Search results for "Oct"
showing 10 items of 3052 documents
Local structure studies of SrTi16O3and SrTi18O3
2014
In this work we report on the local structure of Ti in SrTi 16 O3 (STO16) and SrTi 18 O3 (STO18) investigated in the low temperature range (6‐300K) by extended x-ray absorption fine structure and x-ray absorption near edge structure (XANES) spectroscopy at Ti K-edge and by optical second harmonic generation (SHG). By comparing XANES of STO16 and STO18 we have identified the isotopic effect which produces at T < 100K a noticeable difference in the measured mean square relative displacements (MSRD) of Ti‐O1 bonds: while STO16 follow the expected Einstein-like behavior, for STO18 we have measured an increase of MSRD values with decreasing temperature. This is an indication of an increasing off…
« Doctrine et pensée juridique, XIIe-XVIIIe siècles. La tentation globalisante »
2013
National audience
Synthesis and high-throughput testing of multilayered supported ionic liquid catalysts for the conversion of CO2 and epoxides into cyclic carbonates
2014
Multilayered covalently supported ionic liquid phase (mlc-SILP) materials were synthesised by grafting different bis-vinylimidazolium salts on thiol-functionalised silica. These materials, which contain a cross-linked oligomeric network of imidazolium units, were characterised and tested as catalysts for the reaction of carbon dioxide with various epoxides to produce cyclic carbonates. The materials prepared by supporting a bis-imidazolium iodide salt with xylene or octane as a linker between the imidazolium units were identified as the most active catalysts and displayed high turnover numbers and improved productivity compared to known supported ionic liquid catalysts. The most promising m…
Baltijas valstu OCTA apdrošināšanas tirgus attīstība un to ietekmējošie faktori
2017
OCTA apdrošināšanas tirgus zaudējumi ir novērojami jau kopš 2010. g. Septiņu gadu laikā apdrošināšanas nozare nav nonākusi pie risinājuma, kā rezultātā OCTA apdrošināšanas tirgus varētu veiksmīgi strādāt. Bakalaura darba mērķis ir, pamatojoties uz finanšu rādītājiem, statistikas analīzi un Eiropas Savienības regulējumu, pierādīt, ka zaudējumu attīstības faktors ietekmē OCTA apdrošināšanas tirgu. Mērķa īstenošanai tiks pētīta literatūra un zinātniskie darbi par apdrošināšanu un tās aspektiem, tiks izpētīti Baltijas valstu OCTA apdrošināšanas tirgus rezultāti. Kā arī, ar zaudējumu attīstības modeli, tiks analizēts OCTA apdrošināšanas tirgus, sniedzot secinājumus, kā zaudējumu attīstības fakto…
Latvijā aizstāvētās doktora disertācijas (1923-1944): bibliogrāfisks rādītājs
2004
Grāmata no sērijas "Latvijas Universitātei 85"
Zirconium and hafnium complexes of the thio(bisphenolato) ligand: synthesis, structural characterization and testing as 1-hexenepolymerizationcatalys…
2009
Thio(bisphenolato) complexes of the type [M2(mu-tbop-kappa3O,S,O)2Cl4] [M = Zr 1, Hf 2 and tbop = 2,2-thiobis{4-(1,1,3,3-tetramethyl-butyl)phenolate}] were prepared by HCl elimination from tbopH2 and MCl4. Substitution of the chlorides in 1 and 2 by 2,6-diisopropylphenolato groups (dipp) generates new compounds [M2(mu-tbop-kappa3O,S,O)2(dipp)4] (M = Zr 3, Hf 4). The structures of 1-4 were confirmed by NMR spectroscopy; complexes 3 and 4 were further investigated by X-ray crystallography. These studies showed 1-4 to be dimers either in the solid state or in solution and to have metal centers adopting distorted octahedral geometry. However treatment of MCl4 with [Al2(mu-OEt)2(tbop-kappa3O,S,O…
Y:BaZrO3 Perovskite Compounds I: DFT Study on the Unprotonated and Protonated Local Structures
2011
Y-doped BaZrO(3) derivatives were studied by density functional theory (DFT) to investigate the local arrangements of the octahedral sites in Pm3m cubic frameworks. Single- and double substitution of zirconium by yttrium were considered, including in the presence of a nearby oxygen vacancy. Although the structural symmetry of undoped barium zirconate was not modified after yttrium doping, the presence of yttrium induced several differences in the oxygen sites around it, according to the local geometrical arrangement of yttrium in the host matrix. As an example, the differences between such oxygen sites were shown in the presence of a proton. In this case, different stabilization energies ch…
Seasonal fluctuations and long-term persistence of pathogenic populations of Agrobacterium spp. in soils.
2002
ABSTRACT Short- and long-term persistence of pathogenic (i.e., tumor forming) agrobacteria in soil was investigated in six nursery plots with a history of high crown gall incidence. No pathogenic Agrobacterium strains were isolated in soil samples taken in fall and winter in any plots, but such strains were isolated from both bulk soils and weed rhizospheres (over 0.5 × 10 5 pathogenic CFU/g of bulk soil or rhizosphere) in three out of six plots in spring and summer. PCR amplifications of a vir sequence from DNA extracted from soil confirmed the presence of Ti plasmids in summer and their absence in fall and winter. The results indicate that strains that harbor a Ti plasmid had an unforesee…
Towards Iron(II) Complexes with Octahedral Geometry: Synthesis, Structure and Photophysical Properties
2020
The control of ligand-field splitting in iron (II) complexes is critical to slow down the metal-to-ligand charge transfer (MLCT)-excited states deactivation pathways. The gap between the metal-centered states is maximal when the coordination sphere of the complex approaches an ideal octahedral geometry. Two new iron(II) complexes (C1 and C2), prepared from pyridylNHC and pyridylquinoline type ligands, respectively, have a near-perfect octahedral coordination of the metal. The photophysics of the complexes have been further investigated by means of ultrafast spectroscopy and TD-DFT modeling. For C1, it is shown that&mdash
Titanium dioxide waveguides for supercontinuum generation and optical transmissions in the near-and mid-infrared
2019
International audience; We report the development of titanium dioxide-based waveguides for applications in the near-and mid-infrared. Thanks to embedded metal grating couplers, we demonstrate error free 10 Gbit/s optical transmissions at 1.55 and 2 µm. With additional management of the dispersion profile, we also demonstrate octave spanning supercontinuum in cm-long TiO2 waveguides.