thermal dependence
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Author(s):  
Guilherme Gomide ◽  
Rafael Cabreira Gomes ◽  
Márcio Gomes Viana ◽  
Alex Fabiano Cortez Campos ◽  
Renata Aquino ◽  
...  

2021 ◽  
Vol 923 (2) ◽  
pp. 201
Author(s):  
Oliver Eggenberger Andersen ◽  
Shuai Zha ◽  
André da Silva Schneider ◽  
Aurore Betranhandy ◽  
Sean M. Couch ◽  
...  

Abstract Gravitational waves (GWs) provide unobscured insight into the birthplace of neutron stars and black holes in core-collapse supernovae (CCSNe). The nuclear equation of state (EOS) describing these dense environments is yet uncertain, and variations in its prescription affect the proto−neutron star (PNS) and the post-bounce dynamics in CCSN simulations, subsequently impacting the GW emission. We perform axisymmetric simulations of CCSNe with Skyrme-type EOSs to study how the GW signal and PNS convection zone are impacted by two experimentally accessible EOS parameters, (1) the effective mass of nucleons, m ⋆, which is crucial in setting the thermal dependence of the EOS, and (2) the isoscalar incompressibility modulus, K sat. While K sat shows little impact, the peak frequency of the GWs has a strong effective mass dependence due to faster contraction of the PNS for higher values of m ⋆ owing to a decreased thermal pressure. These more compact PNSs also exhibit more neutrino heating, which drives earlier explosions and correlates with the GW amplitude via accretion plumes striking the PNS, exciting the oscillations. We investigate the spatial origin of the GWs and show the agreement between a frequency-radial distribution of the GW emission and a perturbation analysis. We do not rule out overshoot from below via PNS convection as another moderately strong excitation mechanism in our simulations. We also study the combined effect of effective mass and rotation. In all our simulations we find evidence for a power gap near ∼1250 Hz; we investigate its origin and report its EOS dependence.


2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Lorena de Oliveira Felipe ◽  
Juliano Lemos Bicas ◽  
Meryem Bouhoute ◽  
Mitsutoshi Nakajima ◽  
Marcos A. Neves

AbstractIn this study, the interfacial ability of α-terpineol (α-TOH) was reported, followed by its trapping into oil-in-water (O/W) nanoemulsion as active-ingredient and the long-term observation of this nanosystem influenced by the storage-time (410-days) and temperature (5, 25, 50 °C). The results indicated that the α-TOH can reduce the interfacial tension on the liquid-liquid interface (ΔG°m = −1.81 KJ mol−1; surface density = 8.19 × 10−6 mol m−2; polar head group area = 20.29 Å2), in the absence or presence of surfactant. The O/W nanoemulsion loaded with a high amount of α-TOH (90 mg mL−1; 9α-TOH-NE) into the oil phase was successfully formulated. Among the physical parameters, the mean droplet diameter (MDD) showed a great thermal dependence influenced by the storage-temperature, where the Ostwald ripening (OR) was identified as the main destabilizing phenomena that was taking place on 9α-TOH-NE at 5 and 25 °C along with time. Despite of the physical instability, the integrity of both nanoemulsion at 5 °C and 25 °C was fully preserved up to 410th day, displaying a homogeneous and comparable appearance by visual observation. On contrary, a non-thermal dependence was found for chemical stability, where over 88% of the initial amount of the α-TOH nanoemulsified remained in both 9α-TOH-NE at 5 and 25 °C, up to 410th day. Beyond the key data reported for α-TOH, the importance of this research relies on the long-term tracking of a nanostructured system which can be useful for scientific community as a model for a robust evaluation of nanoemulsion loaded with flavor oils.


Author(s):  
Pablo Fuentealba ◽  
Danae Villagra ◽  
Yolimar Gil ◽  
Héctor Aguilar-Bolados ◽  
Ricardo Costa de Santana ◽  
...  

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1836
Author(s):  
Rachid Traiche ◽  
Hassane Oubouchou ◽  
Kamel Boukheddaden

Among the large family of spin-crossover materials, binuclear systems play an important role due to their specific molecular configurations, allowing the presence of multi-step transitions and elastic frustration. Although this issue benefited from a significant number of spin-based theories, there is almost no elastic description of the spin transition phenomenon in binuclear systems. To overcome this deficiency, in this work we develop the first elastic modeling of thermal properties of binuclear spin-crossover solids. At this end, we investigated a finite spin-crossover open chain constituted of elastically coupled binuclear (A = B) blocks, ⋯A=B−A=B−A=B⋯, in which the considered equivalent A and B sites may occupy two configurations, namely low-spin (LS) and high-spin (HS) states. The sites of the binuclear unit interact via an intramolecular spring and couple to the neighboring binuclear units via other springs. The model also includes the change of length inside and between the binuclear units subsequent to the spin state changes. When injecting an elastic frustration inside the binuclear unit in the LS state, competing interactions between the intra- and the inter-binuclear couplings emerge. The latter shows that according to the intra- and inter-binuclear elastic constants and the strength of the frustration, multi-step transitions are derived, for which a specific self-organization of type (HS = HS)-(LS-LS)-(HS = HS)⋯ is revealed and discussed. Finally, we have also studied the relaxation of the metastable photoinduced HS states at low temperature, in which two relaxation regimes with transient self-organized states were identified when monitoring the elastic frustration rate or the ratio of intra- and intermolecular elastic interactions. These behaviors are reminiscent of the thermal dependence of the order parameters of the system. The present model opens several possibilities of extensions of elastic frustrations acting in polynuclear spin-crossover systems, which may lead to other types of spin-state self-organizations and relaxation dynamics.


