Interaction of Near-Field Light with Ordered Polystyrene Spheres: Experimental Studies

We have experimentally observed the interaction of near-field light excited in a total internal reflection geometry with a periodic two-dimensional array of polystyrene spheres. The angular- and frequencyscanned attenuated-total-reflection (ATR) method was employed to observe the interaction. ATR spectra indicate that there is an easy axis and a difficult axis for the light propagation. When light is incident toward the easy axis, resonant dips appear in the ATR spectra. The experimental results were compared with those obtained by finite-difference time-domain analysis. The numerical results obtained by this method are able to explain a part of the experimental ones. Parts of the dips in the ATR spectra were considered to stem from propagating and whispering-gallery (WG) modes. That is, the propagation of the WG-modes over several spheres may enhance the coupling between the spheres and the incident light, and consequently may induce resonant structures in the ATR spectra.This paper was originally presented at the 5th International Conference on NEAR FIELD OPTICS and RELATED TECHNOLOGIES (NFO-5), which was held on December 6–10, 1998 at Coganoi Bay Hotel, Shirahama, Japan, in cooperation with the Japan Society of Applied Physics and Mombusho Grant-in Aid for Scientific Research on Priority Areas “Nearfield Nano-optics” Project, sponsored by Japan Society for the Promotion of Science.     

Instrumentation of high temperature and pressure reaction system with continuous flow and its hyphenation to a liquid chromatograph.

A continuous flow-type hydrothermal reaction system, in which both temperature and pressure were rapidly and dynamically controlled, was constructed. It is called a real time high temperature and pressure reaction system (RT-HighTP). The RT-HighTP was hyphenated with liquid chromatograph (RT-HighTP-LC) to achieve prompt analysis of the reaction products. The RT-HighTP system produced stable pressure under the supercritical and subcritical phases (%RSD < 3%). The RT-HighTP-LC was able to change the hydrothermal condition rapidly. The hydrothermal products under four conditions were analyzed within 70 min. Further, the hydrothermal products of lignin was easily taken out using the sample collecting loop and analyzed by an external instrument of GC/MS.     

Fine structure and phase transition behavior of fluorinated comb copolymers

The fine structure in the solid state and phase transition behavior of newly synthesized comb copolymers having fluorocarbon and hydrocarbon side‐chains were investigated by temperature controlled wide angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC). From the WAXD profiles, two kinds of short spacing peaks based on the formation of the subcell for fluorinated and hydrogenated side‐chains were confirmed at 5.0 and 4.1 Å, respectively. Furthermore, two kinds of endothermic peaks, which corresponded to melting peaks of both side‐chain crystals, appeared in heating process of the DSC thermograms. From these experimental findings, the phase separation structure having the independently packed immiscible side‐chain crystalline was formed in the whole polymer crystal. In addition, it was found that these comb polymers formed highly ordered (double) layer structure estimated using WAXD and small angle X‐ray scattering (SAXS). These fluorinated comb copolymers form a monolayer on the water surface and their transferred film with phase‐separated structure at nanometer size on solid. There were hydrogenated domains at 10–20 nm diameter scales in these phase separated surface structure of monolayers. From these experimental results, these copolymer monolayers are expected to be used as a new molecular device such as nanolithography based on the surface patterning of polymer nanomaterials. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 416–425, 2006     

Structural and photo-luminescence properties of nanocrystalline silicon films deposited at low temperature by plasma-enhanced chemical vapor deposition

Nanocrystalline silicon (nc-Si) films were prepared by a plasma-enhanced chemical vapor deposition method at a deposition temperature below 220 °C with different dynamic pressures (P_g), hydrogen flow rates ([H₂]), and RF powers, using SiH₄/H₂/SiF₄ mixtures. We examined the photo-luminescence (PL) spectra and the structural properties. We observed two stronger and weaker PL spectra with a peak energies around E_PL = 1.8 and 2.2-2.3 eV, respectively, suggesting that the first band was related to nanostructure in the films, and another band was associated with SiO-related bonds. The nc-Si films with rather large PL intensity was obtained for high [H₂] and/or low pressure values, However, effects of [H₂] are likely to be different from those of P_g. The average grain size (δ) and the crystalline volume fraction (ρ) at first rapidly increase, and then slowly increase, with increasing P_g. Other parameters exhibited opposite behaviors from those of δ or ρ. These results were discussed in connection with the changes in the PL properties with varying the deposition conditions.     

