Dynamic response of target electrons upon low and medium energy ion impact

We found that differential scattering cross sections for medium and low energy He⁺ and Ne⁺ impact on high Z-atoms were significantly enhanced compared with those calculated from the inter-atomic potential based on the Hartree–Fock–Slater atomic model coupled with the bare nuclear charge of a projectile. The enhanced scattering cross sections determined experimentally are reproduced well by a simple model that the center of gravity of target electrons is shifted toward the projectile during a large-angle collision. The shift from the target nucleus is expressed as a function of inter-nuclear distance in terms of a dipole moment (Z₁ and Z₂: atomic numbers of projectile and target, : polarizability, e: electron charge). The effective polarizability β (≡Z₁/Z₂) is expressed as a function of ion velocity v [10⁷ cm/s], in the form β = 0.079 exp[−0.46v].     

Evaluation of the interfacial strength of carbon-fiber-reinforced temperature-resistant polymer composites by the micro-droplet test

This paper presents an evaluation method for the fiber/matrix interfacial strength. The interfacial strength is determined by comparing experimental data with numerical simulations. The micro-droplet test is conducted, and the fiber axial stress at the point of interface debonding is obtained. A numerical simulation is performed with ABAQUS using an axisymmetric finite-element model. In the numerical simulation, an accurate value of the thermal residual stress based on the thermo-viscoelasticity and the damage to the resin around the blade-contacting point is considered to simulate the experimental phenomena ideally. In the thermal residual stress analysis, the actual thermal residual stress is calculated by considering the relaxation modulus and the time–temperature superposition principle for the resin. Damage initiation criteria for both dilatational and shear cases, based on continuum damage mechanics, are considered for the resin. Interfacial debonding is simulated using a cohesive zone model, and the interfacial strength is taken as the strength of the cohesive zone element at the simulated fiber maximum stress corresponding to the experimental value.     

<10$$ \bar{1} $$0> Dislocation at a {2$$ \bar{1} $$$$ \bar{1} $$0} low-angle grain boundary in LiNbO3

A LiNbO₃ bicrystal that contains a {2\( \bar{1} \) \( \bar{1} \)0} low-angle grain boundary with both of 2° tilt misorientation and a slight twist misorientation was fabricated, and resulting dislocation structure at the boundary was analyzed by using transmission electron microscopy (TEM) and scanning TEM. The observations revealed that two types of dislocations of b = 1/3 <2\( \bar{1} \) \( \bar{1} \)0> and b = <10\( \bar{1} \)0> are formed at the boundary. A 1/3 <2\( \bar{1} \) \( \bar{1} \)0> dislocation, which dissociates into two partial dislocations with a {2\( \bar{1} \) \( \bar{1} \)0} stacking fault in between, compensates only tilt misorientation of the boundary. On the other hand, it was found that a <10\( \bar{1} \)0> dislocation, which dissociates into three equivalent partial dislocations with b = 1/3 <10\( \bar{1} \)0>, has both edge and screw components in total. That is, the <10\( \bar{1} \)0> dislocations are formed to compensate the twist misorientation of the boundary, in addition to the tilt misorientation. It is interesting that the three partial dislocations from a <10\( \bar{1} \)0> dislocation are arranged in a zigzag pattern with left–right asymmetry. This special configuration is suggested to originate from the presence of stable stacking fault structure on the {2\( \bar{1} \) \( \bar{1} \)3} plane in LiNbO₃.     

Measurement of semi-volatile organic compounds emitted from various types of indoor materials by thermal desorption test chamber method

This paper presents measurements on semi-volatile organic compounds (SVOCs) emitted from building materials, household electric appliances, and indoor products. It is extremely difficult to apply the emission test chamber method to the accurate measurement of SVOCs because they are absorbed by the internal walls of the chamber. The authors have reported on the development of the thermal desorption test chamber method that can measure correctly the emission rates of SVOCs emitted from materials under actual room-air temperature conditions. This method is composed of two measurement steps. In the first step we capture organic compounds emitted as gaseous matter. After removing the test piece from the chamber, in the second step we continuously gather the organic compounds absorbed by the chamber's internal walls while heating the chamber. We have used this method to measure emissions from various objects, and have confirmed that most SVOCs are caught in the second step. In this paper, we also report on our verification of the accuracy of SVOC measurements taken using an emission chamber and describe the emission characteristics of SVOCs.     

Numerical analysis to better understand the mechanism of the effects of ground supports and reinforcements on the stability of tunnels using the distinct element method

In order to understand the mechanism of the effects of ground supports and reinforcements on tunnel stability, numerical simulations are conducted using the distinct element method. Four cases of simulations are carried out in this paper for tunnels excavated in a sandy ground to investigate the effects of (1) dowels and a lining on a single tunnel, (2) dowels and a lining on two parallel tunnels, (3) forepoling and face bolts on a single tunnel face, and (4) forepoling and face bolts on two tunnels which face each other. It is found that the use of ground supports causes a discontinuous ground to behave as a continuous one. In addition, it is revealed that supports help to form ground arches in the sandy ground. Detailed discussions are given considering the stress paths and the stress distributions.     

