Desmoplastic cerebral astrocytoma of infancy (DCAI) presents as a large supratentorial mass consisting of a central cystic component and an enhancing solid component associated with peripheral dural attachment. We report the unusual MR findings of a DCAI that differed from previously reported cases in terms of the presence of calcification, which is not considered a feature of this tumor, and the absence of an enhancing peripheral dural component.
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ABSTARCTWe have fabricated a new multi-channel polycrystalline silicon thin film transistor (ploy-Si TFT), of which structure may be more effectively hydrogenated than conventional multi-channel poly-Si TFT. The new multi-channel TFT has stripe-cuts in gate electrode so that more hydrogen radicals penetrate into the gate oxide and passivate the active poly-Si layer. After 90 min. hydrogenation of the new device, the electrical characteristics such as threshold voltage and field effect mobility are improved more than those of conventional device.The new multi-channel poly-Si TFT, which receives more hydrogen radicals thorough gate oxide than the conventional multi-channel TFT, can be hydrogenated effectively in long channel devices. Besides the improvement of the device characteristics, our experimental results show that the dominant hydrogenation path is the diffusion though the gate oxide.
We propose a novel fabrication method for a room temperature operating single-electron memory using the size and location controlled poly-Si island by lithographic technique and excimer laser annealing.We have patterned tip shaped excimer laser windows and irradiated laser energy through windows for crystallizing amorphous silicon. As a result of laser energy, the poly-Si grains are growing from patterned window side so that the fine grain and isolated large poly-Si quantum dot are inherently formed by well-known ACSLG regime. The oxidation was then performed by RTP at 950 °C for 30 seconds in order to isolate quantum island and fine poly-Si grains for quantum dot. The peaks of the poly-oxide along the poly-Si grain boundaries were lowered during that oxidation and isolated the poly-Si grains and made oxide barriers.
Synthesis of α-Methylene-δ-valerolactones and α-Methylenecyclohexanones via Radical Cyclization of Propiolates and Acetylenic Ketones.-Intramolecular radical cyclization of (I) mediated by stannyl radicals yields the α-methylenecyclohexanone (Va) or the α-methylene-δ-valerolactone (Vb) after hydrolysis. -(LEE, E.; HUR, C. U.; PARK, C. M.; Tetrahedron Lett.
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