopyranosyl donors in the glycosylation reaction.

  8. Modeling of methanol decomposition on Pt/CeO2/ZrO2 catalyst in a packed bed microreactor

    Pohar, Andrej; Belavič, Darko; Dolanc, Gregor; Hočevar, Stanko


    Methanol decomposition on Pt/CeO2/ZrO2 catalyst is studied inside a packed bed microreactor in the temperature range of 300-380 °C. The microreactor is fabricated using low-temperature co-fired ceramic (LTCC) technology, which is well suited for the production of relatively complex three-dimensional structures. It is packed with 2 wt% Pt-CeO2 catalyst, which is deposited onto ZrO2 spherical particles. A 1D mathematical model, which incorporates diffusion, convection and mass transfer through the boundary layer to the catalyst particles, as well as a 3D computational fluid dynamics model, are developed to describe the methanol decomposition process inside the packed bed. The microreactor exhibits reliable operation and no catalyst deactivation was observed during three months of experimentation. A comparison between the 1D mathematical model and the 3D model, considering the full 3D geometry of the microreactor is made and the differences between the models are identified and evaluated.

  9. Optical properties of bismuth-doped SiO2- or GeO2-based glass core optical fibers

    Firstova, Elena G


    A detailed study of optical properties of bismuth-doped fibers based on SiO2 and GeO2 glasses containing no other dopants has been carried out. To provide important information about spectroscopic properties of IR bismuth-related active centers (BAC) the excitation-emission fluorescence spectra for a spectral region of 220-2000 nm have been measured. The obtained three-dimensional spectra have been presented for different host glass compositions: silicate, germanate, aluminosilicate and phosphosilicate. Energy-level configuration and main radiative transitions associated with BACs in GeO2 and SiO2 glasses have been revealed. Fluorescence lifetime analysis of the basic radiative transitions of BAC have been carried out. It has been shown that the energy-level schemes of BAC-Si and BAC-Ge (BAC associated with silicon and germanium, respectively) are similar, corresponding BAC-Ge energy levels lying 10-16% lower than those of BAC-Si. It has been determined that BAC-Si, BAC-Ge and BAC-Si, BAC-P can exist simultan...

  10. Effects of Partially Ionised Medical Oxygen, Especially with O2•−, in Vibration White Finger Patients

    Slavomír Perečinský


    Full Text Available A major symptom of hand-arm vibration syndrome is a secondary Raynaud’s phenomenon—vibration white finger (VWF—which results from a vasospasm of the digital arteries caused by work with vibration devices leading to occupational disease. Pharmacotherapy of VWF is often ineffective or has adverse effects. The aim of this work was to verify the influence of inhalation of partially ionized oxygen (O2•− on peripheral blood vessels in the hands of patients with VWF. Ninety one (91patients with VWF underwent four-finger adsorption plethysmography, and the pulse wave amplitude was recorded expressed in numeric parameters—called the native record. Next, a cold water test was conducted following with second plethysmography. The patients were divided in to the three groups. First and second inhaled 20-min of ionized oxygen O2•− or oxygen O2 respectively. Thirth group was control without treatment. All three groups a follow-up third plethysmography—the post-therapy record. Changes in the pulse wave amplitudes were evaluated. Inpatients group inhaling O2•− a modest increase of pulse wave amplitude was observed compared to the native record; patients inhaling medical oxygen O2 and the control showed a undesirable decline of pulse wave amplitude in VWF fingers. Strong vasodilatation were more frequent in the group inhaling O2•− compare to O2 (p < 0.05. Peripheral vasodilatation achieved by inhalation of O2•− could be used for VWF treatment without undesirable side effect in hospital as well as at home environment.

  11. Double-Shelled TiO2 Hollow Spheres Assembled with TiO2 Nanosheets.

    Zhang, Chao; Zhou, Yuming; Zhang, Yiwei; Zhao, Shuo; Fang, Jiasheng; Sheng, Xiaoli; Zhang, Tao; Zhang, Hongxing


    High-quality double-shelled TiO2 hollow spheres (DHS-Ti) assembled with TiO2 nanosheets have been synthesized for the first time through a simple hydrothermal treatment of sSiO2 @TiO2 (TiO2 -coated solid SiO2 spheres). The double-shelled structure shows a high BET surface area up to 417.6 m(2)  g(-1) . Anatase DHS-Ti of high crystallinity can be obtained without structural collapse by calcination treatment. The effects of cetyl trimethylammonium bromide (CTAB) concentration, pH, and hydrothermal reaction temperature have also been investigated with a series of contrast experiments. A formation mechanism involving the in situ growth of amorphous TiO2 nanosheets followed by the redeposition of dissolved silica species is proposed. Lastly, the DHS-Ti forming strategy can be extended as a general strategy to fabricate various morphological hollow nanostructures and double-shelled Pt nanocatalysts by rationally selecting functional sSiO2 nanoparticles as core materials. This work could open up a new strategy for controllable synthesis of complex hollow structures and other functional materials.

  12. Enhanced Photocatalytic Activity of ZrO2-SiO2 Nanoparticles by Platinum Doping

    Mohammad W. Kadi


    Full Text Available ZrO2-SiO2 mixed oxides were prepared via the sol-gel method. Photo-assisted deposition was utilized for doping the prepared mixed oxide with 0.1, 0.2, 0.3, and 0.4 wt% of Pt. XRD spectra showed that doping did not result in the incorporation of Pt within the crystal structure of the material. UV-reflectance spectrometry showed that the band gap of ZrO2-SiO2 decreased from 3.04 eV to 2.48 eV with 0.4 wt% Pt doping. The results show a specific surface area increase of 20%. Enhanced photocatalysis of Pt/ZrO2-SiO2 was successfully tested on photo degradation of cyanide under illumination of visible light. 100% conversion was achieved within 20 min with 0.3 wt% of Pt doped ZrO2-SiO2.

  13. Activity and Selectivity for O-2 Reduction to H2O2 on Transition Metal Surfaces

    Siahrostami, Samira; Verdaguer Casadevall, Arnau; Karamad, Mohammadreza;


    Industrially viable electrochemical production of H2O2 requires active, selective and stable electrocatalyst materials to catalyse the oxygen reduction reaction to H2O2. On the basis of density functional theory calculations, we explain why single site catalysts such as Pd/Au show improved select...

  14. Synthesis, Characterization and Properties of CeO2-doped TiO2 Composite Nanocrystals

    Oman ZUAS


    Full Text Available Pure TiO2 and CeO2-doped TiO2 (3 % CeO2-97 %TiO2 composite nanocrystals were synthesized via co-precipitation method and characterized using TGA, XRD, FTIR, DR-UV-vis and TEM. The XRD data revealed that the phase structure of the synthesized samples was mainly in pure anatase having crystallite size in the range of 7 nm – 11 nm. Spherical shapes with moderate aggregation of the crystal particles were observed under the TEM observation. The presence of the CeO2 at TiO2 site has not only affected morphologically but also induced the electronic property of the TiO2 by lowering the band gap energy from 3.29 eV (Eg-Ti to 3.15 eV (Eg-CeTi. Performance evaluation of the synthesized samples showed that both samples have a strong adsorption capacity toward Congo red (CR dye in aqueous solution at room temperature experiment, where  the capacity of the CeTi was higher than the Ti sample. Based on DR-UV data, the synthesized samples obtained in this study may also become promising catalysts for photo-assisted removal of synthetic dye in aqueous solution. DOI:

  15. Synthesis and Characterization of Novel PVA/SiO2-TiO2 Hybrid Fibers

    Haihong Ma


    Full Text Available Hybrid sols of poly (vinyl alcohol (PVA/Silicon oxide-titanium oxide (SiO2-TiO2 were prepared with tetraethoxylsilane and tetrabutyl titanate as precursor using Sol-Gel method. PVA/SiO2-TiO2 hybrid fibers were prepared by drawing from the hybrid sols using dip-coating method and aging treatment. The spinnability of hybrid sols was investigated. Spinnable time (t and spinnable length (l of hybrid sols increased with either the PVA content or the molar ratio of SiO2 and TiO2. The hybrid fibers were characterized by Fourier transform infrared (FT-IR, Scanning electron microscopy (SEM, X-ray diffraction (XRD, Ultraviolet Visible Spectrometry (UV-Vis and (Thermo-gravimetric Analysis TGA. FT-IR results suggested that PVA was linked with (SiO2-TiO2 network by chemical bonds. SEM measurements indicated that when the fibers arrives the maximum spinning length, the diameter of the fibers was about 50 μm, and the whole system was homogeneous. XRD results revealed that the crystallinity of hybrid fibers was decreased distinctly. UV-Vis measurements confirmed that the shielding properties to Ultraviolet (UV were greatly improved with titania filled in the hybrid fibers. TG measurements suggested that the hybrid fibers show better resistance to heat than pure PVA fibers.

  16. O2(a1Δ) Quenching In The O/O2/O3 System

    Azyazov, V. N.; Mikheyev, P. A.; Postell, D.; Heaven, M. C.


    The development of discharge singlet oxygen generators (DSOG's) that can operate at high pressures is required for the power scaling of the discharge oxygen iodine laser. In order to achieve efficient high-pressure DSOG operation it is important to understand the mechanisms by which singlet oxygen (O2(a1Δ)) is quenched in these devices. It has been proposed that three-body deactivation processes of the type O2(a1Δ)+O+M→2O2+M provide significant energy loss channels. To further explore these reactions the physical and reactive quenching of O2(a1Δ) in O(3P)/O2/O3/CO2/He/Ar mixtures has been investigated. Oxygen atoms and singlet oxygen molecules were produced by the 248 nm laser photolysis of ozone. The kinetics of O2(a1Δ) quenching were followed by observing the 1268 nm fluorescence of the O2a1Δ-X3∑ transition. Fast quenching of O2(a1Δ) in the presence of oxygen atoms and molecules was observed. The mechanism of the process has been examined using kinetic models, which indicate that quenching by vibrationally excited ozone is the dominant reaction.

