Topology optimization of hyperbolic metamaterials for an optical hyperlens

This paper presents a level set-based topology optimization method for the microstructural design of an optical hyperlens. The resolution of conventional optics is generally diffraction limited, but the diffraction limit can be overcome by a hyperlens that converts evanescent waves to propagation waves, utilizing a cylindrical geometry to magnify the subwavelength features of imaged objects, which allows such features to be resolved beyond the diffraction limit at the hyperlens output. To support electromagnetic waves that contain information of subwavelength features, the hyperlens must have material properties that include a positive permittivity in the angular direction and a negative permittivity in the radial direction. Here, an energy-based homogenization method is used to obtain the effective permittivity of a metamaterial hyperlens unit cell. A level set-based topology optimization is applied so that the boundaries of the structure are clearly expressed. Moreover, a finite element mesh regeneration scheme is used to precisely capture the boundaries of the metal and dielectric materials of the unit cell that will ultimately form the hyperlens. The optimization algorithm uses the finite element method (FEM) to solve the equilibrium and adjoint equations. Optimum design examples for the design of a hyperlens microstructure are provided to confirm the utility and validity of the presented method.     

Wave-induced liquefaction and instability of offshore monopile in a drum centrifuge

This paper discusses the instability of an offshore monopile in association with wave-induced liquefaction of sand beds. Centrifuge wave tests in a drum channel were performed with viscous scaling introduced such that the time-scaling laws for fluid wave propagation and consolidation of the soil were matched. The relationships between liquefaction and the start and development of monopile instability in a sand bed under wave loading were investigated. The monopile started significant structural rocking when liquefaction occurred and progressed to one-third of the monopile embedment depth. The residual displacement of the pile increased markedly with the downward progress of the liquefied zone, eventually leading to the collapse of the pile. The characteristics of the onset of liquefaction around the monopile were also investigated. It was found that liquefaction first took place at the sides of the monopile rather than at the front or rear presented to the direction of the travelling waves, which highlights the importance of the rotation of the principal stress axes induced in the sand bed under the passage of progressive waves. The experimental results further demonstrated the effect of embedment of the pile in a dense layer. It was found that embedding the pile in the dense layer with thickness equal to or more than half of the pile embedment depth was effective in preventing the significant inclination and collapse of the pile. The present study also clarified the effects of scour protection around the monopile on wave-induced liquefaction and pile instability. It was found that the scour protection increased the liquefaction resistance depending on the diameter ratios of the scour protection and the pile, however, it could not prevent the collapse of the monopile once liquefaction occurred. These results show the importance of soil stratification on the wave-seabed-structure interaction in light of wave-induced liquefaction.     

Dietary PlsEtn Ameliorates Colon Mucosa Inflammatory Stress and ACF in DMH-Induced Colon Carcinogenesis Mice: Protective Role of Vinyl Ether Linkage

Ethanolamine plasmalogen (PlsEtn), a sub-class of ethanolamine glycerophospholipids (EtnGpl), is a universal phospholipid in mammalian membranes. Several researchers are interested in the relationship between colon carcinogenesis and colon PlsEtn levels. Here, we evaluated the functional role of dietary purified EtnGpl from the ascidian muscle (87.3 mol% PlsEtn in EtnGpl) and porcine liver (7.2 mol% PlsEtn in EtnGpl) in 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) in vivo, and elucidated the possible underlying mechanisms behind it. Dietary EtnGpl-suppressed DMH-induced aberrant crypt with one foci (AC1) and total ACF formation (P < 0.05). ACF suppression by dietary ascidian muscle EtnGpl was higher compared with dietary porcine liver EtnGpl. Additionally, dietary EtnGpl decreased DMH-induced oxidative damage, overproduction of TNF-α, and expression of apoptosis-related proteins in the colon mucosa. The effect of dietary ascidian muscle EtnGpl showed superiority compared with dietary porcine liver EtnGpl. Our results demonstrate the mechanisms by which dietary PlsEtn suppress ACF formation and apoptosis. Dietary PlsEtn attained this suppression by reducing colon inflammation and oxidative stress hence a reduction in DMH-induced intestinal impairment. These findings provide new insights about the functional role of dietary PlsEtn during colon carcinogenesis.     

