Solvent-Processible Polymer Membrane-Based Reference Electrodes for Miniature Chemical Sensors

We have recently developed a new type of liquid junction-free reference electrode that is suited for fabrication of miniature ion sensor devices. The proposed reference electrode system employs a solvent-processible polymer membrane, and the best performance membrane so far is formulated with an aromatic type polyurethane,synthesized with 4,4'- methylenebis(phenyl isocyanate) and poly(tetramethylene ether glycol).     

Electron-ion Coulomb Bremsstrahlung in nonideal plasmas

The classical electron-ion Coulomb Bremsstrahlung process is investigated in nonideal plasmas. An effective pseudopotential model taking into account the plasma screening and collective effects is applied to describe the electron-ion interaction potential in a classical nonideal plasma. The classical straight-line trajectory method is applied to the motion of the projectile electron in order to visualize the variation of the differential Bremsstrahlung radiation cross-section (DBRCS) as a function of the scaled impact parameter, nonideal plasma parameter, projectile energy, photon energy, and Debye length. The results show that the DBRCS in ideal plasmas described by the Debye-Hückel potential is always greater than that in nonideal plasmas, i.e., the collective effects reduce the DBRCS for both the soft and hard photon cases. For large impact parameters, the DBRCS for the soft photon case is found to be always greater than that for the hard photon case. Received 1st December 1999     

Picomolar FKBP inhibitors enabled by a single water-displacing methyl group in bicyclic [4.3.1] aza-amides

Methyl groups can have profound effects in drug discovery but the underlying mechanisms are diverse and incompletely understood. Here we report the stereospecific effect of a single, solvent-exposed methyl group in bicyclic [4.3.1] aza-amides, robustly leading to a 2 to 10-fold increase in binding affinity for FK506-binding proteins (FKBPs). This resulted in the most potent and efficient FKBP ligands known to date. By a combination of co-crystal structures, isothermal titration calorimetry (ITC), density-functional theory (DFT), and 3D reference interaction site model (3D-RISM) calculations we elucidated the origin of the observed affinity boost, which was purely entropically driven and relied on the displacement of a water molecule at the protein–ligand–bulk solvent interface. The best compounds potently occupied FKBPs in cells and enhanced bone morphogenic protein (BMP) signaling. Our results show how subtle manipulation of the solvent network can be used to design atom-efficient ligands for difficult, solvent-exposed binding pockets.

Enhancement by displacement. A single methyl group displaces a water molecule from the binding site of FKBPs, resulting in the most potent binders known, outperforming the natural products FK506 and rapamycin in biochemical and cellular assays.     

Spherical Polarization Body: Synthesis of Monodisperse Micron‐Sized Polyaniline Composite Particles

A new method to synthesize uniform polyaniline‐coated composite microparticles was contrived considering the surface reactivity and porous structure of substrate polymer particles. It was found that the pore diameter together with the epoxy functional group plays a crucial role in controlling the structure of polyaniline shell. The polyaniline composite particles produced in this study are believed to find great applicability in piezoelectronics and as electro‐rheological fluids.     

Progress toward limiting generation of dendritic ethynylsilanes (PhCC)4−nMenSi (n = 0–2)

Dendritic carbosilanes based on phenylethynylmethylsilanes (PhCC)_4−nMe_nSi (n = 0–2) as cores were synthesized. The building blocks of the dendrimers consist of double bonds ( PhCCHMeSi ) in the inner shell and triple bonds [(PhCC)₂MeSi ] on the outmost periphery. The synthetic methods used the iterative alkynylation and hydrosilation cycle, which was composed of lithium phenylacethylide and dichloromethylsilane. The limiting generation of the dendrimer for the four branching type (PhCC)₄Si at a core molecule has 32 phenylethynyl groups on the third generation, 48 for the three branching type (PhCC)₃MeSi on the fourth generation, and 64 for the two branching type (PhCC)₂Me₂Si on the fifth generation. The dendrimers were characterized by the use of NMR, Maldi mass, SEC, DSC, UV as well as elemental analysis. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2749–2759, 2000