  17. Catalytic combustion of trichloroethylene over TiO2-SiO2 supported catalysts

    Kulazynski, M.; Ommen, van J.G.; Trawczynski, J.; Walendziewski, J.


    Combustion of trichloroethylene (TCE) on Cr2O3, V2O5, Pt or Pd catalysts supported on TiO2-SiO2 as a carrier has been investigated. It was found that oxide catalysts are very active but their activity quickly diminishes due to loss of the active component, especially at higher reaction temperatures

  18. On the rutile alpha-PbO"2-type phase boundary of TiO"2

    Olsen, J.S.; Gerward, Leif; Jiang, Jianzhong


    The high-pressure, high-temperature phase quilibria of TiO"2 have been studied with special emphasis on the rutile and alpha-PbO"2-type phases. It is found that the phase boundary, when plotted in a pressure-temperature diagram, changes from having a negative to having a positive slope...

  19. TiO2/Cu2O composite based on TiO2 NTPC photoanode for photoelectrochemical (PEC) water splitting under visible light

    Shi, Le


    Water splitting through photoelectrochemical reaction is widely regarded as a major method to generate H2 , a promising source of renewable energy to deal with the energy crisis faced up to human being. Efficient exploitation of visible light in practice of water splitting with pure TiO2 material, one of the most popular semiconductor material used for photoelectrochemical water splitting, is still challenging. One dimensional TiO2 nanotubes is highly desired with its less recombination with the short distance for charge carrier diffusion and light-scattering properties. This work is based on TiO2 NTPC electrode by the optimized two-step anodization method from our group. A highly crystalized p-type Cu2O layer was deposited by optimized pulse potentiostatic electrochemical deposition onto TiO2 nanotubes to enhance the visible light absorption of a pure p-type TiO2 substrate and to build a p-n junction at the interface to improve the PEC performance. However, because of the real photocurrent of Cu2O is far away from its theoretical limit and also poor stability in the aqueous environment, a design of rGO medium layer was added between TiO2 nanotube and Cu2O layer to enhance the photogenerated electrons and holes separation, extend charge carrier diffusion length (in comparison with those of conventional pure TiO2 or Cu2O materials) which could significantly increase photocurrent to 0.65 mA/cm2 under visible light illumination (>420 nm) and also largely improve the stability of Cu2O layer, finally lead to an enhancement of water splitting performance.

  20. Characterization of CeO2-ZrO2 mixed oxides prepared by two different co-precipitation methods

    YUE Mei; CUI Meisheng; ZHANG Na; LONG Zhiqi; HUANG Xiaowei


    A series of cerium zirconium mixed oxides were prepared by two co-precipitation methods using magnesium hydrogen carbonate (MHC) and mixed ammonia-ammonia hydrogen carbonate (AAHC) as precipitant respectively.The crystal structure,BET surface area and morphology of the produced cerium zirconium mixed oxides were characterized by X-ray diffraction (XRD),Brumauer-Emmett-Teller (BET) and scanning electron microscopy (SEM) techniques.The reduction-oxidation behavior and oxygen storage capacity (OSC) performance were also studied by temperature programmed reduction (TPR) and oxygen pulse chemical adsorption methods.The XRD results demonstrated that the cerium zirconium mixed oxides obtained by both methods possessed structure of cubic solid solution phase.The fresh surface area calcinated at 600 ℃,aged surface area after 1000 ℃ and OSC at 500 ℃ of cerium zirconium mixed oxides were determined to be 89.337,34.784 m2/g,and 567 μmol O2/g for MHC method and 122.010,46.307 m2/g,and 665 μmol O2/g for AAHC method,respectively.

  1. Accuracy of pulse oximeters in detecting hypoxemia in patients with chronic thromboembolic pulmonary hypertension.

    Tomoki Kohyama

    Full Text Available Pulse oximetry is routinely used to continuously and non-invasively monitor arterial oxygen saturation (SaO2. When oxygen saturation by pulse oximeter (SpO2 overestimates SaO2, hypoxemia may be overlooked. We compared the SpO2 - SaO2 differences among three pulse oximeters in patients with chronic thromboembolic pulmonary hypertension (CTEPH who spent their daily lives in a poor oxygen state.This prospective observational study recruited 32 patients with CTEPH undergoing elective cardiac catheterization. As we collected arterial blood samples in the catheter laboratory, SpO2 values were simultaneously recorded. Three pulse oximeters were used on each patient, and SpO2 values were compared with oximetry readings using a blood gas analyzer. To determine the optimal SpO2 value by which to detect hypoxemia (SaO2≦90%, we generated receiver operating characteristic (ROC curves for each pulse oximeter.The root mean square of each pulse oximeter was 1.79 (OLV-3100, 1.64 (N-BS, and 2.50 (Masimo Radical. The mean bias (SpO2 - SaO2 for the 90%-95% saturation range was significantly higher for Masimo Radical (0.19 +/- 1.78% [OLV-3100], 0.18 +/- 1.63% [N-BS], and 1.61 +/- 1.91% [Masimo Radical]; p<0.0001. The optimal SpO2 value to detect hypoxemia (SaO2≦90% was 89% for OLV-3100, 90% for N-BS, and 92% for Masimo Radical.We found that the biases and precision with which to detect hypoxemia differed among the three pulse oximeters. To avoid hypoxemia, the optimal SpO2 should be determined for each pulse oximeter.

  2. Activation of O2 and CH4 on yttrium-stabilized zircoma for the partial oxidation of methane to synthesis gas.

    Zhu, Jianjun; Ommen, van Jan G.; Bouwmeester, Henny J.M.; Lefferts, Leon


    The isotopic exchange reaction on ZrO2 and yttrium-stabilized ZrO2 (YSZ) during catalytic partial oxidation of methane to synthesis gas (CPOM) was studied with transient pulse experiments. The results reveal, surprisingly, that CPOM over both oxides proceeds via a Mars¿van Krevelen mechanism. Despit

  3. Chemical synthesis of nanocrystalline ZrO2-SnO2 composite powders

    YANG Huaming; ZHANG Xiangchao; YANG Wuguo; HUANG Chenghuan; QIU Guanzhou


    ZrO2-SnO2 composite nanoparticles were prepared by heating the hydrate precursors synthesized by the chemical co-precipitation reaction of ZrOCl2 and SnCl4. The precursors were examined by differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The composite powder was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and desorption isotherm (Barrett-Joyner-Halenda method). The average crystal size of the nanoparticle ranges from 15 to 30 nm for the sample containing 5%-25% ZrO2 (mass fraction). Most of the pores in the ZrO2-SnO2 nanoparticles are about 10-20 nm in diameter. The composite powder is promising for chemical sensors.

  4. Dynamics of Quasiparticles in CuO2 Planes

    Mattis, Daniel C.

    At 5 electrons per cell, planar CuO2 is an antiferromagnetic insulator rather than a Fermi liquid. We consider the effects of adding a few electrons or holes into such an insulator and derive a relation between the insulating energy gap and effective mass m* of the added carriers. We find m{el}{*} to differ from m{hol}{*} , with both being temperature dependent.

  5. Adhesion of ultrathin ZrO2(111) films on Ni(111) from first principles

    Christensen, Asbjørn; Carter, Emily A.


    We have studied the ZrO2(111)/Ni(111) interface using the ultrasoft pseudopotential formalism within density functional theory. We find that ZrO2(111) adheres relatively strongly at the monolayer level but thicker ceramic films interact weakly with the Ni-substrate. We argue that the cohesion cha...

  6. Oxidation and photo-oxidation of water on TiO2 surface

    Valdes, A.; Qu, Z.W.; Kroes, G.J.


    The oxidation and photo-oxidation of water on the rutile TiO2(110) surface is investigated using density functional theory (DFT) calculations. We investigate the relative stability of different surface terminations of TiO2 interacting with H2O and analyze the overpotential needed...

  7. Effects of Ar and O2 additives on SiO2 etching in C4F8-based plasmas

    Li, Xi; Ling, Li; Hua, Xuefeng; Fukasawa, Masanaga; Oehrlein, Gottlieb S.; Barela, Marcos; Anderson, Harold M.


    Gas mixtures based on C4F8 are promising for the development of high-performance SiO2 plasma etching processes. Measurements of important gas phase species, thin film etching rates and surface chemistry changes were performed for inductively coupled plasmas fed with C4F8/Ar and C4F8/O2 gas mixtures. The addition of Ar to C4F8 causes a strong increase of the plasma density relative to that of pure C4F8 (by up to a factor of 4× at 90% Ar). For O2 addition the changes in plasma density are small up to 90% O2 relative to pure C4F8. Infrared laser absorption spectroscopy was used to determine the absolute densities of neutral CF, CF2 and COF2 radical species as a function of the gas composition. The densities of CF and CF2 were enhanced for certain operating conditions when Ar was added to C4F8 as long as the amount of Ar remained below 20%. For instance, the partial pressure of CF was 0.1 mTorr for a 20 mTorr 1400 W source power discharge for pure C4F8, and increased to 0.13 mTorr at 20% Ar. Above 20% Ar it decreased, roughly following the gas dilution. The CF2 partial pressure was about 5 mTorr for the same conditions, and increased by about 10% at 20% Ar. Above 20% Ar the CF2 partial pressure decreased roughly linearly with the amount of Ar added, to about 2 mTorr at 50% Ar. Of particular interest was the analysis of the difference in behavior of CF, CF2 and COF2 partial pressures over SiO2 and Si surfaces, with and without rf bias power (in the latter case a self-bias voltage of -100 V was used). For pure C4F8 discharges at 20 mTorr and 1400 W inductive power without rf bias the partial pressures of CF, CF2 and COF2 radicals are comparable over SiO2 and Si surfaces. Upon applying a rf bias, the CF2 partial pressure over a SiO2 surface is reduced much more strongly than for a Si surface. The overall reduction appears to be consistent with the relative SiO2/Si etch rate ratios observed for these conditions. These results indicate that CF2 is consumed during the

  8. Electrochemical and optical properties of CeO2-SnO2 and CeO2-SnO2:X (X = Li, C, Si films

    Berton Marcos A.C.


