The climate change imposes to mankind a severe management of CO2 emissions in atmosphere. CO2 valorization through electrocatalysis revealed to be a valuable solution to this global issue. SnO2 is an ...electrocatalyst widely investigated for its capability to reduce CO2 to formic acid. In particular, mesoporous SnO2 offers a high adsorption capability, resulting in a high catalytic activity. In order to improve its performance, Fe-doping is here investigated for the first time. We observed that Fe-doped SnO2 exhibits a remarkable 100% enhancement of the partial current density for HCOOH production at relatively low overpotentials, although keeping the selectivity unchanged.
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•Fe-doped SnO2 is a promising electrocatalyst for CO2 reduction.•The fabrication technique employed makes Fe-doped SnO2 is cheap and easily scalable.•The porous structure offers high adsorption capability, and so a high catalytic activity.•Fe-doped SnO2 electrocatalyst offers remarkable enhancement of the partial current density at relatively low overpotentials.
Cosmic rays’ interactions with the residual atmosphere surrounding the Earth produce a variety of particles, like electrons, positrons, protons, anti-protons, and Helium nuclei that can be observed ...below the local geomagnetic cutoff. In this work, we present new measurements of downward-going, albedo proton fluxes with kinetic energy in the range ∼40–∼250 MeV, performed by the High-Energy Particle Detector (HEPD-01) on board of the China Seismo-Electromagnetic Satellite - CSES-01 - at an altitude of ∼500 km. Employing a dedicated trajectory-tracing simulation routine, the protons collected by HEPD-01 are classified into quasi-trapped (QT), long lifetime (≳10 s) particles concentrating in the equatorial region of the Earth, and un-trapped (UT), distributed at all latitudes; the latter includes both precipitating short lifetime particles (UTS) and pseudo-trapped long lifetime (UTL) populations, abundant in the so-called penumbra regions. The temporal trend of re-entrant protons between 2018 and 2022 is also reported, assessing the stability of such population during the data-taking period of HEPD-01; this highlights their independence from the long-term modulating effect of the solar activity.
•A study of re-entrant albedo protons in the Earth’s magnetosphere as a function of energy with the HEPD-01 payload is presented.•A comparison with past experiments is carried out, with good results.•Time-profiles of re-entrant albedo protons show a general stability during the analyzed period.
Abstract
High-energy, long gamma-ray bursts (GRBs) can be generated by the core collapse of massive stars at the end of their lives. When they happen in the close-by universe they can be ...exceptionally bright, as seen from the Earth in the case of the recent, giant, long-lasting GRB221009A. GRB221009A was produced by a collapsing star with a redshift of 0.152: this event was observed by many gamma-ray space experiments, which also detected an extraordinary long gamma-ray afterglow. The exceptionally large fluence of the prompt emission of about 0.013 erg cm
−2
illuminated a large geographical region centered on India and including Europe and Asia. We report in this paper the observation of sudden electron flux changes correlated with GRB221009A and measured by the HEPP-L charged particle detector on board the China Seismo-Electromagnetic Satellite, which was orbiting over Europe at the time of the GRB event. The time structure of the observed electron flux closely matches the very distinctive time dependence of the photon flux associated with the main part of the emission at around 13:20 UTC on 2022 October 9. To test the origin of these signals, we set up a simplified simulation of one HEPP-L subdetector: the results of this analysis suggest that the signals observed are mostly due to electrons created within the aluminum collimator surrounding the silicon detector, providing real-time monitoring of the very intense photon fluxes. We discuss the implications of this observation for existing and forthcoming particle detectors on low Earth orbits.
Abstract
In this paper we report the detection of five strong gamma-ray bursts (GRBs) by the High-Energy Particle Detector (HEPD-01) mounted on board the China Seismo-Electromagnetic Satellite, ...operational since 2018 on a Sun-synchronous polar orbit at a ∼507 km altitude and 97° inclination. HEPD-01 was designed to detect high-energy electrons in the energy range 3–100 MeV, protons in the range 30–300 MeV, and light nuclei in the range 30–300 MeV n
−1
. Nonetheless, Monte Carlo simulations have shown HEPD-01 is sensitive to gamma-ray photons in the energy range 300 keV–50 MeV, even if with a moderate effective area above ∼5 MeV. A dedicated time correlation analysis between GRBs reported in literature and signals from a set of HEPD-01 trigger configuration masks has confirmed the anticipated detector sensitivity to high-energy photons. A comparison between the simultaneous time profiles of HEPD-01 electron fluxes and photons from GRB190114C, GRB190305A, GRB190928A, GRB200826B, and GRB211211A has shown a remarkable similarity, in spite of the different energy ranges. The high-energy response, with peak sensitivity at about 2 MeV, and moderate effective area of the detector in the actual flight configuration explain why these five GRBs, characterized by a fluence above ∼3 × 10
−5
erg cm
−2
in the energy interval 300 keV–50 MeV, have been detected.
