Porous normalLa1−xnormalSrxConormalO3−δ (LSC) electrodes having Sr composition x=0.4 (LSC-64) and x=0.2 (LSC-82) were fabricated on Sm-doped ceria electrolytes, and studied using electrochemical impedance spectroscopy between T=650–750°C and pnormalO2=0.01–1.0atm . The faradaic portion of the impedance was found to exhibit Gerischer or Gerischer-like characteristics, indicating colimitation by kinetics and transport. The characteristic resistance and frequency response was analyzed using a transport and reaction model that considers parallel bulk and surface diffusion of oxygen, as well as three-dimensional transport effects near the electrode electrolyte interface. In the case of LSC-64, measured characteristics appear to be largely consistent with a bulk transport path, based on independent measurements of the thermodynamic, kinetic, and transport properties of LSC-64. In the case of LSC-82, which has a much lower bulk vacancy concentration under the same conditions, results were inconsistent with an entirely bulk transport path. Results for LSC-82 could be rationalized assuming a parallel surface transport path, where surface mobility is governed by some kind of interstitial or adatom diffusion mechanism.

Multilayer nanoporous films generated by a layer‐by‐layer spin‐on method are presented (see Figure). Precise control of the porosity of the individual layers that comprise the multilayer structure is demonstrated. Due to the simplicity of this fabrication method a wide range of potential applications in the areas of separation science, biotechnology, optics etc. are envisaged.

The C4′-oxidized abasic site (C4-AP), which is produced by a variety of damaging agents has significant consequences on DNA. The lesion is highly mutagenic and reactive, resulting in interstrand cross-links. The base excision repair of DNA containing independently generated C4-AP was examined. C4-AP is incised by Ape1 ~12-fold less efficiently than an apurinic/ apyrimidinic lesion. DNA polymerase β induces the β-elimination of incised C4-AP in ternary complexes, duplexes, and single stranded substrate. However, excision from a ternary complex is most rapid. In addition, the lesion inactivates the enzyme after ~7 turnovers on average by reacting with one or more lysine residues in the lyase active site. Unlike 5′-(2-phosphoryl-1,4-dioxobutane) which very efficiently irreversibly inhibits Pol β, the lesion is readily removed by strand displacement synthesis carried out by the polymerase in conjunction with flap endonuclease 1. DNA repair inhibition by C4-AP may be a partial cause of the cytotoxicity of drugs that produce this lesion. KeywordsDNA damage; base excision repair; inhibition; oxidized abasic site Hydrogen atom abstraction from the 2′-deoxyribose rings of nucleotides in DNA gives rise to several oxidized abasic lesions (1,2). One of these, the C4′-oxidized abasic site (C4-AP, Chart 1) is produced by a variety of DNA damaging agents, including γ-radiolysis and antitumor antibiotics (3-5). Its frequent occurrence is attributed to the high accessibility of the C4′-hydrogen atom to diffusible species, and the relatively low bond dissociation energy of the respective carbon-hydrogen bond (6,7). C4-AP is efficiently incised by the endonucleases in E. coli that are responsible for AP incision (8). In addition, previous studies using C4-AP produced by bleomycin indicated that the lesion is a substrate for mammalian BER enzymes, including Ape1 and Pol β (9). Ape1 incision and subsequent Pol β excision are the first two steps in BER of AP lesions (Scheme 1). However, this pathway does not efficiently excise all abasic lesions. DOB is an oxidized abasic lesion that is produced by a variety of DNA damaging agents. Recent experiments revealed that DOB very efficiently inhibits DNA polymerase β irreversibly (10). C4-AP contains the 1,4-dicarbonyl functional group that is crucial for irreversible Pol β inhibition by DOB. The structural similarity between these two lesions, the central role played by Pol β in BER, and

High performance of SnP2O7-based intermediate temperature fuel cells was obtained with a quaternary ammonium-biphosphate ion-pair coordinated polymer electrolyte.