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We have studied the kinetics of the transitions between the Fe2O3 and Fe3O4 phases as thin epi layers (~2.5 nm) on Al2O3 (001) substrates using time-resolved reflection high energy electron diffraction. The different iron oxide phases were identified using a combination of in-situ and ex-situ characterizations. The transition from an α-Fe2O3 (001) epilayer to a Fe3O4 (111) epilayer through thermal reduction was found to be determined by the Fe-O bonding energy, resulting in a long time scale. The oxidation at high temperature converts a Fe3O4 (111) epilayer to an α-Fe2O3 (001) epilayer quickly; at low temperature, a γ-Fe2O3 (111) epilayer was slowly generated instead. By repeating the deposition/thermal reduction processes, a thicker Fe3O4 (111) film was obtained, which exhibit high crystallinity and moderate magnetic coercivity. [ABSTRACT FROM AUTHOR]

We outline a modeling study of an extrinsic semiconductor interface formed from the interaction of nanostructured metal oxide decorated porous silicon and used for sensing gas phase analytes. We consider simple conductometric sensors that operate at room temperature and atmospheric pressure. Nanostructured metal oxide deposition provides a matrix of responses to various analytes, facilitating the extraction of ambient gas concentrations from sensor responses. The sensors are simulated in four stages with an emphasis to the continual improvement of the modeling effort. Stage 1 focuses solely on the diffusion mechanics of an analyte gas into and out of a micro/nanoporous interface and the observed linear response at low concentrations. Stage 2 focuses on the non-linearity resulting primarily from the quenching of sensor response at higher concentrations and introduces an absorption response mechanism. Here, stage 3 demonstrates how the consideration of charge carrier density leads to the development of a new Fermi-distribution based response mechanism. Stage 4 establishes a combined absorption-Fermi-distribution response mechanism. [ABSTRACT FROM AUTHOR]

An alternative multi-frequency inversion-charge pumping (MFICP) technique was developed to directly separate the inversion charge density (Ninv) from the trapped charge density in high-k/ InGaAs metal-oxide-semiconductor field-effect transistors (MOSFETs). This approach relies on the fitting of the frequency response of border traps, obtained from inversion-charge pumping measurements performed over a wide range of frequencies at room temperature on a single MOSFET, using a modified charge trapping model. The obtained model yielded the capture time constant and density of border traps located at energy levels aligned with the InGaAs conduction band. Moreover, the combination of MFICP and pulsed Id-Vg measurements enabled an accurate effective mobility vs Ninv extraction and analysis. The data obtained using the MFICP approach are consistent with the most recent reports on high-k/InGaAs. [ABSTRACT FROM AUTHOR]

Purpose: To determine the impact of long-term storage on adhesion between titanium and zirconia using resin cements. Materials and Methods: Titanium grade 4 blocks were adhesively fixed onto zirconia disks with four resin cements: Panavia F 2.0 (Kuraray Europe), GC G-Cem (GC Europe), RelyX Unicem (3M ESPE), and SmartCem 2 (Dentsply DeguDent). Shear bond strength was determined after storage in a water bath for 24 h, 16, 90, and 150 days at 37°C, and after 6000 cycles between 5°C and 55°C. Fracture behavior was evaluated using scanning electron microscopy. Results: After storage for at least 90 days and after thermocycling, GC G-Cem (16.9 MPa and 15.1 MPa, respectively) and RelyX Unicem (10.8 MPa and 15.7 MPa, respectively) achieved higher shear bond strength compared to SmartCem 2 (7.1 MPa and 4.0 MPa, respectively) and Panavia F2 (4.1 MPa and 7.4 MPa, respectively). At day 150, GC G-Cem and RelyX Unicem caused exclusively mixed fractures. SmartCem 2 and Panavia F2 showed adhesive fractures in one-third of the cases; all other fractures were of mixed type. After 24 h (GC G-Cem: 26.0, RelyX Unicem: 20.5 MPa, SmartCem 2: 16.1 MPa, Panavia F2: 23.6 MPa) and 16 days (GC G-Cem: 12.8, RelyX Unicem: 14.2 MPa, SmartCem 2: 9.8 MPa, Panavia F2: 14.7 MPa) of storage, shear bond strength was similar among the four cements. Conclusion: Long-term storage and thermocycling differentially affects the bonding of resin cement between titanium and zirconia. [ABSTRACT FROM AUTHOR]

We report here a comparative study of the theoretically calculated electronic structures of cubic BaSnO3 and cubic Ba(M0.5Sn0.5)O3 with M=Ti, V, Cr, Zr, Ce, and Pb, the tetravalent metal ions, to explore their possible efficacy for the visible light photocatalysis and solar energy conversion. We performed the calculations within the framework of density functional theory by using WIEN97 code. The 3d orbitals of Ti, V, and Cr, 4d of Zr, and the 4f and 6s orbitals of Ce and Pb, respectively, contributed to the bottom of the conduction band for narrowing of the band gap of cubic BaSnO3. Calculation of the frequency dependent absorption coefficient I(ω) of Ba(M0.5Sn0.5)O3 indicated that among the transition metal (Ti, V, Cr, and Zr) doped systems, Cr has comparatively higher visible absorption efficiency, whereas among other metal (Pb and Ce) systems, Pb showed significant absorption coefficient in low energy range (E<=2 eV). The comparison of the computed optical absorption coefficients shows that the Ba(M0.5Sn0.5)O3 systems can be arranged with respect to M as (i) Cr>V>Ti among first row transition metals and (ii) Pb>Ce>Zr among rest of tetravalent metals, in decreasing order of photoresponse towards low energy photons (E<=2.5 eV). [ABSTRACT FROM AUTHOR]