2021 ◽  
Vol 12 ◽  
Author(s):  
Marco J. Cabrerizo ◽  
Emilio Marañón

Grazing pressure, estimated as the ratio between microzooplankton grazing and phytoplankton growth rates (g:μ), is a strong determinant of microbial food-web structure and element cycling in the upper ocean. It is generally accepted that g is more sensitive to temperature than μ, but it remains unknown how the thermal dependence (activation energy, Ea) of g:μ varies over spatial and temporal scales. To tackle this uncertainty, we used an extensive literature analysis obtaining 751 paired rate estimates of μ and g from dilution experiments performed throughout the world’s marine environments. On a geographical scale, we found a stimulatory effect of temperature in polar open-ocean (∼0.5 eV) and tropical coastal (∼0.2 eV) regions, and an inhibitory one in the remaining biomes (values between −0.1 and −0.4 eV). On a seasonal scale, the temperature effect on g:μ ratios was stimulatory, particularly in polar environments; however, the large variability existing between estimates resulted in non-significant differences among biomes. We observed that increases in nitrate availability stimulated the temperature dependence of grazing pressure (i.e., led to more positive Ea of g:μ) in open-ocean ecosystems and inhibited it in coastal ones, particularly in polar environments. The percentage of primary production grazed by microzooplankton (∼56%) was similar in all regions. Our results suggest that warming of surface ocean waters could exert a highly variable impact, in terms of both magnitude and direction (stimulation or inhibition), on microzooplankton grazing pressure in different ocean regions.


2021 ◽  
Author(s):  
Upendra Kumar ◽  
Ram Sundar Maurya ◽  
Harshpreet Cheema ◽  
Vedika Yadav ◽  
Aditya Kumar ◽  
...  

Abstract The conventional ceramic route has been used to prepare the La-doped Ba2SnO4 samples by heat-treatment at 1000oC and sintered at 1250oC. The phase identification was carried out using XRD and found to be single phase up to 4 atoms %. The solubility of La at Ba-site were further reconfirmed using FTIR and Raman analysis. The AC conductivity spectra of all samples follow universal Johnscher’s power law; however, the thermal dependence of suggest Arrhenius type conduction within the sample. Further, the scaled conductivity and frequency at all temperatures superimposes on a single master curve, indicates the invariance of conduction mechanism. The impedance spectroscopy studies suggest the major contribution of grain in the conduction and relaxation. The present material could be potentially used in semiconductor device, UV-detector, and mixed ionic and electronic conductor (MIECs) by utilizing absorption states and thermo-curves as metastable state.


2021 ◽  
Author(s):  
Harshpreet Cheema ◽  
Vedika Yadav ◽  
Ram Sundar Maurya ◽  
Varsha Yadav ◽  
Aditya Kumar ◽  
...  

Abstract Samples with doping of Mn (0, 2, and 4%) in ZnFe2O4 were prepared by sol-gel chemical route at 80oC. X-ray powder diffraction and Raman spectrum analysis were used to determine the preliminary phase of obtained samples. W-H and SSP plots were used to determine the crystallite size and micro-strain of samples. Using zeta potential and scanning electron microscope, the surface charge and morphology of the prepared samples were studied. The optical bandgap of sample suggested that it was semiconducting. The dielectric characteristics of samples were examined as a function of temperature at various frequencies (1 KHz, 10 KHz, 100 KHz, and 1 MHz) (60-600oC). Dielectric study revealed the presence of interfacial and orientational polarization, with dielectric constants and dissipation factors ranging from (0.7–460) to (0.3–0.8), remain thermally stability up to 300oC. In samples ZF-0, ZF-2, and ZF-4, the thermal dependence of DC conductivity demonstrates Arrhenius transport with one, two, and three regions of conduction, respectively. The sources of charge carrier in samples were Vo,e1 defects (Vo - 2FE2+ Fe3+') and (2M3+ Zn2+ - 2FE2+ Fe3+'). The current work could help identify possible applications in semiconductor devices, thermally stable capacitors, and as mixed ionic electronic conductors in solid oxide fuel cells.


2021 ◽  
Author(s):  
Juan Manuel González-Olalla ◽  
Juan Manuel Medina-Sánchez ◽  
Presentación Carrillo

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