Some projective contraction theorems

We give here a necessary and sufficient condition for a subvariety of a projective non-singular variety to be contracted in an algebraic variety which is again non-singular projective, and study some geometric properties of the contraction.     

Determination of peptide φ angles in solids by relayed anisotropy correlation NMR

A solid state NMR method is presented for determination of a backbone dihedral angle φ in peptides, being based on the previously reported method, relayed anisotropy correlation (RACO) NMR [Y. Ishii et al., Chem. Phys. Lett. 256 (1996) 133]. In the present method, the and the dipolar tensors in the system are two-dimensionally (2D) correlated via polarization transfer from to under magic angle spinning (MAS). This method was applied to N-acetyl , -valine, and the H–C–N–H dihedral angle was determined to be 154.0±1.4° or 206.0±1.4°, the former agreeing with the X-ray value of 154±5°.     

Thermoanalytical study on the chlorination of hydrated aluminas and transition aluminas

The chlorination processes of four hydrated aluminas (bayerite, gibbsite, pseudoboehmite, boehmite) and four transition aluminas (η-,γ-,δ-,θ-Al₂O₃) were studied in the presence of active carbon by means of a gas-flow DTA apparatus. In the case of hydrated alumina systems three exothermic peaks appeared at about 230, 460 and 500°C or above, which corresponded to the formation of hydrogen chloride, white needle-like crystals and the chlorination of hydrated aluminas, respectively. On the other hand, in transition alumina systems, only one exothermic peak due to the chlorination of transition alumina appeared at 580–670°C. The relationship between the chlorination behavior and structure of transition aluminas was discussed.