Nanoscale electron-beam-driven metamaterial light sources

Free-standing and fiber-coupled photonic metamaterials act as nanoscale, free-electron-driven, tuneable light sources: emission occurs at wavelengths determined by structural geometry in response to electron-beam excitation of metamaterial resonant plasmonic modes

Time-dependent Circulation Flows: Iron Enrichment in Cooling Flows with Heated Return Flows

We describe a new type of dynamical model for hot gas in galaxy groups and clusters in which gas moves simultaneously in both radial directions. Circulation flows are consistent with (1) the failure to observe cooling gas in X-ray spectra, (2) multiphase gas observed near the centers of these flows and (3) the accumulation of iron in the hot gas from Type Ia supernovae in the central galaxy. Dense inflowing gas cools, producing a positive central temperature gradient, as in normal cooling flows. Bubbles of hot, buoyant gas flow outward. Circulation flows eventually cool catastrophically if the outward flowing gas transports mass but no heat; to maintain the circulation both mass and energy must be supplied to the inflowing gas over a large volume, extending to the cooling radius. The rapid radial recirculation of gas produces a flat central core in the gas iron abundance, similar to many observations. We believe the circulation flows described here are the first gasdynamic, long-term evolutionary models that are in good agreement with all essential features observed in the hot gas: little or no gas cools as required by XMM spectra, the gas temperature increases outward near the center, and the gaseous iron abundance is about solar near the center and decreases outward.Comment: 17 pages (emulateapj5) with 6 figures; accepted by The Astrophysical Journa

On the origin of the jet-like radio/X-ray morphology of G290.1-0.8

The origin and evolution of supernova remnants of the mixed-morphology class is not well understood. Several remnants present distorted radio or X-ray shells with jet-like structures. G290.1-0.8 (MSH 11-61A) belongs to this class. We aim to investigate the nature of this supernova remnant in order to unveil the origin of its particular morphology. We based our work on the study of the X-ray emitting plasma properties and the conditions imposed by the cold interstellar medium where the remnant expanded. We use archival radio, HI line data and X-ray observations from XMM-Newton and Chandra observatories, to study G290.1-0.8 and its surrounding medium. Spatially resolved spectral analysis and mean photon energy maps are used to obtain physical and geometrical parameters of the source. Radio continuum and HI line maps give crucial information to understand the radio/X-ray morphology. The X-ray images show that the remnant presents two opposite symmetric bright spots on a symmetry axis running towards the NW-SE direction. Spectral analysis and mean photon energy maps confirm that the physical conditions of the emitting plasma are not homogeneous throughout the remnant. In fact, both bright spots have higher temperatures than the rest of the plasma and its constituents have not reached ionization equilibrium yet. HI line data reveal low density tube-like structures aligned along the same direction. This evidence supports the idea that the particular X-ray morphology observed is a direct consequence of the structure of the interstellar medium where the remnant evolved. However, the possibility that an undetected point-like object, as a neutron star, exists within the remnant and contributes to the X-ray emission cannot be discarded. Finally, we suggest that a supernova explosion due to the collapse of a high-mass star with a strong bipolar wind can explain the supernova remnant morphology.Comment: 8 pages, 6 figures. Accepted for publication in A&

Two-spin entanglement distribution near factorized states

We study the two-spin entanglement distribution along the infinite $S=1/2$ chain described by the XY model in a transverse field; closed analytical expressions are derived for the one-tangle and the concurrences $C_r$, $r$ being the distance between the two possibly entangled spins, for values of the Hamiltonian parameters close to those corresponding to factorized ground states. The total amount of entanglement, the fraction of such entanglement which is stored in pairwise entanglement, and the way such fraction distributes along the chain is discussed, with attention focused on the dependence on the anisotropy of the exchange interaction. Near factorization a characteristic length-scale naturally emerges in the system, which is specifically related with entanglement properties and diverges at the critical point of the fully isotropic model. In general, we find that anisotropy rule a complex behavior of the entanglement properties, which results in the fact that more isotropic models, despite being characterized by a larger amount of total entanglement, present a smaller fraction of pairwise entanglement: the latter, in turn, is more evenly distributed along the chain, to the extent that, in the fully isotropic model at the critical field, the concurrences do not depend on $r$.Comment: 14 pages, 6 figures. Final versio