    Full Text Available Thin solid films of CeO2-SnO2 (17 mol% Sn and CeO2-SnO2:X (X = Li, C and Si were prepared by the sol-gel route, using an aqueous-based process. The addition of Li, C and Si to the precursor solution leads to films with different electrochemical performances. The films were deposited by the dip-coating technique on ITO coated glass (Donnelly Glass at a speed of 10 cm/min and submitted to a final thermal treatment at 450 °C during 10 min in air. The electrochemical and optical properties of the films were determined from the cyclic voltammetry and chronoamperometry measurements using 0.1 M LiOH as supporting electrolyte. The ion storage capacity of the films was investigated using in situ spectroelectrochemical method and during the insertion/extraction process the films remained transparent. The powders were characterized by thermal analysis (DSC/TGA and X-ray diffraction.

  9. Coating SiO2 Support with TiO2 or ZrO2 and Effects on Structure and CO Oxidation Performance of Pt Catalysts

    Mi-Young Kim


    Full Text Available In this work, we studied how TiO2 and ZrO2 coatings enhance the CO oxidation performance of SiO2-supported Pt catalysts under conditions relevant to automotive emissions control. SiO2 was coated with metal oxides TiO2 or ZrO2 by sol-gel method and the subsequent Pt loading was done by incipient wetness method. The prepared catalysts Pt/TiO2-SiO2 and Pt/ZrO2-SiO2 were compared with Pt/SiO2 and Pt/Al2O3 in fresh, sulfated, and hydrothermally aged states. The structure of the catalysts was characterized with BET, XRD, TEM, EDS, EXAFS, XANES, TPD and TPR to help interpret the CO oxidation performance. Higher dispersion, stability, and oxidation state of Pt were achieved on TiO2-SiO2 and ZrO2-SiO2 supports due to stronger metal-support interaction leading to superior CO oxidation performance compared to Pt/SiO2 and Pt/Al2O3. TiO2 and ZrO2 coatings introduced surface acidity but negligible basicity, which is a likely reason for the weak and low adsorption of SO2. The results suggest that the sol-gel coating of SiO2 with metal oxides could be an attractive strategy for designing automotive oxidation catalysts with enhanced performance such as low-temperature activity, sulfur tolerance, and hydrothermal stability.

  10. One-Pot Polyol Synthesis of Pt/CeO2 and Au/CeO2 Nanopowders as Catalysts for CO Oxidation.

    Pilger, Frank; Testino, Andrea; Lucchini, Mattia Alberto; Kambolis, Anastasios; Tarik, Mohammed; El Kazzi, Mario; Arroyo, Yadira; Rossell, Marta D; Ludwig, Christian


    The facile one-pot synthesis of CeO2-based catalysts has been developed to prepare a relatively large amount of nanopowders with relevant catalytic activity towards CO oxidation. The method consists of a two-steps process carried out in ethylene glycol: in the first step, 5 nm well-crystallized pure CeO2 is prepared. In a subsequent second step, a salt of a noble metal is added to the CeO2 suspension and the deposition of the noble metal on the nanocrystalline CeO2 is induced by heating. Two catalysts were prepared: Pt/CeO2 and Au/CeO2. The as-prepared catalysts, the thermally treated catalysts, as well as the pure CeO2, are characterized by XRD, TGA, XPS, FTIR, HR-TEM, STEM, particle size distribution, and N2-physisorption. In spite of the identical preparation protocol, Au and Pt behave in a completely different way: Au forms rather large particles, most of them with triangular shape, easily identifiable and dispersed in the CeO2 matrix. In contrast, Pt was not identified as isolated particles. The high resolution X-ray diffraction carried out on the Pt/CeO2 thermally treated sample (500 degrees C for 1 h) shows a significant CeO2 lattice shrinkage, which can be interpreted as an at least partial incorporation of Pt into the CeO2 crystal lattice. Moreover, only Pt2+ and Pt4+ species were identified by XPS. In literature, the incorporation of Pt into the CeO2 lattice is supported by first-principle calculations and experimentally demonstrated only by combustion synthesis methods. To the best of our knowledge this is the first report where ionically dispersed Pt into the CeO2 lattice is obtained via a liquid synthesis method. The thermally treated Pt/CeO2 sample revealed good activity with 50% CO conversion at almost room temperature.

  11. Optical Properties of Pyrite-structure TiO2%Pyri te-结构Ti O2的光学性质

    刘强; 肖贵乾; 杨秋萍


    利用第一性原理计算了立方相TiO2为黄铁矿结构时的光学性质,利用Kramers-Kronig色散关系分别对金红石矿TiO2和黄铁矿结构TiO2的复介电常数、吸收光谱等参数进行了计算,并将两者进行了比较。金红石矿TiO2的静介电常数的计算结果与实验值一致,而黄铁矿结构TiO2的静介电常数为6.02。吸收谱的对比分析结果表明:与金红石矿TiO2相比,黄铁矿结构TiO2在30 nm处增加了新的吸收峰,并且吸收谱范围扩大到了可见光区。%A density functional theory is used in calculating the optical properties of pyrite type TiO2 . In addition,the author calculated the complex dielectric constant and absorption spectrum of rutile type TiO2 and pyrite type TiO2 through Kramers-Kronig dispersion relation and compared the results of two kinds of structure.It is suggested that the static dielectric constant of rutile type TiO2 calculated is in accord with corresponding experimental data,meanwhile,the static dielectric constant of pyrite type TiO2 is 6.02.The comparison of absorption spectrum in these two structures indicated that a new absorption peak at 30 nm can be observed in absorption spectrum of pyrite type TiO2 and the absorp-tion range extended to the visible region compared with rutile type TiO2 .

  12. Synthesis of iron(Ⅲ)-doped nanostructure TiO2/SiO2 and their photocatalytic activity


    Iron(Ⅲ)-doped nanostructure TiO2-coated SiO2 (TiO2/SiO2) particles were prepared using the layer-by-layer assembly technique and their photocatalytic property was studied. TiO2 colloids were synthesized employing the sol-gel method with TiCl4 as a precursor. The samples were characterized by Fourier transform infrared spectroscopy (FTIR), SEM, EDS, XPS, and XRD. The experimental results show that TiO2 nanopowders on the surface of SiO2 particles are well distributed, the amount of TiO2 is increased with the adding of coating layers, the pure anatase-TiO2 coating layers are synthesized at 500℃, and the photocatalytic activity of Fe3+-doped TiO/SiO2 is higher than tnat of undoped TiO2/SiO2.

  13. Growth of HT-LiCoO2 thin films on Pt-metalized silicon substrates

    ZHANG Yao; CHUNG Chiyuen; ZHU Min


    Layered LiCoO2 (HT-LiCoO2) films were grown on Pt-metalized silicon (PMS) substrates and polished bulk nickel (PBN) substrates by pulsed laser deposition. The effects of substrate temperature, oxygen pressure, and substrate surface roughness on the microstructure of LiCoO2 films were investigated. It has been found that a higher substrate temperature and a higher oxygen pressure favor the formation of better crystallized and less lithium-deficient HT-LiCoO2 films. The HT-LiCoO2 film deposited on PBN substrates consists of large randomly orientated equiaxial grains, whereas on PMS substrate, it is made up of loosely packed highly [001] preferential orientated triangular shaped grains with the average grain size less than 100nm. Electrochemical measurements show that the highly [001] preferentially orientated nanostructured HT-LiCoO2 thin film grown on PMS substrate has good structural stability upon lithium insertion/extraction and can deliver an initial discharge capacity of approximately 45 μA·h·cm-2μm-1 with a cycling efficiency of above 99% at the charge/discharge rate of 0.5C.

  14. Variation of Photocatalytic Function of TiO2 Film by Femtosecond Laser Irradiation

    Tsukamoto, Masahiro; Shinonaga, Togo; Horiguchi, Naoto; Yoshida, Minoru; Fujita, Masayuki; Abe, Nobuyuki

    Titanium dioxide (TiO2) is functional ceramics and shows the photocatalytic function by ultraviolet light illumination. This photocatalytic function enables decomposition of organic matter such as bacteria, mold and odors. In our previous study, the TiO2 film was darkened by the femtosecond laser irradiation and electrical resistance of the darkened film was decreased. In this study, we investigated variation of the photocatalytic function of the darkened TiO2 films. The TiO2 film was produced by aerosol beam irradiation. The wavelength, the pulse width and the repetition rate of the femtosecond laser were 775 nm, 150 fs and 1 kHz, respectively. The laser spot was scanned on the whole area of the TiO2 film surface and the laser fluence was changed within the laser fluence regime in which the laser ablation was not caused and topography of the film surface was not varied. The photocatalytic function of the darkened TiO2 films was evaluated in the acetaldehyde decomposition test. In the test, the films in acetaldehyde were illuminated with the UV and visible light sources, respectively. The acetaldehyde concentration was measured every hour during the illumination. The results of the test shows that the film had photocatalytic function by visible light illumination.

