Fabrication of a PTFE-filled waveguide for millimeter-wave components using SR direct etching

PTFE is widely used as a microwave and millimeter-wave material. However, it is known that PTFE is a difficult material to cut at high precision by conventional machining, or even by laser cutting or electrical discharge machining. It has been reported that PTFE microstructures can be fabricated by direct exposure to synchrotron radiation. A metallic waveguide is one of effective media guiding a millimeter- and submillimeter-wave because of the advantage of low loss. In this paper, the SR direct etching of PTFE is introduced and a trial fabrication of millimeter-wave PTFE waveguide is attempted.     

Additive effect of CF3Cl on OH, CH, and C2 emissions: Shock tube study with C2H4---O2---CF3Cl and CH4---O2---CF3Cl mixtures

Mixtures of C₂H₄---O₂---CF₃Cl and CH₄---O₂---CF₃Cl, highly diluted with argon, were heated to the temperature range 1350–2200K behind reflected shock waves, and the additive effects of CF₃Cl on OH^*, CH^*, and C₂^* emissions in the ethylene and methane combustion processes were examined by observing the delay time, and the intensities of OH^*, CH^*, and C₂^* emissions. It was found that, in ethylene combustion, the addition of CF₃Cl prolonged the delay times to the maximum intensities, decreased the intensities of OH^* and CH^* emissions, and had little influence on that of C₂^* emission. However, in methane combustion, it was found that the addition of CF₃Cl shortened the delay times to the maximum intensities and to the onset of ignition, increased the intensities of CH^* and C₂^* emissions, and had little influence on that of OH^* emission.     

Position Dependence of SS304 and Iron Phases in Welded Specimen by Neutron Diffraction and Bragg-Edge Transmission Method

We investigated the nondestructive examination method by neutron scattering. A welded plate of SS304 (fcc) and iron (bcc) was investigated using neutron diffraction and the Bragg-edge transmission method. We tried to clear the positions of the welded area, SS304 phase, and iron phase and to determine the lattice spacing. The determined value of d ₁₁₁ for SS304 is 2.07471(8) Å using neutron diffraction. With Bragg-edge transmission, it is possible to collect the information of a specimen as two-dimensional (2-D) images using a 2-D position sensitive detector at a pulse neutron source. The determined d ₁₁₁ of SS304 phase indicates between 2.0745(8) and 2.0752(9) Å depending on the measurement points using Bragg-edge transmission. The same tendency was also seen in iron phase. The determined d ₁₁₀ of the iron phase is 2.02802(1) Å using neutron diffraction. The determined d ₁₁₀ of iron phase indicates between 2.0266(7) and 2.0321(13) Å using Bragg-edge transmission. The determined d using diffraction exists within that of Bragg-edge transmission. In order to clarify the position dependency of the phase and lattice spacing, the combined diffraction and Bragg-edge transmission is effective.     

Subchannel analysis of supercritical light water-cooled fast reactor assembly

Subchannel analyses have been carried out for supercritical water-cooled fast reactor fuel assembly. Peak cladding surface temperature difference arising from subchannel heterogeneities have been calculated by using the improved subchannel analysis code STARS and was evaluated to be about 18.5 °C. Several suggestions have been also made for reducing the PCST difference arising from channel heterogeneity. Influences of local power peaking on deflection of cladding surface temperature are explained with pin power distribution taken from core depletion calculation in this paper. Maximum cladding surface temperature at nominal condition is evaluated to be 645.3 °C over the cycle. Statistical thermal design uncertainty associated with PCST calculation is evaluated by Monte-Carlo sampling technique combined with subchannel analysis code. Maximum statistical design uncertainty of PCST is calculated to be 31 °C and is in a good agreement with that from RTDP method. Influence of downward flow in seed region on system sensitivity is investigated by improved Monte-Carlo thermal design procedure. Limiting thermal condition of MCST is 681 °C (650 °C of nominal + 31 °C) within 95/95 limit for SWFR.     

Numerical investigation of heat transfer in upward flows of supercritical water in circular tubes and tight fuel rod bundles

Heat transfer in upward flows of supercritical water in circular tubes and in tight fuel rod bundles is numerically investigated by using the commercial CFD code STAR-CD 3.24. The objective is to have more understandings about the phenomena happening in supercritical water and for designs of supercritical water cooled reactors. Some turbulence models are selected to carry out numerical simulations and the results are compared with experimental data and other correlations to find suitable models to predict heat transfer in supercritical water. The comparisons are not only in the low bulk temperature region, but also in the high bulk temperature region. The two-layer model (Hassid and Poreh) gives a better prediction to the heat transfer than other models, and the standard k– high Re model with the standard wall function also shows an acceptable predicting capability. Three-dimensional simulations are carried out in sub-channels of tight square lattice and triangular lattice fuel rod bundles at supercritical pressure. Results show that there is a strong non-uniformity of the circumferential distribution of the cladding surface temperature, in the square lattice bundle with a small pitch-to-diameter ratio (P/D). However, it does not occur in the triangular lattice bundle with a small P/D. It is found that this phenomenon is caused by the large non-uniformity of the flow area in the cross-section of sub-channels. Some improved designs are numerically studied and proved to be effective to avoid the large circumferential temperature gradient at the cladding surface.     