Due to its advantageous properties, titanium dioxide has been one of the most researched metal oxides and extensively used in various fields, including photocatalysis. Metal (platinum) and non‐metal (sulfur, nitrogen) doped titania thin films were prepared via a particular sol‐gel synthesis, coated onto object glasses and then thermally treated to promote TiO2 crystallization. Until now, photocatalytic activity of titania thin films has mostly been measured with different spectroscopic techniques (IR, UV‐Vis and fluorescence spectroscopy). The aim of the work presented in this article was to find alternative, non‐spectroscopic methods for photocatalytic activity measurements. To achieve this, we performed in‐situ UV‐Vis absorption spectra, conductivity (κ) and pH measurements during photocatalytic degradation of Plasmocorinth B under UV light illumination. Results have shown that there exists a linear correlation between changes in conductivity (Δκ), pH (ΔpH) values and photocatalytic activity of the samples, measured with UV‐Vis spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract Metal-oxide interfaces are of great importance in catalytic applications since each material can provide a distinct functionality that is necessary for efficient catalysis in complex reaction pathways. Moreover, the synergy between two materials can yield properties that exceed the superposition of single sites. While interfaces between metals and metal oxides can play a key role in the reactivity of traditional supported catalysts, significant attention has recently been focused on using "inverted" oxide/metal catalysts to prepare catalytic interfaces with unique properties. In the inverted systems, metal surfaces or nanoparticles are covered by oxide layers ranging from submonolayer patches to continuous films with thickness at the nanometer scale. Inverse catalysts provide an alternative approach for catalyst design that emphasizes control over interfacial sites, including inverted model catalysts that provide an important tool for elucidation of mechanisms of interfacial catalytic reactions and oxide-coated metal nanoparticles that can yield improved stability, activity and selectivity for practical catalysts. This review begins by providing a summary of recent progress in the use of inverted model catalysts in surface science studies, where oxides are usually deposited onto the surface of metal single crystals under ultra-high vacuum conditions. Surface-level studies of inverse systems have yielded key insights into interfacial catalysis and facilitated active site identification for important reactions such as CO oxidation, the water-gas shift reaction, and CO 2 reduction using well-defined model systems, informing strategies for designing improved technical catalysts. We then expand the scope of inverted catalysts, using the "inverse" strategy for preparation of higher-surface area practical catalysts, chiefly through the deposition of metal oxide films or particles onto metal nanoparticles. The synthesis techniques include encapsulation of metal nanoparticles within porous oxide shells to generate core-shell type catalysts using wet chemical techniques, the application of oxide overcoat layers through atomic layer deposition or similar techniques, and spontaneous formation of metal oxide coatings from more conventional catalyst geometries under reaction or pretreatment conditions. Oxide-coated metal nanoparticles have been applied for improvement of catalyst stability, control over transport or binding to active sites, direct modification of the active site structure, and formation of bifunctional sites. Following a survey of recent studies in each of these areas, future directions of inverted catalytic systems are discussed. [ABSTRACT FROM AUTHOR]

ABSTRACT: Electrically conducting, water‐soluble fluorescent copolymer nanocomposites were synthesized by a solution polymerization method under different experimental conditions in the presence of CuO and V2O5 nanoparticles. The prepared copolymer nanocomposites were characterized with analytical tools, including Fourier transform infrared spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, and fluorescence emission spectroscopy. The order of copolymerization was determined on the basis of the UV–vis absorption spectra and fluorescence emission spectra. The copolymer–CuO nanocomposite system exhibited the highest electrical conductivity. The scanning electron microscopy image showed the presence of more CuO nanoparticles on the surface of the copolymer. Furthermore, the catalytic activity of the copolymer nanocomposites was tested for the reduction of p‐nitrophenol. All three types of polymer systems exhibited almost the same apparent rate constant values. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46469. [ABSTRACT FROM AUTHOR]

The preparation of metal oxide particles, such as MgO, NiO, and ZnO, exposing polar facets via the decomposition of suitable precursors in air, molten salts, ionic liquids, or other media has been reported; however, the main driving force(s) and factors that determine their morphology have largely remained elusive. For instance, the adsorption of ions within a molten medium on a growing oxide surface has been proposed to stabilize MgO{111} facets by the so-called molten salt route (MSR). In this article, we examine the thermal decomposition of MgO precursors to assess the influence of precursor decomposition pathways, including the physical state of the reaction intermediates and the possibility of dissolution-recrystallization processes in the formation of octahedral MgO particles. We found that solid-to-solid conversions and recrystallizations in molten nitrates or chlorides are usually incapable of producing well-defined MgO{111} facets, indicating that ion adsorption on MgO may not be the main morphological driving force. Here, we show for Mg(NO3)2·6H2O, the most suited MgO(111) precursor, that its decomposition trajectory is crucial in determining the exposure of {111} facets. The decomposition trajectory may be regulated by using controlled heating profiles, regulated atmospheres, or by incorporating particular salts in the reaction mixture. Our findings indicate that, for neat Mg(NO3)2·6H2O decomposition in air, MgO{111} facets are promoted via magnesium nitrate intermediates in the molten state and in the presence of residual water. These conditions can be achieved by heating the hexahydrate precursor at high rates. On the contrary, decomposition of anhydrous Mg(NO3)2 results in ill-defined MgO morphologies. In a molten NaNO3:KNO3 medium, the formation of liquid eutectic mixtures facilitate H2O retention and ionic mobility, from which well-defined octahedral MgO crystals form, thereby emphasizing the crucial role of water in Mg(II)-nitrate systems. In a NaCl:KCl ionic medium, precursor decomposition occurs via a K3NaMgCl6 intermediate, which melts before converting to the oxide. MgO(111) forms under local melting of the intermediate (before NaCl:KCl melts) and when the H2O content is negligible. In summary, the formation of polar MgO(111) particles is facilitated in molten salt media when MgO is generated via a liquid-to-solid reaction (with intermediates in the molten state). The presence of residual water and ions impact MgO(111) crystallization in ways that still remain elusive, but are not necessarily governed by adsorption-stabilization processes. [ABSTRACT FROM AUTHOR]