  15. Pulse oximetry recorded from the Phone Oximeter for detection of obstructive sleep apnea events with and without oxygen desaturation in children.

    Garde, Ainara; Dehkordi, Parastoo; Wensley, David; Ansermino, J Mark; Dumont, Guy A


    Obstructive sleep apnea (OSA) disrupts normal ventilation during sleep and can lead to serious health problems in children if left untreated. Polysomnography, the gold standard for OSA diagnosis, is resource intensive and requires a specialized laboratory. Thus, we proposed to use the Phone Oximeter™, a portable device integrating pulse oximetry with a smartphone, to detect OSA events. As a proportion of OSA events occur without oxygen desaturation (defined as SpO2 decreases ≥ 3%), we suggest combining SpO2 and pulse rate variability (PRV) analysis to identify all OSA events and provide a more detailed sleep analysis. We recruited 160 children and recorded pulse oximetry consisting of SpO2 and plethysmography (PPG) using the Phone Oximeter™, alongside standard polysomnography. A sleep technician visually scored all OSA events with and without oxygen desaturation from polysomnography. We divided pulse oximetry signals into 1-min signal segments and extracted several features from SpO2 and PPG analysis in the time and frequency domain. Segments with OSA, especially the ones with oxygen desaturation, presented greater SpO2 variability and modulation reflected in the spectral domain than segments without OSA. Segments with OSA also showed higher heart rate and sympathetic activity through the PRV analysis relative to segments without OSA. PRV analysis was more sensitive than SpO2 analysis for identification of OSA events without oxygen desaturation. Combining SpO2 and PRV analysis enhanced OSA event detection through a multiple logistic regression model. The area under the ROC curve increased from 81% to 87%. Thus, the Phone Oximeter™ might be useful to monitor sleep and identify OSA events with and without oxygen desaturation at home.

  16. Experimental evidences of charge transition levels in ZrO2 and at the Si: ZrO2 interface by deep level transient spectroscopy

    Kumar, Arvind; Mondal, Sandip; Koteswara Rao, K. S. R.


    The native defects in zirconium oxide (ZrO2) and defects at the ZrO2/Si interface lead to threshold voltage shifts, Fermi level pinning, and various other reliability concerns. It is necessary to recognize the origin of these defects and to quantify them. A large number of theoretical reports deal with oxygen vacancy related defect states in the ZrO2 films; however, the large band gap limits the experimental assessments. In this study, we have deployed Deep Level Transient Spectroscopy to study the deep level defects present in high-κ ZrO2 gate dielectrics and at the Si:ZrO2 interface. The band alignment of the Al/ZrO2/Si stack was derived from Ultraviolet Photo electron Spectroscopy measurement to find the exact locations of trap levels. Five deep levels were observed in the band gap of ZrO2; these are related to different charge states of oxygen vacancies. The activation energies of these trap states are in the range of 1.16-1.84 eV from the ZrO2 conduction band. The capture cross-section of these states was also measured and found to be quite low (10-21 cm2). The small value of capture cross-sections is attributed to tunneling events occurring between the energy levels of the bulk and interface. This study would aid in the understanding of numerous fascinating facts witnessed in ZrO2, such as resistive switching, threshold voltage instabilities, and leakage current problems associated with oxygen vacancy related traps.

  17. Preparation of Photocatalytic TiO2 and TiO2-SiO2 Particles and Application to Degradation of Trace Organics in Aqueous Solution



    TiO2 and TiO2-SiO2 photocatalysts were prepared by sol-gel and supercritical CO2 fluid drying method and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), etc. Their catalytic properties were tested through the photocatalytic degradation of phenol and aniline in wastewater. The results show that the developed fluidized photocatalytic reactor (FPR) and TiO2 catalyst had better performance in degrading pollutants as compared with slurry photocatalytic reactor (SPR) and commercial TiO2 catalyst. The composition and crystal form of TiO2-SiO2 composite oxide had obvious influence on catalytic effect and TiO2-SiO2 photocatalysts showed better catalytic activity and stability.

  18. A CdS/ZnSe/TiO2 nanotube array and its visible light photocatalytic activities.

    Nguyen, VanManh; Li, Weili; Pham, VanHuan; Wang, Lijia; Sheng, Pengtao; Cai, Qingyun; Grimes, Craig


    A novel CdS/ZnSe/TiO2 nanotube array (NTA) photoelectrode was prepared by deposition of ZnSe nanoparticles (NPs) using pulse electrodeposition technique onto a TiO2 NTA. By successive ion layer adsorption and reaction (SILAR), CdS quantum dots (QDs) deposit onto a ZnSe/TiO2 NTA photoelectrode. The as-prepared CdS/ZnSe/TiO2 NTA photoelectrode performance is significantly improved, which not only greatly extends spatial separation of charges, but also enhance the utilization efficiency of visible-light. This system exhibits excellent charges transport property. The maximum photocurrent density of an 8.25mAcm(-2) was observed in the CdS/ZnSe/TiO2 NTA photoelectrode, which is 37.5, 15.86 and 1.56 times higher than bare TiO2 NTA, ZnSe/TiO2 NTA, and CdS/TiO2NTA photoelectrodes, respectively. The photocatalytic activity of CdS/ZnSe/TiO2 NTA is tested by the degradation of methyl orange (MO) in distilled water under solar light irradiation of 100mW/cm(2). Within about 120min of irradiation, 90.05% MO are removed. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Effect of Nanoparticle Surface Modification and Filling Concentration on Space Charge Characteristics in TiO2/XLPE Nanocomposites

    Youyuan Wang


    Full Text Available This paper focuses on the space charge characteristics in TiO2/cross-linked polyethylene (XLPE nanocomposites; the unmodified and modified by dimethyloctylsilane (MDOS TiO2 nanoparticles were added to XLPE matrix with different mass concentrations (1 wt%, 3 wt%, and 5 wt%. The scanning electron microscope (SEM showed that the MDOS coupling agent could improve the compatibility between TiO2 nanoparticles and XLPE matrix to some extent and reduce the agglomeration of TiO2 nanoparticles compared with unmodified TiO2 nanoparticles; the volume resistivity testing indicated that the volume resistivity of TiO2/XLPE nanocomposites was higher than Pure-XLPE and increased with the increase of filling concentrations. According to the pulsed electroacoustic (PEA measurements, it was concluded that the space charge accumulation was suppressed by filling TiO2 nanoparticles and the distribution of electric field in samples was improved greatly. In addition, it was found that the injection of homocharge was more obvious in MDOS-TiO2/XLPE than that in UN-TiO2/XLPE and the homocharge injection decreased with the increase of filling concentration.

  20. BSA-templated MnO2 nanoparticles as both peroxidase and oxidase mimics.

    Liu, Xing; Wang, Qi; Zhao, Huihui; Zhang, Lichun; Su, Yingying; Lv, Yi


    Inorganic nanomaterials that mimic enzymes are fascinating as they potentially have improved properties relative to native enzymes, such as greater resistance to extremes of pH and temperature and lower sensitivity to proteases. Although many artificial enzymes have been investigated, searching for highly-efficient and stable catalysts is still of great interest. In this paper, we first demonstrated that bovine serum albumin (BSA)-stabilized MnO(2) nanoparticles (NPs) exhibited highly peroxidase-, oxidase-, and catalase-like activities. The activities of the BSA-MnO(2) NPs were evaluated using the typical horseradish peroxidase (HRP) substrates o-phenylenediamine (OPD) and 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of either hydrogen peroxide or dissolved oxygen. These small-sized BSA-MnO(2) NPs with good dispersion, solubility and biocompatibility exhibited typical Michaelis-Menten kinetics and high affinity for H(2)O(2), OPD and TMB, indicating that BSA-MnO(2) NPs can be used as satisfactory enzyme mimics. Based on these findings, BSA-MnO(2) NPs were used as colorimetric immunoassay tags for the detection of goat anti-human IgG in place of HRP. The colorimetric immunoassay using BSA-MnO(2) NPs has the advantages of being fast, robust, inexpensive, easily prepared and with no HRP and H(2)O(2) being needed. These water-soluble BSA-MnO(2) NPs may have promising potential applications in biotechnology, bioassays, and biomedicine.

  1. Effects of nano-SiO2 on the adsorption of chiral metalaxyl to agricultural soils.

    Huang, Junxing; Liang, Chuanzhou; Zhang, Xu


    The application of nanotechnology in agriculture, pesticide delivery and other related fields increases the occurrence of engineered nanoparticles (ENPs) in soil. Since ENPs have larger surface areas and normally a high adsorption capacity for organic pollutants, they are thought to influence the transport of pesticides in soils and thereafter influence the uptake and transformation of pesticides. The adsorption pattern of racemic-metalaxyl on agricultural soils including kinetics and isotherms changed in the presence of nano-SiO2. The adsorption of racemic-metalaxyl on agricultural soil was not enantioselective, in either the presence or the absence of SiO2. The adsorption of racemic-metalaxyl on SiO2 decreased to some extent in soil-SiO2 mixture, and the absolute decrease was dependent on soil properties. The decreased adsorption of metalaxyl on SiO2 in soil-SiO2 mixture arose from the competitive adsorption of soil-dissolved organic matter and the different dispersion and aggregation behaviors of SiO2 in the presence of soil. Interactions between SiO2 and soil particles also contributed to the decreased adsorption of metalaxyl on SiO2, and the interactions were analyzed by extended Derjaguin-Landau-Verwey-Overbeek theory. The results showed that the presence of nano-particles in soils could decrease the mobility of pesticides in soils and that this effect varied with different soil compositions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Synthesis and characterization of conductive polyaniline/TiO2 composite nanofibers

    SU Bitao; MIN Shixiong; SHE Shixiong; TONG Yongchun; BAI Jie


    Fibrillar conductive polyaniline/TiO2 (PANI/TiO2) nanocomposites with different TiO2 amount were synthesized with a template-free in situ polymerization method and characterized by transmission electron microscopy (TEM),X-ray diffraction (XRD),Fourier transform infrared spectroscopy (FT-IR) and conductivity measurement.The morphology determination shows that the PANI/TiO2 composite nanofibers are relatively uniform with the diameter and length in the range of 20-40 nm and 390-420 nm respectively.It also shows that the TiO2 of the composite is rutile crystalline and PANI has some degree of crystallinity.The IR measurement indicates that there is a strong interaction between the PANI and TiO2 nanoparticles,and it has a beneficial effect on the thermal stability of the composite nanofiber.The conductivity of PANI/TiO2 composites changes with TiO2 amount and reaches an optimum value of 2.86 S/cm at 11.1 wt% TiO2.

