Background
A ductile material, such as a polymeric material, releases energy during deformation. The dissipated energy can be evaluated as entropy generation. If the thermodynamic entropy generation ...can be measured, the stress state can be evaluated by the thermodynamic entropy generation.
Objective
In this study, the thermodynamic entropy generation of Polyamide 6 (PA6) was obtained using differential scanning calorimetry (DSC) for a material subjected to arbitrary strain.
Methods
Thermodynamic entropies were measured at the beginning and at each strain state of tensile tests by using DSC, and the volumetric strain was measured with Digital Image Correlation Method.
Results
At the 25% strain just before the necking behavior, the volumetric strain of PA6 was ~4.8%, and the entropy was ~56 kJ/K∙m
3
. Furthermore, the thermodynamic entropy generation of PA6 in carbon fiber reinforced plastics was evaluated under tensile conditions. The results showed that the thermodynamic entropy generation just before the transverse cracking (as same as necking in matrix resin) was ~69 kJ/K∙m
3
and the volumetric strain of PA6 in composite was ~ 3.56 %. As the results, the entropy generation and volumetric strain of PA6 showed almost same values in pure PA6 and PA6 in composite.
Conclusions
Consequently, thermodynamic entropy generation can be measured the volumetric strain of matrix resin.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The effects of rhenium (Re) addition on deuterium (D) retention in neutron-irradiated tungsten (W) were investigated. Pure W and W-5Re (5 at.%) alloy samples were irradiated with neutrons at High ...Flux Isotope Reactor using MFE-RB-19 J capsule. The sample temperature and the damage level were 864 K and 0.35 dpa for pure W and 792 K and 0.26 dpa for W-5Re alloy. A portion of the samples was exposed to D plasma at Tritium Plasma Experiment at Idaho National Laboratory at 823 K to a fluence of 5 × 1025m−2. Vacancy-type defects in neutron-irradiated samples were examined using positron annihilation spectroscopy (PAS); D retention after plasma exposure was evaluated by thermal desorption spectrometry (TDS).
TDS measurements revealed that D retention in the neutron-irradiated W-5Re alloy was similar to that in the unirradiated W sample, whereas a significant increase in D retention was observed in neutron-irradiated W. Thus, Re addition significantly suppressed the increase in D retention after neutron irradiation. This effect was attributed to the suppression of vacancy-type defect formation, as confirmed by PAS.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Context. Hot corinos are extremely rich in complex organic molecules (COMs). Accurate abundance measurements of COMs in such objects are crucial to constrain astrochemical models. In the particular ...case of close binary systems this can only be achieved through high angular resolution imaging. Aims. We aim to perform an interferometric study of multiple COMs in NGC 1333 IRAS 4A, which is a protostellar binary hosting hot corino activity, at an angular resolution that is sufficient to distinguish easily the emission from the two cores separated by 1.8′′. Methods. We used the Atacama Large (sub-)Millimeter Array (ALMA) in its 1.2 mm band and the IRAM Plateau de Bure Interferometer (PdBI) at 2.7 mm to image, with an angular resolution of 0.5′′ (120 au) and 1′′ (235 au), respectively, the emission from 11 different organic molecules in IRAS 4A. This allowed us to clearly disentangle A1 and A2, the two protostellar cores. For the first time, we were able to derive the column densities and fractional abundances simultaneously for the two objects, allowing us to analyse the chemical differences between them. Results. Molecular emission from organic molecules is concentrated exclusively in A2, while A1 appears completely devoid of COMs or even simpler organic molecules, such as HNCO, even though A1 is the strongest continuum emitter. The protostellar core A2 displays typical hot corino abundances and its deconvolved size is 70 au. In contrast, the upper limits we placed on COM abundances for A1 are extremely low, lying about one order of magnitude below prestellar values. The difference in the amount of COMs present in A1 and A2 ranges between one and two orders of magnitude. Our results suggest that the optical depth of dust emission at these wavelengths is unlikely to be sufficiently high to completely hide a hot corino in A1 similar in size to that in A2. Thus, the significant contrast in molecular richness found between the two sources is most probably real. We estimate that the size of a hypothetical hot corino in A1 should be less than 12 au. Conclusions. Our results favour a scenario in which the protostar in A2 is either more massive and/or subject to a higher accretion rate than A1, as a result of inhomogeneous fragmentation of the parental molecular clump. This naturally explains the smaller current envelope mass in A2 with respect to A1 along with its molecular richness. The extremely low abundances of organic molecules in A1 with respect to those in A2 demonstrate that the dense inner regions of a young protostellar core lacking hot corino activity may be poorer in COMs than the outer protostellar envelope.
