Synthèse et caractérisation de la solution solide ZN1-xCUx(IO3)2

L’analogie structurale qui existe entre les iodates des métaux (II) (Zn, Mn, Mg, Co et Ni) et l’iodate du cuivre nous a permis de synthétiser des iodates bimétalliques. Cette analogie provient du réseau anionique IO3- constituant un empilement hexagonal pseudo compact dans lequel les cations occupent les sites octaédriques. L’étude du cas de Zn1-xCux(IO3)2 confirme l’existence de solution solide qui suit la loi de Vegard sur l’ensemble du domaine de composition. Malheureusement, la qualité des cristaux de ces composés bimétalliques était fortement altérée, d’où leur développement comme matériau pour l’optique non linéaire quadratique, apparaît compromis

Characterization of Shewanella oneidensis MtrC: a cell-surface decaheme cytochrome involved in respiratory electron transport to extracellular electron acceptors

MtrC is a decaheme c-type cytochrome associated with the outer cell membrane of Fe(III)-respiring species of the Shewanella genus. It is proposed to play a role in anaerobic respiration by mediating electron transfer to extracellular mineral oxides that can serve as terminal electron acceptors. The present work presents the first spectropotentiometric and voltammetric characterization of MtrC, using protein purified from Shewanella oneidensis MR-1. Potentiometric titrations, monitored by UV–vis absorption and electron paramagnetic resonance (EPR) spectroscopy, reveal that the hemes within MtrC titrate over a broad potential range spanning between approximately +100 and approximately -500 mV (vs. the standard hydrogen electrode). Across this potential window the UV–vis absorption spectra are characteristic of low-spin c-type hemes and the EPR spectra reveal broad, complex features that suggest the presence of magnetically spin-coupled low-spin c-hemes. Non-catalytic protein film voltammetry of MtrC demonstrates reversible electrochemistry over a potential window similar to that disclosed spectroscopically. The voltammetry also allows definition of kinetic properties of MtrC in direct electron exchange with a solid electrode surface and during reduction of a model Fe(III) substrate. Taken together, the data provide quantitative information on the potential domain in which MtrC can operate

K2Au(IO3)5 and βâ KAu(IO3)4: Polar Materials with Strong SHG Responses Originating from Synergistic Effect of AuO4 and IO3 Units

Two new polar potassium gold iodates, namely, K2Au(IO3)5 (Cmc21) and βâ KAu(IO3)4 (C2), have been synthesized and structurally characterized. Both compounds feature zeroâ dimensional polar [Au(IO3)4]â units composed of an AuO4 squareâ planar unit coordinated by four IO3â ions in a monodentate fashion. In βâ KAu(IO3)4, isolated [Au(IO3)4]â ions are separated by K+ ions, whereas in K2Au(IO3)5, isolated [Au(IO3)4]â ions and nonâ coordinated IO3â units are separated by K+ ions. Both compounds are thermally stable up to 400â °C and exhibit high transmittance in the NIR region (λ=800â 2500â nm) with measured optical band gaps of 2.65â eV for K2Au(IO3)5 and 2.75â eV for βâ KAu(IO3)4. Powder secondâ harmonic generation measurements by using λ=2.05â μm laser radiation indicate that K2Au(IO3)5 and βâ KAu(IO3)4 are both phaseâ matchable materials with strong SHG responses of approximately 1.0 and 1.3 times that of KTiOPO4, respectively. Theoretical calculations based on DFT methods confirm that such strong SHG responses originate from a synergistic effect of the AuO4 and IO3 units.Work together: Two new polar iodates, namely, K2Au(IO3)5 (Cmc21) and βâ KAu(IO3)4 (C2), with strong SHG effects (1.0 and 1.3 times that of KTiOPO4) have been discovered (see figure). Theoretical calculations confirm that such strong secondâ harmonic generation (SHG) responses originate from the synergistic effect of the AuO4 and IO3 units.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137203/1/chem201504117-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137203/2/chem201504117.pd

Creating and curating an archive: Bury St Edmunds and its Anglo-Saxon past

This contribution explores the mechanisms by which the Benedictine foundation of Bury St Edmunds sought to legitimise and preserve their spurious pre-Conquest privileges and holdings throughout the Middle Ages. The archive is extraordinary in terms of the large number of surviving registers and cartularies which contain copies of Anglo-Saxon charters, many of which are wholly or partly in Old English. The essay charts the changing use to which these ancient documents were put in response to threats to the foundation's continued enjoyment of its liberties. The focus throughout the essay is to demonstrate how pragmatic considerations at every stage affects the development of the archive and the ways in which these linguistically challenging texts were presented, re-presented, and represented during the Abbey’s history

Crystal Structures of the Europium and Yttrium Hydroxychromate: Eu(OH)(CrO4) and Y(OH)(CrO4). Structural evolution as a function of the Ln3+ ionic radius.

