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A bstract Heavy quarks placed within a hot QCD medium undergo Brownian motion, characterized by specific transport coefficients. Their determination can be simplified by expanding them in T/M , where T is the temperature and M is a heavy quark mass. The leading term in the expansion originates from the colour-electric part of a Lorentz force, whereas the next-to-leading order involves the colour-magnetic part. We measure a colour-magnetic 2-point correlator in quenched QCD at T ∼ (1 . 2 − 2 . 0) T c . Employing multilevel techniques and non-perturbative renormalization, a good signal is obtained, and its continuum extrapolation can be estimated. Modelling the shape of the corresponding spectral function, we subsequently extract the momentum diffusion coefficient, κ . For charm (bottom) quarks, the magnetic contribution adds ∼ 30% (10%) to the electric one. The same increases apply also to the drag coefficient, η . As an aside, the colour-magnetic spectral function is computed at NLO.

We provide a simple proof of a Voronoi type identity using the Laplace transform for a class of arithmetical functions whose generating Dirichlet series satisfy a functional equation with gamma factors. As an application, we derivea Voronoi-type identity for Gaussian integers.

The current understanding of room temperature microplasticity in α/β titanium alloys is reviewed with a special emphasis on dual-phase engineering alloys. As the interplay between microstructure and deformation mechanisms governs both the microscale and macroscale mechanical response, a brief description of the main features of α/β microstructures is first provided. Elastic and plastic deformation in individual phases is then described. The complex interactions that govern the effect of grain boundaries, phase interfaces and microtexture on deformation behaviour are reviewed. Crystal plasticity simulations have evolved over the past decade as a key technique to obtain a mechanistic understanding of the deformation of Ti alloys. Micromechanical aspects are emphasized with a discussion of input parameters required to achieve realistic constitutive modeling. As microplasticity is especially relevant in cyclic loading such as experienced in-service by components, the current understanding of the relation of this regime with fatigue and dwell-fatigue behavior is briefly summarized in the final section.

This study presents the synthesis of a pectin biopolymer through an acidic extraction process from natural sources and the development of a conducting electrolyte film with enhanced conductivity via sodium azide reinforcement into it. The pure and modified self-standing polymer films were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and polarized optical microscopy (POM). XRD analysis confirmed proper phase formation and revealed a monotonic reduction in polymer crystallinity with increasing salt content, which was further supported by POM micrographs. FTIR analysis verified the presence of organic functional groups, showing no significant changes in vibrational energy levels upon salt incorporation. Electrochemical characterization using cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy demonstrated that the strong interaction between sodium azide and the pectin biopolymer significantly enhanced ionic conductivity and stability. It has been shown that upon optimized salt incorporation conductivity of the polymer got enhanced almost four orders. These findings underscore the potential of sodium azide-reinforced pectin films as a viable material for advanced energy storage and conversion devices, offering a promising pathway for future applications in electrochemical systems.

High spatial resolution is needed to study the early development of a nova; here measurements of the angular size and radial velocity of Nova Delphini 2013 reveal early structures in the ejected material and a geometric distance to the nova of about 4.5 kiloparsecs from the Sun. Early observations of the classical Nova Del 2013 Nova Del 2013 is a bright 'naked-eye' nova that erupted from a white dwarf in the constellation of Delphini on 14 August 2013. Gail Schaefer et al . report near-infrared interferometric measurements of the angular expansion of Nova Del 2013 starting from one day after the explosion, with extensive coverage over the first two months. In addition, the authors present reconstructed images of the nova during the first week after detonation. Changes in the apparent expansion rate can be explained by a model consisting of an optically thick core surrounded by a diffuse envelope, and ellipticity in the light distribution suggests a prolate or bipolar structure from as early as the second day. These findings — together with spectra obtained by another group — suggests that novae explosions might be inherently bipolar or that the elliptical shape develops early through interactions with a binary companion at a time when they still share common envelope. A classical nova occurs when material accreting onto the surface of a white dwarf in a close binary system ignites in a thermonuclear runaway 1 , 2 . Complex structures observed in the ejecta at late stages 3 , 4 , 5 could result from interactions with the companion during the common-envelope phase 6 , 7 . Alternatively, the explosion could be intrinsically bipolar, resulting from a localized ignition on the surface of the white dwarf 8 or as a consequence of rotational distortion 9 , 10 . Studying the structure of novae during the earliest phases is challenging because of the high spatial resolution needed to measure their small sizes 11 . Here we report near-infrared interferometric measurements of the angular size of Nova Delphini 2013, starting one day after the explosion and continuing with extensive time coverage during the first 43 days. Changes in the apparent expansion rate can be explained by an explosion model consisting of an optically thick core surrounded by a diffuse envelope. The optical depth of the ejected material changes as it expands. We detect an ellipticity in the light distribution, suggesting a prolate or bipolar structure that develops as early as the second day. Combining the angular expansion rate with radial velocity measurements, we derive a geometric distance to the nova of 4.54 ± 0.59 kiloparsecs from the Sun.

