Disc-like Structure Research Articles

Phenylalanine-embedded carbazole-based fluorescent ‘turn-off’ chemosensor for the detection of metal ions

Fluorescent chemosensors are highly important for various applications including medical diagnostics, environmental monitoring, and industrial processing. Significant advancements have been made to produce sensors capable of detecting biologically and environmentally relevant ions. Specifically, carbazole-derived fluorophores are chemically stable agents with the ability to detect anions, cations, and small bioorganic molecules. However, most carbazole-based fluorescent probes for the detection of metal ions are Schiff bases and require stringent pH control to prevent hydrolysis. On the other hand, amide-based sensors that utilize stable amino acid scaffolds provide a robust sensing platform as well as a soft-chemical environment for detecting both soft and heavy metal ions. Herein, we explored an aromatic amino acid Phe-containing carbazole-based “turn-off” fluorescent chemosensor to improve the sensor specificity using π-conjugation and additional binding sites. The structure of the novel chemosensor was characterized by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy. In addition, the sensing properties towards metal ions were studied using UV–vis and fluorescence spectroscopy. Among the various metal ions tested, the chemosensor showed high selectivity and sensitivity towards Co2+, Ni2+, and Cu2+ ions. The detection limits for Co2+, Ni2+, and Cu2+ ions were found to be 4.78 µM, 3.50 µM, and 5.17 µM respectively. Furthermore, the interaction of Phe-amino-carbazole with the various tested metal ions resulted in a flakes-like supramolecular structure, similar to the native Phe-amino-carbazole, whereas the interaction of the designed chemosensor with the Pb2+ metal ion resulted in a uniform 3D-circular disc-like supramolecular structure, as confirmed by electron microscopy experiment. This highlights the potential of the Phe-containing carbazole-derived chemosensor for the detection of multiple cations with a decrease in the fluorescence response with a lower detection limit.

The structure of massive star-forming galaxies from JWST and ALMA: Dusty, high-redshift disc galaxies

We present an analysis of the NIRCam and MIRI morphological and structural properties of 80 massive ($ (M_ M_ odot )$\,=\,11.2\,pm \,0.1) dusty star-forming galaxies at $, identified as sub-millimetre galaxies (SMGs) by ALMA, which have been observed as part of the PRIMER project. To compare the structure of these massive, active galaxies to more typical, less actively star-forming galaxies, we defined two comparison samples. The first of 850 field galaxies matched in specific star formation rate and redshift and the second of 80 field galaxies matched in stellar mass . From the visual classification of the SMGs, we have identified 20\,pm \,5<!PCT!> as candidate late-stage major mergers, a further 40\,pm \,10<!PCT!> as potential minor mergers, and 40\,pm \,10<!PCT!> that have comparatively undisturbed disc-like morphologies, with no obvious massive neighbours on lesssim \,20\,--\,30\,kpc (projected) scales. These rates are comparable to those for the field samples and indicate that the majority of the sub-millimetre-detected galaxies are not late-stage major mergers, but have interaction rates similar to the general field population at $z$\,sim \,2--3. Through a multi-wavelength morphological analysis, using parametric and non-parametric techniques, we establish that SMGs have comparable near-infrared, mass-normalised sizes to the less active population, $ F444W $\,=\,2.7\,pm \,0.2\,kpc versus $ F444W $\,=\,3.1\,pm \,0.1\,kpc, but exhibit lower S\'ersic indices, consistent with bulge-less discs: F444W $\,=\,1.1\,pm \,0.1, compared to F444W $\,=\,1.9\,pm \,0.1 for the less active field galaxies and $n_ F444W $\,=\,2.8\,pm \,0.2 for the most massive field galaxies . The SMGs exhibit greater single-S\'ersic fit residuals and their morphologies are more structured at 2 relative to 4 when compared to the field galaxies. This appears to be caused by significant structured dust content in the SMGs and we find evidence for dust reddening as the origin of the morphological differences by identifying a strong correlation between the F200W$-$F444W pixel colour and the 870 surface brightness using high-resolution ALMA observations. We conclude that SMGs and both massive and less massive star-forming galaxies at the same epochs share a common disc-like structure, but the weaker bulge components (and potentially lower black hole masses) of the SMGs result in their gas discs being less stable. Consequently, the combination of high gas masses and instabilities triggered either secularly or by minor external perturbations results in higher levels of activity (and dust content) in SMGs compared to typical star-forming galaxies.

