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The finite element method is used to solve Laplace's equation for ion-atom chambers. We first consider a simplified model chamber for which an analytical solution can be obtained; the model chamber serves as a test case to verify the accuracy and convergence of the finite element method. We apply the finite element method to an experimental chamber consisting of five equipotential rings in a grounded cylindrical shell. We determine the strength and homogeneity of the electric field in the region of the chamber where the atoms undergo laser excitation into a Rydberg state. [DOI: 10.1119/1.3000255]

This study addresses the simulation of ion chromatographic (IC) separations performed under conditions where the elution profile consists of a sequence of isocratic and gradient elution steps (referred to as 'complex elution profiles'). First, models for prediction of retention under gradient elution conditions in IC were evaluated using an extensive database of gradient elution retention data. It is shown that one such model is preferred on the basis that it can be used to predict gradient retention times on the basis of isocratic input data. A method is then proposed for using this model for complex elution profiles whereby each step of the elution profile is treated separately and analyte movement through the column is mapped. An empirically based algorithm for predicting peak width under complex elution conditions is also proposed. Evaluation of the suggested approaches was undertaken on a set of 24 analyte anions and 13 analyte cations on 5 different Dionex columns using a range of 5-step complex elution profiles that gave [R.sup.2] values for correlations between predicted and observed retention times of 0.987 for anions and 0.997 for cations. The simulation of separations of anions and cations using a 3-step complex elution profile is demonstrated, with good correlation between observed and predicted chromatograms. The proposed approach is useful for the rapid development of separations when complex elution profiles are used in IC.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2005.09.018 Byline: E. Kallio (a), A. Fedorov (b), E. Budnik (b), T. Sales (a), P. Janhunen (a), W. Schmidt (a), H. Koskinen (a)(q), P. Riihela (a), S. Barabash (c), R. Lundin (c), M. Holmstrom (c), H. Gunell (c), K. Brinkfeldt (c), Y. Futaana (c), H. Andersson (c), M. Yamauchi (c), A. Grigoriev (c), J.-A. Sauvaud (b), J.-J. Thocaven (b), J.D. Winningham (d), R.A. Frahm (d), J.R. Sharber (d), J.R. Scherrer (d), A.J. Coates (e), D.R. Linder (e), D.O. Kataria (e), J. Kozyra (f), J.G. Luhmann (g), E. Roelof (h), D. Williams (h), S. Livi (h), C.C. Curtis (i), K.C. Hsieh (i), B.R. Sandel (i), M. Grande (j), M. Carter (j), S. McKenna-Lawler (k), S. Orsini (l), R. Cerulli-Irelli (l), M. Maggi (l), P. Wurz (m), P. Bochsler (m), N. Krupp (n), J. Woch (n), M. Franz (n), K. Asamura (o), C. Dierker (p) Keywords: Mars; atmosphere; Ionospheres Abstract: We have analysed ion escape at Mars by comparing ASPERA-3/Mars Express ion measurements and a 3-D quasi-neutral hybrid model. As Mars Express does not have a magnetometer onboard, the analysed IMA data are from an orbit when the IMF clock angle was possible to determine from the magnetic field measurements of Mars Global Surveyor. We found that fast escaping planetary ions were observed at the place which, according to the 3-D model, is anticipated to contain accelerated heavy ions originating from the martian ionosphere. The direction of the interplanetary magnetic field was found to affect noticeably which regions can be magnetically connected to Mars Express and to the overall 3-D Mars-solar wind interaction. Author Affiliation: (a) Space Research Unit, Finnish Meteorological Institute, Erik Palmenin aukio 1, P.O. Box 503, FIN-00101 Helsinki, Finland (b) Centre d'Etude Spatiale des Rayonnements, BP-4346, F-31028 Toulouse, France (c) Swedish Institute of Space Physics, Box 812, S-98 128, Kiruna, Sweden (d) Southwest Research Institute, San Antonio, TX 7228-0510, USA (e) Mullard Space Science Laboratory, University College London, Surrey RH5 6NT, UK (f) Space Physics Research Laboratory, University of Michigan, Ann Arbor, MI 48109-2143, USA (g) Space Science Laboratory, University of California in Berkeley, Berkeley, CA 94720-7450, USA (h) Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723-6099, USA (i) University of Arizona, Tucson, AZ 85721, USA (j) Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK (k) Space Technology Ltd., National University of Ireland, Maynooth, Co. Kildare, Ireland (l) Istituto di Fisica dello Spazio Interplanetari, I-00133 Rome, Italy (m) Physikalisches Institut, University of Bern, CH-3012 Bern, Switzerland (n) Max-Planck-Institut fur Aeronomie, D-37191 Katlenburg-Lindau, German (o) Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamichara, Japan (p) Technical University of Braunschweig, Hans-Sommer-Strasse 66, D-38106 Braunschweig, Germany (q) Department of Physical Sciences, University of Helsinki, P.O. Box 64, FIN-00014 Helsinki, Finland Article History: Received 19 April 2005; Revised 12 September 2005

