Search results for " frame"
showing 10 items of 1365 documents
Coupled Susy, pseudo-bosons and a deformed su(1, 1) Lie algebra
2021
Abstract In a recent paper a pair of operators a and b satisfying the equations a † a = bb † + γ 1 and aa † = b † b + δ 1 , has been considered, and their nature of ladder operators has been deduced and analyzed. Here, motivated by the spreading interest in non self-adjoint operators in quantum mechanics, we extend this situation to a set of four operators, c, d, r and s, satisfying dc = rs + γ 1 and cd = sr + δ 1 , and we show that they are also ladder operators. We show their connection with biorthogonal families of vectors and with the so-called D -pseudo bosons. Some examples are discussed.
Gabor-like systems in ${cal L}^2({bf R}^d)$ and extensions to wavelets
2008
In this paper we show how to construct a certain class of orthonormal bases in starting from one or more Gabor orthonormal bases in . Each such basis can be obtained acting on a single function with a set of unitary operators which operate as translation and modulation operators in suitable variables. The same procedure is also extended to frames and wavelets. Many examples are discussed.
Classification of multipartite systems featuring only $|W\rangle$ and $|GHZ\rangle$ genuine entangled states
2015
In this paper we present several multipartite quantum systems featuring the same type of genuine (tripartite) entanglement. Based on a geometric interpretation of the so-called $|W\rangle$ and $|GHZ\rangle$ states we show that the classification of all multipartite systems featuring those and only those two classes of genuine entanglement can be deduced from earlier work of algebraic geometers. This classification corresponds in fact to classification of fundamental subadjoint varieties and establish a connection between those systems, well known in Quantum Information Theory and fundamental simple Lie algebras.
Nanoporosity, Inclusion Chemistry, and Spin Crossover in Orthogonally Interlocked Two-Dimensional Metal-Organic Frameworks
2015
[Fe(tvp)(2)(NCS)(2)] (1) (tvp=trans-(4,4-vinylenedipyridine)) consists of two independent perpendicular stacks of mutually interpenetrated two-dimensional grids. This uncommon supramolecular conformation defines square-sectional nanochannels (diagonal approximate to 2.2nm) in which inclusion molecules are located. The guest-loaded framework 1@guest displays complete thermal spin-crossover (SCO) behavior with the characteristic temperature T-1/2 dependent on the guest molecule, whereas the guest-free species 1 is paramagnetic whatever the temperature. For the benzene-guest derivatives, the characteristic SCO temperature T-1/2 decreases as the Hammet sigma(p) parameter increases. In general, …
Binuclear Cu2+ complex mediated discrimination between L-glutamate and L-aspartate in water.
2005
L-Glutamate and L-aspartate selectivity is achieved by the action of two Cu2+ metal ions rightly disposed in a cyclophanetype macrocyclic framework; electrochemical sensing of glutamate has been achieved by adsorption of the copper complexes on graphite electrodes. Verdejo Viu, Begoña, Begona.Verdejo@uv.es ; Domenech Carbo, Antonio, Antonio.Domenech@uv.es ; Jimenez Garcia, Hermas Rafael, Hermas.Jimenez@uv.es ; Soriano Soto, Concepción, Concepcion.Soriano@uv.es ; Garcia-España Monsonis, Enrique, Enrique.Garcia-Es@uv.es
Peptide Metal–Organic Frameworks for Enantioselective Separation of Chiral Drugs
2017
We report the ability of a chiral Cu(II) 3D MOF based on the tripeptide Gly-L-His-Gly (GHG) for the enantioselective separation of metamphetamine and ephedrine. Monte Carlo simulations suggest that chiral recognition is linked to preferential binding of one of the enantiomers as result of either stronger or additional H-bonds with the framework that lead to energetically more stable diastereomeric adducts. Solid phase extraction (SPE) of a racemic mixture by using Cu(GHG) as extractive phase permits isolating more than 50% of the (+)-ephedrine enantiomer as target compound in only four minutes. To the best of our knowledge, this represents the first example of a MOF capable of separating ch…
Ligand effects on the dimensionality of oxamato-bridged mixed-metal open-framework magnets
2012
Increasing dimensionality [from 2D (1) to 3D (2)] and T(C) [from 10 (1) to 20 K (2)] in two new oxamato-bridged heterobimetallic Mn(II)(2)Cu(II)(3) open-frameworks result from the steric hindrance provided by the different alkyl substituents of the N-phenyloxamate bridging ligands.
Lanthanide Discrimination with Hydroxyl-Decorated Flexible Metal–Organic Frameworks
2018
We report two new highly crystalline metal-organic frameworks (MOFs), derived from the natural amino acids serine (1) and threonine (2), featuring hexagonal channels densely decorated with hydroxyl groups belonging to the amino acid residues. Both 1 and 2 are capable of discriminating, via solid-phase extraction, a mixture of selected chloride salts of lanthanides on the basis of their size, chemical affinity, and/or the flexibility of the network. In addition, this discrimination follows a completely different trend for 1 and 2 because of the different locations of the hydroxyl groups in each compound, which is evocative of steric complementarity between the substrate and receptor. Last bu…
Tunable Spin-Crossover Behavior of the Hofmann-like Network {Fe(bpac)[Pt(CN) 4 ]} through Host-Guest Chemistry
2013
A study of the spin-crossover (SCO) behavior of the tridimensional porous coordination polymer {Fe(bpac)[Pt(CN)4]} (bpac=bis(4-pyridyl) acetylene) on adsorption of different mono- and polyhalobenzene guest molecules is presented. The resolution of the crystal structure of {Fe(bpac)[Pt(CN) 4]}A?G (G=1,2,4-trichlorobenzene) shows preferential guest sites establishing I?A?A?A?I? stacking interactions with the host framework. These host-guest interactions may explain the relationship between the modification of the SCO behavior and both the chemical nature of the guest molecule (electronic factors) and the number of adsorbed molecules (steric factors). Copyright © 2013 WILEY-VCH Verlag GmbH & …
The strategy formation process in the EFQM Excellence Model: a critical review and new perspectives
2011
The adoption of an integrative strategy formation process becomes a way of developing a strategic capability that contributes to generating positive results and sustainable competitive advantages. In today's environments, many companies are also using the EFQM Excellence Model (EEM) to try to develop such a strategic capability. This paper presents an exhaustive review of the literature on the strategic process debate and on the strategic capability of the EEM. As a result, we offer to practitioners a conceptual framework which shows the EEM as a useful driver to facilitate the development of an integrative strategy formation process, and we propose a set of dimensions and variables (the le…