2,648 research outputs found

    Room- and High-Temperature Fatigue Strength of the T5 and Rapid T6 Heat-Treated AlSi10Mg Alloy Produced by Laser-Based Powder Bed Fusion

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    The AlSi10Mg alloy produced by laser-based powder bed fusion (L-PBF) is widely used to produce high-value-added structural parts subjected to cyclic mechanical loads at high temperatures. The paper aims to widen the knowledge of the room- and high-temperature (200 ‚ó¶C) fatigue behavior of the L-PBF AlSi10Mg alloy by analyzing the fully reversed rotating bending test results on mechanically polished specimens. Two heat-treated conditions are analyzed: T5 (direct artificial aging: 4 h at 160 ‚ó¶C) and novel T6R (rapid solution: 10 min at 510 ‚ó¶C, artificial aging: 6 h at 160 ‚ó¶C). The study highlights that (i) the T6R alloy is characterized by higher fatigue strength at room (108 MPa) and high temperatures (92 MPa) than the T5 alloy (92 and 78 MPa, respectively); (ii) thermal exposure at 200 ‚ó¶C up to 17 h does not introduce macroscopical microstructural variation; (iii) fracture surfaces of the room- and high-temperature-tested specimens show comparable crack initiation, mostly from sub-superficial gas and keyhole pores, and failure propagation mechanisms. In conclusion, the L-PBF AlSi10Mg alloy offers good cyclic mechanical performances under various operating conditions, especially for the T6R alloy, and could be considered for structural components operating at temperatures up to 200 ¬į

    Fermi-LAT gamma-ray anisotropy and intensity explained by unresolved Radio-Loud Active Galactic Nuclei

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    Radio-loud active galactic nuclei (AGN) are expected to contribute substantially to both the intensity and anisotropy of the isotropic gamma-ray background (IGRB). In turn, the measured properties of the IGRB can be used to constrain the characteristics of proposed contributing source classes. We consider individual subclasses of radio-loud AGN, including low-, intermediate-, and high-synchrotron-peaked BL Lacertae objects, flat-spectrum radio quasars, and misaligned AGN. Using updated models of the gamma-ray luminosity functions of these populations, we evaluate the energy-dependent contribution of each source class to the intensity and anisotropy of the IGRB. We find that collectively radio-loud AGN can account for the entirety of the IGRB intensity and anisotropy as measured by the Fermi Large Area Telescope (LAT). Misaligned AGN provide the bulk of the measured intensity but a negligible contribution to the anisotropy, while high-synchrotron-peaked BL Lacertae objects provide the dominant contribution to the anisotropy. In anticipation of upcoming measurements with the Fermi-LAT and the forthcoming Cherenkov Telescope Array, we predict the anisotropy in the broader energy range that will be accessible to future observations.Comment: 27 pages, 29 figures. This version matches the published version, minor changes onl

    A Novel T6 Rapid Heat Treatment for AlSi10Mg Alloy Produced by Laser-Based Powder Bed Fusion: Comparison with T5 and Conventional T6 Heat Treatments

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    AlSi10Mg is the most widely studied Al alloy used to produce components by laser-basedpowder bed fusion (LPBF), also known as selective laser melting. Several papers have alreadyinvestigated the effects of conventional heat treatment on the microstructure and mechanicalbehavior of the LPBF AlSi10Mg alloy, overlooking, however, the particular microstructureinduced by rapid solidification. This paper reports on the effects of a T5 heat treatment and anovel T6 heat treatment on microstructure and mechanical behavior of the LPBF AlSi10Mgalloy, consisting of rapid solution (10 minutes at 510¬įC) followed by artificial aging (6 hours at160¬įC). The short solution soaking time reduced the typical porosity growth occurring at thehigh temperature and led to a homogeneous distribution of fine globular Si particles in the Almatrix. In addition, it limited the diffusion processes, increasing the amount of Mg and Si insolid solution available for precipitation hardening and avoiding the microstructuralcoarsening. As a result, the strength-ductility balance was improved by increasing both yieldstrength and elongation to failure, respectively of about 14 and 7 pct compared with the bestsolution among those reported in the literature for conventional T6 heat treatment of LPBFAlSi10Mg alloy

    Black Hole - Neutron Star mergers: using kilonovae to constrain the equation of state

