Advanced radar absorbing ceramic-based materials for multifunctional applications in space environment

In this review, some results of the experimental activity carried out by the authors on advanced composite materials for space applications are reported. Composites are widely employed in the aerospace industry thanks to their lightweight and advanced thermo-mechanical and electrical properties. A critical issue to tackle using engineered materials for space activities is providing two or more specific functionalities by means of single items/components. In this scenario, carbon-based composites are believed to be ideal candidates for the forthcoming development of aerospace research and space missions, since a widespread variety of multi-functional structures are allowed by employing these materials. The research results described here suggest that hybrid ceramic/polymeric structures could be employed as spacecraft-specific subsystems in order to ensure extreme temperature withstanding and electromagnetic shielding behavior simultaneously. The morphological and thermo-mechanical analysis of carbon/carbon (C/C) three-dimensional (3D) shell prototypes is reported; then, the microwave characterization of multilayered carbon-filled micro-/nano-composite panels is described. Finally, the possibility of combining the C/C bulk with a carbon-reinforced skin in a synergic arrangement is discussed, with the aid of numerical and experimental analyses

Resonant Transport in Nb/GaAs/AlGaAs/GaAs Microstructures

Resonant transport in a hybrid semiconductor-superconductor microstructure grown by MBE on GaAs is presented. This structure experimentally realizes the prototype system originally proposed by de Gennes and Saint-James in 1963 in \emph{all}-metal structures. A low temperature single peak superimposed to the characteristic Andreev-dominated subgap conductance represents the mark of such resonant behavior. Random matrix theory of quantum transport was employed in order to analyze the observed magnetotransport properties and ballistic effects were included by directly solving the Bogoliubov-de Gennes equations.Comment: 7 pages REVTeX, 4 figures, to be published by World Scientific in Proceedings of International Symposium on Mesoscopic Superconductivity and Spintronics (NTT R&D Center Atsugi, Japan, March 2002

STAT3, a hub protein of cellular signaling pathways, is triggered by β-hexaclorocyclohexane

Background: Organochlorine pesticides (OCPs) are widely distributed in the environment and their toxicity is mostly associated with the molecular mechanisms of endocrine disruption. Among OCPs, particular attention was focused on the effects of β-hexaclorocyclohexane (β-HCH), a widely common pollutant. A detailed epidemiological study carried out on exposed population in the “Valle del Sacco” found correlations between the incidence of a wide range of diseases and the occurrence of β-HCH contamination. Taking into account the pleiotropic role of the protein signal transducer and activator of transcription 3 (STAT3), its function as a hub protein in cellular signaling pathways triggered by β-HCH was investigated in different cell lines corresponding to tissues that are especially vulnerable to damage by environmental pollutants. Materials and Methods: Human prostate cancer (LNCaP), human breast cancer (MCF-7 and MDA-MB 468), and human hepatoma (HepG2) cell lines were treated with 10 µM β-HCH in the presence or absence of specific inhibitors for different receptors. All samples were subjected to analysis by immunoblotting and RT-qPCR. Results and Conclusions: The preliminary results allow us to hypothesize the involvement of STAT3, through both its canonical and non-canonical pathways, in response to β-HCH. Moreover, we ascertained the role of STAT3 as a master regulator of energy metabolism via the altered expression and localization of HIF-1α and PKM2, respectively, resulting in a Warburg-like effect

