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排序方式: 共有920条查询结果,搜索用时 31 毫秒
1.
2.
Biosorption of Chromium(III) by Biomass of Seaweed Sargassum sp. in a Fixed-Bed Column 总被引:2,自引:0,他引:2
Eneida Sala Cossich Edson Antonio da Silva Célia Regina Granhen Tavares Lúcio Cardozo Filho Teresa Massako Kakuta Ravagnani 《Adsorption》2004,10(2):129-138
This work aimed at modeling chromium biosorption using the biomass of seaweed Sargassum sp. in a fixed-bed column. The mathematical model used was obtained from the mass balance of the component in the liquid phase and in the biosorbent material. The effects of both axial dispersion in the column and the resistance to mass transfer in the solid were considered for the solution of the partial differential equations of the model, using the Galerkin method on finite elements. To represent the equilibrium data of the batch system the Langmuir isotherm were used. The chromium ion adsorption capacity of the seaweed Sargassum sp., at a temperature of 30°C and pH 3.5, was 2.61 mmol/g. The model performance was evaluated from experimental data obtained at 30°C for flow rates of 2, 6 and 8 mL/min. The parameters of the model, mass transfer and axial dispersion coefficients, were adjusted from these experimental data. The model proved adequate to describe chromium biosorption dynamics in fixed-bed columns. 相似文献
3.
Let Um be an m×m Haar unitary matrix and U[m,n] be its n×n truncation. In this paper the large deviation is proven for the empirical eigenvalue density of U[m,n] as m/n→λ and n→∞. The rate function and the limit distribution are given explicitly. U[m,n] is the random matrix model of quq, where u is a Haar unitary in a finite von Neumann algebra, q is a certain projection and they are free. The limit distribution coincides with the Brown measure of the operator quq. 相似文献
4.
Alexander Semenov Aurélia Charlot Rachel Auzély-Velty Marguerite Rinaudo 《Rheologica Acta》2007,46(5):541-568
Dynamics of associating polymer solutions above the reversible gelation point are studied. Each macromolecule consists of
a soluble backbone (B) and a small fraction of specific strongly interacting groups (A or C stickers) attached to B. A mixture
of B–A and B–C associating polymers with 1:1 stoichiometric ratio is considered. As a result of AC association, the polymers
reversibly gelate above the overlap concentration. It is shown that (1) the network strands are linear complexes (double chains)
of B–A and B–C; (2) “diffusion” of the network junction points is characterized by an apparent activation energy, which can
be significantly higher than the energy of one AC bond; (3) most importantly, the randomness of sticker distribution along
the chain can significantly slow down the network relaxation leading to a markedly non-Maxwellian viscoelastic behavior. The
theory elucidates the most essential features of rheological behavior of polysaccharide associating systems (with A = adamantyl
moiety, C = β-cyclodextrin, B = either chitosan or hyaluronan) including similar behavior of G
′ and G
″ in a wide frequency range, strong temperature dependence of the characteristic frequency ω
x
, and an extremely strong effect of added free stickers (fC) on the dynamics.
This paper was presented at Annual European Rheology Conference (AERC) held in Hersonisos, Crete, Greece, April 27–29, 2006. 相似文献
5.
Steve Tisserand Célia Billaud J.R. Falck Charles Mioskowski 《Tetrahedron letters》2006,47(29):5177-5180
CrCl2-mediated condensation of γ-chloro-gem-trichloroalkanes with aldehyde generates homoallylic alcohols through a hydride rearrangement followed by a Nozaki-Hiyama allylation. 相似文献
6.
Luiza Amália Moraes Luis Romero Grados 《Journal of Mathematical Analysis and Applications》2003,281(2):575-586
Let Au(BG) be the Banach algebra of all complex valued functions defined on the closed unit ball BG of a complex Banach space G which are uniformly continuous on BG and holomorphic in the interior of BG, endowed with the sup norm. A characterization of the boundaries for Au(BG) is given in case G belongs to a class of Banach spaces that includes the pre-dual of a Lorentz sequence space studied by Gowers in Israel J. Math. 69 (1990) 129-151. The non-existence of the Shilov boundary for Au(BG) is also proved. 相似文献
7.
Perdigón-Melón J. A. Auroux A. Bonnetot B. 《Journal of Thermal Analysis and Calorimetry》2003,72(2):443-451
As supported palladium oxide catalysts present the best performances in methane combustion in lean conditions, microcalorimetric
studies of the interaction between methane and palladium oxide or metallic palladium supported on Al2O3, ZrO2 and BN have been performed at 673 K. At this temperature methane reduced the palladium oxide, and the heat of reduction of
palladium oxide was shown to depend on the dispersion and on the support. The lowest heats of reduction corresponded to the
highest rates of methane combustion. Moreover methane reforming occurred on metallic palladium, producing hydrogen, and again
methane decomposition was shown to depend on the support.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
9.
Nadir Arada Paulo Correia Adélia Sequeira 《Numerical Methods for Partial Differential Equations》2007,23(6):1468-1500
This article is concerned with the equations governing the steady motion of a viscoelastic incompressible second‐order fluid in a bounded domain. A new proof of existence and uniqueness of strong solutions is given. In addition, using appropriate finite element methods to approximate a coupled equivalent problem, sharp error estimates are obtained using a fixed point argument. The method is applied to the two‐dimensional lid‐driven cavity problem, at low Reynolds number and in a certain range of values of the viscoelastic parameters, to analyze the combined effects of inertia and viscoelasticity on the flow. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007 相似文献
10.
Marcos F. de Campos Marília Emura Fernando J.G. Landgraf 《Journal of magnetism and magnetic materials》2006
Electrical steels, when submitted to operation, present continuous decrease of their magnetic properties, depending on the carbon content. This effect is attributed to the increase of the size of carbides, a process also known as coarsening or Ostwald Ripening. Loss separation can offer a better understanding of this phenomenon. Experimental results show that all effect of aging is inside the hysteresis loss component, with the excess losses unaffected. The carbon content in electrical steels should be less than 25 ppm to avoid magnetic aging. 相似文献