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    The merging of a binary system involving two neutron stars (NSs), or a black hole (BH) and a NS, often results in the emission of an electromagnetic (EM) transient. One component of this EM transient is the epic explosion known as a kilonova (KN). The characteristics of the KN emission can be used to probe the equation of state (EoS) of NS matter responsible for its formation. We predict KN light curves from computationally simulated BH-NS mergers, by using the 3D radiative transfer code \texttt{POSSIS}. We investigate two EoSs spanning most of the allowed range of the mass-radius diagram. We also consider a soft EoS compatible with the observational data within the so-called 2-families scenario in which hadronic stars coexist with strange stars. Computed results show that the 2-families scenario, characterized by a soft EoS, should not produce a KN unless the mass of the binary components are small (MBH‚ȧ6M‚äôM_{\rm BH} \leq 6M_{\odot}, MNS‚ȧ1.4M‚äôM_{\rm NS} \leq 1.4M_{\odot}) and the BH is rapidly spinning (ŌáBH‚Č•0.3\chi_{\rm BH} \geq 0.3). In contrast, a strong KN signal potentially observable from future surveys (e.g. VRO/LSST) is produced in the 1-family scenario for a wider region of the parameter space, and even for non-rotating BHs (ŌáBH=0\chi_{\rm BH} = 0) when MBH=4M‚äôM_{\rm BH} = 4M_{\odot} and MNS=1.2M‚äôM_{\rm NS} = 1.2M_{\odot}. We also provide a fit that allows for the calculation of the unbound mass from the observed KN magnitude, without running timely and costly radiative transfer simulations. Findings presented in this paper will be used to interpret light curves anticipated during the fourth observing run (O4), of the advanced LIGO, advanced Virgo and KAGRA interferometers and thus to constrain the EoS of NS matter.Comment: 14 pages, 16 figures, 2 table

    a conditional linear gaussian network to assess the impact of several agronomic settings on the quality of tuscan sangiovese grapes

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    Summary In this paper, a Conditional Linear Gaussian Network (CLGN) model is built for a two-year experiment on Tuscan Sangiovese grapes involving canopy management techniques (number of buds, defoliation and bunch thinning) and harvest time (technological and late harvest). We found that the impact of the considered treatments on the color of wine can be predicted still in the vegetative season of the grapevine; the best treatments to obtain wines with good structure are those with a low number of buds; the best treatments to obtain fresh wines suitable for young consumers are those with technological rather than late harvest, preferably with a high number of buds, and anyway with both defoliation and bunch thinning not performed

    NTNU-SINTEF SolarNet: A solar irradiation monitoring network at high latitudes

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    This study presents a monitoring network for solar irradiation at high latitudes, called NTNU-SINTEF SolarNet. The network collects, with a time resolution ranging from seconds to hours, solar irradiance data, e.g. global horizontal irradiation, diffuse horizontal irradiation, direct normal irradiation, global tilted irradiation, solar energy generation, which are required in solar irradiation modelling in built environments. The network will be used for specific applications, such as (i) anomalies detection, (ii) influences of ground albedo, and (iii) ageing/degradation of solar modules, that are described in this paper. Some characteristics that make the NTNU-SINTEF SolarNet relevant for solar energy research at high latitudes are identified: short distances among the sensors, the ease of data accessibility, the use of the same sensor typologies, and different solar module technologies. The research holds the potential to boost the solar energy digitalization, impacting on several aspects such as predictive and adaptive control strategies for energy management, design of renewable energy system, multi-scale optimization and efficient exploitation of solar energy.publishedVersio

    p53-sensitive epileptic behavior and inflammation in Ft1 hypomorphic mice

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    Epilepsy is a complex clinical condition characterized by repeated spontaneous seizures. Seizures have been linked to multiple drivers including DNA damage accumulation. Investigation of epilepsy physiopathology in humans imposes ethical and practical limitations, for this reason model systems are mostly preferred. Among animal models, mouse mutants are particularly valuable since they allow conjoint behavioral, organismal, and genetic analyses. Along with this, since aging has been associated with higher frequency of seizures, prematurely aging mice, simulating human progeroid diseases, offer a further useful modeling element as they recapitulate aging over a short time-window. Here we report on a mouse mutant with progeroid traits that displays repeated spontaneous seizures. Mutant mice were produced by reducing the expression of the gene Ft1 (AKTIP in humans). In vitro, AKTIP/Ft1 depletion causes telomere aberrations, DNA damage, and cell senescence. AKTIP/Ft1 interacts with lamins, which control nuclear architecture and DNA function. Premature aging defects of Ft1 mutant mice include skeletal alterations and lipodystrophy. The epileptic behavior of Ft1 mutant animals was age and sex linked. Seizures were observed in 18 mutant mice (23.6% of aged ‚Č• 21 weeks), at an average frequency of 2.33 events/mouse. Time distribution of seizures indicated non-random enrichment of seizures over the follow-up period, with 75% of seizures happening in consecutive weeks. The analysis of epileptic brains did not reveal overt brain morphological alterations or severe neurodegeneration, however, Ft1 reduction induced expression of the inflammatory markers IL-6 and TGF-ő≤. Importantly, Ft1 mutant mice with concomitant genetic reduction of the guardian of the genome, p53, showed no seizures or inflammatory marker activation, implicating the DNA damage response into these phenotypes. This work adds insights into the connection among DNA damage, brain function, and aging. In addition, it further underscores the importance of model organisms for studying specific phenotypes, along with permitting the analysis of genetic interactions at the organismal level