The present work investigates the structural and optical properties of rare earth copper oxides (RE 2 CuO 4 ; RE: Pr, Nd, Sm and Gd) and mixed metal oxides (CeO 2 /CuO) synthesized by template free hydrothermal method. RE 2 CuO 4 were obtained after calcination at 700 °C, temperature appreciably lower than that employed in the conventional ceramic technique. The phase composition, particle size, thermal stability, morphology, elemental distribution and optical properties of the products were elucidated by various analytical techniques. X-ray diffraction patterns revealed tetragonal phase of products except for Cerium. Oval shaped particles forming agglomerates, and homogenous distribution of elements in the sample was evidenced by electron microscopy and elemental mapping. The optical band gap of the rare earth copper oxides is observed to be in the range of 0.79–1.36 eV, while CeO 2 /CuO shows absorption band in the UV region and a band gap of 3.24 eV. ESR analysis shows the paramagnetic behaviour of the samples. [ABSTRACT FROM AUTHOR]

A novel adsorbent, Fe‐Mn‐Zr metal oxide nanocomposite was synthesized and investigated for removal of methyl orange (MO) and eosin yellow (EY) dyes from binary dye solution. The magnetic nanocomposite has shown surface area of 143.01 m2/g and saturation magnetization of 15.29 emu/g. Optimization was carried out via response surface methodology (RSM) for optimizing process variables, and optimum dye removal of 99.26% and 99.55% were obtained for MO and EY dye, respectively with contact time 62 min, adsorbent dose 0.45 g/l, initial MO concentration 11.0 mg/l, and initial EY concentration 25.0 mg/l. A feed forward back propagation neural network model has shown better prediction ability than RSM model for predicting MO and EY dye removal (%). Adsorption process strictly follows Langmuir isotherm model, and enhanced adsorption capacities of 196.07 and 175.43 mg/g were observed for MO and EY dye, respectively due to synergistic effects of physicochemical properties of trimetal oxides. Surface adsorption and pore diffusions are the mechanisms involved in the adsorption as revealed from kinetic studies. [ABSTRACT FROM AUTHOR]

Supported Pt─Au bimetal nanocatalysts have been prepared by an in situ reduction method followed by calcination in air and reduction in H2 atmosphere. The catalysts exhibit a typical yolk‐shell construction composed of a moveable magnetic Fe core and metal oxides shells decorated with Pt─Au nanoparticles. The structure of the bimetal nanocatalysts was characterized in detail by TEM, XRD, XPS, and N2 physical adsorption and the catalytic activity of the nanocatalysts was studied by the catalytic reduction of 4‐nitrophenol to 4‐nitrophenol. It is found that the bimetal nanocatalysts composed with the different metallic oxides (TiO2 and ZrO2) exhibited the comparable Pt─Au particles size (~10 nm). However, the content of Pt─Au nanoparticles was varied with the metallic oxides support. Pt─Au nanoparticles deposited uniformly on TiO2 with higher loadings, however the nanoparticles on ZrO2 exhibited remarkably lower content, which should be attributed to the abundant hydroxyl on TiO2 surface that served as the deposition site for Pt─Au nanoparticles. The result of the reduction reaction indicated that incorporation of TiO2 in the bimetal Pt─Au nanocatalyst could significantly improve the catalytic activity as compared with ZrO2 and m‐SiO2. A possible mechanism was proposed to explain the synergistic effect in the supported Pt─Au bimetal nanocatalysts. [ABSTRACT FROM AUTHOR]

We successfully synthesized a novel viologen derivative (1,1′-bis(3-fluoro-4-(trifluoromethyl)phenyl)-4,4′-bipyridinium bis(trifluoromethylsulfonyl)imide, TFMFPhV(TFSI) 2 ) exhibiting a green-colored state. We selected cyanophenyl viologen (CNPhV 2+ ), a conventional electrochromic (EC) chromophore with a green color indication, to compare EC performance. Ion gels consisting of poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF- co -HFP) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]) were employed as a solid-state electrolyte for EC devices (ECDs). In comparison to CNPhV 2+ -containing devices, the ECDs with TFMFPhV 2+ showed higher transmittance contrast, larger coloration efficiency, faster coloration and bleaching responses, and better coloration/bleaching operational stability. Cyclic voltammetry revealed that the more stable redox behavior of TFMFPhV 2+ is the origin of the outstanding ECD performance. [ABSTRACT FROM AUTHOR]

This work reports the morphological, electrical and luminescent characteristics of Light Emitting Capacitors (LECs) composed by Silicon Rich Oxide (SRO) multilayers. These multilayers alternate four conductive SRO layers (silicon excess of 12 or 14 at%) with three light emitting SRO layers (silicon excess of 6 at%). Transmission electron microscopy reveals that multilayers present well-defined nanoscale layers and interfaces in the multilayers. Furthermore, it is found that layers with high silicon content induce the formation of bigger silicon nanocrystals in the emitting layers as compared to single layers. When LECs are biased through a current-voltage measurement, an electroforming effect, where the current increases abruptly, is observed. This electroforming effect produces conductive trajectories arrays with high silicon content in the conductive SRO layers. These conductive paths allow to the LECs achieve higher current values with lower voltages preserving the luminescent characteristics of the emitting SRO layers. Consequently, it is demonstrated that silicon nanocrystals also act as sources of electro-hole pairs increasing the radiative recombination in the SRO defects. LECs that combine conductive and light emitting SRO films in a multilayered structure allow to enhance brightness and electrical characteristics compared to single layers. Depending on the conductive SRO layer preferential electroluminescence is produced in red or blue region. [ABSTRACT FROM AUTHOR]

