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71.
The crystal structure of Yb2RuD6 has been determined by neutron powder diffraction and the results were consistent with the Fm3m (#225) space group, a=7.2352(18) Å, with the atoms arranged according to the well-known K2PtCl6 structure. No structural phase transition was observed in going from room temperature to 4 K. Raman spectra were not available due to fluorescence, but all fundamental bands and combination bands were assigned from FTIR and PAIR spectra only following previous studies for other alkaline earth and europium ruthenium ternary metal hydrides and deuterides. The deuterium nuclear quadrupole coupling constant, 40.9 kHz, leads to an ionic character of the Ru-D bond of 82%. 相似文献
72.
Müller SH Boedo JA Burrell KH DeGrassie JS Moyer RA Rudakov DL Solomon WM 《Physical review letters》2011,106(11):115001
The first measurements of turbulent stresses and flows inside the separatrix of a tokamak H-mode plasma are reported, using a reciprocating multitip Langmuir probe at the DIII-D tokamak. A strong co-current rotation layer at the separatrix is found to precede intrinsic rotation development in the core. The measured fluid turbulent stresses transport toroidal momentum outward against the velocity gradient and thus try to sustain the edge layer. However, large kinetic stresses must exist to explain the net inward momentum transport leading to co-current core plasma rotation. The importance of such kinetic stresses is corroborated by the success of a simple orbit loss model, representing a purely kinetic mechanism, in the prediction of features of the edge corotation layer. 相似文献
73.
The objective of this study was to determine if topical anesthesia to the larynx and pharynx affects vocal fold motion during dynamic voice evaluation with transnasal flexible endoscopy. Transnasal dynamic laryngeal examinations of 10 patients with no voice complaints were evaluated by five blinded fellowship-trained laryngologists. Each patient was examined before and after application of topical anesthetic. Reviewers rated briskness of right and left vocal fold movement and longitudinal tension on a visual analogue scale. Statistical comparisons were made between individual subject scores before and after anesthetic application. Inter-rater reliability was also assessed. No statistical difference was observed between subject scores before and after anesthetic application. Average intraclass correlation coefficients were 0.643 and 0.591 for pre- and postanesthesia scores, respectively. Application of topical anesthesia to the larynx and pharynx does not affect vocal fold motion. 相似文献
74.
75.
E.J. Moyer D.S. Sayres G.S. Engel J.M. St. Clair F.N. Keutsch N.T. Allen J.H. Kroll J.G. Anderson 《Applied physics. B, Lasers and optics》2008,92(3):467-474
Off-axis integrated cavity output spectroscopy (OA-ICOS) has generated much interest because it potentially allows highly
sensitive field measurements with robust optical alignment. We discuss here design choices involved in design of an OA-ICOS
instrument and how these choices impact instrument sensitivity, using as our example the design of the Harvard ICOS isotope
instrument, which demonstrates the highest reported sensitivity for mid-IR OA-ICOS (2.4×10-11 cm-1Hz-1/2 at 6.7 μm, obtained during measurements of water vapor isotopologues H2O, HDO, and H2
18O in the laboratory and onboard NASA’s WB-57 high-altitude research aircraft). We compare the sensitivity of several OA-ICOS
instruments with differing design parameters, show how comparisons are hindered by differing definitions of instrument performance
metrics, and suggest a common metric of MDAmeas, the fractional absorption equivalent to 1σ uncertainty in an actual measurement, normalized to 1 s integration. We also
note that despite an emphasis on sensitivity in the literature, in the Harvard ICOS isotope instrument and likely also similar
instruments, systematic errors associated with fitting of the baseline laser power are of equal importance to total measurement
uncertainty. 相似文献
76.
77.
John O. Edwards Thomas E. Erstfeld Khairat M. Ibne-Rasa Gerrit Levey Maria Moyer 《国际化学动力学杂志》1986,18(2):165-180
The hydrolysis kinetics of CICN have been reinvestigated from pH 0.0–10.5 and from 18–40°C. In the pH range from 1–5, the hydrolysis rate is invariant and the activation parameters (ΔH? = 84 kJ mol?1 and ΔS? = ?84 J mol?1 K?1) are consistent with water attack. In basic solution the rate is first order each in CICN and OH? concentrations with parameters ΔH? and ΔS? equal to 82 kJ mol?1 and + 54 J mol?1 K?1, respectively. The rate constants with 20 other donors have been measured. Nitrogen nucleophiles are more reactive than oxygen donors, and an alpha-effect is seen. The constants follow a pattern indicative of attack at carbon. Cyanate in its acid form reacts with nucleophiles. Further points on the cyanate rate–pH profile have been obtained. A chromate-catalyzed hydrolysis can contribute between pH 5–10. Some studies were made of the reaction of cyanate with hydrogen peroxide. Free energy correlations are presented. 相似文献
78.
This research study examines the instructional practices of 10 middle grades teachers related to their use of manipulatives in teaching mathematics and their control of mathematics tools during instruction. Through 40 observations of teaching, 30 interviews, and an examination of 67 written documents (including teachers' plans and records), profiles were developed that describe how teachers used and controlled manipulatives during instruction. Results showed that teachers used a variety of manipulatives and other mathematics tools over the course of the year‐long study. Teachers reported using a mathematics tool (manipulative, calculator, or measuring device) in 70% of their lessons, and this self‐report was verified by observations in which teachers used mathematics tools in 68% of their lessons. During a 3‐ to 4‐month period of “free access,” in which students had some measure of control in their selection and use of the mathematics tools, the students used manipulatives spontaneously and selectively. During free access, teachers exhibited various behaviors, including posting lists of items on containers, assigning group leaders to manage tools, and negotiating the control of the mathematics tools during instruction. 相似文献
79.
Moyer SC Cotter RJ Woods AS 《Journal of the American Society for Mass Spectrometry》2002,13(3):274-283
An investigation of phosphate loss from phosphopeptide ions was conducted, using both atmospheric pressure matrix-assisted laser desorption/ionization (AP MALDI) and electrospray ionization (ESI) coupled to an ion trap mass spectrometer (ITMS). These experiments were carried out on a number of phosphorylated peptides in order to investigate gas phase dephosphorylation patterns associated with phosphoserine, phosphothreonine, and phosphotyrosine residues. In particular, we explored the fragmentation patterns of phosphotyrosine containing peptides, which experience a loss of 98 Da under collision induced dissociation (CID) conditions in the ITMS. The loss of 98 Da is unexpected for phosphotyrosine, given the structure of its side chain. The fragmentation of phosphoserine and phosphothreonine containing peptides was also investigated. While phosphoserine and phosphothreonine residues undergo a loss of 98 Da under CID conditions regardless of peptide amino acid composition, phosphate loss from phosphotyrosine residues seems to be dependent on the presence of arginine or lysine residues in the peptide sequence. 相似文献
80.
Levitskaia TG Marquez M Sessler JL Shriver JA Vercouter T Moyer BA 《Chemical communications (Cambridge, England)》2003,(17):2248-2249
Beta-octafluoro-meso-octamethylcalix[4]pyrrole (1) and beta-decafluoro-meso-decamethylcalix[5]pyrrole (2) were found to extract caesium salts of smaller anions (bromide and chloride for 1 and nitrate for 2) as effectively as that of iodide into nitrobenzene (NB) thereby overcoming the Hofmeister bias normally observed for processes of this type. 相似文献