Propagating slow magnetoacoustic waves are commonly observed in different coronal structures but are most prominent in active region fan loops. Their rapid damping with damping lengths of the order of a wavelength has been investigated in the past by several authors. Although different physical mechanisms have been proposed, significant discrepancies between the theory and observations remain. Recent high-resolution observations captured simultaneously by two different instruments reveal distinct damping lengths for slow magnetoacoustic waves, although their passbands are similar. These results suggest a possible contribution of instrumental characteristics to the measurement of damping lengths. Here, we analyze the behavior of slow waves using a different pair of instruments in order to check the prevalence of such results. In particular, the cotemporal observations of active region NOAA AR 12712 by the High-resolution Coronal Imager (Hi-C 2.1; Hi-C) and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) are utilised. The estimated oscillation periods of slow magnetoacoustic waves identified from these data are 2.7 ± 0.2 minutes from SDO/AIA and 2.8 ± 1.2 minutes from Hi-C 2.1. The corresponding propagation speeds are found to be 46.0 ± 1.7 and 48.1 ± 0.6 km s−1, respectively. Damping lengths were calculated by two different methods, the phase tracking method (PTM) and the Amplitude Tracking Method (ATM). The obtained values from the PTM are 4.0 ± 2.1 and 4.1 ± 0.3 Mm, while those from the ATM are 3.4 ± 1.0 and 3.7 ± 0.1 Mm, respectively, for the AIA and Hi-C data. Our results do not indicate any notable difference in damping lengths between these instruments.

The present study involved the assessment of potential generation of acid drainage from a coal mining area in India. Laboratory-based static and kinetic tests on overburden samples were conducted. Results of the static tests using acid base accounting indicate that all samples may be acid generators, and their generation capacity varied between likely, possible and low. To verify the acid generation potentiality of those samples showing a high acid drainage production in the static test, the kinetic test, using humidity cell, was conducted for a period of 15 weeks. The samples were leached with simulated rain water to mimic the chemical weathering under controlled laboratory conditions and imitate actual mine site leaching. Data obtained from chemical analysis of collected leachate were used to estimate production and reaction rates of acid generation and neutralizing capacity. Based on the kinetic test, it can be concluded that presently the neutralizing capacity of the samples is better than the oxidation capacity (acid generation). But due to the high weathering rate of carbonates, as reflected by the simulated leaching test, the neutralizing materials (carbonates) will eventually be exhausted earlier (since they showed dissolution rate) than the acid generation species (sulfates). Thus, acid drainage production is predicted from that point of time, when the neutralizing capacity has been exhausted for these mine sites.

The eruption of Nova Persei 1901 (GK Per) occurred 125 yr ago; remarkably, it still holds major surprises. Using data from the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer (SPHEREx), we find that it has a bipolar molecular hydrogen shell. This shell, which has dimensions 18′×10′ , is cospatial with the Hα nebulosity surrounding the nova, which has been suggested to be an ancient planetary nebula (PN). The shell is detected most strongly in the 0–0 S(9) 4.6947 μm line. A filament of emission in the S(9) 4.6947 μm line is seen ≃45″ southwest of GK Per. This coincides, over much of its length, with the site of X-ray and nonthermal radio emission where the 1901 nova ejecta impinges on the ambient medium. We propose that the H2 emission from the filament arises from the predicted neutral zone between the forward and reverse shocks. Since it is common for bipolar PNe to be accompanied by H2 envelopes, it ostensibly suggests that the 18′×10′ nebulosity is a conventional PN with a luminous, ionizing central source. We show this is not the case, and that the Hα nebulosity may be surrounding gas belonging to preexisting material that was ionized during the 1901 eruption. The ionized gas is presently undergoing recombination on a timescale of ≃3000 yr, explaining why the nebulosity is still visible.

The multiwavelength data from the Solar Dynamics Observatory is extensively used in studying the physics of the Sun and its atmosphere. In this study, we estimate the formation heights of low-corona and chromospheric channels of the Atmospheric Imaging Assembly (AIA) over the atmospheres of sunspot umbrae during the quiet condition period within 20 different active regions. The upward propagating slow magnetoacoustic waves of a 3 minute period, which are perpetually present in sunspots, are utilized for this purpose. Employing a cross-correlation technique, the most frequent time lag between different channel pairs is measured. By combining this information with the local sound speed obtained from the characteristic formation temperatures of individual channels, we estimate the respective formation heights. The median values of formation heights obtained across all active regions in our sample are 356, 368, 858, 1180, and 1470 km, respectively, for the AIA 1600, 1700, 304, 131, and 171 Å channels. The corresponding ranges in the formation heights are 247–453, 260–468, 575–1155, 709–1937, and 909–2585 km, respectively. These values are measured with respect to the Helioseismic Magnetic Imager continuum. We find the formation height of UV channels is quite stable (between 250 and 500 km) and displays only a marginal difference between the AIA 1600 and 1700 Å channels during quiet conditions. On the other hand, the formation height of coronal channels is quite variable.

We report the detection of carbon monoxide (CO) and dust, formed under hostile conditions, in recurrent nova V745 Sco about 8.7 days after its 2014 outburst. The formation of molecules or dust has not been recorded previously in the ejecta of a recurrent nova. The mass and temperature of the CO and dust are estimated to be T CO = 2250 ± 250 K, M CO = (1–5) × 10−8 M ⊙, and T dust = 1000 ± 50 K, M dust ∼ 10−8–10−9 M ⊙, respectively. At the time of their detection, the shocked gas was at a high temperature of ∼107 K as evidenced by the presence of coronal lines. The ejecta were simultaneously irradiated by a large flux of soft X-ray radiation from the central white dwarf. Molecules and dust are not expected to form and survive in such harsh conditions; they are like snowflakes in a furnace. However, it has been posited in other studies that, as the nova ejecta plow through the red giant's wind, a region exists between the forward and reverse shocks that is cool, dense and clumpy where the dust and CO could likely form. We speculate that this site may also be a region of particle acceleration, thereby contributing to the generation of γ-rays.