We analyze the electrical conductivity of polycrystalline semiconductor solids due to the presence of Schottky-type potential barriers formed at intergrains. The density of charged dopants along the grains is usually considered constant leading to parabolic intergranular potential barriers. If temperature is high enough to allow sufficiently mobility to the dopants, their resulting equilibrium distribution is far from constant leading to potential barriers that show a strong non-parabolic character. Implications for the electrical conductivity and then on the sensitivity to barrier height and sample doping in metal oxide gas sensors are discussed. [ABSTRACT FROM AUTHOR]

This article reports on Li self-diffusion in lithium containing metal oxide compounds. Case studies on LiNbO3, Li3NbO4, LiTaO3, LiAlO2, and LiGaO2 are presented. The focus is on slow diffusion processes on the nanometer scale investigated by macroscopic tracer methods (secondary ion mass spectrometry, neutron reflectometry) and microscopic methods (nuclear magnetic resonance spectroscopy, conductivity spectroscopy) in comparison. Special focus is on the influence of structural disorder on diffusion. [ABSTRACT FROM AUTHOR]

To clarify the relationship between the type of the oxide support and the activity of the gold-doped oxide clusters toward H2 oxidation, a suitable closed-shell system AuV2O5+ is chosen to have a comparative study with AuCe2O4+, the first closed-shell cluster that is reactive toward H2 oxidation. The reaction of AuV2O5+ with H2 was characterized by mass spectrometry and density functional theory calculations. The AuV2O5+ cluster is reactive toward H2 leading to the major product of V2O5H2+ (+ Au), whereas the product of AuV2O4+ (+ H2O) is completely absent in the experiment. This is in sharp contrast with the similar reaction system of AuCe2O4+ with H2, in which the formation of H2O was experimentally evidenced. Theoretical calculations revealed that the distinct reaction behaviors between AuV2O5+ and AuCe2O4+ can be attributed to the gold-metal bond strength, which plays an important role in anchoring the gold atom. The weaker Au-V bond promotes the evaporation of Au, which has a negative effect on the total oxidation of H2 to H2O. This comparative study provides molecular-level mechanisms to understand the important roles of the gold-metal bond in the oxidation of hydrogen molecule over metal oxide supports. [ABSTRACT FROM AUTHOR]

Gas insulated substation generates very fast transient overvoltages (VFTOs) in power systems because of disconnector switching operations. The present design of metal-oxide arrester may not be effective against these VFTs and so the arrester fails to operate under VFTO. At this point, it becomes essential to improve the electrical behaviour of arrester. Some of the possible measures for improving the electrical behaviour of arrester blocks are the procurement of higher-voltage gradient, reduction of arrester capacitive effect and reduction in the time lag between residual voltage and current surge. With this background, the microstructural and electrical parameters of arrester block are modified by doping scandium trioxide with basic composition and the samples are prepared using different sintering processes. Subsequently, the voltage gradient, capacitance and the time lag are found for the prepared samples. The performance of new arrester blocks are investigated against VFTO and the results are compared with conventional arrester blocks. From that, it is perceived that the new arrester samples have improved parameters and might be used for protection of power system against VFTO. [ABSTRACT FROM AUTHOR]

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

Electrospinning is the most facile and highly versatile approach to produce 1D polymeric, inorganic, and hybrid nanomaterials with a small diameter, controllable dimensions, and designed architectures. In particular, with large surface area, high porosity, low density, good directionality, and tunable composition, electrospun nanofibers and mats are regarded as ideal candidates for various kinds of electrochemical energy storage devices such as supercapacitors (SCs). In this review, the recent progress in electrospun electrode materials for SCs is presented, covering the architecture design and their electrochemical performance. After a brief introduction about SCs, the basic principles of the electrospinning technique are discussed. Following, attention is paid to the discussion of various electrospun nanofibers and mats including 1D carbons, metal oxides, metal sulfides, metal nitrides, conducting polymers and composite nanomaterials with various types of architectures as electrodes for SCs. The relationship between the composition, architecture, and the electrochemical performance is discussed in detail. Finally, some challenges and perspectives of future research of the electrospun nanofibers and mats for high performance SCs are highlighted. It is anticipated that this review would provide the researchers some inspiration for constructing new types of energy storage devices. [ABSTRACT FROM AUTHOR]

The thin films of iron oxides including magnetite (Fe3O4) and hematite (α-Fe2O3) have many important applications. Both forms of oxide can occur naturally during film growth by iron deposition under various oxidation environments; an important issue is to understand and control the process resulting in a single-phase film. We have performed the in-situ -time studies using X-ray diffraction of such film growth on sapphire (001) under pure ozone by monitoring the (00L) rod. Stable magnetite growth can be maintained at growth temperatures below 600 °C up to a certain critical film thickness, beyond which the growth becomes hematite. The results demonstrate the importance of interfacial interaction in stabilizing the magnetite phase. [ABSTRACT FROM AUTHOR]

By simply changing the oxide support, the selectivity of a metal-oxide catalysts can be tuned. For the CO2 hydrogenation over PtCo bimetallic catalysts supported on different reducible oxides (CeO2, ZrO2, and TiO2), replacing a TiO2 support by CeO2 or ZrO2 selectively strengthens the binding of C,O-bound and O-bound species at the PtCo-oxide interface, leading to a different product selectivity. These results reveal mechanistic insights into how the catalytic performance of metal-oxide catalysts can be fine-tuned. [ABSTRACT FROM AUTHOR]

