Plasmon modes in single gold nanodiscs

Optical properties of single gold nanodiscs were studied by scanning near-field optical microscopy. Near-field transmission spectra of a single nanodisc exhibited multiple plasmon resonances in the visible to near-infrared region. Near-field transmission images observed at these resonance wavelengths show wavy spatial features depending on the wavelength of observation. To clarify physical pictures of the images, theoretical simulations based on spatial correlation between electromagnetic fundamental modes inside and outside of the disc were performed. Simulated images reproduced the observed spatial structures excited in the disc. Mode-analysis of the simulated images indicates that the spatial features observed in the transmission images originate mainly from a few fundamental plasmon modes of the disc

Plasma pharmacokinetics after combined therapy of gemcitabine and oral S-1 for unresectable pancreatic cancer

<p>Abstract</p> <p>Background</p> <p>The combination of gemcitabine (GEM) and S-1, an oral 5-fluorouracil (5-FU) derivative, has been shown to be a promising regimen for patients with unresectable pancreatic cancer.</p> <p>Methods</p> <p>Six patients with advanced pancreatic cancer were enrolled in this pharmacokinetics (PK) study. These patients were treated by oral administration of S-1 30 mg/m²twice daily for 28 consecutive days, followed by a 14-day rest period and intravenous administration of GEM 800 mg/m²on days 1, 15 and 29 of each course. The PK parameters of GEM and/or 5-FU after GEM single-administration, S-1 single-administration, and co-administration of GEM with pre-administration of S-1 at 2-h intervals were analyzed.</p> <p>Results</p> <p>The maximum concentration (Cmax), the area under the curve from the drug administration to the infinite time (AUCinf), and the elimination half-life (T1/2) of GEM were not significantly different between GEM administration with and without S-1. The Cmax, AUCinf, T1/2, and the time required to reach Cmax (Tmax) were not significantly different between S-1 administration with and without GEM.</p> <p>Conclusion</p> <p>There were no interactions between GEM and S-1 regarding plasma PK of GEM and 5-FU.</p

The ASTRO-H X-ray Observatory

The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the high-energy universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV. These instruments include a high-resolution, high-throughput spectrometer sensitive over 0.3-2 keV with high spectral resolution of Delta E < 7 eV, enabled by a micro-calorimeter array located in the focal plane of thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5-80 keV, located in the focal plane of multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4-12 keV, with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera type soft gamma-ray detector, sensitive in the 40-600 keV band. The simultaneous broad bandpass, coupled with high spectral resolution, will enable the pursuit of a wide variety of important science themes.Comment: 22 pages, 17 figures, Proceedings of the SPIE Astronomical Instrumentation "Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray

Hitomi (ASTRO-H) X-ray Astronomy Satellite

The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E  >  2  keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month

Ammonia photosynthesis via an association pathway using a plasmonic photoanode and a zirconium cathode

Most conventional photoelectrochemical-based methods for synthesizing NH3 show low selectivity due to the generation of H-2 as a by-product. In principle, two types of reaction mechanisms can occur in the reduction of N-2 to NH3. One is an associative pathway in which N-2 molecules on the catalyst are hydrogenated. The other is a dissociative pathway in which nitrogen and hydrogen react after the cleavage of the strong N-2 triple bond. Understanding the mechanism of NH3 formation on the electrode will facilitate the development of selective and efficient NH3 synthesis techniques. In this study, we constructed a two-electrode system composed of a strontium titanate photocatalytic anode in which the plasmon effect is expressed by plasmonic gold nanoparticles and a zirconium cathode, which was connected to the external circuit to investigate the reaction by electrochemical analysis in addition to analysis of the product. The bias and pH dependences of the reaction were then systematically investigated, and the plasmon-induced synthesis of NH3 on Zr was proposed to proceed via an associative pathway

Visible-Light-Driven α-Allylation of Carboxylic Acids

A boron-catalyzed alpha-allylation of carboxylic acids with allylsulfones under blue LED irradiation conditions is developed. We propose that photoexcitation of catalytically generated boron enediolates induces single-electron transfer to the allylsulfones. Subsequent C-C bond formation through a radical reaction constructs sterically demanding quaternary carbon centers at the position a to the carboxy group. The p-extended ligand on the boron atom is likely the key for efficient photoexcitation of the boron enediolates

Near-IR vibrational dynamics of periodic gold single and pair nanocuboids

We examined vibrational dynamics of periodic gold single and pair nanocuboids with 9 nm separation at 400 nm excitation by near-IR transient absorption spectroscopy. The similar oscillation periods of coherent phonon vibration (77±1 ps) were observed for both nanocuboids while the damping of the pair was faster than that of the single. From the analysis of bleaching peak shift and finite-difference time-domain calculation, the lattice change in coherent phonon vibration was estimated to be ±1% for a quasiextensional and ±3% for an quasibreathing modes of a single nanocuboid. © 2009 American Institute of Physics

Further enhancement of the near-field on Au nanogap dimers using quasi-dark plasmon modes

Metallic nanogap dimers are extremely useful for enhancing surface-enhanced Raman scattering and various nonlinear optical effects employing near-field enhancement effects induced by the localized surface plasmon resonance. However, the metallic nanogap dimers exhibit an intense light scattering due to the strong dipole-dipole interaction between two metallic nanostructures and, therefore, are not necessarily a structural design that exhibits the highest near-field enhancement due to the radiation loss. Here, we propose further enhancement of the near-field on metallic nanogap dimers using quasi-dark plasmon modes. By coupling with gold (Au) nanorods having the same plasmon resonant wavelength, but completely different sizes, a quasi-dark plasmon mode, which reduces the radiation loss slightly, is induced, resulting in the elongation of the plasmon dephasing time. As a result, the signal of surface-enhanced Raman scattering of crystal violet molecules adsorbed on the Au nanogap dimer is enhanced up to about three times as compared to that measured using the Au nanogap dimer without the Au nanorods. Scattering spectrum measurements as well as electromagnetic simulations were performed to clarify the mechanism for further enhancement of the near-field. The proposed coupled plasmonic system is expected to be advantageous, especially in enhancing nonlinear optical effects using plasmonic enhancement effects