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91.
92.
M. Morcrette A. Gutiérrez-Llorente A. Laurent J. Perrière P. Barboux J.P. Boilot O. Raymond T. Brousse 《Applied Physics A: Materials Science & Processing》1998,67(4):425-428
x La2/3+yTiO3-δ perovskite (with δ≤0.5) were deposited by the laser ablation technique from Li0.33La0.56TiO3 targets. Their growth onto MgO substrateswas studied as a function of the oxygen pressure. For films grown in vacuum (10-6 mbar), a La0.63TiO2.5 composition was obtained, meaning that Ti3+ alone is present in the films, while Li ions are not incorporated under these conditions. This material shows good electric
conductivity (ρ=500 mΩ cm). By contrast, insulating films with a Li0.1La0.70TiO3 composition corresponding to the Ti4+ species were obtained at high oxygen pressures (>0.05 mbar). For all conditions, textured films were grown with different
orientations depending on the temperature and the oxygen pressure.
Received: 10 September 1997/Accepted: 24 November 1997 相似文献
93.
S. L. Molodtsov A. Gutiérrez E. Navas M. Domke G. Kaindl M. Merkel N. Nücker J. Fink V. P. Antropov O. K. Andersen O. Jepsen 《Zeitschrift für Physik B Condensed Matter》1993,92(3):347-351
The electronic structure of K-doped C60 was investigated by photoemission (PE) and X-ray absorption near-edge structure (XANES) studies at the C-1s and K-2p thresholds. In addition, information on the local K-derived partial density of states in superconducting K3C60 was obtained by resonant PE at the K-2p
1/2 threshold. The experimental observations support a complete charge transfer from K to C60 and we clearly observe a finite density of states atE
F
. From resonant PE, occupied states with K-p, d character could be identified in the binding-energy region from 1.5 to 8 eV below, but not directly at the Fermi level. This partial-density-of-states structure agrees well with the results of our band-structure calculations based on the local-density approximation. 相似文献
94.
95.
Gutiérrez-Vega JC 《Optics letters》2007,32(11):1521-1523
We apply the tools of the fractional calculus to introduce new fractional-order beam solutions to the paraxial wave equation that can be regarded as intermediate solutions between the known integral-order solutions. We restrict our attention to the fractionalization of the elegant and standard Hermite-Gaussian beams. 相似文献
96.
Estimation of Temperatures in Geothermal Wells During Circulation and Shut-in in the Presence of Lost Circulation 总被引:1,自引:0,他引:1
García A. Santoyo E. Espinosa G. Hernández I. Gutiérrez H. 《Transport in Porous Media》1998,33(1-2):103-127
The estimation of temperatures in and around a geothermal well during circulation, and during shut-in conditions in the presence of lost circulation is presented in this work. Estimated temperatures are compared with temperature logs measured during drilling stoppages. Temperatures were estimatted using a computer code specifically developed to account for the transient convective heat transfer due to lost circulation in the rock surrounding a well. This feature of the present code is important since wellbore simulators normally consider the heat transfer process in the rock as a merely conductive problem. The code is capable of accounting for these losses at any point in the well and application was made to the study of two Mexican geothermal wells(well LV-3 from the Las Tres Vírgenes field and well EAZ-2 from the Los Azufres field). The results show that the effect of lost circulation on the shut-in temperature profiles can be modelled satisfactorily. Research is under way to improve the present methodology. 相似文献
97.
Light‐Driven Reversible Alignment Switching of Liquid Crystals Enabled by Azo Thiol Grafted Gold Nanoparticles
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Dr. Chenming Xue Jie Xiang Hossein Nemati Dr. Hari Krishna Bisoyi Karla Gutierrez‐Cuevas Dr. Ling Wang Dr. Min Gao Shuang Zhou Prof. Deng‐ke Yang Prof. Oleg D. Lavrentovich Dr. Augustine Urbas Prof. Quan Li 《Chemphyschem》2015,16(9):1852-1856
Stimuli‐directed alignment control of liquid crystals (LCs) with desired molecular orientation is currently in the limelight for the development of smart functional materials and devices. Here, photoresponsive azo thiol (AzoSH) was grafted onto gold nanoparticles (GNPs). The resulting hybrid GNPs were able to homogeneously mix with a commercially available nematic LC host, as evidenced by Cryo‐TEM. Interestingly, the LC nanocomposites were found to undergo reversible alignment transition upon light irradiation as a consequence of the trans–cis photoisomerization of the azo groups on the GNP surface. LC molecules in either planar or bare glass cells were able to change their alignment to vertical upon UV irradiation, while the vertically aligned LC molecules returned to the planar or random orientation under visible irradiation. Neither the azo thiol molecules nor the unfunctionalized GNPs alone promoted the alignment of the LC molecules in the system upon light irradiation. The photoinduced vertical alignment without applied electric or magnetic field was very stable over time and with respect to temperature. Furthermore, an optically switchable device based on the photostimulated reversible alignment control of LCs was demonstrated. 相似文献
98.
Rocio Bueno‐Perez Dr. Juan J. Gutiérrez‐Sevillano Dr. David Dubbeldam Prof. Patrick J. Merkling Prof. Sofia Calero 《Chemphyschem》2015,16(13):2735-2738
The separation of pentanol isomer mixtures is shown to be very efficient using the nanoporous adsorbent zeolitic imidazolate framework ZIF‐77. Through molecular simulations, we demonstrate that this material achieves a complete separation of linear from monobranched—and these from dibranched—isomers. Remarkably, the adsorption and diffusion behaviors follow the same decreasing trend, produced by the channel size of ZIF‐77 and the guest shape. This separation based on molecular branching applies to alkanes and alcohols and promises to encompass numerous other functional groups. 相似文献
99.
In this paper we deal with linear production situations in which there is a limited common-pool resource, managed by an external agent. The profit that a producer can attain depends on the amount of common-pool resource obtained through a certain procedure. We contemplate a competitive process among the producers and study the corresponding non-cooperative games, describing their (strict) Nash equilibria in pure strategies. It is shown that strict Nash equilibria form a subset of strong Nash equilibria, which in turn form a proper subset of Nash equilibria. 相似文献
100.
Eduardo Ordó?ez-Regil Genoveva García-Rosales Omar Eduardo Gutiérrez-Mu?iz 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(1):197-201
Seawater contains trace elements in solution, such as lanthanides and uranium, which can act as natural tracers when they
flocculate to form the sediments of the seabed. Uranium is a special case because it is a radioactive element with isotopic
ratio close to 1.14 (234U/238U) in sea water. Uranium is also present in all fractions of sediments, although the isotopic ratio in each fraction takes
a specific value depending on its origin and surrounding environment. This work has been conducted in order to analyze lanthanides
and uranium in a core of sea sediments. It is focused on separating the fractions forming the layers along the depth profile
of the core sample so as to determine the 234U/238U activity ratios in fractions of organic matter, aquatic life skeletons and dissolved minerals. The Neutron Activation Analysis
showed the presence of U, Lu, Hf, Eu, Ce and Yb ranging up to 50 ppm while alpha spectrometry gave a series of 234U/238U activity ratios which are discussed on the basis of statistical analysis. 相似文献