The Afterglow and Kilonova of the Short GRB 160821B Troja, E.; Castro-Tirado, A. J.; Gonzalez, J Becerra ...
Monthly notices of the Royal Astronomical Society,
08/2019, Letnik:
489, Številka:
2
Journal Article
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GRB 160821B is a short duration gamma-ray burst (GRB) detected and localized by the Neil Gehrels Swift Observatory in the outskirts of a spiral galaxy at z = 0.1613, at a projected physical offset of ...16 kpc from the galaxy’s center. We present X-ray, optical/nIR, and radio observations of its counterpart and model them with two distinct components of emission: a standard afterglow, arising from the interaction of the relativistic jet with the surrounding medium, and a kilonova, powered by the radioactive decay of the sub-relativistic ejecta. Broadband modelling of the afterglow data reveals a weak reverse shock propagating backward into the jet, and a likely jet-break at 3.5 d. This is consistent with a structured jet seen slightly off-axis (θview ∼ θcore) while expanding into a low-density medium (n ≈ 10−3 cm−3). Analysis of the kilonova properties suggests a rapid evolution towards red colours, similar toAT2017gfo, and a low-nIR luminosity, possibly due to the presence of a long-lived neutron star. The global properties of the environment, the inferred low mass (Mej <~ 0.006 Msun) and velocities (vej >~ 0.05c) of lanthanide-rich ejecta are consistent with a binary neutron star merger progenitor.
The present study aims to evaluate plastic deformation's effect by cold-rolling on the precipitation sequence of 2024 aluminum alloy. X-ray diffraction, scanning/transmission electron microscopy, and ...Vickers microhardness tests have been used to characterize the microstructure and mechanical behavior of the alloys. It was observed that plastic deformation induces changes in the precipitation sequence, which affects the mechanical properties and delays the overaging stage. In the deformed alloy, two hardening peaks were observed. These peaks occurred at 30 min (248 HV ± 5) and 600 min (230 HV ± 2) and were attributed to the θ' and S' phases, respectively. However, in the non-deformed alloy, only a single hardening peak was observed. This peak arose after 300 min aging (208 HV ± 4) and was attributed to the S' phase formation. Thus, the precipitation sequence in the deformed alloy was the following: αSSS–CuMg clusters → GPB-II zones/θ''/θ'/ → S' → S, and for the non-deformed alloy was αSSS–CuMg clusters → GPB-II zones/S'/ → S.
Graphical abstract
Aims
The biostimulant effect of Trichoderma spp. on horticultural crops are highly variable. Thus, practical use of Trichoderma sp. requires feasible formulated products and suitable substrates.
...Methods and Results
This study evaluates the survival and the growth‐promotion effect of a Trichoderma saturnisporum rice formulation compared with a nonformulated conidia suspension (seven treatments in total), on tomato, pepper and cucumber seedlings grown in two substrates: (i) rich in organic matter (OM) and (ii) mineral substrate without OM. The results showed beneficial effects on seedling growth in the OM‐rich substrate when T. saturnisporum rice formulation (mainly at maximum concentration) was applied, but the effects were opposite when the mineral substrate without OM was used. The effects were closely linked to the level of inoculum in the substrate, which was greater upon application of the formulated inoculum as opposed to the nonformulated one.
Conclusions
The use of rice to prepare the inoculum of T. saturnisporum seems to be promising for seedling growth in the nursery when it is applied in a substrate that is rich in organic matter, but it must be considered that under certain conditions of food shortage, Trichoderma sp. could show pathogenicity to seedlings.
Significance and Impact of the Study
This study provides evidence of the complexity inherent in the use of micro‐organisms in agriculture, while also confirming that the activity of the biofertilizers based on Trichoderma depends on the type of inoculum and its concentration, as well as the properties of the medium in which the fungi develop. Further studies assessing the effectiveness or possible pathogenicity of Trichoderma in different soils under greenhouse conditions must be addressed.
