Benchmark experiment of large-angle scattering reaction cross section of iron at 14 MeV using two shadow bars – Comparison of experimental results with ENDF/B-VIII –

ABSTRACT

It is important to perform neutron transport simulations with accurate nuclear data in the neutronics design of a fusion reactor. However, absolute values of large-angle scattering cross sections vary among nuclear data libraries even for well-examined nuclide of iron. Benchmark experiments focusing on large-angle scattering cross sections were thus performed to confirm the correctness of nuclear data libraries. The series benchmark experiments were performed at a DT neutron source facility, OKTAVIAN of Osaka University, Japan, by the unique experimental system established by the authors’ group, which can extract only the contribution of large-angle scattering reactions. This system consists of two shadow bars, target plate (iron), and neutron detector (niobium). Two types of shadow bars were used and four irradiations were conducted for one experiment, so that contribution of room-return neutrons was effectively removed and only large-angle scattering neutrons were extracted from the measured four Nb reaction rates. The obtained experimental results were compared with calculations for five nuclear data libraries including JENDL-4.0, JEFF.-3.3, FENDL-3.1, ENDF/B- VII, and recently released ENDF/B-VIII. It was found from the comparison that ENDF/B-VIII showed the best result, though ENDF/B-VII showed overestimation and others are in large underestimation at 14 MeV.     

The significance of colocalization of plasminogen activator inhibitor-1 and vitronectin in hepatic fibrosis

BACKGROUND: We examined the relationships among vitronectin (VN), plasminogen activator inhibitor-1 (PAI-1), and transforming growth factor beta 1 (TGF-beta 1) in liver diseases to evaluate the presence of plasmin cascade in human hepatic fibrosis. METHODS: Blood and liver tissues were obtained from 57 patients with liver disease. Plasma VN, PAI-1 antigen, and PAI-1 activity levels were evaluated. Biopsied liver specimens were observed by light and electron microscopy after immunohistochemical staining. Morphometric analysis was performed on these specimens. RESULTS: Plasma VN and PAI-1 activity levels decreased significantly with the progression of hepatic fibrosis and were particularly marked in the liver cirrhosis group. Plasma PAI-1 antigen level increased significantly. The immunolocalization of the active form of TGF-beta became more intense with the progression of hepatic fibrosis, whereas that of the dual-stained positive areas of PAI-1 and VN (PAI-1.VN) decreased. There was a positive correlation between TGF-beta and PAI-1, whereas there was a negative correlation between TGF-beta and PAI-1.VN. Immunoelectron microscopy showed the localization of PAI-1-VN in the extracellular space around the sinusoidal cells or surface of aggregating platelets, TGF-beta mainly in Ito cells, and VN in hepatocytes near the focal necrotic area or fibrous septa. CONCLUSIONS: These findings suggest that VN and PAI-1 are related to the active form of TGF-beta and that it is possible that the plasmin cascade is present in the human liver.     

Three-dimensional motion of the upper cervical spine in rheumatoid arthritis

Rheumatoid arthritis frequently contributes to instability of the upper cervical spine. Rotational instability of the upper cervical spine was evaluated in rheumatoid arthritis patients using biplanar x-ray photogrammetry. Three-dimensional cervical motion and the instantaneous axis of rotation of the atlas relative to the axis were evaluated in normal and rheumatoid arthritis patients during axial rotation in the horizontal plane. Anterior atlantoaxial subluxation did not increase during axial head rotation in either the atlantoaxial subluxation or the vertical subluxation groups, while the instantaneous axes of rotation were distributed posteriorly in the dens in the RA-normal group, but were widely scattered in the atlantoaxial subluxation group.     

Advanced process device technology for 0.3-μm high-performancebipolar LSIs

A new method is developed for forming shallow emitter/bases, collectors, and graft bases suitable for high-performance 0.3-μm bipolar LSIs. Fabricated 0.5-μm U-SICOS (U-groove isolated sidewall base contact structure) transistors are 44 μm², and they have an isolation width of 2.0 μm, a minimum emitter width of 0.2 μm, a maximum cutoff frequency (f_T) of 50 GHz, and a minimum ECL gate delay time of 27 ps. The key points for fabricating high-performance 0.3-μm bipolar LSIs are the control of the graft base depth and the control of the interfacial layer between emitter poly-Si and single-Si. The importance of a tradeoff relation between f_T and base resistance is also discussed     

Evaluation technique of gate oxide damage

Gate oxide damage by plasma processing was evaluated using structures with various antenna lengths. The gate oxide damage by plasma processing was found to be monitored quantitatively by measuring the charge to breakdown, Q_BD. From the Q_BD measurements, we have confirmed that the degradation occurs during overetching, not in main etching. Plasma current was calculated from the decrease of Q_BD during the etching. The breakdown spot in the gate oxide was detected by photon emission and TEM. The LOCOS structure plays an important role for the degradation by plasma damage. In this paper, it is demonstrated that the Q_BD method is effective for realizing a highly reliable process against plasma damage     