Vinyl polymerization by metal complexes, 26. Vinyl polymerization initiated by polyvinylamine-copper(II) chelate in dimethylsulfoxide solution

The polymerization of acrylonitrile and methyl methacrylate initiated by polyvinylamine-copper(II) chelate was studied in dimethylsulfoxide solution, in the presence and absence of carbon tetrachloride. For comparison, the dimeric chelate(1,3-diaminopropane-copper(II) chelate) was also chosen as an initiator. The initiation activity of the dimeric chelate was found to be higher than that of the polymeric chelate in dimethylsulfoxide solution, different from the cases in aqueous media. The dimeric chelate could initiate the polymerization of acrylonitrile effectively, even in the absence of carbon tetrachloride.     

A natural soil and mechanism of removal: Part II

Based on the findings of interaction between dodecyl benzene sulfonate (DBS) and high molecular weight nitrogen compounds in natural soil in the first report of this series, artificially soiled clothes containing protein were prepared and a washing test was carried out with a use of DBS or nonyl phenol-polyoxyethylene adduct (NPEO). Cattle serum globulin, cod sperm protamine and feather keratin of wild duck were used as protein. The built DBS detergent showed better detergency on the artificially soiled clothes than the built NPEO detergent at a same surfactant concentration of 0.05%, although no difference was observed in the redeposition test between these detergents. A significant dissolving action of DBS was observed. Results indicate that when discussing the mechanism of dissolution of natural soil or in the course of modifying the artificially soiled clothes, a chemical reaction between DBS and protein had to be considered in addition to the well known physico-chemical surface activity of the surfactant for removal of soil.     

Surface modification processing of synthetic rubbers by ultraviolet irradiation and sputter ion etching treatment

The mechanism by which surface modification of two kinds of synthetic rubbers (ethylene-propylene and chloroprene) was brought about by ultraviolet (UV) irradiation and sputter ion etching treatments was studied from a physicochemical point of view. The most remarkable effect of this irradiation treatment was the rapid increase in adhesion properties and the simultaneous decrease in self-stickiness. This nonsticking effect was particularly important for the rapid production of articles from thin rubber sheets. The surface modification mechanism was studied by use of SEM, ESCA, FTIR, and related interfacial analytical procedures. It was shown that surface roughening with a quite thin layer of surface oxidation (∼0.5 μm in depth) is a key factor for the development of nonsticking properties. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1625–1633, 1997     

A two-amino acid insertion in the Cys146- Cys167 loop of the alphaIIb subunit is associated with a variant of Glanzmann thrombasthenia. Critical role of Asp163 in ligand binding

The ligand binding site(s) of the alpha subunit of integrin alphaIIb beta3 (GPIIb-IIIa), a prototypic non-I domain integrin, remains elusive. In this study, we have characterized a Japanese variant of Glanzmann thrombasthenia, KO, whose platelets express normal amounts of alphaIIb beta3. KO platelets failed to bind the activation-independent ligand-mimetic mAb OP-G2 and did not bind fibrinogen or the activation-dependent ligand-mimetic mAb PAC-1 following activation of alphaIIb beta3 under any condition examined. Sequence analysis of PCR fragments derived from KO platelet mRNA revealed a 6-bp insertion leading to a 2-amino-acid insertion (Arg-Thr) between residues 160 and 161 of the alphaIIb subunit. Introduction of the insertion into wild-type recombinant alphaIIb beta3 expressed in 293 cells led to the normal expression of alphaIIb beta3 having the defect in ligand binding function. The insertion is located within the small loop (Cys146-Cys167) in the third NH2-terminal repeat of the alphaIIb subunit. Alanine substitution of each of the oxygenated residues within the loop (Thr150, Ser152, Glu157, Asp159, Ser161, and Asp163) did not significantly affect expression of alphaIIbbeta3, and only Asp163AlaalphaIIb beta3 abolished the ligand binding function. In addition, Asp163AlaalphaIIb beta3 as well as KO mutant alphaIIb beta3 constitutively expressed the PMI-1 epitope. Our present data suggest that Asp163 of the alphaIIb subunit is one of the critical residues for ligand binding.