Characteristics of charged and metastable species in micro-discharges of AC- plasma display panel

The temporal effects of charged and metastable particles in the micro-discharges of an AC plasma display panel (AC-PDP) were investigated under actual driving conditions. The discharge gas used in the 4-in PDP was Neon + 4% Xenon. The discharge characteristics in terms of the time scale related to the space-charge decay, wall charge decay, metastable decay, and charge accumulation were investigated using a pulse technique. For Neon + 4% Xenon gas-mixture discharges of 500 torr, 4 /spl mu/s was related to the time scale of the space-charge decay and wall-charge accumulation time. The minimum sustain voltage started to dramatically increase at 20 /spl mu/s, which was related to the time scale of the metastable particles. Whereas, after 40 /spl mu/s, the minimum sustain voltage slowly increased with a slope of 0.01581, which was related to the inverse of the time scale of the wall charge decay.     

Microwave induced reactions of SO2 and NOx decomposition in the char-bed

Microwaves applied to a pyrolytic carbon matrix enhance the chemical reactions of SO₂ and NO_x decomposition. The SO₂ and NO_x in a coal combustor product gas are adsorbed in a char bed and decomposed by the microwave to elemental sulfur and nitrogen, respectively. High removal rates of SO₂ and NO_x -- near 98% -- were observed in the laboratory tests. The activated carbon used as an adsorbent is also produced inexpensively in the electromagnetic field from coal pyrolysis. During the 21-cycle adsorption and decomposition experiments, the surface area of the bed carbon was increased from 7 m²/g to 700 m²/g. Process concept testing and economic evaluation will be completed in the U.S. Department of Energy, SBIR Phase II Program under Contract Number DE-FG03-90ER80898. This program is also supported in part by the National Science Foundation under Grant Number EHR-910-8774. The paper presents the laboratory test results obtained to date.     

Analysis of the intensity and phase delay of photoinduced infrared absorption from poly(2,5-thienylenevinylene)

Photoinduced infrared absorption spectra have been measured from poly(2,5-thienylenevinylene) by the phase-modulation method with modulation frequencies between 0.8 and 15 kHz. The modulation-frequency dependencies of the intensity and phase delay of the photoinduced infrared absorption have been numerically simulated by the use of a model based on second-order kinetics involving a neutralization recombination process between the positive and negative polarons. This numerical method is useful in analysing the nonlinear response associated with a bimolecular process.     

Catalytic oxidation of carbon monoxide over CoOx/CeO2catalysts

Isomerization of linoleic acid over carbon supported ruthenium and the influence of catalyst preactivation under hydrogen were investigated in a batch reactor. Chemisorbed hydrogen increased the catalytic activity but did also suppress the isomerization selectivity due to double bond hydrogenation. This revised version was published online in June 2006 with corrections to the Cover Date.     

Polynomial structures for nilpotent groups

If a polycyclic-by-finite rank- group admits a faithful affine representation making it acting on properly discontinuously and with compact quotient, we say that admits an affine structure. In 1977, John Milnor questioned the existence of affine structures for such groups . Very recently examples have been obtained showing that, even for torsion-free, finitely generated nilpotent groups , affine structures do not always exist. It looks natural to consider affine structures as examples of polynomial structures of degree one. We introduce the concept of a canonical type polynomial structure for polycyclic-by-finite groups. Using the algebraic framework of the Seifert Fiber Space construction and a nice cohomology vanishing theorem, we prove the existence and uniqueness (up to conjugation) of canonical type polynomial structures for virtually finitely generated nilpotent groups. Applying this uniqueness to a result going back to Malcev, it follows that, for torsion-free, finitely generated nilpotent groups, each canonical polynomial structure is expressed in polynomials of limited degree. The minimal degree needed for obtaining a polynomial structure will determine the ``affine defect number'. We prove that the known counterexamples to Milnor's question have the smallest possible affine defect, i.e. affine defect number equal to one.

     

Seifert manifolds with fiber spherical space forms

We study the Seifert fiber spaces modeled on the product space . Such spaces are ``fiber bundles' with singularities. The regular fibers are spherical space-forms of , while singular fibers are finite quotients of regular fibers. For each of possible space-form groups of , we obtain a criterion for a group extension of to act on as weakly -equivariant maps, which gives rise to a Seifert fiber space modeled on with weakly -equivariant maps as the universal group. In the course of proving our main results, we also obtain an explicit formula for for a cocompact crystallographic or Fuchsian group . Most of our methods for apply to compact Lie groups with discrete center, and we state some of our results in this general context.

     

Many-orbital cluster expansion for the exchange-repulsion energy in the interaction of closed-shell systems

The energy of exchange repulsion between two closed-shell systems described by determinantal wave functions has been represented as a sum of contributions arising from the interaction of two, three and four orbitals at a time. These contributions have been calculated for the interaction of two neon atoms. It has been found that in the van der Waals minimum region the two-orbital components are of secondary importance and that about 90% of the total exchange energy originates from the three-orbital interactions ofL-shell electrons. The four-orbital as well as the double-exchange terms have been found negligible. The approximate algorithms for evaluation of the exchange repulsion energy have been tested and discussed.This work was partly supported by the Polish Academy of Sciences within the project MR-I.9.     

Organization of microcrystals on glass by adenine-thymine hydrogen bonding

Shaking of adenine-tethering glass plates in an aqueous suspension of micrometer-sized, thymine-tethering zeolite crystals such as ZSM-5 (0.6 mum x 1.7 mum x 2.5 mum) or zeolite-A (1.7 mum x 1.7 mum x 1.7 mum) for 3 h at room temperature leads to facile assembly of monolayers of the zeolite microcrystals on the glass plates through the hydrogen-bonding interaction between the tethered adenine and thymine. Control experiments show that the presence of adenine and thymine on the respective solid surface is essential for the monolayer assembly. This establishes that even the micrometer-sized building blocks can be organized by a large number of well-defined weak hydrogen bonding. Increase in the assembly temperature to annealing temperatures leads to a marked increase in the rate of monolayer assembly and in the size of the domain in which zeolite crystals are closely packed in the same three-dimensional orientation.