For multiple years, food packaging migration has been a major concern in food and health sciences. Plastics, such as polyethylene, are continuously utilized in food packaging for preservation and easy handling purposes during transportation and storage. In this work, three types of cheese, Edam, Kefalotyri and Parmesan, of different hardness were studied under two complementary vibrational spectroscopy methods, ATR-FTIR and Raman spectroscopy, to determine the migration of low-density polyethylene from plastic packaging to the surface of cheese samples. The experimental duration of this study was set to 28 days due to the degradation time of the selected cheese samples, which is clearly visible after 1 month in refrigerated conditions at 4 °C. Raman and ATR-FTIR measurements were performed at a 4–3–4–3 day pattern to obtain comparative results. Initially, consistency/repeatability measurement tests were performed on Day₀ for each sample of all cheese specimens to understand if there is any overlap between the characteristic Raman and ATR-FTIR peaks of the cheese with the ones from the low-density polyethylene package. We provide evidence that on Day₁₄, peaks of low-density polyethylene appeared due to polymeric migration in all three cheese types we tested. In all cheese samples, microbial outgrowth started to develop after Day₂₁, as observed visually and under the bright-field microscope, causing peak reverse. Food packaging migration was validated using two different approaches of vibrational spectroscopy (Raman and FT-IR), revealing that cheese needs to be consumed within a short time frame in refrigerated conditions at 4 °C.

In this work we present a method for fabricating three dimensional, ultralight and flexible millimeter metamaterial units using a commercial household 3D printer. The method is low-cost, fast, eco-friendly and accessible. In particular, we use the Fused Deposition Modeling 3D printing technique and we fabricate flexible conductive Spilt Ring Resonators (SRRs) in a free-standing form. We characterized the samples experimentally through measurements of their spectral transmission, using standard rectangular microwave waveguides. Our findings show that the resonators produce well defined resonant electromagnetic features that depend on the structural details and the infiltrating dielectric materials, indicating that the thin, flexible and light 3D printed structures may be used as electromagnetic microwave components and electromagnetic fabrics for coating a variety of devices and infrastructure units, while adapting to different shapes and sizes.

The incorporation of graphene nanoplatelets (GnPs) within a polymer matrix can play an important role in the physical properties and the functionality of the composite material. Composites consisting of low-density polyethylene (LDPE) and GnPs of different concentrations were developed by mixing GnPs with a molten form of the polymeric matrix. The effect of the GnPs content on the morphological, structural, and electrical properties of the composites were investigated. As shown, graphene presence and its concentration significantly modified the polymer matrix properties, a behavior that can be employed for tailoring its applicability in electrical applications. It was found that the increase of the graphene platelets concentration seems to promote the formation of graphene agglomerates, air gaps, and inhomogeneities, while higher dielectric constant/lower dielectric losses can be achieved.

We report the discovery of ferroelectricity below 4.5 K in highly underdoped La${}_2$CuO${}_{4+x}$ accompanied by slow charge dynamics which develop below $T$ ∼ 40 K. An anisotropic magnetoelectric response has also been observed, indicating considerable spin-charge coupling in this lightly doped parent high-temperature copper-oxide superconductor. The ferroelectric state is proposed to develop from polar nanoregions, in which spatial inversion symmetry is locally broken due to nonstoichiometric carrier doping.

We theoretically and experimentally demonstrate a thermally tunable anapole metasurface. By thermally changing the dielectric function, our studies unveil the tolerance of the nonradiating anapole source to the presence of dissipation losses in systems of all-dielectric meta-atoms. The so-called anapole state is an ac current distribution of electric and toroidal dipoles in such a relation that their exclusive destructive interference leads to the absence of far-field radiation. It has been shown to exist in variable dielectric configurations that involve assemblies of infinite dielectric rods, yet a systematic study of its tolerance to losses is still open. Here we examine two designs focusing on their tolerance to dissipation losses: one combining the toroidal mode of a peripheral four-cylinder system with the mixed toroidal mode of a single central cylinder of adjusted size, and another consisting of five rods in a regular pentagon arrangement. The first design exhibits a particularly enhanced toroidal dipole moment and high anapole precision. The second design exhibits anapole states with enhanced loss tolerance and, thus, it is the target of our experimental investigation. For the experiment, we use water-based rod metasurfaces designed for anapole operation in the microwave regime and we employ a characterization in a standard rectangular waveguide. The dielectric properties of water exhibit significant temperature dependence that allows for controlled permittivity and dissipation, leading to the dynamical modification of Mie resonances in meta-atoms. Thus, we experimentally prove the emergence of an anapole state and its tolerance to the losses in a well-controlled system; furthermore, we demonstrate and expose the potential of aqueous schemes for tunable electromagnetic applications.