Background & Aims The phenotypic and functional characteristics of natural killer (NK) cells in chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are incompletely defined and ...largely controversial. Methods We studied NK cell receptor expression, cytotoxic activity, and cytokine production in peripheral blood mononuclear cells from 35 patients with chronic hepatitis C, 22 with chronic hepatitis B, and 30 healthy controls. Results Patients with chronic HBV infection had an increased proportion of NKG2C+ NK cells with normal inhibitory receptor expression and a lower proportion of activated NK cells compared with HCV+ patients, which was associated with normal or reduced cytolytic activity and markedly dysfunctional tumor necrosis factor-α and interferon-γ production. Patients with chronic HCV infection showed a predominantly activating phenotype, featuring a decreased percentage of cells expressing the inhibitory receptor KIR3DL1 and a concomitant increase in the proportion of NKG2D+ NK cells. Expression of the CD69 early activation antigen on NK cells positively correlated with serum alanine aminotransferase and HCV RNA values, suggesting participation of virus-induced effector NK cells in liver necroinflammation. Phenotypic changes in HCV+ patients were associated with enhanced cytokine-induced cytolytic activity and increased usage of natural cytotoxicity and NKG2D receptor pathways, accompanied by defective cytokine production, although to a lesser extent than patients with chronic HBV infection. Conclusions These findings provide evidence for a functional dichotomy in patients with chronic HBV and HCV infections, featuring conserved or enhanced cytolytic activity and dysfunctional cytokine production, which may contribute to virus persistence.
The dual color infrared thermography is a non-intrusive temperature measurement technique, based on the ratio principle between the signals collected at two near wavelengths in local grey body ...hypotheses and applicable when a thermal camera is equipped with a suitable pair of narrow band filters. In this work, the applicability at high temperatures has been investigated by using an analytical model based on Planck's Law integration, convoluted with the real response curves of sensors, optics, filters and attenuators. The presented model has been validated at high temperature and used to optimize the hardware set up for dual color measurements both in terms of operative spectral band and also for choosing the best pair of filters. Furthermore, spectral emissivity trend curves for different materials, available in literature, and at different temperatures have been used in the theoretical model in order to simulate and replicate experimental results. The experimental simulations obtained with dual color technique have been compared with those obtained through classical techniques based on the a priori knowledge and setting of the emissivity average values.
The aim is to establish in which conditions and for which class of Thermal Protection System (TPS) materials used to protect the inner cold structure of hypersonic space vehicles made of aluminium or metallic alloys, the dual color technique can be used for a more accurate and precise temperature measurement compared to the classical techniques. The applicability study was carried out up to high temperature (2000 °C) which are reached by the TPS surfaces during the re-entry phase from Earth orbit or from interplanetary trajectories due to the high heat flux loads produced by the strong shock wave during the deceleration phase.
Background/Aims Hepatitis C virus (HCV) is a known risk factor for hepatocellular carcinoma (HCC), but whether the risk varies among patients infected with different HCV genotypes is still ...controversial. We performed a meta-analysis to clarify whether the genotype 1b is associated with a higher risk of HCC than other genotypes. Methods We identified 57 relevant papers through a literature search to December 2007 but, since age could represent a major confounder, we focused the meta-analysis on the 21 studies presenting age-adjusted risk estimates for HCV genotype 1b vs. other genotypes. We used random-effects models with the DerSimonian–Laird method and assessed heterogeneity between studies and publication bias. Results Patients infected with HCV genotype 1b have almost double the risk to develop HCC than those infected with other genotypes (Relative Risk (95% Confidence Intervals) = 1.78(1.36–2.32)). The pooled risk estimate was somewhat lower when we restricted the analysis to the eight studies conducted in patients with liver cirrhosis (1.60;1.07–2.39) or considering the 36 studies presenting only crude data (1.63;1.30–2.06). In seven studies excluding patients with liver cirrhosis, the RR (95% CI) increased to 2.46(1.69–3.59). Conclusions This meta-analysis suggests that HCV genotype 1b plays an important role in HCC development, especially in patients with early stage liver disease.