Effect of biosurfactants on the self-assembly behavior and drug encapsulation for branched block copolymers

For the past few years, block copolymers have attracted extensive attention in the field of drug delivery. In this work, the hyperbranched PEO-PPO block copolymer H1304 having the same PEO segments and PPO segments as the commercially available 4-branched block copolymer Tetronic1304 was synthesized. Compared with T1304, H1304 was characterized by lower cloud point, smaller critical micelle concentration (CMC), larger micellar size and better drug solubilization capacity. The effect of three biosurfactants lecithin (PC), alkyl glycogen (APG), sodium deoxycholate (NaDC) on the aggregation behavior of H1304 and T1304 were researched. Meanwhile, the solubilization and in vitro release properties of hydrophobic anticancer drug podophyllotoxin were also evaluated. The addition of PC or APG to form a mixed micelle reduced the cloud point and CMC, optimized the drug carrier characteristics. NaDC exhibited different effects due to its unique disclike surface structure. NaDC formed back-to-back aggregates, which interfered the self-assembly process of block copolymer and in turn caused variation of the copolymer micellar properties. The study of mixed systems consisting of biosurfactants and block copolymers will help to change the performance of copolymers in various pharmaceutical fields and contribute to the application of copolymers as drug carriers in drug delivery systems.

Circular orbits of accretion flow around charged black hole coupled with a nonlinear electrodynamics field

This study investigates the particle’s geodesic motion and accretion around the spherically symmetric Reissner–Nordström black hole coupled with a nonlinear electrodynamics field. The formation of the disc-like structure in the accretion process arises from the geodesic motion exhibited by particles near the black hole. In the equatorial plane, we analyze the circular orbits of particles and their stability in detail. The analysis of the fluid’s critical flow, maximum accretion rate, radiant flux energy, radioactive efficiency, and radiant temperature are also examined near the central object. We analyze the perturbations experienced by particles throughout, employing restoring forces and the oscillatory behavior of the particles around the black hole. Our results show that the NED parameter ζ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\zeta $$\\end{document} affects the circular geodesics of particles and the maximum accretion rate of the Reissner–Nordström black hole coupled with nonlinear electrodynamics.

P-300 Exosomes derived from uterine fluid in patients with repeated implantation failure inhibit embryonic adhesion, invasion, and migration to endometrium

Abstract Study question By collecting clinical samples, we focused on the effect and mechanism of exosomes derived from uterine fluid on embryo implantation during the window of implantation. Summary answer Exosomes from uterine fluid in repeated implantation failure group inhibited adhesion, invasion, and migration of trophoblast cells via MAPK, VEGF, estrogen, Rap1 signal pathways. What is known already Implantation of the embryo requires the endometrium to be in an optimal state of reception for simultaneous development of normal blastocyst. Repeated implantation failure can result from embryonic quality and disturbed crosstalk between embryo and endometrium. Exosomes are extra cellular vesicles, they can be secreted into the uterine cavity, and transfer key information to recipient cells. At present, plenty of studies have shown that exosomes derived from uterine fluid worked on the maternal-fetal interaction during the window of implantation. Whether and how exosome from uterine fluid of RIF patients caused transplantation failure remained to be explored. Study design, size, duration During 2023.2-2023.8, 6 women with repeated implantation failure (RIF) and 9 women who had successfully conceived after the first transplant were recruited as RIF and control groups. All the included women were selected strictly according to the inclusion and exclusion criteria, and confounding factors such as age, BMI, and menstrual cycle were excluded, the window of implantation was determined by artificial cycle preparation. Participants/materials, setting, methods Exosomes were identified by Transmission electron microscope(TEM), Western blot(WB) and Nanoparticle Tracking Analysis(NTA). Immunofluorescence test scratch test and transwell experiment were used to verify the effects of exosomes on cell migration and invasion, cell implantation model culture and real-time cells analysis by xCELLigence were used to verify the effect of exosomes on cell adhesion. Finally, Micro-RNA sequence was conducted on Illumina HiSeq 6000 instrumen between two groups to find out the key potential signal pathway. Main results and the role of chance a. Isolation and identification of exosomes: TEM: Exosomes derived from the uterine fluid from the two groups showed a complete disc-like structure; NTA: The average diameter of exosomes from two groups were similar; WB: CD9, CD63, TSG101, HSP70 were expressed in both groups. b. Exosomes can be taken up by trophoblast cells: Immunofluorescence assay showed that exosomes derived from uterine fluid could be taken up by trophoblast cells, and the amount of uptake increased with time. c. Exosomes affect cell migration and invasion: Scratch test and transwell experiment showed that compared with the control group, the migration ability of trophoblast cells in RIF group was reduced, and the number of migrating cells decreased(P＜0.05). d. Exosomes affect cell adhesion: cell implantation model culture and real-time cells analysis by xCELLigence showed that compared with the control group, the adhesion ability of trophoblast cells decreased in the RIF group(P＜0.05). e. miRNA profile between RIF and control group: Before and during the implantation window period, there were significant differences in 43 genes between two groups, these genes regulate embryo implantation by mediating the MAPK, VEGF, estrogen, Rap1, mucin type O-glycan biosynthesis pathway. Limitations, reasons for caution 1.Due to the strict recruitment criteria, the number of women enrolled in the study was limited. 2.Through the analysis of differentially expressed micro-RNAs, relevant downstream pathways have been found. However, there is a lack of corresponding mechanism studies on how gene expression affects maternal-fetal interaction. Wider implications of the findings Through in vitro cell experiment and biological information data analysis, this study allows us to better understand the mechanism of action of exosomes in the embryo implantation process, detect and diagnose RIF populations at an early stage, and provide new ideas for promoting the treatment of infertility and implantation failure. Trial registration number Not applicable.

