ABSTRACT
The High Energy (HE) X-ray telescope on board the Hard X-ray Modulation Telescope (Insight-HXMT) can serve as a wide field of view (FOV) gamma-ray monitor with high time resolution (μs) and ...large effective area (up to thousands cm2). We developed a pipeline to search for gamma-ray bursts (GRBs), using the traditional signal-to-noise ratio (SNR) method for blind search and the coherent search method for targeted search. By taking into account the location and spectrum of the burst and the detector response, the targeted coherent search is more powerful to unveil weak and sub-threshold bursts, especially those in temporal coincidence with gravitational wave (GW) events. Based on the original method in literature, we further improved the coherent search to filter out false triggers caused by spikes in light curves, which are commonly seen in gamma-ray instruments (e.g. Fermi/GBM, POLAR). We show that our improved targeted coherent search method could eliminate almost all false triggers caused by spikes. Based on the first two years of Insight-HXMT/HE data, our targeted search recovered 40 GRBs, which were detected by either Swift/BAT or Fermi/GBM but too weak to be found in our blind search. With this coherent search pipeline, the GRB detection sensitivity of Insight-HXMT/HE is increased to about 1.5E-08 erg cm−2 (200 keV–3 MeV). We also used this targeted coherent method to search Insight-HXMT/HE data for electromagnetic counterparts of LIGO-Virgo GW events (including O2 and O3a runs). However, we did not find any significant burst associated with GW events.
CoCrFeNi and CoCrFeNiAl0.3 high entropy alloys reinforced with in-situ oxide nanoparticles have been successfully fabricated by mechanical milling in combination with hot pressing and hot extrusion. ...The as-fabricated CoCrFeNi samples exhibited an ultrafine grained microstructure with in-situ Cr2O3 oxide nanoparticles formed during hot pressing and extrusion process and distributed both on grain boundaries and in grain interiors. Increasing extrusion temperature from 1000 to 1100 °C caused a significantly increase of grain size from 700 nm to 2.5 μm owing to recrystallization and growth of the recrystallized grains, as well as the coarsening of Cr2O3 nanoparticles with their mean size increasing from 57 to 140 nm. When adding Al elements, finer Al2O3 nanoparticles (mean size: 30 nm) formed in the CoCrFeNiAl0.3 high entropy alloy, leading to refinement of the grains (mean size: 504 nm) due to their pinning effect on grain boundary immigration. After T6 heat treatment, the CoCrFeNiAl0.3 high entropy alloy demonstrated improved mechanical properties with yield strength of 1335 MPa, ultimate tensile strength of 1346 MPa and an elongation to fracture of 7.9%. With quantitative analysis based on the current models, it was concluded that grain boundary strengthening and Orowan strengthening acted as the dominant strengthening mechanisms.
Aims: To investigate the effect of medium compositions and culture conditions on keratinase production by a novel thermophilic fungus Myceliophthora thermophila (Apinis) Oorschot strain ...GZUIFR‐H49‐1.
Methods and Results: The thermophilic strain GZUIFR‐H49‐1 with keratinolytic ability was characterized and identified as a strain of M. thermophila on the basis of its morphological characters and molecular analysis of ITS1‐5.8S‐ITS2 rDNA sequence. Among the medium compositions tested, the soluble starch (SS), urea, sodium thiosulfate and CaCl2 were the most effective C‐source, N‐source, S‐source and mineral ion, respectively, by employing the single‐factor experiment. The urea and pH value were the significant factors (P < 0·05) for the keratinase production in this experiment condition using Plackett–Burman factorial design. The conditions of keratinase production were further optimized by Box–Behnken design. Consequently, there was a 6·4‐fold increase (5100 U l−1) in the keratinase activity than the initial value (800 U l−1) by this optimal process.
Conclusions: This study indicated that the optimization design proved a useful and powerful tool for the development of optimal medium compositions and culture conditions. Myceliophthora thermophila strain GZUIFR‐H49‐1 was a promising fungus strain for keratinase production.
Significance and Impact of the Study: This study characterized a novel thermophilic M. thermophila strain GZUIFR‐H49‐1 with potential applications for keratinase production. These conditions of keratinase production obtained by means of optimization design will be accumulated as potential information for exploration and utilization to the new fungus isolate.
The β-decay half-lives of neutron-rich nuclei with 20≤Z≤50 are systematically investigated using the newly developed fully self-consistent proton–neutron quasiparticle random phase approximation ...(QRPA), based on the spherical relativistic Hartree–Fock–Bogoliubov (RHFB) framework. Available data are reproduced by including an isospin-dependent proton–neutron pairing interaction in the isoscalar channel of the RHFB+QRPA model. With the calculated β-decay half-lives of neutron-rich nuclei a remarkable speeding up of r-matter flow is predicted. This leads to enhanced r-process abundances of elements with A≳140, an important result for the understanding of the origin of heavy elements in the universe.
In this study, (TaxSm1-x)0.04Ti0·96O2 (x = 0, 0.1, 0.4, 0.5, 0.6, 1.0; TSTO) were prepared via a standard solid state reaction method. The ceramics with x = 0.5 show the tetragonal rutile titanium ...dioxide structure, while ceramics with other components present the impurity phase. Notably, compared with x = 0.5 sample, the co-doped ceramics with more Sm3+ or Ta5+ show higher dielectric constant and lower dielectric loss at room temperature, which could be attributed to the formation of grain-boundary segregation. Moreover, the optimum ceramic, (Ta0.1Sm0.9)0.04Ti0·96O2, has the dielectric constant of 1.8 × 105 with relative low dielectric loss and of 0.03 at room temperature and 1 kHz. The excessive doping of Ta5+ or Sm3+ can both improve the dielectric properties, which has developed a new idea for the research of giant dielectric ceramics. The colossal dielectric properties could be explained by the internal barrier layer capacitance (IBLC) model.