Hyperspectral sensors generally acquire images in thespectral range in more than one hundred contiguous narrow channels with a (deca)metric spatial resolution. Each pixel of the image is thus associated with a continuous spectrum which can be used to identify or map surface minerals. The most powerful algorithms (e.g., USGS (United States Geological Survey) Tetracorder) run with a standardized spectral library, are often supervised and require some expert knowledge. In this paper, we present an original method for mineral identification and mapping. Its originality lies in its fully automatic functioning for the full spectral range, from initialization using spectral derivatives, to spectral deconvolution and mineral identification, with a global approach. The modelling combines exponential Gaussians, a continuum including the fundamental water absorption atand deals with overfitting to keep only the relevant Gaussians. We tested the method in the SWIR (Short-Wave InfraRed,) and for 14 minerals representative of industrial environments (e.g., quarries, mines, industries). More than 98% of the simulated spectra were correctly identified. When applied to two AVIRIS (Airborne Visible/InfraRed Imaging Spectrometer) images, results were consistent with ground truth data. The method could be improved by extending it to the VNIR (Visible and Near-InfraRed,) spectral range to include iron oxides and by managing spectral mixtures. [ABSTRACT FROM PUBLISHER]

A new concept that comprises both time- and lateral-resolved X-ray absorption fine-structure information simultaneously in a single shot is presented. This uncomplicated set-up was tested at the BAMline at BESSY-II (Berlin, Germany). The primary broadband beam was generated by a double multilayer monochromator. The transmitted beam through the sample is diffracted by a convexly bent Si (111) crystal, producing a divergent beam. This, in turn, is collected by either an energy-sensitive area detector, the so-called color X-ray camera, or by an area-sensitive detector based on a CCD camera, in θ-2θ geometry. The first tests were performed with thin metal foils and some iron oxide mixtures. A time resolution of lower than 1 s together with a spatial resolution in one dimension of at least 50 μm is achieved. [ABSTRACT FROM AUTHOR]

Quaternary blend hybrid organic solar cells enjoy both an increased light absorption range and an easy method to fabricate because of the simple structure. In this study effects of mixing inorganic metal oxides (ZnO and TiO 2 ) nanoparticles to the active layer of organic photovoltaics devices were investigated. The active layer primarily consists of various ratios of electron donor poly (3-hexylthiophene) (P3HT) and an electron acceptor [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) together with nanostructured ZnO and TiO 2 dispersed in chlorobenzene (CB) and 1,2-dichlorobenzene (DCB). The ratio of PCBM to nanoparticles was varied keeping the ratio of P3HT to acceptor material constant. Mixing of nanoparticle plays a significant role in the resulting power conversion efficiency (PCE) of the devices. An increased PCE for ZnO/TiO 2 doped devices can be attributed to increased absorption in the visible region and enhanced charge collection due to the percolation networks formed by metal oxides nanoparticles. [ABSTRACT FROM AUTHOR]

The extent to which point defects affect the local chemical reactivity and electronic properties of an oxide surface was evaluated with picometer resolution in all three spatial dimensions using simultaneous atomic force/scanning tunneling microscopy measurements performed on the (110) face of rutile TiO2. Oxygen atoms were imaged as protrusions in both data channels, corresponding to a rarely observed imaging mode for this prototypical metal oxide surface. Three-dimensional spectroscopy of interaction forces and tunneling currents was performed on individual surface and subsurface defects as a function of tip-sample distance. An interstitial defect assigned to a subsurface hydrogen atom is found to have a distinct effect on the local density of electronic states on the surface, but no detectable influence on the tip-sample interaction force. Meanwhile, spectroscopic data acquired on an oxygen vacancy highlight the role of the probe tip in chemical reactivity measurements. [ABSTRACT FROM AUTHOR]

Pure and highly crystalline γ-Fe2O3 nanocrystals (NCs) are obtained when hydrolysis and oxidation of a FeII organometallic precursor are performed in successive steps. Their synthesis in pure alkylamine leads to NCs of about 6 nm. In aqueous solutions of poly(vinyl)pyrrolidone, such pristine NCs form aggregates of about 150 nm that exhibit a high transversal relaxivity (r2=466 mm-1 s-1) about four times higher than that of a commercial Feridex magnetic resonance imaging (MRI) contrast agent. Consequently, they provide a significant decrease in the NMR signal at very short echo time (8 ms), which is of paramount importance in clinical practice because of the reduced duration of MRI measurements. [ABSTRACT FROM AUTHOR]

Active carbon (AC) is modified with nickel oxide (NiO) and inorganic metal oxide (LaNiO) to synthesize the AC composites using a simple method. The different nanostructures of the obtained AC composites are investigated to achieve high specific capacitance and conductivity. The obtained composites are characterized via scanning electron microscopy, X-ray diffraction, high-resolution transmission electron microscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy. After two-time repeated immersion and heat treatment, the electrode material exhibits an AC-based mesoporous nanostructure. The corresponding resistance of the synthesized AC@NiO composite is 2.55 Ω, which is lower than that of pure AC (5.94 Ω). The CV results are obtained within a stable potential window of −0.9 to 0.9 V in 7 M KOH aqueous solution. The highest specific capacitance of the AC@NiO composite with LaNiO is 652.19 F g at the scan rate of 1 mV s. [ABSTRACT FROM AUTHOR]

Large range of catalytic systems can be obtained from metal fluorides and oxide hydroxide fluorides prepared by soft chemistry due to various properties, especially high specific surface area and tunable acid–base properties. This article highlights the promising properties of these systems for many heterogeneous catalytic processes which extends the catalogue of solid heterogeneous catalysts and supports for future industrial applications. [ABSTRACT FROM AUTHOR]

