In-situ infrared spectroscopy applied to the study of the electrocatalytic reduction of CO2 : Theory, practice and challenges

Acknowledgements RK and WAS thank the European Research Council (ERC) for the financial support under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 759743 – WUTANG). AC acknowledges the support of the Leverhulme Trust (RPG-2015-040) and OA thanks the University of Aberdeen for an Elphinstone Fellowship.Peer reviewedPostprin

Molecular and Electronic Structure of Electroactive Self-Assembled Monolayers

Self-assembled monolayers (SAMs) containing electroactive functional groups are excellent model systems for the formation of electronic devices by self-assembly. In particular ferrocene-terminated alkanethiol SAMs have been extensively studied in the past. However, there are still open questions related with their electronic structure including the influence of the ferrocene group in the SAM-induced work function changes of the underlying metal. We have thus carried out a thorough experimental and theoretical investigation in order to determine the molecular and electronic structure of ferrocene-terminated alkanethiol SAMs on Au surfaces. In agreement with previous studies we found that the Fc-containing alkanethiol molecules adsorb forming a thiolate bond with the Au surface with a molecular geometry 30 degrees tilted with respect to the surface normal. Measured surface coverages indicate the formation of a compact monolayer. On the other hand, contrary with previous observations, we found that the ferrocene group has little influence on the observed work function decrease which is largely determined by the alkanethiol. Furthermore, the ferrocene moiety lies 14 Å above the metal surface covalently bonded to the alkanethiol SAM and its HOMO is located at -1.6 eV below the Fermi level. Our results provide new valuable insight into the molecular and electronic structure of electroactive SAMs which are of fundamental importance in the field of molecular electronics.Fil: Méndez de Leo, Lucila Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: de la Llave, Ezequiel Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Scherlis Perel, Damian Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Williams, Federico Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Recherches sur les textes de la pyramide du roi Téti. Restitution des parois et étude comparative du programme d'inscription

Cette recherche porte sur les Textes des Pyramides gravés dans les appartements funéraires de la pyramide du roi Téti, premier pharaon de la VIe dynastie (vers 2350-2330 av. J.-C). Les appartements funéraires des pyramides à textes se composent notamment d'un couloir, d'une antichambre, d'une chambre contenant le sarcophage et d'une petite pièce anépigraphe nommée serdab . Les murs nord et sud de l'antichambre et de la chambre funéraire de Téti, ainsi que les murs est et ouest du couloir, ont été retrouvés complètement détruits. Le premier objectif était de procéder à la restitution au 1/5e de ces parois à partir de l établissement des fac-similés des fragments retrouvés lors de l'ouverture de la pyramide en 1881 par Gaston Maspero, puis lors des différentes campagnes de fouille postérieures. La plupart de ces blocs sont conservés dans un magasin de fouilles, à Saqqâra. La restitution des textes s appuie à la fois sur l étude des blocs conservés, celle du système graphique interne à la pyramide, et sur la comparaison avec les neuf autres pyramides à textes actuellement recensées. Pour les textes encore en place sur les autres parois, relevés épigraphiques et photographiques sont nécessaires en vue d'une publication complète des textes. Le deuxième objectif de ce travail consistait à confronter le programme d inscription de cette pyramide avec celui des autres pyramides à textes, notamment la précédente (Ounas) et la suivante (Pépy Ier). Ce second volet met en lumière un certain nombre de principes adoptés par les concepteurs égyptiens.This study revolves around the pyramid texts engraved in the funerary apartments of the King Teti pyramid, first pharaoh of the 6th dynasty (around 2350-2330 B.C.). These funerary apartments of the text pyramids consist namely of a corridor, an antechamber, a sarcophagus chamber and a small anepigraphic room called serdab . The northern and southern walls of the antechamber and the funerary chamber of Teti, in addition to the ones to the east and west of the corridor were found completely destroyed. The primary goal was to carry out a restitution to the 1/5th of these walls through assessing the facsimiles of the fragments found during the opening of the pyramid in 1881 by Gaston Maspero, and during the various excavation campaigns carried out later on. Most of the blocks were kept in an excavation warehouse in Saqqara. The restitution of texts is based both on the study of the conserved blocks, that of the internal diagrammatic system of the pyramid, and on a comparison with the nine other pyramids with texts known today. As per the texts still present on the other walls, epigraphic and photographic surveys are necessary in sight of a complete publication of the texts. The second objective of this work consisted in comparing the inscription programme of this pyramid with that of the other text pyramids, namely the one prior to it (Unas) and the next one (Pepy I). This second section sheds the light on a number of principles adopted by the Egyptian designers.MONTPELLIER-BU Lettres (341722103) / SudocSudocFranceF

