A general procedure to synthesize highly crystalline metal oxide and mixed oxide nanocrystals in aqueous medium and photocatalytic activity of metal/oxide nanohybrids

A conventional and general route has been exploited to the high yield synthesis of many kinds of highly crystalline metal oxide and mixed oxide nanocrystals with different morphologies including belt, rod, truncated-octahedron, cubic, sphere, sheet via the hydrothermal reaction of inorganic precursors in aqueous solution in the presence of bifunctional 6-aminohexanoic acid (AHA) molecules as a capping agent. This method is a simple, reproducible and general route for the preparation of a variety of high-crystalline inorganic nanocrystals in scale-up. The shape of inorganic nanocrystals such as CoWO(4), La(2)(MoO(4))(3) can be controlled by simply adjusting the synthesis conditions including pH solution and reaction temperature. Further, by tuning precursor monomer concentration, the mesocrystal hierarchical aggregated microspheres (e.g., MnWO(4), La(2)(MoO(4))(3)) can be achieved, due to the spontaneous assembly of individual AHA-capped nanoparticles. These obtained AHA-capped nanocrystals are excellent supports for the synthesis of a variety of hybrid metal/oxide nanocrystals in which noble metal particles are uniformly deposited on the surface of each individual nanosupport. The photocatalytic activity of Ag/TiO(2) nanobelts as a typical hybrid photocatalyst sample for Methylene Blue degradation was also studied.     

FeCoHfN thin films fabricated by co-sputtering with high resonance frequency

Thin films of FeCoHfN were fabricated by co-sputtering technique with the deposition angles varied. Their dynamic magnetic properties were characterized and discussed in conjunction with an analysis based on Landau-Lifshitz-Gilbert equation. High ferromagnetic resonance frequency beyond 6 GHz was achieved by adjusting the deposition angle. A discrepancy between static and magnetic anisotropy was observed and discussed within the framework of Hoffmann's ripple theory. Also, the variations of frequency linewidth, damping factor, and permeability with the change of deposition angle were presented and discussed.     

Sex Pheromone Components and Control of the Citrus Pock Caterpillar, Prays endocarpa, Found in the Mekong Delta of Vietnam

The citrus pock caterpillar, Prays endocarpa (Yponomeutidae; Praydinae), is a pest of pomelo (Citrus grandis L.) in Vietnam. Gas chromatography-mass spectrometry analyses of pheromone gland extracts from female moths identified three monoenyl compounds, (Z)-7-tetradecenal (Z7-14:Ald), (Z)-7-tetradecenyl acetate (tentatively identified, Z7-14:OAc), and (Z)-7-tetradecen-1-ol (Z7-14:OH), in a ratio of about 10:3:10. In the field, traps baited with synthetic Z7-14:Ald (0.5 mg) caught male P. endocarpa. The other two compounds, either alone or when added to Z7-14:Ald, did not elicit increases in trap catch (relative to the appropriate treatment). Synthetic Z7-14:Ald was used to monitor and control this species in pomelo orchards in Vinh Long Province. Monitoring revealed that adults were present throughout the year with discernible peaks in December, March, and April. A mass-trapping trial, using 20 traps in a 0.1 ha pomelo orchard, effectively suppressed fruit damage to levels similar to that achieved by an insecticide (Karate 2.5EC). Mating disruption trials, using polyethylene-tube dispensers, each filled with 80 mg of Z7-14:Ald at a rate of 200 or 400 dispensers/ha, also controlled damage by this pest to levels below that achieved by an insecticide treatment. This work demonstrates the potential for pheromone-based control of this pest in Vietnam.     

Stereo Video Retargeting with Representative Seams in a Group of Stereoscopic Frames

The important requirements for stereo video retargeting are threefold: keeping temporal coherence, preventing depth distortion, and minimizing shape distortions of the retargeted video. To meet these requirements, the left and right video sequences are divided into groups of frames (GoFs), where the GoF is a basic unit for the seam carving and we assign a set of fixed seams for all frames within the GoF. To determine the fixed seams for each GoF, we need to find the GoF boundary in the video first. Then, the representative frame for each GoF is generated by considering the spatial saliency and temporal coherence. Also, the confidence of the stereoscopic correspondence between the left and right frames is considered to prevent depth distortion.     

