No abstract

On the substrate carrying a sub-wavelength grating covered with a thin metal layer, a fluorescent dye-labeled cell was observed by fluorescence microscope. The fluorescence intensity was more than 20 times greater than that on an optically flat glass substrate. Such a great fluorescence enhancement from labeled cells bound to the grating substrate was due to the excitation by grating coupled surface plasmon resonance. The application of a grating substrate to two-dimensional detection and fluorescence microscopy appears to offer a promising method of taking highly sensitive fluorescence images.

The ability to precisely control the pattern of metallic structures at the micro‐ and nanoscale for surface plasmon coupling has been demonstrated to be essential for signal enhancement in fields such as fluorescence and surface‐enhanced Raman scattering. In the present study, a series of silver coated gratings with tailored duty ratio and depth and a periodical pitch of 400 nm are designed and implemented. The influence of the grating profile on plasmonic properties and the corresponding enhancement factor are investigated by angular scanning measurement of reflectivity and fluorescence intensity and by finite difference time domain simulation. The application of the substrate in the enhanced fluorescence imaging detection of labeled protein is also investigated. This substrate has a wide range of potential applications in areas including biodiagnostics, imaging, sensing, and photovoltaic cells.

We studied the dielectric relaxation behavior of low mass compounds (LMC) mixed in polystyrene (PS). Specifically, LMCs that are used are alkyl‐cyanobenzene (nCBz, n = 0), alkyl‐cyanobiphenyl (nCB, n = 0, 1, 3, 5, and 7), and alkyl‐cyanoterphenyl (nCT, n = 5), where n represents the number of carbon atoms of the normal alkyl groups of the LMCs. Owing to a much larger dipole moment of the cyano group than that of PS, only motions of the LMCs were observed. In a blend of 5CT (5 wt %)/PS, single relaxation process designated as α was observed. On the other hand, in nCB (5 wt %)/PS, partially overlapped two relaxation processes (α and β) were observed in the order of decreasing temperature. We assigned the α process to cooperative motions between the LMC molecules and the PS segments, and the β process to spatially restricted motions of the LMC molecules in the glassy state. In 0CBz (8 wt %)/PS, the α and β processes were observed in distinct temperature regions and the intensity of the α peak was comparable to that of pure PS, indicating that the 0CBz molecules do not move cooperatively with the PS segments. We conclude the existence of two critical sizes (I and II) of LMC in relation to cooperativity: when an LMC molecule is smaller than the size‐I, the motions of the LMCs and PS segments decouple each other, but above the size‐I, they become cooperative. Above the size‐II, the spatially restricted motion (β‐process) of LMC does not occur. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 967–974, 2006

Composites of LiF and lithium-free manganese compounds (MnF 2 and MnO x ) were prepared by high-energy ball milling and their electrochemical activities as cathode were investigated. Within the voltage range of 1.5 -4.8 V, MnO x /LiF composites exhibited reversible reactivity with a sloping voltage profile, while MnF 2 /LiF composites showed no reactivity. Reversible Li + extraction from the MnO x /LiF composites was observed in a full cell configuration with graphite anode, where total Li + balance was monitored by chemical analysis of the anode and the cathode. Exsitu X-ray diffraction and X-ray absorption fine structure (XAFS) experiments further confirmed that during the first charge LiF is split electrochemically and the Mn oxidation state changes accordingly, but the MnO x /LiF remained amorphous. Composites containing the redox oxide and the lithium compound as two separate solid phases could be used as a source of Li + and it offers a new type of cathode materials for lithium-ion batteries. IntroductionLithium-ion batteries (LIB) are being adopted into the emerging large-scale applications such as electric vehicles and load leveling systems. These applications are much more demanding than the mobile electronics and it is now recognized that breakthroughs allowing the use of new types of high energy density electrochemical reactions with more than one electron transfer per transition metal ion are required. At present, all cathodes in lithium-ion batteries contain the transition metal and lithium in one open framework, which also contains oxygen anions as building blocks of the crystal lattice. However, some theoretical studies have proposed that replacing oxygen anions with fluoride anions may in principle enable the development of new class high voltage cathodes, because fluorine with its highest electronegativity is expected to bring higher redox potential than that of the oxide cathodes (1 -3).