Operation modes of a liquid-crystal modal wave-front corrector

Liquid-crystal modal wave-front correctors provide much better wave-front correction than do piston correctors with the same number of actuators; moreover, use of additional degrees of freedom of the driving ac voltage signals may further improve device performance. Some practical aspects of the operation of liquid-crystal modal wave-front correctors are discussed. Special attention is paid to the interference of various contact responses and to the formation of required phase shapes through wider control of signal frequencies and electric phase shifts. The study is based on an analytic approach and numerical investigation; major theoretical conclusions are verified experimentally.     

Techniques for increasing the throughput of flow injection mass spectrometry

Improvements to the design and operation of a Gilson 215 multiprobe liquid-handling system have resulted in a significant increase in the throughput for flow injection molecular weight characterization of combinatorial chemistry libraries. The rapid injection sequence, and subsequent increased sample throughput, is effected by directing the entire mobile-phase flow through each of the injection loops sequentially while isolating or "dead-ending" the remaining nonactive loops. This mode of operation was accomplished by incorporating column-switching valves prior to and following the set of eight parallel injectors. Analysis rates are achieved without sacrificing the integrity of the flow injection peak profile as baseline resolution is maintained for all samples. Using this system, the total analysis time for a 96-well microtiter plate has been reduced to approximately 5 min.     

Reduction of interindividual-intergroup discontinuity: The role of leader accountability and proneness to guilt.

Two experiments contrasted interactions between group leaders with interactions between individuals in a mixed-motive setting. Consistent with the idea that being accountable to the in-group implies normative pressure to benefit the in-group, Experiment 1 found that accountable leaders were more competitive than individuals. Consistent with the idea that being unaccountable to the in-group implies normative pressure to be cooperative and that high guilt proneness provides motivation to be moral, Experiment 2 found that when guilt proneness was high, unaccountable leaders were less competitive than accountable leaders and did not differ significantly from individuals. In other words, the robust interindividual-intergroup discontinuity effect was eliminated when groups had unaccountable leaders who were high in guilt proneness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synchronized flux corrected remapping for ALE methods

A new optimization-based synchronized flux corrected conservative interpolation (remapping) of mass, momentum and energy for arbitrary Lagrangian Eulerian method is developed. Fluxes of conserved variables (mass, momentum and total energy) are limited in a synchronous FCT-like way to preserve local bounds in density, velocity and specific internal energy.     

Topological numbering of features on a mesh

Assume we are given ann ×n binary image containing horizontally convex features; i.e., for each feature, each of its row's pixels form an interval on that row. In this paper we consider the problem of assigning topological numbers to such features, i.e., assign a number to every featuref so that all features to the left off in the image have a smaller number assigned to them. This problem arises in solutions to the stereo matching problem. We present a parallel algorithm to solve the topological numbering problem inO(n) time on ann ×n mesh of processors. The key idea of our solution is to create a tree from which the topological numbers can be obtained even though the tree does not uniquely represent the to the left of relationship of the features.The work of M. J. Atallah was supported by the Office of Naval Research under Grants N00014-84-K-0502 and N00014-86-K-0689, and the National Science Foundation under Grant DCR-8451393, with matching funds from AT&T. Part of this work was done while he was a Visiting Scientist at the Center for Advanced Architectures project of the Research Institute for Advanced Computer Science, NASA Ames Research Center, Moffett Field, CA 94035, USA. S. E. Hambrusch's work was supported by the Office of Naval Research under Contracts N00014-84-K-0502 and N00014-86K-0689, and by the National Science Foundation under Grant MIP-87-15652. Part of this work was done while she was visiting the International Computer Science Institute, Berkeley, CA 94704, USA. The work of L. E. TeWinkel was supported by the Office of Naval Research under Contract N00014-86K-0689.     

Thermal,structural and textural studies on the double complex salt [Co(NH3)6][Fe(CN)6] and on its silica-supported catalysts

Thermal analyses were carried out for the simple complexes [Co(NH₃)₆]Cl₃ and K₃[Fe(CN)₆] together with the double complex [Co(NH₃)₆][Fe(CN)₆] using thermogravimetric analysis, differential thermal analysis (DTA) and derived DTA (DDTA). Two series of silica-supported catalyst samples were prepared with soaking periods ranging from 5 h to 7 days, and likewise investigated. Structural changes of the original samples and their thermally treated products obtained at temperatures < 500 °C were monitored using X-ray diffraction and infrared spectroscopy. Textural variations were also studied using the N₂ adsorption technique. The decomposition of the simple complex [Co(NH₃)₆]Cl₃ occurs in two main steps that give rise to two asymmetric endothermic peaks centred at 225 and 350 °C. The first step involves two decomposition processes in which primarily two chloride ions migrate to the inner coordination sphere, thereby releasing two coordinated NH₃ that are evolved, followed by simultaneous decomposition and reduction to CoCl₂ · 2NH₃. The second step involves the decomposition of this latter compound to CoCl₂ with some reduction to Co. K₃[Fe(CN)₆] decomposes in a more complex manner, yet two strong exotherms are observed at 345 and 400 °C — the former being accompanied by a loss in weight due to its decomposition, whereas the latter is accompanied by a small increase in weight where an oxidation process seems to take place with its further decomposition. The double complex [Co(NH₃)₆][Fe(CN)₆] exhibits five consecutive decomposition steps in the temperature range 210–305 °C. The first is reproduced as an endotherm at 180 °C, whereas the remaining four steps cannot be distinguished separately by DTA due to the strong exothermic effects and only two exotherms are observed at 255 and 280 °C. The steps are identified according to the simultaneous reaction of six molecules together, leaving a final solid product with empirical formula Fe(CN)₂Co. X-ray diffraction of the double complex retains the characteristics of the constituent simple complexes with the appearance of two new very strong bands with a d- spacing of 0.5483 and 0.3005 nm. The specific surface areas of the catalyst samples are found to depend on the ion moiety supported first during preparation as well as on the soaking period. The catalyst samples are predominantly microporous and the variations in surface characteristics are discussed. V _I-t plots reveal the presence of two groups of pore sizes in some cases.     

First‐principles and crystal‐field calculations of the electronic and optical properties of two novel red phosphors Rb2HfF6:Mn4+ and Cs2HfF6:Mn4+

The electronic, structural, and optical properties of 2 red phosphors, Rb₂HfF₆:Mn⁴⁺ and Cs₂HfF₆:Mn⁴⁺, are evaluated using the first‐principles and crystal field theory methods. The calculated trigonal splitting of the Mn⁴⁺ orbital triplets perfectly matches the experimental excitation spectra. The structural and electronic properties of the mixed compound RbCsHfF₆ are also studied theoretically. In the mixed compound, the inversion center symmetry around the Hf site is removed. This symmetry lowering may result in an increase in the Mn^{4+ 2}E→⁴A₂ zero phonon line (ZPL) intensity, which is very weak in the 2 end members. This finding may be of interest for increasing the phosphor luminosity. It is believed that such a mechanism of local site symmetry lowering by preparing solid solutions may be used for other systems as well, to gain ZPL intensity and perhaps to minimize thermal losses, eventually leading to improved phosphor materials.