Atomic mechanisms of superionic conductivity in fluorite

The subsequent melting/crystallization of the two sub-lattices of CaF₂ is explored by molecular dynamics simulations. Both, heating from 100 K and cooling from 2500 K encompasses two transitions, i.e. the melting/recrystallization of the fluoride sub-lattice and the of whole crystal at different temperatures. Solid state F^? ion conductivity is observed in a temperature range of about 1500–2000 K which reflects a reasonable agreement with the experiment. A systematic study of fluoride migration revealed the atomistic mechanisms of the spontaneous formation of Frenkel defects, followed by void translocation and terminated by recombination of interstitial fluoride ions and vacancies.     

Pseudotetrahedral polyhaloadamantanes as chirality probes: synthesis,separation, and absolute configuration

Pseudotetrahedral, conformationally as well as configurationally stable 1-bromo-3-chloro-5-fluoro- (4) and 1-bromo-3-chloro-5-fluoro-7-iodoadamantane (5) (and some related compounds) were prepared by our recently devised phase-transfer catalytic halogenation protocol; the optical antipodes of 4 were separated by HPLC on chiral phase in ee > 99%, and the absolute configurations were assigned by matching observed and computed circular dichroism spectra. Structure 5 is the first chiral aliphatic hydrocarbon containing all stable (nonradioactive) halogens; its structure was proven by NMR spectroscopy and by X-ray crystal data. We emphasize that the combination of experiment and theory is very powerful in assigning absolute configurations even for molecules without typical chromophors, with small values for the optical rotation, and without an atom at the stereogenic center.     

Exponential smoothing — I

Some new insights and results for exponential smoothing with application to forecasting and parameter estimation. Multidimensional exponential smoothing is described by a Kalman filter model with a limiting stationary gain matrix.     

A properly invariant theory of infinitesimal deformations of an elastic Cosserat point

Summary In the context of a mechanical theory of a Cosserat point developed by Green and Naghdi [1=Quart. J. Mech. and Appl. Math.,44, 335–355 (1991)], this paper establishes a properly invariant theory for infinitesimal deformations. The invariant theory is valid for an elastic Cosserat point with an arbitrary number of directors. Its construction is based on a method developed by Casey and Naghdi [2=Arch. Rational Mech. Anal.,76, 355–391 (1981)] for unconstrained non-polar elastic bodies.     

The non-intermediacy of benzo[1,2-d:2,3-d']bistriazole during the diazotization of a 4-aminobenzotriazole

Labeling studies with ¹⁵N demonstrate that a diazonium ion prepared from a 4-aminobenzotriazole does not cyclize to a tricyclic intermediate.