A wide star-black-hole binary system from radial-velocity measurements.

All stellar-mass black holes have hitherto been identified by X-rays emitted from gas that is accreting onto the black hole from a companion star. These systems are all binaries with a black-hole mass that is less than 30 times that of the Sun1-4. Theory predicts, however, that X-ray-emitting systems form a minority of the total population of star-black-hole binaries5,6. When the black hole is not accreting gas, it can be found through radial-velocity measurements of the motion of the companion star. Here we report radial-velocity measurements taken over two years of the Galactic B-type star, LB-1. We find that the motion of the B star and an accompanying Hα emission line require the presence of a dark companion with a mass of [Formula: see text] solar masses, which can only be a black hole. The long orbital period of 78.9 days shows that this is a wide binary system. Gravitational-wave experiments have detected black holes of similar mass, but the formation of such massive ones in a high-metallicity environment would be extremely challenging within current stellar evolution theories.

Relativistic baryonic jets from an ultraluminous supersoft X-ray source.

The formation of relativistic jets by an accreting compact object is one of the fundamental mysteries of astrophysics. Although the theory is poorly understood, observations of relativistic jets from systems known as microquasars (compact binary stars) have led to a well established phenomenology. Relativistic jets are not expected to be produced by sources with soft or supersoft X-ray spectra, although two such systems are known to produce relatively low-velocity bipolar outflows. Here we report the optical spectra of an ultraluminous supersoft X-ray source (ULS) in the nearby galaxy M81 (M81 ULS-1; refs 9, 10). Unexpectedly, the spectra show blueshifted, broad Hα emission lines, characteristic of baryonic jets with relativistic speeds. These time-variable emission lines have projected velocities of about 17 per cent of the speed of light, and seem to be similar to those from the prototype microquasar SS 433 (refs 11, 12). Such relativistic jets are not expected to be launched from white dwarfs, and an origin from a black hole or a neutron star is hard to reconcile with the persistence of M81 ULS-1's soft X-rays. Thus the unexpected presence of relativistic jets in a ULS challenges canonical theories of jet formation, but might be explained by a long-speculated, supercritically accreting black hole with optically thick outflows.

Genome-wide identification and analyses of the AHL gene family in cotton (Gossypium).

BACKGROUND: Members of the AT-HOOK MOTIF CONTAINING NUCLEAR LOCALIZED (AHL) family are involved in various plant biological processes via protein-DNA and protein-protein interaction. However, no the systematic identification and analysis of AHL gene family have been reported in cotton. RESULTS: To investigate the potential functions of AHLs in cotton, genome-wide identification, expressions and structure analysis of the AHL gene family were performed in this study. 48, 51 and 99 AHL genes were identified from the G.raimondii, G.arboreum and G.hirsutum genome, respectively. Phylogenetic analysis revealed that the AHLs in cotton evolved into 2 clades, Clade-A with 4-5 introns and Clade-B with intronless (excluding AHL20-2). Based on the composition of the AT-hook motif(s) and PPC/DUF 296 domain, AHL proteins were classified into three types (Type-I/-II/-III), with Type-I AHLs forming Clade-B, and the other two types together diversifying in Clade-A. The detection of synteny and collinearity showed that the AHLs expanded with the specific WGD in cotton, and the sequence structure of AHL20-2 showed the tendency of increasing intron in three different Gossypium spp. The ratios of non-synonymous (Ka) and synonymous (Ks) substitution rates of orthologous gene pairs revealed that the AHL genes of G.hirsutum had undergone through various selection pressures, purifying selection mainly in A-subgenome and positive selection mainly in D-subgenome. Examination of their expression patterns showed most of AHLs of Clade-B expressed predominantly in stem, while those of Clade-A in ovules, suggesting that the AHLs within each clade shared similar expression patterns with each other. qRT-PCR analysis further confirmed that some GhAHLs higher expression in stems and ovules. CONCLUSION: In this study, 48, 51 and 99 AHL genes were identified from three cotton genomes respectively. AHLs in cotton were classified into two clades by phylogenetic relationship and three types based on the composition of motif and domain. The AHLs expanded with segmental duplication, not tandem duplication. The expression profiles of GhAHLs revealed abundant differences in expression levels in various tissues and at different stages of ovules development. Our study provided significant insights into the potential functions of AHLs in regulating the growth and development in cotton.