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FMFMET, NUK, UL, UM, UPUK
Submillimetre and millimetre line and continuum observations are important in probing the morphology, column density, and dynamics of the molecular gas and dust around obscured active galactic nuclei ...(AGNs) and their mechanical feedback. With very high-resolution (0.″02 × 0.″03 (2 × 3 pc)) ALMA 345 GHz observations of CO 3–2, HCO
+
4–3, vibrationally excited HCN 4–3
ν
2
= 1
f
, and continuum we have studied the remarkable, extremely radio-quiet, molecular jet and wind of the lenticular galaxy NGC 1377. The outflow structure is resolved, revealing a 150 pc long, clumpy, high-velocity (∼600 km s
−1
), collimated molecular jet where the molecular emission is emerging from the spine of the jet with an average diameter of 3–7 pc. The jet widens to 10–15 pc about 25 pc from the centre, which is possibly due to jet-wind interactions. A narrow-angle (50°–70°), misaligned and rotating molecular wind surrounds the jet, and both are enveloped by a larger-scale CO-emitting structure at near-systemic velocity. The jet and narrow wind have steep radial gas excitation gradients and appear turbulent with high gas dispersion (
σ
> 40 km s
−1
). The jet shows velocity reversals that we propose are caused by precession, or more episodic directional changes. We discuss the mechanisms powering the outflow, and we find that an important process for the molecular jet and narrow wind is likely magneto-centrifugal driving. In contrast, the large-scale CO-envelope may be a slow wind, or cocoon that stems from jet-wind interactions. An asymmetric, nuclear
r
∼ 2 pc dust structure with a high inferred molecular column density
N
(H
2
) ≃1.8 × 10
24
cm
−2
is detected in continuum and also shows compact emission from vibrationally excited HCN. The nuclear dust emission is hot (
T
d
> 180 K) and its luminosity is likely powered by a buried AGN. The lopsided structure appears to be a warped disk, which is responsible for a significant part of the nuclear obscuration and possibly formed as a result of uneven gas inflows. The dynamical mass inside
r
= 1.4 pc is estimated to 9
−3
+2
× 10
6
M
⊙
, implying that the supermassive black hole (SMBH) has a high mass with respect to the stellar velocity dispersion of NGC 1377. We suggest that the SMBH of NGC 1377 is currently in a state of moderate growth, at the end of a more intense phase of accretion and also evolving from a state of more extreme nuclear obscuration. The nuclear growth may be fuelled by low-angular momentum gas inflowing from the gas ejected in the molecular jet and wind. Such a feedback-loop of cyclic outflows and central accretion could explain why there is still a significant reservoir of molecular gas in this ageing, lenticular galaxy. A feedback-loop would be an effective process in growing the nuclear SMBH and thus would constitute an important phase in the evolution of NGC 1377. This also invites new questions as to SMBH growth processes in obscured, dusty galaxies.
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FMFMET, NUK, UL, UM, UPUK
Abstract
Complex organic molecules have been observed for decades in the interstellar medium. Some of them might be considered as small bricks of the macromolecules at the base of terrestrial life. ...It is hence particularly important to understand organic chemistry in Solar-like star-forming regions. In this article, we present a new observational project: Seeds Of Life In Space (SOLIS). This is a Large Project using the IRAM-NOEMA interferometer, and its scope is to image the emission of several crucial organic molecules in a sample of Solar-like star-forming regions in different evolutionary stages and environments. Here we report the first SOLIS results, obtained from analyzing the spectra of different regions of the Class 0 source NGC 1333-IRAS4A, the protocluster OMC-2 FIR4, and the shock site L1157-B1. The different regions were identified based on the images of formamide (NH
2
CHO) and cyanodiacetylene (HC
5
N) lines. We discuss the observed large diversity in the molecular and organic content, both on large (3000–10,000 au) and relatively small (300–1000 au) scales. Finally, we derive upper limits to the methoxy fractional abundance in the three observed regions of the same order of magnitude of that measured in a few cold prestellar objects, namely
–10
−11
with respect to H
2
molecules.
ABSTRACT
The ALMA (Atacama Large Millimeter Array) interferometer, with its unprecedented combination of high sensitivity and high angular resolution, allows for (sub-)mm wavelength mapping of ...protostellar systems at Solar system scales. Astrochemistry has benefitted from imaging interstellar complex organic molecules in these jet–disc systems. Here, we report the first detection of methanol (CH3OH) and methyl formate (HCOOCH3) emission towards the triple protostellar system VLA1623−2417 A1+A2+B, obtained in the context of the ALMA Large Programme FAUST (Fifty AU STudy of the chemistry in the disc/envelope system of solar-like protostars). Compact methanol emission is detected in lines from Eu = 45 K up to 61 K and 537 K towards components A1 and B, respectively. Large velocity gradient analysis of the CH3OH lines towards VLA1623−2417 B indicates a size of 0.11–0.34 arcsec (14–45 au), a column density $N_{\rm CH_3OH}$ = 1016–1017 cm−2, kinetic temperature ≥ 170 K, and volume density ≥ 108 cm−3. A local thermodynamic equilibrium approach is used for VLA1623−2417 A1, given the limited Eu range, and yields Trot ≤ 135 K. The methanol emission around both VLA1623−2417 A1 and B shows velocity gradients along the main axis of each disc. Although the axial geometry of the two discs is similar, the observed velocity gradients are reversed. The CH3OH spectra from B show two broad (4–5 km s−1) peaks, which are red- and blueshifted by ∼ 6–7 km s−1 from the systemic velocity. Assuming a chemically enriched ring within the accretion disc, close to the centrifugal barrier, its radius is calculated to be 33 au. The methanol spectra towards A1 are somewhat narrower (∼ 4 km s−1), implying a radius of 12–24 au.