Research has been conducted on the ozone reactions with halite ions XO (sub)2 (super)- (X= Cl or Br). The study of these reactions carried out under pseudo-first-order conditions via the use of the stopped-flow spectroscopy with excess XO (sub)2 (super)- is presented.

Research has been conducted on the water-soluble polymeric single stranded helicate with the sodium ions. The structural analysis of this molecule performed both in solution and in the solid state and its photochemical transformation in solution are discussed.

Research has been conducted on the ligand metathesis silver-assisted reaction of the platinum(II) complex with acetonitrile. The results of the kinetic studies indicate that the silver assistance operates via an associative step.

Research has been conducted on the aquocob(III)alamin. The results of the electrochemical and Raman spectrum analyses indicate that this aquocob(III)alamin can be reduced by nitric oxide in formingaquocob(II)alamin on the electrode surface.

Research has been conducted on the tetraazamacrocyclic ligands. The design of these ligands constructed with the aim to sensitize luminescence of terbium(III) and europium(III) ions in water is described.

Research has been conducted on the derived from oxasilacyclopentane acetals oxarbenium ions. The nucleophile additions to these ions have been carried out and the results indicate that these reaction form the syn stereochemistry about the established carbon-carbon bond.

Research has been conducted on adenosine kinase. The catalytic activity of the kinase from different sources including yeast and plant has been investigated and the results indicate that it increases in the presence of the pentavalent ions.

The authors review the publications on spin catalysis. The topics of interest include spin wave functions and spin states of triads, spin catalysis by radicals, paramagnetic ions as the spin catalysts and the dynamics of the spin catalytic processes.

Research has been conducted on silylated carboxonium ions. The preparation of these ions via the treatment of triethylsilane and triphenylmethyl tetrakis(pentafluorophenyl)borate with ketones, enones, amides, urea and carbonates in solution is described.

Research has been conducted on the gas-phase ammonium ion/alcohol reactions which proceed with configuration inversion. The structural and energetic features of this reactio have been investigated via the computational studies of ammonium ion/alcohol substitution reactions and the results are reported.

Research has been conducted on the 1,3-bridged calix[5]arene crown-6 ethers which bear alkyl, arylalkyl, alkoxyalkyl and alkoxycarbonylmethyl residues. The synthesis of these compounds has been carried out and the results indicate that the calix[5]arene derivatives behave as mono- or ditopic receptors for the isomeric butylammonium ions.

Recently, an approach for the 'top down' sequence analysis of whole protein ions has been developed, employing electrospray ionization, collision-induced dissociation, and ion/ion proton-transfer reactions in a quadrupole ion trap mass spectrometer. This approach has now been extended to an analysis of the [[M + 12H].sup.12+] to [[M + 5H].sup.5+] ions of ribonuclease A and its N-linked glycosylated analogue, ribonuclease B, to determine the influence of the posttranslational modification on protein fragmentation. In agreement with previous studies on the fragmentation of a range of protein ions, facile gas-phase fragmentation was observed to occur along the protein backbone at the C-terminal of aspartic acid residues, and at the N-terminal of proline, depending on the precursor ion charge state. Interestingly, no evidence was found for gas-phase deglycosylation of the N-linked sugar in ribonuclease B, presumably due to effective competition from the facile amide bond cleavage channels that 'protect' the N-linked glycosidic bond from cleavage. Thus, localization of the posttranslational modification site may be determined by analysis of the 'protein fragment ion mass fingerprint'.

