Istituto Nazionale di Ricerca Metrologica
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Exact formulation for hysteresis loops and energy loss in Stoner–Wohlfarth systems
Get PDFWe propose an exact expression to describe the hysteresis loops of an ensemble of Stoner–Wohlfarth particles undergoing an alternating quasi-static magnetic field. A statistical approach, which treats the quantities characterizing each particle as random variables, is adopted to get the orientation distribution of the local polarizations with respect to the applied field direction and the constitutive equation of the whole particle assembly. The hysteresis loop area gives the energy loss figure, but we have also obtained a straightforward integral expression for this quantity. The analytical relationships for the symmetric loops and the losses are successfully tested against numerical results, and the mathematical method adopted also displayed the ability to reproduce the “elemental loop” associated with any given particle of the system. While having a fundamental character, the proposed approach bears applicative interest, representing a versatile tool as the core of codes that simulate the behavior of devices employing magnetic components
Electrical and Thermal Conductivities of Single CuxO Nanowires
Get PDFCopper oxide nanowires (NWs) are promising elements for the realization of a wide range of devices for low-power electronics, gas sensors, and energy storage applications, due to their high aspect ratio, low environmental impact, and cost-effective manufacturing. Here, we report on the electrical and thermal properties of copper oxide NWs synthetized through thermal growth directly on copper foil. Structural characterization revealed that the growth process resulted in the formation of vertically aligned NWs on the Cu growth substrate, while the investigation of chemical composition revealed that the NWs were composed of CuO rather than Cu2O. The electrical characterization of single-NW-based devices, in which single NWs were contacted by Cu electrodes, revealed that the NWs were characterized by a conductivity of 7.6 x 10(-2 )Scm(-1). The effect of the metal-insulator interface at the NW-electrode contact was analyzed by comparing characterizations in two-terminal and four-terminal configurations. The effective thermal conductivity of single CuO NWs placed on a substrate was measured using Scanning Thermal Microscopy (SThM), providing a value of 2.6 Wm(-1)K-1, and using a simple Finite Difference model, an estimate for the thermal conductivity of the nanowire itself was obtained as 3.1 Wm(-1)K-1. By shedding new light on the electrical and thermal properties of single CuO NWs, these results can be exploited for the rational design of a wide range of optoelectronic devices based on NWs
Ultrasound boosts doxorubicin efficacy against sensitive and resistant ovarian cancer cells
Get PDFOvarian cancer (OC) is characterised by the highest mortality of all gynaecological malignancies, frequent re-lapses, and the development of resistance to drug therapy. Sonodynamic therapy (SDT) is an innovative anti-cancer approach that combines a chemical/drug (sonosensitizer) with low-intensity ultrasound (US), which are both harmless per se ', with the sonosensitizer being acoustically activated, thus yielding localized cytotoxicity often via reactive oxygen species (ROS) generation. Doxorubicin (Doxo) is a potent chemotherapeutic drug that has also been recommended as a first-line treatment against OC. This research work aims to investigate whether Doxo can be used at very low concentrations, in order to avoid its significant side effects, as a sonosensitiser under US exposure to promote cancer cell death in Doxo non-resistant (A2780/WT) and Doxo resistant (A2780/ ADR) human OC cell lines. Moreover, since recurrence is an important issue in OC, we have also investigated whether the proposed SDT with Doxo induces immunogenic cell death (ICD) and thus hinders OC recurrence. Our results show that the sonodynamic anticancer approach with Doxo is effective in both A2780/WT and A2780/ADR cell lines, and that it proceeds via a ROS-dependent mechanism of action and immune sensitization that is based on the activation of the ICD pathway
Muography
Get PDFMuography takes advantage of the specifc properties of cosmic-ray
muons, relativistic leptons that are much heavier than electrons.
Cosmic-ray muons have strong penetrating power and a relativistic
nature, which means they can be used in a range of technologies,
including imagery; positioning, navigation, timing (PNT); and secured
communication in environments where conventional techniques are
unavailable. As cosmic-ray muons are universally present on Earth,
muographic measurements can be conducted in the same manner
across the globe. Similar results have been produced independent of
where measurements were taken. This has enabled the muographic
feld to grow and develop into a powerful tool for investigating natural
phenomena, cultural heritage and PNT. This Primer is intended as an
introductory article that introduces new and established muographic
techniques. Case studies are provided, with examples from recent
interdisciplinary advances. Data reproducibility and limitations are
discussed, before fnishing with an outlook of future developments
Spectral tuning of Bloch Surface Wave resonances by light-controlled optical anisotropy
Get PDFFostered by the recent advancements in photonic technologies, the need for all-optical dynamic control on complex photonic elements is emerging as more and more relevant, especially in integrated photonics and metasurface-based flat-optics. In this framework, optically-induced anisotropy has been proposed as powerful mean enabling tuning functionalities in several planar architectures. Here, we design and fabricate an anisotropic two-dimensional bull's eye cavity inscribed within an optically-active polymeric film spun on a one-dimensional photonic crystal sustaining Bloch surface waves (BSW). Thanks to the cavity morphology, two surface resonant modes with substantially orthogonal polarizations can be coupled within the cavity from free-space illumination. We demonstrate that a dynamic control on the resonant mode energies can be easily operated by modulating the orientation of the optically-induced birefringence on the surface, via a polarized external laser beam. Overall, reversible blue- and red-shifts of the resonant BSWs are observed within a spectral range of about 2 nm, with a moderate laser power illumination. The polymeric structure is constituted by a novel blend of an azopolymer and a thermally-sensitive resist, which allows a precise patterning via thermal scanning probe lithography, while providing a significant structural integrity against photo-fluidization or mass-flow effects commonly occurring in irradiated azopolymers. The proposed approach based on tailored birefringence opens up new pathways to finely control the optical coupling of localized surface modes to/from free-space radiation, particularly in hybrid organic-inorganic devices
A cryogenic sapphire resonator oscillator with 10 − 16 mid-term fractional frequency stability
Get PDFHigh kinetic inductance NbTiN films for quantum limited traveling wave parametric amplifiers
No full textStudio pilota per la valutazione di una procedura per la taratura di termometri misuratori della temperatura dell’aria.
Get PDFThis EURAMET project includes two main activities: Perform a pilot study (in the form of an interlaboratory comparison) to explore issues around calibration in air of temperature sensors; Feed into a guidance document the findings from the pilot study. Background and need for the project Air temperature is measured for a multitude of purposes. Atmospheric air temperature is the key variable in indoor climatisation, in meteorological observations and climate studies. It is also critical to precision dimensional and mass measurements. Understanding and fully evaluating measurement uncertainty for air temperature measurements is an open scientific and technical issue now motivating research efforts and discussion both at the CIPM CCT and in WMO expert teams. While calibration of temperature sensors in liquid is well characterised, the calibration of thermometers in air still requires definition of procedures and guidelines. The problem of the lack of a guide for the calibration of thermometers in air was underlined at the EURAMET TC-T meeting of 2017 as a result of a specific scientific workshop on the matter. The analysis of the air temperature measurement procedures and uncertainty evaluation, including the aspects and contributions due to the calibration of sensors is also a task of the CCT Working Group on Environment and is included in the strategy roadmap of CCT