Trimetallic nanoparticles having a Au-core structure

The Au/Pt/Rh trimetallic nanoparticles were successfully synthesized by a combination of a co-reduction and a self-organization method using poly(N-vinyl-2-pyrrolidone) (PVP) as a protecting reagent. The triple core/shell structure was suggested by HR-TEM, EF-TEM and FT-IR-CO for the trimetallic nanoparticles. The present trimetallic nanoparticles had much higher catalytic activity for hydrogenation than the corresponding monometallic and bimetallic nanoparticles. This high catalytic activity can be due to the sequential electronic effect between different atoms of a particle, which is supported by XPS data.     

In situ analysis of creep behavior of pure Pb using electrochemical creep system

The control of the growth of a Pb-based alloy grid is very important for extending the life of a lead-acid battery. In this study, the creep behavior of pure Pb was investigated in air, in a highly concentrated H₂SO₄ solution, and in a highly concentrated H₂SO₄ solution with the intermittent electrifying to the specimen electrode, which simulated the discharge-charge process of the lead-acid battery, in order to obtain the fundamental knowledge about the growth of the Pb-based alloy grid. The growth or the creep of pure Pb in the stress range of 4.0-6.0 MPa was advanced by a dislocation creep mechanism. The creep rate in a 4.5 kmol m⁻³ H₂SO₄ solution was also accelerated by the electrifying to the electrode. This suggests that the acceleration of the creep rate is closely related to the release of dislocations near the specimen surface by the electrifying.     

Hydrogen production using integrated methanol‐steam reforming reactor with various reformer designs for PEM fuel cells

A 95 mm × 40 mm × 15 mm compact reactor for hydrogen production from methanol‐steam reforming (MSR) is constructed by integrating a vaporizer, reformer, and combustor into a single unit. CuO/ZnO/Al₂O₃ is used as the catalyst for the MSR while the required heat is provided using Platinum (Pt) ‐catalytic methanol combustion. The reactor performance is measured using three reformer designs: patterned micro‐channel; inserted catalyst layer placed in a single plain channel; and catalyst coated directly on the bottom wall of single plain channel. Because of longer reactant residence time and more effective heat transfer, slightly higher methanol conversion can be obtained from the reformer with patterned microchannels. The experimental results show that there is no significant reactor performance difference in methanol conversion, hydrogen (H₂) production rate, and carbon monoxide (CO) composition among these three reformer designs. These results indicated that the flow and heat transfer may not play important roles in compact size reactors. The reformer design with inserted catalyst layer provides convenience in replacing the aged catalyst, which may be attractive in practical applications compared with the conventional packed bed and wall‐coated reformers. Copyright © 2011 John Wiley & Sons, Ltd.     

Positions and Stereochemistry of Methyl Branches in the Novel Sex Pheromone Components Produced by a Lichen Moth, Lyclene dharma dharma

Female moths of Lyclene dharma dharma (Arctiidae, Lithosiinae) produce three sex pheromone components (I–III), for which we assigned the following novel chemical structures; 6-methyl-2-octadecanone (1) for I, 14-methyl-2-octadecanone (2) for II, and 6,14-dimethyl-2-octadecanone (3) for III. In the Iriomote Islands where the insects were collected, a lure including racemic 1 and 2 attracted the male moths without mixing 3. In this study for further confirmation of the plane structures, the positional isomers with a methyl branch at the 4-, 5-, 7-, 13-, or 15-position (4–8, respectively) were synthesized. The GC-MS analyses revealed that natural components I and II were best fitted with those of 1 and 2, respectively, among the methyl-2-octadecanones examined, indicating the usefulness of this analytical instrument and authentic standards for the determination of the positions of methyl branches. In field trapping tests, 4–8 could not substitute for 1 or 2, nor did these compounds inhibit the active binary lure of 1 and 2, indicating that the males strictly recognized the 2-ketones with a methyl branch at the 6- or 14-positions. Next, the absolute configurations of I and II were determined by HPLC with a normal-phased chiral column (Chiralpak AD-H), which could separate the enantiomers of both 1 and 2. The chiral HPLC analysis of a crude pheromone extract indicated that the females exclusively produced (S)-1 and (S)-2. Furthermore, a field evaluation of each enantiomer revealed that (S)-1 and (S)-2 were bioactive but (R)-1 and (R)-2 were not.     