  3. Controllable Synthesis and Tunable Photocatalytic Properties of Ti(3+)-doped TiO2.

    Ren, Ren; Wen, Zhenhai; Cui, Shumao; Hou, Yang; Guo, Xiaoru; Chen, Junhong


    Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti(3+)-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti(4+) on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti(3+)-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity.

  4. Influence of femtosecond surface modification of TiO2 layer to features of organic solar cell

    Sabonis Vytautas


    Full Text Available In this research 300 fs pulses of Yb:KGW laser has been applied to form electron transport layer TiO2 of Grӓtzel type organic solar cells (OSC with different surface roughness. Profiler, AFM, SEM has been used to define surfaces. Scattering of 532 nm wavelength light from ablated regions has been measured. OSC have been formed onto TiO2 and I-V characteristics have been measured. Investigation results demonstrated that laser treatment of TiO2 has impact to the I-V dependencies of OSC.

  5. Optical properties of a HfO2/Si stack with a trace amount of nitrogen incorporation

    Li Ye; Jiang Tingting; Sun Qingqing; Wang Pengfei; Ding Shijin; Zhang Wei


    HfO2 films were deposited by atomic layer deposition through alternating pulsing of Hf[N(C2H5)(CH3)]4 and H2O2.A trace amount of nitrogen was incorporated into the HfO2 through ammonia annealing.The composition,the interface stability of the HfO2/Si stack and the optical properties of the annealed films were analyzed to investigate the property evolution of HfO2 during thermal treatment.With a nitrogen concentration increase from 1.41 to 7.45%,the bandgap of the films decreased from 5.82 to 4.94 eV.

  6. Reaction pathways of dimethyl phthalate degradation in TiO2-UV-O2 and TiO2-UV-Fe(VI) systems.

    Yuan, Bao-ling; Li, Xiang-zhong; Graham, Nigel


    The photocatalytic degradation of dimethyl phthalate (DMP) in aqueous TiO2 suspension under UV illumination has been investigated using oxygen (O2) and ferrate (Fe(VI)) as electron acceptors. The experiments demonstrated that Fe(VI) was a more effective electron acceptor than O2 for scavenging the conduction band electrons from the surface of the catalyst. Some major intermediate products from DMP degradation were identified by HPLC and GC/MS analyses. The analytical results identified dimethyl 3-hydroxyphthalate and dimethyl 2-hydroxyphthalate as the two main intermediate products from the DMP degradation in the TiO2-UV-O2 system, while in contrast phthalic acid was found to be the main intermediate product in the TiO2-UV-Fe(VI) system. These findings indicate that DMP degradation in the TiO2-UV-O2 and TiO2-UV-Fe(VI) systems followed different reaction pathways. An electron spin resonance analysis confirmed that hydroxyl radicals existed in the TiO2-UV-O2 reaction system and an unknown radical species (most likely an iron-oxo species) is suspected to exist in the TiO2-UV-Fe(VI) reaction system. Two pathway schemes of DMP degradation in the TiO2-UV-O2 and TiO2-UV-Fe(VI) reaction systems are proposed. It is believed that the radicals formed in the TiO2-UV-O2 reaction system preferably attack the aromatic ring of the DMP, while in contrast the radicals formed in the TiO2-UV-Fe(VI) reaction systems attack the alkyl chain of DMP.

  7. Aspects of the SrO-CuO-TiO2 Ternary System Related to the Deposition of SrTiO3 and Copper-Doped SrTiO3 Thin-Film Buffer Layers

    A. Ayala


    YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) coated conductors are promising materials for large-scale superconductivity applications. One version of a YBCO coated conductor is based on ion beam assisted deposition (IBAD) of magnesium oxide (MgO) onto polycrystalline metal substrates. SrTiO{sub 3} (STO) is often deposited by physical vapor deposition (PVD) methods as a buffer layer between the YBCO and IBAD MgO due to its chemical stability and lattice mismatch of only {approx}1.5% with YBCO. In this work, some aspects of the stability of STO with respect to copper (Cu) and chemical solution deposition of STO on IBAD MgO templates were examined. Solubility limits of Cu in STO were established by processing Cu-doped STO powders by conventional bulk preparation techniques. The maximum solubility of Cu in STO was {approx}1% as determined by transmission electron microscopy (TEM) and Rietveld refinements of x-ray diffraction (XRD) data. XRD analysis, performed in collaboration with NIST, on powder compositions on the STO/SrCuO{sub 2} tie line did not identify any ternary phases. SrCu{sub 0.10}Ti{sub 0.90}O{sub y} buffer layers were prepared by pulsed laser deposition (PLD) and CSD on IBAD MgO flexible metallic textured tapes. TEM analysis of a {approx}100 nm thick SrCu{sub 0.10}Ti{sub 0.90}O{sub y} buffer layer deposited by PLD showed a smooth Cu-doped STO/MgO interface. A {approx}600 nm thick YBCO film, deposited onto the SrCu{sub 0.10}Ti{sub 0.90}O{sub y} buffer by PLD, exhibited a T{sub c} of 87 K and critical current density (J{sub c}) of {approx}1 MA/cm{sup 2}. STO and Cu-doped STO thin films by CSD were {approx}30 nm thick. The in plane alignment (FWHM) after deposition of the STO improved by {approx}1{sup o} while it degraded by {approx}2{sup o} with the SrCu{sub 0.05}TiO{sub y} buffer. YBCO was deposited by PLD on the STO and SrCu{sub 0.05}TiO{sub y} buffers. The in plane alignment (FWHM) of the YBCO with the STO buffer layer slightly improved while that of the

  8. Investigation of signal processing algorithms for an embedded microcontroller-based wearable pulse oximeter.

    Johnston, W S; Mendelson, Y


    Despite steady progress in the miniaturization of pulse oximeters over the years, significant challenges remain since advanced signal processing must be implemented efficiently in real-time by a relatively small size wearable device. The goal of this study was to investigate several potential digital signal processing algorithms for computing arterial oxygen saturation (SpO(2)) and heart rate (HR) in a battery-operated wearable reflectance pulse oximeter that is being developed in our laboratory for use by medics and first responders in the field. We found that a differential measurement approach, combined with a low-pass filter (LPF), yielded the most suitable signal processing technique for estimating SpO(2), while a signal derivative approach produced the most accurate HR measurements.

  9. Attosecond control of orbital parity mix interferences and the relative phase of even and odd harmonics in an attosecond pulse train.

    Laurent, G; Cao, W; Li, H; Wang, Z; Ben-Itzhak, I; Cocke, C L


    We experimentally demonstrate that atomic orbital parity mix interferences can be temporally controlled on an attosecond time scale. Electron wave packets are formed by ionizing argon gas with a comb of odd and even high-order harmonics, in the presence of a weak infrared field. Consequently, a mix of energy-degenerate even and odd parity states is fed in the continuum by one- and two-photon transitions. These interfere, leading to an asymmetric electron emission along the polarization vector. The direction of the emission can be controlled by varying the time delay between the comb and infrared field pulses. We show that such asymmetric emission provides information on the relative phase of consecutive odd and even order harmonics in the attosecond pulse train.

  10. First Principles Hartree-Fock Description of Lithium Insertion in Oxides. I. The End Members TiO 2and LiTiO 2of the System Li xTiO 2

    Mackrodt, W. C.


