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81.
Mallick K Witcomb MJ Dinsmore A Scurrell MS 《Langmuir : the ACS journal of surfaces and colloids》2005,21(17):7964-7967
This work demonstrated a facile route for the synthesis of poly(3,5-dimethyl aniline) nanofibers by polymerization of 3,5-dimethyl aniline using Pd-acetate as the oxidant. The reduction of Pd ion is accompanied by oxidative polymerization of 3,5-dimethyl aniline, leading to a metal-polymer composite material. Palladium nanoparticles (approximately 2 nm) are uniformly distributed throughout the polymer that makes the composite material a unique morphology. The resultant composite material was characterized by means of different techniques. IR and Raman spectra provide the information on the chemical structure of the polymer. TEM images show the morphology of the polymer and size of the metal particles. 相似文献
82.
The subtle flexibility of the framework material Co(bpy)1.5(NO3)2.(guest) (bpy = 4,4'-bipyridine) (1.(guest)) is demonstrated quantitatively through in situ single-crystal X-ray diffraction measurements of guest desorption and sorption processes. Variable temperature unit cell determinations were employed to monitor the uptake and release of guest species, and full structural determinations have been carried out for the as-grown ethanol-loaded framework (1.(EtOH)), for the empty host framework, and for each of the five introduced guests (methanol: 1.(MeOH), acetone: 1.(ACN), acetonitrile: 1.(MeCN), tetrahydrofuran:1.(THF), dichloromethane: 1.(DCM)). The framework consists of interdigitated two-dimensional bilayers of cobalt(II) centers bridged by bpy ligands, with one-dimensional pores that account for approximately 20% of the total volume. The sorption of guest species of varying size and shape has revealed the framework's ability to adapt to different guests through a range of different framework flexibilities. 相似文献
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85.
Alan K. Halder 《The Journal of the Operational Research Society》1970,21(2):267-278
The development of urban transportation planning models has accelerated in the past decade, until they are now widely accepted aids to the urban decision process. However, the models have had limited impact upon individual decisions, because of their complexity and size. In the absence of radical new approaches to planning, a methodology is suggested to complement the existing procedures.This methodology, which is referred to as "perturbation", is illustrated by reference to the choice of a future network. Some results are presented for the budgeting of capital for a set of investments. 相似文献
86.
Study of transport in the boundary layer of tokamak plasma in presence of magnetic divertors is extended to the second order
in ion collision frequency. Numerical results for ion and energy losses to the collector plates are presented for toroidal
and poloidal divertors. For the toroidal case, the Wiener-Hopf solution for the second order distribution function is obtained.
An error occurring in an earlier first order calculation is pointed out and corrected first order fluxes are also given. For
the poloidal divertor, asymmetry observed in ion and energy transport is found to persist in the second order result. 相似文献
87.
Atul D. Sontakke Kaushik Biswas Ashis K. Mandal Kalyandurg Annapurna 《Journal of fluorescence》2010,20(1):425-434
This paper reports on the preparation and systematic analysis of energy transfer mechanisms in Nd3+–Yb3+–Er3+ co-doped new series of barium-alumino-metaphosphate glasses. The time resolved fluorescence of Nd3+ in triply doped Ba–Al-metaphosphate glasses have revealed that, Yb3+ ions could function as quite efficient bridge for an energy transfer between Nd3+ and Er3+ ions. As a result, a fourfold emission enhancement at 1.54 μm of Er3+ ions has been achieved through an excitation of 4F5/2 level of Nd3+ at 806 nm for the glass having 3 mol% Yb3+ with an energy transfer efficiency reaching up to 94%. Decay of donor (Nd3+) ion fluorescence has been analyzed based on theoretical models such as direct energy transfer model (Inokuti–Hirayama) and
migration assisted energy transfer models (Burshtein’s hopping and Yokota–Tanimoto’s diffusion). The corresponding energy
transfer parameters have been evaluated and discussed. Primarily, electrostatic dipole–dipole (s ~ 6) interactions are found
to be responsible for the occurrence of energy transfer process in theses glasses. 相似文献
88.
The paper deals with the analysis of a non-stationary parabolic partial differential equation with a time delay. The highest order derivative term is affected by the small parameter. This is precisely the case when the magnitude of the convective term becomes much larger compare to that of diffusion term. The solution of problem exhibits steep gradients in the narrow intervals of space and short interval of times. In these cases a dissipative loss turned out to be more complex. Even for the one spatial dimension and one temporal variable, not all difference scheme can capture these steep variation. Although the analysis is restricted to the model in one space dimension, the technique and comparison principles developed should prove useful in assessing the merits of numerical solution of other nonlinear model equations too. 相似文献
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