Analysis of albedo and disc effects in the generalized restricted four-body problem

This manuscript explores the Generalized Restricted Four-Body Problem within the context of radiation pressure, the albedo effect, oblateness, and a disc-like structure that orbits around the primary bodies. We have considered that one of the primaries is a bigger primary, and the rest of the two smaller primaries are of equal masses, in which one of the smaller primaries is considered as a black body. Moreover, the perturbing forces by the effect of radiation pressure and oblateness are considered in the bigger primary. The effect of albedo and oblateness due to the second smaller primary is also taken into count. This study yields nine equilibrium points corresponding to various parameter values, including three collinear and six non-collinear equilibria. We conduct an analysis of the equilibrium points, their linear stability, and the motion around them. In the context of the considered parameter set, certain collinear equilibrium points exhibit stability, while others are unstable. Additionally, most of the non-collinear equilibrium points display linear stability. We also investigate variations in Jacobi’s constant and the positions of existing equilibrium points caused by the albedo and disc effects. It is found that the value of Jacobi constant CLj decreases with an increase in the mass parameter μ at the collinear points, which results in an expansion in the prohibited region. The inhibited zone of motion of the infinitesimal body is shown for different sets of parameters.

Preparation of Titanium Carbide by Carburisation of Titanium Dioxide

Titanium carbide has attracted widespread attention due to its excellent properties. This study investigates the process of carbon thermally reducing TiO2 to prepare TiC through a combination of thermodynamic analysis and experiments. The effects of temperature, TiO2/C molar ratio, and time on the phase transformation and morphology evolution of the products are investigated. The synthesis of titanium carbide involves the main reduction path of TiO2–Magnéli–Ti3O5–Ti2O3–TiCxO1−x. With the increase in reaction temperature and TiC content, the microstructure transitions from a smooth disc-like structure to a loose and porous layered structure, while the particle size decreases significantly. The carburisation rate of the reduced product is more affected by temperature, according to chemical analysis. The carburisation rate increased from 18.37% to 36.09% for 2 h–10 h of holding time at 1400 °C, and from 51.43% to 77.57% for 2 h–10 h of holding time at 1500 °C. The quantification of the carburisation rate provides a valuable reference for the preparation of titanium carbide by TiO2.