A new advanced railgun system for debris impact study

The growing quantity of debris in Earth orbit poses a danger to users of the orbital environment, such as spacecraft. It also increases the risk that humans or manmade structures could be impacted when objects reenter Earth's atmosphere. During the design of a spacecraft, a requirement may be specified for the surviv-ability of the spacecraft against Meteoroid / Orbital Debris (M/OD) impacts throughout the mission; further-more, the structure of a spacecraft is designed to insure its integrity during the launch and, if it is reusable, during descent, re-entry and landing. In addition, the structure has to provide required stiffness in order to allow for exact positioning of experiments and antennas, and it has to protect the payload against the space environment. In order to decrease the probability of spacecraft failure caused by M/OD, space maneuver is needed to avoid M/OD if the M/OD has dimensions larger than 10cm, but for M/OD with dimensions less than 1cm M/OD shields are needed for spacecrafts. It is therefore necessary to determine the impact-related failure mechanisms and associated ballistic limit equations (BLEs) for typical spacecraft components and subsys-tems. The methods that are used to obtain the ballistic limit equations are numerical simulations and la-borato-ry experiments. In order to perform an high energy ballistic characterization of layered structures, a new ad-vanced electromagnetic accelerator, called railgun, has been assembled and tuned. A railgun is an electrically powered electromagnetic projectile launcher. Such device is made up of a pair of parallel conducting rails, which a sliding metallic armature is accelerated along by the electromagnetic effect (Lorentz force) of a cur-rent that flows down one rail, into the armature and then back along the other rail, thanks to a high power pulse given by a bank of capacitors. A tunable power supplier is used to set the capacitors charging voltage at the desired level: in this way the Rail Gun energy can be tuned as a function of the desired bullet velocity. This facility is able to analyze both low and high velocity impacts. A numerical simulation is also performed by using the Ansys Autodyn code in order to analyze the damage. The experimental results and numerical simulations show that the railgun-device is a good candidate to perform impact testing of materials in the space debris energy range

Large Eddy Simulation of acoustic pulse propagation and turbulent flow interaction in expansion mufflers

A novel hybrid pressure-based compressible solver is developed and validated for low Mach number acoustic flow simulation. The solver is applied to the propagation of an acoustic pulse in a simple expansion muffler, a configuration frequently employed in HVAC and automotive exhaust systems. A set of benchmark results for experimental analysis of the simple expansion muffler both with and without flow are obtained to compare attenuation in forced pulsation for various mean-flow velocities. The experimental results are then used for validation of the proposed pressure-based compressible solver. Compressible, Unsteady Reynolds Averaged Navier–Stokes (URANS) simulation of a muffler with a mean through flow is conducted and results are presented to demonstrate inherent limitations associated with this approach. Consequently, a mixed synthetic inflow boundary condition is developed and validated for compressible Large Eddy Simulation (LES) of channel flow. The mixed synthetic boundary is then employed for LES of a simple expansion muffler to analyse the flow-acoustic and acoustic-pulse interactions inside the expansion muffler. The improvement in the prediction of vortex shedding inside the chamber is highlighted in comparison to the URANS method. Further, the effect of forced pulsation on flow-acoustic is observed in regard to the shift in Strouhal number inside the simple expansion muffler

Early predictive response to multi-tyrosine kinase inhibitors in advanced refractory radioactive-iodine differentiated thyroid cancer: A new challenge for [18 f]fdg pet/ct

Differentiated thyroid cancer (DTC) represents the most common thyroid cancer histotype. Generally, it exhibits a good prognosis after conventional treatments; nevertheless, about 20% of patients can develop a local recurrence and/or distant metastasis. In one-third of advanced DTC, the metastatic lesions lose the ability to take up iodine and become radioactive iodine-refractory (RAI-R) DTC. In this set of patients, the possibility to perform localized treatments should always be taken into consideration before the initiation of systemic therapy. In the last decade, some multi-tyrosine kinase inhibitor (MKI) drugs were approved for advanced DTC, impacting on patient’s survival rate, but at the same time, these therapies have been associated with several adverse events. In this clinical context, the role of 2-deoxy-2-[18 F]fluoro-D-glucose positron emission tomography/computed tomography ([18 F]FDG PET/CT) in the early treatment response to these innovative therapies was investigated, in order to assess the potentiality of this diagnostic tool in the early recognition of non-responders, avoiding unnecessary therapy. Herein, we aimed to present a critical overview about the reliability of [18 F]FDG PET/CT in the early predictive response to MKIs in advanced differentiated thyroid cancer

