Effective chiral recognition among ions in polar media

Effective homochiral recognition occurs between the cationic [Fe(eilatin)3]2+ complex and TRISPHAT anions even in polar media such as 90% acetone-CHCl3 (de > or = 89%).     

Catalytic spatiotemporal thermal patterns during CO oxidation on cylindrical surfaces: experiments and simulations

Dynamics of spatiotemporal thermal patterns during the catalytic CO oxidation over Pd supported on a glass-fiber catalytic cloth rolled into a tube of 20 mm diameter and 80 mm length has been studied in a continuous flow reactor by IR thermography. A specially designed aluminum mirror built in the reactor provided image of the entire surface of the horizontally held catalytic tube. With flow in the main axial direction and through the tube surface, we observed periodic motions of a pulse, which was born downstream and propagated upstream. The temperature pulse motion was accompanied by conversion oscillations of CO2. With flow in the main axial direction, parallel to the surface, we observed a stationary hot zone after an oscillatory transient. These patterns can be simulated with a plug-flow-reactor-like heterogeneous reactor model that incorporates previously determined kinetic and transport parameters.     

Optimization of laser-focused deposition lines: Rydberg atoms

Optimally narrow nanoscale lines are computationally obtained for Rb Rydberg atoms deposited on surfaces. The use of optimized polychromatic fields is shown to allow lines as narrow as 1 nm in the absence of transverse velocities and shown to counter the deleterious effects of transverse velocities in laser cooled beams. Specifically, lines as narrow as 6.5 nm wide are obtained in the presence of transverse velocities associated with a temperature of 1 mK. Using this approach it is possible to deposit a single narrow line, even when the atomic beam is bigger than the period of the focusing lens, using as few as two, relatively weak, laser fields.     

Efficiently computing the permanent and Hafnian of some banded Toeplitz matrices

We present a new efficient method for computing the permanent and Hafnian of certain banded Toeplitz matrices. The method covers non-trivial cases for which previous known methods do not apply. The main idea is to use the elements of the first row and column, which determine the entire Toeplitz matrix, to construct a digraph in which certain paths correspond to permutations that the permanent and Hafnian count. Since counting paths can be done efficiently, the permanent and Hafnian for those matrices is easily obtainable.     

The Odd-Distance Plane Graph

The vertices of the odd-distance graph are the points of the plane ℝ². Two points are connected by an edge if their Euclidean distance is an odd integer. We prove that the chromatic number of this graph is at least five. We also prove that the odd-distance graph in ℝ² is countably choosable, while such a graph in ℝ³ is not. The research of J. Maňuch was supported in part by MITACS (Mathematics of Information Technology and Complex Systems). The research of M. Rosenfeld was supported in part by the Chancellor Research Grant and the Institute of Technology, UWT. The research of S. Shelah was supported by the United States-Israel Binational Science Foundation (Grant no. 2002323), and by NSF grant No. NSF-DMS 0600940. No. 923 on Shelah’s publication list. The research of L. Stacho was supported in part by NSERC (Natural Science and Engineering Research Council of Canada) grant.     

Ink‐Jet Printing of Metallic Nanoparticles and Microemulsions

Summary: Two types of ink‐jet inks are presented: ink containing an aqueous dispersion of silver nanoparticles and an oil‐in‐water microemulsion‐based ink. The metallic ink contains nanoparticles of silver, which are formed in the presence of an ionic polymeric stabilizer. Sintering of the printed image obtained with the use of such silver‐based inks at temperatures as low as 300 °C results in formation of patterns possessing noticeable conductivity. The microemulsion inks are based on a thermodynamically stable microemulsion, in which the dispersed oil phase is a volatile solvent containing a water‐insoluble colorant. After contact of the jetted ink droplets with a substrate, nanodroplets of the microemulsion are converted into nanoparticles of the solubilized colorant. In some cases, it was found that the evaporation of microemulsion ink droplets leads to formation of rings composed of ordered nanoparticles.

Scheme of ink‐jet printing of an oil‐in‐water microemulsion followed by conversion of the nanodroplets into nanoparticles, caused by quick evaporation of the solvent within the microemulsion droplets. Therefore, the ink behaves as a dye‐based ink prior to printing, but after printing it behaves like a pigment‐based ink.