Molecular simulations were carried out to elucidate the influence of structural heterogeneity and of the presence of extra-framework cations and water molecules on the adsorption of methane in Engelhard titanosilicates, ETS-10 and ETS-4. The simulations employed three different modeling approaches, (i) with fixed cations and water at their single crystal positions, (ii) with fixed cations and w...

p-biphenylyl, o-biphenylyl, and 1-naphthyl azides were deposited in argon at low temperature in the presence and absence of HCl. In the absence of HCl, the known electronic and vibrational spectra of the corresponding triplet nitrenes, azirines, and didehydroazepines were observed, whereas in the presence of HCl, photolysis of these azides produces new electronic spectra assigned to the corresp...

We have examined the effects of a variety of monovalent cations on K channel gating in squid giant axons. The addition of the permeant cations K, Rb, or Cs to the external medium decreases the channel closing rate and causes a negative shift of the conductance-voltage relationship. Both of these effects are larger in Rb than in K. The opening kinetics of the K channel are, on the other hand, un...

We developed a capillary zone electrophoresis method with indirect UV detection for determination of ammonium cations and alkali and alkaline earth metal cations in jellyfish. As the background electrolyte, a mixture of N-methylbenzylamine, citrate, and 18-crown-6 was used for the complete separation of all analyte cations. The limits of detection were 0.13 - 0.34 mg l(-1) at a signal-to-noise ...

We present a formal method of functional program develop ment based on step by step transformation In their most abstract form speci cations are essentially predicates that relate the result of the speci ed program to the free variables of that pro gram In their most concrete form speci cations are simply programs in a functional programming language Development from abstract speci cations to p...

The asymmetric unit of the title compound, C18H15N6 (3+)·3Cl(-)·2.5H2O, contains two independent (1,3,5-triazine-2,4,6-tri-yl)tripyridinium cations. Both cations are approximately planar, the r.m.s. deviations of fitted non-H atoms being 0.045 and 0.051 Å. In the crystal, extensive O-H⋯Cl, O-H⋯O, N-H⋯Cl and N-H⋯O hydrogen bonds and weak C-H⋯Cl and C-H⋯O inter-actions link the organic cations, C...

The asymmetric unit in the structure of the title compound, C25H22NO2 (+)·Br (-)·0.5CH2Cl2·0.5H2O, comprises two pseudosymmetry-related cations, two bromide anions, a di-chloro-methane molecule and a water mol-ecule of solvation. The two independent cations are conformationally similar with the comparative dihedral angles between the central pyridine ring and the three benzene substituent rings...

The asymmetric unit of the title compound, C18H23N2O(+)·NO3 (-)·0.5H2O, contains two independent 4-{4-[eth-yl(2-hy-droxy-eth-yl)amino]-styr-yl}-1-methyl-pyridin-1-ium cations, two nitrate anions and one lattice water mol-ecule. In the cations, the pyridine ring is twisted with respect by 7.98 (12) and 18.42 (10)° to the benzene ring. In the crystal, the cations, the anions and the lattice water...

We have developed and validated a new force field for cations in zeolites, which explicitly distinguishes Si and Al atoms, as well as different types of oxygens in the framework. Our new force field gives excellent agreement with experimental data on cation positions, site occupancies and vibrational frequencies. Energy minimizations show that Na cations in site I are not at the centers of hexa...

2 October, 1996 ISSN 1100{0686 Forms of Logic Speci cations: A Preliminary Study Kung-Kiu Lauy Mario Ornaghi Dept of Computer Science DSI University of Manchester Universita' degli studi di Milano Manchester M13 9PL Via Comelico 39/41, Milano United Kingdom Italy [email protected] [email protected] Abstract There is no universal agreement on exactly what form a speci cation sho...