    First principles periodic Hartree-Fock calculations are reported for the P4 2/ mnm(rutile), I4 1/ amd(anatase), Pbca(brookite), Pnma(ramsdellite), Pcbn(colombite), Fdoverline3m(spinel), and Imma(orthorhombic) polymorphs of TiO 2, from which the predicted order of stability is The calculated difference in energy between the rutile and anatase structures is 0.02-0.06 eV, in good agreement with a recent local density approximation (LDA) estimate of 0.033 eV and an experiment enthalpy difference of 0.05 eV. The corresponding Hartree-Fock and LDA differences for the brookite structure are 0.06 and 0.058 eV, respectively. The calculated volumes, which are based on isotropic volume-optimized Hartree-Fock energies, are also in good agreement with recent LDA calculations and with experiment. Spin-unrestricted calculations are reported for the Fmoverline3m, Imma, Pnma, and P4 2/ mmmof LiTiO 2, where the stability is in the order The only reported phase for LiTiO 2is Fmoverline3m, for which the calculated volume is in good agreement with experiment. From the relative stabilities of TiO 2and LiTiO 2, the relative lithium insertion potentials corresponding to TiO 2 → LiTiO 2are deduced, with a maximum variation of 1.6 eV for the different polymorphic routes. The maximum voltage predicted is that for the Immaroute which is ˜1 eV larger than that for Pnma. Direct comparisons with the calculated energy for C2/ mLi 0.5MnO 2 → LiMnO 2lead to an estimate of the voltage for ImmaTiO 2 → LiTiO 2of ˜1.3 eV, which is ˜2.5 eV anodicto the Mn system. The corresponding values for the Pnmapolymorphic route are ˜3 and ˜3.5 eV, respectively. Mulliken population analyses indicate that lithium is completely ionized in LiTiO 2and that the charge transfer is predominantly to the oxygen sublattice. There is a rehybridization of the titanium valence orbitals leading to a slight increase in the 3 dpopulation and strong localization of spin density at the titanium sites with local moments of

  11. Adsorption and reactions of O2 on anatase TiO2.

    Li, Ye-Fei; Aschauer, Ulrich; Chen, Jia; Selloni, Annabella


    CONSPECTUS: The interaction of molecular oxygen with titanium dioxide (TiO2) surfaces plays a key role in many technologically important processes such as catalytic oxidation reactions, chemical sensing, and photocatalysis. While O2 interacts weakly with fully oxidized TiO2, excess electrons are often present in TiO2 samples. These excess electrons originate from intrinsic reducing defects (oxygen vacancies and titanium interstitials), doping, or photoexcitation and form polaronic Ti(3+) states in the band gap near the bottom of the conduction band. Oxygen adsorption involves the transfer of one or more of these excess electrons to an O2 molecule at the TiO2 surface. This results in an adsorbed superoxo (O2(-)) or peroxo (O2(2-)) species or in molecular dissociation and formation of two oxygen adatoms (2 × O(2-)). Oxygen adsorption is also the first step toward oxygen incorporation, a fundamental reaction that strongly affects the chemical properties and charge-carrier densities; for instance, it can transform the material from an n-type semiconductor to a poor electronic conductor. In this Account, we present an overview of recent theoretical work on O2 adsorption and reactions on the reduced anatase (101) surface. Anatase is the TiO2 polymorph that is generally considered most active in photocatalysis. Experiments on anatase powders have shown that the properties of photoexcited electrons are similar to those of excess electrons from reducing defects, and therefore, oxygen on reduced anatase is also a model system for studying the role of O2 in photocatalysis. Experimentally, the characteristic Ti(3+) defect states disappear after adsorption of molecular oxygen, which indicates that the excess electrons are indeed trapped by O2. Moreover, superoxide surface species associated with two different cation surface sites, possibly a regular cation site and a cation close to an anion vacancy, were identified by electron paramagnetic resonance spectroscopy. On the

  12. Structure and photoluminescence properties of TeO2-core/TiO2-shell nanowires

    Park, Sunghoon; An, Soyeon; Lee, Chongmu


    TeO2-core/TiO2-shell nanowires were fabricated by thermal evaporation of Te powders and MOCVD of TiO2. The as-synthesized TeO2 nanowires showed a weak broad violet band centered at approximately 430 nm. The emission peak was shifted to a bluish violet region (∼455 nm) by the encapsulation of the nanowires with a TiO2 thin film. The intensity of the major emission from the core-shell nanowires showed strong dependence on the shell layer thickness. The strongest emission was obtained for the shell layer thickness of ∼15 nm and its intensity was approximately 80 times higher than that of the violet emission from the as-synthesized TeO2 nanowires. This enhancement in emission intensity is attributed to the subwavelength optical resonant cavity formation in the shell layer. The major emission intensity was enhanced further and blue-shifted by annealing, which might be attributed to the increase in the Ti interstitial and O vacancy concentrations in the TeO2 cores during annealing.

  13. MnO2/CeO2 for catalytic ultrasonic degradation of methyl orange.

    Zhao, He; Zhang, Guangming; Zhang, Quanling


    Catalytic ultrasonic degradation of aqueous methyl orange was studied in this paper. Heterogeneous catalyst MnO2/CeO2 was prepared by impregnation of manganese oxide on cerium oxide. Morphology and specific surface area of MnO2/CeO2 catalyst were characterized and its composition was determined. Results showed big differences between fresh and used catalyst. The removal efficiency of methyl orange by MnO2/CeO2 catalytic ultrasonic process was investigated. Results showed that ultrasonic process could remove 3.5% of methyl orange while catalytic ultrasonic process could remove 85% of methyl orange in 10 min. The effects of free radical scavengers were studied to determine the role of hydroxyl free radical in catalytic ultrasonic process. Results showed that methyl orange degradation efficiency declined after adding free radical scavengers, illustrating that hydroxyl free radical played an important role in degrading methyl orange. Theoretic analysis showed that the resonance size of cavitation bubbles was comparable with the size of catalyst particles. Thus, catalyst particles might act as cavitation nucleus and enhance ultrasonic cavitation effects. Measurement of H2O2 concentration in catalytic ultrasonic process confirmed this hypothesis. Effects of pre-adsorption on catalytic ultrasonic process were examined. Pre-adsorption significantly improved methyl orange removal. The potential explanation was that methyl orange molecules adsorbed on catalysts could enter cavitation bubbles and undergo stronger cavitation.

  14. Synthesis and Bactericidal Ability of TiO2 and Ag-TiO2 Prepared by Coprecipitation Method

    Robert Liu; Wu, H. S.; Ruth Yeh; Lee, C Y; Yungtse Hung


    Preparation of photocatalysts of TiO2 and Ag-TiO2 was carried out by coprecipitation method. The prepared photocatalysts were characterized by X-ray diffraction (XRD), SEM, EDX, and XRF analysis. The disinfection of E. coli, a model indicator organism for the safe water supply, was investigated by using TiO2 and Ag-TiO2 under different light sources. The treatment efficacy for the inactivation of E. coli would be UV/Ag-TiO2; visible/Ag-TiO2; dark/Ag-TiO2; UV (all 100%) > UV/TiO2 (99%) > visib...

  15. Adsorption Kinetics of Acid Orange 7 on Nano-CeO2-TiO2 in Water.

    Song, Xiaozhen; Zhao, Bin; Gu, Mingjie; Li, Ruixing


    To investigate the application of nano-CeO2-TiO2 as a sorbent in wastewater treatment, CeO2-TiO2 powder was prepared by the solvothermal method and then characterized. The adsorption kinetics of the adsorption of acid orange 7 (AO7) on CeO2-TiO2 were investigated under various conditions, such as initial concentration, temperature, and pH of the AO7 solution. Kinetic analyses were conducted with both Lagergren pseudo-first and pseudo-second order models. The results showed that the CeO2-TiO2 powder was composed of cubic CeO2 and anatase TiO2 with a specific surface area of 140.42 m2 x g(-1). The adsorption capacity of AO7 on CeO2-TiO2 increased with increasing starting concentration of AO7, but decreased with increasing temperature. The most favorable pH range of the A07 solution was 3-8 for the adsorption of AO7 on CeO2-TiO2. The results revealed that the adsorption kinetics of AO7 on CeO2-TiO2 matched the pseudo-second order model very well. The results indicate that CeO2-TiO2 has a potential application in the removal of AO7 from wastewater.

  16. O2-sensing and O2-dependent gene regulation in facultatively anaerobic bacteria.

    Unden, G; Becker, S; Bongaerts, J; Holighaus, G; Schirawski, J; Six, S


    Availability of O2 is one of the most important regulatory signals in facultatively anaerobic bacteria. Various two- or one-component sensor/regulator systems control the expression of aerobic and anaerobic metabolism in response to O2. Most of the sensor proteins contain heme or Fe as cofactors that interact with O2 either by binding or by a redox reaction. The ArcA/ArcB regulator of aerobic metabolism in Escherichia coli may use a different sensory mechanism. In two-component regulators, the sensor is located in the cytoplasmic membrane, whereas one-component regulators are located in the cytoplasm. Under most conditions, O2 can readily reach the cytoplasm and could provide the signal in the cytoplasm. The transcriptional regulator FNR of E. Coli controls the expression of many genes required for anaerobic metabolism in response to O2. Functional homologs of FNR are present in facultatively anaerobic Proteobacteria and presumably also in gram-positive bacteria. The target genes of FNR are mostly under multiple regulation by FNR and other regulators that respond to O2, nitrate, or glucose. FNR represents a 'one-component' sensor/regulator and contains Fe for signal perception. In response to O2 availability, FNR is converted reversibly from the aerobic (inactive) state to the anaerobic (active) state. Experiments suggest that the Fe cofactor is bound by four essential cysteine residues. The O2-triggered transformation between active and inactive FNR presumably is due to a redox reaction at the Fe cofactor, but other modes of interaction cannot be excluded. O2 seems to affect the site-specific DNA binding of FNR at target genes or the formation of an active transcriptional complex with RNA polymerase.

  17. Stability and Occurrence of the Molecule-Containing SiO2 Clathrate Melanophlogite: Metastable Crystallization from a Colloid or Gel?

    Geiger, C. A.; Dachs, E.


