Dielectric nanostructures for control of electromagnetic waves

High refractive index dielectric nanoantennas have emerged as a promising unit for improving optical nanodevices by compensating the drawbacks of plasmonic nanoantennas, which have played a key role in nanophotonics to date. The features of high refractive index dielectric nanoantennas, such as low energy losses, excitation of strong magnetic resonances and enhancement of electric field inside and outside the particle, are expected to provide novel methods to manipulate electromagnetic waves in the nanometer scale. In this thesis, we theoretically explore and experimentally demonstrate a variety of nanostructures based on high refractive index dielectric nanoantennas to aim at the efficient and tuneable control of electromagnetic waves in linear and nonlinear manners. Firstly, asymmetric Si dimers are investigated to achieve unidirectional forward scattering with high efficiency. An electric or magnetic dipole mode is excited in each particle constituting the asymmetric dimer at the same wavelength. The interference between these two dipolar modes can direct the scattered field selectively into the forward direction with high scattering efficiency. Secondly, we investigate metasurfaces built of array of Si nanodimers to obtain switching from high transmission to reflection depending on the incident polarization. The different linear polarization direction of the incident light can alter the hybridization modes of the constituent Si dimers and, hence, the effective permittivity and permeability of the metasurface. The resulted overlap and separation of the electric and magnetic dipolar resonances facilitates the control over the switching between high transmission and reflection. Thirdly, asymmetric Si dimers are explored to obtain tuneable control of directional scattering either in the left or right direction from the incident axis. Our theoretical analysis reveals that the electric or magnetic dipoles excited perpendicular to the dimer axis are mainly responsible for the tuneable scattering. Experimental demonstration of the scattering tuneability is carried out along the substrate by using back focal plane techniques combined with a prism coupling setup. Fourthly, we show that the third harmonic generation from a high refractive index dielectric nanoantenna can be significantly improved by adding a metallic component to build a metal-dielectric hybrid nanostructure. In this way, the plasmonic resonance of a Au nanoring can boost the anapole mode excited in a Si nanodisk, strongly enhancing the electric field inside the Si nanodisk. As a result, high third harmonic intensity and conversion efficiency can be achieved even in nanometer scale. Our findings on how we can attain the efficient and tuneable control of electromagnetic waves using high refractive index dielectric nanostructures will contribute to opening the new paths towards the realization of novel optical nanodevices.Open Acces

HIC-5: A Mobile Molecular Scaffold Regulating the Anchorage Dependence of Cell Growth

HIC-5 is a multidomain LIM protein homologous to paxillin that serves as a molecular scaffold at focal adhesions and in the nucleus. It forms mobile molecular units with LIM-only proteins, PINCH, and CRP2 and translocates in and out of the nucleus via a nuclear export signal (NES). Of note, NES of HIC-5 is distinctive in its sensitivity to the cellular redox state. Recently, the mobile units of HIC-5 have been suggested to be involved in the regulation of the anchorage dependence of cell growth. On loss of adhesion, an increase in reactive oxygen species in the cells modifies NES and stops shuttling, which leads to cell-cycle control. More specifically, the system circumvents nuclear localization of cyclin D1 and transactivates p21Cip1 in detached cells, thereby avoiding anchorage-independent cell growth. Thus, the HIC-5-LIM only protein complex has emerged as a fail-safe system for regulating the anchorage dependence of cell growth

Estimation of microphytobenthic resuspension fluxes in a shallow lagoon in Hokkaido, Japan

We conducted field sampling in a subarctic shallow lagoon (Hichirippu Lagoon) in the eastern part of Hokkaido, Japan. We investigated the chemical composition of the water column, sediment, and sinking particles collected by the sediment trap. The standing stock of chlorophyll a (Chl-a) in the water column and surface sediment were 0.4 to 9.3 and 35.9 to 184 mg m−2, respectively. Using stable isotope analysis, the contribution rate of microphytobenthos to the sinking particles was found to range from 63 to 74%. The average Chl-a content in the sinking particles was significantly lower than that of the water column. Our results suggest that the contribution of phytoplankton present in the water column to the Chl-a collected in the traps is likely to be negligible. We assumed that the Chl-a fluxes obtained in this study were microphytobenthic resuspension fluxes. The daily flux of Chl-a accounted for 47.0 to 1,270% of the total standing stock of Chl-a in the water column. The mean relative percentage of daily Chl-a flux divided by the standing stock of Chl-a in the sediment was 6.5%, which indicates that approximately 7% of the microphytobenthos present in the sediment was resuspended, and 93% of the total succeeded at escaping the winnowing action. Although the resuspension phenomenon had little effect on the population of microphytobenthos, the resuspended microphytobenthos had a major impact on the total micro algal biomass in the water column. This is the first direct estimate of microphytobenthic resuspension flux in shallow estuaries

Modeling of Brittle Crack Propagation/Arrest Behavior in Steel Plates

AbstractTo prevent brittle cracks from causing fatal damage to steel structures, it is needed that steels have enough crack arrestability. However, the brittle crack propagation/arrest behavior has not been explained theoretically enough from the aspect of energy balance and especially the long crack problem has remained as an important unsolved issue for some decades. The authors propose a new model based on local fracture stress criterion to solve the long crack problem. The model considers crack closure effect by uncracked side ligaments formed due to relaxation of plastic constraint progressing with SIF increasing. A simultaneous equation composed of four equations, which formulate local fracture condition, strain hardening, yield point, and dynamic SIF considering side ligaments, is solved to simulate a crack propagation in the model. To validate the model, we compared model simulations with some experiments. Some of them were conducted under the long crack problem condition and obtained the result that they showed good agreements, even under the long crack problem condition. This implies the long crack problem can be explained from the aspect of side ligament development due to the relaxation of plastic constraint