A kinematic study of the disc-outflow system around a high-mass protostar G59.783+0.065 probed by methanol and water masers

ABSTRACT Class II CH3OH masers are used as a convenient tracer of disc-like structures in high-mass star formation. However, more than half of them show a complex distribution in Very Long Baseline Interferometry (VLBI) maps. The origin of such a complex distribution is still unknown. We conducted VLBI monitoring observations to unveil the origin of a complex class II CH3OH maser in the high-mass star-forming region G59.783+0.065. We observed the CH3OH maser at 6.7 GHz and the H2O maser at 22 GHz to probe detailed circumstellar kinematics and structures by the Japanese VLBI network and the VLBI Exploration of Radio Astrometry. We found similar bipolar distributions in both masers, specifically two clusters located 2000 au apart along the east–west direction. We detected a linear distribution of CH3OH masers in the western cluster. A position–velocity diagram shows that the western CH3OH masers trace a rotating disc-wind or infalling component inside an edge-on disc-like structure. In contrast to the simple bipolar expanding motions of the H2O masers, the CH3OH masers exhibited complex motions despite their spatial coincidence. Some of the eastern CH3OH masers showed bipolar expansions similar to the H2O masers, while others displayed random or even inward motions. Such complex kinematics and their close association with the H2O maser could occur at the boundary between outflow and inflow. We suggest that the complex distribution of class II CH3OH masers, like G59.783+0.065 arises from several distinct circumstellar structures that simultaneously achieve maser excitation.

Constraining study of circular orbits and accretion disk around nonlinear electrodynamics black hole

The very latest observation of M87 supermassive black hole (BH) by the Event Horizon Telescope (EHT) provides the accretion onto BHs is an interesting study in the theory of gravity. We study the geodesics structure and accretion near a nonlinear electrodynamics BH in strong and weak field approximations. These approximations provide the disc-like structure under the geodesic motion and accretion around the BH. Near the equatorial plane, we provide some new reasons to make circular orbits and accretion of test particles around the BH. Then we investigate perturbations, the critical speed of the fluid and the mass accretion rate of particles around the central object. The physical validity of this study shows that the parameter β and Q play an important role in the circular orbits and the mass accretion rate in strong and weak field approximations.

SALT spectroscopy of the HMXB associated with the LMC supernova remnant MCSNR J0513−6724

ABSTRACT We report the results of optical échelle spectroscopy with the Southern African Large Telescope (SALT) of the mass donor star BSDL923 in the neutron star (NS) high-mass X-ray binary XMMU J051342.6−672412 associated with the LMC supernova remnant (SNR) MCSNR J0513−6724. We found that BSDL923 is a B0.7 III star with double peaked emission lines originating in a circumbinary disc-like structure. Modelling with the stellar atmosphere code fastwind was used to derive Teff = 27 000 K, log g = 3.22, $v\sin i\approx 100\, {\rm \, km\, s^{-1}}$ and $\log (L_*/\rm \, L_\odot)=5.46$ of BSDL923, as well as to show that the surface of this star is polluted with α-elements from the supernova ejecta. We found also that the NS is orbiting BSDL923 in an eccentric orbit with the orbital period of 1.280 d and the semimajor axis of $17\pm 3 \,R_\odot$, which is less than or equal to the radius of BSDL923 of $25\pm 5 \,R_\odot$. We speculate that the NS is embedded in the atmosphere of BSDL923 either because it was kicked at birth towards this star or because of inflation of BSDL923 caused by the energy input from the supernova blast wave. Using long-slit spectroscopy with SALT, we searched for possible signs of the SNR shell in the 2D spectrum, but did not find them. This lack of detection is consistent with the young age of this SNR, implying that it is still in the adiabatic phase.

Initial flash and spectral formation of Type Ia supernovae with an envelope: applications to overluminous SNe Ia

ABSTRACT Overluminous Type Ia supernovae (SNe Ia) show peculiar observational features, for which an explosion of a super-massive white dwarf (WD) beyond the classical Chandrasekhar-limiting mass has been suggested, largely based on their high luminosities and slow light-curve evolution. However, their observational features are diverse, with a few extremely peculiar features whose origins have not been clarified; strong and persisting C II lines, late-time accelerated luminosity decline and red spectra, and a sub-day time-scale initial flash clearly identified so far at least for three overluminous SNe Ia. In the present work, we suggest a scenario that provides a unified solution to these peculiarities, through hydrodynamic and radiation transfer simulations together with analytical considerations; a C+O-rich envelope (∼0.01−0.1M⊙) attached to an exploding WD. Strong C II lines are created within the shocked envelope. Dust formation is possible in the late phase, providing a sufficient optical depth thereafter. The range of the envelope mass considered here predicts an initial flash with time-scale of ∼0.5−3 days. The scenario thus can explain some of the key diverse observational properties by a different amount of the envelope, but additional factors are also required; we argue that the envelope is distributed in a disc-like structure, and also the ejecta properties, e.g. the mass of the WD, play a key role. Within the context of the hypothesized super-Chandrasekhar-mass WD scenario, we speculatively suggest a progenitor WD evolution including a spin-up accretion phase followed by a spin-down mass-ejection phase.

