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991.
Hugh D. Burrows Carlos F. G. C. Geraldes Teresa J. T. Pinheiro Robin K. Harris Angelika Sebald 《Liquid crystals》2013,40(6-7):853-860
Abstract 207Pb N.M.R. data are reported for a number of even chain length lead(II) carboxylates (soaps) at various temperatures. At room temperature, the solid lead(II) decanoate and tetradecanoate show similar spectra, with a single metal ion site, and modest shielding anisotropy. As the temperature is increased, the soaps (hexanoate to octadecanoate) all form a highly ordered smectic phase, which gives a very broad 207Pb signal of linewidth comparable to that of the solid phase. At higher temperatures, the hexanoate to dodecanoate soaps form a lamellar L α (smectic A) phase, whilst the longer chain length carboxylates melt directly to the liquid phase. Both the lamellar L α and liquid phase give fairly sharp, isotropic signals, whose chemical shifts and linewidths are strongly temperature dependent. Possible explanations for this effect include paramagnetic contributions to the shielding tensor from low-lying electronic states of Pb(II), and contributions to the observed signal from different coordination species produced in the lead(II) carboxylate system. Although there are discrete changes in chemical shift at the phase transition, the magnitudes observed in all the phases are similar, suggesting that there are no dramatic changes in the metal coordination environment. 相似文献
992.
Thomas B. Osborne und Isaak Harris 《Fresenius' Journal of Analytical Chemistry》1910,49(3-4):142-146
Ohne ZusammenfassungNach dem Journal of Biological Chemistry Vol. III, Juli 1907, bearbeitet und übersetzt von Dr. V. Griessmayer. 相似文献
993.
A. J. Hall K. Schwertassek G. Garkuscha K. M. Markuse A. W. Ssurowaja A. P. Sakonschtschikow D. I. Galperin D. I. Tumarkin J. Barritt H. H. Bowen F. L. Goodall A. Whitehead H. R. Hirst A. T. King M. Harris A. L. Smith T. A. Schmelewa und R. Hart 《Fresenius' Journal of Analytical Chemistry》1940,120(5-6):216-220
Ohne Zusammenfassung 相似文献
994.
In this paper we introduce the crossed product construction for a discrete group action on an operator system. In analogy to the work of E. Katsoulis and C. Ramsey, we describe three canonical crossed products arising from such a dynamical system. We describe how these crossed product constructions behave under G-equivariant maps, tensor products, and the canonical -covers. We show that hyperrigidity is preserved under two of the three crossed products. Finally, using A. Kavruk's notion of an operator system that detects -nuclearity, we give a negative answer to a question on operator algebra crossed products posed by Katsoulis and Ramsey. 相似文献
995.
Abdolraouf Samadi-Maybodi Robin K. Harris S. Naser Azizi Alan M. Kenwright 《Magnetic resonance in chemistry : MRC》2001,39(8):443-446
Silicon-29 NMR spectra were obtained for more than 20 aqueous alkaline silicate solutions containing methanol. A signal assigned to CH3OSi(OH)3 or one of its deprotonated congeners was studied in detail for the first time for the solution conditions involved. Its appearance was monitored as a function of the solution compositions. The pseudo-equilibrium constant for its formation is of the order of 0.65. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
996.
997.
998.
P.R. Shearing L.E. Howard P.S. Jørgensen N.P. Brandon S.J. Harris 《Electrochemistry communications》2010,12(3):374-377
The 3-dimensional microstructure of a porous electrode from a lithium-ion battery has been characterized for the first time. We use X-ray tomography to reconstruct a 43 × 348 × 478 μm sample volume with voxel dimensions of 480 nm, subsequent division of the reconstructed volumes into sub-volumes of different sizes allow us to determine microstructural parameters as a function of sub-division size. We show that the minimum size for a representative volume element is about 43 × 60 × 60 μm for volume-specific surface area, but as large as the full sample volume for porosity and tortuosity. 相似文献
999.
J. Prescher F. Reiss F. E. Day M. Grimes H. D. Richmond F. Repiton Höyberg H. Weigmann Ulrich A. Ottiker L. J. Harris C. H. Biesterfeld O. L. Evenson D. Giribaldo und A. Peluffo 《Fresenius' Journal of Analytical Chemistry》1920,59(8-9):374-378
Ohne Zusammenfassung 相似文献
1000.
Tanja Radu Simon Gallagher Brian Byrne Paul Harris Seamus Coveney Stephen McCarron 《光谱学快报》2013,46(7):516-526
Case studies from two sites demonstrate how concentration distributions of hazardous contaminants can be rapidly measured and visualized using portable XRF (X-ray fluorescence) coupled with geostatistical interpolation tools. In this study, lead is used as an exemplar due to its well-known detrimental effect on human health through long-term exposure. A portable Thermo Scientific NITON X-ray fluorescence (XRF) instrument was used for real-time in-situ concentration measurements, which were linked to GPS coordinates of the sampling locations. A 52 point mixed sampling density survey was performed at a site near Maynooth, Co. Kildare, and a second 58 survey undertaken at Dublin City University (DCU). At Maynooth, high concentrations of Pb (above 110 mg/kg) were found close to the site where a local canal meets a road. At the DCU site, results indicate high Pb concentrations (above 160 mg/kg) near a busy main road. Geostatistical techniques were used to generate concentration prediction and critical threshold contour surfaces for both sites. Linked with GPS coordinates for each sampling location, this technology enables the distribution of multiple elements to be mapped over wide areas in a relatively short time. Supplemental materials are available for this article. Go to the publisher's online edition of Spectroscopy Letters to view the supplemental file. 相似文献