Nulliplex-branch, a TERMINAL FLOWER 1 ortholog, controls plant growth habit in cotton.

KEY MESSAGE: Nulliplex-branch (nb) mutants in cotton display a specific architecture. The gene responsible for the nb phenotype was identified, and its modulation mode was further studied. Plant architecture is an important agronomic factor influencing various traits such as yield and variety adaptability in crop plants. Cotton (Gossypium) simultaneously displays monopodial and sympodial growth. Nulliplex-branch (nb) mutants showing determinate sympodial shoots have been reported in both G. hirsutum (Ghnb) and G. barbadense (Gbnb). In this study, the gene responsible for the nb phenotype was identified. GhNB and GbNB were found to be allelic loci and are TERMINAL FLOWER 1 orthologs on the Dt subgenome, though the At copies remain native. Sequencing and association analyses identified four (Gh-nb1-Gh-nb4) and one (Gb-nb1) type of point mutation in the coding sequences of Ghnb and Gbnb, respectively. The NB gene was mainly expressed in the root and shoot apex, and expression rhythms were also observed in these tissues, suggesting that the expression of the NB gene could be regulated by photoperiod. Constitutive overexpression of GhNB suppresses the differentiation of the reproductive shoots. Knockout of both copies of GhNB caused the main and lateral shoots to terminate in flowers, which is a more determinate architecture than that of the nb mutants and implies that its function might be dosage dependent. A protein lipid overlay assay indicated that the amino acid substitutions in Gh-nb1 and Gb-nb1 weaken the ligand-binding activity of the NB protein in vitro. These findings suggest that the NB gene plays crucial roles in regulating the determinacy of shoots, and the modulation of this gene should constitute an effective crop improvement approach through adjusting the growth habit of cotton.

Zero-Material Cost Production of Soil-Coated Fabrics with Underwater Superoleophobicity for Antifouling Oil/Water Separation.

Soil-coated fabrics were fabricated by scrape-coating of soil slurry onto cotton fabrics. The raw materials, soil, and cotton fabrics were, respectively, obtained from farmland and waste bed sheets, making the method a zero-material cost way to produce superwetting membrane. The superhydrophilic/underwater superoleophobic soil-coated fabrics exhibit high efficiency (>99%), ultra-high flux (~45,000 L m-2 h-1), and excellent antifouling behavior for separating water from various oils driven by gravity. The simple fabrication and superior performance suggest that the soil-coated fabric could be a promising candidate as a filtration membrane for practical applications in industrial oily wastewater and oil spill treatments.

Synthesis of a Sm3+-doped YGa1.5Al1.5(BO3)4 phosphor via a mechanical activation-assisted solid-state reaction.

A Sm3+-doped YGa1.5Al1.5(BO3)4 (abbreviated as YGAB) phosphor was synthesized via a solid-state reaction with mechanical activation assistance in a high-energy density stirred bead mill. The samples were characterized by laser particle size analysis, specific surface area analysis, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and fluorescence spectroscopy. In addition, the photoluminescence characteristics, luminescence decay, thermal stability, and LED application of the phosphors were also investigated. The results show that the mechanical activation of mixed raw materials before calcination can reduce the particle size and the activation energy of crystallization, resulting in the formation of the YGAB crystal phase at a lower calcination temperature. The mechanical activation in grinding can accelerate the subsequent solid-phase reaction, make Sm3+ ions more easily diffuse into the YGAB lattice, and improve the crystal structure of the synthesized phosphor, thus enhancing the optical properties of the phosphor. According to the photoluminescence emission (PL) and excitation (PLE) spectra, Sm3+ doped in the YGAB lattice can provide an efficient emission under 405 nm excitation. The optimum doping concentration of Sm3+ ions is 0.03 mol%. The optimum photoluminescence intensity, quantum yield, and fluorescence lifetime of the phosphor synthesized from mixed raw materials ground for 45 min can be obtained. The temperature-dependent PL spectra show that the emission intensity of the YGAB:0.03Sm3+ phosphor at 425 K is 84.7% of its initial intensity at room temperature. It is indicated that the YGAB:0.03Sm3+ phosphor synthesized could be used as one of the promising LED lighting materials.

