Self‐Assembled Hollow Polyaniline/Au Nanospheres Obtained by a One‐Step Synthesis

Self‐assembled hollow nanosphere composites of polyaniline and Au nanoparticles (PANI‐p‐TSA/Au) were chemically synthesized from solutions containing p‐toluenesulfonic acid (p‐TSA) with the addition of gold chloride trihydrate as the oxidant. The composite materials were characterized by SEM, TEM, and a range of spectroscopic methods. Spectroscopic characterizations confirmed that the polymeric product is a form of doped PANI, while electron diffraction and X‐ray diffraction showed that elemental Au was present in the PANI‐p‐TSA/Au nanocomposites. The room temperature electrical conductivity of the PANI‐p‐TSA/Au nanocomposites was two orders of magnitude greater than a PANI‐p‐TSA obtained in the presence of ammonium persulfate as the oxidant under the same conditions.

     

A novel cationic conjugated polymer for homogeneous fluorescence-based DNA detection

A novel water-soluble cationic conjugated polymer, poly({2,5-bis[3-(N,N-diethylamino)-1-oxapropyl]-para-phenylenevinylene}-alt-para-phenylenevinylene) dibromide, was synthesized and used to develop a simple label-free DNA detection essay.     

Interferometric measurement and tomography of the density field of supersonic jets

 The density field of cylindrical supersonic jets is investigated by Mach-Zehnder interferometry. The optical phase shift is extracted from the interferograms by digital image processing. Disturbing turbulence effects in the free shear layer are eliminated by sequential averaging of the phase shifts of several experimental images. The resulting steady state phase shift is used to calculate time-averaged interferograms and to reconstruct the density field by computerized tomography. The obtained results are compared with theoretical predictions and good quantitative agreement is found. Received: 3 March 1997/Accepted: 3 October 1997     

Size of the freeze-out source in high energy heavy ion collisions

Based on a hydro-inspired azimuthally symmetric emission function, we analyze the HBT radius Rs and the single-particle transverse momentum spectra in Au+Au collisions measured by the STAR Collaboration at SNN = 200 GeV. The results show that consistent assumptions about transverse density (and/or flow profile) in the calculation of the HBT radius Rs and single-particle spectral analyses play an important role for understanding the size of the freeze-out source.     

Structure-activity analysis of the purine binding site of human liver glycogen phosphorylase

Human liver glycogen phosphorylase (HLGP) catalyzes the breakdown of glycogen to maintain serum glucose levels and is a therapeutic target for diabetes. HLGP is regulated by multiple interacting allosteric sites, each of which is a potential drug binding site. We used surface plasmon resonance (SPR) to screen for compounds that bind to the purine allosteric inhibitor site. We determined the affinities of a series of compounds and solved the crystal structures of three representative ligands with K(D) values from 17-550 microM. The crystal structures reveal that the affinities are partly determined by ligand-specific water-mediated hydrogen bonds and side chain movements. These effects could not be predicted; both crystallographic and SPR studies were required to understand the important features of binding and together provide a basis for the design of new allosteric inhibitors targeting this site.     

Periodic wavetrains for systems of coupled nonlinear Schrödinger equations

Exact, periodic wavetrains for systems of coupled nonlinear Schrödinger equations are obtained by the Hirota bilinear method and theta functions identities. Both the bright and dark soliton regimes are treated, and the solutions involve products of elliptic functions. The validity of these solutions is verified independently by a computer algebra software. The long wave limit is studied. Physical implications will be assessed.     

Shakedown and limit analysis of periodic composites

The optimization of fiber distribution is analyzed in order to improve the strength performance of metal-matrix composite material, which is submitted to two variable independent loads by coupling homogenization and shakedown theories. Numerical Direct Methods are applied to acquire the shakedown domain of three-dimensional heterogeneous elastic-perfectly plastic fiber-reinforced composite for optimal design. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)