Size Optimization of a N‑Doped Graphene Nanocluster for the Oxygen Reduction Reaction

N-Doped graphene nanoclusters (N-GNCs) are promising electrocatalysts for the oxygen reduction reaction (ORR) at the cathode of fuel cells. In this study, the dependence of the ORR activity on the size of N-GNCs was investigated using first-principles calculations based on density functional theory. The maximum electrode potential (UMax) was estimated from the free energy of the reaction intermediates of the ORR. UMax was predicted to show a volcanic trend with respect to the cluster size. The results suggest that C215H36N with a radius of 13.6 Å is the best candidate for ORRs and is better than platinum in terms of UMax. The volcano-shaped plot of UMax is attributed to the switch of the reaction step that determines UMax, which is caused by the destabilization of reaction intermediates. Such changes in the stability of the intermediates can be explained by the decrease in the local density of states at the reaction site, which is due to the development of the so-called edge state at the zigzag edge. The establishment of experimental techniques to control the cluster size and doping position will be the key to superior catalyst preparation in the future

MOESM1 of Acid-specific formaldehyde donor is a potential, dual targeting cancer chemotherapeutic/chemo preventive drug for FANC/BRCA-mutant cancer

Additional file 1: Table S1. DNA repair genes mutated in the analyzed DT40 clones

Evaluating the Effects of Bioremediation on Genotoxicity of Polycyclic Aromatic Hydrocarbon-Contaminated Soil Using Genetically Engineered, Higher Eukaryotic Cell Lines

Bioremediation is one of the commonly applied remediation strategies at sites contaminated with polycyclic aromatic hydrocarbons (PAHs). However, remediation goals are typically based on removal of the target contaminants rather than on broader measures related to health risks. We investigated changes in the toxicity and genotoxicity of PAH-contaminated soil from a former manufactured-gas plant site before and after two simulated bioremediation processes: a sequencing batch bioreactor system and a continuous-flow column system. Toxicity and genotoxicity of the residues from solvent extracts of the soil were determined by the chicken DT40 B-lymphocyte isogenic cell line and its DNA-repair-deficient mutants. Although both bioremediation processes significantly removed PAHs from the contaminated soil (bioreactor 69% removal, column 84% removal), bioreactor treatment resulted in an increase in toxicity and genotoxicity over the course of a treatment cycle, whereas long-term column treatment resulted in a decrease in toxicity and genotoxicity. However, when screening with a battery of DT40 mutants for genotoxicity profiling, we found that column treatment induced DNA damage types that were not observed in untreated soil. Toxicity and genotoxicity bioassays can supplement chemical analysis-based risk assessment for contaminated soil when evaluating the efficacy of bioremediation

Screening Nonionic Surfactants for Enhanced Biodegradation of Polycyclic Aromatic Hydrocarbons Remaining in Soil After Conventional Biological Treatment

A total of five nonionic surfactants (Brij 30, Span 20, Ecosurf EH-3, polyoxyethylene sorbitol hexaoleate, and R-95 rhamnolipid) were evaluated for their ability to enhance PAH desorption and biodegradation in contaminated soil after treatment in an aerobic bioreactor. Surfactant doses corresponded to aqueous-phase concentrations below the critical micelle concentration in the soil-slurry system. The effect of surfactant amendment on soil (geno)­toxicity was also evaluated for Brij 30, Span 20, and POESH using the DT40 B-lymphocyte cell line and two of its DNA-repair-deficient mutants. Compared to the results from no-surfactant controls, incubation of the bioreactor-treated soil with all surfactants increased PAH desorption, and all except R-95 substantially increased PAH biodegradation. POESH had the greatest effect, removing 50% of total measured PAHs. Brij 30, Span 20, and POESH were particularly effective at enhancing biodegradation of four- and five-ring PAHs, including five of the seven carcinogenic PAHs, with removals up to 80%. Surfactant amendment also significantly enhanced the removal of alkyl-PAHs. Most treatments significantly increased soil toxicity. Only the no-surfactant control and Brij 30 at the optimum dose significantly decreased soil genotoxicity, as evaluated with either mutant cell line. Overall, these findings have implications for the feasibility of bioremediation to achieve cleanup levels for PAHs in soil