Additions of 1–2 Ni (wt. %) and hot deformation on the microstructure and hardness of A356 aged alloy were studied. The results show that the addition of this element generates the formation of ...Ni31Si12 and NiFe phases with high thermal stability. In addition, the presence of Ni into the Al matrix and precipitates of the second phase affect the precipitation kinetics, transformation sequence, growth rate, and slow loss of hardness in the system after reaching the maximum values. For example, the Ni additions contribute to generating the coexistence of β" precipitate and GP-I zones. Of all the strengthening mechanisms present, hardening by precipitation is the most influential in the hardness.
•Plastic deformations alter the precipitation kinetic.•Ni contribute to generating the coexistence of β" precipitate and GP-I zones.•Ni promotes high thermal stability on second phase precipitates.•Hardening by precipitation is the most influential in the hardness.•Ni promotes a slow loss of hardness after reaching the maximum hardness values.
Wave loading on marine structures is the major external force to be considered in the design of such structures. The accurate prediction of the nonlinear high-order components of the wave loading has ...been an unresolved challenging problem. In this paper, the nonlinear harmonic components of hydrodynamic forces on a bottom-mounted vertical cylinder are investigated experimentally. A large number of experiments were conducted in the Danish Hydraulic Institute shallow water wave basin on the cylinder, both on a flat bed and a sloping bed, as part of a European collaborative research project. High-quality data sets for focused wave groups have been collected for a wide range of wave conditions. The high-order harmonic force components are separated by applying the ‘phase-inversion’ method to the measured force time histories for a crest focused wave group and the same wave group inverted. This separation method is found to work well even for locally violent nearly-breaking waves formed from bidirectional wave pairs. It is also found that the
$n$
th-harmonic force scales with the
$n$
th power of the envelope of both the linear undisturbed free-surface elevation and the linear force component in both time variation and amplitude. This allows estimation of the higher-order harmonic shapes and time histories from knowledge of the linear component alone. The experiments also show that the harmonic structure of the wave loading on the cylinder is virtually unaltered by the introduction of a sloping bed, depending only on the local wave properties at the cylinder. Furthermore, our new experimental results reveal that for certain wave cases the linear loading is actually less than 40 % of the total wave loading and the high-order harmonics contribute more than 60 % of the loading. The significance of this striking new result is that it reveals the importance of high-order nonlinear wave loading on offshore structures and means that such loading should be considered in their design.
The plastic deformation effect on activation energy, transformed volume fraction, and Avrami exponent for the phase precipitation in a 2024 aluminum alloy was evaluated in this study. Differential ...scanning calorimetry characterization was carried out in deformed and non-deformed samples, focusing on the study of S phase precipitation (Al2CuMg precipitates with orthorhombic structure, space group Cmcm, and lattice parameters a = 4.03 Å, b = 9.3 Å, c = 7.08 Å). The results show that the solid-state reactions were activated, kinetically controlled, and modified by the plastic deformation. The enthalpy changes, activation energy, and peak temperature shifting confirm that the applied deformation alters the reaction sequence. Two different Avrami exponent values were found, one close to 1.7, which indicates that nucleation occurs in preexisting nucleation sites, and the other near 1.3, which corresponds to phase transformation driven by diffusion mechanisms.
•The S-phase precipitation was thermally activated and kinetically controlled.•%ε modify the ΔH, Tp, and Q but does not affect the precipitation sequence.•Avrami exponent ~1.7 indicated that nucleation occurs in preexisting sites.•Avrami exponent ~1.3 showed that phase transformation is driven by diffusion.