Iron is the most abundant nutritionally essential transition metal found in the human body. It plays important roles in various biological processes such as oxygen delivery, electron transport, enzymatic reactions and DNA synthesis and repair. However, iron can also catalyze the production of free radicals, which are linked to quite a few diseases such as cancer, neurodegenerative diseases, and cardiovascular diseases. Both iron deficiency and iron overload are related to various health problems. Thus, precisely monitoring iron ions (Fe2+ and Fe3+) in biological systems is important in understanding the detailed biological functions of iron and its trafficking pathways. However, effective tools for monitoring labile Fe2+ in biological systems have not yet been established. Reported herein are turn on, reaction-based coumarin and rhodamine-linked nitroxide probes (Cou-T and Rh-T) for selective detection of Fe2+ in solution and in living cells. Rh-T displayed a unique change in the EPR signal as well as enhancement of the fluorescence signal resulting from a specific redox reaction between the probe and Fe2+. The turn-on fluorescence response towards Fe2+ allows the subcellular imaging of endogenous Fe2+ as well as imaging under conditions of external iron supplementation or depletion, with a labile Fe2+ pool located in the mitochondria of human fibroblast primary cells. The detection and mechanism were verified by the magnetic properties of the probe via electron paramagnetic resonance (EPR) spectroscopy in solution and in cells. [ABSTRACT FROM AUTHOR]

We present a straightforward method for accurate and precise U/Pb dating of baddeleyite using quadrupole LA-ICP-MS. To establish the validity of our ICP-MS data we used FC-4b baddeleyite from the Duluth complex as external standard, whereas baddeleyite from the Phalaborwa (South Africa) and the Sorkka (SW Finland) intrusions were treated as unknowns. The analytical protocol includes the use of a matrix matched standard, which allows for an accurate downhole-fractionation and laser-induced interelement fractionation correction. The quadrupole ICP-MS results for the Phalaborwa and Sorkka samples analyzed are accurate within error of the published ID-TIMS U/Pb ages and with a precision of 0.3–0.7% (2σ) from concordia ages of ten to twenty analyses per sample. No orientation effects were observed. [ABSTRACT FROM AUTHOR]

Single crystalline YBa2Cu3O7-δ (YBCO) thin films were grown by pulsed laser deposition in order to probe the oxygen deficiency δ using a mono-energetic positron beam. The sample set covered a large range of δ (0.191<δ<0.791) yielding a variation of the critical temperature T c between 25 and 90K. We found a linear correlation between the Doppler broadening of the positron electron annihilation line and δ determined by X-ray diffraction. Ab-initio calculations have been performed in order to exclude the presence of Y vacancies and to ensure the negligible influence of potentially present Ba or Cu vacancies to the found correlation. Moreover, scanning with the positron beam allowed us to analyze the spatial variation of δ, which was found to fluctuate with a standard deviation of up to 0.079(5) within a single YBCO film. [ABSTRACT FROM AUTHOR]

A nickel-catalyzed thiolation of unactivated C(sp2)–H bonds with disulfides employing the PIP directing group was described. This process uses a catalytic nickel catalyst and no metallic oxidants or cocatalysts are required. The reaction tolerates various important functional groups and heteroarenes, providing an efficient synthetic pathway to access diverse diaryl sulfides. [ABSTRACT FROM AUTHOR]

In this work, we present the substrate temperature induced change in the structural, optical, vibrational and luminescence properties of mixed NiO:WO (95:5) thin films deposited on glass substrates by rf magnetron sputtering technique. X-ray diffraction analysis revealed the onset of crystallization of the films occurred at 300 °C. The average optical transmittance of the films varied between 91 and 97 % in the visible region. The refractive index and extinction coefficient of films are found to decrease with increasing substrate temperature. It was observed that the dispersion data obeyed the single oscillator of the Wemple-DiDomenico model, from which the dielectric constants, ratio between free carrier density and free carrier effective mass, plasma frequency, oscillator energy, oscillator strength, and dispersion energy parameters of NiO:WO films were calculated and reported for the first time due to variation in substrate temperature during deposition by rf magnetron sputtering. The micro-Raman result shows two broad peaks corresponding to one-phonon LO mode at 570 cm and two-phonon LO mode at 1,100 cm due to the vibrations of Ni-O bonds and the peak found at 870 cm belongs to the W-O mode. Room temperature photoluminescence (RTPL) study exhibits two characteristic emission peaks at 3.32 eV (374 nm) and 2.93 eV (423 nm), which corresponding to the transition of 3d Ni ions. We have made an attempt to discuss and correlate these results with the light of possible mechanisms underlying the phenomena. [ABSTRACT FROM AUTHOR]

The direct analysis of metal-oxide nanoparticles (NPs) in suspension by inductively coupled plasma-mass spectrometry (ICP-MS) has been investigated. The roles of the chemical nature, size, crystalline form and agglomeration state of the particles in the recovery rate -- compared with dissolved samples -- have been investigated. Various sample matrices have been tested with the aim to optimize the decomposition process of the particles in the plasma, which governs the quality of the ICP-MS analytical results. It was found that, for SiO2 and ZnO, full recovery was readily obtained in 10-3 mol L-1 NaOH or 0.1% HNO3, respectively. In the case of more stable oxides like TiO2 or CeO2, a positive correlation of the recovery with the concentration of HNO3 in the matrix could be observed, although only NaOH could lead to identical sensitivities for NPs and ionic solutes. Al2O3 could not be satisfactorily analysed (80% recovery at the most). Size and agglomeration state characterization of the selected particles was performed by scanning electron microscopy and dynamic light scattering. The agglomeration state was found to be of minor influence but the size of the primary particle as well as its crystalline phase plays an important role in the analytical recovery. [ABSTRACT FROM AUTHOR]

