One of promising photorechargeable electrode, which has two functions of photovoltaic and electrical energy storage, is a composite film of mesoporous TiO2 and conducting polymer polyaniline. Galvanostatic charge/discharge characteristics of the TiO2-polyaniline composite were examined to reveal how fast the film was charged. The film with a specific capacity 60-120 mAh g–1 was found to be fully charged at high charging rate 20 mA cm–2 which is comparable to high performance solar cells. Such high charging rate was achieved by the compact polyaniline layer covering the large specific surface area of mesoporous TiO2 film.

We have developed a method for epitaxial growth of C60 thin films on tetracene single crystals. The crystal orientation of the C60 film was examined by reflection high energy electron diffraction (RHEED) and X-ray diffraction (XRD). In-situ observation by RHEED revealed that the C60 crystallizes from the very initial stage of the deposition (0.1 nm). A 6-fold symmetric pattern, which was observed in a XRD polar scan, can be taken as direct evidence for the epitaxial growth of C60 commensurate with the tetracene (001) surface lattice.

Periodically textured back reflectors with hexagonal dimple arrays are applied to thin-film microcrystalline silicon (μc-Si:H) solar cells for enhancing light trapping. The period and aspect ratio of the honeycomb textures have a big impact on the photovoltaic performance. When the textures have a moderate aspect ratio, the optimum period for obtaining a high short circuit current density (JSC) is found to be equal to or slightly larger than the cell thickness. If the cell thickness exceeds the texture period, the cell surface tends to be flattened and texture-induced defects are generated, which constrain the improvement in JSC. Based on these findings, we have fabricated optimized μc-Si:H cells achieving a high active-area efficiency exceeding 11% and a JSC of 30 mA/cm2.

Single-crystalline organic solar cells were investigated. Rubrene single crystals made by train sublimation method were used for the active layer of the solar cells. Typical solar cell characteristics and external quantum efficiency (EQE) were observed with the film thickness of several micrometers. In spite of their large film thickness, the EQE spectra showed no screening effect, which means that absorbed photons efficiently converted to electric charges. This can be attributed to the extended exciton diffusion due to uniform and trap free characteristic of rubrene single crystal.

Background and objectives: Endothelial function plays a key role in determining the clinical manifestations of atherosclerosis. Recent reports have shown that healthy elderly subjects with higher trait anxiety tend to have heightened risks of atherosclerotic lesions and cardiovascular disease. The present study was intended to examine whether an association exists between trait anxiety and endothelial function in healthy young and elderly subjects.

Methods: This study examined 26 young male and 30 elderly male subjects using brachial artery flow-mediated dilation (FMD) – a non-invasive ultrasound method – to evaluate endothelial function by measuring the dilation responses of vascular smooth muscle to the nitric oxide produced by endothelial cells following hyperemia.

Results: A significant negative correlation was observed between the State and Trait Anxiety Inventory (STAI)-trait score as a parameter of anxiety and the percentage change of FMD (%FMD) in the elderly subjects, but not in the young subjects. The elderly subjects showed significantly lower %FMD than the young subjects.

Conclusion: These results suggest the possibility that trait anxiety is a predisposing risk factor for cardiovascular damage that might, over a long period, induce atherosclerotic lesions.

We are constructing a fully automatic observation system named RIBOTS (RIken-Bisei Optical Transient Seeker). We aim to detect optical flashes and early afterglows of Gamma-ray bursts (GRB) with RIBOTS. We are constructing RIBOTS with a small telescope because a quick pointing to the burst is essential for our purpose. RIBOTS is linked to the GRB alert system provided by the HETE-2 satellite.

We are investigating well-ordered highly crystalline thin films made using organic molecular beam deposition (OMBD) since it is important to control the formation mechanism at the initial growth process. Then, we developed a new in situ technique of energy dispersive grazing incidence X-ray diffraction utilized within an ultrahigh vacuum system. This technique (in situ ED-GID) makes it possible to examine the crystal structure, orientation and morphology of organic thin films during deposition without any damage to the film. In the present review, we examined the growth process of thin films of functional organic dyes, fullerene (C60) and p-sexiphenyl (6P) by using this in situ ED-GID. The crystal strucutre and molecular orientation in epitaxially-grown thin films were confirmed during the initial stages of growth. Also, the morphology of C60 thin films was examined during the deposition. As a result, it was confirmed that the decay curves of X-ray fluorescence indicate different island growth in C60 thin films.