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421.
422.
Hoyt DW Turcu RV Sears JA Rosso KM Burton SD Felmy AR Hu JZ 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,212(2):378-385
A high-pressure magic angle spinning (MAS) NMR capability, consisting of a reusable high-pressure MAS rotor, a high-pressure rotor loading/reaction chamber for in situ sealing and re-opening of the high-pressure MAS rotor, and a MAS probe with a localized RF coil for background signal suppression, is reported. The unusual technical challenges associated with development of a reusable high-pressure MAS rotor are addressed in part by modifying standard ceramics for the rotor sleeve by abrading the internal surface at both ends of the cylinder. In this way, not only is the advantage of ceramic cylinders for withstanding very high-pressure utilized, but also plastic bushings can be glued tightly in place so that other removable plastic sealing mechanisms/components and O-rings can be mounted to create the desired high-pressure seal. Using this strategy, sealed internal pressures exceeding 150 bars have been achieved and sustained under ambient external pressure with minimal loss of pressure for 72 h. As an application example, in situ13C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg2SiO4) reacted with supercritical CO2 and H2O at 150 bar and 50 °C are reported, with relevance to geological sequestration of carbon dioxide. 相似文献
423.
We give a brief discussion of some of the contributions of Peter Lax to Computational Fluid Dynamics. These include the Lax-Friedrichs and Lax-Wendroff numerical schemes. We also mention his collaboration in the 1983 HLL Riemann solver. We develop two-dimensional Lax-Friedrichs and Lax-Wendroff schemes for the Lagrangian form of the Euler equations on triangular grids. We apply a composite scheme that uses a Lax-Friedrichs time step as a dissipative filter after several Lax-Wendroff time steps. Numerical results for Noh’s infinite strength shock problem, the Sedov blast wave problem, and the Saltzman piston problem are presented. 相似文献
424.
Clive Oppenheimer Mike R. Burton Jacques Durieux David M. Pyle 《Optics and Lasers in Engineering》2002,37(2-3)
We report here novel field spectroscopic measurements of the proportions of H2O, CO2, CO and SO2 in gas emissions from Oldoinyo Lengai, the world's unique, active carbonatite volcano. We found that CO2 constitutes <40 mol% of emissions from a lava lake, and 25 mol% from a cooler fumarole vent. These results suggest that H2O is the predominant gas phase rather than CO2, as reported in previous studies based on conventional sampling (Trans. Am. Geophys. Union 69 (1998) 1466; J. Geophys. Res. 101 (1996) 13819), though it is possible that water is introduced by remelting of older hydrated lava flows. We also observed rapid variations in CO2/CO molar ratios (between 450 and 750 in 1 h) in the lava lake emissions, which could reflect mixing of gases exsolved from deep and shallow magma. Lengai's measured CO2 flux (J. Geophys. Res. 101 (1996) 13819; Geology 23 (1995) 933) exceeds the time-averaged magma discharge rate, suggesting efficient separation of carbon and water-rich fluids from unerupted silicate magma. This may play an important role in parental magma differentiation. 相似文献
425.
N Lozano WT Al-Jamal A Taruttis N Beziere NC Burton J Van den Bossche M Mazza E Herzog V Ntziachristos K Kostarelos 《Journal of the American Chemical Society》2012,134(32):13256-13258
The design of liposome-nanoparticle hybrids offers a rich toolbox for the fabrication of multifunctional modalities. A self-assembled liposome-gold nanorod hybrid vesicular system that consists of lipid-bilayer-associated gold nanorods designed to allow deep tissue detection, therapy, and monitoring in living animals using multispectral optoacoustic tomography has been fabricated and characterized in vitro and in vivo. 相似文献
426.
