Perfect coupling of light to surface plasmons by coherent absorption

We show theoretically that coherent light can be completely absorbed and transferred to surface plasmons in a two- or three-dimensional metallic nanostructure by exciting it with the time-reversed mode of the corresponding surface plasmon laser ("spaser"). The narrow-band perfect absorption is a generalization and application of the concept of critical coupling to a nanocavity with surface plasmon resonances. Perfect coupling of light to nanostructures has potential applications to nanoscale probing as well as background-free spectroscopy and ultrasensitive detection or sensing.     

Migration-enhanced epitaxy (MEE) growth of five-layer asymmetric coupled quantum well (FACQW) and its cross-sectional STM observation

The five-layer asymmetric coupled quantum well (FACQW) is a new potential-tailored quantum well that is promising for ultra-fast and ultra-low-voltage optical modulators and switches. FACQW samples were grown by the migration-enhanced epitaxy (MEE) and the conventional molecular beam epitaxy methods with steep and flat heterointerfaces in the monolayer accuracy. They were characterized with the cross-sectional scanning tunneling microscopy (STM). In the cross-sectional STM image, double-stripe structures with different contrast were observed. The stripe area corresponds to the FACQW (about 10 nm wide), sandwiched with the AlGaAs barrier layers (15 nm wide). A dark line observed at the middle of the FACQW stripe area corresponds to the 3-monolayer-thick AlAs layer. The cross-sectional STM images of the high-quality heterointerface FACQW structures were successfully observed for the samples grown by the MEE method. More detailed studies of this kind of cross-sectional STM observations will be very effective to obtain the optimized growth conditions for fine and complicated ultra-thin structures.     

The Mycobacterium avium subsp. paratuberculosis fibronectin attachment protein, a toll-like receptor 4 agonist, enhances dendritic cell-based cancer vaccine potency

In this study, we showed the direct interaction between Mycobacterium avium subsp. paratuberculosis fibronectin attachment protein (FAP) and toll-like receptor4 (TLR4) via co-localization and binding by using confocal microscopy and co-immunoprecipitation assays. FAP triggered the expression of pro- and antiinflammatory cytokines in a TLR4-dependent manner. In addition, FAP-induced cytokine expression in bone marrow-derived dendritic cells (BMDCs) was modulated in part by glycogen synthase kinase-3 (GSK-3). FAP-induced expression of CD80, CD86, major histocompatibility complex (MHC) class I, and MHC class II in TLR4(+/+) BMDCs was not observed in TLR4(-/-) BMDCs. Furthermore, FAP induced DC-mediated CD8(+) T cell proliferation and cytotoxic T lymphocyte (CTL) activity, and suppressed tumor growth with DC-based tumor vaccination in EG7 thymoma murine model. Taken together, these results indicate that the TLR4 agonist, FAP, a potential immunoadjuvant for DC-based cancer vaccination, improves the DC-based immune response via the TLR4 signaling pathway.     

Improvement of high voltage cycling performance and thermal stability of lithium–ion cells by use of a thiophene additive

This study demonstrates that the addition of thiophene improves the cycle life of lithium–ion cells at high voltage. Electrochemical impedance spectroscopy results suggest that addition of thiophene significantly suppresses the increase of the charge transfer resistance that occurs during cycling up to high voltage. Differential scanning calorimetric studies showed that the thermal stability of fully charged LiCoO₂ cathode was also enhanced in the presence of thiophene.     

Rhamnogalacturonan II is a Toll-like receptor 4 agonist that inhibits tumor growth by activating dendritic cell-mediated CD8+ T cells

We evaluated the effectiveness of rhamnogalacturonan II (RG-II)-stimulated bone marrow-derived dendritic cells (BMDCs) vaccination on the induction of antitumor immunity in a mouse lymphoma model using EG7-lymphoma cells expressing ovalbumin (OVA). BMDCs treated with RG-II had an activated phenotype. RG-II induced interleukin (IL)-12, IL-1β, tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) production during dendritic cell (DC) maturation. BMDCs stimulated with RG-II facilitate the proliferation of CD8⁺ T cells. Using BMDCs from the mice deficient in Toll-like receptors (TLRs), we revealed that RG-II activity is dependent on TLR4. RG-II showed a preventive effect of immunization with OVA-pulsed BMDCs against EG7 lymphoma. These results suggested that RG-II expedites the DC-based immune response through the TLR4 signaling pathway.     

A new 2-arylbenzofuran with antioxidant activity from the black colored rice (Oryza sativa L.) bran

From the black colored rice bran of Oryza sativa cv. Heugjinjubyeo, a new 2-arylbenzofuran, 2-(3,4-dihydroxyphenyl)-4,6-dihydroxybenzofuran-3-carboxylic acid methyl ester, oryzafuran (1), was isolated. Its structure has been elucidated on the basis of spectral data. This compound showed strong antioxidative activity in a 1,1-diphenyl-2-picrylhydrazyl free radical scavenging assay.     

Development of a 100-kHz femtosecond high-power laser using down-chirped regenerative amplification

We have developed a 100-kHz high-power downchirped-pulse-amplification (DPA) Ti:sapphire laser. A regenerative amplifier, acoustooptically switched and pumped by a Q-switched green laser, is employed for the high-energy amplification with a high repetition rate. Dispersion control is achieved, based on the DPA technique, by use of a prism-grating stretcher and a SF10 glass compressor. We have obtained 28 μJ 45 fs laser pulses at 100 kHz with a compression efficiency of 95%, and further compression down to 20 fs is possible due to the broad amplified spectrum.