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排序方式: 共有83条查询结果,搜索用时 15 毫秒
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Fall AB Lindström SB Sundman O Ödberg L Wågberg L 《Langmuir : the ACS journal of surfaces and colloids》2011,27(18):11332-11338
Cellulose nanofibrils constitute an attractive raw material for carbon-neutral, biodegradable, nanostructured materials. Aqueous suspensions of these nanofibrils are stabilized by electrostatic repulsion arising from deprotonated carboxyl groups at the fibril surface. In the present work, a new model is developed for predicting colloidal stability by considering deprotonation and electrostatic screening. This model predicts the fibril-fibril interaction potential at a given pH in a given ionic strength environment. Experiments support the model predictions that aggregation is induced by decreasing the pH, thus reducing the surface charge, or by increasing the salt concentration. It is shown that the primary mechanism for aggregation upon the addition of salt is the surface charge reduction through specific interactions of counterions with the deprotonated carboxyl groups, and the screening effect of the salt is of secondary importance. 相似文献
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Analysis of transmission Mössbauer spectra for high nitrogen Fe?N austenites is done in terms of five iron environments dealing with first and second nearest neighbour shells. The similar analysis for Fe?C austenites which displays only three iron environments led to the conclusion that carbon atoms are ordered whereas nitrogen atoms are more randomly distributed. 相似文献
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Alioune Niang Foued Amrani Mohamed Salhi Philippe Grelu François Sanchez 《Applied physics. B, Lasers and optics》2014,116(3):771-775
We report experimental observation of rains of solitons in figure-of-eight fiber laser passively mode-locked through nonlinear optical loop mirror. Soliton pulses are created from an extended noisy background and drift until they reach a condensed phase comprising several tens of aggregated solitons. The observation of this dynamics tends to strengthen the idea of the universality of the collective behavior of solitons. 相似文献
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In this paper, we study the equation \(\mathcal {L} u=0\) in \(\mathbb {R}^{N}\), where \(\mathcal {L}\) belongs to a general class of nonlocal linear operators which may be anisotropic and nonsymmetric. We classify distributional solutions of this equation, thereby extending and generalizing recent Liouville type theorems in the case where \(\mathcal {L}= (-{\Delta })^{s}\), s ∈ (0, 1) is the classical fractional Laplacian. 相似文献
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The palladium-tetraphosphine catalyzed arylation of an alkylidenecyclopropane gives a simple and direct access to 1-aryl-2-methyl-1-(2,2,3,3-tetramethylcyclopropylidene)propenes. This reaction tolerates several functional groups on the aryl bromides. Even heteroaryl bromides have been used successfully. This reaction probably proceeds via a classical oxidative addition of the aryl bromide to palladium, insertion of the CCMe2 bond in the Ar-Pd bond followed by β-elimination to give the dienes. 相似文献
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The electronic absorption and fluorescence spectra of electrosynthesized poly(3-methoxythiophene)— bithiophene (PMOT-BT) composite oligomers were studied in organic solution (DMSO) and/or in the solid state on ITO plates. Different spectral properties (absorption and fluorescence maximum wavelengths, fluorescence quantum yields, etc.) were found to depend on the bithiophene initial concentration used during electrosynthesis and, subsequently, on the film composition and oligomer chain length. 相似文献
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Birane Fall AbdelAziz Jalil Michael Gau Sumanth Chereddy Michael J. Zdilla Stephanie L. Wunder Parameswara Rao Chinnam 《Ionics》2018,24(2):343-349
A soft solid crystal composed of isoquinoline (IQ) and LiCl was prepared based on the concept of Pearson’s hard-soft acid-base (HSAB) theory. Single-crystal X-ray diffraction best described the isoquinoline3?(LiCl)2 as consisting of molecular Li4Cl4(isoquinoline)6 units, where the LiCl cluster is an array of edge-fused Li2Cl2 rhombs. Electrochemical impedance measurements on pressed pellets showed that conductivity occurs mainly through the bulk via a hopping mechanism, with a calculated activation energy of Ea = 67 kJ/mol. The high value of the activation energy was due to Li4Cl4 clusters that were well separated by intervening IQ ligands in the crystal structure, requiring large hops for ions to migrate through the lattice. 相似文献
10.
Serigne Massamba Seck Stéphane Charvet Modou Fall Emmanuel Baudrin Michaël Lejeune Mohammed Benlahsen 《Electroanalysis》2012,24(9):1839-1846
Nitrogenous amorphous carbon (a‐CNx) thin films were deposited by radio‐frequency cathodic magnetron sputtering (13.56 MHz) on polished and etched titanium disks. While these films are cheaper to prepare than commonly reported carbon‐based electrodes, the usable electrochemical window in aqueous solution is within the same range and spans from ?1.5 to +1.8 V vs. SCE. The electrochemical reactivity was tested using the ferri‐ferrocyanide redox couple as a function of the thin films preparation parameters. The obtained electrochemical properties allow the use of these a‐CNx thin films for stripping electroanalysis of cations in water, minimizing potential solvent reactivity. Cadmium and copper were used to test these detection abilities. Better analytical properties (notably sensitivity and linearity) were obtained as compared to a commercial boron doped diamond electrode. Preliminary competition/interaction experiments for these two cations were performed. 相似文献