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Novel transparent conductive electrodes (TCEs) with copper (Cu)/silver (Ag) core/shell nanofibers (NFs) containing random, aligned, and crossed structures were prepared using a combination of electrospinning (ES) and chemical reduction. The ES process was used to prepare continuous copper nanofibers (Cu-NFs), which were used as core materials and were then immersed in silver ink (Ag ink) to form a protective layer of Ag to protect the Cu-NFs from oxidation. The Ag shell layer protected the Cu-NFs against oxidation and enhanced their conductivity. Such Cu/Ag core/shell webs can be easily transferred on the flexible matrix and can be applied in TCEs. The metal NF webs of different structures exhibited various degrees of conductivity and followed the order random type > crossed type > aligned type; however, the order with respect to transmittance ( T) was inverse. The aligned nanowire networks exhibited a high T of over 80%, and the random ones exhibited a low sheet resistance of less than 10 2 Ω/sq (the best value is 7.85 Ω/sq). The present study demonstrated that TCEs based on Cu/Ag core/shell NF webs have considerable flexibility, transparency, and conductivity and can be applied in novel flexible light-emitting diode devices and solar cells in the future.

Villin-type headpiece domains are approximately 70 amino acid modular motifs found at the C terminus of a variety of actin cytoskeleton-associated proteins. The headpiece domain of villin, a protein found in the actin bundles of the brush border epithelium, is of interest both as a compact F-actin binding domain and as a model folded protein. We have determined the high-resolution crystal structures of chicken villin headpiece (HP67) at 1.4 A resolution as well as two mutants, R37A and W64Y, at 1.45 and 1.5 A resolution, respectively. Replacement of R37 causes a 5-fold reduction in F-actin binding affinity in sedimentation assays. Replacement of W64 results in a much more drastic reduction in F-actin binding affinity without significant changes in headpiece structure or stability. The detailed comparison of these crystal structures with each other and to our previously determined NMR structures of HP67 and the 35-residue autonomously folding subdomain in villin headpiece, HP35, provides the details of the headpiece fold and further defines the F-actin binding site of villin-type headpiece domains.

This paper reports a successful development of a group of efficient soluble polymer-supported chiral tartrate ligands by liquid-phase synthesis for Sharpless epoxidation of a variety of allylic alcohols through ligand diversity. The influence of substituent in chiral tartrate ligands on the enantioselectivities of the reaction was disclosed. Moderate chemical yields and good enantiomeric excesses were obtained by using soluble polymer-supported tartrate ester in the epoxidation of allylic alcohols with Ti(O-i-Pr)(4)/tert-butyl hydroperoxide.

RNAs synthesized in vitro by purified Escherichia coli RNA polymerase from a bacteriophage 82 promoter are heterogeneous at the 5' end. We show that this heterogeneity results from variable addition of extra adenine residues, allowed by slippage of the initial oligonucleotide pppAAA-OH against its DNA template sequence TTT. Slippage backward by one base allows another A to be added, giving pppAAAA-OH, and this cycle can continue more than 20 times before it is ended by incorporation of UMP encoded by the fourth template base A. Slippage is abolished by mutation of the TTT template sequence to TGT and is sensitive to the concentrations of UTP and ATP in the reaction mixture. Analysis of deletions, substitutions, and point mutants implies that the slippage reaction requires only the existence of TTT at the initiation site of the template strand, although changes in neighboring nucleotides slightly affect its efficiency.