The reentry conditions endured by a vehicle entering the atmosphere from an Earth orbit or from an interplanetary trajectory are the most critical phases for materials used as Thermal Protection ...Systems (TPSs), since the spacecraft surfaces have to withstand extremely high heat fluxes and loads due to the hot plasmas generated downstream of the high energy shock waves due to the extreme deceleration. The gases are highly excited and heated to values up to 10000 K immediately downstream of the shock waves. The TPS surfaces are then heated by these gases through convection and radiation, producing very high wall heat fluxes and associated temperatures, which can produce TPS surface temperatures of up to 2300 K. Passive and active TPSs are employed to protect the inner cold structures of the spacecraft which are made from aluminium or metallic alloys. Passive TPS are classified as reusable or single use (ablative) materials. Facilities such as plasma wind tunnels are used to experimentally reproduce the atmospheric reentry of such vehicles. Their use allows the testing and qualification of the TPS which is subjected to thermal and mechanical stresses induced by the hypersonic jet in spite of the unavoidable intrinsic limitations when the complex flight physics phenomena are reproduced in ground test facilities. One of the most complex issues, associated with aerospace safety during a hypersonic Plasma Wind Tunnel test campaign is to measure the free jet temperature and monitor the high heat fluxes generated by the hot plasma, the correlated TPS surface temperatures, and the erosion rate (i.e., recession rate) affecting the behavior of materials representative of space vehicle subcomponents.
The purpose of the present work is to review the diagnostic methodologies used in hypersonic test facilities associated with the working principles, the development, the potential and the limitations of arc jet plasma wind tunnels for the evaluation of the aforementioned critical parameters. At the same time, this review aims to illustrate the most advanced and sensitive non-intrusive diagnostics for the determination of the free jet temperature and its oxygen composition by means of spontaneous Optical Emission Spectroscopy (OES) and Laser Induced Fluorescence (LIF) respectively, and for the determination of the TPS temperature and erosion rate using free emissivity Dual Color Infrared Thermography (DCIT) and on Surface Layer Implantation (SLI) of radioactive tracers techniques.
This is a description of the conceptual foundations used for designing a novel learning environment for mechanics implemented as an Industrial Educational Laboratory - called Fisica in Moto (FiM) - ...at the Ducati Foundation in Bologna. In this paper, we will describe the motivation for and design of the conceptual approach to mechanics used in the lab - as such, the paper is theoretical in nature. The goal of FiM is to provide an approach to the teaching of mechanics based upon imaginative structures found in continuum physics suitable to engineering and science. We show how continuum physics creates models of mechanical phenomena by using momentum and angular momentum as primitive quantities. We analyse this approach in terms of cognitive linguistic concepts such as conceptual metaphor and narrative framing of macroscopic physical phenomena. The model discussed here has been used in the didactical design of the actual lab and raises questions for an investigation of student learning of mechanics in a narrative setting.
The dual color infrared thermography is a non-intrusive temperature measurement technique, based on the ratio principle between the signals collected at two near wavelengths in local grey body ...hypotheses and applicable when a thermal camera is equipped with a suitable pair of narrow band filters. The technique can reveal its utility in fields of applied physics where intrusive techniques are not allowed and/or materials are characterized by unknown emissivity. This physics methodology can be really useful, for example, in temperature determination of solid targets due to ions bombarding by means of accelerators for nuclear (Astro) Physics, environmental physics applications and/or in temperature determination of Space materials (such as TPS - Thermal Protection Systems).
In this work, the applicability at high temperatures has been investigated by using an analytical model based on Planck’s Law integration, convoluted with the real response curves of sensors, optics, filters and attenuators. The presented model has been validated at high temperature and used to optimize the hardware set up for dual color measurements both in terms of operative spectral band and also for choosing the best pair of filters. Furthermore, spectral emissivity trend curves for different materials, available in literature, and at different temperatures have been used in the theoretical model in order to simulate and replicate experimental results. The experimental simulations obtained with dual color technique have been compared with those obtained through classical techniques based on the a priori knowledge and setting of the emissivity average values. The aim is to establish in which conditions and for which class of TPS materials used to protect the inner cold structure of hypersonic space vehicles made of aluminium or metallic alloys, the dual color technique can be used for a more accurate and precise temperature measurement compared to the classical techniques.
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