In this study, surface helium (He) effect on hydrogen isotopes diffusion and trapping/detrapping behavior was modelled and integrated into the HIDT simulation code. Effective dynamics properties of ...hydrogen in tungsten including diffusivity, solubility, recycling and diffusion barrier were considered to reflect the influence of He bubbles. Simulation results showed that total hydrogen retention was reduced with the existence of He bubbles near surface, which was consistent with the reported laboratory experimental results. It was found that the most significant influence came from the diffusion barrier induced by He bubbles. With increasing the barrier factor, total hydrogen retention changed from the tendency of decrease to increase. When the barrier factor was less than 0.3, hydrogen desorption from the implantation surface was dominant, while that from the backside surface became dominant when the barrier factor was greater than 0.4. In the meanwhile, more hydrogen accumulated beyond the He bubble layer was observed. These hydrogen atoms occupied not only in trapping sites, but also in lattice sites. Based on these findings, three desorption stages, namely surface desorption, major desorption and backside desorption, could characterize the TDS spectra with different mechanisms. In addition, our findings were further substantiated by the reported experimental data. This study provides a new perspective to reveal the surface He effect on hydrogen isotopes retention behavior in plasma facing materials.
•Effective dynamics properties were considered to express the influence of He bubbles on hydrogen migration behavior.•Total hydrogen retention was reduced with the existence of He bubbles near surface.•Three desorption stages can characterize the TDS spectra with different mechanisms.•Diffusion barrier induced by He bubbles showed significant influence on the desorption process.•With increasing the barrier factor, total hydrogen retention changed from the tendency of decrease to increase.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study, energetic helium (He) ion irradiation was performed to obtain bulk He distribution in tungsten (W) materials, concurrent with damage introduction at high temperature. Then, deuterium ...(D) implantation and thermal desorption spectrometry were performed to evaluate D retention. At the same time, the surface tritium (T) concentration and depth distribution were evaluated by imaging plate (IP) and β-ray induced X-ray spectroscopy (BIXS) measurements after mixed D-T gas exposure. Numerical simulations were applied to evaluate changes in binding energies, diffusion depths, and trapping sites under different irradiation conditions. The results showed that weak trapping sites with higher concentration, such as vacancies, were produced during only energetic He+ irradiation events, leading to enhancement of D retention. Fe3+-He+ simultaneous irradiation promoted the formation of HexVy complexes, which reduced the concentration of vacancy trapping sites and changed the stress field around defects, leading to the suppression of D trapping behavior. From the reduced effects of D retention caused by HexVy complexes at higher temperatures, the results suggested that defect recovery was the dominant mechanism. With increasing damage level at higher temperatures, more weak trapping sites, such as dislocations and vacancies sites, were produced, leading to a more dominant influence on D retention than HexVy complex effects. It was also found that HexVy complexes prevented D diffusion to the bulk and that simulation results showed that the damage level had little impact on D diffusion depth.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Tungsten samples were irradiated by neutrons in the High Flux Isotope Reactor (HFIR), Oak Ridge National Laboratory at reactor coolant temperatures of 50-70 °C to low displacement damage of 0.025 and ...0.3 dpa. After cooling down, the HFIR neutron-irradiated tungsten samples were exposed to deuterium plasmas in the Tritium Plasma Experiment, Idaho National Laboratory at 100, 200 and 500 °C twice at the ion fluence of 5 × 1025 m−2 to reach the total ion fluence of 1 × 1026 m−2 in order to investigate the near-surface deuterium retention and saturation via nuclear reaction analysis. Final thermal desorption spectroscopy was performed to elucidate the irradiation effect on total deuterium retention. Nuclear reaction analysis results showed that the maximum near-surface (<5 µm depth) deuterium concentration increased from 0.5 at% D/W in 0.025 dpa samples to 0.8 at% D/W in 0.3 dpa samples. The large discrepancy between the total retention via thermal desorption spectroscopy and the near-surface retention via nuclear reaction analysis indicated the deuterium was trapped in bulk (at least 50 µm depth for 0.025 dpa and 35 µm depth for 0.3 dpa) at 500 °C cases even in the relatively low ion fluence of 1026 m−2.
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