Theoretical model for flash generation

Reduction of flash generated in a gas vent is of great concern for manufacturers of electronic parts. The present study proposes a theoretical model for flash generation through consideration of flow characteristics in a gas vent. The model predicts the factors controlling flash, i.e., material parameters such as zero‐shear viscosity, crystallization temperature, thermal conductivity, and heat capacity, and process parameters such as injection and mold wall temperatures, packing pressure, and the clearance of a gas vent. On the other hand, we measure the amount of flash generated in the molding of poly(phenylene sulfide) (PPS) composites containing glass fiber and spherical fillers (CaCO₃ or Al₂O₃). Flash reduces with decreasing size of spherical fillers. These experimental data are successfully interpreted using the flash model. Polym. Eng. Sci., 45:198–206, 2005. © 2005 Society of Plastics Engineers     

Characterization and electrochemical properties of CF4 plasma-treated boron-doped diamond surfaces

The effect of CF₄ plasma etching on diamond surfaces, with respect to treatment time, was investigated using scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. SEM observations and Raman spectra indicated an increase in surface roughening on a scale of 10–20 nm, and an increase in crystal defect density was apparent with treatment time in the range of 10 s to 30 min. In contrast, alteration of the diamond surface terminations from oxygen to fluorine was found to be rather rapid, with saturation of the F/C atomic ratio estimated from XPS analysis after treatment durations of 1 min and more. The redox kinetics of Fe(CN)₆^3−/4− was also found to be significantly modified after 10 s of CF₄ plasma treatment. This behavior shows that C–F terminations predominantly affect the redox kinetics compared to the effect on the surface roughness and crystal defects. The double-layer capacitance (C_dl) of the electrolyte/CF₄ plasma-treated boron-doped diamond interface was found to show a minimum value at 1 min of treatment. These results indicate that a short-duration CF₄ plasma treatment is effective for the fabrication of fluorine-terminated diamond surfaces without undesirable surface damage.     

Radiation detector made of a high-quality polycrystalline diamond

Radiation detector was made of a high-quality CVD polycrystalline diamond composed of frost column like structure diamond grains, and induced charge distribution spectra and drift velocities were measured by using alpha particles. As a result, the CVD polycrystalline achieved maximum induced charge of 83% of HP/HT type IIa diamond. Moreover, the CVD crystal had lower charge loss on electrons compared with the HP/HT type IIa diamond. Drift velocities of electrons and holes were v_e = 7.7 × 10⁴ and v_h = 7.3 × 10⁴cm/s at an electric field of 20 kV/cm, respectively. In addition, response function measurement for 14 MeV neutrons was carried out.     

A non-specific lipid transfer protein from Arabidopsis is a cell wall protein

Lipid transfer proteins (LTPs), mediate the transfer of phospholipids between membranes in vitro. However, the in vivo function of LTPs is not known. To determine the precise location of a non-specific LTP from Arabidopsis, a cDNA clone was used to produce an Arabidopsis LTP:protein A fusion. Antibodies raised against the fusion were used to localize the Arabidopsis LTP by immunoelectron microscopy. LTP was found to be located in the cell wall, mainly in epidermal cells. This location appears to be inconsistent with the proposed role of the protein in intracellular lipid transfer.     

Metabolism of tetramethrin isomers in rat: II. Identification and quantitation of metabolites

1. To examine the metabolic fate of (1RS, trans)- or (1RS, cis)-tetramethrin [3, 4, 5, 6-tetrahydrophthalimidomethyl (1RS, trans)- or (1RS, cis)-chrysanthemate], rat was administered a single oral dose of trans- or cis-[alcohol-14C]tetramethrin at dose levels of 2 or 250 mg/kg. 2. The radiocarbon was almost completely eliminated from rat within 7 days after administration in all groups. 14C-recoveries (expressed as percentages relative to the dosed 14C) in faeces and urine were 38-58 and 42-58% respectively in rat administrated trans-[alcohol-14C]tetramethrin, and in faeces and urine were 66-91 and 9-31% respectively in rat administered cis-[alcohol-14C]tetramethrin. 3. Fourteen metabolites found in excreta were purified by using several chromatographic techniques and identified by spectroanalyses (nmr and MS). Five sulphonate derivatives and three dicarboxylic acid derivatives were found. 4. The main metabolites were sulphonate derivatives in the faeces, and in the urine, alcohols, dicarboxylic acid and reduced metabolites derived from the 3,4,5,6-tetrahydrophthalimide moiety.     

Resistive superconducting transition of κ-type BEDT-TTF organic superconductors in a magnetic field

The superconducting transition of the organic compoundsκ-(BEDT-TTF)₂ X is studied by resistive measurement in a magnetic field up to 10 T applied normal to the conducting plane. For the salts withX=Cu[N(CN)₂]Br andX=CuCN[N(CN)₂] the transition shows fanshaped broadening caused by superconductivity fluctuation. For theX=Cu(NCS)₂ salt the resistivity shows a peak in the transition region in a magnetic field below 4 T.This phenomenon is suppressed in defect-reduced samples for intralayer conduction. We discuss this peak in relation to the thermal fluctuation on the Josephson junction structures in this salt.     

Simulation and experimental analyses of electromagnetic transients behaviors of lightning surge on vertical conductors

Simulation of very fast surge phenomena in a three-dimensional (3-D) structure requires a method based on Maxwell's equations, such as the finite-difference time-domain (FDTD) method or the method of moments, because circuit-equation-based methods cannot handle the phenomena. This paper uses a method of thin-wire representation of the vertical conductor system for the FDTD method which is suitable for the 3-D surge simulation. The thin-wire representation is indispensable to simulate electromagnetic surges on wires or steel frames in which the radius is smaller than a discretized space step used in the FDTD simulation. In this paper, a general surge analysis program named the virtual surge test lab based on the Maxwell's equations formulated by the FDTD method, is used to simulate the surge phenomena of a vertical conductor, including the effects of horizontal wave incidence and vertical wave incidence. Experimental results on the reduced scale model have been presented in order to compare among the simulation results by the FDTD method and the results using numerical electromagnetic code based on the MoM.     

Preferential Oxidation of CO in H2-Rich Gas at Low Temperatures over Au Nanoparticles Supported on Metal Oxides

We investigated Au catalysts supported on TiO₂, Fe₂O₃, and ZnO for their preferential oxidation of CO in a H₂-rich atmosphere. Both full conversion and selectivity were achieved over Au/Fe₂O₃ and Au/ZnO around room temperature, but at higher temperatures the CO conversion was suppressed due to competition between CO and H₂.