Measurement of dissolved oxygen based on enhanced cerium(IV) chemiluminescence.

The reaction of Ce(IV) with pyrogallol caused chemiluminescence, which was enhanced by dissolved oxygen. Dissolved oxygen in water was able to help in the determination by enhancing the chemiluminescence intensity. The limit of detection calculated from 3sigma was 43 micromol/dm3, and the relative standard deviation was 1.2% at 613 micromol/dm3 (n = 5). The results obtained for natural and tap water samples were compared with those provided by conventional methods; the agreement between them corroborated the usefulness of the proposed method. The chemiluminescence mechanism was studied by examining the effect of interference with Cl- and measuring the chemiluminescence spectrum. The chemiluminescence emitter, however, could not be identified.     

Codes from curves with total inflection points

The concept of pure gaps of a Weierstrass semigroup at several points of an algebraic curve has been used lately to obtain codes that have a lower bound for the minimum distance which is greater than the Goppa bound. In this work, we show that the existence of total inflection points on a smooth plane curve determines the existence of pure gaps in certain Weierstrass semigroups. We then apply our results to the Hermitian curve and construct codes supported on several points that compare better to one-point codes from that same curve.      

Magnetic properties and structure of FePt/FeMn multilayers

A systematic study of the magnetic properties by ion beam sputter-deposition system, was conducted in conjunction with the structure of FePt/FeMn multilayers fabricated onto MgO(0 0 1) substrates. Both parallel and perpendicular exchange biases were observed in the multilayers and were found to decrease drastically, as the deposition temperature is higher than 350 °C, which is evidently due to the interdiffusion at the interface. The thickness dependence study shows that the perpendicular magnetic anisotropy observed in the multilayers originates from surface anisotropy, being consistent with the decrease of perpendicular magnetic anisotropy as the deposition temperature is increased. The difference between parallel and perpendicular blocking temperatures that was clearly observed, is possibly due to the spin canting out of plane at the interface.     

Magnitude-redshift relation with varying dark-energy density

The magnitude-redshift test is applied to cosmological models in extended theories of gravity containing extra terms in the Lagrangian which give rise to an evolving dark-energy component. Two classes of models are considered: one based on generalized scalar-tensor theory and the other on curvature corrections to the metric tensor. Results are compared to recent observational data of Type Ia supernovae. The predictions of both kinds of models may provide better fits to the data depending on dimensionless free parameters of order ∼ 0.01−0.1.     

Preliminary quantitative analysis of myocardial fatty acid metabolism from fluorescent X‐ray computed tomography imaging

Fluorescent X‐ray computed tomography (FXCT) using synchrotron radiation reveals the cross‐sectional distribution of specific elements in biomedical objects. The aim of this study was to investigate the feasibility of FXCT imaging to assess the myocardial metabolic state quantitatively. Hearts labelled with non‐radioactive iodine myocardial fatty acid agent 15‐p‐(iodophenyl)‐3‐methylpentadecanoic acid (BMIPP) from cardiomyopathic and normal hamsters were imaged. FXCT images were compared with optical microscope images. Myocardial fatty acid metabolism enhanced with BMIPP was clearly depicted by FXCT, which showed an almost homogeneous image for normal and a heterogeneous image for cardiomyopathic hearts. Morphological structures of the heart such as the left ventricle and myocardial wall were also visualized by FXCT. Optical microscopy showed no fibrosis in normal and slight interstitial fibrosis in cardiomyopathic hearts. In the case of cardiomyopathy, the area of significantly reduced BMIPP uptake was 39% in the short axis of the mid‐left ventricle in the FXCT image, whereas a slight interstitial fibrosis of around 12% was recognized by optical microscopy for the same slice. This result indicated that reduced BMIPP uptake was caused by the myocardial fatty acid metabolic abnormality, not by the fibrosis in cardiomyopathy. Thus, FXCT images might be used to assess the quantitative metabolic analysis in small animal models of heart diseases.