    The mineral melanophlogite is the only known natural SiO2 clathrate. It has been found in a number of localities worldwide in different low-temperature geologic environments. Melanophlogite's thermodynamic stability is not known. Low-temperature hydrothermal laboratory experiments indicate that structure-directing agents and colloid formation are needed for crystallization. The formation of silica-rich colloids/gels and following crystal growth can be observed in glass-ampoule synthesis experiments. In order to better address these issues, the heat capacities of two different molecule-containing melanophlogites of approximate composition 46SiO2·1.80CH4·3.54N2·1.02CO2 from Mt. Hamilton, CA and 46SiO2·3.59CH4·3.10N2·1.31CO2 from Racalmuto, Sicily, along with a heated (molecule-free) sample of composition SiO2, were studied between 5 and 300 K using heat- pulse microcalorimetry. The molecule-free sample was obtained by heating a natural Racalmuto sample at 1173 K for 24 hr. It has a slightly larger low-temperature heat capacity and standard third-law entropy compared to other low-density SiO2 polymorphs such as various zeosils. The standard third-law entropy of the molecule-free sample is S° = 2216.3 J/(mol·K) for 46SiO2 and the natural Mt. Hamilton and Racalmuto samples give S° = 2805.7 J/(mol·K) and S° = 2956.8 J/(mol· K), respectively. The entropy and Gibbs free energy for molecule-free melanophlogite relative to quartz at 298 K are Δ Strans = 6.7 J/(mol·K) and Δ Gtrans = 7.5 kJ/mol, respectively and, thus, it does not have a thermodynamic field of stability in the SiO2 system. The difference in Cp values between molecule-containing and molecule-free melanophlogite is characterized by an increase in Cp from 0 K to approximately 70 K and then reaches a roughly constant value at 70 K cristobalite and chalcedony, suggest that melanophlogite crystallizes metastabily from gels. The occurrence of melanophlogite, and the lack of other SiO2clathrates

  18. A Novel Toxicological Evaluation of TiO2 Nanoparticles on DNA Structure

    ZHU, Rong-Rong; WANG, Shi-Long; ZHANG, Rui; SUN, Xiao-Yu; YAO, Si-De


    TiO2 has been tested to be toxic to DNA under the photo-irradiation of ultraviolet A (UVA). However, in the dark conditions, after several days of treatment with TiO2 in aqueous solution, the interaction between TiO2 and two types of DNA was detected and the mechanisms were studied by the methods of gel-electrophoresis, IR spectroscopy and TEM. The results showed that the DNA would be bound to TiO2; the ratio of binding was related to the concentration and the treating time; the mechanism of binding is related to phosphate groups of DNA. Besides,DNA with different structure showed different degree of binding. These findings showed a new possible way through which the TiO2 nanoparticles interact with DNA.


    M.I. Abbas; K. Ibrahim; Z.Y. Wu; J. Zhang; F.Q. Liu; H.J. Qian


    Photoemission behaviors of nano-CeO2 films with particle sizes ranging from 8nm 1o50nm and bulk CeO2 in Ce 4d-4f absorption region have been investigated. Resonantenhancements of Ce 4f valance band and Ce 5p bands for nano film and bulk materialhave been observed. The variation of electron density of states in valance bands ofnano and bulk structures of CeO2 is discussed in terms of Ce 4d-4f resonance.

  20. Freezing Resistance of HPC with Nano-SiO2

    WANG Baomin; WANG Lijiu; F C Lai


    The test of fast-freezing method is employed to research the freezing resistance of C60and C80 high-performance concrete with nanometer-SiO2,and XRD and SEM are employed to analyze the mechanism of its influence.The experimental results show that the freezing resistance of high-performance concrete has been effectively improved.The compressive strength of C60,C70 and C80 high-performance concrete added with nano-SiO2 can be improved by 8%,6% and 5% respectively,the weight loss can be reduced by 1%,0.6% and 0.3% respectively and the relative dynamic elastic modulus can be improved by 7%,4% and 6%respectively after the 300 times freeze-thaw cycle.

  1. Memory and learning behaviors mimicked in nanogranular SiO2-based proton conductor gated oxide-based synaptic transistors

    Wan, Chang Jin; Zhu, Li Qiang; Zhou, Ju Mei; Shi, Yi; Wan, Qing


    In neuroscience, signal processing, memory and learning function are established in the brain by modifying ionic fluxes in neurons and synapses. Emulation of memory and learning behaviors of biological systems by nanoscale ionic/electronic devices is highly desirable for building neuromorphic systems or even artificial neural networks. Here, novel artificial synapses based on junctionless oxide-based protonic/electronic hybrid transistors gated by nanogranular phosphorus-doped SiO2-based proton-conducting films are fabricated on glass substrates by a room-temperature process. Short-term memory (STM) and long-term memory (LTM) are mimicked by tuning the pulse gate voltage amplitude. The LTM process in such an artificial synapse is due to the proton-related interfacial electrochemical reaction. Our results are highly desirable for building future neuromorphic systems or even artificial networks via electronic elements.In neuroscience, signal processing, memory and learning function are established in the brain by modifying ionic fluxes in neurons and synapses. Emulation of memory and learning behaviors of biological systems by nanoscale ionic/electronic devices is highly desirable for building neuromorphic systems or even artificial neural networks. Here, novel artificial synapses based on junctionless oxide-based protonic/electronic hybrid transistors gated by nanogranular phosphorus-doped SiO2-based proton-conducting films are fabricated on glass substrates by a room-temperature process. Short-term memory (STM) and long-term memory (LTM) are mimicked by tuning the pulse gate voltage amplitude. The LTM process in such an artificial synapse is due to the proton-related interfacial electrochemical reaction. Our results are highly desirable for building future neuromorphic systems or even artificial networks via electronic elements. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr02987e

  2. Catalysis of SO42--ZrO2/TiO2 nanometer solid superacid

    LU Wei-qi; Zhou Yang; Liu Yi-lu


    Superacid catalyst SO42--ZrO2/TiO2 was applied in esterification of Acetic Acid and Butanol. The particle size of ZrO2 in the catalyst was about 12.5 nm. In catalyst preparation conditions, the effect factor order on catalytic activity is H2SO4 concentration > calcination temperature > ZrO2 supported content. The optimum preparation condition is as follows: ZrO2 content 3.5g/g; calcination temperature 600℃, and H2SO4 concentration 0.5mol/L. The catalytic activity is 96.5 vol%.SO42-/MxOy solid superacid is a kind of green catalyst, whose application perspective is bright. In this paper, SO42--ZrO2/TiO2 solid superacid was prepared with nanometer compound carrying method. The acidic strength of catalysts was measured with the following Hammett indicators, 2,4-dinitrofluorobenzene (H0=-14.52) and p-nitrochlorobenzene (H0=-12.70). Catalytic activity was evaluated with esterification reaction of Acetic Acid and Butanol. Reaction temperature was at 105℃, and reaction time was only 1h. The conversion rate of Acetic Acid was analyzed by a gas chromatograph (GC-14C SHIMADZU in Japan)The experimental results showed that H2SO4 concentration had more influences on catalytic activity than other two factors, calcination temperature and ZrO2 supported content. Since sulfur absorbed on the surface of metal oxides is necessary to the acidity of SO42-/MxOy solid superacid,H2SO4 concentration in impregnation solution is needed enough high. But, it can't be too much high,otherwise, Zirconium sulfate formed on the catalyst surface will be harmful influences on catalytic activity. In researched cover, 0.5mol/L H2SO4 concentration is the most suitable, and the catalyst prepared with this concentration has very strong acidity.The optimum preparation condition is as follows: ZrO2 content 3.5g/g; calcination temperature 600℃, and H2SO4 concentration 0.5mol/L. In the catalyst prepared with above conditions, the acidic strength (H0) of the catalyst is smaller than <-14.52, and

  3. Control and enhancement of the oxygen storage capacity of ceria films by variation of the deposition gas atmosphere during pulsed DC magnetron sputtering

    Eltayeb, Asmaa; Vijayaraghavan, Rajani K.; McCoy, Anthony; Venkatanarayanan, Anita; Yaremchenko, Aleksey A.; Surendran, Rajesh; McGlynn, Enda; Daniels, Stephen


    In this study, nanostructured ceria (CeO2) films are deposited on Si(100) and ITO coated glass substrates by pulsed DC magnetron sputtering using a CeO2 target. The influence on the films of using various gas ambients, such as a high purity Ar and a gas mixture of high purity Ar and O2, in the sputtering chamber during deposition are studied. The film compositions are studied using XPS and SIMS. These spectra show a phase transition from cubic CeO2 to hexagonal Ce2O3 due to the sputtering process. This is related to the transformation of Ce4+ to Ce3+ and indicates a chemically reduced state of CeO2 due to the formation of oxygen vacancies. TGA and electrochemical cyclic voltammetry (CV) studies show that films deposited in an Ar atmosphere have a higher oxygen storage capacity (OSC) compared to films deposited in the presence of O2. CV results specifically show a linear variation with scan rate of the anodic peak currents for both films and the double layer capacitance values for films deposited in Ar/O2 mixed and Ar atmosphere are (1.6 ± 0.2) × 10-4 F and (4.3 ± 0.5) × 10-4 F, respectively. Also, TGA data shows that Ar sputtered samples have a tendency to greater oxygen losses upon reduction compared to the films sputtered in an Ar/O2 mixed atmosphere.

  4. Preparation and Characterization of CeO2-TiO2/SnO2:Sb Films Deposited on Glass Substrates by R.F.Sputtering

    ZHAO Qingnan; DONG Yuhong; NI Jiamiao; WANG Peng; ZHAO Xiujian


    CeO2-TiO2 films and CeO2-TiO2/SnO2:Sb(6 mol%)double films were deposited on glass substrates by radio-frequency magnetron sputtering(R.F.Sputtering),using SnO2:Sb(6 mol%)target,and CeO2-TiO2 targets with different molar ratio of CeO2 to TiO2 (CeO2:TiO2=0:1.0;0.1:0.9;0.2:0.8;0.3:0.7;0.4:0.6;0.5:0.5;0.6:0.4; 0.7:0.3; 0.8:0.2;0.9:0.1;1.0:0).The films are characterized by UV-visible transmission and infrared reflection spectra,scanning electron microscopy(SEM),Raman spectroscopy,X-ray photoelectron spectroscopy(XPS)and X-ray diffraction(XRD),respectively.The obtained results show that the amorphous phases composed of CeO2-TiO2 play an important role in absorbing UV, there are Ce3+,Ce4+ and Ti4+ on the surface of the films;the glass substrates coated with CeO2-TiO2(Ce/Ti=0.5:0.5;0.6:0.4)/SnO2:Sb(6 mol%) double films show high absorbing UV(>99),high visible light transmission(75%)and good infrared reflection films can be used as window glass of buildings,automobile and so on.

