[Identification of fresh and old vertebral compression fractures by MRI].

OBJECTIVE: To analyze and explore the value of MRI in distinguishing fresh from old vertebral compression fractures. METHODS: The features of MRI in 43 cases with compression fractures of thoracic or lumbar vertebral bodies were analyzed. MRI sequences included T1WI, T2WI and STIR. RESULTS: Fifty-five vertebral bodies in total were found compression fractures in 43 cases. Forty-six vertebral bodies, which showed low signals or low signals mixing a few high signals on T1WI, high signals on T2WI and significantly high signals on STIR, were identified as fresh compression fractures. Nine vertebral bodies were identified as old compression fractures, because they showed the same signals as normal vertebral bodies on T1WI, T2WI and STIR. CONCLUSION: MRI could accurately distinguish fresh and old vertebral compression fractures, so it is valuable for the distinguishment in forensic identification.

XAFS studies and computational simulation of calixcrowns-caesium complexes in solution.

Caesium L(3)-edge XANES (X-ray absorption near-edge structure) and EXAFS (extended X-ray absorption fine structure) have been evaluated as means of probing the local structure and the interaction of caesium ions with BPC6 {1,3-alternate bis(2-propyloxy)calix[4]arenecrown-6}, BOC6 {1,3-alternate bis(octyloxy)calix[4]arenecrown-6} and BisC6 (1,3-alternate calix[4]arene bis-crown-6) in NPME (o-nitrophenyl methyl ether) or OA (n-octyl alcohol). The XANES results indicate that the molecular symmetry is enhanced as the caesium ions are embedded. The EXAFS spectra demonstrate that the coordination numbers (N) and average distances (R) from the central caesium ion to the O atoms are: for BPC6, N = 7.0, R = 3.22 Angstroms (in NPME), and N = 7.0, R = 3.23 Angstroms (in OA); for BOC6, N = 6.8, R = 3.28 Angstroms (in NPME), and N = 6.9, R = 3.27 Angstroms (in OA); for BisC6, N = 6.9, R = 3.21 Angstroms (in NPME). Density functional theory at the triple-zeta adding polarization basis set level was used to simulate the BPC6, BOC6 and BisC6 coordination with the caesium ions. Data show that the seven-oxygen-configuration average distances from the central caesium ion to the O atoms are R = 3.38 for BPC6, R = 3.40 for BisC6 and R = 3.39 for BOC6.