The influence of the relation [Al] : [Fe] on the phase composition and morphology of the products obtained by the hydrothermal method using solutions of salts of metals and combined sols of aluminum and iron (3+) hydroxides has been studied. The hydrothermal treatment of solutions of salts of aluminum and iron (3+) results in the formation of hematite of a cylindrical or capsular shape, while by the treatment of sols, depending on the relation [Al] : [Fe], it is possible to obtain particles of hematite with an ellipsoidal shape or bundles of amorphous AlOOH. [ABSTRACT FROM AUTHOR]

Nanoporous Pt hollow nanostructures with octahedral and hexagonal frame-like morphologies were prepared by a novel one-pot self-templating route with no assistance from a preformed template or shape-directing agent. The hexagonal frame-like Pt hollow structures exhibited significantly enhanced catalytic activity toward CO oxidation reaction compared to the octahedral Pt hollow nanostructures due to the higher oxidation state of Pt. [ABSTRACT FROM AUTHOR]

In view of high rate fabrication of coated conductors at low-cost, YBa2Cu3O7 (YBCO) films on Ce0.9a0.1O2-y buffered yttria-stabilized zirconia substrates were deposited by means of a novel low-fluorine metal-organic solution route. A high critical current density of 3 MA cm-2 (77 K, self field) was achieved on such an all-chemical derived configuration. Structural characterization showed that the enhanced superconductivity performance of the YBCO films is mainly related to the defects induced by the interface. [ABSTRACT FROM AUTHOR]

Coating is a technology for improving the surface properties of components. Laser coating produces uniform composition with thickened layers that display a good metallurgical bond to the base material. These coatings are dense and crack-free, and have non-porous microstructures. The advantages of the process are that the components' surface will have high resistance to wear and corrosion, even at elevated temperatures. In this work, Ti6Al4V base material was coated with zirconium and zirconia composite material to improve the base material's resistance to corrosion and wear. Zirconium powder mixed with binder (PVA and cold glue) was melted to produce a thin layer, which was then bonded to the Ti6Al4V by irradiation with a fibre laser, thus forming a zirconium + zirconia composite due to an in-situ reaction in the liquid state. The presence of binder in the Zr powder indicated a change in the microstructural behaviour, as the results showed a gradual increase in the hardness of the coated Ti6Al4V from top to bottom. It was also found that Zr + PVA binder coating was uniformly deposited, and had a less dendritic structure compared with Zr without binder or Zr with cold glue. [ABSTRACT FROM AUTHOR]

In2O3 is important because it has been widely used as a transparent contact material and an active gas sensor material. To understand and utilize its intrinsic physics as a semiconductor, it is necessary to have In2O3 with a high material quality. In this article, single-crystalline (001)-oriented In2O3 thin films were grown on yttria-stabilized zirconia (001) substrate, and a group theory analysis and transmission electron microscopy (TEM) experiments were conducted to investigate the defects within the In2O3 film. Owing to the reduced symmetry of the bixbyite structure (space group Ia3) in comparison with the fluorite template (space group Fm3m), the formation of antiphase domains and 90° rotation domains in the In2O3 thin films is anticipated. This prediction is confirmed experimentally by TEMand high-angle annular dark-field scanning transmission electron microscopy images. The size of the enclosed domains ranges from 50 to 300 nm, and the major domain boundaries are along the (110), (110), (010) and (100) planes. The rotation domains are related by a fourfold rotation operation along the h001i directions, which will cause the permutation of the axes of the bixbyite structure. [ABSTRACT FROM AUTHOR]

Highlights: [•] XPS investigation on exchange coupled Fe/NiO bilayer on Si substrate has been reported. [•] Prior to irradiation, only oxide phases of iron and nickel are present. [•] Emergence of Si2p signal on the irradiation has been observed. [•] Formation of silicide phases have been confirmed on the irradiation. [•] Metallic phase of Ni has also emerged on the irradiation. [Copyright &y& Elsevier]

Semiconductor-based gas sensors that use n-type WO3 or p-type Co3O4 powder were fabricated and their gas sensing properties toward NO2 or NO (0.5-5 ppm in air) were investigated at 100 °C or 200 °C. The resistance of the WO3-based sensor increased on exposure to NO2 and NO. On the other hand, the resistance of the Co3O4-based sensor varied depending on the operating temperature and the gas species. The chemical states of the surface of WO3 or those of the Co3O4 powder on exposure to 1 ppm NO2 and NO were investigated by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. No clear differences between the chemical states of the metal oxide surface exposed to NO2 or NO could be detected from the DRIFT spectra. [ABSTRACT FROM AUTHOR]

Glycosylation is an important posttranslational modification of proteins and plays a crucial role in both cellular functions and secretory pathways. Sialic acids (SAs), a family of nine-carbon-containing acidic monosaccharides, often terminate the glycan structures of cell surface molecules and secreted glycoproteins and perform an important role in many biological processes. Hence, a more profound profiling of the sialylated glycoproteomics may improve our knowledge of this modification and its effects on protein functions. Here, we systematically investigated different strategies to enrich the SA proteins in human plasma using a newly developed technology that utilizes titanium dioxide for sialylated N-glycoproteomics profiling by mass spectrometry. Our results showed that using a combination of a filter-aided sample preparation method, TiO chromatography, multiple enzyme digestion, and two-dimensional reversed-phase peptide fractionation led to a more profound profiling of the SA proteome. In total, 982 glycosylation sites in 413 proteins were identified, among which 37.8 % were newly identified, to establish the largest database of sialic acid containing proteins from human plasma. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Controlling actively the structures of carbon nanotubes such as the alignment, length, diameter, chirality and the number of walls still remains a crucial challenge. The properties of CNTs are highly structure sensitive and particularly dependent on the diameter and number of walls. In this brief communication, we synthesise monodisperse CoFeO nanoparticles of uniform diameters, i.e. 4.8 and 6.9 nm, which are modified with oleic acid as a catalyst for the growth of CNTs. We show that a forest of vertically aligned CNTs of uniform diameters and lengths can be grown using CoFeO nanoparticles. The internal diameters and lengths of CNTs grown using CoFeO nanoparticles of 4.8 and 6.9 nm diameters are, respectively, 4.4 and 6.2 nm and 10 and 15 μm. It is clearly shown that the number of walls of CNTs can be engineered changing the materials of the catalytic nanoparticles. The present results may well encourage further systematic studies on the growth of CNTs using various combinations of elements for the catalytic nanoparticles under different external conditions, which may provide not only the possibilities of controlling the properties of CNTs but also an insight into the nucleation and growth mechanisms. [ABSTRACT FROM AUTHOR]