Reverse Authentication in Financial Transactions and Identity Management

New families of protocol, based on communication over human-based side channels, permit secure pairing or group formation in ways such that no party has to prove its name. Rather, individuals are able to hook up devices in their possession to others that they can identify by context. We examine a model in which, to prove his or her identity to a party, the user first uses one of these “human-interactive security protocols” or HISPs to connect to it. Thus, when authenticating A to B, A first authenticates a channel she has to B: the reverse direction. This can be characterised as bootstrapping a secure connection using human trust. This provides new challenges to the formal modelling of trust and authentication.     

Improved Graphitic Structure of Continuous Carbon Nanofibers via Graphene Oxide Templating

Continuous carbon nanofibers (CNF) present an attractive building block for a variety of multifunctional materials and devices. However, the carbonization of poly(acrylonitrile) (PAN) precursors usually results in CNFs with poor graphitic structure and, consequently, modest/non‐optimized properties. This paper reports that the graphitic structure of CNFs can be improved with an addition of a small amount of graphene oxide into PAN prior to processing. Continuous CNFs with 1.4 wt% of graphene oxide nanoparticles are prepared from PAN solutions by electrospinning, stabilized, and carbonized at 800 °C, 1200 °C, and 1850 °C. While the as‐prepared graphene oxide‐filled PAN nanofibers exhibit a considerable reduction in polymer crystallinity, Raman analysis of the carbonized nanofibers shows that both templating with graphene oxide and increasing the carbonization temperature significantly improve the graphitic order in CNFs. The effect of graphene oxide is more significant at higher carbonization temperatures. Selected area electron diffraction analysis of individual nanofibers reveals increased graphitic order and preferred orientation both in the vicinity of visible graphene oxide nanoparticles and in the regions where nanoparticles were not visible. These results indicate a possibility of global templating in CNFs, where the addition of a small amount of graphene oxide nanoparticles can template the formation of good, preferentially oriented graphitic crystallites in CNFs, leading to improved structure and mechanical and transport properties.     

Operational behavior and reforming kinetics over Ni/YSZ of a planar type pre-reformer for SOFC systems

At Forschungszentrum Jülich GmbH, a multi-component SOFC design based on planar stacks has been developed, in which all hot system components are scaled to a nominal SOFC stack power of 5 kW. To optimize the SOFC system it is necessary to investigate the effects of design and operating parameters on the system components like pre-reformer and afterburner. A special designed 5-layer planar type steam pre-reformer on basis of Ni/YSZ has been built and tested for operational behavior and kinetics of steam reforming with methane. This paper summarizes and discusses the experimental results on the global reaction kinetics of a Jülich planar pre-reformer in the temperature range between 350 °C and 620 °C at ambient pressure (1 bar). The species compositions of product gas at different feed compositions, flow rates and temperatures are determined by using gas-chromatographic methods and dew-point measurements. The reproducibility of experiments in the low temperature range (especially less than 430 °C) was only assured, when the catalyst has been reduced before every kinetic experiment. The proposed kinetic expression of Arrhenius type (second order with respect to mole fraction of methane and first order with respect to mole fraction of water) gives a good agreement with the experimental results of the methane steam reforming. It is general effective for different steam to carbon ratios. The temperature distribution in the pre-reformer and the loss of heat are also discussed.     

Nd0.5Sr0.5Fe0.8Cu0.2O3−δ–xSm0.2Ce0.8O1.9 cobalt-free composite cathodes for intermediate temperature solid oxide fuel cells

Cobalt-free composites Nd_0.5Sr_0.5Fe_0.8Cu_0.2O_3−δ (NSFCu)–xSm_0.2Ce_0.8O_1.9 (SDC) (x = 0–60 wt%) are investigated as IT-SOFC cathodes. The characteristic properties of cobalt-free composite cathodes comparing to cobalt-based composites are revealed. The DC conductivity and thermal expansion coefficient of the composite cathodes decrease with the content of SDC x, while the polarization resistance R_p shows the least value with addition of 40 wt% of SDC. The power density of the single cell with NSFCu-40% SDC composite cathode improved significantly compared with that of undoped NSFCu cathode, with peak values of 488, 623, 849 and 1052 mW cm⁻² at 600, 650, 700, and 750 °C, respectively. Moreover, the performance of the composite cathode is stable within testing period of 370 h at 700 °C, indicating that the NSFCu-40% SDC is an excellent cobalt-free composite cathode applied in IT-SOFC.