Since the first scientific article about "fairy rings" in 1675 and subsequent studies reviewed in 1884, this phenomenon has been a mystery attributed to "fairies". [1] The tendency of all fungi to grow outward from the point of germination of the spore results in circular colonies in a widely varying group of fungi. Fairy rings are zones of stimulated grass growth. They appear as more or less continuous, circular bands of turfgrass that are darker green and faster growing than adjacent plants of the same species (Figure 1 A). These belts of greener plants can range from 10 to 30 cm wide, and the diameter of the circles they form is generally between 0.9 and 3.7 m. Fungi are responsible for this growth stimulation; presumably through the saprophytic action of the fungus mycelium, the protein portion of nonliving organic matter in the soil is decomposed to ammonia. The ammonia combines with other compounds, or is used as a substrate by successive bacteria to generate nitrites and nitrates. The resulting accumulation of nitrogen in the soil in a form readily available to higher plants causes the typical growth pattern of conspicuous bands of taller, darker green plants. [1,2] We questioned this accepted notion, even if it is partially true, and thus investigated the possibility of a specific plantgrowth-regulating substance(s) being produced by the fungi. We cultured a fairy-ring-forming fungus, Lepista sordida, examined the effect of the culture on the growth of turfgrass, and found that the culture supernatant promoted plant growth. L. sordida is widespread in northern temperate zones throughout the world, [3] including the campus of our university where this study was conducted ( Figure S1 in the Supporting Information).First, to confirm that our L. sordida strain exhibits growthpromoting activity, the cultivated mycelia were placed under bentgrass seedlings (Agrostis palustris) in a deep petri dish and incubated for three weeks. Grass treated with the fungus grew taller than untreated grass (Figure 1 B). Isolation of the active compound from the fungus was guided by its growth-regulating activity on bentgrass. The liquid-cultured fungus was filtered, the filtrate was fractionated by repeated chromatography, and the fractions were tested for their growth-regulating activity. This lead to the isolation and purification of the active compound, 2-azahypoxanthine (AHX; Figures 2 A, B, S2 and S3). Although AHX has been reported as a photolytic degradation product from an antitumor drug, dacarbazine (5-(3,3-dimethyltriazeno)imidazole-4-carboxamide) [4] and has been synthesized, [5] this is the first reported isolation of AHX from a natural source.AHX elongated the shoots and roots of bentgrass seedlings (Figure 2 B). The effect of AHX on shoots was observed at 0.2 and 1 mm and on roots at 0.05 and 0.2 mm. In order to confirm the presence of AHX in the interaction between the fungus and bentgrass (Figure 1 B and Figure S4)

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The mechanism of NiSi2/Si interface formation on (100)Si is examined. The interface roughness between NiSi2 and Si strongly depends on the substrate impurity species. A smooth interface is formed on As-doped Si, but the interface is highly faceted on the {111} plane on BF2-doped Si. The covalent radius of the impurity atoms strongly affects the interface formation. An interfacial distorted layer is observed only at the NiSi2/As-doped Si interface. This distorted layer could reduce the lattice strain between NiSi2 and Si. These results demonstrate the possibility of realizing a homogeneous epitaxial interface.

Demand for low-power ULSIs for mobile electronic equipment is increasing rapidly. To reduce power consumption, lower operating voltage and minimized device size (or count) is essential. To lower the actual threshold voltage and lower the operation voltage, SO1 MOSFET with gate-body connection is proposed [I].However, the circuit architecture that affords the maximum advantage of the body controlled SO1 MOSFET is not reported.This SO1 CMOS pass-gate logic offers the lowest operation voltage and reduced transistor dimensions.

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