The dependence of the spectroscopic and electrical transport characteristics of graphene grown by chemical vapor deposition on oxide-passivations was investigated. We found that in graphene transfer and transistor fabrication processes, Al2O3- and Cr2O3-passivations are effective to suppress the extrinsic p-type doping into graphene due to surface contamination. TiO2- and NiO-passivations are not suitable because p-d hybridization between graphene π (pz) and metal (Ti or Ni) d orbitals occurs at the interfaces, resulting in deteriorated transport properties. [ABSTRACT FROM AUTHOR]

Abstract: We review recent spectroscopic mapping measurements on Bi2Sr2CaCu2O8+ x that establish experimental signatures of incipient stripe order. Model calculations show how to disentangle the effects of band structure and incipient order and allow us to model details of the energy-dependence of the observed modulations associated with incipient stripe order. Comprehensive doping and temperature studies reveal the correlation between the onset of the pseudogap and incipient stripe order in Bi2Sr2CaCu2O8+ x , yet they also show that stripes are most likely the consequence of the pseudogap rather than its cause. [Copyright &y& Elsevier]

Ferrihydrite is a common iron hydroxide nanomineral commonly found in soils, sediments, and surface waters. Reactivity with this important environmental surface often controls the fate and mobility of both essential nutrients and inorganic contaminants. Despite the critical role of ferrihydrite in environmental geochemistry, its structure is still debated. In this work, we apply bulk sensitive Fe L edge X-ray absorption spectroscopy to study the crystal field environment of the Fe in ferrihydrite and other Fe oxides of known structure. This direct probe of the local electronic structure provides verification of the presence of tetrahedrally coordinated Fe(III) in the structure of ferrihydrite and puts to rest the controversy on this issue. [ABSTRACT FROM AUTHOR]

The present Review opens with an overview of metal oxides and the description of their material properties. The first part mainly deals with various preparation techniques and growth mechanisms, which have been largely developed in the last few decades to fabricate different types of metal oxide nanostructures. The second part, on the other hand, will provide the Reader with an up-to-date summary of different applications in which metal oxides nanostructures have been successfully implemented and/or suggested. In particular, great attention will be dedicated to the implementation of metal oxide nanostructures for gas sensing as well as light emission applications, for which both working principles and integration, as well as the latest reported cutting edge results are herein reported. Finally, we emphasize on the current potentials of metal oxide nanostructured materials and future challenges that this field in continuous expansion is currently facing. [ABSTRACT FROM AUTHOR]

We developed a miniaturized LC-MS system with a high-recovery phosphopeptide enrichment protocol that allows phosphoproteome analysis of 104 cells. In the enrichment protocol, the key step is to add sodium deoxycholate and sodium lauroyl sarcosinate to the buffer solution for protein extraction and digestion and to omit any subsequent desalt/desurfactant step before phosphopeptide enrichment. The phosphopeptides enriched by hydroxy acid-modified metal oxide chromatography (HAMMOC) are directly injected onto a miniaturized LC column using a nitrogen-pressure-driven cell, instead of switching valve-type injectors. The miniaturized analytical column of 25 μm diameter provided a 3.6-fold improvement in sensitivity over the conventional 100 μm diameter column. Overall, our analytical system provided approximately 80-fold improvement on average in the LC-MS response, and we identified 1011 unique phosphorylated sites based on 995 unique phosphopeptides from a single analysis of 104 HeLa cells (approximately 1 μg of proteins). This is the most sensitive phosphoproteomics system that has so far been reported for proteome-wide analysis of in vivo phosphorylation in mammalian cells. [ABSTRACT FROM AUTHOR]

It has recently been reported that nitrogen oxide species (e.g., N2O5, NO2, NO3, and/or N2O) can have an impact on ozone based atomic layer deposition (ALD) of metal oxides when ozone is generated by dielectric barrier discharge (DBD) in O2/N2 mixtures. In this work, we further investigate the effect of the O2/N2 ratio in the DBD for HfO2 ALD using HfCl4 as metal precursor. Using O3 in the absence of nitrogen oxides, uniform HfO2 layers are obtained between 200 and 250°C in a hot wall cross flow reactor. The self-limiting nature of the O3 and HfCl4 reaction is demonstrated at 225°C and the growth-per-cycle is 0.12 nm. At higher temperature, O3 decomposes at the HfO2 coated reactor walls, resulting in a decreasing HfO2 thickness over Si substrates in the direction of the gas flow. Using O3 in combination with nitrogen oxides by DBD in N2/O2 mixtures, we obtained uniform HfO2 layers in the 200-300°C temperature range. At 300°C, the GPC is 0.14 nm and the HfO2 films show a low impurity content. Both processes produce high quality dielectric layers in Pt gated capacitors. [ABSTRACT FROM AUTHOR]