A 64-Mb DRAM with meshed power line

A 64-Mb dynamic RAM (DRAM) has been developed with a meshed power line (MPL) and a quasi-distributed sense-amplifier driver (qDSAD) scheme. It realizes high speed, t_RAS=50 ns (typical) at V_cc=3.3 V, and 16-b input/output (I/O). This MPL+qDSAD scheme can reduce sensing delay caused by the metal layer resistance. Furthermore, to suppress crosstalk noise, a V_SS shield peripheral layout scheme has been introduced, which also widens power line widths. This 64-Mb DRAM was fabricated with 0.4-μm CMOS technology using KrF excimer laser lithography. A newly developed memory cell structure, the tunnel-shaped stacked-capacitor cell (TSSC), was adapted to this 64-Mb DRAM     

Diffusion Bonded EDM Electrode with Micro Holes for Jetting Dielectric Liquid

This paper describes improvement of machining characteristics of electrical discharge machining of deep slots using a tool electrode which has micro holes for jetting dielectric liquid over the working surface. The tool electrode was made by the diffusion bonding of two copper plates, over an interface on which micro grooves for jetting the dielectric fluid were formed using electrolyte jet machining. In conventional machining, it is difficult to drill micro holes at the end of a slim electrode and circulate the dielectric fluid from the other end. Hence a solid tool electrode is used and periodically lifted up during machining to flush debris particles out of the discharge gap. Use of the newly developed tool electrode was found to shorten the processing time and improve machining accuracy significantly compared with the conventional solid tool electrode. Since the holes are micro, the outlet shapes are not replicated onto the bottom surface of the slot machined.     

Stabilization of SnO2 ultrafine particles by additives

In order to stabilize ultrafine particles of SnO₂ which is essential to obtain high gas sensitivity, a systematic investigation was undertaken regarding the stabilizing effects of 5 at% impregnated foreign additives, consisting of oxides or polyoxy compounds of 31 metals and 3 non-metals. The data of specific surface area, SA, as well as SnO₂ crystallite size, D, evaluated from X-ray diffraction showed that the additives could be classified into several groups according to the effectiveness. The most effective group, consisting of P-Ba, Sm, Ba, P, Mo, W, Ca, Sr, Cr and In, could keepD less than 10 nm even after calcination at 900°C, whereas pure SnO₂ underwent grain growth to haveD of 13 and 27 nm at 600 and 900°C, respectively. Electron microscopy revealed that neck sizes, X, between crystallites were fairly proportional toD(X/D = 0.80). A simple analysis of SA and D data based on a monosized sphere model suggested that each crystallite was coordinated with 3–4.5 neighbours through the necks. The existing state and stabilizing mechanism of additives are discussed in conjunction with the electrical resistance of porously sintered elements.     

Thermal properties of ethylene ionomers

The annealing effect of ethylene ionomers annealed at various temperatures and for various periods was studied by differential scanning calorimetry. Two endothermic melting peaks were observed for all the ethylene ionomers annealed. The melting peak at the lower temperature, which was assigned to bundlelike crystal owing to a Hoffman-Weeks relationship, shifted to a higher temperature with the annealing temperature and period, indicative of recrystallization. There is physical cross-linking consisting of ionic aggregates, such as multiplets and clusters in ethylene ionomers. The crystallization kinetics of ethylene ionomers was fundamentally similar, but different from that of low-density polyethylene. Crystallization and recrystallization suggested a mobile ethylene chain in both amorphous regions and ionic aggregates even in the presence of cross-linking.     

Gel-size dependence of temperature-induced microphase separation in weakly-charged polymer gels

The gel-size dependence of microphase separation in weakly-charged gels of N-isopropylacrylamide (NIPA) and 1-vinylimidazole (VI) copolymers has been investigated using swelling measurement, small-angle neutron scattering (SANS), and dynamic and static light scattering (DLS/SLS). It is known that weakly-charged polymer gels undergo microphase separation in a poor solvent as a result of competing interactions involving hydrophobic attraction versus electrostatic repulsion. The microphase separation is characterized by a scattering maximum in SANS intensity functions of which Bragg spacing, Λ, is around 20-30 nm. However, when gel size was reduced to the order of Λ, no microphase separation was observed. Instead, a typical scattering of isolated spherical particles was clearly observed. On the basis of the experimental evidence, we conclude that microphase separation has its own wavelength independent of gel size, and nanometer-order gels, i.e., nanogels, do not undergo microphase separation.