Alpha localized radiolysis and corrosion mechanisms at the iron/water interface: Role of molecular species

This paper is devoted to the iron corrosion phenomena induced by the α (4He2+) water radiolysis species studied in conjunction with the production/consumption of H2 at the solid/solution interface. On one hand, the solid surface is characterized during the 4He2+ ions irradiation by in situ Raman spectroscopy; on another hand, the H2 gas produced by the water radiolysis is monitored by ex situ gas measurements. The 4He2+ ions irradiation experiments are provided either by the CEMHTI (E = 5.0 MeV) either by the ARRONAX (E = 64.7 MeV) cyclotron facilities. The iron corrosion occurs only under irradiation and can be slowed down by H2 reductive atmosphere. Pure iron and carbon steel solids are studied in order to show two distinct behaviors of these surfaces vs. the 4He2+ ions water irradiation: the corrosion products identified are the magnetite phase (Fe(II)Fe(III)2O4) correlated to an H2 consumption for pure iron and the lepidocrocite phase (γ-Fe(III)OOH) correlated to an H2 production for carbon steel sample. This paper underlined the correlation between the iron corrosion products formation onto the solid surface and the H2 production/consumption mechanisms. H2O2 species is considered as the single water radiolytic species involved into the corrosion reaction at the solid surface with an essential role in the oxidation reaction of the iron surface. We propose to bring some light to these mechanisms, in particular the H2 and H2O2 roles, by the in situ Raman spectroscopy during and after the 4He2+ ions beam irradiation. This in situ experiment avoids the evolution of the solid surface, in particular phases which are reactive to the oxidation processing

Molecular Evolutionary Trends and Feeding Ecology Diversification in the Hemiptera, Anchored by the Milkweed Bug Genome

Background: The Hemiptera (aphids, cicadas, and true bugs) are a key insect order, with high diversity for feeding ecology and excellent experimental tractability for molecular genetics. Building upon recent sequencing of hemipteran pests such as phloem-feeding aphids and blood-feeding bed bugs, we present the genome sequence and comparative analyses centered on the milkweed bug Oncopeltus fasciatus, a seed feeder of the family Lygaeidae. Results: The 926-Mb Oncopeltus genome is well represented by the current assembly and official gene set. We use our genomic and RNA-seq data not only to characterize the protein-coding gene repertoire and perform isoform-specific RNAi, but also to elucidate patterns of molecular evolution and physiology. We find ongoing, lineage-specific expansion and diversification of repressive C2H2 zinc finger proteins. The discovery of intron gain and turnover specific to the Hemiptera also prompted the evaluation of lineage and genome size as predictors of gene structure evolution. Furthermore, we identify enzymatic gains and losses that correlate with feeding biology, particularly for reductions associated with derived, fluid nutrition feeding. Conclusions: With the milkweed bug, we now have a critical mass of sequenced species for a hemimetabolous insect order and close outgroup to the Holometabola, substantially improving the diversity of insect genomics. We thereby define commonalities among the Hemiptera and delve into how hemipteran genomes reflect distinct feeding ecologies. Given Oncopeltus’s strength as an experimental model, these new sequence resources bolster the foundation for molecular research and highlight technical considerations for the analysis of medium-sized invertebrate genomes

The genome of the water strider Gerris buenoi reveals expansions of gene repertoires associated with adaptations to life on the water.

BACKGROUND: Having conquered water surfaces worldwide, the semi-aquatic bugs occupy ponds, streams, lakes, mangroves, and even open oceans. The diversity of this group has inspired a range of scientific studies from ecology and evolution to developmental genetics and hydrodynamics of fluid locomotion. However, the lack of a representative water strider genome hinders our ability to more thoroughly investigate the molecular mechanisms underlying the processes of adaptation and diversification within this group. RESULTS: Here we report the sequencing and manual annotation of the Gerris buenoi (G. buenoi) genome; the first water strider genome to be sequenced thus far. The size of the G. buenoi genome is approximately 1,000 Mb, and this sequencing effort has recovered 20,949 predicted protein-coding genes. Manual annotation uncovered a number of local (tandem and proximal) gene duplications and expansions of gene families known for their importance in a variety of processes associated with morphological and physiological adaptations to a water surface lifestyle. These expansions may affect key processes associated with growth, vision, desiccation resistance, detoxification, olfaction and epigenetic regulation. Strikingly, the G. buenoi genome contains three insulin receptors, suggesting key changes in the rewiring and function of the insulin pathway. Other genomic changes affecting with opsin genes may be associated with wavelength sensitivity shifts in opsins, which is likely to be key in facilitating specific adaptations in vision for diverse water habitats. CONCLUSIONS: Our findings suggest that local gene duplications might have played an important role during the evolution of water striders. Along with these findings, the sequencing of the G. buenoi genome now provides us the opportunity to pursue exciting research opportunities to further understand the genomic underpinnings of traits associated with the extreme body plan and life history of water striders

Molecular evolutionary trends and feeding ecology diversification in the Hemiptera, anchored by the milkweed bug genome.

