PEG‐Biscyanoacrylate Crosslinker for Octyl Cyanoacrylate Bioadhesive

PEG400 (polyethylene glycol, M_W 400) biscyanoacrylate is synthesized and copolymerized with 2‐octyl cyanoacrylate for potential use as bioadhesive. PEG400 biscyanoacrylate is synthesized from the esterification of anthracenyl cyanoacrylic acid where the anthracene unit serves as vinyl‐protecting group. Copolymerization increases the plasticity, mechanical strength, and resilience of the resulted polymer as determined by dynamic mechanical analysis. Peeling test confirms its superior bioadhesive properties. Surface morphology is characterized by SEM imaging. The formulations are cytocompatible and safe. This cyanoacrylate composition may provide improved bioadhesive cyanoacrylates.

     

Phonon confinement effects in Raman spectra of porous silicon at non‐resonant excitation condition

Light emitting porous silicon samples with different porosities, i.e. crystalline sizes, were produced from the low level doped p‐type silicon wafers by the anodization process. The effects of strong phonon confinement, redshift and broadening, were found on the O(Γ) phonon mode of the Raman spectra recorded at non‐resonant excitation condition using a near infrared 1064 nm laser excitation wavelength. Similarly, the blueshift of the photoluminescence peak was observed by reducing the crystalline sizes. Vibrational and optical findings were analysed within the existing models of confinement on the vibrational and electronic states of silicon nanocrystals. Since the energy of the photoluminescence peak of small nanocrystals also depends on the oxygen content on the surface of nanocrystals, the surface oxidation states were examined using infrared and energy dispersive spectroscopy. The partial coverage of the surface of nanocrystals was found due to the sample exposure to air. As a consequence, the photoluminescence energy did not increase as would be expected from the quantum confinement model. These results further indicate that the oxygen passivation along with the quantum confinement determines the electronic states of the silicon nanocrystals in porous silicon. Copyright © 2014 John Wiley & Sons, Ltd.     

Comparison of Various K̄N Partial Wave Analyses in the Region 0–1400 MeV/c

A comprehensive comparative study of the available K̄N partial wave analyses is made with a view to bring out their similarities and disagreements and to point towards those momentum regions that require particular attention in all future analyses. The multichannel nature of the K̄N scattering is discussed along with the presently available scattering cross-section data for various channels. The parametrization of the various partial wave analyses is discussed and their amplitudes calculated and compared under the set of conventions proposed by Levi Setti.