A new molecular dyad consisting of a Cy5 chromophore and ferrocene (Fc) and a triad consisting of Cy5, Fc, and β‐cyclodextrin (CD) are synthesized and their photophysical properties investigated at both the ensemble and single‐molecule levels. Hole transfer efficiency from Cy5 to Fc in the dyad is reduced upon addition of CD. This is due to an increase in the Cy5‐Fc separation (r) when the Fc is encapsulated in the macrocyclic host. On the other hand, the triad adopts either a Fc‐CD inclusion complex conformation in which hole transfer quenching of the Cy5 by Fc is minimal or a quasi‐static conformation with short r and rapid charge transfer. Single‐molecule fluorescence measurements reveal that r is lengthened when the triad molecules are deposited on a glass substrate. By combining intramolecular charge transfer and competitive supramolecular interaction, the triad acts as an efficient chemical sensor to detect different bioactive analytes such as amantadine hydrochloride and sodium lithocholate in aqueous solution and synthetic urine. 相似文献
The formation of singularities in finite time in nonlocal Burgers’ equations, with time-fractional derivative, is studied in detail. The occurrence of finite-time singularity is proved, revealing the underlying mechanism, and precise estimates on the blowup time are provided. The employment of the present equation to model a problem arising in job market is also analyzed.
The aim of this paper is to solve a real-world problem proposed by an international company operating in Spain and modeled as a variant of the Open Vehicle Routing Problem in which the makespan, i.e., the maximum time spent on the vehicle by one person, must be minimized. A competitive multi-start algorithm, able to obtain high quality solutions within reasonable computing time is proposed. The effectiveness of the algorithm is analyzed through computational testing on a set of 19 school-bus routing benchmark problems from the literature, and on 9 hard real-world problem instances. 相似文献
The structure of oxotungstate films (as-deposited and subjected to heat treatment at temperatures of up to 600°C) prepared through electrodeposition on platinum and gold polycrystalline substrates is investigated using different physicochemical methods. It is shown that the oxotungstate films consist of X-ray amorphous hydrated mixtures of isopoly compounds, predominantly in the form of paratungstates with [H2W12O42]10− anions. The structural transformation with an increase in the temperature in air is accompanied by the loss of water, the transformation of paratungstate anions into more oxidized forms, their destruction, and the crystallization of nonstoichiometric hydroxylated oxide phases.
In this paper we study the Hankel transformation and convolution on certain spaces
of entire functions and its dual
that is a space of hyperfunctions and contains the (even)-Schwartz space Se′. We prove that the Hankel transform is an automorphism of
. Also the Hankel convolutors of
are investigated.
Authors’ addresses: Jorge J. Betancor, Claudio Jerez and Lourdes Rodríguez-Mesa, Departamento de Análisis Matemático, Universidad
de la Laguna, Campus de Anchieta, Avda. Astrofísico Francisco Sánchez, s/n, 38271 La Laguna (Sta. Cruz de Tenerife), Espa?a;
Sandra M. Molina, Departamento de Matemáticas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata,
Funes 3350 (7600), Mar del Plata, Argentina 相似文献
The newly discovered superconductor FeSe(1-x) (x approximately 0.08, T(c)(onset) approximately 13.5 K at ambient pressure rising to 27 K at 1.48 GPa) exhibits a structural phase transition from tetragonal to orthorhombic below 70 K at ambient pressure-the crystal structure in the superconducting state shows remarkable similarities to that of the REFeAsO(1-x)F(x) (RE = rare earth) superconductors. 相似文献
Structural defects play major role in catalysis and electrocatalysis. Nanocrystalline (or nanostructured) materials composed
of nanometer-sized crystallites joined via grain boundaries have been recognized for their specific structure and properties,
differentiating them from single crystals, coarsely grained materials or nanometer-sized supported single-grained particles
(Gleiter, Nanostruct Mater 1:1–19, 1992). In this paper, we use Pt electrodes, prepared by electrodeposition on glassy carbon and gold supports, as model nanocrystalline
materials to explore the influence of grain boundaries and other structural defects on electrocatalysis of CO and methanol
oxidation. We build on the recently established correlations between the nanostructure (lattice parameter, grain size, and
microstrains) of electrodeposited Pt and the deposition potential (Plyasova et al., Electrochim. Acta 51:4447–4488, 2006) and use the latter to obtain materials with variable density of grain boundary regions. The activity of electrodeposited
Pt in the oxidation of methanol and adsorbed CO exceeds greatly that for Pt(111), polycrystalline Pt, or single-grained Pt
particles. It is proposed that active sites in nanostructured Pt are located at the emergence of grain boundaries at the surface.
For methanol electrooxidation, the electrodes with optimal nanostructure exhibit relatively high rates of the “direct” oxidation
pathway and of the oxidation of strongly adsorbed poisoning intermediate (COads), but not-too-high methanol dehydrogenation rate constant. These electrodes exhibit an initial current increase during potentiostatic
methanol oxidation explained by the COads oxidation rate constant exceeding the methanol decomposition rate constant.