A Semi-Analytical Model for the Formation and Evolution of Radio Relics in Galaxy Clusters

Radio relics are Mpc-sized synchrotron sources located in the peripheral regions of galaxy clusters. Models based on the diffuse shock acceleration (DSA) scenario have been widely accepted to explain the formation of radio relics. However, a critical challenge to these models is that most observed shocks seem too weak to generate detectable emission, unless fossil electrons, a population of mildly energetic electrons that have been accelerated previously, are included in the models. To address this issue, we present a new semi-analytical model to describe the formation and evolution of radio relics by incorporating fossil relativistic electrons into DSA theory, which is constrained by a sample of 14 observed relics, and employ the Press-Schechter formalism to simulate the relics in a $20^{\circ} \times 20^{\circ}$ sky field at 50, 158, and 1400 MHz, respectively. Results show that fossil electrons contribute significantly to the radio emission, which can generate radiation four orders of magnitude brighter than that solely produced by thermal electrons at 158 MHz, and the power distribution of our simulated radio relic catalog can reconcile the observed $P_{1400}-M_{\mathrm{vir}}$ relation. We predict that $7.1\%$ clusters with $M_{\mathrm{vir}} > 1.2\times 10^{14}\,\mathrm{M}_{\odot}$ would host relics at 158 MHz, which is consistent with the result of $10 \pm 6\%$ given by the LoTSS DR2. It is also found that radio relics are expected to cause severe foreground contamination in future EoR experiments, similar to that of radio halos. The possibility of AGN providing seed fossil relativistic electrons is evaluated by calculating the number of radio-loud AGNs that a shock is expected to encounter during its propagation.Comment: 15 pages, 20 figures. Accepted for publication in MNRAS. Comments welcom

Genome analysis of a plasmid-bearing myxobacterim Myxococcus sp. strain MxC21 with salt-tolerant property

Myxobacteria are widely distributed in various habitats of soil and oceanic sediment. However, it is unclear whether soil-dwelling myxobacteria tolerate a saline environment. In this study, a salt-tolerant myxobacterium Myxococcus sp. strain MxC21 was isolated from forest soil with NaCl tolerance >2% concentration. Under 1% salt-contained condition, strain MxC21 could kill and consume bacteria prey and exhibited complex social behaviors such as S-motility, biofilm, and fruiting body formation but adopted an asocial living pattern with the presence of 1.5% NaCl. To investigate the genomic basis of stress tolerance, the complete genome of MxC21 was sequenced and analyzed. Strain MxC21 consists of a circular chromosome with a total length of 9.13 Mbp and a circular plasmid of 64.3 kb. Comparative genomic analysis revealed that the genomes of strain MxC21 and M. xanthus DK1622 share high genome synteny, while no endogenous plasmid was found in DK1622. Further analysis showed that approximately 21% of its coding genes from the genome of strain MxC21 are predominantly associated with signal transduction, transcriptional regulation, and protein folding involved in diverse niche adaptation such as salt tolerance, which enables social behavior such as gliding motility, sporulation, and predation. Meantime, a high number of genes are also found to be involved in defense against oxidative stress and production of antimicrobial compounds. All of these functional genes may be responsible for the potential salt-toleration. Otherwise, strain MxC21 is the second reported myxobacteria containing indigenous plasmid, while only a small proportion of genes was specific to the circular plasmid of strain MxC21, and most of them were annotated as hypothetical proteins, which may have a direct relationship with the habitat adaptation of strain MxC21 under saline environment. This study provides an inspiration of the adaptive evolution of salt-tolerant myxobacterium and facilitates a potential application in the improvement of saline soil in future

UiO-66-NH₂@PMAA: A Hybrid Polymer–MOFs Architecture for Pectinase Immobilization

A hybrid polymer–MOFs architecture UiO-66-NH₂@PMAA was synthesized by tethering polymethacrylic acid (PMAA) onto the surface of the metal–organic frameworks UiO-66-NH₂, and it was further employed for pectinase immobilization by electrostatic interactions. The hybrid architecture was prepared through a combination of atom transfer radical polymerization (ATRP), click chemistry and postsynthetic modification (PSM). The optimal immobilization parameters were at 25 °C and pH 4.0 with 10 U/mL of pectinase for 2 h, under which pectinase showed the highest enzymatic activity (1.215 U/mg) and protein loading (448.5 mg/g), respectively. Compared with free pectinase, the immobilized was found to exhibit higher pH, thermo, and storage stability. Additionally, the immobilized pectinase had remarkable reusability, the residual activity reached as high as 81% after 8 cycles continuously. Meanwhile, the desorption of immobilized pectinase can be achieved by changing pH values of the medium. Obviously, the UiO-66-NH₂@PMAA with attractive properties is highly promising for enzyme immobilization

Twist-Shaped CuO Nanowires as Anode Materials for Lithium Ion Batteries

Twist-shaped CuO nanowires were synthesized by two-step method consisting of solution reaction and then heat treatment. The as-synthesized samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). When evaluated as anode materials for lithium ion batteries, twist-shaped CuO nanowires showed a high initial discharge capacity of 983 mAh g−1 and maintained a reversible capacity of 320 mAh g−1 over 50 cycles at the current density of 100 mA g−1. Thus, 1D twist-shaped CuO nanowires provide a new insight into the development of anode materials for next-generation high performance lithium ion batteries

Combined analysis of carotenoid metabolites and the transcriptome to reveal the molecular mechanism underlying fruit colouration in zucchini (Cucurbita pepo L.)

To reveal the molecular mechanism underlying peel colouration, carotenoid metabolites and the transcriptome were jointly analysed in zucchini peels with three different colours: light green (Lg), yellow (Y), and orange (O). Our results showed that the carotenoid levels in O (157.075 μg/g) and Y (22.734 μg/g) were both significantly higher than in Lg (7.435 μg/g), while the chlorophyll content was highest in Lg (32.326 μg/g), followed by O (7.294 μg/g) and Y (4.617 μg/g). A total of 14 carotenoids were detected in zucchini peels, primarily lutein (103.167 μg/g in Lg, 509.667 μg/g in Y, and 1543.333 μg/g in O). In particular, significant accumulation of antheraxanthin, zeaxanthin, neoxanthin, and β-cryptoxanthin was first reported in orange zucchini in this study. Furthermore, two modules with hub genes related to carotenoid or chlorophyll content were identified through weighted gene coexpression network analysis. Additionally, the transcription level of some hub genes (PIF4, APRR2, bHLH128, ERF4, PSY1, LCYE2, and RCCR3) was highly correlated with pigment content in the peel, which may be responsible for carotenoid accumulation and chlorophyll degradation in the Y and O varieties. Taken together, the results obtained in this study help to provide a novel mechanism underlying peel colouration in zucchini