Ocular Effects of Exposure to 40, 75, and 95 GHz Millimeter Waves

The objective of this study was to develop a model of ocular damage induced by 40, 75, and 95 GHz continuous millimeter waves (MMW), thereby allowing assessment of the clinical course of ocular damage resulting from exposure to thermal damage-inducing MMW. This study also examined the dependence of ocular damage on incident power density. Pigmented rabbit eyes were exposed to 40, 75, and 95 GHz MMW from a spot-focus-type lens antenna. Slight ocular damage was observed 10 min after MMW exposure, including reduced cornea thickness and reduced transparency. Diffuse fluorescein staining around the pupillary area indicated corneal epithelial injury. Slit-lamp examination 1 day after MMW exposure revealed a round area of opacity, accompanied by fluorescence staining, in the central pupillary zone. Corneal edema, indicative of corneal stromal damage, peaked 1 day after MMW exposure, with thickness gradually subsiding to normal. Three days after exposure, ocular conditions had almost normalized, though corneal thickness was slightly greater than that before exposure. The 50% probability of ocular damage (DD₅₀) was in the order 40?>?95?≈?75 GHz at the same incident power densities.     

Metal-induced negative oxide charge detected by an alternating current surface photovoltage in thermally oxidized Fe-contaminated n-type Si (001) wafers

The atomic-bridging type negative oxide charge in SiO₂ is investigated using the Fe-contaminated (001) surface of n-type Si wafers. The investigation is done on the basis of a chemical analysis and a method in which the frequency-dependent alternating current (AC) surface photovoltage (SPV) is measured. At room temperature, an AC SPV appears and gradually increases, saturating after approximately one day (with an Fe concentration on the Si surface of 4.0 × 10¹³ atoms/cm²). The AC SPV eventually becomes inversely proportional to frequency except at very low frequencies (< 10 Hz) corresponding to weak or strong inversion, indicating that the negative Fe induced oxide charge appears in the form of a (FeOSi)⁻ network. Also, in Fe-contaminated n-type Si(001) surfaces thermally oxidized at between 550 and 650 °C for 60 min, strong inversion is unquestionably observed, proving that the (FeOSi)⁻ network survives and that most of the added Fe has segregated into the region closest to the surface of the thin SiO₂ film. At 850 °C and/or for long oxidation times, the AC SPV decreases and ultimately disappears, implying that the (FeOSi)⁻ network has collapsed and may have changed into Fe₂O₃. A model for the metal-induced negative oxide charge in the conventional oxide charge diagram is proposed.     

High‐fat Diet‐induced Intestinal Hyperpermeability is Associated with Increased Bile Acids in the Large Intestine of Mice

Metabolic syndrome is characterized by low‐grade chronic systemic inflammation, which is associated with intestinal hyperpermeability. This study examined the effects of 3 high‐fat diets (HFDs) composed of different fat sources (soybean oil and lard) on the intestinal permeability, tight junction (TJ) protein expression, and cecal bile acid (BA) concentrations in mice, and then analyzed their interrelations. C57/BL6 mice were fed the control diet, HFD (soybean oil), HFD (lard), and HFD (mix; containing equal concentrations of soybean oil and lard) for 8 wk. Glucose tolerance, intestinal permeability, TJ protein expression, and cecal BA concentration were evaluated. Feeding with the 3 HDFs similarly increased body weight, liver weight, and fat pad weight, and induced glucose intolerance and intestinal hyperpermeability. The expression of TJ proteins, zonula occludens‐2 and junctional adhesion molecule‐A, were lower in the colons of the 3 HFD groups than in the control group (P < 0.05), and these changes appeared to be related to intestinal hyperpermeability. Feeding with HFDs increased total secondary BA (SBA) and total BA concentrations along with increases in some individual BAs in the cecum. Significant positive correlations between intestinal permeability and the concentrations of most SBAs, such as deoxycholic acid and ω‐muricholic acids, were detected (P < 0.05). These results suggest that the HFD‐induced intestinal hyperpermeability is associated with increased BA secretion. The abundance of SBAs in the large intestine may be responsible for the hyperpermeability.     

Thermal fatigue of Ag flake sintering die-attachment for Si/SiC power devices

Emerging SiC power semiconductor devices are expected to work under the high temperature condition of 250–300 °C while the operation of Si devices is limited up to 180 °C. The die-bonding materials for emerging SiC power devices hence need to have sufficient capability in such extreme operating environments. In this study, we investigated the thermomechanical reliability of the die-attach technology using Ag flake paste, which can be processed by low-temperature and low-pressure sintering. The Ag flakes start to sinter immediately after the organic dispersant layer is removed from the flake surface at 160 °C, and die-bonding consequently becomes possible. The tested Si die-attachments joining with the paste maintained high strength (23 MPa) up to 1,000 thermal cycles from ?40 to 180 °C. The stable microstructures without crack and no interfacial debonding assure the reliability of the Ag flake paste die-attach of Si. SiC die-attachments also maintained their high strength (24 MPa) up to 1,000 cycles of ?40 and 250 °C, though a slight degradation appeared after 1,000 cycles. The debondings at the sintered Ag flake paste layer/SiC wafer interface were affected to the joining strength with the Ag flake paste. The obtained results indicate that our Ag flake paste die-attach can be applied to both Si and SiC power devices capable of high temperature operations.     

