Numerical study of two-airfoil arrangements by a discrete vortex method

Theoretical and Computational Fluid Dynamics - The aerodynamic characteristics of two neighboring airfoils are greatly different from those of a single airfoil, for both attached and detached flow...     

Electrodynamics of Magnetoelectric Media and Magnetoelectric Fields

The relationship between magnetoelectricity and electromagnetism is a subject of a strong interest and numerous discussions in microwave and optical wave physics and material sciences. The definition of the energy and momentum of the electromagnetic (EM) field in a magnetoelectric (ME) medium is not a trivial problem. The question of whether electromagnetism and magnetoelectricity can coexist without an extension of Maxwell's theory arises when the effects of EM energy propagation are studied and the group velocity of the waves in an ME medium is considered. The energy balance equation reveals unusual topological structure of fields in ME materials. Together with certain constraints on the constitutive parameters of a medium, definite constraints on the local field structure should be imposed. Analyzing the EM phenomena inside an ME material, the question “what kind of the near fields arising from a sample of such a material can be measured?” should be answered. The visualization of the ME states requires an experimental technique that is based on an effective coupling to the violation of spatial as well as temporal inversion symmetry. To observe the ME energy in a subwavelength region, it is necessary to assume the existence of first-principle near fields—the ME fields. These are non-Maxwellian near fields with specific properties of violation of spatial and temporal inversion symmetry. A particular interest to the ME fields arises in studies of metamaterials with “artificial-atoms” ME elements.     

Linear viscoelasticity of a two-dimensional glass-former by stress-fluctuation formalism

Viscoelastic properties of dense colloids are investigated using the stress-fluctuation formalism and equilibrium molecular dynamics simulations. The focus is on a two-dimensional (2D) non-additive Lennard-Jones binary mixture, which is a glass-former. Its behaviour is compared with that of a one-component Lennard-Jones system, which forms a 2D crystal with triangular lattice at low temperatures. The systems are under fixed pressure and temperature conditions. The effects of the mixing, the temperature and the pressure are studied. Calculated functions include the shear modulus relaxation function, the dynamic moduli (storage modulus and loss modulus), the complex compliance and the dynamic viscosity. Both the liquid and the solid (crystal and glass) states are investigated. Qualitative aspects are discussed in the light of simple rheological models.     

Optical properties and electronic structure of methylammonium iodocuprate as an X-ray scintillator

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Ultrathin Films of Porous Metal–Organic Polyhedra for Gas Separation

Ultrathin films of a robust Rh^II-based porous metal–organic polyhedra (MOP) have been obtained. Homogeneous and compact monolayer films (ca. 2.5 nm thick) were first formed at the air–water interface, deposited onto different substrates and characterized using spectroscopic methods, scanning transmission electron microscopy and atomic force microscopy. As a proof of concept, the gas separation performance of MOP-supported membranes has also been evaluated. Selective MOP ultrathin films (thickness ca. 60 nm) exhibit remarkable CO₂ permeance and CO₂/N₂ selectivity, demonstrating the great combined potential of MOP and Langmuir-based techniques in separation technologies.     

High-Energy Proton-Beam-Induced Polymerization/Oxygenation of Hydroxynaphthalenes on Meteorites and Nitrogen Transfer from Urea: Modeling Insoluble Organic Matter?

Formation and structural modification of oxygenated polycyclic aromatic hydrocarbons (oxyPAHs) by UV irradiation on minerals have recently been proposed as a possible channel of PAH transformation in astrochemical and prebiotic scenarios of possible relevance for the origin of life. Herein, it is demonstrated that high-energy proton-beam irradiation in the presence of various meteorites, including stony iron, achondrite, and chondrite types, promotes the conversion of two representative oxyPAH compounds, 1-naphthol and 1,8-dihydroxynaphthalene, to complex mixtures of oxygenated and oligomeric derivatives. The main identified products include polyhydroxy derivatives, isomeric dimers encompassing benzofuran and benzopyran scaffolds, and, notably, a range of quinones and perylene derivatives. Addition of urea, a prebiotically relevant chemical precursor, expanded the range of identified species to include, among others, quinone diimines. Proton-beam irradiation of oxyPAH modulated by nitrogen-containing compounds such as urea is proposed as a possible contributory mechanism for the formation and processing of insoluble organic matter in meteorites and in prebiotic processes.     

Biocompatible Lipid‐Coated Persistent Luminescent Nanoparticles for In Vivo Imaging of Dendritic Cell Migration

Dendritic cell (DC)‐based vaccines for immunotherapy have already achieved promising results in the last decade. To further improve current treatment protocols and enhance the therapeutic outcome, noninvasive in vivo tracking of DCs remains of crucial importance. Persistent luminescent nanoparticles (PLNPs) are inorganic materials which show an afterglow for hours after the optical excitation has ceased. If the afterglow is in the near‐infrared, the emission of injected particles can be tracked in vivo. However, stability and toxicity issues limit the use of bare PLNPs for biological applications. Therefore, appropriate surface functionalization is needed to improve their biocompatibility. In this study, it is demonstrated that near‐infrared light emitting LiGa₅O₈:Cr³⁺ nanoparticles can be functionalized with a biocompatible lipid coating which provides them with outstanding stability in biological media. In vitro experiments show efficient uptake, absence of cytotoxicity even at very high particle concentrations, and no adverse effects on the maturation potential of DCs. DCs labeled with lipid‐coated LiGa₅O₈:Cr³⁺ nanoparticles injected in mice can be imaged over days, confirming efficient in vivo migration to the popliteal lymph node. Together the results show that lipid coated LiGa₅O₈:Cr³⁺ nanoparticles possess excellent possibilities for further use in research and development of DC based vaccines.     

Effective p-type photocurrent sensitization of n-Bi2O3 with p-CuBi2O4 and p-CuO: Z-scheme photoelectrochemical system

Journal of Solid State Electrochemistry - Nanostructured n-Bi2O3/p-CuBi2O4/p-CuO photocathodes with incident photon-to-current conversion efficiency IPCEmax = 70%...