The MOSDEF survey: a new view of a remarkable z = 1.89 merger

ABSTRACT We present a detailed study of a galaxy merger taking place at z = 1.89 in the GOODS-S field. Here, we analyse Keck/MOSFIRE spectroscopic observations from the MOSFIRE Deep Evolution Field (MOSDEF) survey along with multiwavelength photometry assembled by the 3D-HST survey. The combined data set is modelled to infer the past star formation histories (SFHs) of both merging galaxies. They are found to be massive, with log10(M*/M⊙) > 11, with a close mass ratio satisfying the typical major-merger definition. Additionally, in the context of delayed-τ models, GOODS-S 43114, and GOODS-S 43683 have similar SFHs and low star formation rates (log10(SFR(SED)/${\rm M}_{\odot }\,\rm {yr}^{-1}$) < 1.0) compared to their past averages. The best-fitting model SEDs show elevated H δA values for both galaxies, indicating that their stellar spectra are dominated by A-type stars, and that star formation peaked ∼0.5−1 Gyr ago and has recently declined. Additionally, based on SED fitting both merging galaxies turned on and shut off star formation within a few hundred Myr of each other, suggesting that their bursts of star formation may be linked. Combining the SFHs and H δA results with recent galaxy merger simulations, we infer that these galaxies have recently completed their first pericentric passage and are moving apart. Finally, the relatively low second velocity moment of GOODS-S 43114, given its stellar mass suggests a disc-like structure. However, including the geometry of the galaxy in the modelling does not completely resolve the discrepancy between the dynamical and stellar masses. Future work is needed to resolve this inconsistency in mass.

Binary-object spectral-synthesis in 3D (BOSS-3D)

Context. To quantitatively decode the information stored within an observed spectrum, detailed modelling of the physical state and accurate radiative transfer solution schemes are required. The accuracy of the model is then typically evaluated by comparing the calculated and observed spectra. In the analysis of stellar spectra, the numerical model often needs to account for binary companions and 3D structures in the stellar envelopes. The enigmatic binary (or multiple) system LB-1 constitutes a perfect example of such a complex multi-D problem. Thus far, the LB-1 system has been indirectly investigated by 1D stellar-atmosphere codes and by spectral disentangling techniques, yielding differing conclusions about the nature of the system (e.g., a B-star and black-hole binary with an accretion disc around the black hole or a stripped-star and Be-star binary system have been proposed). Aims. To improve our understanding of the LB-1 system, we directly modelled the phase-dependent Hα line profiles of this system. To this end, we developed and present a multi-purpose binary-object spectral-synthesis code in 3D (BOSS-3D). Methods. BOSS-3D calculates synthetic line profiles for a given state of the circumstellar material. The standard pz-geometry commonly used for single stars is extended by defining individual coordinate systems for each involved object and by accounting for the appropriate coordinate transformations. The code is then applied to the LB-1 system, considering two main hypotheses, a binary containing a stripped star and Be star, or a B star and a black hole with a disc. Results. Comparing these two scenarios, neither model can reproduce the detailed phase-dependent shape of the Hα line profiles. A satisfactory match with the observations, however, is obtained by invoking a disc around the primary object in addition to the Be-star disc or the black-hole accretion disc. Conclusions. The developed code can be used to model synthetic line profiles for a wide variety of binary systems, ranging from transit spectra of planetary atmospheres, to post-asymptotic giant branch binaries including circumstellar and circumbinary discs and massive-star binaries with stellar winds and disc systems. For the LB-1 system, our modelling provides strong evidence that each object in the system contains a disc-like structure.