International audienceThe Eu(OH)(CrO4) and Y(OH)(CrO4) compounds were obtained under hydrothermal conditions and characterized by single crystal X-ray diffraction analysis. They are isostructural and crystallize in the monoclinic system, space group P21/n (no. 14) with lattice parameters a = 8.278(1) Å, b = 11.400(2) Å, c = 8.393(1) Å, β = 93.76(2)°, V = 790.3(2) Å3, Z = 4, d = 4.79 g.cm-3 for Eu(OH)(CrO4) and a = 8.151(1) Å, b = 11.362(2) Å, c = 8.285(1) Å, β = 94.23(1)°, V = 765.2(2) Å3, Z = 4, d = 3.85 g.cm-3 for Y(OH)(CrO4). The [EuO8] polyhedra form infinite double chains along the a direction which are connected by common edges and corners. These double chains are related together in the two other directions via the [CrO4]2- tetrahedra to form a three-dimensional network in which channels appear parallel to the [100] direction. We examine the structural evolution, as a function of the Ln3+ ionic radius, in the series Ln(OH)(CrO4) compounds (with Ln = Nd, Eu, Gd, Tb, Er, Yb) and Y(OH)(CrO4). To determine the best coordination number of each lanthanide and yttrium ions, different calculations of bond valence sum have been realized

Promising Material for Infrared Nonlinear Optics: NaI3O8 salt containing a New Octaoxotriiodate(V) Anion formed from Condensation of [IO3]- Iodate

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Titanyl Iodate - A Promising Material for Infrared Nonlinear Optics Showing Structural Similarities with KTP

International audienceA new nonlinear compound, TiO(IO3)2, was synthesized by the hydrothermal method and characterized by single-crystal X-ray diffraction. It crystallizes in the acentric Cmc21 space group with the following lattice parameters: a = 10.222(1) Å, b = 8.254(1) Å, c = 7.277(1) Å, and V = 613.98(13) Å3. The structure has alternating Ti-O bond lengths, short [Ti-O 1.733(12) Å, titanyl bond] and long [Ti-O 2.113(12) Å], as observed in the KTiOPO4 (KTP) material. IR spectroscopy and NLO efficiency studies on a powder sample suggest that TiO(IO3)2 is a good potential NLO material

Ingénierie cristalline pour l'optique non linéaire quadratique (iodates métalliques)

La plupart des matériaux pour l'ONL quadratique actuellement commercialisés sont utilisés pour des applications dans le domaine de l'UV au proche infrarouge. Cependant, l'atmosphère présente deux autres fenêtres de transparence dans l'infrarouge : fenêtre II entre 3 et 5 m et fenêtre III entre 8 et 12 m. Les matériaux susceptibles de couvrir les besoins pour les applications entre 4 m et 12 m sont peu nombreux. Les composés d'iodates anhydres étudiés dans ce travail de formule générale M(IO3)n ou MM'(IO3)4 sont synthétisés soit par lente évaporation dans l'acide nitrique concentré soit en synthèse hydrothermale. Les études structurales menées par diffraction des rayons X sur poudre et sur monocristal, mettent en évidence une analogie entre les composés M(IO3)2, M(IO3)3 et a-LiIO3 qui permet l'obtention de solutions solides. Les composés étudiés présentent trois caractéristiques communes importantes : grande stabilité thermique en moyenne 500C, non hygroscopicité et très grande fenêtre de transparence qui s'étend en continue de l'UV, pour les composés incolores, vers l'infrarouge lointain en moyenne jusqu'à 13 m. De plus, ils présentent un seuil de dommage optique sur poudre de l'ordre de quelques GW.cm-2 et l'efficacité en doublement de fréquence est comparable voire supérieure à celle observée pour a-LiIO3. Par ailleurs, l'insertion d'éléments luminescents a pu être réalisée dans certaines de ces matrices. Nous disposons maintenant de toute une famille de matériaux potentiellement actifs (émission laser due à la présence d'éléments luminescents pour les lasers à longueurs d'ondes fixes ou accordables) et/ou passifs (doubleur de fréquence) qui pourraient répondre aux exigences requises pour les applications visées.Nowadays, most of quadratic NLO commercial materials are used for applications in the field of UV to the near infrared. However, the atmosphere presents two others windows of transparency in the infrared: window II between 3 and 5 m and window III between 8 and 12 m. The materials which can be used for applications between 4 m and 12 m are very few. Anhydrous iodate compounds studied in this work of general formula M(IO3)n or MM'(IO3)4 were synthesised either by slow evaporation in concentrated nitric acid or in hydrothermal synthesis. Structural analyses carried out by X-ray diffraction on powder and on single crystal, underline an analogy between M(IO3)2, M(IO3)3 and a-LiIO3 compounds which allows us to synthesise solid solutions. The compounds studied present three important common characteristics: great thermal stability on average 500C, non hygroscopicity and a very large window of transparency which extends continuously from UV, for colourless compounds, towards the far infrared on average up to 13 m. They also have an optical damage threshold equal to some GW.cm-2 on powder and an intensity of second harmonic generation signal similar or even higher than the one observed for a-LiIO3. Moreover, the insertion of luminescent elements could be done in several iodate matrices. We now have a whole family of potentially active materials (laser emission caused by luminescent elements for lasers with wavelengths fixed or tunable) and/or passive materials (frequency doubling) which could respond to the requirements for concerned applications.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF