The triazatruxene derivative azatrux binds to the parallel form of the human telomeric G-quadruplex under molecular crowding conditions: Biophysical and molecular modeling studies

The present study has employed a combination of spectroscopic, calorimetric and computational methods to explore the binding of the three side-chained triazatruxene derivative, termed azatrux, to a human telomeric G-quadruplex sequence, under conditions of molecular crowding. The binding of azatrux to the tetramolecular parallel [d(TGGGGT)](4) quadruplex in the presence and absence of crowding conditions, was also characterized. The data indicate that azatrux binds in an end-stacking mode to the parallel G-quadruplex scaffold and highlights the key structural elements involved in the binding. The selectivity of azatrux for the human telomeric G-quadruplex relative to another biologically relevant G-quadruplex (c-Kit87up) and to duplex DNA was also investigated under molecular crowding conditions, showing that azatrux has good selectivity for the human telomeric G-quadruplex over the other investigated DNA structures. (C) 2011 Elsevier Masson SAS. All rights reserved.

1D-Leaky Wave Antenna Employing Parallel-Plate Waveguide Loaded With PRS and HIS

A new type of one-dimensional leaky-wave antenna (LWA) with independent control of the beam-pointing angle and beamwidth is presented. The antenna is based on a simple structure composed of a bulk parallel-plate waveguide (PPW) loaded with two printed circuit boards (PCBs), each one consisting of an array of printed dipoles. One PCB acts as a partially reflective surface (PRS), and the other grounded PCB behaves as a high impedance surface (HIS). It is shown that an independent control of the leaky-mode phase and leakage rate can be achieved by changing the lengths of the PRS and HIS dipoles, thus resulting in a flexible adjustment of the LWA pointing direction and directivity. The leaky-mode dispersion curves are obtained with a simple Transverse Equivalent Network (TEN), and they are validated with three-dimensional full-wave simulations. Experimental results on fabricated prototypes operating at 15 GHz are reported, demonstrating the versatile and independent control of the LWA performance by changing the PRS and HIS parameters.

Comparison of parallel and perpendicular polarized counterpropagating light for suppressing high harmonic generation

The use of counterpropagating laser pulses to suppress high harmonic generation (HHG) is investigated experimentally for pulses polarized parallel or perpendicular to the driving laser pulse. It is shown for the first time that perpendicularly polarized pulses can suppress HHG. The intensity of the counterpropagating pulse required for harmonic suppression is found to be much larger for perpendicular polarization than for parallel polarization, in good agreement with simple models of the harmonic suppression. These results have applications to quasi-phase-matching of HHG with trains of counterpropagating pulses. (C) 2007 Optical Society of America.

Design criteria for a barrier-based gas-liquid flow distributor for parallel microchannels

This paper presents criteria for the design of a flow distributor for even distribution of gas and liquid flows over parallel microchannels. The design criteria are illustrated for the case of a nitrogen-water Taylor flow (1

Asymptotic modeling of short plane-parallel high-pressure glow discharge

Here a self-consistent continuum model is presented for a narrow gap plane-parallel dc glow discharge. The set of governing equations consisting of continuity and momentum equations for positive ions, fast (emitted by the cathode) and slow electrons (generated by fast electron impact ionization) coupled with Poisson's equation is treated by the technique of matched asymptotic expansions. Explicit results are obtained in the asymptotic limit: (chi delta) much less than 1, where chi = e Phi(a)/kT, delta = (r(D)/L)(2) (Phi(a) is the applied voltage, r(D) is the Debye radius) and pL much greater than 1(Hg mm cm), where p is the gas pressure and L is the gap length. In the case of high pressure, the electron energy relaxation length is much smaller than the gap length, and so the local field approximation is valid. The discharge space divides naturally into a cathode fall sheath, a quasineutral plasma region, and an anode fall sheath. The electric potential distribution obtained for each region in a (semi)analytical form is asymptotically matched to the adjoining regions in the region of overlap. The effects of the gas pressure, gap length, and applied voltage on the length of each region are investigated. (C) 2000 American Institute of Physics. [S1070-664X(00)01302-1].