Nontopological Condensates for the Self‐Dual Chern‐Simons‐Higgs Model

For the abelian self‐dual Chern‐Simons‐Higgs model we address existence issues of periodic vortex configurations—the so‐called condensates—of nontopological type as k → 0, where k > 0 is the Chern‐Simons parameter. We provide a positive answer to the longstanding problem on the existence of nontopological condensates with magnetic field concentrated at some of the vortex points (as a sum of Dirac measures) as k → 0, a question that is of definite physical interest. © 2015 Wiley Periodicals, Inc.     

Period two implies chaos for a class of ODEs

We extend a result of J. Andres and K. Pastor concerning scalar time-periodic first order ordinary differential equations without uniqueness, by proving that the existence of just one subharmonic implies the existence of large sets of subharmonics of all given orders. Since these periodic solutions must coexist with complicated dynamics, we might paraphrase T. Y. Li and J. A. Yorke by loosely saying that in this setting even period two implies chaos. Similar results are obtained for a class of differential inclusions.

     

Asymmetric Poincaré inequalities and solvability of capillarity problems

In this paper we first establish an asymmetric version of the Poincaré inequality in the space of bounded variation functions, and then, basically relying on this result, we discuss the existence, the non-existence and the multiplicity of bounded variation solutions of a class of capillarity problems with asymmetric perturbations.     

Synthesis of Iron Oxide Nanoparticles in Listeria innocua Dps (DNA‐Binding Protein from Starved Cells): A Study with the Wild‐Type Protein and a Catalytic Centre Mutant

A comparative analysis of the magnetic properties of iron oxide nanoparticles grown in the cavity of the DNA‐binding protein from starved cells of the bacterium Listeria innocua, LiDps, and of its triple‐mutant lacking the catalytic ferroxidase centre, LiDps‐tm, is presented. TEM images and static and dynamic magnetic and electron magnetic resonance (EMR) measurements reveal that, under the applied preparation conditions, namely alkaline pH, high temperature (65 °C), exclusion of oxygen, and the presence of hydrogen peroxide, maghemite and/or magnetite nanoparticles with an average diameter of about 3 nm are mineralised inside the cavities of both LiDps and LiDps‐tm. The magnetic nanoparticles (MNPs) thus formed show similar magnetic properties, with superparamagnetic behaviour above 4.5 K and a large magnetic anisotropy. Interestingly, in the EMR spectra an absorption at half‐field is observed, which can be considered as a manifestation of the quantum behaviour of the MNPs. These results indicate that Dps proteins can be advantageously used for the production of nanomagnets at the interface between molecular clusters and traditional MNPs and that the presence of the ferroxidase centre, though increasing the efficiency of nanoparticle formation, does not affect the nature and fine structure of the MNPs. Importantly, the self‐organisation of MNP‐containing Dps on HRTEM grids suggests that Dps‐enclosed MNPs can be deposited on surfaces in an ordered fashion.     

Highly selective vapochromic fluorescence of polycarbonate films Doped with an ICT‐Based solvatochromic probe

The vapochromic properties of a fluorescent 3‐[2‐(4‐nitrophenyl) ethenyl]‐1‐(2‐ethylhexyl)‐2‐methylindole (NPEMI‐E) characterized by intramolecular charge transfer (ICT) character, dispersed in polycarbonate (PC) films is reported. NPEMI‐E solvatochromism is investigated by means of experimental and computational methods. Fluorescent PC films containing 0.1 wt % of NPEMI‐E are prepared and exposed to saturated atmospheres of different volatile organic compounds (VOCs). NPEMI‐E/PC films show remarkable and reversible vapochromism when exposed to VOCs with high polarity index and favorable interaction with PC matrix such as CHCl₃. Only minor variations in the emission wavelength are actually recorded for all other classes of VOCs investigated. The hue parameter is also used for the effective extraction of spectral information from digital color images without the need for wavelength discriminators. Overall, the present results support the use of NPEMI‐E/PC films for the cost‐effective detection of CHCl₃ vapors. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1171–1180     

Luminescent iridium(III) complexes with N^C^N-coordinated terdentate ligands: dual tuning of the emission energy and application to organic light-emitting devices

A family of complexes (1a-3a and 1b-3b) was prepared, having the structure Ir(N^C^N)(N^C)Cl. Here, N^C(∧)N represents a terdentate, cyclometallating ligand derived from 1,3-di(2-pyridyl)benzene incorporating CH(3) (1a,b), F (2a,b), or CF(3) (3a,b) substituents at the 4 and 6 positions of the benzene ring, and N^C is 2-phenylpyridine (series a) or 2-(2,4-difluorophenyl)pyridine (series b). The complexes are formed using a stepwise procedure that relies on the initial introduction of the terdentate ligand to form a dichloro-bridged iridium dimer, followed by cleavage with the N^C ligand. (1)H NMR spectroscopy reveals that the isomer that is exclusively formed in each case is that in which the pyridyl ring of the N^C ligand is trans to the cyclometallating aryl ring of the N^C^N ligand. This conclusion is unequivocally confirmed by X-ray diffraction analysis for two of the complexes (1b and 3a). All of the complexes are highly luminescent in degassed solution at room temperature, emitting in the green (1a,b), blue-green (2a,b), and orange-red (3a,b) regions. The bidentate ligand offers independent fine-tuning of the emission energy: for each pair, the "b" complex is blue-shifted relative to the analogous "a" complex. These trends in the excited-state energies are rationalized in terms of the relative magnitudes of the effects of the substituents on the highest occupied and lowest unoccupied orbitals, convincingly supported by time-dependent density functional theory (TD-DFT) calculations. Luminescence quantum yields are high, up to 0.7 in solution and close to unity in a PMMA matrix for the green-emitting complexes. Organic light emitting devices (OLEDs) employing this family of complexes as phosphorescent emitters have been prepared. They display high efficiencies, at least comparable, and in some cases superior, to similar devices using the well-known tris-bidentate complexes such as fac-Ir(ppy)(3). The combination of terdentate and bidentate ligands is seen to offer a versatile approach to tuning of the photophysical properties of iridium-based emitters for such applications.     

Computation of the eigenvalues of Fredholm–Stieltjes integral equations

The Rayleigh–Ritz and the inverse iteration methods are used in order to compute the eigenvalues of Fredholm–Stieltjes integral equations, i.e. Fredholm equations with respect to suitable Stieltjes-type measures. Some applications to the so-called ‘charged’ (in German ‘belastete’) integral equation, and particularly the problem of computing the eigenvalues of a string charged by a finite number of cursors are given.     

Lyapunov Functions for Infinite-Dimensional Systems

We study Lyapunov functions for infinite-dimensional dynamical systems governed by general maximal monotone operators. We obtain a characterization of Lyapunov pairs by means of the associated Hamilton-Jacobi partial differential equations, whose solutions are meant in the viscosity sense, as evolved in works of Tataru and Crandall-Lions. Our approach also leads to a new sufficient condition for Lyapunov pairs, generalizing a classical result of Pazy.     

An Iterative Variant of the Degenerate Kernel Method for Solving Fredholm Integral Equations

An iterative variant of the classical degenerate kernel method for solving Fredholm integral equations of the second kind is presented and its convergence properties are studied.