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71.
Mulder A Jukovic A Lucas LN van Esch J Feringa BL Huskens J Reinhoudt DN 《Chemical communications (Cambridge, England)》2002,(22):2734-2735
The binding of TSPP by a dithienylethene-tethered beta-cyclodextrin dimer can be altered reversibly by irradiation with light. 相似文献
72.
The change of the FWHM of the mass distribution of the fission products as a function of angular momentum is interpreted as a signature for a mechanism which is intermediate between compound nucleus formation and deep inelastic reactions. An intermediate composite system is assumed to be formed during the reaction, which undergoes fission. This kind of mechanism can therefore be called fast fission phenomena. It is related to the existence of a long lifetime component in déep inelastic reactions. Within the framework of a simple statistical model a qualitative as well as a quantitative estimate is done for a particular system. The conditions under which such a mechanism can be observed are discussed. 相似文献
73.
74.
Grimault S Lucas T Quellec S Mariette F 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,170(1):79-87
MRI thermometry methods are usually based on the temperature dependence of the proton resonance frequency. Unfortunately, these methods are very sensitive to the phase drift induced by the instability of the scanner which prevents any temperature mapping over long periods of time. A general method based on 3D spatial modelling of the phase drift as a function of time is presented. The MRI temperature measurements were validated on gel samples with uniform and constant temperature and with a linear temperature gradient. In the case of uniform temperature conditions, correction of the phase drift proved to be essential when long periods of acquisition were required, as bias could reach values of up to 200 degrees C in its absence. The temperature uncertainty measured by MRI was 1.2 degrees C in average over 290 min. This accuracy is coherent with the requirements for food applications especially when thermocouples are useless. 相似文献
75.
Stefania Gabelli Evan Houston Thomas G. Lucas 《Journal of Pure and Applied Algebra》2004,194(3):281-298
Generalizing work of Gilmer and Heinzer, we define a t#-domain to be a domain R in which for any two distinct subsets and of the set of maximal t-ideals of R. We provide characterizations of these domains, and we show that polynomial rings over t#-domains are again t#-domains. Finally, we study overrings of t#-domains. 相似文献
76.
Sheridan B Martin DS Power JR Barrett SD Smith CI Lucas CA Nichols RJ Weightman P 《Physical review letters》2000,85(21):4618-4621
Introducing reflection anisotropy spectroscopy (RAS) as a new probe for solid-liquid interfaces, we present results for the Au(110)/electrolyte interface which serves as a model system. We demonstrate that RAS is sensitive to surface phase transitions, step morphology, and electronic surface states. Using an empirical approach, the RA spectra are reproduced and features are identified which reflect the known character of the bias voltage driven (2x1) to (1x1) phase transition. RAS is established as an experimental technique to probe the electronic structure of solid-liquid interfaces in real time to study a wide range of interface properties. 相似文献
77.
Ji-Won Moon Lucas W. Yeary Adam J. Rondinone Claudia J. Rawn Melanie J. Kirkham Yul Roh Lonnie J. Love Tommy J. Phelps 《Journal of magnetism and magnetic materials》2007
The magnetic susceptibility (κRT) and saturation magnetization (MS) of microbially synthesized magnetites were systematically examined. Transition metal (Cr, Mn, Co, Ni and Zn)- and lanthanide (Nd, Gd, Tb, Ho and Er)-substituted magnetites were microbially synthesized by the incubation of transition metal (TM)- and lanthanide (L)-mixed magnetite precursors with either thermophilic (TOR-39) or psychrotolerant (PV-4) metal-reducing bacteria (MRB). Zinc incorporated congruently into both the precursor and substituted magnetite, while Ni and Er predominantly did not. Microbially synthesized Mn- and Zn-substituted magnetites had higher κRT than pure biomagnetite depending on bacterial species and they exhibited a maximum κRT at 0.2 cationic mole fraction (CMF). Other TMs’ substitution linearly decreased the κRT with increasing substitution amount. Based on the MS values of TM- and L-substituted magnetite at 0.1 and 0.02 CMF, respectively, Zn (90.7 emu/g for TOR-39 and 93.2 emu/g for PV-4)- and Mn (88.3 emu/g by PV-4)-substituted magnetite exhibited higher MS than standard chemical magnetite (84.7 emu/g) or pure biomagnetite without metal substitution (76.6 emu/g for TOR-39 and 80.3 emu/g for PV-4). Lanthanides tended to decrease MS, with Gd- and Ho-substituted magnetites having the highest magnetization. The higher magnetization of microbially synthesized TM-substituted magnetites by the psychrotroph, PV-4 may be explained by the magnetite formation taking place at low temperatures slowing mechanics, which may alter the magnetic properties compared to the thermophile, through suppression of the random distribution of substituted cations. 相似文献
78.
The manganite La0.67Sr0.33MnO3 (LSMO) layers are deposited on single crystal MgO(0 0 1) substrates using a magnetron dc sputtering. The crystalline perfection of the layers, both the as-prepared and the annealed, are characterized by X-ray diffraction technique, rocking curve measurements, Rutherford backscattering spectroscopy (RBS) and transmission electron microscopy (TEM). TEM analyses give evidence of the epitaxial growth of the annealed LSMO with a nanocrystalline surface layer. The temperature dependence of resistance in the 77-340 K range is measured by a standard four-probe technique. While the as-prepared film does not show any transition from paramagnetic to ferromagnetic state, the film annealed in oxygen shows steep R(T) dependence with a peak at 330 K and maximal slope (dR/dT) at 290 K where the maximal sensitivity is 3% K−1. 相似文献
79.
80.
J.E. Bailey G.A. Chandler G.A. Rochau Y. Maron S.A. Slutz G.S. Dunham I. Golovkin P.W. Lake R.W. Lemke J.M. Lucas J.J. MacFarlane T.A. Mehlhorn T.C. Moore D.G. Schroen E. Stambulchik K. Youngblood 《High Energy Density Physics》2005,1(1):21-30
A dynamic hohlraum is created when an annular z-pinch plasma implodes onto a cylindrical 0.014 g/cc 6-mm-diameter CH2 foam. The impact launches a radiating shock that propagates toward the axis at 350 μm/ns. The radiation trapped by the tungsten z-pinch plasma forms a 200 eV hohlraum that provides X-rays for indirect drive inertial confinement fusion capsule implosion experiments. We are developing the ability to diagnose the hohlraum interior using emission and absorption spectroscopy of Si atoms added as a tracer to the central portion of the foam. Time- and space-resolved Si spectra are recorded with an elliptical crystal spectrometer viewing the cylindrical hohlraum end-on. A rectangular aperture at the end of the hohlraum restricts the field of view so that the 1D spectrometer resolution corresponds approximately to the hohlraum radial direction. This enables distinguishing between spectra from the unshocked radiation-heated foam and from the shocked foam. Typical spectral lines observed include the Si Lyα with its He-like satellites and the He-like resonance sequence including Heα, Heβ, and Heγ, along with some of their associated Li-like satellites. Work is in progress to infer the hohlraum conditions using collisional–radiative modeling that accounts for the radiation environment and includes both opacity effects and detailed Stark broadening calculations. These 6-mm-scale radiation-heated plasmas might eventually also prove suitable for testing Stark broadening line profile calculations or for opacity measurements. 相似文献