An 8‐week feeding trial followed by an acute combined stress of low‐salinity and nitrite were designed to examine the effects of Rhodiola rosea on growth, body composition and antioxidant capacity of ...the white shrimp Litopenaeus vannamei. Shrimp (3.60 ± 0.03 g) were randomly allocated to 4 groups, with 3 replicates per group and 30 shrimp per replicate. The dietary groups were given as follows: control and diets containing R. rosea (300, 1000 and 3000 mg kg−1). Antioxidant capacity including total antioxidant status (TAS), activities of superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px), catalase (CAT) as well as gene expression of GSH‐Px and CAT in hepatopancreas of shrimp was analysed at the end of feeding trial and again during the combined stress. The results showed that supplemental R. rosea had no significant impacts on growth and whole body composition of shrimp. There was significant effect of R. rosea supplementation dose and times on the antioxidant status parameters of L. vannamei. R. rosea (3000 mg kg−1) significantly improved the resistance of L. vannamei against the combined stress of low‐salinity and nitrite, as indicated by the significant higher activities of TAS, GSH‐Px and CAT (P < 0.05), as well as by the higher transcript levels of GPx and CAT gene (P < 0.05).
As one of the most promising first wall/blanket structure materials in fusion reactors, oxide dispersion strengthened (ODS) ferritic steel has been extensively studied in past decades. The grain size ...of ODS steels is often between 200 and 1000 nm, called ultrafine-grained (UFG). Refining their grain size, if possible, should further enhance their radiation tolerance. In the present work, we report on a novel zirconium-doped nanocrystalline (NC) 14YWTZ ODS steel composed of a ferritic matrix with an average grain size of 50 nm and high-density oxide nanoprecipitates with an average diameter of 3.3 nm. Both NC and UFG 14YWT ODS steels were irradiated with helium ions at 450 °C. Abnormal lattice shrinking and narrowing of X-ray diffraction peaks are found in irradiated NC ODS steel. The NC ODS steel has an extremely high sink strength of ∼ 3 × 1016 m−2, which is mainly contributed by grain boundaries and effectively inhibits the aggregation of He atoms and the growth of He bubbles. The bubble size, void swelling, and irradiation hardening in NC ODS steel irradiated at a high dose, when compared to those in UFG ODS steel, are significantly smaller. The underlying mechanisms for the high irradiation tolerance in the NC ODS steel are discussed. This work provides an approach to further enhancing the radiation resistance of conventional UFG ODS steels by refining their grain size to nanoscale dimensions.
The study focused on the processing how to obtain nanoscale bainite for improving mechanical properties of a low-carbon-medium-manganese steel with nominal chemical composition of ...Fe–0.07C–7.9Mn–0.14Si–0.05Al–0.002S–0.003P (wt%), using warm rolling, intercritical annealing and bainite transformation. The results indicated that, after bainitic hold at 330 °C for 2 h, the steel had a yield stress (σy) of 770 MPa and tensile stress (σTS) of 1130 MPa, with a high elongation-to-failure (ɛf) of 0.62 at strain rate of 1 × 10−3 s−1. The product of σTS and ɛf was high at 70 GPa %, which is twice that the value (30 GPa %) required for third generation advanced high-strength steels. Furthermore, it is remarkably higher than the reported value of 46 GPa% for steel with identical chemical composition. Microstructural observations indicated that the steel consisted of nanoscale lamellae with characteristics of radial arrangement of bainitic ferrite and retained austenite (RA) of average thickness of ~120 nm. The volume fraction of RA was as high as 32% with carbon concentration of 1.75 wt%. The bainitic isothermal temperature and time not only affected the bainite morphology but also the volume fraction, distribution, microstructure and carbon concentration of RA, which are responsible for superior combination of high strength and good ductility of the steel.
A phylogeny is a tree-based model of common ancestry that is an indispensable tool for studying biological variation. Phylogenies play a special role in the study of rapidly evolving populations such ...as viruses, where the proliferation of lineages is constantly being shaped by the mode of virus transmission, by adaptation to immune systems, and by patterns of human migration and contact. These processes may leave an imprint on the shapes of virus phylogenies that can be extracted for comparative study; however, tree shapes are intrinsically difficult to quantify. Here we present a comprehensive study of phylogenies reconstructed from 38 different RNA viruses from 12 taxonomic families that are associated with human pathologies. To accomplish this, we have developed a new procedure for studying phylogenetic tree shapes based on the 'kernel trick', a technique that maps complex objects into a statistically convenient space. We show that our kernel method outperforms nine different tree balance statistics at correctly classifying phylogenies that were simulated under different evolutionary scenarios. Using the kernel method, we observe patterns in the distribution of RNA virus phylogenies in this space that reflect modes of transmission and pathogenesis. For example, viruses that can establish persistent chronic infections (such as HIV and hepatitis C virus) form a distinct cluster. Although the visibly 'star-like' shape characteristic of trees from these viruses has been well-documented, we show that established methods for quantifying tree shape fail to distinguish these trees from those of other viruses. The kernel approach presented here potentially represents an important new tool for characterizing the evolution and epidemiology of RNA viruses.
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