  5. Photocatalytic performance of TiO2 catalysts modified by H3PW12O40, ZrO2 and CeO2

    CAI Tiejun; LIAO Yuchao; PENG Zhenshan; LONG Yunfei; WEI Zongyuan; DENG Qian


    The binary composite photo-catalysts CeO2/TiO2, ZrO2/TiO2 and the ternary composite photo-catalysts H3PW12O40-CeO2/TiO2,H2PW12O40-ZrO2/TiO2 were prepared by sol-gel method. The catalysts were characterized by thermogravimetric-differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The photocatalyfic elimination of methanol was used as model reaction to evaluate the photocatalytic activity of the composite catalysts under ultraviolet light irradiation. The effects of doped content, activation temperature, time, initial concentration of methanol and gas flow rate on the catalytic activity were investigated. The results showed that after doping a certain amount of CeO2 and ZrO2, crystaniTation process of TiO2 was restrained, particles of catalysts are smaller and more uniform. Doping ZrO2 not only significantly improved the catalytic activity, but also increased thermal stability. Doping H3PW12O40 also enhanced the catalytic activity. The catalytic activities of binary and ternary composite photocatalysts were significantly higher than tin-doped TiO2. The dynamics law of photocatalytic reaction over the binary CeO2/TiO2 and ZrO2/TiO2 catalysts has been studied. The activation energy 15.627 and 15.631 kJ/mol and pre-exponential factors 0.5176 and 0.9899 s-1 over each corresponding catalyst were obtained. This reaction accords to the first order dynamics law.

  6. Grain Size and Wettability of TiO2/SiO2 Photocatalytic Composite Thin Films


    The uniform transparent TiO2/SiO2 photocatalytic composite thin films are prepared by sol-gel method on the soda lime glass substrates, and characterized by UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), BET surface area, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that the addition of SiO2 to TiO2 thin films can suppress the grain growth of TiO2 crystal, increase the hydroxyl content on the surface of TiO2 films, lower the contact angle for water on TiO2 films and enhance the hydrophilic property of TiO2 films. The super-hydrophilic TiO2/SiO2 photocatalytic composite thin films with the contact angle of 0-° are obtained by the addition of 10%-20% SiO2 in mole fraction.

  7. Laboratory Study of O2(b1Σ g+, υ = 1) Collisional Removal at Thermospheric Temperatures

    Wouters, E. R.; Pejaković, D. A.; Phillips, K. E.; Kalogerakis, K. S.


    In the Earth's thermosphere, energy transfer from O(1D) to O2 generates oxygen molecules in the υ = 0 and 1 levels of the O2(b1Σg+) state. The emissions in the O2(b1Σ g+ - X3Σ g-) system (Atmospheric Band) present a major component of the Earth's airglow. Interpretation of the measured intensities of O2 Atmospheric Band emissions can yield altitude profiles of oxygen atom density and local temperature in the lower thermosphere. To achieve this goal accurate laboratory measurements of the collisional removal rate coefficients of O2(b, υ = 1) and their temperature dependence are essential. Atmospheric observations suggest that the relevant colliders for the removal of O2(b, υ = 1) in the lower thermosphere are O2 and O(3P). We report measurements of the rate coefficients for the collisional removal of O2(b, υ = 1) by O2, N2, and CO2, at temperatures in the range 300--1000 K. A state-specific two-laser technique is used, in which the visible output of the first laser directly excites O2 to O2(b, υ = 1), and the ultraviolet output of the second laser probes the O2(b, υ = 1) population by resonantly enhanced multiphoton ionization via the υ= 4 level of the d1Π g Rydberg state. The temporal evolution of the O2(b, υ = 1) population is monitored by varying the time delay between the two laser pulses. The rate coefficient of the collisional removal of O2(b, υ = 1) by O2 increases monotonically with temperature from about 1.5 x 10-11 cm3 s-1 to about 6*E-11 cm3 s-1 in the range 300--1000 K. Experiments with colliders N2 and CO2 determine the upper limits for the removal rate coefficients of O2(b, υ = 1) by N2 and CO2 to be 2 orders of magnitude smaller. This work extends previous studies of O2(b, υ = 1) at room and low temperatures.1,2 We are currently planning experiments to investigate the collisional removal of O2(b, υ = 1) by O atoms. This study was supported by the NSF's Grant ATM-0209229. The participation of K. Phillips in this project was funded by

  8. C-V and DLTS studies of radiation induced Si-SiO2 interface defects

    Capan, I.; Janicki, V.; Jacimovic, R.; Pivac, B.


    Interface traps at the Si-SiO2 interface have been and will be an important performance limit in many (future) semiconductor devices. In this paper, we present a study of fast neutron radiation induced changes in the density of Si-SiO2 interface-related defects. Interface related defects (Pb centers) are detected before and upon the irradiation. The density of interface-related defects is increasing with the fast neutron fluence.

  9. Effect of TiO2 particle size on the performance of viologen-anchored TiO2 electrochromic device.

    Kim, Yong Joo; Jeong, Hyun Ki; Seo, Jung Kyu; Chai, Seung Yong; Kim, Young Seok; Lim, Goo Il; Cho, Min Ho; Lee, Ik-Mo; Choi, Young S; Lee, Wan In


    The effect of TiO2 particle size on the performance of the electrochromic device (ECD) has been investigated in this work by applying the TiO2 nanoparticles in 7, 15, and 30 nm sizes. The phosphonated viologen, bis(2-phosphonoethyl)-4,4'-bipyridinium dibromide, was anchored on the TiO2 surfaces for the construction of ECD. The ECD derived from 7 nm-sized TiO2 demonstrated the highest contrast ratio with high optical transparency, whereas it showed the slowest switching response. The enhancement of coloration efficiency with decrease of TiO2 particle size is due to the increased amount of the anchored viologen on TiO2 electrode. On the other hand, the relatively slower switching response would be caused by the difficulty of diffusion for the electrolytes and counter-ions through the small pores of the nanocrystalline TiO2 electrode derived from 7 nm-sized nanoparticles.

  10. Dose-Dependent Effects of CeO2 on Microstructure and Antibacterial Property of Plasma-Sprayed TiO2 Coatings for Orthopedic Application

    Zhao, Xiaobing; Liu, Gaopeng; Zheng, Hai; Cao, Huiliang; Liu, Xuanyong


    Titanium and its alloys have been used extensively for orthopedic and dental implants. Although these devices have achieved high rates of success, two major complications may be encountered: the lack of osseointegration and the biomaterial-related infection. Accordingly, cerium oxide (CeO2)-doped titanium oxide (TiO2) materials were coated on titanium by an atmospheric plasma spraying (APS) technique. The phase structures, morphologies, and surface chemical states of the obtained coatings were characterized by x-ray diffraction, scanning electron microscopy, and x-ray photoelectron spectroscopy techniques. The in vitro antibacterial and cytocompatibility of the materials were studied with Staphylococcus aureus ( S. aureus, ATCC25923) and osteoblast precursor cell line MC3T3-E1. The results indicated that the addition of CeO2 shifts slightly the diffraction peaks of TiO2 matrix to low angles but does not change its rutile phase structure. In addition, the CeO2/TiO2 composite coatings possess dose-dependent corrosion resistance and antimicrobial properties. And doping of 10 wt.% CeO2 exhibits the highest activity against S. aureus, improved corrosion resistance, and competitive cytocompatibility, which argues a promising option for balancing the osteogenetic and antibacterial properties of titanium implants.

  11. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells.

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao


    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time.


    Y. J. O. Asencios

    Full Text Available Abstract In this work the behavior of NiO-PrO2-ZrO2 catalysts containing various nickel loadings was evaluated in the partial oxidation of methane and oxidative-reforming reactions of methane. The catalysts were characterized by X-Ray Diffraction Analysis (in situ-XRD, Temperature Programmed Reduction (H2-TPR, Scanning Electron Microscopy (SEM/EDX and Adsorption-Desorption of nitrogen (BET area. The reactions were carried out at 750 °C and 1 atm for 5 hours. The catalysts were studied with different nickel content: 0, 5, 10 and 15% (related to total weight of catalyst, wt%. In both reactions, the catalyst containing the mixture of the three oxides (NiO/PrO2/ZrO2 with 15% nickel (15NiPrZr catalyst showed the best activity for the conversion of the reactants into Syngas and showed high selectivity for H2 and CO. The results suggest that the promoter PrO2 and the Niº centers are in a good proportion in the catalyst with 15% Ni. Our results showed that low nickel concentrations in the catalyst led to high metallic dispersion; however, very low nickel concentrations did not favor the methane transformation into Syngas. The catalyst containing only NiO/ZrO2 in the mixture was not sufficient for the catalysis. The presence of the promoter PrO2 was very important for the catalysis of the POM.

  13. Nanosized TiO2-induced reproductive system dysfunction and its mechanism in female mice.

    Xiaoyang Zhao

    Full Text Available Recent studies have demonstrated nanosized titanium dioxide (nano-TiO