Effect of fabrication process on characteristics of phosphorescence organic light emitting diodes with methoxy-substituted starburst low-molecule as a host

The effect of dry process and wet process on the characteristics of phosphorescence organic light-emitting devices (OLEDs) employing a phosphorescent dye fac-tris(2-phenylpyridine) iridium(III) (Ir(ppy)₃) doped into a methoxy-substituted starburst low-molecule material methoxy-substituted 1,3,5-tris[4-(diphenylamino) phenyl]benzene (TDAPB) are investigated. The FT-IR and absorption spectra of TDAPB films fabricated by a dry process, and a wet process are almost same, and the PL spectra of those films are different. The carrier transport capability of TDAPB by a dry process is lower than that by a wet process. The photoluminescence intensity of Ir(ppy)₃ doped in TDAPB fabricated by a wet process is higher than that by a dry process. A maximum external current efficiency of more than 20 cd/A and luminance of more than 10,000 cd/m² were obtained. Maximum luminance of devices monotonously decreases with increasing the thickness of a dry-processed emitting layer. The main emission zone of the OLED was located in almost at the center of the emitting layer. The improvement of device performance in the OLED fabricated by a wet process was achieved due to the high efficient energy transfer from TDAPB to Ir(ppy)₃, high carrier transporting capability and the formation of homogeneous film, compared with that fabricated by a dry process.     

Development of an S-doped titania nanotube (TNT) site-selectively loaded with iron(III) oxide and its photocatalytic activities

We investigated an S-doped titania nanotube (TNT) loaded with Fe₂O₃ nanoparticles in order to improve photocatalytic activity of S-doped TNT under visible light irradiation. S-doped TNT was successfully prepared using the solid-phase method at 350 °C under aerated conditions. S-doped TNT showed photoabsorption in the 400–500 nm visible light region and showed photocatalytic activity for oxidation of acetaldehyde under visible light irradiation. Loading of Fe₂O₃ on S-doped TNT remarkably improved the photocatalytic activity of S-doped TNT. PA spectra measurement, which was performed in order to elucidate the mechanism of activity improvement, showed that the efficiency of charge separation between photoexcited electrons and holes was improved because the electrons were trapped by Fe₂O₃. Enhancement of photocatalytic activity was strongly dependent on the site of Fe₂O₃ nanoparticles loaded on TNT. PA spectra measurement showed that the photoexcited electrons transferred to Fe₂O₃ from S-doped TNT under UV light irradiation or to S-doped TNT from Fe₂O₃ under visible light irradiation.     

In vivo Raman study of the living rat esophagus and stomach using a micro-Raman probe under an endoscope

A small endoscope system equipped with a micro Raman probe is developed for in vivo Raman measurements in living rats. The measurements are done under anesthesia and artificial respiration to minimize the impact on the rats. Raman spectra of living rat esophagus and stomach are successfully measured. Our results suggest that the Raman spectra reflect subsurface tissue structure that cannot be distinguished in the endoscope image. After the experiments, rats recover without any aftereffects. It is verified that the Raman measurement using the present system is safe and noninvasive for rats.     

Enzyme-linked immunosorbent assay for nonylphenol using antibody-bound microfluid filters in vertical fluidic operation

We developed an enzyme-linked immunosorbent assay for an endocrine disrupter, nonylphenol, using a microreactor composed of two reaction vessels stacked vertically through a microfluid filter. The filters constructed by deep X-ray lithography possessed 2100 through-bores (phi40 x 200 microm) in polymethylmethacrylate sheets (phi3 mm), which are appropriate for biochemical reactions. Through the optimization of the immunoassay, nonylphenol was quantitatively detected at the range of 0.1-10 ng/ml.     

Simulation of subwavelength metallic gratings using a new implementation of the recursive convolution finite-difference time-domain algorithm

We introduce a new implementation of the finite-difference time-domain (FDTD) algorithm with recursive convolution (RC) for first-order Drude metals. We implemented RC for both Maxwell's equations for light polarized in the plane of incidence (TM mode) and the wave equation for light polarized normal to the plane of incidence (TE mode). We computed the Drude parameters at each wavelength using the measured value of the dielectric constant as a function of the spatial and temporal discretization to ensure both the accuracy of the material model and algorithm stability. For the TE mode, where Maxwell's equations reduce to the wave equation (even in a region of nonuniform permittivity) we introduced a wave equation formulation of RC-FDTD. This greatly reduces the computational cost. We used our methods to compute the diffraction characteristics of metallic gratings in the visible wavelength band and compared our results with frequency-domain calculations.