The aim of this work is to investigate the mechanisms controlling the current-carrying capability of ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ thin films. A comparison between the magnetic properties of a film with intrinsic grain-boundary defects and two films crossed by columnar defects with different densities is presented. Such properties have been studied by means of ac susceptibility measurements, resistivity measurements, and structural characterizations. The Clem and Sanchez model [Phys. Rev. B 50, 9355 (1994)] is used to extract critical current values from the susceptibility data. In the virgin film, correlated grain-boundary defects were created among islands with homogeneous size, by means of the appropriate modifications in the growth process. Columnar defects were produced through 0.25-GeV Au-ion irradiation. The central issue concerns the investigation of the plateaulike features characterizing the log-log field dependence of the critical current density, the analysis of the $J_c$ temperature dependence, and of the irreversibility line. An analytical expression of $J_c$ vs B is given in order to compare the main issues with the experimental data. This model suggests that the intergrain pinning dominates in the high-current/low-temperature regime through a network of frustrated Josephson junctions, while the intragrain pinning is effective near the irreversibility line.

Superconductor‐normal metal‐superconductor (SNS) Josephson junctions consisting of Y‐Ba‐Cu‐O/Au/Nb film‐layered structure have been fabricated using epitaxial Y‐Ba‐Cu‐O films. SNS junctions with a‐b plane orientated Y‐Ba‐Cu‐O films exhibit the Josephson effect, while the junctions with c‐axis orientated Y‐Ba‐Cu‐O films have no Josephson current. Moreover, a‐b plane orientated junctions show anisotropic Fraunhofer patterns in the magnetic field dependence of the critical current according to the direction of film orientations. These anisotropic behaviors reveal that the proximity effect is strongly affected by the anisotropic coherence length and the magnetic penetration depth of Y‐Ba‐Cu‐O films.

Different chemical formulations for the synthesis of highly intercalated graphite bisulfate have been tested. In particular, nitric acid, potassium nitrate, potassium dichromate, potassium permanganate, sodium periodate, sodium chlorate, and hydrogen peroxide have been used in this synthesis scheme as the auxiliary reagent (oxidizing agent). In order to evaluate the presence of delamination, and pre-expansion phenomena, and the achieved intercalation degree in the prepared samples, the obtained graphite intercalation compounds have been characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), infrared spectroscopy (FT-IR), micro-Raman spectroscopy (μ-RS), and thermal analysis (TGA). Delamination and pre-expansion phenomena were observed only for nitric acid, sodium chlorate, and hydrogen peroxide, while the presence of strong oxidizers (KMnO4, K2Cr2O7) led to stable graphite intercalation compounds. The largest content of intercalated bisulfate is achieved in the intercalated compounds obtained from NaIO4 and NaClO3.

Neurodegenerative diseases, particularly affecting aged people, have relevant health and social costs. Different forms of diseases, often involving serious forms of dementia, are included in this class of pathology requiring specific clinical treatments to be fronted. Thus, timely and reliable diagnosis is a critical aspect for choosing a valid medical therapy. A mild cognitive impairment (MCI) reflects a cognitive decline but not yet a state of dementia and often does not compromise daily life activities.¹ Alzheimer’s disease (AD) is a more severe neurodegenerative pathology characterized by a progressive damage of synaptic links and neuronal cells mainly in the hippocampus brain region. The occurrence of pathological aggregates of proteins including beta-amyloid fragments ($\mathrm{A}\beta$-plaques) in the interneuronal spaces of brain tissue and the increased level of tau- and hyperphosphorylated-tau proteins in the cerebrospinal fluid of AD-affected subjects indicated the relevance of beta-amyloids ($\mathrm{A}\beta$) and tau-protein in the AD development.^{2 – 4} Both substances are biomarkers of AD progression^2,4 and are a reliable sign of a neurodegenerative cerebral process also in the early-stage phase.^{5 – 7} These biomarkers can be transported into the vascular system across the blood–brain barrier (BBB).^8,9 The BBB plays an important role in the selective passage of several substances between brain and blood systems and in the maintenance and integrity of the brain. A dysfunctional BBB with impaired ability to clear $\mathrm{A}\beta$ and tau protein from the brain has been associated with the development of AD.¹⁰ Traces of these biomarkers are present in the systemic blood circulation and can rejoin the vascularization of other body districts, as the retina, lens, and lacrimal regions, affecting the composition of tears.^{11 – 13} The relevance of changes occurring in the eye as a consequence of AD has been reported by Lim et al.¹⁴ Consequently, tears are an ideal medium for investigating changes induced by neurodegenerative pathologies. They are easily accessible and can be collected using minimally invasive methods.