Mn-Induced Surface Reconstructions on GaAs(001)

We have systematically studied the surface reconstructions induced by the adsoprtion of Mn atoms on GaAs(001). Several types of adsorption structures were observed depending on the preparation conditions, and were identified using complementary experimental techniques of reflection high-energy electron diffraction, scanning tunneling microscopy, reflectance difference spectroscopy, and X-ray photoelectron spectroscopy. The sequence of surface structures as a function of As coverage was confirmed by the experiments and first-principles calculations. Under the most Ga-rich conditions, (2 × 2)­α and (6 × 2) structures are formed, both having As atoms at faulted sites and Ga–Ga dimers at the third atomic layer. As the As coverage is increased, the structure with Ga–As dimer [(2 × 2)­β] becomes more stable, and, finally, the <i>c</i>(4 × 4) structure consisting of three As–As dimers is energetically favored at the As-rich limit. We found that the location of Mn atoms critically depends on the surface As coverage: As-deficient (2 × 2)­α, (6 × 2), and (2 × 2)­β structures have the Mn atoms at 4-fold hollow sites, while the incorporation of Mn atoms into the substitutional Ga sites is enhanced in the most As-rich <i>c</i>(4 × 4) structure, in which the upper limit of substitutional Mn is 0.25 ML

Chromosome location of GPI anchor synthesis genes.

<p>Chr: Chromosome; N.I.: not identified.</p

Biosynthesis of the glycosylphosphatidyl inositol (GPI)-anchored protein.

<p>Synthesis of GPI-anchored proteins involves multiple reaction steps. Briefly, the first step of GPI anchor biosynthesis is catalyzed by a multi-subunit GPI-<i>N</i>-acetylglucosaminyltransferase comprised of at least 6 different proteins (PIG-A, PIG-C, PIG-H, PIG-P, PIG-Q, PIG-Y). In addition, DPM2 appears to regulate this first step, followed by de-<i>N</i>-acetylation by the PIG-L. PIG-W then attaches an acyl chain to form glucosamine-(acyl)PI. In the next step, three mannose (Man) residues are added sequentially to glucosamine-(acyl)PI, generating Man-Man-Man-glucosamine-(acyl)PI by PIG-M/PIG-X complex, PIG-V, and PIG-B. After the Man-1 and Man-2 conjugation, PIG-N adds ethanolamine phosphates (EtNP) to the Man-1. In the final step of GPI anchor synthesis, PIG-O/PIG-F and PIG-G/PIG-F complexes attach EtNP to the Man-3 and Man-2, respectively, to generate the mature GPI anchor protein.</p

Cell survival after PA exposure.

<p>(<b>A</b>) In a low cell density experiment using a 24-well plate (2.5×10³ cells/250 µL/well), DT40 cells were exposed to PA (0.0221–0.125 nM). After a three-day cultivation, cell viability was determined by XTT. Each point represents the mean and S.D. (bars) from three independent experiments. (<b>B</b>) In a high cell density experiment using a 96-well plate (4×10⁴ cells/50 µl/well), DT40 cells were exposed to PA (0.5–1.2 nM). After a seven-day incubation, colony formation was scored visually using an inverted microscope. Each point represents the mean and S.D. (bars) from three independent experiments.</p

Spontaneous mutational spectrum of <i>PIG-O</i> gene in DT40 cells.

<p>Spontaneous mutational spectrum of <i>PIG-O</i> gene in DT40 cells.</p

First Synthesis of Porphyrin-Fused 1,10-Phenanthroline−Ruthenium(II) Complexes

Synthesis of [Ru(phenP)3](PF6)2, where phenP = phenanthrolinoporphyrin, has been achieved by the reaction of phenanthrolinoporphyrins with RuCl3 for the first time. The phenP reacted with Ru(II) to form RuL2(phenP)2+ complexes (L = 2,2′-bipyridine or 1,10-phenanthroline), which were converted into the dyads Ru−phenP(Zn) on treatment with zinc acetate