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Solid phase crystallization of thin films of undoped amorphous Si prepared by plasma enhanced chemical vapor deposition has been studied by transmission electron microscopy (TEM). From the TEM images, the thermodynamic parameters for the amorphous and crystalline phases were extracted. These parameters were compared with those previously reported for evaporated, chemical vapor deposited, and self-implanted amorphous Si. We conclude that the thermodynamic parameters are very similar for different amorphous Si films, although the initial structure of the films is comparatively different from one to another. To explain this, the existence of an intermediate amorphous state is assumed and discussed.

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A new perovskite related Sr 0.97NbO 3 phase has been synthesized. Although both powder X-ray diffraction and selected area electron diffraction studies suggest a primitive cubic perovskite structure with a p #4.023 A ˚, high resolution powder neutron diffraction reveals a subtle lattice distortion from cubic symmetry. The detailed crystal structure has been refined with the orthorhombic space group P2 1 2 1 2 with a=5.6881 A ˚, b=5.6821 A ˚and c=8.0566 A ˚. The structure is built up from two types of NbO 6 octahedra, one elongated, the other compressed along c. The lattice distortion from cubic symmetry has been found to mainly originate from tilting of NbO 6 octahedra, whereas the √2a p ×√2a p ×2a p superstructure arises from ordering of alternate elongated and compressed octahedra.

The capsid protein (CP) of Cucumber mosaic virus (CMV) is required for cell-to-cell movement, mediated by the 3a movement protein (MP). Deletion of the C-terminal 33 amino acids of the CMV 3a MP (in the mutant designated 3aDC33 MP) resulted in CP-independent cell-to-cell movement, but not long-distance movement. RNA-binding studies done in vitro using isolated bacterially expressed MP showed that the 3aDC33 MP bound RNA more strongly, with fewer regions sensitive to RNase and formed cooperatively bound complexes at lower ratios of protein : RNA than the wild-type (wt) 3a MP. Analysis of the architecture of the complexes by atomic force microscopy showed that the wt 3a MP formed a single type of complex with RNA, resembling beads on a string. By contrast, the 3aDC33 MP formed several types of complexes, including complexes with virtually no MP bound or thicker layers of MP bound to the RNA. Assays showed that protein-RNA complexes containing high levels of either MP inhibited the infectivity and in vitro translatability of viral RNAs. The 3aDC33 MP inhibited these processes at lower ratios of protein : RNA than the wt 3a MP, consistent with its stronger binding properties. The apparent contradiction between these inhibition data and the CP-independent cell-to-cell movement of CMV expressing the 3aDC33 MP is discussed.