Scapolite : alkali atom configurations , antiphase domains , and compositional Yariations
Electrostatic energy calculations on an intermediate scapolite indicate that Na+ should prefer to be adjacent to Clanions and Ca2* to be adjacent to CO3radicals. The calculations also indicate that short-range ordering of NarCl and CaaCO3 clusters is energetically favored and might give rise to antiphase domains. Electrical neutrality considerations on the anion/radical site in scapolite suggest that the unusual compositional variations observed in the marialite-meionite series are the result of crystallographic constraints on the two possible independent exchange reactions in scapolite: NaCICaCO-3 and NaSie6-Ai. The compositions of naturally occurring scapolites may be explained in terms of the scapolite composition that represents local charge balance between Ca2*, Na* cations and Cl-, COIanions.
Crystal structure of a sodium and chlorine‐rich scapolite
Relations intermolkculaires La chaine contient deux atomes d'hydrog6ne particuli6rement liants, H(35) et H(36) fix6s sur l'azote quaternaire. D'autre part celui de l'hydroxyle, H(31), est souvent actif. Dans le propranolol, l'alpr6nolol et l'6ph6drine, tous trois forment des liaisons avec l 'anion CI-. Dans l'isopr6naline, le groupement quaternaire se lie soit b. l 'anion SO42-, soit aux groupements O H ph6noliques tandis que les groupements hydroxyle fix6s sur C(13) sont en relation avec l'anion, l'eau d'hydratation ou un autre hydroxyle. Enfin dans la noradr6naline, le groupement quaternaire est li6 ft. l 'anion CI-. Entre les noyaux aromatiques hydrophobes les interactions sont g6n6ralement faibles mais dans les cat6cholamines, les hydroxyles des radicaux -C6Ha (OH)2 sont souvent en relation avec l'anion (interactions de type O . . . H N et O H . . . CI-). Conclusion
Time lapse photography of clouds from high altitude balloons.
Time lapse pictures of clouds taken by cameras flown at altitudes of 30 km on balloons provide valuable insights into the convection and electrification of cloud systems. Simple camera arrangements for taking such pictures are described.