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1.
Richard Combes Marie-Noëlle Levelut Bernard Trémillon 《Journal of Electroanalytical Chemistry》1978,91(1):125-131
Reactions between cerium trichloride and oxide ions were studied in NaCl+KCl (1/1) at 1000°K, by potentiometry with a calcia-stabilized zirconia membrane electrode. Titration curves clearly demonstrated the existence of soluble cerium oxychloride (CeO+) and precipitated cerium oxide (Ce2O3), with respective dissociation constants 10?11 and 10?30 (molality scale). The corresponding conditional solubility diagram {log S (CeIII)=f(pO2?)} is presented and discussed. 相似文献
2.
J.C. Peuzin 《Solid State Communications》1974,15(7):1203-1208
We show that in a magnetically and elastically uniaxial ferromagnetic insulator, a new type of inhomogeneous elastic wave may propagate along a 180° domain wall. A numerical example is given. 相似文献
3.
Zhongrui Chen Maxime Bert Simon Pascal Gabriel Canard Olivier Siri 《Tetrahedron letters》2019,60(38):151024
The transamination reaction of 2,5-diaminobenzoquinonediimine (QDI) with ethylenediamine gave fluorescent 1,2,3,4-tetrahydropyrazino[2,3-g]quinoxaline (1). When the same reaction was carried out with N,N’-bis(aminoethyl)-1,3-propanediamine, a novel cationic quinoxalinium species (2) was isolated, which can be further condensed with p-cyanobenzaldehyde to afford a benzimidazolo-fused quinoxaline dye (3) that is a water-soluble fluorophore in the UV–visible range. 相似文献
4.
Thi Thanh-Tâm Nguyên Claude Delseth Jean-Pierre Kintzinger Pierre-Alain Carrupt Pierre Vogel 《Tetrahedron》1980,36(19):2793-2797
Natural-abundance 17O-NMR spectra of 7-oxanorbornane exo-3-oxatricyclo [3.2.1.02.4]octane and their unsaturated derivatives (endo cyclic and exocyclic double bonds) have been measured. Linear correlation laws were observed for of these ethers/corresponding hydrocarbons. The “cyclization shifts” for δo in ethers were not correlated by the “cyclization shifts” for δc of the corresponding hydrocarbons. 相似文献
5.
Professor C.J. Scriba 《Historia Mathematica》1984,11(2):222-225
6.
F.R. Van Buren G.H.J. Broers A.J. Bouman C. Boesveld 《Journal of Electroanalytical Chemistry》1978,88(3):353-361
Results of an electrochemical method for the determination of oxygen ion diffusion coefficients DO2? in porous pellets of La0.50Sr0.50CoO3?y are presented. Log DO2? can be expressed as log DO2?=?(2.3±0.2) 103/T?(6.6±0.6) cm2 s?1. The activation energy Ea for the diffusion process equals 44 kJ mol?1. Further the related electrochemical measurement and the adjustment of the oxygen deficiency y are described. At 75°C the following empirical Nernst relation between the electrode potential E (vs. a Pt/H2 (1 atm) electrode in the same solution) and Δy is found: E=627–108 ln (Δy + 0.0054) mV. (Δy=y?y0; y0=mole fraction of vacancies at the reversible O2 potential of 1190 mV). The use of La0.50Sr0.50CoO3?y as a solid solution electrode in practical storage cells seems to be excluded for thermodynamic and kinetic reasons. 相似文献
7.
On invariant states and the commutant of a group of quasi-free automorphisms of the CAR algebra. III
Akitaka Kishimoto 《Reports on Mathematical Physics》1979,16(1):121-124
It is shown that a state of the CAR algebra is an extreme invariant state under the group of quasi-free automorphisms αU with unitaries u in a von Neumann algebra M on the one- particle Hilbert space if and only if it is a gauge-invariant quasi-free state Ø A corresponding to A in M' with 0 ≤ A ≤ 1, under the assumption that M does not contain any finite type I factor direct summands. 相似文献
8.
Alkynylsilanes add photochemically to cyclopentenone to give bicyclo[3.2.0]heptenones. The photochemical rearrangement of adducts was studied. A method to eliminate the trimethylsilyl substituent is proposed. The structure of adducts is proved by spectroscopy, mainly 13C NMR. 相似文献
9.
Doriane Gérard Marc Guéroult Leticia Casas-Godoy Jean-Stéphane Condoret Isabelle André Alain Marty Sophie Duquesne 《Tetrahedron: Asymmetry》2017,28(3):433-441
Enzyme-catalyzed enantiomer discrimination is still a great challenge for the development of industrial pharmaceutical processes. For the resolution of ibuprofen, naproxen and ketoprofen racemates, three major anti-inflammatory drugs, only lipases from Candida rugosa present a high selectivity if solvent and surfactant use is discarded. However, their catalytic activities are too low. In the present work, we demonstrate that the lipase Lip2p from the yeast Yarrowia lipolytica has a higher catalytic activity than C. rugosa lipases to hydrolyze the ethyl esters of ibuprofen, naproxen and ketoprofen, but its selectivity is not sufficient [E = 52 (S); 11 (S) and 1.5 (R) respectively]. The enantioselectivity was further improved by site-directed mutagenesis, targeted at the substrate binding site and guided by molecular modelling studies. By investigating the binding modes of the (R)- and (S)-enantiomers in the active site, two amino acid residues located in the hydrophobic substrate binding site of the lipase, namely residues 232 and 235, were identified as crucial for enantiomer discrimination and enzyme activity. The (S) enantioselectivity of Lip2p towards ethyl ibuprofen esters was rendered infinite (E ? 300) by replacing V232 by an A or C residue. Substitution of V235 by C, M, S, or T amino acids led to a great increase in the (S)-enantioselectivity (E ? 300) towards naproxen ethyl ester. Finally, the variant V232F enabled the efficient kinetic resolution of ethyl ketoprofen ester enantiomers [(R)-enantiopreference; E ? 300]. In addition to the increase in selectivity, a remarkable increase in velocity by 2.6, 2.7 and 2.5 times, respectively, was found for ibuprofen, naproxen and ketoprofen ethyl esters. 相似文献
10.
J.M. Costantini D. Damien C.H. de Novion A. Blaise A. Cousson H. Abazli M. Pagès 《Journal of solid state chemistry》1983,47(2):219-224
We describe the preparation and some physical properties of Pu2O2Te. The plutonium oxide telluride is isostructural with the corresponding rare-earth oxide tellurides which crystallize in the tetragonal system of La2O2Te-type. Magnetic susceptibility data from 4 K to room temperature are reported together with resistivity measurements. Pu2O2Te is found to be an antiferromagnet below 56 K and a semiconductor with an intrinsic energy gap of 0.65 eV. The magnetic behavior is interpreted in terms of superexchange coupling interactions via nonmetal p orbitals, i.e., in terms of 5f-p overlaps. This conclusion is supported by crystal chemistry considerations by comparison of cell volumes of Pu2O2Te and Nd2O2Te. In Pu2O2Te, the Pu crystal radius is found to be much lower than that of Nd in Nd2O2Te, suggesting some 5f electron “delocalization” leading to a crystal radius shrinkage. As for the hexagonal Pu2O2X compounds, with X = O, S, Se, the measured gap may be considered as the energy separation between the chalcogen np band and the 6d-7s conduction band, the occupied 5f states lying just below the np band with some 5f-np overlap. 相似文献