Attraction to Herbivore-induced Plant Volatiles by the Host-foraging Parasitoid Fly <Emphasis Type="Italic">Exorista japonica</Emphasis>

Responses of the tachinid fly Exorista japonica Townsend to odors from corn plants infested with the fly’s host, the larvae of the noctuid moth Mythimna separata (Walker), were examined in a wind tunnel. Naïve female flies showed a higher rate of landing on M. separata-infested corn plants from which the host larvae had been removed than on artificially damaged or intact corn plants. When paper impregnated with a solution of headspace volatiles collected from host-infested plants was attached to intact plants, females landed on the plants at a high rate. Females also responded to intact plants to which had been attached with paper impregnated with a synthetic blend of nine chemicals identified previously in host-infested plants. There was an optimum concentration of the synthetic blend for the females’ landing. Of the nine chemicals identified previously, four [(E)-4,8-dimethyl-1,3,7-nonatriene, indole, 3-hydroxy-2-butanone, and 2-methyl-1-propanol] released only by host-infested plants were classified as a host-induced blend. The other five [(Z)-3-hexen-1-yl acetate, (E)-2-hexenal, hexanal, (Z)-3-hexen-1-ol, and linalool] were classified as a non-specific blend released not only by infested plants but also by artificially damaged or intact plants. In the wind tunnel, E. japonica females did not respond to intact plants to which paper containing a solution of non-specific blend or host-induced blend was attached. However, they showed a high level of response to a mixture of the non-specific and host-induced blends. These results indicate that naïve E. japonica use a combination of non-specific and host-induced blends as an olfactory cue for locating host-infested plants.     

Influence of separated vortex on aerodynamic noise of an airfoil blade

In order to clarify the mechanism by which aerodynamic noise is generated from separated flow around an airfoil blade, the relation between the attack angle and the aerodynamic noise of the blade was analyzed using a wind tunnel experiment and a CFD code. In the case of rear surface separation, the separated vortex which has a large-scale structure in the direction of the blade chord is transformed into a structure that concentrates at the trailing edge with an increase in the attack angle. The aerodynamic noise level then becomes small according to the vortex scale in the blade chord. When the flow is separated at the leading edge, a separated vortex of low pressure is formed at the vicinity of the trailing edge. The pressure fluctuations on the blade surface at the vicinity of the trailing edge become large due to the vortex in the wake. It is considered that the aerodynamic noise level increases when the flow is separated at the leading edge because the separated vortex is causing the fluctuations due to wake vortex shedding.     

Evaluation of mineral admixtures on the viewpoint of chloride ion migration through mortar

Recently, it has been said that deterioration of concrete structures occurs due to migration of ions, such as Cl⁻ or Na⁺, through concrete. In addition, some electrochemical methods which control migration properties through concrete, like desalination or re-alkalization, are becoming more important. However, the mechanisms of ion migration, in electric fields, through concrete are not well understood. Moreover, the effects of mineral admixtures, such as fly ash, silica fume and ground-granulated blast furnace slag on ion migration through concrete have not been closely investigated. From this viewpoint, for the evaluation of mineral admixtures, the properties of chloride ion migration through mortar containing fly ash, silica fume and ground-granulated blast furnace slag have been investigated.     

Recent progress in thermal analysis of polymers: experimental techniques and a new aspect of temperature in measurement of material properties

Thermal analysis has been utilized in polymer research for a long time and its usefulness is widely recognized. High‐performance commercial instruments have driven significant progress in the thermal studies of polymers. On the other hand, new experimental instruments have been developed in laboratories as well. In this paper attention is paid to the latter category. The laboratory‐made instrument focused on the target material and/or phenomena provides data that are not available from other techniques. Experiments using the temperature modulation technique, which has been successfully utilized in laboratory‐made instruments, are introduced in this paper. The temperature modulation technique reveals a new aspect of temperature useful for studies of material properties. © 2016 Society of Chemical Industry     

Carbon Nitride Loaded with an Ultrafine,Monodisperse, Metallic Platinum-Cluster Cocatalyst for the Photocatalytic Hydrogen-Evolution Reaction

For the realization of a next-generation energy society, further improvement in the activity of water-splitting photocatalysts is essential. Platinum (Pt) is predicted to be the most effective cocatalyst for hydrogen evolution from water. However, when the number of active sites is increased by decreasing the particle size, the Pt cocatalyst is easily oxidized and thereby loses its activity. In this study, a method to load ultrafine, monodisperse, metallic Pt nanoclusters (NCs) on graphitic carbon nitride is developed, which is a promising visible-light-driven photocatalyst. In this photocatalyst, a part of the surface of the Pt NCs is protected by sulfur atoms, preventing oxidation. Consequently, the hydrogen-evolution activity per loading weight of Pt cocatalyst is significantly improved, 53 times, compared with that of a Pt-cocatalyst loaded photocatalyst by the conventional method. The developed method is also effective to enhance the overall water-splitting activity of other advanced photocatalysts such as SrTiO₃ and BaLa₄Ti₄O₁₅.