Effects of exosomes from human adipose-derived mesenchymal stem cells on pulmonary vascular endothelial cells injury in septic mice and its mechanism

Effects of exosomes from human adipose-derived mesenchymal stem cells on pulmonary vascular endothelial cells injury in septic mice and its mechanism

Dynamics of the restricted three-body problem having elongated smaller primary with disc-like structure

In this paper, we have analysed the dynamical behavior of the restricted three-body problem having elongated smaller primary with disc-like structure. We discuss the zero-velocity curve, equilibrium points, and their stability by considering the different segment-length of the elongated primary and mass ratio of the primary. The impacts of disc-like structure and elongated primary body are observed on the equilibrium points and their stability analysis. We demonstrate that all collinear equilibrium points are unstable by varying the mass parameter μ and the segment length l. Further, the critical point for mass parameter μc at non-collinear equilibrium points is calculated. Furthermore, we emphasize our discussion through an example by taking mass parameter μ=0.01<μc and segment-length l=0.01. Finally, we conclude that the proposed problem is a credible model for describing the infinitesimal body’s motion in a disc-like structure with an elongated smaller primary.

Recent Progress in Electrospun Nanofiber-Based Degenerated Intervertebral Disc Repair

Annulus fibrosus fissure and fibrosis of nucleus pulposus are severe morphological characteristics of intervertebral disc degeneration. Currently, surgery or drugs are used to relieve pain in such cases. Tissue engineering is a new multidisciplinary strategy with great potential for use in joint replacement and organ regeneration. Based on the natural anatomy of intervertebral discs, intervertebral disc scaffolds are fabricated by exploiting the special arrangement of extracellular matrix fibers. Electrospun nanofibers possess clear advantages in repairing degenerated intervertebral discs. This article reviews and summarizes recently developed methods for improving and fabricating electrospun nanofiber annulus fibrosus scaffolds in terms of nanofiber alignment, material selection, loading additives, and the progress made in combining other advanced technologies with electrospun nanofibers. In addition, the improvement in mechanical properties and biocompatibility of nucleus pulposus scaffolds by electrospun nanofiber-reinforced hydrogels is discussed. Finally, complete intervertebral disc scaffolds can be fabricated using the disc-like angle-ply structure and other emerging fabrication methods. Taken together, electrospun nanofiber intervertebral disc scaffolds are promising for clinical applications.

Protostellar Interferometric Line Survey of the Cygnus X region (PILS-Cygnus)

Context. Complex organic molecules (COMs) are commonly detected in and near star-forming regions. However, the dominant process in the release of these COMs from the icy grains – where they predominately form – to the gas phase is still an open question. Aims. We investigate the origin of COM emission in a high-mass protostellar source, CygX-N30 MM1, through high-angular-resolution interferometric observations over a continuous broad frequency range. Methods. We used 32 GHz Submillimeter Array observations with continuous frequency coverage from 329 to 361 GHz at an angular resolution of ~1″ to do a line survey and obtain a chemical inventory of the source. The line emission in the frequency range was used to determine column densities and excitation temperatures for the COMs. We also mapped out the intensity distribution of the different species. Results. We identified approximately 400 lines that can be attributed to 29 different molecular species and their isotopologues. We find that the molecular peak emission is along a linear gradient, and coincides with the axis of red- and blueshifted H2CO and CS emission. Chemical differentiation is detected along this gradient, with the O-bearing molecular species peaking towards one component of the system and the N- and S-bearing species peaking towards the other. The chemical gradient is offset from but parallel to the axis through the two continuum sources. The inferred column densities and excitation temperatures are compared to other sources where COMs are abundant. Only one deuterated molecule is detected, HDO, while an upper limit for CH2DOH is derived, leading to a D/H ratio of &lt;0.1%. Conclusions. We conclude that the origin of the observed COM emission is probably a combination of the young stellar sources along with accretion of infalling material onto a disc-like structure surrounding a young protostar and located close to one of the continuum sources. This disc and protostar are associated with the O-bearing molecular species, while the S- and N-bearing species on the other hand are associated with the other continuum core, which is probably a protostar that is slightly more evolved than the other component of the system. The low D/H ratio likely reflects a pre-stellar phase where the COMs formed on the ices at warm temperatures (~30 K), where the deuterium fractionation would have been inefficient. The observations and results presented here demonstrate the importance of good frequency coverage and high angular resolution when disentangling the origin of COM emission.