BACKGROUND: The Hemiptera (aphids, cicadas, and true bugs) are a key insect order, with high diversity for feeding ecology and excellent experimental tractability for molecular genetics. Building upon recent sequencing of hemipteran pests such as phloem-feeding aphids and blood-feeding bed bugs, we present the genome sequence and comparative analyses centered on the milkweed bug Oncopeltus fasciatus, a seed feeder of the family Lygaeidae. RESULTS: The 926-Mb Oncopeltus genome is well represented by the current assembly and official gene set. We use our genomic and RNA-seq data not only to characterize the protein-coding gene repertoire and perform isoform-specific RNAi, but also to elucidate patterns of molecular evolution and physiology. We find ongoing, lineage-specific expansion and diversification of repressive C2H2 zinc finger proteins. The discovery of intron gain and turnover specific to the Hemiptera also prompted the evaluation of lineage and genome size as predictors of gene structure evolution. Furthermore, we identify enzymatic gains and losses that correlate with feeding biology, particularly for reductions associated with derived, fluid nutrition feeding. CONCLUSIONS: With the milkweed bug, we now have a critical mass of sequenced species for a hemimetabolous insect order and close outgroup to the Holometabola, substantially improving the diversity of insect genomics. We thereby define commonalities among the Hemiptera and delve into how hemipteran genomes reflect distinct feeding ecologies. Given Oncopeltus's strength as an experimental model, these new sequence resources bolster the foundation for molecular research and highlight technical considerations for the analysis of medium-sized invertebrate genomes

LET effects on the hydrogen production induced by the radiolysis of pure water

Radiation chemical primary yields g(H2) have been determined for irradiations performed with 60Co γ-rays source of LCP (Orsay, France) and with helium ion beams (Eα=5.0 MeV-64.7 MeV) using protective agent bromide anions in solution. The α (4He2+) irradiation experiments were performed either at CEMHTI or at the new ARRONAX cyclotron facility (2010). Both sources (γ and cyclotrons) allow working with a large LET value range between 0.23 and 151.5 keV/μm. On one hand, the obtained results have been compared with those available in the literature and plotted as a function of the LET parameter in order to discuss the effects of track structure on the production of molecular hydrogen. On the other hand, the primary radiation chemistry yield g(H2) values are compared with global radiation chemical yields G(H2) obtained during irradiations of pure water irradiated under air or argon without scavenging. For each system, it appears that radiation chemical yields increase with the LET value. Our results suggest that using bromide anions, at low concentration, as a protective agent becomes ineffective when the LET value used is higher than 120±20 keV/μm

Relationship between the progress of the foliar pathogens caused by Septoria tritici and the reduction of the photosynthetic vitality of plants in Grand-Duchy of Luxembourg in 2004.

peer reviewe

Table of biomechanical variables

This table contains the quantitative biomechanical variable measured and analysed in our study

Tree

This file is the Bayesian phylogenetic reconstruction used to assess phenotypic complexity. The file could be open with a text editor software

H2 production by γ and He ions water radiolysis, effect of presence TiO2 nanoparticles

The effect of TiO2 particles on the yield of H2 formation under water radiolysis is measured. Irradiations were performed using a 60Co γ−ray source as well as with He ions particles (4He2+) generated by a cyclotron with an external beam energy of 6 MeV. The resulting hydrogen as a stable product of radiolysis was measured by mass spectrometry. G(H2) obtained for water radiolysis by He ions−irradiation in aerated and argon water are found to be 1.91 × 10−7 and 1.35 × 10−7 mol J−1, respectively. In the presence of titanium oxide anatase−type dispersed in water, under He ions−irradiation, G(H2) is found to increase slightly from 1.04 × 10−7 to 1.35 × 10−7 mol J−1 by increasing the specific surface from 8 to 253 m2/g, respectively. Under γ-irradiation, G(H2) is found to be 0.41 × 10−7 mol J−1 close to primary yield of hydrogen in presence of OH. Radical scavenger. In addition, radiolysis of water adsorbed in the titanium oxide with low water content, which corresponds to a few layers of water sorbed onto the solid surface gives a huge values of the G(H2). For the same amount of water, with using the dose absorbed by TiO2 particles, for He ions-irradiation, G(H2) increases from 14.5 × 10−7 to 35 × 10−7 mol J-1 by increasing the surface area of TiO2 nanoparticles from 4 to 52 m2/g, respectively. For γ−irradiation G(H2) is found to be 5.25 × 10−7 mol J-1 for the sample with 8 m2/g specific surface area

R_script_final

This file is the R script used for the different analysis conducted in this study, The file can be open using R studio