Saccharomyces cerevisiae-based system for studying clustered DNA damages

DNA-damaging agents can induce clustered lesions or multiply damaged sites (MDSs) on the same or opposing DNA strands. In the latter, attempts to repair MDS can generate closely opposed single-strand break intermediates that may convert non-lethal or mutagenic base damage into double-strand breaks (DSBs). We constructed a diploid S. cerevisiae yeast strain with a chromosomal context targeted by integrative DNA fragments carrying different damages to determine whether closely opposed base damages are converted to DSBs following the outcomes of the homologous recombination repair pathway. As a model of MDS, we studied clustered uracil DNA damages with a known location and a defined distance separating the lesions. The system we describe might well be extended to assessing the repair of MDSs with different compositions, and to most of the complex DNA lesions induced by physical and chemical agents

Identifying Where REDD+ Financially Out Competes Oil Palm in Floodplain Landscapes Using a Fine-Scale Approach

Reducing Emissions from Deforestation and forest Degradation (REDD+) aims to avoid forest conversion to alternative land-uses through financial incentives. Oil-palm has high opportunity costs, which according to current literature questions the financial competitiveness of REDD+ in tropical lowlands. To understand this more, we undertook regional finescale and coarse-scale analyses (through carbon mapping and economic modelling) to assess the financial viability of REDD+ in safeguarding unprotected forest (30,173 ha) in the Lower Kinabatangan floodplain in Malaysian Borneo. Results estimate 4.7 million metric tons of carbon (MgC) in unprotected forest, with 64% allocated for oil-palm cultivations. Through fine-scale mapping and carbon accounting, we demonstrated that REDD+ can outcompete oil-palm in regions with low suitability, with low carbon prices and low carbon stock. In areas with medium oil-palm suitability, REDD+ could outcompete oil palm in areas with: very high carbon and lower carbon price; medium carbon price and average carbon stock; or, low carbon stock and high carbon price. Areas with high oil palm suitability, REDD + could only outcompete with higher carbon price and higher carbon stock. In the coarse-scale model, oil-palm outcompeted REDD+ in all cases. For the fine-scale models at the landscape level, low carbon offset prices (US $3 MgCO2e) would enable REDD+ to outcompete oil-palm in 55$27 million to secure these areas for 25 years. Higher carbon offset price (US $30 MgCO2e) would increase the competitiveness of REDD+ within the landscape but would still only capture between 69$380–416 million in carbon financing. REDD+ has been identified as a strategy to mitigate climate change by many countries (including Malaysia). Although REDD+ in certain scenarios cannot outcompete oil palm, this research contributes to the global REDD+ debate by: highlighting REDD+ competitiveness in tropical floodplain landscapes; and, providing a robust approach for identifying and targeting limited REDD+ funds

Structural characterization and electrochemical behavior of titanium carbon thin films

Symposium K on Protective Coatings and Thin Films held at the European-Materials-Research-Society Spring Meeting (E-MRS), Nice, FRANCE, MAY 09-13, 2011In the present work we report the results concerning the synthesis of Ti-C films obtained by a co-sputtering process of both titanium and graphite targets. The titanium content within the coatings has been adjusted in a wide range, allowing different structures of the films, to be formed. The chemical composition of the films was determined by X-ray photoelectron spectroscopy (XPS). Phase structure was analyzed by grazing angle X-ray diffraction (GXRD), while the morphology and microstructure were investigated by scanning electron microscopy (SEM). The possibility of using the resulting materials for electrochemical applications was also examined. For these purposes, the Ti-C films used as electrodes were investigated in terms of both reactivity and stability. Electrochemical investigations were carried out by using cyclic voltammetry and spectroscopy electrochemical techniques. (C) 2011 Elsevier B.V. All rights reserved

Two-step approach for the nanofabrication of highly ordered ultra-long porous gold nanowires with an adjustable porosity for SERS-based sensors

Recently, nanoporous gold has been pointed out as a promising candidate for the development of SERS-based sensors for the detection of environmental toxins and small molecules [1]. One way to improve the detection ability of such sensors is by engineering the porosity and shape of nanoporous material. In this work we report on a versatile two-step approach for the synthesis of porous nanowires involving plasma deposition of gold-copper alloy on a nanograted substrate followed by a selective electrochemical etching. The relevance of the approach is its ability to prepare highly ordered ultra-long porous gold nanowires with an adjustable porosity and a length up to the macroscale. The resulting gold porous nanowire exhibits a very high roughness and high specific surface area suitable for highly sensitive detection of small molecules by SERS. References: [1] L. Zhang, H. Chang, A. Hirata, H. Wu,Q.-K. Xue and M. Chen, ACS Nano 7, 4595 (2013

Visible Light-Driven Electron Transfer from a Dye-Sensitized p-Type NiO Photocathode to a Molecular Catalyst in Solution: Toward NiO-Based Photoelectrochemical Devices for Solar Hydrogen Production

International audienceThe photoelectrochemical activity of a mesoporous NiO electrode sensitized by a ruthenium complex was investigated with several rhodium and cobalt H-2-evolving catalysts. Photocurrent as high as 80 mu A/cm(2) was produced by irradiation of such photocathode in the presence of the Rh(III) polypyridyl complexes, while cobalt complexes gave almost no photocurrent. Photolysis experiments led to the two-electron reduced form of the Rh(III) complexes into Rh(I) complexes and demonstrate the occurrence of an electron transfer chain from NiO to the catalyst. Mott-Schottky experiments evidenced the pH dependence of the NiO flat band potential, explaining the dramatic drop of the photocurrent in acidic conditions (cyanoanilinium). By contrast, in weaker acid conditions (formic acid) the photocurrent increases and the key Rh(III) hydride intermediate was efficiently generated. In acetonitrile solution, Rh(III)-H slowly reacts with HCOOH to generate H-2. However, this process was not catalytic, because the reduction potential of the Ru sensitizer is not sufficiently negative to reduce the Rh(III)-H into Rh(II)-H