Feasibility of using U to reconstruct close-in fallout deposition from the Hiroshima atomic bomb

The first results on the feasibility of using ²³⁶U to reconstruct the level and spatial distribution of close-in fallout deposition from the Hiroshima A-bomb are reported, coupled with the use of global fallout ¹³⁷Cs and ^239 + 240Pu. The results for global fallout ²³⁶U in soil samples (0-30 cm) from Ishikawa prefecture showed that the deposition density of ²³⁶U from the global fallout can be accurately evaluated using AMS. All deposited ²³⁶U, ¹³⁷Cs and ^239 + 240Pu appeared to have been recovered using 30-cm cores. It was also noted from the depth profiles for ²³⁶U/^239 + 240Pu and ²³⁶U/¹³⁷Cs ratios that the downward behavior of ²³⁶U in the soil was apparently similar to that of ^239 + 240Pu, while the ¹³⁷Cs was liable to be retained in upper layers compared with ²³⁶U and ^239 + 240Pu. The accumulated levels were 1.78 × 10¹³ atoms m^− 2 for ²³⁶U, 4340 Bq m^− 2 for ¹³⁷Cs and 141 Bq m^− 2 for ^239 + 240Pu. The ratios of ²³⁶U/¹³⁷Cs and ²³⁶U/^239 + 240Pu were (4.10 ± 0.12) × 10⁹ and (1.26 ± 0.04) × 10¹¹ atoms Bq^− 1, respectively. Results of ²³⁶U, ¹³⁷Cs and ^239 + 240Pu measurements for the seven soil cores (0-30 cm) from Hiroshima were discussed on the basis of ratios of ²³⁶U/¹³⁷Cs and ²³⁶U/^239 + 240Pu by comparing with those from the background area in Ishikawa, indicating that the global fallout dominates the current level of ²³⁶U accumulation in soil in the Black-rain area around Hiroshima after the Hiroshima bomb, and the contribution of the close-in fallout ²³⁶U produced by the Hiroshima A-bomb seems difficult to observe.     

Novel Pt/La1−xBixOF/SBA-16 catalysts for liquid-phase phenol oxidation

Novel catalysts of Pt/La_1−xBi_xOF/SBA-16 (SBA-16: Santa Barbara Amorphous No. 16) were synthesized, and their catalytic activities for phenol decomposition in the liquid phase were investigated. Lanthanum oxyfluoride (LaOF) was selected as the promoter due to its contribution to the smooth migration of oxygen species in the lattice and the acceleration of phenol adsorption on the catalyst surface. Reducible Bi³⁺ ions were introduced in the LaOF lattice to provide oxygen supply ability to LaOF. Among the prepared catalysts, the highest activity was obtained for the 7 wt% Pt/16 wt% La_0.99Bi_0.01OF/SBA-16 catalyst, which could remove 97% of phenol after 5 h of reaction at 80°C in an open-air atmosphere.     

Mixed powder coating film using thermoplastic polyester and its alkaline resistance

To improve alkaline resistance, a newly mixed powder coating film using thermoplastic polyethylene terephthalate (PET) was investigated. Two kinds of polyvinyl butyral (PVB) and two kinds of polyamide (PA) were chosen as the secondary polymer. The melting temperatures (T _ms) of these materials were lower than that of primary PET polymer so the mixed powder coating was able to form a dual phase film through a fluidized bed coating process. Microscope and Fourier transform infrared spectroscopy (FTIR) observations revealed that the dual phase structure was indeed successfully formed and there was a secondary layer over the entire surface area of the film. This mixed powder coating film significantly enhanced the alkaline resistance to an environment filled with NaOH solution at 40°C in which a secondary material would be effective in protecting the film. With regard to both alkaline resistance and film formability, PET/PVB was superior to the PET/PA mixture.     

Nanoparticle formation in H2O/N2 and H2O/Ar mixtures under irradiation by 20 MeV protons and positive corona discharge

To investigate the contribution of ions to gas nucleation, we have performed experiments on the formation of water droplets in H₂O/N₂ and H₂O/Ar gas mixtures by irradiation with a 20 MeV proton beam and by positive corona discharge. The size of the formed nanoparticles was measured using a differential mobility analyzer equipped with a Faraday cup electrometer. Using the proton beam, droplets around 10 nm in diameter were observed for both positively and negatively charged particles, but none were found when the corona discharge was used. This implies the importance of the presence of both positive and negative ions for the formation of nanosize droplets, which attract each other by Coulomb interactions, enhancing the collision frequency and leading to the formation of the 10 nm droplets.     

Determination of traction-separation laws on an acrylic adhesive under shear and tensile loading

Structural acrylic adhesives are of special interest because those adhesives are cured at room temperature and can be bonded to oily substrates. To use those adhesives widely for structural bonding, it is necessary to clarify the methodology for predicting strengths of bonding structures with those adhesives. Recently, cohesive zone models (CZMs) have been receiving intensive attentions for simulation of fracture strengths of adhesive joints, especially when bonded with ductile adhesives. The traction-separation laws under mode I and mode II loadings require to estimate fracture toughness of adhesively bonded joints. In this paper, the traction-separation laws of an acrylic adhesive in mode I and mode II were directly obtained from experiments using Arcan type adhesively bonded specimens. The traction-separation laws were determined by simultaneously recording the J-integral and the opening displacements in the directions normal and tangential to the adhesive layer, respectively.     

