Reversible and irreversible trapping at room temperature in poly(thiophene) thin-film transistors

We measured the bias stress characteristics of poly(thiophene) semi-crystalline thin-film transistors (TFTs) as a function stress times, gate voltages and duty-cycles. At room temperature, the bias stress has two components: a fast reversible component and a slow irreversible component. We hypothesize that the irreversible component is due to charge trapping in the disordered areas of the semiconductor film. At low duty-cycle (<2%), the fast bias stress component is reversed during the off-part of the cycle therefore the observed VT shift in only caused by irreversible trapping. Irreversible trapping follows power-law kinetics with a time exponent approximately equal to 0.37. We use these findings to estimate the lifetime of TFTs used as switches in display backplanes

All change: protein conformation and the ubiquitination reaction cascade

The structures of enzymes that collectively modify proteins by covalent addition of ubiquitin-like protein moieties have provided significant insights into the regulatory pathways they compose and have highlighted the importance of protein flexibility for the mechanism and regulation of the ubiquitination reaction

Halogen Bonds Form the Basis for Selective P-TEFb Inhibition by DRB

SummaryCdk9, the kinase of the positive transcription elongation factor b, is required for processive transcription elongation by RNA polymerase II. Cdk9 inhibition contributes to the anticancer activity of many Cdk inhibitors under clinical investigation and hence there is interest in selective Cdk9 inhibitors. DRB (5,6-dichlorobenzimidazone-1-β-D-ribofuranoside) is a commonly used reagent for Cdk9 inhibition in cell biology studies. The crystal structures of Cdk9 and Cdk2 in complex with DRB reported here describe the molecular basis for the DRB selectivity toward Cdk9. The DRB chlorine atoms form halogen bonds that are specific for the Cdk9 kinase hinge region. Kinetic and thermodynamic experiments validate the structural findings and implicate the C-terminal residues of Cdk9 in contributing to the affinity for DRB. These results open the possibility to exploit halogen atoms in inhibitor design to specifically target Cdk9

Slope Stability Evaluation for an Existing Steep Cut in Weathered Volcanics, Hong Kong

This case study concerns an investigation of a major existing soil slope. It is a 60m (197 ft) high cutting slope, at 40 degrees to 60 degrees to the horizontal, exhibiting a considerably greater degree of stability than was obtained by a series of geotechnical investigations and analyses. The common practice of correlation between widely spaced borings is shown to be inappropriate at this site because of the highly variable ground conditions. Rather, the comprehensive geological comprehensive engineering investigation carried out has enabled a detailed appreciation of the distribution and nature of weathered materials at the site. Transitional materials with soil-like appearance and weak rock properties have been identified. Based on this information, slope stability evaluation was carried out with more realistic results and with greater confidence