Design of compact methanol reformer for hydrogen with low CO for the fuel cell power generation

The effect of the heat transfer area and the thermal conductivity of the reactor materials are evaluated with three identical structured reactors having multiple columned-catalyst bed and using three different reactor materials, aluminum alloy, brass and stainless steel. A series of compact methanol reformers are then designed and fabricated with the use of large reactor surface area in catalyst beds and high heat transfer constant to produce hydrogen fuel with 2–4 ppm of CO for the fuel cell (FC) power generation. The same design principle is successfully used for easy scale up of the reactor capacity from 250 L/h to 10,000 L/h. This low CO hydrogen (68–70%) used as the fuel for the fuel cell power generation provides a very competitive cost of hydrogen and electric power, $0.20–0.23/m³ of H₂ and $0.196/KWh, respectively.     

Propionates and Acetates of Chiral Secondary Alcohols: Novel Sex Pheromone Components Produced by a Lichen Moth Barsine expressa (Arctiidae: Lithosiinae)

Females of a lichen moth, Barsine expressa (Arctiidae, Lithosiinae), which inhabit Iriomote Island in Japan, were captured by a black-light trap, and the pheromone gland extract was analyzed by gas chromatography (GC) with an electroantennographic (EAG) detector, and by GC coupled with mass spectrometry. The females produced several EAG-active esters, and the mass spectrum of a major component indicated the mixture consists of propionates derived from C₁₇-saturated secondary alcohols, which were inseparable on the capillary GC column. In addition to these main components, the pheromone glands included two acetate derivatives of C₁₇ alcohols, and other propionates of C₁₆ and C₁₅ alcohols. The crude extract was treated with K₂CO₃, and a 1:1 mixture of C₁₇ alcohols with a C₆- or C₇-chain moiety was obtained. The two alcohols were uniformly converted into monodeuterated n-heptadecane by mesylation and succeeding LiAlD₄ reduction. This result revealed a straight-chain structure of the C₁₇ alcohols with the acyl groups located at the 7- or 8-position. Field tests on Iriomote Island showed that the synthetic esters were behaviorally active. A 1:1 mixture of racemic 7-propioxyheptadecane and 8-propioxyheptadecane, which were prepared from the secondary alcohols synthesized by a Grignard coupling reaction, attracted male moths. Furthermore, propionates of the alcohols synthesized enantioselectively by using a hydrolytic kinetic resolution with Jacobsen’s catalyst were evaluated. Only the traps baited with a mixture of the two esters with the same S-configuration significantly attracted B. expressa males. In the Tokyo area, the propionate mixture attracted a closely related species, Barsine aberrans aberrans.     

Zeitbereichsbetrachtung der Reflexions- und Transmissionseigenschaften einer dünnen,verlustbehafteten Schicht

Übersicht Die Reflexions- und Transmissionseigenschaften einer ebenen, verlustbehafteten, dünnen Schicht, die sich zwischen zwei homogenen, verlustfreinen Halbräumen befindet, wird analytisch im Zeitbereich untersucht. Die unter beliebigem Einfallswinkel auf die Schicht auftreffende homogene, ebene TEM-Welle darf deshalb eine beliebig vorgebbare Wellenform besitzen. Es wird gezeigt, daß für dünne Schichten Reflexions- und Durchgangsfaktoren angegeben werden können. Aus den Reflexionsfaktoren werden Oberflächenimpedanzen zum Einsatz in FDTD-Algorithmen entwickelt. Anschließend werden die Resultate auf den Fall, daß beide Halbräume unterschiedliche Materialeigenschaften besitzen, erweitert und in numerischen Simulationen angewendet.

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Time domain calculations of the reflection and transmission properties of a thin and lossy slab

Contents Reflection and transmission properties of a thin and lossy slab, surrounded by two homogeneous and lossless semi-infinite media, are analytically examined in the time domain. Arbitrary incidence angles of the incident, homogeneous and plane TEM-wave are allowed. The time-domain method used allows arbitrary wave shapes. It is shown that reflection and transmission coefficients exist for thin slabs. From the reflection coefficients we develop surface impedance boundary conditions for the use in FDTD-method. Subsequently, the results are expanded to the case where material properties of the two semi-infinite spaces are different. Finally, the application of the developed surface impedance boundary conditions in numerical simulations is shown.

     

Optimal allocation of heterogeneous workers in a U-shaped production line

In this paper, we deal with a U-shaped production line with multiple heterogeneous multi-function workers. Skills of workers are assumed to be different. We consider an optimization problem for finding an allocation of workers to the line that minimizes the overall cycle time under the minimum number of workers satisfying the demand. All of processing, operation and walking times are deterministic. We propose an algorithm for computing an optimal allocation of workers to machines.