2,4,6-Triphenylpyrylium ion immobilized inside the supercages of zeolite Y enhances by 1-2 orders of magnitude the response of electrochemical oxidation of dopamine in neutral aqueous media accompanied by a remarkable inhibition of post-electron-transfer reactions. The negative charge of the zeolite framework in which the 2,4,6-triphenylpyrylium ion is incorporated blocks the electrochemical oxidation of the negative ascorbate ion, enabling the determination of micromolar concentrations of dopamine in the presence of a large excess ([10.sup.3]-[10.sup.4] times) of ascorbate in phosphate buffer (pH 7.4). Under optimized conditions, linear calibration plots were obtained for a differential pulse detection mode over the range 250-1 [micro] M dopamine with a sensitivity of 62 nA/ [micro] M and a detection limit (S/N = 3) of 0.2 [micro] M in the presence of 1.0 mM ascorbate.

Research has been conducted on the annelated housane. The preparation of the unknown housanes via the Hunig isopyrazole route has been carried out and the study of the rearrangement behavior complexities of the cyclopentadiyl radical cations and cyclopentyl cations is presented.

Research has been conducted on the triad family composed of C (sub)60 attached to the tetrathiafulvalene moieties by a rigid spacer. The synthesis of these triads and the isolation and characterization of some isomers have been carried out and the results are reported.

A simplified mathematical model has been developed for finding lattice energies of binary group I and II ionic compounds. It uses the Solver technique to estimate the empirical constants. Knowing the crystal structure or actual lattice parameters is not necessary. Students can focus on basic electrostatics, involving moles of ions pre empirical formula, ion charge, and self-consistent ionic radii. Surprisingly good agreement with Born-Haber cycle lattice energies was found.

Use of a teaching model to correct acknowledged misconceptions in electrochemistry without use of videos and computers is discussed. Use of a semipermeable membrane, not a salt bridge, to complete a circuit and demonstrate maintenance of cell neutrality is the essential feature of the model. The value of the model is supported by research using pretests and testing after use.

The crystal structure of 1,2-diphenyl-5,7-di-tert-butylspiro(2.5)octa-1,4,7-trien-6-one is examined using X-ray analysis. It was observed that although the C-C-C spiro angle in 3(49.64(7) degrees) is one of the smallest known for carbon atom, it has no effect on the relationship between C=O bond length and the difference between the single and double bond lengths in the cyclohexadienone moiety. These findings show that the neutral 3 is not a good model for the charged bridged vinylidenephenonium as indicated by both structural criteria and NRT analyses.

An enhanced Monte Carlo method was applied for the simulation of the ion transport in classical drift tube for ion-molecule asymmetric systems such as O-/O2 or N+/N2. The new technique takes care of the problem of incident ions which disappear at relatively high electric fields because of asymmetric charge transfer or electron detachment. These ion elimination processes were compensated by a fictitious ion formation which enhances the accuracy of the ion distribution function and swarm coefficient computations.

A solution procedure to the Poisson-Boltzmann equation for computing the electrical double layer properties of semipermeable microbial membranes was described. Surface charging data for bacterial membranes were utilized to examine all ions in the calculation of surface and Donnan potentials for the membranes in multicomponent electrolytes. Results showed that trace amounts of divalent and trivalent cations at very low concentrations have considerable effects on the calculated surface and Donnan potentials.

Semiempirical models were developed for MeV ion electronic energy loss and damage formation. The B. P and As ions were implanted at room temperature in silicon. The models were examined by comparing measurements with Monte Carlo impurity and damage depth distribution simulations. Results reveal a systematic underestimate of simulated damage distribution peak depth position.

The results of a temporal variation simulation study of the energy of positive ions deposited in a metal electrodes dipped in a plasma shows the electrons of the plasma are expelled from the electrodes as a result of the application of negative step potential to the electrode. The negative impurity ions move away from the electrodes and the positive ions move towards the electrode and are trapped in the ion-matrix sheath and ultimately absorbed by the electrode.

The density distribution of mobile ions in the oxide of a metal-oxide-semiconductor structure was characterized using a theoretical model. The model assumed that when the combined mobilizing forces became sufficient to provide the needed activation energy for overcoming the effective potential well, the equilibrium concentration of these mobile ions was attained.

Research has been conducted on the osmium(VI)-nitrido complex chemistry. Results indicate that the reaction between azide ion and electron-rich nitrido complex gives Os(IV)-azidoimido product containing unbridged N (sub)4 (super)2- ligand.

A two-part exercise in theoretical modeling of ion hydration is presented. The exercise aims to explore that changes brought by an introduction of a simple on water molecule. The accuracy of a range of computational methods is also examined.

Research has been conducted on the open-shell Kegin ion consisting of high-spin iron(III) atoms. The preparation, structure and physical properties of this ion are described.