Measurement of strain distributions near the steel/epoxy interface by micro-Raman spectroscopy under tensile load condition

Micro-Raman spectroscopy was applied for evaluating the stress distributions in the vicinity of the interface of the steel/epoxy bonded joint under tensile loading condition. Herein, single-walled carbon nanotubes (SWNTs) embedded in a polymer can be used as a mechanical sensor, in which the position of the D* Raman band varies with the strain or stress transferred to SWNTs from the surrounding matrix. In order to evaluate the strain distributions, however, it is required to elucidate the effect of the multiaxial stress on the D* band shift, because a multiaxial stress field appears in the vicinity of the interface and, the validity of this method has been confirmed only under uniaxial loading condition. Hence, at first, the D* band shift of a bulk epoxy/SWNT composite was measured under biaxial loading condition using a cruciform-type specimen. It was found that the D* band shift could be standardized in terms of the strain in the polarized direction even though under the biaxial condition. Then, on the basis of the result, this method was applied for evaluating the strain distributions of the steel/SWNT composite bonded joints under uniaxial tensile loading condition. The observation indicated that the strain singularity appeared in the vicinity of the interface, similar to the results of the finite-element analysis, and the observed strain almost agreed with calculated one in the range of 0.03–10 mm distance from the interface.     

Preparation of Lead Lanthanum Zirconate Titanate (PLZT, (Pb,La)(Zr,Ti)O3) Fibers by Sol-Gel Method

Lead lanthanum zirconate titanate (PLZT, (Pb,La)(Zr,-Ti)O₃) ceramic fibers were prepared by the sol-gel method from a solution of lead acetate trihydrate, lanthanum isopropoxide, zirconium n -propoxide, and titanium isopropoxide that contained 2-methoxyethanol as the solvent. The sols obtained from the solution were concentrated at 156°-174°C for 2 h. Concentration at higher temperatures resulted in more-viscous sols of higher specific gravities. The concentration resulted in the formation of spinnable sols, which had viscosities >10⁵ mPas and exhibited Newtonian flow properties. These spinnable sols were formed to be so stable that no change in viscosity and spinnability was observed for more than three months when stored in a sealed container at room temperature. Gel-to-ceramic fiber conversion was investigated by means of X-ray diffractometry, infrared spectroscopy, and thermal analysis. Single-phase perovskite PLZT ceramic fibers 5-200 μm in diameter and >20 cm in length were obtained. Scanning electron microscopy (SEM) observation and Brunauer-Emmett-Teller (BET) measurement showed that heat treatment of the fibers at a lower rate resulted in the formation of fibers of denser microstructure. Although the SEM image of the cross section of the fibers revealed a relatively dense microstructure and a laser beam could be transmitted through a fiber 6 mm in length, BET measurement of the fibers indicated that the fibers had more than a few percent of open porosities, and scattering of light was observed in the laser-beam guiding test.     

Solid solubility of silicon and germanium in aluminium under pressure

The solid solubility of silicon and germanium in aluminium under pressure are investigated using the microscopic electronic theory based on pseudopotentials and using the virtual crystal approximation. Obtained results for the lattice constant and the solid solubility under pressure in the Al-Si and Al-Ge systems are in good agreement with the few available experimental data, in spite of our not introducing any adjustable parameter except for the lattice constant of pure aluminium crystal. The heat of solution and the pressure-volume relation in the Al-Si and Al-Ge systems are presented theoretically.     

High density packaging technology ultra thin package & new tab package

As electronic devices become more highly integrated, the demand for small, high pin count packages has been increasing. We have developed two new types of IC packages in response to this demand. One is an ultra thin small outline package (TSOP) which has been reduced in size from the standard SOP and the other, which uses Tape Automated Bonding (TAB) technology, is a super thin, high pin count TAB in cap (T.I.C.) package. In this paper, we present these packages and their features along with the technologies used to improve package reliability and TAB. Thin packages are vulnerable to high humidity exposure, especially after heat shock.1 The following items were therefore investigated in order to improve humidity resistance: (1) The molding compound thermal stress, (2) Water absorption into the molding compound and its effect on package cracking during solder dipping, (3) Chip attach pad area and its affect on package cracking, (4) Adhesion between molding resin and chip attach pad and its affect on humidity resistance. With the improvements made as a result of these investigations, the reliability of the new thin packages is similar to that of the standard thicker plastic packages.     

Synthesis and properties of carbons dispersed with α-iron particles from divinylbenzene-vinylferrocene

α-Iron-dispersed carbon was synthesized, through pressure pyrolysis of divinylbenzene-vinylferrocene above 750°C, and by reduction of magnetite-dispersed carbon. Divinylbenzenevinylferrocene copolymer was pyrolysed at 125 MPa above 750°C to yield carbons dispersed with α-iron accompanied by cementite. Magnetite in the carbon matrix was reduced to α-iron after heat treatments at 500°C in a flow of hydrogen. Carbons synthesized by the pressure pyrolysis of divinylbenzene-vinylferrocene at 800°C and 125 MPa contained iron-compound particles up to 200 nm, whereas the median diameter of α-iron particles in the carbon matrix after reduction treatments was 20 nm. α-Iron-dispersed carbon had a Curie temperature of 770°C. The saturation magnetization of iron-dispersed carbon increased with increasing the pyrolysis temperature of divinylbenzene-vinylferrocene copolymer, and reached a constant value of 183 e.m.u.g⁻¹ at 800°C. The saturation magnetization of α-iron-dispersed carbon after the reduction treatment revealed practically the theoretical value of α-iron. Carbons finely dispersed with only α-iron particles were synthesized successfully by reduction of magnetitedispersed carbons.