In situ infrared reflection absorption spectroscopy studies of the interaction of Nafion (R) with the Pt electrode surface

Infrared Reflection Absorption Spectroscopy (IRRAS) has been applied to study the nature of the co-ordination of Nafion(R) to a Pt electrode surface. The experiments have been carried out using a Pt electrode coated with a thin film of Nafion(R) assembled into a thin layer spectroelectrochemical cell. The potential modulation or the subtractively normalized interfacial Fourier transform infrared reflection spectroscopy (SNIFTIRS) experiments have been performed, in order to distinguish between the bulk properties of the Nation(R) membrane and the properties of the membrane at the interace with the Pt electrode. The results showed that the interaction between the membrane and a Pt electrode resembles the interaction between a Pt electrode and a sulfuric acid solution

Electrochemical and Photon Polarization Modulation Infrared Reflection Absorption Spectroscopy Study of the Electric Field Driven Transformations of a Phospholipid Bilayer Supported at a Gold Electrode Surface

Electrochemistry and polarization modulation Fourier transform infrared reflection absorption spectroscopy (PM-FTIRRAS) was employed to investigate fusion of small unilamellar vesicles of 1,2dioyl-sn-glycero-3-phosphatidyl choline (DOPC) onto the Au(111) electrode. Electrochemical studies demonstrated that the DOPC vesicles fuse and spread onto the gold electrode surface at small charge densities −8 μC cm(−2) < σ(M) < 0 μC cm(−2)(if the static electric field is <2 × 10(8) V/m) to form a bilayer. At σ(M) < −8 μC cm(−2), the film is detached from the electrode surface; however, the film remains in close proximity to the surface. The PM-FTIRRAS experiments demonstrated that the field-driven transformation of the film involves changes in hydration, orientation, and conformation in the polar headgroup region and that changes in the packing and tilt of the acyl chains are consequences of the headgroup rearrangements

Alignment of the spacers between trnS and trnG and rpL20-5’rpS12 in 87 samples from Sabatia kennedyana, representing the northern (NS, Canada), central (MA, USA) and southern (NC, USA) range of the species.

The spacers between trnS and trnG and rpL20-5’rpS12 were aligned with a consensus length of 1161 bp which was reduced to 812 bp after removing gaps and missing data. Among the 87 samples, 28 cpDNA haplotypes harbouring 38 informative sites were identified in 812 bp. Haplotype sequences were deposited in the GenBank database under accession numbers JX003130 –JX003186 for the rpL20-5’rpS12 intergenic spacer and JX003187 – JX003245 for the trnS-trnG intergenic spacer

Data from: Rethinking refugia: tree topology, divergence dates, and demographic history trace the distribution of the endangered Plymouth gentian (Sabatia kennedyana) from the Pleistocene glaciation to present day

Premise of study: Molecular population genetics is a powerful tool to infer how species responded to past environmental change. In the northern hemisphere, interest is increasing in how species responded to changes in ice coverage and temperature during the last glaciation maximum (LGM, between 18000–21000 yr ago) with a common assumption that glacial refugia were located at the southern edge of a species range. Methods: We reconstructed the glacial and postglacial phylogeography of Sabatia kennedyana, a member of the Atlantic Coastal Plains Flora with a current distribution from Nova Scotia (NS) to South Carolina, using both cpDNA and nuclear markers. We also examined clinal variation in morphological traits, in particular relative investment in asexual vs sexual growth. Key results: We find strong evidence that the species did not reside in southern glacial refugia, but rather in primary glacial refugia off the exposed continental shelf extending from Cape Cod and that this area was responsible for the founding of modern populations across the range from Nova Scotia (NS) to the United States. Additionally, based on the finding of higher cpDNA diversity and older cpDNA lineages in NS, we propose that multiple founder events occurred in NS, while only a single lineage gave rise to current populations in the United States. Conclusions: By understanding how S. kennedyana responded to past shifts in climate and by identifying areas of high genetic diversity in the northern range edge, we discuss the potential response of the species to future climate change scenarios