A comparison of 2D Magnetohydrodynamic supernova simulations with the CoCoNuT-FMT and Aenus-Alcar codes

ABSTRACT Code comparisons are a valuable tool for the verification of supernova simulation codes and the quantification of model uncertainties. Here, we present a first comparison of axisymmetric magnetohydrodynamic (MHD) supernova simulations with the CoCoNuT-FMT and Aenus-Alcar codes, which use distinct methods for treating the MHD induction equation and the neutrino transport. We run two sets of simulations of a rapidly rotating 35M⊙ gamma-ray burst progenitor model with different choices for the initial field strength, namely $10^{12}\, \mathrm{G}$ for the maximum poloidal and toroidal field in the strong-field case and $10^{10}\, \mathrm{G}$ in the weak-field case. We also investigate the influence of the Riemann solver and the resolution in CoCoNuT-FMT. The dynamics is qualitatively similar for both codes and robust with respect to these numerical details, with a rapid magnetorotational explosion in the strong-field case and a delayed neutrino-driven explosion in the weak-field case. Despite relatively similar shock trajectories, we find sizeable differences in many other global metrics of the dynamics, like the explosion energy and the magnetic energy of the proto-neutron star. Further differences emerge upon closer inspection, for example, the disc-like surface structure of the proto-neutron star proves high sensitivity to numerical details. The electron fraction distribution in the ejecta as a crucial determinant for the nucleosynthesis is qualitatively robust, but the extent of neutron- or proton-rich tails is sensitive to numerical details. Due to the complexity of the dynamics, the ultimate cause of model differences can rarely be uniquely identified, but our comparison helps gauge uncertainties inherent in current MHD supernova simulations.

Biodegradation of low-density polyethylene (LDPE) sheet by microalga, Uronema africanum Borge

Plastic (polyethylene) pollution is a severe cause of deterioration of a healthy environment. For example, ingestion of plastics in the animal gut, clogging of water canals and retarded solid waste management. Many conventional methods of polyethylene degradation include UV photooxidation, thermal oxidation, incineration, chemical oxidation and landfill are being practiced. However, these methods are not feasible, costlier and not a complete solution for this global issue. Therefore, plausible, alternative solution for this issue is biodegradation. Microbes such as bacteria, fungi and algae are involved in polyethylene degradation in its natural habitat. Among them, algae were given very less importance. In our present study, a potential microalga, morphologically identified as Uronema africanum Borge, isolated from a waste plastic bag collected from a domestic waste dumping site in a freshwater lake. This microalga was further treated with the LDPE sheet in BBM culture medium. Based on the results obtained from light microscopy, dark field microscopy, GC–MS, FT-IR, SEM and AFM, it was concluded that the microalga has initiated degradation of LDPE sheet within 30 days of incubation. Concurrently, the configuration of corrosions, abrasions, grooves and ridges were found similar with the morphological features of the microalga. For example, the configuration of the radial disc-like attachment structure of the microalga was found corresponding to the abrasions on the surface of LDPE sheet at an average size of 20–30 µm in diameter. Whereas, the configuration of ridges and grooves were found similar with the filamentous nature of the microalga (10–15 µm width). This is a hitherto report on the biodegradation of LDPE sheet by the microalga Uronema africanum Borge.

Neutron Studies of a High Spin Fe19 Molecular Nanodisc

The molecular cluster system [Fe19(metheidi)10(OH)14O6(H2O)12]NO3·24H2O, abbreviated as Fe19, contains nineteen Fe(III) ions arranged in a disc-like structure with the total spin S = 35/2. For the first order, it behaves magnetically as a single molecule magnet with a 16 K anisotropy barrier. The high spin value enhances weak intermolecular interactions for both dipolar and superexchange mechanisms and an eventual transition to antiferromagnetic order occurs at 1.2 K. We used neutron diffraction to determine both the mode of ordering and the easy spin axis. The observed ordering was not consistent with a purely dipolar driven order, indicating a significant contribution from intermolecular superexchange. The easy axis is close to the molecular Fe1–Fe10 axis. Inelastic neutron scattering was used to follow the magnetic order parameter and to measure the magnetic excitations. Direct transitions to at least three excited states were found in the 2 to 3 meV region. Measurements below 0.2 meV revealed two low energy excited states, which were assigned to S = 39/2 and S = 31/2 spin states with respective excitation gaps of 1.5 and 3 K. Exchange interactions operating over distances of order 10 Å were determined to be on the order of 5 mK and were eight-times stronger than the dipolar coupling.