No abstract

ABSTRACT--To purify the kuchijirosho causative agent derived from brains of kuchijirosho-affected tiger pufferTakifugu rubripes, the method of density gradient centrifu gation using iodinated contrast medium, Angio-Conray (solium iotalamata solution), was used. The extracts of kuchijirosho-affected brains were loaded on 3-55% gradient of Angio-Conray, and centrifuged at 280,000•~g for 2 h.The lethal activity to grass puffer Takifugu niphobles was found in a fraction with a density around 1.096 g/cm3. The infectivity of the extracts of kuchijirosho-affected brains was lost by treatment with ether, UV-irradiation, propiolacton or proteinase K.

In this study, an experimental apparatus was developed where the relative humidity (RH) and oxygen concentration could be controlled between 0.01-10%RH and 1-100000 ppm, respectively. This apparatus was used to study the roles of water and oxygen molecules on the friction of carbon nitride (CN X) coatings. The friction properties of Si 3 N 4 balls sliding against CN X (Si 3 N 4 /CN X) under a nitrogen atmosphere were classified into the following three modes according to their average friction coefficients (µ a) and the stability of the friction: Mode I, µ a < 0.05 (stable); Mode II, 0.05 < µ a < 0.3 (stable); and Mode III, 0.3 < µ a (unstable). To achieve a low friction coefficient (e. g. < 0.05), the optimum RH and oxygen concentration were 0.1-1.0%RH and 100-10000 ppm, respectively. Time-of-flight secondary ion mass spectroscopy (TOF-SIMS) showed that hydrogen and hydroxyl radicals derived from water molecules chemisorbed onto the worn surfaces of the CN X coatings. Raman spectroscopy suggested that the structure of carbon on the worn surfaces was different from that of the deposited CN X coating. We concluded that low friction (Mode I) arose from the water and oxygen molecules terminating carbon dangling bonds and structural changes in CN X .

No abstract

No abstract