Electron-beam-driven nanoscale metamaterials light sources

Nanoscale light (ultimately laser) and surface plasmon (ultimately 'spaser') sources for numerous potential nanophotonic applications have generated and continue to generate considerable research interest, with a variety of optically- and electrically-pumped sources recently demonstrated. We show experimentally that beams of free electrons can be used to induce light emission from nanoscale planar photonic metamaterials, at wavelengths determined by both the metamaterial design parameters and the electron energy

Phase-change chalcogenide glass metamaterial

Combining metamaterials with functional media brings a new dimension to their performance. Here we demonstrate substantial resonance frequency tuning in a photonic metamaterial hybridized with an electrically/optically switchable chalcogenide glass. The transition between amorphous and crystalline forms brings about a 10% shift in the near-infrared resonance wavelength of an asymmetric split-ring array, providing transmission modulation functionality with a contrast ratio of 4:1 in a device of sub-wavelength thickness.Comment: 3 pages, 3 figure

Metamaterial electro-optic switch of nanoscale thickness

We demonstrate an innovative concept for nanoscale electro-optic switching. It exploits the frequency shift of a narrow-band Fano resonance mode in a plasmonic planar metamaterial induced by a change in the dielectric properties of an adjacent chalcogenide glass layer. An electrically stimulated transition between amorphous and crystalline forms of the glass brings about a 150 nm shift in the near-infrared resonance providing transmission modulation with a contrast ratio of 4:1 in a device of subwavelength thickness

Drug delivery applications of three-dimensional printed (3DP) mesoporous scaffolds

Mesoporous materials are structures characterized by a well-ordered large pore system with uniform porous dimensions ranging between 2 and 50 nm. Typical samples are zeolite, carbon molecular sieves, porous metal oxides, organic and inorganic porous hybrid and pillared materials, silica clathrate and clathrate hydrates compounds. Improvement in biochemistry and materials science led to the design and implementation of different types of porous materials ranging from rigid to soft two-dimensional (2D) and three-dimensional (3D) skeletons. The present review focuses on the use of three-dimensional printed (3DP) mesoporous scaffolds suitable for a wide range of drug delivery applications, due to their intrinsic high surface area and high pore volume. In the first part, the importance of the porosity of materials employed for drug delivery application was discussed focusing on mesoporous materials. At the end of the introduction, hard and soft templating synthesis for the realization of ordered 2D/3D mesostructured porous materials were described. In the second part, 3DP fabrication techniques, including fused deposition modelling, material jetting as inkjet printing, electron beam melting, selective laser sintering, stereolithography and digital light processing, electrospinning, and two-photon polymerization were described. In the last section, through recent bibliographic research, a wide number of 3D printed mesoporous materials, for in vitro and in vivo drug delivery applications, most of which relate to bone cells and tissues, were presented and summarized in a table in which all the technical and bibliographical details were reported. This review highlights, to a very cross-sectional audience, how the interdisciplinarity of certain branches of knowledge, as those of materials science and nano-microfabrication are, represent a growing valuable aid in the advanced forum for the science and technology of pharmaceutics and biopharmaceutics

Low cost system for visualization and exhibition of pottery finds in archeological museums

The objective of this project is to build a low-cost system for surveying, modeling, prototyping and interactive visualizing aimed at the enhancement of islamic pottery finds of X – XI centuries. The system will allow various applications: the creation of systems for displaying artifacts from the museum alongside the exhibition, the virtual view of restorations from fragments, including AR and VR, the physical reconstruction of the original form using 3D printer to show the pieces in their entirety, as well as the construction of interactive virtual archives to be made available to scholars and visitors