Clay-Coated Meshes with Superhydrophilicity and Underwater Superoleophobicity for Highly Efficient Oil/Water Separation.

A novel clay-coated mesh was fabricated via a simple brush-coating method without the use of special equipment, chemical reagents, and complex chemical reactions and operation processes. Possessing superhydrophilicity and underwater superoleophobicity, the clay-coated mesh can be used for efficiently separating various light oil/water mixtures. The clay-coated mesh also exhibits excellent reusability, maintaining a high separation efficiency of 99.4% after 30 repeated separations of the kerosene/water mixture.

Nitrogen-doped porous carbon encapsulates multivalent cobalt-nickel as oxygen reduction reaction catalyst for zinc-air battery.

In this study, we present a bimetallic ion coexistence encapsulation strategy employing hexadecyl trimethyl ammonium bromide (CTAB) as a mediator to anchor cobalt-nickel (CoNi) bimetals in nitrogen-doped porous carbon cubic nanoboxes (CoNi@NC). The fully encapsulated and uniformly dispersed CoNi nanoparticles with the improved density of active sites help to accelerate the oxygen reduction reaction (ORR) kinetics and provide an efficient charge/mass transport environment. Zinc-air battery (ZAB) equipped CoNi@NC as cathode exhibits an open-circuit voltage of 1.45 V, a specific capacity of 870.0 mAh g-1, and a power density of 168.8 mW cm-2. Moreover, the two CoNi@NC-based ZABs in series display a stable discharge specific capacity of 783.0 mAh g-1, as well as a large peak power density of 387.9 mW cm-2. This work provides an effective way to tune the dispersion of nanoparticles to boost active sites in nitrogen-doped carbon structure, and enhance the ORR activity of bimetallic catalysts.

Inspiraling streams of enriched gas observed around a massive galaxy 11 billion years ago.

Stars form in galaxies, from gas that has been accreted from the intergalactic medium. Simulations have shown that recycling of gas-the reaccretion of gas that was previously ejected from a galaxy-could sustain star formation in the early Universe. We observe the gas surrounding a massive galaxy at redshift 2.3 and detect emission lines from neutral hydrogen, helium, and ionized carbon that extend 100 kiloparsecs from the galaxy. The kinematics of this circumgalactic gas is consistent with an inspiraling stream. The carbon abundance indicates that the gas had already been enriched with elements heavier than helium, previously ejected from a galaxy. We interpret the results as evidence of gas recycling during high-redshift galaxy assembly.

Template-Sacrificing Synthesis of Ni-Co Layered Double Hydroxides Polyhedron as Advanced Anode for Lithium Ions Battery.

The novel hollowed Ni-Co layered double hydroxide polyhedron (H-(Ni, Co)-LDHP) is synthesized via a template-sacrificing approach using ZIF-67 as template. The morphology, crystallinity, porous texture, and chemical state of H-(Ni, Co)-LDHP are examined. It demonstrates that the H-(Ni, Co)-LDHP not only provides rich redox sites but also promotes the kinetics due to presence of numerous rational channels. As a result, the H-(Ni, Co)-LDHP manifests the desirable lithium ions storage performance when employed as anode. This study paves a new way for preparing hollowed nanostructure toward advanced electrochemical applications.

A Retrotransposon Insertion in GhMML3_D12 Is Likely Responsible for the Lintless Locus li3 of Tetraploid Cotton.

