Immobilized heterobimetallic Ru/Co nanoparticle-catalyzed Pauson-Khand-type reactions in the presence of pyridylmethyl formate

Heterobimetallic Ru/Co nanoparticles, immobilized on charcoal, were synthesized and used as catalysts in the Pauson-Khand-type reaction in the presence of pyridylmethyl formate instead of carbon monoxide; the catalysts were effective for intra- and intermolecular reactions and easily reused without loss of catalytic activity.     

Synthesis of novel 2,6-disubstituted-3,4-dimethylidene tetrahydropyrans via Prins-type cyclization

Synthesis of novel substituted tetrahydropyrans with adjacent exo-methylene groups at the C3 and C4 positions via Prins-type cyclization has been described.     

Magnetic and noise properties of as-deposited and annealed soft underlayer

We studied the magnetic and noise properties with various soft underlayer (SUL) types. For an as-deposited SUL, the results of spectrum, oscilloscope waveform and MFM indicated that the SUL types with IrMn pinning layer have more noise level than that of SUL types without IrMn pinning layer. And, after magnetic filed annealing along radial direction of disk, the exchange bias field increased and the noise level of type B (exchange bias type) decreased. These results reveal that incomplete or partial coupling may be generated at the interface between IrMn and ferromagnetic layer in as-deposited SUL. This incomplete coupling may result in complex or multidomain patterns in ferromagnetic layer.     

Surface status and size influences of nickel nanoparticles on sulfur compound adsorption

Metallic nickel nanoparticles were incorporated on mesoporous silica to remove sulfur compounds in diesel selectively. In the first method, nickel nanoparticles were formed on mesoporous silica SBA-15 by impregnation and subsequent reduction of nickel nitrate. The sulfur adsorption capacity was strongly dependent on the nickel loading and the average nickel particle size. In the second method, nickel nanoparticles were synthesized in solution in the presence of a capping agent and then incorporated in mesoporous silica MCF by sonication. Although these particles maintain their sizes on the MCF surface after heat treatment, capping agent remaining on the Ni particle surface might interfere the adsorption of sulfur compounds.     

Influence of pretreatment methods on adsorption and catalytic characteristics of toluene over heterogeneous palladium based catalysts

The adsorption and catalytic characteristics of heterogeneous palladium based catalyst and its modified catalysts with gases (air and hydrogen) and acidic aqueous solution (HCl) were studied for evaluating the influence of pretreatment methods for toluene. The structural and energetic adsorption properties of the parent and pretreated catalysts were analyzed by means of nitrogen adsorption isotherms and gravimetric methods. The light-off curve and the XPS investigation were used for analyzing the catalytic activity and the surface state of palladium. It was clearly shown from the experimental results that hydrogen pretreated catalysts having metallic surface state exhibited the highest adsorption capacity and catalytic activity compared to that of parent and modified catalysts. The adsorption equilibrium data for toluene were obtained at three different temperatures and correlated successfully with the two-site Langmuir molecular isotherm model (L2m). It was also found that the palladium phase has more adsorption affinity for toluene molecules than the alumina support. The isosteric heat of adsorption calculated by using the Clausius-Clapeyron equation significantly changed with the coverage and the lateral interactions between the adsorbate-adsorbate molecules control the system. Furthermore, comparative analysis of the adsorption energy distribution revealed that the parent and its modified catalysts have different types of surface energetic heterogeneities.     

Dispersion measurement technique based on the self-seeding laser oscillation of a Fabry-Perot laser diode

A simple dispersion measurement technique has been proposed and demonstrated by using the self-seeding laser oscillation of a Fabry-Perot laser diode through an optical closed-loop path. When the multi-mode optical pulses emitted from the laser are re-injected into the laser after traversing a fiber-under-test, a single mode laser oscillation occurs through the closed-loop path due to the group velocity difference between the pulses of different wavelengths. We measured the dispersion parameter of the fiber-under-test from the modulation frequency changes required to induce single-mode laser oscillations through the optical closed-loop path. The maximum measurement error was less than 1.5% for the optical fibers as compared with a commercial instrument.     

Frequency domain optical tomography using a conjugate gradient method without line search

A conjugate gradient method without line search (CGMWLS) is presented. This method is used to retrieve the local maps of absorption and scattering coefficients inside the tissue-like test medium, with the synthetic data. The forward problem is solved with a discrete-ordinates finite-difference method based on the frequency domain formulation of radiative transfer equation. The inversion results demonstrate that the CGMWLS can retrieve simultaneously the spatial distributions of optical properties inside the medium within a reasonable accuracy, by reducing cross-talk between absorption and scattering coefficients.     

Growth of InN films and nanorods by H-MOVPE

InN films and nanorods were grown by hydride metalorganic vapor phase epitaxy (H-MOVPE) and the effects of growth temperature, and NH₃/TMIn and HCl/TMIn ratios on morphological dependences were studied. The growth habit of InN varied from thin film to microrod to nanorod to no deposition as the growth conditions were changed about transition from growth to etching conditions. The growth and etch regimes were also predicted by chemical equilibrium calculations of In–C–H–Cl–N-inert system. The optical properties of InN nanorods and columnar structured films were measured by room temperature PL and a maximum intensity was observed at 1.08 eV for both structures.     

Enhanced luminescent properties of Y3Al5O12:Tb,Ce phosphor prepared by spray pyrolysis

Yttrium aluminum garnet (YAG) particles doped with Tb³⁺ or double doped with Tb³⁺ and Ce³⁺ were prepared by spray pyrolysis and characterized by photo- and cathode-luminescence. It was tried to incorporate a broad band of Ce³⁺ activator into the line peaks of Tb³⁺ in YAG host without the reduction of emission intensity. Ce-codoped YAG:Tb particles showed a broad band emission due to the d-f transition of Ce³⁺ and a reduction in the intensity of emission peaks due to ⁵D₃-⁷F_j (j=3, 4, 5, 6) transition of Tb³⁺ when they were excited by the ultraviolet light of 270 nm. These results supported that an effective energy transfer occurs from Tb³⁺ to Ce³⁺ in YAG host. Codoping Ce³⁺ ions greatly intensified the excitation peak at 270 nm for the emission at 540 nm of Tb³⁺, which means that more lattice defects, involving in the energy absorption and transfer to Tb³⁺, are formed by the Ce³⁺ codoping. The finding gives a promising approach for enhancing the luminescence efficiency.     

Simulation of two‐phase flow–body interaction problems using direct forcing/fictitious domain–level set method

In the present paper, a direct forcing/fictitious domain (DF/FD)–level set method is proposed to simulate the twophase flow–body interaction. The DF/FD does not sacrifice accuracy and robustness by employing a discrete δ (Dirac delta) function to transfer quantities between the Eulerian nodes and Lagrangian points explicitly as the immersed boundary method. The advantages of this approach are the simple concept, the easy implementation and the utilization of original governing equation without modification. The main idea is to combine DF/FD method with the level set method in the Cartesian coordinates. We present the results of a number of test cases to illustrate the effectiveness of the proposed method for single‐phase flow–body interaction problem and the two‐phase flows with a stationary body. Eventually, the simulations of various water entry problems have been conducted to validate the capability and the accuracy of the present method on solving the twophase flow–body interaction. Consequently, the present results are found to be in good agreement with those of previous studies. Copyright © 2013 John Wiley & Sons, Ltd.