No abstract

No abstract

No abstract

MgO protecting layers, which have high ion induced secondary electron emission coefficient (), are required in order to decrease the firing voltage of plasma displays. Theoretical estimation of ideal value is needed for a design of better protecting layers. In this study, we report our developed calculation method based on a tight-binding quantum calculation and application to an estimation of values of MgO protecting layers. From our calculation results, it was revealed that electron trap sites arising from surface roughness would work as an effective emission sites and increase value. Especially for Xe þ species as induced ion, the value changed drastically by the presence of the trapped electron. It is also suggested that a presence of chemisorbed water on the MgO surface decreases the values because of the contribution of the electrons at the low energy levels originated from surface OH groups. #

Binding of purified Clostridium botulinum type A, C1 and E toxins to cultured cells was studied by an immunocytochemical method. Type A and C1 toxins bound strongly to neuron cultures prepared from brains of foetal mice, but binding of type E toxin was weak. None of the toxin types bound to the feeder layer, composed of non-neuronal cells. The heavy-chain component of the type C1 toxin bound to neurons, but the light chain component did not. Type C1 toxin also bound only to cell lines of neuronal origin. When type C1 toxin [final concentration 4 x 10(2) LD50 (10 ng) per well] was added to primary neuron cultures in 96-well plates, degeneration of neuronal processes and rounding of neuronal somas were observed, but type A and E toxins did not produce such changes. The binding and cytotoxic activities of type C1 toxin were blocked by heat treatment (80 degrees C for 30 min) or by preincubation of the toxin with polyclonal anti-C1 IgG and some of the monoclonal antibodies which neutralized the toxin activity in mice. In the neuronal processes treated with C1 toxin, many degenerated mitochondria, membranous dense bodies and vesicles were observed by electron microscopy; these ultrastructural changes were similar to those of Wallerian degeneration in vivo.

For the analysis of the relationship between carrier transfer properties and morphologies of light-emitting polymers, it is important to investigate carrier transfer pathways. We developed a novel computational method for analysis of carrier transfer pathways by the combination of tight-binding quantum chemistry calculation with Monte Carlo method. This novel method was applied to the prediction of electron transfer in poly(9,9'-dioctylfluorene)(PDOF), which is known as a blue light-emitting polymer. We successfully investigated the electron transfer pathways in PDOF films. We found that the electron transfer mainly occurs in an intra chain, but the inter chain electron transfer was also observed between aromatic rings whose distance was less than 4.0 Å.

No abstract

No abstract