    In Vitro Activity of Essential Oils Against Planktonic and Biofilm Cells of Extended-Spectrum ő≤-Lactamase (ESBL)/Carbapenamase-Producing Gram-Negative Bacteria Involved in Human Nosocomial Infections

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    The aim of this study was to analyze the antibacterial activity of four essential oils (EOs), Melaleuca alternifolia, Eucalyptus globulus, Mentha piperita, and Thymus vulgaris, in preventing the development and spread of extended-spectrum -lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae, metallo-beta-lactamase (MBL)-producing Pseudomonas aeruginosa and carbapenemase (KPC)-producing Klebsiella pneumoniae. A total of 60 strains were obtained from the stock collection from the Microbiology Laboratory of Hesperia Hospital, Modena, Italy. Twenty ESBLproducing E. coli, 5 K. pneumoniae, 13 KPC-producing K. pneumoniae, and 20 MBL-producing P. aeruginosa were cultured and reconfirmed as ESBL and carbapenamase producers. Polymerase chain reaction was used for the detection of genes responsible for antibiotic resistance (ESBL and KPC/MBL). Antibacterial activity of the EOs was determined using the agar disk diusion assay, and minimal inhibitory concentrations (MICs) were also evaluated. Lastly, adhesion capability and biofilm formation on polystyrene and glass surfaces were studied in 24 randomly selected strains. M. alternifolia and T. vulgaris EOs showed the best antibacterial activity against all tested strains and, as revealed by agar disk diusion assay, M. alternifolia was the most eective, even at low concentrations. This eect was also confirmed by MICs, with values ranging from 0.5 to 16 g/mL and from 1 to 16 g/mL, for M. alternifolia and T. vulgaris EOs, respectively. The EOs’ antibacterial activity compared to antibiotics confirmed M. alternifolia EO as the best antibacterial agent. T. vulgaris EO also showed a good antibacterial activity with MICs lower than both reference antibiotics. Lastly, a significant anti-biofilm activity was observed for the two EOs (*P < 0.05 and **P < 0.01 for M. alternifolia and T. vulgaris EOs, respectively). A good antibacterial and anti-biofilm activity of M. alternifolia and T. vulgaris EOs against all selected strains was observed, thus demonstrating a future possible use of these EOs to treat infections caused by ESBL/carbapenemase-producing strains, even in association with antibiotics

    Chemico-biological characterization of Torpedino Di Fondi¬ģ tomato fruits. A comparison with San Marzano cultivar at two ripeness stages

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    Torpedino di Fondi (TF) is a hybrid tomato landrace developed in Sicily and recently introduced in the south Lazio area along with the classical San Marzano (SM) cultivar. The present study aimed at characterizing TF tomatoes at both pink and red ripening stages, and at comparing them with traditional SM tomatoes. A multidisciplinary approach consisting of morphological, chemical (FT‚ÄźICR MS, NMR, HPLC, and spectrophotometric methods), and biological (antioxidant and antifungal in vitro activity) analyses was applied. Morphological analysis confirmed the mini‚Äź San Marzano nature and the peculiar crunchy and solid consistency of TF fruits. Pink TF tomatoes displayed the highest content of hydrophilic antioxidants, like total polyphenols (0.192 mg/g), tannins (0.013 mg/g), flavonoids (0.204 mg/g), and chlorophylls a (0.344 mg/g) and b (0.161 mg/g), whereas red TF fruits were characterized by the highest levels of fructose (3000 mg/100 g), glucose (2000 mg/100 g), tryptophan (2.7 mg/100 g), phenylalanine (13 mg/100 g), alanine (25 mg/100 g), and total tri‚Äźunsaturated fatty acids (13% mol). Red SM fruits revealed the greatest content of lipophilic antioxidants, with 1234 mg/g of total carotenoids. In agreement with phenolics content, TF cultivar showed the greatest antioxidant activity. Lastly, red TF inhibited Candida species (albicans, glabrata and krusei) growth
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