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101.
Maria Bocheńska Robert Banach Anna Zielińska Victor CH. Kravtsov 《Journal of inclusion phenomena and macrocyclic chemistry》2001,39(3-4):219-228
Some di- and tetraamide tert-butylcalix[4]areneswere synthesized and described. Their ionophoric properties were studied in liquid membrane ion-selective electrodes. The correlation between thechemical structure (conformation in solution determined by 1H NMR) and potentiometric ion-selectivity and complex formation constant havebeen studied. The PVC membrane electrodes based on tetraamides 8–11 show high sodium selectivity, are stable and long lasting. Disubstituted amides 1–7 are selective for larger and more lipophilic ions, as for exampleguanidinium ion. The crystal structure of the diamide 4 was determined by single crystal X-ray analysis. Crystals of 4 are triclinic, spacegroup P-1, with: a = 16,669(8), b = 17.795(10), c = 20.984(8) Å, =91.08(4)°, = 91.60(3)°, = 90.73(4)° and Z = 4. Ionophore 4 posseses a distorted cone conformation and is substituted at the proximal phenol rings. 相似文献
102.
Andreas N. Alexandrou Timothy M. McGilvreay Gilmer Burgos 《ournal of non Newtonian Fluid Mechanics》2001,100(1-3)
In this paper we study steady flow of Herschel–Bulkley fluids in a canonical three-dimensional expansion. The fluid behavior was modeled using a regularized continuous constitutive relation, and the flow was obtained numerically using a mixed-Galerkin finite element formulation with a Newton–Raphson iteration procedure coupled to an iterative solver. Results for the topology of the yielded and unyielded regions, and recirculation zones as a function of the Reynolds and Bingham numbers and the power-law exponent, are presented and discussed for a 2:1 and a 4:1 expansion ratio. The results reveal the strong interplay between the Bingham and Reynolds numbers and their influence on the formation and break up of stagnant zones in the corner of the expansion and on the size and location of core regions. 相似文献
103.
Bragg diffraction spot intensities of a colloidal single crystal were found to exhibit a DebyeWaller factor-like decay. The Lindemann parameter and the mean-square displacement after infinite times of the colloidal particles could be obtained. 相似文献
104.
105.
106.
D. Mac-Leod Carey C. Morales-Verdejo A. Muñoz-Castro F. Burgos D. Abril C. Adams E. Molins O. Cador I. Chávez J.M. Manríquez R. Arratia-Pérez J.Y. Saillard 《Polyhedron》2010
The reaction of 2,6-diethyl-4,8-dimethyl-s-indacenyl-dilithium (Li2Ic′) with [Cp*RuCl]4 gives the organometallic binuclear bis-pentamethylcyclopentadienyl-ruthenium-s-indacene complex, [{Cp*Ru}2Ic′] (1, Ic′ = 2,4-diethyl-4,8-dimethyl-s-indacene), in high yields. The subsequent oxidation of 1 with a ferricinium salt ([Fc]+[BF4]−) gives the mixed valence compound [{Cp*Ru}2Ic′]+[BF4]− (1+). Compound 1 was structurally characterized by X-ray crystallography, finding that both {Cp*Ru} fragments are coordinated to opposite sites of the Ic′ ligand. The structural and electronic features of 1 and 1+ have been rationalized by Density Functional Theory (DFT) calculations, which suggest that both metallic centers get closer to the Ic′ and subtle electronic reorganizations occurs when chemical oxidation takes place. Cyclic voltammetry and ESR experiments suggest a high electronic interaction between the metallic centers mediated by the Ic′ bridging ligand. Time dependent DFT (TD-DFT) calculations were carried out to understand and assign the intervalence band present in the mixed-valent specie (1+). The main achievement of this article is to feature the relationship of the experimental data with the computational results obtained with the Amsterdam Density Functional package (ADF). Both experimental and theoretical facts demonstrate that the mixed valence system (1+) is a delocalized one, and it can be classified as a Class III system according to the Robin & Day classification. 相似文献
107.
M. Burgos A.C. Márquez-García A. Morales-Campoy 《Linear algebra and its applications》2012,437(5):1183-1193
Let A and B be Banach algebras. Assume that A is unital. We prove that an additive map strongly preserves Drazin (or equivalently group) invertibility, if and only if T is a Jordan triple homomorphism. When A and B are C1-algebras, we characterize the linear maps strongly preserving generalized invertibility (in the Jordan systems’ sense), and as consequence we determine the structure of selfadjoint linear maps strongly preserving Moore–Penrose invertibility. 相似文献
108.
CH. Sedlmair K. Seshan A. Jentys J. A. Lercher 《Research on Chemical Intermediates》2003,29(3):257-269
The influence of SO2 exposure under lean (oxidizing) and rich (reducing) reaction conditions on the storage and oxidation/reduction function of a commercial NOx storage-reduction catalyst was investigated by temperature-programmed uptake experiments and high temperature XRD. Both the storage capacity and the oxidation/reduction function of the catalyst were deactivated by SO2 exposure under lean and rich reaction conditions. The deactivation of the storage component, i.e. the loss of the NOx storage capacity, resulted mainly from the formation of Ba-sulfates accumulating in the bulk phase, which have a high thermal stability (>800°C) and, therefore, cannot be removed under the typical operation conditions of a NSR catalyst. For the oxidation function only a temporarily deactivation during lean reaction conditions was observed. Besides the formation of SO2-
4 species on the storage component at the beginning of the SO2 exposure under rich conditions, an adsorption of SO2 on the noble metal component was observed resulting in the formation of sulfur deposits. The oxidation of these sulfur species with a subsequent spillover of SO2-
4 species to the storage component during lean conditions could accelerate the deactivation of the storage capacity. 相似文献
109.
M. E. Burgos 《Foundations of Physics》1998,28(8):1323-1346
We assume, in the first place, that two kinds of processes occur in nature: the strictly continuous and causal ones, which are governed by the Schrödinger equation and those implying discontinuities, which are ruled by probability laws. In the second place, we adopt a postulate ensuring the statistical sense of conservation laws. These hypotheses allow us to state a rule telling, in principle, in which situations and to which vectors the system's state can collapse, and which are the corresponding probabilities. The way our proposed approach works is illustrated with some examples and with the analysis of the measurement problem. We obtain the exponential decay law. A comparison with other attempts to solve the measurement problem is performed. 相似文献
110.
O. Petracic S. Sahoo CH. Binek W. Kleemann J.B. Sousa S. Cardoso 《Phase Transitions》2013,86(4-5):367-375
Ac susceptibility measurements were performed on discontinuous magnetic multilayers [Co 80 Fe 20 ( t )/Al 2 O 3 (3 nm)] 10 , t = 0.9 and 1.0 nm, by Superconducting Quantum Interference Device (SQUID) magnetometry. The CoFe forms nearly spherical ferromagnetic single-domain nanoparticles in the diamagnetic Al 2 O 3 matrix. Due to dipolar interactions and random distribution of anisotropy axes the system exhibits a spin-glass phase. We measured the ac susceptibility as a function of temperature 20 h T h 100 K at different dc fields and as a function of frequency 0.01 h f h 1000 Hz. The spectral data were successfully analyzed by use of the phenomenological Cole-Cole model, giving a power-law temperature dependence of the characteristic relaxation time c and a high value for the polydispersivity exponent, f , 0.8, typical of spin glass systems. 相似文献