Cotton (Gossypium) seed fibers can be divided into lint (long) or fuzz (very short). Using fiberless (fuzzless-lintless) mutants, the lint initiation gene Li3 was identified by map-based cloning. The gene is an R2R3-MYB transcription factor located on chromosome D12 (GhMML3_D12). Sequence analysis revealed that li3 is a loss-of-function allele containing a retrotransposon insertion in the second exon that completely blocks the gene's expression. The genetic loci n2 and n3 underlying the recessive fuzzless phenotype in Gossypium hirsutum were also mapped. The genomic location of n3 overlapped with that of the dominant fuzzless locus N1 , and n3 appeared to be a loss-of-function allele caused by a single nucleotide polymorphism (SNP) mutation in the coding region of GhMML3_A12. The n2 allele was found to be co-located with li3 and originated from G. babardense. n2 and li3 are possibly the multiple alleles of the GhMML3_D12 gene. Genetic analysis showed that Li3 and N3 are a pair of homologs with additive effects for the initiation of fibers (fuzz or lint). In addition, the presence of another locus was speculated, and it appeared to show an inhibitory effect on the expression of GhMML3. These findings provide new information about the genetic factors affecting the initiation of fibers in cotton.

Open-Bud Duplicate Loci Are Identified as MML10s, Orthologs of MIXTA-Like Genes on Homologous Chromosomes of Allotetraploid Cotton.

The open-bud (ob) mutants in cotton display abnormal flower buds with the stigma and upper anthers exposed before blooming. This characteristic is potentially useful for the efficient production of hybrid seeds. The recessive inheritance pattern of the ob phenotype in allotetraploid cotton is determined by duplicated recessive loci (ob1ob1ob2ob2). In this study, ob1, which is a MIXTA-like MYB gene on chromosome D13 (MML10_Dt), was identified by map-based cloning. In Gossypium barbadense (Gb) acc. 3-79, a single nucleotide polymorphism (SNP) (G/A) at the splice site of the first intron and an 8-bp deletion in the third exon of MML10_Dt were found, which are the causative mutations at the ob1 loci. A 1783-bp deletion that leads to the loss of the third exon and accounts for the causal variation at the ob2 loci was found in MML10_At of Gossypium hirsutum (Gh) acc. TM-1. The ob phenotype results from the combination of these two loss-of-function loci. Genotyping assays showed that the ob1 and ob2 loci appeared after the formation of allotetraploid cotton and were specific for Gb and Gh, respectively. All Gb lines and most Gh cultivars carry the single corresponding mutant alleles. Genome-wide transcriptome analysis showed that some of the MYB genes and genes related to cell wall biogenesis, trichome differentiation, cytokinin signal transduction, and cell division were repressed in the ob mutants, which may lead to suppression of petal growth. These findings should be of value for breeding superior ob lines in cotton.

Different divergence events for three pairs of PEBPs in Gossypium as implied by evolutionary analysis.

INTRODUCTION: The phosphatidylethanolamine-binding protein (PEBP) gene family plays a crucial role in seed germination, reproductive transformation, and other important developmental processes in plants, but its distribution in Gossypium genomes or species, evolutionary properties, and the fates of multiple duplicated genes remain unclear. OBJECTIVES: The primary objectives of this study were to elucidate the distribution and characteristics of PEBP genes in Gossypium, as well as the evolutionary pattern of duplication and deletion, and functional differentiation of PEBPs in plants. METHODS: Using the PEBP protein sequences in Arabidopsis thaliana as queries, blast alignment was carried out for the identification of PEBP genes in four sequenced cotton species. Using the primers designed according to the PEBP genome sequences, PEBP genes were cloned from 15 representative genomes of Gossypium genus, and the gene structure, CDS sequence, protein sequence and properties were predicted and phylogenetic analysis was performed. Taking PEBP proteins of grape as reference, grouping of orthologous gene, analysis of phylogeny and divergence of PEBPs in nine species were conducted to reconstruct the evolutionary pattern of PEBP genes in plants. RESULTS: We identified and cloned 160 PEBPs from 15 cotton species, and the phylogenetic analysis showed that the genes could be classified into the following three subfamilies: MFT-like, FT-like and TFL1-like. There were eight single orthologous group (OG) members in each diploid and 16 double OG members in each tetraploid. An analysis of the expression and selective pressure indicated that expression divergence and strong purification selection within the same OG presented in the PEBP gene family. CONCLUSION: An evolutionary pattern of duplication and deletion of the PEBP family in the evolutionary history of Gossypium was suggested, and three pairs of genes resulted from different whole-genome duplication events.