Variable x-ray and γ-ray emission is characteristic of the most extreme physical processes in the universe. We present multiwavelength observations of a unique γ-ray—selected transient detected by ...the Swift satellite, accompanied by bright emission across the electromagnetic spectrum, and whose properties are unlike any previously observed source. We pinpoint the event to the center of a small, star-forming galaxy at redshift z = 0.3534. Its high-energy emission has lasted much longer than any γ-ray burst, whereas its peak luminosity was ∼100 times higher than bright active galactic nuclei. The association of the outburst with the center of its host galaxy suggests that this phenomenon has its origin in a rare mechanism involving the massive black hole in the nucleus of that galaxy.
DG Canum Venaticorum (DG CVn) is a binary system in which one of the components is an M-type dwarf ultrafast rotator, only three of which are known in the solar neighbourhood. Observations of DG CVn ...by the Swift satellite and several ground-based observatories during its superflare event on 2014 allowed us to perform a complete hard X-ray–optical follow-up of a superflare from the red-dwarf star. The observations support the fact that the superflare can be explained by the presence of (a) large active region(s) on the surface of the star. Such activity is similar to the most extreme solar flaring events. This points towards a plausible extrapolation between the behaviour from the most active red-dwarf stars and the processes occurring in the Sun.
Fusarium wilts are economically important diseases for which there are no effective chemical control measures. However, biological control and fertility management are becoming efficient alternatives ...for controlling this disease. Growth media formulated with composts that are able to suppress Fusarium wilt of tomato provide a control system that integrates both strategies. The aim of this study was to predict Fusarium wilt suppression of growth media using abiotic and biotic variables. Grape marc compost was the most effective medium used to suppress Fusarium wilt. Cork compost was intermediate, and light peat and expanded vermiculite were the most conducive growth media. The growth media evaluated were in a pH range of 6.26 to 7.97. Both composts had high beta-glucosidase activity. When pH and beta-glucosidase activity were taken into account as predictive variables, more than 91% of the variation in severity of Fusarium wilt was explained. This relationship illustrates the effect of nutrient availability and the degree of microbiostasis, two key factors in this pathosystem. Microbial populations involved in suppressiveness were cellulolytic and oligotrophic actinomycetes, fungi, and the ratios cellulolytic actinomycetes/cellulolytic bacteria, oligotrophic bacteria/copiotrophic bacteria, and oligotrophic actinomycetes/oligotrophic bacteria. Based on community level physiological profiles, different community structures were evident among growth media evaluated.
The presence of deleterious Al4C3 phase has been for long a major challenge in the manufacture of Al matrix composites reinforced with carbide phases. In this contribution, the hydrophilic Al4C3 ...phase has been successfully eliminated from the surface of B4C/Al composites prepared by pressureless infiltration, using a post-processing approach by the hybrid system chemical vapor deposition (HYSY-CVD) route. B4C/Al composites containing intentionally formed Al4C3 were first prepared by pressureless infiltration and subsequently treated by HYSY-CVD, varying temperature (400 and 500°C), time (30 and 60min) and amount of solid precursor Na2SiF6 (10 and 20g). In conformity with reaction thermodynamic predictions using the HSC 6.1® and FactSage® programs and databases, analysis by XRD and SEM confirms the superficial elimination of Al4C3 and the seedless formation of passivating AlF3 and Na5Al3F14. Optimal conditions to maximize the amount of AlF3 deposited were established by ANOVA and the effectiveness of the fluoride phases was evaluated in hardness and corrosion tests, confirming the stability of fluoride phases and the integrity of the composites. Microstructure characterization and hardness tests of specimens after three years substantiate the efficacy of AlF3 and Na5Al3F14 phases. A hydrophobic and impermeable fluoride coating multiphase layer is thus obtained.
Microstructure evolution of B4C/Al composites before and after post-processing. Display omitted
•The hygroscopic and deleterious Al4C3 phase was successfully eliminated by a post-processing approach.•A hydrophobic and impermeable fluoride coating multiphase layer is deposited on the composites.•The stability of fluoride phases and the integrity of the composites are confirmed.•Optimal conditions to maximize the amount of AlF3 deposited were established.
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