Melih Ozlen Benjamin A. Burton Cameron A. G. MacRae 《Journal of Optimization Theory and Applications》2014,160(2):470-482
This paper introduces an improved recursive algorithm to generate the set of all nondominated objective vectors for the Multi-Objective Integer Programming (MOIP) problem. We significantly improve the earlier recursive algorithm of Özlen and Azizo?lu by using the set of already solved subproblems and their solutions to avoid solving a large number of IPs. A numerical example is presented to explain the workings of the algorithm, and we conduct a series of computational experiments to show the savings that can be obtained. As our experiments show, the improvement becomes more significant as the problems grow larger in terms of the number of objectives. 相似文献
427.
de la Puente Luz M White CT Rivera-Sagredo A Reilly J Burton K Harvey G 《Journal of chromatography. A》2003,983(1-2):101-114
Novel normal-phase gradient systems have been employed for fast high-throughput chiral analyses of Discovery compounds in our research laboratories in Eli Lilly and Company. In this report, we describe an automated screening approach based on gradient elution, in order to achieve accurate enantiomeric excess determinations, and chiral separations when needed, in the shortest possible timeframe. Baseline resolution of enantiomers has been obtained for over 85% of the samples so tested. For the remaining cases, complete enantioseparation by isocratic optimisation is generally achieved in a single shot. This technique has been proven to be robust and is now standard operating procedure at our analytical research laboratories. 相似文献
428.
It is reasoned in this paper that the traditional assumption of grain volume conservation during diffusion creep is correct only for special grain configurations. An analysis is presented that illustrates this, using a hypothetical arrangement of grains specifically chosen to be stable against both grain boundary sliding and grain rotation, so that the extent of grain volume non-conservation can be illustrated in the absence of these factors. The influence on the development of the ‘denuded’ zones that characterize diffusion creep in particle-containing materials is addressed. The analysis contributes to an explanation for the discrepancies between the creep strain estimated from zone sizes and the overall specimen strain, a discrepancy that has been used in the past as counter evidence for the diffusion creep mechanism. Suggestions are made for the improved modelling of diffusion creep in polycrystalline materials and duplex structures. 相似文献
429.
Spin polarized electronic structure calculations of total energies for ordered supercells in the system Fe2O3–FeTiO3 suggest that some layered ordered phases are more stable than an isocompositional mechanical mixture of hematite, Fe2O3, and ilmenite, FeTiO3. This result contradicts established ideas about hematite–ilmenite phase relations because it suggests that there is at least one stable ordered phase with a bulk composition intermediate between hematite and ilmenite. It is not clear if this result is an artifact of the approximations made in generalized gradient spin density functional calculations, or if an intermediate phase, or phases, is in fact stable. The electronic structure of a 30-atom layered supercell was studied by a variety of techniques. The supercell structure is FTFFFT, where F is an Fe layer and T is a Ti layer perpendicular to the hexagonal c axis. The idea was to investigate possible charge ordering on Fe sites, that is a postulate of the ‘lamellar magnetism hypothesis’, but significant Fe2+–Fe3+ordering is not predicted. 相似文献
430.
Timothy J. Johnson Robert L. Sams Sarah D. Burton Thomas A. Blake 《Analytical and bioanalytical chemistry》2009,395(2):377-386
We report quantitative infrared spectra of vapor-phase hydrogen peroxide (H2O2) with all spectra pressure-broadened to atmospheric pressure. The data were generated by injecting a concentrated solution
(83%) of H2O2 into a gently heated disseminator and diluting it with pure N2 carrier gas. The water vapor lines were quantitatively subtracted from the resulting spectra to yield the spectrum of pure
H2O2. The results for the ν6 band strength (including hot bands) compare favorably with the results of Klee et al. (J Mol. Spectrosc. 195:154, 1999) as well as with the HITRAN values. The present results are 433 and 467 cm-2 atm−1 (±8 and ±3% as measured at 298 and 323 K, respectively, and reduced to 296 K) for the band strength, matching well the value
reported by Klee et al. (S = 467 cm−2 atm−1 at 296 K) for the integrated band. The ν1 + ν5 near-infrared band between 6,900 and 7,200 cm−1 has an integrated intensity S = 26.3 cm−2 atm−1, larger than previously reported values. Other infrared and near-infrared bands and their potential for atmospheric monitoring
are discussed. 相似文献