A Unique Case of Adenoid Cystic Carcinoma of the Left Main Bronchus

A unique case of adenoid cystic carcinoma of the left main bronchus is reported

Profile of Transforming Growth Factor-β Responses During the Murine Hair Cycle

Transforming growth factor-β (TGF-β) appears to promote the regression phase of the mammalian hair cycle, in vivo in mice and in organ culture of human hair follicles. To assess the relationship between TGF-β activity and apoptosis of epithelial cells during the murine hair cycle, we identified active TGF-β responses using phospho-Smad2/3-specific antibodies (PS2). Strong, nuclear PS2 staining was observed in the outer root sheath throughout the anagen growth phase. Some bulb matrix cells were positive for PS2 during late anagen. Extensive, but weak, staining was observed in this region at the anagen-catagen transition. We also examined expression of TGF-β-stimulated clone-22 (TSC-22), which is associated with TGF-β-induced apoptosis of some cell lines. Recombinant rat TSC-22 was used to generate a rabbit anti-TSC-22 antibody useful for immunohistochemistry. TSC-22 RNA accumulation and immunoreactivity were observed in follicles throughout the murine hair cycle, including the dermal papilla and lower epithelial strand of late-catagen hair follicles. Neither the expression pattern nor the presence of nuclear TSC-22 correlated with the sites of apoptosis, suggesting that TSC-22 is not an effector of apoptosis in mouse catagen hair follicles. These studies support a complex role for TGF-β in regulating the regression phase of the cycle, with potential for indirect promotion of apoptosis during the anagen–catagen transition

Characterisation of secondary metabolites associated with neutrophil apoptosis

We studied changes in secondary metabolites in human neutrophils undergoing constitutive or tumour necrosis factor (TNFalpha) stimulated apoptosis by a combination of high-performance liquid chromatography (HPLC) and NMR spectroscopy. Our results show that in contrast to freshly isolated neutrophils, neutrophil cells aged for 20 h in vitro had marked differences in the levels of a number of endogenous metabolites including lactate, amino acids and phosphocholine (PCho). There was no change in the concentration of taurine or glutamate and the ATP/ADP ratio was not affected. Levels of glutamine and lactate actually decreased. Identical changes were also observed in neutrophils stimulated to undergo apoptosis over a shorter time period (6 h) in the presence of TNFalpha and the phosphatidylinositol-3-kinase inhibitor wortmannin (WM). The changes in the concentration of PCho suggest possible activation of phospholipase associated with apoptosis or a selective failure of phosphatidycholine synthesis. The increased levels of apoptosis obtained with WM+TNFalpha, compared to TNFalpha by itself, suggest a synergistic effect by these compounds. The acceleration in rate of apoptosis probably arises from suppression by WM of pathway(s) that normally delay the onset of apoptosis. Changes in PCho and other endogenous metabolites, if proven to be characteristic of apoptosis in other cell systems, may permit non-invasive quantification of apoptosis.

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熱帯, 亜熱帯産果実のPineapple, Mango, Papaya, Avocado, Orange, Grapefruitについて, 糖類と有機酸の定性定量を行った。糖類はガスクロマトグラフィーにより, 有機酸はガスクロマトグラフィーおよびシリカゲルクロマトグラフィーで分析した。主なる糖類はD-fructose, α-D-glucose, β-D-glucose, Sucroseの4種類であった。各果実糖類のそれぞれの総含有量はPineapple 2338mg/100g, Papaya 4882mg/100g, Mango 219mg/100g, Avocado 129mg/100g, Orange 1497mg/100g, Grapefruit 2018mg/100gであった。PineappleにはSucroseが最も多量に含有し, PapayaのSucrose含有量はPineappleに相反し少なかった。OrangeとGrapefruitの各糖類の組成は類似していた。有機酸についてはすべての果実にシュウ酸, マロン酸, フマール酸, リンゴ酸, クエン酸が多少にかかわらず検出された。総有機酸含有量は, Pineapple 342mg/100g, Papaya 101mg/100g, Mango 63mg/100g, Avocado 65mg/100g, Orange 239mg/100g, Grapefruit 426mg/100gであった。Pineappleの酸の大部分はリンゴ酸とクエン酸であり, OrangeとGrapefruitの酸はクエン酸で占められていた。We determind sugars and organic acids of such tropical and subtropical fruits as pineapples, mangos, papayas, avocados, oranges and grapefruits. The sugars were analysed by gas chromatography, and the organic acids by liquid and gas chromatography. Following four sugars, D-fructose, α-D-glucose, β-D-glucose, and sucrose were major sugars. The total contents of these four sugars in the fruits were, 2338mg/100g for pineapples, 4882mg/100g for papayas, 219mg/100g for mangos 129mg/100g for avocados, 1497mg/100g for oranges and 2018mg/100g for grapefruits. Pineapples contained sucrose most, contrary to papayas. The contents of the four sugars in oranges and grapefruits were comparable each other. Oxalic, malonic, fumaric, malic, and citric acids were detected, more or less, in all the fruits. The total contents of the acids were 342mg/100g for pineapples, 101mg/100g for papayas, 63mg/100g for mangos, 65mg/100g for avocados 239mg/100g for oranges, and 426mg/100g for grapefruits. Malic and citric acids comprised the large portion of the acids of pineapples. Citric acids comprised that of oranges and grapefruits