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61.
17O static and magic angle spinning NMR spectra are reported from three crystalline cyclic titanodiphenylsiloxanes at magnetic fields of 5.6, 14.1, and 17.6 T. These compounds allow the NMR parameters characteristic of Ti-O-Si environments to be determined. It appears from these data that the quadrupole interaction (C(Q)) of such environments is in the range of 3-3.5 MHz and that Si-O-TiO3 sites are less shifted than Si-O-TiO5. The relatively large isotropic chemical range observed suggests that for structurally and atomically disordered titanosilicate-based materials the very highest applied magnetic field may not produce the best 17O solid state NMR spectra. There appears to be a correlation between the 17O shift and Ti-O bondlength. 相似文献
62.
63.
The analysis of the infrared reflectivity spectrum of partially reduced rutile TiO1.96 reveals a plasmon-LO phonon coupling. Pure-phonon and plasmon frequencies and life times are determined by fit with an appropriate model using the factorized form of the dielectric function for the phonon modes added to a plasmon contribution also derived from the factorized form. Results are compared with data obtained in the insulating stoichiometric rutile. 相似文献
64.
65.
Choi HC Gray AJ Vicente CL Xia JS Gervais G Halperin WP Mulders N Lee Y 《Physical review letters》2004,93(14):145302
Superfluid 3He in high porosity aerogel is the system in which the effects of static impurities on a p-wave superfluid can be investigated in a systematic manner. We performed shear acoustic impedance measurements on this system (98% porosity aerogel) in the presence of magnetic fields up to 15 T at the sample pressures of 28.4 and 33.5 bars. We observed the splitting of the superfluid transition into two transitions in high fields in both bulk and liquid in aerogel. The field dependence of the splitting in aerogel resembles that of the bulk superfluid 3He caused by the presence and growth of the A1 phase. Our results provide the first evidence of the A1 phase in superfluid (3)He/aerogel. 相似文献
66.
Choi H Yawata K Haard TM Davis JP Gervais G Mulders N Sharma P Sauls JA Halperin WP 《Physical review letters》2004,93(14):145301
The specific heat of superfluid 3He, disordered by a silica aerogel, is found to have a sharp discontinuity marking the thermodynamic transition to superfluidity at a temperature reduced from that of bulk 3He. The magnitude of the discontinuity is also suppressed. This disorder effect can be understood from the Ginzburg-Landau theory which takes into account elastic quasiparticle scattering suppressing both the transition temperature and the amplitude of the order parameter. We infer that the limiting temperature dependence of the specific heat is linear at low temperatures in the disordered superfluid state, consistent with predictions of gapless excitations everywhere on the Fermi surface. 相似文献
67.
68.
Lagacé L Dumont J Brazeau G Soucy A Haché J Marquis V 《Journal of AOAC International》2002,85(5):1144-1147
A quick and simple method was developed for determination of formaldehyde in maple syrup. In this method, formaldehyde reacts with Fluoral P to form a complex which is chemically extracted by isobutanol and determined by spectrofluorimetry. Performance, as gauged by the limits of detection (0.16 mg/kg) and quantitation (0.21 mg/kg), recovery (>79%), and variability (1.9-16.1%, depending on fortification level and class of syrup) were superior to the current official AOAC standard method. 相似文献
69.
Belkacem Benmerad Achoura Guehria‐Laidoudi Fadila Balegroune Henrik Birkedal Gervais Chapuis 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):789-792
The structure of the title compound, [La(C5H6O4)(C5H7O4)‐(H2O)]·H2O, consists of dense layers formed by chains of one‐edge‐sharing LaO9(H2O) polyhedra, linked together by the glutarate ligand. The three‐dimensional polymeric structure, built up through connection of these layers by the hydrogen glutarate ligand, exhibits cavities accommodating a guest water molecule. The lanthanum ion is tenfold coordinated by four glutarates, acting as bridging–chelating carboxylate groups, by three hydrogen glutarates, three times monodentate, and by one water molecule. Its coordination polyhedron is highly distorted and intermediate between a bicapped dodecahedron and a tetracapped trigonal prism. Hydrogen bonding links the two water molecules and the framework built up from this polynuclear coordination polymer. A very short hydrogen bond, D?A = 2.484 (3) Å, links the protonated with the deprotonated acid groups in the hydrogen glutarate. 相似文献
70.
Ali Shahverdi Keun Su Kim Yasaman Alinejad Gervais Soucy 《Journal of nanoparticle research》2012,14(2):660-10
A simple, cost-effective and energy-efficient approach was developed for in situ purity enhancement and surface modification
of single-walled carbon nanotubes (SWCNTs) produced using an induction thermal plasma process. In this process, SWCNT-containing materials are thermally treated with oxygen flow inside a filtration chamber, while they are assembled into the
sheets during the synthesis process. Owing to selective thermal oxidation, the amount of amorphous carbon was significantly
reduced in the final product resulting in higher purity SWCNT-containing materials. Parametric study indicated that the amorphous
carbon content was noticeably diminished in the product at an oxygen volume concentration of 10% in the synthesis system.
Raman analysis indicated a decrease in the population of the SWCNTs with diameters smaller than 1.3 nm after in situ exposure
to 10 vol.% of oxygen. In addition to the successful reduction of amorphous carbon content, the oxygen-functionalized SWCNTs
were also observed in the final product using this process. 相似文献