Reflectionless tunneling in planar Nb/GaAs hybrid junctions

Reflectionless-tunneling was observed in Nb/GaAs superconductor/semiconductor junctions fabricated through a two-step procedure. First, periodic $\delta$-doped layers were grown by molecular beam epitaxy near the GaAs surface, followed by an As cap layer to protect the surface during {\it ex-situ} transfer. Second, Nb was deposited by dc-magnetron sputtering onto the GaAs(001) 2 $\times$ 4 surface {\it in-situ} after thermal desorption of the cap layer. The magnetotransport behavior of the resulting hybrid junctions was successfully analyzed within the random matrix theory of phase-coherent Andreev transport. The impact of junction morphology on reflectionless tunneling and the applicability of the fabrication technique to the realization of complex superconductor/semiconductor mesoscopic systems are discussed.Comment: 10 pages, 3 figures, to be published in Appl. Phys. Let

Unfolding political attitudes through the face: facial expressions when reading emotion language of left- and right-wing political leaders

Spontaneous emotionally congruent facial responses (ECFR) to others\u2019 emotional expressions can occur by simply observing others\u2019 faces (i.e., smiling) or by reading emotion related words (i.e., to smile). The goal of the present study was to examine whether language describing political leaders\u2019 emotions affects voters by inducing emotionally congruent facial reactions as a function of readers\u2019 and politicians\u2019 shared political orientation. Participants read sentences describing politicians\u2019 emotional expressions, while their facial muscle activation was measured by means of electromyography (EMG). Results showed that reading sentences describing left and right-wing politicians \u201csmiling\u201d or \u201cfrowning\u201d elicits ECFR for ingroup but not outgroup members. Remarkably, ECFR were sensitive to attitudes toward individual leaders beyond the ingroup vs. outgroup political divide. Through integrating behavioral and physiological methods we were able to consistently tap on a \u2018favored political leader effect\u2019 thus capturing political attitudes towards an individual politician at a given moment of time, at multiple levels (explicit responses and automatic ECFR) and across political party membership lines. Our findings highlight the role of verbal behavior of politicians in affecting voters\u2019 facial expressions with important implications for social judgment and behavioral outcomes

Covid-19 and ENT practice: Our experience: ENT outpatient department, ward and operating room management during the SARS-CoV-2 pandemic

Coronavirus COVID-19 SARS-CoV-2 ENT Otolaryngolog

Strontium-Substituted α-TCP: Structure, Stability, and Reactivity in Solution

& alpha;-Tricalcium phosphate (& alpha;-TCP) is widelyused as acomponent of bone cements, and many efforts have been made to dopeit with strontium ion (Sr), which is known for its beneficial rolein bone tissue. However, the range of possible substitution of strontiumfor calcium (Ca) into & alpha;-TCP, as well as its effect on the & alpha;-TCPstructure, has not been clarified yet. Herein, we investigate thissubstitution through the examination of & alpha;-TCP synthesized athigh temperatures in the presence of increasing amounts of strontiumaccording to two different routes: 1-step and 2-steps. The results show that Sr can enter into an & alpha;-TCPstructure up to about 10 atom % and substitutes for calcium mostlyat specific cation sites, namely, M(5), M(11), and M(17), characterizedby relatively low bond valence sums and long mean Ca-O distance.Strontium presence stabilizes & alpha;-TCP delaying its transformationinto octacalcium phosphate and hydroxyapatite in H3PO4, as well as in physiological solution. Although the two methodsof synthesis provide similar structural results, the products of 1-step synthesis display a slightly smaller crystallitesize and greater solubility and, as a consequence, a faster hydrolysisreaction.& alpha;-Tricalcium phosphatepreparation through the solid-statereaction is described following two different procedures. The investigationof the range of possible substitution of strontium for calcium into & alpha;-TCP as well as its effect on the & alpha;-TCP structure ispresented. Furthermore, it is shown that strontium presence stabilizes & alpha;-TCP and delays its hydrolysis reaction into octacalcium phosphateand hydroxyapatite