Sex pheromones from male forewings of the Common Grass Yellow Eurema mandarina

Journal of Chemical Ecology - The common grass yellow Eurema mandarina has a characteristic patch (sex brand) composed of specialized scales (androconia) and wing intermembranous cells on the...     

Synthetic Biomarker Design by Using Analyte‐Responsive Acetaminophen

The use of synthetic biomarkers is an emerging technique to improve disease diagnosis. Here, we report a novel design strategy that uses analyte‐responsive acetaminophen (APAP) to expand the catalogue of analytes available for synthetic biomarker development. As proof‐of‐concept, we designed hydrogen peroxide (H₂O₂)‐responsive APAP (HR‐APAP) and succeeded in H₂O₂ detection with cellular and animal experiments. In fact, for blood samples following HR‐APAP injection, we demonstrated that the plasma concentration ratio [APAP+APAP conjugates]/[HR‐APAP] accurately reflects in vivo differences in H₂O₂ levels. We anticipate that our practical methodology will be broadly useful for the preparation of various synthetic biomarkers.     

Evaluation of Spaceborne SiC Mirror Materials Using Samples Cut from the Periphery of a Mirror Body

The Japan Aerospace Exploration Agency has studied large-scale, lightweight mirrors constructed of SiC-based materials as a key technology for future earth observations and astronomical missions. One of the most important technical issues for large-scale ceramic components is their quality stability (viz., differences in material properties depending on the part and the processing), which might influence the structural and/or thermal reliability through unforeseen deformation and breakage. In this study, the authors used a simple, low-cost method for evaluating the properties of SiC mirror materials. Using mechanical testing, thermodilatometry, and microstructural analysis on samples cut from the periphery of a prototype 800-mm-diameter mirror body, the overall quality of the mirror body material was determined.     

QoE assessment of fairness in networked game with olfaction: influence of time it takes for smell to reach player

In this paper, we carry out QoE (Quality of Experience) assessment of fairness between players in a networked game with olfaction. In the assessment, we investigate the influence of the time it takes for a smell to reach a player on the fairness. As the networked game, we deal with a fruit harvesting game in which two players play in a 3D virtual space, and we change the time it takes for a smell to reach a player by generating constant delays at two terminals. As a result, for example, we illustrate that the fairness is hardly damaged when the constant delays are smaller than about 500 ms.     

Reproducibility of Aluminum Foam by Combining Sintering and Dissolution Process with Precursor Foaming Process

A preliminary study of the reproducibility of aluminum foam was performed. Aluminum foam was fabricated by a sintering and dissolution process. It was found that aluminum foam containing a blowing agent can be fabricated without the decomposition of the blowing agent, namely, the densified aluminum foam can be used as a foamable precursor for refoaming. By heat treatment of the densified aluminum foam containing the blowing agent, pores were reproduced in the aluminum.     

Synthesis and structure–property relationships of novel thiazole‐containing poly(amide imide)s with high refractive indices and low birefringences

The primary objective of this study was to investigate the structure–property relationships in high‐performance polymers with high refractive indices and low birefringences. A series of novel poly(amide imide)s (PAIs) were synthesized from a thiazole‐containing diimide–diacid monomer and various aromatic diamines. The influence of the pendant phenyl substituents on the optical properties of these PAIs was studied by comparison with the analogous polymers containing methyl groups. The PAIs exhibited excellent solubility and good thermal stability. The optical transmittances of the PAI films at 450 nm were higher than 75%. The combination of the thiazole units, thioether linkages and pendant phenyl rings provided the PAIs with high average refractive indices of 1.7361–1.7536 and low birefringences of 0.0066–0.0097 at 632.8 nm. © 2014 Society of Chemical Industry